@phdthesis{Azari,
  author    = {Azari, Banafsheh},
  title     = {Bidirectional Texture Functions: Acquisition, Rendering and Quality Evaluation},
  doi       = {10.25643/bauhaus-universitaet.3779},
  url       = {http://nbn-resolving.de/urn:nbn:de:gbv:wim2-20180820-37790},
  school      = {Bauhaus-Universit{\"a}t Weimar},
  abstract  = {As one of its primary objectives, Computer Graphics aims at the simulation of fabrics' complex reflection behaviour. Characteristic surface reflectance of fabrics, such as highlights, anisotropy or retro-reflection arise the difficulty of synthesizing. This problem can be solved by using Bidirectional Texture Functions (BTFs), a 2D-texture under various light and view direction. But the acquisition of Bidirectional Texture Functions requires an expensive setup and the measurement process is very time-consuming. Moreover, the size of BTF data can range from hundreds of megabytes to several gigabytes, as a large number of high resolution pictures have to be used in any ideal cases. Furthermore, the three-dimensional textured models rendered through BTF rendering method are subject to various types of distortion during acquisition, synthesis, compression, and processing. An appropriate image quality assessment scheme is a useful tool for evaluating image processing algorithms, especially algorithms designed to leave the image visually unchanged. In this contribution, we present and conduct an investigation aimed at locating a robust threshold for downsampling BTF images without loosing perceptual quality. To this end, an experimental study on how decreasing the texture resolution influences perceived quality of the rendered images has been presented and discussed. Next, two basic improvements to the use of BTFs for rendering are presented: firstly, the study addresses the cost of BTF acquisition by introducing a flexible low-cost step motor setup for BTF acquisition allowing to generate a high quality BTF database taken at user-defined arbitrary angles. Secondly, the number of acquired textures to the perceptual quality of renderings is adapted so that the database size is not overloaded and can fit better in memory when rendered. Although visual attention is one of the essential attributes of HVS, it is neglected in most existing quality metrics. In this thesis an appropriate objective quality metric based on extracting visual attention regions from images and adequate investigation of the influence of visual attention on perceived image quality assessment, called Visual Attention Based Image Quality Metric (VABIQM), has been proposed. The novel metric indicates that considering visual saliency can offer significant benefits with regard to constructing objective quality metrics to predict the visible quality differences in images rendered by compressed and non-compressed BTFs and also outperforms straightforward existing image quality metrics at detecting perceivable differences.},
  subject      = {Wahrnehmung},
  language  = {en}
}
@phdthesis{Gerold,
  author    = {Gerold, Fabian},
  title     = {Konzepte zur interaktiven Entwurfsraum-Exploration im Tragwerksentwurf},
  doi       = {10.25643/bauhaus-universitaet.2153},
  url       = {http://nbn-resolving.de/urn:nbn:de:gbv:wim2-20140408-21532},
  school      = {Bauhaus-Universit{\"a}t Weimar},
  pages     = {101},
  abstract  = {Der Entwurfsraum f{\"u}r den Entwurf eines Tragwerks ist ein n-dimensionaler Raum, der aus allen freien Parametern des Modells aufgespannt wird. Traditionell werden nur wenige Punkte dieses Raumes durch eine numerische (computergest{\"u}tzte) Simulation evaluiert, meist auf Basis der Finite-Elemente-Methode. Mehrere Faktoren f{\"u}hren dazu, dass heute oft viele Revisionen eines Simulationsmodells durchlaufen werden: Zum einen ergeben sich oft Planungs{\"a}nderungen, zum anderen ist oft die Untersuchung von Planungsalternativen und die Suche nach einem Optimum w{\"u}nschenswert. In dieser Arbeit soll f{\"u}r ein vorhandenes Finite-Elemente-Framework die sequentielle Datei-Eingabeschnittstelle durch eine Netzwerkschnittstelle ersetzt werden, die den Erfordernissen einer interaktiven Arbeitsweise entspricht. So erlaubt die hier konzipierte Schnittstelle interaktive, inkrementelle Modell{\"a}nderungen sowie Status- und Berechnungsergebnis-Abfragen durch eine bidirektionale Schnittstelle. Die Kombination aus interaktiver numerischer Simulation und Interoperabilit{\"a}t durch die Anwendung von Konzepten zur Bauwerks-Informations-Modellierung im Tragwerksentwurf ist Ziel dieser Dissertation. Die Beschreibung der Konzeption und prototypischen Umsetzung ist Gegenstand der schriftlichen Arbeit.},
  subject      = {Interaktive numerische Simulation},
  language  = {de}
}
@phdthesis{Dang,
  author    = {Dang, Trang},
  title     = {Automated Detailing of 4D Schedules},
  doi       = {10.25643/bauhaus-universitaet.2310},
  url       = {http://nbn-resolving.de/urn:nbn:de:gbv:wim2-20141006-23103},
  school      = {Bauhaus-Universit{\"a}t Weimar},
  pages     = {120},
  abstract  = {The increasing success of BIM (Building Information Model) and the emergence of its implementation in 3D construction models have paved a way for improving scheduling process. The recent research on application of BIM in scheduling has focused on quantity take-off, duration estimation for individual trades, schedule visualization, and clash detection. Several experiments indicated that the lack of detailed planning causes about 30\% non-productive time and stacking of trades. However, detailed planning still has not been implemented in practice despite receiving a lot of interest from researchers. The reason is associated with the huge amount and complexity of input data. In order to create a detailed planning, it is time consuming to manually decompose activities, collect and calculate the detailed information in relevant. Moreover, the coordination of detailed activities requires much effort for dealing with their complex constraints. This dissertation aims to support the generation of detailed schedules from a rough schedule. It proposes a model for automated detailing of 4D schedules by integrating BIM, simulation and Pareto-based optimization.},
  subject      = {Simulation},
  language  = {en}
}
@phdthesis{Schrader,
  author    = {Schrader, Kai},
  title     = {Hybrid 3D simulation methods for the damage analysis of multiphase composites},
  doi       = {10.25643/bauhaus-universitaet.2059},
  url       = {http://nbn-resolving.de/urn:nbn:de:gbv:wim2-20131021-20595},
  school      = {Bauhaus-Universit{\"a}t Weimar},
  pages     = {174},
  abstract  = {Modern digital material approaches for the visualization and simulation of heterogeneous materials allow to investigate the behavior of complex multiphase materials with their physical nonlinear material response at various scales. However, these computational techniques require extensive hardware resources with respect to computing power and main memory to solve numerically large-scale discretized models in 3D. Due to a very high number of degrees of freedom, which may rapidly be increased to the two-digit million range, the limited hardware ressources are to be utilized in a most efficient way to enable an execution of the numerical algorithms in minimal computation time. Hence, in the field of computational mechanics, various methods and algorithms can lead to an optimized runtime behavior of nonlinear simulation models, where several approaches are proposed and investigated in this thesis. Today, the numerical simulation of damage effects in heterogeneous materials is performed by the adaption of multiscale methods. A consistent modeling in the three-dimensional space with an appropriate discretization resolution on each scale (based on a hierarchical or concurrent multiscale model), however, still contains computational challenges in respect to the convergence behavior, the scale transition or the solver performance of the weak coupled problems. The computational efficiency and the distribution among available hardware resources (often based on a parallel hardware architecture) can significantly be improved. In the past years, high-performance computing (HPC) and graphics processing unit (GPU) based computation techniques were established for the investigationof scientific objectives. Their application results in the modification of existing and the development of new computational methods for the numerical implementation, which enables to take advantage of massively clustered computer hardware resources. In the field of numerical simulation in material science, e.g. within the investigation of damage effects in multiphase composites, the suitability of such models is often restricted by the number of degrees of freedom (d.o.f.s) in the three-dimensional spatial discretization. This proves to be difficult for the type of implementation method used for the nonlinear simulation procedure and, simultaneously has a great influence on memory demand and computational time. In this thesis, a hybrid discretization technique has been developed for the three-dimensional discretization of a three-phase material, which is respecting the numerical efficiency of nonlinear (damage) simulations of these materials. The increase of the computational efficiency is enabled by the improved scalability of the numerical algorithms. Consequently, substructuring methods for partitioning the hybrid mesh were implemented, tested and adapted to the HPC computing framework using several hundred CPU (central processing units) nodes for building the finite element assembly. A memory-efficient iterative and parallelized equation solver combined with a special preconditioning technique for solving the underlying equation system was modified and adapted to enable combined CPU and GPU based computations. Hence, it is recommended by the author to apply the substructuring method for hybrid meshes, which respects different material phases and their mechanical behavior and which enables to split the structure in elastic and inelastic parts. However, the consideration of the nonlinear material behavior, specified for the corresponding phase, is limited to the inelastic domains only, and by that causes a decreased computing time for the nonlinear procedure. Due to the high numerical effort for such simulations, an alternative approach for the nonlinear finite element analysis, based on the sequential linear analysis, was implemented in respect to scalable HPC. The incremental-iterative procedure in finite element analysis (FEA) during the nonlinear step was then replaced by a sequence of linear FE analysis when damage in critical regions occured, known in literature as saw-tooth approach. As a result, qualitative (smeared) crack initiation in 3D multiphase specimens has efficiently been simulated.},
  subject      = {high-performance computing},
  language  = {en}
}
@phdthesis{CarvajalBermudez,
  author    = {Carvajal Berm{\´u}dez, Juan Carlos},
  title     = {New methods of citizen participation based on digital technologies},
  doi       = {10.25643/bauhaus-universitaet.4712},
  url       = {http://nbn-resolving.de/urn:nbn:de:gbv:wim2-20220906-47124},
  school      = {Bauhaus-Universit{\"a}t Weimar},
  abstract  = {The current thesis presents research about new methods of citizen participation based on digital technologies. The focus on the research lies on decentralized methods of participation where citizens take the role of co-creators. The research project first conducted a review of the literature on citizen participation, its origins and the different paradigms that have emerged over the years. The literature review also looked at the influence of technologies on participation processes and the theoretical frameworks that have emerged to understand the introduction of technologies in the context of urban development. The literature review generated the conceptual basis for the further development of the thesis. The research begins with a survey of technology enabled participation applications that examined the roles and structures emerging due to the introduction of technology. The results showed that cities use technology mostly to control and monitor urban infrastructure and are rather reluctant to give citizens the role of co-creators. Based on these findings, three case studies were developed. Digital tools for citizen participation were conceived and introduced for each case study. The adoption and reaction of the citizens were observed using three data collection methods. The results of the case studies showed consistently that previous participation and engagement with informal citizen participation are a determinining factor in the potential adoption of digital tools for decentralized engagement. Based on these results, the case studies proposed methods and frameworks that can be used for the conception and introduction of technologies for decentralized citizen participation.},
  subject      = {Partizipation},
  language  = {en}
}
@phdthesis{Vogler,
  author    = {Vogler, Verena},
  title     = {A framework for artificial coral reef design: Integrating computational modelling and high precision monitoring strategies for artificial coral reefs - an Ecosystem-aware design approach in times of climate change},
  isbn      = {978-3-00-074495-2},
  doi       = {10.25643/bauhaus-universitaet.4611},
  url       = {http://nbn-resolving.de/urn:nbn:de:gbv:wim2-20220322-46115},
  school      = {Bauhaus-Universit{\"a}t Weimar},
  pages     = {243},
  abstract  = {Tropical coral reefs, one of the world's oldest ecosystems which support some of the highest levels of biodiversity on the planet, are currently facing an unprecedented ecological crisis during this massive human-activity-induced period of extinction. Hence, tropical reefs symbolically stand for the destructive effects of human activities on nature [4], [5]. Artificial reefs are excellent examples of how architectural design can be combined with ecosystem regeneration [6], [7], [8]. However, to work at the interface between the artificial and the complex and temporal nature of natural systems presents a challenge, i.a. in respect to the B-rep modelling legacy of computational modelling. The presented doctorate investigates strategies on how to apply digital practice to realise what is an essential bulwark to retain reefs in impossibly challenging times. Beyond the main question of integrating computational modelling and high precision monitoring strategies in artificial coral reef design, this doctorate explores techniques, methods, and linking frameworks to support future research and practice in ecology led design contexts. Considering the many existing approaches for artificial coral reefs design, one finds they often fall short in precisely understanding the relationships between architectural and ecological aspects (e.g. how a surface design and material composition can foster coral larvae settlement, or structural three-dimensionality enhance biodiversity) and lack an integrated underwater (UW) monitoring process. Such a process is necessary in order to gather knowledge about the ecosystem and make it available for design, and to learn whether artificial structures contribute to reef regeneration or rather harm the coral reef ecosystem. For the research, empirical experimental methods were applied: Algorithmic coral reef design, high precision UW monitoring, computational modelling and simulation, and validated through parallel real-world physical experimentation - two Artificial Reef Prototypes (ARPs) in Gili Trawangan, Indonesia (2012-today). Multiple discrete methods and sub techniques were developed in seventeen computational experiments and applied in a way in which many are cross valid and integrated in an overall framework that is offered as a significant contribution to the field. Other main contributions include the Ecosystem-aware design approach, Key Performance Indicators (KPIs) for coral reef design, algorithmic design and fabrication of Biorock cathodes, new high precision UW monitoring strategies, long-term real-world constructed experiments, new digital analysis methods and two new front-end web-based tools for reef design and monitoring reefs. The methodological framework is a finding of the research that has many technical components that were tested and combined in this way for the very first time. In summary, the thesis responds to the urgency and relevance in preserving marine species in tropical reefs during this massive extinction period by offering a differentiated approach towards artificial coral reefs - demonstrating the feasibility of digitally designing such 'living architecture' according to multiple context and performance parameters. It also provides an in-depth critical discussion of computational design and architecture in the context of ecosystem regeneration and Planetary Thinking. In that respect, the thesis functions as both theoretical and practical background for computational design, ecology and marine conservation - not only to foster the design of artificial coral reefs technically but also to provide essential criteria and techniques for conceiving them. Keywords: Artificial coral reefs, computational modelling, high precision underwater monitoring, ecology in design.},
  subject      = {Korallenriff},
  language  = {en}
}
@phdthesis{Walsdorf,
  author    = {Walsdorf, Joern},
  title     = {M-Learning: Lernen im mobilen Kontext an Hochschulen},
  doi       = {10.25643/bauhaus-universitaet.2136},
  url       = {http://nbn-resolving.de/urn:nbn:de:gbv:wim2-20140304-21361},
  school      = {Bauhaus-Universit{\"a}t Weimar},
  abstract  = {A fundamental characteristic of human beings is the desire to start learning at the moment of birth. The rather formal learning process that learners have to deal with in school, on vocational training or in university, is currently subject to fundamental changes. The increasing technologization, overall existing mobile devices, the ubiquitous access to digital information, and students being early adaptors of all these technological innovations require reactions on the part of the educational system. This study examines such a reaction: The use of mobile learning in higher education. Examining the subject m-learning first requires an investigation of the educational model e-learning. Many universities already established e-learning as one of their educational segments, providing a wide range of methods to support this kind of teaching. This study includes an empirical acceptance analysis regarding the general learning behavior of students and their approval of e-learning methods. A survey on the approval of m-learning supplements the results. Mobile learning is characterized by both the mobility of the communication devices and the users. Both factors lead to new correlations, demonstrate the potential of today's mobile devices and the probability to increase the learning performance. The dissertation addresses these correlations and the use of mobile devices in the context of m-learning. M-learning and the usage of mobile devices not only require a reflection from a technological point of view. In addition to the technical features of such mobile devices, the usability of their applications plays an important role, especially with regard to the limited display size. For the purpose of evaluating mobile apps and browser-based applications, various analytical methods are suitable. The concluding heuristic evaluation points out the vulnerability of an established m-learning application, reveals the need for improvement, and shows an approach to rectify the shortcoming.},
  subject      = {Mobile Learning},
  language  = {de}
}
@phdthesis{Kulik,
  author    = {Kulik, Alexander},
  title     = {User Interfaces for Cooperation},
  doi       = {10.25643/bauhaus-universitaet.2720},
  url       = {http://nbn-resolving.de/urn:nbn:de:gbv:wim2-20161202-27207},
  school      = {Bauhaus-Universit{\"a}t Weimar},
  pages     = {261},
  abstract  = {This thesis suggests cooperation as a design paradigm for human-computer interaction. The basic idea is that the synergistic co-operation of interfaces through concurrent user activities enables increased interaction fluency and expressiveness. This applies to bimanual interaction and multi-finger input, e.g., touch typing, as well as the collaboration of multiple users. Cooperative user interfaces offer more interaction flexibility and expressivity for single and multiple users. Part I of this thesis analyzes the state of the art in user interface design. It explores limitations of common approaches and reveals the crucial role of cooperative action in several established user interfaces and research prototypes. A review of related research in psychology and human-computer interaction offers insights to the cognitive, behavioral, and ergonomic foundations of cooperative user interfaces. Moreover, this thesis suggests a broad applicability of generic cooperation patterns and contributes three high-level design principles. Part II presents three experiments towards cooperative user interfaces in detail. A study on desktop-based 3D input devices, explores fundamental benefits of cooperative bimanual input and the impact of interface design on bimanual cooperative behavior. A novel interaction technique for multitouch devices is presented that follows the paradigm of cooperative user interfaces and demonstrates advantages over the status quo. Finally, this thesis introduces a fundamentally new display technology that provides up to six users with their individual perspectives of a shared 3D environment. The system creates new possibilities for the cooperative interaction of multiple users. Part III of this thesis builds on the research results described in Part II, in particular, the multi-user 3D display system. A series of case studies in the field of collaborative virtual reality provides exemplary evidence for the relevance and applicability of the suggested design principles.},
  subject      = {Human-Computer Interaction (HCI)},
  language  = {en}
}
@phdthesis{Moehring,
  author    = {Moehring, Mathias},
  title     = {Realistic Interaction with Virtual Objects within Arm's Reach},
  doi       = {10.25643/bauhaus-universitaet.1859},
  url       = {http://nbn-resolving.de/urn:nbn:de:gbv:wim2-20130301-18592},
  school      = {Bauhaus-Universit{\"a}t Weimar},
  pages     = {124},
  abstract  = {The automotive industry requires realistic virtual reality applications more than other domains to increase the efficiency of product development. Currently, the visual quality of virtual invironments resembles reality, but interaction within these environments is usually far from what is known in everyday life. Several realistic research approaches exist, however they are still not all-encompassing enough to be usable in industrial processes. This thesis realizes lifelike direct multi-hand and multi-finger interaction with arbitrary objects, and proposes algorithmic and technical improvements that also approach lifelike usability. In addition, the thesis proposes methods to measure the effectiveness and usability of such interaction techniques as well as discusses different types of grasping feedback that support the user during interaction. Realistic and reliable interaction is reached through the combination of robust grasping heuristics and plausible pseudophysical object reactions. The easy-to-compute grasping rules use the objects' surface normals, and mimic human grasping behavior. The novel concept of Normal Proxies increases grasping stability and diminishes challenges induced by adverse normals. The intricate act of picking-up thin and tiny objects remains challenging for some users. These cases are further supported by the consideration of finger pinches, which are measured with a specialized finger tracking device. With regard to typical object constraints, realistic object motion is geometrically calculated as a plausible reaction on user input. The resulting direct finger-based interaction technique enables realistic and intuitive manipulation of arbitrary objects. The thesis proposes two methods that prove and compare effectiveness and usability. An expert review indicates that experienced users quickly familiarize themselves with the technique. A quantitative and qualitative user study shows that direct finger-based interaction is preferred over indirect interaction in the context of functional car assessments. While controller-based interaction is more robust, the direct finger-based interaction provides greater realism, and becomes nearly as reliable when the pinch-sensitive mechanism is used. At present, the haptic channel is not used in industrial virtual reality applications. That is why it can be used for grasping feedback which improves the users' understanding of the grasping situation. This thesis realizes a novel pressure-based tactile feedback at the fingertips. As an alternative, vibro-tactile feedback at the same location is realized as well as visual feedback by the coloring of grasp-involved finger segments. The feedback approaches are also compared within the user study, which reveals that grasping feedback is a requirement to judge grasp status and that tactile feedback improves interaction independent of the used display system. The considerably stronger vibrational tactile feedback can quickly become annoying during interaction. The interaction improvements and hardware enhancements make it possible to interact with virtual objects in a realistic and reliable manner. By addressing realism and reliability, this thesis paves the way for the virtual evaluation of human-object interaction, which is necessary for a broader application of virtual environments in the automotive industry and other domains.},
  subject      = {Virtuelle Realit{\"a}t},
  language  = {en}
}
@phdthesis{Lux,
  author    = {Lux, Christopher},
  title     = {A Data-Virtualization System for Large Model Visualization},
  doi       = {10.25643/bauhaus-universitaet.1985},
  url       = {http://nbn-resolving.de/urn:nbn:de:gbv:wim2-20130725-19855},
  school      = {Bauhaus-Universit{\"a}t Weimar},
  pages     = {211},
  abstract  = {Interactive scientific visualizations are widely used for the visual exploration and examination of physical data resulting from measurements or simulations. Driven by technical advancements of data acquisition and simulation technologies, especially in the geo-scientific domain, large amounts of highly detailed subsurface data are generated. The oil and gas industry is particularly pushing such developments as hydrocarbon reservoirs are increasingly difficult to discover and exploit. Suitable visualization techniques are vital for the discovery of the reservoirs as well as their development and production. However, the ever-growing scale and complexity of geo-scientific data sets result in an expanding disparity between the size of the data and the capabilities of current computer systems with regard to limited memory and computing resources. In this thesis we present a unified out-of-core data-virtualization system supporting geo-scientific data sets consisting of multiple large seismic volumes and height-field surfaces, wherein each data set may exceed the size of the graphics memory or possibly even the main memory. Current data sets fall within the range of hundreds of gigabytes up to terabytes in size. Through the mutual utilization of memory and bandwidth resources by multiple data sets, our data-management system is able to share and balance limited system resources among different data sets. We employ multi-resolution methods based on hierarchical octree and quadtree data structures to generate level-of-detail working sets of the data stored in main memory and graphics memory for rendering. The working set generation in our system is based on a common feedback mechanism with inherent support for translucent geometric and volumetric data sets. This feedback mechanism collects information about required levels of detail during the rendering process and is capable of directly resolving data visibility without the application of any costly occlusion culling approaches. A central goal of the proposed out-of-core data management system is an effective virtualization of large data sets. Through an abstraction of the level-of-detail working sets, our system allows developers to work with extremely large data sets independent of their complex internal data representations and physical memory layouts. Based on this out-of-core data virtualization infrastructure, we present distinct rendering approaches for specific visualization problems of large geo-scientific data sets. We demonstrate the application of our data virtualization system and show how multi-resolution data can be treated exactly the same way as regular data sets during the rendering process. An efficient volume ray casting system is presented for the rendering of multiple arbitrarily overlapping multi-resolution volume data sets. Binary space-partitioning volume decomposition of the bounding boxes of the cube-shaped volumes is used to identify the overlapping and non-overlapping volume regions in order to optimize the rendering process. We further propose a ray casting-based rendering system for the visualization of geological subsurface models consisting of multiple very detailed height fields. The rendering of an entire stack of height-field surfaces is accomplished in a single rendering pass using a two-level acceleration structure, which combines a minimum-maximum quadtree for empty-space skipping and sorted lists of depth intervals to restrict ray intersection searches to relevant height fields and depth ranges. Ultimately, we present a unified rendering system for the visualization of entire geological models consisting of highly detailed stacked horizon surfaces and massive volume data. We demonstrate a single-pass ray casting approach facilitating correct visual interaction between distinct translucent model components, while increasing the rendering efficiency by reducing processing overhead of potentially invisible parts of the model. The combination of image-order rendering approaches and the level-of-detail feedback mechanism used by our out-of-core data-management system inherently accounts for occlusions of different data types without the application of costly culling techniques. The unified out-of-core data-management and virtualization infrastructure considerably facilitates the implementation of complex visualization systems. We demonstrate its applicability for the visualization of large geo-scientific data sets using output-sensitive rendering techniques. As a result, the magnitude and multitude of data sets that can be interactively visualized is significantly increased compared to existing approaches.},
  subject      = {Computer Graphics},
  language  = {en}
}
@phdthesis{Fleischmann,
  author    = {Fleischmann, Ewan},
  title     = {Analysis and Design of Blockcipher Based Cryptographic Algorithms},
  doi       = {10.25643/bauhaus-universitaet.1983},
  url       = {http://nbn-resolving.de/urn:nbn:de:gbv:wim2-20130722-19835},
  school      = {Bauhaus-Universit{\"a}t Weimar},
  pages     = {272},
  abstract  = {This thesis focuses on the analysis and design of hash functions and authenticated encryption schemes that are blockcipher based. We give an introduction into these fields of research - taking in a blockcipher based point of view - with special emphasis on the topics of double length, double call blockcipher based compression functions. The first main topic (thesis parts I - III) is on analysis and design of hash functions. We start with a collision security analysis of some well known double length blockcipher based compression functions and hash functions: Abreast-DM, Tandem-DM and MDC-4. We also propose new double length compression functions that have elevated collision security guarantees. We complement the collision analysis with a preimage analysis by stating (near) optimal security results for Abreast-DM, Tandem-DM, and Hirose-DM. Also, some generalizations are discussed. These are the first preimage security results for blockcipher based double length hash functions that go beyond the birthday barrier. We then raise the abstraction level and analyze the notion of 'hash function indifferentiability from a random oracle'. So we not anymore focus on how to obtain a good compression function but, instead, on how to obtain a good hash function using (other) cryptographic primitives. In particular we give some examples when this strong notion of hash function security might give questionable advice for building a practical hash function. In the second main topic (thesis part IV), which is on authenticated encryption schemes, we present an on-line authenticated encryption scheme, McOEx, that simultaneously achieves privacy and confidentiality and is secure against nonce-misuse. It is the first dedicated scheme that achieves high standards of security and - at the same time - is on-line computable.},
  subject      = {Kryptologie},
  language  = {en}
}
@phdthesis{Gollub,
  author    = {Gollub, Tim},
  title     = {Information Retrieval for the Digital Humanities},
  doi       = {10.25643/bauhaus-universitaet.4673},
  url       = {http://nbn-resolving.de/urn:nbn:de:gbv:wim2-20220801-46738},
  school      = {Bauhaus-Universit{\"a}t Weimar},
  pages     = {177},
  abstract  = {In ten chapters, this thesis presents information retrieval technology which is tailored to the research activities that arise in the context of corpus-based digital humanities projects. The presentation is structured by a conceptual research process that is introduced in Chapter 1. The process distinguishes a set of five research activities: research question generation, corpus acquisition, research question modeling, corpus annotation, and result dissemination. Each of these research activities elicits different information retrieval tasks with special challenges, for which algorithmic approaches are presented after an introduction of the core information retrieval concepts in Chapter 2. A vital concept in many of the presented approaches is the keyquery paradigm introduced in Chapter 3, which represents an operation that returns relevant search queries in response to a given set of input documents. Keyqueries are proposed in Chapter 4 for the recommendation of related work, and in Chapter 5 for improving access to aspects hidden in the long tail of search result lists. With pseudo-descriptions, a document expansion approach is presented in Chapter 6. The approach improves the retrieval performance for corpora where only bibliographic meta-data is originally available. In Chapter 7, the keyquery paradigm is employed to generate dynamic taxonomies for corpora in an unsupervised fashion. Chapter 8 turns to the exploration of annotated corpora, and presents scoped facets as a conceptual extension to faceted search systems, which is particularly useful in exploratory search settings. For the purpose of highlighting the major topical differences in a sequence of sub-corpora, an algorithm called topical sequence profiling is presented in Chapter 9. The thesis concludes with two pilot studies regarding the visualization of (re)search results for the means of successful result dissemination: a metaphoric interpretation of the information nutrition label, as well as the philosophical bodies, which are 3D-printed search results.},
  subject      = {Information Retrieval},
  language  = {en}
}
@phdthesis{Anderka,
  author    = {Anderka, Maik},
  title     = {Analyzing and Predicting Quality Flaws in User-generated Content: The Case of Wikipedia},
  doi       = {10.25643/bauhaus-universitaet.1977},
  url       = {http://nbn-resolving.de/urn:nbn:de:gbv:wim2-20130709-19778},
  school      = {Bauhaus-Universit{\"a}t Weimar},
  abstract  = {Web applications that are based on user-generated content are often criticized for containing low-quality information; a popular example is the online encyclopedia Wikipedia. The major points of criticism pertain to the accuracy, neutrality, and reliability of information. The identification of low-quality information is an important task since for a huge number of people around the world it has become a habit to first visit Wikipedia in case of an information need. Existing research on quality assessment in Wikipedia either investigates only small samples of articles, or else deals with the classification of content into high-quality or low-quality. This thesis goes further, it targets the investigation of quality flaws, thus providing specific indications of the respects in which low-quality content needs improvement. The original contributions of this thesis, which relate to the fields of user-generated content analysis, data mining, and machine learning, can be summarized as follows: (1) We propose the investigation of quality flaws in Wikipedia based on user-defined cleanup tags. Cleanup tags are commonly used in the Wikipedia community to tag content that has some shortcomings. Our approach is based on the hypothesis that each cleanup tag defines a particular quality flaw. (2) We provide the first comprehensive breakdown of Wikipedia's quality flaw structure. We present a flaw organization schema, and we conduct an extensive exploratory data analysis which reveals (a) the flaws that actually exist, (b) the distribution of flaws in Wikipedia, and, (c) the extent of flawed content. (3) We present the first breakdown of Wikipedia's quality flaw evolution. We consider the entire history of the English Wikipedia from 2001 to 2012, which comprises more than 508 million page revisions, summing up to 7.9 TB. Our analysis reveals (a) how the incidence and the extent of flaws have evolved, and, (b) how the handling and the perception of flaws have changed over time. (4) We are the first who operationalize an algorithmic prediction of quality flaws in Wikipedia. We cast quality flaw prediction as a one-class classification problem, develop a tailored quality flaw model, and employ a dedicated one-class machine learning approach. A comprehensive evaluation based on human-labeled Wikipedia articles underlines the practical applicability of our approach.},
  subject      = {Data Mining},
  language  = {en}
}
@phdthesis{Forler,
  author    = {Forler, Christian},
  title     = {Analysis Design \& Applications of Cryptographic Building Blocks},
  publisher = {Shaker Verlag},
  doi       = {10.25643/bauhaus-universitaet.2376},
  url       = {http://nbn-resolving.de/urn:nbn:de:gbv:wim2-20150330-23764},
  school      = {Bauhaus-Universit{\"a}t Weimar},
  pages     = {213},
  abstract  = {This thesis deals with the basic design and rigorous analysis of cryptographic schemes and primitives, especially of authenticated encryption schemes, hash functions, and password-hashing schemes. In the last decade, security issues such as the PS3 jailbreak demonstrate that common security notions are rather restrictive, and it seems that they do not model the real world adequately. As a result, in the first part of this work, we introduce a less restrictive security model that is closer to reality. In this model it turned out that existing (on-line) authenticated encryption schemes cannot longer beconsidered secure, i.e. they can guarantee neither data privacy nor data integrity. Therefore, we present two novel authenticated encryption scheme, namely COFFE and McOE, which are not only secure in the standard model but also reasonably secure in our generalized security model, i.e. both preserve full data inegrity. In addition, McOE preserves a resonable level of data privacy. The second part of this thesis starts with proposing the hash function Twister-Pi, a revised version of the accepted SHA-3 candidate Twister. We not only fixed all known security issues of Twister, but also increased the overall soundness of our hash-function design. Furthermore, we present some fundamental groundwork in the area of password-hashing schemes. This research was mainly inspired by the medial omnipresence of password-leakage incidences. We show that the password-hashing scheme scrypt is vulnerable against cache-timing attacks due to the existence of a password-dependent memory-access pattern. Finally, we introduce Catena the first password-hashing scheme that is both memory-consuming and resistant against cache-timing attacks.},
  subject      = {Kryptologie},
  language  = {en}
}
@phdthesis{Schneider,
  author    = {Schneider, Sven},
  title     = {Sichtbarkeitsbasierte Raumerzeugung - Automatisierte Erzeugung r{\"a}umlicher Konfigurationen in Architektur und St{\"a}dtebau auf Basis sichtbarkeitsbasierter Raumrepr{\"a}sentationen},
  doi       = {10.25643/bauhaus-universitaet.2590},
  url       = {http://nbn-resolving.de/urn:nbn:de:gbv:wim2-20160613-25900},
  school      = {Bauhaus-Universit{\"a}t Weimar},
  pages     = {225},
  abstract  = {Das Erzeugen r{\"a}umlicher Konfigurationen ist eine zentrale Aufgabe im architektonischen bzw. st{\"a}dtebaulichen Entwurfsprozess und hat zum Ziel, eine f{\"u}r Menschen angenehme Umwelt zu schaffen. Der Geometrie der entstehenden R{\"a}ume kommt hierbei eine zentrale Rolle zu, da sie einen großen Einfluss auf das Empfinden und Verhalten der Menschen aus{\"u}bt und nur noch mit großem Aufwand ver{\"a}ndert werden kann, wenn sie einmal gebaut wurde. Die meisten Entscheidungen zur Festlegung der Geometrie von R{\"a}umen werden w{\"a}hrend eines sehr kurzen Zeitraums (Entwurfsphase) getroffen. Fehlentscheidungen die in dieser Phase getroffen werden haben langfristige Auswirkungen auf das Leben von Menschen, und damit auch Konsequenzen auf {\"o}konomische und {\"o}kologische Aspekte. Mittels computerbasierten Layoutsystemen l{\"a}sst sich der Entwurf r{\"a}umlicher Konfigurationen sinnvoll unterst{\"u}tzen, da sie es erm{\"o}glichen, in k{\"u}rzester Zeit eine große Anzahl an Varianten zu erzeugen und zu {\"u}berpr{\"u}fen. Daraus ergeben sich zwei Vorteile. Erstens kann die große Menge an Varianten dazu beitragen, bessere L{\"o}sungen zu finden. Zweitens kann das Formalisieren von Bewertungskriterien zu einer gr{\"o}ßeren Objektivit{\"a}t und Transparenz bei der L{\"o}sungsfindung f{\"u}hren. Um den Entwurf r{\"a}umlicher Konfigurationen optimal zu unterst{\"u}tzen, muss ein Layoutsystem in der Lage sein, ein m{\"o}glichst großes Spektrum an Grundrissvarianten zu erzeugen (Vielfalt); und zahlreiche M{\"o}glichkeiten und Detaillierungsstufen zur Problembeschreibung (Flexibilit{\"a}t), sowie Mittel anzubieten, mit denen sich die Anforderungen an die r{\"a}umliche Konfiguration ad{\"a}quat beschreiben lassen (Relevanz). Bez{\"u}glich Letzterem spielen wahrnehmungs- und nutzungsbezogene Kriterien (wie z. B. Grad an Privatheit, Gef{\"u}hl von Sicherheit, Raumwirkung, Orientierbarkeit, Potenzial zu sozialer Interaktion) eine wichtige Rolle. Die bislang entwickelten Layoutsysteme weisen hinsichtlich Vielfalt, Flexibilit{\"a}t und Relevanz wesentliche Beschr{\"a}nkungen auf, welche auf eine ungeeignete Methode zur Repr{\"a}sentation von R{\"a}umen zur{\"u}ckzuf{\"u}hren sind. Die in einem Layoutsystem verwendeten Raumrepr{\"a}sentationsmethoden bestimmen die M{\"o}glichkeiten zur Formerzeugung und Problembeschreibung wesentlich. Sichtbarkeitsbasierte Raumrepr{\"a}sentationen (Sichtfelder, Sichtachsen, Konvexe R{\"a}ume) eignen sich in besonderer Weise zur Abbildung von R{\"a}umen in Layoutsystemen, da sie einerseits ein umfangreiches Repertoire zur Verf{\"u}gung stellen, um r{\"a}umliche Konfigurationen hinsichtlich wahrnehmungs- und nutzungsbezogener Kriterien zu beschreiben. Andererseits lassen sie sich vollst{\"a}ndig aus der Geometrie der begrenzenden Oberfl{\"a}chen ableiten und sind nicht an bestimmte zur Formerzeugung verwendete geometrische Objekte gebunden. In der vorliegenden Arbeit wird ein Layoutsystem entwickelt, welches auf diesen Raumrepr{\"a}sentationen basiert. Es wird ein Evaluationsmechanismus (EM) entwickelt, welcher es erm{\"o}glicht, beliebige zweidimensionale r{\"a}umliche Konfigurationen hinsichtlich wahrnehmungs- und nutzungsrelevanter Kriterien zu bewerten. Hierzu wurde eine Methodik entwickelt, die es erm{\"o}glicht automatisch Raumbereiche (O-Spaces und P-Spaces) zu identifizieren, welche bestimmte Eigenschaften haben (z.B. sichtbare Fl{\"a}che, Kompaktheit des Sichtfeldes, Tageslicht) und bestimmte Relationen zueinander (wie gegenseitige Sichtbarkeit, visuelle und physische Distanz) aufweisen. Der EM wurde mit Generierungsmechanismen (GM) gekoppelt, um zu pr{\"u}fen, ob dieser sich eignet, um in großen Variantenr{\"a}umen nach geeigneten r{\"a}umlichen Konfigurationen zu suchen. Die Ergebnisse dieser Experimente zeigen, dass die entwickelte Methodik einen vielversprechenden Ansatz zur automatisierten Erzeugung von r{\"a}umlichen Konfigurationen darstellt: Erstens ist der EM vollst{\"a}ndig vom GM getrennt, wodurch es m{\"o}glich ist, verschiedene GM in einem Entwurfssystem zu verwenden und somit den Variantenraum zu vergr{\"o}ßern (Vielfalt). Zweitens erlaubt der EM die Anforderungen an eine r{\"a}umliche Konfiguration flexibel zu beschreiben (unterschiedliche Maßst{\"a}be, unterschiedlicher Detaillierungsgrad). Letztlich erlauben die verwendeten Repr{\"a}sentationsmethoden eine Problembeschreibung vorzunehmen, die stark an der Wirkung des Raumes auf den Menschen orientiert ist (Relevanz). Die in der Arbeit entwickelte Methodik leistet einen wichtigen Beitrag zur Verbesserung evidenzbasierter Entwurfsprozesse, da sie eine Br{\"u}cke zwischen der nutzerorientierten Bewertung von r{\"a}umlichen Konfigurationen und deren Erzeugung schl{\"a}gt.},
  subject      = {Architektur},
  language  = {de}
}
@phdthesis{List,
  author    = {List, Eik},
  title     = {Design, Analysis, and Implementation of Symmetric-key (Authenticated) Ciphers},
  doi       = {10.25643/bauhaus-universitaet.4523},
  url       = {http://nbn-resolving.de/urn:nbn:de:gbv:wim2-20211103-45235},
  school      = {Bauhaus-Universit{\"a}t Weimar},
  pages     = {258},
  abstract  = {Modern cryptography has become an often ubiquitous but essential part of our daily lives. Protocols for secure authentication and encryption protect our communication with various digital services, from private messaging, online shopping, to bank transactions or exchanging sensitive information. Those high-level protocols can naturally be only as secure as the authentication or encryption schemes underneath. Moreover, on a more detailed level, those schemes can also at best inherit the security of their underlying primitives. While widespread standards in modern symmetric-key cryptography, such as the Advanced Encryption Standard (AES), have shown to resist analysis until now, closer analysis and design of related primitives can deepen our understanding. The present thesis consists of two parts that portray six contributions: The first part considers block-cipher cryptanalysis of the round-reduced AES, the AES-based tweakable block cipher Kiasu-BC, and TNT. The second part studies the design, analysis, and implementation of provably secure authenticated encryption schemes. In general, cryptanalysis aims at finding distinguishable properties in the output distribution. Block ciphers are a core primitive of symmetric-key cryptography which are useful for the construction of various higher-level schemes, ranging from authentication, encryption, authenticated encryption up to integrity protection. Therefore, their analysis is crucial to secure cryptographic schemes at their lowest level. With rare exceptions, block-cipher cryptanalysis employs a systematic strategy of investigating known attack techniques. Modern proposals are expected to be evaluated against these techniques. The considerable effort for evaluation, however, demands efforts not only from the designers but also from external sources. The Advanced Encryption Standard (AES) is one of the most widespread block ciphers nowadays. Therefore, it is naturally an interesting target for further analysis. Tweakable block ciphers augment the usual inputs of a secret key and a public plaintext by an additional public input called tweak. Among various proposals through the previous decade, this thesis identifies Kiasu-BC as a noteworthy attempt to construct a tweakable block cipher that is very close to the AES. Hence, its analysis intertwines closely with that of the AES and illustrates the impact of the tweak on its security best. Moreover, it revisits a generic tweakable block cipher Tweak-and-Tweak (TNT) and its instantiation based on the round-reduced AES. The first part investigates the security of the AES against several forms of differential cryptanalysis, developing distinguishers on four to six (out of ten) rounds of AES. For Kiasu-BC, it exploits the additional freedom in the tweak to develop two forms of differential-based attacks: rectangles and impossible differentials. The results on Kiasu-BC consider an additional round compared to attacks on the (untweaked) AES. The authors of TNT had provided an initial security analysis that still left a gap between provable guarantees and attacks. Our analysis conducts a considerable step towards closing this gap. For TNT-AES - an instantiation of TNT built upon the AES round function - this thesis further shows how to transform our distinguisher into a key-recovery attack. Many applications require the simultaneous authentication and encryption of transmitted data. Authenticated encryption (AE) schemes provide both properties. Modern AE schemes usually demand a unique public input called nonce that must not repeat. Though, this requirement cannot always be guaranteed in practice. As part of a remedy, misuse-resistant and robust AE tries to reduce the impact of occasional misuses. However, robust AE considers not only the potential reuse of nonces. Common authenticated encryption also demanded that the entire ciphertext would have to be buffered until the authentication tag has been successfully verified. In practice, this approach is difficult to ensure since the setting may lack the resources for buffering the messages. Moreover, robustness guarantees in the case of misuse are valuable features. The second part of this thesis proposes three authenticated encryption schemes: RIV, SIV-x, and DCT. RIV is robust against nonce misuse and the release of unverified plaintexts. Both SIV-x and DCT provide high security independent from nonce repetitions. As the core under SIV-x, this thesis revisits the proof of a highly secure parallel MAC, PMAC-x, revises its details, and proposes SIV-x as a highly secure authenticated encryption scheme. Finally, DCT is a generic approach to have n-bit secure deterministic AE but without the need of expanding the ciphertext-tag string by more than n bits more than the plaintext. From its first part, this thesis aims to extend the understanding of the (1) cryptanalysis of round-reduced AES, as well as the understanding of (2) AES-like tweakable block ciphers. From its second part, it demonstrates how to simply extend known approaches for (3) robust nonce-based as well as (4) highly secure deterministic authenticated encryption.},
  subject      = {Kryptologie},
  language  = {en}
}
@phdthesis{Schollmeyer,
  author    = {Schollmeyer, Andre},
  title     = {Efficient and High-Quality Rendering of Higher-Order Geometric Data Representations},
  doi       = {10.25643/bauhaus-universitaet.3823},
  url       = {http://nbn-resolving.de/urn:nbn:de:gbv:wim2-20181120-38234},
  school      = {Bauhaus-Universit{\"a}t Weimar},
  pages     = {143},
  abstract  = {Computer-Aided Design (CAD) bezeichnet den Entwurf industrieller Produkte mit Hilfe von virtuellen 3D Modellen. Ein CAD-Modell besteht aus parametrischen Kurven und Fl{\"a}chen, in den meisten F{\"a}llen non-uniform rational B-Splines (NURBS). Diese mathematische Beschreibung wird ebenfalls zur Analyse, Optimierung und Pr{\"a}sentation des Modells verwendet. In jeder dieser Entwicklungsphasen wird eine unterschiedliche visuelle Darstellung ben{\"o}tigt, um den entsprechenden Nutzern ein geeignetes Feedback zu geben. Designer bevorzugen beispielsweise illustrative oder realistische Darstellungen, Ingenieure ben{\"o}tigen eine verst{\"a}ndliche Visualisierung der Simulationsergebnisse, w{\"a}hrend eine immersive 3D Darstellung bei einer Benutzbarkeitsanalyse oder der Designauswahl hilfreich sein kann. Die interaktive Darstellung von NURBS-Modellen und -Simulationsdaten ist jedoch aufgrund des hohen Rechenaufwandes und der eingeschr{\"a}nkten Hardwareunterst{\"u}tzung eine große Herausforderung. Diese Arbeit stellt vier neuartige Verfahren vor, welche sich mit der interaktiven Darstellung von NURBS-Modellen und Simulationensdaten befassen. Die vorgestellten Algorithmen nutzen neue F{\"a}higkeiten aktueller Grafikkarten aus, um den Stand der Technik bez{\"u}glich Qualit{\"a}t, Effizienz und Darstellungsgeschwindigkeit zu verbessern. Zwei dieser Verfahren befassen sich mit der direkten Darstellung der parametrischen Beschreibung ohne Approximationen oder zeitaufw{\"a}ndige Vorberechnungen. Die dabei vorgestellten Datenstrukturen und Algorithmen erm{\"o}glichen die effiziente Unterteilung, Klassifizierung, Tessellierung und Darstellung getrimmter NURBS-Fl{\"a}chen und einen interaktiven Ray-Casting-Algorithmus f{\"u}r die Isofl{\"a}chenvisualisierung von NURBSbasierten isogeometrischen Analysen. Die weiteren zwei Verfahren beschreiben zum einen das vielseitige Konzept der programmierbaren Transparenz f{\"u}r illustrative und verst{\"a}ndliche Visualisierungen tiefenkomplexer CAD-Modelle und zum anderen eine neue hybride Methode zur Reprojektion halbtransparenter und undurchsichtiger Bildinformation f{\"u}r die Beschleunigung der Erzeugung von stereoskopischen Bildpaaren. Die beiden letztgenannten Ans{\"a}tze basieren auf rasterisierter Geometrie und sind somit ebenfalls f{\"u}r normale Dreiecksmodelle anwendbar, wodurch die Arbeiten auch einen wichtigen Beitrag in den Bereichen der Computergrafik und der virtuellen Realit{\"a}t darstellen. Die Auswertung der Arbeit wurde mit großen, realen NURBS-Datens{\"a}tzen durchgef{\"u}hrt. Die Resultate zeigen, dass die direkte Darstellung auf Grundlage der parametrischen Beschreibung mit interaktiven Bildwiederholraten und in subpixelgenauer Qualit{\"a}t m{\"o}glich ist. Die Einf{\"u}hrung programmierbarer Transparenz erm{\"o}glicht zudem die Umsetzung kollaborativer 3D Interaktionstechniken f{\"u}r die Exploration der Modelle in virtuellenUmgebungen sowie illustrative und verst{\"a}ndliche Visualisierungen tiefenkomplexer CAD-Modelle. Die Erzeugung stereoskopischer Bildpaare f{\"u}r die interaktive Visualisierung auf 3D Displays konnte beschleunigt werden. Diese messbare Verbesserung wurde zudem im Rahmen einer Nutzerstudie als wahrnehmbar und vorteilhaft befunden.},
  subject      = {Rendering},
  language  = {en}
}
@phdthesis{Beck,
  author    = {Beck, Stephan},
  title     = {Immersive Telepresence Systems and Technologies},
  doi       = {10.25643/bauhaus-universitaet.3856},
  url       = {http://nbn-resolving.de/urn:nbn:de:gbv:wim2-20190218-38569},
  school      = {Bauhaus-Universit{\"a}t Weimar},
  pages     = {149},
  abstract  = {Modern immersive telepresence systems enable people at different locations to meet in virtual environments using realistic three-dimensional representations of their bodies. For the realization of such a three-dimensional version of a video conferencing system, each user is continuously recorded in 3D. These 3D recordings are exchanged over the network between remote sites. At each site, the remote recordings of the users, referred to as 3D video avatars, are seamlessly integrated into a shared virtual scenery and displayed in stereoscopic 3D for each user from his or her perspective. This thesis reports on algorithmic and technical contributions to modern immersive telepresence systems and presents the design, implementation and evaluation of the first immersive group-to-group telepresence system in which each user is represented as realistic life-size 3D video avatar. The system enabled two remote user groups to meet and collaborate in a consistent shared virtual environment. The system relied on novel methods for the precise calibration and registration of color- and depth- sensors (RGBD) into the coordinate system of the application as well as an advanced distributed processing pipeline that reconstructs realistic 3D video avatars in real-time. During the course of this thesis, the calibration of 3D capturing systems was greatly improved. While the first development focused on precisely calibrating individual RGBD-sensors, the second stage presents a new method for calibrating and registering multiple color and depth sensors at a very high precision throughout a large 3D capturing volume. This method was further refined by a novel automatic optimization process that significantly speeds up the manual operation and yields similarly high accuracy. A core benefit of the new calibration method is its high runtime efficiency by directly mapping from raw depth sensor measurements into an application coordinate system and to the coordinates of its associated color sensor. As a result, the calibration method is an efficient solution in terms of precision and applicability in virtual reality and immersive telepresence applications. In addition to the core contributions, the results of two case studies which address 3D reconstruction and data streaming lead to the final conclusion of this thesis and to directions of future work in the rapidly advancing field of immersive telepresence research.},
  subject      = {Virtuelle Realit{\"a}t},
  language  = {en}
}
@phdthesis{Berhe,
  author    = {Berhe, Asgedom Haile},
  title     = {Mitigating Risks of Corruption in Construction: A theoretical rationale for BIM adoption in Ethiopia},
  doi       = {10.25643/bauhaus-universitaet.4517},
  url       = {http://nbn-resolving.de/urn:nbn:de:gbv:wim2-20211007-45175},
  school      = {Bauhaus-Universit{\"a}t Weimar},
  pages     = {336},
  abstract  = {This PhD thesis sets out to investigate the potentials of Building Information Modeling (BIM) to mitigate risks of corruption in the Ethiopian public construction sector. The wide-ranging capabilities and promises of BIM have led to the strong perception among researchers and practitioners that it is an indispensable technology. Consequently, it has become the frequent subject of science and research. Meanwhile, many countries, especially the developed ones, have committed themselves to applying the technology extensively. Increasing productivity is the most common and frequently cited reason for that. However, both technology developers and adopters are oblivious to the potentials of BIM in addressing critical challenges in the construction sector, such as corruption. This particularly would be significant in developing countries like Ethiopia, where its problems and effects are acute. Studies reveal that bribery and corruption have long pervaded the construction industry worldwide. The complex and fragmented nature of the sector provides an environment for corruption. The Ethiopian construction sector is not immune from this epidemic reality. In fact, it is regarded as one of the most vulnerable sectors owing to varying socio-economic and political factors. Since 2015, Ethiopia has started adopting BIM, yet without clear goals and strategies. As a result, the potential of BIM for combating concrete problems of the sector remains untapped. To this end, this dissertation does pioneering work by showing how collaboration and coordination features of the technology contribute to minimizing the opportunities for corruption. Tracing loopholes, otherwise, would remain complex and ineffective in the traditional documentation processes. Proceeding from this anticipation, this thesis brings up two primary questions: what are areas and risks of corruption in case of the Ethiopian public construction projects; and how could BIM be leveraged to mitigate these risks? To tackle these and other secondary questions, the research employs a mixed-method approach. The selected main research strategies are Survey, Grounded Theory (GT) and Archival Study. First, the author disseminates an online questionnaire among Ethiopian construction engineering professionals to pinpoint areas of vulnerability to corruption. 155 responses are compiled and scrutinized quantitatively. Then, a semi-structured in-depth interview is conducted with 20 senior professionals, primarily to comprehend opportunities for and risks of corruption in those identified highly vulnerable project stages and decision points. At the same time, open interviews (consultations) are held with 14 informants to be aware of state of the construction documentation, BIM and loopholes for corruption in the country. Consequently, these qualitative data are analyzed utilizing the principles of GT, heat/risk mapping and Social Network Analysis (SNA). The risk mapping assists the researcher in the course of prioritizing corruption risks; whilst through SNA, methodically, it is feasible to identify key actors/stakeholders in the corruption venture. Based on the generated research data, the author constructs a [substantive] grounded theory around the elements of corruption in the Ethiopian public construction sector. This theory, later, guides the subsequent strategic proposition of BIM. Finally, 85 public construction related cases are also analyzed systematically to substantiate and confirm previous findings. By ways of these multiple research endeavors that is based, first and foremost, on the triangulation of qualitative and quantitative data analysis, the author conveys a number of key findings. First, estimations, tender document preparation and evaluation, construction material as well as quality control and additional work orders are found to be the most vulnerable stages in the design, tendering and construction phases respectively. Second, middle management personnel of contractors and clients, aided by brokers, play most critical roles in corrupt transactions within the prevalent corruption network. Third, grand corruption persists in the sector, attributed to the fact that top management and higher officials entertain their overriding power, supported by the lack of project audits and accountability. Contrarily, individuals at operation level utilize intentional and unintentional 'errors' as an opportunity for corruption. In light of these findings, two conceptual BIM-based risk mitigation strategies are prescribed: active and passive automation of project audits; and the monitoring of project information throughout projects' value chain. These propositions are made in reliance on BIM's present dimensional capabilities and the promises of Integrated Project Delivery (IPD). Moreover, BIM's synchronous potentials with other technologies such as Information and Communication Technology (ICT), and Radio Frequency technologies are topics which received a treatment. All these arguments form the basis for the main thesis of this dissertation, that BIM is able to mitigate corruption risks in the Ethiopian public construction sector. The discourse on the skepticisms about BIM that would stem from the complex nature of corruption and strategic as well as technological limitations of BIM is also illuminated and complemented by this work. Thus, the thesis uncovers possible research gaps and lays the foundation for further studies.},
  subject      = {Building Information Modeling},
  language  = {en}
}
@phdthesis{PreisDutra,
  author    = {Preis Dutra, Joatan},
  title     = {Cultural Heritage on Mobile Devices: Building Guidelines for UNESCO World Heritage Sites' Apps},
  doi       = {10.25643/bauhaus-universitaet.4531},
  url       = {http://nbn-resolving.de/urn:nbn:de:gbv:wim2-20211129-45319},
  school      = {Bauhaus-Universit{\"a}t Weimar},
  pages     = {360},
  abstract  = {Technological improvements and access provide a fertile scenario for creating and developing mobile applications (apps). This scenario results in a myriad of Apps providing information regarding touristic destinations, including those with a cultural profile, such as those dedicated to UNESCO World Heritage Sites (WHS). However, not all of the Apps have the same efficiency. In order to have a successful app, its development must consider usability aspects and features aligned with reliable content. Despite the guidelines for mobile usability being broadly available, they are generic, and none of them concentrates specifically into cultural heritage places, especially on those placed in an open-air scenario. This research aims to fulfil this literature gap and discusses how to adequate and develop specific guidelines for a better outdoor WHS experience. It uses an empirical approach applied to an open-air WHS city: Weimar and its Bauhaus and Classical Weimar sites. In order to build a new set of guidelines applied for open-air WHS, this research used a systematic approach to compare literature-based guidelines to industry-based ones (based on affordances), extracted from the available Apps dedicated to WHS set in Germany. The instructions compiled from both sources have been comparatively tested by using two built prototypes from the distinctive guidelines, creating a set of recommendations collecting the best approach from both sources, plus suggesting new ones the evaluation.},
  subject      = {Benutzerschnittstellenentwurfssystem},
  language  = {en}
}
@phdthesis{Rausch,
  author    = {Rausch, Gabriel},
  title     = {Dreidimensionale Webanwendungen zur Verr{\"a}umlichung von Informationen},
  doi       = {10.25643/bauhaus-universitaet.2702},
  url       = {http://nbn-resolving.de/urn:nbn:de:gbv:wim2-20161116-27029},
  school      = {Bauhaus-Universit{\"a}t Weimar},
  pages     = {204},
  abstract  = {Die vorliegende Arbeit untersucht das Potential von Webanwendungen in 3D zur Vermittlung von Informationen im Allgemeinen und zur Darstellung von st{\"a}dtebaulichen Zusammenh{\"a}ngen im Speziellen. Als grundlegender Faktor der visuellen und funktionalen Qualit{\"a}t - welche die Wahrnehmung des Nutzers direkt beeinflusst -, erfolgt die Bewertung der Machbarkeit von 3D Webinhalten unter Anwendung einer explorativen, qualitativen Evaluierung von Webagenturen. Darauf aufbauend wird das Potential von 3D Webanwendungen aus Nutzerperspektive untersucht, um Zusammenh{\"a}nge herstellen zu k{\"o}nnen: einerseits zwischen der Machbarkeit bei der Entwicklung und anderseits die Akzeptanzkriterien beim Rezipienten betreffend. Die empirische Studie, die mit dem Forschungspartner Bosch f{\"u}r diese Arbeit modelliert wurde, eruiert zum einen, inwiefern 3D im Vergleich zu 2D und 2,5D, und zum anderen WebGL im Vergleich zu bisherigen 3D Webtechnologien die visuelle Wahrnehmung und kognitive Leistungsf{\"a}higkeit des Nutzers beeinflusst. Die Erkenntnisse der Untersuchung zeigen Parallelen zu bestehenden Studien aus web-fernen Bereichen. Um die Bedeutung von 3D Webanwendungen zur Verbesserung von Entscheidungsprozessen in Stadtplanungsprojekten ableiten zu k{\"o}nnen, werden Aspekte zur Interaktion und visuellen Wahrnehmung in den speziellen Kontext von Stadtplanungswerkzeugen gebracht. Dabei wird {\"u}berpr{\"u}ft, ob sich web-basierte 3D Visualisierungen sinnvoll zur Vermittlung st{\"a}dtebaulicher Zusammenh{\"a}nge einbinden lassen und inwieweit bestehende Projekte, wie in dieser Arbeit beispielhaft das vom Fraunhofer IGD entwickelte Forschungsprojekt urbanAPI, die Technologie WebGL nutzen k{\"o}nnen. Vor diesem Hintergrund soll die Arbeit Akzeptanzkriterien und Nutzungsbarrieren von 3D Webanwendungen auf Basis der Technologie WebGL identifizieren, um einen Beitrag zur Machbarkeit von Webanwendungen und zur Entwicklung entsprechender Stadtplanungswerkzeuge zu leisten.},
  subject      = {WEB},
  language  = {de}
}
@phdthesis{Mthunzi,
  author    = {Mthunzi, Everett},
  title     = {Interactive Surface Environments: Design and Implementation},
  doi       = {10.25643/bauhaus-universitaet.6406},
  url       = {http://nbn-resolving.de/urn:nbn:de:gbv:wim2-20230704-64065},
  school      = {Bauhaus-Universit{\"a}t Weimar},
  pages     = {128},
  abstract  = {This dissertation presents three studies on the design and implementation of interactive surface environments. It puts forward approaches to engineering interactive surface prototypes using prevailing methodologies and technologies. The scholarly findings from each study have been condensed into academic manuscripts, which are conferred herewith. The first study identifies a communication gap between engineers of interactive surface systems (i.e., originators of concepts) and future developers. To bridge the gap, it explores a UML-based framework to establish a formal syntax for modeling hardware, middleware, and software of interactive surface prototypes. The proposed framework targets models-as-end-products, towards enabling a shared view of research prototypes thereby facilitating dialogue between concept originators and future developers. The second study positions itself to support developers with an open-source solution for exploiting 3D point clouds for interactive tabletop applications using CPU architectures. Given dense 3D point-cloud representations of tabletop environments, the study aims toward mitigating high computational effort by segmenting candidate interaction regions as a preprocessing step. The study contributes a robust open-source solution for reducing computational costs when leveraging 3D point clouds for interactive tabletop applications. The solution itself is flexible and adaptable to variable interactive surface applications. The third study contributes an archetypal concept for integrating mobile devices as active components in augmented tabletop surfaces. With emphasis on transparent development trails, the study demonstrates the utility of the open-source tool developed in the second study. In addition to leveraging 3D point clouds for real-time interaction, the research considers recent advances in computer vision and wireless communication to realize a modern, interactive tabletop application. A robust strategy that combines spatial augmented reality, point-cloud-based depth perception, CNN-based object detection, and Bluetooth communication is put forward. In addition to seamless communication between adhoc mobile devices and interactive tabletop systems, the archetypal concept demonstrates the benefits of preprocessing point clouds by segmenting candidate interaction regions, as suggested in the second study. Collectively, the studies presented in this dissertation contribute; 1—bridging the gap between originators of interactive surface concepts and future developers, 2— promoting the exploration of 3D point clouds for interactive surface applications using CPU-based architectures, and 3—leveraging 3D point clouds together with emerging CNN-based object detection, and Bluetooth communication technologies to advance existing surface interaction concepts.},
  subject      = {Mensch-Maschiene-Kommunikation},
  language  = {en}
}
@phdthesis{AlKhatib2021,
  author    = {Al Khatib, Khalid},
  title     = {Computational Analysis of Argumentation Strategies},
  doi       = {10.25643/bauhaus-universitaet.4461},
  url       = {http://nbn-resolving.de/urn:nbn:de:gbv:wim2-20210719-44612},
  school      = {Bauhaus-Universit{\"a}t Weimar},
  pages     = {134},
  year      = {2021},
  abstract  = {The computational analysis of argumentation strategies is substantial for many downstream applications. It is required for nearly all kinds of text synthesis, writing assistance, and dialogue-management tools. While various tasks have been tackled in the area of computational argumentation, such as argumentation mining and quality assessment, the task of the computational analysis of argumentation strategies in texts has so far been overlooked. This thesis principally approaches the analysis of the strategies manifested in the persuasive argumentative discourses that aim for persuasion as well as in the deliberative argumentative discourses that aim for consensus. To this end, the thesis presents a novel view of argumentation strategies for the above two goals. Based on this view, new models for pragmatic and stylistic argument attributes are proposed, new methods for the identification of the modelled attributes have been developed, and a new set of strategy principles in texts according to the identified attributes is presented and explored. Overall, the thesis contributes to the theory, data, method, and evaluation aspects of the analysis of argumentation strategies. The models, methods, and principles developed and explored in this thesis can be regarded as essential for promoting the applications mentioned above, among others.},
  subject      = {Argumentation},
  language  = {en}
}