Dissertationen: „Simulation and Modelling“

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Kurdi, Omar. „Crowd modelling and simulation“. Thesis, University of Sheffield, 2017. http://etheses.whiterose.ac.uk/18669/.

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In this thesis we analysed the behaviour of crowd flows in large gatherings, taking a case study of the corridors where the Sa'yee ritual are performed. Of the current simulation models few of them addressed disabled persons in their model calculations and they did not include real-life data in order to analyse the crowd behaviour. None of the crowd modelling and simulation studies of the Hajj crowd, focused mainly on crowd behaviours during the Sa'yee ritual. We have proposed and developed a methodology to extract crowd characteristics from real-life videos with unknown camera angle and position. Agent tracking for different conditions of weather and various walking styles have been studied in the scope of our study. We further tested the feasibility of the use of drone to track agent behaviour in our methodology. We propose, design, and develop, a realistic and flexible state-based model of the Sa'yee ritual that can be mapped onto different agent-based systems, and then implement it in the modelling platforms Netlogo and FLAME. Further a comparison is made in terms of processing speed so that the model could be escalated to larger crowd. There are two enhancements carried out in the Sa'yee model and simulations, that makes this research novel and different than other contemporary researches. The first is the addition of different types of people (men, women and people with disabilities), and the second is the use of real video recordings from CCTV to analyse and model the walking behaviours of pilgrims. We carried out experiments that define the safety limit for the number of people in a group, and the results of defining a dedicated corridor for the disabled population. An empirical study shows that some aspects of the model such as agent density, behaviour, and speed match the real Sa'yee crowd. Therefore, the model can be used to study the general crowd behaviour in terms of agent density and speed of the agents with only slight modifications. The model is mapped from Netlogo to FLAME which validates that our model can be extrapolated to simulate larger crowd and huge number of agents. In addition, safety guidelines for better crowd management have been proposed to enhance crowd flow and reduce risks.

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Shapiro, Janet. „Simulation modelling of spatial problems“. Thesis, London Metropolitan University, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.294985.

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3

Abdollahi, Mehrzad. „Vehicle ride modelling and simulation“. Thesis, University of Birmingham, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.633064.

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The work in this thesis is aimed primarily at developing a vehicle ride simulation program based on a generalised vehicle model formulation to evaluate the effect of various system parameters on the ride quality of a vehicle, and secondly to develop an optimisation scheme for determining the optimum setting of suspension parameters as related to ride comfort. The simulation program can accommodate the non-linearity of the suspension components such as tyres, shock absorbers and suspension springs. Based on a twin tube shock absorber in production, a damper model was developed. This damper model was included in a vehicle model and was run in parallel with the simulation program. A variety of vehicle models were developed and simulated in the time domain with various road obstacles such as half-sine, half-circle and ramp, and the results are presented. In order to improve the accuracy of the simulated response in the time domain, an attempt has been made to find the wheel envelope as it passes an obstacle. Based on a real car in production, two different vehicle models were developed and simulated in the frequency domain and the simulated responses were compared with those obtained from experiments. A series of tests were carried out on a test vehicle on the ride simulator and the transient responses were compared with those obtained from the simulation program. Attempts were made to improve the accuracy of the simulated response by inclusion of bilinear damper models in the simulation process. Several studies has been made to investigate the effect of various vehicle system parameter on the overall ride performance.

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Gove, Darryl James. „Simulation modelling of infectious diseases“. Thesis, University of Southampton, 1997. https://eprints.soton.ac.uk/414488/.

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This thesis looks at the use mathematical modelling, in particular the use of simulation as a solution technique, when applied to the problem of the study of infectious diseases. The thesis examines two different routes of infection of the bacteria Chlamydia trachomatis - the sexually transmitted disease Chlamydia, and the ocular disease Trachoma. Several simulation models are developed within the thesis. The exploration of Chlamydia results in a prototype model which it is suggested could be extended in a future project. The work exploring Trachoma resulted in the development of a model useful in the evaluation of intervention strategies, as well as the statistical analysis of data which provides the necessary data for the modelling work. The analysis provides values for the duration of Trachoma infection, and for the incidence of the infection; figures which have previously not been available.

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Aronsson, Anders, und Martin Andersson. „Modelling and Simulation of Debt Portfolios“. Thesis, Uppsala University, Department of Mathematics, 2002. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-122073.

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6

Ezeanochie, Tochukwu Chinedu. „Modelling and Simulation of Filopodial Protrusion“. Thesis, Université d'Ottawa / University of Ottawa, 2015. http://hdl.handle.net/10393/32781.

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The effect of substrate surface topology on the interaction of living cells with inanimate substrates is a well-established phenomenon. When cells are placed on biomaterials, they outgrow protrusions called filopodia that sense surface features in their immediate surroundings and initiate the formation of stable cell adhesion complexes closer to the cell body. Adhesion proteins permit filopodia to constantly explore the surrounding microenvironment. A better understanding of the relationship of filopodia with surface features is highly relevant for exploiting custom-made surfaces to guide cell activity. In this work, mathematical modeling and simulation were used to describe different phenomena related to the interaction of a filopodium with its microenvironment, with the aim of reproducing experimentally observed phenomena associated to filopodia growth and interactions with substrates. The Kelvin Voigt model was used for the viscoelastic response of filopodia. Result predict filopodia protrusion under test conditions and helps improving our understanding on the effect of substrate topology on the biomechanical response of filopodial extensions.

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Tam, Jimmy Chi-Ming. „An expert system for simulation modelling“. Thesis, University of Ottawa (Canada), 1988. http://hdl.handle.net/10393/5097.

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8

Bose, Sonia Manjusri. „Computer simulation modelling of polymer ageing“. Thesis, University of Surrey, 2002. http://epubs.surrey.ac.uk/843495/.

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Detailed information of the underlying mechanisms of macromolecular disintegration processes is not always fully available from lab-based experiments and GPC. A powerful computer simulation technique was thus indispensable in this respect whilst saving time, labour and expense. This project aims to develop an interactive computer program to capture the behaviour of a complex reactor and offer the following functionality: mathematical calculations, graph/chart generation, processing simulation-experiment pertaining to user-given scission and environmental characteristics, data saving and re-loading etc, Windows-style menu-driven interfaces provide templates for easy implementation of complex mathematical algorithms -a new simulation technique (Slider interfaces) presented in the thesis, based on cellulose-ageing study in electrical transformers (Heywood, 2000). A novel statistical concept was introduced to significantly improve real-tune performance of mathematical calculations to simulate polymer chain fragmentation phenomena, enabling transformation of the simple iterative to a semi-iterative and instant calculation algorithm. Three new mathematical functions were constructed - (a) Monte Carlo Dynamic (Slider), (b) Algebraic Exact, (c) Markov Statistical models, initially using an arbitrary time scale for degradation. Real-time simulation was developed using three time model variants that included the interpretation of deviations in the order reaction rate from linearity to an exponential type function. The above transformation enhanced reproducibility and accuracy of degraded MWD curve sampling whilst then- graphical display & clarity via 'Cubic B-Spline' smoothing-algorithm. Complex models were created from a ranking ensemble of single scission mechanisms, structured with levels of probability constructs to effectively simulate GPC-like curve-deformities and side-shifts. The simulation results provided new information in the following key areas: the temporal shift patterns of MWD/PCLD under different ageing conditions graphical comparisons between simulated and observed Idnetic and scission parameters. the dominant types of scission strategy at different reactor conditions, the dependence of reaction behaviour on the polymer structural order. An alternative way of predicting life expectancy of an ageing polymer via relating time- temperature to the magnitude of intermediate MWD curve shifts that is independent on DP. The latter is an average value and subjected to errors. An equation was derived for this. Introduction of a binary tree "death time" algorithm for calculation of the life expectancy of different categories of polymer chain species. Non-iterative techniques developed here opens up new avenues of further research. The developed algorithms and computer program may provide ample scope for investigating the ageing of other industrially important polymers and can be utilised in other areas of polymer research with little modification where probability distribution is sought.

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Åkerström, Paul. „Modelling and simulation of hot stamping /“. Luleå : Luleå tekniska universitet/Tillämpad fysik, maskin- och materialteknik/Hållfasthetslära, 2006. http://epubl.ltu.se/1402-1544/2006/30/LTU-DT-0630-SE.pdf.

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10

Kalhori, Vahid. „Modelling and simulation of mechanical cutting“. Doctoral thesis, Luleå, 2001. http://epubl.luth.se/1402-1544/2001/28/index.html.

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11

Artuğ, Gamze. „Modelling and simulation of nanofiltration membranes“. Göttingen Cuvillier, 2007. http://d-nb.info/986774685/04.

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ANNA, RICARDO E. SILVA DE SANT. „ROTOR ACCIDENT ANALYSIS: MODELLING AND SIMULATION“. PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIRO, 2007. http://www.maxwell.vrac.puc-rio.br/Busca_etds.php?strSecao=resultado&nrSeq=11885@1.

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A Dissertação aqui apresentada descreve um acidente em um rotor de máquina de grande porte (compressor de ar) de uma fábrica de fertilizante cujas conseqüências foram perdas financeiras de alta monta tanto para a empresa quanto para o Estado, pela importância econômica onde a fábrica é situada. O objetivo da Dissertação foi simular matematicamente o acidente ocorrido e esclarecer o mesmo. Para se chegar ao diagnóstico do problema se modelou o rotor e o discretizou pelo Método de Elementos Finitos. As técnicas de investigação do problema e a sua seqüência de investigação podem ser tomadas como base em investigação de eventuais acidentes envolvendo rotores futuramente. O capítulo relativo a Análise Modal será extraído como base de apostila para curso envolvendo pessoal da área de Manutenção Mecânica.
A problem related with an air compressor gave birth to the MSc Thesis. Problems related with rotative machines are usual in the industrial field. Difficulties come from the data gathering in order to analyze, and propose a theory of failure in order to explain and avoid the recurrence of such problem. Modelling a rotor with a Timoshenko beam element and the discretization by finite element method permit the dynamical analysis and the modal analysis of the rotor considering its interaction with the radial and thrust bearings (assuming stiffness and rigidity). The work is divided in seven chapters: chapter one introduces the work and gives the overview of it; chapter two describes the industrial problem; chapter three is a brief explanation of bearing types and the fundamental principle of lubrication; chapter four introduces vibration theory and modal analysis; chapter five introduces the finite element method; chapter six is the simulation of the problem, using tailor-made MATLABr programs to reconstruct the problem and to compare the test field results with the here mentioned formulation; chapter seven discusses the results and proposes future works. Appendix shows the kinetic theory and the beam deformation model used in the program and the Laval simple rotor as a limited description of the dynamic of a rotor with distributed mass, rigidity and stiffness. The aim of this work is to help understand and avoid the recurrence of the failure described and to easy the understanding of modal analysis for new engineers and technicians which will deal with rotor dynamics.

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Barakat, Mamdouh Taysir. „Semantic modelling for discrete event simulation“. Thesis, London School of Economics and Political Science (University of London), 1992. http://etheses.lse.ac.uk/2823/.

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Discrete event simulation modelling has been established as an important tool for management planning. This process has been aided by the availability of off-the-shelf simulation systems for microcomputers. Traditionally these have had text-based interfaces and very limited graphics. As the availability of powerful colour microcomputers have increased, graphical front-ends have been added. As clients have got used to consistent graphical interfaces (e.g. Apple Macintosh or Microsoft Windows), they have desired the same level of integration in their simulation support environments. Research in other fields has been utilised in improving simulation environments. These fields include relational databases, expert systems, formal languages and graphical environments. This thesis examines the use of artificial intelligence in the discrete event simulation field with the aim of examining some potential areas in which it might be possible to improve simulation environments. Existing simulation research in the artificial intelligence (AI) field is extended by investigating the graphical AI knowledge-base called semantic networks. This thesis demonstrates semantic modelling, a discrete event simulation modelling approach based on semantic networks, which attempts to give a consistent graphical interface throughout the life cycle of a simulation study. The semantic modelling approach also incorporates expert system and natural language research. A prototype system of this approach is described.

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Poushpas, Saman. „Wind farm simulation modelling and control“. Thesis, University of Strathclyde, 2016. http://digitool.lib.strath.ac.uk:80/R/?func=dbin-jump-full&object_id=27911.

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The increasing trend towards large-scale deployment of wind energy imposes numerous operational challenges regarding large integration of wind power to the transmission system including the maintenance of system stability due to the uncertain nature of wind power. Thus, the traditional way of operating and controlling wind turbines and wind power plants are becoming less acceptable. Furthermore, wind power plants are progressively being subjected to the Transmission network operators (TSO's) regulations and are required to operate as a single controllable unit, similar to the conventional power plants, to provide active power regulation. To provide such a functionality, wind turbines in a wind farm must provide more flexible output power control in a quick and safe operating manner. Additionally, the operation of the wind turbines must be coordinated so as to operate the whole wind power plant as a single controllable entity. The main goal of this thesis is to generate a wind farm Simulink model that captures all the essential dynamics for the wind farm controller design and load analysis. To achieve this main aim, a mathematic wind farm model has been developed which offers sufficiently fast simulation for iterative controller design task, and contains a suitable wind-field model that provides a suitable representation of the wind-field and wake propagation through the wind farm. The wind farm controller design with the objectives of primary frequency response and power optimisation has also been investigated.

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Gärtner, Christian. „Organic laser diodes modelling and simulation“. Karlsruhe Univ.-Verl. Karlsruhe, 2008. http://d-nb.info/993660703/04.

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16

Hultberg, Ida. „Modelling and Simulation of Unknown Factors in Simulation Based Acquisition“. Thesis, University of Skövde, Department of Computer Science, 2002. http://urn.kb.se/resolve?urn=urn:nbn:se:his:diva-715.

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When a new product should be acquired, a model over its functionality is made. A quite new idea in the military area is to use simulations to find out what and how much to acquire. Since the product never has been on the market before it is hard to know how factors in the surroundings, like weather and other active objects, will affect it. Therefore these unknown factors that appear during the creation or acquiring of a new product need to be taken into consideration.

A literature study is performed about how modelling of simulations can be done, and how unknown factors can be considered when modelling a simulation. The study goes into if unknown factors are taken into consideration when modelling in the Process component in Simulation Based Acquisition (SBA). The result of this study shows that SBA facilitates in the process of finding and reducing unknown factors.

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Cherif, Redha. „Software Process Simulation Modelling : A Multi Agent-Based Simulation Approach“. Thesis, Blekinge Tekniska Högskola, Avdelningen för programvarusystem, 2008. http://urn.kb.se/resolve?urn=urn:nbn:se:bth-5787.

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In this research we present one of the first actual applications of Multi Agent-Based Simulation (MABS) to the field of software process simulation modelling (SPSM). Although a few previous applications were attempted, we explain in our literature review how these failed to take full advantage of the agency paradigm. Our research resulted in a model of the software development process that integrates performance, cognition and artefact quality, for which we built a common simulation framework to implement and run MABS and System Dynamics (SD) simulators upon the same integrated models. Although it is not possible to fully verify and validate implementations and models like ours, we used a number of verification and validation techniques to increase our confidence in these. Our work is also quite unique in that it compares MABS to SD in the context of SPSM. Here, we uncovered quite interesting properties of each simulation approach and how MABS, for example, is "risk averse" when compared to SD. In our discussion section we also present a number of lessons learned regarding the two simulation paradigms as well as various shortcomings in the models we adopted and our own.

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Tomlinson, S. P. „The hydraulic automatic simulation package (HASP) : Modelling and simulation aspects“. Thesis, University of Bath, 1987. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.375337.

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19

Bennett, Donald John. „Semiconductor process modelling“. Thesis, University of the West of Scotland, 1994. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.259677.

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20

Oezkan, Oezguer. „Operational modelling practical manufacturing systems“. Thesis, University of Southampton, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.323768.

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21

Ahmed, Rizwan. „A rapid simulation modelling process for novice software process simulation modellers“. Thesis, University of Hertfordshire, 2005. http://hdl.handle.net/2299/14298.

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In recent years, simulation modelling of software processes have has promoted as a tool to understand, study, control, and manage software development processes. Claims have been made that simulation models are useful and effective at gaining insight into software development processes. However, little has been said about the process of developing simulation models for software engineering problems. Simulation modelling is a young discipline in software engineering. Consequently, many number software process simulation modellers are thought to be novices. The simulation modelling process is believed to have had an effect on the quality of a simulation study. Although there is a body of knowledge available in the general simulation literature to guide and educate novices, the software process simulation modelling literature lacks information for novice software process simulation modellers to understand and adopt a simulation modelling process. This thesis aims to develop a simulation modelling process for novice software process simulation modellers. This thesis reports how the development and evaluation of a simulation modelling process for novice software process simulation modellers. The rapid simulation modelling process (RSMP) is based on an empirical study of the contexts and practices of expert simulation modellers in SPSM and Operational Research (OR). The RSMP is intended to be independent of a particular simulation technique (i. e. system dynamics or discrete event simulation) and guides novice software process simulation modellers through a set of steps that should be undertaken during a simulation study; the RSMP emphasises heavy client contact and provides guidelines for model documentation. The RSMP has been evaluated through controlled experiments with novice software process simulation modellers using system dynamics (SD) modelling. In the future, it will be further evaluated with software process simulation modellers using discrete event simulation. The RSMP has also been evaluated with a panel of expert software process simulation modellers. The main contribution of this study lies in providing novice software process simulation modellers with a simulation modelling process, which embodies real world simulation practice and is intended to be independent of a particular simulation technique.

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Hawkins, James David. „Computer simulation of trachoma“. Thesis, University of Southampton, 1989. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.255761.

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23

Albertyn, Martin. „Generic simulation modelling of stochastic continuous systems“. Thesis, Pretoria : [s.n.], 2004. http://upetd.up.ac.za/thesis/available/etd-05242005-112442.

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24

Ulriksson, Jenny. „Consistency management in collaborative modelling and simulation“. Licentiate thesis, KTH, Microelectronics and Information Technology, IMIT, 2005. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-571.

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The aim of this thesis is to exploit the technological capabilities of computer supported collaborative work (CSCW) in the field of collaborative Modelling and Simulation (M&S). The thesis focuses on addressing two main problems: (i) providing flexible means of consistency management in collaborative M&S, and (ii) the ability of providing platform and application independent services for collaborative M&S.

In this work, some CSCW technologies and how some of the concepts can be incorporated in a distributed collaborative M&S environment, have been studied. An environment for component based simulation development and visualization, which provides support for collaborative M&S, has been designed. Some consistency policies that can be used in conjunction with distributed simulation and the High Level Architecture (HLA) have been investigated. Furthermore, the efficient utilization of HLA and XML in combination, as the foundation of a CSCW infrastructure has been proved. Two consistency policies were implemented utilizing HLA, a strict and an optimistic, in the distributed collaborative environment. Their performance was compared to the performance of a totally relaxed policy, in various collaboration situations.

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Klang, Henrik, und Andreas Lindholm. „Modelling and simulation of a gas turbine“. Thesis, Linköping University, Department of Science and Technology, 2005. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-2893.

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In this thesis, a gas turbine simulator for the Siemens GT10C was developed and implemented.

It concerns everything from the theory behind the simulator; both the hard- ware and software involved, to how the actual simulator was built using these tools. The theory concerns itself with basic automatic control concepts, as well as basic turbine theory.

The simulator setup is being discussed concerning both technical and eco- nomic issues. A robust hardware solution is then selected, using the basic re- quirements, which the simulator then is built around.

The tools used are the Siemens SIMATIC automatic control system and the Siemens SIMIT real-time simulator using a SIMBA Pro PCI card to interface with the PLC:s in the SIMATIC system. Matlab are also used to a lesser extent to build the simulator behavior in SIMIT.

In the end, a fully featured simulator is presented that can be used for various purposes such as training operators, trying out new concepts and testing the automatic control system used to control the turbine.

Further development that could be done, by other engineers, in the future, is also discussed.

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Lindström, Stefan. „Modelling and simulation of paper structure development“. Doctoral thesis, Mittuniversitetet, Institutionen för naturvetenskap, teknik och matematik, 2008. http://urn.kb.se/resolve?urn=urn:nbn:se:miun:diva-7003.

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A numerical tool has been developed for particle-level simulations of fibre suspension flows, particularly forming of the fibre network structure of paper sheets in the paper machine. The model considers inert fibres of various equilibrium shapes, and finite stiffness, interacting with each other through normal, frictional, and lubrication forces, and with the surrounding fluid medium through hydrodynamic forces. Fibre–fluid interactions in the non-creeping flow regime are taken into account, and the two-way coupling between the solids and the fluid phases is included by enforcing momentum conservation between phases. The incompressible three-dimensional Navier–Stokes equations are employed tomodel themotion of the fluid medium. The validity of the model has been tested by comparing simulation results with experimental data from the literature. It was demonstrated that the model predicts well the motion of isolated fibres in shear flow over a wide range of fibre flexibilities. It was also shown that the model predicts details of the orientation distribution of multiple, straight, rigid fibres in a sheared suspension. Furthermore, model predictions of the shear viscosity and first normal stress difference were in fair agreement with experimental data found in the literature. Since the model is based solely on first principles physics, quantitative predictions could be made without any parameter fitting. Based on these validations, a series of simulations have been performed to investigate the basic mechanisms responsible for the development of the stress tensor components for monodispersed, non-Brownian fibres suspended in a Newtonian fluid in shear flow. The effects of fibre aspect ratio, concentration, and inter-particle friction, as well as the tendency of fibre agglomeration, were examined in the nonconcentrated regimes. For the case of well dispersed suspensions, semi-empirical relationships were found between the aforementioned fibre suspension properties, and the steady state apparent shear viscosity, and the first/second normal stress differences. Finally, simulations have been conducted for the development of paper structures in the forming section of the paper machine. The conditions used for the simulations were retrieved from pilot-scale forming trial data in the literature, and from real pulp fibre analyses. Dewatering was simulated by moving two forming fabrics toward each other through a fibre suspension. Effects of the jet-to-wire speed difference on the fibre orientation anisotropy, the mass density distribution, and three-dimensionality of the fibre network, were investigated. Simulation results showed that the model captures well the essential features of the forming effects on these paper structure parameters, and also posed newquestions on the conventional wisdom of the forming mechanics.

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Uzir, Mohamad Hekarl. „Dynamic modelling and simulation of biocatalytic reactions“. Thesis, University College London (University of London), 2005. http://discovery.ucl.ac.uk/1446784/.

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Enzyme catalysis is of key importance in the synthesis of new fine chemicals. The use of enzymes to undertake chemical conversion has become commonplace among pharmaceutical companies alongside conventional catalysis. This is mainly due to the working conditions of enzyme-catalysed reactions, the specificity as well as stereo- and regio- selectivity of enzymes as biocatalysts. Many novel techniques have been developed to carry out such catalysis ranging from a simple batch reactor to a complex fiuidised bed reactor. Evaluating these techniques requires experimental work and repeat experiments and through these, optimised conditions could be achieved for better yield and productivity. Experimental work is costly and the only cost-effective method is to introduce computer-based experiments via mathematical modelling. For this purpose, a complete kinetic study based on mechanisms of general enzyme-catalysed reactions was established and the Michaelis-Menten type kinetics has been used as the basis of the steady-state analysis. Prior to the steady-state kinetics, dynamic analyses of enzyme-catalysed reactions were also undertaken and this has led to the understanding of the quasi steady-state assumption that governed the model. New conditions were proposed for the validity of this assumption and the stability of enzyme-catalysed reactions. In this work, Baeyer-Villiger monooxygenase enzyme-catalysed synthesis of optically pure lactone was used as a model system. A complete model of the rate expression of Baeyer-Villiger reaction was devised. This provided the foundation of the fed-batch whole cell process model carried out as the main part of this work. The effect of substrate and product inhibitions was integrated into this model system and an outcome comparable to that of the experimental data was achieved. The whole cell process system has been found to be affected by membrane diffusivity during the course of reaction. This has led to the introduction of diffusion coefficients for both substrate and product into the process model. A simple enzyme-catalysed reaction-diffusion system was successfully modelled and numerically solved. Finally, stability analysis was carried out in order to prove and understand the particular biocatalytic process system.

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Eldabi, Tillal. „Simulation modelling : problem understanding in healthcare management“. Thesis, Brunel University, 2000. http://bura.brunel.ac.uk/handle/2438/5264.

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One of the main problems that face decision makers in healthcare systems is complexity and the lack of a well-defined problem. This causes a lack of understanding about the system. Another problem associated with healthcare systems is that usually there are several stakeholders involved in decision making. In such cases different stakeholders may have different views about the problem. In addition to the lack of understanding and intercommunication, there is the tendency in healthcare management to use quantitative methods for analysing the system. These methods are highly data dependant and usually based on historical data, which may not reflect the system's performance under the present circumstances, given the changing pace of healthcare services and structure. Also data may not be available in the first place. This research looks at how modelling techniques may help healthcare stakeholders to understand their system and increase their level of intercommunication (in the case of multiple stakeholders) with minimum dependency on data. Two main aspects are considered in this research: first appraising the existing modelling techniques with regard to problem understanding and intercommunication, and second, looking for an effective modelling approach for achieving such objectives. Discrete Event Simulation (DES) offers good facilities for modelling for understanding. However, DES could be used more effectively to enable viable understanding and means of communication. It is assumed that in order to enhance stakeholders' understanding and intercommunication, that it is better to involve them in the process of modelling from the beginning, using an iterative modelling process, and without being restricted to logical steps. To achieve this a case study strategy is followed in order to devise a modelling framework that helps in enhancing stakeholders' understanding and intercommunication. In this particular research Single Case approach is employed using two case studies. The first case study is used as an attempt to evaluate the hypotheses and tackle research questions which are raised based on an analysis of findings from the literature. The experimentation and analysis part are used to refine the initial hypotheses. These hypotheses are then examined using the second case study to establish a picture about how to achieve the research objectives. In both case studies simulation modelling is examined with regard to the research questions. The thesis concludes by identifying a modelling approach that has high versatility and flexibility to enhance stakeholders understanding and intercommunication. The approach is called MAPIU2, which stands for a Modelling Approach that is Iterative Participative for Understanding. From its name it can be deducted that the main factors of this approach are based on involving the stakeholders in the modelling process from the beginning in an iterative behaviour. One of the main lessons learned is that to achieve better results from the simulation modelling it is important that stakeholders should be involved with modelling process rather than just getting the final results, which helps implanting any decisions or recommendations arising from the model.

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Lohy, Das Jesmin Permala. „Modelling and Simulation to Improve Antimalarial Therapy“. Doctoral thesis, Uppsala universitet, Institutionen för farmaceutisk biovetenskap, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-330113.

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The introduction of artemisinin-based combination therapy (ACT) substantially reduced malaria-related mortality and morbidity during the past decade. Despite the widespread use of ACT, there is still a considerable knowledge gap with regards to safety, efficacy and pharmacokinetic properties of these drugs, particularly in vulnerable populations like children and pregnant women. In addition, there is growing evidence of widespread artemisinin-resistance across the Greater Mekong Subregion. Expedited delivery of novel antimalarial drugs with different mechanisms of action to the clinical setting is still far off; therefore, it is crucial to improve the use of existing antimalarial drugs for optimal outcome in order to prolong their therapeutic life span. This thesis focuses on utilizing pharmacometric tools to support this effort for malaria prevention and treatment. An extensive simulation framework was used to explore alternative malaria chemopreventive dosing regimens of a commonly used ACT, dihydroartemisinin-piperaquine. Different monthly and weekly dosing regimens were evaluated and this allowed an understanding of the interplay between adherence, loading dose and malaria incidence. A weekly dosing regimen substantially improved the prevention effect and was less impacted by poor adherence. This is also expected to reduce selection pressure for development of resistance to piperaquine. Population pharmacokinetics-pharmacodynamic models were developed for artesunate and the active metabolite dihydroartemisinin, effect on parasite clearance, in patients with artemisinin-resistant and -sensitive malaria infections in Southeast Asia. The modeling identified an association between parasite density and drug bioavailability. It predicted the presence of high levels of artemisinin resistant infection among patients in Cambodia and its spread into Myanmar. A nomogram to identify patients with artemisinin resistant infections was developed. Furthermore, the model was used to demonstrate the need for extended treatment duration to treat patients with artemisinin resistant infections. A population pharmacokinetic model developed from data on pregnant women in East Africa allowed further understanding of artemether-lumefantrine exposure in pregnant populations. It also suggested that the lumefantrine exposure in this population is not compromised. In summary, the results presented in this thesis demonstrate the value of pharmacometric approaches for improving antimalarial drug treatment and prevention. This ultimately contributes to overcoming the prevailing challenges to malaria control.

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Gue, Chang Shin. „Submarine landslide flows simulation through centrifuge modelling“. Thesis, University of Cambridge, 2012. https://www.repository.cam.ac.uk/handle/1810/243401.

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Landslides occur both onshore and offshore. However, little attention has been given to offshore landslides (submarine landslides). Submarine landslides have significant impacts and consequences on offshore and coastal facilities. The unique characteristics of submarine landslides include large mass movements and long travel distances at very gentle slopes. This thesis is concerned with developing centrifuge scaling laws for submarine landslide flows through the study of modelling submarine landslide flows in a mini-drum centrifuge. A series of tests are conducted at different gravity fields in order to understand the scaling laws involved in the simulation of submarine landslide flows. The model slope is instrumented with miniature sensors for measurements of pore pressures at different locations beneath the landslide flow. A series of digital cameras are used to capture the landslide flow in flight. Numerical studies are also carried out in order to compare the results obtained with the data from the centrifuge tests. The Depth Averaged Material Point Method (DAMPM) is used in the numerical simulations to deal with large deformation (such as the long runout of submarine landslide flows). Parametric studies are performed to investigate the validity of the developed centrifuge scaling laws under the initial and boundary conditions given in the centrifuge tests. Both the results from the centrifuge tests and numerical simulations appear to follow the proposed centrifuge scaling laws, which differ from the conventional centrifuge scaling laws. The results provide a better understanding of the centrifuge scaling laws that need to be adopted for centrifuge experiments involving submarine landslide flows, as well as giving an insight into the flow mechanism involved in submarine landslide flows.

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31

O'Donovan, Brendan Donal. „Modelling and simulation of engineering design processes“. Thesis, University of Cambridge, 2004. https://www.repository.cam.ac.uk/handle/1810/251938.

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32

Kolachina, Srinivasa Kranthi Kiran, und Nishu Reddy. „Modelling and Simulation of a Resonant Converter“. Thesis, Blekinge Tekniska Högskola, Institutionen för tillämpad signalbehandling, 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:bth-3374.

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This thesis is a part of collaborated project between Alstom and Blekinge Institute of Technology. In this thesis a fifth order non- linear Hamilton observer is applied on a series resonant converter. Two models for individual modes are given for a resonant power converter, one is suitable for simulation and other is suitable for simulation and analysis. The circuit is run in eight modes. A switched model of a fifth order DC/DC converter consisting of eight different switching modes has been derived and the performance of the circuit is studied under several conditions by simulation.
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33

Yaacob, Zulkefli. „Modelling and simulation of transient gas flow“. Thesis, University of Salford, 1996. http://usir.salford.ac.uk/26975/.

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One of the objectives of this research was to develop mathematical models for transient flow in a gas transmission system. Models were developed from the continuity and the momentum equations. Different approximations in the equations result in the formulation of two different sets of partial differential equations, and these are the hyperbolic and the parabolic models. The Partial Differential Equations were numerically solved by an implicit finite difference technique. A Four Point Scheme was use to approximate the pressures, flows and their partial derivatives. With this scheme a second order accuracy for both spatial and time variables was achieved for both hyperbolic and parabolic models. The nonlinear equation sets from the finite differences discretization process are solved by using a Newton-Raphson iterative procedure. This procedure resulted in the formation of a sparse Jacobian Matrix. This large matrix was then compacted algebraically to reduce the time of the numerical solution. Although an implicit finite difference approximation was used in simulating the models, the important of the correct choice of the magnitude of the temporal and spatial steps should not be overlooked, particularly for high frequency disturbances 'Aliasing' problems will occur if temporal or spatial steps which are too large relative to the frequency of disturbance are used. Comparisons between the response of the hyperbolic and the parabolic models with different input boundary conditions were performed. As a result, recommendations are made on how the different models should be used in simulating real pipeline systems.

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34

El-Mounayri, Hazim A. „Generic solid modelling based machining process simulation“. Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1997. http://www.collectionscanada.ca/obj/s4/f2/dsk2/ftp03/NQ30083.pdf.

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35

Pantea, Radu Catalin. „Wood cutting system, modelling and process simulation“. Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1999. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape8/PQDD_0020/MQ47226.pdf.

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36

Nilsson, Annika. „Modelling and simulation of metal working processes /“. Luleå, 2000. http://epubl.luth.se/1402-1544/2000/41/index.html.

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37

Chaleeraktrakoon, Chavalit. „Stochastic modelling and simulation of streamflow processes“. Thesis, McGill University, 1995. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=28704.

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The main objectives of this research are to propose a general stochastic method for determining analytically the distribution of flood volume, and to develop a simulation procedure for generating synthetic multiseason streamflows at different sites simultaneously. The research study is divided into two parts: (a) First, a general stochastic model is proposed to derive analytically the probability distribution function for flood volume. The volume of a flood is defined as the sum of an unbroken sequence of consecutive daily flows above a given truncation level. Analytical expressions were then derived for the exact distribution of flood volume for various cases in which successive flow exceedances can be assumed to be either independent or correlated, and the cumulative flow exceedance can be considered to be independent or dependent of the corresponding flood duration. The proposed stochastic method is more general and more flexible than empirical fitting approach because it can take explicitly into account different stochastic properties inherent in the underlying streamflow process. Results of a numerical application have shown that the proposed model could provide a very good fit between observed and theoretical results. Further, in the estimation of flood volume distribution, it has been found that the effect of the serial correlation property of the flow series is not significant as compared to the impact due to the dependence between flood volume and corresponding duration. Finally, it has been demonstrated that the simplistic assumption of triangular flood hydrograph shape, as usually appeared in previous studies, is not necessary in the estimation of flood volume distribution. (b) Second, a multivariate stochastic simulation approach is proposed for generating synthetic seasonal streamflow series at a single location or at many different locations concurrently. The suggested simulation scheme is based on the combination of the singular value decomposition

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Wu, Hongjin. „Modelling and simulation of electric mining shovels“. Thesis, McGill University, 1995. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=28964.

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The electric mining shovel is the main rock loading machine at the majority of surface mining operations. The performance and utilization of these multi-million dollar machines can govern an entire mining operation. Despite their significance, they remain largely unexplored in terms of their potential. The thesis discusses the development of the forward and inverse kinematic models, the Newton-Euler dynamics, and the actuator dynamics for an electric mining shovel. The thesis relates to work undertaken towards the development of a mining shovel simulator, the purpose of which is to explore productivity and machine performance issues as a function of the interaction of the shovel with the ground. Both the parametric and nonparametric system identification results are presented, based on field test data collected from an operating mining shovel. Simulator results describing analytical and empirical models, as well as continuous-time controller and disturbance rejection are also presented. The thesis concludes with a discussion of planned continuing work.

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Lehaney, Brian. „Simulation modelling in administration-by-consensus organisations“. Thesis, Brunel University, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.286696.

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Nikoukaran, Jalal. „Using software to select simulation modelling packages“. Thesis, Brunel University, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.266637.

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41

Arinaminpathy, Thayalini. „Modelling and simulation studies of glutamate receptors“. Thesis, University of Oxford, 2005. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.413984.

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42

Kaye, Samantha Louise. „Modelling and simulation studies of NMDA receptors“. Thesis, University of Oxford, 2007. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.442836.

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43

Capener, Charlotte E. „Modelling and simulation studies of potassium channels“. Thesis, University of Oxford, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.249241.

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44

Law, Richard J. „Modelling and simulation studies of membrane proteins“. Thesis, University of Oxford, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.249273.

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45

Christodoulou, Konstantinos. „Variable structure modelling in strategic business simulation“. Thesis, London Business School (University of London), 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.246309.

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46

Sampò, Enrico. „Modelling chassis flexibility in vehicle dynamics simulation“. Thesis, University of Surrey, 2011. http://epubs.surrey.ac.uk/782825/.

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This thesis deals with the development of advanced mathematical models for the assessment of the influence of chassis flexibility on vehicle handling qualities. A review of the literature relevant to the subject is presented and discussed in the first part of the thesis. A preliminary model that includes chassis flexibility is then developed and employed for a first assessment of the significance of chassis flexibility. In the second part of the thesis a symbolic multibody library for vehicle dynamics simulations is introduced. This library constitutes the basis for the development of an advanced 14-degrees-of-freedom vehicle model that includes chassis flexibility. The model is then demonstrated using a set of data relative to a real vehicle. Finally, simulation results are discussed and conclusions are presented. The advanced model fully exploits a novel multibody formulation which represent the kinematics and the dynamics of the system with a level of accuracy which is typical of numeric multibody models while retaining the benefits of purpose-developed hand- derived models. More specifically, a semi-recursive formulation, a velocity projection technique and a symbolic development are, for the first time, coupled with flexible body modelling. The effect of chassis flexibility on vehicle handling is observed through the analysis of open- and closed-loop manoeuvres. Results show that chassis flexibility induces variations of lateral load transfer distribution and suspension kinematics that sensibly affect the steady-state behaviour of the vehicle. Further effects on dynamic response and high-speed stability are demonstrated. Also, optimal control theory is employed to demonstrate the existence of a strict correlation between chassis flexibility and driver behaviour. The research yields new insights into the dynamics of vehicles with a flexible chassis and highlights critical aspects of chassis design. Although the focus is on sports and race cars, both the modelling approach and the results can be extended to other vehicles.

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Marurngsith, Worawan. „Simulation modelling of distributed-shared memory multiprocessors“. Thesis, University of Edinburgh, 2006. http://hdl.handle.net/1842/870.

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Distributed shared memory (DSM) systems have been recognised as a compelling platform for parallel computing due to the programming advantages and scalability. DSM systems allow applications to access data in a logically shared address space by abstracting away the distinction of physical memory location. As the location of data is transparent, the sources of overhead caused by accessing the distant memories are difficult to analyse. This memory locality problem has been identified as crucial to DSM performance. Many researchers have investigated the problem using simulation as a tool for conducting experiments resulting in the progressive evolution of DSM systems. Nevertheless, both the diversity of architectural configurations and the rapid advance of DSM implementations impose constraints on simulation model designs in two issues: the limitation of the simulation framework on model extensibility and the lack of verification applicability during a simulation run causing the delay in verification process. This thesis studies simulation modelling techniques for memory locality analysis of various DSM systems implemented on top of a cluster of symmetric multiprocessors. The thesis presents a simulation technique to promote model extensibility and proposes a technique for verification applicability, called a Specification-based Parameter Model Interaction (SPMI). The proposed techniques have been implemented in a new interpretation-driven simulation called DSiMCLUSTER on top of a discrete event simulation (DES) engine known as HASE. Experiments have been conducted to determine which factors are most influential on the degree of locality and to determine the possibility to maximise the stability of performance. DSiMCLUSTER has been validated against a SunFire 15K server and has achieved similarity of cache miss results, an average of +-6% with the worst case less than 15% of difference. These results confirm that the techniques used in developing the DSiMCLUSTER can contribute ways to achieve both (a) a highly extensible simulation framework to keep up with the ongoing innovation of the DSM architecture, and (b) the verification applicability resulting in an efficient framework for memory analysis experiments on DSM architecture.

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Ren, Lei. „Load carriage biomechanics: modelling, simulation and measurement“. Thesis, University of Salford, 2005. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.491796.

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The objective of this thesis is to develop and validate a computational methodology for load carriage biomechanics studies, which can lead to better understanding of the biomechanical interactions between pack and human body, and thus to improve load carriage system design.

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Gunal, Murat M. „Simulation Modelling for Understanding Performance in Healthcare“. Thesis, Lancaster University, 2008. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.499962.

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50

Jeong, Hae-Duck Joshua. „Modelling of self-similar teletraffic for simulation“. Thesis, University of Canterbury. Computer Science, 2002. http://hdl.handle.net/10092/5454.

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Recent studies of real teletraffic data in modern computer networks have shown that teletraffic exhibits self-similar (or fractal) properties over a wide range of time scales. The properties of self-similar teletraffic are very different from the traditional models of teletraffic based on Poisson, Markov-modulated Poisson, and related processes. The use of traditional models in networks characterised by self-similar processes can lead to incorrect conclusions about the performance of analysed networks. These include serious over-estimations of the performance of computer networks, insufficient allocation of communication and data processing resources, and difficulties ensuring the quality of service expected by network users. Thus, full understanding of the self-similar nature in teletraffic is an important issue. Due to the growing complexity of modern telecommunication networks, simulation has become the only feasible paradigm for their performance evaluation. In this thesis, we make some contributions to discrete-event simulation of networks with strongly-dependent, self-similar teletraffic. First, we have evaluated the most commonly used methods for estimating the self-similarity parameter H using appropriately long sequences of data. After assessing properties of available H estimators, we identified the most efficient estimators for practical studies of self-similarity. Next, the generation of arbitrarily long sequences of pseudo-random numbers possessing specific stochastic properties was considered. Various generators of pseudo-random self-similar sequences have been proposed. They differ in computational complexity and accuracy of the self-similar sequences they generate. In this thesis, we propose two new generators of self-similar teletraffic: (i) a generator based on Fractional Gaussian Noise and Daubechies Wavelets (FGN-DW), that is one of the fastest and the most accurate generators so far proposed; and (ii) a generator based on the Successive Random Addition (SRA) algorithm. Our comparative study of sequential and fixed-length self-similar pseudo-random teletraffic generators showed that the FFT, FGN-DW and SRP-FGN generators are the most efficient, both in the sense of accuracy and speed. To conduct simulation studies of telecommunication networks, self-similar processes often need to be transformed into suitable self-similar processes with arbitrary marginal distributions. Thus, the next problem addressed was how well the self-similarity and autocorrelation function of an original self-similar process are preserved when the self-similar sequences are converted into suitable self-similar processes with arbitrary marginal distributions. We also show how pseudo-random self-similar sequences can be applied to produce a model of teletraffic associated with the transmission of VBR JPEG /MPEG video. A combined gamma/Pareto model based on the application of the FGN-DW generator was used to synthesise VBR JPEG /MPEG video traffic. Finally, effects of self-similarity on the behaviour of queueing systems have been investigated. Using M/M/1/∞ as a reference queueing system with no long-range dependence, we have investigated how self-similarity and long-range dependence in arrival processes affect the length of sequential simulations being executed for obtaining steady-state results with the required level of statistical error. Our results show that the finite buffer overflow probability of a queueing system with self-similar input is much greater than the equivalent queueing system with Poisson or a short-range dependent input process, and that the overflow probability increases as the self-similarity parameter approaches one.

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Dissertationen zum Thema „Simulation and Modelling“

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