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1
Munawar, Mohammad Ahmad. "Multi-interface Multi-channel wireless mesh networks." Thesis, University of Waterloo, 2004. http://hdl.handle.net/10012/875.
Abstract:
In this thesis we propose a multi-channel wireless network based on nodes that use multiple 802. 11 radio interfaces. The proposed system is singular, as it does not require new hardware or a new MAC, but instead leverages commodity 802. 11-based products. With this system, we target scenarios where the nodes are stationary and where their location can often be controlled. We evaluate the performance in this setup using an ad-hoc network approach whereby nodes generate as well as forward data. We also present and appraise a purely-wireless multi-channel infrastructure, which operates like the WLAN infrastructure-based networks in existence today, but without any fixed-line support. In such an infrastructure nodes dedicated for routing purposes provide wireless connectivity to users. We show that a multi-interface system provide significantly higher capacity in many scenarios. Our work puts forward various challenges, points to various anomalies in the operation of the 802. 11 MAC protocol, and shows the need to tackle unfairness issues. Our experiments demonstrate that the mere use of more dual-interface nodes does not necessarily create higher capacity. We also show that traffic differentiation significantly increases aggregate throughput in realistic scenarios. Finally, we provide an example of how simple channel-allocation algorithms in controlled random topologies can allow us to take advantage of a multi-interface system.
2
Wang, Jun. "Interface assignment, bandwidth allocation and scheduling for wireless mesh networks /." access full-text access abstract and table of contents, 2009. http://libweb.cityu.edu.hk/cgi-bin/ezdb/thesis.pl?phd-cs-b30082705f.pdf.
Abstract:
Thesis (Ph.D.)--City University of Hong Kong, 2009."Submitted to Department of Computer Science in partial fulfillment of the requirements for the degree of Doctor of Philosophy." Includes bibliographical references (leaves [104]-116)
3
Wang, Junfang. "Efficient Positioning Technique for Multi-Interface Multi-Rate Wireless Mesh Networks." University of Cincinnati / OhioLINK, 2010. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1289937715.
4
Morris, David Victor. "A new graphical user interface for a 3D topological mesh modeler." Texas A&M University, 2008. http://hdl.handle.net/1969.1/85977.
Abstract:
In this thesis, I present a new platform-independent, open source, intuitive
graphical user interface for TopMod, an application designed for interacting with
3-dimensional manifold meshes represented by a Doubly Linked Face List (DLFL).
This new interface, created using the Trolltech Qt user interface library, enables
users to construct and interact with complex manifold meshes much faster and more
easily than was previously possible. I also present a method for the rapid creation
of a successful online community of users and developers, by integrating a variety
of open source web-based software packages. The new website, which includes a
discussion forum, a news blog, a collaborative user and developer wiki, and a source
code repository and release manager, received an average of 250 unique visits per
day during the first two months of its existence, and it continues to be utilized by a
variety of users and developers worldwide.
5
Randrianarivony, Maharavo. "Software pertaining to the preparation of CAD data from IGES interface for mesh-free and mesh-based numerical solvers." Universitätsbibliothek Chemnitz, 2007. http://nbn-resolving.de/urn:nbn:de:swb:ch1-200700267.
Abstract:
We focus on the programming aspect of the treatment of digitized
geometries for subsequent use in mesh-free and mesh-based numerical
solvers. That perspective includes the description of our C/C++ implementations
which use OpenGL for the visualization and MFC classes for the user
interface. We report on our experience about implementing with the IGES
interface which serves as input for storage of geometric information. For
mesh-free numerical solvers, it is helpful to decompose the boundary of a
given solid into a set of four-sided surfaces. Additionally, we will describe
the treatment of diffeomorphisms on four-sided domains by using transfinite
interpolations. In particular, Coons and Gordon patches are appropriate for
dealing with such mappings when the equations of the delineating curves
are explicitly known. On the other hand, we show the implementation of
the mesh generation algorithms which invoke the Laplace-Beltrami operator.
We start from coarse meshes which one refine according to generalized
Delaunay techniques. Our software is also featured by its ability of treating
assembly of solids in B-Rep scheme.
6
Anand, Nagarajan. "A Conforming to Interface Structured Adaptive Mesh Refinement for Modeling Complex Morphologies." The Ohio State University, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=osu1574436067401755.
7
Chen, Yuhao. "Conforming to interface structured adaptive mesh refinement technique for modeling moving boundary problems." The Ohio State University, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=osu1492428866626613.
8
Kim, Bo Hung. "A graphical preprocessing interface for non-conforming spectral element solvers." [College Station, Tex. : Texas A&M University, 2006. http://hdl.handle.net/1969.1/ETD-TAMU-1819.
9
Teixeira, de Oliveira Carina. "Conception et optimisation de performance inter-couches dans les réseaux maillés radio multi-canal multi-interface." Thesis, Grenoble, 2012. http://www.theses.fr/2012GRENM056/document.
Abstract:
Dans cette thèse, nous nous concentrons sur la conception et l’optimisation de performances inter-couches dans les réseaux maillés radio multi-canal multi-interface. Afin de profiter de l'augmentation de la capacité de ces réseaux, un certain nombre de problèmes doit être résolu. La première contribution de cette thèse est une nouvelle classification et une évaluation formelle des différentes stratégies d’assignation de canaux et d’interfaces. Nous adressons en particulier la connectivité en termes de formation de topologie, densité de connexions et découverte de voisinage. La deuxième contribution présente des algorithmes de broadcast fonctionnant pour n’importe quelle stratégie d’assignation multi-canal multi-interface. Ces algorithmes garantissent qu’un paquet de broadcast est délivré avec une probabilité minimale à tous les voisins. La troisième contribution de cette thèse propose d’évaluer la capacité (débit) obtenue à travers les différentes solutions d’assignation de canaux et d’interfaces. Plus précisément, nous proposons trois formulations de programmation linéaire mixte pour modéliser le routage et les contraintes de partage de bande passante en présence d'interférences. Nous dérivons ensuite des bornes supérieures et inférieures pour deux stratégies MAC différentes. Notre dernière contribution propose de développer une solution de routage inter-couches pour les réseaux maillés multi-canal multi-interface. En particulier, nous proposons une métrique de qualité de lien estimant la bande passante résiduelle d'un lien. Un protocole de routage adapté permet ensuite de trouver les routes offrant le meilleur débit. Toutes nos contributions sont validées par des nombreuses simulations qui démontrent l'efficacité de nos solutions. En résumé, cette thèse fournit une analyse en profondeur des réseaux maillés radio multi-canal multi-interface, ainsi que des lignes directrices pour les concepteurs de réseaux afin de déployer des réseaux performantsIn this PhD thesis, we focus on the design and performance optimization of multi-channel multi-interface wireless mesh networks. To take advantage of the increased capacity in such networks, a number of issues has to be handled properly. The first contribution of this thesis is a novel classification and formal evaluation of different channel and interface assignment strategies. In particular, we focus on connectivity in terms of topology formation, density of connections, and neighbor discovery. Our second contribution presents broadcast algorithms able to handle any of the multi-channel multi-interface assignment strategies. These algorithms guarantee a broadcast packet to be delivered with a minimum probability to all neighbors. The third contribution of this thesis consists in evaluating the network capacity (i.e., throughput) obtained through the different channel and interface assignments schemes. More specifically, we propose three mixed integer linear programming formulations to model the routing and bandwidth sharing constraints in presence of interference. We derive then upper and lower bounds for different MAC strategies. The fourth and last contribution of this thesis is the development of a novel cross-layer routing solution for multi-channel multi-interface mesh networks. In particular, we propose a link-quality aware metric to estimate the residual bandwidth of a link. An on-demand routing protocol selects the routes offering the best throughput. All our contributions are validated through extensive simulations that demonstrate the efficiency of our solutions. In summary, this thesis provide insight into the improvement of multi-channel multi-interface wireless mesh networks, as well as guidelines for network designers in planning efficient deployments
10
Sambasivan, Shiv Kumar. "A sharp interface Cartesian grid hydrocode." Diss., University of Iowa, 2010. https://ir.uiowa.edu/etd/593.
Abstract:
Dynamic response of materials to high-speed and high-intensity loading conditions is important in several applications including high-speed flows with droplets, bubbles and particles, and hyper-velocity impact and penetration processes. In such high-pressure physics problems, simulations encounter challenges associated with the treatment of material interfaces, particularly when strong nonlinear waves like shock and detonation waves impinge upon them. To simulate such complicated interfacial dynamics problems, a fixed Cartesian grid approach in conjunction with levelset interface tracking is attractive. In this regard, a sharp interface Cartesian grid-based, Ghost Fluid Method (GFM) is developed for resolving embedded fluid, elasto-plastic solid and rigid (solid) objects in hyper-velocity impact and high-intensity shock loaded environment. The embedded boundaries are tracked and represented by virtue of the level set interface tracking technique. The evolving multi-material interface and the flow are coupled by meticulously enforcing the boundary conditions and jump relations at the interface. In addition, a tree-based Local Mesh Refinement scheme is employed to efficiently resolve the desired physics. The framework developed is generic and is applicable to interfaces separating a wide range of materials and for a broad spectrum of speeds of interaction (O(km/s)). The wide repertoire of problems solved in this work demonstrates the flexibility, stability and robustness of the method in accurately capturing the dynamics of the embedded interface. Shocks interacting with large ensembles of particles are also computed.
11
Zhang, Xu. "Nonconforming Immersed Finite Element Methods for Interface Problems." Diss., Virginia Tech, 2013. http://hdl.handle.net/10919/20380.
Abstract:
In science and engineering, many simulations are carried out over domains consisting ofmultiple materials separated by curves/surfaces. If partial differential equations (PDEs)
are used to model these simulations, it usually leads to the so-called interface problems of
PDEs whose coefficients are discontinuous. In this dissertation, we consider nonconforming
immersed "nite element (IFE) methods and error analysis for interface problems.
We "first consider the second order elliptic interface problem with a discontinuous diffusion
coefficient. We propose new IFE spaces based on the nonconforming rotated Q1 "finite elements on Cartesian meshes. The degrees of freedom of these IFE spaces are determined by midpoint values or average integral values on edges. We investigate fundamental properties of these IFE spaces, such as unisolvency and partition of unity, and extend well-known trace inequalities and inverse inequalities to these IFE functions. Through interpolation error analysis, we prove that these IFE spaces have optimal approximation capabilities.
We use these IFE spaces to develop partially penalized Galerkin (PPG) IFE schemes whose
bilinear forms contain penalty terms over interface edges. Error estimation is carried out
for these IFE schemes. We prove that the PPG schemes with IFE spaces based on integral-value degrees of freedom have the optimal convergence in an energy norm. Following a similar approach, we prove that the interior penalty discontinuous Galerkin schemes based on these IFE functions also have the optimal convergence. However, for the PPG schemes based on midpoint-value degrees of freedom, we prove that they have at least a sub-optimal convergence. Numerical experiments are provided to demonstrate features of these IFE methods and compare them with other related numerical schemes.
We extend nonconforming IFE schemes to the planar elasticity interface problem with discontinuous Lam"e parameters. Vector-valued nonconforming rotated Q1 IFE functions with
integral-value degrees of freedom are unisolvent with appropriate interface jump conditions.
More importantly, the Galerkin IFE scheme using these vector-valued nonconforming rotated
Q1 IFE functions are "locking-free" for nearly incompressible elastic materials.
In the last part of this dissertation, we consider potential applications of IFE methods to
time dependent PDEs with moving interfaces. Using IFE functions in the discretization in
space enables the applicability of the method of lines. Crank-Nicolson type fully discrete
schemes are also developed as alternative approaches for solving moving interface problems.
Ph. D.
12
Cross, J. T. "Adaptivity, mesh generation and user interface design applied to the finite element simulation of casting processes." Thesis, Swansea University, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.636324.
Abstract:
Adaptivity is a process by which a numerical solution is improved by changing the discretisation according to some criterion based on the value of the field variable. The criterion is frequently an estimate of the error, and the improvement is frequently done by regenerating the mesh. In this work 2D error estimation and mesh regeneration schemes are described for both heat transfer and fluid flow analyses, covering both steady-state and time dependent problems. In addition, several schemes based on criteria other than error estimation are presented. Casting is an application area which has most of the features that make adaptivity worthwhile, complex geometries, time dependency, moving fronts and high gradients. Examples exhibiting these features are given, showing that solutions can be obtained at moderate computational cost and, importantly, without user interference. The generation of meshes for an adaptive casting analysis required flexibility, robustness speed and an ability to work automatically. An implementation of the advancing front 2D mesh generation method, implemented in C, is described that achieves these objectives. Some methods for improving robustness and mesh quality are outlined, as well as a description of the main data structure used to facilitate fast searching. Several examples show the ability of the generator to cope with complex geometries of the type found in casting problems. Although adaptivity can allow the major part of the solution process to be carried out automatically, an experienced operator is still required to define the analysis domain, set boundary and initial conditions, set analysis parameters and examine the results. In an effort to make casting analysis available to those with foundry, as opposed to numerical, experience, a graphical user interface has been designed and implemented. This has been done with the benefit of a considerable amount of foundry feedback, as well as recourse to the literature of human-computer interaction. The interface is currently being used successfully in a number of UK foundries.
13
González, Barrameda José Andrés. "Search Space Analysis and Efficient Channel Assignment Solutions for Multi-interface Multi-channel Wireless Networks." Thèse, Université d'Ottawa / University of Ottawa, 2011. http://hdl.handle.net/10393/20155.
Abstract:
This thesis is concerned with the channel assignment (CA) problem in multi-channel
multi-interface wireless mesh networks (M2WNs). First, for M2WNs with general topologies,
we rigorously demonstrate using the combinatorial principle of inclusion/exclusion
that the CA solution space can be quantified, indicating that its cardinality is greatly
influenced by the number of radio interfaces installed on each router. Based on this analysis,
a novel scheme is developed to construct a new reduced search space, represented
by a lattice structure, that is searched more efficiently for a CA solution. The elements
in the reduced lattice-based space, labeled Solution Structures (SS), represent groupings
of feasible CA solutions satisfying the radio constraints at each node. Two algorithms
are presented for searching the lattice structure. The first is a greedy algorithm that
finds a good SS in polynomial time, while the second provides a user-controlled depthfirst
search for the optimal SS. The obtained SS is used to construct an unconstrained
weighted graph coloring problem which is then solved to satisfy the soft interference
constraints.
For the special class of full M2WNs (fM2WNs), we show that an optimal CA solution
can only be achieved with a certain number of channels; we denote this number as the
characteristic channel number and derive upper and lower bounds for that number as a
function of the number of radios per router. Furthermore, exact values for the required
channels for minimum interference are obtained when certain relations between the number
of routers and the radio interfaces in a given fM2WN are satisfied. These bounds are
then employed to develop closed-form expressions for the minimum channel interference
that achieves the maximum throughput for uniform traffic on all communication links.
Accordingly, a polynomial-time algorithm to find a near-optimal solution for the channel
assignment problem in fM2WN is developed.
Experimental results confirm the obtained theoretical results and demonstrate the
performance of the proposed schemes.
14
Holcomb, Andrew M. "Development of a graphical user interface for the coarse mesh radiation transport code COMET and cross section generation with HELIOS." Thesis, Georgia Institute of Technology, 2013. http://hdl.handle.net/1853/52952.
Abstract:
The coarse mesh radiation transport (COMET) code uses response functions to solve the neutron transport equation. Most nuclear codes used today have a very steep learning curve; COMET is no exception. To ease the user's onus of learning how to create correctly formatted COMET input-files, a graphical user interface (GUI) was created. The GUI allows the user to select values for all the relevant variables while simultaneously minimizing the errors a typical new user would make. To this end, the GUI creates all of the input files required to run COMET. The GUI also provides a visualization tool that the user may use to check the problem geometry before running COMET. The GUI is also responsible for post-processing the COMET output for visualization with TecPlot.
In addition to the GUI, multi-group cross section libraries were generated as part of the MHTGR-350 (Modular High Temperature Gas Reactor) benchmark problem under development at Georgia Tech. This project aims to couple COMET with a thermal hydraulics code to best model the true physics of the reactor design. In order for this goal to be actualized, six-group cross sections were generated over the operational temperature range of the MHTGR using the current coupling and collision probability code HELIOS.
15
Guo, Ruchi. "A Linear Immersed Finite Element Space Defined by Actual Interface Curve on Triangular Meshes." Thesis, Virginia Tech, 2017. http://hdl.handle.net/10919/79946.
Abstract:
In this thesis, we develop the a new immersed finite element(IFE) space formed by piecewise linear polynomials defined on sub-elements cut by the actual interface curve for solving elliptic interface problems on interface independent meshes. A group of geometric identities and estimates on interface elements are derived. Based on these geometric identities and estimates, we establish a multi-point Taylor expansion of the true solutions and show the estimates for the second order terms in the expansion. Then, we construct the local IFE spaces by imposing the weak jump conditions and nodal value conditions on the piecewise polynomials. The unisolvence of the IFE shape functions is proven by the invertibility of the well-known Sherman-Morrison system. Furthermore we derive a group of fundamental identities about the IFE shape functions, which show that the two polynomial components in an IFE shape function are highly related. Finally we employ these fundamental identities and the multi-point Taylor expansion to derive the estimates for IFE interpolation errors in L2 and semi-H1 norms.Master of Science
16
Kubrak, Boris. "Direct numerical simulation of gas transfer at the air-water interface in a buoyant-convective flow environment." Thesis, Brunel University, 2014. http://bura.brunel.ac.uk/handle/2438/10196.
Abstract:
The gas transfer process across the air-water interface in a buoyant-convective environment has been investigated by Direct Numerical Simulation (DNS) to gain improved understanding of the mechanisms that control the process. The process is controlled by a combination of molecular diffusion and turbulent transport by natural convection. The convection when a water surface is cooled is combination of the Rayleigh-B´enard convection and the Rayleigh-Taylor instability. It is therefore necessary to accurately resolve the flow field as well as the molecular diffusion and the turbulent transport which contribute to the total flux. One of the challenges from a numerical point of view is to handle the very different levels of diffusion when solving the convection-diffusion equation. The temperature diffusion in water is relatively high whereas the molecular diffusion for most environmentally important gases is very low. This low molecular diffusion leads to steep gradients in the gas concentration, especially near the interface. Resolving the steep gradients is the limiting factor for an accurate resolution of the gas concentration field. Therefore a detailed study has been carried out to find the limits of an accurate resolution of the transport for a low diffusivity scalar. This problem of diffusive scalar transport was studied in numerous 1D, 2D and 3D numerical simulations. A fifth-order weighted non-oscillatory scheme (WENO) was deployed to solve the convection of the scalars, in this case gas concentration and temperature. The WENO-scheme was modified and tested in 1D scalar transport to work on non-uniform meshes. To solve the 2D and 3D velocity field the incompressible Navier-Stokes equations were solved on a staggered mesh. The convective terms were solved using a fourth-order accurate kinetic energy conserving discretization while the diffusive terms were solved using a fourth-order central method. The diffusive terms were discretized using a fourth-order central finite difference method for the second derivative. For the time-integration of the velocity field a second-order Adams-Bashworth method was employed. The Boussinesq approximation was employed to model the buoyancy due to temperature differences in the water. A linear relationship between temperature and density was assumed. A mesh sensitivity study found that the velocity field is fully resolved on a relatively coarse mesh as the level of turbulence is relatively low. However a finer mesh for the gas concentration field is required to fully capture the steep gradients that occur because of its low diffusivity. A combined dual meshing approach was used where the velocity field was solved on a coarser mesh and the scalar field (gas concentration and temperature) was solved on an overlaying finer submesh. The velocities were interpolated by a second-order method onto the finer sub-mesh. A mesh sensitivity study identified a minimum mesh size required for an accurate solution of the scalar field for a range of Schmidt numbers from Sc = 20 to Sc = 500. Initially the Rayleigh-B´enard convection leads to very fine plumes of cold liquid of high gas concentration that penetrate the deeper regions. High concentration areas remain in fine tubes that are fed from the surface. The temperature however diffuses much stronger and faster over time and the results show that temperature alone is not a good identifier for detailed high concentration areas when the gas transfer is investigated experimentally. For large timescales the temperature field becomes much more homogeneous whereas the concentration field stays more heterogeneous. However, the temperature can be used to estimate the overall transfer velocity KL. If the temperature behaves like a passive scalar a relation between Schmidt or Prandtl number and KL is evident. A qualitative comparison of the numerical results from this work to existing experiments was also carried out. Laser Induced Fluorescence (LIF) images of the oxygen concentration field and Schlieren photography has been compared to the results from the 3D simulations, which were found to be in good agreement. A detailed quantitative analysis of the process was carried out. A study of the horizontally averaged convective and diffusive mass flux enabled the calculation of transfer velocity KL at the interface. With KL known the renewal rate r for the so called surface renewal model could be determined. It was found that the renewal rates are higher than in experiments in a grid stirred tank. The horizontally averaged mean and fluctuating concentration profiles were analysed and from that the boundary layer thickness could be accurately monitored over time. A lot of this new DNS data obtained in this research might be inaccessible in experiments and reveal previously unknown details of the gas transfer at the air water interface.
17
Siniscalchi, Rodrigo Teixeira 1971. "Efeitos biomecanicos da inclusão de orificios de tamanho padronizado em telas de polipropileno monofilamentar na interface tecidual da parede abdominal de ratas adultas." [s.n.], 2008. http://repositorio.unicamp.br/jspui/handle/REPOSIP/312342.
Abstract:
Orientadores: Cassio Luis Zanettini Riccetto, Paulo Cesar Rodrigues PalmaDissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Ciencias Medicas
Made available in DSpace on 2018-08-12T04:47:27Z (GMT). No. of bitstreams: 1 Siniscalchi_RodrigoTeixeira_M.pdf: 4843609 bytes, checksum: 15b98ee38e8ef7b8b7e68b7ace186491 (MD5) Previous issue date: 2008
Resumo: Introdução: Os prolapsos da parede vaginal são muito prevalentes. Em seu tratamento utilizam-se técnicas baseadas em suturas (correções sítio-específicas) ou, mais recentemente, o emprego de telas (próteses). Considerando-se a elevada taxa de recorrência com as técnicas convencionais, as telas passaram a representar uma opção potencial para o tratamento de casos selecionados de prolapsos urogenitais. O material sintético mais utilizado atualmente é o polipropileno monofilamentar, com índices de cura de até 90%. Com o objetivo de diminuir a quantidade de material implantado e promover melhor integração da prótese aos tecidos, evitando, respectivamente, a dispareunia e a extrusão das mesmas, foi proposta a inclusão de orifícios de tamanho padronizado nas telas, denominados orifícios facilitadores de integração. Objetivo: Avaliar, "in vivo", as propriedades biomecânicas de um tipo tela de polipropileno monofilamentar e os efeitos da inclusão de orifícios facilitadores de integração sobre a resistência na interface com o leito receptor. Material e Métodos: Foram utilizadas 40 ratas adultas nas quais foram implantadas, de um lado da sua parede abdominal, na interface entre a hipoderme e a fáscia anterior da musculatura abdominal, uma tela de polipropileno monofilamentar retangular medindo 24 x 11 mm sem orifícios (grupo 1) e, do outro lado uma tela semelhante, com 2 orifícios circulares de 6mm de diâmetro (grupo 2). Após 90 dias, as ratas foram sacrificadas sendo sua parede abdominal retirada e dividida simetricamente em 2 blocos, que continham, respectivamente, as telas com e sem orifícios. O estudo biomecânico foi realizado em um tensiômetro de precisão, no qual a tela era tracionada em sentido uniaxial até que se desprendesse da interface tecidual. Para quantificar a aderência e elasticidade tecidual, em cada grupo, foram analisadas as seguintes variáveis: carga máxima; deflexão até a carga máxima; trabalho até a carga máxima; consistência do material; além dos valores de carga, deflexão e trabalho executado no momento do desprendimento da tela. Resultados: Verificou-se que a aderência das telas de polipropileno aos tecidos circunvizinhos aumentou significativamente com a inclusão de orifícios de tamanho padronizado como demonstrado na análise dos valores encontrados para a carga máxima (p < 0,001); trabalho até a carga máxima (p < 0,001); carga no desprendimento da tela (p < 0,001); e trabalho até o desprendimento da tela (p < 0,001). Os orifícios também conferiram à tela de polipropileno maior elasticidade, como demonstrado na análise dos valores de deflexão até a carga máxima (p < 0,001) e deflexão até o desprendimento da tela (p < 0,001). Não foi observada diferença significante (p = 0,87) quando analisada a variável consistência do material (ou módulo de elasticidade). Conclusão: A inclusão de orifícios de tamanho padronizado em telas de polipropileno monofilamentar, além de reduzir o seu peso e a quantidade de material implantado, aumentou sua elasticidade e aderência aos tecidos quando implantadas na interface da parede abdominal de ratas adultas. Estes achados sugerem que a inclusão de orifícios facilitadores de integração pode influenciar, favoravelmente, o seu emprego na prática clínica.
Abstract: Objective: The use of polypropylene mesh to repair vaginal prolapse is well established in selected cases. In order to reduce the weight and increase the elasticity of the mesh, to bind the product to tissues and also to decrease the amount of material used, the inclusion of standard orifices to the size meshes was proposed. These orifices were called "helper orifices" as they improve integration. In this original study, the biomechanical properties of a type of monofilament polypropylene mesh were evaluated in vivo, as well as the effects of the inclusion of the orifices on the interface resistance in the receiving area. Method: Forty female rats received an implant of monofilament polypropylene mesh, measuring 24 x 11 mm with no orifices, on one side of the abdominal wall, at the interface between the hypoderm and the anterior fascia of the abdominal muscles (group 1). On the other side, a similar mesh with two circular orifices (6 mm diameter) was implanted (group 2). The rats were euthanized 90 days later and their abdominal walls were removed and divided into two blocks, one with the mesh without orifices and the other with the mesh with orifices. The biomechanical study used a precision tensiometer in which the mesh was uniaxially tensioned until it was loosened from the tissue interface. In order to determine the tissue adherence in each group, the following variables were analyzed: maximum load; deflection at maximum load; work to maximum load; stiffness as well as load, deflection and work at detachment of the mesh. Results: It was verified that the adherence of the polypropylene mesh to the surrounding tissue increased significantly with the inclusion of standard size orifices as it is demonstrated in the analysis of values found to the maximum load (p < 0.001); work to maximum load (p < 0.001); load at detachment of the mesh (p < 0.001); and work to detachment of the mesh (p < 0.001). The orifices also brought higher elasticity to the polypropylene mesh as demonstrated in the analysis of the values of deflection at maximum load (p < 0,001) and deflection at detachment of the mesh (p < 0.001). It was not observed statistical differences (p = 0.87) when analyzing the stiffness of the material. Conclusion: Besides reducing the weight and amount of material, the inclusion of standard size orifices in the monofilament polypropylene mesh increased the elasticity and adherence to the tissues when implanted in the interface of the abdominal wall in adult female rats. These findings suggest that the inclusion of helper orifices to improve integration may have a favorable influence in clinical practice.
Mestrado
Cirurgia
Mestre em Cirurgia
18
Krishnan, Sreedevi. "An Adaptively refined Cartesian grid method for moving boundary problems applied to biomedical systems." Diss., University of Iowa, 2006. https://ir.uiowa.edu/etd/87.
Abstract:
A major drawback in the operation of mechanical heart valve prostheses is thrombus formation in the near valve region potentially due to the high shear stresses present in the leakage jet flows through small gaps between leaflets and the valve housing. Detailed flow analysis in this region during the valve closure phase is of interest in understanding the relationship between shear stress and platelet activation.
An efficient Cartesian grid method is developed for the simulation of incompressible flows around stationary and moving three-dimensional immersed solid bodies as well as fluid-fluid interfaces. The embedded boundaries are represented using Levelsets and treated in a sharp manner without the use of source terms to represent boundary effects. The resulting algorithm is implemented in a straightforward manner in three dimensions and retains global second-order accuracy. When dealing with problems of disparate length scales encountered in many applications, it is necessary to resolve the physically important length scales adequately to ensure accuracy of the solution. Fixed grid methods often have the disadvantage of heavy mesh requirement for well resolved calculations. A quadtree based adaptive local mesh refinement scheme is developed to complement the sharp interface Cartesian grid method scheme for efficient and optimized calculations. Detailed timing and accuracy data is presented for a variety of benchmark problems involving moving boundaries.
The above method is then applied to modeling heart valve closure and predicting thrombus formation. Leaflet motion is calculated dynamically based on the fluid forces acting on it employing a fluid-structure interaction algorithm. Platelets are modeled and tracked as point particles by a Lagrangian particle tracking method which incorporates the hemodynamic forces on the particles. Leaflet closure dynamics including rebound is analyzed and validated against previous studies. Vortex shedding and formation of recirculation regions are observed downstream of the valve, particularly in the gap between the valve and the housing. Particle exposure to high shear and entrapment in recirculation regions with high residence time in the vicinity of the valve are observed corresponding to regions prone to thrombus formation.
19
Regnault, Paul. "Front-Tracking mesh adaptation for the simulation of two-phase flows with coalescence and breakup." Electronic Thesis or Diss., Université Gustave Eiffel, 2023. http://www.theses.fr/2023UEFL2076.
Abstract:
Dans le cadre des écoulements diphasiques à phases séparées, ce travail porte sur la gestion dynamique du maillage de l'interface (constitué de triangles en 3D) et son impact sur l'approximation des propriétés géométriques que sont la position et la courbure. Les équations de conservation de la mécanique des fluides sont résolues sur des grille fixes, décalées et structurées. L'interface est suivie de façon lagrangienne au cours du temps avec un maillage mobile et déformable : on parle de méthode de type « Front-Tracking ». En plus des opérations de remaillage classiques (suppression et échange d'arêtes, insertion de sommets notamment), on étudiera l'adaptation du maillage à la courbure de l'interface et l'utilisation d'une approximation polynomiale pour améliorer l'insertion de sommets ou la suppression d'arêtes. Ces méthodes sont évaluées sur des surfaces analytiques mobiles et déformables, sans résolution des équations de Navier-Stokes ni changement topologique. Dans les écoulements diphasiques, des changements topologiques peuvent avoir lieu : la coalescence et la rupture. Nous proposons une méthode de coalescence et une méthode de rupture d'interface. Ces deux méthodes sont activées selon des critères de distance et sont basées uniquement sur le maillage de l'interface, sans recourir au maillage eulérien. Ces méthodes sont utilisées sur des configurations numériques et expérimentales de la littérature pour apprécier leur robustesse et leurs performancesIn the context of two-phase flows with separated phases, this work focuses on dynamic management of the interface mesh (made up of connected triangles in 3D) and its impact on the approximation of geometrical properties that are position and curvature. The conservation equations of fluid mechanics are solved on fixed, staggered and structured grids. The interface is tracked in a Lagrangian fashion with a moving and deformable mesh: this method is known as the"Front-tracking" method. In addition to classical remeshing operations (edgesplitting, collapsing and swapping for instance), we will study the adaptation of the mesh to the curvature of the interface and the use of polynomial approximation to improve edge splitting and collapsing. These methods are evaluated on analytical, mobile and deformable surfaces, with neither the resolution of the Navier-Stokes equations nor topological changes. In two-phaseflows, topological changes may happen: coalescence and breakup. We propose a method for coalescence and a method for breakup. These two methods are activated by distance criteria and rely only on the interface mesh, without resorting to the Eulerian mesh. These methods are employed on numerical and experimental configurations from the literature to appreciate their robustness and performances
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Tachon, Loïc. "Développement d'outils numériques et expérimentaux dédiés à l'étude de l'évaporation en présence de ligne triple." Thesis, Aix-Marseille 1, 2011. http://www.theses.fr/2011AIX10027/document.
Abstract:
Les travaux réalisés au cours de cette thèse visent à apporter une aide à la compréhension des mécanismes régissant l'évaporation des films liquides. La physique des problèmes à changement de phase avec ligne de contact est gouvernée par des mécanismes agissant au niveau de ces dernières ainsi qu'au niveau des interfaces gaz-liquide. La description géométrique des interfaces est donc un point clef dans cette étude tant d'un point de vue numérique qu'expérimental. Un outil numérique tridimensionnel de suivi d'interface infiniment fine a été créé afin d'anticiper la simulation numérique de ces problèmes. Cet algorithme repose sur une description quadratique de l'interface qui est une surface du maillage. L’ordre de convergence de cette méthode relatif à différentes caractéristiques (courbure, normale, position) de l'interface ainsi que sa qualité conservative ont été étudiés.Parallèlement à cette approche numérique, une technique expérimentale d'inversion optique a été développée. Celle-ci permet la mesure dynamique du profil d'une interface au voisinage de la ligne de contact dans le cadre de fluide très mouillant. Cette méthode, appliquée dans le cadre d'un problème de film en évaporation quasi axisymétrique a permis, dans le cadre d'une expérience simple, une première quantification des flux de chaleur et de masse échangés au niveau de la ligne de contactThe tasks fulfilled during this study aim at providing tools for understanding the mechanisms of liquid film evaporation. Evaporation in the presence of a triple lines is ruled by physical mechanisms acting on these singularities as well as on the gas liquid interfaces. Thus, the interface description, under it numerical as experimental aspects, is a key point of this study. A numerical tridimentionnal sharp interface tracking tool has been developed to be used in further numerical simulation of the evaporation problem. In this algorithm, the interface is described as a quadratic grid surface. Its convergence orders relatively to geometrical parameters of the interface (curvature, normal, position) has been studied.In the mean time, an experimental optical inversion technique has been developed and validated. It allows a dynamic measurement of the interface shape in the vicinity of the triple line of highly wetting fluid. This method has been applied to the case of a quasi axisymetric evaporating film and provides a first quantification of the heat and mass transfers generated by the triple line region
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Dourado, Antonio Miguel Batista. "Modelo de especificação de interfaces tangíveis de mesa TTUI-SM." Universidade Federal de São Carlos, 2012. https://repositorio.ufscar.br/handle/ufscar/508.
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In the scenario of computational interfaces development, researches efforts aim to offer new ways of interaction that are closer to the natural way which humans interact with the real world. Amongst the diversity of interface modalities, the tabletop tangible interfaces make the link between physical objects and virtual objects, making possible to "grasp" the interface and interact with it physically, also counting on multitouch interactions. However, in the development process of this kind of interface, there is a lack of specification s model that supports, not only the physical objects interaction, but multitouch interactions as well, and that organizes and classifies the specification in a more agile manner, easier to document and implement. Thus, this work presents a new tabletop tangible user interface specification model, TTUI-SM, that classifies and organizes the interface element specification within many components. A diagramatic tool, TTUI-SMT, was developed based on this model, aiming to make the interface specification and development faster, easier and automatized. To validate the model and tool, two studycases were introduced and specified. An experiment was conducted to evaluate both model and tool, resulting in the comprovation, through questionnaires analysis, of the proposed benefits.
No cenário de desenvolvimento de interfaces computacionais, os avanços nas pesquisas buscam oferecer novas formas de interação que se aproximam da forma natural com que o homem interage com o mundo real. Dentre as diversas interfaces avançadas, as interfaces tangíveis de mesa (tabletop), promovem a ligação entre objetos físicos e objetos virtuais, possibilitando ao usuário interagir com objetos digitais por meio do ambiente físico, e também por meio de interações multitoques. Entretanto, o processo de desenvolvimento deste tipo de interface carece de um modelo de especificação que contemple, além das interações por meio de objetos, interações multitoques e que organize e classifique a especificação de uma maneira mais ágil e mais fácil de documentar e implementar. Assim, este trabalho apresenta um novo modelo de especificação de elementos de interface tangível de mesa, denominado TTUI-SM, que organiza a especificação de elementos de interface em diversos componentes. Uma ferramenta diagramática, o TTUI-SMT, baseada neste modelo de especificação, também foi desenvolvida visando agilizar, facilitar e automatizar o processo de especificação da interface e do seu desenvolvimento. Para validar o modelo e a ferramenta, dois estudos de caso foram introduzidos e especificados. Um experimento foi conduzido para avaliar o modelo e a ferramenta e, por meio de questionários, os benefícios propostos foram validados.
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Domingues, Michael André Pinto. "Modelling and control platform for 3D printers." Master's thesis, Universidade de Aveiro, 2014. http://hdl.handle.net/10773/14859.
Abstract:
Mestrado em Engenharia de Computadores e Telemática3D printers are becoming cheaper and widely used in various market segments as architecture, industrial design, automotive and aerospace engineering, providing an easy and cheaper way to produce parts and mockups. Although applications for controlling 3D printers exist, they are still poor in graphical design and difficult to use or understand due the advanced knowledge required. Most 3D printing applications allow importing and rendering a model with a 3D engine, and printing it with advanced configurations. Taking this into consideration it is intended to design and evaluate an application that presents common and advanced funcionalities through a simple, stable and easy to use user interface. An application (BEESOFT) was designed and developed taking the above objectives into consideration. It enhances the way users interact with the BEETHEFIRST printer, by providing an integrated environment where each user can, in a coordinated way, use the functionalities to quickly print. The simple user interface, the guided and self-explanatory wizards to help configure quickly the 3D printer and the robustness, error control and stability of the user interface, 3D engine and the communication protocol, distinguishes it from the other applications. This new application was evaluated using an usability testing plan and a heuristic evaluation analysis. Results confirm BEESOFT is an easy to use application that allows users with differents degrees of expertise to easily print a 3D model, but they also revealed some usability problems in the 3D canvas when modeling. The positive reaction and the results show BEESOFT simple, user spoken language and functional user interface with optimized printing profiles can be used in any sector of industry, education, etc.
As impressoras 3D estão cada vez mais baratas sendo usadas em variados nichos de mercado como na arquitectura, design industrial, engenharia automóvel e aeroespacial, fornecendo uma forma fácil e barata de produzir partes e maquetes. Embora já existam aplicações de controlo de impressoras 3D, apresentam uma interface pobre e são difíceis de usar ou perceber devido ao conhecimento necessário. A maior parte das impressoras 3D permitem importar e processar um modelo 3D e imprimir com recurso a configurações avançadas. Tendo isto em consideração pretende-se desenvolver e avaliar uma aplicação constituida por funcionalidades básicas e avançadas com uma interface de utilizador estável e simples de usar. A aplicação (BEESOFT) foi projectada e desenvolvida tendo em consideração os objectivos acima referidos. E potencia o modo como os utilizadores interagem com a impressora BEETHEFIRST, fornecendo um ambiente integrado onde cada utilizador pode, de forma orientada, usar as funcionalidades para rapidamente imprimir. A interface de utilizador simples de usar, os assistentes e auto-explicativos para ajudar a configurar rapidamente a impressora 3D, a robustez, o controlo de erros, a estabilidade da interface de utilizador, o motor 3D e o protocolo de comunicação, destacam esta aplicação de outras existentes. Esta nova aplicação foi avaliada através de um plano de testes de usabilidade e de uma análise de avaliação heurística. Os resultados confirmam que o BEESOFT é uma aplicaçao fácil de usar e que permite aos utilizadores, com variados níveis de experiência, imprimir facilmente um modelo 3D, mas também reveleram alguns problemas de usabilidade no motor 3D aquando de operações de modelação. A reacção positiva e os resultados mostraram que a interface de utilizador do BEESOFT é simples, funcional, com uma linguagem acessível e com perfis de impressão optimizados, possibilitando o seu uso em qualquer sector da indústria, educação, etc.
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Costin, William James. "Radial basis function interpolation applied to discontinuous mesh interfaces." Thesis, University of Bristol, 2013. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.653069.
Abstract:
For large-scale Computational Fluid Dynamics (CFD) simulations it is often necessary to divide the domain into a mesh of discrete points or volumes. However, the domain can also be split into a set of zones separated by interfaces, allowing the zones to be meshed individually. Discontinuous or nonmatching mesh spacing across the zonal interfaces offers many advantages, particularly in terms of easing the mesh generation process, reduction of required mesh densities, and relative motion between mesh zones. However, accurate data transfer across the interfaces is required for global solution accuracy to be maintained. A more versatile data transfer method for discontinuous interfaces has the potential to reduce both the complexity of, and constraints place on, the process of discretising complex domains. This research was motivated by work on large-scale parallelised CFD simulations using high quality structured multiblock meshes. For such tasks the accuracy of the final result has a significant dependence on the quality of the mesh used to discretise the domain. The mesh is split into separate zones for parallel computation but must be generated as a topographically consistent whole, rather than individually for each zone. The objective therefore was to create a new method of discontinuous interface data transfer that does not place topographic limitations on the mesh, simplifying the mesh generation process. To this end, the fields of flow solution, high accuracy interpolation and mesh generation have been investigated with the aim of formulating and assessing a new data transfer approach. A new data transfer method based on Radial Basis Function (RBF) interpolation is developed and presented. Strategies for the construction of the interpolation data set are compared and a new more advanced approach developed. A series of analytical tests are used to assess the properties of the new method: Both the order of accuracy of the method and the ability to accurately model the full range of frequency content are considered. The method is applied to both finite difference and finite volume numerical solutions. For the latter both multi-grid discretisation and parallelised solution have been ,j ABSTRACT implemented as part of integration into an existing parallel, multiblock, multi grid compressible flow solver. Additionally, the relative merits and cost of localised and global forms of the method are assessed. The method has been applied to a series of aeronautical test cases including a subsonic and transonic aerofoil. The results show that the method is both effective and robust, providing accurate transmission for well and poorly conceived interface geometries. One great success is that in generic form the method remains applicable to all iterative solution methods with similar domain discretisation requirements; as a result there are many opportunities for further work.
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Jašek, Roman. "Multiplatform Game Development Using the Unity Engine." Master's thesis, Vysoké učení technické v Brně. Fakulta informačních technologií, 2014. http://www.nusl.cz/ntk/nusl-236075.
Abstract:
Tato práce se zabývá možnostmi herního vývoje pro víceré platformy pomocí enginu Unity 3D. Rozebírá různé aspekty multiplatformního vývoje na počítačích i mobilních zařízeních. Důraz je kladen na analýzu tvorby her současně pro více platforem a problémy spojené s tímhle přístupem. Práce poskytuje možnosti řešení problémů, které vyvstanou při použití tohohle postupu, pomocí nástrojů, které poskytuje Unity 3D. Analýza se zabývá zejména na zvyšování výkonu her za použití metod dostupných na všech platformách vybraných pro testování. Tyhle vylepšení zahrnují způsoby jak snížit práci ve scéně a naopak zvýšit počet vykreslení za sekundu při zachování stejné vizuální kvality. Práce také nabízí pohled do minulosti tohoto odvětví a předpoklady o jeho příštím směrování.
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Boucker, Marc. "Modélisation numérique multidimensionnelle d'écoulements diphasiques liquide-gaz en régimes transitoire et permanent : méthodes et applications." Cachan, Ecole normale supérieure, 1998. http://www.theses.fr/1998DENS0032.
Abstract:
Ce travail est consacré au développement d'une méthode de résolution numérique d'un modèle simplifie d'écoulements diphasiques liquide-gaz, a sa mise en œuvre dans une maquette logicielle et a sa validation sur des configurations d'écoulements stationnaires et instationnaires. Le modèle d'écoulement diphasique considéré est une restriction du modèle général à deux fluides comprenant deux équations de bilan de masse et deux équations de bilan de quantité de mouvement. Ce système ne peut se mettre sous forme conservative et sa partie convective n'est pas hyperbolique. Une méthode volumes finis fondée sur le schéma volumes finis a flux caractéristiques est appliquée a ce système et adaptée au cas tridimensionnel sur des maillages non structures formes de tétraèdres. Une discrétisation originale du terme non conservatif dans le cas multidimensionnel est proposée. Une formulation implicite non linéaire du schéma numérique permet d'atteindre de grandes valeurs du nombre de cfl (supérieur a 100). Par ailleurs, les contraintes visqueuses sont prises en compte dans un algorithme à pas fractionnaire au moyen d'une discrétisation par éléments finis. Le passage de la discrétisation volumes finis a la discrétisation éléments finis est réalisé a l'aide des techniques de projections appelées passerelles volumes finis - éléments finis. Les calculs sur des cas test de validation ont permis d'obtenir les principaux résultats suivants : démonstration de la faisabilité de calculs sur un modèle diphasique a deux fluides non hyperbolique, en 3d sur des maillages non structures ; la gamme des taux de vide est accessible numériquement sur presque toute son étude ; l'efficacité du traitement implicite en temps pour atteindre des états stationnaires est démontrée.
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Zaza, Chady. "Contribution à la résolution numérique d'écoulements à tout nombre de Mach et au couplage fluide-poreux en vue de la simulation d'écoulements diphasiques homogénéisés dans les composants nucléaires." Thesis, Aix-Marseille, 2015. http://www.theses.fr/2015AIXM4701.
Abstract:
Le calcul d'écoulements dans les générateurs de vapeur des réacteurs à eau pressurisée est un problème complexe, faisant intervenir différents régimes d'écoulement et plusieurs échelles de temps et d'espace. Un scénario accidentel peut être caractérisé par des variations très rapides pour un nombre de Mach de l'ordre de l'unité. A l'inverse en régime nominal l'écoulement peut être stationnaire, à bas nombre de Mach. De plus quelque soit le régime considéré, la complexité de la géométrie d'un générateur de vapeur conduit à modéliser le faisceau de tubes par un milieu poreux, d'où le problème de couplage à l'interface avec le milieu fluide.Un schéma de correction de pression tout-Mach en volumes finis colocalisés a été introduit pour les équations d'Euler et de Navier-Stokes. L'existence d'une solution discrète, la consistance du schéma au sens de Lax et la positivité de l'énergie interne ont été démontrées. Le schéma a été ensuite étendu aux modèles diphasiques homogènes du code GENEPI développé au CEA. Enfin un algorithme Multigrille-AMR a été adaptée pour permettre de mettre en oeuvre notre schéma sur des maillages adaptatifs.Concernant la seconde problématique, une extension de la loi de Beavers-Joseph a été proposée pour le régime convectif. En introduisant un saut d'énergie cinétique à l'interface, on retrouve une loi de type Beavers-Joseph mais avec un coefficient de glissement non-linéaire, qui dépend de la vitesse fluide à l'interface et de la vitesse Darcy. La validité de cette nouvelle condition d'interface a été évaluée en réalisant des calculs de simulation numérique directe à différents nombres de ReynoldsThe numerical simulation of steam generators of pressurized water reactors is a complex problem, involving different flow regimes and a wide range of length and time scales. An accidental scenario may be associated with very fast variations of the flow with an important Mach number. In contrast in the nominal regime the flow may be stationary, at low Mach number. Moreover whatever the regime under consideration, the array of U-tubes is modelled by a porous medium in order to avoid taking into account the complex geometry of the steam generator, which entails the issue of the coupling conditions at the interface with the free-fluid.We propose a new pressure-correction scheme for cell-centered finite volumes for solving the compressible Navier-Stokes and Euler equations at all Mach number. The existence of a discrete solution, the consistency of the scheme in the Lax sense and the positivity of the internal energy were proved. Then the scheme was extended to the homogeneous two-phase flow models of the GENEPI code developed at CEA. Lastly a multigrid-AMR algorithm was adapted for using our pressure-correction scheme on adaptive grids.Regarding the second issue addressed in this work, an extension to the Beavers-Joseph law was proposed for the convective regime. By introducing a jump in the kinetic energy at the interface, we recover an interface condition close to the Beavers-Joseph law but with a non-linear slip coefficient, which depends on the free-fluid velocity at the interface and on the Darcy velocity. The validity of this new transmission condition was assessed with direct numerical simulations at different Reynolds numbers
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Nguyen, Truong B. "Efficient Numerical Methods For Chemotaxis And Plasma Modulation Instability Studies." Wright State University / OhioLINK, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=wright1564487925507593.
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Zerguine, Walid. "Adaptation de maillages anisotropes et écoulements multifluides : Applications en injection assistée eau." Paris, ENMP, 2010. http://www.theses.fr/2010ENMP0082.
Abstract:
L’Injection Assistée Eau (IAE) est un procédé récent de fabrications de pièces creuses thermoplastiques. La simulation numérique est une étape importante du processus de mise au point de cette technologie innovante. Le cadre de ces travaux de thèse est le développement d’un module de simulation numérique du procédé IAE. Les retombées industrielles et technologiques de cet outil numérique apporteront des informations cruciales sur la sensibilité des propriétés des pièces injectées aux conditions d’injection. L’hydrodynamique du système multiphasique polymère-eau-air est décrite par la résolution des équations de Navier-Stokes dans le cadre d’une formulation monolithique eulérienne. La méthode consiste à résoudre le système d’équations sur un seul maillage. Une fonction distance permet de décrire les interfaces eau-polymère et polymère-air, et de fournir les propriétés physiques de chaque sous-domaine. Une stratégie innovante d’adaptation dynamique de maillage anisotrope permet de diminuer les fortes hétérogénéités des phases en présence. Deux voies sont explorées. La première considère des maillages définis à partir de métriques construites a priori sur le gradient de la fonction Level set et la seconde approche considère la construction d’une métrique basée sur un estimateur d’erreur a posteriori minimisant l’erreur d’approximation sous contrainte de garder un nombre d’éléments constant. Une confrontation à des essais expérimentaux valide la pertinence de notre outil à prédire de manière précise l’évolution de la veine d’eau dans la pièce type IAEThe Water Assisted Injection Molding (WAIM) is a recent manufacturing process that produces thermoplastic hollow parts. Numerical simulation is an important step in the development of this innovative technology. The framework of the thesis is the development of a numerical simulation module for the WAIM process. The industrial and technological benefits of this numerical tool will provide crucial information on the sensitivity of the properties of injection molded parts to injection conditions. The hydrodynamics of the multiphase polymer-water-air system is described by the resolution of the Navier-Stokes equations within the framework of an eulerian monolithic formulation. The method consists in solving the system of equations on a single mesh. A distance function allows to describe the interfaces water-polymer and polymer-air to supply the physical properties of every sub-domain. A strategy of anisotropic dynamic mesh adaptation allows to decrease the strong heterogeneities of the phases in presence. Two ways are investigated. The first one considers meshes constructed from a priori metrics based on the gradient of the Levelset function and the second approach considers the construction of a metric based on a posteriori error estimator minimizing the error of approximation under constraint to keep a constant number of elements. A confrontation in experimental trials confirms the relevance of our tool to predict the evolution of the water vein in a typical WAIM part
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Utzinger, Johannes. "Analysis and computation of solid interfaces on the meso scale." Kaiserslautern Techn. Univ., Lehrstuhl für Techn. Mechanik, 2008. http://d-nb.info/997953586/34.
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Carli, Marta. "Meso- and nano-structured metal-dielectric interfaces for plasmonic nanofocusing." Doctoral thesis, Università degli studi di Padova, 2013. http://hdl.handle.net/11577/3423458.
Abstract:
With increasing demand for nanoscale optical devices, the ability to confine the light on length scales smaller than those allowed by the diffraction limit of light has begun to attract enormous interest. A possible solution to this problem is offered by Plasmonics.
Under certain conditions, a metal-dielectric interface supports Surface Plasmons (SPs), i.e. electromagnetic excitations strongly coupled to oscillations of free electrons in the metal. Thanks to these excitations, electromagnetic energy can be confined in a sub-wavelength volume close to the metal surface. This opens up the way for a wide range of opportunities and applications, from photovoltaics to biosensing.
The focus of this thesis was to engineer metal-dielectric interfaces in order to excite plasmonic hotspots, i.e. nanometer-sized regions where the electromagnetic field is strongly enhanced. As hinted above, this can be achieved by conveniently meso- and/or nano-structuring the metal surface. The properties of metal-dielectric interfaces emerging from these studies are of particular interest in the field of molecular sensing, but are also of more fundamental interest.
Different classes of devices are proposed. We started from digital plasmonic gratings, studying their excitation modes thoroughly. We then moved to nanostructures supporting a Localized Surface Plasmon Resonance (LSPR), specifically plasmonic nanoantennae, which are of special interest for the enhancement of well-established sensing techniques such as SERS. Coming to nanofocusing, we studied plasmonic wedges – which provide adiabatic nanofocusing at their ridge – as well as bull’s eye/Archimedean spiral structures, which can generate and focus Surface Plasmons carrying orbital angular momentum (OAM). Finally, we proposed a non-trivial integration of the above-mentioned effects, in the form of an Archimedean spiral coupled to nanoantenna resonators.
In parallel, we collaborated with the company A.P.E. Research to develop a new characterization instrument, called EllipsSNOM. It consists in implementing a SNOM head on a J.A. Woollam Co. Inc. Variable Angle Spectroscopic Ellipsometer (VASE). This challenging task was pursued in order to get simultaneous control of the far field and the near field properties of the structures; ellipsometry and SNOM microscopy are indeed both essential techniques to achieve a full characterization of plasmonic nanodevices.All’aumentare della richiesta di dispositivi ottici di scala nanometrica, la possibilità di confinare la luce su scale di lunghezza inferiori a quelle consentite dal limite di diffrazione della luce ha iniziato ad attrarre un enorme interesse. Una possibile soluzione a questo problema è offerta dalla Plasmonica. In determinate condizioni, un'interfaccia metallo-dielettrico supporta Plasmoni di Superficie (SP), cioè eccitazioni elettromagnetiche fortemente accoppiate alle oscillazioni degli elettroni liberi nel metallo. Grazie a queste eccitazioni, l’energia elettromagnetica può essere confinata in un volume di dimensioni inferiori alla lunghezza d’onda della luce vicino alla superficie metallica. Questo apre la strada a una vasta gamma di opportunità e applicazioni, dal fotovoltaico alla biosensoristica. L’obiettivo di questa tesi è stato progettare interfacce metallo-dielettrico al fine di eccitare hotspot plasmonici, cioè regioni di dimensioni nanometriche dove il campo elettromagnetico è fortemente potenziato. Come accennato sopra, questo può essere ottenuto meso- e/o nano-strutturando opportunamente la superficie del metallo. Le proprietà delle interfacce metallo-dielettrico che emergono da questi studi sono di particolare interesse nel campo della sensoristica, ma sono anche di interesse più fondamentale. Sono proposte diverse classi di dispositivi. Siamo partiti da reticoli plasmonici digitali, studiando a fondo i loro modi di eccitazione. Ci siamo poi spostati su nanostrutture che supportano una Risonanza Plasmonica di Superficie Localizzata (LSPR), nello specifico nanoantenne plasmoniche, che sono di particolare interesse per il potenziamento di tecniche sensoristiche ben consolidate come il SERS. Venendo poi al nanofocusing, abbiamo studiato strutture plasmoniche tipo wedges (cunei) – che forniscono nanofocusing adiabatico sulla loro cresta – e strutture tipo bull’s eye/spirali di Archimede, in grado di generare e focalizzare Plasmoni Superficiali che trasportano momento angolare orbitale (OAM). Infine, abbiamo proposto un'integrazione non banale degli effetti sopra citati, in forma di una spirale di Archimede accoppiata a una nanoantenna. In parallelo, abbiamo collaborato con la ditta A.P.E. Research per sviluppare un nuovo strumento di caratterizzazione, chiamato EllipsSNOM. Esso consiste nell’implementazione di una testa SNOM su un ellissometro spettroscopico J.A. Woollam Co. Inc. Variable Angle Spectroscopic Ellipsometer (VASE). Questo intrigante obiettivo è stato perseguito al fine di ottenere il controllo simultaneo delle proprietà di campo lontano e di campo vicino delle strutture; ellissometria e microscopia SNOM sono infatti entrambe tecniche essenziali per realizzare una completa caratterizzazione dei nanodispositivi plasmonici.
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Gonzales, Candy Veronica Tenorio. "Marmoreio digital com interface natural." reponame:Repositório Institucional da UFABC, 2017.
Abstract:
Orientador: Prof. Dr. Mario Alexandre GazziroDissertação (mestrado) - Universidade Federal do ABC, Programa de Pós-Graduação em Ciência da Computação, 2017.
Marmoreio em papel é um método de design principalmente utilizado por artistas desenvolvedores de capas de livros, no qual tinta a base de óleo é depositada sobre uma superfície aquosa, de forma a produzir padrões texturais semelhantes à do mármore. Os padrões são o resultado da flutuação dos pigmentos de tinta sobre a água definidos pelos movimentos manuais do artista que, em seguida, é cuidadosamente transferido para uma superfície de papel ou tecido absorvente. Apesar do fato de alguns sistemas digitais de marmoreio já terem sido desenvolvidos no passado, nenhum deles pôde fornecer simultaneamente uma interface natural ao usuário e uma simulação em tempo real. Este trabalho obteve a melhora do processo de marmoreio digital através de uma interface fácil de aprender, apresentando simultaneamente características de resposta rápida e de fácil navegação através de uma caneta digital, usando uma mesa digitalizadora como superfície de design, processando algoritmos na GPU por meio de programas shaders para os cálculos de dinâmica computacional de fluidos, envolvendo resolução em tempo real das Equações de Navier-Stokes.
Paper marbling is a design method mainly used by artists who develop book covers, in which is deposited oil-based paint on an aqueous surface in order to produce textured patterns like marble. The patterns are the result of the fluctuation of the ink pigments on the water defined by the artist¿s manual movements which is then carefully transferred to a surface o f absorbent paper or fabric. Although some digital marbling systems have already been developed in the past, none of them could simultaneously provide a natural user interface and real time simulation. This work improvement of the digital marbling process through an easy to learn interface, simultaneously presenting fast response characteristics and easy navigation through of a pen stylus, using a pen tablet as a design surface, processing GPU algorithms using shaders to calculate computational fluids dynamics, involving real time resolution of the Navier-Stokes equations.
32
Zhang, Kai. "Carbon nanotube thermal interface material and its application in high brightness LED packages /." View abstract or full-text, 2008. http://library.ust.hk/cgi/db/thesis.pl?MECH%202008%20ZHANG.
33
Chan, Edward King-Long. "A study of moisture diffusion at the epoxy/copper interface for plastic IC packages /." View abstract or full-text, 2006. http://library.ust.hk/cgi/db/thesis.pl?MECH%202006%20CHAN.
34
Dong, Liang. "Interface morphology and its stability in martensitic phase transformation of NiTi shape memory alloy /." View abstract or full-text, 2008. http://library.ust.hk/cgi/db/thesis.pl?MECH%202008%20DONG.
35
Mohaghegh, Fazlolah. "A parallelized diffuse interface solver with applications to meso scale simulation of suspensions." Diss., University of Iowa, 2017. https://ir.uiowa.edu/etd/5971.
Abstract:
The ultimate goal of this research is to develop the capability of direct numerical simulation of a flow containing numerous rigid finite size particles. In order to reach this goal, we have implemented the smoothed profile method (SPM) in the University of Iowa in-house solver, pELAFINT3D and overcame several challenges related to the method. This includes a proposed formulation for the interface thickness and many validations and comparisons with experimental data as well as with a second-order accurate sharp interface method. As one of the issues related to low-density particles is the instability, SPM has been improved by developing to a fully implicit scheme. Moreover, use of higher order integration formulation and implementation of Euler parameters have been shown to be helpful in stabilization of the calculations.
To preserve the efficiency when the number of the particles increases, local mesh refinement is shown to be a very effective tool. A revised version of SPM that has only one projection step is proposed to improve the efficiency of the method. A comprehensive efficiency study is performed and it has been shown that the new method is less expensive in problems with high added mass effect when strongly coupled fluid-structure interaction schemes are used. Moreover, the code is massively parallelized using MPI and PETSc libraries. The parallelization includes I/O, operations leading to construction of the linear solver as well as the solver itself.
Simulation of a particle laden flow involves particles collisions. Two novel collision models are suggested which are able to avoid particle overlapping for arbitrary shape particles. The methods are efficient as they are not involved with extra grid refinement related to implementing lubrication forces. The issue of handling continuously changing number of particles in a particle laden flow is solved by implementation of a linked list data structure for the particles.
By studying a flow over a constricted region we showed that the platelets’ activation is more likely to happen for the particles that pass from the middle of the upper bump region because those particles will have longer exposure time to the high shear flow behind the bump. PDF contour of particles’ presence show the more concentrated presence of the particles near the bump. Moreover, the interaction of RBCs and platelets pushes the platelets toward the wall after the bottom wall.
36
Chung, Paular Wai Kwan. "Interfacial adhesion between epoxy molding compound and copper leadframe under different thermal conditions /." View Abstract or Full-Text, 2002. http://library.ust.hk/cgi/db/thesis.pl?MECH%202002%20CHUNGP.
Abstract:
Thesis (M. Phil.)--Hong Kong University of Science and Technology, 2002.Includes bibliographical references (leaves 111-114). Also available in electronic version. Access restricted to campus users.
37
Utzinger, Johannes [Verfasser]. "Analysis and computation of solid interfaces on the meso scale / Johannes Utzinger." Kaiserslautern : Techn. Univ., Lehrstuhl für Techn. Mechanik, 2008. http://d-nb.info/997953586/34.
38
Mateus, Bruno Miguel Jesus. "CuboChef: mesa inteligente e interactiva para cozinhas domésticas." Master's thesis, Universidade da Beira Interior, 2012. http://hdl.handle.net/10400.6/1548.
Abstract:
Actualmente, devido à evolução da tecnologia, é cada vez mais recorrente a procura de soluções de interacção mais naturais com o computador. Neste sentido surgem as superfícies com tecnologia multitoque que estão cada vez mais presentes no quotidiano do ser humano, tanto ao nível pessoal, como empresarial ou social.
Este relatório apresenta a evolução da tecnologia multitoque, tanto ao nível de hardware como de software, desde a sua criação até ao estado de desenvolvimento actual, analisando de forma mais detalhada as tecnologias actuais de construção e funcionamento destes sistemas. Esta análise possibilitou obter o conhecimento necessário para construir um protótipo de uma mesa com tecnologia multitoque, recorrendo a um sistema de construção de baixo custo e com um funcionamento estável.
Para além da construção do protótipo da mesa, desenvolveu-se ainda uma aplicação interactiva no Adobe Flash Cs6 e programada em Action Script 3, que em conjunto com o protótipo da mesa resultou no projecto final de Mestrado em Design Multimédia.
Este projecto final consiste na concepção de uma mesa inteligente e interactiva (através de toque e gestos), que pretende facilitar e dinamizar as tarefas realizadas nas cozinhas domésticas (ex.: receitas, informação dos alimentos e compras online), oferecendo ainda uma nova dinâmica a este espaço com a introdução de pequenas subaplicações que permitem criar não só um ambiente de bem-estar e lazer (ex.: musica e jogos), mas também um ambiente de produtividade pessoal e profissional (ex.: e-mail, notícias e redes sociais).Currently, due to the evolution of technology, the demand for solutions that allow a more natural interaction with the computer becomes increasingly frequent. Thus it’s natural that multitouch technology surfaces and interfaces become increasingly present in our daily lives, at a personal, entrepreneurial as well as social level. This report presents the evolution of multitouch technology, regarding both hardware and software, from its inception to the present stage of development, analyzing in more detail the current technologies of construction and operation of these systems. This analysis allowed us to obtain the knowledge needed to build a prototype of a table with multitouch technology, using a construction system with low cost and stable operation. Besides building the table prototype, we also developed an interactive application in Adobe Flash Cs6 and programmed in Action Script 3, which together with the prototype of the table resulted in the final project to achieve our Master’s degree in Multimedia Design. This final project consists in the design of an interactive and intelligent table (through touch and gesture), which aims to facilitate and give dynamism to the tasks performed in domestic kitchens (e.g. recipes, food information and online shopping), presenting a new dynamic to this space with the introduction of small sub-applications that allow not only create an atmosphere of well-being and entertainment (e.g. music and games), but also an environment of personal and professional productivity (e.g. e-mail, news and social networks).
39
Hassan, Sahar. "Intégration de connaissances anatomiques a priori dans des modèles géométriques." Phd thesis, Université de Grenoble, 2011. http://tel.archives-ouvertes.fr/tel-00607260.
Abstract:
L'imagerie médicale est une ressource de données principale pour différents types d'applications. Bien que les images concrétisent beaucoup d'informations sur le cas étudié, toutes les connaissances a priori du médecin restent implicites. Elles jouent cependant un rôle très important dans l'interprétation et l'utilisation des images médicales. Dans cette thèse, des connaissances anatomiques a priori sont intégrées dans deux applications médicales. Nous proposons d'abord une chaîne de traitement automatique qui détecte, quantifie et localise des anévrismes dans un arbre vasculaire segmenté. Des lignes de centre des vaisseaux sont extraites et permettent la détection et la quantification automatique des anévrismes. Pour les localiser, une mise en correspondance est faite entre l'arbre vasculaire du patient et un arbre vasculaire sain. Les connaissances a priori sont fournies sous la forme d'un graphe. Dans le contexte de l'identification des sous-parties d'un organe représenté sous forme de maillage, nous proposons l'utilisation d'une ontologie anatomique, que nous enrichissons avec toutes les informations nécessaires pour accomplir la tâche de segmentation de maillages. Nous proposons ensuite un nouvel algorithme pour cette tâche, qui profite de toutes les connaissances a priori disponibles dans l'ontologie.
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AGHINA, Mauricio Alves da Cunha e. "Interfaces naturais para interação com uma mesa de controle virtual de um simulador de uma usina nuclear." reponame:Repositório Institucional do IEN, 2012. http://hdl.handle.net/ien/808.
Abstract:
Submitted by Almir Azevedo (barbio1313@gmail.com) on 2014-08-08T13:19:37Z
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MAURICIO ALVES DA CUNHA E AGHINA_D_2012.pdf: 3967079 bytes, checksum: 4967d16b666f01de68d7c1b24d6591d4 (MD5)Made available in DSpace on 2014-08-08T13:19:37Z (GMT). No. of bitstreams: 1 MAURICIO ALVES DA CUNHA E AGHINA_D_2012.pdf: 3967079 bytes, checksum: 4967d16b666f01de68d7c1b24d6591d4 (MD5) Previous issue date: 2012
Devido as normas muito rígidas de segurança de operação de uma usina nuclear, os operadores, tem que ser muito bem treinados, para que possam opera-la dentro dos procedimentos de segurança necessários. Este treinamento é feito através de simuladores, que possibilitam a operação do usuário, a mais próxima possível de uma mesa de controle real, e que possam ser inseridas situações de acidentes, para que eles treinem, como voltar a usina para uma condição normal de funcionamento. Normalmente são utilizados dois tipos de simulador.: O desejado é o full scope que é um simulador computacional da dinâmica da usina usado em conjunto com a réplica física da mesa de controle, mas este tipo de simulador envolve um alto custo de construção. O segundo tipo é o que usa janelas sinópticas de varias regiões da mesa de controle original, o seu custo de construção é menor, mas tem uma fidelidade menor com a aparência da mesa original. Atualmente, com o uso da realidade virtual as mesas de controle podem ser modeladas em 3D, fazendo com que a interface do simulador seja bem parecida com a aparência da mesa de controle original e com um baixo custo de construção. Este trabalho mostra o uso de interfaces naturais para interação do operador com a mesa virtual, com o intuito que ele não use nenhum dispositivo mecânico para a visualização e atuação com a mesa virtual. Para isto foram usados procedimentos, tais como: visão computacional para reconhecimento da posição de observação do operador, de suas mãos para a atuação dos controles da mesa e reconhecimento de voz.
Due to very strict standards of safe operation of a nuclear power plant operators must be well trained so they can operate it within the necessary safety procedures. This is done through training simulators, which enable the user operation, as close as possible to the real control desk, and can be inserted accident situations, so they train, how to return the plant to a normal operating condition. Normally is used two types of simulator. Preferred is the full scope simulator, what is a computational dynamics program of the plant used in conjunction with a physical replica of the control desk, but this type of simulator involves a high construction cost. The second type is what uses synoptic windows of various regions of the original control desk, its construction cost is smaller, but it have a little fidelity to the original appearance of the table. Currently, with the use of virtual reality, control desks can be modeled in 3D, making the simulator interface is very similar to the appearance of the real control desk with a low cost construction. This work shows the use of natural interfaces for operator interaction with the virtual control desk, in order that it does not use any mechanical device for displaying and acting with it. For procedures that were used, such as: computer vision to recognize the position of the operator's and observation of their hands to the work of the desk controls and voice recognition.
41
Sencu, Razvan. "Multiscale stochastic fracture mechanics of composites informed by in-situ X-ray CT tests." Thesis, University of Manchester, 2017. https://www.research.manchester.ac.uk/portal/en/theses/multiscale-stochastic-fracture-mechanics-of-composites-informed-by-insitu-xray-ct-tests(85a0be40-9e7a-4df3-a366-69ac6ce02e35).html.
Abstract:
This thesis presents the development of a new multiscale stochastic fracture mechanics modelling framework informed by in-situ X-ray Computed Tomography (X-ray CT) tests, which can be used to enhance the quality of new designs and prognosis practices for fibre reinforced composites. To reduce the empiricism and conservatism of existing methods, this PhD research systematically has tackled several challenging tasks including: (i) extension of the cohesive interface crack model to multi-phase composites in both 2D and 3D, (ii) development of a new in-house loading rig to support in-situ X-ray CT tests, (iii) reconstruction of low phase-contrast X-ray CT datasets of carbon fibre composites, (iv) integration of X-ray CT image-based models into detailed crack propagation FE modelling and (v) validation of a partially informed multiscale stochastic modelling method by direct comparison with in-situ X-ray CT tensile test results.
42
Martins, Filipe. "Multitouch para ambientes de cozinha: CuboChef." Master's thesis, Universidade da Beira Interior, 2012. http://hdl.handle.net/10400.6/1549.
Abstract:
A mesa CuboChef insere-se no âmbito da tecnologia interactiva multitouch e foi desenvolvida na Universidade da Beira Interior, mais precisamente no Laboratório de Instalações Multimédia Interactivas (LIMI), no âmbito do mestrado em Design Multimédia.
Aproveitando uma tecnologia inovadora e em franca expansão, o projecto traça como objectivo a construção de uma mesa multitouch e respectivas aplicação e mini-aplicações, destinada a ajustar ao ambiente de uma cozinha futurista, permitindo melhorar a qualidade de vida do seu utilizador, facilitando tarefas quotidianas como cozinhar, encomendar refeições já prontas, comprar alimentos em falta e, paralelamente, obter informação complementar sobre estes produtos e encontrar opções divertidas para ocupar tempos de espera.CuboChef table was developed with interactive multitouch technology at University of Beira Interior’s LIMI (Multimedia Interactive Installations Lab), within the master of Multimedia Design. Applying an innovative technology in constant evolution, this Project sets as a primal goal the construction of a multitouch table and respective application and mini-applications, aimed to set on a futuristic kitchen and allow the life quality of its user(s) through the simplification of daily tasks such as cooking, ordering take-away, buying food and, at the same time, obtaining information about all these products and finding entertaining choices to occupy all the waiting times.
43
Wang, Wenfeng. "Investigation of Energy Alignment Models at Polymer Interfaces." Scholar Commons, 2014. https://scholarcommons.usf.edu/etd/5148.
Abstract:
The presented study investigated the Induced Density of Interface States (IDIS) model at different polymer interfaces by using photoemission spectroscopy in combination with electrospray deposition.
In recent years, organic electronics have attracted considerable attention due to their advantages of low-cost and easy-fabrication. The performance of such devices crucially depends on the energy barrier that controls the interface charge transfer. A significant effort has been made to explore the mechanisms that determine the direction and magnitude of charge transfer barriers in these devices. As a result of this effort, the IDIS model was developed to predict the energy alignment at metal/organic and organic/organic interfaces. The validity of the IDIS model on molecular interfaces was confirmed by the results of a series of experiments with small molecular materials, which are in good agreement with the theoretical calculations from the IDIS model. The charge neutrality level (CNL) and screening factor for various organic materials can be determined from the linear correlation between the hole injection barrier at metal/organic interface and the work function of its corresponding metal substrate, which stands as one of the most important features of the IDIS model.
The study presented here explores whether the IDIS model is also valid for polymer interfaces. Two prototypical polymer materials: poly(3-hexylthiophene) (P3HT) and poly[2-methoxy-5-(2'-ethylhexyloxy)-p-phenylene vinylene] (MEH-PPV) were selected for the investigation. In the first part of this study, a series of metal/polymer interfaces were prepared using electrospray and investigated with photoemission
spectroscopy. The linear relationship between the hole barriers extracted from the metal/polymer interface and the work function of its respective metal substrate suggests that the IDIS model is also valid for metal/polymer interfaces. The CNLs and the screening factors of P3HT and MEH-PPV are determined respectively. The experiment results are also discussed with regard to the Integer Charge Transfer (ICT) model. The comparison between the two models suggests that the IDIS model should be applied to interfaces prepared in vacuum while the ICT model works on interfaces with an ambient contamination layer present. The second part of the dissertation discusses the photoemission results of the MEH-PPV/P3HT heterojunction from the perspectives of the two models. The results indicate that the IDIS model is valid for polymer/polymer heterojunctions. The IDIS model more accurately predicted the measured orbital line up by using its principles for organic/organic heterojunction than the ICT model.
44
Todescato, Francesco. "Functional dielectric/semiconductor and metal/semiconductor interfaces in organic field-effect transistors." Doctoral thesis, Università degli studi di Padova, 2007. http://hdl.handle.net/11577/3425125.
Abstract:
The work presented in this thesis focuses on the investigation of two interfaces which play a crucial role in the physics of organic electronic devices: the dielectric/organic semiconductor and the organic semiconductor/metal ones.
Regarding the dielectric/OS interface, we have deeply investigated the relationship between the SiO2 cleaning protocol or treatment and the electrical response of OFETs based on two PPV semiconducting polymers (MEH-PPV and OC1C10-PPV) and on a quarterthiopene derivative small molecule (DHCO-4T).
Regarding the OS/metal interface, we investigated the electrical performances of PPV and DHCO-4T based OFETs with different metal contacts.
45
Kaiser, Benjamin [Verfasser]. "A generalised interface for multi-level coupling of beam unit cell meso-models to macro finite elements in draping simulation / Benjamin Kaiser." Düren : Shaker, 2020. http://d-nb.info/1220610003/34.
46
Zhang, Qing. "HIGH QUALITY HUMAN 3D BODY MODELING, TRACKING AND APPLICATION." UKnowledge, 2015. http://uknowledge.uky.edu/cs_etds/39.
Abstract:
Geometric reconstruction of dynamic objects is a fundamental task of computer vision and graphics, and modeling human body of high fidelity is considered to be a core of this problem. Traditional human shape and motion capture techniques require an array of surrounding cameras or subjects wear reflective markers, resulting in a limitation of working space and portability. In this dissertation, a complete process is designed from geometric modeling detailed 3D human full body and capturing shape dynamics over time using a flexible setup to guiding clothes/person re-targeting with such data-driven models. As the mechanical movement of human body can be considered as an articulate motion, which is easy to guide the skin animation but has difficulties in the reverse process to find parameters from images without manual intervention, we present a novel parametric model, GMM-BlendSCAPE, jointly taking both linear skinning model and the prior art of BlendSCAPE (Blend Shape Completion and Animation for PEople) into consideration and develop a Gaussian Mixture Model (GMM) to infer both body shape and pose from incomplete observations. We show the increased accuracy of joints and skin surface estimation using our model compared to the skeleton based motion tracking. To model the detailed body, we start with capturing high-quality partial 3D scans by using a single-view commercial depth camera. Based on GMM-BlendSCAPE, we can then reconstruct multiple complete static models of large pose difference via our novel non-rigid registration algorithm. With vertex correspondences established, these models can be further converted into a personalized drivable template and used for robust pose tracking in a similar GMM framework. Moreover, we design a general purpose real-time non-rigid deformation algorithm to accelerate this registration. Last but not least, we demonstrate a novel virtual clothes try-on application based on our personalized model utilizing both image and depth cues to synthesize and re-target clothes for single-view videos of different people.
47
Erias, Morandeira Felipe. "Emergent IoT configurations for same-place collaboration." Thesis, Malmö högskola, Fakulteten för kultur och samhälle (KS), 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:mau:diva-21437.
Abstract:
This thesis project describes a system to make presentations more collaborative, consisting on a mobile application using mesh technology.The mesh network may be set up through the choreography of interaction created by attendees tapping their phones together at the start of the meeting. The fluid workflow for requesting and handing over control of the projector encourages sharing and makes the interaction between presenter and audience more collaborative.The design was evaluated through a collaborative session that pointed at several future lines of work. Furthermore, we found opportunities to leverage the use of mesh networks in the workplace.Finally, we carried out two explorations of the use of projectors and movement capture for the creation of visual content. This, along with the previous work, served as a base for the argument that there is an opportunity to discover rich interaction possibilities in the combination of small, modular IoT devices to create augmented spaces.
48
Beckstein, Pascal. "Methodenentwicklung zur Simulation von Strömungen mit freier Oberfläche unter dem Einfluss elektromagnetischer Wechselfelder." Doctoral thesis, Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2018. http://nbn-resolving.de/urn:nbn:de:bsz:14-qucosa-232474.
Abstract:
Im Bereich der industriellen Metallurgie und Kristallzüchtung treten bei zahlreichen Anwendungen, wo magnetische Wechselfelder zur induktiven Beeinflussung von leitfähigen Werkstoffen eingesetzt werden, auch Strömungen mit freier Oberfläche auf. Das Anwendungsspektrum reicht dabei vom einfachen Aufschmelzen eines Metalls in einem offenen Tiegel bis hin zur vollständigen Levitation. Auch der sogenannte RGS-Prozess, ein substratbasiertes Kristallisationsverfahren zur Herstellung siliziumbasierter Dünnschichtmaterialien, ist dafür ein Beispiel. Um bei solchen Prozessen die Interaktion von Magnetfeld und Strömung zu untersuchen, ist die numerische Simulationen ein wertvolles Hilfsmittel. Für beliebige dreidimensionale Probleme werden entsprechende Berechnungen bisher durch eine externe Kopplung kommerzieller Programme realisiert, die für Magnetfeld und Strömung jeweils unterschiedliche numerische Techniken nutzen. Diese Vorgehensweise ist jedoch im Allgemeinen mit unnötigem Rechenaufwand verbunden. In dieser Arbeit wird ein neu entwickelter Methodenapparat auf Basis der FVM vorgestellt, mit welchem sich diese Art von Berechnungen effizient durchführen lassen. Mit der Implementierung dieser Methoden in foam-extend, einer erweiterten Version der quelloffenen Software OpenFOAM, ist daraus ein leistungsfähiges Werkzeug in Form einer freien Simulationsplattform entstanden, welches sich durch einen modularen Aufbau leicht erweitern lässt. Mit dieser Plattform wurden in foam-extend auch erstmalig dreidimensionale Induktionsprozesse im Frequenzraum gelöst.
49
Zhang, Ziyu. "Finite Element Methods for Interface Problems with Mesh Adaptivity." Diss., 2015. http://hdl.handle.net/10161/11316.
Abstract:
This dissertation addresses interface problems simulated with the finite element method (FEM) with mesh adaptivity. More specifically, we concentrate on the strategies that adaptively modify the mesh and the associated data transfer issues.
In finite element simulations there often arises the need to change the mesh and continue the simulation on a new mesh. Analysts encounter such an issue when they adaptively refine the mesh to reduce the computational cost, smooth distorted elements to improve system conditioning, or introduce new surfaces and change the domain in simulations of fracture problems. In such circumstances, the transfer of data from the old mesh to the new one is of crucial importance, especially for nonlinear problems. We are concerned in this work with contact problems with adaptive re-meshing and fracture problems modeled with the eXtended finite element method (X-FEM). For the former ones, the transfer of surface data is built upon the technique of parallel transport, and the error of such a transfer strategy is investigated through classic benchmark tests. A transfer scheme based on a least squares problem is also proposed to transfer the bulk data when nearly incompressible hyperelastic materials are employed. For the latter type of problems, we facilitate the transfer of internal variables by making partial elements utilize the same quadrature points from the uncut parent elements and meanwhile adjusting the quadrature weights via the solution of moment fitting equations. The proposed scheme helps avoid the complicated remapping procedure of internal variables between two different sets of quadrature points. A number of numerical examples are presented to demonstrate the robustness and accuracy of our proposed approaches.
Another renowned technique to simulate fracture problems is based upon the phase-field formulation, where a set of coupled mechanics and phase-field equations are solved via FEM without modeling crack geometries. However, losing the ability to model distinct surfaces in the phase-field formulation has drawbacks, such as difficulties simulating contact on crack surfaces and poorly-conditioned stiffness matrices. On the other hand, using the pure X-FEM in fracture simulations mandates the calculation of the direction and increment of crack surfaces at each step, introducing intricacies of tracing crack evolution. Thus, we propose combining phase-field and X-FEM approaches to utilize their individual benefits based on a novel medial-axis algorithm. Consequently, we can still capture complex crack geometries while having crack surfaces explicitly modeled by modifying the mesh with the X-FEM.
Dissertation
50
Chen, Ying-Yu, and 陳盈羽. "Interface Constraint Aware Channel Assignment Algorithms in Wireless Mesh Networks." Thesis, 2015. http://ndltd.ncl.edu.tw/handle/07681389733309161999.
Abstract:
博士國立交通大學
資訊科學與工程研究所
103
The channel assignment problem in wireless mesh networks is considered in this thesis. Due to the limited number of radio interfaces that each node is equipped with, channel assignment must ensure that the interface constraint is obeyed, i.e., the number of different channels assigned to the links incident on a node must not exceed the number of interfaces the node is equipped with. However, interface constraint may be one of the causes that hinder the performance of some of the existing heuristics. This thesis contains two major parts. In the first part, we use simulated annealing to solve the channel assignment problem in wireless mesh networks. We consider using two neighbor generating approaches that handle the interface constraint in different ways. The first approach generates random solutions that need not conform to the interface constraint. With the incorporation of a penalty function technique, the solutions gradually converge to feasible solutions. The second approach allows only feasible solutions to be generated during the simulated annealing process. Simulations are conducted that compare our proposed simulated annealing algorithms with a tabu-based algorithm under different network settings and traffic scenarios. The results show that our algorithms exhibit improved network performance over the tabu-based algorithm. The second part of this thesis is motivated by the fact that although many channel assignment heuristics have been proposed, the interface constraint is usually treated as a separate constraint that is not well incorporated in the heuristics themselves. In the second part of this thesis, we propose a mixed hypergraph model that captures the interface constraint on nodes and the interference between links. Based on the proposed model, we develop a greedy-based channel assignment algorithm that minimizes the interference between links while conforming to the interface constraint. Simulation results show that our proposed algorithm performs noticeably well when the number of network interface cards is small.