Refine
Year of publication
Document Type
- Article (75)
- Workingpaper / Report (17)
- Conference Proceeding (15)
- Master's Thesis (6)
- Bachelor Thesis (2)
- Course Material (2)
- Study Thesis (2)
- Researchdata (1)
Language
- English (120) (remove)
Has Fulltext
- yes (120) (remove)
Keywords
- DOAJ (31)
- FHD (7)
- Germany (4)
- Innovation (3)
- Lehre (3)
- Master (3)
- Business Case (2)
- DEAL (2)
- Deutschland (2)
- Entrepreneurship (2)
Department/institution
- Fachbereich - Maschinenbau und Verfahrenstechnik (61)
- Fachbereich - Medien (38)
- Fachbereich - Sozial- & Kulturwissenschaften (8)
- Fachbereich - Elektro- & Informationstechnik (7)
- Sound and Vibration Engineering (7)
- Creative Media Production and Entertainment Computing (6)
- Fachbereich - Wirtschaftswissenschaften (6)
- Digitale Vernetzung und Informationssicherheit (3)
- Intelligente Mensch-Technik-Interaktion (3)
- Digital Learning and Digital Literacy (2)
There is a popular saying in German: Innovation is when the market shouts “Hooray!”. Thus, a new idea is only as good as its diffusion into the addressed social system. The question is what affects the adoption or rejection of a new idea. Carsten Deckert shares his experience on the main innovation resistances and on ways to increase the acceptance of new ideas. He talks about which perceived attributes of innovations are conducive to the rate of adoption of an innovation and which are characteristics of failed innovations.
Thermoelectric generators (TEGs) have the ability to convert waste heat into electrical energy under unfavorable conditions and are becoming increasingly popular in academia, but have not yet achieved a broad commercial success, due to the still comparably low efficiency. To increase the efficiency and economic viability of TEGs, research is performed on the materials on one hand and on the system connection on the other. In the latter case, the net output power of the cooling system plays a key role. At first glance, passive cooling seems preferable to active cooling because it does not affect the net electrical output power. However, as shown in the present review, the active cooling is to be preferred for net output power. The situation is similar in air and water-cooling. Even though air-cooling is easier to set up, the water-cooling should be preferred to achieve higher net output power. It is shown that microchannel cooling has similar hydraulic performance to conventional cooling and inserts increase the net output power of TEG. As the review reveals that active water-cooling should be the method of choice to achieve high net output power, it also shows that a careful optimization is necessary to exploit the potential.
The German banking system and the global financial crisis: causes, developments and policy responses
(2009)
Germany’s banking sector has been severely hit by the global financial crisis. In a German context as of February, 2009, this paper reviews briefly the structure of the banking industry, quantifies effects of the crisis on banks and surveys responses of economic policy. It is argued that policy design needs to enhance transparency and enforce the liability principle. In addition, economic policy should not eclipse principles of competition policy.
Music-related decision-making encompasses a wide range of behaviours including those associated with listening choices, composition and performance, and decisions involving music education and therapy. Although research programmes in psychology and economics have contributed to an improved understanding of music-related behaviour, historically, these disciplines have been unconnected. Recently, however, researchers have begun to bridge this gap by employing tools from behavioural economics. This article contributes to the literature by providing a discussion about the benefits of using behavioural economics in music-decision research. We achieve this in two ways. First, through a systematic review, we identify the current state of the literature within four key areas of behavioural economics-heuristics and biases, social decision-making, behavioural time preferences, and dual-process theory. Second, taking findings of the literature as a starting point, we demonstrate how behavioural economics can inform future research. Based on this, we propose the Behavioural Economics of Music (BEM), an integrated research programme that aims to break new ground by stimulating interdisciplinary research in the intersection between music, psychology, and economics.
This paper explores the tensions in team creativity. The tensions in team creativity are based on a tension between originality and effectiveness in the standard definition of creativity. To display the tensions in team creativity, the value square (“Wertequadrat”) developed by Schulz von Thun (1998) is used which balances a value with its countervalue. The author identifies tensions for cohesion, consensus and conformity. Cohesion is described as a tension between team diversity and team safety, consensus as a tension between constructive controversy and participatory decision-making and conformity as a tension between support for innovation and task orientation. Finally, the connection of individual and team creativity is described as an interplay between solitary and interactive components.
The definition of individual creativity is based on a tension between novelty on the one side and usefulness respectively appropriateness on the other side. The paper explores how this tension pervades the stage and componential theories of creativity. To achieve this, the so called value square (“Wertequadrat”) developed by Helwig (1967) and Schulz von Thun (1998)is used which balances a value with its countervalue to analyze creativity. The author identifies tensions of action and inaction, expertise and mindfulness, precision and ambiguity as well as immersion and detachment permeating the creative process and the components of creativity. As a conclusion a morphological box for creativity is presented which allows one to show which combination of characteristics of the tensions support different stages of creativity. Furthermore implications for development and time management are discussed.
The standard definition of creativity is based on a tension between originality and effectiveness. Borrowing from the wave-particle duality in physics one could say that there is an originality-effectiveness duality at work for creativity. The paper explores how this tension pervades Amabile's (1997) componential theory of organizational creativity with the components organizational motivation, management practices (including work assignment and work control) and resources. As a method the so called value square (" Wertequadrat ") developed by Helwig (1967) and Schulz von Thun (1998) is used which balances a value with its countervalue. The author identifies a tension of corporate tradition and corporate change for organizational motivation, a tension of skills and challenges for work assignment, a tension of management by control and management by loss of control for work control as well as a tension of organizational efficiency and organizational slack for resources. Additionally different implications of these tensions for the resistance of a company to creativity, for an organizational climate conducive to creativity as well as for resource allocation in creative endeavours are discussed.
The Long Tail theory serves as an explanation for market change triggered through evolving online market conditions. However, it is often referred to without empirical validation, or with inconsistent findings on its applicability. Therefore, this paper analyses the applicability of the Long Tail theory to German online media offerings as of 2014 and 2016, focusing on offerings that serve information purposes (information offerings). Based on a unique dataset of commercially oriented online media offerings (Longitudinal IntermediaPlus 2014–2016), an analysis for three Long Tail characteristics (variety increase, opposing concentration between hit and niche offerings and niche market share increase) is conducted. By additionally distinguishing between political and entertainment-oriented information offerings as boundaries of democratized online market conditions the analysis reveals that the Long Tail theory is not fully applicable to any market sample, and especially not to politically oriented offerings.
Heterogeneous catalysts usually consist of porous, inorganic materials. Especially in the mobile application, e.g., in exhaust gas catalysis as a part of the gas line of an engine, there are loads due to vibrations and high gas velocities. It can be assumed that physical stress will lead to a loss of the catalytically active coating. The present contribution describes experimental setups and methods for a systematic and reproducible investigation of the main influences to the mass loss due to vibrational and fluid‐mechanical stress caused by particle‐free gas flows.
Synthesis and Analysis of a Novel Linkage Mechanism with the Helical Motion of the End-Effector
(2020)
Markerless talent tracking is widely used for interactions and animations within virtual environments. In a virtual (tv) studio talents could be overburden by interaction tasks because camera and text require extensive attention. We take a look into animations and inter- actions within a studio, which do not require any special attention or learning. We show the generation of an artificial shadow from a talent, which ease the keying process, where separation of real shadows from the background is a difficult task. We also demonstrate animations of footsteps and dust. Furthermore, capturing talents’ height can also be used to adjust the parameters of elements in the virtual environment, like the position and scaling of a virtual display. In addition to the talents, a rigid body was tracked as placeholder for graphics, easing the interaction tasks for a talent. Two test productions show the possibilities, which subtle animations offer. In the second production, the rendering was improved (shadows, filtering, normal maps, ...) and instead of using the rigid body to move an object (a flag), the animation was only controlled by the hand’s position.
Spec2Vec: Improved mass spectral similarity scoring through learning of structural relationships
(2021)
Spectral similarity is used as a proxy for structural similarity in many tandem mass spectrometry (MS/MS) based metabolomics analyses such as library matching and molecular networking. Although weaknesses in the relationship between spectral similarity scores and the true structural similarities have been described, little development of alternative scores has been undertaken. Here, we introduce Spec2Vec, a novel spectral similarity score inspired by a natural language processing algorithm-Word2Vec. Spec2Vec learns fragmental relationships within a large set of spectral data to derive abstract spectral embeddings that can be used to assess spectral similarities. Using data derived from GNPS MS/MS libraries including spectra for nearly 13,000 unique molecules, we show how Spec2Vec scores correlate better with structural similarity than cosine-based scores. We demonstrate the advantages of Spec2Vec in library matching and molecular networking. Spec2Vec is computationally more scalable allowing structural analogue searches in large databases within seconds.
We present a novel metric Spatial Recall Index to assess the performance of machine-learning (ML) algorithms for automotive applications, focusing on where in the image which performance occurs. Typical metrics like intersection-over-union (IoU), precisionrecallcurves or average precision (AP) quantify the performance over a whole database of images, neglecting spatial performance variations. But as the optics of camera systems are spatially variable over the field of view, the performance of ML-based algorithms is also a function of space, which we show in simulation: A realistic objective lens based on a Cooke-triplet that exhibits typical optical aberrations like astigmatism and chromatic aberration, all variable over field, is modeled. The model is then applied to a subset of the BDD100k dataset with spatially-varying kernels. We then quantify local changes in the performance of the pre-trained Mask R-CNN algorithm. Our examples demonstrate the spatial dependence of the performance of ML-based algorithms from the optical quality over field, highlighting the need to take the spatial dimension into account when training ML-based algorithms, especially when looking forward to autonomous driving applications.
Spatial precision and recall indices to assess the performance of instance segmentation algorithms
(2022)
The Sound Spatialization Framework is a C++ toolkit and development environment for providing advanced sound spatialization for virtual reality and multimedia applications. The Sound Spatialization Framework provides many powerful display and user-interface features not found in other sound spatialization software packages. It provides facilities that go beyond simple sound source spatialization: visualization and editing of the soundscape, multiple sinks, clustering of sound sources, monitoring and controlling resource management, support for various spatialization backends, and classes for MIDI animation and handling.
Cell migration is associated with the dynamic protrusion of a thin actin-based cytoskeletal extension at the cell front, which has been shown to consist of two different substructures, the leading lamellipodium and the subsequent lamellum. While the formation of the lamellipodium is increasingly well understood, organizational principles underlying the emergence of the lamellum are just beginning to be unraveled. We report here on a 1D mathematical model which describes the reaction-diffusion processes of a polarized actin network in steady state, and reproduces essential characteristics of the lamellipodium-lamellum system. We observe a steep gradient in filament lengths at the protruding edge, a local depolymerization maximum a few microns behind the edge, as well as a differential dominance of the network destabilizer ADF/cofilin and the stabilizer tropomyosin. We identify simple and robust organizational principles giving rise to the derived network characteristics, uncoupled from the specifics of any molecular implementation, and thus plausibly valid across cell types. An analysis of network length dependence on physico-chemical system parameters implies that to limit array treadmilling to cellular dimensions, network growth has to be truncated by mechanisms other than aging-induced depolymerization, e.g., by myosin-associated network dissociation at the transition to the cell body. Our work contributes to the analytical understanding of the cytoskeletal extension's bisection into lamellipodium and lamellum and sheds light on how cells organize their molecular machinery to achieve motility.
Reconciling work and family life is one of the main issues of welfare state policies in the fields of childcare and long-term care. On that account, policy and research are focused almost exclusively on women – often on the reconciliation of work and childbearing – and social policy at the state level. In our study, we concentrate on men who reconcile gainful employment with elderly care, and we include the company level – a level of analysis often neglected in traditional theoretical approaches and typologies of comparative welfare state research. In Germany, during the last decade, the share of sons who are responsible for taking care of their elderly relatives has remarkably increased. In our qualitative research, we carried out comparative case studies in eleven German companies. We conducted around 60 interviews with male employees caring for an elderly relative, as well as with members of the works councils and human resources departments in different kinds of companies. We analysed which familial, social, professional, legal as well as occupational resources are central for these men, how they cope with reconciling work and care, and which gaps in the welfare system they identify. Interestingly, the overwhelming majority of the caring sons claim not to have problems in reconciling work and care, although they spend significant time on caring. In this paper we try to explain this pattern by looking at their typical care arrangements. We found that while women tend to organise employment around care, men rather seem to organise care around their employment. Given the feminist critique of the “adult worker model” this is an interesting result and needs theoretical reflection. Do men have the solution to the care-blindness of the “adult worker model” without falling into the “cold modern model of care”? Which resources are mainly used in “adult worker care arrangements”? Where are the limits of the approach?
The “fair” taxation of digital business models is challenging. One of the key aspects – both policy makers and the public opinion consider as most pressuring – is the determination of intragroup transfer prices for intangibles used in digital business models. In this paper, we address the issue of a “perceived fair” taxation of the digital economy in the light of the arm’s length principle based on a survey with transfer pricing experts. The aim of the survey is not to estimate arm’s length profit allocations but rather to elicit fairness considerations in different transfer pricing related scenarios. In a digital economy framework where arm’s length profits are distributed extremely inequitably, subjects perceive this distribution of profits as most unfair compared to more balanced scenarios. Consequently, subjects propose a “fair” distribution of profits that substantially differs from the exogenously given arm’s length allocation. In scenarios with a more balanced arm’s length allocation of profits, we find that the perceived fairness for the expert groups increases while a control group of business students is almost not influenced by the arm’s length allocation of profits.
The decarbonization of for example the energy or heat sector leads to the transformation of distribution grids. The expansion of decentralized energy resources and the integration of new consumers due to sector coupling (e.g. heat pumps or electric vehicles) into low voltage grids increases the need for grid expansion and usage of flexibilities in the grid. A high observability of the current grid status is needed to perform these tasks efficiently and effectively. Therefore, there is a need to increase the observability of low voltage grids by installing measurement technologies (e.g. smart meters). Multiple different measurement technologies are available for low voltage grids which can vary in their benefit to observation quality and their installation costs. Therefore, Bayernwerk Netz GmbH and E.DIS AG in cooperation with E-Bridge Consulting GmbH and the Institute for High Voltage Equipment and Grids, Digitalization and Energy Economics (IAEW) investigated the effectiveness of different strategies for the smartification of low voltage grids. This paper presents the methodology used for the investigation and exemplary results focusing on the impact of intelligent cable distribution cabinets and smart meters on the quality of the state estimation.
In the EILD.nrw project, Open Educational Resources (OER) are being developed for teaching databases. Instructors can use the tools and courses in a variety of learning scenarios. Students of computer science and application subjects learn the complete life cycle of databases. For this purpose, quizzes, interactive tools, instructional videos, and courses for learning management systems are developed and published under a Creative Commons license.
The settling velocities of helminth eggs of three types, namely Ascaris suum (ASC), Trichuris suis (TRI), and Oesophagostomum spp. (OES), in clean tap water are computationally determined by means of computational fluid dynamics, using the general-purpose CFD software ANSYS Fluent 18.0. The previous measurements of other authors are taken as the basis for the problem formulation and validation, whereby the latter is performed by comparing the predicted sink velocities with those measured in an Owen tube. To enable a computational treatment, the measured shapes of the eggs are parametrized by idealizing them in terms of elementary geometric forms. As the egg shapes show a variation within each class, “mean” shapes are considered. The sink velocities are obtained through the computationally obtained drag coefficients. The latter are defined by means of steady-state calculations. Predicted sink velocities are compared with the measured ones. It is observed that the calculated values show a better agreement with the measurements, for ASC and TRI, compared to the theoretical sink values delivered by the Stokes theory. However, the observed agreement is still found not to be very satisfactory, indicating the role of further parameters, such as the uncertainties in the characterization of egg shapes or flocculation effects even in clean tap water.
Music consumption and distribution has changed drastically in the last twenty years due to digitalization. Instead of buying music products, like CDs or even downloaded digital music files, today music is predominantly distributed via online music streaming. Therefore, it is mandatory for the music industry as well as researchers to determine which factors are affecting consumers intention to use music streaming services. This study aims to investigate drivers of Behavioral Intention (BI) to use a music streaming service. Particularly, aspects of social preferences in the context of music streaming will be explored. Therefore, a research model is created, based on the Value-based Adoption Model (VAM) (Kim et al., 2007) with an extension to take social factors into account. An online questionnaire with 102 participants was conducted to test the research model and the corresponding hypotheses. In order to evaluate reliable indications, some adjustments needed to be made resulting in a corrected research model. The final independent variables of the corrected model are Perceived Value (PV) (which is composed of Perceived Usefulness (PU) and Perceived Enjoyment (PE)), Perceived Ease of Use (PEU), Perceived Price Value (PPV), Facilitating Conditions (FC), Perceived Fairness (PF), Social Connectivity (SC), and Peer-Effects (PFX). The empirical results show that Perceived Value (PV), Perceived Price Value (PPV), and Perceived Fairness (PF) are determinants of consumers Behavioral Intention (BI) to use a music streaming service.
Mass spectrometry data is one of the key sources of information in many workflows in medicine and across the life sciences. Mass fragmentation spectra are generally considered to be characteristic signatures of the chemical compound they originate from, yet the chemical structure itself usually cannot be easily deduced from the spectrum. Often, spectral similarity measures are used as a proxy for structural similarity but this approach is strongly limited by a generally poor correlation between both metrics. Here, we propose MS2DeepScore: a novel Siamese neural network to predict the structural similarity between two chemical structures solely based on their MS/MS fragmentation spectra. Using a cleaned dataset of > 100,000 mass spectra of about 15,000 unique known compounds, we trained MS2DeepScore to predict structural similarity scores for spectrum pairs with high accuracy. In addition, sampling different model varieties through Monte-Carlo Dropout is used to further improve the predictions and assess the model's prediction uncertainty. On 3600 spectra of 500 unseen compounds, MS2DeepScore is able to identify highly-reliable structural matches and to predict Tanimoto scores for pairs of molecules based on their fragment spectra with a root mean squared error of about 0.15. Furthermore, the prediction uncertainty estimate can be used to select a subset of predictions with a root mean squared error of about 0.1. Furthermore, we demonstrate that MS2DeepScore outperforms classical spectral similarity measures in retrieving chemically related compound pairs from large mass spectral datasets, thereby illustrating its potential for spectral library matching. Finally, MS2DeepScore can also be used to create chemically meaningful mass spectral embeddings that could be used to cluster large numbers of spectra. Added to the recently introduced unsupervised Spec2Vec metric, we believe that machine learning-supported mass spectral similarity measures have great potential for a range of metabolomics data processing pipelines.
While developing for multiple platforms at once seems like a convenient solution, there are several challenges arising when trying to abstract the entire mobile development. This paper is meant to evaluate current cross-platform development for mobile applications. The background for its necessity, its conceptual approach and the problems to face when developing cross-platform were determined and explained in detail. Afterwards, certain solutions were evaluated against the former insights. Based on the results, an informed discussion and conclusion was performed. The mobile environment consist of only two big players by now, Android and iOS. These operating systems differ in architecture, design and consequently in the way applications are developed for each of them. Therefore, high demands are made towards cross-platform solutions. Tools which allow for the creation of applications for multiple platforms at once have to match native applications in regard to user experience and performance. At the same time they need to be able to optimize developments with the goal of being cost efficient. Apache Cordova, Xamarin and NativeScript were selected for evaluation in regard to their ability to meet these requirements. Cordova acts as the comparison group of cross-platform tools. It is the big player in the field and there are reasons for this. However, aspiring solutions with higher nativity and ambitious approaches are emerging. Xamarin and NativeScript deliver top quality results while offering loosely coupled developments. Therefore it is possible to develop high quality applications and still benefit from the advantages of platform-independent solutions. As a consequence mobile development is about to change in the foreseeable future. More sophisticated approaches may lead to a higher number of developments done cross-platform, and rightfully so.
Progressive web applications (PWAs) seem to be the next big thing in the mobile landscape. These are web applications with “super-powers” which are meant to provide the kinds of user experiences previously only native mobile applications could. Therefore they are able to match native applications in their capabilities but still thrive on the reachability of the web. They achieve this by implementing certain characteristics which originate from innovative standards and sophisticated best practices. Conveniently, as it is the web, PWAs are working seamlessly cross-platform. One of the closest things to a PWA so far may be an application created with the NativeScript framework. Such an application is also developed with web technologies yet able to use any native interface directly. This is made possible by using a designated runtime for mediating between JavaScript and the mobile system. Eventually, NativeScript is able to offer a high degree nativity yet also of convenient abstraction during development. This paper is set out to deliver further insight into both approaches by contrasting them based on the characteristics of PWAs. For this purpose, these characteristics are elaborated and adjusted to be applicable to native mobile applications. Hence a reasonable basis for what to expect from a native application is derived. Then NativeScript is assessed on this basis by the means of transferable concepts and technologies as well as a prototypic mobile application. Finally, an informed discussion and conclusion is performed based on the results. The comprehensive characteristics of PWAs resolve previous shortcomings with well thought out concepts and new technologies. These are transferable to native mobile applications to a far extent and may also be put into practice with NativeScript. The framework’s approach may be very well called ingenious, however, in the long run it might fall short of the innovative concept of PWAs. Having said this, it is still able to serve as a practical measure for creating appealing user experiences for multiple systems with arguably little effort. Due to large overlap a transformation between the two application types is a realistic option. Either way, web technologies are far from what they used to be and it is exciting to see how the mobile and web landscape will evolve in the future.
The article discusses the question of “How to convey the experience in a virtual environment to third parties?” and explains the different technical implementations which can be used for live streaming and recording of a mixed reality experience. The real-world applications of our approach include education, entertainment, e- sports, tutorials, and cinematic trailers, which can benefit from our research by finding a suitable solution for their needs. We explain and outline our Mixed Reality systems as well as discuss the experience of recorded demonstrations of different VR applications, including the need for calibrated camera lens parameters based on realtime encoder values.
The task of the Center for Language Research is to provide content-based English language instruction for students of computer science and engineering. As such, we find ourselves at the confluence of many of the streams currently running through the English Language Teaching profession, including English for Science and Technology (EST), English for Academic Purposes (EAP), English for Specific Purposes (ESP), Computer-assisted language learning (CALL), content-based instruction, and multimedia applications in foreign language pedagogy. This paper describes our initial attempts to construct a number of World Wide Web pages where students will be able to study EST, EAP, and computer science topics on their own in a multimedia environment.
Methanol Synthesis with Steel Mill Gases: Performance Investigations in an On‐Site Technical Center
(2021)
This dissertation, written for the course Master of European Social Policy Analysis – National University of Ireland Maynooth - , shows the context or so-called framework within which the medical social work service in two different welfare states: Ireland and Germany operates. This means the societal context as a whole, the health system in general (macro-level) and the hospital setting (mezzo-level) in particular. The idea of this publication is to give a short overview of the historic development of medical social work (micro-level) in Ireland and Germany and some background information about what medical social work is. The time frame examined starts from the 1980s up to present. The main questions to be answered are: What are the interdependencies between the macro-, mezzo- and micro-level? Have changes in the health system in general and the hospitals in particular influenced medical social work and if so how? What are the similarities and differences in the two countries?
Marktdaten
(2018)
Die in der Schriftenreihe Trading verwendeten Forschungsdaten beinhalten historische Kursdaten, geliefert von Lenz+Partner AG (Deutschland), für eine Auswahl an Aktien. Die Datei „FEBRDUSA_1“ zeigt diese Auswahl in Form der deutschen Wertpapierkennnummer (Spalte „Titel“), des Handelszeitraums (Spalten „Beginn“ und „Ende“) und des Aktiennamens. Kursdaten sind in dieser Datei nicht enthalten, sondern liegen in einer umfangreichen Datenbank vor.
Die Marktdaten umfassen 867 Aktien und sind das Ergebnis eines im Jahr 2015 durchgeführten Auswahlprozesses mit dem Ziel, Datenqualität und Handelbarkeit der Aktien zu verbessern. Es wurden folgende Bedingungen gefordert:
- Die Aktien werden an der Frankfurter Börse gehandelt.
- Sie sind in einem der deutschen Aktienindizes DAX, MDAX, TECDAX, SDAX, HDAX, CDAX, Technology All Share, Prime All Share und GEX oder in den amerikanischen Aktienindizes S&P 500 oder Nasdaq 100 gelistet.
- Die Kursdaten der in Frankfurt gehandelten Aktien enden nicht vor dem Jahr 2014.
- Der (unbereinigte) Eröffnungskurs Ende 2013 beträgt mindestens 1 EUR. Diese Bedingung soll dazu beitragen, das Handeln von „penny stocks“ zu verhindern.
Die vorliegende Marktdefinition resultierte in 867 Aktien, die frühestens am 11. Dezember 2014 enden, sodass eine Auswertung der Marktdaten mit vollständigen Kurswerten bis zu diesem Zeitpunkt möglich ist. Der Markt ist groß genug, um interessante Kaufbedingungen mit einer ausreichend großen Anzahl an Kaufkandidaten zu untersuchen.
Magneto-hydrothermal triple-convection in a W-shaped porous cavity containing oxytactic bacteria
(2022)
Bioconvective heat and mass transport phenomena have recently been the subject of interest in diverse fields of applications pertaining to the motion of fluids and their thermophysical properties. The transport processes in a system involving triple convective phenomena, irregular geometry, and boundary conditions constitute a complex phenomenon. This work aims to explore the mixed thermo-bioconvection of magnetically susceptible fluid containing copper nanoparticles and oxytactic bacteria in a novel W-shaped porous cavity. The buoyant convention is generated due to the isothermal heating at the wavy bottom wall, whereas the mixed convection is induced due to the shearing motion of the top-cooled sliding wall. Furthermore, the bioconvection is induced due to the manifestation of oxytactic bacteria or organisms. The inclined sidewalls are insulated. The geometry is packed with water based Cu nanoparticle mixed porous structure, which is subjected to a magnetizing field acted horizontally. The complex transport equations are transformed into nondimensional forms, which are then computed using the finite volume-based developed code. The coupled triple-convective flow physics are explored for a wide range of involved controlling parameters, which could provide helpful insight to the system designer for its proper operation. The shape of geometry can be considered one of the important parameters to control the heat and mass transport phenomena. In general, the influence of amplitude (δ) is more compared to the waviness number (m) of the undulations. The magnitude of heat (Nu) and mass (Sh) transfer rate for the W-shaped cavity is high compared to conventional square and trapezoidal-shaped cavities. The output of the analysis could be very helpful for the designer for modeling devices operating on nanotechnology-based bioconvection, microbial fuel cells, and others.
Land of High Hopes
(2019)
We are living in the era of sophisticated, state-of-the-art technology, artificial intelligence, accelerating data sciences at ultimate speed and sheer unlimited possibilities. We are able to shoot unmanned rockets equipped with vehicles into the orbit. We can afford to spend fortunes on research and development. However, and that leaves me bloodcurdling and furious, we haven´t managed yet to settle at least some of the most pressing global humanitarian needs: access to food, water, electricity, education and healthcare. So how can we be proud of any achievements? What does make us proud anyway?! ...
Sound and music are well-studied aspects of the quality of experience in restaurants; the role of the room acoustical conditions, their influence on the visitors’ soundscape evaluation and their impact on the overall customer satisfaction in restaurants, however, has received less scientific attention. The present field study therefore investigated whether sound pressure level, reverberation time, and soundscape pleasantness can predict factors associated with overall restaurant quality. In total, 142 persons visiting 12 restaurants in Berlin rated relevant acoustical and non-acoustical factors associated with restaurant quality. Simultaneously, the A-weighted sound pressure level (LA,eq,15) was measured, and the reverberation time in the occupied state (T20,occ) was obtained by measurements performed in the unoccupied room and a subsequent calculation of the occupied condition according to DIN 18041. Results from linear mixed-effects models revealed that both the LA,eq,15 and T20,occ had a significant influence on soundscape pleasantness and eventfulness, whereby the effect of T20,occ was meditated by the LA,eq,15. Also, the LA,eq,15 as well as soundscape pleasantness were significant predictors of overall restaurant quality. A comprehensive structural equation model including both acoustical and non-acoustical factors, however, indicates that the effect of soundscape pleasantness on overall restaurant quality is mediated by the restaurant’s atmosphere. Our results support and extend previous findings which suggest that the acoustical design of restaurants involves a trade-off between comfort and liveliness, depending on the desired character of the place.
This paper investigates the implementation of a human body model for the simulation of a jumping motion in Simulink. It contains details to get an insight into modern biomechanics without previous experience. In the simulation, a Hill-Type muscle is used to generate joint momentum with a phenomenologically realistic relationship between muscle length and force. The simulation published with this article is one of many solutions to design a humanoid simulation. The paper guides through the implemented build and explains its range of application.
Investing as Random Trial
(2017)
We introduce an investment algorithm for a market of individual securities. The investment algorithm is derived from constraints depending on investment parameters in order to limit the risk and to take into account an individual investor. One constraint is devoted to trading costs. Purchased securities are selected randomly among securities that meet the buy condition, making trading a random trial. Simulations with historical price data are demonstrated for a simple example: The buy condition is evaluated on the basis of the price relationship for two subsequent trading days and the sales condition is defined by holding securities only for one day. A trading expert evaluates the expected return for the investment algorithm with respect to the random selection. Thus, the expert informs precisely on how many market players perform using the same investment algorithm. Its findings are for a parametrized set of buy conditions simultaneously, which makes a trading expert a valuable tool for theorists as well as for practitioners. In our example, the trading expert demonstrated clearly a significant mean reversion effect for a horizon of one day.
Impact of Renewable Energy Expansion to the Balancing Energy Demand of Differential Balancing Groups
(2018)
The research addresses the present situation on the German electricity market caused by variable renewable energy sources. The increasing number of households with photovoltaic and battery storage systems and their impacts require special attention. These systems change the traditional electricity customer from the sole electricity consumer to an electricity producer and consumer in one person. These so-called prosumers differ in their actual electricity demand from the initially estimated electricity demand with standard load profile. This discrepancy results in deviations within a differential balancing group. Thereby, the main finding of this research is a significant higher balancing energy demand with the expansion of photovoltaic and battery storage systems. Hence, the standard load profile is particularly not suitable for differential balancing groups with a high penetration of solar systems and still less suitable for groups with solar and battery storage systems
CFX 11.0 is a Computational Fluid Dynamics (CFD) program for simulating the behavior of systems involving fluid flow, heat transfer, and other related physical processes. It works by solving the equations of fluid flow (in a special form) over a region of interest, with specified (known) conditions on the boundary of that region. This tool is used here to analyse the straw cutter which is used to comminute the straw which is left standing in the field after stripper header has stripped the grains from the crops. Stripper Header is a new technique different to conventional harvester machines and it is still under development and testing. It works on the principle in which grains are first stripped off from the head of the standing crop which helps in much reduced intake freeing up the separation systems to handle a larger volume of grains. But with this, the new problem of the disposal of the long, uncut straw left after stripping of grains arose. So a straw cutter is used after the stripper header stage in this Combine Harvester, where the rotor is equipped with pressed steel blades and rotates towards the crop, i.e., it cuts and lifts the straw over the top. This technique is environment friendly because previously farmers would have to burn the long, uncut straw standing in the fields while in this case mulched straw can be used for min-till systems. This rotor based straw cutting machine is analysed here which helps us in increasing power efficiency and comminution rate and quality of cut straw particles. Here fluid flow simulation has been preferred over particle simulation: - CFX 10.0 tool is not very effective for particle simulation techniques and computation time is increased considerably. - It’s very hard to realize particle simulation in CFX 10.0 because we have to define size and properties of each particle and besides this wall conditions would have to be defined differently for every boundary. - Besides this, it’s hard to realize cutting effect with straw particles in CFX 10.0 which otherwise would be comminuted in real life conditions. - The results obtained from fluid simulation are validated using experimental results and found to be nearly the same which clearly contradicts any need of performing particle simulation.
The population is growing constantly in urban areas. This results in an increasing demand for mobility solutions while it is also worldwide aimed to reduce greenhouse gas emissions. This paper summarizes the results of a comparative study concerning the greenhouse gas emissions (based on carbon footprint) caused by alternative urban passenger transportation systems. The emissions for the vehicles and their infrastructure are analyszed over the entire life cycle from manufacturing up to their end of life. An existing cable car sytem in La Paz, Bolivia was analysed and evaluated in comparison to other modes of transportation such as small busses, large busses and a tram. According to the system definitions and the considered balance framework the study shows that beside the use of the systems the materials and the manufacturing as well as the infrastructure have a significant impact on the total emissions over the life cycle. To put focus on the „true and real“ impacts to the society it is preferable to consider the measurement results in total absolute emissions.
This essay looks at the potentials and limitations of user research for studies on the practice of drama education. To date, this field has been dominated by impact studies. After illustrating the blind spots that are created by taking this research approach to the practice of drama education, we will present the user research perspective and look at the opportunities that it provides to generate new, differentiated knowledge. User research makes it possible to illuminate the processes of acquiring and using knowledge in terms of its delivery. It also provides a potential framework of analysis for placing these processes in the delivery context, which includes subjective learning types, relevance and institutional and social conditions. This expanded perspective will make it possible to identify the factors that foster and limit benefits and reflect them in practice.
In order to determine demand as precisely as possible, many businesses use several forecasting methods. The aim of forecasting is to determine future demand based on data from the past. The use of a specific method is not always easy and depends on a number of factors. To help prospective engineers find the most suitable forecasting method for a specific problem, a forecasting game was developed and then evaluated.
The paper describes the design and the evaluation of the forecasting game. In order to provide an overview of existing forecasting methods, the first part of the paper examined the mathematical fundamentals of eight different forecasting methods and outlined the requirements for their application.
The second part of the paper describes the creation of a forecasting game in which prospective engineers can learn how to determine the appropriate forecasting method for specific scenarios. In total, five scenarios covering the three different demand patterns (linear/stationary, trend and seasonal) as well as the forecast quality methods were developed and can be played through. For each scenario, the player has to choose the most appropriate forecasting method for a specific problem based on a self-created task description. To make the game as realistic as possible, a fictional company with a background story was designed.
The last part was about the evaluation of the forecasting game. For the evaluation, a student survey to gather the opinions of the students was conducted. The results of the student survey show an overall positive evaluation of the simulation game by the students. However, the test also showed that the game takes a certain amount of time. Since only 15 of the approximately 30 students who tested the game participated in the evaluation, the results are not significant.
The OECD Base Erosion Profit Shifting (BEPS) Initiative as well as the current fairness oriented public discussion regarding the taxation of digital business models highlight the importance and complexity of the arm's length principle. In a theoretical model of an internationally fragmented digital good's production process, we show that fairness considerations of tax authorities (namely inequity aversion) can result in a falling apart between a perceived "fair" and arm's length distribution of profits across tax jurisdictions. Our model predicts that a multinational firm follows the fundamental paradigm of international taxation, i.e. the arm's length principle, to properly incentivize internal agents involved in the production of a digital good. However, with inequity averse tax authorities, we find that tax authorities "prefer" a more equal distribution of profits compared to the arm's length allocation. From a multinational firm's perspective, inequity aversion among tax authorities dampens the strategic effect to - in accordance with arm's length principle - shift profits to low tax countries.
Despite their overwhelming complexity, living cells display a high degree of internal mechanical and functional organization which can largely be attributed to the intracellular biopolymer scaffold, the cytoskeleton. Being a very complex system far from thermodynamic equilibrium, the cytoskeleton's ability to organize is at the same time challenging and fascinating. The extensive amounts of frequently interacting cellular building blocks and their inherent multifunctionality permits highly adaptive behavior and obstructs a purely reductionist approach. Nevertheless (and despite the field's relative novelty), the physics approach has already proved to be extremely successful in revealing very fundamental concepts of cytoskeleton organization and behavior. This review aims at introducing the physics of the cytoskeleton ranging from single biopolymer filaments to multicellular organisms. Throughout this wide range of phenomena, the focus is set on the intertwined nature of the different physical scales (levels of complexity) that give rise to numerous emergent properties by means of self-organization or self-assembly.
Poor young people more often face health difficulties, (learning) disabilities, and are overrepresented in special schools. Consequently, youth from poor households disproportionately frequently participate in disability‐specific programs aiming to improve their educational levels and labor market opportunities. They face a double burden of disability and poverty. In our study, we look at poor and non‐poor youth with disabilities (YPWD) who participate in vocational rehabilitation (VR) and whether VR helps them (a) in transitioning into employment and (b) in leaving poverty. We examine the association between the receipt of initial basic income support (BIS) as a poverty indicator, later labor market outcomes, and earned vocational qualification using administrative data. We make use of a sample of all persons accepted for VR in 2010 (N = 36,645). We employ logit models on VR attendees’ labor market outcomes three and five years after being accepted for VR as well as on their earned vocational qualifications. Beside initial poverty status, we control for educational level, type, and degree of disability and program pattern during the VR process. Our findings show that YPWD from poor households have a decreased likelihood of a vocational certificate and employment. Additionally, they are more likely to receive BIS than young people not from poor households and thus more likely to remain poor. In conclusion, VR seems to support poor YPWD less in their school‐to‐work transitions. Thus, disability‐specific programs should be more tailored to the social situations of participants, and counsellors should be more sensitive to their social backgrounds.
The impact of culture on entrepreneurship is a widely accepted phenomenon. Cultural factors influence entrepreneurship via different mechanisms on the macro-, meso-, and micro-level of a country. Building on existing research, we draw a clear link between national cultural dimensions and entrepreneurship, using a new model that arranges different cultural dimensions in groups based on their particular function: political, social, or individual (PSI-model) and that distinguishes between values and practices where relevant. The PSI-model provides a coherent theoretical framework on which different cultural dimensions and their impact on entrepreneurship can be analysed, allowing for particular attention to be drawn to social practices and social values. This paper contributes to a better understanding of the relationship between culture and entrepreneurship, providing empirical evidence of how specific cultural dimensions influence entrepreneurship. The findings are of relevance from a policy perspective and can be used to generate practical recommendations for national institutions interested in promoting entrepreneurship and entrepreneurial activities. The findings are also transferable to other fields related to national cultural dimensions such as level of innovation, investment, budgeting etc.
The links between innovativeness as a driver of economic performance, and the determinants of innovativeness have been investigated by management scholars and economists for decades, focusing mostly on “hard factors” as investment in research and development, or education. Focusing on a relatively neglected, but in times of globalization even more important aspect, the infuence of cultural characteristics on innovativeness, we apply diferent econometric models to test for links between cultural tightness and looseness on the one hand, and national innovativeness on the other hand. We fnd that cultural tightness—in the sense of homogenous and intolerant societies—has a negative link to national innovativeness, while cultural looseness—in the sense of tolerant and diverse societies—displays a positive link to national innovativeness.
The late immersion of multi-touch sensitive displays enables the use of tangibles on multi-touch screens. There a several wide spread and/or sophisticated solutions to fulfill this need but they seem to have some flaws. One popular system at the time of writing is an overlay frame that can be placed on a normal display with the corresponding size. The frame creates a grid with infrared light emitting diodes. The disruption of this grid can be detected and messages with the positions are sent via usb to a connected computer. This system is quite robust in matters of ambient light insensitivity and also fast to calibrate. Unfortunately it is not created with the recognition of tangibles in mind and printed patterns can not be resolved. This article summarizes an attempt to create fiducials that are recognized by an infrared multi-touch frame as fingers. Those false fingers are checked by a software for known patterns. Once a known pattern (= fiducial) has been recognized its position and orientation are send with the finger positions towards the interactive software. The usability is tested with an example application where tangibles and finger touches are used in combination.
Education at the University of Aizu is focussed upon computer science. Besides being the subject matter of many courses, however, the computer also plays a vital role in the educational process itself, both in the distribution of instructional media, and in providing students with valuable practical experience. All students have unlimited access (24-hours-a-day) to individual networked workstations, most of which are multimedia-capable (even video capture is possible in two exercise rooms). Without software and content tailored for computer-aided instruction, the hardware becomes an expensive decoration. In any case, there is a need to better educate the instructors and students in the use of the equipment. In the interest of facilitating effective, collaborative use of network-based computers in teaching, this article explores the impact that a network environment can have on such activities. First, as a general overview, and to examine the motivation for the use of a network environment in teaching, this article reviews a range of different styles of collaboration. Then the article shows what kind of tools are available for use, within the context of what has come to be called Computer-Supported Cooperative Work (CSCW).
The construction of a basis of a certain lattice of interest is a basic tool in many fields of algorithmic number theory. All too often we can not compute with the original lattices because of irrational numbers involved but have to work with approximations of them. While helpful bounds were shown about the reduction of lattice bases in cite{buchmann94reducing}, here we introduce the notion of a $(epsilon,delta)$-constructable basis of a lattice and determine the precision of vectors that is necessary to extend a set to a $(epsilon,delta)$-constructable basis.
Actin filaments are conductive to ionic currents, mechanical and voltage solitons. These travelling localisations can be utilised to generate computing circuits from actin networks. The propagation of localisations on a single actin filament is experimentally unfeasible to control. Therefore, we consider excitation waves propagating on bundles of actin filaments. In computational experiments with a two-dimensional slice of an actin bundle network we show that by using an arbitrary arrangement of electrodes, it is possible to implement two-inputs-one-output circuits.
Computational investigation of hemodynamics in hardshell venous reservoirs: A comparative study
(2019)
Extracorporeal circulation using heart‐lung‐machines is associated with a profound activation of corpuscular and plasmatic components of circulating blood, which can also lead to deleterious events such as systemic inflammatory response and hemolysis. Individual components used to install the extracorporeal circulation have an impact on the level of activation, most predominantly membrane oxygenators and hardshell venous reservoirs as used in extracorporeal systems. The blood flows in two different hardshell reservoirs are computationally investigated. A special emphasis is placed on the prediction of an onset of transition and turbulence generation. Reynolds‐averaged numerical simulations (RANS) based on a transitional turbulence model, as well as large eddy simulations (LES) are applied to achieve an accurate prediction. In the LES analysis, the non‐Newtonian behavior of the blood is considered via the Carreau model. Blood damage potential is quantified applying the Modified Index of Hemolysis (MIH) based on the predicted flow fields. The results indicate that the flows in both reservoirs remain predominantly laminar. For one of the reservoirs, considerable turbulence generation is observed near the exit site, caused by the specific design for the connection with the drainage tube. This difference causes the MIH of this reservoir to be nearly twice as large as compared to the alternative design. However, a substantial improvement of these performance criteria can be expected by a local geometry modification.
Room reverberation alters the spatial impression and timbre of a sound by modulating its spectral and temporal characteristics. Thus, we argue that, on a perceptual level, reverberation basically breaks down into interaural differences and spectro-temporal cues and that the separation of a perceived timbre into a sound source and a surrounding room is a purely cognitive process. To investigate the connection between the perception of reverberation cues and timbre analysis, the sensitivity for changes in reverberation was compared to timbre perception abilities. The Timbre Perception Test was used to measure the perception of the temporal envelope, spectral centroid, and spectral flux of artificial sounds. Sensitivity for changes in reverberation time was tested with a discrimination task using speech and noise with speech-alike spectral and temporal envelopes as source signals. Musical and acoustical expertise was assessed through the Goldsmiths Musical Sophistication Index and self-reports on experience with and knowledge of acoustics. There was a considerable correlation between timbre and reverberance perception ability, but timbre perception and academic experience predicted only 41% of the variance in reverberance perception. Still, perception abilities related to similar acoustical phenomena seem to be better indicators of listening skills than self-reports on acoustical or musical expertise.