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 - 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 - THES A1 - Jakob, Dietmar Friedrich T1 - Teilhabegerechtigkeit bei der digitalen Inklusion älterer Erwachsener: Eine Potenzialanalyse von Sprachassistenten T1 - Equity of participation in digital inclusion of older adults: A potential analysis of voice assistants N2 - This cumulative dissertation delves into the complexities and opportunities surrounding older adults’ adoption and use of Voice Assistants (VAs), focusing on digital participation equity from theologic-ethical and social perspectives. Through an extensive series of methodologically diverse studies—including systematic literature reviews, laboratory experiments, surveys, and field studies—the research aims to uncover how older adults perceive, interact with, and are impacted by technologies, such as the particular model “Amazon Echo Show 10, 3rd generation with integrated voice interface ALEXA”. The investigation also seeks to pinpoint the obstacles that impede the adoption of these technologies among this demographic. The research initially demonstrates that older adults can recognize the utility of VAs in various applications, including information retrieval, entertainment, and health management. The findings underscore the importance of these devices in enhancing the quality of life by providing easier access to essential services and facilitating social interaction, even among those who may be physically isolated. However, the dissertation identifies significant concerns among older adults regarding privacy and data security, influencing their willingness to embrace VAs. The devices’ complexity and occasional interaction difficulties—such as command formulation and speech recognition issues—further challenge their usability for this group. A notable and unique aspect of the study is the anthropomorphization of devices by some older adults. This behavior, where users attribute human-like characteristics or emotional connections to VAs, suggests deeper psychological and social dimensions in the user-technology relationship. This phenomenon is examined to understand its implications for technology acceptance and the potential for these devices to mitigate feelings of loneliness and social isolation. In summary, this dissertation provides practical recommendations for enhancing the design, communication, and functionality of VAs to better cater to the needs and preferences of older adults. It underscores the importance of technology development that respects the dignity and autonomy of older individuals, ensuring their digital participation and equity. The work advocates for a comprehensive approach that integrates ethical considerations into technology design and dissemination, thereby promoting a framework that supports the full inclusion of older adults in the digital world. N2 - Diese kumulative Dissertation untersucht die Komplexität und die Möglichkeiten, die mit der Annahme und Nutzung von Sprachassistenten durch ältere Erwachsene verbunden sind, und konzentriert sich auf die digitale Teilhabegerechtigkeit aus theologisch-ethischer und sozialer Sicht. Durch eine umfangreiche Reihe methodisch unterschiedlicher Studien - darunter systematische Literaturauswertungen, Laborexperimente, Umfragen und Feldstudien - zielt diese Forschung darauf ab herauszufinden, wie ältere Erwachsene Technologien wie kommerzielle Sprachassistenten, wie z. B. das spezielle Modell "Amazon Echo Show 10, 3. Generation mit integriertem Sprachinterface Alexa" wahrnehmen, mit ihnen interagieren und von ihnen beeinflusst werden. Die Untersuchung versucht auch, die Hindernisse aufzuzeigen, die die Annahme dieser Technologien in dieser Bevölkerungsgruppe behindern und geht auch auf Tendenzen von Antropomorphisierung der Geräte ein. Die Untersuchung zeigt zunächst, dass ältere Erwachsene den Nutzen von Sprachassistenten in verschiedenen Anwendungen erkennen können, darunter für die Informationsbeschaffung, Unterhaltung und das Gesundheitsmanagement. Die Ergebnisse unterstreichen die Bedeutung dieser Geräte für die Verbesserung der Lebensqualität, indem sie den Zugang zu wichtigen Dienstleistungen erleichtern und die soziale Interaktion fördern, selbst bei Personen, die körperlich isoliert sind. Die Dissertation zeigt jedoch auch, dass ältere Menschen Bedenken hinsichtlich des Schutzes der Privatsphäre und der Datensicherheit haben, was ihre Bereitschaft, Sprachassistenten zu nutzen, deutlich beeinflusst. Die Komplexität der Geräte und gelegentliche Schwierigkeiten bei der Interaktion - wie etwa Probleme bei der Befehlsformulierung und der Spracherkennung - stellen eine weitere Herausforderung für die Benutzerfreundlichkeit dieser Gruppe dar. Ein bemerkenswerter und einzigartiger Aspekt der Studie ist die Anthropomorphisierung der Geräte durch einige ältere Erwachsene. Dieses Verhalten, bei dem die Benutzer Sprachassistenten menschenähnliche Eigenschaften oder emotionale Verbindungen zuschreiben, deutet auf tiefere psychologische und soziale Dimensionen in der Beziehung zwischen Benutzer und Technologie hin. Dieses Phänomen wird untersucht, um seine Auswirkungen auf die Technologieakzeptanz und das Potenzial dieser Geräte, Gefühle von Einsamkeit und sozialer Isolation zu mildern, zu verstehen. Abschließend bietet die Dissertation gezielte Empfehlungen zur Verbesserung von Design, Kommunikation und Funktionalität von Sprachassistenten, um den Bedürfnissen und Vorlieben älterer Menschen besser gerecht zu werden. Sie unterstreicht die Notwendigkeit einer Technologieentwicklung, die die Würde und Autonomie älterer Menschen in den Vordergrund stellt und ihre digitale Teilhabe und Gleichberechtigung gewährleistet. Die Arbeit fordert einen ganzheitlichen Ansatz, der ethische Überlegungen in die Entwicklung und Verbreitung von Technologien einbezieht, und setzt sich für einen Rahmen ein, der die vollständige Einbeziehung älterer Menschen in die digitale Welt unterstützt. KW - Human Computer Interation KW - Voice Assistants KW - Older Adults KW - Digital Equity Y1 - 2025 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:739-opus4-15849 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 - GEN A1 - Kott, Annette A1 - Schuster, Jennifer A1 - Groß, Rainer A1 - Bauer, Christoph T1 - Maßnahmenkatalog Green IT an bayerischen Hochschulen N2 - "Der vorliegende Maßnahmenkatalog bietet abgestimmte Empfehlungen, um Nachhaltigkeit für bayerische Hochschulen im Bereich Green IT zu fördern. Ziel ist es, energieeffizientes Verhalten zu unterstützen und die IT-Landschaft nachhaltiger zu gestalten. Die Maßnahmen zielen nicht nur auf die Förderung eines verantwortungsvollen Handelns ab, sondern bieten auch das Potenzial, langfristig Kosteneinsparungen durch einen energieeffizienten Betrieb zu erzielen. Gleichzeitig wird nachhaltiges Handeln durch gesetzliche Vorgaben wie dem Energieeffizienzgesetz zunehmend verbindlicher, da auch Hochschulen diesen Anforderungen unterliegen. Der Maßnahmenkatalog unterstützt dabei, diese regulatorischen Anforderungen zu erfüllen und gleichzeitig einen wesentlichen Beitrag zur Ressourcenschonung sowie zur Reduzierung von Treibhausgasemissionen zu leisten." (Zielsetzung, Seite III) KW - Nachhaltigkeit KW - Informationstechnologie KW - Hochschul-IT Y1 - 2025 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:739-opus4-15327 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 - JOUR A1 - Bleyer, Bernhard A1 - Zink, Roland T1 - Sustainable Development Goals und ihre Orientierungsfunktion für angewandte Wissenschaften T1 - Sustainable Development Goals and their guidance function for applied sciences JF - Bavarian Journal of Applied Science N2 - Editorial des Bavarian Journal of Applied Science 5 KW - Sustainable development goals KW - nachhaltige Entwicklung Y1 - 2019 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:739-opus4-14372 VL - 2019 IS - 5 SP - 406 EP - 411 CY - Deggendorf ER - TY - JOUR A1 - Bleyer, Bernhard T1 - Sven Ove Hansson (Hrsg.), The Ethics of Technology. Methods and Approaches JF - TATuP – Zeitschrift für Technikfolgenabschätzung in Theorie und Praxis 28/3 N2 - Rezension zu Hansson (Hg.): The ethics of technology : methods and approaches, erschienen 2017 bei Rowman & Littlefield (978-1-78348-658-8) KW - Technologie KW - Technologieentwicklung KW - Technikethik KW - Ethik Y1 - 2019 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:739-opus4-14436 N1 - Zuerst erschienen in https://www.tatup.de/ : https://doi.org/10.14512/tatup.28.3.73 VL - 28 (2019) IS - 3 SP - 73 EP - 74 PB - Oekom Verlag ER - TY - JOUR A1 - Adiatu, Afeez T1 - Energizing the inter-regional cooperation and energy governance : an exploration of the Africa-EU energy partnership JF - Journal of Sustainable Development of Energy, Water and Environment Systems (ISSN: 1848-9257, DOI: 10.13044/j.sdewes) N2 - The emergence of change in the global energy governance structure is precipitated by the shift in global energy technology. The shift from carbon-intense energy to cleaner sources surpasses technological discontinuation. The inter-regional, regional, and sub-regional grouping emerged in global energy governance to support governance capabilities across countries. This research seeks to investigate the inter-regional partnership between Africa and the European Union initiated to facilitate energy decision-making. This study adopts thematic analysis to explore literature and reports on the Africa-EU partnership to understand its impact on the future of the African energy sector. This research argues using a neo-liberal lens that the limited state capacity in energy governance may necessitate inter-regional partnerships to aid energy sector development in Africa. The study concludes that considering Africa's potential in renewable energy sources such as solar irradiation and the limited energy access in the Sub-Saharan region, intervention of external capabilities through technological and financial aids may stimulate the utilization of such potential. KW - global energy governance KW - renewable energy KW - energy transition KW - regionalism KW - global governance Y1 - 2024 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:739-opus4-15782 VL - 2024 IS - 12(4) PB - SDEWES Centre CY - Zagreb ER - TY - GEN A1 - Schuster, Jennifer A1 - Kott, Annette A1 - Bauer, Christoph A1 - Groß, Rainer T1 - Kennzahlenkatalog Green IT an bayerischen Hochschulen N2 - "Der vorliegende, mit den bayerischen Hochschulen und Universitäten abgestimmte Kennzahlenkatalog für Green IT, dient als Grundlage, um einheitlich Kennzahlen für die bayerischen Rechenzentren zu erfassen und damit einen nachhaltigen IT-Betrieb der Hochschulen zu unterstützen. Durch die Implementierung und Erfassung dieser Kennzahlen werden, die ökologischen Auswirkungen der IT messbargemacht. Dies ermöglicht die Wirksamkeit von Maßnahmen quantitativ zu überprüfen und den IT-Betrieb in eine ökologisch nachhaltige Richtung zu steuern. Im Rahmen des Energieeffizienzgesetzes wird das Einsparen von Energie und Treibhausgasen auch für Hochschulen zunehmend verbindlicher. Der Katalog beschreibt die im Energieeffizienzgesetz geforderten Kennzahlen, enthält eine strukturierte Vorgehensweise zur Implementierung und unterstützt dabei die gesetzlichen Anforderungen einzuhalten." (S. III) KW - Informationstechnologie KW - Rechenzentrum KW - Hochschulen KW - Energieeffizienzgesetz Y1 - 2025 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:739-opus4-18675 ER - TY - JOUR A1 - Schmid-Petri, Hannah A1 - Elschner, Sophie G. T1 - Transitionalists, traditionalists or pioneers? How German municipal energy companies are responding to the national energy transition JF - Energy Research & Social Science (Online ISSN: 2214-6326) N2 - The Renewable Energy Sources Act (EEG) in Germany aims to transition the country to a sustainable energy system. This has led to a decentralization of the energy market and a shift toward community-focused energy supply systems. Municipal energy companies (MECs), deeply rooted in their communities, are crucial in facilitating this transition and promoting innovative technologies. Websites serve as important communication tools, facilitating interaction between companies and consumers. In our study, we conducted a quantitative content analysis to examine how MECs communicate issues related to the energy transition on their web pages (N = 300). In general, our results show that the energy transition was rarely mentioned on landing pages, and while companies are improving their sustainable electricity products, renewable gas and heating tariffs have received little attention. Additionally, we identified three communication types of MECs: The transitionalists (45 %), the traditionalists (35 %), and the pioneers (20 %), with the latter being the most innovative that emphasizes issues related to the energy transition. Overall, it can be said that the MECs have not yet fully exploited their potential to position themselves as pioneers of the energy transition in their website communications. Y1 - 2024 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:739-opus4-18714 VL - 2024 IS - 109 PB - Elsevier CY - Amsterdam ER - TY - JOUR A1 - Otto, Alena A1 - Tilk, Christian T1 - Intelligent design of sensor networks for data-driven sensor maintenance at railways JF - Omega (Online ISSN: 1873-5274) N2 - With rapid advances in digitization, many critical processes in transportation, industries, and our daily life rely on sensor measurements. With time, however, the measurements may get gradually biased and their precision deteriorates, leading to an enhanced risk of major disruptions caused by false sensor measurements. All single sensor measurements are uncertain and deviate from the true value. To detect malfunctioning sensors early on, a set of recent measurements of each sensor has to be constantly cross-checked against the measurements of a given number of other sensors, i.e., sensors should form a diagnosable network. In this article, we examine the intelligent positioning of safety-relevant sensors at railways such that the installed sensors can constantly cross-check each other and the number of the required sensors is minimized. The arising sensor positioning problem (SPP) belongs to the family of the coordinated set covering problems with two binary matrices: the choice of columns in one matrix implies the selection of specific columns and rows in the other matrix. We formulate an integer program, provide some formal analysis of the SPP and design a customized large neighborhood search metaheuristic RuM, which finds close-to-optimality solutions fast. In our computational experiments, we show that if we ignore the diagnosability requirement, the installed sensors cannot sufficiently cross-check each other in most cases. However, it costs only a few (or even no) additional sensors to ensure the diagnosability of the sensor network. KW - Rail transport KW - Integer programming KW - Sensors KW - Set covering problem KW - Network design KW - Diagnosable network Y1 - 2024 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:739-opus4-18771 VL - 2024 IS - 127 PB - Elsevier CY - Amsterdam ER - TY - JOUR A1 - Fekih Hassen, Wiem A1 - Schoppik, Luis A1 - Schiegg, Sascha A1 - Gerl, Armin T1 - Power management approach of hybrid energy storage system for electric vehicle charging stations JF - Smart Cities N2 - The applicability of Hybrid Energy Storage Systems (HESSs) has been shown in multiple application fields, such as Charging Stations (CSs), grid services, and microgrids. HESSs consist of an integration of two or more single Energy Storage Systems (ESSs) to combine the benefits of each ESS and improve the overall system performance. In this work, we propose a novel power management controller called the Hybrid Controller for the efficient HESS’s charging and discharging, considering the State of Charge (SoC) of the HESS and the dynamic supply and load. The Hybrid Controller optimises the use of the HESS, i.e., minimises the amount of energy drawn from and discharged to the grid, thus utilising and prioritising the provided Photovoltaic (PV) power. The performance of our proposal was assessed via simulation using various evaluation metrics, i.e., Autarky, charge/discharge cycle, and Self-Consumption (SC), where we defined 24 scenarios in different locations in Germany. KW - HESS KW - RFB KW - lithium battery KW - power distribution KW - OpenEMS KW - real load dataset Y1 - 2024 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:m347-opus-6045 SN - 2624-6511 VL - 7 (2024) IS - 6 SP - 4025 EP - 4051 PB - MDPI CY - Basel ER - TY - JOUR A1 - Hackl, Veronika A1 - Müller, Alexandra Elena A1 - Granitzer, Michael A1 - Sailer, Maximilian T1 - Is GPT-4 a reliable rater? Evaluating consistency in GPT-4's text ratings JF - Frontiers in Education N2 - This study reports the Intraclass Correlation Coefficients of feedback ratings produced by OpenAI's GPT-4, a large language model (LLM), across various iterations, time frames, and stylistic variations. The model was used to rate responses to tasks related to macroeconomics in higher education (HE), based on their content and style. Statistical analysis was performed to determine the absolute agreement and consistency of ratings in all iterations, and the correlation between the ratings in terms of content and style. The findings revealed high interrater reliability, with ICC scores ranging from 0.94 to 0.99 for different time periods, indicating that GPT-4 is capable of producing consistent ratings. The prompt used in this study is also presented and explained. KW - artificial intelligence KW - GPT-4 KW - large language model KW - prompt engineering KW - feedback KW - higher education Y1 - 2023 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:739-opus4-18348 SN - 2504-284X VL - 2023 IS - 8 PB - Frontiers CY - Lausanne ER - TY - THES A1 - Frank, Florian T1 - Integrating physical unclonable functions from novel nanomaterials, circuit elements, and memory technologies into future hardware architectures N2 - Cryptographic keys are fundamental components for ensuring security in digital systems. To ensure reliable key generation and management, various technical concepts have been developed, primarily based on dedicated hardware components such as Trusted Platform Modules (TPMs). However, many modern systems, especially small resource-constrained devices, typically lack hardware support for secure key generation and management. To address these limitations, Physical Unclonable Functions (PUFs) have proven to be an effective solution for key generation, device authentication, and identification tasks. PUFs leverage inherent variations in hardware components to produce unique, device-specific keys. For a well-designed PUF, these keys can be reproduced reliably on the same device but are practically impossible to clone. Various types of PUFs exist, including those that exploit slight delay differences in circuits with symmetric paths. Others rely on physical characteristics of components already present in the computing system, such as SRAM or DRAM. However, many of these constructions rely on technologies that could be replaced by emerging ones in the future. Such a replacement may involve a transition from traditional memory technologies, such as SRAM, DRAM, and flash memory, to emerging Non-Volatile Memories (NVMs), including Ferroelectric RAM (FRAM), Magnetoresistive RAM (MRAM), and Resistive RAM (ReRAM). These new technologies, in turn, necessitate innovative hardware security solutions for generating intrinsic hardware fingerprints, ensuring security for next-generation embedded devices. Furthermore, the integration of nanomaterials, such as carbon nanotubes, into processor architectures and the adoption of reconfigurable hardware platforms like Field-Programmable Gate Arrays (FPGAs) require the development of specifically tailored cybersecurity solutions. This dissertation aims to develop hardware-based security mechanisms for these types of devices by designing new PUF constructions and demonstrating their practical applications. One focus lies on PUFs extracted from nanomaterials and emerging circuit elements, particularly memristive devices and Carbon NanoTube Field-Effect Transistors (CNT-FETs). For memristive devices, which form the basis of ReRAM memory, this work analyzes methods ranging from simple binary quantization to advanced techniques exploiting device-specific response patterns. In the case of CNT-FETs, custom-fabricated wafers are developed to construct PUFs with optimal properties, such as high robustness, uniformity, and entropy, even under varying environmental conditions. These conditions include fluctuations in ambient temperature. Based on an analysis of fundamental system components, this work evaluates the feasibility of deriving PUFs from fully integrated circuits. A specific focus is placed on emerging non-volatile memory technologies, assessing their potential for PUF applications. To achieve PUF behavior in these memory devices, techniques such as intentional timing manipulation, induced bit flips through row hammering, and variations in supply voltage are examined. These resulting bit flips can be exploited as PUF responses. Additionally, transforming raw PUF responses into cryptographically usable keys and integrating specific PUFs into practical applications are core components of this work. The demonstrated practical applications include an innovative architecture for encrypting and binding data to non-volatile memory modules, implemented on Multiprocessor System-on-Chips (MPSoCs) incorporating FPGAs. This architecture enables the storage of confidential data on non-volatile memory while simultaneously using the same module as a PUF, without requiring separate memory partitions solely for the PUF functionality. Finally, practical applications of hardware fingerprints in the automotive sector are demonstrated, including an FPGA-based implementation to maintain security while preserving the temporal determinism of time-critical messages. These goals are met through the use of hardware-implemented cryptographic algorithms coupled with an FPGA-based ring oscillator PUF. To summarize, this work presents new types of PUF implementations, starting with nanomaterials and emerging circuit elements, extending to PUFs derived from integrated circuits, and demonstrates innovative solutions for their integration into MPSoC-based architectures. N2 - Kryptografische Schlüssel bilden die Grundlage nahezu aller Verfahren zur Gewährleistung der IT-Sicherheit in digitalen Systemen. Um deren Generierung und Verwaltung zuverlässig zu ermöglichen, wurden verschiedene technische Konzepte entwickelt, allen voran dedizierte Hardware-Komponenten wie Trusted Platform Modules (TPMs). Ein Nachteil solcher Konzepte ist jedoch, dass diese Module nicht in allen Systemen integrierbar sind, weshalb Mikrocontroller in kleinen eingebetteten Systemen häufig keine Unterstützung für hardwaregestützte Schlüsselverwaltung bieten. Um dennoch eine sichere Kommunikation zu gewährleisten, haben sich kryptografische Schlüssel, die aus sogenannten Physical Unclonable Functions (PUFs) abgeleitet werden, als effektive Lösung bewährt. PUFs nutzen hardwarebedingte physikalische Abweichungen, die häufig durch den Produktionsprozess verursacht werden, um daraus einen unklonbaren, gerätespezifischen kryptografischen Schlüssel zu erzeugen. Ein Beispiel sind verzögerungsbasierte PUFs, die minimale Signalverzögerungen aufgrund geringfügiger Abweichungen in den Leitungslängen sowie weiteren elektrischen Parametern nutzen, um eine unklonbare, gerätegebundene Charakteristik zu extrahieren. Des Weiteren haben sich PUFs, die auf bereits in einem Rechensystem vorhandenen Hardwarekomponenten wie DRAM oder SRAM basieren, als kostengünstige Möglichkeit eines Hardware-Sicherheitsankers erwiesen. Der Großteil der derzeit verfügbaren PUF-Implementierungen basiert jedoch nahezu ausschließlich auf älterer Hardware, wie den oben erwähnten Speichertechnologien. In Zukunft könnten diese jedoch durch neuartige nichtflüchtige Speichertechnologien, insbesondere Ferroelectric RAM (FRAM), Magnetoresistive RAM (MRAM) und Resistive RAM (ReRAM), ersetzt werden. Bei diesen Technologien besteht ebenfalls die Notwendigkeit zur Ableitung von kryptografisch sicheren Schlüsseln, um den Schutz zukünftiger eingebetteter Systeme zu gewährleisten. Weitere zukunftsgerichtete Entwicklungen werden die Integration von Nanomaterialien, beispielsweise in Prozessoren, sowie der vermehrte Einsatz neuer Hardwarearchitekturen, wie etwa solcher auf Basis von Field-Programmable Gate Arrays (FPGAs), umfassen. Diese Dissertation hat sich zum Ziel gesetzt, diese Probleme zu adressieren. Sie umfasst die Entwicklung und Analyse verschiedener Arten neuartiger PUFs sowie deren Integration in praktische Anwendungen. Zunächst wird eine Analyse bestimmter Nanomaterialien durchgeführt, insbesondere die Untersuchung neuartiger, auf Kohlenstoffnanoröhrchen basierender Feldeffekttransistoren. Hierfür wurden speziell gefertigte Siliziumwafer entwickelt, um PUFs mit optimalen Eigenschaften wie hoher Robustheit, Uniqueness und Entropie zu realisieren. Dies soll selbst unter variierenden Umgebungsbedingungen, einschließlich Schwankungen der Umgebungstemperatur, gewährleistet werden. Darüber hinaus wird das Verhalten von memristiven Bauelementen, den Basiselementen von ReRAM Modulen, im Hinblick auf mögliche PUF-Implementierungen untersucht. Dabei werden Lösungen zur binären Klassifikation entwickelt und spezifische Response-Pattern beim Anlegen verschiedener elektrischer Signale untersucht. Im nächsten Schritt wurde die Erzeugung von PUFs in integrierten Schaltkreisen betrachtet, insbesondere in den oben genannten nichtflüchtigen Speichern. Hierzu werden Methoden genutzt, die sich bereits bei älteren Speichermodulen als erfolgreich erwiesen haben. Dazu gehören unter anderem die Variation der Versorgungsspannung, das absichtliche Unterschreiten der Zugriffszeiten sowie das Erzeugen von Bit-Flips mittels Row Hammering. Im letzten Teil dieser Dissertation wird die Integration verschiedener PUFs in praktische Anwendungen untersucht. Zu diesem Zweck wird eine FPGA-basierte Architektur entwickelt, die unter Verwendung von intrinsischen speicherbasierten PUFs das Speichermodul gleichzeitig zum Ablegen vertraulicher Daten nutzt und diese Daten zusätzlich durch einen vom gleichen Modul abgeleiteten Schlüssel an dieses bindet. Dies ist möglich, ohne zusätzlichen Speicherplatz für die PUF-Erzeugung zu reservieren. Ein weiterer praktischer Anwendungsfall im Automotive-Kontext wird demonstriert. Hier wird ebenfalls eine FPGA-basierte Lösung vorgestellt, die Authentizität und Integrität im Fahrzeug gewährleistet und gleichzeitig den zeitlichen Determinismus der Kommunikation im Fahrzeug bewahrt. Dies wird durch den Einsatz hardwaregestützter kryptografischer Algorithmen in Verbindung mit einem FPGA-basierten Ring-Oszillator-PUF erreicht. Zusammenfassend stellt diese Arbeit neuartige PUF-Implementierungen vor, die auf Konstruktionen mit Nanomaterialien und innovativen Schaltungselementen basieren. Aufbauend darauf werden Methoden zur Extraktion von PUFs aus neuartigen nichtflüchtigen Speichertechnologien untersucht. Abschließend werden praxisnahe, innovative Anwendungen auf MPSoC-Plattformen vorgestellt, die den Einsatz von PUFs demonstrieren. KW - Physical Unclonable Functions KW - Hardware Security KW - Nanomaterials KW - Emerging Memory Technologies KW - FPGAs Y1 - 2026 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:739-opus4-20104 ER - TY - THES A1 - Wirth, Olivia T1 - Digital Platforms and Mobile Technologies for Development: Essays on Firm Formalization, Financial Inclusion, and Agricultural Resilience in Sub-Saharan Africa N2 - Mobile technologies and digital platforms have expanded rapidly across sub-Saharan Africa, creating opportunities to strengthen state capacity, broaden financial inclusion, and build agricultural resilience. This dissertation examines their development impacts across three settings. Chapter 1 combines novel administrative tax records with high resolution data on mobile network rollout in Uganda to estimate the effects of mobile internet access on firm tax behavior and public revenue. Exploiting plausibly exogenous rollout timing, we find that improved access increases firm formalization and expands the tax base, strengthening revenue collection. Chapter 2 presents a randomized controlled trial in Niger—the world’s most financially excluded country—to identify barriers to adoption of a mobile money platform. Information provision raises awareness but not use, consistent with information being necessary but insufficient for diffusion. By contrast, a modest financial incentive significantly increases both adoption and usage. Chapter 3 uses a household panel collected before and after a severe drought in northern Ghana and exploits variation in rainfall in a differences-in-differences framework to estimate effects on production, income sources and adaptation plans. We find that increasing drought severity lowers soybean yields and revenues and decreases reliance on own-business income and remittances, reflecting broader livelihood impacts. Farmers who use mobile phones to access agricultural information make different input choices and adaptation plans. Taken together, these findings highlight the promise of mobile technologies and digital platforms for development. Their effectiveness, however, depends on complementary infrastructure and local capacity, underscoring the need for scalable, context-specific strategies to harness these tools for inclusive growth and resilience. KW - Digitalisierung KW - Mobilität KW - Landwirtschaft KW - Afrika Y1 - 2026 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:739-opus4-20049 ER -