@phdthesis{Weitze,
  author    = {Weitze, Laura Katharina},
  title     = {Erweiterte Prozessbewertung von Biogasanlagen unter Ber{\"u}cksichtigung organoleptischer Parameter und Erfahrungswissen},
  doi       = {10.25643/bauhaus-universitaet.3849},
  url       = {http://nbn-resolving.de/urn:nbn:de:gbv:wim2-20190129-38499},
  school      = {Bauhaus-Universit{\"a}t Weimar},
  pages     = {308},
  abstract  = {Landwirtschaftliche Biogasanlagen leisten mit ca. 9.300 Anlagen und einem Anteil von 5,3\% an der Stromerzeugung, einen Beitrag zur Erzeugung Erneuer-barer Energien in Deutschland. Die Optimierung dieser Anlagen f{\"o}rdert die nachhaltige Bereitstellung von Strom, W{\"a}rme und BioErdgas. Das Ergebnis dieser Forschungsarbeit ist die Entwicklung eines mehrmethodi-schen Bewertungsansatzes zur Beschreibung der Qualit{\"a}t der Eingangs-substrate als Teil einer ganzheitlichen Prozessoptimierung. Dies gelingt durch die kombinierte Nutzung klassischer Analyses{\"a}tze, der Nutzung organolepti-scher Parameter - der humansensorischen Sinnenpr{\"u}fung - und der Integration von prozess- und substratspezifischem Erfahrungswissen. Anhand von halbtechnischen Versuchen werden Korrelationen und Kausalit{\"a}ten zwi-schen chemisch-physikalischen, biologischen, organoleptischen und erfahrungsbezogenen Parametern erforscht. Die Entwicklung einer Fallbasis mit Hilfe des Fallbasierten Schließens, einer Form K{\"u}nstlicher Intelligenz, zeigt das Entwicklungs- und Integrationspotenzial der Automatisierung auf, insbesondere auch im Hinblick auf neue Ans{\"a}tze z.B. Industrie 4.0. Erste L{\"o}sungen zur Bew{\"a}ltigung der identifizierten Herausforderungen der mehrmethodischen Prozessbewertung werden vorgestellt. Abschließend wird ein Ausblick auf den weiteren Forschungsbedarf gegeben und die {\"U}bertragbarkeit des mehrmethodischen Bewertungsansatzes auf andere Anwendungsfelder z.B. Bioabfallbehandlung, Kl{\"a}ranlagen angeregt.},
  subject      = {Biogasanlage},
  language  = {de}
}
@phdthesis{ZHANG2018,
  author    = {ZHANG, CHAO},
  title     = {Crack Identification using Dynamic Extended Finite Element Method and Thermal Conductivity Engineering for Nanomaterials},
  doi       = {10.25643/bauhaus-universitaet.3847},
  url       = {http://nbn-resolving.de/urn:nbn:de:gbv:wim2-20190119-38478},
  school      = {Bauhaus-Universit{\"a}t Weimar},
  year      = {2018},
  abstract  = {Identification of flaws in structures is a critical element in the management of maintenance and quality assurance processes in engineering. Nondestructive testing (NDT) techniques based on a wide range of physical principles have been developed and are used in common practice for structural health monitoring. However, basic NDT techniques are usually limited in their ability to provide the accurate information on locations, dimensions and shapes of flaws. One alternative to extract additional information from the results of NDT is to append it with a computational model that provides detailed analysis of the physical process involved and enables the accurate identification of the flaw parameters. The aim here is to develop the strategies to uniquely identify cracks in two-dimensional 2D) structures under dynamic loadings. A local NDT technique combined eXtended Finite Element Method (XFEM) with dynamic loading in order to identify the cracks in the structures quickly and accurately is developed in this dissertation. The Newmark-b time integration method with Rayleigh damping is used for the time integration. We apply Nelder-Mead (NM)and Quasi-Newton (QN) methods for identifying the crack tip in plate. The inverse problem is solved iteratively, in which XFEM is used for solving the forward problem in each iteration. For a timeharmonic excitation with a single frequency and a short-duration signal measured along part of the external boundary, the crack is detected through the solution of an inverse time-dependent problem. Compared to the static load, we show that the dynamic loads are more effective for crack detection problems. Moreover, we tested different dynamic loads and find that NM method works more efficient under the harmonic load than the pounding load while the QN method achieves almost the same results for both load types. A global strategy, Multilevel Coordinate Search (MCS) with XFEM (XFEM-MCS) methodology under the dynamic electric load, to detect multiple cracks in 2D piezoelectric plates is proposed in this dissertation. The Newmark-b method is employed for the time integration and in each iteration the forward problem is solved by XFEM for various cracks. The objective functional is minimized by using a global search algorithm MCS. The test problems show that the XFEM-MCS algorithm under the dynamic electric load can be effectively employed for multiple cracks detection in piezoelectric materials, and it proves to be robust in identifying defects in piezoelectric structures. Fiber-reinforced composites (FRCs) are extensively applied in practical engineering since they have high stiffness and strength. Experiments reveal a so-called interphase zone, i.e. the space between the outside interface of the fiber and the inside interface of the matrix. The interphase strength between the fiber and the matrix strongly affects the mechanical properties as a result of the large ratio of interface/volume. For the purpose of understanding the mechanical properties of FRCs with functionally graded interphase (FGI), a closed-form expression of the interface strength between a fiber and a matrix is obtained in this dissertation using a continuum modeling approach according to the ver derWaals (vdW) forces. Based on the interatomic potential, we develop a new modified nonlinear cohesive law, which is applied to study the interface delamination of FRCs with FGI under different loadings. The analytical solutions show that the delamination behavior strongly depends on the interphase thickness, the fiber radius, the Young's moduli and Poisson's ratios of the fiber and the matrix. Thermal conductivity is the property of a material to conduct heat. With the development and deep research of 2D materials, especially graphene and molybdenum disulfide (MoS2), the thermal conductivity of 2D materials attracts wide attentions. The thermal conductivity of graphene nanoribbons (GNRs) is found to appear a tendency of decreasing under tensile strain by classical molecular dynamics (MD) simulations. Hence, the strain effects of graphene can play a key role in the continuous tunability and applicability of its thermal conductivity property at nanoscale, and the dissipation of thermal conductivity is an obstacle for the applications of thermal management. Up to now, the thermal conductivity of graphene under shear deformation has not been investigated yet. From a practical point of view, good thermal managements of GNRs have significantly potential applications of future GNR-based thermal nanodevices, which can greatly improve performances of the nanosized devices due to heat dissipations. Meanwhile, graphene is a thin membrane structure, it is also important to understand the wrinkling behavior under shear deformation. MoS2 exists in the stable semiconducting 1H phase (1H-MoS2) while the metallic 1T phase (1T-MoS2) is unstable at ambient conditions. As it's well known that much attention has been focused on studying the nonlinear optical properties of the 1H-MoS2. In a very recent research, the 1T-type monolayer crystals of TMDCs, MX2 (MoS2, WS2 ...) was reported having an intrinsic in-plane negative Poisson's ratio. Luckily, nearly at the same time, unprecedented long-term (>3months) air stability of the 1T-MoS2 can be achieved by using the donor lithium hydride (LiH). Therefore, it's very important to study the thermal conductivity of 1T-MoS2. The thermal conductivity of graphene under shear strain is systematically studied in this dissertation by MD simulations. The results show that, in contrast to the dramatic decrease of thermal conductivity of graphene under uniaxial tensile, the thermal conductivity of graphene is not sensitive to the shear strain, and the thermal conductivity decreases only 12-16\%. The wrinkle evolves when the shear strain is around 5\%-10\%, but the thermal conductivity barely changes. The thermal conductivities of single-layer 1H-MoS2(1H-SLMoS2) and single-layer 1T-MoS2 (1T-SLMoS2) with different sample sizes, temperatures and strain rates have been studied systematically in this dissertation. We find that the thermal conductivities of 1H-SLMoS2 and 1T-SLMoS2 in both the armchair and the zigzag directions increase with the increasing of the sample length, while the increase of the width of the sample has minor effect on the thermal conductions of these two structures. The thermal conductivity of 1HSLMoS2 is smaller than that of 1T-SLMoS2 under size effect. Furthermore, the temperature effect results show that the thermal conductivities of both 1H-SLMoS2 and 1T-SLMoS2 decrease with the increasing of the temperature. The thermal conductivities of 1HSLMoS2 and 1T-SLMoS2 are nearly the same (difference <6\%) in both of the chiral orientations under corresponding temperatures, especially in the armchair direction (difference <2.8\%). Moreover, we find that the strain effects on the thermal conductivity of 1HSLMoS2 and 1T-SLMoS2 are different. More specifically, the thermal conductivity decreases with the increasing tensile strain rate for 1T-SLMoS2, while fluctuates with the growth of the strain for 1HSLMoS2. Finally, we find that the thermal conductivity of same sized 1H-SLMoS2 is similar with that of the strained 1H-SLMoS2 structure.},
  subject      = {crack},
  language  = {en}
}
@phdthesis{Kessler2018,
  author    = {Keßler, Andrea},
  title     = {Matrix-free voxel-based finite element method for materials with heterogeneous microstructures},
  doi       = {10.25643/bauhaus-universitaet.3844},
  url       = {http://nbn-resolving.de/urn:nbn:de:gbv:wim2-20190116-38448},
  school      = {Bauhaus-Universit{\"a}t Weimar},
  pages     = {113},
  year      = {2018},
  abstract  = {Modern image detection techniques such as micro computer tomography (μCT), magnetic resonance imaging (MRI) and scanning electron microscopy (SEM) provide us with high resolution images of the microstructure of materials in a non-invasive and convenient way. They form the basis for the geometrical models of high-resolution analysis, so called image-based analysis. However especially in 3D, discretizations of these models reach easily the size of 100 Mill. degrees of freedoms and require extensive hardware resources in terms of main memory and computing power to solve the numerical model. Consequently, the focus of this work is to combine and adapt numerical solution methods to reduce the memory demand first and then the computation time and therewith enable an execution of the image-based analysis on modern computer desktops. Hence, the numerical model is a straightforward grid discretization of the voxel-based (pixels with a third dimension) geometry which omits the boundary detection algorithms and allows reduced storage of the finite element data structure and a matrix-free solution algorithm. This in turn reduce the effort of almost all applied grid-based solution techniques and results in memory efficient and numerically stable algorithms for the microstructural models. Two variants of the matrix-free algorithm are presented. The efficient iterative solution method of conjugate gradients is used with matrix-free applicable preconditioners such as the Jacobi and the especially suited multigrid method. The jagged material boundaries of the voxel-based mesh are smoothed through embedded boundary elements which contain different material information at the integration point and are integrated sub-cell wise though without additional boundary detection. The efficiency of the matrix-free methods can be retained.},
  subject      = {Dissertation},
  language  = {en}
}
@phdthesis{MizrakBilen,
  author    = {Mizrak Bilen, Burcin},
  title     = {A Power-Centered Approach to the Capitalization of Climate Change in Property Sector and Strategic Limitation},
  doi       = {10.25643/BAUHAUS-UNIVERSITAET.3840},
  url       = {http://nbn-resolving.de/urn:nbn:de:gbv:wim2-20190107-38406},
  school      = {Bauhaus-Universit{\"a}t Weimar},
  pages     = {256},
  abstract  = {The capitalization of 'certified' sustainable building sector will be investigated over the power theory of value approach of Jonathan Nitzan and Shimshon Bichler. The study will be initiated by questioning why the environment problems are one of the first items on the agenda and by sharing the ideas of scholars who approaches the subject skeptically, because the predominant literature underlying the necessity and prominence of the topic is already well-known and adapted by the majority. Over the theory developed by Nitzan and Bichler, the concepts of capitalization, strategic sabotage, power, legitimacy, and obedience will be discussed. The hypothesis of "the absentee owners of the construction sector, holding the whip hand and capitalizing the ecology, control the growth and the creativity of green building production and make it carbon-dependent, in order to increase their profit margin" will be questioned. To strengthen the arguments in the hypothesis, the factors, the institutional arrangements, value measurement methods, which affect directly the net present value, will be investigated both in corporation and in building scale in detail, because net present value/ capitalization is asserted as the most important criteria by Nitzan and Bichler to make the investment decisions in the capitalist economic system. To trace the implications of power and the strategic sabotage that power caused, as the empirical dimension of this dissertation, an interface exploring the correlational ties between the climate responsive architecture and the ever changing political, economical, and social contexts and building economics praxis by decades will be developed and the expert interviews will be conducted with the design teams and the appraisers.},
  subject      = {Klima{\"a}nderung},
  language  = {en}
}
@phdthesis{Strassmann,
  author    = {Straßmann, Sarah},
  title     = {Expanded Pictures: Das Handlungsgef{\"u}ge des fotografischen Bildes im Kontext von Internet und Social Media},
  doi       = {10.25643/bauhaus-universitaet.3838},
  url       = {http://nbn-resolving.de/urn:nbn:de:gbv:wim2-20190102-38388},
  school      = {Bauhaus-Universit{\"a}t Weimar},
  pages     = {164},
  abstract  = {In der vorliegenden Arbeit wird die Bedeutung und Funktion des fotografischen Bildes und im Besonderen der Handyfotografie im Kontext von Internet und sozialen Onlinenetzwerken beschrieben, untersucht und diskutiert. Im Spannungsfeld zwischen sozialwissenschaftlichen Theorien, foto- und medientheoretischem Diskurs sowie {\"a}sthetisch k{\"u}nstlerischen Perspektiven wird ausgelotet, welche konkreten visuellen und sozialen Formen die gegenw{\"a}rtige mobile digitale Bildpraxis angenommen hat, wie sich ihre Gebrauchsweise innerhalb des globalen gesellschaftlichen Alltags darstellt, und in welcher Weise ihr spezielles Zusammenspiel aus „shooting", „uploading", „sharing" zu neuen menschlichen Handlungsmustern und zur Schaffung neuer kultureller Realit{\"a}ten beitr{\"a}gt.},
  subject      = {Digitale Fotografie},
  language  = {de}
}