TY - THES A1 - Ehlers, Christoph T1 - Top-k Semantic Caching N2 - The subject of this thesis is the intelligent caching of top-k queries in an environment with high latency and low throughput. In such an environment, caching can be used to reduce network traffic and improve response time. Slow database connections of mobile devices and to databases, which have been offshored, are practical use cases. A semantic cache is a query-based cache that caches query results and maintains their semantic description. It reuses partial matches of previous query results. Each query that is processed by the semantic cache is split into two disjoint parts: one that can be completely answered with tuples of the cache probe query, and another that requires tuples to be transferred from the server (remainder query). Existing semantic caches do not support top-k queries, i.e., ordered and limited queries. In this thesis, we present an innovative semantic cache that naturally supports top-k queries. The support of top-k queries in a semantic cache has considerable effects on cache elements, operations on cache elements -- like creation, difference, intersection, and union -- and query answering. Hence, we introduce new techniques for cache management and query processing. They enable the semantic cache to become a true top-k semantic cache. In addition, we have developed a new algorithm that can estimate the lower bounds of query results of sorted queries using multidimensional histograms. Using this algorithm, our top-k semantic cache is able to pipeline partial query results of top-k queries. Thereby, query execution performance can be significantly increased. We have implemented a prototype of a top-k semantic cache called IQCache (Intelligent Query Cache). An extensive and thorough evaluation with various benchmarks using our prototype demonstrates the applicability and performance of top-k semantic caching in practice. The experiments prove that the top-k semantic cache invariably outperforms simple hash-based caching strategies and scales very well. KW - Database KW - Caching KW - Semantic Caching KW - Top-k KW - Mobile KW - Semantisches Caching KW - Abfrageverarbeitung Y1 - 2015 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:739-opus4-3055 ER - TY - THES A1 - Braun, Bastian T1 - Web-based Secure Application Control N2 - The world wide web today serves as a distributed application platform. Its origins, however, go back to a simple delivery network for static hypertexts. The legacy from these days can still be observed in the communication protocol used by increasingly sophisticated clients and applications. This thesis identifies the actual security requirements of modern web applications and shows that HTTP does not fit them: user and application authentication, message integrity and confidentiality, control-flow integrity, and application-to-application authorization. We explore the other protocols in the web stack and work out why they can not fill the gap. Our analysis shows that the underlying problem is the connectionless property of HTTP. However, history shows that a fresh start with web communication is far from realistic. As a consequence, we come up with approaches that contribute to meet the identified requirements. We first present impersonation attack vectors that begin before the actual user authentication, i.e. when secure web interaction and authentication seem to be unnecessary. Session fixation attacks exploit a responsibility mismatch between the web developer and the used web application framework. We describe and compare three countermeasures on different implementation levels: on the source code level, on the framework level, and on the network level as a reverse proxy. Then, we explain how the authentication credentials that are transmitted for the user login, i.e. the password, and for session tracking, i.e. the session cookie, can be complemented by browser-stored and user-based secrets respectively. This way, an attacker can not hijack user accounts only by phishing the user's password because an additional browser-based secret is required for login. Also, the class of well-known session hijacking attacks is mitigated because a secret only known by the user must be provided in order to perform critical actions. In the next step, we explore alternative approaches to static authentication credentials. Our approach implements a trusted UI and a mutually authenticated session using signatures as a means to authenticate requests. This way, it establishes a trusted path between the user and the web application without exchanging reusable authentication credentials. As a downside, this approach requires support on the client side and on the server side in order to provide maximum protection. Another approach avoids client-side support but can not implement a trusted UI and is thus susceptible to phishing and clickjacking attacks. Our approaches described so far increase the security level of all web communication at all time. This is why we investigate adaptive security policies that fit the actual risk instead of permanently restricting all kinds of communication including non-critical requests. We develop a smart browser extension that detects when the user is authenticated on a website meaning that she can be impersonated because all requests carry her identity proof. Uncritical communication, however, is released from restrictions to enable all intended web features. Finally, we focus on attacks targeting a web application's control-flow integrity. We explain them thoroughly, check whether current web application frameworks provide means for protection, and implement two approaches to protect web applications: The first approach is an extension for a web application framework and provides protection based on its configuration by checking all requests for policy conformity. The second approach generates its own policies ad hoc based on the observed web traffic and assuming that regular users only click on links and buttons and fill forms but do not craft requests to protected resources. N2 - Das heutige World Wide Web ist eine verteilte Plattform für Anwendungen aller Art: von einfachen Webseiten über Online Banking, E-Mail, multimediale Unterhaltung bis hin zu intelligenten vernetzten Häusern und Städten. Seine Ursprünge liegen allerdings in einem einfachen Netzwerk zur Übermittlung statischer Inhalte auf der Basis von Hypertexten. Diese Ursprünge lassen sich noch immer im verwendeten Kommunikationsprotokoll HTTP identifizieren. In dieser Arbeit untersuchen wir die Sicherheitsanforderungen moderner Web-Anwendungen und zeigen, dass HTTP diese Anforderungen nicht erfüllen kann. Zu diesen Anforderungen gehören die Authentifikation von Benutzern und Anwendungen, die Integrität und Vertraulichkeit von Nachrichten, Kontrollflussintegrität und die gegenseitige Autorisierung von Anwendungen. Wir untersuchen die Web-Protokolle auf den unteren Netzwerk-Schichten und zeigen, dass auch sie nicht die Sicherheitsanforderungen erfüllen können. Unsere Analyse zeigt, dass das grundlegende Problem in der Verbindungslosigkeit von HTTP zu finden ist. Allerdings hat die Geschichte gezeigt, dass ein Neustart mit einem verbesserten Protokoll keine Option für ein gewachsenes System wie das World Wide Web ist. Aus diesem Grund beschäftigt sich diese Arbeit mit unseren Beiträgen zu sicherer Web-Kommunikation auf der Basis des existierenden verbindungslosen HTTP. Wir beginnen mit der Beschreibung von Session Fixation-Angriffen, die bereits vor der eigentlichen Anmeldung des Benutzers an der Web-Anwendung beginnen und im Erfolgsfall die temporäre Übernahme des Benutzerkontos erlauben. Wir präsentieren drei Gegenmaßnahmen, die je nach Eingriffsmöglichkeiten in die Web-Anwendung umgesetzt werden können. Als nächstes gehen wir auf das Problem ein, dass Zugangsdaten im WWW sowohl zwischen den Teilnehmern zu Authentifikationszwecken kommuniziert werden als auch für jeden, der Kenntnis dieser Daten erlangt, wiederverwendbar sind. Unsere Ansätze binden das Benutzerpasswort an ein im Browser gespeichertes Authentifikationsmerkmal und das sog. Session-Cookie an ein Geheimnis, das nur dem Benutzer und der Web-Anwendung bekannt ist. Auf diese Weise kann ein Angreifer weder ein gestohlenes Passwort noch ein Session-Cookie allein zum Zugriff auf das Benutzerkonto verwenden. Darauffolgend beschreiben wir ein Authentifikationsprotokoll, das vollständig auf die Übermittlung geheimer Zugangsdaten verzichtet. Unser Ansatz implementiert eine vertrauenswürdige Benutzeroberfläche und wirkt so gegen die Manipulation derselben in herkömmlichen Browsern. Während die bisherigen Ansätze die Sicherheit jeglicher Web-Kommunikation erhöhen, widmen wir uns der Frage, inwiefern ein intelligenter Browser den Benutzer - wenn nötig - vor Angriffen bewahren kann und - wenn möglich - eine ungehinderte Kommunikation ermöglichen kann. Damit trägt unser Ansatz zur Akzeptanz von Sicherheitslösungen bei, die ansonsten regelmäßig als lästige Einschränkungen empfunden werden. Schließlich legen wir den Fokus auf die Kontrollflussintegrität von Web-Anwendungen. Bösartige Benutzer können den Zustand von Anwendungen durch speziell präparierte Folgen von Anfragen in ihrem Sinne manipulieren. Unsere Ansätze filtern Benutzeranfragen, die von der Anwendung nicht erwartet wurden, und lassen nur solche Anfragen passieren, die von der Anwendung ordnungsgemäß verarbeitet werden können. KW - Computersicherheit KW - Datensicherung KW - Internet Y1 - 2015 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:739-opus4-3048 ER - TY - THES A1 - Tran, Nguyen Khanh Linh T1 - Kaehler Differential Algebras for 0-Dimensional Schemes and Applications N2 - The aim of this dissertation is to investigate Kaehler differential algebras and their Hilbert functions for 0-dimensional schemes in P^n. First we give relations between Kaehler differential 1-forms of fat point schemes and another fat point schemes. Then we determine the Hilbert polynomial and give a sharp bound for the regularity index of the module of Kaehler differential m-forms, for 05%) better results than all other publicly available disambiguation algorithms on 7 of 9 datasets without data set specific tuning. Moreover, we discuss the influence of the quality of the knowledge base on the disambiguation accuracy and indicate that our algorithm achieves better results than non-publicly available state-of-the-art algorithms. KW - Entity Linking KW - Entity Disambiguation KW - Neuronal Networks KW - Embeddings Y1 - 2016 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:739-opus4-3704 ER - TY - BOOK A1 - Wehner, Stefanie ED - Wehner, Stefanie ED - Kurfürst, Sandra T1 - Southeast Asian Transformations N2 - Southeast Asia is one of the most dynamic regions in the world. This volume offers a timely approach to Southeast Asian Studies, covering recent transitions in the realms of urbanism, rural development, politics, and media. While most of the contributions deal with the era of post-independence, some tackle the colonial period and the resulting developments. The volume also includes insights from Southern India. As a tribute to the interdisciplinary project of Southeast Asian Studies, this book brings together authors from disciplines as diverse as area studies, sociology, history, geography, and journalism. KW - Südostasien KW - sozialer Wandel Y1 - 2020 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:739-opus4-10406 SN - 978-3-8394-5171-7 PB - Transcript CY - Bielefeld ER - TY - THES A1 - Beierl, Stefan T1 - Public Works Programmes: Review of their effectiveness and empirical essays on their contribution to climate resilience and social cohesion N2 - Poverty, underemployment, lack of infrastructure, low agricultural productivity, degradation of natural resources, climate change, and eroding social cohesion are among the biggest challenges that many low and lower-middle income countries are facing. Objectives linked to addressing these pressing challenges have been ascribed to public works programmes (PWPs). These are social protection instruments which offer remuneration (in cash or kind) for vulnerable people in exchange for temporary work on labour-intensive low-skill activities with social benefits. PWPs are being implemented in around two out of three developing countries. Given the substantial amounts spent on PWPs, it is critical to know to what extent the expectations towards them are backed by evidence. This dissertation sheds light on this overarching question with three self-contained essays. The first essay synthesises the evidence from PWPs in Sub-Saharan Africa, guided by three questions: First, what can we infer from the available impact evaluations regarding the effectiveness of PWPs as a social protection instrument? Second, what do we know about the role of the wage vector, asset vector, and skills vector in this respect? Third, what can we infer about the role of design features in explaining differences in outcomes? The other two essays use empirical evidence from Malawi to address more specific questions regarding the potential of PWPs to strengthen climate resilience and the relationship between PWPs and social cohesion. What sets the evidence synthesis in my first essay apart from existing reviews of PWPs is that it accounts for their heterogeneity by systematically differentiating results by PWP type and outcome area (income, consumption and expenditures, labour supply, food security, nutrition, asset holdings, agricultural production and techniques, and education). Programmes that offer short-term ad-hoc employment (Type 1) are distinguished from programmes that offer more predictable employment over longer periods (Type 2). For the review of impacts, this paper relies solely on (quasi-)experimental studies, but for the analysis of the role of design factors also on other literature. In line with existing reviews, my results suggest that Type 1 programmes can effectively enable consumption smoothing in the wake of acute crises, whereas in contexts of chronic poverty, Type 2 programmes perform, on balance, better. Offering complementary access to extension services in Type 2 programmes can boost impacts further. However, in all cases, evidence is too scant and mixed to safely conclude whether the higher benefits of costlier PWP types justify the cost premium. The second essay investigates the potential of PWPs to strengthen climate resilience. Among the main social protection instruments, the biggest potential to strengthen climate resilience is often ascribed to PWPs if they create climate-smart community assets and transfer knowledge of climate-smart practices. Yet, there is a lack of evidence whether design changes to this end can indeed enhance the contribution of an existing PWP to climate resilience. I use a difference-in-differences approach based on two-period panel data to analyse how a modified PWP model performs compared to the standard model of Malawi’s largest PWP after 24 months. The key modification is to embed public works in a communal watershed management plan with a strong emphasis on collective action and capacity building. I find that the modified approach considerably increased communal watershed management activities through voluntary labour contributions on top of the paid public works labour. While this increase was mainly driven by PWP participants, non-participants also made substantial contributions. I also find a small increase in the adoption of soil and water conservation practices on respondents’ private land, especially by non-PWP participants. These findings imply that such modest changes can make PWPs climate-smarter. In particular, they can broaden the engagement in and adoption of climate-smart activities beyond the group of PWP participants. The co-authored third essay investigates the relationship between Malawi’s MASAF PWP and social cohesion, specifically within-community cooperation for the common good. Like the existing studies, we face the challenge that neither the assignment of the programme to communities nor the selection of individual participants is randomised. We try to mitigate the endogeneity concerns by triangulating fixed effects panel analyses for a set of outcomes and sectors using two datasets with different units of analysis (households and communities). We find that public works are positively associated with coordination activities and voluntary (unpaid) contributions to public goods, along both vertical ties (between community members and local leaders) and horizontal ties (among community members). Especially for school-building activities, voluntary inputs in the form of labour and other in-kind contributions are higher in the presence of the public works programme. Our results contribute to a better understanding of the link between social protection programmes with community-driven features and social cohesion. Overall, the findings of the three essays in this dissertation contribute to the knowledge base regarding effectiveness and potential of PWPs across a broad range of outcome areas. Specifically, they offer new insights how to harness the potential of PWP to strengthen climate resilience and into the seemingly positive relationship between PWPs and social cohesion. The findings can help researchers and policy makers who are interested specifically in PWPs or in any of the many objectives that can be pursued through PWPs. KW - Public Works KW - Social Protection KW - Social cohesion KW - Review KW - Climate resilience Y1 - 2022 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:739-opus4-10491 ER - TY - JOUR A1 - Augsten, Pauline A1 - Glassner, Sebastian A1 - Rall, Jenni T1 - The Myth of Responsibility: Colonial Cruelties and Silence in German Political Discourse JF - Global Studies Quarterly N2 - Germany is considered a role model for dealing with past mass atrocities. In particular, the social reappraisal of the Holocaust is emblematic of this. However, when considering the genocide on the Herero and Nama in present-day Namibia, it is puzzling that an official recognition was only pronounced after almost 120 years, in May 2021. For a long time, silence surrounded this colonial cruelty in German political discourse. Although the discourse on German responsibility toward Namibia emerged after the end of World War II, it initially appeared detached from the genocide. That silence on colonial atrocities is to be considered a cruelty itself. Studies on silence have been expanding and becoming richer. Building on these works, the paper sets two goals: First, it advances the theorization of silence by producing a new typology, which is then integrated into discourse-bound identity theory. Second, it applies this theory to the analysis of the silencing and later acknowledging of the genocide on the Herero and Nama by German political elites. To this end, Bundestag debates, official documents, and statements by relevant political actors are analyzed in the period from 1980 to 2021. The results reveal the dynamics between hegemonic and counter-hegemonic discursive formations, how those are shifting in a period of 40 years, and what role silence plays in it. Beyond our emphasis on the genocide on the Herero and Nama, our findings might benefit future studies as the approach proposed in this paper can make silence a tangible research object for global studies. Y1 - 2022 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:739-opus4-10437 SP - 1 EP - 12 ER - TY - JOUR A1 - Caspari-Sadeghi, Sima T1 - Applying Learning Analytics in Online Environments: Measuring Learners’ Engagement Unobtrusively JF - Frontiers in Education N2 - Prior to the emergence of Big Data and technologies such as Learning Analytics (LA), classroom research focused mainly on measuring learning outcomes of a small sample through tests. Research on online environments shows that learners’ engagement is a critical precondition for successful learning and lack of engagement is associated with failure and dropout. LA helps instructors to track, measure and visualize students’ online behavior and use such digital traces to improve instruction and provide individualized support, i.e., feedback. This paper examines 1) metrics or indicators of learners’ engagement as extracted and displayed by LA, 2) their relationship with academic achievement and performance, and 3) some freely available LA tools for instructors and their usability. The paper concludes with making recommendations for practice and further research by considering challenges associated with using LA in classrooms. Y1 - 2022 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:739-opus4-10440 SP - 1 EP - 6 ER - TY - THES A1 - Alshawish, Ali T1 - Risk-based Security Management in Critical Infrastructure Organizations N2 - Critical infrastructure and contemporary business organizations are experiencing an ongoing paradigm shift of business towards more collaboration and agility. On the one hand, this shift seeks to enhance business efficiency, coordinate large-scale distribution operations, and manage complex supply chains. But, on the other hand, it makes traditional security practices such as firewalls and other perimeter defenses insufficient. Therefore, concerns over risks like terrorism, crime, and business revenue loss increasingly impose the need for enhancing and managing security within the boundaries of these systems so that unwanted incidents (e.g., potential intrusions) can still be detected with higher probabilities. To this end, critical infrastructure organizations step up their efforts to investigate new possibilities for actively engaging in situational awareness practices to ensure a high level of persistent monitoring as well as on-site observation. Compliance with security standards is necessary to ensure that organizations meet regulatory requirements mostly shaped by a set of best practices. Nevertheless, it does not necessarily result in a coherent security strategy that considers the different aims and practical constraints of each organization. In this regard, there is an increasingly growing demand for risk-based security management approaches that enable critical infrastructures to focus their efforts on mitigating the risks to which they are exposed. Broadly speaking, security management involves the identification, assessment, and evaluation of long-term (or overall) objectives and interests as well as the means of achieving them. Due to the critical role of such systems, their decision-makers tend to enhance the system resilience against very unpleasant outcomes and severe consequences. That is, they seek to avoid decision options associated with likely extreme risks in the first place. Practically speaking, this risk attitude can significantly influence the decision-making process in such critical organizations. Towards incorporating the aversion to extreme risks into security management decisions, this thesis investigates thoroughly the capabilities of a recently emerged theory of games with payoffs that are probability distributions. Unlike traditional optimization techniques, this theory provides an alternative decision technique that is more robust to extreme risks and uncertainty. Furthermore, this thesis proposes a new method that gives a decision maker more control over the decision-making process through defining loss regions with different importance levels according to people's risk attitudes. In this way, the static decision analysis used in the distribution-valued games is transformed into a dynamic process to adapt to different subjective risk attitudes or account for future changes in the decision caused by a learning process or other changes in the context. Throughout their different parts, this thesis shows how theoretical models, simulation, and risk assessment models can be combined into practical solutions. In this context, it deals with three facets of security management: allocating limited security resources, prioritizing security actions, and tweaking decision making. Finally, the author discusses experiences and limitations distilled from this research and from investigating the new theory of games, which can be taken into account in future approaches. KW - Security Management KW - Game Theory KW - Critical Infrastructures KW - Risk Attitude KW - Uncertainty KW - Spieltheorie KW - Risikomanagement Y1 - 2021 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:739-opus4-10026 ER - TY - THES A1 - Luck, Nathalie T1 - Transformation towards a more sustainable agricultural system in Indonesia: Empirical essays on the role of information and endorsement N2 - In many cases, transitioning towards sustainable agricultural production requires farmers to change their practices. These changes can include the adoption of sustainable agricultural practices, water-saving, or the disadoption of excessive chemical input use or land burning. Policy makers interested in making agricultural production more sustainable need to understand what encourages the uptake of sustainable practices and what is effective in reducing unsustainable practices. This thesis seeks to understand whether and how information provision and endorsement can contribute to the transition towards more sustainable agricultural systems. The thesis consists of three self-contained papers. The first paper explores the potential of religious endorsement for inducing pro-environmental behaviour and encouraging the disadoption of fire as an agricultural practice, thereby preventing forest fires. The paper analyses the impact of a fatwa (an Islamic religious ruling) on reducing fire incidence in Indonesia. Results indicate that fire incidence decreased in Muslim majority villages following the issuing of the fatwa. For the post-fatwa period from August 2016 to December 2019, the average monthly effect amounts to around 2.2 prevented fire events per village. This is a considerable effect. The paper concludes that fire prevention efforts, and potentially other environmental conservation efforts, could benefit significantly from support by religious institutions and stakeholders. The second paper investigates the role of information provision and training for the adoption of organic farming practices in Java, Indonesia. We use a randomised controlled trial (RCT) to identify the impact of a three-day hands-on training in organic farming for smallholder farmers. We find that the training intervention increased the adoption of organic inputs and had a positive and statistically significant effect on farmers’ knowledge and perceptions of organic farming. Overall, our findings suggest that information constraints are a barrier to the adoption of organic farming, as information provision increased the use of organic farming practices. The third paper investigates whether urban and suburban Indonesian consumers are willing to pay a price premium for organic food. We use an incentive-compatible auction based on the Becker-DeGroot-Marschak (BDM) approach to elicit consumers’ WTP. We further study the effect of income and a randomised information treatment about the benefits of organic food on respondents’ WTP. Estimates suggest that consumers are willing to pay a price premium for organic rice, on average 20 percent more than what they paid for conventional rice outside of our experiment. However, our results also indicate that raising consumers’ WTP further is complex. Showing participants a video about the health or, alternatively, environmental benefits of organic food was not effective in further raising WTP. Exposure to the environmental benefits video was, however, effective in raising stated organic food consumption intentions. KW - technology adoption, religion, organic farming, WTP KW - Landwirtschaft KW - Nachhaltigkeit KW - Entwicklungsökonomie Y1 - 2021 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:739-opus4-10037 ER - TY - JOUR A1 - Maletzky de García, Martina T1 - Bridging the state and market logics of refugee labour market inclusion – a comparative study on the inclusion activities of German professional chambers JF - Comparative Migration Studies N2 - Due to their high numbers, refugees’ labour market inclusion has become an important topic for Germany in recent years. Because of a lack of research on meso-level actors’ influences on labour market inclusion and the transcendent role of organizations in modern societies, the article focuses on the German professional chambers’ role in the process of refugee inclusion. The study shows that professional chambers are intermediaries between economic actors, the government and refugees, which all follow their own logics and ideas of labour market inclusion (the state, the market and the community logic). The measures taken by professional chambers mainly reflect a governmental logic (to reduce refugee unemployment) combined with a market logic (to provide human resources to economic actors). A community logic (altruism) only comes into play as a rather unintended consequence of measures addressing the other two logics. The measures of two types of professional chambers are compared. Close similarities between them reveal that the organization type is of theoretical relevance to explain the type of measures organizations opt for. Y1 - 2021 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:101:1-2021100821553693088701 ER - TY - JOUR A1 - Fritsch, Markus T1 - Data for modeling nitrogen dioxide concentration levels across Germany JF - Data in Brief N2 - The described secondary data provide a comprehensive basis for modeling conditional mean nitrogen dioxide (NO2) concentration levels across Germany. Besides concentration levels, meta data on monitoring sites from the German air quality monitoring network, geocoordinates, altitudes, and data on land use and road lengths for different types of roads are provided. The data are based on a grid of resolution 1 × 1 km, which is also included. The underlying raw data are open access and were retrieved from different sources. The statistical software R was used for (pre-)processing the data and all codes are provided in an online repository. The data were employed for modeling mean annual NO2 concentration levels in the paper "Agglomeration and infrastructure effects in land use regression models for air pollution - Specification, estimation, and interpretations" by Fritsch and Behm (2021). KW - Air pollution; Corine land cover; EEA air quality data; Nitrogen dioxide Y1 - 2021 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:739-opus4-10086 ER - TY - THES A1 - Csizmadia, Bence T1 - The EUrope of Differentiated Territorial Integration? Regional Cross-Border Governance in the Multi-Level Governance System of the EU. A Case Study of the EUSALP and the EUSDR N2 - Netzwerke der Regional Cross-Border Governance haben in der EU insbesondere in den vergangenen zwei Jahrzehnten einen spürbaren Bedeutungszuwachs erfahren. Sie stellen hochkomplexe Governancestrukturen dar und bieten für beteiligte Akteure einen großen Mehrwert. Die EUSDR und EUSALP sind eine weitere Fortentwicklung von RCBG und können in verschiedenen Bereichen nachweisbare Erfolge vorweisen, werden jedoch der hohen im Vorfeld postulierten Erwartungshaltung nicht gerecht. RCBG-Netzwerke und insbesondere die Makroregionalen Strategien tragen in gewisser Weise zu einer territorialen Differenzierung der EU bei, diese sind jedoch noch weit davon entfernt, dass die zum Teil postulierte Erwartungshaltung bezüglich einer „(Makro-)Regionalisierung der EU“ erfüllt wird. KW - Multi-Level-Governance KW - Regional Cross-Border Governance KW - EUSALP KW - EUSDR KW - Macro-regional strategies KW - EUSDR KW - EUSALP KW - Regionalentwicklung Y1 - 2021 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:739-opus4-9959 ER - TY - THES A1 - Silva, Vivian dos Santos T1 - A Composite Syntactic-Semantic Interpretable Text Entailment Approach Exploring Commonsense Knowledge Graphs N2 - Natural Language Processing has an important role in Artificial Intelligence for easing human-machine interaction. Processing human language, though, poses many challenges, among which is the semantics-related phenomenon known as language variability, the fact that the same thing can be said in several ways. NLP applications' inputs and outputs can be expressed in different forms, whose equivalence can be verified through inference. The textual entailment paradigm was established to enable the creation of a unifying framework for applied inference, providing a means of delivering other NLP task from handling inference issues in an ad-hoc manner, using instead the outputs of an inference-dedicated mechanism. Text entailment, the task of determining whether a piece of text logically follows from another piece of text, involves different scenarios, which can range from a simple syntactic variation to more complex semantic relationships between sentences. However, most approaches try a one-size-fits-all solution that usually favors some scenario to the detriment of another. The commonsense world knowledge necessary to support more complex inferences is also usually employed in a limited way, with most approaches sticking to shallow semantic information, leaving more elaborate semantic relationships aside. Furthermore, most systems still work as a "black box", providing a yes/no answer that does not explain the underlying reasoning process. This thesis aims at addressing these issues by proposing a composite interpretable approach for recognizing text entailment where the entailment pair is analyzed so the most relevant phenomenon is detected and the suitable method can be used to solve it. Syntactic variations are dealt with through the analysis of the sentences' syntactic structures, and semantic relationships are detected with the aid of a knowledge graph built from natural language dictionary definitions. Also, if a semantic matching is involved, the answer is made interpretable through the generation of natural language justifications that explain the semantic relationship between the pieces of text. The result is the XTE - Explainable Text Entailment - a system that outperforms well-established tools based on single-technique entailment algorithms, and that also gives an important step towards Explainable AI, allowing the inference model interpretation, making the semantic reasoning process explicit and understandable. KW - Textual Entailment KW - Knowledge Graph KW - Semantic Interpretability Y1 - 2022 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:739-opus4-10706 ER - TY - THES A1 - Opris, Andre T1 - Holomorphic Extensions in the Structure R_{an,exp} N2 - In this thesis we consider real analytic functions, i.e. functions which can be described locally as convergent power series and ask the following: Which real analytic functions definable in R_{an,exp} have a holomorphic extension which is again definable in R_{an,exp}? Finding a holomorphic extension is of course not difficult simply by power series expansion. The difficulty is to construct it in a definably way. We will not answer the question above completely, but introduce a large non trivial class of definable functions in R_{an,exp} where for example functions which are iterated compositions from either side of globally subanalytic functions and the global logarithm are contained. We call them restricted log-exp-analytic. After giving some preliminary results like preparation theorems and Tamm's Theorem for this class of functions we are able to show that real analytic restricted log-exp-analytic functions have a holomorphic extension which is again restricted log-exp-analytic. KW - O-Minimality KW - Preparation Theorems KW - Restricted Log-Exp-Analytic Functions KW - Complexification KW - Tamm's Theorem KW - O-Minimalität Y1 - 2022 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:739-opus4-10691 ER - TY - THES A1 - Schmid, Josef T1 - Learning-Based Quality of Service Prediction in Cellular Vehicle Communication N2 - Network communication has become a part of everyday life, and the interconnection among devices and people will increase even more in the future. A new area where this development is on the rise is the field of connected vehicles. It is especially useful for automated vehicles in order to connect the vehicles with other road users or cloud services. In particular for the latter it is beneficial to establish a mobile network connection, as it is already widely used and no additional infrastructure is needed. With the use of network communication, certain requirements come along. One of them is the reliability of the connection. Certain Quality of Service (QoS) parameters need to be met. In case of degraded QoS, according to the SAE level specification, a downgrade of the automated system can be required, which may lead to a takeover maneuver, in which control is returned back to the driver. Since such a handover takes time, prediction is necessary to forecast the network quality for the next few seconds. Prediction of QoS parameters, especially in terms of Throughput (TP) and Latency (LA), is still a challenging task, as the wireless transmission properties of a moving mobile network connection are undergoing fluctuation. In this thesis, a new approach for prediction Network Quality Parameters (NQPs) on Transmission Control Protocol (TCP) level is presented. It combines the knowledge of the environment with the low level parameters of the mobile network. The aim of this work is to perform a comprehensive study of various models including both Location Smoothing (LS) grid maps and Learning Based (LB) regression ones. Moreover, the possibility of using the location independence of a model as well as suitability for automated driving is evaluated. N2 - Netzwerkkommunikation ist zu einem Teil des täglichen Lebens geworden, und die Vernetzung von Geräten und Menschen wird in Zukunft noch weiter zunehmen. Ein neuer Bereich, in dem diese Entwicklung zunimmt, sind vernetzte Fahrzeuge. Es ist vorteilhaft automatisierte Fahrzeuge mit anderen Verkehrsteilnehmern oder Cloud-Diensten zu verbinden. Insbesondere für letztere ist der Einsatz einer mobilen Netzwerkverbindung zweckmäßig, da sie bereits weit verbreitet ist und keine zusätzliche Infrastruktur erfordert. Mit der Nutzung des Netzwerkes gehen auch einige Anforderungen einher. Die Zuverlässigkeit der Verbindung ist entscheidend. Kann keine ausreichende Qualität der Verbindung erfüllt werden kann nach SAE Spezifikation das Herunterstufen der Automatisierungsstufe erforderlich sein. In letzter Konsequenz kann diese schließlich zu einem Übernahmemanöver führen, wobei die Kontrolle wieder an den Fahrer zurückgegeben wird. Da ein solcher Wechsel Zeit in Anspruch nimmt, ist eine Vorhersage erforderlich, um die Netzqualität in den nächsten Sekunden zu prognostizieren. Eine solche Vorhersage der Dienstgüte (Quality of Service (QoS)), besonders hinsichtlich Durchsatz und Latenz, nach wie vor eine recht anspruchsvolle Aufgabe, da die drahtlosen Übertragungseigenschaften einer sich bewegenden mobilen Netzwerkverbindung großen Schwankungen unterliegen. In dieser Dissertation wird ein neuer Ansatz für die Vorhersage von Network Quality Parameters (NQPs) auf der Ebene des Transmission Control Protocol (TCP) vorgestellt. Er kombiniert das Wissen der Umgebung mit den Parametern des Mobilfunknetzes. Das Ziel dieser Arbeit ist eine umfangreiche Untersuchung verschiedener Modelle, darunter sind sowohl Lokalisationsglättende Kachel-Karten wie auch Regressionsverfahren aus dem Bereich des Maschinellen Lernens. Darüber hinaus wird dessen die Möglichkeit der Nutzung der Ortsunabhängigkeit eines Modells erörtert sowie Eignung für automatisiertes Fahren evaluiert. Y1 - 2022 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:739-opus4-10772 ER - TY - THES A1 - Koçer, Volkan T1 - Three Essays on Global and Local Brands N2 - In three essays, this dissertation examines the past, present and future of branding in an international context, contributing to the research area of global/local brands, while also offering managers valuable insights for their branding strategies. The first essay provides scholars and practitioners a detailed state of the art of global/local brand research and proposes promising angles for future research, especially considering major challenges for our societies. The second essay incorporates the segment of cosmopolitan consumers into perceived brand globalness/localness research. Theoretically grounded in the concepts of social identity theory and complexity, the essay builds on perceived brand globalness/localness to analyze how cosmopolitans arrange both their global and local orientations. Aside offering scholars a new theoretical lens regarding consumer cosmopolitanism, managers can benefit from the gained insights, if cosmopolitans are a particular target group in their business strategy. The third and final essay meta-analytically investigates how the variables perceived brand globalness and localness materialize on various key outcome variables. At heart of this essay is a comparison of both perceived brand globalness and localness, offering scholars and practitioners valuable empirical insights on similarities and differences between their effects on outcomes such as brand quality. KW - global brands KW - local brands KW - perceived brand globalness KW - perceived brand localness KW - international marketing Y1 - 2022 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:739-opus4-10722 ER - TY - THES A1 - Murawski, Lena T1 - Essays on current topics in employee entrepreneurial behaviors and attitudes N2 - A firm's entrepreneurial orientation (EO) is its propensity to act proactively, innovate, take risks, and engage in competitive and autonomous behaviors. Prior research shows that EO is an im-portant factor for new ventures to overcome barriers to survival and fostering growth, measured by annual sales and employment growth rates. In particular, individual-level EO (IEO) is an important driver of a firm’s EO. The firm’s ability to exploit opportunities appearing in the mar-ket and to achieve superior performance depends on the employees’ skills and experiences to act and think entrepreneurially. The main objective of this dissertation is to investigate how and when employees engage in entrepreneurial behaviors at work. Building on three essays, this dissertation takes an interdisciplinary approach to employee entrepreneurial behaviors in new ventures, encompassing both entrepreneurship and gamification research. The first main contri-bution proposed in this field is a more nuanced understanding of how employee entrepreneurial behaviors help young firms cope with growth-related, organization-transforming challenges (i.e., changes in organizational culture that accompany growth, the introduction of hierarchical structures, and the formalization of processes). When new ventures grow, employees’ IEO tends to manifest in introducing technological innovations and business improvements rather than in actions related to risk-taking. Second, this dissertation reveals the relevance of self-efficacy for entrepreneurial behaviors and explores how gamification can enhance employee entrepreneurial behaviors in new ventures. Based on these findings, this dissertation contributes to EO research by highlighting the role of IEO as a building block for EO pervasiveness. This research further develops our knowledge on the use of gamification in new ventures. This cu-mulative dissertation is structured as follows. Part A is an introduction to the study of entrepre-neurial behaviors. Part B contains the three essays.  KW - Entrepreneurial behaviors, gamification, entrepreneurial orientation, start-up, new venture, start-up growth Y1 - 2022 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:739-opus4-10740 ER - TY - THES A1 - Niklaus, Christina T1 - From Complex Sentences to a Formal Semantic Representation using Syntactic Text Simplification and Open Information Extraction N2 - Sentences that present a complex linguistic structure act as a major stumbling block for Natural Language Processing (NLP) applications whose predictive quality deteriorates with sentence length and complexity. The task of Text Simplification (TS) may remedy this situation. It aims to modify sentences in order to make them easier to process, using a set of rewriting operations, such as reordering, deletion or splitting. These transformations are executed with the objective of converting the input into a simplified output, while preserving its main idea and keeping it grammatically sound. State-of-the-art syntactic TS approaches suffer from two major drawbacks: first, they follow a very conservative approach in that they tend to retain the input rather than transforming it, and second, they ignore the cohesive nature of texts, where context spread across clauses or sentences is needed to infer the true meaning of a statement. To address these problems, we present a discourse-aware TS framework that is able to split and rephrase complex English sentences within the semantic context in which they occur. By generating a fine-grained output with a simple canonical structure that is easy to analyze by downstream applications, we tackle the first issue. For this purpose, we decompose a source sentence into smaller units by using a linguistically grounded transformation stage. The result is a set of selfcontained propositions, with each of them presenting a minimal semantic unit. To address the second concern, we suggest not only to split the input into isolated sentences, but to also incorporate the semantic context in the form of hierarchical structures and semantic relationships between the split propositions. In that way, we generate a semantic hierarchy of minimal propositions that benefits downstream Open Information Extraction (IE) tasks. To function well, the TS approach that we propose requires syntactically well-formed input sentences. It targets generalpurpose texts in English, such as newswire or Wikipedia articles, which commonly contain a high proportion of complex assertions. In a second step, we present a method that allows state-of-the-art Open IE systems to leverage the semantic hierarchy of simplified sentences created by our discourseaware TS approach in constructing a lightweight semantic representation of complex assertions in the form of semantically typed predicate-argument structures. In that way, important contextual information of the extracted relations is preserved that allows for a proper interpretation of the output. Thus, we address the problem of extracting incomplete, uninformative or incoherent relational tuples that is commonly to be observed in existing Open IE approaches. Moreover, assuming that shorter sentences with a more regular structure are easier to process, the extraction of relational tuples is facilitated, leading to a higher coverage and accuracy of the extracted relations when operating on the simplified sentences. Aside from taking advantage of the semantic hierarchy of minimal propositions in existing Open IE Abstract approaches, we also develop an Open IE reference system, Graphene. It implements a relation extraction pattern upon the simplified sentences. The framework we propose is evaluated within our reference TS implementation DisSim. In a comparative analysis, we demonstrate that our approach outperforms the state of the art in structural TS both in an automatic and a manual analysis. It obtains the highest score on three simplification datasets from two different domains with regard to SAMSA (0.67, 0.57, 0.54), a recently proposed metric targeted at automatically measuring the syntactic complexity of sentences which highly correlates with human judgments on structural simplicity and grammaticality. These findings are supported by the ratings from the human evaluation, which indicate that our baseline implementation DisSim returns fine-grained simplified sentences that achieve a high level of syntactic correctness and largely preserve the meaning of the input. Furthermore, a comparative analysis with the annotations contained in the RST Discourse Treebank (RST-DT) reveals that we are able to capture the contextual hierarchy between the split sentences with a precision of approximately 90% and reach an average precision of almost 70% for the classification of the rhetorical relations that hold between them. Finally, an extrinsic evaluation shows that when applying our TS framework as a pre-processing step, the performance of state-ofthe-art Open IE systems can be improved by up to 32% in precision and 30% in recall of the extracted relational tuples. Accordingly, we can conclude that our proposed discourse-aware TS approach succeeds in transforming sentences that present a complex linguistic structure into a sequence of simplified sentences that are to a large extent grammatically correct, represent atomic semantic units and preserve the meaning of the input. Moreover, the evaluation provides sufficient evidence that our framework is able to establish a semantic hierarchy between the split sentences, generating a fine-grained representation of complex assertions in the form of hierarchically ordered and semantically interconnected propositions. Finally, we demonstrate that state-of-the-art Open IE systems benefit from using our TS approach as a pre-processing step by increasing both the accuracy and coverage of the extracted relational tuples for the majority of the Open IE approaches under consideration. In addition, we outline that the semantic hierarchy of simplified sentences can be leveraged to enrich the output of existing Open IE systems with additional meta information, thus transforming the shallow semantic representation of state-of-the-art approaches into a canonical context-preserving representation of relational tuples. KW - Text Simplification KW - Syntactic Simplification KW - Open Information Extraction KW - Semantic Representation KW - Complex Sentences Y1 - 2022 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:739-opus4-10540 ER - TY - THES A1 - Lenz, Luciane T1 - The diffusion of modern energy technologies in low-income settings - evidence from rural sub-Saharan Africa N2 - This collection of three chapters responds to today’s energy challenges. It explores innovative policy aimed to equip the energy poor with access to improved cooking energy and electricity, looking both at the demand and supply side of modern energy technologies. Concretely, it discusses mechanisms to increase uptake of off-grid solar electricity in rural Rwanda based on experimental demand measurements (Chapter 1), it studies how to diffuse improved cooking technologies in rural Senegal via supply-side mechanisms (Chapter 2), and it identifies the need to target cooking technologies in consideration of the broader household context in rural Senegal and beyond (Chapter 3). KW - Technology adoption KW - Energy access KW - Rural development KW - Subsaharisches Afrika KW - Armut KW - Energietechnik KW - Erneuerbare Energien Y1 - 2022 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:739-opus4-10550 ER - TY - THES A1 - Mandarawi, Waseem T1 - Multi-objective Network Virtualization and its Applicability to Industrial Networks N2 - Network virtualization provides high flexibility for deploying communication services in dense and heterogeneous environments. Two main approaches (dimensions) that are usually combined exist: Network Function Virtualization (NFV) technologies for functionality virtualization and Virtual Network Embedding (VNE) algorithms for resource virtualization. These approaches can be applied to different network levels, such as factory and enterprise levels of industrial networks. Several objectives and constraints, that might be conflicting, shall be considered when network virtualization is applied, mainly in complex topologies. This thesis proposes a network virtualization model that considers both virtualization dimensions, two network levels, and different objectives and constraints. The network levels considered are two primary levels in industrial networks. However, this consideration does not restrict the model to a particular environment or certain levels. The considered objectivities/constraints are topology, reliability, security, performance, and resource usage. Based on this model, we first build an overall combined solution for autonomic and composite virtual networking. This solution considers both virtualization dimensions, two network levels, and target objectives. Furthermore, this solution combines three novel virtualization sub-approaches that consider performance, reliability, and performance. However, the sub-approaches apply to different combinations of levels and dimensions, and the reliability approach additionally considers the resource usage objective. After presenting all solutions, we map them to the defined model. Regarding applicability to industrial networks, the combined approach is applied to an enterprise-level Industrial Internet of Things (IIoT) use case inspired by the smart factory concept in Industry 4.0. However, the sub-approaches are applied to more specific use cases. The performance and reliability solutions are integrated with relevant components of the Time Sensitive Networks (TSN) standard as a modern technology for industrial networks. The goal is to enrich the reliability and performance capabilities of TSN with the flexibility of network virtualization. In the combined approach, we compose and embed an environment-aware Extended Virtual Network (EVN) that represents the physical devices, virtual application functions, and required Service Function Chains (SFCs). We use the graph transformation method to transform abstract application requirements (represented by an Application Request (AR)) into an EVN. Both EVN composition and embedding methods consider the Substrate Network (SN) topology and different security, reliability, performance, and resource usage policies. These policies are applied with a certain priority and depend on the properties of communicating entities such as location and type. The EVN is embedded using property-based node mapping, reliability-aware branching, and a greedy chain embedding heuristic. The chain embedding heuristic is evaluated using a random topology that represents the use case. The performance sub-approach is NFV-based and is applied to a specific use case with Time-critical Traffic (TCT) flows. We develop and evaluate a complete framework for virtualizing Time-aware Shaper (TAS) using high-performance NFV. The reliability sub-approach is VNE-based and is applied to a specific factory level use case. We develop minimal and maximal branching heuristics based on a reliability-aware k-shortest path algorithm and compare them using a typical factory topology. We then integrate these algorithms with a Frame Replication and Elimination for Reliability (FRER) simulator to realize reliability policies by the autonomic and efficient configuration of a supporting technology. The security sub-approaches are related to both virtualization dimensions and are applied to generic enterprise-level use cases. However, the applicability of the security aspect to industrial networks is only shown in the combined (EVN) approach and its use case. We research the autonomic security management in Network Function Virtualization Infrastructure (NFVI) with the main goal of early reaction to threats through SFC reconfiguration through Virtual Network Function (VNF) live migration. This goal is approached by supporting the security measurements with a decision making architecture that considers, on the one hand, the threats and events in the environment and, on the other hand, the Service Level Agreement (SLA) between the NFVI provider and user. For this purpose, we classify the VNF-specific attacks and define possible early detectable behavior patterns. Finally, we develop a security-aware VNE heuristic that considers the security requirements of the Virtual Network (VN) and the security capabilities of the SN. This approach is modified in the combined approach to consider deploying virtualized security VNFs. KW - Network Virtualization KW - Industrial Networks KW - Virtual Network Embedding KW - Network Function Virtualization KW - Time Sensitive Networking Y1 - 2022 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:739-opus4-10606 ER - TY - THES A1 - Behm, Svenia T1 - Four essays on statistical modelling of environmental data N2 - This dissertation deals with geostatistical, time series, and regression analytical approaches for modelling spatio-temporal processes, using air quality data in the applications. The work is structured into four essays the abstracts of which are given in the following. The first essay is titled 'Spatial detrending revisited: Modelling local trend patterns in NO2-concentration in Belgium and Germany'. It is written in co-authorship by Prof. Dr. Harry Haupt and Dr. Angelika Schmid and published in 2018 in Spatial Statistics 28, pp. 331-351 (https://doi.org/10.1016/j.spasta.2018.04.004). Abstract Short-term predictions of air pollution require spatial modelling of trends, heterogeneities, and dependencies. Two-step methods allow real-time computations by separating spatial detrending and spatial extrapolation into two steps. Existing methods discuss trend models for specific environments and require specification search. Given more complex environments, specification search gets complicated by potential nonlinearities and heterogeneities. This research embeds a nonparametric trend modelling approach in real-time two-step methods. Form and complexity of trends are allowed to vary across heterogeneous environments. The proposed method avoids ad hoc specifications and potential generated predictor problems in previous contributions. Examining Belgian and German air quality and land use data, local trend patterns are investigated in a data driven way and are compared to results computed with existing methods and variations thereof. An important aspect of our empirical illustration is the heterogeneity and superior performance of local trend patterns for both research regions. The findings suggest that a nonparametric spatial trend modelling approach is a valuable tool for real-time predictions of pollution variables: it avoids specification search, provides useful exploratory insights and reduces computational costs. The second essay is titled 'Predictability of hourly nitrogen dioxide concentration'. It is written in co-authorship with Prof. Dr. Harry Haupt and published in 2020 in Ecological Modelling 428, 109076 (https://doi.org/10.1016/j.ecolmodel.2020.109076). Abstract Temporal aggregation of air quality time series is typically used to investigate stylized facts of the underlying series such as multiple seasonal cycles. While aggregation reduces complexity, commonly used aggregates can suffer from non-representativeness or non-robustness. For example, definitions of specific events such as extremes are subjective and may be prone to data contaminations. The aim of this paper is to assess the predictability of hourly nitrogen dioxide concentrations and to explore how predictability depends on (i) level of temporal aggregation, (ii) hour of day, and (iii) concentration level. Exploratory tools are applied to identify structural patterns, problems related to commonly used aggregate statistics and suitable statistical modeling philosophies, capable of handling multiple seasonalities and non-stationarities. Hourly times series and subseries of daily measurements for each hour of day are used to investigate the predictability of pollutant levels for each hour of day, with prediction horizons ranging from one hour to one week ahead. Predictability is assessed by time series cross validation of a loss function based on out-of-sample prediction errors. Empirical evidence on hourly nitrogen dioxide measurements suggests that predictability strongly depends on conditions (i)-(iii) for all statistical models: for specific hours of day, models based on daily series outperform models based on hourly series, while in general predictability deteriorates with exposure level. The third essay is titled 'Agglomeration and infrastructure effects in land use regression models for air pollution – Specification, estimation, and interpretations'. It is written in co-authorship with Dr. Markus Fritsch and published in 2021 in Atmospheric Environment 253, 118337 (https://doi.org/10.1016/j.atmosenv.2021.118337). Abstract Established land use regression (LUR) techniques such as linear regression utilize extensive selection of predictors and functional form to fit a model for every data set on a given pollutant. In this paper, an alternative to established LUR modeling is employed, which uses additive regression smoothers. Predictors and functional form are selected in a data-driven way and ambiguities resulting from specification search are mitigated. The approach is illustrated with nitrogen dioxide (NO2) data from German monitoring sites using the spatial predictors longitude, latitude, altitude and structural predictors; the latter include population density, land use classes, and road traffic intensity measures. The statistical performance of LUR modeling via additive regression smoothers is contrasted with LUR modeling based on parametric polynomials. Model evaluation is based on goodness of fit, predictive performance, and a diagnostic test for remaining spatial autocorrelation in the error terms. Additionally, interpretation and counterfactual analysis for LUR modeling based on additive regression smoothers are discussed. Our results have three main implications for modeling air pollutant concentration levels: First, modeling via additive regression smoothers is supported by a specification test and exhibits superior in- and out-of-sample performance compared to modeling based on parametric polynomials. Second, different levels of prediction errors indicate that NO2 concentration levels observed at background and traffic/industrial monitoring sites stem from different processes. Third, accounting for agglomeration and infrastructure effects is important: NO2 concentration levels tend to increase around major cities, surrounding agglomeration areas, and their connecting road traffic network. The fourth essay is titled 'Outlier detection and visualisation in multi-seasonal time series and its application to hourly nitrogen dioxide concentration'. It is written in single authorship and has not been published yet. Abstract Outlier detection in data on air pollutant recordings is conducted to uncover data points that refer to either invalid measurements or valid but unusually high concentration levels. As air pollutant data is typically characterised by multiple seasonalities, the task of outlier detection is associated with the question of how to deal with such non-stationarities. The present work proposes a method that combines time series segmentation, seasonal adjustment, and standardisation of random variables. While the former two are employed to obtain subseries of homoskedastic data, the latter ensures comparability across the subseries. Further, the standardised version of the seasonally adjusted subseries represents a scaled measure for the outlyingness of each data point in the original time series from its mean and therefore forms a suitable basis for outlier detection. In an empirical application to data on hourly NO2 concentration levels recorded at a traffic monitoring site in Cologne, Germany, over the years 2016 to 2019, the common boxplot criterion is used to examine each standardised seasonally adjusted subseries for positive outliers. The results of the analyses are put into their natural temporal order and displayed in a heatmap layout that provides information on when single and sequential outliers occur. KW - Spatio-temporal modelling KW - time series analysis KW - regression KW - geostatistics KW - multiple seasonalities KW - environmental data KW - Statistik KW - Geostatistik KW - Umweltdaten Y1 - 2022 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:739-opus4-10539 ER - TY - THES A1 - Tomek, Raphaela T1 - Quiet please! - School Noise and its Effects on Student Teachers and Practicing Teachers N2 - Lärm in Schulen gilt aus unterschiedlichen Gründen als massiver Belastungsfaktor für Lehrkräfte und kann deshalb zu Leistungsdefiziten im Beruf, aber auch zu physischen und psychischen Beeinträchtigungen führen. Die Erforschung von Schullärm und seinen Auswirkungen ist daher essentiell. Die drei Studien, die in dieser Arbeit vorgestellt werden, untersuchten die unmittelbaren Auswirkungen von Lärm auf Lehramtsstudierende und die mittelbaren Auswirkungen auf praktizierende Lehrkräfte. In der ersten und zweiten Studie wurde im Rahmen zweier Experimente überprüft, wie sich Pausenlärm auf das Stresserleben, die Leistung in einem Konzentrationstest und auf die Fehlerkorrektur eines Diktats auswirkt. Auf Grundlage des transaktionalen Stressmodells (Lazarus & Folkman, 1984) wurde vermutet, dass Lärm zu einer Erhöhung des Stresserlebens führt. Der Maximal-Adaptability-Theorie (Hancock & Warm, 1989, 2003) nach sollte der Lärm zunächst eine optimale Leistung, langfristig jedoch eine Leistungsbeeinträchtigung verursachen. Um dies zu überprüfen, bearbeiteten in der ersten Studie 74 und in der zweiten Studie 104 Lehramtsstudierende der Universität Passau zwei unterschiedliche Konzentrationstests und korrigierten das Diktat eines Schülers, während sie kurzen, kontinuierlichen oder keinen Pausenlärm hörten. In beiden Experimenten führte kontinuierlicher Lärm zu einer Erhöhung des Stresserlebens. Weder kurzer noch kontinuierlicher Lärm führte zu einer Verschlechterung der Konzentrationsleistung. Weiter zeigten sich unterschiedliche Befunde: Im ersten Experiment führte ein kurzer Konzentrationstest in Kombination mit kontinuierlichem Lärm zu positiven Effekten in der Diktatkorrektur, d.h. die Versuchspersonen wiesen eine bessere Leistung in der Fehlerkorrektur auf. Im zweiten Experiment führte ein langer Konzentrationstest in Kombination mit kurzem oder kontinuierlichem Lärm zu negativen Effekten, d.h. die Probanden machten vergleichsweise mehr Fehler bei der anschließenden Diktatkorrektur. Daraus lässt sich schlussfolgern, dass Schullärm einerseits das Stresserleben erhöhen und andererseits die anschließende Leistungsfähigkeit der Lehrkräfte verbessern oder einschränken kann. Letzteres scheint allerdings von der konkreten Situation abzuhängen. Im ersten Teil der dritten Studie lag der Fokus auf den Bewältigungsstilen und dem erlebten Stress der Lehrkräfte. Da Bewältigungsstile nachweislich einen großen Einfluss auf die psychische Gesundheit haben, lag die Vermutung nahe, dass das durch Lärm verursachte Stresserleben je nach Bewältigungsstil unterschiedlich ausfällt. Auf der Grundlage des Belastungs-Beanspruchungsmodells (Rudow, 2000) und des transaktionalen Stressmodells (Lazarus & Folkman, 1984) wurde angenommen, dass Lehrkräfte mit riskanten Copingstilen mehr Stresssymptome erleben. Deshalb wurde im Rahmen einer Online-Studie untersucht, ob es in Bezug auf psychische und körperliche Symptome Unterschiede zwischen Lehrkräften mit distinkten Bewältigungsstilen gibt. Dazu wurden 99 bayerische Grund- und Mittelschullehrkräfte befragt. Aus den übergeordneten Skalen Engagement und Resilienz resultierten vier berufliche Bewältigungsstile. Der Typ Gesundheit (hohes Engagement, hohe Resilienz), der Schon-Typ (niedriges Engagement, hohe Resilienz), Typ A (hohes Engagement, niedrige Resilienz) und Typ Burnout (niedriges Engagement, niedrige Resilienz) unterschieden sich hinsichtlich Bedrohungseinschätzung, Lärmstress, Stimm- und Hörproblemen sowie lärmbedingtem Burnout. Im Vergleich zum Typ Gesundheit wiesen die Risikotypen Typ A und Typ Burnout ein höheres Stresserleben auf und erwiesen sich generell anfälliger gegenüber Schullärm als der Typ Gesundheit. Dies ist die erste Studie, die zeigen konnte, dass Schullärm besonders für Lehrkräfte mit riskanten Copingstilen eine Gefährdung darstellt. Im zweiten Teil der dritten Studie lag der Fokus auf den Wirkungspfaden von Schullärm. Hier wurden Zusammenhänge zwischen individuellen Eigenschaften der Lehrkräfte und den unterschiedlichen Auswirkungen von Schullärm vermutet. Basierend auf dem vereinfachten Modell von Lehrerstress (van Dick & Wagner, 2001) wurde an 159 bayerischen Grund- und Mittelschullehrkräften untersucht, ob Lärmstress und Stimmermüdung die Verbindung zwischen Lärmempfindlichkeit und lärmbedingtem Burnout vermitteln. Die Ergebnisse zeigten, dass Stress die Beziehung zwischen Lärmempfindlichkeit und Stimmermüdung vermittelte; Stimmermüdung vermittelte die Beziehung zwischen Lärmstress und lärmbezogenem Burnout; Lärmstress und Stimmermüdung vermittelten seriell die Beziehung zwischen Lärmempfindlichkeit und lärmbedingtem Burnout. Dies ist die erste Studie die Verbindungen zwischen lärmempfindlichen Lehrkräften und Lärmstress, Stimmproblemen und lärmbedingtem Burnout aufzeigen konnte. N2 - Noise in schools is considered a massive stress factor for teachers because of various reasons and can therefore lead to performance deficits in the job, but also to physical and psychological impairments. Consequently, research on school noise and its effects is essential. The three studies presented in this paper examined the immediate effects of noise on student teachers and the collateral effects on practicing teachers. In the first and second study, two experiments were conducted to examine the effects of noise during breaks on stress experience, performance in a concentration test, and error correction of a dictation. Based on the transactional stress model (Lazarus & Folkman, 1984), it was hypothesized that noise leads to an increase in stress experience. According to the maximal adaptability theory (Hancock & Warm, 1989, 2003), noise should initially cause optimal performance, but in the long run should cause performance impairment. For this purpose, in the first study 74 and in the second study 104 student teachers of the University of Passau worked on two different concentration tests and corrected a student’s dictation while listening to short, continuous, or no noise. In both experiments, continuous noise led to an increase in the experience of stress. Neither short nor continuous noise led to a deterioration in concentration performance. Further, different findings emerged: In the first experiment, a short concentration test in combination with continuous noise led to positive effects in dictation correction, i.e., subjects showed better performance in error correction. In the second experiment, a long concentration test combined with short or continuous noise resulted in negative effects, i.e., subjects made more errors in the subsequent correction of dictation. It can be concluded that school noise can, on the one hand, increase the experience of stress and, on the other hand, promote or limit teachers’ subsequent performance. The latest, however, seems to depend on the specific situation of the individual. In the first part of the third study, the focus was on teachers’ coping styles and experienced stress. Since coping styles have been shown to have a major impact on mental health, it was reasonable to assume that the stress experience caused by noise would vary depending on the coping style. Based on the stress-strain model (Rudow, 2000) and the transactional stress model (Lazarus & Folkman, 1984), it was hypothesized that teachers with risky coping styles experience more stress symptoms. Therefore, an online study was conducted to investigate whether there were differences in psychological and physical symptoms between teachers with different coping styles. For this purpose, 99 Bavarian elementary and middle school teachers were surveyed. Four professional coping styles resulted from the overarching scales of professional commitment and resilience. The healthy type (high commitment, high resilience), the unambitious type (low commitment, high resilience), type A (high commitment, low resilience), and type burnout (low commitment, low resilience) differed in terms of threat appraisal, noise stress, voice and hearing problems, and noise-related burnout. Compared to the healthy type, the risk types − type A and type burnout − exhibited higher stress experience and were generally more susceptible to school noise than the healthy type. This is the first study to show that school noise is particularly hazardous for teachers with risky coping styles. The second part of the third study focused on the impact pathways of school noise. Associations between teachers’ individual characteristics and the consequences of school noise were hypothesized. Based on the simplified model of teacher stress (van Dick & Wagner, 2001), we examined 159 Bavarian elementary and middle school teachers to determine whether noise stress and vocal fatigue mediate the association between noise sensitivity and noise-related burnout. Results indicated that noise stress mediated the relationship between noise sensitivity and vocal fatigue; vocal fatigue mediated the relationship between noise stress and noise-related burnout; noise stress and vocal fatigue serially mediated the relationship between noise sensitivity and noise-related burnout. This is the first study to show links between noise-sensitive teachers and noise stress, voice problems, and noise-related burnout. KW - school noise KW - teacher stress KW - student teachers KW - practicing teachers KW - performance Y1 - 2022 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:739-opus4-10626 ER - TY - THES A1 - Steudner, Tobias T1 - Understanding Consumers' Digital Data Disclosure Decision-Making: A Focus on Data Sharing Cooperations, Perceived Risks and Low-Cognitive-Effort Processing N2 - Due to the advances of digitalization, firms are able to collect more and more personal consumer data and strive to do so. Moreover, many firms nowadays have a data sharing cooperation with other firms, so consumer data is shared with third parties. Accordingly, consumers are confronted regularly with the decision whether to disclose personal data to such a data sharing cooperation (DSC). Despite privacy research has become highly important, peculiarities of such disclosure settings with a DSC between firms have been neglected until now. To address this gap is the first research objective in this thesis. Another underexplored aspect in privacy research is the impact of low-cognitive-effort decision-making. This is because the privacy calculus, the most dominant theory in privacy research, assumes for consumers a purely cognitive effortful and deliberative disclosure decision-making process. Therefore, to expand this perspective and examine the impact of low-cognitive-effort decision-making is the second research objective in this thesis. Additionally, with the third research objective, this thesis strives to unify and increase the understanding of perceived privacy risks and privacy concerns which are the two major antecedents that reduce consumers’ disclosure willingness. To this end, five studies are conducted: i) essay 1 examines and compares consumers’ privacy risk perception in a DSC disclosure setting with disclosure settings that include no DSC, ii) essay 2 examines whether in a DSC disclosure setting consumers rely more strongly on low-cognitive-effort processing for their disclosure decision, iii) essay 3 explores different consumer groups that vary in their perception of how a DSC affects their privacy risks, iv) essay 4 refines the understanding of privacy concerns and privacy risks and examines via meta-analysis the varying effect sizes of privacy concerns and privacy risks on privacy behavior depending on the applied measurement approach, v) essay 5 examines via autobiographical recall the effects of consumers’ feelings and arousal on disclosure willingness. Overall, this thesis shines light on consumers’ personal data disclosure decision-making: essay 1 shows that the perceived risk associated with a disclosure in a DSC setting is not necessarily higher than to an identical firm without DSC. Also, essay 3 indicates that only for the smallest share of consumers a DSC has a negative impact on their disclosure willingness and that one third of consumers do not intensively think about consequences for their privacy risks arising through a DSC. Additionally, essay 2 shows that a stronger reliance on low-cognitive-effort processing is prevalent in DSC disclosure settings. Moreover, essay 5 displays that even unrelated feelings of consumers can impact their disclosure willingness, but the effect direction also depends on consumers’ arousal level. This thesis contributes in three ways to theory: i) it shines light on peculiarities of DSC disclosure settings, ii) it suggests mechanisms and results of low-effort processing, and iii) it enhances the understanding of perceived privacy risks and privacy concerns as well as their resulting effect sizes. Besides theoretical contributions, this thesis offers practical implications as well: it allows firms to adjust the disclosure setting and the communication with their consumers in a way that makes them more successful in data collection. It also shows that firms do not need to be too anxious about a reduced disclosure willingness due to being part of a DSC. However, it also helps consumers themselves by showing in which circumstances they are most vulnerable to disclose personal data. That consumers become conscious of situations in which they are especially vulnerable to disclose data could serve as a countermeasure: this could prevent that consumers disclose too much data and regret it afterwards. Similarly, this thesis serves as a thought-provoking input for regulators as it emphasizes the importance of low-cognitive-effort processing for consumers’ decision-making, thus regulators may be able to consider this in the future. In sum, this thesis expands knowledge on how consumers decide whether to disclose personal data, especially in DSC settings and regarding low-cognitive-effort processing. It offers a more unified understanding for antecedents of disclosure willingness as well as for consumers’ disclosure decision-making processes. This thesis opens up new research avenues and serves as groundwork, in particular for more research on data disclosures in DSC settings. KW - Privacy KW - Disclosure KW - Dual Processing KW - Emotion KW - Privacy Concerns Y1 - 2022 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:739-opus4-10583 ER - TY - THES A1 - Alyousef, Ammar T1 - E-Mobility Management: Towards a Grid-friendly Smart Charging Solution N2 - Replacing fossil-fueled vehicles with Electric Vehicles (EVs) poses new challenges for power distribution networks. Specifically speaking, the electrification of the mobility sector relies on the ability to process and analyze information on when, where, for how long, or how fast charging processes will take place. Nevertheless, such kind of information is typically difficult to acquire or insufficiently predictable due to the dynamic nature of the system. Also, the increasing adoption rate of the renewable energy sources, specifically the domestic Photovoltaic (PV) systems, and the potentially associated grid defection scenarios will significantly impact the cost and efforts required to operate the grid in terms of power quality and demand-supply aspects. However, such emerging requirements have arguably not been taken into account when the distribution grid was built originally. Besides, expanding the distribution and transmission capacity is a very costly and lengthy process. Therefore, any proposed solution should be cost-effective as well as environment-, grid- and user-friendly. To this end, the advancements in Information and Communications Technology (ICT) are increasingly adopted and applied. This thesis addresses the rapidly growing EV sector and deals with the problems to overcome potential power quality degradation caused by the challenges mentioned above. Since time switch and radio ripple control as existing solutions in Germany are costly and neither very effective nor scalable as it requires hardware retrofitting of existing public Charging Stations (CSs), the primary focus of this work is the development of an appropriate, standards-based, scalable, and smart charging solution of EVs. Such a solution can, in turn, boost the usage of renewable energy by ensuring that the existing grid infrastructure can operate within its permissible limits while maintaining acceptable levels of power quality. This work introduces a new definition of the concept, “grid-friendly EV charging”, where the power demand of a CS is adjusted depending on the real-time status of a power grid. In this regard, the conflicting concerns of stakeholders in an EV ecosystem are considered. For example, a Distribution System Operator (DSO) does not want to reveal a lot of technical details about the power grid or its status. Similarly, a Charging Service Provider (CSP) wants to keep its clients happy without sharing the details of its business model with others, namely, DSOs. For that sake, a distributed smart charging architecture is proposed in this thesis. It is event-driven and responds in nearly real-time to unforeseen and critical grid situations such as high/low voltage, congestion, phase unbalance, and harmonics. In that regard, the publish/subscribe messaging pattern, used as a part of the architecture, enables an efficient and well-performing communication scheme among the different components. Moreover, an indication mechanism about the different issues in a power grid is developed; it adopts the traffic light model. It works as a black box to separate smart controllers for each CS and configured only by the CSP. Smart chargers enable a smooth adjustment of the charging power to avoid drastic changes in the grid state. To that end, two types of intelligent controllers are developed and tested. While the first controller is inspired by the fuzzy logic, the second one is inspired by the slow-start mechanism used in TCP to control congestion in computer networks. A simulative approach is applied to evaluate the solution, thereby, a topology of a real low voltage grid with realistic load and generation profiles is used. Furthermore, a set of metrics is defined regarding the main concerns of stakeholders: voltage, overloading, fairness, the satisfaction of EV users and grid operator, as well as the grid-friendly behavior of a CS/ EV user. The evaluation shows that the solution is able to guarantee a safe operation of the grid. The proposed system can ensure a grid-friendly charging by sacrificing of a small portion of user satisfaction, that sacrifice of a user is awarded via a points-based reward system. Last but not least, the proposed distributed controllers are compared to two other controllers: (1) a decentralized controller based only on sensing the local voltage and (2) a very strict centralized controller focusing on grid-friendliness. The latter ensures proportional fairness among users regarding the objective function of the optimization problem solved in each simulation step. The distributed controllers are superior to the decentralized controller in terms of grid friendly and fairness and converge in general to the centralized one. KW - E-Mobility KW - Smart Charging KW - Grid-Friendliness KW - Elektromobilität KW - Lademanagement KW - Netzstabilität Y1 - 2021 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:739-opus4-9302 ER - TY - THES A1 - Niedermeier, Florian T1 - Power-Adaptive Computing in Future Energy Networks N2 - The current electricity grid is undergoing major changes. There is increasing pressure to move away from power generation from fossil fuels, both due to ecological concerns and fear of dependencies on scarce natural resources. Increasing the share of decentralized generation from renewable sources is a widely accepted way to a more sustainable power infrastructure. However, this comes at the price of new challenges: generation from solar or wind power is not controllable and only forecastable with limited accuracy. To compensate for the increasing volatility in power generation, exerting control on the demand side is a promising approach. By providing flexibility on demand side, imbalances between power generation and demand may be mitigated. This work is concerned with developing methods to provide grid support on demand side while limiting the associated costs. This is done in four major steps: first, the target power curve to follow is derived taking both goals of a grid authority and costs of the respective load into account. In the following, the special case of data centers as an instance of significant loads inside a power grid are focused on more closely. Data center services are adapted in a way such as to achieve the previously derived power curve. By means of hardware power demand models, the required adaptation of hardware utilization can be derived. The possibilities of adapting software services are investigated for the special use case of live video encoding. A method to minimize quality of experience loss while reducing power demand is presented. Finally, the possibility of applying probabilistic model checking to a continuous demand-response scenario is demonstrated. KW - Power-adaptive software KW - Energy systems KW - Energieversorgung KW - Software Y1 - 2021 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:739-opus4-9993 ER - TY - THES A1 - Bongers, Franziska Maria T1 - Three essays on digital and non-digital transformations in business-to-business markets N2 - Fundamental changes in business-to-business (B2B) buying behavior confront B2B supplier firms with unprecedented challenges. On the one hand, a rising share of industrial buyers demands digitalized offerings and processes from suppliers. Consequently, suppliers are urged to implement digital transformations by expanding the range of both digital offerings and processes. On the other hand, B2B buyers increasingly expect suppliers to provide individually tailored solutions to their idiosyncratic needs. Hence, suppliers are also required to implement non-digital transformations by providing offerings and processes that are customized to each customers’ specific requirements. The rise of these digital and non-digital transformations calls established knowledge into question. Thus, B2B marketing research and practice are urged to create a comprehensive understanding of digital and non-digital transformations by means of novel and empirically grounded insights and derive actionable response strategies. In respond, my dissertation addresses the overall research question of how B2B supplier firms can successfully implement both digital and non-digital transformations in three individual essays. In Essay 1, I offer a broader perspective on both digital and non-digital transformations by investigating digital service customization (i.e., the tailoring of digital B2B services to customers’ individual needs). Through a systematic literature review and bibliometric analysis, I outline a comprehensive set of factors that favor the application of distinct digital service customization strategies. Essay 2 represents a deep dive into digital transformations of sales processes. By making use of two rich sets of qualitative interview material from supplier and buyer firms, I identify the challenges resulting for B2B salespeople from the introduction of digital sales channels into personal selling. Moreover, I uncover facilitating mechanisms that sales managers can employ to support salespeople in coping with digital sales channels. Finally, Essay 3 constitutes a deep dive into non-digital transformations. Based on qualitative interview material and survey data from matched sales manager–salesperson dyads, the essay explores how configurations of individual salespeople’s personal and procedural competencies facilitate success at selling customer solutions (i.e., highly customized, performance-oriented offerings comprising products and/or services). The essay shows that successfully selling customized offerings like solutions hinges on salespeople’s unique configurations of present and absent competencies. In a nutshell, these essays provide three major insights on how B2B suppliers can successfully implement digital and non-digital transformations. First, they underscore that a comprehensive understanding of the origins and spillover effects of transformations is a key prerequisite to successfully implementing them. Second, they unveil that digital and non-digital transformations impact on multiple organizational levels. Third, they point out important resources and capabilities that help suppliers to successfully implement transformations, be they digital or non-digital. With this dissertation, I make substantial contributions to the broader literature on digital and non-digital transformations in B2B contexts. At the same time, my dissertation provides hands-on implications for managers in B2B supplier firms that are facing fundamental transformations in the marketplace—both digital and non-digital in nature. KW - business-to-business; digitalization; customization; digital services; digital sales channels; customer solutions Y1 - 2021 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:739-opus4-9149 ER - TY - THES A1 - Ansah, Frimpong T1 - Performance and optimization technologies for software defined industrial networks N2 - The concept of programmable networks is radically changing the way communication infrastructures are designed, integrated, and operated. Currently, the topic is spearheaded by concepts such as software-defined networking, forwarding and control element separation, and network function virtualization. Notably, software-defined networking has attracted significant attention in telecommunication and data centers and thus already in some production-grade networks. Despite the prevalence of software-defined networking in these domains, industrial networks are yet to see its benefits to encourage adoption. However, the misconceptions around the concept itself, the role of virtualization, and algorithms pose a significant obstacle. Furthermore, the desire to accommodate new services in the automation industry results in a pattern of constantly increasing complexity of industrial networks, which is compounded by the requirement to provide stringent deterministic service guarantees considering characteristically different applications and thus posing a significant challenge for management, configuration, and maintenance as existing solutions are architecturally inflexible. Therefore, the first contribution of this thesis addresses the misconceptions around software-defined networking by providing a comparative analysis of programmable network concepts, detailing where software-defined networks compare with other concepts and how its principles can be leveraged to evolve industrial networks. Armed with the fundamental principles of programmable networks, the second contribution identifies virtualization technologies and proposes novel algorithms to provide varied quality of service guarantees on converged time-sensitive Ethernet networks using software-defined networking concepts. Finally, a performance analysis of a software-defined hybrid deployment solution for control and management of time-sensitive Ethernet networks that integrates proposed novel algorithms is presented as an industrial use-case that enables industrial operators to harness the full potential of time-sensitive networks. KW - Performance KW - Software Defined Industrial Networks KW - Virtual Network Embedding KW - Schedulability Analysis KW - Worst-case Delay Analysis KW - Software Defined Industrial Networks KW - Deterministic Petri-net and Queuing networks KW - Virtual Network Embedding and Worst-case Delay Analysis KW - Schedulability Analysis KW - Performance Y1 - 2021 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:739-opus4-9002 PB - Universität Passau CY - Passau ER - TY - THES A1 - Zierke, Oliver T1 - Innovation and Competition in the Digital Economy: Implications for Internet Platforms, Telecommunications Networks and Data Sharing Initiatives N2 - Governments around the world currently focus on shaping the digital economy. Particular attention is paid to Internet platforms, Internet infrastructure and data as essential components of the digital economy. The three studies in this thesis contribute to the understanding of the behavior of firms in each of these domains and derive insights for future regulations and business projects. The first study deals with the ranking of content on Internet platforms and how it affects the incentives of content providers to invest in content quality. The focus of the study is on sponsored ranking and organic ranking, but the case that a vertically integrated content provider is favored by an Internet platform is also taken into account. Using a game theoretic model, it is shown that there is no ranking design that strictly leads to more investment compared to the other designs. It is also shown that the Internet platform usually chooses the type of ranking that, from the perspective of the Internet platform and consumers, yields the best expected overall content quality. The second study deals with the incentive of Internet service providers to throttle specific Internet content. The key finding is that Internet service providers use this instrument to utilize the capacity of their telecommunications network more efficiently. This leads not only to more benefits for Internet users, but also to a higher incentive to invest in network capacity due to better monetization. The third study examines the circumstances under which firms are willing to share data with other firms. By means of an economic laboratory experiment, it is shown that more data is shared if the firms have control over who exactly they share data with. Thus, for example, data pools that grant unrestricted data access to all participating firms can be expected to perform worse than data pools that give their participating firms control over with whom their uploaded data is shared. In addition, the third study finds that established relationships are characterized by more data sharing and less volatility in the amount of shared data than new relationships. The study concludes that data sharing projects should not be expected to work optimally right away. In summary, the studies in this thesis identify a number of costs that may arise when digital firms' choice is restricted by regulation or design. The ability of Internet service providers to throttle certain content and the ability of Internet platforms to choose the ranking design are usually used in the best interests of consumers. Data sharing also works best when firms are free to decide who gets their data. KW - online platform KW - ranking algorithm KW - sponsored search KW - platform regulation KW - net neutrality Y1 - 2021 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:739-opus4-10006 ER - TY - THES A1 - Lang, Thomas T1 - AI-Supported Interactive Segmentation of 3D Volumes N2 - The segmentation of volumetric datasets, i.e., the partitioning of the data into disjoint sub-volumes with the goal to extract information about these regions,is a difficult problem and has been discussed in medical imaging for decades. Due to the ever-increasing imaging capabilities, in particular in X-ray computed tomography (CT) or magnetic resonance imaging, segmentation in industrial applications also gains interest. Especially in industrial applications the generated datasets increase in size. Hence, most applications apply well-known techniques in a 2+1-dimensional manner,i.e., they apply image segmentation procedures on each slice separately and track the progress along the axis of the volume in which the slices are stacked on. This discards the information on preceding or subsequent slices, which is often assumed to be nearly identical. However, in the industrial context this might prove wrong since industrial parts might change their appearance significantly over the course of even a few slices. Moreover, artifacts can further distort the content of the slices. Therefore, three-dimensional processing of voxel volumes has to be preferred, which induces constraints upon the segmentation procedures. For example, they must not consider global information as it is usually not feasible in big scans to compute them efficiently. Yet another frequent problem is that applications focus on individual parts only and algorithms are tailored to that case. Most prominent medical segmentation procedures do so by applying methods to specifically find the liver and only the liver of a patient, for example. The implication is that the same method then cannot be applied to find other parts of the scan and such methods have to be designed individually for any object to be segmented. Flexible segmentation methods are needed too specifically when partitioning unique scans. We define a unique scan to be a voxel dataset for which no comparable volume exists. Classical examples include the use case of cultural heritage where not only the objects themselves are unique but also scan parameters are optimized to obtain the best image quality possible for that specific scan. This thesis aims at introducing novel methods for voxelwise classifications based on local geometric features. The latter are computed from local environments around each voxel and extract information in similar ways as humans do, namely by observing their similarity to geometric or textural primitives. These features serve as the foundation to learning the proposed voxelwise classifiers and to discriminate between segmented and unsegmented voxels. On the one hand, they perform fully automated clustering of volumes for which a representative random sample is extracted first. On the other hand, a set of segmenting classifiers can be trained from few seed voxels, i.e., volume elements for which a domain expert marked if they belong to the components that shall be segmented. The interactive selection offers the advantage that no completely labeled voxel volumes are necessary and hence that unique scans of objects can be segmented for which no comparable scans exist. Overall, it will be shown that all proposed segmentation methods are effectively of linear runtime with respect to the number of voxels in the volume. Thus, voxel volumes without size restrictions can be segmented in an efficient linear pass through the volume. Finally, the segmentation performance is evaluated on selected datasets which shows that the introduced methods can achieve good results on scans from a broad variety of domains for both small and big voxel volumes. N2 - Die Segmentierung von Volumendaten, also die Partitionierung der Daten in disjunkte Teilvolumen zur weiteren Informationsextraktion, ist ein Problem, welches in der medizinischen Bildverarbeitung seit Jahrzehnten behandelt wird. Bedingt durch die sich ständig verbessernden Bilderfassungsmethoden, speziell im Bereich der Röntgen-Computertomographie (CT) oder der Magnetresonanztomographie, gewinnt die Segmentierung von industriellen Volumendaten auch an Wichtigkeit. Insbesondere im industriellen Kontext steigt die Größe der zu segmentierenden Daten jedoch rasant an, so dass sich die meisten Segmentierungsapplikationen auf den 2+1-dimensionalen Fall beschränken, also Bilder verarbeiten und die Ergebnisse über mehrere Bilder hinweg verfolgen. Jedoch werden somit beispielsweise geometrische Informationen über benachbarte Schichten ignoriert. Diese können sich aber gerade im industriellen Bereich signifikant ändern. Aus diesem Grund ist hier die dreidimensionale Bildverarbeitung vorzuziehen. Dadurch ergeben sich neue Einschränkungen, beispielsweise können keine globalen Informationen zur Segmentierung herangezogen werden, da diese typischerweise nicht effizient berechenbar sind. Ferner fokussieren sich dreidimensionale Methoden aus medizinischen Bereichen zumeist auf bestimmte Bestandteile der Daten, wie einzelne Organe. Dies schränkt die Generalität dieser Methoden signifikant ein und somit sind separate Verfahren für jedes zu segmentierende Objekt notwendig. Flexible Methoden sind darüber hinaus bei Anwendung auf einzigartige Scans erforderlich. Ein einzigartiger Scan ist ein Voxelvolumen, für welches kein vergleichbares Datum existiert. Klassische Beispiele sind Kulturgutdigitalisate, da dort nicht nur die Objekte einzigartig sind, sondern auch die Aufnahmeparameter spezifisch für diesen einen Scan optimiert wurden. Die vorliegende Dissertation führt neuartige Methoden zur voxelweisen dreidimensionalen Segmentierung von Volumendaten auf Basis lokaler geometrischer Informationen ein. Die Bewertung dieser Informationen imitiert die menschliche Objektwahrnehmung, indem lokale Regionen mit geometrischen oder strukturellen Primitiven verglichen werden. Mit Hilfe dieser Bewertungen werden voxelweise anzuwendende Klassifikatoren trainiert, welche zwischen erwünschten und unerwünschten Voxeln unterscheiden sollen. Ein Teil dieser Klassifikatoren führt eine vollautomatische Clustering-Analyse durch, nachdem eine repräsentative und zufällig ausgewählte Teilmenge fester Größe an Voxeln selektiert wurde. Die verbliebenen Segmentierungsalgorithmen erhalten Trainingsdaten in Form von Seed-Voxeln, also wenige Volumenelemente, die von einem Domänenexperten markiert wurden. Diese interaktive Herangehensweise ermöglicht das Einbringen von Expertenwissen ohne die Notwendigkeit vollständig annotierter Trainingsvolumen, wodurch auch einzigartige Scans segmentiert werden können. Für alle Verfahren wird dargelegt, dass die eingeführten Algorithmen von asymptotisch linearer Laufzeit in der Anzahl der Voxel im Volumen sind. Somit können Voxeldaten ohne Größenbeschränkungen in einem effizienten linearen Durchgang verarbeitet werden. Abschließend wird die Performanz der vorgestellten Verfahren auf ausgewählten Daten evaluiert und aufgezeigt, dass mit denselben wenigen Verfahren gute Ergebnisse auf vielen unterschiedlichen Domänen und gleichfalls auf kleinen und großen Volumen erzielt werden können. KW - Segmentation KW - Computed Tomography KW - Artificial Intelligence KW - Active Learning KW - Interactive KW - Machine learning KW - Image processing Y1 - 2021 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:739-opus4-9221 ER - TY - THES A1 - Salehi Rizi, Fatemeh T1 - Graph Representation Learning for Social Networks N2 - Online social networks provide a rich source of information about millions of users worldwide. However, due to sparsity and complex structure, analyzing these networks is quite challenging and expensive. Recently, graph embedding emerged to map networked data into low-dimensional representations, i.e. vector embeddings. These representations are fed into off-the-shelf machine learning algorithms to simplify and speed up graph analytic tasks. Given the immense importance of social network analysis, in this thesis, we aim to study graph embedding for social networks in three directions. Firstly, we focus on social networks at microscopic level to primarily encode the structural characteristic of users' personal networks so-called ego networks. These representations are utilized in evaluation tasks whose performance depends on relational information from direct neighbors. For example, social circle prediction and event attendance inference both need structural information from neighbors in social networks. Secondly, we explore assessing the content of vector embeddings in terms of topological properties. This could be explained via two proposed approaches: 1) a learning to rank algorithm in which the model weights reveal the importance of properties at subgraph level (ego networks), 2) a regression model for direct approximation of network statistical properties at vertex level. Thirdly, we propose extensions of graph embedding to capture sign or additional content of social networks. Users in social media often express their feelings and attitudes towards others which forms sentiment links besides social links. We design a joint objective function whose terms capture semantics of both social and sentiment links simultaneously. We also propose a multi-task learning framework for networks with attributes and labels by stacking autoencoders. The weights of the learning tasks are automatically assigned via an adaptive loss weighting layer. Y1 - 2021 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:739-opus4-9211 ER - TY - JOUR A1 - Basmadjian, Robert T1 - Flexibility-Based Energy and Demand Management in Data Centers BT - a Case Study for Cloud Computing JF - Energies N2 - The power demand (kW) and energy consumption (kWh) of data centers were augmenteddrastically due to the increased communication and computation needs of IT services. Leveragingdemand and energy management within data centers is a necessity. Thanks to the automated ICTinfrastructure empowered by the IoT technology, such types of management are becoming more feasiblethan ever. In this paper, we look at management from two different perspectives: (1) minimization of theoverall energy consumption and (2) reduction of peak power demand during demand-response periods.Both perspectives have a positive impact on total cost of ownership for data centers. We exhaustivelyreviewed the potential mechanisms in data centers that provided flexibilities together with flexiblecontracts such as green service level and supply-demand agreements. We extended state-of-the-artby introducing the methodological building blocks and foundations of management systems for theabove mentioned two perspectives. We validated our results by conducting experiments on a lab-gradescale cloud computing data center at the premises of HPE in Milano. The obtained results support thetheoretical model, by highlighting the excellent potential of flexible service level agreements in Green IT:33% of overall energy savings and 50% of power demand reduction during demand-response periods inthe case of data center federation. Y1 - 2019 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:739-opus4-9251 VL - 2019 IS - 12 SP - 1 EP - 22 PB - MDPI CY - Basel ER - TY - JOUR A1 - Schiffbeck, Adrian T1 - The Spiritual “Freelancers”: Young People, Religiosity and Community Problem Solving JF - SCIENTIA MORALITAS - International Journal of Multidisciplinary Research N2 - Earlier research showed that religion is related to participation among adolescents. It emphasized the effects of belonging (affiliation to groups and traditions) on community service among Western populations. This article takes one step further and focuses on religiosity as a potential motivation for community problem solving during adolescence and young adulthood, in the Eastern European Orthodox cultural setting. Data comes from several semistructured interviews with participants in a civic project conducted in the city of Timisoara (Romania). Findings indicated a low impact of the social religious component on engagement. The cognitive dimension of belief and the emotional bonding (prayer, ritual connection to the higher reality) function as indirect motivators, through the moral element of behavior. Results also showed a privatization of spiritual life at young adults (the invisible religion): estrangement from doctrines and the development of an individualistic type of morality, meant to drive volunteer activities further. Y1 - 2020 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:739-opus4-9268 VL - 2020 IS - Volume 5, no. 1 SP - 131 EP - 152 ER - TY - THES A1 - Soubeiga, Sidiki T1 - Four empirical essays on the role of institutional quality, political instability and entrepreneurship for economic growth and jobs in Sub-Saharan Africa N2 - Most Sub-Saharan African (SSA) countries experienced sound economic growth and a declining rate of poverty over the last two decades. Though, by far, the SSA region remains the poorest in the world and faces tremendous political, social, and economic challenges. Moreover, due to the COVID-19 pandemic, SSA entered into a recession with a GDP growth rate of minus 5% in 2020 as ever recorded over 25 years. This has also induced an increase in poverty in the region, which adds up to the structural challenges and further highlight the need of sound policies to address economic growth, governance, jobs, and poverty for the region to meet the Sustainable Development Goals (SDGs) in 2030 and beyond. This thesis examines the effects of institutional quality, political instability, and a government targeted entrepreneurship program on the accumulation of human, physical, and financial capital by households and firms. In the literature, these factors are identified as the key determinants of economic growth and job creation, yet this thesis contributes to a knowledge gap, especially at the microeconomic level, on how households and firms accumulate these factors in the presence of weak institutional quality, political instability, and government targeted entrepreneurship programs. In particular, this thesis investigates heterogeneity as well as a single country study of the effects of institutional quality and political instability; it also employs a randomized controlled trial (RCT) to assess the impacts of two different targeted entrepreneurship support programs; and finally, it taps on data from this field experiment to assess the performance of two different targeting mechanisms for selecting growth-oriented entrepreneurs. Each paper is self-contained and three among the four papers were written with co-authors. The first paper assesses the effects of institutional quality and political instability on household assets and human capital accumulation in 19 Sub-Saharan African countries for the period 2003-16. In this paper, the concept of instability is enlarged to include factual instability as measured by the number of political violence and civil unrest events, perceived instability as measured by the perceptions of the quality of institutions by households, and the interplay between factual and perceived instability. Contrary to most previous analyses, this paper takes into account household wealth distribution to show how the effects of political instability differ for poor vs. rich households. For identification, I exploit the variation of factual and perceived instability across 185 administrative regions in the 19 countries. My regressions control for a large range of confounding factors measured at the levels of households, regions, and countries. Overall, factual and perceived instability are associated with higher investments in assets, and factual instability is also associated with more investment in house improvements, yet it is negatively associated with the ownership of financial accounts. With regard to the heterogeneous effects, increased factual or perceived instability is associated with more investments in physical capital but less investments in financial and human capital among rich households, and with less investments in physical, financial and human capital among poor households. These findings suggest that political instability might enhance the accumulation of wealth by rich households and reduce that of poor households, implying that the detrimental effects of political instability have lasting consequences for poor households, especially when poor households are exposed to an actual or even just perceived deteriorating quality of the country’s institutions. The second paper, written with Nicolas Büttner and Michael Grimm, analyzes households’ investments in assets and their consumption, and education and health expenditures when exposed to actual instability as measured by the number of political violence and protest events in Burkina Faso. There is a large, rather macroeconomic, literature that shows that political instability and social conflict are associated with poor economic outcomes including lower investment and reduced economic growth. However, there is only very little research on the impact of instability on households’ behavior, in particular their saving and investment decisions. This paper merges six rounds of household survey data and a geo-referenced time series of politically motivated events and fatalities from the Armed Conflict Location and Event Data project (ACLED) to analyze households’ decisions when exposed to instability in Burkina Faso. For identification, the paper exploits variation in the intensity of political instability across time and space while controlling for time-effects and municipality fixed effects as well as rainfall and nighttime light intensity, and many other potential confounders. The results show a negative effect of political instability on financial savings, the accumulation of durables, investment in house improvements, as well as on investment in education and health. Instability seems, in particular, to lead to a reshuffling from investment expenditures to increased food consumption, implying lower growth prospects in the future. With respect to economic growth, the sizable education and health effects seem to be particularly worrisome. The third paper, written with Michael Grimm and Michael Weber, employs a randomized controlled trial (RCT) to assess the short-term effects of a government support program targeted at already existing and new firms located in a semi-urban area in Burkina Faso. Most support programs targeted at small firms in low- and middle-income countries fail to generate transformative effects and employment at a larger scale. Bad targeting, too little flexibility and the limited size of the support are some of the factors that are often seen as important constraints. This paper assesses the short-term effects of a randomized targeted government support program to a pool of small and medium-sized firms that have been selected based on a rigorous business plan competition (BPC). One group received large cash grants of up to US$8,000, flexible in use. A second group received cash grants of an equally important size, but earmarked to business development services (BDSs) and thus less flexible and with a required own contribution of 20%. A third group serves as a control group. All firms operate in agri-business or related activities in a semi-urban area in the Centre-Est and Centre-Sud regions of Burkina Faso. An assessment of the short-term impacts shows that beneficiaries of cash grants engage in better business practices, such as formalization and bookkeeping. They also invest more, though, this does not translate into higher profits and employment yet. Beneficiaries of cash grants and BDSs show a higher ability to innovate. The results also show that cash grants cushioned the adverse effects of the COVID-19 pandemic for the beneficiaries. More generally, this study adds to the thin literature on support programs implemented in a fragile-state context. The fourth paper, written with Michael Weber, examines the selection of entrepreneurs based on expert judgments for a BPC in Burkina Faso. To support job creation in developing countries, governments allocate significant funds to a typically small number of new or already existing micro, small, and medium-sized enterprises (MSMEs) that are growth oriented. Increasingly, these enterprises are picked through BPCs where thematic experts are asked to make the selection. So far, there exists contrasting and limited evidence on the effectiveness and efficiency of these expert judgments for screening growth-oriented entrepreneurs among contestants in BPCs. Alternative or complementary approaches such as evaluation and selection algorithms are discussed in the literature but evidence on their performance is thin. This paper uses a principal component analysis (PCA) to build a metric for comparing the performance of these alternative mechanisms for targeting entrepreneurs with high potential to grow. The results show expert subjectivity bias in judging contestant entrepreneurs. The paper finds that the scores from the expert judgment and those from the algorithm perform similarly well for picking the top-ranked or talented entrepreneurs. It also finds that both types of scores have predictive power, i.e. have statistically significantly associated with 17 firm performance outcomes measured 10 or 34 months after the BPC started. Yet, the predictive power, as measured by the magnitude of the regression coefficients, is higher for the algorithm metric, even when it is considered jointly with expert judgment scores. Despite the statistical superiority of the algorithm, expert assessments at least through pitches of entrepreneurs have proved useful in many settings where free-riding or misuse of public funds may occur. Hence, efficiency and precision could be achieved by relying on a reasoned combination of expert judgments and an algorithm for targeting growth-oriented entrepreneurs. These four papers bring new insights on the relationship between weak institutions, political instability, and targeted government support to entrepreneurship for increasing the accumulation of financial, physical, and human capital, and productivity. And these are the key factors for spurring economic growth and creating jobs in SSA. These findings suggest that efficient institutions building in SSA countries would enhance citizen perceptions of good governance which would reduce political instability and enable households including the poor to accumulate productive assets, increase their productivity and reduce poverty. The findings also suggest that targeted government entrepreneurship support programs, e.g. in the forms of cash grants with monitored disbursements yet flexible in use, can enhance firms’ human capital, productive assets, and innovations, even in the short term. Moreover, the targeting mechanism of such programs could be made more effective and efficient by relying on a combinaison of expert judgments and an algorithm for picking growth-oriented entrepreneurs. KW - Subsaharisches Afrika KW - Wirtschaftsentwicklung KW - Wirtschaftswachstum Y1 - 2022 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:739-opus4-10326 ER - TY - THES A1 - Schmid, Matthias T1 - Towards Storing 3D Model Graphs in Relational Databases N2 - The increasing relevance of massive graph data reinforces the need for adequate graph data management. While several graph database engines have been developed, the storage of graph data in a relational database management system, and therefore the seamless integration into existing information systems remains an open challenge. Motivated by the use case to integrate Building Information Modeling (BIM) data into the MonArch system, we propose a solution that transforms the BIM data into a property graph and stores this graph in the database system. We present a novel approach to efficiently store property graph data in a relational database management system using JSON functionality and redundant storage of edges in adjacency lists and show how to import huge data sets into this schema. Applying this approach, we import data sets of up to nearly 1 TB of disk space within the relational database, while only having 96 GB of main memory available. We also present a new approach of how to retrieve data from this database schema, translating queries written in the popular property graph query language Cypher into SQL. Hence, we provide an intuitive way to write semantically complex queries. We also demonstrate the efficiency of our approach using the standardized Linked Data Benchmark Council – Social Network Benchmark (LDBC - SNB) framework. Our approach increases the throughput for this benchmark by up to 85 times, compared to existing approaches for RDBMS. In addition, we propose a new method to transform BIM data into the property graph model and how to apply the aforementioned property graph storage to this data. We can import IFC models of up to 300 MB within five minutes. We show the suitability of our approach using our own use case specific benchmark, which we integrated into the previously mentioned Social Network Benchmark. For our interactive use case-specific queries, we achieve response times faster than 5 ms in 99% of all executions. Finally, we present how the aforementioned approach to store BIM data in a relational database management system is integrated into the existing MonArch system by splitting the different functionalities of our approach into a microservice architecture. N2 - Die steigende Relevanz von riesigen Graphdatenmengen verstärkt die Notwendigkeit von adäquatem Graphdaten Management. Während bereits mehrere Graphdatenbanken entwickelt wurden, bleibt die Speicherung von Graphdaten in relationalen Datenbanken und die damit verbundene nahtlose Integration in bereits existierende Informationssysteme eine ungelöste Herausforderung. Motiviert durch unseren eigenen Anwendungsfall Building Information Modeling (BIM)Daten in das MonArch Informationssystem zu integrieren, schlagen wir einen Ansatz vor, BIM Daten in eine Property Graph Form umzuwandeln und diesen in der Datenbank zu speichern. Um dies zu erreichen, stellen wir einen neuartigen Ansatz vor, um Property Graphen in einem relationalen Datenbanksystem zu speichern, indem wir Funktionalitäten wie JSON und die redundante Speicherung von Kanten in Adjazenzlisten kombinieren und zeigen wie große Mengen dieser Daten in das Schema importiert werden können. Durch die Anwendung unseres Ansatzes können wir Datensätze von bis zu 1 TB in das Datenbanksystem importieren, während wir nur 96 GB Hauptspeicher zur Verfügung haben. Wir stellen außerdem einen neuen Ansatz vor, um Daten aus dem zuvor genannten Schema abzufragen, indem wir die beliebte Graphanfragesprache Cypher in die Sprache SQL übersetzen. Dadurch erreichen wir eine intuitive Art semantisch komplexe Anfragen zu schreiben. Zusätzlich zeigen wir die Effizienz unseres Ansatzes, indem wir das standardisierte Evaluationsframework Social Network Benchmark des Linked Data Benchmar Council (LDBC – SNB) verwenden. Unser Ansatz erhöht den Durchsatz dieses Benchmarks, im Vergleich zu existierenden Ansätzen für relationale Datenbanksysteme, auf einen bis zu 85-fachen Durchsatz. Zusätzlich schlagen wir eine neue Methode vor, um BIM Daten in das Property Graph Modell zu übertragen und wie das zuvor vorgestellte Speichermodel verwendet werden kann, um diese Daten zu speichern. Damit können wir IFC Modelle mit bis zu 300 MB in unter 5 Minuten in unser System importieren. Schließlich zeigen wir die Eignung unseres Ansatzes, indem wir einen eigenen Benchmark spezifisch für unseren Anwendungsfall verwenden, welchen wir in den zuvor erwähnte Social Network Benchmark integriert haben. Für unsere anwendungsfallspezifischen Anfragen erreichen wir Antwortzeiten von unter 5 ms in 99% der Ausführungen. KW - Graph-based database models KW - Relational database model KW - Property graph KW - Industry Foundation Classes KW - IFC Store Y1 - 2022 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:739-opus4-10353 ER - TY - JOUR A1 - Haupt, Harry A1 - Fritsch, Markus ED - Rykov, Vladimir V. T1 - Quantile Trend Regression and Its Application to Central England Temperature JF - Mathematics N2 - The identification and estimation of trends in hydroclimatic time series remains an important task in applied climate research. The statistical challenge arises from the inherent nonlinearity, complex dependence structure, heterogeneity and resulting non-standard distributions of the underlying time series. Quantile regressions are considered an important modeling technique for such analyses because of their rich interpretation and their broad insensitivity to extreme distributions. This paper provides an asymptotic justification of quantile trend regression in terms of unknown heterogeneity and dependence structure and the corresponding interpretation. An empirical application sheds light on the relevance of quantile regression modeling for analyzing monthly Central England temperature anomalies and illustrates their various heterogenous trends. Our results suggest the presence of heterogeneities across the considered seasonal cycle and an increase in the relative frequency of observing unusually high temperatures. KW - temperature KW - trend modeling KW - seasonality KW - heterogeneity KW - quantile regression KW - C02 KW - C14 KW - C18 KW - C22 KW - Q54 Y1 - 2022 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:739-opus4-10382 SN - 2227-7390 VL - 10 IS - 3 PB - MDPI ER - TY - THES A1 - Schiffbeck, Adrian T1 - The influence of religious motivations on young people`s civic engagement N2 - With respect to religious motivations for political participation and civic engagement, scholars have set their focus on social capital and the recruiting potential for volunteers inside religious communities. Less attention has been paid to individual religious impulses, but also to reasons for which people step out from deliberative processes, especially in regard to the Eastern European Orthodox cultural context. We are approaching this under-explored research field in this dissertation, with focus on the Romanian city of Timișoara, and look at three particular aspects: the influence of religious perceptions on political protests (analysis of the 1989 revolution), the manner in which religion motivates young people to volunteer (view on a local community project) and factors determining people to retreat from public engagement (analysis of citizens` local committees). The research methods are qualitative - interviews, group discussions and analytical interpretation. Results show that non- or less religious young people are encouraged to protest by an indefinable supernatural force and motivated by moral interests (need for dignity and a fair treatment / procedural justice), more than material ones (distributive justice). When engaging in the community, the impulse partially comes from an intrinsic spirituality and a privatized experience with the divine. Giving up civic engagement has nothing to do with remuneration, but with the need for freedom of expression and moral appreciation. KW - Civic engagement, Community, Motivation, Religion, Protest, Young people KW - Rumänien KW - Soziales Engagement KW - Religion KW - Jugend KW - Bürgerbeteiligung, Jugend, Motivation, Protest, Unsichtbare Religion Y1 - 2021 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:739-opus4-10291 ER - TY - JOUR A1 - Rohlfing, Ingo A1 - Bethke, Felix T1 - How do researchers choose their goals of inference? A survey experiment on the effects of the state of research and method preferences on the choice between research goals N2 - In empirical research, scholars can choose between an exploratory causes-of-effects analysis, a confirmatory effects-ofcauses approach, or a mechanism-of-effects analysis that can be either exploratory or confirmatory. Understanding the choice between the approaches is important for two reasons. First, the added value of each approach depends on how much is known about the phenomenon of interest at the time of the analysis. Second, because of the specializations of methods, there are benefits to a division of labor between researchers who have expertise in the application of a given method. In this preregistered study, we test two hypotheses that follow from these arguments. We theorize that exploratory research is chosen when little is known about a phenomenon and a confirmatory approach is taken when more knowledge is available. A complementary hypothesis is that quantitative researchers opt for confirmatory designs and qualitative researchers for exploration because of their academic socialization. We test the hypotheses with a survey experiment of more than 900 political scientists from the United States and Europe. The results indicate that the state of knowledge has a significant and sizeable effect on the choice of the approach. In contrast, the evidence about the effect of methods expertise is more ambivalent. Y1 - 2023 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:739-opus4-12739 IS - Research & Politics, 10(2) SP - 1 EP - 7 PB - Sage Publications ER - TY - THES A1 - Garbas, Janina T1 - From now to next – Three essays on consumer responses to innovative technology-driven business models N2 - Over the last decades, ongoing advancements in information technology (i.e., Internet and mobile devices) have expanded a firm’s ability to communicate and interact with consumers and hence, create the potential of building sustainable relationships. Tailoring offerings through (1) consumer-initiated customization and (2) firm-initiated personalization is considered a key driver of long-term consumer relationships. As technologies continue to evolve, the opportunities for tailored marketing expand and enable new technology-driven business models that help to leverage customization and personalization and strengthen customer relationships in the era of the digital economy. Across three independent essays, the purpose of this dissertation is to answer the overarching research question of how innovative technology-driven business models versus traditional business models in the domains of customization and personalization influence consumer behavior. Thereby, this dissertation contributes to an understanding of challenges and opportunities of innovative customization and personalization business models with the ultimate goal of enabling their successful diffusion in the marketplace. Specifically, in Essay 1 and Essay 2, I investigate an innovative business model located in the realm of customization, that is, internal product upgrades (i.e., offering fee-based access to originally built-in, but deliberately restricted, optional features). Using a conceptual approach, Essay 1 provides a framework for understanding how internal product upgrades will likely influence consumers’ responses. As such, it outlines evolving challenges and opportunities of internal product upgrades and derives questions for future research. In Essay 2, I use an empirical approach to examine pitfalls of internal product upgrades in the product usage phase. Drawing on research on normative expectations and perceived ownership, this essay reveals that consumers respond less favorably to internal (vs. external) product upgrades and investigates managerially relevant boundary conditions. Finally, Essay 3 creates novel insights into a business model in the domain of personalization. This essay examines how the increasingly prevalent data disclosure practice of firms engaging in a network with other firms to exchange consumer data, which we denote as Business Network Data Exchange (BNDE), influences consumers’ privacy-related decision-making. In particular, this essay shows that consumers are less likely to disclose personal data in BNDE (vs. traditional dyadic) data exchange settings and that immediate affective reactions are crucial in explaining consumers’ privacy-related decision-making. Within this dissertation, I make substantial contributions at a more general level to literature on customization and personalization by comparing innovative business models to established ones. At the individual essay level, I extend existing research in the domains of product feature modifications, norm violations, and privacy-related decision making. Moreover, this dissertation provides actionable implications for managers who are facing the decision to transform their established business model into an innovative technology-driven one. KW - technology-driven business models KW - consumer behavior KW - customization KW - personalization Y1 - 2022 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:739-opus4-11132 ER - TY - THES A1 - Resch, René Matthias T1 - Three Essays on Brand Management in the Business-to-Business Context: Brand Identity, Brand Culture, and Brand Essence N2 - This dissertation examines the overarching research question of how the suppliers’ brand management in the form of brand identity, brand culture, and brand essence influences buyer-seller relationships in three independent essays. In Essay 1, I address the structure, capabilities, and outcomes of brand identity from a supplier perspective. Through qualitative interviews with suppliers, I examine how widespread the concept of brand identity is in practice and what exactly practitioners understand by it. Going further, I look at what capabilities and conditions are necessary for brand identity to be successful and what outcomes suppliers hope to achieve. Using an Information-Display-Matrix (IDM) test and a sample of Master of Business Administration (MBA) students, I examine the relevance of brand functions in more detail. In Essay 2, I use a dyadic dataset with matched buyer-seller dyads to examine the causes and effects of perceptual congruence and incongruence of brand culture strength on the buyer-seller relationship, while considering relationship-specific investments and interaction mechanisms as moderating effects. I show that congruence and incongruence have different effects on customer loyalty and price sensitivity and that these are strongly context-dependent. In Essay 3, I deal with brand essence strength interactions and their effects on the buyer-seller relationship. I use a dyadic dataset with matched buyer-seller dyads to show how brand essence strength influences customer loyalty and customer profitability, and how it interacts with key customer attitudes and other important buyer-seller relationship closeness indicators. This dissertation makes a significant contribution to the literature on brand identity, brand culture, and brand essence in buyer-seller relationships. Furthermore, my dissertation offers practical implications for managers at B2B suppliers who (re)shape their brand management with a focus on the inner parts of the brand. KW - brand management KW - business-to-business KW - brand identity KW - brand culture KW - brand essence Y1 - 2023 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:739-opus4-11589 ER - TY - THES A1 - Le, Mirjam T1 - The Peri-urban City: Cargo Cult Urbanism, Porosity and an Emerging Urban Citizenship in Vietnamese Secondary Cities N2 - The impact of urban development on local residents in the urban periphery oscillates between processes of empowerment and processes of marginalization as well as between state-controlled order and decentralized self-organization. Consequently local authorities, including urban planners and local residents need to negotiate their respective roles in the production and usage of urban space defined by transition, transformation and ambiguity. Therefore, this work examines the underlying patterns, interactions and structures which define the negotiation of state-society relations in the framework of a porous peri-urban landscape in Vietnam’s secondary cities. In Chapter 1, peri-urban areas are defined as space of transformation where pattern of rural land use are intertwined with pattern of urban land use to create an urban-rural interface with blurred boundaries. The main characteristic of the spatial pattern in Tam Kỳ and Buôn Ma Thuột is rooted urban porosity leading to the spatial intertwining of rural, peri-urban and urban spaces. The emerging urban landscape can be defined as peri-urban city. Three main themes define this peri-urban city beyond porosity: (1) processes of transformation creating the peri-urban city, (2) networks of power and control as means to adapt to these transformations and (3) mobility as prerequisite for ability to benefit from the changing landscape in peri-urban cities. Chapter 2 describes how state authorities, urban planners and private investors at the local level in Tam Kỳ and Buôn Ma Thuột use porous space to reproduce the city based on their aspirations. This leads to a cargo cult urbanism, where urban planning is rooted in future aspirations for the city. Plans and construction efforts reference the image of a modern urban future and produce the image of a city, which does not exists in the real urban space of Tam Kỳ and Buôn Ma Thuột. In the meantime, practices based in peri-urban space are often contradictory to the official aspirations of local state authorities Chapter 3 explores this emerging divergence between the aspired urban space by the state and the reality of urban space rooted in material and social porosity. Traditional, newly accessible and environmental porosity provide an array of accessible space which transforms the peri-urban city into a social arena of encounters and interaction. Consequently, porosity enables local residents to maintain urban space as commons. This counters the push towards the privatization of urban space by state and private actors and creates multiple aspirations for the urban future. Rooted in urban space as commons, porosity enables the usage of peri-urban space as spaces of resistance as discussed in Chapter 4. Mobility and interaction are means of reproduction in the porous ambiguity of urban materiality but also become means of everyday resistance. The emerging spatialities of emancipation provide opportunities for an emerging urban citizenship. Urban materiality and urban citizenship have a mutually constitutive relationship. KW - peri-urbanization KW - Vietnam KW - urban citizenship KW - urban porosity KW - cargo-cult urbanism Y1 - 2024 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:739-opus4-14097 ER - TY - THES A1 - Postel, Lea T1 - In Data We Trust: Three Essays on Consumers' Trust-Based Decision-Making Strategies in Privacy-Relevant Online Contexts N2 - Technological advancements and new legal requirements are continuously changing the online data disclosure landscape in terms of both, the quantity and quality of data that firms can acquire. Nowadays, consumers are required to disclose personal data online multiple times a day and in a variety of different contexts, such as creating user profiles, online payment or using location-based services. Despite consumers’ increasing online privacy concerns, firms rely ever more strongly on consumer data that they convert into a competitive advantage through personalized product recommendations and targeted advertising. In an effort to encourage consumer data disclosure, many firms have focused on building trust as a way to counterbalance privacy concerns and mitigate risk perceptions. Correspondingly, marketing literature has continued to examine the interplay of trust and consumer privacy concerns. While the extant research has considerably advanced our understanding of the role of trust in privacy-related decision-making, the majority of studies has mainly focused on single-stage, dyadic disclosure settings and cognitive decision-making processes. Against this background, the overarching goal of this thesis is to shed light on under-researched data disclosure contexts involving trust and to explore additional facets of the underlying decision-making processes. For example, considering pre- and post-disclosure stages when evaluating consumers’ data disclosure decisions allows for a more holistic picture of the decision-making process. Similarly, social media and sharing economy settings challenge the traditional assumption of purely dyadic consumer-firm data disclosure, thus extending traditional conceptualizations of trust. Across three independent essays, this thesis addresses the overarching research question of how the peculiarities of multi-stage and multi-actor settings shape consumers’ trust-based decision-making strategies. Y1 - 2024 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:739-opus4-14021 ER - TY - THES A1 - Bermeitinger, Bernhard T1 - Investigating a Second-Order Optimization Strategy for Neural Networks N2 - In summary, this cumulative dissertation investigates the application of the conjugate gradient method CG for the optimization of artificial neural networks (NNs) and compares this method with common first-order optimization methods, especially the stochastic gradient descent (SGD). The presented research results show that CG can effectively optimize both small and very large networks. However, the default machine precision of 32 bits can lead to problems. The best results are only achieved in 64-bits computations. The research also emphasizes the importance of the initialization of the NNs’ trainable parameters and shows that an initialization using singular value decomposition (SVD) leads to drastically lower error values. Surprisingly, shallow but wide NNs, both in Transformer and CNN architectures, often perform better than their deeper counterparts. Overall, the research results recommend a re-evaluation of the previous preference for extremely deep NNs and emphasize the potential of CG as an optimization method. N2 - Zusammenfassend untersucht die vorliegende kumulative Dissertation die Anwendung des konjugierten Gradienten (CG) zur Optimierung künstlicher neuronaler Netzwerke (NNs) und vergleicht diese Methode mit verbreiteten Optimierungsverfahren erster Ordnung, insbesondere dem Stochastischem Gradientenabstieg (SGD). Die in den Arbeiten präsentierten Forschungsergebnisse zeigen, dass CG in der Lage ist, sowohl kleinere als auch sehr große Netzwerke effektiv zu optimieren. Allerdings kann die Maschinen- genauigkeit bei 32-Bit-Berechnungen zu Problemen führen, beste Ergebnisse werden erst in 64-Bit-Fließkommazahlen erreicht. Die Forschung betont auch die Bedeutung der Initialisierung der NN-Parameter und zeigt, dass eine Initialisierung mittels Singulärwertzerlegung zu deutlich geringeren Fehlerwerten führt. Überraschenderweise erzielen flachere NNs bessere Ergebnisse als tiefe NNs mit einer vergleichbaren Anzahl an trainierbaren Parametern, unabhängig vom jeweiligen NN, das die künstlichen Daten erzeugt. Es zeigt sich auch, dass flache, breite NNs, sowohl in Transformer-, als auch in CNN-Architekturen oft besser abschneiden als ihre tieferen Gegenstücke. Insgesamt empfehlen die Forschungsergebnisse eine Neubewertung der bisherigen Präferenz für extrem tiefe NNs und betonen das Potential von CG als Optimierungsmethode. Y1 - 2024 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:739-opus4-14087 ER - TY - JOUR A1 - Frank, Florian A1 - Böttger, Simon A1 - Mexis, Nico A1 - Anagnostopoulos, Nikolaos Athanasios A1 - Mohamed, Ali A1 - Hartmann, Martin A1 - Kuhn, Harald A1 - Helke, Christian A1 - Arul, Tolga A1 - Katzenbeisser, Stefan A1 - Hermann, Sascha T1 - CNT-PUFs: highly robust and heat-tolerant carbon-nanotube-based physical unclonable functions N2 - In this work, we explored a highly robust and unique Physical Unclonable Function (PUF) based on the stochastic assembly of single-walled Carbon NanoTubes (CNTs) integrated within a wafer-level technology. Our work demonstrated that the proposed CNT-based PUFs are exceptionally robust with an average fractional intra-device Hamming distance well below 0.01 both at room temperature and under varying temperatures in the range from 23 °C to 120 °C. We attributed the excellent heat tolerance to comparatively low activation energies of less than 40 meV extracted from an Arrhenius plot. As the number of unstable bits in the examined implementation is extremely low, our devices allow for a lightweight and simple error correction, just by selecting stable cells, thereby diminishing the need for complex error correction. Through a significant number of tests, we demonstrated the capability of novel nanomaterial devices to serve as highly efficient hardware security primitives. KW - Carbon NanoTube (CNT) KW - Physical Unclonable Function (PUF) KW - Nanomaterials (NMs) KW - hardware security KW - security KW - privacy KW - Internet of Things (IoT) Y1 - 2023 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:739-opus4-14011 VL - 2023 IS - 13(22) PB - MDPI CY - Basel ER - TY - THES A1 - Klepikova, Tatiana T1 - Crossing Soviet Thresholds: Privacy, Literature, and Politics in Late Soviet Russia N2 - My dissertation examines literary mythologies of privacy in the authoritarian Russia of 1953–1985. This era was marked by an expansion of “non-state spheres,” or areas of life of which the Communist state increasingly released its control after Joseph Stalin’s death in 1953. Political elites, architects, and designers, as well as ordinary citizens co-constructed and explored the rising spheres through the languages of their respective fields—by producing regulations and laws, designing and erecting new types of buildings, developing new and modernizing already familiar everyday objects as well as devising new ways of integrating these objects into private and public spaces. Alongside these voices, transformations in the cultural sphere in general, and literature in particular, were most vocal. The late Soviet era witnessed the dissolution of the ossified ideology of socialist realism that focused on the glorification of the “new Soviet man” and had held culture in its tight grips since the 1930s. Starting from the 1950s, writers increasingly focused on portraying areas of life that lay beyond one’s public commitments and experimented with new meanings, codes, and forms to give shape to novel spheres of experience of the “late Soviet man” that can be subsumed under the concept of the “private sphere.” The analytical framework of my dissertation is built around the journey to understand the mechanisms and architecture that powered the imagination of models of distancing oneself from the state and the society at large—scenarios of privacy, as we may call them today. I examine Russian prose and drama of the 1950s–1980s as a laboratory for the ideas of privacy, which was increasingly sought in the society disillusioned by the Communist doctrine and thus progressively alienating from active participation in the public sphere. I analyze the meanings that writers incorporated into new and old forms of domesticity—private flats that became progressively widespread throughout the 1950s–1980s, rooms in communal apartments, individual houses—to determine the spectrum of concepts that nurtured the idea of privacy in the late Soviet literary imagination. I also examine representations of reciprocal paradigms of relations between subjects from which the state and society at large were increasingly excluded. In the examples that I analyze, forms of private withdrawals variate from establishing control over liminal spaces or escaping into the world of feelings and emotions and building a connection to a person or space (significant for the characters for private rather than public reasons) to experimenting with language and pursuing one’s idiolect despite the ubiquitous “officialese,” as well as living in temporalities asynchronous with the public time. Beyond revealing the visions of different, non-state existences in the late Soviet era, my text also advocates examining the role of official literature as a platform for subversion and change that was no less important in an authoritarian state than dissident literature. I see officially published texts as a cultural subaltern who defies the state of affairs and slowly but firmly turns the “state sphere” into a public one by pushing its own agenda through publications that test and gain ground for bolder visions of Soviet life that are not predicated on the commitment to the public sphere. With individual mechanisms of power assertion employed by the state or literature in the late Soviet era well-researched, the framework is still missing that would capture the shifts of borders between the private and public spheres under the influence of these actors. In devising such framework, I build upon sociological theories of disattendability and civil inattention that Erving Goffman conceived to describe conventions of individual behavior and social interaction in public. Extending these theories toward the studies of literary politics, I argue that by envisioning scenarios of a private retreat and bringing them into officially published editions, literature normalized privacy as a late Soviet imaginary and, therefore, continuously heightened its own disattendability, thereby expanding the borders of the private sphere. On the side of the state, the border was defined by the triggers of disturbance of civil inattention: privacy was conceded in return for disattendability. Under such conditions, literature became a bizarre “private kitchen” that performed private and public functions simultaneously—similar to the kitchens in newly-built individual apartments that were popular loci of socialization in the late Soviet era. It turned into a place where one can escape—it became one of the “niches of privacy” where it was possible to discuss and negotiate the world, in which the society lived or to which it should strive. At the same time, it assumed the role of a surrogate for the public sphere within the “state” sphere by pushing its own agenda through the publication of literary texts that sought to imagine a person rather than a cog in the Communist machine and thus transformed socialist realism into a literary current “with a human face.” In my research, privacy, literature, and politics are bound together to reveal a vibrant spectacle of the continuous interaction between the state, cultural elites, and the citizens, in which thresholds are erected and crossed incessantly. Fictional private sites were battlefields for the production and contestation of ideologies, and the exposure of these literary wars to the public eye played a fundamental role in shifting the borders between the private and the public spheres in an authoritarian late Soviet Russia. The patterns of relations between the state and culture that I uncover in my dissertation resonate in neo-authoritarian twenty-first-century Russia, making privacy an important lens for our insight into the role of culture in rising authoritarian and failing democratic systems across the globe. KW - privacy KW - literature KW - Soviet Y1 - 2024 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:739-opus4-13771 ER - TY - THES A1 - Mußotter, Marlene T1 - On nation, homeland, and democracy: Toward a novel three-factor measurement model for nationalism and patriotism BT - revisiting the nationalism-patriotism distinction N2 - The nationalism-patriotism distinction is one of the most influential distinctions in the field of political psychology. While frequently used, the distinction suffers from a number of shortcomings that have hitherto been devoted little attention to. This dissertation aims to contribute to fill this research gap by systematically addressing these pitfalls. Notably, it does not abandon the binary distinction as such, but aims to further refine it. Thoroughly revisiting the nationalism-patriotism distinction, it synthesises the field's two predominant research traditions, i.e. the work of Kosterman and Feshbach (1989) in the U.S. and the one of Blank and Schmidt (2003) in Germany, that have not been brought into dialogue. In so doing, and engaging with research on attachment, it calls for a more nuanced triad of attachments: nationalism, that revolves around the nation; patriotism, that refers to the homeland; and democratic patriotism with democracy as its object of attachment. In line with this triad, it introduces a novel three-factor measurement model that has been validated in three studies in Germany. Overall, the dissertation underlines the need to approach ambiguous and complex concepts such as nationalism and patriotism in a more theoretically consistent way before operationalizing them in a rigorous manner. KW - Nationalismus KW - Patriotismus KW - Demokratie KW - Nation KW - Identität Y1 - 2024 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:739-opus4-13781 ER - TY - THES A1 - Fink, Simon Dominik T1 - Constrained Planarity Algorithms in Theory and Practice N2 - In the constrained planarity setting, we ask whether a graph admits a crossing-free drawing that additionally satisfies a given set of constraints. These constraints are often derived from very natural problems; prominent examples are Level Planarity, where vertices have to lie on given horizontal lines indicating a hierarchy, Partially Embedded Planarity, where we extend a given drawing without modifying already-drawn parts, and Clustered Planarity, where we additionally draw the boundaries of clusters which recursively group the vertices in a crossing-free manner. In the last years, the family of constrained planarity problems received a lot of attention in the field of graph drawing. Efficient algorithms were discovered for many of them, while a few others turned out to be NP-complete. In contrast to the extensive theoretical considerations and the direct motivation by applications, only very few of the found algorithms have been implemented and evaluated in practice. The goal of this thesis is to advance the research on both theoretical as well as practical aspects of constrained planarity. On the theoretical side, we consider two types of constrained planarity problems. The first type are problems that individually constrain the rotations of vertices, that is they restrict the counter-clockwise cyclic orders of the edges incident to vertices. We give a simple linear-time algorithm for the problem Partially Embedded Planarity, which also generalizes to further constrained planarity variants of this type. The second type of constrained planarity problem concerns more involved planarity variants that come down to the question whether there are embeddings of one or multiple graphs such that the rotations of certain vertices are in sync in a certain way. Clustered Planarity and a variant of the Simultaneous Embedding with Fixed Edges Problem (Connected SEFE-2) are well-known problems of this type. Both are generalized by our Synchronized Planarity problem, for which we give a quadratic algorithm. Through reductions from various other problems, we provide a unified modelling framework for almost all known efficiently solvable constrained planarity variants that also directly provides a quadratic-time solution to all of them. For both our algorithms, a key ingredient for reaching an efficient solution is the usage of the right data structure for the problem at hand. In this case, these data structures are the SPQR-tree and the PC-tree, which describe planar embedding possibilities from a global and a local perspective, respectively. More specifically, PC-trees can be used to locally describe the possible cyclic orders of edges around vertices in all planar embeddings of a graph. This makes it a key component for our algorithms, as it allows us to test planarity while also respecting further constraints, and to communicate constraints arising from the surrounding graph structure between vertices with synchronized rotation. Bridging over to the practical side, we present the first correct implementation of PC-trees. We also describe further improvements, which allow us to outperform all implementations of alternative data structures (out of which we only found very few to be fully correct) by at least a factor of 4. We show that this yields a simple and competitive planarity test that can also yield an embedding to certify planarity. We also use our PC-tree implementation to implement our quadratic algorithm for solving Synchronized Planarity. Here, we show that our algorithm greatly outperforms previous attempts at solving related problems like Clustered Planarity in practice. We also engineer its running time and show how degrees of freedom in the theoretical algorithm can be leveraged to yield an up to tenfold speed-up in practice. KW - Constrained Planarity KW - Clustered Planarity KW - Synchronized Planarity KW - Algorithm Engineering Y1 - 2024 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:739-opus4-13817 ER - TY - THES A1 - Danner, Dominik T1 - Towards Quality of Service and Fairness in Smart Grid Applications N2 - Due to the increasing amount of distributed renewable energy generation and the emerging high demand at consumer connection points, e. g., electric vehicles, the power distribution grid will reach its capacity limit at peak load times if it is not expensively enhanced. Alternatively, smart flexibility management that controls user assets can help to better utilize the existing power grid infrastructure for example by sharing available grid capacity among connected electric vehicles or by disaggregating flexibility requests to hybrid photovoltaic battery energy storage systems in households. Besides maintaining an acceptable state of the power distribution grid, these smart grid applications also need to ensure a certain quality of service and provide fairness between the individual participants, both of which are not extensively discussed in the literature. This thesis investigates two smart grid applications, namely electric vehicle charging-as-a-service and flexibility-provision-as-a-service from distributed energy storage systems in private households. The electric vehicle charging service allocation is modeled with distributed queuing-based allocation mechanisms which are compared to new probabilistic algorithms. Both integrate user constraints (arrival time, departure time, and energy required) to manage the quality of service and fairness. In the queuing-based allocation mechanisms, electric vehicle charging requests are packetized into logical charging current packets, representing the smallest controllable size of the charging process. These packets are queued at hierarchically distributed schedulers, which allocate the available charging capacity using the time and frequency division multiplexing technique known from the networking domain. This allows multiple electric vehicles to be charged simultaneously with variable charging currents. To achieve high quality of service and fairness among electric vehicle charging processes, dynamic weights are introduced into a weighted fair queuing scheduler that considers electric vehicle departure time and required energy for prioritization. The distributed probabilistic algorithms are inspired by medium access protocols from computer networking, such as binary exponential backoff, and control the quality of service and fairness by adjusting sampling windows and waiting periods based on user requirements. The second smart grid application under investigation aims to provide flexibility provision-as-a-service that disaggregates power flexibility requests to distributed battery energy storage systems in private households. Commonly, the main purpose of stationary energy storage is to store energy from a local photovoltaic system for later use, e. g., for overnight charging of an electric vehicle. This is optimized locally by a home energy management system, which also allows the scheduling of external flexibility requests defined by the deviation from the optimal power profile at the grid connection point, for example, to perform peak shaving at the transformer. This thesis discusses a linear heuristic and a meta heuristic to disaggregate a flexibility request to the single participating energy management systems that are grouped into a flexibility pool. Thereby, the linear heuristic iteratively assigns portions of the power flexibility to the most appropriate energy management system for one time slot after another, minimizing the total flexibility cost or maximizing the probability of flexibility delivery. In addition, a multi-objective genetic algorithm is proposed that also takes into account power grid aspects, quality of service, and fairness among par-ticipating households. The genetic operators are tailored to the flexibility disaggregation search space, taking into account flexibility and energy management system constraints, and enable power-optimized buffering of fitness values. Both smart grid applications are validated on a realistic power distribution grid with real driving patterns and energy profiles for photovoltaic generation and household consumption. The results of all proposed algorithms are analyzed with respect to a set of newly defined metrics on quality of service, fairness, efficiency, and utilization of the power distribution grid. One of the main findings is that none of the tested algorithms outperforms the others in all quality of service metrics, however, integration of user expectations improves the service quality compared to simpler approaches. Furthermore, smart grid control that incorporates users and their flexibility allows the integration of high-load applications such as electric vehicle charging and flexibility aggregation from distributed energy storage systems into the existing electricity distribution infrastructure. However, there is a trade-off between power grid aspects, e. g., grid losses and voltage values, and the quality of service provided. Whenever active user interaction is required, means of controlling the quality of service of users’ smart grid applications are necessary to ensure user satisfaction with the services provided. Y1 - 2023 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:739-opus4-13731 ER - TY - THES A1 - Grösbrink, Carl-Friederich T1 - Three Essays on Firm Value and Firm Risk and their Relation to IT-Exposure, Corporate Social Responsibility, and Religiosity N2 - 1. IT-Exposure and Firm Value: We analyze the joint influence of a firm’s information technology (IT)-Exposure and investment behavior on firm value. Estimating a firm’s (partial) IT-Exposure allows for distinguishing between firms with a business model that is challenged by IT above and below market average. Hence, we estimate the annual IT-Exposure of a firm using a 3-factor Fama-French model extended by an IT-proxy. Subsequently, we analyze the relationship with Tobin’s Q in a panel data context, accounting for the relationship between IT-Exposure and investments proxied by R&D as well as CapEx. We use more than 48,000 firm-year observations for firms in the Russell 3000 Index covering the period 1990 to 2018. Although IT-Exposure has a negative impact on firm value, this discount can be overcompensated by up to 2.1 times by sufficient investments through R&D and CapEx, giving a firm with an average Tobin’s Q a premium of 14.8% to 19.2%, while controlling for endogeneity. 2. Corporate Social Responsibility, Risk, and Firm Value: An Unconditional Quantile Regression Approach: This paper examines the impact of corporate social responsibility (CSR) on firm risk, comprising total risk, idiosyncratic risk, and systematic risk, as well as firm value. We focus on analyzing the interrelationships along the entire distribution of the dependent variables, thus estimating an unconditional quantile regression (UQR). The analysis is based on CSR scores from Refinitiv and MSCI, using up to 12,013 firm-year observations over the period 2002 to 2019 for all U.S. companies listed on NYSE, NASDAQ, and AMEX. UQR reveals strongly heterogeneous effects along the unconditional quantiles of the dependent variables, which are reflected in sign changes, magnitude and significance variations. For CSR we find a risk-reducing as well as value-enhancing effect. When applying fixed effects OLS, we can just partly confirm the risk-reducing and value-enhancing effect of CSR shown in the literature. 3. Heterogenous Effects of Religiosity on Firm Risk and Firm Value: An Unconditional Quantile Regression Approach: This paper examines the impact of religiosity on firm risk, comprising total risk, idiosyncratic risk, and systematic risk, as well as firm value. We focus on analyzing the interrelationships along the entire distribution of the dependent variables, thus estimating an unconditional quantile regression (UQR). The analysis is based on all U.S. companies listed on NYSE, NASDAQ, and AMEX for the period from 1980 through 2020. UQR reveals strongly heterogeneous effects along the unconditional quantiles of the dependent variables, which are reflected in sign changes, magnitude and significance variations. Overall, the risk-reducing effect of religiosity is more pronounced in the higher quantiles of the distribution. We further observe a value-reducing as well as value-enhancing religiosity effect. When applying fixed effects OLS, we can confirm the risk-reducing and non-existing value effect of religiosity shown in the literature. The robustness of our results is underpinned by a battery of additional tests. KW - Firm Value KW - Firm Risk KW - IT-Exposure KW - Corporate Social Responsibility KW - Religiosity Y1 - 2023 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:739-opus4-11558 ER - TY - THES A1 - Seruset, Marco T1 - Three Essays on Price Discovery, Stock Liquidity, and Crash Risk N2 - Abstract 1: This paper investigates whether market quality, uncertainty, investor sentiment and attention, and macroeconomic news affect bitcoin price discovery in spot and futures markets. Over the period December 2017 – March 2019, we find significant time variation in the contribution to price discovery of the two markets. Increases in price discovery are mainly driven by relative trading costs and volume, and by uncertainty to a lesser extent. Additionally, medium-sized trades contain most information in terms of price discovery. Finally, higher news-based bitcoin sentiment increases the informational role of the futures market, while attention and macroeconomic news have no impact on price discovery. Abstract 2: We investigate whether local religious norms affect stock liquidity for U.S. listed companies. Over the period 1997–2020, we find that firms located in more religious areas have higher liquidity, as reflected by lower bid-ask spreads. This result persists after the inclusion of additional controls, such as governance metrics, and further sensitivity and endogeneity analyses. Subsample tests indicate that the impact of religiosity on stock liquidity is particularly evident for firms operating in a poor information environment. We further show that firms located in more religious areas have lower price impact of trades and smaller probability of information-based trading. Overall, our findings are consistent with the notion that religiosity, with its antimanipulative ethos, probably fosters trust in corporate actions and information flows, especially when little is known about the firm. Finally, we conjecture an indirect firm value implication of religiosity through the channel of stock liquidity. Abstract 3: This study shows that higher physical distance to institutional shareholders is associated with higher stock price crash risk. Since monitoring costs increase with distance, the results are consistent with the monitoring theory of local institutional investors. Cross-sectional analyses show that the effect of proximity on crash risk is more pronounced for firms with weak internal governance structures. The significant relation between distance and crash risk still holds under the implementation of the Sarbanes-Oxley Act, however, to a lower extent. Also, the existence of the channel of bad news hoarding is confirmed. Finally, I show that there is heterogeneity in distance-induced monitoring activities of different types of institutions. Y1 - 2023 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:739-opus4-11563 ER - TY - THES A1 - Maimunah, Siti T1 - Reclaiming "Tubuh-Tanah Air": A Life Project on Doing Feminist Political Ecology at the Capitalist Frontier N2 - My study examines how the configuration of the capitalist frontier through extractivism shapes ethnicity, gender, and intersectionality in the areas surrounding a nickel mine in Sorowako (East Luwu District, South Sulawesi), logging and coal mining along the Lalang River (Murung Raya District, Central Kalimantan) Indonesia. The colonial frontier intersects with the capitalist frontier and provides the circumstances for its formation. The colonial restrictions, religions, commodities, the imposition of labor discipline, and political changes have molded ethnic identities and relationships with nature. Furthermore, using autoethnography and Feminist Political Ecology, I combine my experiences as a woman academic-activist with the experiences of the people in my research area. I identify how communities and individuals interact with the multiple-frontier in everyday life by defining the configuration of the frontier from above and below. Thus, my dissertation contributes to understanding how I, the community, and the capitalist frontier landscape are contained and can potentially transform into multidimensional resistance. I develop a link between the body as the interior frontier and the extractive landscape to be transformed into a perspective of “Tubuh-tanah air” as a future arena of engagement and resistance to extractivism. KW - Extractivism KW - Capitalist frontier KW - Feminist Political Ecology KW - Resistance KW - Tubuh-tanah air Y1 - 2023 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:739-opus4-11656 ER - TY - THES A1 - McLarren, Katharina T1 - Religion and International Society - Approaches to Including Religion in the International Relations Research Agenda N2 - Religion can unite and divide, it can lead to a strengthening or a weakening of identity and legitimacy. Religion can stoke conflicts but it can also pacify them – within societies and in international politics. Religion endures and it can exist independently of states, it can constitute them, and it can provide new forms of states, societies, and empires. Arguably, religion shapes or even constitutes the international society of states, an aspect so far neglected in the field of International Relations. The dissertation provides a new definition of religion for International Relations and the English School in particular. Based upon this understanding of religion, the five publications presented in the dissertation provide new analytical and theoretical concepts and approaches to fill the research gap. Religion is integrated into the theoretical framework of the English School in the form of a “prime institution” and with the help of the “quilt model”. While the former expands the theoretical framework, the latter adds an analytical layer. Based upon this definition religion is also introduced as a concept (“hybrid actorness”) in Foreign Policy Analysis, opening it up to become less state-centrist and more transnational-oriented, thereby boosting its relevance considering the evolving international (global) society. In another step, the Securitization framework of analysis is expanded to include (freedom) of religion. By revisiting the publications, the dissertation is able to identify next steps in terms of avenues of research. Finally, the dissertation reveals areas of study which contribute to increasing the pertinence of IR, particularly of the English School. KW - Religion KW - International Society KW - English School Y1 - 2022 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:739-opus4-12365 ER - TY - JOUR A1 - Caspari-Sadeghi, Sima T1 - Learning assessment in the age of big data: Learning analytics in higher education JF - Cogent Education N2 - Data-driven decision-making and data-intensive research are becoming prevalent in many sectors of modern society, i.e. healthcare, politics, business, and entertainment. During the COVID-19 pandemic, huge amounts of educational data and new types of evidence were generated through various online platforms, digital tools, and communication applications. Meanwhile, it is acknowledged that educa-tion lacks computational infrastructure and human capacity to fully exploit the potential of big data. This paper explores the use of Learning Analytics (LA) in higher education for measurement purposes. Four main LA functions in the assessment are outlined: (a) monitoring and analysis, (b) automated feedback, (c) prediction, prevention, and intervention, and (d) new forms of assessment. The paper con-cludes by discussing the challenges of adopting and upscaling LA as well as the implications for instructors in higher education. KW - Big data KW - learning analytics KW - technology-enhanced assessment Y1 - 2022 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:739-opus4-12236 VL - 2023 IS - Volume 110, issue 1 PB - Taylor & Francis ER - TY - THES A1 - Duffourc, Mindy T1 - Liability for Negligent Healthcare Clinical Risk Management in the United States and Germany N2 - Systems-focused error prevention efforts are internationally recognized in the healthcare industry, and industry efforts to identify and correct organizational defects through the process of CRM are well established in the U.S. and Germany. However, in both countries, there is no clear corresponding liability for healthcare organizations who fail to engage in systems-based learning through the process of clinical risk management (CRM). Although both jurisdictions do recognize organization-based theories of liability, liability for negligent CRM has not been explicitly recognized by courts in either jurisdiction to date. German legal scholars, recognizing this gap in liability for healthcare organizations, have written in support of finding liability for negligent CRM under existing tort law; however, there is no corresponding discussion in the American legal literature. This dissertation fills that gap with a comparative analysis of medical negligence law in the U.S. and Germany through the international lens of modern medical error prevention science and policy to articulate a legal basis and sketch the evidentiary framework for tort liability based on negligent CRM. KW - law KW - law and medicine KW - medical liability KW - medical negligence KW - medical errors Y1 - 2024 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:739-opus4-13859 ER - TY - JOUR A1 - Herbold, Steffen A1 - Hautli‑Janisz, Annette A1 - Heuer, Ute A1 - Kikteva, Zlata A1 - Trautsch, Alexander T1 - A large‑scale comparison of human‑written versus ChatGPT‑generated essays JF - Scientific Reports N2 - ChatGPT and similar generative AI models have attracted hundreds of millions of users and have become part of the public discourse. Many believe that such models will disrupt society and lead to significant changes in the education system and information generation. So far, this belief is based on either colloquial evidence or benchmarks from the owners of the models—both lack scientific rigor. We systematically assess the quality of AI-generated content through a large-scale study comparing human-written versus ChatGPT-generated argumentative student essays. We use essays that were rated by a large number of human experts (teachers). We augment the analysis by considering a set of linguistic characteristics of the generated essays. Our results demonstrate that ChatGPT generates essays that are rated higher regarding quality than human-written essays. The writing style of the AI models exhibits linguistic characteristics that are different from those of the human-written essays. Since the technology is readily available, we believe that educators must act immediately. We must re-invent homework and develop teaching concepts that utilize these AI models in the same way as math utilizes the calculator: teach the general concepts first and then use AI tools to free up time for other learning objectives. Y1 - 2023 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:739-opus4-13961 VL - 13 PB - Springer Nature ER - TY - JOUR A1 - Hassen, Wiem Fekih A1 - Ben Ahmed, Mariem T1 - Optimization of a Redox-Flow Battery Simulation Model Based on a Deep Reinforcement Learning Approach JF - Batteries N2 - Vanadium redox-flow batteries (VRFBs) have played a significant role in hybrid energy storage systems (HESSs) over the last few decades owing to their unique characteristics and advantages. Hence, the accurate estimation of the VRFB model holds significant importance in large-scale storage applications, as they are indispensable for incorporating the distinctive features of energy storage systems and control algorithms within embedded energy architectures. In this work, we propose a novel approach that combines model-based and data-driven techniques to predict battery state variables, i.e., the state of charge (SoC), voltage, and current. Our proposal leverages enhanced deep reinforcement learning techniques, specifically deep q-learning (DQN), by combining q-learning with neural networks to optimize the VRFB-specific parameters, ensuring a robust fit between the real and simulated data. Our proposed method outperforms the existing approach in voltage prediction. Subsequently, we enhance the proposed approach by incorporating a second deep RL algorithm—dueling DQN—which is an improvement of DQN, resulting in a 10% improvement in the results, especially in terms of voltage prediction. The proposed approach results in an accurate VFRB model that can be generalized to several types of redox-flow batteries. KW - energy storage KW - redox-flow battery KW - battery modeling KW - battery state variables KW - parameter optimization KW - accurate estimation KW - voltage prediction KW - deep reinforcement learning KW - deep q-learning KW - dueling deep q-networks Y1 - 2023 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:739-opus4-13994 VL - 10 PB - MDPI CY - Basel ER - TY - JOUR A1 - Rowedder, Simon A1 - Wilcox, Phill A1 - Brandtstädter, Susanne T1 - Negotiating Chinese Infrastructures of Modern Mobilities: Insights from Southeast Asia JF - Advances in Southeast Asian Studies (ASEAS) N2 - Since the launch of the BRI, particular modes of movement are integral to its vision of what it means to be a modern world citizen. Nowhere is this more apparent than in Southeast Asia, where China-backed infrastructure projects expand, and at great speed. Such infrastructure projects are carriers of particular versions of modernity, promising rapid mobility to populations better connected than ever before. Yet, until now, little attention has been paid to how mobility and promises of mobility intersect with local understandings of development. In the introduction to this special issue, we argue that it is essential to think about the role infrastructure plays in forms of development that place connectivity at the center. We suggest that considering development, mobility and mo-dernity together is enlightening because it interrogates the connections between these interlocking themes. Through an introduction to five ethnographically grounded papers and two commentaries, all of which engage with infrastructures in different contexts throughout Southeast Asia, we demonstrate that there are significant gaps between of-ficial policy and lived experience. This makes the need to interrogate what infrastructure, mobilities, and global China really mean all the more pressing. KW - Belt and Road Initiative (BRI) KW - China-Backed Infrastructure KW - Development KW - Mobility KW - Southeast Asia Y1 - 2023 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:739-opus4-13973 VL - vol. 16 IS - no. 2 SP - 175 EP - 188 ER - TY - JOUR A1 - Hassen, Wiem Fekih A1 - Imen Azzouz, Imen Azzouz T1 - Optimization of Electric Vehicles Charging Scheduling Based on Deep Reinforcement Learning: A Decentralized Approach JF - Energies N2 - The worldwide adoption of Electric Vehicles (EVs) has embraced promising advancements toward a sustainable transportation system. However, the effective charging scheduling of EVs is not a trivial task due to the increase in the load demand in the Charging Stations (CSs) and the fluctuation of electricity prices. Moreover, other issues that raise concern among EV drivers are the long waiting time and the inability to charge the battery to the desired State of Charge (SOC). In order to alleviate the range of anxiety of users, we perform a Deep Reinforcement Learning (DRL) approach that provides the optimal charging time slots for EV based on the Photovoltaic power prices, the current EV SOC, the charging connector type, and the history of load demand profiles collected in different locations. Our implemented approach maximizes the EV profit while giving a margin of liberty to the EV drivers to select the preferred CS and the best charging time (i.e., morning, afternoon, evening, or night). The results analysis proves the effectiveness of the DRL model in minimizing the charging costs of the EV up to 60%, providing a full charging experience to the EV with a lower waiting time of less than or equal to 30 min. KW - smart EV charging KW - day-ahead planning KW - deep Q-Network KW - data-driven approach KW - waiting time KW - cost minimization KW - real dataset Y1 - 2023 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:739-opus4-13985 VL - 16 PB - MDPI CY - Basel ER - TY - THES A1 - Daschner, Stefan T1 - Essays on Trust, Behavior, and Decision-Making in the Human-Algorithm Interaction N2 - With recent progresses in the field of artificial intelligence (AI), algorithms can support more complex tasks (Frey and Osborne, 2017) that seemed safe from automation a few years ago (Brynjolfsson and McAfee, 2012). They can even outperform human decision-making in many task domains (Meehl, 1954; Dawes et al., 1989). The prominent defeat of Garry Kasparov, the world champion in chess, in 1997 is a milestone for the potentials of algorithms, increasing the value of IBM’s stock increased by $18 billion (Norvig and Russell, 2010). More recently, universal chatbots such as ChatGPT and the Bing Chatbot Sydney can influence millions of users and provide them answers to a broad range of tasks. To gain a competitive edge, companies invest heavily in algorithmic systems (Kappelman et al., 2021), which are considered as one of the most important drivers of today’s economy (Brynjolfsson and McAfee, 2011; Hogharth and Makridakis, 1981; Önkal et al., 2019). Particularly in management accounting, an algorithmic data analysis offers the potential to support a high decision quality, making their usage a key factor for success. However, algorithms can not only support, but also manipulate human decision-making (Roose et al., 2023). Algorithmic advice can lead to overtrust, i.e. to the heuristic replacement of vigilant information seeking and processing in favor of the advice provided (Mosier et al., 2001). The implementation of algorithmic decision support systems is thus no panacea to improve human decision-making. In contrast, they can entail new risks, such as the uncritical use of these algorithms (Boden, 2016). Yet, this ‘dark side’ of algorithms is not sufficiently investigated in the field of management accounting. With advances in machine learning, algorithmic support can become even more of a black box, blurring the reference points for evaluating its advice quality and thus increasing the risk of overtrust. Stephen Hawking even warns that AI will be “either the best, or the worst thing, ever to happen to humanity” (Alex Hern in: The Guardian: Stephen Hawking: AI will be 'either best or worst thing' for humanity, 19th October 2016). Interacting with such algorithmic systems therefore requires data literacy skills for an appropriate use. They seem to be a crucial prerequisite in today’s data-driven world to reap of the benefits of algorithmic systems. If no reflective and critical interaction between human and algorithm can be ensured, the trend towards a digitalized world will be a race against the algorithm (Brynjolfsson and McAfee, 2011). This dissertation takes this understudied critical perspective on the increasing implementation of algorithmic systems and sheds light on different aspects of human-algorithm interaction, ranging from the ability to use data visualization tools to trust calibrations and critical evaluations of algorithmic advices. Study I investigates an adequate information representation of subjective multiple criteria decision problems, an important task in management accounting, to support human decision-making. Study II distinguishes different designs of the human-algorithm interaction investigated in the trust in automation literature and compiles factors influencing the calibration of trust and behavior toward the true capabilities of the algorithm. Study III examines the role of performance feedback on trust and advice usage in a forecasting task for a better understanding of the recently observed phenomenon ‘algorithm aversion’. Finally, Study IV focusses on the risk of overtrust in advice in repeated interactions with a forecasting advisor and investigates the calibration of advice usage. Each study thereby represents an independent contribution and contains all information relevant to the respective research questions asked in the study. KW - artifical intelligence KW - algorithmic advice Y1 - 2024 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:739-opus4-14749 ER - TY - THES A1 - Stoffer, Gloria T1 - Three essays on b2b solution selling - challenges in sales, contracting, and pricing N2 - Offering solutions impose manifold challenges on suppliers. To master these challenges, suppliers need excellent commercial capabilities. This thesis considers these challenges and opportunities in sales, contracting, and pricing of complex B2B solutions in three essays: Essay 1 addresses the increased complexity for solution salespeople, who represent an essential strategic asset in solution selling. In-depth interviews with solution sales managers in study 1 and survey data from matched sales manager-salesperson dyads in study 2, reveal nine specific equifinal configurations of key personal and procedural competencies that qualify individual salespeople in their role and thus determine their solution sales success. The focus of essay 2 lies on B2B export relationships for complex product-service combinations in an international context. A regression analysis based on a survey study with 198 responses shows several direct and indirect effects of contractual and cultural constructs. The results give insights under which cultural framework conditions contract specificity serves as a safeguarding mechanism against uncertainty and opportunism. Essay 3 examines how the bidirectional agency relationship between suppliers and customers and the performance uncertainty of a solution influence B2B customers’ acceptance of performance-based pricing (PBP). Drawing on a cross-industry survey with 196 managers of B2B firms, this study contributes to extend PBP literature by showing how bidirectional agency relationships shape customers’ acceptance of PBP. In sum, this thesis contributes to a better understanding on how to optimize commercial capabilities in the context of national and international solution selling. It thereby focuses on addressing recently identified causes that hinder B2B firms from increasing their margins through solution selling by (1) optimizing the sales force through a better understanding of important resources and capabilities for solution selling, (2) optimizing their contractual set-up through a better understanding of cultural factors and the interplay with contract specificity, and 3) optimizing price policy through a better understanding of framework conditions, which have an impact on customers’ acceptance of PBP. KW - solution selling KW - customization KW - business-to-business Y1 - 2024 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:739-opus4-14728 ER - TY - THES A1 - Mladenov, Mladen T1 - Running in the Hamster Wheel. The Foreign Policy of Serbia between National Identity and the International Society. N2 - The thesis addresses a current topic related to the foreign policy of Serbia whereby Serbian foreign policy is analysed with reference to its domestic factors - in particular national identity - and also with regards to Serbia’s foreign factors, such as the Europeanization process and the nature of the international system. The overarching focus of the thesis is laid on the following puzzle: in spite of not attaining self-declared foreign policy goals and changing dynamics at the systemic level, Serbia’s foreign policy appear to be stable over time. In each of the five publications comprising the thesis, a narrower aspect of this puzzle is addressed. KW - Serbia; foreign policy analysis; nationalism; europeanisation Y1 - 2024 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:739-opus4-14702 ER - TY - INPR A1 - Klöpf, Tobias A1 - Wehner, Stefanie T1 - Vulnerabilities and capacities : dealing with coastal flooding in Ghana´s Volta Region N2 - Coastal flooding events pose an existential threat to populations around the world, particularly in the Global South. As a result of climate change and other, direct forms of anthropogenic interference, the magnitude and frequency of such floodings is predicted to continuously increase in the near future. Therefore, it is important to understand the vulnerability of affected people to implement appropriate measures. This research presents a case study on coastal flooding and its impact on livelihoods in the Volta Region of Ghana. The paper utilizes a vulnerability framework that focuses on exposure, susceptibility, as well as the capacities to anticipate, cope with, and recover from the effects of natural hazards. Based on a qualitative approach, the study focusses on those households who were directly affected of a severe tidal flood in November 2021, leading to a total destruction of their property. The research was conducted in March, July and August 2022. It revealed that the studied group had low capacity to anticipate and had no contingency plans in case of relocation. Further, we discovered different strategies that people applied to deal with the situation eight months after the flood event. Most households applied (short term) coping strategies to reestablish their former marine-based livelihood systems. Adaption in terms of long-term adjustment of their livelihoods played only a minor role and could be found in form of out-migration in a limited number of households. T3 - Migration, translocality and development in times of climate change. Mitra|WA Working Paper Series - 2 KW - Fishing community KW - Climate change adaption KW - Crisis migration KW - Displacement KW - Relocation Y1 - 2024 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:739-opus4-14597 IS - 2 CY - Passau ER - TY - JOUR A1 - Patil, Amit A1 - Ghasemi, Abdorasoul A1 - de Meer, Hermann T1 - Analysis of protection blinding in active distribution grids JF - IET Renewable Power Generation N2 - Protection blinding is a challenging issue in renewables-penetrated distribution grids and refers to a situation where a circuit breaker may not trip due to fault current contribution from distributed generation. This research addresses how the distributed generation location and capacity impact the operation of the circuit breaker in terms of the response time of the circuit breakers. The relative electrical distances of the faults and distributed generation to the circuit breakers are considered. The impact of distributed generation capacity considering the fault location is characterized using a new index called the heterogeneity index. The electrical distance between distributed generations and circuit breakers and the electrical distance between fault and circuit breaker is considered by a second new index called the electrical distance ratio. Data analysis on simulation results shows that these indices capture the phenomena of protection blinding caused by distributed generation. Results show that a higher distributed generation penetration and faults that are electri cally further away from a circuit breaker show severe cases of protection blinding captured by the indices. Furthermore, it is demonstrated how these indices can identify the worst impacted locations in the distribution grid. A key result is that protection blinding does not necessarily occur solely due to the presence of distributed generation between a circuit breaker and a fault, but is dependent on factors such as distributed generation location in the distribution grid, fault level, fault level distribution across the generation units and fault location. KW - General & introductory electrical electronics engineering Y1 - 2024 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:739-opus4-14661 ER - TY - THES A1 - Püllen, Dominik T1 - Holistic Security Engineering for Software-Defined Vehicles N2 - With the increasing use of digital technologies in the automotive sector, the traditional automobile is undergoing a structural transformation, requiring new technologies and enabling innovative mobility concepts. In particular, the ability to drive automatically or even fully autonomously, update control software, and remain connected to the environment allows attackers to infiltrate highly critical vehicle systems and take control without adequate protection. Once not only individual vehicles but entire fleets are dominated by software, cyberattacks could disrupt a significant portion of the infrastructure and expose passengers to substantial risks. This work follows a holistic approach to protecting highly automated software-defined vehicles from cyberattacks by designing and implementing security concepts in the main phases of a vehicle's lifecycle. We use SAE level 4 prototype vehicles to evaluate our proposed techniques. We start with a systematic security requirement analysis using the ISA-62443 standard series, demonstrating how threats can be identified in a collaborative, hierarchical process and how the resulting security risks impact the software and hardware architecture of a self-driving vehicle. We show how this analysis process results in concrete requirements whose consideration reduces the overall security risk to a tolerable level. Subsequently, we develop technical solutions for selected requirements. We begin by securing the CAN and FlexRay legacy protocols, which we foresee being used in specific areas of SDV in a transitional period despite technological changes. To enable vehicle-wide security management, we address the management and distribution of cryptographic keys within such networks, mainly focusing on resource-constrained devices. We propose using lightweight implicit certificates for deriving cryptographic group keys that can be used in CAN networks. Additionally, we demonstrate how the slot-based frame structure of the FlexRay protocol allows for efficient "multi-slot" authentication, for which we calculate cryptographic keys using hash-based key chains. SDV use Ethernet-based communication protocols and custom middleware stacks to transmit large amounts of data in real-time. We develop a three-stage security process for the novel ASOA, which enables the development and central orchestration of system-agnostic functional software components on embedded systems and HPC platforms. After the central specification of the security architecture at the data flow level, security tokens are automatically calculated and distributed for runtime protection of the service-oriented, DDS-based data transmission. Our process ensures the strict separation of function and system knowledge, allowing for cost-effective and adaptable security architecture management. The evaluation in four self-driving, software-defined vehicles demonstrates an average runtime overhead of approximately 5.71%. As the initial risk analysis and actual cyberattacks have shown, protective measures against the compromise of control units must be taken alongside communication security. To address this, we develop a method for verifying and validating the software integrity of control units. A governmental third party confirms a measurement through a digital certificate, proving the examined vehicle's trustworthiness and suitability for participation in automated traffic. In the final step of this work, we present an assessment scheme that allows software-defined vehicles to evaluate security incidents during operation in terms of their maximum expected damage and initiate appropriate countermeasures. We follow the ISO/SAE 21434 standard and model attack paths using a graph representing dependencies among internal vehicle assets to account for the propagation effects of cyberattacks. The assessment of a security incident considers not only the probability of individual attack paths but also the vehicle context. Our practical evaluation demonstrates that we can detect, report, and assess security incidents below the human reaction time in the earlier mentioned prototype vehicles. Y1 - 2024 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:739-opus4-14497 ER - TY - THES A1 - Donner, Eva Katharina T1 - 4 Essays on Sustainable Development and Organizations’ Response to Stakeholder’s Expectations N2 - As integral part of the society, environment, and economy, the organization’s survival and growth depend on legitimacy which reflects the social support and acceptance of its stakeholders, the institutions and individuals it interacts with. Organizations interact with internal and external stakeholder groups which not necessarily have the same legitimacy expectations. Due to several reasons, such as the adoption of new laws or the invention of new technologies, stakeholders’ expectations of legitimate actions can change in the course of time. Thus, to respond to changing stakeholder’s expectations, as integral part of a changing environment, is complex. The main objective of this dissertation is to answer the research question: “How do organizations respond to changing stakeholder’s expectations in context of sustainable development?”. Building on two empirical settings with four essays, this dissertation provides insights into organizations’ responses as reaction to changing stakeholder expectations with regard to sustainable development. In particular, it takes a closer look on the interplay between internal stakeholders, such as employees, and external stakeholders, such as politics or customers. The first essay summarizes the organizational factors for the implementation of a research data management (RDM) system within higher education institutes (HEI) and how they interact with each other. Based on Leavitt’s (1965) classical model of organizational change, the essay provides an overview about the interrelation between the individual components that make up an RDM system. The second essay investigates how early career researchers within HEI make use of different respond strategies to the state, market, professional, and community logic in context of RDM. It provides insights how employees deal with changing environmental conditions and the organization’s response to them. The third essay analyses the shift from voluntary to mandatory sustainability reporting and demonstrates different strategies organizations adopt to respond to it. The fourth essay incorporates the findings of the third essay and investigates which factors influence the organization’s strategy to respond. It focuses on the interface between the top management team and the chief executive officer. This dissertation makes at least two overall contributions to management and organization studies research. First, it emphasizes the role of different stakeholder groups and their impact on the organizations’ activities. Second, this dissertation shows the value of connecting different theoretical approaches such as institutional logics, upper echelon theory, and organizational transparency research in context of organizational legitimacy and demonstrates that a nuanced view is necessary to understand the concept of organizational legitimacy. This cumulative dissertation is structured as follows. Part A is an introduction to the study organizational legitimacy. Part B contains the four essays. KW - Legitimacy KW - Strategisches Management Y1 - 2024 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:739-opus4-14516 ER - TY - THES A1 - Fritz, Manuela T1 - Health challenges of the 21st century - Empirical essays on the health and economic burden of non-communicable diseases and climate change in Southeast Asia N2 - In the ongoing 21st century, low- and middle-income countries will face two health challenges that are thoroughly different from what these countries have been dealing with in preceding centuries. First, they are confronted with surging rates of non-communicable diseases (NCDs), and second, climate change will take its toll and is predicted to cause catastrophic health impairments and exacerbate chronic health conditions further. Both will pose a disproportionate health and economic burden on low- and middle-income countries, which are also the countries least able to cope with them. By threatening individual health and socioeconomic improvements, and by putting an immense burden on already constrained health care systems, they impede the progress in poverty reduction and widen health inequities between the rich and the poor. Against this background, this thesis investigates the potential of NCD prevention and treatment measures in the context of Southeast Asia, with case studies in Indonesia. Specifically, it seeks to understand what kind of health interventions have the potential to be (cost-)effective considering the cultural background, lifestyle, health literacy and health system capacities in the region. Further, this thesis analyzes the interplay between NCDs and climate change and assesses the financial burden that both might pose in the decades to come. Hence, this thesis contributes to a better understanding of how the two health challenges of the 21st century, NCDs and climate change, can be addressed in the context of Southeast Asia and offers insights into what type of health policies and interventions can play a supportive role. KW - Health KW - Climate change KW - Non-communicable diseases KW - Southeast Asia Y1 - 2023 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:739-opus4-12649 ER - TY - THES A1 - Alhamzeh, Alaa T1 - Language Reasoning by means of Argument Mining and Argument Quality N2 - Understanding of financial data has always been a point of interest for market participants to make better informed decisions. Recently, different cutting edge technologies have been addressed in the Financial Technology (FinTech) domain, including numeracy understanding, opinion mining and financial ocument processing. In this thesis, we are interested in analyzing the arguments of financial experts with the goal of supporting investment decisions. Although various business studies confirm the crucial role of argumentation in financial communications, no work has addressed this problem as a computational argumentation task. In other words, the automatic analysis of arguments. In this regard, this thesis presents contributions in the three essential axes of theory, data, and evaluation to fill the gap between argument mining and financial text. First, we propose a method for determining the structure of the arguments stated by company representatives during the public announcement of their quarterly results and future estimations through earnings conference calls. The proposed scheme is derived from argumentation theory at the micro-structure level of discourse. We further conducted the corresponding annotation study and published the first financial dataset annotated with arguments: FinArg. Moreover, we investigate the question of evaluating the quality of arguments in this financial genre of text. To tackle this challenge, we suggest using two levels of quality metrics, considering both the Natural Language Processing (NLP) literature of argument quality assessment and the financial era peculiarities. Hence, we have also enriched the FinArg data with our quality dimensions to produce the FinArgQuality dataset. In terms of evaluation, we validate the principle of ensemble learning on the argument identification and argument unit classification tasks. We show that combining a traditional machine learning model along with a deep learning one, via an integration model (stacking), improves the overall performance, especially in small dataset settings. In addition, despite the fact that argument mining is mainly a domain dependent task, to this date, the number of studies that tackle the generalization of argument mining models is still relatively small. Therefore, using our stacking approach and in comparison to the transfer learning model of DistilBert, we address and analyze three real-world scenarios concerning the model robustness over completely unseen domains and unseen topics. Furthermore, with the aim of the automatic assessment of argument strength, we have investigated and compared different (refined) versions of Bert-based models that incorporate external knowledge in the decision layer. Consequently, our method outperforms the baseline model by 13 ± 2% in terms of F1-score through integrating Bert with encoded categorical features. Beyond our theoretical and methodological proposals, our model of argument quality assessment, annotated corpora, and evaluation approaches are publicly available, and can serve as strong baselines for future work in both FinNLP and computational argumentation domains. Hence, directly exploiting this thesis, we proposed to the community, a new task/challenge related to the analysis of financial arguments: FinArg-1, within the framework of the NTCIR-17 conference. We also used our proposals to react to the Touché challenge at the CLEF 2021 conference. Our contribution was selected among the «Best of Labs». KW - NLP, Argument Mining, Argument Quality Assessment, Financial Argumentation, Earnings Conference Calls Y1 - 2023 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:739-opus4-12699 ER - TY - JOUR A1 - Donner, Eva Katharina T1 - Research data management systems and the organization of universities and research institutes: A systematic literature review JF - Journal of Librarianship and Information Science N2 - New technological developments, the availability of big data, and the creation of research platforms open a variety of opportunities to generate, store, and analyze research data. To ensure the sustainable handling of research data, the European Commission as well as scientific commissions have recently highlighted the importance of implementing a research data management system (RDMS) in higher education institutes (HEI) which combines technical as well as organizational solutions. A deep understanding of the requirements of research data management (RDM), as well as an overview of the different stakeholders, is a key prerequisite for the implementation of an RDMS. Based on a scientific literature review, the aim of this study is to answer the following research questions: “What organizational factors need to be considered when implementing an RDMS? How do these organizational factors interact with each other and how do they constrain or facilitate the implementation of an RDMS?” The structure of the analysis is built on the four components of Leavitt’s classical model of organizational change: task, structure, technology, and people. The findings reveal that the implementation of RDMS is strongly impacted by the organizational structure, infrastructure, labor culture as well as strategic considerations. Overall, this literature review summarizes different approaches for the implementation of an RDMS. It also identifies areas for future research. KW - Data handling KW - information infrastructure KW - organization KW - organizational change KW - research data management KW - research data management system Y1 - 2022 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:739-opus4-12654 SN - 0961-0006 SN - 1741-6477 VL - 55 IS - 2 SP - 261 EP - 281 PB - SAGE Publications CY - Sage UK: London, England ER - TY - JOUR A1 - Sengl, Michael A1 - Heinke, Elfi T1 - Teaching Journalism Literacy in Schools: The Role of Media Companies as Media Educators in Germany JF - Media and Communication N2 - German journalism is facing major challenges including declining circulation, funding, trust, and political allegations of spreading disinformation. Increased media literacy in the population is one way to counter these issues and their implications. This especially applies to the sub‐concept of journalism literacy, focusing on the ability to consume news critically and reflectively, thus enabling democratic participation. For media companies, promoting journalism literacy seems logical for economic and altruistic reasons. However, research on German initiatives is scarce. This article presents an explorative qualitative survey of experts from seven media companies offering journalistic media education projects in German schools, focusing on the initiatives’ content, structure, and motivation. Results show that initiatives primarily aim at students and teachers, offering mostly education on journalism (e.g., teaching material) and via journalism (e.g., journalistic co‐production with students). While these projects mainly provide information on the respective medium and journalistic practices, dealing with disinformation is also a central goal. Most initiatives are motivated both extrinsically (e.g., reaching new audiences) and intrinsically (e.g., democratic responsibility). Despite sometimes insufficient resources and reluctant teachers, media companies see many opportunities in their initiatives: Gaining trust and creating resilience against disinformation are just two examples within the larger goal of enabling young people to be informed and opinionated members of a democratic society. KW - disinformation KW - journalism literacy KW - ournalistic media education KW - media literacy KW - news media literacy Y1 - 2023 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:739-opus4-12499 VL - volume 11 IS - issue 2 SP - 53 EP - 63 PB - Cogitatio Press CY - Lisbon, Portugal ER - TY - THES A1 - Graßl, Isabella T1 - Diversity in Programming Education: Effects of Topic and Group Constellation on Young Programming Novices N2 - The field of software engineering faces a significant diversity crisis, characterized by a critical lack of heterogeneity despite ongoing efforts to promote gender equality. The persistent male dominance in this domain has created an urgent need for more heterogeneous groups in software engineering. This lack of diversity not only hinders underrepresented groups from entering the field but also prevents them from gaining initial programming experiences, which are a core component of software engineering and essential for developing computational thinking. To address this crisis and its implications, early interventions are key in shaping positive perceptions, building confidence, and sparking initial interest in programming among underrepresented groups before societal stereotypes of programming as a nerdy field manifests. This means starting with basic programming courses for children and continuing through to first-year university students in order to foster technical skills and computational thinking, alongside creativity and collaboration. However, there is limited understanding of how introductory programming course designs impact diversity-dependent characteristics to create welcoming and learning-friendly environments. This understanding is particularly important for underrepresented groups, especially girls, to benefit from their first programming experiences as they are often hindered by the initial perception of programming as (1) abstract and unappealing, and (2) non-social to novices. Engaging, creative, and relatable topics in programming courses might demystify complex programming concepts, making them more accessible, less intimidating, and appealing. However, understanding programming is not just about the content---it is also about the context in which it is learned. Introducing programming as social activity is important, particularly for young learners. By emphasizing team work, we might encourage collaboration and peer support, counteracting the lone-wolf programmer stereotype. Therefore, this doctoral thesis investigates the effects of both key aspects in programming courses---(1) topic choices and (2) group constellations---on young programming novices. The aim is to provide a holistic understanding of how different course designs can support diverse learners and promote gender equality in programming education. While this research primarily addresses gender diversity due to the persistent gender gap in software engineering, it also examines additional diversity dimensions, including age, ethnicity, prior programming experience, disabilities, and educational background. A total of 13 studies were conducted within this thesis, examining the current state of educational settings and utilizing various introductory programming courses designed for children aged 8 to 18, as well as first-year university students. These studies employed different programming environments, such as Scratch and Sonic Pi, and incorporated a variety of topics and group constellations to observe their effects on student outcomes. By using a mixed-methods design, data were gathered through surveys, observations, and both data-driven and manual code analysis. Key findings reveal that it is particularly noteworthy how children utilize the programming environment to engage with and creatively express topics aligned with their interests which also align mostly with gender-stereotypes, including elements from internet and popular culture as well as socio-cultural narratives. However, gender-sensitive and neutral topic choices enhance engagement, self-efficacy, contribution, code quality and creative output, while also contributing to reduce stereotypical beliefs about programming, particularly among girls. In line with the findings for the course topic, group constellations also influence programming experiences. In particular, introducing pair programming in courses shows a promising approach for young learners, but attention must be paid to mitigate socially learned gender-stereotypical behaviours. Another finding indicates that, unlike professional software teams, mixed-diverse student teams often encounter substantial challenges, thus benefit from clear communication guidelines and supportive environments to promote better collaboration. This doctoral thesis concludes with guidelines for designing more effective and inclusive introductory programming courses. These recommendations include using gender-sensitive course materials, allowing for creative freedom through topic choices while encouraging the use of advanced programming concepts, promoting collaboration through pair programming while fostering enhanced communication, boosting self-efficacy with quick positive feedback for girls in particular, and providing emotional support for underrepresented groups. By following these guidelines, educators can create more engaging, inclusive, and effective programming courses. This may ultimately promote a more equitable and diverse future generation of professional software developers while also fostering computational thinking, encouraging a broader interest in programming among all young learners. KW - Softwareentwicklung KW - Lernsituation Y1 - 2024 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:739-opus4-15049 ER - TY - THES A1 - Berger, Christian T1 - Towards Fast and Adaptive Byzantine State Machine Replication for Planetary-Scale Systems N2 - State machine replication (SMR) is a classical approach for building resilient distributed systems. In Byzantine fault-tolerant (BFT) systems, no concrete assumptions are made about the behavior of faulty replicas. With the advancement of distributed ledger technologies (DLT), planetary-scale BFT SMR ist becoming practical and necessary as it can serve as a consensus primitive to keep the ledger consistent. In our view, the alignment of BFT SMR to DLT brings new challenges, for instance the scalability aspect, where recent research works less frequently address latency improvements than throughput improvements. Further challenges include the geographic dispersion of replicas within a planetary-scale system and the need of a BFT SMR protocol to react to environmental changes during runtime. This thesis has the objective to improve BFT SMR for planetary-scale systems by lowering the protocol latency observed by clients and by making the BFT SMR system adaptive, i.e., enabling replicas to react to perceived changes such as changing network characteristics or faulty replicas. As a first contribution of this thesis, we discover that fast, consensus-free (read-only) operations is a flawed optimization in seminal BFT SMR frameworks, such as PBFT and BFT-SMaRt. We explain how the read-only optimization can violate the protocol's liveness by showing an attack and then present a solution that makes the overall, optimized protocol both live and linearizable. The second contribution is Adaptive Wide-Area Replication (AWARE), which enables a geo-replicated system to adapt to its environment, thus improving the geographical scalability of consensus if replicas are dispersed across the world. Essentially, AWARE is an automated and dynamic voting-weight tuning and leader positioning scheme, which supports the emergence of fast consensus quorums in the system and builds upon previous work, the WHEAT protocol. AWARE combines reliable self-monitoring with a consensus latency prediction model, thus striving to minimize the system’s consensus latency at runtime, which subsequently results in latency improvements observed by clients scattered across the globe, which we validate through experiments. The third contribution presents FlashConsensus, a protocol derived from AWARE, that also adjusts the resilience threshold. The core idea is the tentative use of a lower resilience threshold which leads to smaller consensus quorums and thus consensus acceleration in common-case scenarios where we expect only few faulty replicas. FlashConsensus achieves threat-level awareness through the incorporation of two modes of operation and BFT forensic support and guarantees liveness and linearizability under optimal resilience. Moreover, FlashConsensus allows for client-side speculation by using incremental consistency guarantees to further lower request latency. Additionally, we investigate on the question whether we can reason about the performance of large-scale systems utilizing simulations. We discover, that we can faithfully forecast the performance of BFT protocols by plugging real protocol implementations into a high-performance network simulator. For instance, simulation results reveal that, using 51 replicas scattered across the planet, FlashConsensus can finalize operations in less than 0.4 s, which is half of the time required for a PBFT-like protocol in the same network, and matching the latency of this protocol running on the best possible internet links (transmitting at 67% of the speed of light). N2 - Die Zustandsmaschinenreplikation (ZMR) ist ein klassischer Ansatz für zuverlässige verteilte Systeme. In Byzantinischen fehlertoleranten (BFT) Systemen werden keine konkreten Annahmen über das Verhalten von fehlerhaften Replikaten gemacht. Mit dem Voranschreiten der sog. „Distributed Ledger Technologien“ (DLT) wird planetare BFT ZMR praktikabel und notwendig, da sie als Konsensusprimitiv dienen kann, um die Konsistenz einer Blockchain aufrechtzuerhalten. Unserer Ansicht nach bringt die Ausrichtung von BFT ZMR an DLT neue Herausforderungen mit sich, z.B. den Skalierbarkeitsaspekt, bei dem jüngste Forschungsarbeiten seltener Latenzverbesserungen als Durchsatzverbesserungen untersuchen. Weitere Herausforderungen umfassen die geografische Verteilung von Replikaten innerhalb eines planetaren Systems sowie die Notwendigkeit eines BFT ZMR Protokolls während der Laufzeit auf Veränderungen zu reagieren. Diese Dissertation verfolgt das Ziel, die BFT ZMR für planetare Systeme durch Senkung der von Clients beobachteten Protokolllatenz zu verbessern und die BFT ZMR-Systeme anpassungsfähig zu machen, indem Replikate auf wahrgenommene Änderungen wie sich ändernde Netzwerkcharakteristiken oder fehlerhafte Replikate reagieren können. Als erster Beitrag dieser Dissertation zeigen wir, dass schnelle, konsensusfreie (nur-lesende) Operationen in grundlegenden BFT ZMR Protokollen, wie PBFT und BFT-SMaRt, eine fehlerhafte Optimierung sind. Wir erklären, wie die nur-lesende Optimierung die Liveness (Verfügbarkeit von Operationen) des Protokolls verletzen kann, indem wir einen Angriff präsentieren und dann eine Lösung vorschlagen, die das insgesamt optimierte Protokoll sowohl live (verfügbar) als auch linearisierbar („linearizable“ -- streng konsistent) macht. Der zweite Beitrag ist Adaptive Wide-Area Replication (AWARE), mit der ein geo-repliziertes System sich an seine Umgebung anpassen kann und damit die geografische Skalierbarkeit des Konsensus verbessert, wenn Replikate auf der ganzen Welt verteilt sind. Im Wesentlichen ist AWARE ein automatisches und dynamisches Stimmgewichtseinstellungs- und Anführerpositionierungs-schema, das die Entstehung schneller Konsensusquoren im System unterstützt und auf früheren Arbeiten, wie dem WHEAT-Protokoll, aufbaut. AWARE kombiniert zuverlässige Selbstüberwachung mit einem Konsensuslatenzvorhersagemodell und strebt danach, die Konsensuslatenz des Systems zur Laufzeit zu minimieren, was letztendlich zu Latenzgewinnen führt, die von Clients auf der ganzen Welt beobachtbar sind, was wir durch Experimente bestätigen. Der dritte Beitrag stellt FlashConsensus vor, ein Protokoll, das aus AWARE abgeleitet ist und auch die Resilienzschwelle anpasst. Die Kernidee ist die vorübergehende Verwendung einer niedrigeren Resilienzschwelle, die zu kleineren Konsensusquoren und damit zu einer Beschleunigung des Konsensus in häufigen Fällen führt, in denen nur wenige fehlerhafte Replikate erwartet werden. FlashConsensus erkennt und reagiert auf Bedrohungen durch die Einbeziehung von zwei Betriebsarten und BFT-Forensikunterstützung und garantiert Liveness sowie Konsistenz unter optimaler Resilienz. Darüber hinaus ermöglicht es die Spekulation auf Clientseite durch die Verwendung inkrementeller Konsistenzgarantien, um die Clientlatenz weiter zu senken. Zusätzlich werden wir uns mit der Frage beschäftigen, ob wir die Performanz von groß-skalierten Systemen mittels Simulationen beurteilen können. Wir stellen fest, dass wir die Performanz von BFT Protokollen durch das Einstöpseln von echten Protokollimplementierungen in einen hochleistungsfähigen Netzwerksimulator zuverlässig vorhersagen können. Beispielsweise zeigen Simulationen, dass FlashConsensus mit 51 Replikaten, die auf der ganzen Welt verteilt sind, Operationen in weniger als 0,4 s linearisierbar verarbeiten kann, was die Hälfte der Zeit ist, die für ein PBFT-ähnliches Protokoll im gleichen Netzwerk erforderlich ist und ähnlich schnell ist wie dieses Protokoll mit bestmöglichen Internetverbindungen (Übertragung mit 67% der Lichtgeschwindigkeit). KW - Byzantine fault tolerance KW - state machine replication KW - consensus KW - adaptiveness KW - planetary-scale Y1 - 2024 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:739-opus4-15059 ER - TY - THES A1 - Sentanoe, Stewart T1 - VMIaaS: Virtual Machine Introspection as a Service N2 - In this digital era, communication in the digital world is becoming part of our daily lives. One key technology that becomes part of this digital transformation is cloud computing. It allows users to have a running system as a virtual machine (VM) on the cloud without owning a physical server. Unfortunately, adversaries can also use those systems to conduct criminal activities. Therefore, developing a method to extract evidence from those systems is also necessary. One way is through digital forensics, and one method to do digital forensics of a VM is using virtual machine introspection (VMI). However, VMI has yet to be made available by any public cloud provider. This thesis addresses this issue by introducing methods for deploying VMI on public cloud providers. Four main challenges have to be solved. Firstly, VMI requires access to the hypervisor, which practically can access all VMs running on the same server. This leads to security and privacy issues where customers can introspect each other VMs. To solve this problem, this thesis introduces KVMIveggur, a versatile access control of VMI. It comes with different options that every customer can choose from based on their needs. Secondly, VMI introduces overhead to the running VM. This is because most of the introspection mechanisms perform data access to the monitored VM. Performing data access on a running VM can cause data inconsistency. Hence, pausing the VM before executing the data access is better. However, when the VM pausing frequency is high, it will affect the performance of the monitored VM. The current state-of-the-art techniques use caching to reduce the VM pausing frequency. However, it faces a problem: the cached data may be outdated compared to the actual data. Therefore, this thesis introduces VMIFresh, a better caching mechanism. We leverage both active and passive tracing mechanisms to ensure high performance and consistency of the data (freshness). Thirdly, many state-of-the-art VMI libraries and applications run perfectly only on Intel processors because Intel CPUs provide the best hardware support for VMI. However, AMD and ARM processors are getting more popular in cloud computing. Thus, it is necessary to retrofit VMI capabilities to support AMD and ARM processors. This thesis describes the requirements to employ VMI on AMD and ARM processors. We also provide the implementation of those requirements. Finally, to do introspection using VMI, it is crucial to have proper symbol information (layout and location of data structures) of the introspected operating system (OS) and user applications. While many existing VMI approaches concentrate primarily on analyzing OS data structures, analyzing user application data often receives no attention. In our approach, we address this gap by focussing on application-level introspection. We have identified several use cases that require this kind of introspection. We focus on cryptographic key extraction for two specific instances: secure shell (SSH) and transport layer security (TLS) by leveraging the power of machine learning techniques to locate those keys in the main memory effectively and efficiently. After we had solved those challenges, we combined a couple of our approaches and introduced two VMI applications: Sarracenia and VMIGuard. Sarracenia is a deception technology that tracks activities done on an SSH session. The main goal of Sarracenia is to attract adversaries away from the production system and learn about their behavior. On the other hand, VMIGuard also monitors the SSH traffic. But, it specifically monitors the activity of any git-related activities. The main goal of VMIGuard is to ensure the integrity of the hosted data from any internal malicious actor. KW - Cloud Computing KW - Computersicherheit Y1 - 2024 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:739-opus4-15027 ER - TY - THES A1 - Ghaffar, Abdul Muqeet T1 - Understanding Individuals’ Willingness for Prosocial Data Disclosure: Exploring Antecedents and Investigating Strategies for its Promotion N2 - Privacy research has traditionally focused on understanding individuals' behavior in disclosing personal data by assuming that individuals disclose their data mainly out of self-interest. However, in many contexts, individuals disclose their data primarily for the benefit of others and society, thereby showing a form of prosocial behavior. This dissertation conceptualizes these types of data disclosure as prosocial data disclosures and argues that existing privacy research frameworks, such as the privacy calculus, have not been sufficiently applied in privacy research and need to be reevaluated to fully capture the complexities of prosocial data disclosures. Despite the growing relevance of understanding individuals’ willingness for prosocial data disclosures, existing research in this field is limited. This dissertation consists of four essays that seek to deepen the understanding of the underlying decision-making processes of individuals by exploring the antecedents and investigating strategies that promote prosocial data disclosure. By employing different research methods, including systematic literature reviews, qualitative and quantitative surveys, interviews, workshops, and conjoint analysis, this dissertation contributes to the identification of the multifaceted antecedents of prosocial data disclosure which can be classified into different drivers and barriers. Furthermore, by integrating insights from different disciplines such as behavioral economics, social psychology, and information systems research, this dissertation provides empirical evidence for the use of message framing and the deliberate emphasis on impact uncertainty as two promising strategies in promoting prosocial data disclosure. The findings derived from all four essays inform privacy research and prosocial behavior research about the need for sophisticated theories that are capable of better capturing the complexities of prosocial data disclosure. Additionally, the findings offer practical implications for designing ethically responsible data disclosure practices while respecting individual privacy rights. KW - privacy KW - behavioral economics KW - social psychology KW - message framing KW - impact uncertainty Y1 - 2024 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:739-opus4-15001 ER - TY - THES A1 - Masselus, Lise T1 - Evaluating Poverty Alleviation: Essays on Microfinance, Energy Access and Limits to the Gold Standard in Empirical Economics N2 - In my dissertation, I combine topical contributions on microfinance and energy access, two prevalent poverty alleviation policies, with methodological contributions on how empirical economics research can contribute to effective policymaking. Chapter 1 reviews the existing experimental evidence on microfinance. We use this deep literature to highlight challenges in generalizing from empirical research. Chapter 2 and 3 provide empirical insights on the energy access-poverty nexus. We study the long-term adoption of grid electrification and evaluate whether productive use can foster adoption and impact. Chapter 4 addresses data quality, an essential yet often overlooked element in research and policymaking. This introduction provides a general overview on microfinance, energy access, and methodological critiques on common practices in empirical economics research. [from the introduction] KW - energy access KW - microfinance KW - meta-science KW - survey methods Y1 - 2024 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:739-opus4-14981 ER - TY - JOUR A1 - Deiner, Adina A1 - Feldmeier, Patric A1 - Fraser, Gordon A1 - Schweikl, Sebastian A1 - Wang, Wengran T1 - Automated test generation for SCRATCH programs JF - Empirical Software Engineering N2 - The importance of programming education has led to dedicated educational program- ming environments, where users visually arrange block-based programming constructs that typically control graphical, interactive game-like programs. The SCRATCH programming environment is particularly popular, with more than 90 million registered users at the time of this writing. While the block-based nature of S CRATCH helps learners by preventing syntactical mistakes, there nevertheless remains a need to provide feedback and support in order to implement desired functionality. To support individual learning and classroom settings, this feedback and support should ideally be provided in an automated fashion, which requires tests to enable dynamic program analysis. In prior work we introduced W HISKER , a framework that enables automated testing of S CRATCH programs. However, creating these automated tests for S CRATCH programs is challenging. In this paper, we therefore investigate how to automatically generate W HISKER tests. Generating tests for S CRATCH raises important challenges: First, game-like programs are typically randomised, leading to flaky tests. Second, S CRATCH programs usually consist of animations and interactions with long delays, inhibiting the application of classical test generation approaches. Thus, the new application domain raises the question of which test generation technique is best suited to produce high coverage tests capable of detecting faulty behaviour. We investigate these questions using an extension of the W HISKER test framework for automated test generation. Evaluation on common programming exercises, a random sample of 1000 S CRATCH user programs, and the 1000 most popular S CRATCH programs demonstrates that our approach enables W HISKER to reliably accelerate test executions, and even though many SCRATCH programs are small and easy to cover, there are many unique challenges for which advanced search-based test generation using many-objective algorithms is needed in order to achieve high coverage. KW - Search-based testing KW - Block-based programming KW - SCRATCH Y1 - 2023 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:101:1-2023091108301581209964 VL - 28 IS - 3 SP - 1 EP - 63 PB - Springer Nature CY - Berlin ER - TY - JOUR A1 - Narh, John T1 - The resource curse and the role of institutions revisited JF - Environment, Development and Sustainability N2 - Many studies have shown that natural resource abundant countries with strong institutions tend to escape the resource curse. Institutional quality has been examined using broad indices of rule of law, the rate of murder, the share of the shadow economy and provision of public goods. Nonetheless, we need to locate the specific institutional conditions under which the curse manifests since some “rule of law” countries like Nigeria and Angola are generally classified as resource cursed. In this review, I argue that managing and distributing natural resource wealth through a centralised planning strategy and lack of a binding long-term national development plan are institutional conditions that encourage government unaccountability as they do not restrict policy makers against discretionary distribution of natural resource windfall, rent seeking, clientelism and corruption which contribute to poor economic development and growth. Also, inadequate regulations on how to address the potential or actual impacts of natural resource extraction on the livelihood of local people and the environment tend to precipitate grievance-induced resource conflict. KW - Resource curse KW - Government accountability KW - Institutions KW - Natural resource KW - conflict KW - Natural resource windfall KW - Financial development Y1 - 2023 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:101:1-2024030609203689018522 VL - 27 SP - 8187 EP - 8207 PB - Springer Nature CY - Berlin ER - TY - JOUR A1 - Ertel, Florence A1 - Donig, Simon A1 - Eckl, Markus A1 - Gassner, Sebastian A1 - Göler, Daniel A1 - Rehbein, Malte T1 - Using web archives for an explorative study of the web presence of German parties during the European election 2019 JF - Quality & Quantity N2 - In the digital age, political science is faced with a shift of election campaigns and politi- cal discourse to digital or virtual arenas. Because the internet is a highly volatile medium and online content can become inaccessible after the campaign season, new challenges for research arise as well as the need for the preservation of online content. Moreover, the sheer volume of data researchers have to deal with has reached levels where traditional methods are being highly challenged. This paper puts forth a web harvesting workflow with a strong focus on granular extraction of unstructured information (publication dates) for automated analysis. As our approach is methodological, we would like to point out the benefits that researches in political science may draw from adapting our methodology. We demonstrate this by analysing an event-based web crawl of German parties participating in the election campaign for the European Parliamentary Election in 2019. We employ distant reading methods to generate topic models, which are subsequently evaluated by hermeneutic analysis of a subset of the data. KW - Web archives KW - European parliamentary election KW - Second order elections KW - Distant reading KW - Topic modelling Y1 - 2023 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:101:1-2023082609050515725791 VL - 58 IS - 1 SP - 603 EP - 625 PB - Springer Nature CY - Berlin ER - TY - JOUR A1 - Piwoni, Eunike A1 - Mußotter, Marlene T1 - The evolution of the civic–ethnic distinction as a partial success story: Lessons for the nationalism–patriotism distinction JF - Nations and Nationalism N2 - This article brings, for the first time, two of the most pivotal distinctions in nationalism studies into extended dialogue: the civic–ethnic distinction (CED) and the nationalism–patriotism distinction (NPD). By reviewing both the evolution of those distinctions over the previous decades and the ways in which they have been used in quantitative empirical research, we argue that the CED's evolution has been a partial success story, whereas discourse around the NPD has not seen substantial development. Despite lingering inconsistencies, researchers drawing on the CED have been successful in addressing different lines of critique and in using the CED as a heuristic for investigating notions of nationhood as expressed in public perceptions. In contrast, there has been only limited dialogue between theoretical and empirical approaches to the NPD. The article illustrates how research drawing on the NPD could profit from the CED's evolution. We close by providing a conceptual roadmap to guide the path towards more terminological clarity and to construct more theoretically robust measures for nationalism and patriotism. We specifically suggest that nationalism and patriotism should be consistently understood as ideal types that citizens can simultaneously hold to varying degrees. KW - civic nationalism KW - civic–ethnic distinction KW - ethnic–civic KW - national attachments KW - nationalism–patriotism distinction KW - nationhood KW - national identity KW - political psychology KW - surveys Y1 - 2023 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:739-opus4-16266 VL - 29 IS - 3 SP - 906 EP - 921 PB - Wiley CY - Hoboken ER - TY - JOUR A1 - Schwartz, Niels T1 - Topology of closure systems in algebraic lattices JF - Algebra universalis N2 - Algebraic lattices are spectral spaces for the coarse lower topology. Closure systems in algebraic lattices are studied as subspaces. Connections between order theoretic properties of a closure system and topological properties of the subspace are explored. A closure system is algebraic if and only if it is a patch closed subset of the ambient algebraic lattice. Every subset X in an algebraic lattice P generates a closure system〈X〉P . The closure system〈Y 〉P generated by the patch closure Y of X is the patch closure of〈X〉P. If X is contained in the set of nontrivial prime elements of P then〈X〉P is a frame and is a coherent algebraic frame if X is patch closed in P. Conversely, if the algebraic lattice P is coherent then its set of nontrivial prime elements is patch closed. KW - Poset KW - Complete lattice KW - Algebraic lattice KW - Frame KW - Closure system KW - Closure operator KW - Spectral space KW - Specialization KW - Coarse lower topology KW - Scott topology KW - Patch topology Y1 - 2023 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:101:1-2023090808111682406614 VL - 84 IS - 2 SP - 1 EP - 33 PB - Springer Nature CY - Berlin ER - TY - JOUR A1 - Münch, Miriam A1 - Rutter, Ignaz A1 - Stumpf, Peter T1 - Partial and Simultaneous Transitive Orientations via Modular Decompositions JF - Algorithmica N2 - A natural generalization of the recognition problem for a geometric graph class is the problem of extending a representation of a subgraph to a representation of the whole graph. A related problem is to find representations for multiple input graphs that coin- cide on subgraphs shared by the input graphs. A common restriction is the sunflower case where the shared graph is the same for each pair of input graphs. These problems translate to the setting of comparability graphs where the representations correspond to transitive orientations of their edges. We use modular decompositions to improve the runtime for the orientation extension problem and the sunflower orientation problem to linear time. We apply these results to improve the runtime for the partial represen- tation problem and the sunflower case of the simultaneous representation problem for permutation graphs to linear time. We also give the first efficient algorithms for these problems on circular permutation graphs. KW - Representation extension KW - Simultaneous representation KW - Comparability KW - graph KW - Permutation graph KW - Circular permutation graph KW - Modular decomposition Y1 - 2023 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:101:1-2024022914111908687000 VL - 86 IS - 4 SP - 1263 EP - 1292 PB - Springer Nature CY - Berlin ER - TY - JOUR A1 - Trautsch, Alexander A1 - Herbold, Steffen A1 - Grabowski, Jens T1 - Are automated static analysis tools worth it? An investigation into relative warning density and external software quality on the example of Apache open source projects JF - Empirical Software Engineering N2 - Automated Static Analysis Tools (ASATs) are part of software development best practices. ASATs are able to warn developers about potential problems in the code. On the one hand, ASATs are based on best practices so there should be a noticeable effect on software quality. On the other hand, ASATs suffer from false positive warnings, which developers have to inspect and then ignore or mark as invalid. In this article, we ask whether ASATs have a measurable impact on external software quality, using the example of PMD for Java. We investigate the relationship between ASAT warnings emitted by PMD on defects per change and per file. Our case study includes data for the history of each file as well as the differences between changed files and the project in which they are contained. We investigate whether files that induce a defect have more static analysis warnings than the rest of the project. Moreover, we investigate the impact of two different sets of ASAT rules. We find that, bug inducing files contain less static analysis warnings than other files of the project at that point in time. However, this can be explained by the overall decreasing warning density. When compared with all other changes, we find a statistically significant difference in one metric for all rules and two metrics for a subset of rules. However, the effect size is negligible in all cases, showing that the actual difference in warning density between bug inducing changes and other changes is small at best. KW - Static code analysis KW - Quality evolution KW - Software metrics KW - Software quality Y1 - 2023 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:101:1-2023091108203018898026 VL - 28 IS - 3 SP - 1 EP - 21 PB - Springer Nature CY - Berlin ER - TY - JOUR A1 - Frühwirth, Lorenz A1 - Prochno, Joscha T1 - Hölder’s inequality and its reverse — a probabilistic point of view JF - Mathematische Nachrichten N2 - In this article, we take a probabilistic look at Hölder's inequality, considering the ratio of terms in the classical Hölder inequality for random vectors in ℝ𝑛. We prove a central limit theorem for this ratio, which then allows us to reverse the inequality up to a multiplicative constant with high probability. The models of randomness include the uniform distribution on 𝓁𝑛𝑝 balls and spheres. We also provide a Berry–Esseen–type result and prove a large and a moderate deviation principle for the suitably normalized Hölder ratio. KW - Berry–Esseen bound KW - central limit theorem KW - Hölder’s inequality KW - 𝓁 𝑛 𝑝 ball KW - large deviation principle KW - moderate deviation principle KW - reverse inequality Y1 - 2023 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:101:1-2023062315175042989607 VL - 296 IS - 12 SP - 5493 EP - 5512 PB - Wiley CY - Hoboken ER - TY - JOUR A1 - Sommer, Tim T1 - Romantic objects, Victorian collections : scribal relics and the authorial body JF - Literature Compass N2 - Over the course of the nineteenth century, literary manuscripts came to be seen as tangible evidence of the creative process and as a key to the personality of the author. The material traces of writing were understood to outlive their creators and promise to resurrect the authorial body through the magic of the relic. This article reconstructs how authorial script gradually transformed into a collectible object pursued as a memento and a commodity. Letters, drafts, and fair copies by major modern writers found their way into the collections of British aristocrats and American industrialists at the same time that hunting for literary autographs diversified into a middle-class pursuit. Surveying recent scholarship on nineteenth-century collecting and material culture, the essay offers a condensed cultural history of the literary manuscript as a collectible and draws attention to how collectors and collecting feature in fictional texts of the period. It focuses on the artefactual mobility and custodial afterlives of Romantic papers in Victorian literature and culture, exploring a form of collecting which crossed boundaries between periods and national literary traditions. KW - archive KW - authorship KW - collecting KW - literary manuscripts KW - relics KW - Romanticism KW - Victorianism Y1 - 2023 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:739-opus4-16248 VL - 21 IS - 1-3 PB - Wiley CY - Hoboken ER - TY - THES A1 - Rose, Julian T1 - Poor Economics and the Long Term: Empirical Essays on Energy and Economic Poverty N2 - This dissertation explores different aspects of poverty specific to urban and rural areas. The first two chapters examine energy access for poor urban households, emphasizing the need for effective energy policies that ensure access while considering environmental and climate impacts. The final two chapters analyze the long-term effects of transfer programs targeting poor rural households, aiming to overcome poverty traps. The dissertation expands the methodological toolkit typically used in economics, addressing increasing concerns about the generalizability of experimental results, the narrow focus of research question in causal research, and the credibility crisis of empirical research. KW - Armut KW - Energieversorgung KW - Stadt KW - Ländlicher Raum KW - Wirtschaftshilfe Y1 - 2024 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:739-opus4-15124 ER - TY - THES A1 - Hofstadler, Julian T1 - Qualitative and quantitative convergence results for randomised integration methods N2 - In this thesis different randomised integration methods based on either, randomised Quasi-Monte Carlo, or (adaptive) Markov chain Monte Carlo methods are studied. Depending on the underlying integration problem we show qualitative and quantitative results, which ensure the asymptotic correctness of an algorithm or provide explicit error bounds. The first problem we consider is Lebesgue integration in the unit cube. We prove that a class of structured randomised integration methods is consistent w.r.t. convergence in mean and probability for any integrable function. Under slightly stronger integrability conditions we show that one also has almost sure convergence for median modified methods. We demonstrate the applicability of our theoretical results by considering randomly shifted lattice rules, randomised (t,d)-sequences, Latin hypercube samples, and randomised Frolov points. Secondly, we study integration w.r.t. probability measures which are available only via their non-normalised density. In this context we investigate Markov chain Monte Carlo methods which satisfy a spectral gap condition and functions which do not need to have a finite second moment. We prove error bounds for the absolute mean error where the rate of convergence is optimal. Illustrative scenarios where our theory is applicable are the random walk Metropolis algorithm as well as slice samplers. Finally, we study so-called adaptive increasingly rare Markov chain Monte Carlo algorithms. Based on a simultaneous Wasserstein contraction assumption we estimate the mean squared error and also prove bounds which characterise the path-wise convergence of the estimator. To demonstrate the applicability of our results we consider a number of examples, among which are doubly intractable distributions. Y1 - 2024 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:739-opus4-15196 ER - TY - THES A1 - Greifenstein, Luisa T1 - Supporting Primary School Programming Education through Formative Feedback N2 - Children are increasingly surrounded by computer science aspects in their everyday life. Primary school education aims at empowering children to participate in and reflect on their environment. Therefore, computer science related contents such as programming are increasingly introduced into primary school curricula. However, this also involves challenges in particular for teachers, who need to familiarise themselves with the new curriculum. As a result, primary school teachers often struggle to help primary school children with their programming issues. Corrective feedback given during the learning process (i. e. formative feedback) can help by promoting cognitive factors such as content knowledge. This thesis therefore aims to support primary school programming education through formative feedback. In order to shed light on different perspectives, both teachers and children participated in the studies in a mixed methods design. Teachers’ challenges and children’s programming issues were explored as a basis for knowing what both target groups struggle with. This was done by conducting content analysis on the challenges and issues collected and using the resulting categories for further quantitative analysis. The effects of different characteristics of feedback on the effectiveness and efficiency of teaching and learning programming were then explained. This was done by asking the teachers and children to explain their ratings and conducting content analysis on their explanations. The support of primary school programming education through formative feedback builds on the major challenge of teachers’ lack of content knowledge and the corresponding strategies of teacher training and automated feedback. Indeed, automated feedback was found to be mostly helpful for debugging and task creation. In order to provide direct support to children, common programming issues were identified in terms of the understanding of programming concepts and the usage of the programming environment. Effects on children’s learning and their preferences were identified for several feedback characteristics, leading for example to elaborated hints instead of simple direct instructions. Based on these results, a formative feedback approach of hint cards was developed and evaluated. The hint cards approach proved to be a useful example strategy for supporting primary school programming education through formative feedback. N2 - Kinder sind in ihrem Alltag zunehmend von informatischen Phänomenen umgeben. Die Grundschulbildung zielt darauf ab, Kinder zu befähigen, an ihrer Umwelt teilzuhaben und sie zu reflektieren. Daher werden informatikbezogene Inhalte wie das Programmieren zunehmend in die Lehrpläne der Grundschulen aufgenommen. Dies bringt jedoch auch Herausforderungen mit sich, insbesondere für die Lehrkräfte, die sich mit dem neuen Lehrplan und Ansätzen vertraut machen müssen. Infolgedessen fällt es Grundschullehrkräften oft schwer, Grundschulkindern bei ihren Programmierproblemen zu helfen. Korrektives Feedback, das während des Lernprozesses gegeben wird (formatives Feedback), kann helfen, indem es kognitive Faktoren wie fachliches Wissen fördert. Ziel dieser Arbeit ist es daher, den Programmierunterricht in der Grundschule durch formatives Feedback zu unterstützen. Um die unterschiedlichen Perspektiven zu beleuchten, nahmen sowohl Lehrkräfte als auch Kinder an den Studien in einem Mixed Methods-Design teil. Die Herausforderungen der Lehrkräfte und die Schwierigkeiten der Kinder bei der Programmierung wurden exploriert, um zu erfahren, womit beide Zielgruppen Probleme haben. Dazu wurden die gesammelten Herausforderungen und Probleme einer qualitativen Inhaltsanalyse unterzogen und die daraus resultierenden Kategorien für eine weitere quantitative Analyse verwendet. Außerdem wurden die Auswirkungen verschiedener Merkmale des Feedbacks auf die Effektivität und Effizienz des Lehrens und Lernens von Programmierkonzepten erklärt. Dazu erläuterten die Lehrkräfte und Kinder ihre Bewertungen und ihre Erläuterungen wurden einer qualitativen Inhaltsanalyse unterzogen. Die Unterstützung des Programmierunterrichts in der Grundschule durch formatives Feedback baut auf der großen Herausforderung des fehlenden fachlichen Wissens der Lehrkräfte und den entsprechenden Strategien der Lehrkräftebildung und des automatischen Feedbacks auf. Das automatische Feedback erwies sich beim Debugging und bei der Erstellung von Aufgaben als hilfreich. Um die Kinder direkt zu unterstützen, wurden allgemeine Programmierprobleme in Bezug auf das Verständnis von Programmierkonzepten und die Nutzung der Programmierumgebung ermittelt. Es wurden Auswirkungen auf das Lernen der Kinder und ihre Präferenzen für verschiedene Feedback-Merkmale ermittelt, was beispielsweise in elaborierten Hinweisen anstelle einfacher direkter Anweisungen resultiert. Auf der Grundlage dieser Ergebnisse wurde ein formatives Feedbackkonzept mit Hinweiskärtchen entwickelt und evaluiert. Dieses Konzept erwies sich als nützliche Strategie zur Unterstützung des Programmierunterrichts in der Grundschule durch formatives Feedback. KW - feedback KW - programming education KW - primary school education KW - Rückmeldung KW - Grundschulunterricht KW - Algorithmische Programmierung Y1 - 2024 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:739-opus4-15188 ER - TY - THES A1 - Welearegai, Gebrehiwet Biyane T1 - Precise Detection of Injection Attacks in Real-world Applications N2 - Code injection attacks like the one used in the high-profile 2017 Equifax breach, have become increasingly common, ranking at the top of OWASP’s list of critical web application vulnerabilities. The injection attacks can also target embedded applications running on processors like ARM and Xtensa by exploiting memory bugs and maliciously altering the program’s behavior or even taking full control over a system. Especially, ARM’s support of low power consumption without sacrificing performance is leading the industry to shift towards ARM processors, which advances the attention of injection attacks as well. In this thesis, we are considering web applications and embedded applications (running on ARM and Xtensa processors) as the target of injection attacks. To detect injection attacks in web applications, taint analysis is mostly proposed but the precision, scalability, and runtime overhead of the detection depend on the analysis types (e.g., static vs dynamic, sound vs unsound). Moreover, in the existing dynamic taint tracking approach for Java- based applications, even the most performant can impose a slowdown of at least 10–20% and often far more. On the other hand, considering the embedded applications, while some initial research has tried to detect injection attacks (i.e., ROP and JOP) on ARM, they suffer from high performance or storage overhead. Besides, the Xtensa has been neglected though used in most firmware-based embedded WiFi home automation devices. This thesis aims to provide novel approaches to precisely detect injection attacks on both the web and embedded applications. To that end, we evaluate JavaScript static analysis frameworks to evaluate the security of a hybrid app (JS & native) from an industrial partner, provide RIVULET – a tool that precisely detects injection attacks in Java-based real-world applications, and investigate injection attacks detection on ARM and Xtensa platforms using hardware performance counters (HPCs) and machine learning (ML) techniques. To evaluate the security of the hybrid application, we initially compare the precision, scalability, and code coverage of two widely-used static analysis frameworks—WALA and SAFE. The result of our comparison shows that SAFE provides higher precision and better code coverage at the cost of somewhat lower scalability. Based on these results, we analyze the data flows of the hybrid app via taint analysis by extending the SAFE’s taint analysis and detected a potential for injection attacks of the hybrid application. Similarly, to detect injection attacks in Java-based applications, we provide Rivulet which monitors the execution of developer-written functional tests using dynamic taint tracking. Rivulet uses a white-box test generation technique to re-purpose those functional tests to check if any vulnerable flow could be exploited. We compared Rivulet to the state-of-the-art static vulnerability detector Julia on benchmarks and Rivulet outperformed Julia in both false positives and false negatives. We also used Rivulet to detect new vulnerabilities. Moreover, for applications running on ARM and Xtensa platforms, we investigate ROP1 attack detection by combining HPCs and ML techniques. We collect data exploiting real- world vulnerable applications and small benchmarks to train the ML. For ROP attack detection on ARM, we also implement an online monitor which labels a program’s execution as benign or under attack and stops its execution once the latter is detected. Evaluating our ROP attack detection approach on ARM provides a detection accuracy of 92% for the offline training and 75% for the online monitoring. Similarly, our ROP attack detection on the firmware-only Xtensa processor provides an overall average detection accuracy of 79%. Last but not least, this thesis shows how relevant taint analysis is to precisely detect injection attacks on web applications and the power of HPC combined with machine learning in the control flow injection attacks detection on ARM and Xtensa platforms. Y1 - 2023 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:739-opus4-12926 ER - TY - JOUR A1 - Caspari-Sadeghi, Sima T1 - Artificial Intelligence in Technology-Enhanced Assessment: A Survey of Machine Learning JF - Journal of Educational Technology Systems N2 - Intelligent assessment, the core of any AI-based educational technology, is defined as embedded, stealth and ubiquitous assessment which uses intelligent techniques to diagnose the current cognitive level, monitor dynamic progress, predict success and update students’ profiling continuously. It also uses various technologies, such as learning analytics, educational data mining, intelligent sensors, wearables and machine learning. This can be the key to Precision Education (PE): adaptive, tailored, individualized instruction and learning. This paper explores (a) the applications of Machine Learning (ML) in intelligent assessment, and (b) the use of deep learning models in ‘knowledge tracing and student modeling’. The paper concludes by discussing barriers involved in using state-of-the-art ML methods and some suggestions to unleash the power of data and ML to improve educational decision-making. KW - artificial intelligence KW - knowledge tracing KW - machine learning KW - technology-enhanced assessment (TEA) Y1 - 2022 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:739-opus4-11818 SN - 0047-2395 SN - 1541-3810 VL - 51 IS - 3 SP - 372 EP - 386 PB - SAGE Publications CY - Sage CA: Los Angeles, CA ER - TY - JOUR A1 - Ghosh Dastidar, Kanishka A1 - Jurgovsky, Johannes A1 - Siblini, Wissam A1 - Granitzer, Michael T1 - NAG: neural feature aggregation framework for credit card fraud detection JF - Knowledge and Information Systems N2 - The state-of-the-art feature-engineering method for fraud classification of electronic pay-ments uses manually engineered feature aggregates, i.e., descriptive statistics of thetransaction history. However, this approach has limitations, primarily that of being dependenton expensive human expert knowledge. There have been attempts to replace manual aggre-gation through automatic feature extraction approaches. They, however, do not consider thespecific structure of the manual aggregates. In this paper, we define the novel Neural Aggre-gate Generator (NAG), a neural network-based feature extraction module that learns featureaggregates end-to-end on the fraud classification task. In contrast to other automatic featureextraction approaches, the network architecture of the NAG closely mimics the structureof feature aggregates. Furthermore, the NAG extends learnable aggregates over traditionalones through soft feature value matching and relative weighting of the importance of differ-ent feature constraints. We provide a proof to show the modeling capabilities of the NAG.We compare the performance of the NAG to the state-of-the-art approaches on a real-worlddataset with millions of transactions. More precisely, we show that features generated with theNAG lead to improved results over manual aggregates for fraud classification, thus demon-strating its viability to replace them. Moreover, we compare the NAG to other end-to-endapproaches such as the LSTM or a generic CNN. Here we also observe improved results. Weperform a robust evaluation of the NAG through a parameter budget study, an analysis of theimpact of different sequence lengths and also the predictions across days. Unlike the LSTMor the CNN, our approach also provides further interpretability through the inspection of itsparameters. KW - finance KW - credit card fraud KW - representation learning Y1 - 2022 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:101:1-2022060219175235764329 VL - 2022 IS - 64 SP - 831 EP - 858 PB - Springer Nature CY - Berlin ER - TY - THES A1 - Patil, Amit Dilip T1 - Towards Resilient Protection of Interconnected ICT and Power Systems N2 - Due to the increasing number of distributed renewable energy sources, the distribution grid faces new operational challenges. Information and Communication Technology (ICT) systems can resolve these challenges through grid services that use automation, monitoring, and real-time decision-making, helping maintain an acceptable operational state of the distribution grid. However, the reliance of the power system on the ICT system and vice versa in the so-called smart grid creates interdependencies between the systems, which present new pathways for failure propagation. Therefore, these interdependencies require special attention to ensure stable system operation in the face of these challenges. However, these interdependencies have not been studied extensively in the literature. This thesis investigates approaches to model, quantify and improve the performance and resilience of the smart grid infrastructure. The interdependencies are formalised as interconnectors, entities that exist in all the connected systems. These interconnectors consist of components from both systems, where the components are modelled as state variables. These state variables determine the interconnector state and the service delivered. Failures represented by a change in state variables may impact the state. These state variables are deployed in a discrete event simulation framework to determine the system performance over time. The simulation result is represented on a two-dimensional state-space diagram depicting the operational state and service delivered. This allows for the resilience analysis of a system under various scenarios. The interdependencies are further investigated by exploring the role of ICT-based grid services in power grids, whose state is defined based on ICT properties, such as latency. These properties are formalised using property graphs. The ICT properties obtained from these graphs are used to parameterise a finite state automaton model of a grid service states, which are then used to determine the state of the entire smart grid. Case studies of state estimation and adaptive protection highlight the application of this approach. The use of ICT in state estimation allows the distinction of a global and perceived view of the power grid, which influences decision-making in the face of challenges. This thesis further investigates the protection system in detail. The overcurrent protection system is adversely impacted by distributed generation, resulting in undesired phenomena such as protection blinding. This thesis characterises this phenomenon by proposing two indices that capture the protection trip time under the influence of distributed generation. These indices consider the electrical distance between faults, protection and distributed generation. These indices and simulation results identify the worst-impacted locations in the power grid in terms of protection trip time. They also identify fault locations under given assumptions that do not cause protection blinding. ICT can resolve protection blinding by adapting the sensitivity of protection relays. However, since faults must be cleared in a short timeframe, communication delays may adversely impact the fault-clearing time. A discrete event simulation model is proposed to study protection performance in distribution grids. Investigation of time distribution assumptions reveals that the lognormal distribution accurately captures the circuit breaker trip time. The impact of the distributed generation and communication delay on the protection system is determined by measuring fault-clearing times using discrete event simulation. Results show that for the system studied, protection blinding is critical for low impedance faults in grids with high fault levels, while high impedance faults are critical in grids with low fault levels. Moreover, sympathetic tripping is seen at increased distribution grid fault levels and fault impedance. Furthermore, while communication systems reduce fault clearing times, increased delays harm protection systems. Finally, communication system components like sensors can fail, preventing fault detection. This thesis proposes a genetic algorithm-based approach to optimally place redundant sensors, minimising protection blinding under communication uncertainty within a redundancy budget. Results demonstrate the algorithm's effectiveness in optimising redundant sensor locations, reducing system costs, and improving fault tolerance. For the system and scenarios investigated, an average of 60% redundant sensors are relocated, reducing the average protection trip time by 36.65% compared to a baseline approach that does not consider communication uncertainty. This encourages incorporating communication component failure considerations in power system planning. KW - information and communication technology KW - smart grid KW - discrete event simulation KW - property graphs KW - protection blinding KW - genetic algorithm Y1 - 2025 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:739-opus4-16088 ER - TY - JOUR A1 - Fritz, Manuela T1 - Temperature and non‐communicable diseases: Evidence from Indonesia's primary health care system JF - Health Economics N2 - Climate change induced rising temperatures will pose a detrimental threat to decent health in the coming decades. Especially at risk are individuals with chronic diseases, since heat can exacerbate a variety of health conditions. In this article, I examine the heat‐morbidity relationship in the context of Indonesia, focusing on chronic, non‐communicable diseases, namely diabetes, cardiovascular and respiratory diseases. Using a novel dataset from the Indonesian national health insurance scheme Jaminan Kesehatan Nasional/Badan Penyelenggara Jaminan Sosial (BPJS) and linking it with meteorological data on the daily‐district level, I estimate the causal effect of high temperatures on the daily number of primary health care visits. The results show that on a hot day all‐cause visits and visits with a diagnosis of diabetes and cardiovascular diseases increase by 8%, 25% and 14%, respectively. These increases are permanent and not offset by visit displacement or ‘harvesting’. Visits related to respiratory diseases seem not to be affected by high temperatures. I use several climate change scenarios to predict the increase in visits and costs by the end of the century, which all forecast a substantial financial burden for the health care system. These results might have relevance for other middle‐income countries with similar climatic conditions. KW - climate change KW - health KW - Indonesia KW - JKN/BPJS kesehatan KW - non‐communicable diseases KW - temperature Y1 - 2022 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:739-opus4-11429 VL - 31 IS - 11 SP - 2445 EP - 2464 PB - Wiley CY - Hoboken ER - TY - JOUR A1 - Fekih Hassen, Wiem A1 - Challouf, Maher T1 - Long short-term renewable energy sources prediction for grid-management systems based on stacking ensemble model JF - Energies N2 - The transition towards sustainable energy systems necessitates effective management of renewable energy sources alongside conventional grid infrastructure. This paper presents a comprehensive approach to optimizing grid management by integrating Photovoltaic (PV), wind, and grid energies to minimize costs and enhance sustainability. A key focus lies in developing an accurate scheduling algorithm utilizing Mixed Integer Programming (MIP), enabling dynamic allocation of energy resources to meet demand while minimizing reliance on cost-intensive grid energy. An ensemble learning technique, specifically a stacking algorithm, is employed to construct a robust forecasting pipeline for PV and wind energy generation. The forecasting model achieves remarkable accuracy with a Root Mean Squared Error (RMSE) of less than 0.1 for short-term (15 min and one day ahead) and long-term (one week and one month ahead) predictions. By combining optimization and forecasting methodologies, this research contributes to advancing grid management systems capable of harnessing renewable energy sources efficiently, thus facilitating cost savings and fostering sustainability in the energy sector. Y1 - 2024 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:739-opus4-14649 VL - 2024 IS - 17(13) ER - TY - THES A1 - Kravets-Meinke, Daria T1 - Search Engines and Foreign Influence: How Google and Yandex Mediate Russia’s Propaganda Abroad N2 - This cumulative dissertation examined how the US-based Google and Russia-based Yandex mediate the propaganda efforts of Russia’s ruling elites abroad on a case study of Belarus. The findings presented here contribute to a nuanced understanding of how algorithmic gatekeepers, particularly search engines, can be strategically appropriated or manipulated to reinforce and export state narratives beyond national borders. The main conclusion of this dissertation is that both Yandex and Google, albeit through different mechanisms and to varying extents, can serve as mediators of Russia’s propaganda efforts abroad. KW - search engines KW - Russia KW - propaganda Y1 - 2025 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:739-opus4-15953 ER - TY - JOUR A1 - Blanc, Julia A1 - Annekatrin, Meißner T1 - Towards a holistic approach to sustainable development : inner development as a missing link for sustainability transformation JF - Religions (Special issue "Sustainable development : the normative contribution of theology") N2 - The discourse on understanding and implementing sustainable development has so far focused primarily on the external aspects, neglecting the internal dimension of people. The main purpose of our paper is to contribute to addressing this research gap. Therefore, we intend to (1) substantiate existing aspects of the Inner Development Goals (IDGs), (2) complement them, and (3) link the concept of the IDGs to normative discourses in Christian Social Ethics and Social Philosophy. Our results show that the dimensions of Being, Relating, and Collaborating in the IDG Framework can be substantiated by the normative discourse on spirituality and by reference to the social principle of personality in Christian Social Ethics, as well as by the Indian Social Philosophical Perspective of Vimala Thakar which focuses on a value-based approach. This paper suggests that the concept of the IDGs will be strengthened by adding the dimension of Caring—understood as the concern and responsibility for the wholeness in the combining of the inner and outer dimensions. By linking the concept of the Inner Development Goals to the existing normative discourses in Christian Social Ethics and Social Philosophy, our research contributes to making the concept connectable and deepens the discussions on a practical and theoretical level. KW - holistic sustainable development KW - change of consciousness KW - being KW - caring KW - christian social ethics KW - social philosophy Y1 - 2025 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:739-opus4-15816 VL - 2025 IS - 16(1) PB - MDPI CY - Basel ER - TY - JOUR A1 - Fritz, Manuela A1 - Grimm, Michael A1 - Weber, Ingmar A1 - Yom-Tov, Elad A1 - Praditya, Benedictus T1 - Can social media encourage diabetes self-screenings? A randomized controlled trial with Indonesian Facebook users JF - npj | Digital medicine N2 - Nudging individuals without obvious symptoms of non-communicable diseases (NCDs) to undergo a health screening remains a challenge, especially in middle-income countries, where NCD awareness is low but the incidence is high. We assess whether an awareness campaign implemented on Facebook can encourage individuals in Indonesia to undergo an online diabetes self-screening. We use Facebook’s advertisement function to randomly distribute graphical ads related to the risk and consequences of diabetes. Depending on their risk score, participants receive a recommendation to undergo a professional screening. We were able to reach almost 300,000 individuals in only three weeks. More than 1400 individuals completed the screening, inducing costs of about US$0.75 per person. The two ads labeled “diabetes consequences” and “shock” outperform all other ads. A follow-up survey shows that many high-risk respondents have scheduled a professional screening. A cost-effectiveness analysis suggests that our campaign can diagnose an additional person with diabetes for about US$9. KW - Health care economics KW - Population screening KW - Risk factors Y1 - 2024 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:739-opus4-15157 VL - 2024 IS - 7 PB - Macmillan Publishers Limited CY - Basingstoke ER -