Les silices nanostructurées sont des matériaux ultra-poreux (plus de 80% de porosité) utilisés pour la confection de Panneaux Isolants sous Vides (PIV). Elles possèdent des propriétés thermiques exceptionnelles, mais de piètres propriétés mécaniques.L’enjeu de cette thèse est d’étudier ces matériaux aux échelles de la particule (quelques nm), de l’agrégat de particules (quelques dizaines de nm) et de l’agglomérat d’agrégats (quelques centaines de nm), afin de mieux comprendre les comportements mécanique et thermique à l’aide de simulations, et de proposer des pistes pour améliorer le compromis thermique / mécanique. La nature particulaire du matériau et son caractère multi-échelle justifient l’utilisation de méthodes de simulations discrètes (DEM : Discrete Element Method). Un modèle original permettant de générer des agrégats à morphologiecontrôlée (dimension fractale, rayon de giration, porosité) est proposé. Le comportement à la compaction des agrégats est ensuite étudié par simulations DEM. Une approche par cyclage à faible densité a été développée pour obtenir des arrangements initiaux réalistes d’agrégats. La prépondérance des phénomènes adhésifs dans le système rend en effet celui-ci très sensible à l’arrangement initial. La réponse en traction des structures générées par compaction est également évaluée.L’influence de la morphologie des agrégats, de l’adhésion et du frottement ont été étudiées. L’accent est mis sur la comparaison de deux types de silices (pyrogénées et précipitées) présentant des morphologies différentes et pour lesquelles des données expérimentales permettent une confrontation avec les simulations. Les simulations présentées permettent d’apporter des réponses sur l’origine des différences de comportement mécanique observées expérimentalement pour ces deux types de silice.Une modélisation de la conductivité thermique du matériau, avec une focalisation sur la conductivité solide, est également proposée. / Nanostructured silicas are ultra-porous materials (more than 80 % porosity) used to make Vacuum Insulation Panels (VIP).They have exceptional thermal properties, but poor mechanical properties. The goal of this thesis is to study these materials at the scale of the particle (a few nm), the aggregate of particles (a few tens of nm) and the agglomerate of aggregates (a few hundred nm), in order to better understand mechanical and thermal behaviour using simulations, and to propose ways to improve the thermal / mechanical compromise. The particulate nature of the material and its multi-scale naturejustify the use of Discrete Element Methods (DEM). An original model allowing to generate aggregates with controlledmorphology (fractal dimension, radius of gyration, porosity) is proposed. The compaction behaviour of the aggregates is then studied by DEM. A low-density cycling approach has been developed to obtain realistic initial aggregate arrangements.The preponderance of adhesive phenomena in the system makes it very sensitive to the initial arrangement. The tensile response of structures generated by compaction is also evaluated. The influence of aggregate morphology, adhesion and friction were studied. Emphasis is placed on the comparison of two types of silica (pyrogenic and precipitated) with different morphologies and for which experimental data allow a comparison with simulations. The simulations presented allow us to provide answers on the origin of the differences in mechanical behaviour observed experimentally for these two types of silica.A modeling of the thermal conductivity of the material, with a focus on solid conductivity, is also proposed.

The implementation of a fast track section is a commonly used strategy to improve patient flow in emergency departments (EDs). A fast track section reserves resources (beds, doctors and nurses) for lower acuity patients, and is thus aimed to reduce the wait time and length of stay of these patients. We use a discrete event simulation to investigate the impact of adding a fast track section to an emergency department. We quantify the effect of introducing a fast track on length of stay and waiting time to bed for low and high acuity patients in a crowded ED and compare it to an ED without fast track (Combined ED). We simulate a crowded ED by increasing the patient arrival rate, changing the acuity mix and increasing the time taken for admitted patients in the ED to obtain an inpatient bed (boarding time). We demonstrate that, when compared to a Combined ED with the same number of resources, the introduction of a fast track reduces the wait time to bed for lower acuity patients. However, this comes at the cost of increased waiting time for some higher acuity patients, which is unacceptable in practice. In investigating the solutions to this problem, we find that changing patient prioritization is the most effective way of reducing wait times under crowding. This change in priority does not require the addition of beds, doctors and nurses, and is therefore a cost-effective approach. Finally, we discuss the implications of our results for emergency departments.

This thesis is concerned with the development of algorithms for simulation optimization (SO), a special case of stochastic optimization where the objective function can only be evaluated through noisy observations from a simulation. Deterministic techniques, when directly applied to simulation optimization problems fail to converge due to their inability to handle randomness thus requiring sophisticated algorithms. However, many existing algorithms dedicated for simulation optimization often show poor performance on implementation as they require extensive parameter tuning. To overcome these shortfalls with existing SO algorithms, we develop ADALINE, a line search based algorithm that eliminates the need for any user defined parameters. ADALINE is designed to identify a local minimum on continuous and integer ordered feasible sets. ADALINE on a continuous feasible set mimics deterministic line search algorithms, while it iterates between a line search and an enumeration procedure on integer ordered feasible sets in its quest to identify a local minimum. ADALINE improves upon many of the existing SO algorithms by determining the sample size adaptively as a trade-off between the error due to estimation and the optimization error, that is, the algorithm expends simulation effort proportional to the quality of the incumbent solution. We also show that ADALINE converges ``almost surely'' to the set of local minima. Finally, our numerical results suggest that ADALINE converges to a local minimum faster, outperforming other advanced SO algorithms that utilize variable sampling strategies. To demonstrate the performance of our algorithm on a practical problem, we apply ADALINE in solving a surgery rescheduling problem. In the rescheduling problem, the objective is to minimize the cost of disruptions to an existing schedule shared between multiple surgical specialties while accommodating semi-urgent surgeries that require expedited intervention. The disruptions to the schedule are determined using a threshold based heuristic and ADALINE identifies the best threshold levels for various surgical specialties that minimizes the expected total cost of disruption. A comparison of the solutions obtained using a Sample Average Approximation (SAA) approach, and ADALINE is provided. We find that the adaptive sampling strategy in ADALINE identifies a better solution quickly than SAA. / Ph. D. / This thesis is concerned with the development of algorithms for simulation optimization (SO), where the objective function does not have an analytical form, and can only be estimated through noisy observations from a simulation. Deterministic techniques, when directly applied to simulation optimization problems fail to converge due to their inability to handle randomness thus requiring sophisticated algorithms. However, many existing algorithms dedicated for simulation optimization often show poor performance on implementation as they require extensive parameter tuning. To overcome these shortfalls with existing SO algorithms, we develop ADALINE, a line search based algorithm that minimizes the need for user defined parameter. ADALINE is designed to identify a local minimum on continuous and integer ordered feasible sets. ADALINE on continuous feasible sets mimics deterministic line search algorithms, while it iterates between a line search and an enumeration procedure on integer ordered feasible sets in its quest to identify a local minimum. ADALINE improves upon many of the existing SO algorithms by determining the sample size adaptively as a trade-off between the error due to estimation and the optimization error, that is, the algorithm expends simulation effort proportional to the quality of the incumbent solution. Finally, our numerical results suggest that ADALINE converges to a local minimum faster than the best available SO algorithm for the purpose. To demonstrate the performance of our algorithm on a practical problem, we apply ADALINE in solving a surgery rescheduling problem. In the rescheduling problem, the objective is to minimize the cost of disruptions to an existing schedule shared between multiple surgical specialties while accommodating semi-urgent surgeries that require expedited intervention. The disruptions to the schedule are determined using a threshold based heuristic and ADALINE identifies the best threshold levels for various surgical specialties that minimizes the expected total cost of disruption. A comparison of the solutions obtained using traditional optimization techniques, and ADALINE is provided. We find that the adaptive sampling strategy in ADALINE identifies a better solution more quickly than traditional optimization.

Providing care services across several departments and care givers creates the complexity of the patient pathways, as it deals with different departments, policies, professionals, regulations and many more. One example of complex patient pathways (CPP) is one that exists in integrated care, which most literature relates to health and social care integration. The world population and demand for care services have increased. Therefore, necessary actions need to be taken in order to improve the services given to patients in maintaining their quality of life. As the complexity arises due to different needs of stakeholders, it creates many problems especially when it involves complex patient pathways (CPP). To reduce the problems, many researchers tried using several decision tools such as Discrete Event Simulation (DES), System Dynamic (SD), Markov Model and Tree Diagram. This also includes Direct Experimentation, one of techniques in Lean Thinking/Techniques, in their efforts to help simplify the system complexity and provide decision support tools. However, the CPP models were developed using a single tools which makes the models have some limitations and not capable in covering the entire needs and features of the CPP system. For example, lack of individual analysis, feedback loop as well as lack of experimentation prior to the real implementation. As a result, ineffective and inefficient decision making was made. The researcher also argues that by combining the DES and SD techniques, named the hybrid simulation, the CPP model would be enhanced and in turn will help to provide decision support tools and consequently, will reduce the problems in CPP to the minimum level. As there is no standard framework, a framework of a hybrid simulation for modelling the CPP system is proposed in this research. The researcher is much concerned with the framework development rather than the CPP model itself, as there is no standard model that can represent any type of CPP since it is different in term of its regulations, policies, governance and many more. The framework is developed based on several literatures, selected among developed framework/models that have used combinations of DES and SD techniques simultaneously, applied in a large system or in healthcare sectors. This is due to the condition of the CPP system which is a large healthcare system. The proposed framework is divided into three phases, which are Conceptual, Modelling and Models Communication Phase, and each phase is decomposed into several steps. To validate the suitability of the proposed framework that provides guidance in developing CPP models using hybrid simulation, the inductive research methodology will be used with the help of case studies as a research strategy. Two approaches are used to test the suitability of the framework – practical and theoretical. The practical approach involves developing a CPP model (within health and social care settings) assisted by the SD and DES simulation software which was based on several case studies in health and social care systems that used single modelling techniques. The theoretical approach involves applying several case studies within different care settings without developing the model. Four case studies with different areas and care settings have been selected and applied towards the framework. Based on suitability tests, the framework will be modified accordingly. As this framework provides guidance on how to develop CPP models using hybrid simulation, it is argued that it will be a benchmark to researchers and academicians, as well as decision and policy makers to develop a CPP model using hybrid simulation.

Este trabalho cria um modelo, em simulação a eventos discretos, utilizando o software ARENA 5.0, do centro de distribuição de peças de uma empresa do ramo automotivo, para geração de informações relacionadas ao deslocamento dos funcionários nos corredores. Existem diversas variáveis que estão diretamente relacionadas à movimentação no processo de retirada de itens, tais como capacidade e velocidade do transportador manual, influência do peso dos itens na coleta, dentre outras, que dificultam o processo de tomada de decisão. As técnicas propostas na bibliografia apresentam dificuldades em fornecer soluções já que não são capazes de trabalhar simultaneamente com estas variáveis, apresentando, assim, resultados discrepantes com a realidade. A simulação permite lidar com tais variáveis e fornecer resultados que servirão de suporte aos decisores para a tomada de decisão e assim gerenciar melhor os funcionários para completar a coleta de itens dos pedidos sem atrasos / This work builds a model, by the discrete event simulation, using the software ARENA 5.0, of a parts distribution centre of an automotive company, to generate information related to employees routing in aisles. There are several variables related to the movement in the retrieving process, such as capacity and velocity of the manual trolley, influence of the mass of items in the collecting process, among others, which make the decision process difficult. The techniques found in the literature demonstrate certain difficulties in providing solutions because they are not capable of dealing with those variables simultaneously, presenting, consequently, discrepancy results to the reality. The simulation permits to deal with those variables simultaneously and proving results to support managers in decisions and, therefore, to improve employees management in order to finalize the collecting of items without delay

Este trabalho cria um modelo, em simulação a eventos discretos, utilizando o software ARENA 5.0, do centro de distribuição de peças de uma empresa do ramo automotivo, para geração de informações relacionadas ao deslocamento dos funcionários nos corredores. Existem diversas variáveis que estão diretamente relacionadas à movimentação no processo de retirada de itens, tais como capacidade e velocidade do transportador manual, influência do peso dos itens na coleta, dentre outras, que dificultam o processo de tomada de decisão. As técnicas propostas na bibliografia apresentam dificuldades em fornecer soluções já que não são capazes de trabalhar simultaneamente com estas variáveis, apresentando, assim, resultados discrepantes com a realidade. A simulação permite lidar com tais variáveis e fornecer resultados que servirão de suporte aos decisores para a tomada de decisão e assim gerenciar melhor os funcionários para completar a coleta de itens dos pedidos sem atrasos / This work builds a model, by the discrete event simulation, using the software ARENA 5.0, of a parts distribution centre of an automotive company, to generate information related to employees routing in aisles. There are several variables related to the movement in the retrieving process, such as capacity and velocity of the manual trolley, influence of the mass of items in the collecting process, among others, which make the decision process difficult. The techniques found in the literature demonstrate certain difficulties in providing solutions because they are not capable of dealing with those variables simultaneously, presenting, consequently, discrepancy results to the reality. The simulation permits to deal with those variables simultaneously and proving results to support managers in decisions and, therefore, to improve employees management in order to finalize the collecting of items without delay

Este trabalho apresenta o desenvolvimento de um modelo de simulação que em base a dois dos maiores recursos naturais da Colômbia, o carvão e os recursos hídricos, procura dimensionar um sistema intermodal de transporte que visa o aproveitamento de ditas riquezas e o fornecimento de carvão térmico para produção de energia nos principais países industrializados do mundo. Neste trabalho os principais dados levantados de fontes como a Agencia Internacional de Energia, o World Energy Council, o Ministério de Transporte e o Ministério de Minas e Energia da Colômbia, entre outras, permitiram entender melhor o contexto e detalhar o problema em consideração. Baseado na metodologia de simulação de eventos discretos a descrição do sistema modelado é feita através do detalhamento de seus subcomponentes, os parâmetros de entradas, as saídas esperadas e a esquematização do modelo conceitual para conduzir os testes computacionais no software computacional Arena, conforme um cenário padrão de experimentações definido para conseguir o escoamento do excedente da produção de mineiro procedente do departamento colombiano de Cesar. Finalmente, logo de ter achado a melhor configuração para o sistema, esta foi testada e analisada o desempenho da mesma quando mudanças como variações na demanda de carvão entre outras foram introduzidas. / This work introduces the development of a simulation model based on two of the largest natural resources of Colombia, the coal and water resources, looking for sizing an intermodal system of transportation aiming for the approach of such resources and the supplying of steam coal for energy productions in the world industrialized countries. Data collection taken from sources as International Energy Agency, World Energy Council, Colombian Transport and Energy Ministries, between others, allowed a better understanding and detailing of the context for the studied problem. Founded on discrete event simulation methodology, the system description is done thought the detailing of its subcomponents, the input parameters, outputs and conceptual model schematization for conducting experimental tests in the Arena computational software, considering a standard scenario in order to size the intermodal transportation system for Colombian thermic coal exportation based on the surplus production from Cesar department. Finally, after finding the best configuration for the system, its performance was tested and analyzed adopting changes such variations in demand for coal among others.

Este trabalho apresenta o desenvolvimento de um modelo de simulação que em base a dois dos maiores recursos naturais da Colômbia, o carvão e os recursos hídricos, procura dimensionar um sistema intermodal de transporte que visa o aproveitamento de ditas riquezas e o fornecimento de carvão térmico para produção de energia nos principais países industrializados do mundo. Neste trabalho os principais dados levantados de fontes como a Agencia Internacional de Energia, o World Energy Council, o Ministério de Transporte e o Ministério de Minas e Energia da Colômbia, entre outras, permitiram entender melhor o contexto e detalhar o problema em consideração. Baseado na metodologia de simulação de eventos discretos a descrição do sistema modelado é feita através do detalhamento de seus subcomponentes, os parâmetros de entradas, as saídas esperadas e a esquematização do modelo conceitual para conduzir os testes computacionais no software computacional Arena, conforme um cenário padrão de experimentações definido para conseguir o escoamento do excedente da produção de mineiro procedente do departamento colombiano de Cesar. Finalmente, logo de ter achado a melhor configuração para o sistema, esta foi testada e analisada o desempenho da mesma quando mudanças como variações na demanda de carvão entre outras foram introduzidas. / This work introduces the development of a simulation model based on two of the largest natural resources of Colombia, the coal and water resources, looking for sizing an intermodal system of transportation aiming for the approach of such resources and the supplying of steam coal for energy productions in the world industrialized countries. Data collection taken from sources as International Energy Agency, World Energy Council, Colombian Transport and Energy Ministries, between others, allowed a better understanding and detailing of the context for the studied problem. Founded on discrete event simulation methodology, the system description is done thought the detailing of its subcomponents, the input parameters, outputs and conceptual model schematization for conducting experimental tests in the Arena computational software, considering a standard scenario in order to size the intermodal transportation system for Colombian thermic coal exportation based on the surplus production from Cesar department. Finally, after finding the best configuration for the system, its performance was tested and analyzed adopting changes such variations in demand for coal among others.

Orientadores: Edson Luiz Ursini, Paulo Sérgio Martins Pedro / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Tecnologia / Made available in DSpace on 2018-08-24T15:16:37Z (GMT). No. of bitstreams: 1 Santos_VlademirFazio_M.pdf: 4330659 bytes, checksum: a576d09102c26740d57f44a9686c5b76 (MD5) Previous issue date: 2014 / Resumo: Iniciativas industriais para finalizar a produção de multi-commodities embaladas sem formar estoque requerem inovação tecnológica constante. Atuam sincronizadamente com o múltiplo carregamento simultâneo diretamente em caminhões. Para isso desenvolvemos um modelo de simulação por eventos discretos e apresentamos seu modelo analítico de tráfego validado com Redes de Filas de Jackson e pela Lei de Conservação de Little. Descrevemos os limites do intervalo de variação de tempos máximos e médios de permanência de multi-commodities em sistemas de tempo real para três servidores paralelos. Esse sistema opera com mudanças dinâmicas de diferentes políticas de escalonamento. Um resultado é a confirmação do compromisso entre tempos máximos e médios independentemente de intensidade de tráfego e de políticas de escalonamento a que o modelo seja submetido. Outro é a identificação de uma faixa de relativa estabilidade operacional fora de regiões críticas. Assim, contribuímos com os princípios de um método que pode ser adotado como apoio às decisões de planejamento em ambientes industriais complexos submetidos a filas em tempo real / Abstract: The industrial initiatives for the production finalization of packed multi-commodities without forming stock require constant technological innovation. They operate a synchronous process to simultaneous multi-loading straightly into trucks. Regarding to this we developed a discrete event simulation model and present its traffic analytical model validated with the theory of Jackson Queueing Networks and the Little's Conservation Law. We describe the limits for the range of multi-commodities throuput-times and maximum waiting time in real-time systems with three parallel servers. This system operates with dynamical changes of different scheduling policies. A reached result is the confirmation of the average and maximum times mutual commitment despite of traffic intensity and scheduling policies that the model is submitted to. Another is the identification of a range of relative operational stability out of critical regions. As a contribution we offer the principles of a method that can be used to planning decision support in complex industrial environments subject to real-time queues / Mestrado / Tecnologia e Inovação / Mestre em Tecnologia

The topic of this thesis is vertical transportation where multiple elevators are controlled by group traffic control. The elevators controlled by group traffic control are coordinated in order to work more efficiently than elevators that are only physically placed next to each other. The objective of this thesis is creation of a program, which allows modelling of operation of a lift triplex situated in Rajská building in Žižkov campus of the University of Economics in Prague. Applied method is discrete simulation performed in R software. Created script allows simulation of operation of elevators according to several described algorithms and subsequent comparison of their influence on the performance of the system. Using simulations the most suitable group traffic control is found and it is shown that shared memory used for cooperating units positively influence the service.