Universität Stuttgart
Permanent URI for this communityhttps://elib.uni-stuttgart.de/handle/11682/1
Browse
34 results
Search Results
Item Open Access A model-based framework for the assessment of energy-efficiency and CO2-mitigation measures in multi-cylinder paper drying(Stuttgart : Universität Stuttgart, Institut für Energiewirtschaft und Rationelle Energieanwendung, 2022) Godin, Hélène; Radgen, Peter (Prof. Dr.-Ing.)Thesis on the effect of energy-efficiency and CO2-mitigation measures in multi-cylinder paper drying.Item Open Access Untersuchung einer Augmented Reality Kollaborationssoftware in der verteilten agilen Arbeitsweise der Automobilentwicklung(2024) Dyhringer, Robert; Resch, Michael (Prof. Dr.-Ing. Dr. h.c. Dr. h.c. Prof. e.h)Der Begriff Metaverse motiviert seit 2021 neue Forschung in der Wissenschaft, insbesondere in der Automobilentwicklung. Die Kombination von agilen Arbeitsweisen und verteilter Zusammenarbeit wirft neue Herausforderungen auf, die durch den Einsatz einer kollaborativen Augmented Reality Software bewältigt werden können. Eine methodisch entwickelte Software und wissenschaftliche Studien zeigen in dieser Arbeit, dass die Technologie der Augmented Reality die gleichberechtigte Gruppenarbeit und die Kommunikation in einem agilen Setup verbessern kann.Item Open Access Urban health games. Collaborative, expressive & reflective(2012) Knöll, Martin; De Bruyn, Gerd (Prof. Dr. phil.)In order to promote healthy lifestyles and wellbeing, many public health experts call for innovative and transdisciplinary research approaches. They welcome contributions from a great variety of professions including nutritional and environmental sciences, epidemiology, medicine, geography, sports sciences and urban planning. Meanwhile, designers are investigating the ways in which new layouts for lunch rooms may better inform people about healthier food choices. Architects and urban planners are stressing pedestrian-friendly street networks and buildings to such an extent that they discreetly hide away elevators to encourage people climbing the stairs. With this dissertation, I would like to draw attention to digital health games as a participatory, location sensitive and playful approach to promote healthy behaviours, which so far has been little addressed by urban research. Health games aim to be entertaining, but also seek to engage players into learning or physical exercise. One of their commercially most successful products to date - Nintendo's Wii Sports series - may be played foremost in peoples' homes. However, health games run increasingly on mobile devices and begin to interact with their topographic, cultural and social context. The iPhone game Monumental for instance invites players to climb iconic monuments such as Eiffel Tower or Empire State Building. At the same time, the game is tracking players' movement through the iPhone's on-board accelerometer. Their designers hope to engage participants by beating personal high scores and by competing with their friends via Facebook or other social networking sites. Several mobile games likewise have explored the potentials of social influence for health promotion. Notably, they have highlighted architectural theory as a major source of inspiration claiming to learn from cities and buildings how to stimulate social interaction and support. With this dissertation, I would like to invite further consideration on how architectural and urban research can contribute to the design and analysis of digital health games. Beyond providing health-related expertise on specific buildings, places and topographies, I will demonstrate how architectural and urban theory reveals a profound source to discuss aspects of user participation, social interaction and can help to create a wider range of gameplay experiences. In turn, I will demonstrate how what I define as urban health games may unfold particular potentials as a design tool that enables users to discuss and indicate health-orientated urban interventions. I will therefore investigate architectural and urban design theory with a focus on spatial strategies to support health-related behaviour. Seeking to involve users into design processes as much as possible, I will pay particular attention to the theoretical concepts of so-called "organic" architects from the first half of 20th century. The latter have criticised precisely those colleagues, who we may consider as functionalist and indeed health-orientated. Hugo Häring for instance criticised Le Corbusier for imposing idealistic, over-rational and pre-fixed designs onto peoples' daily routines. In contrast, he claimed for users to articulate design briefs and wanted architects to develop open-ended design processes. I will follow the notion of temporary, personally tailored architecture to post-war planners such as Archigram and Yona Friedman. Building upon these concepts, I will demonstrate how today's mobile technologies can contribute to the advantages of making users aware of environmental influences on one's health and wellbeing. To this end I will investigate how the notion of serious games has developed as a temporary experience that connects mobile technology, body data and different real world locations. Whereas traditional sports have highlighted self-improvement and foremost competitive forms of play, I will show how health games will have to explore a wider range of play activities to appeal to their audience. Investigating game design theory and relating it to relevant urban projects, I will highlight more creative forms of playing digital health games in the city. Understanding urbanity as state of increased social and cultural exchange and reflecting on attempts for re-appropriating urban space through spatial practices, I will illustrate what may render mobile and location sensitive health games as distinctively urban. I will conclude this investigation by presenting three ways of playing health games in the city as collaborative, expressive and reflective. This framework will be based on an analysis of how current examples of health games benefit from and contribute to their social and built environment.Item Open Access 3D CFD Simulation von Turboladern innerhalb einer Motorumgebung(2014) Boose, Benjamin; Bargende, Michael (Prof. Dr.)Im Rahmen dieser Forschungsarbeit wird das Verhalten mehrflutiger Abgasturbolader innerhalb einer Motorumgebung mit pulsierenden Randbedingungen in verschiedenen Motorbetriebspunkten mittels eines CFD Ansatzes untersucht. Dazu wird ein vollständiges dreidimensionales Strömungsmodell eines asymmetrischen Zwillingsstromturboladers aufgebaut, beginnend bei den Abgaskrümmern über die Turbinen- und Verdichtergehäuse inklusive der kompletten Laufräder bis hin zum Vorkatalysator. Die Eintrittsrandbedingungen für die Abgaskrümmer bestehend aus zeitabhängigem Massenfluss und Temperatur für zwei Motorbetriebspunkte bei hoher und niedriger Drehzahl werden von einem eindimensionalen Strömungsmodell des gesamten Motors generiert. Die Turbinen- und Verdichterseite des Modells sind durch ein Momentengleichgewicht gekoppelt und die aktuelle Turboladerdrehzahl wird für jeden Zeitschritt berechnet. Aus diesem Grund werden für die Analyse des Turboladers weder Turbinen- noch Verdichterkennfelder benötigt. Um die Rotation der Laufräder zu modellieren, wird ein Ansatz mit explizit bewegten Gittern verwendet und die Laufradgitter werden vor jedem Zeitschritt mittels eines Gitterinterfaces an die stationären Gehäuse gekoppelt. Als Ergebnisse des Modells werden verschiedene zeitaufgelöste physikalische Größen sowie Wellenleistung und Laderdrehzahl ausgewiesen. Auf Grund der pulsierenden Druckrandbedingung ist es ebenfalls möglich, die instationären Effekte wie Befüllen und Entleeren der Turbine zu untersuchen. Darüberhinaus ist das Modell dieser Forschungsarbeit in der Lage sowohl den instationären Wirkungsgrad unter Druckpulsationen als auch die Überströmverluste, welche durch die unterschiedlichen Druckniveaus der Fluten bei pulsierender Beaufschlagung entstehen, zu analysieren. Um diese Verluste zu quantifizieren, werden neue Kennzahlen eingeführt. Auf Basis der asymmetrischen Zwillingsstromturbine wird eine Doppelstromturbine und eine symmetrische Zwillingsstromturbine mit dem selben Volumen konstruiert. Es werden identische Randbedingungen und die gleichen Laufräder für die Analyse der beiden neuen Varianten verwendet. Diese Turbinenlayouts werden mit dem Ausgangsmodell bezüglich Laderdrehzahl, Wellenleistung und instationärem Wirkungsgrad verglichen. Mit Hilfe neu eingeführter Kennzahlen ist ein Vergleich der Überströmverluste innerhalb der Turbine und des daraus folgenden Rückströmens in den Abgaskrümmer möglich. Das Rückströmen führt zu einem erhöhten Abgasgegendruck und beeinflusst den Ladungswechsel des Zylinders.Item Open Access Miscibility, viscoelastic reinforcement, and transport properties of blend membranes based on sulfonated poly(phenylene sulfone)s(2021) Saatkamp, Torben; Maier, Joachim (Prof. Dr.)Chemical energy that hydrogen may generate during combustion and the corresponding electrical energy are interconvertible by means of a fuel cell (FC) and by the electrolysis of water (WE), which allows for the utilization of the complementary nature of these two key energy vectors towards energy sustainability. A proton exchange membrane (PEM) made from an ionomer is commonly employed as the electrolyte in mobile fuel cell applications and in water electrolyzers that require dynamic operability and pressurized product gases. New PEM materials are needed to increase performance, reduce environmental impact, and allow for a more targeted design of PEMFC and PEMWE systems, all of which is in some way limited by the use of the established perfluorosulfonic acid (PFSA) type ionomers. This work’s focus lies on sulfonated poly(phenylene sulfone)s (sPPS), a unique group of fluorine-free cation conducting ionomers. They are unique in terms of their chemical stability and transport properties, however, typical in terms of their salt-like brittleness in the dry state and extensive swelling at high humidity and in water. To make the unique properties of sPPS available in application, the goal of this work is to take a comprehensive approach to their viscoelastic reinforcement. Therefore, the structure of this thesis entails three related aspects along the process from pure materials to the optimization of robust PEMs for application. The first chapter focuses on the optimization of the intrinsic viscoelastic properties of a particularly suited sPPS (termed S360, with IEC 2.78 meq g-1, EW 360 g mol-1) which lays the groundwork for reliable and systematic further development. To achieve this, relevant properties of S360 are first characterized and viscoelastic shortcomings as seen in water uptake measurements and tensile tests under dry conditions (≤ 30% relative humidity, RH) discussed. The step-growth polymerization of S360 is optimized after finding significant inorganic contamination retained in the established purification process of the widely used monomer sulfonated difluorodiphenyl sulfone (sDFDPS), allowing for the preparation of the ionomer in reproducible high molecular weight. Relevant properties of high molecular weight S360 are characterized and an enhancement of mechanical properties at 30% RH as well as when submerged in water is found. Access to reproducible high quality of S360 enables its first-time use and study as a PEM in a completely fluorine-free WE cell. At 80 °C, record performance amongst fluorine free electrolytes in PEMWEs of 3.48 A cm-2 at 1.8 V is achieved, showcasing the potential of sPPS for application. The second chapter entails the identification and better understanding of a suitable and versatile reinforcement concept for creating robust membranes based on sPPS. To achieve this, the established homogeneously miscible acid-base polymer blends of sulfonated ionomers with poly(benzimidazole) (PBI, and its derivatives PBIO and PBIOO) are discussed in-depth and chosen for later systematic optimization in combination with sPPS. Since the origin of miscibility in PBI blends with sulfonated ionomers is insufficiently described in literature and could facilitate targeted design of new blend components, a model acid-base polymer blend system comprising pyridine-functionalized poly(sulfone) (PSU) is created. Pyridine groups of different basicity tethered to PSU in varying concentration are used to investigate the effect that interpolymer acid-base interaction strength and concentration have on miscibility in blends with 80 wt% S360, as derived from the blend membranes’ cross-sectional SEMs. High mutual compatibility is achieved at high concentration of weak interpolymer interaction, which is interpreted with regards to the observed miscibility in PBI blends. Based on the derived role that hydrogen bonds may play in PBI blends, the difference of interpolymer interaction in solution (during membrane formation) and in the dry membrane is described. This could enable the development of new blend concepts in the future. An exemplary miscible blend that comprises interpolymer hydrogen bonds only in solution but not in the final membrane is shown. The third chapter describes the optimization and balance of properties in the previously described polymer blends with PBIO, following the goal to prepare membranes which can be evaluated in fuel cells and fabricated on a wider scale in order to bring the attractive properties of sPPS into application. To achieve this, S360-blend membranes of varying PBIO content are characterized with regard to conductivity and mechanical properties in various conditions. High mechanical robustness is achieved in S360 blends with 30 wt% PBIO but is accompanied by dramatic reduction of conductivity, due to the charge-consuming acid-base interaction. The findings are translated into blends with fully sulfonated sPPS (termed S220, with IEC 4.54 meq g-1, EW 220 g mol-1) which allows for the creation of membranes that combine mechanical toughness with high conductivity at a ratio of 25 wt% PBIO in S220, making the material suited for production on a commercial casting line and fuel cell testing. Membranes based on S360 that comprise 15 wt% PBIO are designated for further studies in PEMWEs, where membrane requirements differ significantly from that in PEMFCs, highlighting the versatility of the reinforcement approach chosen in this work. Finally, first fuel cell tests of thin spray coated PBIO blend membranes are conducted, and initial durability testing of sPPS-based membranes in fuel cells is possible. Overall, the results presented in this work are strongly interrelated which underlines the importance of comprehensiveness in the successful viscoelastic reinforcement of sulfonated poly(phenylene sulfone)s. Ultimately, the blend membranes resulting from this work can be used as a platform for further development of sPPS-based PEMs in the future.Item Open Access Housing adjustment to handle natural hazards : proactive urban development planning for an effective response to natural hazards and to "build back better" in recovery, rehabilitation, and reconstruction - on the case of Banda Aceh, Indonesia(2021) Lucas, Sabrina; Schönwandt, Walter L. (Prof. Dr.-Ing. Dipl.-Ing. Dipl.-Psych.)Natural hazards, including climatological, meteorological, hydrological, and geophysical hazards can have a devastating impact on human life, the built environment, urban development, and economy. A lack of money and resources, inadequate planning laws and regulations as well as a lack of effective monitoring strategies, are reasons why people in developing countries are particularly vulnerable to the impact of natural hazards. In many cases, there is a lack of information and knowledge about what can be done to appropriately adjust housing, comprising the immediate physical environment, both within and outside of buildings where people live, and which serve as a shelter from external influences. The present thesis investigates the need for pre-disaster housing adjustment strategies as a necessary contribution of urban development planning at a local level. This was achieved through systematic interviews and field studies in the post disaster study area Banda Aceh, Indonesia. Two instruments for pre-disaster planning are introduced: ‘Proactive urban development planning as pre-disaster protection’, a systematic risk management approach, before a disaster strikes as part of the everyday planning process; and a ‘reconstruction template’ to prepare for the worst-case scenario. With these two instruments, not only the quality of reconstruction projects can be improved but, in long-term urban development planning, housing can be adjusted to natural hazards. This approach is based on the UNISDR (United Nations International Strategy for Disaster Risk Reduction) Sendai framework for Disaster Risk Reduction 2015-2030 and forms a bridge between post-disaster reconstruction and long-lasting urban development.Item Open Access Data-driven modelling of neuromechanical adaptation in skeletal muscles in response to isometric exercise(Stuttgart : Institute for Modelling and Simulation of Biomechanical Systems, Chair of Continuum Biomechanics and Mechanobiology, University of Stuttgart, 2022) Altan, Neriman Ekin; Röhrle, Oliver (Prof., PhD)This study aims to model the changes in the behaviour of motor neurons of the vastus lateralis in response to unilateral isometric knee extension exercise (UIKEE). For this, the phenomenological motor control model by Fuglevand et al. (1993) has been used. Input parameters for this model have been calibrated against data from experimental studies available in literature by using Bayesian updating. The pre-exercise state of the motor neuron pool of the muscle describing the recruitment behaviour as well as the contractile properties of the motor neurons have been constructed. Data collected from a systematic review on the change in isometric strength due to UIKEE has been modelled using Bayesian lonigutidinal model-based meta-analysis. Using the model of the change in isometric strength, increase in the average motor neuron discharge rate following UIKEE has been quantified.Item Open Access Technologieakzeptanz von virtuellen Lern- und Arbeitsumgebungen(2021) Pletz, Carolin; Zinn, Bernd (Prof. Dr.)Mit dem Einsatz innovativer Technologien in Lern- und Arbeitsprozessen werden vor dem Hintergrund der Digitalisierung und Industrie 4.0 multiple Potenziale verbunden. Insbesondere immersive virtuelle Lern- und Arbeitsumgebungen (Virtual Reality, kurz IVR) bieten vielversprechende Möglichkeiten, um das Lernen und Arbeiten gewinnbringend zu unterstützen. Unter IVR werden computergenerierte Darstellungen verstanden, welche dreidimensional und interaktiv sind. Die Nutzenden können über natürliche Benutzerschnittstellen regelrecht in die virtuelle Umgebung „eintauchen“. Der in der Arbeit bilanzierte Forschungsstand zeigt, dass zu Beginn der Forschungsbemühungen allerdings nur wenig über die Technologieakzeptanz von IVR und den entsprechenden fördernden und hemmenden Faktoren bekannt ist. Unter der Technologieakzeptanz wird die „positive Annahmeentscheidung einer Innovation durch die [Anwenderinnen und] Anwender“ (Simon, 2001, S. 89) verstanden. In Anbetracht dieser Forschungslücke besteht das zentrale Forschungsvorhaben der vorliegenden Arbeit deshalb in der Generierung eines Beschreibungs- und Erklärungswissens zur Technologieakzeptanz von IVR bei (potenziellen) Nutzerinnen und Nutzern. Ein theoretischer Rahmen zur Digitalisierung der Arbeitswelt, zu Virtual Reality Technologien und zur Technologieakzeptanz sowie eine Übersicht über den entsprechenden empirischen Forschungsstand führen in die Thematik ein. Die Arbeit umfasst vier empirische Studien zur Untersuchung der Technologieakzeptanz von IVR. In der ersten Studie werden die theoretischen Annahmen des Technology Acceptance Models (TAM) in Bezug auf die Technologieakzeptanz von IVR empirisch geprüft. Das TAM geht davon aus, dass die Nutzungsintention von Informationstechnologien hauptsächlich von der wahrgenommenen Nützlichkeit und Benutzerfreundlichkeit beeinflusst wird. Studie 1 untersucht in diesem Zusammenhang die Technologieakzeptanz und die nutzerbezogenen Faktoren Alter und Vorerfahrung mit der Technologie im Rahmen einer quantitativen Fragebogenerhebung mit (potenziellen) Nutzerinnen und Nutzern von IVR. Die zweite Studie fokussiert die Technologieakzeptanz eines virtuellen Verkaufsraums und bezieht neben den Kernfaktoren des TAM die soziale Norm, wahrgenommene Verhaltenskontrolle sowie die organisationsbezogenen Faktoren Unterstützung durch die Führung, Anwendertraining und Anwendersupport in die Betrachtung ein. Die Datenerhebung erfolgt ebenfalls mittels eines quantitativen Fragebogens. In der dritten Studie wird eine virtuelle Lernanwendung für Bedienerschulungen formativ im Hinblick auf die Technologieakzeptanz, User Experience und den Lerntransfer von virtuell gelerntem Handlungswissen auf reale Tätigkeiten mittels einer qualitativen Videoanalyse evaluiert. Die vierte Studie zielt auf die Identifikation von weiteren nutzerbezogenen, organisationsbezogenen und insbesondere technologiespezifischen fördernden und hemmenden Faktoren im Rahmen einer qualitativen Interviewstudie mit Experten ab. Die Ergebnisse zeigen, dass das TAM auch als geeignete Grundlage zur Untersuchung der Technologieakzeptanz von IVR herangezogen werden kann und die wahrgenommene Nützlichkeit sowie Benutzerfreundlichkeit einen Einfluss auf die Nutzungsintention haben (Studie 1). Ebenso beeinflusst die wahrgenommene Verhaltenskontrolle die Nutzungsintention und die organisationalen Faktoren hängen positiv mit den TAM-Faktoren zusammen (Studie 2). Es wird verdeutlicht, dass mit der Untersuchung innovativer Technologien auch neuartige methodische Zugänge in Forschungsbemühungen einhergehen müssen (Studie 3). Weitere nutzerbezogene, organisationsbezogene und technologiespezifische Einflussfaktoren auf die Technologieakzeptanz werden für den Einsatz von IVR in Lehr-Lernkontexten identifiziert (Studie 4). Zusammenfassend lassen sich auf der Basis der eigenen Forschungsergebnisse und unter Berücksichtigung der Limitationen praxisrelevante Ansatzpunkte zur Steigerung der Technologieakzeptanz von IVR ableiten.Item Open Access Entwicklung eines Modells zur Ermittlung psychischer Beanspruchung am Beispiel von Reisenden bei geschäftlich bedingten Hotelaufenthalten(Stuttgart : Fraunhofer Verlag, 2018) Borkmann, Vanessa; Spath, Dieter (Univ. Prof. Dr.-Ing. Dr.-Ing. E.h. Dr. h.c.)Die wissenschaftliche Arbeit untersucht belastende und erholungsförderliche Einflussfaktoren und deren Wirkungen während des Hotelaufenthalts auf die psychische Beanspruchung des geschäftlich Reisenden. Die arbeitswissenschaftliche Untersuchung stützt sich dabei auf einen multidisziplinären Forschungsansatz, der komplexe Zusammenhänge und selektierte Erkenntnisse über die klassischen Grenzen hinweg inhaltlich verknüpft.Item Open Access On the information transfer between imagery, point clouds, and meshes for multi-modal semantics utilizing geospatial data(2022) Laupheimer, Dominik; Haala, Norbert (apl. Prof. Dr.-Ing.)The semantic segmentation of the huge amount of acquired 3D data has become an important task in recent years. Images and Point Clouds (PCs) are fundamental data representations, particularly in urban mapping applications. Textured meshes integrate both representations by wiring the PC and texturing the reconstructed surface elements with high-resolution imagery. Meshes are adaptive to the underlying mapped geometry due to their graph structure composed of non-uniform and non-regular entities. Hence, the mesh is a memory-efficient realistic-looking 3D map of the real world. For these reasons, we primarily opt for semantic segmentation of meshes, which is a widely overlooked topic in photogrammetry and remote sensing yet. In particular, we head for multi-modal semantics utilizing supervised learning. However, publicly available annotated geospatial mesh data has been rare at the beginning of the thesis. Therefore, annotating mesh data has to be done beforehand. To kill two birds with one stone, we aim for a multi-modal fusion that enables multi-modal enhancement of entity descriptors and semi-automatic data annotation leveraging publicly available annotations of non-mesh data. We propose a novel holistic geometry-driven association mechanism that explicitly integrates entities of modalities imagery, PC, and mesh. The established entity relationships between pixels, points, and faces enable the sharing of information across the modalities in a two-fold manner: (i) feature transfer (measured or engineered) and (ii) label transfer (predicted or annotated). The implementation follows a tile-wise strategy to facilitate scalability to large-scale data sets. At the same time, it enables parallel, distributed processing, reducing processing time. We demonstrate the effectiveness of the proposed method on the International Society for Photogrammetry and Remote Sensing (ISPRS) benchmark data sets Vaihingen 3D and Hessigheim 3D. Taken together, the proposed entity linking and subsequent information transfer inject great flexibility into the semantic segmentation of geospatial data. Imagery, PCs, and meshes can be semantically segmented with classifiers trained on any of these modalities utilizing features derived from any of these modalities. Particularly, we can semantically segment a modality by training a classifier on the same modality (direct approach) or by transferring predictions from other modalities (indirect approach). Hence, any established well-performing modality-specific classifier can be used for semantic segmentation of these modalities - regardless of whether they follow an end-to-end learning or feature-driven scheme. We perform an extensive ablation study on the impact of multi-modal handcrafted features for automatic 3D scene interpretation - both for the direct and indirect approach. We discuss and analyze various Ground Truth (GT) generation methods. The semi-automatic labeling leveraging the entity linking achieves consistent annotation across modalities and reduces the manual label effort to a single representation. Please note that the multiple epochs of the Hessigheim data consisting of manually annotated PCs and semi-automatically annotated meshes are a result of this thesis and provided to the community as part of the Hessigheim 3D benchmark. To further reduce the labeling effort to a few instances on a single modality, we combine the proposed information transfer with active learning. We recruit non-experts for the tedious labeling task and analyze their annotation quality. Subsequently, we compare the resulting classifier performances to conventional passive learning using expert annotation. In particular, we investigate the impact of visualizing the mesh instead of the PC on the annotation quality achieved by non-experts. In summary, we accentuate the mesh and its utility for multi-modal fusion, GT generation, multi-modal semantics, and visualizational purposes.