@phdthesis{Schnoes, author = {Schn{\"o}s, Christian Emanuel}, title = {Handlungsressourcen von zivilgesellschaftlichen Akteuren in Planungsprozessen}, doi = {10.25643/bauhaus-universitaet.4634}, url = {http://nbn-resolving.de/urn:nbn:de:gbv:wim2-20220505-46346}, school = {Bauhaus-Universit{\"a}t Weimar}, pages = {273}, abstract = {Diese Dissertation untersucht Handlungsressourcen von zivilgesellschaftlichen Akteuren in Planungsprozessen um innerst{\"a}dtische Planungsverfahren. Den theoretischen Rahmen bilden die Kapitalarten von Pierre Bourdieu, die zusammen mit dem Matrixraum von Dieter L{\"a}pple zu einem neuen Feldbegriff des ‚Raumfeldes' zusammengef{\"u}hrt und operationalisiert wurden. Es handelt sich um eine qualitative Arbeit, die zwischen Stadtsoziologie und Urbanistik zu verorten ist. Als Fallbeispiele wurde die Erweiterung des Berliner Mauerparks sowie das Baugebiet „So! Berlin" in Berlin gew{\"a}hlt.}, subject = {Zivilgesellschaft}, language = {de} } @phdthesis{Torres, author = {Torres, C{\´e}sar}, title = {El paisaje de la Cuenca Lechera Central Argentina: la huella de la producci{\´o}n sobre el territorio}, doi = {10.25643/bauhaus-universitaet.4683}, url = {http://nbn-resolving.de/urn:nbn:de:gbv:wim2-20220803-46835}, school = {Bauhaus-Universit{\"a}t Weimar}, pages = {427}, abstract = {In recent times, the study of landscape heritage acquires value by virtue of becoming an alternative to rethink regional development, especially from the point of view of territorial planning. In this sense, the Central Argentine Dairy Basin (CADB) is presented as a space where the traces of different human projects have accumulated over centuries of occupation, which can be read as heritage. The impact of dairy farming and other productive activities has shaped the configuration of its landscape. The main hypothesis assumed that a cultural landscape would have been formed in the CADB, whose configuration would have depended to a great extent on the history of productive activities and their deployment over the territory, and this same history would hide the keys to its alternative. The thesis approached the object of study from descriptive and cartographic methods that placed the narration of the history of territory and the resources of the landscape as a discursive axis. A series of intentional readings of the territory and its constituent parts pondered the layers of data that have accumulated on it in the form of landscape traces, with the help of an approach from complementary dimensions (natural, sociocultural, productive, planning). Furthermore, the intersection of historical sources was used in order to allow the construction of the territorial story and the detection of the origin of the landscape components. A meticulous cartographic work also helped to spatialise the set of phenomena and elements studied, and was reflected in a multiscalar scanning.}, subject = {Landschaft}, language = {es} } @phdthesis{Zhang, author = {Zhang, Yongzheng}, title = {A Nonlocal Operator Method for Quasi-static and Dynamic Fracture Modeling}, doi = {10.25643/bauhaus-universitaet.4732}, url = {http://nbn-resolving.de/urn:nbn:de:gbv:wim2-20221026-47321}, school = {Bauhaus-Universit{\"a}t Weimar}, abstract = {Material failure can be tackled by so-called nonlocal models, which introduce an intrinsic length scale into the formulation and, in the case of material failure, restore the well-posedness of the underlying boundary value problem or initial boundary value problem. Among nonlocal models, peridynamics (PD) has attracted a lot of attention as it allows the natural transition from continuum to discontinue and thus allows modeling of discrete cracks without the need to describe and track the crack topology, which has been a major obstacle in traditional discrete crack approaches. This is achieved by replacing the divergence of the Cauchy stress tensor through an integral over so-called bond forces, which account for the interaction of particles. A quasi-continuum approach is then used to calibrate the material parameters of the bond forces, i.e., equating the PD energy with the energy of a continuum. One major issue for the application of PD to general complex problems is that they are limited to fairly simple material behavior and pure mechanical problems based on explicit time integration. PD has been extended to other applications but losing simultaneously its simplicity and ease in modeling material failure. Furthermore, conventional PD suffers from instability and hourglass modes that require stabilization. It also requires the use of constant horizon sizes, which drastically reduces its computational efficiency. The latter issue was resolved by the so-called dual-horizon peridynamics (DH-PD) formulation and the introduction of the duality of horizons. Within the nonlocal operator method (NOM), the concept of nonlocality is further extended and can be considered a generalization of DH-PD. Combined with the energy functionals of various physical models, the nonlocal forms based on the dual-support concept can be derived. In addition, the variation of the energy functional allows implicit formulations of the nonlocal theory. While traditional integral equations are formulated in an integral domain, the dual-support approaches are based on dual integral domains. One prominent feature of NOM is its compatibility with variational and weighted residual methods. The NOM yields a direct numerical implementation based on the weighted residual method for many physical problems without the need for shape functions. Only the definition of the energy or boundary value problem is needed to drastically facilitate the implementation. The nonlocal operator plays an equivalent role to the derivatives of the shape functions in meshless methods and finite element methods (FEM). Based on the variational principle, the residual and the tangent stiffness matrix can be obtained with ease by a series of matrix multiplications. In addition, NOM can be used to derive many nonlocal models in strong form. The principal contributions of this dissertation are the implementation and application of NOM, and also the development of approaches for dealing with fractures within the NOM, mostly for dynamic fractures. The primary coverage and results of the dissertation are as follows: -The first/higher-order implicit NOM and explicit NOM, including a detailed description of the implementation, are presented. The NOM is based on so-called support, dual-support, nonlocal operators, and an operate energy functional ensuring stability. The nonlocal operator is a generalization of the conventional differential operators. Combining with the method of weighted residuals and variational principles, NOM establishes the residual and tangent stiffness matrix of operate energy functional through some simple matrix without the need of shape functions as in other classical computational methods such as FEM. NOM only requires the definition of the energy drastically simplifying its implementation. For the sake of conciseness, the implementation in this chapter is focused on linear elastic solids only, though the NOM can handle more complex nonlinear problems. An explicit nonlocal operator method for the dynamic analysis of elasticity solid problems is also presented. The explicit NOM avoids the calculation of the tangent stiffness matrix as in the implicit NOM model. The explicit scheme comprises the Verlet-velocity algorithm. The NOM can be very flexible and efficient for solving partial differential equations (PDEs). It's also quite easy for readers to use the NOM and extend it to solve other complicated physical phenomena described by one or a set of PDEs. Several numerical examples are presented to show the capabilities of this method. -A nonlocal operator method for the dynamic analysis of (thin) Kirchhoff plates is proposed. The nonlocal Hessian operator is derived from a second-order Taylor series expansion. NOM is higher-order continuous, which is exploited for thin plate analysis that requires \$C^1\$ continuity. The nonlocal dynamic governing formulation and operator energy functional for Kirchhoff plates are derived from a variational principle. The Verlet-velocity algorithm is used for time discretization. After confirming the accuracy of the nonlocal Hessian operator, several numerical examples are simulated by the nonlocal dynamic Kirchhoff plate formulation. -A nonlocal fracture modeling is developed and applied to the simulation of quasi-static and dynamic fractures using the NOM. The phase field's nonlocal weak and associated strong forms are derived from a variational principle. The NOM requires only the definition of energy. We present both a nonlocal implicit phase field model and a nonlocal explicit phase field model for fracture; the first approach is better suited for quasi-static fracture problems, while the key application of the latter one is dynamic fracture. To demonstrate the performance of the underlying approach, several benchmark examples for quasi-static and dynamic fracture are solved.}, subject = {Variationsprinzip}, language = {en} } @phdthesis{Mojahedin, author = {Mojahedin, Arvin}, title = {Analysis of Functionally Graded Porous Materials Using Deep Energy Method and Analytical Solution}, doi = {10.25643/bauhaus-universitaet.4867}, url = {http://nbn-resolving.de/urn:nbn:de:gbv:wim2-20221220-48674}, school = {Bauhaus-Universit{\"a}t Weimar}, abstract = {Porous materials are an emerging branch of engineering materials that are composed of two elements: One element is a solid (matrix), and the other element is either liquid or gas. Pores can be distributed within the solid matrix of porous materials with different shapes and sizes. In addition, porous materials are lightweight, and flexible, and have higher resistance to crack propagation and specific thermal, mechanical, and magnetic properties. These properties are necessary for manufacturing engineering structures such as beams and other engineering structures. These materials are widely used in solid mechanics and are considered a good replacement for classical materials by many researchers recently. Producing lightweight materials has been developed because of the possibility of exploiting the properties of these materials. Various types of porous material are generated naturally or artificially for a specific application such as bones and foams. Like functionally graded materials, pore distribution patterns can be uniform or non-uniform. Biot's theory is a well-developed theory to study the behavior of poroelastic materials which investigates the interaction between fluid and solid phases of a fluid-saturated porous medium. Functionally graded porous materials (FGPM) are widely used in modern industries, such as aerospace, automotive, and biomechanics. These advanced materials have some specific properties compared to materials with a classic structure. They are extremely light, while they have specific strength in mechanical and high-temperature environments. FGPMs are characterized by a gradual variation of material parameters over the volume. Although these materials can be made naturally, it is possible to design and manufacture them for a specific application. Therefore, many studies have been done to analyze the mechanical and thermal properties of FGPM structures, especially beams. Biot was the pioneer in formulating the linear elasticity and thermoelasticity equations of porous material. Since then, Biot's formulation has been developed in continuum mechanics which is named poroelasticity. There are obstacles to analyzing the behavior of these materials accurately like the shape of the pores, the distribution of pores in the material, and the behavior of the fluid (or gas) that saturated pores. Indeed, most of the engineering structures made of FGPM have nonlinear governing equations. Therefore, it is difficult to study engineering structures by solving these complicated equations. The main purpose of this dissertation is to analyze porous materials in engineering structures. For this purpose, the complex equations of porous materials have been simplified and applied to engineering problems so that the effect of all parameters of porous materials on the behavior of engineering structure has been investigated. The effect of important parameters of porous materials on beam behavior including pores compressibility, porosity distribution, thermal expansion of fluid within pores, the interaction of stresses between pores and material matrix due to temperature increase, effects of pore size, material thickness, and saturated pores with fluid and unsaturated conditions are investigated. Two methods, the deep energy method, and the exact solution have been used to reduce the problem hypotheses, increase accuracy, increase processing speed, and apply these in engineering structures. In both methods, they are analyzed nonlinear and complex equations of porous materials. To increase the accuracy of analysis and study of the effect of shear forces, Timoshenko and Reddy's beam theories have been used. Also, neural networks such as residual and fully connected networks are designed to have high accuracy and less processing time than other computational methods.}, subject = {Por{\"o}ser Stoff}, language = {en} } @phdthesis{LopezZermeno, author = {L{\´o}pez Zerme{\~n}o, Jorge Alberto}, title = {Isogeometric and CAD-based methods for shape and topology optimization: Sensitivity analysis, B{\´e}zier elements and phase-field approaches}, doi = {10.25643/bauhaus-universitaet.4710}, url = {http://nbn-resolving.de/urn:nbn:de:gbv:wim2-20220831-47102}, school = {Bauhaus-Universit{\"a}t Weimar}, abstract = {The Finite Element Method (FEM) is widely used in engineering for solving Partial Differential Equations (PDEs) over complex geometries. To this end, it is required to provide the FEM software with a geometric model that is typically constructed in a Computer-Aided Design (CAD) software. However, FEM and CAD use different approaches for the mathematical description of the geometry. Thus, it is required to generate a mesh, which is suitable for FEM, based on the CAD model. Nonetheless, this procedure is not a trivial task and it can be time consuming. This issue becomes more significant for solving shape and topology optimization problems, which consist in evolving the geometry iteratively. Therefore, the computational cost associated to the mesh generation process is increased exponentially for this type of applications. The main goal of this work is to investigate the integration of CAD and CAE in shape and topology optimization. To this end, numerical tools that close the gap between design and analysis are presented. The specific objectives of this work are listed below: • Automatize the sensitivity analysis in an isogeometric framework for applications in shape optimization. Applications for linear elasticity are considered. • A methodology is developed for providing a direct link between the CAD model and the analysis mesh. In consequence, the sensitivity analysis can be performed in terms of the design variables located in the design model. • The last objective is to develop an isogeometric method for shape and topological optimization. This method should take advantage of using Non-Uniform Rational B-Splines (NURBS) with higher continuity as basis functions. Isogeometric Analysis (IGA) is a framework designed to integrate the design and analysis in engineering problems. The fundamental idea of IGA is to use the same basis functions for modeling the geometry, usually NURBS, for the approximation of the solution fields. The advantage of integrating design and analysis is two-fold. First, the analysis stage is more accurate since the system of PDEs is not solved using an approximated geometry, but the exact CAD model. Moreover, providing a direct link between the design and analysis discretizations makes possible the implementation of efficient sensitivity analysis methods. Second, the computational time is significantly reduced because the mesh generation process can be avoided. Sensitivity analysis is essential for solving optimization problems when gradient-based optimization algorithms are employed. Automatic differentiation can compute exact gradients, automatically by tracking the algebraic operations performed on the design variables. For the automation of the sensitivity analysis, an isogeometric framework is used. Here, the analysis mesh is obtained after carrying out successive refinements, while retaining the coarse geometry for the domain design. An automatic differentiation (AD) toolbox is used to perform the sensitivity analysis. The AD toolbox takes the code for computing the objective and constraint functions as input. Then, using a source code transformation approach, it outputs a code for computing the objective and constraint functions, and their sensitivities as well. The sensitivities obtained from the sensitivity propagation method are compared with analytical sensitivities, which are computed using a full isogeometric approach. The computational efficiency of AD is comparable to that of analytical sensitivities. However, the memory requirements are larger for AD. Therefore, AD is preferable if the memory requirements are satisfied. Automatic sensitivity analysis demonstrates its practicality since it simplifies the work of engineers and designers. Complex geometries with sharp edges and/or holes cannot easily be described with NURBS. One solution is the use of unstructured meshes. Simplex-elements (triangles and tetrahedra for two and three dimensions respectively) are particularly useful since they can automatically parameterize a wide variety of domains. In this regard, unstructured B{\´e}zier elements, commonly used in CAD, can be employed for the exact modelling of CAD boundary representations. In two dimensions, the domain enclosed by NURBS curves is parameterized with B{\´e}zier triangles. To describe exactly the boundary of a two-dimensional CAD model, the continuity of a NURBS boundary representation is reduced to C^0. Then, the control points are used to generate a triangulation such that the boundary of the domain is identical to the initial CAD boundary representation. Thus, a direct link between the design and analysis discretizations is provided and the sensitivities can be propagated to the design domain. In three dimensions, the initial CAD boundary representation is given as a collection of NURBS surfaces that enclose a volume. Using a mesh generator (Gmsh), a tetrahedral mesh is obtained. The original surface is reconstructed by modifying the location of the control points of the tetrahedral mesh using B{\´e}zier tetrahedral elements and a point inversion algorithm. This method offers the possibility of computing the sensitivity analysis using the analysis mesh. Then, the sensitivities can be propagated into the design discretization. To reuse the mesh originally generated, a moving B{\´e}zier tetrahedral mesh approach was implemented. A gradient-based optimization algorithm is employed together with a sensitivity propagation procedure for the shape optimization cases. The proposed shape optimization approaches are used to solve some standard benchmark problems in structural mechanics. The results obtained show that the proposed approach can compute accurate gradients and evolve the geometry towards optimal solutions. In three dimensions, the moving mesh approach results in faster convergence in terms of computational time and avoids remeshing at each optimization step. For considering topological changes in a CAD-based framework, an isogeometric phase-field based shape and topology optimization is developed. In this case, the diffuse interface of a phase-field variable over a design domain implicitly describes the boundaries of the geometry. The design variables are the local values of the phase-field variable. The descent direction to minimize the objective function is found by using the sensitivities of the objective function with respect to the design variables. The evolution of the phase-field is determined by solving the time dependent Allen-Cahn equation. Especially for topology optimization problems that require C^1 continuity, such as for flexoelectric structures, the isogeometric phase field method is of great advantage. NURBS can achieve the desired continuity more efficiently than the traditional employed functions. The robustness of the method is demonstrated when applied to different geometries, boundary conditions, and material configurations. The applications illustrate that compared to piezoelectricity, the electrical performance of flexoelectric microbeams is larger under bending. In contrast, the electrical power for a structure under compression becomes larger with piezoelectricity.}, subject = {CAD}, language = {en} } @phdthesis{Zacharias, author = {Zacharias, Christin}, title = {Numerical Simulation Models for Thermoelastic Damping Effects}, doi = {10.25643/bauhaus-universitaet.4735}, url = {http://nbn-resolving.de/urn:nbn:de:gbv:wim2-20221116-47352}, school = {Bauhaus-Universit{\"a}t Weimar}, pages = {191}, abstract = {Finite Element Simulations of dynamically excited structures are mainly influenced by the mass, stiffness, and damping properties of the system, as well as external loads. The prediction quality of dynamic simulations of vibration-sensitive components depends significantly on the use of appropriate damping models. Damping phenomena have a decisive influence on the vibration amplitude and the frequencies of the vibrating structure. However, developing realistic damping models is challenging due to the multiple sources that cause energy dissipation, such as material damping, different types of friction, or various interactions with the environment. This thesis focuses on thermoelastic damping, which is the main cause of material damping in homogeneous materials. The effect is caused by temperature changes due to mechanical strains. In vibrating structures, temperature gradients arise in adjacent tension and compression areas. Depending on the vibration frequency, they result in heat flows, leading to increased entropy and the irreversible transformation of mechanical energy into thermal energy. The central objective of this thesis is the development of efficient simulation methods to incorporate thermoelastic damping in finite element analyses based on modal superposition. The thermoelastic loss factor is derived from the structure's mechanical mode shapes and eigenfrequencies. In subsequent analyses that are performed in the time and frequency domain, it is applied as modal damping. Two approaches are developed to determine the thermoelastic loss in thin-walled plate structures, as well as three-dimensional solid structures. The realistic representation of the dissipation effects is verified by comparing the simulation results with experimentally determined data. Therefore, an experimental setup is developed to measure material damping, excluding other sources of energy dissipation. The three-dimensional solid approach is based on the determination of the generated entropy and therefore the generated heat per vibration cycle, which is a measure for thermoelastic loss in relation to the total strain energy. For thin plate structures, the amount of bending energy in a modal deformation is calculated and summarized in the so-called Modal Bending Factor (MBF). The highest amount of thermoelastic loss occurs in the state of pure bending. Therefore, the MBF enables a quantitative classification of the mode shapes concerning the thermoelastic damping potential. The results of the developed simulations are in good agreement with the experimental results and are appropriate to predict thermoelastic loss factors. Both approaches are based on modal superposition with the advantage of a high computational efficiency. Overall, the modeling of thermoelastic damping represents an important component in a comprehensive damping model, which is necessary to perform realistic simulations of vibration processes.}, subject = {Werkstoffd{\"a}mpfung}, language = {en} } @phdthesis{Liu, author = {Liu, Bokai}, title = {Stochastic multiscale modeling of polymeric nanocomposites using Data-driven techniques}, doi = {10.25643/bauhaus-universitaet.4637}, url = {http://nbn-resolving.de/urn:nbn:de:gbv:wim2-20220503-46379}, school = {Bauhaus-Universit{\"a}t Weimar}, pages = {134}, abstract = {In recent years, lightweight materials, such as polymer composite materials (PNCs) have been studied and developed due to their excellent physical and chemical properties. Structures composed of these composite materials are widely used in aerospace engineering structures, automotive components, and electrical devices. The excellent and outstanding mechanical, thermal, and electrical properties of Carbon nanotube (CNT) make it an ideal filler to strengthen polymer materials' comparable properties. The heat transfer of composite materials has very promising engineering applications in many fields, especially in electronic devices and energy storage equipment. It is essential in high-energy density systems since electronic components need heat dissipation functionality. Or in other words, in electronic devices the generated heat should ideally be dissipated by light and small heat sinks. Polymeric composites consist of fillers embedded in a polymer matrix, the first ones will significantly affect the overall (macroscopic) performance of the material. There are many common carbon-based fillers such as single-walled carbon nanotubes (SWCNT), multi-walled carbon nanotubes (MWCNT), carbon nanobuds (CNB), fullerene, and graphene. Additives inside the matrix have become a popular subject for researchers. Some extraordinary characters, such as high-performance load, lightweight design, excellent chemical resistance, easy processing, and heat transfer, make the design of polymeric nanotube composites (PNCs) flexible. Due to the reinforcing effects with different fillers on composite materials, it has a higher degree of freedom and can be designed for the structure according to specific applications' needs. As already stated, our research focus will be on SWCNT enhanced PNCs. Since experiments are timeconsuming, sometimes expensive and cannot shed light into phenomena taking place for instance at the interfaces/interphases of composites, they are often complemented through theoretical and computational analysis. While most studies are based on deterministic approaches, there is a comparatively lower number of stochastic methods accounting for uncertainties in the input parameters. In deterministic models, the output of the model is fully determined by the parameter values and the initial conditions. However, uncertainties in the input parameters such as aspect ratio, volume fraction, thermal properties of fiber and matrix need to be taken into account for reliable predictions. In this research, a stochastic multiscale method is provided to study the influence of numerous uncertain input parameters on the thermal conductivity of the composite. Therefore, a hierarchical multi-scale method based on computational homogenization is presented in to predict the macroscopic thermal conductivity based on the fine-scale structure. In order to study the inner mechanism, we use the finite element method and employ surrogate models to conduct a Global Sensitivity Analysis (GSA). The SA is performed in order to quantify the influence of the conductivity of the fiber, matrix, Kapitza resistance, volume fraction and aspect ratio on the macroscopic conductivity. Therefore, we compute first-order and total-effect sensitivity indices with different surrogate models. As stochastic multiscale models are computational expensive, surrogate approaches are commonly exploited. With the emergence of high performance computing and artificial intelligence, machine learning has become a popular modeling tool for numerous applications. Machine learning (ML) is commonly used in regression and maps data through specific rules with algorithms to build input and output models. They are particularly useful for nonlinear input-output relationships when sufficient data is available. ML has also been used in the design of new materials and multiscale analysis. For instance, Artificial neural networks and integrated learning seem to be ideally for such a task. They can theoretically simulate any non-linear relationship through the connection of neurons. Mapping relationships are employed to carry out data-driven simulations of inputs and outputs in stochastic modeling. This research aims to develop a stochastic multi-scale computational models of PNCs in heat transfer. Multi-scale stochastic modeling with uncertainty analysis and machine learning methods consist of the following components: -Uncertainty Analysis. A surrogate based global sensitivity analysis is coupled with a hierarchical multi-scale method employing computational homogenization. The effect of the conductivity of the fibers and the matrix, the Kapitza resistance, volume fraction and aspect ratio on the 'macroscopic' conductivity of the composite is systematically studied. All selected surrogate models yield consistently the conclusions that the most influential input parameters are the aspect ratio followed by the volume fraction. The Kapitza Resistance has no significant effect on the thermal conductivity of the PNCs. The most accurate surrogate model in terms of the R2 value is the moving least square (MLS). -Hybrid Machine Learning Algorithms. A combination of artificial neural network (ANN) and particle swarm optimization (PSO) is applied to estimate the relationship between variable input and output parameters. The ANN is used for modeling the composite while PSO improves the prediction performance through an optimized global minimum search. The thermal conductivity of the fibers and the matrix, the kapitza resistance, volume fraction and aspect ratio are selected as input parameters. The output is the macroscopic (homogenized) thermal conductivity of the composite. The results show that the PSO significantly improves the predictive ability of this hybrid intelligent algorithm, which outperforms traditional neural networks. -Stochastic Integrated Machine Learning. A stochastic integrated machine learning based multiscale approach for the prediction of the macroscopic thermal conductivity in PNCs is developed. Seven types of machine learning models are exploited in this research, namely Multivariate Adaptive Regression Splines (MARS), Support Vector Machine (SVM), Regression Tree (RT), Bagging Tree (Bag), Random Forest (RF), Gradient Boosting Machine (GBM) and Cubist. They are used as components of stochastic modeling to construct the relationship between the variable of the inputs' uncertainty and the macroscopic thermal conductivity of PNCs. Particle Swarm Optimization (PSO) is used for hyper-parameter tuning to find the global optimal values leading to a significant reduction in the computational cost. The advantages and disadvantages of various methods are also analyzed in terms of computing time and model complexity to finally give a recommendation for the applicability of different models.}, subject = {Polymere}, language = {en} } @phdthesis{Habtemariam, author = {Habtemariam, Abinet Kifle}, title = {Generalized Beam Theory for the analysis of thin-walled circular pipe members}, doi = {10.25643/bauhaus-universitaet.4572}, url = {http://nbn-resolving.de/urn:nbn:de:gbv:wim2-20220127-45723}, school = {Bauhaus-Universit{\"a}t Weimar}, pages = {188}, abstract = {The detailed structural analysis of thin-walled circular pipe members often requires the use of a shell or solid-based finite element method. Although these methods provide a very good approximation of the deformations, they require a higher degree of discretization which causes high computational costs. On the other hand, the analysis of thin-walled circular pipe members based on classical beam theories is easy to implement and needs much less computation time, however, they are limited in their ability to approximate the deformations as they cannot consider the deformation of the cross-section. This dissertation focuses on the study of the Generalized Beam Theory (GBT) which is both accurate and efficient in analyzing thin-walled members. This theory is based on the separation of variables in which the displacement field is expressed as a combination of predetermined deformation modes related to the cross-section, and unknown amplitude functions defined on the beam's longitudinal axis. Although the GBT was initially developed for long straight members, through the consideration of complementary deformation modes, which amend the null transverse and shear membrane strain assumptions of the classical GBT, problems involving short members, pipe bends, and geometrical nonlinearity can also be analyzed using GBT. In this dissertation, the GBT formulation for the analysis of these problems is developed and the application and capabilities of the method are illustrated using several numerical examples. Furthermore, the displacement and stress field results of these examples are verified using an equivalent refined shell-based finite element model. The developed static and dynamic GBT formulations for curved thin-walled circular pipes are based on the linear kinematic description of the curved shell theory. In these formulations, the complex problem in pipe bends due to the strong coupling effect of the longitudinal bending, warping and the cross-sectional ovalization is handled precisely through the derivation of the coupling tensors between the considered GBT deformation modes. Similarly, the geometrically nonlinear GBT analysis is formulated for thin-walled circular pipes based on the nonlinear membrane kinematic equations. Here, the initial linear and quadratic stress and displacement tangent stiffness matrices are built using the third and fourth-order GBT deformation mode coupling tensors. Longitudinally, the formulation of the coupled GBT element stiffness and mass matrices are presented using a beam-based finite element formulation. Furthermore, the formulated GBT elements are tested for shear and membrane locking problems and the limitations of the formulations regarding the membrane locking problem are discussed.}, subject = {Finite-Elemente-Methode}, language = {en} } @phdthesis{Valizadeh, author = {Valizadeh, Navid}, title = {Developments in Isogeometric Analysis and Application to High-Order Phase-Field Models of Biomembranes}, doi = {10.25643/bauhaus-universitaet.4565}, url = {http://nbn-resolving.de/urn:nbn:de:gbv:wim2-20220114-45658}, school = {Bauhaus-Universit{\"a}t Weimar}, abstract = {Isogeometric analysis (IGA) is a numerical method for solving partial differential equations (PDEs), which was introduced with the aim of integrating finite element analysis with computer-aided design systems. The main idea of the method is to use the same spline basis functions which describe the geometry in CAD systems for the approximation of solution fields in the finite element method (FEM). Originally, NURBS which is a standard technology employed in CAD systems was adopted as basis functions in IGA but there were several variants of IGA using other technologies such as T-splines, PHT splines, and subdivision surfaces as basis functions. In general, IGA offers two key advantages over classical FEM: (i) by describing the CAD geometry exactly using smooth, high-order spline functions, the mesh generation process is simplified and the interoperability between CAD and FEM is improved, (ii) IGA can be viewed as a high-order finite element method which offers basis functions with high inter-element continuity and therefore can provide a primal variational formulation of high-order PDEs in a straightforward fashion. The main goal of this thesis is to further advance isogeometric analysis by exploiting these major advantages, namely precise geometric modeling and the use of smooth high-order splines as basis functions, and develop robust computational methods for problems with complex geometry and/or complex multi-physics. As the first contribution of this thesis, we leverage the precise geometric modeling of isogeometric analysis and propose a new method for its coupling with meshfree discretizations. We exploit the strengths of both methods by using IGA to provide a smooth, geometrically-exact surface discretization of the problem domain boundary, while the Reproducing Kernel Particle Method (RKPM) discretization is used to provide the volumetric discretization of the domain interior. The coupling strategy is based upon the higher-order consistency or reproducing conditions that are directly imposed in the physical domain. The resulting coupled method enjoys several favorable features: (i) it preserves the geometric exactness of IGA, (ii) it circumvents the need for global volumetric parameterization of the problem domain, (iii) it achieves arbitrary-order approximation accuracy while preserving higher-order smoothness of the discretization. Several numerical examples are solved to show the optimal convergence properties of the coupled IGA-RKPM formulation, and to demonstrate its effectiveness in constructing volumetric discretizations for complex-geometry objects. As for the next contribution, we exploit the use of smooth, high-order spline basis functions in IGA to solve high-order surface PDEs governing the morphological evolution of vesicles. These governing equations are often consisted of geometric PDEs, high-order PDEs on stationary or evolving surfaces, or a combination of them. We propose an isogeometric formulation for solving these PDEs. In the context of geometric PDEs, we consider phase-field approximations of mean curvature flow and Willmore flow problems and numerically study the convergence behavior of isogeometric analysis for these problems. As a model problem for high-order PDEs on stationary surfaces, we consider the Cahn-Hilliard equation on a sphere, where the surface is modeled using a phase-field approach. As for the high-order PDEs on evolving surfaces, a phase-field model of a deforming multi-component vesicle, which consists of two fourth-order nonlinear PDEs, is solved using the isogeometric analysis in a primal variational framework. Through several numerical examples in 2D, 3D and axisymmetric 3D settings, we show the robustness of IGA for solving the considered phase-field models. Finally, we present a monolithic, implicit formulation based on isogeometric analysis and generalized-alpha time integration for simulating hydrodynamics of vesicles according to a phase-field model. Compared to earlier works, the number of equations of the phase-field model which need to be solved is reduced by leveraging high continuity of NURBS functions, and the algorithm is extended to 3D settings. We use residual-based variational multi-scale method (RBVMS) for solving Navier-Stokes equations, while the rest of PDEs in the phase-field model are treated using a standard Galerkin-based IGA. We introduce the resistive immersed surface (RIS) method into the formulation which can be employed for an implicit description of complex geometries using a diffuse-interface approach. The implementation highlights the robustness of the RBVMS method for Navier-Stokes equations of incompressible flows with non-trivial localized forcing terms including bending and tension forces of the vesicle. The potential of the phase-field model and isogeometric analysis for accurate simulation of a variety of fluid-vesicle interaction problems in 2D and 3D is demonstrated.}, subject = {Phasenfeldmodell}, language = {en} } @phdthesis{ShaabanMohamed, author = {Shaaban Mohamed, Ahmed Mostafa}, title = {Isogeometric boundary element analysis and structural shape optimization for Helmholtz acoustic problems}, doi = {10.25643/bauhaus-universitaet.4703}, url = {http://nbn-resolving.de/urn:nbn:de:gbv:wim2-20220816-47030}, school = {Bauhaus-Universit{\"a}t Weimar}, abstract = {In this thesis, a new approach is developed for applications of shape optimization on the time harmonic wave propagation (Helmholtz equation) for acoustic problems. This approach is introduced for different dimensional problems: 2D, 3D axi-symmetric and fully 3D problems. The boundary element method (BEM) is coupled with the isogeometric analysis (IGA) forming the so-called (IGABEM) which speeds up meshing and gives higher accuracy in comparison with standard BEM. BEM is superior for handling unbounded domains by modeling only the inner boundaries and avoiding the truncation error, present in the finite element method (FEM) since BEM solutions satisfy the Sommerfeld radiation condition automatically. Moreover, BEM reduces the space dimension by one from a volumetric three-dimensional problem to a surface two-dimensional problem, or from a surface two-dimensional problem to a perimeter one-dimensional problem. Non-uniform rational B-splines basis functions (NURBS) are used in an isogeometric setting to describe both the CAD geometries and the physical fields. IGABEM is coupled with one of the gradient-free optimization methods, the Particle Swarm Optimization (PSO) for structural shape optimization problems. PSO is a straightforward method since it does not require any sensitivity analysis but it has some trade-offs with regard to the computational cost. Coupling IGA with optimization problems enables the NURBS basis functions to represent the three models: shape design, analysis and optimization models, by a definition of a set of control points to be the control variables and the optimization parameters as well which enables an easy transition between the three models. Acoustic shape optimization for various frequencies in different mediums is performed with PSO and the results are compared with the benchmark solutions from the literature for different dimensional problems proving the efficiency of the proposed approach with the following remarks: - In 2D problems, two BEM methods are used: the conventional isogeometric boundary element method (IGABEM) and the eXtended IGABEM (XIBEM) enriched with the partition-of-unity expansion using a set of plane waves, where the results are generally in good agreement with the linterature with some computation advantage to XIBEM which allows coarser meshes. -In 3D axi-symmetric problems, the three-dimensional problem is simplified in BEM from a surface integral to a combination of two 1D integrals. The first is the line integral similar to a two-dimensional BEM problem. The second integral is performed over the angle of revolution. The discretization is applied only to the former integration. This leads to significant computational savings and, consequently, better treatment for higher frequencies over the full three-dimensional models. - In fully 3D problems, a detailed comparison between two BEM methods: the conventional boundary integral equation (CBIE) and Burton-Miller (BM) is provided including the computational cost. The proposed models are enhanced with a modified collocation scheme with offsets to Greville abscissae to avoid placing collocation points at the corners. Placing collocation points on smooth surface enables accurate evaluation of normals for BM formulation in addition to straightforward prediction of jump-terms and avoids singularities in \$\mathcal{O} (1/r)\$ integrals eliminating the need for polar integration. Furthermore, no additional special treatment is required for the hyper-singular integral while collocating on highly distorted elements, such as those containing sphere poles. The obtained results indicate that, CBIE with PSO is a feasible alternative (except for a small number of fictitious frequencies) which is easier to implement. Furthermore, BM presents an outstanding treatment of the complicated geometry of mufflers with internal extended inlet/outlet tube as an interior 3D Helmholtz acoustic problem instead of using mixed or dual BEM.}, subject = {Randelemente-Methode}, language = {en} } @phdthesis{Harirchian, author = {Harirchian, Ehsan}, title = {Improved Rapid Assessment of Earthquake Hazard Safety of Existing Buildings Using a Hierarchical Type-2 Fuzzy Logic Model}, doi = {10.25643/bauhaus-universitaet.4396}, url = {http://nbn-resolving.de/urn:nbn:de:gbv:wim2-20210326-43963}, school = {Bauhaus-Universit{\"a}t Weimar}, pages = {143}, abstract = {Although it is impractical to avert subsequent natural disasters, advances in simulation science and seismological studies make it possible to lessen the catastrophic damage. There currently exists in many urban areas a large number of structures, which are prone to damage by earthquakes. These were constructed without the guidance of a national seismic code, either before it existed or before it was enforced. For instance, in Istanbul, Turkey, as a high seismic area, around 90\% of buildings are substandard, which can be generalized into other earthquakeprone regions in Turkey. The reliability of this building stock resulting from earthquake-induced collapse is currently uncertain. Nonetheless, it is also not feasible to perform a detailed seismic vulnerability analysis on each building as a solution to the scenario, as it will be too complicated and expensive. This indicates the necessity of a reliable, rapid, and computationally easy method for seismic vulnerability assessment, commonly known as Rapid Visual Screening (RVS). In RVS methodology, an observational survey of buildings is performed, and according to the data collected during the visual inspection, a structural score is calculated without performing any structural calculations to determine the expected damage of a building and whether the building needs detailed assessment. Although this method might save time and resources due to the subjective/qualitative judgments of experts who performed the inspection, the evaluation process is dominated by vagueness and uncertainties, where the vagueness can be handled adequately through the fuzzy set theory but do not cover all sort of uncertainties due to its crisp membership functions. In this study, a novel method of rapid visual hazard safety assessment of buildings against earthquake is introduced in which an interval type-2 fuzzy logic system (IT2FLS) is used to cover uncertainties. In addition, the proposed method provides the possibility to evaluate the earthquake risk of the building by considering factors related to the building importance and exposure. A smartphone app prototype of the method has been introduced. For validation of the proposed method, two case studies have been selected, and the result of the analysis presents the robust efficiency of the proposed method.}, subject = {Fuzzy-Logik}, language = {en} } @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{Weissker, author = {Weißker, Tim}, title = {Group Navigation in Multi-User Virtual Reality}, doi = {10.25643/bauhaus-universitaet.4530}, url = {http://nbn-resolving.de/urn:nbn:de:gbv:wim2-20211124-45305}, school = {Bauhaus-Universit{\"a}t Weimar}, pages = {148}, abstract = {Multi-user virtual reality systems enable collocated as well as distributed users to perform collaborative activities in immersive virtual environments. A common activity in this context is to move from one location to the next as a group to explore the environment together. The simplest solution to realize these multi-user navigation processes is to provide each participant with a technique for individual navigation. However, this approach entails some potentially undesirable consequences such as the execution of a similar navigation sequence by each participant, a regular need for coordination within the group, and, related to this, the risk of losing each other during the navigation process. To overcome these issues, this thesis performs research on group navigation techniques that move group members together through a virtual environment. The presented work was guided by four overarching research questions that address the quality requirements for group navigation techniques, the differences between collocated and distributed settings, the scalability of group navigation, and the suitability of individual and group navigation for various scenarios. This thesis approaches these questions by introducing a general conceptual framework as well as the specification of central requirements for the design of group navigation techniques. The design, implementation, and evaluation of corresponding group navigation techniques demonstrate the applicability of the proposed framework. As a first step, this thesis presents ideas for the extension of the short-range teleportation metaphor, also termed jumping, for multiple users. It derives general quality requirements for the comprehensibility of the group jumping process and introduces a corresponding technique for two collocated users. The results of two user studies indicate that sickness symptoms are not affected by user roles during group jumping and confirm improved planning accuracy for the navigator, increased spatial awareness for the passenger, and reduced cognitive load for both user roles. Next, this thesis explores the design space of group navigation techniques in distributed virtual environments. It presents a conceptual framework to systematize the design decisions for group navigation techniques based on Tuckman's model of small-group development and introduces the idea of virtual formation adjustments as part of the navigation process. A quantitative user study demonstrates that the corresponding extension of Multi-Ray Jumping for distributed dyads leads to more efficient travel sequences and reduced workload. The results of a qualitative expert review confirm these findings and provide further insights regarding the complementarity of individual and group navigation in distributed virtual environments. Then, this thesis investigates the navigation of larger groups of distributed users in the context of guided museum tours and establishes three central requirements for (scalable) group navigation techniques. These should foster the awareness of ongoing navigation activities as well as facilitate the predictability of their consequences for all group members (Comprehensibility), assist the group with avoiding collisions in the virtual environment (Obstacle Avoidance), and support placing the group in a meaningful spatial formation for the joint observation and discussion of objects (View Optimization). The work suggests a new technique to address these requirements and reports on its evaluation in an initial usability study with groups of five to ten (partially simulated) users. The results indicate easy learnability for navigators and high comprehensibility for passengers. Moreover, they also provide valuable insights for the development of group navigation techniques for even larger groups. Finally, this thesis embeds the previous contributions in a comprehensive literature overview and emphasizes the need to study larger, more heterogeneous, and more diverse group compositions including the related social factors that affect group dynamics. In summary, the four major research contributions of this thesis are as follows: - the framing of group navigation as a specific instance of Tuckman's model of small-group development - the derivation of central requirements for effective group navigation techniques beyond common quality factors known from single-user navigation - the introduction of virtual formation adjustments during group navigation and their integration into concrete group navigation techniques - evidence that appropriate pre-travel information and virtual formation adjustments lead to more efficient travel sequences for groups and lower workloads for both navigators and passengers Overall, the research of this thesis confirms that group navigation techniques are a valuable addition to the portfolio of interaction techniques in multi-user virtual reality systems. The conceptual framework, the derived quality requirements, and the development of novel group navigation techniques provide effective guidance for application developers and inform future research in this area.}, 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{Mauludin, author = {Mauludin, Luthfi Muhammad}, title = {Computational Modeling of Fracture in Encapsulation-Based Self-Healing Concrete Using Cohesive Elements}, doi = {10.25643/bauhaus-universitaet.4520}, url = {http://nbn-resolving.de/urn:nbn:de:gbv:wim2-20211008-45204}, school = {Bauhaus-Universit{\"a}t Weimar}, pages = {170}, abstract = {Encapsulation-based self-healing concrete has received a lot of attention nowadays in civil engineering field. These capsules are embedded in the cementitious matrix during concrete mixing. When the cracks appear, the embedded capsules which are placed along the path of incoming crack are fractured and then release of healing agents in the vicinity of damage. The materials of capsules need to be designed in a way that they should be able to break with small deformation, so the internal fluid can be released to seal the crack. This study focuses on computational modeling of fracture in encapsulation-based selfhealing concrete. The numerical model of 2D and 3D with randomly packed aggreates and capsules have been developed to analyze fracture mechanism that plays a significant role in the fracture probability of capsules and consequently the self-healing process. The capsules are assumed to be made of Poly Methyl Methacrylate (PMMA) and the potential cracks are represented by pre-inserted cohesive elements with tension and shear softening laws along the element boundaries of the mortar matrix, aggregates, capsules, and at the interfaces between these phases. The effects of volume fraction, core-wall thickness ratio, and mismatch fracture properties of capsules on the load carrying capacity of self-healing concrete and fracture probability of the capsules are investigated. The output of this study will become valuable tool to assist not only the experimentalists but also the manufacturers in designing an appropriate capsule material for self-healing concrete.}, subject = {beton}, language = {en} } @phdthesis{Stang, author = {Stang, Ren{\´e}}, title = {Methode zur {\"O}koeffizienzbewertung w{\"a}rmetechnischer Anlagen in Geb{\"a}uden}, publisher = {VDI Verlag}, address = {D{\"u}sseldorf}, isbn = {978-3-18-300623-6 (print)}, doi = {10.25643/bauhaus-universitaet.4528}, url = {http://nbn-resolving.de/urn:nbn:de:gbv:wim2-20211119-45280}, school = {Bauhaus-Universit{\"a}t Weimar}, pages = {222}, abstract = {Die vorliegende Arbeit richtet sich an Ingenieur*innen und Wissenschaftler*innen der technischen Geb{\"a}udeausr{\"u}stung. Sie greift einen sich abzeichnenden {\"A}nderungsbedarf in der Umwelt- und Nachhaltigkeitsbewertung von Geb{\"a}uden und w{\"a}rmetechnischen Anlagen auf. Der aktuell genutzte nicht erneuerbare Prim{\"a}renergiebedarf wird insbesondere hinsichtlich k{\"u}nftiger politischer Klima- und Umweltschutzziele als alleinige Bewertungsgr{\"o}ße nicht ausreichend sein. Die mit dieser Arbeit vorgestellte {\"O}koeffizienzbewertungsmethode kann als geeignetes Instrument zur L{\"o}sung der Probleme beitragen. Sie erm{\"o}glicht systematische, ganzheitliche Bewertungen und reproduzierbare Vergleiche w{\"a}rmetechnischer Anlagen bez{\"u}glich ihrer {\"o}kologischen und {\"o}konomischen Nachhaltigkeit. Die wesentlichsten Neuentwicklungen sind die spezifische Umweltleistung, in Erweiterung zum genutzten Prim{\"a}renergiefaktor, und der {\"O}koeffizienzindikator UWI.}, subject = {Energiewirtschaft}, language = {de} } @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{Bockelmann, author = {Bockelmann, Leo}, title = {Zeit, dass sich was dreht. Windenergieanlagen aus denkmalkundlicher Perspektive}, doi = {10.25643/bauhaus-universitaet.4543}, url = {http://nbn-resolving.de/urn:nbn:de:gbv:wim2-20211210-45439}, school = {Bauhaus-Universit{\"a}t Weimar}, pages = {233}, abstract = {Knapp 30.000 Windenergieanlagen zwischen Nordsee und Alpen lassen un{\"u}bersehbar erkennen, dass sich unser Energiesystem in einer umfassenden Transformation befindet. Allenthalben erf{\"a}hrt diese Entwicklung eine breite und kontroverse Rezeption und auch in der Denkmalpflege werden Windenergieanlagen aufgrund ihrer mitunter erheblichen Auswirkungen auf die Landschaft noch {\"u}berwiegend als St{\"o}rung wahrgenommen. Diese Arbeit nimmt dagegen die historische Entwicklung in den Blick und pl{\"a}diert daf{\"u}r, Windenergieanlagen als bedeutendes Kulturerbe zu verstehen. Angesichts des Voranschreitens der Energiewende wird angenommen, dass gerade {\"a}lteren Modellen als baulichen Zeugnissen umfangreicher energiepolitischer Ver{\"a}nderungen seit den 1970er Jahren eine hohe Bedeutung zugeschrieben werden kann. Daher besteht das Ziel darin, Windenergieanlagen herauszuarbeiten, welche als hervorragende Zeugnisse der Entwicklung der Windenergienutzung in Deutschland zu bewerten sind. Zur Ann{\"a}herung werden diese zun{\"a}chst als Untersuchungsgegenstand typologisch abgegrenzt. Eine wesentliche Besonderheit von Windenergieanlagen besteht darin, dass sie im Verh{\"a}ltnis zur eigentlichen Fl{\"a}chenversiegelung durch ihre vertikale Struktur erhebliche visuelle Auswirkungen auf die Landschaft haben. Anschließend wird die Entwicklung der Windenergienutzung seit den 1970er Jahren genauer betrachtet, welche insgesamt nicht linear verlief und von vielen Konflikten gekennzeichnet ist. Diese muss im Kontext eines wachsenden Umweltbewusstseins verstanden werden, das umfangreiche energiepolitische Ver{\"a}nderungen zur Folge hatte. Auf dieser Grundlage werden schließlich in einer denkmalkundlichen Reihenuntersuchung Windenergieanlagen herausgearbeitet, welche in hervorragender Weise von der Entwicklung zeugen. Die Auswahl bleibt allerdings mit sechs Objekten im Verh{\"a}ltnis zum Gesamtbestand von knapp 30.000 Anlagen relativ beschr{\"a}nkt, weil das auf die Abgrenzung von Besonderheiten ausgelegte etablierte Denkmalverst{\"a}ndnis bei einem zeitlich so dichten Bestand gleichartiger Bauwerke an eine Grenze kommt. Abschließend werden m{\"o}gliche Erhaltungsperspektiven sowie denkmaltheoretische und -praktische Schlussfolgerungen diskutiert. Dabei ist unbedingt ein Erhalt am Ursprungsstandort anzustreben, wobei im Einzelfall entschieden werden muss, ob Belange des Funktions- oder Substanzerhaltes h{\"o}her zu gewichten sind. Die skizzierten Auswahlprobleme regen dar{\"u}ber hinaus zur Diskussion zus{\"a}tzlicher denkbarer Bewertungskategorien an, wobei sich insbesondere die gesellschaftliche Wahrnehmung und {\"o}kologische Werte aufdr{\"a}ngen. Zudem kann f{\"u}r die st{\"a}rkere Ber{\"u}cksichtigung von Funktionszusammenh{\"a}ngen bei der Betrachtung technischer Infrastruktur in der Denkmalpflege pl{\"a}diert werden. Insgesamt f{\"u}hrt die denkmalkundliche Auseinandersetzung mit Windenergieanlagen damit weit {\"u}ber die Herausarbeitung einzelner Objekte hinaus und macht eindr{\"u}cklich auf aktuelle Herausforderungen der Denkmalpflege und dar{\"u}ber hinaus aufmerksam.}, subject = {Industriekultur}, language = {de} } @phdthesis{Ren, author = {Ren, Huilong}, title = {Dual-horizon peridynamics and Nonlocal operator method}, doi = {10.25643/bauhaus-universitaet.4403}, url = {http://nbn-resolving.de/urn:nbn:de:gbv:wim2-20210412-44039}, school = {Bauhaus-Universit{\"a}t Weimar}, pages = {223}, abstract = {In the last two decades, Peridynamics (PD) attracts much attention in the field of fracture mechanics. One key feature of PD is the nonlocality, which is quite different from the ideas in conventional methods such as FEM and meshless method. However, conventional PD suffers from problems such as constant horizon, explicit algorithm, hourglass mode. In this thesis, by examining the nonlocality with scrutiny, we proposed several new concepts such as dual-horizon (DH) in PD, dual-support (DS) in smoothed particle hydrodynamics (SPH), nonlocal operators and operator energy functional. The conventional PD (SPH) is incorporated in the DH-PD (DS-SPH), which can adopt an inhomogeneous discretization and inhomogeneous support domains. The DH-PD (DS-SPH) can be viewed as some fundamental improvement on the conventional PD (SPH). Dual formulation of PD and SPH allows h-adaptivity while satisfying the conservations of linear momentum, angular momentum and energy. By developing the concept of nonlocality further, we introduced the nonlocal operator method as a generalization of DH-PD. Combined with energy functional of various physical models, the nonlocal forms based on dual-support concept are derived. In addition, the variation of the energy functional allows implicit formulation of the nonlocal theory. At last, we developed the higher order nonlocal operator method which is capable of solving higher order partial differential equations on arbitrary domain in higher dimensional space. Since the concepts are developed gradually, we described our findings chronologically. In chapter 2, we developed a DH-PD formulation that includes varying horizon sizes and solves the "ghost force" issue. The concept of dual-horizon considers the unbalanced interactions between the particles with different horizon sizes. The present formulation fulfills both the balances of linear momentum and angular momentum exactly with arbitrary particle discretization. All three peridynamic formulations, namely bond based, ordinary state based and non-ordinary state based peridynamics can be implemented within the DH-PD framework. A simple adaptive refinement procedure (h-adaptivity) is proposed reducing the computational cost. Both two- and three- dimensional examples including the Kalthoff-Winkler experiment and plate with branching cracks are tested to demonstrate the capability of the method. In chapter 3, a nonlocal operator method (NOM) based on the variational principle is proposed for the solution of waveguide problem in computational electromagnetic field. Common differential operators as well as the variational forms are defined within the context of nonlocal operators. The present nonlocal formulation allows the assembling of the tangent stiffness matrix with ease, which is necessary for the eigenvalue analysis of the waveguide problem. The present formulation is applied to solve 1D Schrodinger equation, 2D electrostatic problem and the differential electromagnetic vector wave equations based on electric fields. In chapter 4, a general nonlocal operator method is proposed which is applicable for solving partial differential equations (PDEs) of mechanical problems. The nonlocal operator can be regarded as the integral form, ``equivalent'' to the differential form in the sense of a nonlocal interaction model. The variation of a nonlocal operator plays an equivalent role as the derivatives of the shape functions in the meshless methods or those of the finite element method. Based on the variational principle, the residual and the tangent stiffness matrix can be obtained with ease. The nonlocal operator method is enhanced here also with an operator energy functional to satisfy the linear consistency of the field. A highlight of the present method is the functional derived based on the nonlocal operator can convert the construction of residual and stiffness matrix into a series of matrix multiplications using the predefined nonlocal operators. The nonlocal strong forms of different functionals can be obtained easily via the concept of support and dual-support. Several numerical examples of different types of PDEs are presented. In chapter 5, we extended the NOM to higher order scheme by using a higher order Taylor series expansion of the unknown field. Such a higher order scheme improves the original NOM in chapter 3 and chapter 4, which can only achieve one-order convergence. The higher order NOM obtains all partial derivatives with specified maximal order simultaneously without resorting to shape functions. The functional based on the nonlocal operators converts the construction of residual and stiffness matrix into a series of matrix multiplication on the nonlocal operator matrix. Several numerical examples solved by strong form or weak form are presented to show the capabilities of this method. In chapter 6, the NOM proposed as a particle-based method in chapter 3,4,5, has difficulty in imposing accurately the boundary conditions of various orders. In this paper, we converted the particle-based NOM into a scheme with interpolation property. The new scheme describes partial derivatives of various orders at a point by the nodes in the support and takes advantage of the background mesh for numerical integration. The boundary conditions are enforced via the modified variational principle. The particle-based NOM can be viewed a special case of NOM with interpolation property when nodal integration is used. The scheme based on numerical integration greatly improves the stability of the method, as a consequence, the operator energy functional in particle-based NOM is not required. We demonstrated the capabilities of current method by solving the gradient solid problems and comparing the numerical results with the available exact solutions. In chapter 7, we derived the DS-SPH in solid within the framework of variational principle. The tangent stiffness matrix of SPH can be obtained with ease, and can be served as the basis for the present implicit SPH. We proposed an hourglass energy functional, which allows the direct derivation of hourglass force and hourglass tangent stiffness matrix. The dual-support is {involved} in all derivations based on variational principles and is automatically satisfied in the assembling of stiffness matrix. The implementation of stiffness matrix comprises with two steps, the nodal assembly based on deformation gradient and global assembly on all nodes. Several numerical examples are presented to validate the method.}, subject = {Peridynamik}, language = {en} } @phdthesis{Mueller, author = {M{\"u}ller, Matthias}, title = {Frost-Tausalz-Angriff auf Beton - Neue Erkenntnisse zum Schadensmechanismus}, doi = {10.25643/bauhaus-universitaet.4502}, url = {http://nbn-resolving.de/urn:nbn:de:gbv:wim2-20210922-45025}, school = {Bauhaus-Universit{\"a}t Weimar}, pages = {226}, abstract = {F{\"u}r die Verminderung der betonspezifischen CO2-Emissionen wird ein verst{\"a}rkter Einsatz klinkerreduzierter Zemente bzw. Betone angestrebt. Die Reduzierung des Klinkergehaltes darf jedoch nicht zu einer lebensdauerrelevanten Beeintr{\"a}chtigung der Betondauerhaftigkeit f{\"u}hren. In diesem Zusammenhang stellt der Frost-Tausalz-Widerstand eine kritische Gr{\"o}ße dar, da er bei h{\"o}heren Klinkersubstitutionsraten h{\"a}ufig negativ beeinflusst wird. Erschwerend kommt hinzu, dass f{\"u}r klinkerreduzierte Betone nur ein unzureichender Erfahrungsschatz vorliegt. Ein hoher Frost-Tausalz-Widerstand kann daher nicht ausschließlich anhand deskriptiver Vorgaben gew{\"a}hrleistet werden. Demgem{\"a}ß sollte perspektivisch auch f{\"u}r frost-tausalzbeanspruchte Bauteile eine performancebasierte Lebensdauerbetrachtung erfolgen. Eine unverzichtbare Grundlage f{\"u}r das Erreichen dieser Ziele ist ein Verst{\"a}ndnis f{\"u}r die Schadensvorg{\"a}nge beim Frost-Tausalz-Angriff. Der Forschungsstand ist jedoch gepr{\"a}gt von widerspr{\"u}chlichen Schadenstheorien. Somit wurde als Zielstellung f{\"u}r diese Arbeit abgeleitet, die existierenden Schadenstheorien unter Ber{\"u}cksichtigung des aktuellen Wissensstandes zu bewerten und mit eigenen Untersuchungen zu pr{\"u}fen und einzuordnen. Die Sichtung des Forschungsstandes zeigte, dass nur zwei Theorien das Potential haben, den Frost-Tausalz-Angriff umfassend abzubilden - die Glue Spall Theorie und die Cryogenic Suction Theorie. Die Glue Spall Theorie f{\"u}hrt die Entstehung von Abwitterungen auf die mechanische Sch{\"a}digung der Betonoberfl{\"a}che durch eine anhaftende Eisschicht zur{\"u}ck. Dabei sollen nur bei moderaten Tausalzkonzentrationen in der einwirkenden L{\"o}sung kritische Spannungszust{\"a}nde in der Eisschicht auftreten, die eine Sch{\"a}digung der Betonoberfl{\"a}che hervorrufen k{\"o}nnen. In dieser Arbeit konnte jedoch nachgewiesen werden, dass starke Abwitterungen auch bei Tausalz¬konzentrationen auftreten, bei denen eine mechanische Sch{\"a}digung des Betons durch das Eis auszuschließen ist. Damit wurde die fehlende Eignung der Glue Spall Theorie aufgezeigt. Die Cryogenic Suction Theorie fußt auf den eutektischen Eigenschaften von Tausalz-l{\"o}sungen, die im gefrorenen Zustand immer als Mischung auf festem Wassereis und fl{\"u}ssiger, hochkonzentrierter Salzl{\"o}sung bestehen, solange ihre Eutektikumstemperatur nicht unter¬schritten wird. Die fl{\"u}ssige Phase im salzhaltigen Eis stellt f{\"u}r gefrorenen Beton ein bisher nicht ber{\"u}cksichtigtes Fl{\"u}ssigkeitsreservoir dar, welches trotz der hohen Salzkonzentration die Eisbildung in der Betonrandzone verst{\"a}rken und so die Entstehung von Abwitterungen verursachen soll. In dieser Arbeit wurde best{\"a}tigt, dass die Eisbildung im Zementstein beim Gefrieren in hochkonzentrierter Tausalzl{\"o}sung tats{\"a}chlich verst{\"a}rkt wird. Das Ausmaß der zus{\"a}tzlichen Eisbildung wurde dabei auch von der F{\"a}higkeit des Zementsteins zur Bindung von Chloridionen aus der Tausalzl{\"o}sung beeinflusst. Zusammenfassend wurde festgestellt, dass die Cryogenic Suction Theorie eine gute Beschreibung des Frost-Tausalz-Angriffes darstellt, aber um weitere Aspekte erg{\"a}nzt werden muss. Die Ber{\"u}cksichtigung der intensiven S{\"a}ttigung von Beton durch den Prozess der Mikroeislinsenpumpe stellt hier die wichtigste Erweiterung dar. Basierend auf dieser {\"U}berlegung wurde eine kombinierte Schadenstheorie aufgestellt. Wichtige Annahmen dieser Theorie konnten experimentell best{\"a}tigt werden. Im Ergebnis wurde so die Grundlage f{\"u}r ein tiefergehendes Verst{\"a}ndnis des Frost-Tausalz-Angriffes geschaffen. Zudem wurde ein neuer Ansatz identifiziert, um die (potentielle) Verringerung des Frost-Tausalz-Widerstandes klinkerreduzierter Betone zu erkl{\"a}ren.}, subject = {Beton}, language = {de} } @phdthesis{Fauth, author = {Fauth, Judith}, title = {Ein handlungsorientiertes Entscheidungsmodell zur Feststellung der Genehmigungsf{\"a}higkeit von Bauvorhaben}, publisher = {Bauhaus-Universit{\"a}tsverlag}, address = {Ilmtal-Weinstraße}, isbn = {978-3-95773-299-6}, doi = {10.25643/bauhaus-universitaet.4509}, url = {http://nbn-resolving.de/urn:nbn:de:gbv:wim2-20210928-45093}, school = {Bauhaus-Universit{\"a}t Weimar}, pages = {318}, abstract = {Die Auseinandersetzung mit der Digitalisierung ist in den letzten Jahren in den Medien, auf Konferenzen und in Aussch{\"u}ssen der Bau- und Immobilienbranche angekommen. W{\"a}hrend manche Bereiche Neuerungen hervorbringen und einige Akteure als Pioniere zu bezeichnen sind, weisen andere Themen noch Defizite hinsichtlich der digitalen Transformation auf. Zu dieser Kategorie kann auch das Baugenehmigungsverfahren gez{\"a}hlt werden. Unabh{\"a}ngig davon, wie Architekten und Ingenieure in den Planungsb{\"u}ros auf innovative Methoden setzen, bleiben die Bauvorlagen bisher zuhauf in Papierform oder werden nach der elektronischen Einreichung in der Beh{\"o}rde ausgedruckt. Vorhandene Ressourcen, beispielsweise in Form eines Bauwerksinformationsmodells, die Unterst{\"u}tzung bei der Baugenehmigungsfeststellung bieten k{\"o}nnen, werden nicht ausgesch{\"o}pft. Um mit digitalen Werkzeugen eine Entscheidungshilfe f{\"u}r die Baugenehmigungsbeh{\"o}rden zu erarbeiten, ist es notwendig, den Ist-Zustand zu verstehen und Gegebenheiten zu hinterfragen, bevor eine Gesamtautomatisierung der innerbeh{\"o}rdlichen Vorg{\"a}nge als alleinige L{\"o}sung zu verfolgen ist. Mit einer inhaltlich-organisatorischen Betrachtung der relevanten Bereiche, die Einfluss auf die Baugenehmigungsfeststellung nehmen, wird eine Optimierung des Baugenehmigungsverfahrens in den Beh{\"o}rden angestrebt. Es werden die komplexen Bereiche, wie die Gesetzeslage, der Einsatz von Technologie aber auch die subjektiven Handlungsalternativen, ermittelt und strukturiert. Mit der Entwicklung eines Modells zur Feststellung der Baugenehmigungsf{\"a}higkeit wird sowohl ein Verst{\"a}ndnis f{\"u}r Einflussfaktoren vermittelt als auch eine Transparenzsteigerung f{\"u}r alle Beteiligten geschaffen. Neben einer internationalen Literaturrecherche diente eine empirische Studie als Untersuchungsmethode. Die empirische Studie wurde in Form von qualitativen Experteninterviews durchgef{\"u}hrt, um den Ist-Zustand im Bereich der Baugenehmigungsverfahren festzustellen. Das erhobene Datenmaterial wurde aufbereitet und anschließend einer softwaregest{\"u}tzten Inhaltsanalyse unterzogen. Die Ergebnisse wurden in Kombination mit den Erkenntnissen der Literaturrecherche in verschiedenen Analysen als Modellgrundlage aufgearbeitet. Ergebnis der Untersuchung stellt ein Entscheidungsmodell dar, welches eine L{\"u}cke zwischen den gegenw{\"a}rtigen Abl{\"a}ufen in den Baubeh{\"o}rden und einer Gesamtautomatisierung der Baugenehmigungspr{\"u}fung schließt. Die prozessorientierte Strukturierung entscheidungsrelevanter Sachverhalte im Modell erm{\"o}glicht eine Unterst{\"u}tzung bei der Baugenehmigungsfeststellung f{\"u}r Pr{\"u}fer und Antragsteller. Das theoretische Modell konnte in Form einer Webanwendung in die Praxis {\"u}bertragen werden.}, subject = {Baugenehmigung}, language = {de} } @phdthesis{Hoerold, author = {H{\"o}rold, Stefan}, title = {Leistungsbezogene Musterjahresganglinien f{\"u}r den Straßenbetriebsdienst}, doi = {10.25643/bauhaus-universitaet.4491}, url = {http://nbn-resolving.de/urn:nbn:de:gbv:wim2-20210830-44910}, school = {Bauhaus-Universit{\"a}t Weimar}, pages = {124}, abstract = {In den letzten Jahrzehnten unterlag der Straßenbetriebsdienst tiefgreifenden Ver{\"a}nderungen. Diese Ver{\"a}nderungen schließt auch die betriebliche Steuerungsphilosophie ein, um eine planungsrationale und {\"o}konomische Gestaltung des Straßenbetriebsdienstes zu unterst{\"u}tzen. Dabei erfolgt eine verbindliche Vorgabe der Leistungsinhalte und -umf{\"a}nge und erm{\"o}glicht eine Budgetierung f{\"u}r das vorgesehene Jahresarbeitsprogramm. Ziel der Untersuchung ist die Entwicklung eines Modells f{\"u}r die Ermittlung von leistungsbezogenen Musterjahresganglinien zur Unterst{\"u}tzung der Jahresarbeitsplanung. Daf{\"u}r lagen f{\"u}r jede Leistung des Leistungsbereiches „Gr{\"u}npflege" jeweils 260 einzelne Jahresganglinien vor. Im Ergebnis der Untersuchung wird die leistungsbezogene Musterjahresganglinie in vier Schritten ermittelt. Im ersten Schritt erfolgt die Pr{\"u}fung der Datenqualit{\"a}t; im zweiten Schritt eine Korrelationsanalyse; im dritten Schritt die fachliche {\"U}berpr{\"u}fung der Leistungsauspr{\"a}gung und im vierten Schritt die Ermittlung der leistungsbezogenen Musterjahresganglinie aus den verbliebenen leistungsbezogenen Jahresganglinien.}, subject = {Straßenbetriebsdienst}, language = {de} } @phdthesis{Ruhland, author = {Ruhland, Grit}, title = {FOLGELANDSCHAFT. Eine Untersuchung der Auswirkungen des Uranbergbaus auf die Landschaft um Gera/Ronneburg.}, doi = {10.25643/bauhaus-universitaet.4495}, url = {http://nbn-resolving.de/urn:nbn:de:gbv:wim2-20210906-44953}, school = {Bauhaus-Universit{\"a}t Weimar}, pages = {357}, abstract = {Das Kernthema dieser Arbeit ist die Besch{\"a}ftigung mit den Folgen des Uranbergbaus in dem Gebiet um die ehemalige Abbauregion der Wismut SAG/SDAG in Ronneburg (Ostth{\"u}ringen). Dieses Thema wird unter historischen, sozialen, kulturanthropologischen und k{\"u}nstlerischen Aspekten betrachtet und in den Zusammenhang mit den weltweiten Voraussetzungen der Nuklearindustrie und Auswirkungen des Uranbergbaus und seiner Folgen gestellt. Die Arbeit legt dar, wie eine Uranbergbaufolgelandschaft entsteht und welches Wissen ist f{\"u}r ein angemessenes Verst{\"a}ndnis des Ph{\"a}nomens wichtig ist. Es wird untersucht, ob Kunst bez{\"u}glich der Uranbergbaufolgelandschaft einen relevanten Beitrag leisten kann bzw. in welcher Form dies versucht wurde, bzw. stellte Arbeiten vor, die verwandete Themen bearbeitet haben. In Kombination dieser beiden Hauptaspekte geht die Arbeit der Frage nach, welche Faktoren die Uranbergbaufolgelandschaft pr{\"a}gen und ob es sinnvolle Beteiligungsfelder f{\"u}r k{\"u}nstlerisches Forschen oder Handeln gibt sowie welche Bedingungen hierf{\"u}r erf{\"u}llt werdenm{\"u}ssten. Die Kernthese der Arbeit ist, dass k{\"u}nstlerische Arbeiten im Themenfeld des Uranbergbaus unter bestimmten Bedingungen relevante Beitr{\"a}ge leisten k{\"o}nnen.}, subject = {Uranbergbau}, language = {de} } @phdthesis{Pereyra2022, author = {Pereyra, Ail{\´e}n Suyai}, title = {Continuidades, tensiones y rupturas en las pr{\´a}cticas del habitar, en el marco de las transformaciones de barrios 'tradicionales'. El Caso de barrio G{\"u}emes 2000-2016}, doi = {10.25643/bauhaus-universitaet.4651}, url = {http://nbn-resolving.de/urn:nbn:de:gbv:wim2-20220524-46511}, school = {Bauhaus-Universit{\"a}t Weimar}, pages = {263}, year = {2022}, abstract = {El presente trabajo se inscribe en el campo de los estudios urbanos y plantea como ejes estructurantes la intersección entre las políticas públicas, el barrio y las prácticas del habitar (de Certeau, 1996, 1999; Gravano, 2003) en el marco de las transformaciones del espacio urbano en los barrios pericentrales, también denominados tradicionales de la ciudad de Córdoba, particularmente lo acontecido en Barrio G{\"u}emes, durante el periodo 2010-2016. El propósito del abordaje se inscribe en conocer y realizar aportes generalizables a la comprensión de las prácticas del habitar como unidad de análisis. En ese marco, el problema de investigación se formula en el siguiente interrogante: ?'cómo se modifican las prácticas del habitar en el marco de las transformaciones urbanas, en un modo de producción capitalista? Se entiende a las prácticas como acciones elementales de las "artes de hacer" que las personas ordinarias ponen en marcha en su vida cotidiana: para circular, cocinar, trabajar, vincularse. También, a través de las mismas resignifican los espacios, les otorgan una valoración (positiva o negativa), se identifican como parte de la identidad y a su vez se reconocen lugares de (des)encuentro y vías de circulación. Para su abordaje se toma como unidad de estudio el caso de barrio G{\"u}emes. El recorte espacial (o físico) del trabajo empírico está localizado en la ciudad de Córdoba, y se sitúa en la periferia del área central. Esta localización permite comprender el surgimiento de las primeras expansiones urbanas como consecuencia del crecimiento demográfico y cómo estas, se transformaron en los primeros barrios. El recorte temporal se encuentra delimitado entre los años 2000 y 2016, respaldado intencionalmente por dos acontecimientos significativos: el censo de población (2001) y la celebración del Bicentenario de la Independencia en Argentina. Los cambios materializados en ciertos espacios urbanos, tanto en ciudades latinoamericanas (Buenos Aires, Salvador de Bahía en Brasil, México Distrito Federal, etc.) como en otras partes del mundo (New Orleans en los Estados Unidos, el distrito de Kreuzberg- Friedrichshain en Berlín, el puerto de Hamburgo en Alemania, etc.) demuestran cómo estos espacios se van transformado acorde al modo de reproducción capitalista. Pues, se trataba de espacios que en algún momento cumplieron funciones económicas-sociales jerarquizadas y luego por la dinámica misma del capitalismo, la sobreacumulación, dejan de ser rentables y pasan a ser espacios "obsoletos". En ese sentido, la omisión de acciones públicas y/o privadas, la desatención y el crecimiento de situaciones sociales conflictivas (delitos, inseguridad, degradación) en estos espacios, funciona como argumento para que los gobiernos locales comiencen a planear el futuro y modernizarlos. De esta manera, se plantean políticas urbanas con el objetivo de impulsar acciones de renovación o rehabilitación para dinamizar económicamente determinados sectores. Dos elementos discursivos aparecen como posibilitadores del proceso de renovación urbana: el turismo y el patrimonio. En ese sentido, bajo la recuperación patrimonial de ciertos lugares se dinamizan los territorios, por lo que el turismo se vuelve una herramienta económica que produce un excedente de plusvalía. La puesta en valor de bienes tangibles e intangibles atrae la afluencia de visitantes y, a la vez, es rentable económicamente. Ahora bien, muchas veces los proyectos tienen en cuenta las variables morfológicas y físicas, dejando en un segundo plano el impacto en el espacio próximo y las relaciones entre los habitantes con su territorio. Actualmente los espacios elegidos por los municipios para la intervención pública y/o privada son los barrios, puesto que son espacios cercanos al centro y considerados estratégicos. Por lo general, el argumento es la necesidad de rehabilitar/renovar zonas poco aprovechadas o degradadas con el objetivo de mejorar la calidad de vida de la población y dinamizar el sector (Brites, 2017; Guevara, 2012). Desde los 2000 el barrio G{\"u}emes asiste a un proceso de crecimiento inusitado. La cantidad de artesanos se disparó y variedad de productos ofrecidos, emergieron los comercios que forman parte de la oferta comercial, gastronómica y cultural del barrio. Hace varios años, presenta nuevos actores económicos que se pueden observar en la apertura de galerías comerciales; ubicadas sobre el eje de las calles Belgrano, Achával Rodríguez, Fructuoso Rivera y la creciente aparición de edificaciones alrededor de la feria artesanal histórica; con la venta y exposición de piezas del arte plástico, gastronomía, negocios de diseñadores cordobeses y hasta la inclusión de la idea del del "desarrollo sustentable" en los techos de las galerías. La modificación del corpus normativo, la aparición de edificación en altura y el boom económico tuvieron como resultado, la valorización del suelo urbano, la retroalimentación en el espacio con el emplazamiento de nuevas actividades comerciales y servicios culturales. A la par, en el espacio barrial se presentan nuevos residentes con otros hábitos y prácticas que ponen en disputa los modos de habitar en el espacio. A riesgo de simplificar, estas transformaciones fueron producto de los cambios políticoideológicos, de los modelos e instrumentos de gestión urbana puestos en juego en los diversos momentos históricos y de las propias prácticas sociales y culturales de los habitantes. De esta manera, se centrará la mirada analítica en las transformaciones de las prácticas del habitar de los pobladores de los Barrios G{\"u}emes, en el marco de la metamorfosis del espacio urbano (atravesado por tendencias de mediatización y mercantilización de la experiencia) que conjugó un proceso de intersección y asociatividad entre políticas públicas y expansión inmobiliaria.}, subject = {Stadtviertel}, language = {es} } @phdthesis{Fauth, author = {Fauth, Judith}, title = {A process-oriented decision model for determining the permitability of construction projects}, doi = {10.25643/bauhaus-universitaet.4602}, url = {http://nbn-resolving.de/urn:nbn:de:gbv:wim2-20220309-46020}, school = {Bauhaus-Universit{\"a}t Weimar}, pages = {325}, abstract = {In recent years, the discussion of digitalization has arrived in the media, at conferences, and in committees of the construction and real estate industry. While some areas are producing innovations and some contributors can be described as pioneers, other topics still show deficits with regard to digital transformation. The building permit process can also be counted in this category. Regardless of how architects and engineers in planning offices rely on innovative methods, building documents have so far remained in paper form in too many cases, or are printed out after electronic submission to the authority. Existing resources - for example in the form of a building information model, which could provide support in the building permit process - are not being taken advantage of. In order to use digital tools to support decision-making by the building permit authorities, it is necessary to understand the current situation and to question conditions before pursuing the overall automation of internal authority processes as the sole solution. With a substantive-organizational consideration of the relevant areas that influence building permit determination, an improvement of the building permit procedure within authorities is proposed. Complex areas - such as legal situations, the use of technology, as well as the subjective alternative action - are determined and structured. With the development of a model for the determination of building permitability, both an understanding of influencing factors is conveyed and an increase in transparency for all parties involved is created. In addition to an international literature review, an empirical study served as the research method. The empirical study was conducted in the form of qualitative expert interviews in order to determine the current state in the field of building permit procedures. The collected data material was processed and subsequently subjected to a software-supported content analysis. The results were processed, in combination with findings from the literature review, in various analyses to form the basis for a proposed model. The result of the study is a decision model that closes the gap between the current processes within the building authorities and an overall automation of the building permit review process. The model offers support to examiners and applicants in determining building permit eligibility, through its process-oriented structuring of decision-relevant facts. The theoretical model could be transferred into practice in the form of a web application.}, subject = {Baugenehmigung}, language = {en} } @phdthesis{Chawdhury, author = {Chawdhury, Samir}, title = {Partitioned Algorithms using Vortex Particle Methods for Fluid-Structure Interaction of Thin-walled Flexible Structures}, publisher = {arts + science weimar GmbH}, address = {Weimar}, isbn = {978-3-95773-297-2}, doi = {10.25643/bauhaus-universitaet.6404}, url = {http://nbn-resolving.de/urn:nbn:de:gbv:wim2-20230703-64042}, school = {Bauhaus-Universit{\"a}t Weimar}, pages = {256}, abstract = {Structures under wind action can exhibit various aeroelastic interaction phenomena, which can lead to destructive and catastrophic events. Such unstable interaction can be beneficially used for small-scale aeroelastic energy harvesting. Proper understanding and prediction of fluid-structure interactions (FSI) phenomena are therefore crucial in many engineering fields. This research intends to develop coupled FSI models to extend the applicability of Vortex Particle Methods (VPM) for numerically analysing the complex FSI of thin-walled flexible structures under steady and fluctuating incoming flows. In this context, the flow around deforming thin bodies is analysed using the two-dimensional and pseudo-three-dimensional implementations of VPM. The structural behaviour is modelled and analysed using the Finite Element Method. The partitioned coupling approach is considered because of the flexibility of using different mathematical procedures for solving fluid and solid mechanics. The developed coupled models are validated with several benchmark FSI problems in the literature. Finally, the models are applied to several fundamental and application field of FSI problems of different thin-walled flexible structures irrespective of their size.}, subject = {Windenergie}, language = {en} } @phdthesis{Potocka, author = {Potocka, Anna}, title = {Wearables: Kontrollregime zwischen Affekt und Technologie}, doi = {10.25643/bauhaus-universitaet.4459}, url = {http://nbn-resolving.de/urn:nbn:de:gbv:wim2-20210713-44594}, school = {Bauhaus-Universit{\"a}t Weimar}, pages = {164}, abstract = {{\"U}berwachungspraktiken und -technologien sind in der heutigen Welt omnipr{\"a}sent und wohl nicht mehr wegzudenken. Ob CCTV-Systeme, Biometrie oder Data Mining - unsere Gesellschaft befindet sich in einem st{\"a}ndigen {\"U}berwachungsmodus, der sich weit {\"u}ber einen begrenzten Raum oder zeitlichen Rahmen hinausstreckt. {\"U}berwacht wird {\"u}berall: privat, am Arbeitsplatz oder im Cyberspace, und alles: Interaktionen, {\"A}ußerungen, Verhalten. Es werden Unmengen von Daten gesammelt, strukturiert, kombiniert, gekauft und verkauft. Dieser Modus stellt mehr als eine bloße Neuauflage des Bentham-Foucaultschen Panoptikons dar: der aktuelle {\"U}berwachungsmodus, die informationelle Asymmetrie als ihren tragenden Pfeiler beibehaltend, dient nicht nur der Disziplinierung, sondern viel mehr der Kontrolle, die nicht prim{\"a}r negativ-sanktionierend, sondern positiv-leistungssteigernd wirkt: es ist nicht das Ziel, die Individuen zu bestrafen und ein bestimmtes Verhalten zu verbieten, sondern sie durch Belohnung, Interaktion und spielerische Elemente dazu zu bringen, sich auf die gew{\"u}nschte Art zu verhalten und im Endeffekt sich selbst zu {\"u}berwachen. Die Kontrolle wird auf diese Weise zum zentralen Schauplatz der Machtaus{\"u}bung, die sich {\"u}ber das Beobachten, Speichern, Auswerten und Sortieren vollzieht. Diese Prozesse hinterlassen keinen Frei- oder Spielraum f{\"u}r Ambiguit{\"a}t; sie verwirklichen die Diktatur der klaren Kante, der Klassifizierung und Kategorisierung ohne Schattierungen. Die Macht selbst befindet sich in einem kontinuierlichen Fluss, sie ist ubiquit{\"a}r, dennoch schwer lokalisierbar. Sie fungiert nicht mehr unter dem Signum einer pseudosakralen zentralen Instanz, sondern wird durch diverse Akteure und Assemblages kolportiert. Die durch sie implizierten Praktiken der Selbstkontrolle, kulturgeschichtlich ebenfalls religi{\"o}s oder zumindest philosophisch konnotiert, sind die neuen Rituale des Sehens und Gesehen-Werdens. Im Zeitalter der elektronischen Datentechnologien gibt es diverse Agenten der {\"U}berwachung. Vom besonderen Interesse sind dabei die Wearables, weil sie intim, affektiv und haptisch arbeiten und so, {\"u}ber das Sehen und Gesehen-Werden hinaus, das Ber{\"u}hren und Ber{\"u}hrt-Werden und somit die Neuregulierung von N{\"a}he und Distanz ins Spiel bringen. Sie schreiben sich zwar in eine Vermessungstradition eins, die ihre Urspr{\"u}nge mindestens im 19. Jahrhundert hat, unterscheiden sich aber von dieser in ihrer Intensit{\"a}t und Sinnlichkeit.}, subject = {Technologie}, language = {de} } @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} } @phdthesis{Shamskooshki, author = {Shamskooshki, Hanieh}, title = {Perception of Socio-Spatial Segregation: The Interaction of Physical and Social Urban Space-Study case of Tehran Neighborhoods}, doi = {10.25643/bauhaus-universitaet.4466}, url = {http://nbn-resolving.de/urn:nbn:de:gbv:wim2-20210802-44666}, school = {Bauhaus-Universit{\"a}t Weimar}, abstract = {"How to understand the interaction between urban space and social processes" is a significant question in urban studies. To answer that, the city needs to be recognized as both a physical and a social entity and urban theory and practice need to connect these (Hillier 2007). The present research aims to re-examine the complex correlation between spatial and social inequality manifestations in the city of Tehran regarding the concept of segregation. It observes the causes and consequences of segregation in Tehran and provides an insight into both concepts of socio-spatial segregation and neighborhood effects and creates a link between them. First, I argue when, where, and for whom spatial locations affect the chances of social networks in Tehran. Then, I discuss how neighborhood effects can emerge via social network mechanisms and thus affect the perceptions of residents in the neighborhoods.}, subject = {Soziales Netzwerk}, language = {en} } @phdthesis{KhademiZahedi, author = {Khademi Zahedi, Reza}, title = {Stress Distribution in Buried Defective PE Pipes and Crack Propagation in Nanosheets}, doi = {10.25643/bauhaus-universitaet.4481}, url = {http://nbn-resolving.de/urn:nbn:de:gbv:wim2-20210803-44814}, school = {Bauhaus-Universit{\"a}t Weimar}, pages = {235}, abstract = {Buried PE pipelines are the main choice for transporting hazardous hydrocarbon fluids and are used in urban gas distribution networks. Molecular dynamics (MD) simulations used to investigate material behavior at nanoscale.}, subject = {Gasleitung}, language = {en} } @phdthesis{Gruender, author = {Gr{\"u}nder, Anika}, title = {Denkmalzug{\"a}nge zwischen Abgrenzen, Genießen, Erinnern und Teilhaben}, doi = {10.25643/bauhaus-universitaet.4456}, url = {http://nbn-resolving.de/urn:nbn:de:gbv:wim2-20210628-44569}, school = {Bauhaus-Universit{\"a}t Weimar}, pages = {349}, abstract = {Die interdisziplin{\"a}re Dissertationsschrift l{\"a}sst sich im Horizont internationaler Forschungen zu Denkmalwerten, neuer Ans{\"a}tze in der Kultur- und Wissensvermittlung rund um Baudenkmale sowie k{\"u}nstlerisch- ethnographischem Forschen an und mit Denkmalen verorten. Der erste Teil der Arbeit widmet sich Denkmalen und der Denkmalpflege im Kontext k{\"u}nstlerischer und sozialwissenschaftlicher Allianzen. Ausgangspunkt ist die Feststellung, dass die Denkmalpflege zwar sehr vieles {\"u}ber Denkmale weiß, aber kaum etwas {\"u}ber deren Rezeption beim breiten Publikum. Im Mittelpunkt steht die Frage, wie hier Praktiken der bildenden Kunst und Arbeitsweisen der Kulturanthropologie die Disziplin der Denkmalpflege bereichern k{\"o}nnen, oder sogar m{\"u}ssen. Den zweiten Teil bildet eine empirische Studie, in der die popul{\"a}re Wahrnehmung von Denkmalen qualitativ erforscht wird. Das Schloss und Rittergut Bedheim im s{\"u}dlichen l{\"a}ndlichen Th{\"u}ringen dient dabei als konkreter Untersuchungsort. Reaktionen von Besucherinnen und Besuchern werden mit Hilfe von drei k{\"u}nstlerischen Eingriffen angeregt und diese dann ethnographisch-offen dokumentiert und ausgewertet. Auf dieser Basis werden Zug{\"a}nge zum Denkmal ermittelt. W{\"a}hrend die meisten BesucherInnen das Denkmal als „Arbeit" wahrnehmen, geraten einige ins „Tr{\"a}umen" oder „Erinnern", man „genießt" das Ensemble als authentische und {\"a}sthetische Ressource, oder findet Zugang {\"u}ber das spontane „Erkl{\"a}ren" baukonstruktiver oder baulicher Situationen. F{\"u}r andere bedeutet der Besuch die „Teilhabe" an einem Prozess. Schloss Bedheim wird als Ort stetiger Ver{\"a}nderung gesch{\"a}tzt. In der Wahrnehmung der BesucherInnen verquicken sich Aspekte des Bewunderns mit solchen des Abgrenzens. Die eigene Alltagswelt und das eigene Zuhause bilden hierbei Bezugspunkte. Schloss Bedheim wird auf diese Weise zum Imaginationsraum, zur Energietankstelle und zur gern besuchten Problemwelt. Die Ergebnisse der Arbeit liegen in zwei Erkenntnisfeldern: Auf einer methodischen Ebene zeigt sie, wie in der Denkmalpflege vertiefte Fachlichkeit mit einer tats{\"a}chlichen Kontaktaufnahme mit dem Publikum verbunden werden kann und damit soziale Gef{\"u}ge an Baudenkmalen qualitativ ermittelt werden k{\"o}nnen. Ebenso wird deutlich, dass k{\"u}nstlerische Eingriffe Ausl{\"o}ser von Gespr{\"a}chen sind, als Kontaktfl{\"a}chen zur Alltagswelt dienen und so zu einer vielf{\"a}ltigen Auseinandersetzung mit Denkmalen f{\"u}hren. Auf einer inhaltlichen Ebene liefert die Arbeit Erkenntnisse zu Wahrnehmungsweisen von Denkmalen. Neben den erw{\"a}hnten Zug{\"a}ngen, wird die Existenz und Bedeutung einer regional vernetzten Wahrnehmung von Denkmalen aufgedeckt. Des Weiteren zeigen die Ergebnisse, dass das {\"O}ffnen von Baudenkmalen als und im Prozess ungenutzte Potentiale birgt und es wird angeregt, dies in zuk{\"u}nftigen denkmalpflegerischen Konzepten eine gr{\"o}ßere Rolle spielen zu lassen. Die Vision eines „Kompendiums der Zug{\"a}nge" wird entwickelt, mit dessen Hilfe sich ein enormes Wissen {\"u}ber Rollen und Bedeutungen die Baudenkmale in unserer Gesellschaft spielen, sammeln ließe.}, subject = {Denkmalpflege}, language = {de} } @phdthesis{Foka, author = {Foka, Zinovia}, title = {The Space In-Between. Tracing Transformative Processes in Nicosia's Buffer Zone.}, doi = {10.25643/bauhaus-universitaet.4444}, url = {http://nbn-resolving.de/urn:nbn:de:gbv:wim2-20210531-44447}, school = {Bauhaus-Universit{\"a}t Weimar}, pages = {266}, abstract = {This thesis examines urban partition in Nicosia, the capital of Cyprus, and how its changing roles and shifting perceptions in a post-conflict setting reflect power relations, and their constant renegotiation. Nicosia, the capital of Cyprus, was officially divided in 1974 in the aftermath of an eighteen-year-long conflict between the island's Turkish- and Greek-Cypriot communities. As a result, a heavily militarized Buffer Zone, established as an emergency measure against perpetuation of intercommunal violence, has been cutting through its historic centre ever since. This thesis departs from a genuine interest in the material and ideational dimensions of urban partition. How is it constructed, not merely in physical terms but in the minds of the societies affected by conflict? How is it established in official and everyday discourses? What kinds of mechanisms have been developed to maintain it, and make an inseparable part of the urban experience? Moreover, taking into account the consensus in relevant literature pertaining to the imperative for its removal, this thesis is inquiring into the relevance of peace agreements to overcoming urban partition. For this purpose, it also looks at narratives and practices that have attempted to contest it. The examples examined in this thesis offer pregnant analytical moments to understand Nicosia's Buffer Zone as a dynamic social construct, accommodating multiple visions of and for the city. Its space 'in-between' facilitates encounters between various actors, accommodates new meanings, socio-spatial practices and diverse imaginaries. In this sense, urban partition is explored in this thesis as a phenomenon that transcends scales as well as temporalities, entwining past, present, and future.}, subject = {Stadtforschung}, language = {en} } @phdthesis{Alkam, author = {Alkam, Feras}, title = {Vibration-based Monitoring of Concrete Catenary Poles using Bayesian Inference}, volume = {2021}, publisher = {Bauhaus-Universit{\"a}tsverlag}, address = {Weimar}, doi = {10.25643/bauhaus-universitaet.4433}, url = {http://nbn-resolving.de/urn:nbn:de:gbv:wim2-20210526-44338}, school = {Bauhaus-Universit{\"a}t Weimar}, pages = {177}, abstract = {This work presents a robust status monitoring approach for detecting damage in cantilever structures based on logistic functions. Also, a stochastic damage identification approach based on changes of eigenfrequencies is proposed. The proposed algorithms are verified using catenary poles of electrified railways track. The proposed damage features overcome the limitation of frequency-based damage identification methods available in the literature, which are valid to detect damage in structures to Level 1 only. Changes in eigenfrequencies of cantilever structures are enough to identify possible local damage at Level 3, i.e., to cover damage detection, localization, and quantification. The proposed algorithms identified the damage with relatively small errors, even at a high noise level.}, subject = {Parameteridentifikation}, language = {en} } @phdthesis{Goswami, author = {Goswami, Somdatta}, title = {Phase field modeling of fracture with isogeometric analysis and machine learning methods}, doi = {10.25643/bauhaus-universitaet.4384}, url = {http://nbn-resolving.de/urn:nbn:de:gbv:wim2-20210304-43841}, school = {Bauhaus-Universit{\"a}t Weimar}, pages = {168}, abstract = {This thesis presents the advances and applications of phase field modeling in fracture analysis. In this approach, the sharp crack surface topology in a solid is approximated by a diffusive crack zone governed by a scalar auxiliary variable. The uniqueness of phase field modeling is that the crack paths are automatically determined as part of the solution and no interface tracking is required. The damage parameter varies continuously over the domain. But this flexibility comes with associated difficulties: (1) a very fine spatial discretization is required to represent sharp local gradients correctly; (2) fine discretization results in high computational cost; (3) computation of higher-order derivatives for improved convergence rates and (4) curse of dimensionality in conventional numerical integration techniques. As a consequence, the practical applicability of phase field models is severely limited. The research presented in this thesis addresses the difficulties of the conventional numerical integration techniques for phase field modeling in quasi-static brittle fracture analysis. The first method relies on polynomial splines over hierarchical T-meshes (PHT-splines) in the framework of isogeometric analysis (IGA). An adaptive h-refinement scheme is developed based on the variational energy formulation of phase field modeling. The fourth-order phase field model provides increased regularity in the exact solution of the phase field equation and improved convergence rates for numerical solutions on a coarser discretization, compared to the second-order model. However, second-order derivatives of the phase field are required in the fourth-order model. Hence, at least a minimum of C1 continuous basis functions are essential, which is achieved using hierarchical cubic B-splines in IGA. PHT-splines enable the refinement to remain local at singularities and high gradients, consequently reducing the computational cost greatly. Unfortunately, when modeling complex geometries, multiple parameter spaces (patches) are joined together to describe the physical domain and there is typically a loss of continuity at the patch boundaries. This decrease of smoothness is dictated by the geometry description, where C0 parameterizations are normally used to deal with kinks and corners in the domain. Hence, the application of the fourth-order model is severely restricted. To overcome the high computational cost for the second-order model, we develop a dual-mesh adaptive h-refinement approach. This approach uses a coarser discretization for the elastic field and a finer discretization for the phase field. Independent refinement strategies have been used for each field. The next contribution is based on physics informed deep neural networks. The network is trained based on the minimization of the variational energy of the system described by general non-linear partial differential equations while respecting any given law of physics, hence the name physics informed neural network (PINN). The developed approach needs only a set of points to define the geometry, contrary to the conventional mesh-based discretization techniques. The concept of `transfer learning' is integrated with the developed PINN approach to improve the computational efficiency of the network at each displacement step. This approach allows a numerically stable crack growth even with larger displacement steps. An adaptive h-refinement scheme based on the generation of more quadrature points in the damage zone is developed in this framework. For all the developed methods, displacement-controlled loading is considered. The accuracy and the efficiency of both methods are studied numerically showing that the developed methods are powerful and computationally efficient tools for accurately predicting fractures.}, subject = {Phasenfeldmodell}, language = {en} } @phdthesis{Bianco, author = {Bianco, Marcelo Jos{\´e}}, title = {Coupling between Shell and Generalized Beam Theory (GBT) elements}, doi = {10.25643/bauhaus-universitaet.4391}, url = {http://nbn-resolving.de/urn:nbn:de:gbv:wim2-20210315-43914}, school = {Bauhaus-Universit{\"a}t Weimar}, pages = {265}, abstract = {In the last decades, Finite Element Method has become the main method in statics and dynamics analysis in engineering practice. For current problems, this method provides a faster, more flexible solution than the analytic approach. Prognoses of complex engineer problems that used to be almost impossible to solve are now feasible. Although the finite element method is a robust tool, it leads to new questions about engineering solutions. Among these new problems, it is possible to divide into two major groups: the first group is regarding computer performance; the second one is related to understanding the digital solution. Simultaneously with the development of the finite element method for numerical solutions, a theory between beam theory and shell theory was developed: Generalized Beam Theory, GBT. This theory has not only a systematic and analytical clear presentation of complicated structural problems, but also a compact and elegant calculation approach that can improve computer performance. Regrettably, GBT was not internationally known since the most publications of this theory were written in German, especially in the first years. Only in recent years, GBT has gradually become a fertile research topic, with developments from linear to non-linear analysis. Another reason for the misuse of GBT is the isolated application of the theory. Although recently researches apply finite element method to solve the GBT's problems numerically, the coupling between finite elements of GBT and other theories (shell, solid, etc) is not the subject of previous research. Thus, the main goal of this dissertation is the coupling between GBT and shell/membrane elements. Consequently, one achieves the benefits of both sides: the versatility of shell elements with the high performance of GBT elements. Based on the assumptions of GBT, this dissertation presents how the separation of variables leads to two calculation's domains of a beam structure: a cross-section modal analysis and the longitudinal amplification axis. Therefore, there is the possibility of applying the finite element method not only in the cross-section analysis, but also the development for an exact GBT's finite element in the longitudinal direction. For the cross-section analysis, this dissertation presents the solution of the quadratic eigenvalue problem with an original separation between plate and membrane mechanism. Subsequently, one obtains a clearer representation of the deformation mode, as well as a reduced quadratic eigenvalue problem. Concerning the longitudinal direction, this dissertation develops the novel exact elements, based on hyperbolic and trigonometric shape functions. Although these functions do not have trivial expressions, they provide a recursive procedure that allows periodic derivatives to systematise the development of stiffness matrices. Also, these shape functions enable a single-element discretisation of the beam structure and ensure a smooth stress field. From these developments, this dissertation achieves the formulation of its primary objective: the connection of GBT and shell elements in a mixed model. Based on the displacement field, it is possible to define the coupling equations applied in the master-slave method. Therefore, one can model the structural connections and joints with finite shell elements and the structural beams and columns with GBT finite element. As a side effect, the coupling equations limit the displacement field of the shell elements under the assumptions of GBT, in particular in the neighbourhood of the coupling cross-section. Although these side effects are almost unnoticeable in linear analysis, they lead to cumulative errors in non-linear analysis. Therefore, this thesis finishes with the evaluation of the mixed GBT-shell models in non-linear analysis.}, subject = {Biegetheorie}, language = {en} } @phdthesis{Baron, author = {Baron, Nicole}, title = {Natural Urban Resilience: Understanding general urban resilience through Addis Ababa's inner city}, doi = {10.25643/bauhaus-universitaet.4416}, url = {http://nbn-resolving.de/urn:nbn:de:gbv:wim2-20210428-44166}, school = {Bauhaus-Universit{\"a}t Weimar}, abstract = {This dissertation describes the urban actors and spatial practices that contribute to natural urban resilience in Addis Ababa's inner city. Natural urban resilience is a non-strategical and bottom-up, everyday form of general urban resilience - an urban system's ability to maintain its essential characteristics under any change. This study gains significance by exposing conceptual gaps in the current un-derstanding of general urban resilience and highlighting its unconvincing applicability to African cities. This study attains further relevance by highlighting the danger of the ongoing large-scale redevelopment of the inner city. The inner city has naturally formed, and its urban memory, spaces, and social cohesion contribute to its primarily low-income population's resilience. This thesis argues that the inner city's demolition poses an incalculable risk of maladaptation to future stresses and shocks for Addis Ababa. The city needs a balanced urban discourse that highlights the inner city's qualities and suggests feasible urban transformation measures. "Natural Urban Resilience" contributes an empirical study to the debate by identifying those aspects of the inner city that contribute to general resilience and identifies feasible action areas. This study develops a qualitative research design for a single case study in Addis Ababa. The data is obtained through expert interviews, interviews with resi-dents, and the analysis of street scene photos, which are abstracted using Grounded Theory. That way, this thesis provides first-time knowledge about who and what generates urban resilience in the inner city of Addis Ababa and how. Furthermore, the study complements existing theories on general urban resilience. It provides a detailed understanding of the change mechanisms in resilience, of which it identifies four: adaptation, upgrading, mitigation, and resistance. It also adapts the adaptive cycle, a widely used concept in resilience thinking, conceptually for urban environments. The study concludes that the inner city's continued redevelopment poses an incalculable threat to the entire city. Therefore, "Natural urban resilience" recommends carefully weighing any intervention in the inner city to promote Addis Ababa's overall resilience. This dissertation proposes a pattern language for natural urban resilience to support these efforts and to translate the model of natural urban resilience into practice.}, subject = {Stadtforschung}, language = {en} } @phdthesis{Arzmi, author = {Arzmi, Azmah}, title = {Reinterpreting Marzahn, Berlin \& Petržalka, Bratislava: From Process of State Socialist Utopia to Utopia of State Capitalist Process}, doi = {10.25643/bauhaus-universitaet.4392}, url = {http://nbn-resolving.de/urn:nbn:de:gbv:wim2-20210315-43927}, school = {Bauhaus-Universit{\"a}t Weimar}, abstract = {Housing estates were fundamentally conceived upon state socialist utopia ideas to provide standard housing for citizens. While former state socialist housing estates have been extensively researched in the field of architecture, urban and sociology studies, there is still a gap in identifying how production processes affect morphological changes during the post-socialist era. This thesis compares the processes in the production of the largest housing estates of Marzahn in GDR and Petržalka in Czechoslovakia from 1970 to 1989 through contextual analysis of primary and secondary sources, which include visual maps, diagrams from professional architecture and planning journals, government documents and textbooks, as well as academic journals, books and newspaper articles. Then it discusses how these processes inadvertently created conducive conditions affecting their development in the market economy after 1989. It then interprets the results through application of Actor-Network Theory and Historical Institutionalism, while conceptualising them through David Harvey's dialectical utopianism theory. Harvey (2000) delineates two types of utopia, one of spatial form and one of process. The former refers to materialised ideals in physical forms whereas the latter refers to the ongoing process of spatializing. The thesis aims to show how the production of Marzahn in GDR was more path dependent on policies established in 1950s and 1960s whereas Petržalka was a product of new Czechoslovakian policies in 1970s, changing aspects of the urban planning process, a manifestation of a more emphatic technocratic thinking on a wider scale. This ultimately influences the trajectories of development after 1989, showing more effects in Petržalka.}, subject = {Kulturerbe}, language = {en} } @phdthesis{Reshetnikova, author = {Reshetnikova, Tatiana}, title = {Transformation of the Environment: Influence of "Urban Reagents." German and Russian Case Studies}, doi = {10.25643/bauhaus-universitaet.4351}, url = {http://nbn-resolving.de/urn:nbn:de:gbv:wim2-20210128-43517}, school = {Bauhaus-Universit{\"a}t Weimar}, pages = {256 (thesis) + 23 (Folder) + 83 (CD)}, abstract = {An urban regeneration manifests itself through urban objects operating as change agents. The en-tailed diverse effects on the surroundings demonstrate experimental origin - an experiment as a preplanned but unpredictable method. An understanding of influences and features of urban ob-jects requires scrutiny due to a high potential of the elements to force an alteration and reactions. This dissertation explores the transformation of the milieu and mechanisms of this transformation.}, subject = {Stadtentwicklung}, language = {en} } @phdthesis{Bielik, author = {Bielik, Martin}, title = {FORM-ACTIVITY-MOVEMENT INTERACTION MODEL}, doi = {10.25643/bauhaus-universitaet.4397}, url = {http://nbn-resolving.de/urn:nbn:de:gbv:wim2-20210407-43970}, school = {Bauhaus-Universit{\"a}t Weimar}, pages = {269}, abstract = {This dissertation investigates the interactions between urban form, allocation of activities, and pedestrian movement in the context of urban planning. The ability to assess the long-term impact of urban planning decisions on what people do and how they get there is of central importance, with various disciplines addressing this topic. This study focuses on approaches proposed by urban morphologists, urban economists, and transportation planners, each aiming the attention at a different part of the form-activity-movement interaction. Even though there is no doubt about the advantages of these highly focused approaches, it remains unclear what is the cost of ignoring the effect of some interactions while considering others. The general aim of this dissertation is to empirically test the validity of the individual models and quantify the impact of this isolationist approach on their precision and bias. For this purpose, we propose a joined form-activity-movement interaction model and conduct an empirical study in Weimar, Germany. We estimate how the urban form and activities affect movement as well as how movement and urban form affect activities. By estimating these effects in isolation and simultaneously, we assess the bias of the individual models. On the one hand, the empirical study results confirm the significance of all interactions suggested by the individual models. On the other hand, we were able to show that when these interactions are estimated in isolation, the resulting predictions are biased. To conclude, we do not question the knowledge brought by transportation planners, urban morphologists, and urban economists. However, we argue that it might be of little use on its own. We see the relevance of this study as being twofold. On the one hand, we proposed a novel methodological framework for the simultaneous estimation of the form-activity-movement interactions. On the other hand, we provide empirical evidence about the strengths and limitations of current approaches.}, subject = {Stadtplanung}, language = {en} } @phdthesis{Sproete, author = {Spr{\"o}te, Daniel}, title = {Immobilienportfoliomanagement {\"o}ffentlicher musealer Schl{\"o}sserverwaltungen - Daten zur Investitionssteuerung}, doi = {10.25643/bauhaus-universitaet.4426}, url = {http://nbn-resolving.de/urn:nbn:de:gbv:wim2-20210510-44260}, school = {Bauhaus-Universit{\"a}t Weimar}, pages = {220}, abstract = {Die Arbeit leistet einen wissenschaftlichen Beitrag zur Erforschung der Einsatzm{\"o}glichkeiten eines Immobilienportfoliomanagements f{\"u}r {\"o}ffentliche museale Schl{\"o}sserverwaltungen in Deutschland. Insbesondere wird ein f{\"u}r deren Organisation spezifisches Modell zur Investitionssteuerung herausgearbeitet und dessen Anwendbarkeit in der Praxis mit Experten diskutiert.}, subject = {Unbewegliche Sache}, language = {de} } @phdthesis{Javanmardi, author = {Javanmardi, Leila}, title = {URBANISM AND DICTATORSHIP. A Study on Urban Planning in Contemporary History of Iran, Second Pahlavi: 1941-1979}, doi = {10.25643/bauhaus-universitaet.4597}, url = {http://nbn-resolving.de/urn:nbn:de:gbv:wim2-20220224-45971}, school = {Bauhaus-Universit{\"a}t Weimar}, pages = {237}, abstract = {The evolution of urbanism under dictatorship forms the core of the current research. This thesis is part of a research network at Bauhaus-Universit{\"a}t Weimar, which studies the 20th century's urbanism under different dictatorships. The network has provided a cross-cultural and cross-border environment and has enabled the author to communicate with other like-minded researchers. The 2015 published book of this group 'Urbanism and Dictatorship: A European Perspective' strengthens the foundation of this research's theoretical and methodological framework. This thesis investigates urban policies and plans leading to the advancement of urbanization and the transformation of urban space in Iran during the second Pahlavi (1941-1979) when the country faced a milestone in its history: Nationalization of the Iranian oil industry. By reflecting the influence of economic and socio-political determinants of the time on urbanism and the urbanization process, this work intends to critically trace the effect of dictatorship on evolved urbanism before and after the oil nationalization in 1951. The research on the second Pahlavi's urbanism has been limitedly addressed and has only recently expanded. Most of the conducted studies date back to less than a decade ago and could not incorporate all the episodes of the second Pahlavi urbanism. These works have often investigated urbanism and architecture by focusing merely on the physical features and urban products in different years regardless of the importance of urbanism as a tool in the service of hegemony. In other words, the majority of the available literature does not intend to address the socio-economic and political roots of urban transformations and by questioning 'what has been built?' investigates the individual urban projects and plans designed by individual designers without interlinking these projects to the state's urban planning program and tracing the beneficiaries of those projects or questioning 'built for whom?' Moreover, some chapters of this modern urbanism have rarely been investigated. For instance, scant research has looked into the works of foreign designers and consultants involved in the projects such as Peter Georg Ahrens or Constantinos A. Doxiadis. Similarly, the urbanism of the first decade of the second Pahlavi, including the government of Mossadegh, has mainly been overlooked. Therefore, by critically analyzing the state's urban planning program and the process of urbanization in Iran during the second Pahlavi, this research aims to bridge the literature gap and to unravel the effect of the power structure on urban planning and products while seeking to find a pattern behind the regime's policies. The main body of this work is concentrated on studying the history of urbanism in Iran, of which collecting data and descriptions played a crucial role. To prevent the limitations associated with singular methods, this research's methodology is based on methodological triangulation (Denzin, 2017). With the triangulation scheme, the data is gathered by combining different qualitative and quantitative methods such as the library, archival and media research, online resources, non-participatory observation, and photography. For the empirical part, the city of Tehran is selected as the case study. Moreover, individual non-structured interviews with the locals were conducted to gain more insights regarding urban projects.}, subject = {Stadtplanung}, language = {en} } @phdthesis{Schmitz, author = {Schmitz, Tonia Annick}, title = {Entwicklung und Bilanzierung eines Photobioreaktorsystems zur Makroalgenkultivierung am Standort einer landwirtschaftlichen Biogasanlage}, doi = {10.25643/bauhaus-universitaet.4177}, url = {http://nbn-resolving.de/urn:nbn:de:gbv:wim2-20200604-41774}, school = {Bauhaus-Universit{\"a}t Weimar}, pages = {220}, abstract = {Marine Makroalgen besitzen vielversprechende Eigenschaften und Inhaltsstoffe f{\"u}r die Verwendung als Energietr{\"a}ger, Nahrungsmittel oder als Ausgangsstoff f{\"u}r Pharmazeutika. Dass die Quantit{\"a}t und Qualit{\"a}t der in nat{\"u}rlicher Umgebung wachsenden Makroalgen schwankt, reduziert jedoch deren Verwertbarkeit und erschwert die Erschließung hochpreisiger Marktsegmente. Zudem ist eine Ausweitung der Zucht in marinen und k{\"u}stennahen Aquakulturen in Europa gegenw{\"a}rtig wenig aussichtsreich, da vielversprechende Areale bereits zum Fischfang oder als Erholungs- bzw. Naturschutzgebiete ausgewiesen sind. Im Rahmen dieser Arbeit wird demzufolge ein geschlossenes Photobioreaktorsystem zur Makroalgenkultivierung entwickelt, welches eine umfassende Kontrolle der abiotischen Kultivierungsparameter und eine effektive Aufbereitung des Kulturmediums vorsieht, um eine standortunabh{\"a}ngige Algenproduktion zu erm{\"o}glichen. Zur Bilanzierung des Gesamtkonzeptes einer Kultivierung und Verwertung (stofflich oder energetisch) werden die spezifischen Wachstumsraten und Methanbildungspotentiale der Algenarten Ulva intestinalis, Fucus vesiculosus und Palmaria palmata in praktischen Versuchen ermittelt. Im Ergebnis wird f{\"u}r den gegenw{\"a}rtigen Entwicklungsstand der Kultivierungsanlage eine positive Bilanz f{\"u}r die stoffliche Verwertung der Algenart Ulva intestinalis und eine negative Bilanz f{\"u}r die energetische Verwertung aller untersuchten Algenarten erzielt. Wird ein Optimalszenario betrachtet, indem die Besatzdichten und Wachstumsraten der Algen in der Zucht erh{\"o}ht werden, bleibt die Energiebilanz negativ. Allerdings summieren sich die finanzielle Einnahmen durch einen Verkauf der Algen als Produkt auf j{\"a}hrlich 460.869€ f{\"u}r Ulva intestinalis, 4.010€ f{\"u}r Fucus vesiculosus und 16.913€ f{\"u}r Palmaria palmata. Im Ergebnis ist insbesondere eine stoffliche Verwertung der gez{\"u}chteten Gr{\"u}nalge Ulva intestinalis anzustreben und die Produktivit{\"a}t der Zuchtanlage im Sinne des Optimalszenarios zu steigern.}, subject = {Makroalgen}, language = {de} } @phdthesis{AbuBakar, author = {Abu Bakar, Ilyani Akmar}, title = {Computational Analysis of Woven Fabric Composites: Single- and Multi-Objective Optimizations and Sensitivity Analysis in Meso-scale Structures}, issn = {1610-7381}, doi = {10.25643/bauhaus-universitaet.4176}, url = {http://nbn-resolving.de/urn:nbn:de:gbv:wim2-20200605-41762}, school = {Bauhaus-Universit{\"a}t Weimar}, pages = {151}, abstract = {This study permits a reliability analysis to solve the mechanical behaviour issues existing in the current structural design of fabric structures. Purely predictive material models are highly desirable to facilitate an optimized design scheme and to significantly reduce time and cost at the design stage, such as experimental characterization. The present study examined the role of three major tasks; a) single-objective optimization, b) sensitivity analyses and c) multi-objective optimization on proposed weave structures for woven fabric composites. For single-objective optimization task, the first goal is to optimize the elastic properties of proposed complex weave structure under unit cells basis based on periodic boundary conditions. We predict the geometric characteristics towards skewness of woven fabric composites via Evolutionary Algorithm (EA) and a parametric study. We also demonstrate the effect of complex weave structures on the fray tendency in woven fabric composites via tightness evaluation. We utilize a procedure which does not require a numerical averaging process for evaluating the elastic properties of woven fabric composites. The fray tendency and skewness of woven fabrics depends upon the behaviour of the floats which is related to the factor of weave. Results of this study may suggest a broader view for further research into the effects of complex weave structures or may provide an alternative to the fray and skewness problems of current weave structure in woven fabric composites. A comprehensive study is developed on the complex weave structure model which adopts the dry woven fabric of the most potential pattern in singleobjective optimization incorporating the uncertainties parameters of woven fabric composites. The comprehensive study covers the regression-based and variance-based sensitivity analyses. The second task goal is to introduce the fabric uncertainties parameters and elaborate how they can be incorporated into finite element models on macroscopic material parameters such as elastic modulus and shear modulus of dry woven fabric subjected to uni-axial and biaxial deformations. Significant correlations in the study, would indicate the need for a thorough investigation of woven fabric composites under uncertainties parameters. The study describes here could serve as an alternative to identify effective material properties without prolonged time consumption and expensive experimental tests. The last part focuses on a hierarchical stochastic multi-scale optimization approach (fine-scale and coarse-scale optimizations) under geometrical uncertainties parameters for hybrid composites considering complex weave structure. The fine-scale optimization is to determine the best lamina pattern that maximizes its macroscopic elastic properties, conducted by EA under the following uncertain mesoscopic parameters: yarn spacing, yarn height, yarn width and misalignment of yarn angle. The coarse-scale optimization has been carried out to optimize the stacking sequences of symmetric hybrid laminated composite plate with uncertain mesoscopic parameters by employing the Ant Colony Algorithm (ACO). The objective functions of the coarse-scale optimization are to minimize the cost (C) and weight (W) of the hybrid laminated composite plate considering the fundamental frequency and the buckling load factor as the design constraints. Based on the uncertainty criteria of the design parameters, the appropriate variation required for the structural design standards can be evaluated using the reliability tool, and then an optimized design decision in consideration of cost can be subsequently determined.}, subject = {Verbundwerkstoff}, language = {en} } @phdthesis{Lee, author = {Lee, Sihyo}, title = {The making of totalitarian city in Pyongyang: The spatial transition from free to ideology, and for marketization}, doi = {10.25643/bauhaus-universitaet.4173}, url = {http://nbn-resolving.de/urn:nbn:de:gbv:wim2-20200526-41731}, school = {Bauhaus-Universit{\"a}t Weimar}, pages = {238}, abstract = {Space is a social product and a social producer. The main aim of this thesis is to reveal 'the process of totalitarian city making in Pyongyang', especially in the light of the interaction between the power and urban space. The totalitarian city of Pyongyang was born out of modernization in the process of masses formation. During the growth of colonial capitalism and Christian liberal ideas, Pyongyang was modernized and displayed the characteristics of a modern city with industrialization and urbanization. During the introduction of Japanese colonial capitalism, peasants, women, and slaves became the first masses and urban poor, and they later transformed into the mob; their violence was finally demonstrated during the Anti-Chinese Riot. After the 1945 independence, Kim's regime formed the one-party state with a cry for revolution. They produced an atmosphere of imminent war to instill fear and hatred into the psyche of Pyongyang citizens. The regime eliminated all political opponents in 1967 and finally declared the totalitarian ideology in 1974. During this process, Pyongyang demonstrated two main characteristics of a totalitarian city: the space of terror and of ideology. The space of terror produces the fear of death and the space of ideology controls the thought and life of citizens. After entry to the market, to keep Kim's controlling power, the regime used the strategy of location exchange. The camp, market, and Foreign Currency Shop were effective tools to prepare for executives' gifts. However, the market also produces the desire not only for consumption but also for freedom and truth; it is tearing down the foundation of the totalitarian city of Pyongyang. This research focuses primarily on the interaction between political power and urban space. In the process of making a totalitarian city, the power produced urban space and it influenced the psyche of Pyongyang citizens. Even though this spatial transition has created the totalitarian city and helped maintain political power, it also led and produced intended or unintended social variation in Pyongyang society.}, subject = {Pyongyang}, language = {en} } @phdthesis{HosseinNezhadShirazi, author = {Hossein Nezhad Shirazi, Ali}, title = {Multi-Scale Modeling of Lithium ion Batteries: a thermal management approach and molecular dynamic studies}, doi = {10.25643/bauhaus-universitaet.4098}, url = {http://nbn-resolving.de/urn:nbn:de:gbv:wim2-20200214-40986}, school = {Bauhaus-Universit{\"a}t Weimar}, abstract = {Rechargeable lithium ion batteries (LIBs) play a very significant role in power supply and storage. In recent decades, LIBs have caught tremendous attention in mobile communication, portable electronics, and electric vehicles. Furthermore, global warming has become a worldwide issue due to the ongoing production of greenhouse gases. It motivates solutions such as renewable sources of energy. Solar and wind energies are the most important ones in renewable energy sources. By technology progress, they will definitely require batteries to store the produced power to make a balance between power generation and consumption. Nowadays,rechargeable batteries such as LIBs are considered as one of the best solutions. They provide high specific energy and high rate performance while their rate of self-discharge is low. Performance of LIBs can be improved through the modification of battery characteristics. The size of solid particles in electrodes can impact the specific energy and the cyclability of batteries. It can improve the amount of lithium content in the electrode which is a vital parameter in capacity and capability of a battery. There exist diferent sources of heat generation in LIBs such as heat produced during electrochemical reactions, internal resistance in battery. The size of electrode's electroactive particles can directly affect the produced heat in battery. It will be shown that the smaller size of solid particle enhance the thermal characteristics of LIBs. Thermal issues such as overheating, temperature maldistribution in the battery, and thermal runaway have confined applications of LIBs. Such thermal challenges reduce the Life cycle of LIBs. As well, they may lead to dangerous conditions such as fire or even explosion in batteries. However, recent advances in fabrication of advanced materials such as graphene and carbon nanotubes with extraordinary thermal conductivity and electrical properties propose new opportunities to enhance their performance. Since experimental works are expensive, our objective is to use computational methods to investigate the thermal issues in LIBS. Dissipation of the heat produced in the battery can improve the cyclability and specific capacity of LIBs. In real applications, packs of LIB consist several battery cells that are used as the power source. Therefore, it is worth to investigate thermal characteristic of battery packs under their cycles of charging/discharging operations at different applied current rates. To remove the produced heat in batteries, they can be surrounded by materials with high thermal conductivity. Parafin wax absorbs high energy since it has a high latent heat. Absorption high amounts of energy occurs at constant temperature without phase change. As well, thermal conductivity of parafin can be magnified with nano-materials such as graphene, CNT, and fullerene to form a nano-composite medium. Improving the thermal conductivity of LIBs increase the heat dissipation from batteries which is a vital issue in systems of battery thermal management. The application of two-dimensional (2D) materials has been on the rise since exfoliation the graphene from bulk graphite. 2D materials are single-layered in an order of nanosizes which show superior thermal, mechanical, and optoelectronic properties. They are potential candidates for energy storage and supply, particularly in lithium ion batteries as electrode material. The high thermal conductivity of graphene and graphene-like materials can play a significant role in thermal management of batteries. However, defects always exist in nano-materials since there is no ideal fabrication process. One of the most important defects in materials are nano-crack which can dramatically weaken the mechanical properties of the materials. Newly synthesized crystalline carbon nitride with the stoichiometry of C3N have attracted many attentions due to its extraordinary mechanical and thermal properties. The other nano-material is phagraphene which shows anisotropic mechanical characteristics which is ideal in production of nanocomposite. It shows ductile fracture behavior when subjected under uniaxial loadings. It is worth to investigate their thermo-mechanical properties in its pristine and defective states. We hope that the findings of our work not only be useful for both experimental and theoretical researches but also help to design advanced electrodes for LIBs.}, subject = {Akkumulator}, language = {en} } @phdthesis{Truemer, author = {Tr{\"u}mer, Andr{\´e}}, title = {Calcinierte Tone als Puzzolane der Zukunft - Von den Rohstoffen bis zur Wirkung im Beton}, isbn = {978-3-00-065011-6}, doi = {10.25643/bauhaus-universitaet.4096}, url = {http://nbn-resolving.de/urn:nbn:de:gbv:wim2-20200214-40968}, school = {Bauhaus-Universit{\"a}t Weimar}, pages = {222}, abstract = {Vor dem Hintergrund einer stetig wachsenden Nachfrage an Beton wie auch ambitionierter Reduktionsziele beim in der Zementproduktion anfallenden CO2 gelten calcinierte Tone als derzeit aussichtsreichste technische Neuerung im Bereich nachhaltiger Bindemittelkonzepte. Unter Ausnutzung ihrer Puzzolanit{\"a}t soll ein erheblicher Teil der Klinkerkomponente im Zement ersetzt werden, wobei der zu ihrer Aktivierung notwendige Energiebedarf vergleichsweise niedrig ist. Wesentliche Vorteile der Tone sind ihre weltweit nahezu unbegrenzte Verf{\"u}gbarkeit sowie der {\"a}ußerst geringe rohstoffbedingte CO2-Ausstoß w{\"a}hrend der Calcinierung. Schwierigkeiten auf dem Weg der Umsetzung bestehen allerdings in der Vielseitigkeit des Systems, welches durch eine hohe Variet{\"a}t der Rohtone und des daraus folgenden thermischen Verhaltens gekennzeichnet ist. Entsprechend schwierig ist die {\"U}bertragbarkeit von Erfahrungen mit bereits etablierten calcinierten Tonen wie dem Metakaolin, der sich durch hohe Reinheit, einen aufwendigen Aufbereitungsprozess und eine entsprechend hohe Reaktivit{\"a}t auszeichnet. Ziel der Arbeit ist es daher, den bereits erlangten Kenntnisstand auf andere, wirtschaftlich relevante Tone zu erweitern und deren Eignung f{\"u}r die Anwendung im Beton herauszuarbeiten. In einem mehrstufigen Arbeitsprogramm wurde untersucht, inwieweit großtechnisch nutzbare Tone aktivierbar sind und welche Eigenschaften sich daraus f{\"u}r Zement und Beton ergeben. Die dabei festgestellte Reihenfolge Kaolinit > Montmorillonit > Illit beschreibt sowohl die Reaktivit{\"a}t der Brennprodukte als auch umgekehrt die H{\"o}he der optimalen Calciniertemperatur. Auch wandelt sich der Charakter der entstandenen Metaphasen in dieser Abfolge von r{\"o}ntgenamorph und hochreaktiv zu glasig und reaktionstr{\"a}ge. Trotz dieser Einordnung konnte selbst mit dem Illit eine mit Steinkohlenflugasche vergleichbare Puzzolanit{\"a}t festgestellt werden. Dies best{\"a}tigte sich anschließend in Parameterversuchen, bei denen die Einfl{\"u}sse von Rohstoffqualit{\"a}t, Calcinierung, Aufbereitung und Zement hinsichtlich der Reaktivit{\"a}tsausbeute bewertet wurden. Die Bandbreite der erzielbaren Qualit{\"a}ten ist dabei immens und gipfelt nicht zuletzt in stark unterschiedlichen Wirkungen auf die Festbetoneigenschaften. Hier machte sich vor allem die f{\"u}r Puzzolane typische Porenverfeinerung bemerkbar, sodass viele von Transportvorg{\"a}ngen abh{\"a}ngige Schadmechanismen unterdr{\"u}ckt wurden. Andere Schadex-positionen wie der Frostangriff ließen sich durch Zusatzmaßnahmen wie dem Eintrag von Luftporen beherrschen. Zu bem{\"a}ngeln sind vor allem die schlechte Verarbeitbarkeit kaolinitischer Metatone wie auch die f{\"u}r Puzzolane stark ausgepr{\"a}gte Carbonatisierungsneigung. Wesentliches Ergebnis der Arbeit ist, dass auch Tone, die bisher als geringwertig bez{\"u}glich des Aktivierungspotentials galten, nutzbare puzzolanische Eigenschaften entwickeln k{\"o}nnen. So kann selbst ein stark verunreinigter Illit-Ton die Qualit{\"a}t von Flugasche erreichen. Mit stei-gendem Tonmineralgehalt sowie bei Pr{\"a}sens thermisch instabilerer Tonminerale wie Mont-morillonit und Kaolinit erweitert sich das Spektrum nutzbarer Puzzolanit{\"a}ten bis hin zur hochreaktiven Metakaolin-Qualit{\"a}t. Damit lassen sich gute bis sehr gute Betoneigenschaften erzielen, sodass die Leistungsf{\"a}higkeit etablierter Kompositmaterialien erreicht wird. Somit sind die Voraussetzungen f{\"u}r eine umfangreiche Nutzung der erheblichen Tonmengen im Zement und Beton gegeben. Entsprechend k{\"o}nnen Tone einen effektiven Beitrag zu einer gesteigerten Nachhaltigkeit in der Baustoffproduktion weltweit leisten.}, subject = {Beton}, language = {de} } @phdthesis{Kavrakov, author = {Kavrakov, Igor}, title = {Synergistic Framework for Analysis and Model Assessment in Bridge Aerodynamics and Aeroelasticity}, publisher = {Bauhaus-Universit{\"a}tsverlag}, address = {Weimar}, isbn = {978-3-95773-284-2}, doi = {10.25643/bauhaus-universitaet.4109}, url = {http://nbn-resolving.de/urn:nbn:de:gbv:wim2-20200316-41099}, school = {Bauhaus-Universit{\"a}t Weimar}, pages = {314}, abstract = {Wind-induced vibrations often represent a major design criterion for long-span bridges. This work deals with the assessment and development of models for aerodynamic and aeroelastic analyses of long-span bridges. Computational Fluid Dynamics (CFD) and semi-analytical aerodynamic models are employed to compute the bridge response due to both turbulent and laminar free-stream. For the assessment of these models, a comparative methodology is developed that consists of two steps, a qualitative and a quantitative one. The first, qualitative, step involves an extension of an existing approach based on Category Theory and its application to the field of bridge aerodynamics. Initially, the approach is extended to consider model comparability and completeness. Then, the complexity of the CFD and twelve semi-analytical models are evaluated based on their mathematical constructions, yielding a diagrammatic representation of model quality. In the second, quantitative, step of the comparative methodology, the discrepancy of a system response quantity for time-dependent aerodynamic models is quantified using comparison metrics for time-histories. Nine metrics are established on a uniform basis to quantify the discrepancies in local and global signal features that are of interest in bridge aerodynamics. These signal features involve quantities such as phase, time-varying frequency and magnitude content, probability density, non-stationarity, and nonlinearity. The two-dimensional (2D) Vortex Particle Method is used for the discretization of the Navier-Stokes equations including a Pseudo-three dimensional (Pseudo-3D) extension within an existing CFD solver. The Pseudo-3D Vortex Method considers the 3D structural behavior for aeroelastic analyses by positioning 2D fluid strips along a line-like structure. A novel turbulent Pseudo-3D Vortex Method is developed by combining the laminar Pseudo-3D VPM and a previously developed 2D method for the generation of free-stream turbulence. Using analytical derivations, it is shown that the fluid velocity correlation is maintained between the CFD strips. Furthermore, a new method is presented for the determination of the complex aerodynamic admittance under deterministic sinusoidal gusts using the Vortex Particle Method. The sinusoidal gusts are simulated by modeling the wakes of flapping airfoils in the CFD domain with inflow vortex particles. Positioning a section downstream yields sinusoidal forces that are used for determining all six components of the complex aerodynamic admittance. A closed-form analytical relation is derived, based on an existing analytical model. With this relation, the inflow particles' strength can be related with the target gust amplitudes a priori. The developed methodologies are combined in a synergistic framework, which is applied to both fundamental examples and practical case studies. Where possible, the results are verified and validated. The outcome of this work is intended to shed some light on the complex wind-bridge interaction and suggest appropriate modeling strategies for an enhanced design.}, subject = {Br{\"u}cke}, language = {en} } @phdthesis{Jentzsch, author = {Jentzsch, Sina}, title = {Appell der Dinge. K{\"u}nstlerische Zuwendung zu den Dingen in den 1960er-Jahren}, doi = {10.25643/bauhaus-universitaet.4112}, url = {http://nbn-resolving.de/urn:nbn:de:gbv:wim2-20200323-41129}, school = {Bauhaus-Universit{\"a}t Weimar}, pages = {261}, abstract = {Diese Dissertation besch{\"a}ftigt sich mit Kunstwerken, die das allt{\"a}gliche Ding in den Blick nehmen. N{\"a}hrboden dieser Kunstform sind die soziokulturellen Entwicklungen des 20. Jahrhunderts, mit denen wesentliche Ver{\"a}nderungen hinsichtlich des Verh{\"a}ltnisses von Mensch und Ding einhergingen. Daraus resultierte eine allgemeine k{\"u}nstlerische Zuwendung zu den Dingen und eine einzigartige Kulmination aus verschiedenartigen Auseinandersetzungen mit ihnen als kunstf{\"a}hige Gegenst{\"a}nde, {\"u}ber die sich die neue Dingwelt erschlossen wurde und deren Kunstwerke einen Spiegel dieser Entwicklungen darstellen. Die Dissertation stellt ebenfalls die Dinge selbst in den Fokus. Vier Aspekte von Dingen (Materialit{\"a}t, Funktionalit{\"a}t, Repr{\"a}sentationalit{\"a}t und Relationalit{\"a}t) werden gesondert ins Auge gefasst und in den theoretischen Diskurs des 20. Jahrhunderts eingeordnet, um sie als Teil der gelebten Realit{\"a}t besser zu verstehen, von der sich der {\"a}sthetische Blick nicht trennen l{\"a}sst. Anhand der k{\"u}nstlerischen Positionen von Robert Rauschenberg, Christo und Jeanne-Claude, Daniel Spoerri und Arman sowie Claes Oldenburg werden die verschiedenen Aspekte der Dinge n{\"a}her betrachtet und analysiert, wie diese speziell in den Kunstwerken thematisiert werden und welche Relevanz sie f{\"u}r deren Rezeptionserfahrung haben. Die Korrelation dieser beiden Ebenen - die Dinge als konstitutiver Bestandteil im sozialen Raum und die Dinge als Elemente in Kunstwerken -, die im Fokus der vorliegenden Untersuchung steht, erm{\"o}glicht es, die k{\"u}nstlerische Zuwendung zu den Dingen in den 1960er-Jahren neu einzuordnen. Dar{\"u}ber hinaus wird dadurch ein differenziertes Bild von der Kunst dieser Zeit sowie den Dingen in der Kunst im Allgemeinen gezeichnet.}, subject = {Ding}, language = {de} } @phdthesis{Krtilova, author = {Krtilova, Katerina}, title = {Gesten des Denkens. Vil{\´e}m Flussers Medienphilosophie}, doi = {10.25643/bauhaus-universitaet.4067}, url = {http://nbn-resolving.de/urn:nbn:de:gbv:wim2-20200123-40679}, school = {Bauhaus-Universit{\"a}t Weimar}, pages = {202}, abstract = {In einer systematischen Interpretation von Vil{\´e}m Flussers Werk schl{\"a}gt die Arbeit vor, Flussers Ansatz als einen medienphilosophischen zu verstehen, insofern er das „wie" der medienphilosophischen Fragestellung in den Mittelpunkt r{\"u}ckt. Medien werden nicht erst dann zu einem wesentlichen Bestandteil von Flussers Philosophie, wenn er sie explizit zum Gegenstand seiner Untersuchungen der gegenw{\"a}rtigen Kultur und Gesellschaft oder historischer R{\"u}ckblicke macht; Denken vollzieht sich immer in Medien oder medialen Praktiken, es wird nicht nur von ihnen (mit) gepr{\"a}gt - ohne Medien g{\"a}be es kein Denken und umgekehrt ver{\"a}ndert sich Philosophie mit den (jeweils) neuen Medien. Ausgehend von Begriffen oder eher Denkfiguren, die neben dem „was" des jeweils verhandelten Themas auch das „wie" der Reflexion selbst adressieren, wird der „Umbruch in der Struktur des Denkens" zugleich als Beschreibung von Medienumbr{\"u}chen verstanden - mit dem Fluchtpunkt des Sprungs in das Universum der Komputation - und als Vollzug der gegenw{\"a}rtigen Ver{\"a}nderung der „Methode des Denkens". Flussers (Ver)Suche einer Reflexion, die nicht mehr durch das Medium Schrift strukturiert ist, sondern sowohl alten Medien wie dem Bild - bzw. Praktiken des Abbildens, Darstellens, Einbildens usw. - als auch neuen Medien - dem Komputieren - Geltung verschafft, laufen auf eine widerspr{\"u}chliche Diagnose des neuen Universums der Komputation (anders: der technischen Bilder) hinaus : eine kybermetisch inspirierte Vision der frei modellierbaren Wirklichkeit(en) einerseits und die Dystopie einer Welt, in der Apparaten Denken, Wahrnehmen und Handeln beherrschen andererseits. Die Arbeit zeigt auf, wie Flusser zu dieser Aporie der Medienreflexion - die weit {\"u}ber Flussers Werk hinaus virulent bleibt - gelangt und wie sie, ausgehend von seiner Figur der Geste, im Sinne einer performativen Medienreflexion gel{\"o}st werden k{\"o}nnte.}, subject = {Medientheorie}, language = {de} } @phdthesis{Sung, author = {Sung, Younkyoung}, title = {Cultural Tourism and Social Resilience: Discourse of Historic Cities in East Germany, the Case of Gotha and Eisenach}, doi = {10.25643/bauhaus-universitaet.4092}, url = {http://nbn-resolving.de/urn:nbn:de:gbv:wim2-20200212-40920}, school = {Bauhaus-Universit{\"a}t Weimar}, abstract = {This thesis explores how cultural heritage plays a role in the development of urban identity by engaging both actively and passively with memory, i.e. remembering and forgetting. I argue that architectural heritage is a medium where specific cultural and social decisions form its way of presentation, and it reflects the values and interests of the period. By the process of remembering and forgetting, the meanings between inhabitant and object in urban environment are practiced, and the meanings are created. To enable the research in narrative observation, cultural tourism management is chosen as the main research object, which reflects the alteration of interaction between the architectural heritage and urban identity. Identifying the role of heritage management, the definition of social resilience and the prospects of cultural heritage as a means of social resilience are addressed. Case region of the research is East Ger- many, thereby, the study examines the distinct approaches and objectives regarding heritage management under the different political systems along the German reunification process. The framework is based on various theoretical paradigms to investigate the broad research questions: 1) What is the role of historic urban quarters in the revitalisation of East German towns? 2) How was the transition processed by cultural heritage management? 3) How did policy affect residents' lives? The case study is applied to macro level (city level: Gotha and Eisenach) and micro level study (object level: specific heritage sites), to analyse the performance of selective remembering and making tourist destination through giving significance to specific heritage. By means of site observations, archival research, qualitative inter- views, photographs, and discourse analysis on printed tourism materials, the study demonstrates that certain sites and characteristics of the city enable creating and focusing messages, which aids the social resilience. Combining theory and empirical studies this thesis attempts to widen the academic discussion regarding the practice of remembering and forgetting driven by cultural heritage. The thesis argues for cultural heritage tourism as an element of social resilience and one that embraces the historic and cultural identity of the inhabitants.}, subject = {Stadtmarketing}, language = {en} }