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Dissertations / Theses on the topic 'Computational modeling and simulation'
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Emerson, Tonya Lynn. "Ductile fracture mechanics : modeling, experiments, and computational simulation /." For electronic version search Digital dissertations database. Restricted to UC campuses. Access is free to UC campus dissertations, 2002. http://uclibs.org/PID/11984.
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Le, Xuan Tuan. "Understanding complex systems through computational modeling and simulation." Thesis, Paris Sciences et Lettres (ComUE), 2017. http://www.theses.fr/2017PSLEP003.
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Les approches de simulation classiques ne sont en général pas adaptées pour traiter les aspects de complexité que présentent les systèmes complexes tels que l'émergence ou l'adaptation. Dans cette thèse, l'auteur s'appuie sur ses travaux menés dans le cadre d'un projet de simulation sur l’épidémie de grippe en France associée à des interventions sur une population en considérant le phénomène étudié comme un processus diffusif sur un réseau complexe d'individus, l'originalité réside dans le fait que la population y est considérée comme un système réactif. La modélisation de tels systèmes nécessite de spécifier explicitement le comportement des individus et les réactions de ceux-cis tout en produisant un modèle informatique qui doit être à la fois flexible et réutilisable. Les diagrammes d'états sont proposés comme une approche de programmation reposant sur une modélisation validée par l'expertise. Ils correspondent également à une spécification du code informatique désormais disponibles dans les outils logiciels de programmation agent. L'approche agent de type bottom-up permet d'obtenir des simulations de scénario "what-if" où le déroulement des actions peut nécessiter que les agents s'adaptent aux changements de contexte. Cette thèse propose également l'apprentissage pour un agent par l'emploi d'arbre de décision afin d'apporter flexibilité et lisibilité pour la définition du modèle de comportement des agents et une prise de décision adaptée au cours de la simulation. Notre approche de modélisation computationnelle est complémentaire aux approches traditionnelles et peut se révéler indispensable pour garantir une approche pluridisciplinaire validable par l'expertiseTraditional approaches are not sufficient, and sometimes impossible in dealing with complexity issues such as emergence, self-organization, evolution and adaptation of complex systems. As illustrated in this thesis by the practical work of the author in a real-life project, the spreading of infectious disease as well as interventions could be considered as difusion processes on complex networks of heterogeneous individuals in a society which is considered as a reactive system. Modeling of this system requires explicitly specifying of each individual’s behaviors and (re)actions, and transforming them into computational model which has to be flexible, reusable, and ease of coding. Statechart, typical for model-based programming, is a good solution that the thesis proposes. Bottom-up agent based simulation finds emergence episodes in what-if scenarios that change rules governing agent’s behaviors that requires agents to learn to adapt with these changes. Decision tree learning is proposed to bring more flexibility and legibility in modeling of agent’s autonomous decision making during simulation runtime. Our proposition for computational models such as agent based models are complementary to traditional ones, and in some case they are unique solutions due to legal, ethical issues
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Lambeth, Melissa Jo. "Computational modeling of skeletal muscle glycogenolysis dynamics /." Thesis, Connect to this title online; UW restricted, 2003. http://hdl.handle.net/1773/8095.
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Barua, Himel Barua. "COMPUTATIONAL MODELING OF CHEMICAL VAPOR DEPOSITION." University of Akron / OhioLINK, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=akron1469721885.
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Simoni, Giulia. "Modeling Startegies for Computational Systems Biology." Doctoral thesis, Università degli studi di Trento, 2020. http://hdl.handle.net/11572/254361.
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Mathematical models and their associated computer simulations are nowadays widely used in several research fields, such as natural sciences, engineering, as well as social sciences. In the context of systems biology, they provide a rigorous way to investigate how complex regulatory pathways are connected and how the disruption of these processes may contribute to the develop- ment of a disease, ultimately investigating the suitability of specific molecules as novel therapeutic targets. In the last decade, the launching of the precision medicine initiative has motivated the necessity to define innovative computational techniques that could be used for customizing therapies. In this context, the combination of mathematical models and computer strategies is an essential tool for biologists, which can analyze complex system pathways, as well as for the pharmaceutical industry, which is involved in promoting programs for drug discovery.
In this dissertation, we explore different modeling techniques that are used for the simulation and the analysis of complex biological systems. We analyze the state of the art for simulation algorithms both in the stochastic and in the deterministic frameworks. The same dichotomy has been studied in the context of sensitivity analysis, identifying the main pros and cons of the two approaches. Moreover, we studied the quantitative system pharmacology (QSP) modeling approach that elucidates the mechanism of action of a drug on the biological processes underlying a disease. Specifically, we present the definition, calibration and validation of a QSP model describing Gaucher disease type 1 (GD1), one of the most common lysosome storage rare disorders. All of these techniques are finally combined to define a novel computational pipeline for patient stratification. Our approach uses modeling techniques, such as model simulations, sensitivity analysis and QSP modeling, in combination with experimental data to identify the key mechanisms responsible for the stratification. The pipeline has been applied to three test cases in different biological contexts: a whole-body model of dyslipidemia, the QSP model of GD1 and a QSP model of cardiac electrophysiology. In these test cases, the pipeline proved to be accurate and robust, allowing the interpretation of the mechanistic differences underlying the phenotype classification.
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Withrow, Travis P. "Computational Modeling of Atom Probe Tomography." The Ohio State University, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=osu1525763934302517.
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Yang, Le. "Computational Modeling and Simulation Study of Dermal Wound Healing Proliferative Phase." VCU Scholars Compass, 2011. http://scholarscompass.vcu.edu/etd/278.
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Dermal wound healing proliferative phase is a complicated physiological process in which many growth factors, cell types and matrix components participate. The process must be well coordinated to restore the structural and functional integrity of tissue injured. Many disorders interrupting healing process result in abnormal healing such as chronic wounds or excessive scarring. Mathematical modeling has been used to investigate many aspects of wound healing. Angiogenesis is pertinent for dermal wound healing since the cellular activities involved in tissue repair requires oxygen and nutrients to be delivered to the wound site. By using a hybrid agent-based model, we investigated the interactive dynamics of vasculature growth and collagen network growth. Our model further examine the effects of tissue oxygen tension (hypoxia, normoxia, hyperoxia) on healing process. Wound contraction is generally beneficial for the overall healing since it reduces the wound size thus reduces the chance to be infected. However, contraction going overboard may result in excessive scarring. Our model seeks to investigate the source of driving force during early and late stage of wound contraction. For the first time, skin is modeled as a fiber-reinforced anisotropic soft tissue. The effects of a dynamically orienting collagen matrix on the contraction process are thus shown. The simulation results of the model agree with the hypothesis that scar formation is the byproduct of collagen fiber synthesis and alignment in the presence of the tensile stress field generated by a wound contraction process. Multi-scale modeling is illuminating because it can help explain the phenomena at tissue level by the subcellular level events. We built a multi-scale model of general wound healing proliferative phase by embedding a TGFbeta pathway to each fibroblasts. The subcellular level model is an ODE system and the cellular level model is a hybrid agent-based model of fibroblast migration, proliferationg and collagen production. Our model clearly shows how varying mechanics of the subcellular level system results in varying tissue level pattern (collagen orientation and cell population distribution). The model can be further extended to incorporate subcellular events relating to angiogenesis and wound contraction.
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Venkatachalam, Sangeeta. "Modeling Infectious Disease Spread Using Global Stochastic Field Simulation." Thesis, University of North Texas, 2006. https://digital.library.unt.edu/ark:/67531/metadc5335/.
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Susceptibles-infectives-removals (SIR) and its derivatives are the classic mathematical models for the study of infectious diseases in epidemiology. In order to model and simulate epidemics of an infectious disease, a global stochastic field simulation paradigm (GSFS) is proposed, which incorporates geographic and demographic based interactions. The interaction measure between regions is a function of population density and geographical distance, and has been extended to include demographic and migratory constraints. The progression of diseases using GSFS is analyzed, and similar behavior to the SIR model is exhibited by GSFS, using the geographic information systems (GIS) gravity model for interactions. The limitations of the SIR and similar models of homogeneous population with uniform mixing are addressed by the GSFS model. The GSFS model is oriented to heterogeneous population, and can incorporate interactions based on geography, demography, environment and migration patterns. The progression of diseases can be modeled at higher levels of fidelity using the GSFS model, and facilitates optimal deployment of public health resources for prevention, control and surveillance of infectious diseases.
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Wang, Kezhou Denney Thomas Stewart. "Numerical modeling of nasal cavities and air flow simulation." Auburn, Ala., 2006. http://repo.lib.auburn.edu/2006%20Spring/doctoral/WANG_KEZHOU_24.pdf.
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Indrakanti, Saratchandra. "A Global Stochastic Modeling Framework to Simulate and Visualize Epidemics." Thesis, University of North Texas, 2012. https://digital.library.unt.edu/ark:/67531/metadc115099/.
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Epidemics have caused major human and monetary losses through the course of human civilization. It is very important that epidemiologists and public health personnel are prepared to handle an impending infectious disease outbreak. the ever-changing demographics, evolving infrastructural resources of geographic regions, emerging and re-emerging diseases, compel the use of simulation to predict disease dynamics. By the means of simulation, public health personnel and epidemiologists can predict the disease dynamics, population groups at risk and their geographic locations beforehand, so that they are prepared to respond in case of an epidemic outbreak. As a consequence of the large numbers of individuals and inter-personal interactions involved in simulating infectious disease spread in a region such as a county, sizeable amounts of data may be produced that have to be analyzed. Methods to visualize this data would be effective in facilitating people from diverse disciplines understand and analyze the simulation. This thesis proposes a framework to simulate and visualize the spread of an infectious disease in a population of a region such as a county. As real-world populations have a non-homogeneous demographic and spatial distribution, this framework models the spread of an infectious disease based on population of and geographic distance between census blocks; social behavioral parameters for demographic groups. the population is stratified into demographic groups in individual census blocks using census data. Infection spread is modeled by means of local and global contacts generated between groups of population in census blocks. the strength and likelihood of the contacts are based on population, geographic distance and social behavioral parameters of the groups involved. the disease dynamics are represented on a geographic map of the region using a heat map representation, where the intensity of infection is mapped to a color scale. This framework provides a tool for public health personnel and epidemiologists to run what-if analyses on disease spread in specific populations and plan for epidemic response. By the means of demographic stratification of population and incorporation of geographic distance and social behavioral parameters into the modeling of the outbreak, this framework takes into account non-homogeneity in demographic mix and spatial distribution of the population. Generation of contacts per population group instead of individuals contributes to lowering computational overhead. Heat map representation of the intensity of infection provides an intuitive way to visualize the disease dynamics.
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Li, Yanjun. "COMPUTATIONAL MODELING OF IN VIVO METABOLIC PROCESSES IN SKELETAL MUSCLE." Case Western Reserve University School of Graduate Studies / OhioLINK, 2011. http://rave.ohiolink.edu/etdc/view?acc_num=case1283473428.
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Hlady, Christopher Scott. "Nosocomial infection modeling and simulation using fine-grained healthcare data." Diss., University of Iowa, 2011. https://ir.uiowa.edu/etd/4856.
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Simulation has long been used in healthcare settings to study a range of problems, such as determining ideal staffing levels, allocating patient beds, and assisting with medical decision making. Some of this work naturally focuses on the spread of infection within hospitals, where the importance of hospitals as loci and amplifiers of infection was demonstrated during the 2002-2003 SARS outbreak. Increasingly, fine-grained healthcare data is being collected (e.g., patient care data stored in electronic medical record systems, and healthcare worker data from sources including nurse locator badges), presenting an opportunity to develop models that can drive more realistic simulations. We seek to build a realistic hospital simulator that can be used to answer a wide variety of questions about infection prevention, the allocation and placement of expensive resources, and issues surrounding patient care.
Our simulation framework requires three primary inputs: architectural, healthcare worker, and patient data. We used data from the University of Iowa Hospitals and Clinics to build our virtual hospital. We manually constructed a weighted, directed, 19,000 node graph-theoretic representation of the facility based on printed architectural drawings. Using timestamped location information from electronic medical record system logins and algorithms inspired by prior work on location-aware search, each healthcare worker is modeled by one or more “centers” of activity. Centers are determined using a maximum likelihood approach to fit a location and appropriate decay parameters that best describe the observed data. Finally, we developed compartmental patient models of varying granularity, with each compartment representing some subset of patient care areas within the hospital. Transition probabilities and patient length of stay were fit using three years of patient data.
In designing our simulator, we were able to minimize assumptions about how healthcare workers and patients move, avoiding the “random mixing” assumption common to many infectious disease simulators. We translated techniques from location-aware search into the hospital environment, developed data structures for use in efficiently processing millions of location data points in tens of thousands of rooms for thousands of healthcare workers, improved the performance of the algorithm for identifying optimal single-center healthcare worker models, and introduced heuristics for training multi-center models. We validated our models by comparing the properties of simulated data to known quantities, and testing against expert expectations. To the best of our knowledge, this is the first agent-level hospital-wide simulator based on fine-grained location and interaction data for healthcare workers and patients.
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Hübner, Katrin. "Computational lipidology." Doctoral thesis, Humboldt-Universität zu Berlin, Mathematisch-Naturwissenschaftliche Fakultät I, 2008. http://dx.doi.org/10.18452/15827.
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Wichtige Marker in der klinischen Routine für die Risikoabschätzung von kardiovaskulären Erkrankungen (CVD) sind Blutcholesterinwerte auf Basis von Lipoproteinklassen wie ''schlechtes'' LDL oder ''gutes'' HDL. Dies vernachlässigt, dass jede Lipoproteinklasse eine nicht-homogene Population von Lipoproteinpartikeln unterschiedlicher Zusammensetzung aus Lipiden und Proteinen bildet. Studien zeigen zudem, dass solche Sub-populationen von Lipoproteinen im Stoffwechsel als auch im Beitrag zu CVD unterschiedlich sind. Mehrwert und routinemäßiger Einsatz einer detaillierteren Auftrennung von Lipoproteinen sind jedoch umstritten, da die experimentelle Fraktionierung und Analyse aufwendig, zeit- und kostenintensiv sind. Die vorliegende Arbeit ''Computational Lipidology'' präsentiert einen neuartigen Modellierungsansatz für die Berechnung von Lipoproteinverteilungen (Lipoproteinprofil) im Blutplasma, wobei erstmals individuelle Lipoproteinpartikel anstelle von Lipoproteinklassen betrachtet werden. Das Modell berücksichtigt elementare Bestandteile (Lipide, Proteine) und Prozesse des Stoffwechsel von Lipoproteinen. Stochastische wie deterministische Simulationen errechnen auf Basis aller Lipoproteinpartikel im System deren Dichteverteilung. Die Modellberechnungen reproduzieren erfolgreich klinisch gemessene Lipoproteinprofile von gesunden Patienten und zeigen Hauptmerkmale von pathologischen Situationen, die durch Störung eines der zugrundeliegenden molekularen Prozesse verursacht werden. Hochaufgelöste Lipoproteinprofile zeigen die Verteilung von sogenannten ''high-resolution density sub-fractions'' (hrDS) innerhalb von Hauptlipoproteinklassen. Die Ergebnisse stimmen mit klinischen Beobachtungen sehr gut überein, was die Arbeit als einen signifikanten Schritt in Richtung Analyse von individuellen Unterschieden, patienten-orientierte Diagnose von Fettstoffwechselstörungen und Identifikation neuer Sub-populationen von potentiell klinischer Relevanz qualifiziert.Monitoring the major lipoprotein classes, particularly low-density lipoproteins (''bad'' LDL) and high-density lipoproteins (''good'' HDL) for characterizing risk of cardiovascular disease (CVD) is well-accepted and routine in clinical practice. However, it is only one-half of the truth as lipoprotein classes comprise non-homogeneous populations of lipoprotein particles varying significantly in their composition of lipids and apolipoproteins. Various studies have shown differing metabolic behavior and contribution to CVD of individual lipoprotein sub-populations. Nevertheless, the superiority of more detailed lipoprotein fractionation is still a matter of debate because experimental separation and analysis is an elaborate, time-consuming and expensive venture and not yet worthwhile for routine measurements. The present work ''Computational Lipidology'' aims at establishing a novel modeling approach to calculate the distribution of lipoproteins (lipoprotein profile) in blood plasma being the first that settles on individual lipoprotein complexes instead of common lipoprotein classes. Essential lipoprotein constituents and processes involved in the lipoprotein metabolism are taken into account. Stochastic as well as deterministic simulations yield the distribution of lipoproteins over density based on the set of individual lipoprotein complexes in the system. The model calculations successfully reproduce lipoprotein profiles measured in healthy subjects and show main characteristics of pathological situations elicited by disorder in one of the underlying molecular processes. Moreover, the model reveals the distribution of high-resolution lipoprotein sub-fractions (hrDS) within major density classes. The results show satisfactory agreement with clinical observations which qualifies the work as a significant step towards analyzing inter-individual variability, patient-oriented diagnosis of lipid disorders and identifying new sub-fractions of potential clinical relevance.
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San, Omer. "Multiscale Modeling and Simulation of Turbulent Geophysical Flows." Diss., Virginia Tech, 2012. http://hdl.handle.net/10919/28031.
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The accurate and efficient numerical simulation of geophysical flows is of great interest in numerical weather prediction and climate modeling as well as in numerous critical areas and industries, such as agriculture, construction, tourism, transportation, weather-related disaster management, and sustainable energy technologies. Oceanic and atmospheric flows display an enormous range of temporal and spatial scales, from seconds to decades and from centimeters to thousands of kilometers, respectively. Scale interactions, both spatial and temporal, are the dominant feature of all aspects of general circulation models in geophysical fluid dynamics. In this thesis, to decrease the cost for these geophysical flow computations, several types of multiscale methods were systematically developed and tested for a variety of physical settings including barotropic and stratified wind-driven large scale ocean circulation models, decaying and forced two-dimensional turbulence simulations, as well as several benchmark incompressible flow problems in two and three dimensions. The new models proposed here are based on two classes of modern multiscale methods: (i) interpolation based approaches in the context of the multigrid/multiresolution methodologies, and (ii) deconvolution based spatial filtering approaches in the context of large eddy simulation techniques. In the first case, we developed a coarse-grid projection method that uses simple interpolation schemes to go between the two components of the problem, in which the solution algorithms have different levels of complexity. In the second case, the use of approximate deconvolution closure modeling strategies was implemented for large eddy simulations of large-scale turbulent geophysical flows. The numerical assessment of these approaches showed that both the coarse-grid projection and approximate deconvolution methods could represent viable tools for computing more realistic turbulent geophysical flows that provide significant increases in accuracy and computational efficiency over conventional methods.Ph. D.
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Kuhlman, Christopher J. "High Performance Computational Social Science Modeling of Networked Populations." Diss., Virginia Tech, 2013. http://hdl.handle.net/10919/51175.
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Dynamics of social processes in populations, such as the spread of emotions, influence, opinions, and mass movements (often referred to individually and collectively as contagions), are increasingly studied because of their economic, social, and political impacts. Moreover, multiple contagions may interact and hence studying their simultaneous evolution is important. Within the context of social media, large datasets involving many tens of millions of people are leading to new insights into human behavior, and these datasets continue to grow in size. Through social media, contagions can readily cross national boundaries, as evidenced by the 2011 Arab Spring. These and other observations guide our work. Our goal is to study contagion processes at scale with an approach that permits intricate descriptions of interactions among members of a population. Our contributions are a modeling environment to perform these computations and a set of approaches to predict contagion spread size and to block the spread of contagions. Since we represent populations as networks, we also provide insights into network structure effects, and present and analyze a new model of contagion dynamics that represents a person\'s behavior in repeatedly joining and withdrawing from collective action. We study variants of problems for different classes of social contagions, including those known as simple and complex contagions.Ph. D.
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Doro, Emmanuel O. "Computational modeling of falling liquid film free surface evaporation." Diss., Georgia Institute of Technology, 2012. http://hdl.handle.net/1853/44812.
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A computational model is developed to investigate fundamental flow physics and transport phenomena of evaporating wavy-laminar falling liquid films of water and black liquor. The computational model is formulated from first principles based on the conservation laws for mass, momentum, energy and species in addition to a phase transport equation for capturing interface deformation and evolution. Free surface waves are generated by monochromatic perturbation of velocity. Continuum models for interfacial evaporation define source terms for liquid vaporization and species enrichment in the conservation laws. A phenomenological crystallization model is derived to account for species depletion due to salt precipitation during black liquor falling film evaporation. Using highly resolved numerical grids on parallel computers, the computational model is implemented to analyze the dynamics of capillary separation eddies in low Reynolds number falling films, investigate the dominant mechanisms of heat transfer enhancement in falling films at moderately high Reynolds numbers and study the fundamental wave structures and wave induced transport in black liquor falling films on flat and cylindrical walls. From simulation results, a theory based on the dynamics of wavefront streamwise pressure gradient is proposed to explain interfacial waves interaction that give rise to multiple backflow regions in films dominated by solitary-capillary waves. The study shows that the mechanism of heat transfer enhancement in moderately high Reynolds number films follows from relatively lower conduction thermal resistance and higher crosswise convective transport at newly formed intermediate wavefronts. Interfacial phenomena such as wave-breaking and vapor entrainment observed in black liquor falling films is explained in terms of a mechanistic theory based on evolution of secondary instabilities and large amplitude wave force imbalances.
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Brown, Jason. "Computational fluid dynamics in an equation-based, acausal modeling environment." Diss., Georgia Institute of Technology, 2010. http://hdl.handle.net/1853/37247.
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The practice of building simulation is split between domains such as energy, multizone airflow, computational fluid dynamics (CFD) airflow, and controls analysis, as well as between the tools which conduct these analyses. Previous work in the integration of these analyses and tools have focused on linking existing tools, written in algorithmic programming languages, together by interfacing them using coupling mechanisms implemented in algorithmic programming languages. This thesis takes a different approach, using the equation-based, object oriented modeling language Modelica to create models in different domains and interfaces between those models within a single framework which has benefits to the modeler/analyst in terms of both representation of physical processes and flexibility in modeling systems composed of many interacting components.
Specifically, the simulation of airflows within buildings has historically been compartmentalized into distinct domains such as nodal network (multizone) simulations and CFD. Such airflow simulations are also often treated independently of building energy simulations (via heat transfer) despite their interrelation. Recent work has reported on combining these types of analyses by linking pre-existing simulation software together. Here a prototype CFD package of models is built in Modelica and coupled to models of conductive heat transfer and controls. Comparisons of results of simulations so constituted to analytical solutions and benchmark data available in the literature show good agreement, indicating the technical viability of this approach. Limitations include the absence of turbulence modeling and the lack of modeling features which improve computational efficiency, such as non-uniform grids.
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Geiser, Kyle. "Computational modeling and simulation for projectile impact and indentation of biological tissues and polymers." Thesis, Massachusetts Institute of Technology, 2017. http://hdl.handle.net/1721.1/112507.
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Thesis: S.M., Massachusetts Institute of Technology, Department of Biological Engineering, 2017.Cataloged from PDF version of thesis.
Includes bibliographical references (pages 89-95).
Understanding the elastic and viscoelastic responses of biological soft tissues and engineered polymer simulants is of great interest to predicting and preventing penetrative injuries. Detailed understanding of the mechanical processes at work could aid in the development and evaluation of protective strategies such as armor and helmets, and repair strategies including robotic surgery or needle-based drug delivery. However, due to the mechanical complexity of so-called "soft tissues," including nonlinear viscoelastic behavior, surface adhesion, material failures and shock effects, the experimental characterization of various soft tissues is challenging and individual mechanical processes are often impossible to decouple without computational models and simulations. This thesis presents two finite element models designed to provide both replicate the results of indentation and impact experiments on synthetic polymers, aimed to decouple competing mechanical characteristics of contact based deformation. The first of these models describes the indentation on polydimethylsiloxane bilayer composites, with the aim of describing the relative effects of a adhesion and viscoelastic properties on the measured deformation response. That model expands on this objective via the analysis of the effects of surface adhesion commonly associated with highly compliant polymers and tissues. The second model attempts to replicate impact of a high velocity projectile on a relatively stiff material, polyurethane urea, and on a comparatively compliant polymer, gelatin hydrogel. These models provide means to simulate, predict and characterize material response, validated by comparison with available experiments. Such validated models can be used to simulate and design new materials as tissue simulants or as protective media that predictably dissipate concentrated mechanical impact.
by Kyle Geiser.
S.M.
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Iwashita, Takuya. "Computational Studies on the Dynamics of Small-Particle Suspensions using Meso-Scale Modeling." 京都大学 (Kyoto University), 2009. http://hdl.handle.net/2433/77956.
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Wang, Xuguang. "Spatial Adaptive Crime Event Simulation With RA/CA/ABM Computational Laboratory." University of Cincinnati / OhioLINK, 2005. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1108526413.
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O'Brien, Sean. "Polyethylene wear modeling in modular total knee replacements using finite element simulation." Journal of Engineering in Medicine, 2011. http://hdl.handle.net/1993/5106.
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A computational model for the prediction of articular and backside polyethylene (PE) wear of total knee replacements (TKRs) could enable the optimization of TKRs for the reduction of polyethylene wear, thereby improving the long term success of TKRs. A finite element model was developed for the TKR and the results were implemented in a computational wear model to assess PE wear. The wear factors of Archard’s wear law were identified by implementing the finite element simulation results along with knee simulator wear test results. Archard’s wear law was found to have insufficient accuracy for the purpose of optimization. Therefore, a novel computational wear model was developed by the author based on a theoretical understanding of the molecular behavior of PE. The model predicted result fell within the standard deviation of the independent knee simulator wear test results, indicating a high level of accuracy for the novel computational wear model.
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Kohn, Harold D. "A Test of Abelson and Baysinger's (1984) Optimal Turnover Hypothesis in the Context of Public Organizations using Computational Simulation." Diss., Virginia Tech, 2008. http://hdl.handle.net/10919/26658.
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Both practitioners and researchers have long noted that employee turnover creates both positive and negative consequences for an organization. From a management perspective, the question is how much turnover is the right amount. Abelson and Baysinger (1984) first proposed that an optimal level of turnover could be found based on individual, organizational, and environmental factors. However, as Glebbeek and Bax (2004) noted, their approach was overly complex to empirically verify, let alone utilize at the practitioner level.
This study is an attempt to demonstrate whether a logic- and theory-based model and computational simulation of the employee turnover-organizational performance relationship can actually produce Abelson and Baysinger's optimal turnover curve (the inverted U-shape) when studied in the context of a public organization. The modeling approach is based on developing and integrating causal relationships derived from logic and the theory found in the literature. The computational approach used parallels that of Scullen, Bergey, and Aiman-Smith (2005).
The level of analysis of this study is the functional department level of large public organizations placing it below the macro level of entire agencies as studied in public administration, but above the level of small group research. The focus is on agencies that employ thousands of employees in specific professional occupations such as engineers, attorneys, and contract specialists.
Employee attrition (equivalent to turnover as this model has been structured) is the independent variable. Workforce performance capacity and staffing costs are the dependent variables. Work organization and organizational “character” (i.e., culture, HRM policies, and environment) are moderating elements that are held constant. Organizational parameters and initial conditions are varied to explore the problem space through the use of a number of case scenarios of interest. The model examines the effects on the dependent variables of annual turnover rates ranging from 0% to 100% over a 10-year period. Organizational size is held constant over this period.
The simulation model introduces several innovative concepts in order to adapt verbal theory to mathematical expression. These are an organizational stagnation factor, a turbulence factor due to turnover, and workforce performance capacity. Its value to research comes from providing a framework of concepts, relationships, and parametric values that can be empirically tested such as through comparative analyses of similar workgroups in an organization. Its value for management lies in the conceptual framework it provides for logical actions that can be taken to control turnover and/or mitigate turnover's impact on the organization.
The simulation model used a 100-employee construct as per Scullen, Bergey, and Aiman-Smith (2005), but was also tested with 1000 employees as well and no significant differences in outcome were found. Test cases were run over a 10-year period. The model was also run out to 30 years to test model stability and no instability was found.
Key findings and conclusions of the analysis are as follows: 1. Results demonstrate that Abelson and Baysinger's (1984) inverted-U curve can occur, but only under certain conditions such as bringing in higher-skilled employees or alleviating stagnation. 2. Results support Scullen, Bergey, and Aiman-Smith's (2005) findings that workforce performance potential increases under the condition of increasing the quality of replacement employees. 3. Organizational type, as defined in the public administration literature, does not affect the results.
In addition, an analysis of recent empirical work by Meier and Hicklin (2007) who examine the relationship between employee turnover and student test performance using data from Texas school districts is provided as an Addendum. This analysis demonstrates how the modeling and simulation methodology can be used to analyze and contribute to theory development based in empirical research.Ph. D.
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Aussel, Amélie. "Computational modeling of healthy and epileptic hippocampal oscillations." Electronic Thesis or Diss., Université de Lorraine, 2019. http://www.theses.fr/2019LORR0202.
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L'hippocampe peut présenter différents rythmes oscillatoires au cours du cycle veille-sommeil, chacun étant impliqué dans des processus cognitifs. Par exemple, des oscillations thêta-gamma sont produites pendant la veille et sont associés à la navigation spatiale et la mémoire à court terme, tandis que des complexes sharp-wave-ripples, produits durant les périodes de sommeil lent profond, jouent un rôle important dans la consolidation de la mémoire. Des modèles existent pour reproduire chacun de ces rythmes, cependant les mécanismes impliqués dans leur génération et les transitions entre eux ne sont pas encore parfaitement compris. Cette question est d'autant plus importante qu'une altération des rythmes hippocampiques est impliquée dans l'épilepsie du lobe temporal médian phamaco-résistante, une forme courante d'épilepsie qui ne peut pas être contrôlée par les traitements médicamenteux existants. Des modèles ont aussi été développés pour reproduire des crises d'épilepsie ou des pointes intercritiques, mais ces modèles ne parviennent pas à expliquer entièrement les liens entre les conditions neuropathologiques de l'hippocampe, des processus physiologiques comme le cycle veille-sommeil, et les oscillations qui en résultent. Dans ce contexte, l'objectif principal de cette thèse est d'apporter une meilleure compréhension de diverses oscillations hippocampiques, tant physiologiques que pathologiques. Pour ce faire, nous développons tout d'abord un modèle computationnel de l'hippocampe sain incluant au total plus de trente mille neurones Hodgkin-Huxley, représentés par des dizaines de milliers d'équations différentielles résolues numériquement, et comprenant une estimation du potentiel extracellulaire (LFP) généré par les neurones dipolaires tel que mesuré par une électrode macroscopique afin d'être plus facilement interprété. Nous effectuons ensuite une étude complète de l'activité de notre réseau basée sur des plans d'expérience afin d'étudier le rôle des paramètres intrinsèques du modèle et l'importance de la stimulation en entrée dans la production de différents rythmes couplés. Par la suite, notre modèle est évalué dans un contexte réaliste: l'activité qu'il génère quand il est soumis à des entrées réalistes est comparée avec des enregistrements intracérébraux obtenus sur des patients épileptiques. Nous montrons ainsi que notre modèle est capable de générer des oscillations de veille ou de sommeil similaires aux signaux cliniques sur le plan temporel et fréquentiel. Nous relions les modifications de paramètres du modèle (gains synaptiques et conductances de canaux ioniques) à une modulation cholinergique, et montrons comment les dynamiques des neurones influencent principalement les oscillations basse fréquence, tandis que la connectivité fonctionnelle contrôle les oscillations haute fréquence. Enfin, nous détaillons davantage notre modèle afin d'inclure quatre modifications de l'hippocampe observées dans les cas d'épilepsies du lobe temporal médian, à savoir la sclérose hippocampique, le bourgeonnement des fibres moussues, et une altération des dynamiques potassiques et chloriques (qui se traduisent par des modifications de la connectivité du réseau ou des paramètres des neurones individuels), et montrons comment ces mécanismes peuvent interagir avec le cycle veille-sommeil décrit précédemment pour donner lieu à des synchronisations et rythmes pathologiques. En conclusion, nous proposons dans cette thèse un modèle unique de l'hippocampe regroupant divers mécanismes précédemment décrits dans des travaux séparés, et analysons son activité oscillatoire tandis que nous varions différents paramètres représentant les propriétés structurelles et fonctionnelles du réseau, ainsi que des modifications pathologiques observées en épilepsie. Nos résultats apportent un nouvel éclairage sur les mécanismes impliqués dans la génération des oscillations hippocampiques, qui pourraient ouvrir la voie à de futures applications cliniquesThe hippocampus can exhibit different oscillatory rhythms within the sleep-wake cycle, each of them being involved in cognitive processes. For example, theta-nested gamma oscillations, consisting of the coupling of theta and gamma rhythms, are produced during wakefulness and are associated with spatial navigation and working memory tasks, whereas sharp-wave-ripple complexes, consisting of fast oscillatory events occurring during low frequency waves, are produced during slow-wave sleep and quiet waking and play an important role in memory consolidation. Models exist to reproduce and explain the generation of each of these rhythms, yet the mechanisms involved in their generation and the transitions between them are not yet fully understood. This question is all the more important that altered hippocampal rhythms are involved in drug-resistant mesial temporal lobe epilepsy, a common form of epilepsy which cannot be controlled by existing pharmaceutical treatments. Some models have also been previously developed to reproduce epileptic seizures (episodes of excessive neural activity) or interictal discharges (brief peaks of synchronous activity), but these models cannot fully explain the links between neuropathological conditions of the hippocampus, physiological processes such as the sleep-wake cycle, and the resulting oscillations. In this context, the main objective of this thesis is to provide better understanding of various hippocampal oscillations, both physiological and pathological. To do so, we first design a full computational model of the healthy hippocampal formation including the entorhinal cortex, the dentate gyrus and the CA3 and CA1 regions. This model includes more than thirty thousand Hodgkin-Huxley point neurons, represented by tens of thousands differential equations to be solved numerically, as well as an estimation of the extracellular potentials (LFP) generated by the dipolar neurons as measured by a macroscopic electrode, so as to be more easily interpretable. We perform a thorough study of our model's activity based on design of experiments techniques to identify the role of each of its intrinsic parameters and the importance of input stimulation in the production coupled oscillatory outputs. We then evaluate our model in a realistic context : its activity under realistic input stimulation is compared with intracranial recordings obtained in epileptic patients. We demonstrate that our model is able to reproduce both sleep and wakefulness oscillations with temporal and frequential similarities with the clinically measured signals. We link the modification of some parameters of the model (synaptic gains and ion channel conductances) with cholinergic modulation, and show how single neuron dynamics are mostly responsible for the frequency of slow oscillations of our network, while network functional connectivity controls its fast oscillations. Finally, we detail our model further to include four pathological modifications of the hippocampus seen in mesial temporal lobe epilepsies, that is hippocampal sclerosis, mossy fiber sprouting, and impaired potassium and chloride dynamics in pyramidal neurons (which are modeled by changing the network connectivity or the parameters of individual neuron dynamics), and show how these mechanisms can interact with the previously described sleep-wake cycle and lead to pathological synchrony and rhythms such as seizures, interictal spikes and fast ripples. In conclusion, we propose in this thesis a unique model of the hippocampus regrouping many mechanisms previously described in separate works, and analyze its oscillatory activity as we vary different parameters representing either structural or functional properties of the network, as well as pathological modifications observed in epilepsy. Our results provide new insights into the mechanisms underlying the generation of various hippocampal oscillations, which could open the way to future clinical applications
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Mclaughlin, Keith. "Development of Improved Models for Gas Sorption Simulation." Scholar Commons, 2013. http://scholarcommons.usf.edu/etd/4916.
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Computational chemistry offers one the ability to develop a better understanding of the complex physical and chemical interactions that are fundamental to macro- and mesoscopic processes that are seen in laboratory experiments, industrial processes, and ordinary, everyday life. For many systems, the physics of interest occur at the molecular or atomistic levels, and in these cases, computational modeling and two well refined simulation techniques become invaluable: Monte Carlo (MC) and molecular dynamics (MD). In this work, two well established problems were tackled. First, models and potentials for various gas molecules were produced and refined from first principles. These models, although based on work done previously by Belof et al., are novel due to the inclusion of many-body van der Waals interactions, advanced r-12 repulsion combining rules for treating unlike intra- and intermolecular interactions, and highly-efficient treatment of induction interactions. Second, a multitude of models were developed and countless MD simulations were performed in order to describe and understand the giant frictional anisotropy of d-AlCoNi, first observed by Park et al. in 2005.
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Cheng, Jingjing. "Shaken baby syndrome : simulation via computational and physical modelling." Thesis, University of Sheffield, 2008. http://etheses.whiterose.ac.uk/6116/.
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The terms "abusive head injury" and "shaken baby syndrome" refer to a unique pattern of non-accidental traumatic injury occurring in children that many clinicians and researchers have good reason to believe is caused by violent shaking. Typical injuries include subdural haemorrhage, retinal haemorrhage as well as tears to cortical bridging veins. A major paradox is that the injuries induced by a shaking event are much more severe than those caused by even violent single - impact head trauma, despite the relatively low accelerations in shaking. Infants younger than 6 months are significantly more vulnerable to the shaken baby syndrome than older infants and children, and one possible explanation is given that the softness of the infant brain and compliant skull structure allows violent motions to be set up (Cheng et al. 2005). These new mechanisms, could have an important role in explaining the basic mechanics of shaken baby syndrome. Several models of infant head have been created with the optimized anatomical detail and accurate constitutive material properties from literature. The driving input to these models is derived from data generated in our research programme at the Transport Research Laboratory (TRL) (Brudenell 2000) with the theory of kinematics rigid body reconstruction. Numerical simulations are applied by using the finite element system LS-DYNA, and the consequences have been correlated with clinically observed damage in infant victims, and the brain skull boundary condition is investigated via the fluid structure interaction (FSI) method. A shaking testing apparatus has been custom designed with computer aided design methodology (CAD), and is manufactured and assembled in the workshop. The driving of the rig is able to apply stable, repetitive linear motion within the range of accuracy and magnitude of human shaking. An experimental model has been constructed and mounted on the rig with important structures consisting of brain, cerebrospinal fluid (CSF), skull and infantile membrane. The system validates the computational modelling by demonstrating the relative motion of the continuum system within the transparent skull replica. The research, as a first exploration in this area, contributes to the study of the infant abusive head injury, and is able to draw the data together in a discussion of the implications for the mechanics of the shaken baby syndrome.
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Noetscher, Gregory Michael. "The VHP-F Computational Phantom and its Applications for Electromagnetic Simulations." Digital WPI, 2014. https://digitalcommons.wpi.edu/etd-dissertations/237.
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Modeling of the electromagnetic, structural, thermal, or acoustic response of the human body to various external and internal stimuli is limited by the availability of anatomically accurate and numerically efficient computational models. The models currently approved for use are generally of proprietary or fixed format, preventing new model construction or customization. 1. This dissertation develops a new Visible Human Project - Female (VHP-F) computational phantom, constructed via segmentation of anatomical cryosection images taken in the axial plane of the human body. Its unique property is superior resolution on human head. In its current form, the VHP-F model contains 33 separate objects describing a variety of human tissues within the head and torso. Each obejct is a non-intersecting 2-manifold model composed of contiguous surface triangular elements making the VHP-F model compatible with major commercial and academic numerical simulators employing the Finite Element Method (FEM), Boundary Element Method (BEM), Finite Volume Method (FVM), and Finite-Difference Time-Domain (FDTD) Method. 2. This dissertation develops a new workflow used to construct the VHP-F model that may be utilized to build accessible custom models from any medical image data source. The workflow is customizable and flexible, enabling the creation of standard and parametrically varying models facilitating research on impacts associated with fluctuation of body characteristics (for example, skin thickness) and dynamic processes such as fluid pulsation. 3. This dissertation identifies, enables, and quantifies three new specific computational bioelectromagnetic problems, each of which is solved with the help of the developed VHP-F model: I. Transcranial Direct Current Stimulation (tDCS) of human brain motor cortex with extracephalic versus cephalic electrodes; II. RF channel characterization within cerebral cortex with novel small on-body directional antennas; III. Body Area Network (BAN) characterization and RF localization within the human body using the FDTD method and small antenna models with coincident phase centers. Each of those problems has been (or will be) the subject of a separate dedicated MS thesis.
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Edmonds, Christopher Michael. "Computational investigations of biopolymer translocation through nanopore devices." Diss., Georgia Institute of Technology, 2013. http://hdl.handle.net/1853/50260.
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Nanopores (1 – 10 nm diameter) constructed in solid-state membranes, have shown promise as next-generation biopolymer analysis devices offering both high resolution and high throughput. One promising application of nanopores is in the analysis of nucleic acids, such as DNA. This involves translocation experiments in which DNA is placed in an ionic solution and is forced through a nanopore with the aid of an applied electric field. The modulation of ionic current through the pore during DNA translocation can then be correlated to various properties of the biopolymer such as the length.
To optimally design and operate nanopore devices, it would be advantageous to develop an accurate computer simulation methodology to predict the physics of the translocation process. Hence, I have developed a physically accurate, computationally efficient simulation methodology to predict and analyze the physics of biopolymer translocation through solid-state (silicon nitride) nanopores. The overall theme of this thesis is to use this simulation methodology to thoroughly investigate important issues in the physics underlying translocation experiments and thereby determine the effects of key structural and operation parameters, such as nanopore dimensions, applied voltage, hydrodynamic interactions, solvent viscosity, and the polymer chain length. The results from these simulation studies can assist in not only proper nanopore design, but also help determine the proper experimental environments and parameters for nanopore operation.
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Petrauskas, Karolis. "Computational Modelling of Biosensors of Complex Geometry." Doctoral thesis, Lithuanian Academic Libraries Network (LABT), 2011. http://vddb.laba.lt/obj/LT-eLABa-0001:E.02~2011~D_20110701_105911-89480.
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Biosensors are analytical devices mainly used to detect analytes and measure their concentrations. Mathematical modeling is widely used for optimizing and analyzing an operation of biosensors for reducing price of development of new biosensors. The object of this research is mathematical and computer models, describing an operation of biosensors, made of several parts with different properties. The dissertation covers models, formulated in one and two-dimensional spaces by partial differential equations with non-linear members, and solved numerically, using the method of finite differences. The numerical models are implemented by a computer program. An original mathematical model for a biosensor with a carbon nanotube electrode is presented in the dissertation. The conditions at which the one-dimensional mathematical model can be used instead of two-dimensional one for accurate prediction of the biosensor response are investigated. Elements, used to build models of biosensors with a complex structure, were systemized. The biosensor description language is proposed and the computer software, simulating an operation of biosensors in the one-dimensional space and a rectangular domain of the two-dimensional space, is developed. An adequateness of the model for the biosensor with the carbon nanotube electrode and the impact of structural and geometrical properties on a response of the biosensor were investigated, performing computer experiments using the developed software.Biojutikliai yra įrenginiai, skirti medžiagoms aptikti bei jų koncentracijoms matuoti. Siekiant sumažinti biojutiklių gamybos kaštus yra pasitelkiamas matematinis biojutikliuose vykstančių procesų modeliavimas. Disertacijoje nagrinėjami matematiniai ir kompiuteriniai biojutiklių modeliai, aprašantys biojutiklių, sudarytų iš kelių, skirtingas savybes turinčių dalių, veikimą. Nagrinėjami modeliai yra formuluojami vienmatėje bei dvimatėje erdvėse, aprašomi diferencialinėmis lygtimis dalinėmis išvestinėmis su netiesiniais nariais ir yra sprendžiami skaitiškai, naudojant baigtinių skirtumų metodą. Skaitiniai modeliai yra įgyvendinami kompiuterine programa. Disertacijoje pateikiamas originalus matematinis modelis biojutikliui su anglies nanovamzdelių elektrodu, nustatyti kriterijai, apibrėžiantys, kada biojutiklį su perforuota membrana galima modeliuoti vienmačiu modeliu. Darbe susisteminti elementai, naudojami biojutiklių modelių formulavimui, pagrindinį dėmesį skiriant biojutiklio struktūrinėms savybėms modeliuoti. Apibrėžta biojutiklių modelių aprašo kalba ir sukurta programinė įranga, leidžianti modeliuoti biojutiklių veikimą vienmačiais modeliais arba modeliais, formuluojamais stačiakampėje dvimatės erdvės srityje. Taikant sukurtą biojutiklių modeliavimo programinę įrangą, ištirtas biojutiklio su anglies nanovamzdelių elektrodu modelio adekvatumas ir struktūrinių bei geometrinių savybių įtaka biojutiklio elgsenai.
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Hradisky, Michal. "Turbulence Modeling of Strongly Heated Internal Pipe Flow Using Large Eddy Simulation." DigitalCommons@USU, 2011. https://digitalcommons.usu.edu/etd/925.
Full textAbstract:
The main objective of this study was to evaluate the performance of three Large Eddy Simulation (LES) subgrid scale (SGS) models on a strongly heated, low Mach number upward gas flow in a vertical pipe with forced convection. The models chosen for this study were the Smagorinsky-Lilly Dynamic model (SLD), the Kinetic Energy Transport model (KET), and the Wall-Adaptive Local-Eddy viscosity model (WALE). The used heating rate was sufficiently large to cause properties to vary significantly in both the radial and streamwise directions. All simulations were carried out using the commercial software FLUENT.
The effect of inlet turbulence generation techniques was considered as well. Three inlet turbulence generation techniques were compared, namely, the Spectral Synthesizer Method (SSM), the Vortex Method (VM), and the Generator (GEN) technique. A user-defined function (UDF) was written to implement the GEN technique into the solver; the SSM and VM techniques were already build-in. All simulation and solver settings were validated by performing computational simulations of isothermal fully developed pipe flow and results were compared to available experimental and Direct Numerical Simulation (DNS) data.
For isothermal boundary conditions, among the three inlet turbulence generation techniques, the GEN technique produced results which best matched the experimental and DNS results. All three LES SGS models performed equally well when coupled with the GEN technique for the study of isothermal pipe flow. However, all models incorrectly predicted the behavior of radial and circumferential velocity fluctuations near the wall and the GEN technique proved to be the most computationally expensive. For simulations with longer computational domain, the effect of the inlet turbulence generation technique diminishes. However, results suggest that both the SLD and KET models need shorter computational domains to recover proper LES behavior when coupled with the VM technique in comparison to the WALE SGS model with the same turbulence inlet generation technique.
For high heat flux simulations all SGS models were coupled with the VM technique to decrease the computational effort to obtain statistically steady-state solution. For comparative purposes, one simulation was carried out using the WALE and GEN techniques. All simulations equally significantly underpredicted the streamwise temperature distribution along the pipe wall as well as in the radial directions at various streamwise locations. These effects are attributed to the overpredicted streamwise velocity components and incorrect behavior of both the radial and circumferential velocity components in the near wall region for all subgrid scale models.
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Fors, Jonathan. "Modeling and OpenFOAM simulation of streamers in transformer oil." Thesis, Linköpings universitet, Institutionen för fysik, kemi och biologi, 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-80932.
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Electric breakdown in power transformers is preceded by pre-breakdown events such as streamers. The understanding of these phenomena is important in order to optimize liquid insulation systems. Earlier works have derived a model that describes streamers in transformer oil and utilized a finite element method to produce numerical solutions. This research investigates the consequences of changing the numerical method to a finite volume-based solver implemented in OpenFOAM. Using a standardized needle-sphere geometry, a number of oil and voltage combinations were simulated, and the results are for the most part similar to those produced by the previous method. In cases with differing results the change is attributed to the more stable numerical performance of the OpenFOAM solver. A proof of concept for the extension of the simulation from a two-dimensional axial symmetry to three dimensions is also presented.Elektriska genomslag i högspänningstransformatorer föregås av bildandet av elektriskt ledande kanaler som kallas streamers. En god förståelse av detta fenomen är viktigt vid konstruktionen av oljebaserad elektrisk isolation. Tidigare forskning i ämnet har tagit fram en modell för fortplantningen av streamers. Denna modell har sedan lösts numeriskt av ett beräkningsverktyg baserat på finita elementmetoden. I denna uppsats undersöks konsekvenserna av att byta metod till finita volymsmetoden genom att implementera en lösare i OpenFOAM. En standardiserad nål-sfär-geometri har ställts upp och ett flertal kombinationer av oljor och spänningar har simulerats. De flesta resultaten visar god överensstämmande med tidigare forskning medan resultat som avviker har tillskrivits de goda numeriska egenskaperna hos OpenFOAM-lösaren. En ny typ av simulering har även genomförts där simulationen utökas från en tvådimensionell axisymmetrisk geometri til tre dimensioner.
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Andrews, Brian. "Computational Solutions for Medical Issues in Ophthalmology." Case Western Reserve University School of Graduate Studies / OhioLINK, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=case15275972120621.
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Guion, Alexandre Nicolas. "Modeling and simulation of liquid microlayer formation and evaporation in nucleate boiling using computational fluid dynamics." Thesis, Massachusetts Institute of Technology, 2017. http://hdl.handle.net/1721.1/112380.
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Thesis: Ph. D., Massachusetts Institute of Technology, Department of Nuclear Science and Engineering, 2017.This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.
Cataloged from student-submitted PDF version of thesis.
Includes bibliographical references (pages 243-252).
The transport of latent heat makes boiling one of the most efficient modes of heat transfer, allowing a wide range of systems to improve their thermal performance, from microelectronic devices to nuclear power plants. In particular, Boiling Water Reactors (BWR) use boiling as the primary mode of heat transfer in the reactor core to accommodate very high heat fluxes. In Pressurized Water Reactors (PWR) subcooled flow boiling can occur in hot sub-channels. As a bubble grows outside of a surface imperfection during nucleate boiling, viscous stresses at the wall can be strong enough to impede liquid motion and trap a thin liquid layer - referred to as microlayer, underneath the growing bubble. The contribution of microlayer evaporation to overall heat transfer and bubble growth can be large, in particular in the case of water1. In practice, numerical simulations of nucleate boiling resolve the macroscopic interface of the bubble and resort to subgrid models to account for the evaporation of the microlayer at the microscopic scale. The applicability of this subgrid modeling approach relies on the capacity to initialize the microlayer shape and extension, prior to its evaporation. However, existing models of microlayer formation are either physically incomplete2 or purely empirical3. In this work, we first confirm through a sensitivity study the need for accurate modeling of microlayer formation to initialize boiling simulations and to reproduce physical boiling dynamics (a). Then, we build the first generally applicable model for microlayer formation through direct computations of the hydrodynamics of bubble growth at the wall for a wide range of conditions and fluids, including water at 0.101MPa (lab experiments) and 15.5MPa (PWR), capillary numbers Ca [is element of] [0.001; 0.1], and contact angles [theta] [is element of] [10°; 90°] (b). In addition, we modify an existing experimental pool boiling setup to measure with unprecedented accuracy initial bubble growth rates needed to predict microlayer formation (c). Lastly, we develop a numerical procedure based on hydrodynamics theories to obtain mesh-independent results in moving contact line simulations for a wide range of contact angles and viscosity ratios (d). In particular, we use direct computations of the transition to a Landau-Levich-Derjaguin film in forced dewetting to inform the onset of microlayer formation in nucleate boiling. These contributions(a) (b) (c) (d) bridge a significant gap in our understanding of how boiling works and can be modeled at the microscopic scale, which represents a first step in designing surfaces with higher heat transfer performance and in building safer and more efficient energy systems.
by Alexandre Nicolas Guion.
Ph. D.
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Vincent, Timothy John. "Computational Modeling and Simulation of Thermal-Fluid Flow and Topology Formation in Laser Metal Additive Manufacturing." University of Dayton / OhioLINK, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=dayton1512398718245784.
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Karlsson, Gunnar. "Diffusion in Poly(vinyl alcohol) and Polyethylene as Determined by Computational Simulations and Modeling." Doctoral thesis, KTH, Polymer Technology, 2002. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-3370.
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Poly(vinyl alcohol) and polyethylene polymer systems werebuilt in order to study their transport properties (diffusion).First a verification of the AMBER force field was conducted fora poly(vinyl alcohol) system built from a chain with 145repeating units. NPT-molecular dynamics simulations attemperatures between 400 and 527 K were performed. The resultsof the simulations were compared withpressure-volume-temperature data, solubility parameter, X-rayscattering pattern and data for the characteristic ratio. Thefractional free volume distribution was computed and thediffusion characteristics of water in the polymer werestudied.
Further another poly(vinyl alcohol) system, with 600repeating units, was used to study oxygen diffusion in dry andwet poly(vinyl alcohol). In these systems the focus was toinvestigate the oxygen paths relative to the backbone and alsothe effect of water on the diffusion coefficients. Jump mapsand correlation function between the velocity of the oxygen wascalculated. The water has a huge impact on the oxygen diffusionand the preferred paths.
A larger molecule (limonene) was studied in a polyethylenematrix consisting of 6000 anisotropic united atoms. A 100 nslong trajectory was recorded and also shortertrajectories atdifferent temperatures, which gave the temperature dependenceof the diffusion coefficients. Correlation functions for thelimonene molecule shows that it rotates and tumbles when movingthru the matrix.
The main results from the molecular dynamics simulationsshowed that diffusion of larger molecules are possible and alsothat molecular dynamics simulations can predict plasticizationeffects.
A new fast experimental method for determining diffusioncoefficients with non iso thermal thermogravimetry weredeveloped. The advantage is that the experiments only takesminutes instead of days with a small effect on theaccuracy.
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Maurya, Abhilasha. "Computational simulation and analytical development of Buckling Resistant Steel Plate Shear Wall (BR-SPSW)." Thesis, Virginia Tech, 2012. http://hdl.handle.net/10919/34466.
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Steel plate shear walls (SPSWs) are an attractive option for lateral load resisting systems for both new and retrofit construction. They, however, present various challenges that can result in very thin web plates and excessively large boundary elements with moment connections, neither of which is economically desirable. Moreover, SPSW also suffers from buckling at small loads which results in highly pinched hysteretic behavior, low stiffness, and limited energy dissipation. To mitigate these shortcomings, a new type of SPSW has been developed and investigated. The buckling resistant steel plate shear wall (BR-SPSW) utilizes a unique pattern of cut-outs to reduce buckling. Also, it allows the use of simple shear beam-column connections and lends tunability to the shear wall system. A brief discussion of the concept behind the BR-SPSW is presented. A detailed parametric study is presented that investigates the sensitivity of the local and global system behavior to the geometric design variables using finite element models as the main tool. The key output parameters which define the system response are discussed in detail. Analytical solutions for some output parameters like strength and stiffness have been derived and resulting equations are proposed. Finally, preliminary suggestions have been made about how this system can be implemented in practice to improve the seismic resistance of the buildings. The proposed BR-SPSW system was found to exhibit relatively fuller hysteretic behavior with high resistance during the load reversals, without the use of moment connections.Master of Science
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Shi, Liming. "Computational Fluid Dynamics Simulation of Steam Reforming and Autothermal Reforming for Fuel Cell Applications." Ohio University / OhioLINK, 2009. http://rave.ohiolink.edu/etdc/view?acc_num=ohiou1234712316.
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Sarsam, Susan W. "Computational simulation technique : computational studies and molecular modelling of proteins coordinated by metal-based chemotherapeutic agents." Thesis, University of Reading, 2011. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.553144.
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Research in the field of titanium-based complexes as potential anticancer drugs has led to impressive results in vitro, but there is still scope for further improvements. Significant effort has been put into synthetic research and biological evaluation of titanocene derivatives, as well as the identification of their main biological targets. Surprisingly, the area of computer-aided drug design (CADD) has not been utilized up-to-date for the design of novel titanium-based compounds. The work within the thesis describes the computational approaches employed to study the mode of action of titanium-based anticancer agents, highlighting the structural features required for biological activity. Consequently, novel titanium-based derivatives were designed and synthesized. Furthermore, the synthetic attempts for amidosilyl-substituted titanocene and ferrocene derivatives with potentially enhanced activity are also reported. The first chapter provides a thorough introduction into the developments in the field of metal-based antitumour agents with a particular emphasis on titanium-based agents and assessment of their cytotoxic activity. Chapter 2 describes the first systematic receptor- based docking approach utilized to understand the binding mode of titanium-based agents against human serum albumin (RSA). The first 3D-QSAR study, which is reported in Chapter 3, was performed on a series of titanocene complexes to gain insight into the key structural features vital for their biological activity and to advance the design of potent titanocene anticancer agents. The successful synthesis of six novel benzyl-substituted titanocene derivatives, which have been designed based on the 3D-QSAR analysis is described in Chapter 4. Chapter 5 focuses on the attempts made for the synthesis of a range of amidosilyl-substituted titanium and iron-based metallocenes. Although the amidosilyl- substituted derivatives could not be obtained as pure compounds, six titanium and iron- based metallocenes were successfully synthesized. Chapter 6 summarizes the results obtained and provides suggestions for areas of future research.
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Buzolin, Prescila Glaucia Christianini. "Modelagem em simulação computacional do cristal e superfícies do BaZr'O IND. 3' e SrZr"O IND. 3': propriedades eletrônicas e estruturais /." Bauru : [s.n.], 2010. http://hdl.handle.net/11449/100924.
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Orientador: Julio Ricardo SambranoBanca: Aguinaldo Robinson de Souza
Banca: João Batista Lopes Martins
Banca: Sergio Ricardo de Lazaro
Banca: Carlton Anthony Taft
O Programa de Pós-Graduação em Ciência e Tecnologia de Materiais, PosMat, tem caráter institucional e integra as atividades de pesquisa em materiais de diversos campi da Unesp
Resumo: O crescente avanço tecnológico na área computacional permite o aprimoramento em diferentes campos de pesquisa, tal como a Química Teórica e Computacional capaz de aprimorar e prever novas propriedades em materiais com grandes aplicações tecnológicas, tais como catalisadores, células solares, memórias de computador, entre outros. Em particular, materiais que apresentam tais aplicações são as perovskitas, de fórmula geral AB 'IND. 3'. O objetivo desta tese é aplicar a Química Teórica e Computacional, a fim de proporcionar uma melhor compreensão das propriedades físicas, químicas e estruturais das perovskitas BaZr'O IND. 3' (BZ) e SrZr"O IND. 3' (SZ). As simulações computacionais foram desenvolvidas com o programa CRYSTALO3, aplicando-se a teoria do funcional de densidade (DFT) com os funcionais híbridos B3LYP e B3PW para investigar as propriedades eletrônicas e estruturais do bulk e das superfícies: (001) com as possíveis terminações Zr'O IND. 2' e AO (onde A = Ba ou Sr) e (110) com as possíveis terminações, ZrO, A e O. Também foram feitos cálculos para entender o conceito de ordem-desordem local, responsável por propriedades como a fotoluminescência (FL) à temperatura ambiente.
Abstract: The increasing technological advances in the computer to the improvement on different fields of research, such as Computacional and Theoretical Chemistry able to improve and provide new properties in materials with high technology applicatons such as catalysts, solar cells, computer memory, among others. In particular, materials that have such applications are the perovskitas of general formula AB 'IND. 3'. The objective of this thesis is to apply the Theoretical and Computational Chemistry, to provide a better understanding of the physical, chemical and structural properties of perovskites BaZr'O IND. 3' (BZ) e SrZr"O IND. 3' (SZ). Computational simulations were conducted with the program CRYSTAL0, applying the theory of density functional (DFT) with hybrid functional B3LYP and B3PW to investigate the structural and electronic properties of bulk and surfaces: (001) with the possible terminations Zr'O IND. 2' and AO (where A = Ba or Sr) and (110) with the possible terminations, ZrO, A and. Calculations were also made to understand the concept of local order-disorder, responsible for properties such as photoluminescence (PL) at room temperature.
Doutor
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Liacouras, Peter C. "Computational Modeling to Predict Mechanical Function of Joints: Validations and Applications of Lower Leg Simulations." VCU Scholars Compass, 2006. http://scholarscompass.vcu.edu/etd/1437.
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Computational models of musculoskeletal joints and limbs can provide useful information about joint mechanics. Validated models can be used as a predictive device for understanding joint function and serve as a clinical tool for predicting the outcome of surgical procedures. A new computational modeling approach was developed for simulating joint kinematics that are dictated by bone/joint anatomy, ligamentous constraints, and applied loading.Three-dimensional computational models of the lower leg were created. Model development involved generating three-dimensional surfaces from CT images, followed by importing these surfaces into SolidWorks and COSMOSMotion. ThroughSolidWorks and COSMOSMotion, each bone surface was created into a solid object and positioned, necessary components added, and simulations executed. Three dimensional contacts inhibited intersection of the bones during motion. Ligaments were represented as linear springs. Model predictions were then validated by comparison to three different previously performed cadaver studies (syndesmotic injury study, inversion stability study, and mechanical laxity study) and one simultaneously performed cadaver study (anterior drawer test).In the syndesmotic injury study, the relative motion between the tibia and fibula in intact, transected, and repaired states was measured under the application of an external rotation of the ankle. The inversion stability study focused on the elongation behavior of lateral ankle ligaments and inversion range of motion during the application of an applied load. The mechanical laxity study focused on differences in anterior/posterior and inversion/eversion movement in intact and transected states. Each computational simulation was placed under the same conditions as its respective cadaver study and revealed a capability to predict behaviors in each case. The syndesmotic injury model was able to predict tibia1 rotation, fibular rotation, and anterior/posterior displacement. In the inversion simulation, calcaneofibular ligament extension and angles of inversion compared well. The laxity study showed increases in anteroposter motion after the transactions of the ATFL and CFL; and diffenences in inversion after the transaction of the CFL. The Anterior Drawer simulation produced similar ligament elongations and loads when compared to cadaver studies.Overall, the computational models were able to predict joint kinematics of the lower leg with particular focus on the ankle complex. Additional parameters can be calculated through such models that are not easily obtained experimentally such as ligament forces, force transmission across joints, and three-dimensional movement of all bones.
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Biswas, Souvik. "Direct numerical simulation and two-fluid modeling of multi-phase bubbly flows." Link to electronic thesis, 2007. http://www.wpi.edu/Pubs/ETD/Available/etd-050307-224407/.
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Dissertation (Ph.D.) -- Worcester Polytechnic Institute.Keywords: Multiphase flow; Two-fluid modeling; Direct numerical simulation; Two fluid modeling. Includes bibliographical references (leaves 116-119).
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Damián, Ares Gonzalo. "Integrative computational modeling & in-vivo characterization of residual deformations in hemodynamics." Laboratório Nacional de Computação Científica, 2016. https://tede.lncc.br/handle/tede/230.
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Fundação Carlos Chagas Filho de Amparo à Pesquisa do Estado do Rio de Janeiro (FAPERJ)
This thesis is concerned with two major problems arising in the modeling of the cardiovascular system. The first topic consists in a comprehensive approach for the simulation of arterial blood flow and its effect on the stress state of the arterial wall, and the second topic is concerned with the in-vivo characterization of residual deformations in arterial wall tissues, based on data provided by medical images. Specifically, regarding the first topic, an original modeling framework is proposed for the treatment of hemodynamic problems with increased realism, featuring a combination of several modeling techniques in order to account for i) the fact that the initial (image-based) geometry corresponds to a configuration which is at equilibrium with an internal pressure acting over the lumen, and with tethering forces located at the artificial (axial) boundaries delimiting the arterial region of interest; ii) the fluid-structure interaction problem; iii) the complex constitutive behavior of the arterial wall; iv) the influence of surrounding tissues; v) the interaction of the vessel with the rest of the cardiovascular system; and iv) the influence of residual stresses. In order to tackle the issues described above, the preload mechanical problem is solved in a first stage, finding the zero-load material configuration which is employed to define suitable constitutive equations. This is performed by finding the solution for the mechanical equilibrium of the given image configuration considering the vessel at this state to be loaded by an internal baseline pressure and an axial traction (caused by tethering forces) at the artificial boundaries. It is worthwhile to mention that this axial traction is such that a previously defined pre-stretch level is considered on the equilibrium image configuration. Once the reference configuration is obtained, the complete 3D fluid-structure interaction simulation is carried out, coupled with a dimensionally reduced 1D model of the rest of the cardiovascular system. Strong coupling via fixed-point iterations is achieved for the fluid-structure interaction, while the dimensionally heterogeneous coupling is achieved through a Broyden method. Regarding the constitutive modeling, a fiber-reinforced hyperelastic constitutive law is considered. Furthermore, through the analysis of several numerical examples, the sensitivity with respect to the existence of the preload stresses is assessed to quantify the importance of this issue. These results indicate that the stress state of the arterial wall is strongly influenced by the existence of preload. Therefore, the consideration of such preload state is mandatory for the prediction of stresses in arterial tissue. For the second topic, a conceptual framework is presented for the in-vivo estimation of residual deformations and stresses. As a given data, a set of known configurations for an arterial segment is considered, which can potentially be obtained from medical imaging techniques. The mechanical equilibrium equations corresponding to such configurations are introduced through a variational approach, highlighting the role of the residual deformations and associated stresses. In this context, a cost functional is proposed to measure the imbalance of the mechanical setting arising from the consideration of inconsistent residual deformations, based on the generalized residuals of the associated variational equations. Then, the characterization of residual deformations becomes an optimization problem, focused on the minimization of this cost functional. For this purpose, a simple gradient descent method and an interior-point algorithm for constrained optimization are explored in this work. The proposed methodology is tested using three numerical examples based on manufactured solutions, a simple clamped bar, a thick-walled cylinder and a three-layered aorta artery. The obtained results are promising and suggest that the present method (or variants based on the present ideas), when coupled with adequate image acquisition techniques, could successfully lead to the in-vivo identification of residual deformations.
Esta tese aborda dois problemas de relevância na modelagem do sistema cardiovascular humano. O primeiro tema consiste no desenvolvimento de um enfoque abrangente para a simulação do escoamento sanguíneo e sua interação com a parede arterial, e o segundo tópico é a caracterização in-vivo de tensões e deformações residuais na parede arterial baseada em dados fornecidos por imagens médicas. De maneira específica, em relação ao primeiro tópico, um marco de modelagem é proposto para o tratamento de problemas hemodinâmicos com um alto grau de realismo, apresentando uma combinação de diferentes técnicas de modelagem para levar em conta i) o fato que as geometrias iniciais obtidas a partir de imagens médicas são correspondentes a um sistema de carregamentos não nulos, definido pela existência da pressão interna no lumen e de tensões axiais localizadas nos contornos artificiais do segmento arterial; ii) o problema de interação fluido-estrutura; iii) o complexo comportamento constitutivo da parede arterial; iv) a interação do segmento de interesse com o resto do sistema cardiovascular; e v) a influência dos tecidos circundantes; e vi) a existência de tensões residuais. Para a abordagem das questões descritas acima, o problema mecânico de precarregamento é resolvido em uma primeira etapa, encontrando a configuração material de carregamento nulo onde as equações constitutivas são usualmente definidas. Isto é realizado encontrando a solução do problema de equilíbrio mecânico da estrutura arterial dada, considerando que o vaso está submetido a um nível de pressão de base e uma tração axial nos contornos artificiais. Vale a pena ressaltar que esta tração axial é correspondente a um nível de pre-estiramento previamente definido. Uma vez que a configuração de referência é obtida, a simulação fluido-estrutura 3D é realizada, acoplada com um modelo dimensionalmente reduzido do resto do sistema cardiovascular. Um acoplamento forte através de iterações de ponto fixo é empregado para representar a interação fluido-estrutura, equanto o acoplamento entre modelos dimensionalmente heterogêneos é conseguido usando um método tipo Broyden. Em relação à modelagem constitutiva, um modelo hyperelástico reforçado com fibras é considerado. Além disso, através da análise de vários exemplos numéricos, a sensibilidade com relação à existência de precarregamentos é quantificada para remarcar a relevância desta questão. Tais resultados indicam que o estado de tensão da parede arterial é fortemente influenciado pela existência de precarregamentos. Assim sendo, levar em consideração esse estado de precarga é fundamental para a predição de tensões no tecido arterial. Em relação ao segundo tópico, um marco conceptual é apresentado para estimação de tensões e deformações residuais. Consideramos que os dados são um conjunto de configurações de um segmento arterial, as quais poderiam ser obtidas a partir do uso de técnicas de adquisição e , processamento e segmentação de imagens. Utilizando um enfoque variacional, são apresentadas as equações de equilíbrio mecânico para as configurações conhecidas, acentuando o papel desempenhado pelas deformações residuais. Neste contexto, apresenta-se um funcional custo que mede o desbalance mecânico que é originado se um campo de deformações residuais inconsistente é admitido. Este funcional custo está baseado no resíduo generalizado das equações variacionais previamente mencionadas. Como consequência, o problema de estimação de deformações residuais é transformado em um problema de otimização, no qual se procura minimizar o funcional custo proposto. Com este objetivo, neste trabalho de tese são considerados dois métodos, um método de gradiente e um algoritmo de ponto interior para problemas que apresentam restrições. A metodologia proposta é testada em três exemplos numéricos baseados em soluções manufaturadas: um barra engastada, um cilindro de parede grossa, e uma artéria aorta composta por três camadas. Os resultados obtidos são promissores e sugerem que o método apresentado (ou variantes baseadas nas ideias aqui mostradas) junto com técnicas adequadas para a adquisição de imagens podem conduzir à identificação in-vivo de deformações residuais.
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Saunders, Michael G. "Electrodynamical Modeling for Light Transport Simulation." Digital Commons @ East Tennessee State University, 2017. https://dc.etsu.edu/honors/373.
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Modernity in the computer graphics community is characterized by a burgeoning interest in physically based rendering techniques. That is to say that mathematical reasoning from first principles is widely preferred to ad hoc, approximate reasoning in blind pursuit of photorealism. Thereby, the purpose of our research is to investigate the efficacy of explicit electrodynamical modeling by means of the generalized Jones vector given by Azzam [1] and the generalized Jones matrix given by Ortega-Quijano & Arce-Diego [2] in the context of stochastic light transport simulation for computer graphics. To augment the status quo path tracing framework with such a modeling technique would permit a plethora of complex optical effects—including dispersion, birefringence, dichroism, and thin film interference, and the physical optical elements associated with these effects—to become naturally supported, fully integrated features in physically based rendering software.
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Kitchovitch, Stephan. "Computational modelling and analysis of seasonal influenza transmission and evolution." Thesis, University of Cambridge, 2012. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.610402.
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Dressler, Sven. "Simulation of Fibre Pull-out Using a Graphics Processing Unit Accelerated Discrete Element Model." Diss., University of Pretoria, 2020. http://hdl.handle.net/2263/75931.
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The combination of brittle material with ductile fibres can produce competent composites. The fibres transmit tensile forces across cracks that form in the brittle matrix at relatively low tensile strains. The fibre reinforcing, therefore, acts to both increase the maximum stress a structural section can support and improve the post maximum stress behaviour from brittle to ductile failure. An essential aspect of defining the effectiveness of fibre reinforcing is resolving the behaviour of the interface between the fibre and the matrix as the load being transmitted between the matrix and fibre increases.
The interface behaviour for simple fibres is understood analytically, and several models exist that can predict the stresses in the interface. Numerical models using finite element methods (FEM) have been used to investigate this problem in a more general way. FEM, being inherently a description of a continuum, does not elegantly describe the debonding process that occurs during the debonding of fibres from the surrounding matrix. Discrete Element Methods (DEM) describe continuous and discontinuous materials as the interaction between multiple independent particles and are well suited for modelling fracture and evolving contacts.
For this study two different DEM contact models are compared to investigate the model complexity that is required to describe fibre/matrix interface stresses and debonding accurately. A simple model (a linear spring model that only transmits normal and tangential forces) and a more complex model (parallel bonds which transmit normal and tangential forces, moments, and torsion) were used. Two stages of fibre pull-out were modelled independently using a GPU accelerated DEM simulator developed by the author: a fully bonded stage and the de-bonding stage. It was found that both models were able to simulate all stages when compared to analytical solutions. No improvement to the model behaviour was evident from using a complex contact model; for this reason, a simpler, faster contact model should be used to analyse this problem.
The DEM code is written relying heavily on the Numba module which allows the compilation of Python syntax for execution on a GPU. Non-reversible bond damage is simulated, and each bond must, therefore, be stored and bond damage updated at each time step. The implementation of collision detection, particle force determination and equation of motion integration written for execution on GPU are discussed. The data structure and memory use are described. The method used to apply boundary conditions is described. The performance of the developed code is investigated by comparison with similar codes, using Numpy and Numba Python modules, written for serial execution on CPU only. It was found that the developed code was 1000 times faster than the Numpy+Python implementation and 4 times faster than the Numba+Python implementation for force determination and equation of motion integration. Collision detection was 900 times faster compared to Numpy+Python but performed slower compared to Numba+Python.Dissertation (MEng)--University of Pretoria, 2020.
Mechanical and Aeronautical Engineering
MEng
Unrestricted
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Munoz, Diego Jose. "Modeling and Simulation of Circumstellar Disks with the Next Generation of Hydrodynamic Solvers." Thesis, Harvard University, 2013. http://dissertations.umi.com/gsas.harvard:11151.
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This thesis is a computational study of circumstellar gas disks, with a special focus on modeling techniques and on numerical methods not only as scientific tools but also as a target of study. In particular, in-depth discussions are included on the main numerical strategy used, namely the moving-mesh method for astrophysical hydrodynamics. In this work, the moving-mesh approach is used to simulate circumstellar disks for the first time.Astronomy
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Cameron, David Stuart. "Modelling affect regulation dynamics (MARDy) : a computational simulation of affect change." Thesis, University of Sheffield, 2013. http://etheses.whiterose.ac.uk/3255/.
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This thesis explores the process of controlled affect regulation - the deliberate control of feelings and expressions - in terms of its dynamics. The thesis takes the perspective that affect is a dynamic and controllable process, regulated towards held goals, which themselves are controllable and dynamic. It is argued that affect regulation dynamics are underexplored, as are the dynamics of the related concepts of self-regulatory capacity and affect goal adjustment. A model of affect regulation dynamics (MARDy) is presented, which integrates affect regulation, self-regulatory capacity, and affect goal adjustment, within a control theory framework. A computational simulation of the MARDy model is constructed and known trends in affect are simulated. The model further offers predictions of affect dynamics and understanding of underlying mechanisms involved. Two studies are conducted to collect data for model representation. In Study 1, affect diary data are collected from five university staff and students. Parameter values for the model are derived from determining best fitting correlations of model results with the diary data across dimensions of felt-affect, self-regulatory capacity, felt-affect goals and affect-expression goals. In Study 2, affect diary data are collected from six teaching staff at a local primary school. This study extends beyond the first, to also incorporate data for affect-expressions. The capacity for the model to represent this second data set is assessed, using the protocol from Study 1. In a third, simulated, study, the model is extended to represent a network of two individuals. Propositions regarding affect dynamics across the dyad are made and tested in simulation. Considerations are offered for dyad representation in the affect regulation literature. The proposed dynamics of affect regulation, arising from model development and the three studies described, are discussed in terms of current literature; theoretical and practical implications of model results and propositions are discussed.
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Zappone, Marco. "Computational Fluodynamics Modeling (CFD) of horizontal propane jet fires." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2021.
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With regard to pipeline transportation of hazardous material, the occurrence of a jet fire is one of the most common accidents in case of loss of containment. In light of this consideration, an appropriate estimation of the accident scenario is necessary to determine the magnitude of the risk and the required measures to avoid or mitigate the consequences. Computational Fluid Dynamics (CFD) represents a valid tool to be used in this framework, because of its capability to describe the evolution of the accident, considering the obstacles and the site-specific factors. In this work, the capability of FLACS CFD code to simulate a propane horizontal jet fire is analyzed and the code is validated against experimental data. The parameters used for the validation are the jet fire geometrical characteristics and the flame temperature. The assessment is performed comparing different numerical models available in FLACS code in order to define the most appropriate to describe horizontal jet-fires. Then, the accuracy of simulation results is assessed using statistical performance metric parameters. In conclusion, results show that the FLACS CFD code is able to describe the horizontal jet fire phenomena in good accordance with experimental data, even though with a slight overprediction. On this basis, an initial study of the model proposed to simulate horizontal jet fire impingement on a pipe is conducted, and the possibility to use Fire Dynamics Simulator (FDS) CFD code to simulate horizontal jet fire is explored.
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Caulfield, Thomas R. "Structural basis for the fidelity of translation modeling the accommodation pathway /." Diss., Atlanta, Ga. : Georgia Institute of Technology, 2008. http://hdl.handle.net/1853/22553.
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Thesis (Ph. D.)--Chemistry and Biochemistry, Georgia Institute of Technology, 2008.Committee Chair: Harvey, Stephen C; Committee Member: Hud, Nicholas V; Committee Member: Oyelere, Adegboyega; Committee Member: Wartell, Roger.
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Busaryev, Oleksiy. "On Computing and Tracking Geometrical and Topological Features." The Ohio State University, 2012. http://rave.ohiolink.edu/etdc/view?acc_num=osu1354679582.
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Lu, Jiaqing. "Numerical Modeling and Computation of Radio Frequency Devices." The Ohio State University, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=osu1543457620064355.
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