@phdthesis{Staeudel, author = {St{\"a}udel, J{\"u}rgen}, title = {Development, Implementation and Operation of Integrated Sanitation Systems Based on Material-Flows - Integrated Sanitation in the City of Darkhan, Mongolia - A Practicable Example}, doi = {10.25643/bauhaus-universitaet.3179}, url = {http://nbn-resolving.de/urn:nbn:de:gbv:wim2-20170512-31794}, school = {Bauhaus-Universit{\"a}t Weimar}, abstract = {The world society faces a huge challenge to implement the human right of "access to sanitation". More and more it is accepted that the conventional approach towards providing sanitation services is not suitable to solve this problem. This dissertation examines the possibility to enhance "access to sanitation" for people who are living in areas with underdeveloped water and wastewater infrastructure systems. The idea hereby is to follow an integrated approach for sanitation, which allows for a mutual completion of existing infrastructure with resource-based sanitation systems. The notion "integrated sanitation system (iSaS)" is defined in this work and guiding principles for iSaS are formulated. Further on the implementation of iSaS is assessed at the example of a case study in the city of Darkhan in Mongolia. More than half of Mongolia's population live in settlements where yurts (tents of Nomadic people) are predominant. In these settlements (or "ger areas") sanitation systems are not existent and the hygienic situation is precarious. An iSaS has been developed for the ger areas in Darkhan and tested over more than two years. Further on a software-based model has been developed with the goal to describe and assess different variations of the iSaS. The results of the assessment of material-flows, monetary-flows and communication-flows within the iSaS are presented in this dissertation. The iSaS model is adaptable and transferable to the socio-economic conditions in other regions and climate zones.}, subject = {Abwasser}, language = {en} } @phdthesis{MeyerKohlstock, author = {Meyer-Kohlstock, Daniel}, title = {Prospects for Biochar in a Bio-Waste Cascade}, doi = {10.25643/bauhaus-universitaet.3631}, url = {http://nbn-resolving.de/urn:nbn:de:gbv:wim2-20171108-36310}, school = {Bauhaus-Universit{\"a}t Weimar}, pages = {118}, abstract = {In the early 2000s the pre-Columbian, anthropologically produced black soil in the Amazon basin, „Terra Preta de {\´I}ndio", received greater scientific attention. Compared to the surrounding poor soils, this very fertile anthrosol contains significantly higher levels of microorganisms and nutrients. The reason for this was determined to be the likewise high levels of charred biomass. This stable carbon, now called biochar, has since been intensively examined as an option to improve soil and to store carbon. Although the creation of Terra Preta was most likely based on a purposeful utilization of organic residues from households and gardens, biochar plays no role in the current recycling of bio-waste. However, the implementation of biochar could lead to many improvements. Results from agricultural research suggest that not only the yield capacity of soils can be increased but also the process performance of composting and biogas plants. The latter is especially relevant since currently about 40\% of all collected bio-waste in Germany is recycled in an energy-material cascade consisting of anaerobic digestion and composting. The use of biochar in this cascade could then sequentially increase biogas yields, reduce greenhouse gas emissions, and improve compost quality. To realize the aforementioned advantages, the concept of biochar has to be integrated into the existing bio-waste cascade as practically as possible. This was done by the development of a theoretical scenario that allowed the analysis of energy and material flows to evaluate biochar's recycling performance. Furthermore, the legal and economic framework were examined to assess the feasibility of the extended cascade and to suggest possible adjustments to the frameworks.}, subject = {Kompost}, language = {en} } @phdthesis{Schwedler, author = {Schwedler, Michael}, title = {Integrated structural analysis using isogeometric finite element methods}, doi = {10.25643/bauhaus-universitaet.2737}, url = {http://nbn-resolving.de/urn:nbn:de:gbv:wim2-20170130-27372}, school = {Bauhaus-Universit{\"a}t Weimar}, pages = {209}, abstract = {The gradual digitization in the architecture, engineering, and construction industry over the past fifty years led to an extremely heterogeneous software environment, which today is embodied by the multitude of different digital tools and proprietary data formats used by the many specialists contributing to the design process in a construction project. Though these projects become increasingly complex, the demands on financial efficiency and the completion within a tight schedule grow at the same time. The digital collaboration of project partners has been identified as one key issue in successfully dealing with these challenges. Yet currently, the numerous software applications and their respective individual views on the design process severely impede that collaboration. An approach to establish a unified basis for the digital collaboration, regardless of the existing software heterogeneity, is a comprehensive digital building model contributed to by all projects partners. This type of data management known as building information modeling (BIM) has many benefits, yet its adoption is associated with many difficulties and thus, proceeds only slowly. One aspect in the field of conflicting requirements on such a digital model is the cooperation of architects and structural engineers. Traditionally, these two disciplines use different abstractions of reality for their models that in consequence lead to incompatible digital representations thereof. The onset of isogeometric analysis (IGA) promised to ease the discrepancy in design and analysis model representations. Yet, that initial focus quickly shifted towards using these methods as a more powerful basis for numerical simulations. Furthermore, the isogeometric representation alone is not capable of solving the model abstraction problem. It is thus the intention of this work to contribute to an improved digital collaboration of architects and engineers by exploring an integrated analysis approach on the basis of an unified digital model and solid geometry expressed by splines. In the course of this work, an analysis framework is developed that utilizes such models to automatically conduct numerical simulations commonly required in construction projects. In essence, this allows to retrieve structural analysis results from BIM models in a fast and simple manner, thereby facilitating rapid design iterations and profound design feedback. The BIM implementation Industry Foundation Classes (IFC) is reviewed with regard to its capabilities of representing the unified model. The current IFC schema strongly supports the use of redundant model data, a major pitfall in digital collaboration. Additionally, it does not allow to describe the geometry by volumetric splines. As the pursued approach builds upon a unique model for both, architectural and structural design, and furthermore requires solid geometry, necessary schema modifications are suggested. Structural entities are modeled by volumetric NURBS patches, each of which constitutes an individual subdomain that, with regard to the analysis, is incompatible with the remaining full model. The resulting consequences for numerical simulation are elaborated in this work. The individual subdomains have to be weakly coupled, for which the mortar method is used. Different approaches to discretize the interface traction fields are implemented and their respective impact on the analysis results is evaluated. All necessary coupling conditions are automatically derived from the related geometry model. The weak coupling procedure leads to a linear system of equations in saddle point form, which, owed to the volumetric modeling, is large in size and, the associated coefficient matrix has, due to the use of higher degree basis functions, a high bandwidth. The peculiarities of the system require adapted solution methods that generally cause higher numerical costs than the standard procedures for symmetric, positive-definite systems do. Different methods to solve the specific system are investigated and an efficient parallel algorithm is finally proposed. When the structural analysis model is derived from the unified model in the BIM data, it does in general initially not meet the requirements on the discretization that are necessary to obtain sufficiently accurate analysis results. The consequently necessary patch refinements must be controlled automatically to allowfor an entirely automatic analysis procedure. For that purpose, an empirical refinement scheme based on the geometrical and possibly mechanical properties of the specific entities is proposed. The level of refinement may be selectively manipulated by the structural engineer in charge. Furthermore, a Zienkiewicz-Zhu type error estimator is adapted for the use with isogeometric analysis results. It is shown that also this estimator can be used to steer an adaptive refinement procedure.}, subject = {Finite-Elemente-Methode}, language = {en} } @phdthesis{Ehrhardt, author = {Ehrhardt, Dirk}, title = {ZUM EINFLUSS DER NACHBEHANDLUNG AUF DIE GEF{\"U}GEAUSBILDUNG UND DEN FROST-TAUMITTELWIDERSTAND DER BETONRANDZONE}, doi = {10.25643/bauhaus-universitaet.3688}, url = {http://nbn-resolving.de/urn:nbn:de:gbv:wim2-20171120-36889}, school = {Bauhaus-Universit{\"a}t Weimar}, pages = {235}, abstract = {Die Festigkeitsentwicklung des Zementbetons basiert auf der chemischen Reaktion des Zementes mit dem Anmachwasser. Durch Nachbehandlungsmaßnahmen muss daf{\"u}r gesorgt werden, dass dem Zement gen{\"u}gend Wasser f{\"u}r seine Reaktion zur Verf{\"u}gung steht, da sonst ein Beton mit minderer Qualit{\"a}t entsteht. Die vorliegende Arbeit behandelt die grunds{\"a}tzlichen Fragen der Betonnachbehandlung bei Anwendung von Straßenbetonen. Im Speziellen wird die Frage des erforderlichen Nachbehandlungsbedarfs von h{\"u}ttensandhaltigen Kompositzementen betrachtet. Die Wirkung der Nachbehandlung wird anhand des erreichten Frost-Tausalz-Widerstandes und der Gef{\"u}geausbildung in der unmittelbaren Betonrandzone bewertet. Der Fokus der Untersuchungen lag auf abgezogenen Betonoberfl{\"a}chen. Es wurde ein Modell zur Austrocknung des jungen Betons erarbeitet. Es konnte gezeigt werden, dass in einer fr{\"u}hen Austrocknung (Kapillarphase) keine kritische Austrocknung der Betonrandzone einsetzt, sondern der Beton ann{\"a}hrend gleichm{\"a}ßig {\"u}ber die H{\"o}he austrocknet. Es wurde ein Nomogramm entwickelt, mit dem die Dauer der Kapillarphase in Abh{\"a}ngigkeit der Witterung f{\"u}r Straßenbetone abgesch{\"a}tzt werden kann. Eine kritische Austrocknung der wichtigen Randzone setzt nach Ende der Kapillarphase ein. F{\"u}r Betone unter Verwendung von Zementen mit langsamer Festigkeitsentwicklung ist die Austrocknung der Randzone nach Ende der Kapillarphase besonders ausgepr{\"a}gt. Im Ergebnis zeigen diese Betone dann einen geringen Frost-Tausalz-Widerstand. Mit Zementen, die eine 2d-Zementdruckfestigkeit ≥ 23,0 N/mm² aufweisen, wurde unabh{\"a}ngig von der Zementart (CEM I oder CEM II/B-S) auch dann ein hoher Frost-Tausalz-Widerstand erreicht, wenn keine oder eine schlechtere Nachbehandlung angewendet wurde. F{\"u}r die Praxis ergibt sich damit eine einfache M{\"o}glichkeit der Vorauswahl von geeigneten Zementen f{\"u}r den Verkehrsfl{\"a}chenbau. Betone, die unter Verwendung von Zementen mit langsamere Festigkeitsentwicklung hergestellt werden, erreichen einen hohen Frost-Tausalz-Widerstand nur mit einer geeigneten Nachbehandlung. Die Anwendung von fl{\"u}ssigen Nachbehandlungsmitteln (NBM gem{\"a}ß TL NBM-StB) erreicht eine {\"a}hnliche Wirksamkeit wie eine 5 t{\"a}gige Feuchtnachbehandlung. Voraussetzung f{\"u}r die Wirksamkeit der NBM ist, dass sie auf eine Betonoberfl{\"a}che ohne sichtbaren Feuchtigkeitsfilm (feuchter Glanz) aufgespr{\"u}ht werden. Besonders wichtig ist die Beachtung des richtigen Auftragszeitpunktes bei k{\"u}hler Witterung, da hier aufgrund der verlangsamten Zementreaktion der Beton l{\"a}nger Anmachwasser abst{\"o}ßt. Ein zu fr{\"u}her Auftrag des Nachbehandlungsmittels f{\"u}hrt zu einer Verschlechterung der Qualit{\"a}t der Betonrandzone. Durch Bereitstellung hydratationsabh{\"a}ngiger Transportkenngr{\"o}ßen (Feuchtetransport im Beton) konnten numerische Berechnungen zum Zusammenspiel zwischen der Austrocknung, der Nachbehandlung und der Gef{\"u}geentwicklung durchgef{\"u}hrt werden. Mit dem erstellten Berechnungsmodell wurden Parameterstudien durchgef{\"u}hrt. Die Berechnungen best{\"a}tigen die wesentlichen Erkenntnisse der Laboruntersuchungen. Dar{\"u}ber hinaus l{\"a}sst sich mit dem Berechnungsmodell zeigen, dass gerade bei langsam reagierenden Zementen und k{\"u}hler Witterung ohne eine Nachbehandlung eine sehr d{\"u}nne Randzone (ca. 500 µm - 1000 µm) mit stark erh{\"o}hter Kapillarporosit{\"a}t entsteht.}, subject = {Beton}, language = {de} } @phdthesis{Msekh, author = {Msekh, Mohammed Abdulrazzak}, title = {Phase Field Modeling for Fracture with Applications to Homogeneous and Heterogeneous Materials}, doi = {10.25643/bauhaus-universitaet.3229}, url = {http://nbn-resolving.de/urn:nbn:de:gbv:wim2-20170615-32291}, school = {Bauhaus-Universit{\"a}t Weimar}, pages = {190}, abstract = {The thesis presents an implementation including different applications of a variational-based approach for gradient type standard dissipative solids. Phase field model for brittle fracture is an application of the variational-based framework for gradient type solids. This model allows the prediction of different crack topologies and states. Of significant concern is the application of theoretical and numerical formulation of the phase field modeling into the commercial finite element software Abaqus in 2D and 3D. The fully coupled incremental variational formulation of phase field method is implemented by using the UEL and UMAT subroutines of Abaqus. The phase field method considerably reduces the implementation complexity of fracture problems as it removes the need for numerical tracking of discontinuities in the displacement field that are characteristic of discrete crack methods. This is accomplished by replacing the sharp discontinuities with a scalar damage phase field representing the diffuse crack topology wherein the amount of diffusion is controlled by a regularization parameter. The nonlinear coupled system consisting of the linear momentum equation and a diffusion type equation governing the phase field evolution is solved simultaneously via a Newton- Raphson approach. Post-processing of simulation results to be used as visualization module is performed via an additional UMAT subroutine implemented in the standard Abaqus viewer. In the same context, we propose a simple yet effective algorithm to initiate and propagate cracks in 2D geometries which is independent of both particular constitutive laws and specific element technology and dimension. It consists of a localization limiter in the form of the screened Poisson equation with, optionally, local mesh refinement. A staggered scheme for standard equilibrium and screened Cauchy equations is used. The remeshing part of the algorithm consists of a sequence of mesh subdivision and element erosion steps. Element subdivision is based on edge split operations using a given constitutive quantity (either damage or void fraction). Mesh smoothing makes use of edge contraction as function of a given constitutive quantity such as the principal stress or void fraction. To assess the robustness and accuracy of this algorithm, we use both quasi-brittle benchmarks and ductile tests. Furthermore, we introduce a computational approach regarding mechanical loading in microscale on an inelastically deforming composite material. The nanocomposites material of fully exfoliated clay/epoxy is shaped to predict macroscopic elastic and fracture related material parameters based on their fine-scale features. Two different configurations of polymer nanocomposites material (PNCs) have been studied. These configurations are fully bonded PNCs and PNCs with an interphase zone formation between the matrix and the clay reinforcement. The representative volume element of PNCs specimens with different clay weight contents, different aspect ratios, and different interphase zone thicknesses are generated by adopting Python scripting. Different constitutive models are employed for the matrix, the clay platelets, and the interphase zones. The brittle fracture behavior of the epoxy matrix and the interphase zones material are modeled using the phase field approach, whereas the stiff silicate clay platelets of the composite are designated as a linear elastic material. The comprehensive study investigates the elastic and fracture behavior of PNCs composites, in addition to predict Young's modulus, tensile strength, fracture toughness, surface energy dissipation, and cracks surface area in the composite for different material parameters, geometry, and interphase zones properties and thicknesses.}, subject = {Finite-Elemente-Methode}, language = {en} } @phdthesis{Podlaszewska, author = {Podlaszewska, Rizky Suci Ammalia}, title = {The Placemaking of Destination. Localization and Commoditization process of Urban Tourism. Study case Palembang Indonesia}, doi = {10.25643/bauhaus-universitaet.3699}, url = {http://nbn-resolving.de/urn:nbn:de:gbv:wim2-20171201-36995}, school = {Bauhaus-Universit{\"a}t Weimar}, abstract = {This research addresses the discourse of tourism as a tool for place-making of urban destination. Relevant to the study of place-making is the analysis of the commoditization and localization process dependent upon the appropriation of urban landscape and local cultures. In the research, localization is interpreted as the act of determining the attributes of locality, while commoditization is defined as the process by which local attributes that have commercial potential end up in becoming tourism commodity. Following this, the commoditization of intrinsic cultural value is disseminated within a branding strategy and intervention reflecting social and political relations. Therefore, the research suggests that tourism place-making has not only been constructed through the top-down regulatory body, but has been also generated through the attributes of its locality. By utilizing the critical and constructivist paradigm, the research depicts the conditions of the localization and commoditization process in establishing the base line of its realization within the symbolic economy. Thus, a qualitative case study approach was adopted. The study area of this dissertation is Palembang, as one of the capital cities in Indonesia advancing in its overall urban development. To investigate urban tourism as a tool for development strategy, it is useful to investigate the role of tourism which embodies (1) spatial transformation; how tourism gives significant impacts on urban form, and (2) the socio-cultural aspect; how neighbourhood is related to tourism industry. The findings suggest that tourism place-making involves the reciprocity of urban dynamics: cities take on tourism as a reference model of development, and tourist areas adopt the proliferation of cultural lifestyle to meet the industry's demands.}, subject = {Urbanistik}, language = {en} } @phdthesis{Smirnova, author = {Smirnova, Elena}, title = {"Kennst du das Land, wo bl{\"u}ht Oranienbaum?" - A Case Study on Strategic and Territorial Planning in St. Petersburg (Russia)}, doi = {10.25643/bauhaus-universitaet.3255}, url = {http://nbn-resolving.de/urn:nbn:de:gbv:wim2-20170711-32556}, school = {Bauhaus-Universit{\"a}t Weimar}, abstract = {The research examines the system of strategic and territorial planning of St. Petersburg focusing on Lomonosov (Oranienbaum) as its case study. The study provides the analysis of the planning documentation developed for the city in the post-Soviet period. In particular, it elaborates on the currently enforced Strategy of Economic and Social Development of St. Petersburg-2030 (2014) and the City General Plan (2005), discussing the aspects of their development and implementation, as well as complex interrelation. Thereby, peculiarities of the spatial development of the St. Petersburg agglomeration are also investigated, elaborating on the state policy on agglomerations, historic development of St. Petersburg and relations with the Leningrad Region, governance and imbalances of the St. Petersburg spatial development, including proposed development scenarios. Consequently, the study employs a highly indicative case of the Lomonosov town municipal unit aiming to illustrate the practical implementation of administrative, territorial and strategic policies in a given context within a system of the state planning adopted in St. Petersburg, in particular, taking into consideration recently proclaimed necessity for the transition to a polycentric city model following an innovative scenario for the socioeconomic and spatial development. In particular, Lomonosov (Oranienbaum) is explored egarding its current socio-economic situation and development scenarios: industrial site and cultural tourism. The Oranienbaum museum and nature-reserve is also thoroughly assessed with regard to its cultural tourism potential. Finally, the urban environment of Lomonosov (Oranienbaum) is comprehensively scrutinized in terms of its historic development, residential housing typology, UNESCO World Heritage preservation and local urban heritage. In conclusion, the data on Lomonosov present in the St. Petersburg strategic and territorial planning documents is provided.}, subject = {Lomonossow}, language = {en} } @phdthesis{Nariman, author = {Nariman, Nazim}, title = {Numerical Methods for the Multi-Physical Analysis of Long Span Cable-Stayed Bridges}, doi = {10.25643/bauhaus-universitaet.3710}, url = {http://nbn-resolving.de/urn:nbn:de:gbv:wim2-20171122-37105}, school = {Bauhaus-Universit{\"a}t Weimar}, pages = {236}, abstract = {The main categories of wind effects on long span bridge decks are buffeting, flutter, vortex-induced vibrations (VIV) which are often critical for the safety and serviceability of the structure. With the rapid increase of bridge spans, research on controlling wind-induced vibrations of long span bridges has been a problem of great concern.The developments of vibration control theories have led to the wide use of tuned mass dampers (TMDs) which has been proven to be effective for suppressing these vibrations both analytically and experimentally. Fire incidents are also of special interest in the stability and safety of long span bridges due to significant role of the complex phenomenon through triple interaction between the deck with the incoming wind flow and the thermal boundary of the surrounding air. This work begins with analyzing the buffeting response and flutter instability of three dimensional computational structural dynamics (CSD) models of a cable stayed bridge due to strong wind excitations using ABAQUS finite element commercial software. Optimization and global sensitivity analysis are utilized to target the vertical and torsional vibrations of the segmental deck through considering three aerodynamic parameters (wind attack angle, deck streamlined length and viscous damping of the stay cables). The numerical simulations results in conjunction with the frequency analysis results emphasized the existence of these vibrations and further theoretical studies are possible with a high level of accuracy. Model validation is performed by comparing the results of lift and moment coefficients between the created CSD models and two benchmarks from the literature (flat plate theory) and flat plate by (Xavier and co-authors) which resulted in very good agreements between them. Optimum values of the parameters have been identified. Global sensitivity analysis based on Monte Carlo sampling method was utilized to formulate the surrogate models and calculate the sensitivity indices. The rational effect and the role of each parameter on the aerodynamic stability of the structure were calculated and efficient insight has been constructed for the stability of the long span bridge. 2D computational fluid dynamics (CFD) models of the decks are created with the support of MATLAB codes to simulate and analyze the vortex shedding and VIV of the deck. Three aerodynamic parameters (wind speed, deck streamlined length and dynamic viscosity of the air) are dedicated to study their effects on the kinetic energy of the system and the vortices shapes and patterns. Two benchmarks from the literature (Von Karman) and (Dyrbye and Hansen) are used to validate the numerical simulations of the vortex shedding for the CFD models. A good consent between the results was detected. Latin hypercube experimental method is dedicated to generate the surrogate models for the kinetic energy of the system and the generated lift forces. Variance based sensitivity analysis is utilized to calculate the main sensitivity indices and the interaction orders for each parameter. The kinetic energy approach performed very well in revealing the rational effect and the role of each parameter in the generation of vortex shedding and predicting the early VIV and the critical wind speed. Both one-way fluid-structure interaction (one-way FSI) simulations and two-way fluid-structure interaction (two-way FSI) co-simulations for the 2D models of the deck are executed to calculate the shedding frequencies for the associated wind speeds in the lock-in region in addition to the lift and drag coefficients. Validation is executed with the results of (Simiu and Scanlan) and the results of flat plate theory compiled by (Munson and co-authors) respectively. High levels of agreements between all the results were detected. A decrease in the critical wind speed and the shedding frequencies considering (two-way FSI) was identified compared to those obtained in the (one-way FSI). The results from the (two-way FSI) approach predicted appreciable decrease in the lift and drag forces as well as prediction of earlier VIV for lower critical wind speeds and lock-in regions which exist at lower natural frequencies of the system. These conclusions help the designers to efficiently plan and consider for the design and safety of the long span bridge before and after construction. Multiple tuned mass dampers (MTMDs) system has been applied in the three dimensional CSD models of the cable stayed bridge to analyze their control efficiency in suppressing both wind -induced vertical and torsional vibrations of the deck by optimizing three design parameters (mass ratio, frequency ratio and damping ratio) for the (TMDs) supporting on actual field data and minimax optimization technique in addition to MATLAB codes and Fast Fourier Transform technique. The optimum values of each parameter were identified and validated with two benchmarks from the literature, first with (Wang and co-authors) and then with (Lin and co-authors). The validation procedure detected a good agreement between the results. Box-Behnken experimental method is dedicated to formulate the surrogate models to represent the control efficiency of the vertical and torsional vibrations. Sobol's sensitivity indices are calculated for the design parameters in addition to their interaction orders. The optimization results revealed better performance of the MTMDs in controlling both the vertical and the torsional vibrations for higher mode shapes. Furthermore, the calculated rational effect of each design parameter facilitates to increase the control efficiency of the MTMDs in conjunction with the support of the surrogate models which simplifies the process of analysis for vibration control to a great extent. A novel structural modification approach has been adopted to eliminate the early coupling between the bending and torsional mode shapes of the cable stayed bridge. Two lateral steel beams are added to the middle span of the structure. Frequency analysis is dedicated to obtain the natural frequencies of the first eight mode shapes of vibrations before and after the structural modification. Numerical simulations of wind excitations are conducted for the 3D model of the cable stayed bridge. Both vertical and torsional displacements are calculated at the mid span of the deck to analyze the bending and the torsional stiffness of the system before and after the structural modification. The results of the frequency analysis after applying lateral steel beams declared that the coupling between the vertical and torsional mode shapes of vibrations has been removed to larger natural frequencies magnitudes and higher rare critical wind speeds with a high factor of safety. Finally, thermal fluid-structure interaction (TFSI) and coupled thermal-stress analysis are utilized to identify the effects of transient and steady state heat-transfer on the VIV and fatigue of the deck due to fire incidents. Numerical simulations of TFSI models of the deck are dedicated to calculate the lift and drag forces in addition to determining the lock-in regions once using FSI models and another using TFSI models. Vorticity and thermal fields of three fire scenarios are simulated and analyzed. The benchmark of (Simiu and Scanlan) is used to validate the TFSI models, where a good agreement was manifested between the two results. Extended finite element method (XFEM) is adopted to create 3D models of the cable stayed bridge to simulate the fatigue of the deck considering three fire scenarios. The benchmark of (Choi and Shin) is used to validate the damaged models of the deck in which a good coincide was seen between them. The results revealed that the TFSI models and the coupled thermal-stress models are significant in detecting earlier vortex induced vibration and lock-in regions in addition to predicting damages and fatigue of the deck and identifying the role of wind-induced vibrations in speeding up the damage generation and the collapse of the structure in critical situations.}, subject = {Stabilit{\"a}t}, language = {en} } @phdthesis{Wenzel, author = {Wenzel, Jakob}, title = {Design and Analysis of Cryptographic Algorithms for Authentication}, doi = {10.25643/bauhaus-universitaet.3714}, url = {http://nbn-resolving.de/urn:nbn:de:gbv:wim2-20171208-37140}, school = {Bauhaus-Universit{\"a}t Weimar}, abstract = {During the previous decades, the upcoming demand for security in the digital world, e.g., the Internet, lead to numerous groundbreaking research topics in the field of cryptography. This thesis focuses on the design and analysis of cryptographic primitives and schemes to be used for authentication of data and communication endpoints, i.e., users. It is structured into three parts, where we present the first freely scalable multi-block-length block-cipher-based compression function (Counter-bDM) in the first part. The presented design is accompanied by a thorough security analysis regarding its preimage and collision security. The second and major part is devoted to password hashing. It is motivated by the large amount of leaked password during the last years and our discovery of side-channel attacks on scrypt - the first modern password scrambler that allowed to parameterize the amount of memory required to compute a password hash. After summarizing which properties we expect from a modern password scrambler, we (1) describe a cache-timing attack on scrypt based on its password-dependent memory-access pattern and (2) outline an additional attack vector - garbage-collector attacks - that exploits optimization which may disregard to overwrite the internally used memory. Based on our observations, we introduce Catena - the first memory-demanding password-scrambling framework that allows a password-independent memory-access pattern for resistance to the aforementioned attacks. Catena was submitted to the Password Hashing Competition (PHC) and, after two years of rigorous analysis, ended up as a finalist gaining special recognition for its agile framework approach and side-channel resistance. We provide six instances of Catena suitable for a variety of applications. We close the second part of this thesis with an overview of modern password scramblers regarding their functional, security, and general properties; supported by a brief analysis of their resistance to garbage-collector attacks. The third part of this thesis is dedicated to the integrity (authenticity of data) of nonce-based authenticated encryption schemes (NAE). We introduce the so-called j-IV-Collision Attack, allowing to obtain an upper bound for an adversary that is provided with a first successful forgery and tries to efficiently compute j additional forgeries for a particular NAE scheme (in short: reforgeability). Additionally, we introduce the corresponding security notion j-INT-CTXT and provide a comparative analysis (regarding j-INT-CTXT security) of the third-round submission to the CAESAR competition and the four classical and widely used NAE schemes CWC, CCM, EAX, and GCM.}, subject = {Kryptologie}, language = {en} } @phdthesis{Hollberg, author = {Hollberg, Alexander}, title = {A parametric method for building design optimization based on Life Cycle Assessment}, doi = {10.25643/bauhaus-universitaet.3800}, url = {http://nbn-resolving.de/urn:nbn:de:gbv:wim2-20180928-38000}, school = {Bauhaus-Universit{\"a}t Weimar}, pages = {262}, abstract = {The building sector is responsible for a large share of human environmental impacts. Architects and planners are the key players for reducing the environmental impacts of buildings, as they define them to a large extent. Life Cycle Assessment (LCA) allows for the holistic environmental analysis of a building. However, it is currently not employed to improve the environmental performance of buildings during the design process, although the potential for optimization is greatest there. One main reason is the lack of an adequate means of applying LCA in the architectural design process. As such, the main objective of this thesis is to develop a method for environmental building design optimization that is applicable in the design process. The key concept proposed in this thesis is to combine LCA with parametric design, because it proved to have a high potential for design optimization. The research approach includes the analysis of the characteristics of LCA for buildings and the architectural design stages to identify the research gap, the establishment of a requirement catalogue, the development of a method based on a digital, parametric model, and an evaluation of the method. An analysis of currently available approaches for LCA of buildings indicates that they are either holistic but very complex or simple but not holistic. Furthermore, none of them provide the opportunity for optimization in the architectural design process, which is the main research gap. The requirements derived from the analysis have been summarized in the form of a catalogue. This catalogue can be used to evaluate both existing approaches and potential methods developed in the future. In this thesis, it served as guideline for the development of the parametric method - Parametric Life Cycle Assessment (PLCA). The unique main feature of PLCA is that embodied and operational environmental impact are calculated together. In combination with the self-contained workflow of the method, this provides the basis for holistic, time-efficient environmental design optimization. The application of PLCA to three examples indicated that all established mandatory requirements are met. In all cases, environmental impact could be significantly reduced. In comparison to conventional approaches, PLCA was shown to be much more time-efficient. PLCA allows architects to focus on their main task of designing the building, and finally makes LCA practically useful as one of several criteria for design optimization. With PLCA, the building design can be time-efficiently optimized from the beginning of the most influential early design stages, which has not been possible until now. PLCA provides a good starting point for further research. In the future, it could be extended by integrating the social and economic aspects of sustainability.}, subject = {Bauentwurf}, language = {en} } @phdthesis{Arboleda, author = {Arboleda, Pablo}, title = {Reckoning with Incompiuto Siciliano: Unfinished Public Works as Modern Ruins and All which it Entails}, doi = {10.25643/bauhaus-universitaet.3265}, url = {http://nbn-resolving.de/urn:nbn:de:gbv:wim2-20170715-32656}, school = {Bauhaus-Universit{\"a}t Weimar}, pages = {150}, abstract = {Since the end of the 1950s, Italy has focused part of its modernization on the erection of public works. Due to corruption, mafia, and further malpractice, this form of development has occasionally failed, producing a high number of constructions that have remained unfinished for decades. In 2007, the group of artists Alterazioni Video constructed an informal survey in the form of an on-line tool open to public contributions, which revealed that there are 395 unfinished public works in Italy from which 156, approximately 39.5\%, are located in Sicily alone. In view of such a statistic, Alterazioni Video opted to coin the term 'Incompiuto Siciliano' - literally 'Sicilian Incompletion' - to refer to unfinished public works as a formal architectural style. This re-interpretation, which aims to convey the recovered dignity of these 'modern ruins', considers unfinished public works a type of heritage with the potential to represent the entirety of Italian society. Furthermore, it goes as far as to say an unfinished public work is 'Incompiuto Siciliano' despite being located in another of the Italian regions. This doctoral dissertation embraces the artists' argument to develop a complete study of Incompiuto Siciliano by embedding this architectural style/artistic project within the main debates on modern ruins at present. This is important because it is expected to contribute to the revalorization and eventual recommissioning of unfinished sites by validating Incompiuto Siciliano in the realm of academia. Furthermore, this work aspires to be a worthwhile source of information for future investigations dealing with cultural interpretations of incompletion in any other context - a not unreasonable goal considering how unfinished works are one of the key urban topics after the 2008 financial crisis. Hence, this doctoral dissertation uses Incompiuto Siciliano to discuss a different perspective in each of the five chapters and, though these can be read as independent contributions, the objective is that all chapters read together, form a clear, concise, continuous unit. And so it must be said this is not a dissertation about unfinished public works in Italy; this is a dissertation about Incompiuto Siciliano as an artistic response to unfinished public works in Italy - which clearly requires an interdisciplinary analysis involving Urban Studies, Cultural Geography, Contemporary Archaeology, Critical Heritage and Visual Arts.}, subject = {Kulturerbe}, language = {en} } @phdthesis{Oroz, author = {Oroz, Gonzalo}, title = {Die Wege der Ungleichheit. Eine Studie {\"u}ber die Beziehung zwischen sozial-r{\"a}umlicher Segregation und Verkehrsinfrastruktur. Der Fall Santiago de Chile}, doi = {10.25643/bauhaus-universitaet.2924}, url = {http://nbn-resolving.de/urn:nbn:de:gbv:wim2-20170412-29244}, school = {Bauhaus-Universit{\"a}t Weimar}, pages = {353}, abstract = {Die Arbeit besch{\"a}ftigt sich mit den Auswirkungen des Baus von neuen Stadtautobahnen in Santiago de Chile. Ziel der Studie ist, die Ver{\"a}nderungen im Segregationsmuster der Hauptstadt Chiles, die durch den Bau dieser Autobahnen entstanden sind, zu beschreiben. Die Arbeit betrachtet die Entstehung von Segregationsmustern als kulturell-historisches Ph{\"a}nomen urbaner Bedeutung, weswegen die Entwicklung der Stadt Santiago und deren Segregationsmuster nicht nur aus der Perspektive der Stadtsoziologie und der Stadtgeographie, sondern auch aus einer historischen Perspektive analysiert wird. Dabei liegt der Schwerpunkt der Arbeit auf der Wechselbeziehung zwischen Verkehrsinfrastruktur und sozial-r{\"a}umlicher Verteilung der verschiedenen sozialen Gruppen. Die Entstehung der neuen Stadtautobahnen in Santiago de Chile l{\"a}sst sich nur durch eine mehrdimensionale Betrachtung erkl{\"a}ren. Diese Bauten und die besondere Art in der sie gebaut und betrieben werden, konnten nur durch die Einf{\"u}hrung von Konzessionsmechanismen innerhalb einer neoliberalen Markwirtschaft entstehen. In diesem sozial-{\"o}konomischer Rahmen, bei dem die B{\"u}rger lediglich als potenzielle Kunden betrachtet werden, sind die Infrastrukturbauten - darunter auch die Stadtautobahnen - maßgeschneiderte Produkte f{\"u}r eine Minderheit. Dieses Konzept hat gravierende Folgen f{\"u}r das Sozialgef{\"u}ge der Stadt Santiago. Die Folgen der Einf{\"u}hrung der Stadtautobahnen auf das Segregationsmuster und das Sozialgef{\"u}ge der Hauptstadt Chiles werden anhand zweier Fallstudien veranschaulicht. Mittels einer mehrschichtigen qualitativen Methodik werden die Auswirkungen des Baus von Stadtautobahnen im Armenviertel »Santo Tom{\´a}s« des s{\"u}dlichen Stadtbezirk »La Pintana« und im elit{\"a}ren »Condominio La Reserva« im n{\"o}rdlichen Ausdehnungsgebiet »Chacabuco« analysiert. Anschließend wird ein neues Beschreibungsmodell f{\"u}r die lateinamerikanische Stadt vorgeschlagen; das »symbiotische Stadtmodell« st{\"u}tzt sich zum gr{\"o}ßten Teil auf den Ausbau des Autobahnnetzes.}, subject = {Segregation}, language = {de} } @phdthesis{Conrad, author = {Conrad, Lisa}, title = {Organisation im soziotechnischen Gemenge - Mediale Umschichtungen durch die Einf{\"u}hrung von SAP}, publisher = {transcript Verlag}, address = {Bielefeld}, isbn = {978-3-8376-3784-7}, doi = {10.25643/bauhaus-universitaet.3107}, url = {http://nbn-resolving.de/urn:nbn:de:gbv:wim2-20180503-31079}, school = {Bauhaus-Universit{\"a}t Weimar}, pages = {211}, abstract = {Der Alltag in Organisationen besteht vor allem aus den Medien und Technologien, mit denen die Koordination zwischen einzelnen Arbeitsabl{\"a}ufen hergestellt wird. Diese ethnografische Studie begleitet den Prozess der Einf{\"u}hrung eines SAP-Systems in einem mittelst{\"a}ndischen Unternehmen und zeigt, wie das bestehende Geflecht aus Praktiken und Technologien eine Neuanordnung erf{\"a}hrt. Dabei tritt das komplexe soziotechnische Gemenge zutage, auf dem Koordination und Organisation beruhen. Es geht um Hardware, ebenso wie Software, um mechanische und elektronische Medien, um Papiere, Drucker, Akten, Interfaces und Tastaturen, aber auch um die jahrzehntelang eingespielten Routinen und das Erfahrungswissen der Angestellten.}, subject = {Organisationsforschung}, language = {de} }