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Published: 14 March 2023

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1

Yang, Xingzhou. "Immersed Interface Method for Elasticity Problems with Interfaces." NCSU, 2004. http://www.lib.ncsu.edu/theses/available/etd-07062004-175450/.

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An immersed interface method and an immersed finite element method for solving linear elasticity problems with two phases separated by an interface have been developed in this thesis. For the problem of interest, the underlying elasticity modulus is a constant in each phase but vary from phase to phase. The basic goal here is to design an efficient numerical method using a fixed Cartesian grid. The application of such a method to problems with moving interfaces driving by stresses has a great advantage: no re-meshing is needed. A local optimization strategy is employed to determine the finite difference equations at grid points near or on the interface. The bi-conjugate gradient method and the GMRES with preconditioning are both implemented to solve the resulting linear systems of equations and compared. The level set method is used to represent the interface. Numerical results are presented to show that the immersed interface method is second-order accurate.
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2

Amoah-Kusi, Christian. "Constant Interface Temperature Reliability Assessment Method: An Alternative Method for Testing Thermal Interface Material in Products." PDXScholar, 2015. https://pdxscholar.library.pdx.edu/open_access_etds/2295.

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As electronic packages and their thermal solutions become more complex the reliability margins in the thermal solutions diminish and become less tolerant to errors in reliability predictions. The current method of thermally stress testing thermal solutions can be over or under predicting end of life thermal performance. Benefits of accurate testing and modeling are improved silicon yield in manufacturing, improved performance, lower cost thermal solutions, and shortened test times. The current method of thermally stress testing is to place the entire unit in an elevated isothermal temperature and periodically measure thermal performance. Isothermally aging is not an accurate representation of how the unit will be used by the customer and does not capture the thermal gradients and mechanical stresses due to different coefficients of thermal expansion of the materials used in the thermal solution. A new testing system, CITRAM which is an acronym for Constant Interface Temperature Reliability Method, has been developed that uses an electronic test board. The approach captures the thermal and mechanical stresses accurately and improves test time by 20-30% as a result of automation. Through this study a difference in the two methods has been identified and the new CITRAM method should be adopted as current practice.
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3

SEIXAS, MARIA LUCIA ARRAES. "A MAP-BASED INTERFACE EVALUATION METHOD." PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIRO, 2004. http://www.maxwell.vrac.puc-rio.br/Busca_etds.php?strSecao=resultado&nrSeq=5793@1.

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CONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICO
A integração de informação geográfica e mapas digitais nos Sistemas de Informação Geográfica (SIGs) produz soluções para vários grupos de usuários. Vem crescendo o número de usuários não especializados que utilizam SIGs na Web ou em desktop para localizar endereços, planejar rotas, planejar viagens, encontrar lugares, e assim por diante. Estas aplicações menos complexas e destinadas a qualquer pessoa carecem fundamentalmente de avaliação, pois da qualidade da interação depende seu sucesso comercial. Apesar desta necessidade, praticamente não encontramos pesquisas sobre como avaliar estas aplicações mais simples de SIGs. Neste trabalho propomos um método de Inspeção Semiótica para Interfaces baseadas em Mapas (o ISIM) capaz de analisar o efeito de representações usadas nestas interfaces na comunicação da informação geográfica. O ISIM combina técnicas analíticas e empíricas. As técnicas analíticas são usadas para definir contextos de uso e perfis de usuários, bem como para interpretar observações empíricas. Técnicas empíricas são usadas em testes e entrevistas com usuários, para comparar parte dos dados obtidos com as técnicas analíticas. O ISIM, que inicialmente abrange dos SIGs apenas as interações baseadas em mapas, identifica uma classe de problemas básicos deste tipo de interação e, como é o caso de vários outros métodos semióticos, dá indicações sobre possibilidades de solução para eles.
The integration of digital maps and geographical information into Geographical Information Systems (GIS) produces solutions for several groups of users. There is an increasing number of non experts that use GIS on the Web or in desktop applications to locate addresses, plan routes and trips, find places, and so on. Less complex applications designed for general use critically need evaluation, because their commercial success depends heavily on the quality of human-computer interaction. In spite of such critical need, it is very hard to find research about how to evaluate these kinds of simpler applications. We propose a semiotic inspection method (whose acronym in Portuguese is ISIM) that analyzes the effect of representations in map-based interfaces to communicate geographic information. ISIM combines analytic and empirical techniques to carry out evaluations. Analytic techniques are used to define contexts of use and users' profiles, as well as to interpret empirical observations. ISIM also uses an empirical technique of tests and interviews with users. ISIM, whose scope encompasses only GIS map-based interaction, can identify a class of basic problems of interaction and, as is the case with many semiotic methods, hint at design solutions for them.
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4

Li, Zhilin. "The immersed interface method : a numerical approach for partial differential equations with interfaces /." Thesis, Connect to this title online; UW restricted, 1994. http://hdl.handle.net/1773/6761.

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5

Wiegmann, Andreas. "The explicit jump immersed interface method and interface problems for differential equations /." Thesis, Connect to this title online; UW restricted, 1998. http://hdl.handle.net/1773/5774.

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6

Yang, Chao-Yang Yang. "Formative evaluation method for website interface development." Thesis, Coventry University, 2005. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.436297.

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The overall aim of the research was to develop a low cost, tailorable, formative evaluation method for web designers. The last fifteen years has witnessed the rapid development of the World Wide' Web, an information resource that users surf and mine for work, leisure, entertainment and transaction purposes. Its evaluation as a computer based product has led to the assumption by some researchers, that web site and HCI usability are the same (Nielsen, 2000; Brinck, Gergle and Wood, 2002). This is reflected in many web site evaluation guidelines and instruments that characterise usability in terms of learnability, efficiency, memorability, errors and satisfaction (Rubin, 1994). However, the web is used differently from other software e.g. surfing the web is not necessarily task directed and users may access the Internet purely to obtain intellectual and emotional gratification (Spool et ai, 1999). Therefore, it is quite possible that what determines user satisfaction is very different in each context. Additionally, commerce plays a fundamental part in a lot of websites so that their goals may be different from conventional computer system design e.g. to increase the user base or encourage repeat visits. Further, with limited budgets, website designers are unlikely to involve their users during the design process and not all owebsite designers have access to an evaluator, appropriate testing facilities or evaluation knowledge to support their design. Given these arguments, this research developed and validated a low-cost evaluation 'ethod for web designers to use for formative evaluation, prior to site launch. The method addressed both HCI and commercial website goals such as the encouragement of repeat visits. To achieve this, a series of studies were conducted. Firstly, contemporary evaluation methods were evaluated to explore their possible limitations with respect to website design. T.hen the users' and designers' needs from websites and website evaluation methods were identified. This led to the development of a tai/orable method that could be applied to a wide range of small commercial websites, that took into account the issues users of websites were concerned about, and also designers' requirements of an evaluation method. The method was formalized as a set of guidelines, verified in the evaluation of a website. The potential usefulness of the method was then verified by demonstrations to selected website designers who confirmed it was useful, practical, and needed. In summary, this research contributes to knowledge firstly by identifying the need for 'designer friendly' evaluation methods in this context; secondly be showing the mismatch between current methods (based on Hel) and the requirements of website design and thirdly by producing a method to meet the need.
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7

He, Xiaoming. "Bilinear Immersed Finite Elements For Interface Problems." Diss., Virginia Tech, 2009. http://hdl.handle.net/10919/27819.

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In this dissertation we discuss bilinear immersed finite elements (IFE) for solving interface problems. The related research works can be categorized into three aspects: (1) the construction of the bilinear immersed finite element spaces; (2) numerical methods based on these IFE spaces for solving interface problems; and (3) the corresponding error analysis. All of these together form a solid foundation for the bilinear IFEs. The research on immersed finite elements is motivated by many real world applications, in which a simulation domain is often formed by several materials separated from each other by curves or surfaces while a mesh independent of interface instead of a body-fitting mesh is preferred. The bilinear IFE spaces are nonconforming finite element spaces and the mesh can be independent of interface. The error estimates for the interpolation of a Sobolev function in a bilinear IFE space indicate that this space has the usual approximation capability expected from bilinear polynomials, which is O(h²) in L² norm and O(h) in H¹ norm. Then the immersed spaces are applied in Galerkin, finite volume element (FVE) and discontinuous Galerkin (DG) methods for solving interface problems. Numerical examples show that these methods based on the bilinear IFE spaces have the same optimal convergence rates as those based on the standard bilinear finite element for solutions with certain smoothness. For the symmetric selective immersed discontinuous Galerkin method based on bilinear IFE, we have established its optimal convergence rate. For the Galerkin method based on bilinear IFE, we have also established its convergence. One of the important advantages of the discontinuous Galerkin method is its flexibility for both p and h mesh refinement. Because IFEs can use a mesh independent of interface, such as a structured mesh, the combination of a DG method and IFEs allows a flexible adaptive mesh independent of interface to be used for solving interface problems. That is, a mesh independent of interface can be refined wherever needed, such as around the interface and the singular source. We also develop an efficient selective immersed discontinuous Galerkin method. It uses the sophisticated discontinuous Galerkin formulation only around the locations needed, but uses the simpler Galerkin formulation everywhere else. This selective formulation leads to an algebraic system with far less unknowns than the immersed DG method without scarifying the accuracy; hence it is far more efficient than the conventional discontinuous Galerkin formulations.
Ph. D.
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8

Cinkilic, Emre. "Comparison of Interface State Spectroscopy Techniques by Characterizing Dielectric – InGaAs Interfaces." The Ohio State University, 2013. http://rave.ohiolink.edu/etdc/view?acc_num=osu1366329582.

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9

Marshall, L. S. "A formal description method for user interfaces." Thesis, University of Manchester, 1986. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.377673.

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10

Loubenets, Alexei. "A new finite element method for elliptic interface problems." Licentiate thesis, KTH, Numerical Analysis and Computer Science, NADA, 2006. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-3908.

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A finite element based numerical method for the two-dimensional elliptic interface problems is presented. Due to presence of these interfaces the problem will contain discontinuities in the coefficients and singularities in the right hand side that are represented by delta functionals along the interface. As a result, the solution to the interface problem and its derivatives may have jump discontinuities. The introduced method is specifically designed to handle this features of the solution using non-body fitted grids, i.e. the grids are not aligned with the interfaces.

The main idea is to modify the standard basis function in the vicinity of the interface such that the jump conditions are well approximated. The resulting finite element space is, in general, non-conforming. The interface itself is represented by a set of Lagrangian markers together with a parametric description connecting them. To illustrate the abilities of the method, numerical tests are presented. For all the considered test problems, the introduced method has been shown to have super-linear or second order of convergence. Our approach is also compared with the standard finite element method.

Finally, the method is applied to the interface Stokes problem, where the interface represents an elastic stretched band immersed in fluid. Since we assume the fluid to be homogeneous, the Stokes equations are reduced to a sequence of three Poisson problems that are solved with our method. The numerical results agree well with those found in the literature.

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11

Rabadi, Kairas. "PERFORMANCE OF INTERFACE ELEMENTS IN THE FINITE ELEMENT METHOD." Master's thesis, University of Central Florida, 2004. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/2188.

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The objective of this research is to assess the performance of interface elements in the finite element method. Interface elements are implemented in the finite element codes such as MSC.NASTRAN, which is used in this study. Interface elements in MSC.NASTRAN provide a tool to transition between a shell-meshed region to another shell-meshed region as well as from a shell-meshed region to a solid-meshed region. Often, in practice shell elements are layered on shell elements or on solid elements without the use of interface elements. This is potentially inaccurate arising in mismatched degrees of freedom. In the case of a shell-to-shell interface, we consider the case in which the two regions have mismatched nodes along the boundary. Interface elements are used to connect these mismatched nodes. The interface elements are especially useful in global/local analysis, where a region with a dense mesh interfaces to a region with a less dense mesh. Interface elements are used to help avoid using special transition elements between two meshed regions. This is desirable since the transition elements can be severely distorted and cause poor results. Accurate results are obtained in shell-shell and shell-solid combinations. The most interesting result is that not using interface elements can lead to severe inaccuracies. This difficulty is illustrated by computing the stress concentration of a sharp elliptical hole.
M.S.M.E.
Department of Mechanical, Materials and Aerospace Engineering;
Engineering and Computer Science
Mechanical Engineering
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12

Geng, Weihua. "Interface method and Green's function based Poisson Boltzmann equation solver and interface technique based molecular dynamics." Diss., Connect to online resource - MSU authorized users, 2008.

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13

Sarles, Stephen Andrew. "Physical Encapsulation of Interface Bilayers." Diss., Virginia Tech, 2010. http://hdl.handle.net/10919/26950.

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This dissertation presents the development of a new form of biomolecular material system which features interface lipid bilayers capable of hosting a wide variety of natural and engineered proteins. This research builds on the droplet interface bilayer (DIB) platform which first demonstrated that, through self-assembly, lipid-encased water droplets submersed in oil can be physically connected to form a liquid-supported lipid bilayer at the droplet interface. Key advantages of the DIB method over previous bilayer formation techniques include the lack of a supporting substrate which simplifies bilayer formation and the ability to connect many droplets to form `cell-inspired' networks which can provide a collective utility based on the compositions and arrangement of the droplets. The research present herein specifically seeks to overcome three limitations of the original droplet interface bilayer: limited portability due to lack of droplet support, the use of externally supported electrodes to electrically probe the network, and the requirement that in order to form DIB networks, aqueous volumes must be individually dispensed and arranged. The approach presented in this document is to provide increased interactions between the contained liquid phases and a supporting substrate in order to achieve both increased usability through refined methods of packaging and in situ interface formation which eliminates the need to create individual droplets. Physical encapsulation is defined as the the use of a solid substrate to contain both liquid phases such that the aqueous volumes are physically supported on one length scale (10-1000µm) while not inhibiting the self-assembly of phospholipids at the oil/water interface occurring on a much smaller length scale (1-10nm). Physically-encapsulated droplet interface bilayers are achieved by connecting lipid-encased droplets within a substrate that tightly confines the positions of neighboring droplets. A term called the packing factor is introduced to quantify the ratio of the aqueous volumes per the total compartment volume. Physically-encapsulated droplet interface bilayers formed in high packing factor substrate (30%) that also features integrated electrodes demonstrate all of the properties that unencapsulated DIBs exhibit (electrical resistances greater than 1GΩ, failure potentials between |200-300|mV, and the ability to host transmembrane proteins) but these confined assemblies can be moved, shaken, and even completely inverted. Additionally, a structured experiment to quantify the durability of interface bilayers shows that encapsulated and unencapsulated droplet interface bilayers can both survive 3-7g of lateral acceleration prior to bilayer failure, but have different modes of failure. Encapsulated DIBs tend to rupture, while unencapsulated DIBs completely separate. Physical encapsulation is also shown to permit the in situ formation of durable interface bilayers when the substrate is made from a flexible material. The importance of this approach stems from the fact that, by using the substrate to locally partition a single aqueous volume into multiple volumes, there is no need to arrange individual droplets. This method of bilayer formation is termed the regulated attachment method (RAM), since the separation and subsequent reattachment of the aqueous volumes is regulated by the opening and closing of an aperture within the flexible substrate. In this dissertation, a mechanical force is used to directly modulate the aperture dimension for controlling both the initial formation and final size of the interface. With the demonstrated advantages of portability and controlled attachment offered by physical encapsulation, encapsulated lipid bilayers are formed within a completely sealed flexible substrate. A key aspect of this final work is to demonstrate that both the organic and aqueous phases can be stabilized internally, creating a complete material system that features tailorable interface bilayers.
Ph. D.
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14

Gozluklu, Burak. "Delamination Analysis By Using Cohesive Interface Elements In Laminated Composites." Master's thesis, METU, 2009. http://etd.lib.metu.edu.tr/upload/12611005/index.pdf.

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Finite element analysis using Cohesive Zone Method (CZM) is a commonly used method to investigate delamination in laminated composites. In this study, two plane strain, zero-thickness six-node quadratic (6-NQ) and four-node linear (4-NL) interface elements are developed to implement CZM. Two main approaches for CZM formulation are categorized as Unified Mode Approach (UMA) and Separated Mode Approach (SMA), and implemented into 6-NQ interface elements to model a double cantilever beam (DCB) test of a unidirectional laminated composite. The results of the approaches are nearly identical. However, it is theoretically shown that SMA spawns non-symmetric tangent stiffness matrices, which may lower convergence and/or overall performance, for mixed-mode loading cases. Next, a UMA constitutive relationship is rederived. The artificial modifications for improving convergence rates such as lowering penalty stiffness, weakening interfacial strength and using 6-NQ instead of 4-NL interface elements are investigated by using the derived UMA and the DCB test model. The modifications in interfacial strength and penalty stiffness indicate that the convergence may be improved by lowering either parameter. However, over-softening is found to occur if lowering is performed excessively. The morphological differences between the meshes of the models using 6-NQ and 4-NL interface elements are shown. As a consequence, it is highlighted that the impact to convergence performance and overall performance might be in opposite. Additionally, benefits of selecting CZM over other methods are discussed, in particular by theoretical comparisons with the popular Virtual Crack Closure Technique. Finally, the numerical solution scheme and the Arc-Length Method are discussed.
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15

Blades, Eric Lindsay. "A sliding interface method for unsteady unstructured parallel flow simulations." Diss., Mississippi State : Mississippi State University, 2004. http://library.msstate.edu/etd/show.asp?etd=etd-10142004-165050.

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16

Khuu, Vinh P. "Evaluation of thermal interface materials and the laser flash method." College Park, Md. : University of Maryland, 2009. http://hdl.handle.net/1903/9873.

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Thesis (Ph.D.) -- University of Maryland, College Park, 2009.
Thesis research directed by: Dept. of Mechanical Engineering. Title from t.p. of PDF. Includes bibliographical references. Published by UMI Dissertation Services, Ann Arbor, Mich. Also available in paper.
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17

Persson, Markus, and Alexander Semb. "Designing Success : Industrial Process Interface Development." Thesis, Blekinge Tekniska Högskola, Avdelningen för programvarusystem, 2004. http://urn.kb.se/resolve?urn=urn:nbn:se:bth-3115.

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This master thesis describes and treats the conflict between usability and safety in designing industrial interfaces. With literature studies and case studies as a base it analyzes valuable characteristics that are important to include in a design process to increase the possibility to solve this conflict. Further, the thesis investigates several existing design methods and the most valuable parts are extracted and merged into a new method that this thesis argues to have the ability to bridge the gap between safety and usability. The TSAR method, (Task and Safety Analysis Rationale), is based on parts of several existing and established methods proven to work due to extensive usage.
Magisteruppsatsen beskriver och behandlar konflikten mellan användbarhet och användarsäkerhet vid design av industriella gränssnitt. Med litteratur och fallstudier som grund analyseras värdefulla karakteristika som är betydelsefulla i en designprocess för att öka möjligheten att lösa denna konflikt. Vidare undersöker uppsatsen olika typer av etablerade designmetoder varav de mest värdefulla delarna är extraherade och sammanfogade till en ny metod. Denna metod argumenteras i uppsatsen för att besitta förmågan att överbrygga klyftan mellan användbarhet och användarsäkerhet. Metoden TSAR, (Task and Safety Analysis Rationale), baseras på delar av existerande och etablerade metoder som har bevisats applicerbara genom utbredd användning.
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18

Ben, Romdhane Mohamed. "Higher-Degree Immersed Finite Elements for Second-Order Elliptic Interface Problems." Diss., Virginia Tech, 2011. http://hdl.handle.net/10919/39258.

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A wide range of applications involve interface problems. In most of the cases, mathematical modeling of these interface problems leads to partial differential equations with non-smooth or discontinuous inputs and solutions, especially across material interfaces. Different numerical methods have been developed to solve these kinds of problems and handle the non-smooth behavior of the input data and/or the solution across the interface. The main focus of our work is the immersed finite element method to obtain optimal numerical solutions for interface problems. In this thesis, we present piecewise quadratic immersed finite element (IFE) spaces that are used with an immersed finite element (IFE) method with interior penalty (IP) for solving two-dimensional second-order elliptic interface problems without requiring the mesh to be aligned with the material interfaces. An analysis of the constructed IFE spaces and their dimensions is presented. Shape functions of Lagrange and hierarchical types are constructed for these spaces, and a proof for the existence is established. The interpolation errors in the proposed piecewise quadratic spaces yield optimal O(h³) and O(h²) convergence rates, respectively, in the L² and broken H¹ norms under mesh refinement. Furthermore, numerical results are presented to validate our theory and show the optimality of our quadratic IFE method. Our approach in this thesis is, first, to establish a theory for the simplified case of a linear interface. After that, we extend the framework to quadratic interfaces. We, then, describe a general procedure for handling arbitrary interfaces occurring in real physical practical applications and present computational examples showing the optimality of the proposed method. Furthermore, we investigate a general procedure for extending our quadratic IFE spaces to p-th degree and construct hierarchical shape functions for p=3.
Ph. D.
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Ronkainen, S. (Sami). "Designing for ultra-mobile interaction:experiences and a method." Doctoral thesis, University of Oulu, 2010. http://urn.fi/urn:isbn:9789514261794.

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Abstract Usability methodology has matured into a well-defined, industrially relevant field with its own findings, theories, and tools, with roots in applying information technology to user interfaces ranging from control rooms to computers, and more recently to mobile communications devices. The purpose is regularly to find out the users’ goals and to test whether a design fulfils the usability criteria. Properly applied, usability methods provide reliable and repeatable results, and are excellent tools in fine-tuning existing solutions The challenges of usability methodologies are in finding new concepts and predicting their characteristics before testing, especially when it comes to the relatively young field of mobile user interfaces. Current usability methods concentrate on utilising available user-interface technologies. They do not provide means to clearly identify, e.g., the potential of auditory or haptic output, or gestural input. Consequently, these new interaction techniques are rarely used, and the long-envisioned useful multimodal user interfaces are yet to appear, despite their assumed and existing potential in mobile devices. Even the most advocated and well-known multimodal interaction concepts, such as combined manual pointing and natural language processing, have not materialised in applications. An apparent problem is the lack of a way to utilise a usage environment analysis in finding out user requirements that could be met with multimodal user interfaces. To harness the full potential of multimodality, tools to identify both little or unused and overloaded modalities in current usage contexts are needed. Such tools would also help in putting possibly existing novel interaction paradigms in context and pointing out possible deficiencies in them. In this thesis, a novel framework for analysing the usage environment from a user-centric perspective is presented. Based on the findings, a designer can decide between offering a set of multiple devices utilising various user-interface modalities, or a single device that offers relevant modalities, perhaps by adapting to the usage environment. Furthermore, new techniques for creating mobile user interfaces utilising various modalities are proposed. The framework has evolved from the experiences gathered from the designs of experimental and actual product-level uni- and multimodal user interface solutions for mobile devices. It has generated novel multimodal interaction and interface techniques that can be used as building blocks in system designs.
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Calle, Ochoa Andres Eduardo. "InterSis : uma interface grafica para modelamento sismico." [s.n.], 2003. http://repositorio.unicamp.br/jspui/handle/REPOSIP/287053.

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Orientadores: Martin Tygel, Rodrigo de Souza Portugal
Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Mecanica
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Resumo: o modelamento desempenha importante papel nos estudos de processamento e inversão de dados sísmicos. Muitos problemas complicados podem ser melhor atacados e entendidos quando os fenômenos de propagação de ondas envolvidos podem ser modelados, pelo menos em modelos geológicos mais simples. Tendo em vista ser o modelamento sísmico uma área de vasta aplicação e interesse, um grande número de pacotes computacionais existem capazes de oferecer sofisti-cadas capacitações para propósitos de modelagem. Esses pacotes são sujeitos entretanto, a severas limitações em sua utilização, não só devido aos seus altos custos, quanto também à inacessibi-lidade de seus códigos fonte. Por outro lado, as alternativas que existem, na forma de pacotes de uso livre, não representam substituição satisfatória. Isto porque os pacotes de modelamento disponíveis, geralmente desenvolvidos em ambientes científico-acadêmicos, não são suficiente-mente amigáveis e flexíveis, por exemplo na especificação de parâmetros de entrada, disposição gráfica de resultados, etc. o objetivo desta dissertação é investigar os principais problemas associados à construção de uma interface gráfica capaz de suportar uma variedade de programas de modelamento existentes e disponíveis como programas livres. Como resultado dessas investigações, é apresentada neste tra-balho a interface gráfica chamada InterSis. A interface InterSis foi construída de modo a aceitar, de forma simples e unificada, programas de modelamento destinados à propagação de ondas em meios 2D e 2.5D.InterSis foi desenvolvida utilizando os pacotes de domínio público GTK + (Graphical Tool/dt) e SU (Seismic Una). No seu presente estágio, InterSis é capaz de atuar como efetiva plataforma para os programas: (a) Seis88, um programa bem estabelecido de traçado de raios em mode-los elásticos e isotrópicos, desenvolvido por V. Cerveny e I. Psencík e (b) fd2d um programa de diferenças finitas para a equação de onda acústica, desenvolvido por 1. Costa. Como uma pro-priedade de particular interesse, InterSis utiliza a informação fomecida pelo programa Seis88 para computar os parâmetros do chamado método CRS (do Inglês Common-Reflection-Suiface). Desta forma, a interface proposta pode ser de valia nos estudos de imageamento e inversão que utilizam o método CRS. Vale notar que, devido à sua estrutura de caráter geral, InterSis pode ser bem adaptada a outros programas de modelamento
Abstract: Modelling plays an important role in seismie data processing and inversion. Several compli-cated problems can be better addressed and understood, when the wave propagation involved ean be modelled, at least in simple versions ofthe geological model. As a wide topie of application and interest, a number of commercial softwares exist that offer sophisticated capabilities for modelling purposes. These packages are subjected to a number of limitations on their use, not only of costs, but also because their source codes are not accessible. On the other hand, the few ahematives existo in the form of open packages do not represent an easy replacement. The available modelling codes, mainly developed within academie-scientific environments, are not friendly and flexible enough, e.g., in the specification of input parameters and display of resu1ts. The aim of this work is to investigate the main problems connected with the construction of a graphica1 interface that would be an useful support to a number of modelling programs available as open codes. As a result of the investigations, a graphical interface, ca1led InterSis, has been developed. InterSis ean accept and handle, in a simple and unified way,softwares that involves seismic modelling in 2D and 2.5D media. InterSis was developed using the public-domain softwares GTK + (Graphica/ Too/kit) and SU (Seismic Unix). In its present stage, it is able to be an effective platform for the following programs : (a) Seis88, a well-established ray-tracing program developed by v. Cerveny and I. PsenãK and (b) fd2d a finite-difference program for the acoustie wave equation developed by J. Costa. As a particular feature, InterSis uses the information provided by Seis88 to compute the parameters ofthe COmnJOlI-Rejlectioll-Surface (CRS) method. In this way, the proposed intedàce ean be useful to imaging and inversion studies based on the CRS method. It is to be noted that, due to its general s1ructure, InterSis can be well adapted to other modelling programs
Mestrado
Reservatórios e Gestão
Mestre em Ciências e Engenharia de Petróleo
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21

Samvin, David. "Finite Element Methods for Interface Problems." Licentiate thesis, Jönköping University, JTH, Industriell produktutveckling, produktion och design, 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:hj:diva-54570.

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This thesis focuses on computationally efficient methods for flow in fractured porous media. Two approaches are presented where the interface is embedded on the underlying finite element mesh. The methods allow for representation of the interface geometry from the underlying discretization and with discontinuities across the interface. However, embedding interfaces raises stability concerns in which we alleviate using stabilization terms. The aim of this thesis is to present the basics of the two main approaches and to provide brief details on the mathematics involved.
Denna avhandling fokuserar på effektiva beräkningsmetoder för flöde i porösa media med sprickor. Två tillvägagångssätt presenteras där sprickan tillåts skära det underliggande finita elementnätet. Sprickans inverkan på flödet tas om hand med hjälp av den underliggande diskretiseringen som tillåter diskontinuiteter. Med andra ord kan flöden modelleras med olika egenskaper; på var sida av sprickan, samt längs sprickan. Metoden tar även hand om instabilitet som uppstår dels på grund av godtyckliga skärningar av bakgrundselementen och dels på grund av olika materialegenskaper. Syftet med denna avhandling är att presentera grunderna för dessa metoder och ge grundläggande matematiska förklaringar.
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22

Brewster, Stephen. "Providing a structured method for integrating non-speech audio into human-computer interfaces." Thesis, University of York, 1994. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.241055.

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23

Zaichenkov, Pavel. "A method for consistent non-local configuration of component interfaces." Thesis, University of Hertfordshire, 2017. http://hdl.handle.net/2299/19053.

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Service-oriented computing is a popular technology that facilitates the development of large-scale distributed systems. However, the modular composition and flexible coordination of such applications still remains challenging for the following reasons: 1) the services are provided as loosely coupled black boxes that only expose their interfaces to the environment; 2) interacting services are not usually known in advance: web services are dynamically chosen to fulfil certain roles and are often replaced by services with a similar functionality; 3) the nature of the service-based application is decentralised. Loose coupling of web services is often lost when it comes to the construction of an application from services. The reason is that the object-oriented paradigm, which is widely used in the implementation of web services, does not provide a mechanism for service interface self-tuning. As a result, it negatively impacts upon the interoperability of web services. In this dissertation we present a formal method for automatic service configuration in the presence of subtyping, polymorphism, and flow inheritance. This is a challenging problem. On the one hand, the interface description language must be flexible enough to maintain service compatibility in various contexts without any modification to the service itself. On the other hand, the composition of interfaces in a distributed environment must be provably consistent. Our method is based on constraint satisfaction and Boolean satisfiability. First, we define a language for specifying service interfaces in a generic form, which is compatible with a variety of contexts. The language provides support for parametric polymorphism, Boolean variables, which are used to control dependencies between any elements of interface collections, and flow inheritance using extensible records and variants. We implemented the method as a constraint satisfaction solver. In addition to this, we present a protocol for interface configuration. It specifies a sequence of steps that leads to the generation of context-specific service libraries from generic services. Furthermore, we developed a toolchain that performs a complete interface configuration for services written in C++. We integrated support for flexible interface objects (i.e. objects that can be transferred in the application along with their structural description). Although the protocol relies solely on interfaces and does not take behaviour concerns into account, it is capable of finding discrepancies between input and output interfaces for simple stateful services, which only perform message synchronisation. Two running examples (a three buyers use-case and an image processing application) are used along the way to illustrate our approach. Our results seem to be useful for service providers that run their services in the cloud. The reason is twofold. Firstly, interfaces and the code behind them can be generic as long as they are sufficiently configurable. No communication between service designers is necessary in order to ensure consistency in the design. Instead, the interface correspondence in the application is ensured by the constraint satisfaction algorithm, which we have already designed. Secondly, the configuration and compilation of every service are separated from the rest of the application. This prevents source code leaks in proprietary software which is running in the cloud.
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Marella, Saikrishna V. Udaykumar H. S. "A Parallelized sharp-interface fixed grid method for moving boundary problems." Thesis supplements, 2006. http://ir.uiowa.edu/etd/88.

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Wu, Xuqing. "DSS user interface design method with application to shop floor scheduling." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1999. http://www.collectionscanada.ca/obj/s4/f2/dsk3/ftp04/mq47118.pdf.

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26

Brehm, Christoph. "Novel Immersed Interface Method for Solving the Incompressible Navier-Stokes Equations." Diss., The University of Arizona, 2011. http://hdl.handle.net/10150/202770.

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For simulations of highly complex geometries, frequently encountered in many fields of science and engineering, the process of generating a high-quality, body-fitted grid is very complicated and time-intensive. Thus, one of the principal goals of contemporary CFD is the development of numerical algorithms, which are able to deliver computationally efficient, and highly accurate solutions for a wide range of applications involving multi-physics problems, e.g. Fluid Structure Interaction (FSI). Immersed interface/boundary methods provide considerable advantages over conventional approaches, especially for flow problems containing moving boundaries.In the present work, a novel, robust, highly-accurate, Immersed Interface Method (IIM) is developed, which is based on a local Taylor-series expansion at irregular grid points enforcing numerical stability through a local stability condition. Various immersed methods have been developed in the past; however, these methods only considered the order of the local truncation error. The numerical stability of these schemes was demonstrated (in a global sense) by considering a number of different test-problems. None of these schemes used a concrete local stability condition to derive the irregular stencil coefficients. This work will demonstrate that the local stability constraint is valid as long as the DFL-number does not reach a limiting value. The IIM integrated into a newly developed Incompressible Navier-Stokes (INS) solver is used herein to simulate fully coupled FSI problems. The extension of the novel IIM to a higher-order method, the compressible Navier-Stokes equations and the Maxwell's equations demonstrate the great potential of the novel IIM.In the second part of this dissertation, the newly developed INS solver is employed to study the flow of a stalled airfoil and steady/unsteady stenotic flows. In this context, a new biglobal stability analysis approach based on solving an Initial Value Problem (IVP), instead of the traditionally used EigenValue Problem (EVP), is presented. It is demonstrated that this approach based on an IVP is computationally less expensive compared to EVP approaches while still capturing the relevant physics.
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Marella, Saikrishna V. "A Parallelized sharp-interface fixed grid method for moving boundary problems." Diss., University of Iowa, 2006. https://ir.uiowa.edu/etd/88.

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The primary objective of this thesis is to develop a general computational framework to perform large scale moving boundary problems in fluid mechanics. The interactions of moving entities with fluid flow are common to numerous engineering and biomedical applications. The novel computational platform developed comprises of a) an efficient fluid flow solver b) an accurate and easily implemented unified formulation to capture the interactions of the moving bodies with the flow and c) parallel execution capability to enable large scale computations. The above features are formulated and implemented in a computer code, ELAFINT3D. The current thesis demonstrates the accuracy, efficiency and robustness of this framework. The performance of ELAFINT3D on distributed memory systems is also presented. Finally, this framework is employed to simulate a series of large scale, three-dimensional moving boundary problems involving complex interfacial motions and flow phenomena. These numerical experiments establish the strengths of the current tool.
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Eriksson, Isak, and Andreas Johansson. "Developing a method for an ERP system user interface beta test program." Thesis, Linköping University, Department of Computer and Information Science, 2008. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-15760.

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With  this  thesis  we  have  been  interested  in  how  to  utilise  an  user  interface beta  test  period.  Which  activities  are  appropriate  to  be  performed,  with  focus  on  how  activities  contribute  to  user  interface  validation,  further  user  interface  improvements,  and  improvements  of  the  user  interface  roll‐out.  Additionally  we  have  tried  to  couple  this  to  end‐user  satisfaction  and  acceptance  of  this new user interface, since the usage of the system is mandatory for the end users.    

 

We  have  approached  this  by  developing  a  method  that  is  based  on  four  different  perspectives.  Three  perspectives  are  studied theoretically,  and  one  perspective  is  based  on  empiric  research.  These  perspectives  are  separate  from  each  other;  to  combine  them  we  have  used  a  common  denominator  of  increased  system  usage.  This  denominator  is  derived  from  a  viewpoint upon  end‐users  and  how  user  satisfaction,  user  acceptance,  and  behaviour  incentives  for  usage  affect  the  perspectives and consequently our result.  

 

This  broad  research  has  resulted  in  a  self‐sustaining  method  that  we  describe  both  in  an  overview  and  in  greater  detail  explain  the  beta  period  and  the  associated  roles,  the  different  activities  and  how  they  should  be  executed  in  relevance  to  time.  For  every  activity  a  table  of  considerations,  i.e.  when,  who,  how,  and  why  are  presented  together  with  an  explanation  how  the  activity  can  influence end‐users to use the system.   

 

We  conclude  that  the  result  of  this  thesis  will  aid  and  guide  vendor  companies  through  the  beta  testing  program  of  a  new  user  interface.  The  resulting  method  determines  which  activities  that  can  be  of  interest to carry out and how these will  contribute  to  future  development  and/or  improve  roll‐out.  By  utilising this  method as a framework we see the possibility to incorporate it in an existing user-centre development process, but it can also be used as a simple, straightforward,  and self‐sustaining method. 

 

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MacFadden, James. "Computational methods for incompressible fluid flows, with reference to interface modelling by an extended finite element method." Thesis, Swansea University, 2006. https://cronfa.swan.ac.uk/Record/cronfa42810.

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In this thesis an implicit Semi-Discrete Stabilized eXtended Finite Element formulation has been successfully developed and implemented for laminar Newtonian incompressible fluid flows. In doing so we have contributed to the research into the field of incompressible fluid flows, multiphase flow and fluid-rigid body interaction. The fluid flows are governed by the incompressible viscous Navier-Stokes equations, using a Finite Element formulation to model the fluid behaviour numerically. A Semi-Discrete time integration scheme was implemented, discretizing in space, leaving the system of ordinary differential equations to be integrated in time. Initially the classical Galerkin method is used to formulate the boundary value problem from the governing equations, however stability issues due to incompressibility and dominant advection terms force the implementation of the stabilized formulation, i.e. SUPG/PSPG. This approach gives greater flexibility in choice of velocity/pressure interpolations, such as equal order functions. The time integration schemes (Generalized alpha method and Generalized Midpoint rule) were compared and contrasted, with the Generalized alpha method demonstrating improved convergence. The highly nonlinear form of the governing equations required an implicit iterative solver and the Newton-Raphson procedure was chosen. Several tests were performed throughout the formulation of the boundary value problem to validate the implementation. The result, a robust, efficient and accurate unsteady incompressible Newtonian fluid formulation. extended FEM was introduced by adding terms to the FEM formulation in a Partition of Unity framework. With the addition of complex solution procedures X-FEM was implemented and tested for multiphase and fluid-rigid body interaction, demonstrating the attractive qualities of this method.
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Angelides, Michael. "Stress compatible finite elements for bimaterial interface problems." Thesis, McGill University, 1987. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=63808.

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31

Zhu, Hong Fang. "An immersed interface method algorithm with discontinuous coefficients for the energy equation." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1998. http://www.collectionscanada.ca/obj/s4/f2/dsk2/tape17/PQDD_0027/MQ27028.pdf.

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32

Suada, Muhamad Giri. "A finite element method for delamination initiation and growth using interface elements." Thesis, Imperial College London, 1997. http://hdl.handle.net/10044/1/11923.

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33

Mehrabian, Hadi. "Simulation of selected interfacial dynamic problems using Cahn-Hilliard diffuse-interface method." Thesis, University of British Columbia, 2014. http://hdl.handle.net/2429/46267.

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Using the Cahn-Hilliard diffuse-interface model, I have studied three interfacial dynamic problems for incompressible immiscible two-phase flows. As the first problem, capillary instability of a liquid torus is computed. The main differences between the torus and a straight thread are the presence of an axial curvature and an external flow field caused by the retraction of the torus. We show that the capillary wave initially grows linearly as on a straight thread. The axial curvature decreases the growth rate of the capillary waves while the external flow enhances it. Breakup depends on the competition of two time scales: one for torus retraction and the other for neck pinch-off. The outcome is determined by the initial amplitude of the disturbance, the thickness of the torus relative to its circumference, and the viscosity ratio. The second problem concerns interfacial dynamics and three-phase contact line motion of wicking through micropores of two types of geometries: axisymmetric tubes with contractions and expansions of the cross section, and two-dimensional planar channels with a Y-shaped bifurcation. Results show that the liquid meniscus undergoes complex deformation during its passage through contraction and expansion. Pinning of the interface at protruding corners limits the angle of expansion into which wicking is allowed. Capillary competition between branches downstream of a Y-shaped bifurcation may result in arrest of wicking in the wider branch. As the third problem, auto-ejection of drops from capillary tubes is studied. This study focuses on two related issues: the critical condition for autoejection, and the role of geometric parameters in the hydrodynamics. From analyzing the dynamics of the meniscus in the straight tube and the nozzle, we develop a criterion for the onset of auto-ejection based on a Weber number defined at the exit of the nozzle and an effective length that encompasses the geometric features of the tube-nozzle combination. In particular, this criterion shows that ejection is not possible in straight tubes. With steeper contraction in the nozzle, we predict two additional regimes of interfacial rupture: rapid ejection of multiple droplets and air bubble entrapment.
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Zhu, Hong Fang Carleton University Dissertation Engineering Mechanical and Aerospace. "An Immersed interface method algorithm with discontinuous coeffcients for the energy equation." Ottawa, 1997.

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Ağıroğlu, İzzet Onur Tanoğlu Gamze. "An application of the finite differences method to a dynamical interface problem/." [s.l.]: [s.n.], 2004. http://library.iyte.edu.tr/tezler/master/matematik/T000445.pdf.

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36

Sellers, Eric William. "A P300-based brain-computer interface testing an alternative method of communication /." [Tampa, Fla.] : University of South Florida, 2004. http://purl.fcla.edu/fcla/etd/SFE0000536.

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Sellers, Eric W. "A P300-Based Brain-Computer Interface: Testing an Alternative Method of Communication." Scholar Commons, 2004. https://scholarcommons.usf.edu/etd/1242.

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The current study evaluates the effectiveness of a Brain-Computer Interface (BCI) system that operates by detecting a P300 elicited by one of four randomly presented stimuli (i.e., YES, NO, PASS, END). Two groups of participants were tested. The first group included three ALS patients that varied in degree of disability, but all retained the ability to communicate; the second group included three Non-ALS controls. Each participant participated in ten experimental sessions during a period of approximately 6 weeks. Sessions were conducted either at the participant's home or in the lab. During each run the participant's task was to attend to one stimulus and disregard the other three. Stimuli were presented auditorily, visually, or in both modes. Additionally, on each run, the experimenter would either tell the participant which stimulus to focus on, or ask the participant a question and the participant would focus on the correct "YES/NO" answer to the question. Overall, for each participant, the ERPs elicited by the target stimuli could be discriminated from the non-target stimuli; however, less variability was observed in the Non-ALS group. Comparing across sessions, the within session variability was lower than across session variability. In addition, waveform morphology varied as a function of the presentation mode, but not in a similar pattern for each participant. Offline and simulated online classification algorithms conducted using step-wise discriminant analysis produced results suggesting the potential for online classification performance at levels acceptable for communication. Future investigations will begin to focus on testing online classification performance with real-time feedback, and continuing to examine stimulus properties to determine how to maximize P300 amplitude for individual users.
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Klicker, Laura. "A Method for Standardization within the Payload Interface Definition of a Service-Oriented Spacecraft using a Modified Interface Control Document​." Thesis, KTH, Rymdteknik, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-217971.

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With a big picture view of increasing the accessibility of space, standardization is applied within a service-oriented space program. The development of standardized spacecraft interfaces for numerous and varied payloads is examined through the lens of the creation of an Interface Control Document (ICD) within the Peregrine Lunar Lander project of Astrobotic Technologies, Inc. The procedure is simple, transparent, and adaptable; its applicability to other similar projects is assessed.
För en ökad tillgång till rymden finns det behov av standardisering för en förbättrad service. Utvecklingen av standardiserade rymdfarkostgränsytor för flera och olika nyttolaster har undersökts via ett dokumentet för gränssnittskontroll (ICD) inom projektet Peregrine Lunar Lander för Astrobotic Technologies, Inc. Proceduren är enkel, transparent och anpassningbar; dess användning för andra liknande projekt har värderats.
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Sambasivan, Shiv Kumar. "A sharp interface Cartesian grid hydrocode." Diss., University of Iowa, 2010. https://ir.uiowa.edu/etd/593.

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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.
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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.

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41

Morrison, Heather. "Online catalogue research and the verbal protocol method." MCB University Press, 1999. http://hdl.handle.net/2429/957.

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The verbal protocol method is used extensively in computer usability studies. This study was designed to test the feasibility of using the verbal protocol method as a means of conducting field research on the online catalogue. Ten undergraduate students conducted their own research on DRA’s Infogate. As they searched, they talked aloud about what keys they were pressing, what was happening on the screen, and their reactions. Transcripts of sessions were analyzed. A total of 65 different problems or comments were noted during search sessions, with 11 problems or comments noted in three or more sessions. This supports the hypothesis that the verbal protocol method is a valuable means of identifying common problems for users. It is suggested that the verbal protocol method offers great potential as a research tool in librarianship, for example in the area of interface design.
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Figiel, Lukasz. "Sensitivity Analysis of Interface Fatigue Crack Propagation in Elastic Composite Laminates." Doctoral thesis, Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2004. http://nbn-resolving.de/urn:nbn:de:swb:14-1102358246078-89903.

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Composite laminates are an important subject of modern technology and engineering. The most common mode of failure in these materials is probably interlaminar fracture (delamination). Delamination growth under applied fatigue loads usually leads to structural integrity loss of the composite laminate, and hence its catastrophic failure. It is known that several parameters can affect the fatigue fracture performance of laminates. These include the constituent material properties, composite geometry, fatigue load variables or environmental factors. The knowledge about effects of these parameters on fatigue delamination growth can lead to a better understanding of composite fatigue fracture behaviour. Effects of some of these parameters can be elucidated by undertaking appropriate sensitivity analysis combined with the finite element method (FEM) and related software. The purpose of this work was three-fold. The first goal was the elaboration and computational implementation of FEM-based numerical strategies for the sensitivity analysis of interface fatigue crack propagation in elastic composite laminates. The second goal of this work was the numerical determination and investigation of displacement and stress fields near the crack tip, contact pressures along crack surfaces, mixed mode angle, energy release rate and the number of cumulative fatigue cycles. The third aim of the present study was to use the developed strategies to evaluate numerically the sensitivity gradients of the total energy release rate and fatigue life with respect to design variables of the curved boron/epoxy-aluminium (B/Ep-Al) composite laminate in two different material configurations under cyclic shear of constant amplitude. This study provided novel strategies for undertaking sensitivity analysis of the delamination growth under fatigue loads for elastic composite laminates using the package ANSYS. The numerical results of the work shed more light on mechanisms of interfacial crack propagation under cyclic shear in the case of a curved B/Ep-Al composite laminate. Moreover, the outcome of the sensitivity gradients demonstrated some advantages for using the sensitivity analysis to pinpoint directions for the optimisation of fatigue fracture performance of elastic laminates. The strategies proposed in this work can be used to study the sensitivity of the interface fatigue crack propagation in other elastic laminates, if the crack propagates at the interface between the elastic and isotropic components. However, the strategies can be potentially extended to composites with interfacial cracks propagating between two non-isotropic constituents under a constant amplitude fatigue load. Finally, the strategies can also be used to undertake the sensitivity analysis of composite fatigue life with respect to variables of fatigue load.
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Marth, Wieland. "Hydrodynamic Diffuse Interface Models for Cell Morphology and Motility." Doctoral thesis, Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2016. http://nbn-resolving.de/urn:nbn:de:bsz:14-qucosa-204651.

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In this thesis, we study mathematical models that describe the morphology of a generalized biological cell in equilibrium or under the influence of external forces. Within these models, the cell is considered as a thermodynamic system, where streaming effects in the cell bulk and the surrounding are coupled with a Helfrich-type model for the cell membrane. The governing evolution equations for the cell given in a continuum formulation are derived using an energy variation approach. Such two-phase flow problems that combine streaming effects with a free boundary problem that accounts for bending and surface tension can be described effectively by a diffuse interface approach. An advantage of the diffuse interface approach is that models for e.g. different biophysical processes can easily be combined. That makes this method suitable to describe complex phenomena such as cell motility and multi-cell dynamics. Within the first model for cell motility, we combine a biological network for GTPases with the hydrodynamic Helfrich-type model. This model allows to account for cell motility driven by membrane protrusion as a result of actin polymerization. Within the second model, we moreover extend the Helfrich-type model by an active gel theory to account for the actin filaments in the cell bulk. Caused by contractile stress within the actin-myosin solution, a spontaneous symmetry breaking event occurs that lead to cell motility. In this thesis, we further study the dynamics of multiple cells which is of wide interest since it reveals rich non-linear behavior. To apply the diffuse interface framework, we introduce several phase field variables to account for several cells that are coupled by a local interaction potential. In a first application, we study white blood cell margination, a biological phenomenon that results from the complex relation between collisions, different mechanical properties and lift forces of red blood cells and white blood cells within the vascular system. Here, it is shown that inertial effects, which can become of relevance in various parts of the cardiovascular system, lead to a decreasing tendency for margination with increasing Reynolds number. Finally, we combine the active polar gel theory and the multi-cell approach that is capable of studying collective migration of cells. This hydrodynamic approach predicts that collective migration emerges spontaneously forming coherently-moving clusters as a result of the mutual alignment of the velocity vectors during inelastic collisions. We further observe that hydrodynamics heavily influence those systems. However, a complete suppression of the onset of collective migration cannot be confirmed. Moreover, we give a brief insight how such highly coupled systems can be treated numerically using finite elements and how the numerical costs can be limited using operator splitting approaches and problem parallelization with OPENMP
Diese Dissertation beschäftigt sich mit mathematischen Modellen zur Beschreibung von Gleichgewichts- und dynamischen Zuständen von verallgemeinerten biologischen Zellen. Die Zellen werden dabei als thermodynamisches System aufgefasst, bei dem Strömungseffekte innerhalb und außerhalb der Zelle zusammen mit einem Helfrich-Modell für Zellmembranen kombiniert werden. Schließlich werden durch einen Energie-Variations-Ansatz die Evolutionsgleichungen für die Zelle hergeleitet. Es ergeben sie dabei Mehrphasen-Systeme, die Strömungseffekte mit einem freien Randwertproblem, das zusätzlich physikalischen Einflüssen wie Biegung und Oberflächenspannung unterliegt, vereinen. Um solche Probleme effizient zu lösen, wird in dieser Arbeit die Diffuse-Interface-Methode verwendet. Ein Vorteil dieser Methode ist, dass es sehr einfach möglich ist, Modelle, die verschiedenste Prozesse beschreiben, miteinander zu vereinen. Dies erlaubt es, komplexe biologische Phänomene, wie zum Beispiel Zellmotilität oder auch die kollektive Bewegung von Zellen, zu beschreiben. In den Modellen für Zellmotilität wird ein biologisches Netzwerk-Modell für GTPasen oder auch ein Active-Polar-Gel-Modell, das die Aktinfilamente im Inneren der Zellen als Flüssigkristall auffasst, mit dem Multi-Phasen-Modell kombiniert. Beide Modelle erlauben es, komplexe Vorgänge bei der selbst hervorgerufenen Bewegung von Zellen, wie das Vorantreiben der Zellmembran durch Aktinpolymerisierung oder auch die Kontraktionsbewegung des Zellkörpers durch kontraktile Spannungen innerhalb des Zytoskelets der Zelle, zu verstehen. Weiterhin ist die kollektive Bewegung von vielen Zellen von großem Interesse, da sich hier viele nichtlineare Phänomene zeigen. Um das Diffuse-Interface-Modell für eine Zelle auf die Beschreibung mehrerer Zellen zu übertragen, werden mehrere Phasenfelder eingeführt, die die Zellen jeweils kennzeichnen. Schließlich werden die Zellen durch ein lokales Abstoßungspotential gekoppelt. Das Modell wird angewendet, um White blood cell margination, das die Annäherung von Leukozyten an die Blutgefäßwand bezeichnet, zu verstehen. Dieser Prozess wird dabei bestimmt durch den komplexen Zusammenhang zwischen Kollisionen, den jeweiligen mechanischen Eigenschaften der Zellen, sowie deren Auftriebskraft innerhalb der Adern. Die Simulationen zeigen, dass diese Annäherung sich in bestimmten Gebieten des kardiovaskulären Systems stark vermindert, in denen die Blutströmung das Stokes-Regime verlässt. Schließlich wird das Active-Polar-Gel-Modell mit dem Modell für die kollektive Bewegung vom Zellen kombiniert. Dies macht es möglich, die kollektive Bewegung der Zellen und den Einfluss von Hydrodynamik auf diese Bewegung zu untersuchen. Es zeigt sich dabei, dass der Zustand der kollektiven gerichteten Bewegung sich spontan aus der Neuausrichtung der jeweiligen Zellen durch inelastische Kollisionen ergibt. Obwohl die Hydrodynamik einen großen Einfluss auf solche Systeme hat, deuten die Simulationen nicht daraufhin, dass Hydrodynamik die kollektive Bewegung vollständig unterdrückt. Weiterhin wird in dieser Arbeit gezeigt, wie die stark gekoppelten Systeme numerisch gelöst werden können mit Hilfe der Finiten-Elemente-Methode und wie die Effizienz der Methode gesteigert werden kann durch die Anwendung von Operator-Splitting-Techniken und Problemparallelisierung mittels OPENMP
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44

Berthelsen, Petter Andreas. "An immersed interface method for two-dimensional modelling of stratified flow in pipes." Doctoral thesis, Norwegian University of Science and Technology, Department of Energy and Process Engineering, 2004. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-306.

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This thesis deals with the construction of a numerical method for solving two-dimensional elliptic interface problems, such as fully developed stratified flow in pipes. Interface problems are characterized by its non-smooth and often discontinuous behaviour along a sharp boundary separating the fluids or other materials. Classical numerical schemes are not suitable for these problems due to the irregular geometry of the interface. Standard finite difference discretization across the interface violates the interfacial boundary conditions; therefore special care must be taken at irregular grid nodes.

In this thesis a decomposed immersed interface method is presented. The immersed interface method is a numerical technique formulated to solve partial differential equations in the presence of an interface where the solution and its derivatives may be discontinuous and non-smooth. Componentwise corrections terms are added to the finite difference stencil in order to make the discretization well-defined across the interface. A method that approximates the correction terms is also proposed. Results from numerical experiments show that the rate of convergence is approximately of second order.

Moreover, the immersed interface method is applied to stratified multiphase flow in pipes. The flow is assumed to be fully developed and in steady-state. For turbulent flow, both a low Reynolds number turbulence model and a two-layer turbulence model are adopted in order to imitate turbulence in the flow field and in the vicinity of the boundaries. The latter turbulence model is modified accordingly to account for the effects of a wavy interface. In this case, the concept of interfacial roughness is used to model the wavy nature of the interface.

Numerical results are compared with analytical solutions for laminar flow and experimental data for turbulent flow. It is also demonstrated that the current numerical method offers more flexibility in simulating stratified pipe flow problems with complex shaped interfaces, including three-phase flow, than seen in any previous approach.


Paper I reprinted with kind permission of Elsevier, Sciencedirect
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Kulkarni, Vikram Digambar. "A piecewise linear interface tracking method for 3-D Eulerian incompressible fluid flows." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1999. http://www.collectionscanada.ca/obj/s4/f2/dsk2/ftp01/MQ36910.pdf.

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46

Gustafson-Pearce, Olinkha. "The application of the information architecture method to design an intuitive haptic interface." Thesis, Brunel University, 2005. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.429234.

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47

Hinneh, Perry. "The Finite Block Method : a meshless study of interface cracks in bi-materials." Thesis, Queen Mary, University of London, 2018. http://qmro.qmul.ac.uk/xmlui/handle/123456789/39754.

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The ability to extract accurately the stress intensity factor and the T-Stress for fractured engineering materials is very significant in the decision-making process for in-service engineering components, mainly for their functionality and operating limit. The subject of computational fracture mechanics in engineering make this possible without resulting to expensive experimental processes. In this thesis, the Finite Block Method (FBM) has been developed for the meshless study of interface stationary crack under both static and dynamic loading in bi-materials. The finite block method based on the Lagrangian interpolation is introduced and the various mathematical constructs are examined. This includes the use of the mapping technique. In a one-dimensional and a two-dimensional case, numerical studies were performed in order to determine the interpolation error. The finite block method in both the Cartesian coordinate and the polar coordinate systems is developed to evaluate the stress intensity factors and the T-stress for interface cracks between bi-materials. Using the William's series for bi-material, an expression for approximating the stress and displacement at the interface crack tip is established. In order to capture accurately the stress intensity factors and the T-stress at the crack tip, the asymptotic expansions of the stress and displacement around the crack tip are introduced with a singular core technique. The accuracy and capability of the finite block method in evaluating interface cracks is demonstrated by several numerical assessments. In all cases, comparisons have been made with numerical solutions by using the boundary collocation method, the finite element method and the boundary element method, etc.
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48

Doong, Jia-maw. "A dynamic, time-stepping boundary element method for frictional crack and interface problems /." The Ohio State University, 1988. http://rave.ohiolink.edu/etdc/view?acc_num=osu1487588939087424.

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49

Liu, Yang. "The Immersed Interface Method for Flow Around Non-Smooth Boundaries and Its Parallelization." Thesis, Southern Methodist University, 2017. http://pqdtopen.proquest.com/#viewpdf?dispub=10283304.

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In the immersed interface method (IIM), the boundaries of objects in a fluid are treated as immersed interfaces in the fluid. Singular forces are used to represent the effects of the objects on the fluid, and jump conditions induced by the singular forces are incorporated into numerical schemes to simulate the flow. Previously, the immersed interface method for simulating smooth rigid objects with prescribed motion in 2D & 3D incompressible viscous flows has been developed by Xu. In this thesis, we extend the method for rigid objects with non-smooth boundaries by computing necessary jump conditions using line segment representation of 2D objects. We also present the parallelization strategy for the development of a high-performance program for distributed-memory parallel computing with Message Passing Interface (MPI ). Different tests are performed, and numerical results and comparisons are given to study the accuracy, efficiency, and robustness of our method.

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Mohammed, Imaduddin F. "An interface to grid file method for datacube storage and range sum query /." Available to subscribers only, 2007. http://proquest.umi.com/pqdweb?did=1404354991&sid=9&Fmt=2&clientId=1509&RQT=309&VName=PQD.

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