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1

Ibrahim, Rashidi. "Vibration assisted machining : modelling, simulation, optimization, control and applications". Thesis, Brunel University, 2010. http://bura.brunel.ac.uk/handle/2438/4732.

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Increasing demand for precision components made of hard and brittle materials such as glasses, steel alloys and advanced ceramics, is such that conventional grinding and polishing techniques can no longer meet the requirements of today's precision manufacturing engineering. Particularly, in order to undertake micro-milling of optical glasses or other hard-machining materials, vibration assisted machining techniques have been adopted. However, it is essential and much needed to undertake such processes based on a scientific approach, i.e. the process to be quantitatively controlled and optimized rather than carried out with a trial-and-error manner. In this research, theoretical modelling and instrumental implementation issues for vibration assisted micro-milling are presented and explored in depth. The modelling is focused on establishing the scientific relationship between the process variables such as vibration frequency, vibration amplitude, feedrate and spindle speed while taking into account machine dynamics effect and the outcomes such as surface roughness generated, tool wear and material removal rate in the process. The machine dynamics has been investigated including a static analysis, machine tool-loop stiffness, modal analysis, frequency response function, etc, carried out for both the machine structure and the piezo-actuator device. The instrumentation implementation mainly includes the design of the desktop vibration assisted machining system and its control system. The machining system consists of a piezo-driven XY stage, air bearing spindle, jig, workpiece holder, PI slideway, manual slideway and solid metal table to improve the system stability. The control system is developed using LabVIEW 7.1 programming. The control algorithms are developed based on theoretical models developed by the author. The process optimisation of vibration assisted micro-milling has been studied by using design and analysis of experiment (DOE) approach. Regression analysis, analysis of variance (ANOVA), Taguchi method and Response Surface Methodology (RSM) have been chosen to perform this study. The effects of cutting parameters are evaluated and the optimal cutting conditions are determined. The interaction of cutting parameters is established to illustrate the intrinsic relationship between cutting parameters and surface roughness, tool wear and material removal rate. The predicted results are confirmed by validation experimental cutting trials. This research project has led to the following contribution to knowledge: (1) Development of a prototype desktop vibration assisted micro-milling machine. (2) Development of theoretical models that can predict the surface finish, tool wear and material removal rate quantitatively. (3) Establishing in depth knowledge on the use of vibration assisted machining principles. (4) Optimisation of cutting process parameters and conditions through simulations and machining trials for through investigation of vibration assisted machining.
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Sun, Yan. "Modelling, simulation and optimization of near-ambient grain drying". Thesis, Imperial College London, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.243324.

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Siurana, Paula Maria. "Modelling and multiobjective optimization for simulation of cyanobacterial metabolism". Doctoral thesis, Universitat Politècnica de València, 2017. http://hdl.handle.net/10251/90578.

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The present thesis is devoted to the development of models and algorithms to improve metabolic simulations of cyanobacterial metabolism. Cyanobacteria are photosynthetic bacteria of great biotechnological interest to the development of sustainable bio-based manufacturing processes. For this purpose, it is fundamental to understand metabolic behaviour of these organisms, and constraint-based metabolic modelling techniques offer a platform for analysis and assessment of cell's metabolic functionality. Reliable simulations are needed to enhance the applicability of the results, and this is the main goal of this thesis. This dissertation has been structured in three parts. The first part is devoted to introduce needed fundamentals of the disciplines that are combined in this work: metabolic modelling, cyanobacterial metabolism and multi-objective optimisation. In the second part the reconstruction and update of metabolic models of two cyanobacterial strains is addressed. These models are then used to perform metabolic simulations with the application of the classic Flux Balance Analysis (FBA) methodology. The studies conducted in this part are useful to illustrate the uses and applications of metabolic simulations for the analysis of living organisms. And at the same time they serve to identify important limitations of classic simulation techniques based on mono-objective linear optimisation that motivate the search of new strategies. Finally, in the third part a novel approach is defined based on the application of multi-objective optimisation procedures to metabolic modelling. Main steps in the definition of multi-objective problem and the description of an optimisation algorithm that ensure the applicability of the obtained results, as well as the multi-criteria analysis of the solutions are covered. The resulting tool allows the definition of non-linear objective functions and constraints, as well as the analysis of multiple Pareto-optimal solutions. It avoids some of the main drawbacks of classic methodologies, leading to more flexible simulations and more realistic results. Overall this thesis contributes to the advance in the study of cyanobacterial metabolism by means of definition of models and strategies that improve plasticity and predictive capacities of metabolic simulations.
La presente tesis está dedicada al desarrollo de modelos y algoritmos para mejorar las simulaciones metabólicas de cianobacterias. Las cianobacterias son bacterias fotosintéticas de gran interés biotecnológico para el desarrollo de bioprocesos productivos sostenibles. Para este propósito, es fundamental entender el comportamiento metabólico de estos organismos, y el modelado metabólico basado en restricciones ofrece una plataforma para el análisis y la evaluación de las funcionalidades metabólicas de las células. Se necesitan simulaciones fidedignas para aumentar la aplicabilidad de los resultados, y este es el objetivo principal de esta tesis. Esta disertación se ha estructurado en tres partes. La primera parte está dedicada a introducir los fundamentos necesarios de las disciplinas que se combinan en este trabajo: el modelado metabólico, el metabolismo de cianobacterias, y la optimización multiobjetivo. En la segunda parte, se encara la reconstrucción y la actualización de los modelos metabólicos de dos cepas de cianobacterias. Estos modelos se usan después para llevar a cabo simulaciones metabólicas con la aplicación de la metodología clásica Flux Balance Analysis (FBA). Los estudios realizados en esta parte son útiles para ilustrar los usos y aplicaciones de las simulaciones metabólicas para el análisis de los organismos vivos. Y al mismo tiempo sirven para identificar importantes limitaciones de las técnicas clásicas de simulación basadas en optimización lineal mono-objetivo que motivan la búsqueda de nuevas estrategias. Finalmente, en la tercera parte, se define una nueva aproximación basada en la aplicación al modelado metabólico de procedimientos de optimización multiobjetivo. Se cubren los principales pasos en la definición de un problema multiobjetivo y la descripción de un algoritmo de optimización que aseguren la aplicabilidad de los resultados obtenidos, así como el análisis multi-criterio de las soluciones. La herramienta resultante permite la definición de funciones objetivo y restricciones no lineales, así como el análisis de múltiples soluciones en el sentido de Pareto. Esta herramienta evita algunos de los principales inconvenientes de las metodologías clásicas, lo que lleva a obtener simulaciones más flexibles y resultados más realistas. En conjunto, esta tesis contribuye al avance en el estudio del metabolismo de cianobacterias por medio de la definición de modelos y estrategias que mejoran la plasticidad y las capacidades predictivas de las simulaciones metabólicas.
La present tesi està dedicada al desenvolupament de models i algorismes per a millorar les simulacions metabòliques de cianobacteris. Els cianobacteris són bacteris fotosintètics de gran interés biotecnològic per al desenvolupament de bioprocessos productius sostenibles. Per a aquest propòsit, és fonamental entendre el comportament metabòlic d'aquests organismes, i el modelatge metabòlic basat en restriccions ofereix una plataforma per a l'anàlisi i l'avaluació de les funcionalitats metabòliques de les cèl·lules. Es necessiten simulacions fidedignes per a augmentar l'aplicabilitat dels resultats, i aquest és l'objectiu principal d'aquesta tesi. Aquesta dissertació s'ha estructurat en tres parts. La primera part està dedicada a introduir els fonaments necessaris de les disciplines que es combinen en aquest treball: el modelatge metabòlic, el metabolisme de cianobacteris i l'optimització multiobjectiu. En la segona part, s'adreça la reconstrucció i l'actualització dels models metabòlics de dos soques de cianobacteris. Aquests models s'empren després per a portar a terme simulacions metabòliques amb l'aplicació de la metodologia clàssica Flux Balance Analysis (FBA). Els estudis realitzats en aquesta part són útils per a il·lustrar els usos i aplicacions de les simulacions metabòliques per a l'anàlisi dels organismes vius. I al mateix temps serveixen per a identificar importants limitacions de les tècniques clàssiques de simulació basades en optimització lineal mono-objectiu que motiven la cerca de noves estratègies. Finalment, en la tercera part, es defineix una nova aproximació basada en l'aplicació al modelatge metabòlic de procediments d'optimització multiobjectiu. Es cobreixen els principals passos en la definició d'un problema multiobjectiu i la descripció d'un algorisme d'optimització que asseguren l'aplicabilitat dels resultats obtinguts, així com l'anàlisi multi-criteri de les solucions. La ferramenta resultant permet la definició de funcions objectiu i restriccions no lineals, així com l'anàlisi de múltiples solucions òptimes en el sentit de Pareto. Aquesta ferramenta evita alguns dels principals inconvenients de les metodologies clàssiques, el que porta a obtenir simulacions més flexibles i resultats més realistes. En conjunt, aquesta tesi contribueix a l'avanç en l'estudi del metabolisme de cianobacteris per mitjà de la definició de models i estratègies que milloren la plasticitat i les capacitats predictives de les simulacions metabòliques.
Siurana Paula, M. (2017). Modelling and multiobjective optimization for simulation of cyanobacterial metabolism [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/90578
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Ashaibani, A. S. "Modelling simulation and optimization of refinery processess with energy conservation". Thesis, University of Bradford, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.511389.

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Aris, Najmil Faiz Mohamed. "Surfaces functionality of precision machined components : modelling, simulation, optimization and control". Thesis, Brunel University, 2008. http://bura.brunel.ac.uk/handle/2438/5092.

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This research develops an analytical scientific approach for investigating the high precision surface generation and the quantitative analysis of the effects of direct factors in precision machining. The research focuses on 3D surface characterization with particular reference to the turning process and associated surface generation. The most important issue for this research is surface functionality which is becoming important in the current engineering industry. The surface functionality should match with the characterization parameters of the machined surface, which can be expressed in formula form as proposed in chapter 4. Modelling and simulation are extensively used in the research. The modelling approach integrates the cutting forces model, thermal mode% vibration model, tool wear model, machining system response model and surface topography model. All of those models are integrated as a whole model. The physical model with such as direct inputs is formed. The major inputs to the model are tooling geometry and the process variables. The outputs from the modelling approach are cutting force, surface texture parameters, dimensional errors, residual stress and material removal rate. MATLAB and Simulink are used as tools to implement the modelling and simulation. According to the simulation results, it is found that the feed rate has the most profound effect on in surface generation. The influence of the vibrations between the cutting tool and the workpiece on the surface roughness may be minimised by the small feed rate and large tool nose radius. Surface functionality simulation has been developed to model and simulate the surface generation in precision turning. The surface functionality simulation model covers the material and tool wear as well. It shows that chip formation is resulted from cutting forces. Cutting trials are conducted to validate the modelling and simulation developed. There are positive results that show the agreement between the simulation and experimental results. The analysis of the results of turning trials and simulations are conducted in order to find out the effects of process variables and tooling characteristics on surface texture and topography and machining instability. From the research, it can be concluded that the investigation on modelling and simulation of precision surfaces generation in precision turning is performed well against the research objectives as proposed. Recommendations for future work are to improve the model parameters identification, including comprehensive tool wear, chip formation and using Neural Networks modelling in the engineering surface construction system.
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Scaglioso, Giovanni. "Modelling, simulation and optimization of maintenance considerations on condition based maintenance". Master's thesis, Alma Mater Studiorum - Università di Bologna, 2015. http://amslaurea.unibo.it/8308/.

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Globalization has increased the pressure on organizations and companies to operate in the most efficient and economic way. This tendency promotes that companies concentrate more and more on their core businesses, outsource less profitable departments and services to reduce costs. By contrast to earlier times, companies are highly specialized and have a low real net output ratio. For being able to provide the consumers with the right products, those companies have to collaborate with other suppliers and form large supply chains. An effect of large supply chains is the deficiency of high stocks and stockholding costs. This fact has lead to the rapid spread of Just-in-Time logistic concepts aimed minimizing stock by simultaneous high availability of products. Those concurring goals, minimizing stock by simultaneous high product availability, claim for high availability of the production systems in the way that an incoming order can immediately processed. Besides of design aspects and the quality of the production system, maintenance has a strong impact on production system availability. In the last decades, there has been many attempts to create maintenance models for availability optimization. Most of them concentrated on the availability aspect only without incorporating further aspects as logistics and profitability of the overall system. However, production system operator’s main intention is to optimize the profitability of the production system and not the availability of the production system. Thus, classic models, limited to represent and optimize maintenance strategies under the light of availability, fail. A novel approach, incorporating all financial impacting processes of and around a production system, is needed. The proposed model is subdivided into three parts, maintenance module, production module and connection module. This subdivision provides easy maintainability and simple extendability. Within those modules, all aspect of production process are modeled. Main part of the work lies in the extended maintenance and failure module that offers a representation of different maintenance strategies but also incorporates the effect of over-maintaining and failed maintenance (maintenance induced failures). Order release and seizing of the production system are modeled in the production part. Due to computational power limitation, it was not possible to run the simulation and the optimization with the fully developed production model. Thus, the production model was reduced to a black-box without higher degree of details.
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Achermann, David. "Modelling, simulation and optimization of maintenance strategies under consideration of logistic processes /". Zürich : ETH, 2008. http://opac.nebis.ch/cgi-bin/showAbstract.pl?sys=000259627.

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Pang, Xi. "Trade-off analysis of forest ecosystem services – A modelling approach". Doctoral thesis, KTH, Hållbarhet, utvärdering och styrning, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-216432.

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Forest is a resource that is increasingly utilized for multiple purposes. The balance between energy demands and the long-term capacity of ecosystems to support biodiversity and other ecosystem services is crucial. The aim of this project was to increase the knowledge on and to develop methods and tools for trade-offs and synergies analysis among forest ecosystem services based on different forest management policies. Paper I provides an overview of existing models for integrated energy-environment assessment. A literature review was conducted on assessment models and their ability to integrate energy with environmental aspects. Missing environmental aspects concern land use, landscapes and biodiversity. In Paper II a modelling framework was set up to link a landscape simulator with a habitat network model for integrated assessment of bioenergy feedstock and biodiversity related impacts in Kronoberg County. In Paper III we continued with the same management scenarios, while the analysis was expanded to five ecosystem services by developing the Landscape simulation and Ecological Assessment (LEcA) tool: industrial wood, bioenergy, forest carbon stock, recreation areas and habitat networks. In Paper IV we present two heuristic methods for spatial optimization – simulated annealing (SA) and genetic algorithm (GA) – to find optimal solutions for allocating harvest activities, in order to minimize the impacts on habitat networks. In Paper V, as response to the findings in Paper I, we linked the energy model MESSAGE with our LEcA tool for forest bioenergy demand assessment while applying environmental and transport restrictions, in a study of Lithuania. We found trade-offs between industrial wood production and bioenergy on one side, and recreation values, biodiversity, and to some extent carbon storage on the other side. The LEcA tool integrated forest simulation and management with assessment of ecosystem services, which is promising for integrated sustainability assessment of forest management policies.

QC 20171023

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Dritsas, Ioannis. "Stochastic modelling and simulation-based optimization of specialty fibres for high power fibre lasers". Thesis, City University London, 2007. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.446447.

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Vasini, Ester Maria <1986&gt. "Numerical Modelling and Simulation Optimization of Geothermal Reservoirs Using the Tough2 Family of Codes". Doctoral thesis, Alma Mater Studiorum - Università di Bologna, 2016. http://amsdottorato.unibo.it/7412/1/Vasini_EsterMaria_tesi.pdf.

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In order to improve the reservoir engineering activities and, in particular, to optimize numerical modelling and simulation of geothermal reservoirs using the TOUGH family of codes, it has been decided to use the software T2Well for the interpretation of well-tests, coupling T2Well with the equation of state module EWASG, which describes the typical thermodynamic condition in high enthalpy geothermal reservoirs. T2Well-EWASG has been coupled and tested through the typical process of verification and validation. The application of T2Well-EWASG for the interpretation of well-tests related to the slim hole WW-01 drilled in the Wotten Waven Field (Commonwealth of Dominica) proves that it can be used as a tool for integrated interpretation of surface and downhole measurements collected during the performance of production tests in geothermal wells. The strength of this tool is that it allows to reduce the different possible solutions (in terms of reservoir characterization) within an acceptable error, by allowing the interpretation of surface and downhole measurements in conjunction, instead of separately. From this point of view T2Well-EWASG can effectively be used as a tool which allows an improvement of reservoir engineering activities. Finally, the huge amount of data managed during these activities has permitted to test and project the improvement of pre- and post- processing tools specific for TOUGH2 created by the geothermal research group of DICAM. In particular, the pre- and post-processing tools have been validated with a case study dealing with the migration of non-condensable gases in deep sedimentary formation.
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Vasini, Ester Maria <1986&gt. "Numerical Modelling and Simulation Optimization of Geothermal Reservoirs Using the Tough2 Family of Codes". Doctoral thesis, Alma Mater Studiorum - Università di Bologna, 2016. http://amsdottorato.unibo.it/7412/.

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In order to improve the reservoir engineering activities and, in particular, to optimize numerical modelling and simulation of geothermal reservoirs using the TOUGH family of codes, it has been decided to use the software T2Well for the interpretation of well-tests, coupling T2Well with the equation of state module EWASG, which describes the typical thermodynamic condition in high enthalpy geothermal reservoirs. T2Well-EWASG has been coupled and tested through the typical process of verification and validation. The application of T2Well-EWASG for the interpretation of well-tests related to the slim hole WW-01 drilled in the Wotten Waven Field (Commonwealth of Dominica) proves that it can be used as a tool for integrated interpretation of surface and downhole measurements collected during the performance of production tests in geothermal wells. The strength of this tool is that it allows to reduce the different possible solutions (in terms of reservoir characterization) within an acceptable error, by allowing the interpretation of surface and downhole measurements in conjunction, instead of separately. From this point of view T2Well-EWASG can effectively be used as a tool which allows an improvement of reservoir engineering activities. Finally, the huge amount of data managed during these activities has permitted to test and project the improvement of pre- and post- processing tools specific for TOUGH2 created by the geothermal research group of DICAM. In particular, the pre- and post-processing tools have been validated with a case study dealing with the migration of non-condensable gases in deep sedimentary formation.
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Prokop, Aleš. "Optimalizace procesů výrobní linky". Master's thesis, Vysoké učení technické v Brně. Fakulta podnikatelská, 2008. http://www.nusl.cz/ntk/nusl-221747.

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This thesis presents simulation method and simulation software Witness as a decision management instrument of a company, applied in STEKO spol. s r.o. The goal of this thesis is to create a model of real business process in the simulation program and following optimalization.
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Fang, Yiping. "Critical infrastructure protection by advanced modelling, simulation and optimization for cascading failure mitigation and resilience". Thesis, Châtenay-Malabry, Ecole centrale de Paris, 2015. http://www.theses.fr/2015ECAP0013/document.

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Sans cesse croissante complexité et l'interdépendance des infrastructures critiques modernes, avec des environs de risque plus en plus complexes, posent des défis uniques pour leur exploitation sûre, fiable et efficace. L'objectif de la présente thèse est sur la modélisation, la simulation et l'optimisation des infrastructures critiques (par exemple, les réseaux de transmission de puissance) à l'égard de leur vulnérabilité et la résilience aux défaillances en cascade. Cette étude aborde le problème en modélisant infrastructures critiques à un niveau fondamental, en se concentrant sur la topologie du réseau et des modèles de flux physiques dans les infrastructures critiques. Un cadre de modélisation hiérarchique est introduit pour la gestion de la complexité du système. Au sein de ces cadres de modélisation, les techniques d'optimisation avancées (par exemple, non-dominée de tri binaire évolution différentielle (NSBDE) algorithme) sont utilisés pour maximiser à la fois la robustesse et la résilience (capacité de récupération) des infrastructures critiques contre les défaillances en cascade. Plus précisément, le premier problème est pris à partir d'un point de vue de la conception du système holistique, c'est-à-dire certaines propriétés du système, tels que ses capacités de topologie et de liaison, sont redessiné de manière optimale afin d'améliorer la capacité de résister à des défaillances systémiques de système. Les deux modèles de défaillance en cascade topologiques et physiques sont appliquées et leurs résultats correspondants sont comparés. En ce qui concerne le deuxième problème, un nouveau cadre est proposé pour la sélection optimale des mesures appropriées de récupération afin de maximiser la capacité du réseau d’infrastructure critique de récupération à partir d'un événement perturbateur. Un algorithme d'optimisation de calcul pas cher heuristique est proposé pour la solution du problème, en intégrant des concepts fondamentaux de flux de réseau et le calendrier du projet. Exemples d'analyse sont effectués en se référant à plusieurs systèmes de CI réalistes
Continuously increasing complexity and interconnectedness of modern critical infrastructures, together with increasingly complex risk environments, pose unique challenges for their secure, reliable, and efficient operation. The focus of the present dissertation is on the modelling, simulation and optimization of critical infrastructures (CIs) (e.g., power transmission networks) with respect to their vulnerability and resilience to cascading failures. This study approaches the problem by firstly modelling CIs at a fundamental level, by focusing on network topology and physical flow patterns within the CIs. A hierarchical network modelling technique is introduced for the management of system complexity. Within these modelling frameworks, advanced optimization techniques (e.g., non-dominated sorting binary differential evolution (NSBDE) algorithm) are utilized to maximize both the robustness and resilience (recovery capacity) of CIs against cascading failures. Specifically, the first problem is taken from a holistic system design perspective, i.e. some system properties, such as its topology and link capacities, are redesigned in an optimal way in order to enhance system’s capacity of resisting to systemic failures. Both topological and physical cascading failure models are applied and their corresponding results are compared. With respect to the second problem, a novel framework is proposed for optimally selecting proper recovery actions in order to maximize the capacity of the CI network of recovery from a disruptive event. A heuristic, computationally cheap optimization algorithm is proposed for the solution of the problem, by integrating foundemental concepts from network flows and project scheduling. Examples of analysis are carried out by referring to several realistic CI systems
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Persson, Marie. "Modelling and Analysing Hospital Surgery Operations Management". Licentiate thesis, Karlskrona : Department of Systems and Software Engineering, Blekinge Institute of Technology, 2007. http://www.bth.se/fou/Forskinfo.nsf/allfirst2/020017aaa5cc3a0fc125734d0034ad77?OpenDocument.

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Diaz, Leiva Juan Esteban. "Simulation-based optimization for production planning : integrating meta-heuristics, simulation and exact techniques to address the uncertainty and complexity of manufacturing systems". Thesis, University of Manchester, 2016. https://www.research.manchester.ac.uk/portal/en/theses/simulationbased-optimization-for-production-planning-integrating-metaheuristics-simulation-and-exact-techniques-to-address-the-uncertainty-and-complexity-of-manufacturing-systems(9ef8cb33-99ba-4eb7-aa06-67c9271a50d0).html.

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This doctoral thesis investigates the application of simulation-based optimization (SBO) as an alternative to conventional optimization techniques when the inherent uncertainty and complex features of real manufacturing systems need to be considered. Inspired by a real-world production planning setting, we provide a general formulation of the situation as an extended knapsack problem. We proceed by proposing a solution approach based on single and multi-objective SBO models, which use simulation to capture the uncertainty and complexity of the manufacturing system and employ meta-heuristic optimizers to search for near-optimal solutions. Moreover, we consider the design of matheuristic approaches that combine the advantages of population-based meta-heuristics with mathematical programming techniques. More specifically, we consider the integration of mathematical programming techniques during the initialization stage of the single and multi-objective approaches as well as during the actual search process. Using data collected from a manufacturing company, we provide evidence for the advantages of our approaches over conventional methods (integer linear programming and chance-constrained programming) and highlight the synergies resulting from the combination of simulation, meta-heuristics and mathematical programming methods. In the context of the same real-world problem, we also analyse different single and multi-objective SBO models for robust optimization. We demonstrate that the choice of robustness measure and the sample size used during fitness evaluation are crucial considerations in designing an effective multi-objective model.
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Liang, Wen. "Integrated feature, neighbourhood, and model optimization for personalised modelling and knowledge discovery". Click here to access this resource online, 2009. http://hdl.handle.net/10292/749.

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“Machine learning is the process of discovering and interpreting meaningful information, such as new correlations, patterns and trends by sifting through large amounts of data stored in repositories, using pattern recognition technologies as well as statistical and mathematical techniques” (Larose, 2005). From my understanding, machine learning is a process of using different analysis techniques to observe previously unknown, potentially meaningful information, and discover strong patterns and relationships from a large dataset. Professor Kasabov (2007b) classified computational models into three categories (e.g. global, local, and personalised) which have been widespread and used in the areas of data analysis and decision support in general, and in the areas of medicine and bioinformatics in particular. Most recently, the concept of personalised modelling has been widely applied to various disciplines such as personalised medicine, personalised drug design for known diseases (e.g. cancer, diabetes, brain disease, etc.) as well as for other modelling problems in ecology, business, finance, crime prevention, and so on. The philosophy behind the personalised modelling approach is that every person is different from others, thus he/she will benefit from having a personalised model and treatment. However, personalised modelling is not without issues, such as defining the correct number of neighbours or defining an appropriate number of features. As a result, the principal goal of this research is to study and address these issues and to create a novel framework and system for personalised modelling. The framework would allow users to select and optimise the most important features and nearest neighbours for a new input sample in relation to a certain problem based on a weighted variable distance measure in order to obtain more precise prognostic accuracy and personalised knowledge, when compared with global modelling and local modelling approaches.
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Gokan, Khan Michel. "Performance Modelling and Simulation of Service Chains for Telecom Clouds". Licentiate thesis, Karlstads universitet, Institutionen för matematik och datavetenskap (from 2013), 2021. http://urn.kb.se/resolve?urn=urn:nbn:se:kau:diva-83687.

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New services and ever increasing traffic volumes require the next generation of mobile networks, e.g. 5G, to be much more flexible and scalable. The primary enabler for its flexibility is transforming network functions from proprietary hardware to software using modern virtualization technologies, paving the way of virtual network functions (VNF). Such VNFs can then be flexibly deployed on cloud data centers while traffic is routed along a chain of VNFs through software-defined networks. However, such flexibility comes with a new challenge of allocating efficient computational resources to each VNF and optimally placing them on a cluster. In this thesis, we argue that, to achieve an autonomous and efficient performance optimization method, a solid understanding of the underlying system, service chains, and upcoming traffic is required. We, therefore, conducted a series of focused studies to address the scalability and performance issues in three stages. We first introduce an automated profiling and benchmarking framework, named NFV-Inspector to measure and collect system KPIs as well as extract various insights from the system. Then, we propose systematic methods and algorithms for performance modelling and resource recommendation of cloud native network functions and evaluate them on a real 5G testbed. Finally, we design and implement a bottom-up performance simulator named PerfSim to approximate the performance of service chains based on the nodes’ performance models and user-defined scenarios.
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18

Sudiro, Maria. "Alternative processes for the production of biofuels and synthetic fuels: development, simulation and optimization". Doctoral thesis, Università degli studi di Padova, 2008. http://hdl.handle.net/11577/3425637.

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The research project of this PhD thesis was the development of alternative processes for the production of biofuels and synthetic fuels. The work consisted mainly modelling, process simulation and optimization, with an additional experimental part about the production of bioethanol by glucose fermentation. Regarding this part, a pilot reactor has been built in order to measure the kinetics of fermentation under CO2 pressure and interesting results, at different conditions, have been obtained. About bioethanol also a simulation work has been done: a first generation process production of bioethanol has been optimized. Then the interest was focused on the development and modelling of alternative processes for the production of synthetic fuels from coal (Coal to Liquid or CTL). Innovative and alternative solutions have been developed especially for the gasification section. Two configurations for gasification were proposed and verified in order to carried out the gasification with air instead of oxygen, without diluting the syngas produced with nitrogen. For each process considered the analysis began with the thermodynamic study and, after that, kinetics and mass transfer have been considered. Performances of the different processes developed have been evaluated, regarding to energy efficiency and environmental impact (CO2 emissions), obtaining significant improvements compared with existing technologies. Finally, a simplified economic and financial analysis was attempted.
Il progetto di ricerca di questa tesi di dottorato ha riguardato lo sviluppo di processi alternativi per la produzione di biocarburanti e carburanti di sintesi. Il lavoro svolto è stato prevalentemente di modellazione, simulazione e ottimizzazione di processo, a cui si è aggiunta una parte sperimentale sulla produzione di bioetanolo. Per quanto riguarda quest’ultima, si è costruita un’apparecchiatura per misurare le cinetiche di fermentazione alcolica sotto pressione di CO2, e si sono ottenuti risultati interessanti a diverse condizioni di lavoro. Anche una parte del lavoro di simulazione ha riguardato il bioetanolo, di cui è stato ottimizzato un processo di produzione di prima generazione. Poi l’interesse si è focalizzato sullo sviluppo e sulla modellazione di processi alternativi per la produzione di combustibili sintetici da carbone (Coal to Liquid o CTL). Si sono messe a punto soluzioni innovative ai processi esistenti soprattutto per la sezione di gassificazione. Sono state proposte e verificate mediante simulazione due idee per realizzare la gassificazione del carbone con aria, senza diluire il gas di sintesi prodotto. Per ogni processo considerato l’analisi è iniziata con lo studio termodinamico per poi includere anche gli aspetti cinetici e di trasporto di materia. Si sono valutate le prestazioni dei processi proposti, con riferimento all’efficienza energetica e all’impatto ambientale (emissioni di CO2), ottenendo risultati decisamente migliorativi rispetto alle tecnologie esistenti. Si è abbozzata infine un’analisi economico-finanziaria.
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19

Talbot, Edith. "Manufacturing process modelling of thermoplastic composite resistance welding". Thesis, McGill University, 2005. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=83934.

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One-, two- and three-dimensional transient heat transfer finite element models are developed to simulate the resistance welding process of pre-consolidated unidirectional AS4 carbon fibre reinforced Poly-ether-ether-ketone (APC-2/AS4) laminates with a metal mesh heating element, in a lap-shear configuration. The finite element models are used to investigate the effect of process and material parameters on the thermal behaviour of the coupon size welds, yielding to a better understanding of the process. The 1-D model determines: (a) the importance of including the latent heat of PEEK, and (b) the through-thickness temperature gradient away from the edges, for different tooling plate materials. The 2-D model simulates the cross-section of the process, considering the convective and irradiative heat losses from the areas of the heating element exposed to air. The 3-D model includes the heat conduction along the length of the laminates, to fully depict the thermal behaviour of the welds. Finally, the models are compared with experimental data.
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20

Grossi, Matteo. "Dynamic design, optimization and simulation of a control strategy for a pharmaceutical bioprocess". Master's thesis, Alma Mater Studiorum - Università di Bologna, 2019. http://amslaurea.unibo.it/17906/.

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In recent years, pharmaceutical companies have grown interest in developing new technologies for the continuous manufacturing of drug products. The continuous manufacturing of pharmaceuticals is critical in order to increase productivity and to reduce the amount of overall waste in a time-efficient manner. To strive towards this goal, in this work, the realistic case study of the continuous production of lovastatin is investigated and modeled. Therefore, based on the steady-state model proposed by Colombo et al. (2018) [1], a control plant-wide control strategy is developed and simulated for a semi-continuous benchmark simulation model for the production of lovastatin. Hence, the upstream and downstream processes have been integrated with feedback control systems using rigorous non-linear dynamic process models, in order to reach an accurate control of the process variables, and thus consistently maintain the predefined product quality. The proposed strategy ultimately leads to the identification and the development of a comprehensive benchmark model of an end-to-end plant-wide controlled system that, as it captures the generic dynamics of a bio-pharmaceutical process, can be deemed as a starting point for further simulations and implementations of other chemical process units. The results showed that under considerable and durable disturbances, the designed control strategy is capable to take action and adjust the process variables to their set points values, thus attesting for the effectiveness of the proposed model.
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21

Weiß, Ursula [Verfasser], i Malte A. [Akademischer Betreuer] Peter. "Modelling and simulation of electromagnetic source mechanisms and sensor optimization via homogenization / Ursula Weiß ; Betreuer: Malte A. Peter". Augsburg : Universität Augsburg, 2021. http://d-nb.info/1228787948/34.

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22

CAMPIONE, Antonino. "Electrodialysis modelling for low energy desalination". Doctoral thesis, Università degli Studi di Palermo, 2020. http://hdl.handle.net/10447/395212.

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23

Rybicki, Martin Rafael [Verfasser], i Ingenuin [Akademischer Betreuer] Gasser. "Mathematical Modelling, Simulation and Optimization of Gas Dynamics in a Car’s Exhaust Pipe / Martin Rafael Rybicki. Betreuer: Ingenuin Gasser". Hamburg : Staats- und Universitätsbibliothek Hamburg, 2014. http://d-nb.info/1055069879/34.

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Rybicki, Martin [Verfasser], i Ingenuin [Akademischer Betreuer] Gasser. "Mathematical Modelling, Simulation and Optimization of Gas Dynamics in a Car’s Exhaust Pipe / Martin Rafael Rybicki. Betreuer: Ingenuin Gasser". Hamburg : Staats- und Universitätsbibliothek Hamburg, 2014. http://d-nb.info/1055069879/34.

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25

Abebe, Birhanu Tamene [Verfasser], i Christoph [Gutachter] Pflaum. "Modelling, Simulation and Optimization of Thin Film Silicon Solar Cells on Flexible Aluminium Substrate / Birhanu Tamene Abebe ; Gutachter: Christoph Pflaum". Erlangen : Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), 2017. http://d-nb.info/1138837563/34.

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26

CIRILLO, GIOVANNI AMEDEO. "Engineering quantum computing technologies: from compact modelling to applications". Doctoral thesis, Politecnico di Torino, 2022. http://hdl.handle.net/11583/2971119.

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27

Ayele, Getnet Tadesse. "Exploiting the synergies from coupled electricity and heat distribution networks : modelling, simulation and optimization based on an extended energy hub approach". Thesis, Ecole nationale supérieure Mines-Télécom Atlantique Bretagne Pays de la Loire, 2020. http://www.theses.fr/2020IMTA0215.

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La littérature récente montre qu'il existe un potentiel important de décarbonation et d'amélioration de l'efficacité des réseaux d’énergie, qui peut être exploité grâce à la synergie offerte par les systèmes multi-énergies (MES). Les technologies de couplages, telles que les centrales de cogénération, les pompes à chaleur et les stockages thermiques, sont largement recommandées pour une flexibilité accrue et un meilleur taux de pénétration des énergies renouvelables dans les secteurs du chauffage et de l'électricité. Sur la base de ce constat, la taille et le nombre de technologies de couplage dans les réseaux de distribution de chaleur, telles que les centrales de production combinée de chaleur et d'électricité (cogénération) et les pompes à chaleur (PAC), augmentent. Ces technologies étant exclusivement gérées par les gestionnaires de réseaux de chauffage urbain, leur fonctionnement devient parfois sous-optimal du point de vue du réseau électrique et elles peuvent entraîner une surcharge des réseaux de distribution d'électricité basse tension (en particulier pour les grandes puissances installées). Des modèles de simulation et d'optimisation intégrés sont nécessaires pour exploiter efficacement les synergies sans compromettre les réseaux de distribution composants les MES. Ces modèles ne sont pas encore développés. Les outils classiques de simulation mono-vecteur d’énergie ne sont pas capables d’intégrer les paramètres de fonctionnement couplé clés des réseaux de distribution multi vecteurs. Une nouvelle méthodologie de simulation et d'optimisation de MES est développée dans cette thèse, basée sur une approche d'Extended Energy Hub (EEH). Une structure générale de modélisation est d'abord proposée sous forme modulaire, afin de pouvoir être facilement adaptée à tout type de réseaux énergétiques multi vecteurs. Celle-ci est ensuite utilisée pour développer les détails d'un modèle intégré de flux de charges régissant les réseaux couplés de chauffage et de distribution d'électricité. Plusieurs études de cas, traitant de topologies de réseaux radiales et maillées, sont considérées pour la démonstration et la validation numérique du modèle proposé. Ce modèle de flux de charges est en outre combiné avec un algorithme d'optimisation (PSO) afin de mener des études de flux de puissances intégrées optimaux. Le potentiel offert par cette démarche est illustré par l'étude du placement optimal des technologies de couplage, comme les pompes à chaleur (PAC), dans les réseaux couplés de chauffage et de distribution d'électricité. La capacité de l'outil développé est de plus illustrée par l'exploitation des synergies des réseaux couplés en présence d'énergies renouvelables intermittentes et d'un signal de prix de l'électricité variable. Il est démontré que les méthodologies de simulation et d'optimisation basées sur l'EEH, proposées dans cette thèse sont très efficaces, flexibles et facilement évolutives pour intégrer les paramètres de fonctionnement clés des réseaux intégrés d'électricité et de chauffage urbain. Les modèles développés peuvent ainsi être utilisés comme plate-forme d’études de l'intégration des réseaux intelligents et des réseaux thermiques intelligents
Recent literature shows that there is a significant potential of decarbonisation and efficiency improvement that can be achieved through the synergy from multi-energy systems (MESs). Coupling technologies, such as co-generation plants, heat pumps and thermal storages are widely recommended as means of unlocking additional flexibility and increasing the penetration of renewables in the heating and electricity sectors. In view of that, the size and number of coupling technologies, such as combined heat and power plants and heat pumps (HPs), being installed in the heat distribution networks are increasing. As these technologies are exclusively managed by the district heating network operators, their operation sometimes becomes suboptimal from the electricity network point of view, and they (in particular large HPs) may cause overloading of the low voltage electricity distribution networks. Integrated simulation and optimisation models are required to exploit the synergies effectively without compromising the constituent distribution networks of MES. Such models are not yet well developed. The conventional single-energy-carrier simulation tools are not capable of capturing key operating parameters of the multi-carrier distribution networks either. A novel methodology for simulation and optimisation of MES is developed in this thesis based on an Extended Energy Hub (EEH) approach. The general framework is first developed in modular form so that it can be easily adapted for any type of multi-carrier energy networks. The framework is then used to develop the details of an integrated load flow model governing coupled heating and electricity distribution networks. Various load flow case studies with radial and meshed topologies are considered for demonstration and numerical validation of the proposed model. The load flow model is further combined with a particle swarm optimisation algorithm in order to conduct integrated optimal power flow studies. Its contribution to the state of art is demonstrated by studying the optimal placement of coupling technologies, such as HPs and boilers in coupled heating and electricity distribution networks. The capacity of the model is further illustrated by exploiting the synergies using HPs together with thermal storage in the presence of intermittent renewables and variable electricity price signal. It is shown that the EEH-based simulation and optimisation methodologies proposed in this thesis are very effective, flexible and easily scalable in capturing the key operating parameters of integrated electricity and district heating networks. The models can be used as a platform for further studies on integration of smart grids and smart thermal networks
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28

Erlendsson, Örn. "Daylight Optimization - A Parametric Study of Atrium Design : Early Stage Design Guidelines of Atria for Optimization of Daylight Autonomy". Thesis, KTH, Installations- och energisystem, 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-146292.

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This thesis investigates the design of atria for daylighting in large scale buildings. Athree dimensional test building with a central atrium was constructed and various parameters of the atrium altered. The impact of these changes was studied through computer simulations of annual daylight distribution by implementing state of theart software. Daylight autonomy is simulated for an annual climate file for Stockholm, Sweden. In the thesis, notion is made of basic daylighting concepts, the importance of bringing daylight into buildings is argued, and the daylighting criteria of three environmental certification tools introduced. Furthermore, a detailed comparison is made on several well known daylight simulation tools. A newly developed, state of the art, daylight simulation tool called Honeybee, is used in the simulation process. The tool utilizes the calculation engines of wellknown daylight simulation software Radiance and Daysim, which apply backward ray-tracing to reach accurate results. Honeybee is coupled to the graphical algorithmeditor Grasshopper for Rhinoceros 3D, which allows for an efficient way of parametric modelling. The comparison of five different daylight simulation tools showed that Honeybee outweighs the capabilities of many of them by offering a wast range of simulation capabilities and also giving the user exceptional control of result data within multiple zones of the test building. The results of the daylight study have been compiled into a document which purpose is to serve as early stage design guidelines of atria for architects. Many factors have been shown through simulation to have a dramatic impact on daylighton an annual basis, and several suggestions have been made on how to maximize the quantity of daylight within buildings containing atria.
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29

Nordström, Erik. "Advanced Modelling and Energy Efficiency Prediction for Road Vehicles". Thesis, Umeå universitet, Institutionen för fysik, 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-175358.

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This thesis presents a first real world case-study of road transport operations that use the COVER format, in which the driver and the vehicle are regarded as separate entities. This format enables a complex representation of the transport operation that potentially better describe reality compared to the conventional representation used in today’s certification tools. The representation of operations treated in this thesis is called Operating Cycles and has been used to fully describe three representative transport missions from a case-study truck. Stochastically generated operating cycles have been used to create a large data set and thus prevent overfitting of specific cycles. The Operating Cycle-representation allowed for fair comparison between vehicle designs and ultimately manifested a vehicle composition that reduced the fuel consumption by nearly 10% for the same kind of transport operations.
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30

Velasco, Carrau Jesús. "Unmanned Aerial Vehicles Modelling and Control Design. A Multi-Objective Optimization Approach". Doctoral thesis, Universitat Politècnica de València, 2020. http://hdl.handle.net/10251/156034.

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[ES] Aquesta tesi presenta els resultats de la feina de recerca dut a terme sobre el modelatge i el disseny de controladors per a micro-aeronaus no tripulades mitjançant tècniques d'optimització multi-objectiu. Dos principals camps d'estudi estan presents al llarg d'ella. D'una banda, l'estudi de com modelar i controlar plataformes aèries de petita envergadura. I, de l'altra, l'estudi sobre l'ús de tècniques heurístiques d'optimització multi-objectiu per aplicar en el procés de parametrització de models i controladors en micro-aeronaus no tripulades. S'obtenen com a resultat principal una sèrie d'eines que permeten prescindir d'experiments en túnels de vent o de sensòrica d'alt cost, passant directament a la utilització de dades de vol experimental a la identificació paramètrica de models dinàmics. A més, es demostra com la utilització d'eines d'optimització multi-objectiu en diferents fases de desenvolupament de controladors ajuda a augmentar el coneixement sobre la plataforma a controlar i augmenta la fiabilitat i robustesa dels controladors desenvolupats, disminuint el risc de passar de les fases prèvies de el disseny a la validació en vol real.
[CA] Esta tesis presenta los resultados del trabajo de investigación llevado a cabo sobre el modelado y el diseño de controladores para micro-aeronaves no tripuladas mediante técnicas de optimización multi-objetivo. Dos principales campos de estudio están presentes a lo largo de ella. Por un lado, el estudio de cómo modelar y controlar plataformas aéreas de pequeña envergadura. Y, por otro, el estudio sobre el empleo de técnicas heurísticas de optimización multi-objetivo para aplicar en el proceso de parametrización de modelos y controladores en micro-aeronaves no tripuladas. Se obtienen como resultado principal una serie de herramientas que permiten prescindir de experimentos en túneles de viento o de sensórica de alto coste, pasando directamente a la utilización de datos de vuelo experimental en la identificación paramétrica de modelos dinámicos. Además, se demuestra como la utilización de herramientas de optimización multi-objetivo en diferentes fases del desarrollo de controladores ayuda a aumentar el conocimiento sobre la plataforma a controlar y aumenta la fiabilidad y robustez de los controladores desarrollados, disminuyendo el riesgo de pasar de las fases previas del diseño a la validación en vuelo real.
[EN] This thesis presents the results of the research work carried out on the modelling and design of controllers for micro-unmanned aerial vehicles by means of multi-objective optimization techniques. Two main fields of study are present throughout it. On one hand, the study of how to model and control small aerial platforms. And, on the other, the study on the use of heuristic multi-objective optimization techniques to apply in the process of models and controllers parameterization in micro-unmanned aerial vehicles. The main result is a series of tools that make it possible manage without wind tunnel experiments or high-cost air-data sensors, going directly to the use of experimental flight data in the parametric identification of dynamic models. In addition, a demonstration is given on how the use of multi-objective optimization tools in different phases of controller development helps to increase knowledge about the platform to be controlled and increases the reliability and robustness of the controllers developed, reducing the risk of hoping from the initial design phases to validation in real flight.
Velasco Carrau, J. (2020). Unmanned Aerial Vehicles Modelling and Control Design. A Multi-Objective Optimization Approach [Tesis doctoral]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/156034
TESIS
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31

Wikedzi, Alphonce Wendelin. "Optimization and performance of grinding circuits: the case of Buzwagi Gold Mine (BGM)". Doctoral thesis, Technische Universitaet Bergakademie Freiberg Universitaetsbibliothek "Georgius Agricola", 2018. http://nbn-resolving.de/urn:nbn:de:bsz:105-qucosa-235098.

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Buzwagi Gold Mine (BGM) is operated by Acacia Mining and located in the Lake Victoria Goldfields of central Tanzania. The mine commenced its operation since April 2009 and treats a sulphide copper-gold ore to produce gold in form of doré bars and a concentrate containing gold, copper and silver. The BGM comminution circuit includes a primary crushing stage with a gyratory crusher and a two grinding circuits using a Semi-Autogenous Grinding (SAG) mill and a ball mill. The SAG mill circuit also includes a single-deck screen and a cone crusher while the ball mill circuit utilizes hydrocyclones. Currently, the grinding circuits are inefficient in achieving the aspired product fineness of xP,80 = 125 μm even at low to normal throughputs (450-600 t/h). An evaluation and optimization study of the circuit performance was conducted to improve the product fineness through circuit surveys, experimental lab work and simulations. In three full scale sampling campaigns, size distributions and solids contents of the samples were determined at selected points in the circuit. Further, several types of breakage tests were conducted; standard Bond tests to determine ore grindability and work indices, batch grinding tests to determine parameters for breakage and selection functions , and standard ball mill tests for mineral liberation characterization by an automated mineral liberation analyzer (MLA).The tests were conducted in a size range from 0.063 to 2 mm. Then, mass balance of the circuit was calculated and the models for mills, screens and hydrocyclones were employed in MODSIM (version 3.6.24). Firstly, simulations were conducted to optimize the existing plant. Several options were evaluated such as reduction of SAG screen aperture, adjustment of cyclone feed solids content and reduction of vortex finder and apex diameters. Moreover, simulations were also evaluated for a possible modification of the existing circuit and include; partial splitting of the cyclone underflow back to SAG mill, introduction of a second classification stage as well as introduction of a second ball mill. The evaluation of breakage tests and survey data revealed the following; the Bond work index obtained for the current ore ranges between 17.20 - 18.70 kWh/t compared to 14.50 - 16.50 kWh/t which was estimated during plant design.This indicates a change in hardness of the ore during the last 7 years. Harder ore means more energy requirement for an efficient operation, the consequence of which is increased costs. Thus, a periodic review of the ore hardness for ongoing mining operation is recommended. This will help in establishing better blends as well as prediction of appropriate tonnages for the existing ore types, so as to be efficiently treated by the available plant design. The work indices of the ore blends treated during survey were correlated with their quartz content and showed a strong linear relationship (R2= 0.95). Therefore, the work index for the BGM ore could be predicted based on known quartz content of the material. Further, the model could be used as a control tool for monitoring hardness variation of the SAG mill feed. The mineral liberation studies indicated that the valuable phase (pyrite-pyrrhotite) could be liberated at relatively coarser particle sizes (200-400 µm). This implies that, there could be no problem with the efficiency of the gravity circuit for the BGM operation, where the gold contained in pyrite-pyrrhotite could be easily concentrated. However, the efficiency of flotation and cyanidation processes will still require finer feed. In overall, the liberation characteristics of the ore blends treated during survey showed minor differences. The Bond efficiency factors of 48-61 % were obtained for the BGM grinding circuit, indicating an inefficient operation. This suggests that the operation could achieve targets by lowering the throughput. Further, the SAG mill circuit was characterized by fluctuating feed size of between xF,80 =102 to 185 mm. A need for control of the feed size as well as blending ratios was recommended for an efficient operation in terms of throughput and final product size. This could be achieved through closer monitoring of the primary crusher performance and proper control of the ratios for the SAG mill feeders drawing the ore from the stockpile. The ball mill grinding efficiency was poor and could be indicated by the fraction < 125 µm of only 5-9 % or xP, 80 : >400 µm in the mill discharge. This was deemed due to poor hydrocyclone performance which was characterized by higher feed solids content, coarser overflow xP,80: >200 µm as well as cut sizes, xT : > 200 µm. An improvement of product fineness up to 327 µm could be achieved during the simulation and optimization of the existing design. This could be achieved by modification of the operating conditions such as reduction of SAG screen aperture from 12 mm to 10 mm, reduction of vortex finder from 280 mm to 270.3 mm, reduction of apex diameter from 150 mm to 145.6 mm as well as adjustment of the cyclone feed solids content from 66.7 to 67.1 %. Based on this result, it was concluded that the current equipment could not achieve the target product quality (i.e. xP,80 = 125 µm ). Further simulations based on flowsheet modification options showed that a second ball mill (series configuration) can help to achieve the desired product fineness as well as an increase of throughput from 618 t/h to 780 t/h. Although the circulating load increases to approximately 500 % in this configuration, it is outweighed by the benefits. Importantly, this option is cost intensive and hence may be considered as a long term solution and especially after cost-benefit analysis. Finally, the results based on optimization of the existing design is recommended as short term solution for improvement of the BGM operation. Although the fineness achieved is still low (i.e. xP,80 = 327 µm) compared to the target (i.e. xP,80 = 125 µm), this gives additional advantage in the sense that, also better hydrocyclone performance is achieved in terms of overflow product (xP,80 = 105 µm vs. > 240 µm) , cut size (xT =133.1 µm vs. > 220 µm) and circulating load (CL =350 %). The improved overflow fineness will contribute to improved efficiency for the downstream processes.
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32

Aradi, Thabiani Cristine. "Planejamento de operações de manutenção submarina". Universidade de São Paulo, 2015. http://www.teses.usp.br/teses/disponiveis/3/3135/tde-07032016-115426/.

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A presente pesquisa buscou resolver o problema de planejamento de operações submarinas através das perspectivas de programação de tarefas e dimensionamento de frota. O problema consistiu em estabelecer a melhor sequência de tarefas a serem atendidas por embarcações levando em consideração sua compatibilidade, regras de sequenciamento e o tamanho da frota. O problema é uma extensão do modelo clássico de roteirização com janelas de tempo com o objetivo de minimizar os custos associados à roteirização e as perdas econômicas associadas às interrupções de produção. A resolução do trabalho concentrou-se no curto e longo prazo, utilizando como principal método de solução a heurística Simulated Anneling por meio de um algoritmo de simulação-otimização.
This research aimed at solving the problem of planning underwater operations that involves job scheduling and fleet sizing decisions. The problem consisted in establish the best sequence of tasks to be atended by vessels taking into account compatibility constraints, sequencing rules and the size of the fleet. The problem is an extension of the classical vehicle routing problem with time windows. The objective is to minimize the routing costs and the economic losses associated with production losses. The solution procedure focused on short and long-term decisions based on the heuristic Simulated Anneling through a simulation-optimization algorithm.
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33

Qi, Rui. "Optimization and optimal control of plant growth : application of GreenLab model for decision aid in agriculture". Phd thesis, Châtenay-Malabry, Ecole centrale de Paris, 2010. http://tel.archives-ouvertes.fr/tel-00494918.

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The objective of the thesis is to improve plant yield through optimization and optimal control based on the GreenLab plant growth model. Therefore, the thesis proposed a methodology for investigation of plant yield improvement，whose characteristics are that (1) investigations are all based on the functional-structural plant growth model GreenLab and (2) heuristic optimization algorithm and optimal control techniques are applied to the plant growth model in order to improve plant yield. By applying optimization techniques on different species of plants (crops or trees) and for different kinds of optimization problems, common characteristics that a plant with high yield should possess were obtained. The optimal results in the thesis revealed the source-sink dynamics during the plant growth. The optimization results can be considered as references to guide breeding for ideotype and to improve cultivation modes. The optimization application of GreenLab could thus be possibly used to the agricultural decision support system.To achieve the aims of the thesis, the thesis investigated the effects of endogenous factors and exogenous environmental factors of plant growth on plant yield separately. First, given environmental conditions, the thesis investigated endogenous factors, and then the thesis did optimal control on exogenous environmental factors given plant genotype. Therefore, the problems investigated in the thesis consist of general optimization problems and optimal control problems.The main contributions of the thesis include following issues: According to the species of plants, single optimization problems, multi-objective optimization problems and optimization problems with constraints with respect to plant endogenous factors were formulated and investigated, in order to find the ideotype of plants with high plant yield. A population based algorithm is more suitable for the optimization problems in this thesis. Due to its better performance compared with other heuristic optimization algorithms, all optimization problems were solved by a population-based, heuristic optimization algorithm, namely Particle Swarm Optimization (PSO). Optimal control on the pruning strategy was formulated and investigated in the thesis. As GreenLab can be considered as discrete dynamic system and the objective function of the optimal control problem is analytical, the gradient based method, which is based on the variational approach and Lagrange theory, was used to solve the optimal control problem. Moreover, the optimal solutions were compared with the ones found by PSO, in order to validate the PSO method. The insect population dynamics was modeled mathematically, which was compatible with the plant model GreenLab in terms of spatial and temporal scales, to study the effect of biotic factors on plant growth. The interaction among plants, pests and auxiliaries was implemented, and the ecosystem model, which involves the three tri-trophic components, was thus developed in the thesis. The tri-trophic ecosystem model can simulate the insect population dynamics and the plant growth with consideration of the interaction of insects. Moreover, the tri-trophic ecosystem model considered the partition of individuals in the insect population among plant organs, which is not taken into account in the previous works. A global sensitivity analysis method Morris method was used to analyze the most important parameters and the least influential parameters to model outputs of interest. Through optimization on pest management techniques, the optimal strategies of the application of the pest management techniques were obtained. Estimation of GreenLab parameters with about 400 sets of observation data of 44 tomato genotypes was done in the thesis, by using a generalized non-linear least square algorithm. Taking the estimated parameter values as parameter space, the GreenLab model parameters were optimized, in order to maximize the fruit yield. Through the analysis of the correlation of estimated and optimal parameters with the fruit yield by statistical analysis methods, the most important parameters that result in the difference of fruit yield were found. According to the correlation and optimization results, the phenotypic differences among genotypes were explained from the physiological point of view.
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Hussain, Mohammed Salih. "Numerical simulation and effective management of saltwater intrusion in coastal aquifers". Thesis, University of Exeter, 2015. http://hdl.handle.net/10871/19239.

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Seawater intrusion (SWI) is a widespread environmental problem, particularly in arid and semi-arid coastal areas. Unplanned prolonged over-pumping of groundwater is the most important factor in SWI that could result in severe deterioration of groundwater quality. Therefore, appropriate management strategies should be implemented in coastal aquifers to control SWI with acceptable limits of economic and environmental costs. This PhD project presents the development and application of a simulation-optimization (S/O) model to assess different management methods of controlling saltwater intrusion while satisfying water demands, and with acceptable limits of economic and environmental costs, in confined and unconfined coastal aquifers. The first S/O model (FE-GA) is developed by direct linking of an FE simulation model with a multi-objective Genetic Algorithm (GA) to optimize the efficiency of a wide range of SWI management scenarios. However, in this S/O framework, several multiple calls of the simulation model by the population-based optimization model, evaluating best individual candidate solutions resulted in a considerable computational burden. To solve this problem the numerical simulation model is replaced by an Evolutionary Polynomial Regression (EPR)-based surrogate model in the next S/O model (EPR-GA). Through these S/O approaches (FE-GA and EPR-GA) the optimal coordinates and rates of the both abstraction and recharge barriers are determined in the studied management scenarios. As a result, a new combined methodology, so far called ADRTWW, is proposed to control SWI. The ADRTWW model consists of deep Abstraction of saline water near the coast followed by Desalination of the abstracted water to a potable level for public uses and simultaneously Recharging the aquifer using a more economic source of water such as treated wastewater (TWW). In accordance to the available recharge options (injection through well or infiltration from surface pond), the general performance of ADRTWW is evaluated in different hydro-geological settings of the aquifers indicating that it offers the least cost and least salinity in comparison with other scenarios. The great capabilities of both developed S/O models in identification of the best management solutions and the optimal coordinates and rates of the abstraction well and recharge well/pond are discussed. Both FE-GA and EPR-GA can be successfully employed by a robust decision support system. In the next phase of the study, the general impacts of sea level rise (SLR), associated with its transgression nature along the coastline surface on the saltwater intrusion mechanism are investigated in different hypothetical and real case studies of coastal aquifer systems. The results show that the rate and the amount of SWI are considerably greater in aquifers with flat shoreline slopes compared with those with steep slopes. The SWI process is followed by a significant depletion in quantity of freshwater resources at the end of the century. The situation is exacerbated with combined action of SLR and groundwater withdrawals. This finding is also confirmed by 3D simulation of SWI in a regional coastal aquifer (Wadi Ham aquifer) in the UAE subjected to the coupled actions of SLR and pumping.
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Touš, Michal. "Výpočtový systém pro výběr optimálního způsobu využití energie generované spalovacími procesy". Doctoral thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2012. http://www.nusl.cz/ntk/nusl-234148.

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PhD thesis deals with application of simulation and optimization methods in the field of waste and biomass utilization for energy purposes. Current situation in this field is described in the introductory. Following chapters deal with approaches of creating mathematical models of apparatus and processes used in the field of interest for simulation and optimization purposes. Stochastic methods, which are widely applied for real problems solution, are mentioned as well. The core of the thesis consists in proposal of systematic approach and its application for simulation and optimization model building used in the field of interest. The application is demonstrated through two case studies. The first one deals with the building of simulation model of an existing waste-to-energy plant using its operation data. The second study deals with optimization model building and its application for a problem regarding utilization of biomass in an existing energy system.
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Castelan, Anne. "Modélisation de composants d'extraction de la chaleur : application à l'optimisation de système d'électronique de puissance". Thesis, Toulouse 3, 2017. http://www.theses.fr/2017TOU30341/document.

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Avec le remplacement des réseaux hydrauliques et pneumatiques à bord des aéronefs par des réseaux électriques, le nombre d'équipements embarqués pour assurer un bon fonctionnement augmentera. Le passage à un avion entièrement électrique permettrait de réduire les couts de production et fonctionnement, assurerait une meilleure fiabilité des systèmes, et réduirait l'impact écologique de la circulation d'un tel appareil. En effet, un tel avion serait plus léger qu'un avion actuel. Pour s'assurer de cela, il est nécessaire de réduire la masse des équipements embarqués servant à la gestion, la mise en forme, la distribution d'énergie électrique. Le dimensionnement et l'optimisation de la masse des équipements embarqués est donc une problématique fondamentale dans le développement de l'avion plus électrique. Cette masse est majoritairement fixée par les systèmes de refroidissement lorsque l'on considère des systèmes de conversion d'énergie. Parmi l'ensemble des systèmes de refroidissement disponibles et dédiés au refroidissement des convertisseurs statiques, deux grandes technologies ont été sélectionnées, dans l'objectif d'en produire des modèles dédiés à des routines d'optimisation. Les dissipateurs à ailettes droites en convection forcée, ainsi que les systèmes associant dissipateurs à ailettes et caloducs seront modélisés au cours de ces travaux de thèse. Des modèles analytiques de ces systèmes de refroidissement seront proposés, dans l'optique de pouvoir optimiser au mieux leur masse tout en assurant un bon fonctionnement thermique. Même si de nombreuses méthodes de dimensionnement et d'optimisation dédiées aux systèmes de refroidissement existent, notre choix de modélisation s'est porté sur une représentation analytique. En effet, ce type de modélisation est déduit d'une résolution exacte de l'équation de la chaleur pour représenter des configurations géométriques et thermiques simples. Les configurations sélectionnées correspondent à des configurations simples à modéliser analytiquement. L'avantage de tels modèles réside dans le fait que le comportement thermique de systèmes de refroidissement, i.e de la température de la source de chaleur à l'ambiant, est une fonction des paramètres géométriques, des matériaux et des conditions environnementales des systèmes de refroidissement. Ce sont donc des modèles très rapides d'exécution qui donnent une solution exacte du comportement thermique des dissipateurs modélisés. Ils présentent donc un réel intérêt dans l'optique d'optimiser la masse de ces systèmes
The replacement of hydraulic and pneumatic network embedded in aircraft by electrical network will increase the number of embedded systems to ensure the effective functioning of the aircraft. The development of an electrical aircraft will allow the reduction of production and functioning costs. It will also help ensure a better reliability of systems and will reduce the ecological impact of the aircraft circulation. This kind of plane would be lighter than a usual one. To be sure of this, it is necessary to reduce weight of embedded equipment's dedicated to management, conversion and distribution of electrical energy. The sizing and the optimization of embedded equipment's weight is a critical issue in the development of more electrical aircraft. This weight is mostly defined by heat transfer systems, when we consider the sizing of energy conversion system A lot of heat transfer system exists and are dedicated to the cooling of power converters. We selected two of these heat transfer system, in order to produce models of them. These models will be used in optimization routines. Plate fin heat sink in forced convection, and system assembly, combining heat pipe and plate fin heat sink, will be modelled during this thesis. Analytical models of these heat transfer systems will be developed, to optimize their weight and ensure a good cooling of electrical systems. Even if lots of dimensioning and optimization methods exists, dedicated to heat transfer systems, we choose to use analytical modelling. This kind of models gives an exact solution to the heat equation, to describe simple geometric and thermic configurations. Selected heat transfer systems can be simply described. The main advantage of these models is that it represents the thermal behavior of the system as a function of its geometrical parameters, materials and environmental conditions. Execution of these models is very fast and gives a precise solution of the thermal parameters of the described configuration. There is then a real interest to use this type of models to optimize weight of heat transfer systems, and then power converter
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37

Lamy, Christophe. "Novel accurate tyre slip angle measurement means : application to tyre model identification". Thesis, Mulhouse, 2010. http://www.theses.fr/2010MULH3256.

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Le trafic routier devenant de plus en plus dense, la sécurité active des véhicules doit être sans cesse améliorée. Ceci nécessite notamment une amélioration de la dynamique des véhicules. La majeure partie des efforts transmis par la chaussée au véhicule passant par les pneumatiques, une connaissance précise de l’interface pneu-sol est primordiale. Ceci passe notamment par le développement de modèles de pneumatiques et leur identification, à partir de mesures spécifiques, lors des phases de conception et de mise au point d’un véhicule. Le projet de thèse a pour objectif principal de contribuer à une meilleure détermination du point de fonctionnement dynamique de l’ensemble pneumatique/roue. Plus précisément, il s’agit d’améliorer la détermination de l’angle de dérive du pneumatique, dont la précision est encore aujourd’hui insuffisante pour une analyse des performances des pneumatiques à partir d’essais sur piste. Cette détermination est réalisée simultanément à la détermination des autres grandeurs nécessaires à l’étude de l’interface roue-sol : glissement longitudinal du pneumatique, angle de carrossage de la roue et torseur des efforts roue-sol. Ce projet s’est appuyé sur la collaboration entre la Direction de la Recherche de Renault et le laboratoire MIPS de l’Université de Haute-Alsace. Des études préliminaires menées par Renault et par le MIPS sur ce sujet ont servi de support à ce projet.Une étude menée en début de thèse a permis de rédiger un cahier des charges exhaustif, en termes de performances de mesure de l’angle de dérive du pneumatique, permettant d’étudier avec suffisamment de précision la dynamique du véhicule, en se basant sur indicateurs de performance. Afin de répondre au cahier des charges, une solution de mesure novatrice de l’angle de dérive du pneu a été conçue et développée au cours de la thèse. Celle-ci se base sur l’intégration de mesures inertielles et GPS au niveau du plan de jante, à l’aide d’un filtre de Kalman étendu (EKF). Par la suite, un capteur de mesure (INS/GPS) dédié a été conçu, développé et enfin intégré à un véhicule d’essais. Les performances de mesure du nouveau capteur INS/GPS ont été validées vis-à-vis du cahier des charges, en suivant une procédure de caractérisation mise au point spécifiquement durant la thèse. L’angle de dérive pneu est ainsi mesuré avec une précision de 0,1° (à 3o) sur une plage de 360°, tout en étant insensible à la texture et à la granularité de la chaussée ; contrairement aux solutions industrielles existantes. Lorsque ce moyen de mesure novateur est couplé à d’autres mesures standard de la dynamique du véhicule, le mouvement complet du plan de jante est alors déterminé également avec la précision requise. Ceci en ajoutant uniquement un capteur au niveau du plan de jante, ce qui permet de limiter l’inertie ajoutée à la roue, en comparaison aux moyens de mesures existants.Pour valider le nouveau moyen de mesure développé et montrer tout son intérêt, une méthodologie d’identification d’un modèle de pneumatique (Magic Formula 5.2) a été proposée et validée expérimentalement. Un algorithme d’optimisation Simplex a été développé afin de pouvoir identifier un modèle de pneu, aussi bien à partir de mesures (sur piste ou sur banc de test) qu’à partir de données de simulation. Ainsi, les paramètres du modèle de pneumatique peuvent être optimisés durant la phase de conception d’un véhicule, afin de répondre à des indicateurs de performance du véhicule bien définis. Aujourd’hui, les mesures précises du capteur INS/GPS, conjuguées à l’algorithme d’optimisation développé, sont notamment utilisées pour identifier des modèles de pneu à partir de mesure sur piste, et pour définir les paramètres du modèle de pneu nécessaires, en phase de conception de véhicule. […]
The road traffic becomes more and more dense so that the active safety of road vehicles must continuously improved. This especially requires the improvement of the vehicle dynamics. The major part of the forces applied by the road to the vehicle are issued of the tyres. So, an accurate knowledge of the tyre-road interaction is primordial. This especially requires the development of the modelling and the identification of tyre models in the phases of design and tuning of a vehicle. The main goal of the thesis project is the contribution to a better determination of the dynamic functioning point of the system tyre/wheel. More accurately, is aims at improving the tyre slip angle determination accuracy, which is still insufficient for the analysis of tyre performance from vehicle-on-track tests. This determination is performed simultaneously to the determination of the other variables required in study of the tyre-road interface: longitudinal slip ratio, camber angle, tyre forces and moments. This project has been made in collaboration with the Research Department of Renault and the MIPS laboratory of the University of Haute-Alsace. Preliminary studies carried out by Renault and MIPS on this topic have served as a support to this project. A study carried out at the beginning of the thesis has helped to the determination of exhaustive requirements, in terms of tyre slip angle measurement performance, allowing the study of the vehicle dynamics with a sufficient accuracy, using performance indicators. A novel tyre slip angle measurement means has been developed in the thesis, in order to fit these requirements. It is based on the combination of inertial and GPS data near the wheel rim edge plane, using a extended Kalman filter (EKF). A dedicated measurement sensor (INS/GPS) has then be designed, developed and embedded in a test vehicle. The measurement performance of the novel INS/GPS has been validated according to the requirements, following a characterization procedure which has been specifically designed in the thesis. The tyre slip angle is then measured with an accuracy of 0.1° (at 3σ) in a range of 360°, with a insensitivity to the texture and the granularity of the road, contrary to the existing industrial solutions. When this novel measurement means is coupled with other standard measurements in vehicle dynamics, the whole motion of the wheel rim is then also determined with the required accuracy. This is made possible by mounting only one sensor at the level of the wheel rim edge plan, which helps to limit the inertia added to the wheel, in comparison with the existing measuring systems.A strategy of identification of a tyre model (Magic Formula 5.2) has been proposed and validated experimentally, in order to validate the novel measurement means developed. A Simplex optimization algorithm has been developed for the identification of a tyre model, from measurements (on a track or on a test rig) and/or simulation data. So, the tyre model parameters can be optimized in the phase of vehicle design, in order to fit well know vehicle performance indicators. The accurate INS/GPS measurements, combined with the optimization algorithm, are now especially used for the identification of tyre models from vehicle-on-track measurements and for the determination of the tyre model parameters required in the design phase. The novel INS/GPS is also considered as a reference for the tyre slip angle measurement, whatever the road grip (dry, wet, snow covered, ice covered ...). A number of research collaborations, especially with a worldwide tyre manufacturer, are been launched following the thesis results, especially for the study of the correlation between the physical tyre properties and the vehicle dynamics
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38

Torregrosa, Jaime Bárbara. "Modelling and analysis of an air-conditioning system for vehicles based on magnetocaloric refrigeration". Doctoral thesis, Universitat Politècnica de València, 2016. http://hdl.handle.net/10251/68503.

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[EN] This PhD thesis studies the application of the magnetic refrigeration technology in the air-conditioning system of automobiles. Thermal models of each of the components of such a system have been developed with the purpose of determining accurately its global performance. A dynamic one-dimensional model of a parallel-plate active magnetic regenerator (AMR) has been developed. The model is based in a new numerical scheme that reduces the computation time by 88% compared to the most commonly employed method. The model reproduces very accurately the passive regenerator cases with analytic solution and has been thoroughly validated against experimental results of both passive regenerator and AMR tests. The inclusion in the model of the magnetocaloric properties experimentally measured with a sample of the employed material, the demagnetizing effect, the fluid flow maldistribution and the losses to the ambient in the experimental setup have all been keys to obtain a good agreement with the experiments. The influence of the uncertainties and simplifications assumed when modelling these physical phenomena has been analyzed in detail, which has allowed the validation of different approaches. Besides, a dynamic model of the air-conditioning (AC) system of an electric vehicle has been developed. Thermal models of each of the system components have been included, namely the cabin, the hydraulic loops with the air-to-coolant heat exchangers and the electric auxiliaries. The modelling methodology employed is based on the combination of the conservation equations with the semi-empirical fitting of the global heat transfer coefficient. Excellent validation results have been obtained with experimental results in a wide range of operating conditions. The vehicle model has been employed to obtain the cooling and heating demand of a commercial full electric minibus, as well as the working temperatures. A broad optimization study has been carried out with the AMR model with the purpose of determining the design and working parameters of such a refrigerator that fulfil the cooling requirements of the vehicle with a minimum combined total system mass (affecting the weight of the vehicle and the economic cost) and electric consumption. The electric demand of the electrical AC auxiliaries has also been considered. Additionally, the heating performance of the optimal designs has been calculated. The application of AMR refrigerators in mobile air-conditioning systems is analyzed in comparison to the features of current vapor-compression systems.
[ES] En la presente tesis doctoral se ha estudiado la aplicación de un refrigerador magnético en un sistema de aire acondicionado para automóviles. Con el fin de determinar las prestaciones de dicho sistema de manera global y precisa, se ha desarrollado un modelo térmico de cada uno de sus componentes. Por un lado, se ha desarrollado un modelo dinámico unidimensional de regenerador magnético activo (AMR) de placas planas paralelas, basado en un nuevo esquema numérico que reduce el tiempo de cálculo hasta en un 88% respecto al esquema más empleado. El modelo reproduce con gran exactitud los casos de regenerador con solución analítica y ha sido validado exhaustivamente con resultados experimentales funcionando como regenerador pasivo y como AMR. Para obtener buenos ajustes ha sido clave la inclusión en el modelo de las propiedades magnetocalóricas medidas experimentalmente con una muestra del material empleado, el efecto desmagnetizante, la mala distribución del fluido y las pérdidas hacia el ambiente del montaje experimental. La influencia de las incertidumbres y las simplificaciones en el modelado de estos fenómenos se ha analizado detalladamente, lo cual ha permitido validar diferentes aproximaciones. Por otro lado, se ha desarrollado un modelo dinámico del sistema de aire acondicionado de un vehículo eléctrico. Se incluye el modelo térmico de la cabina, los bucles hidráulicos para la distribución de la potencia térmica con los intercambiadores de calor agua-aire y los auxiliares eléctricos. La metodología empleada para el desarrollo de estos modelos, basada en la combinación de ecuaciones de conservación con el ajuste semi-empírico de los coeficientes globales de transmisión de calor, ha producido excelentes resultados de validación con resultados experimentales en un amplio rango de condiciones de funcionamiento. El modelo del vehículo se ha empleado para obtener la demanda de refrigeración y calefacción de un minibús eléctrico comercial, así como las temperaturas de funcionamiento del sistema. Con el modelo de AMR se ha llevado a cabo un amplio estudio de optimización para determinar los parámetros de diseño y de funcionamiento de dicho refrigerador que cubren las necesidades de refrigeración del vehículo una masa del conjunto del sistema y un consumo eléctrico mínimos, incluyendo el consumo de los auxiliares. Adicionalmente se han calculado las prestaciones de calefacción de las combinaciones óptimas. La aplicabilidad de este sistema en automóviles se analiza en comparación con un sistema equivalente de compresión de vapor.
[CAT] En aquesta tesi doctoral s'ha estudiat l'aplicació d'un refrigerador magnètic en un sistema d'aire condicionat per a automòbils. A fi de determinar les prestacions d'aquest sistema de manera global i precisa, s'ha desenvolupat un model tèrmic de cadascun dels components. D'una banda, s'ha desenvolupat un model dinàmic unidimensional de regenerador magnètic actiu (AMR) de plaques planes paral·leles, basat en un nou esquema numèric que redueix el temps de càlcul fins d'un 88% respecte a l'esquema més emprat. El model reprodueix amb gran exactitud els casos de regenerador amb solució analítica, i ha sigut validat exhaustivament amb resultats experimentals funcionant com a regenerador passiu i com a AMR. Per a obtenir bons ajustos ha sigut clau la inclusió en el model de les propietats magnetocalòriques mesurades experimentalment amb una mostra del material emprat, l'efecte desmagnetitzador, la mala distribució del fluid i les pèrdues cap a l'ambient del muntatge experimental. La influència de les incerteses i les simplificacions en la modelització d'aquests fenòmens s'ha analitzat detalladament, la qual cosa ha permès validar diferents aproximacions. D'altra banda, s'ha desenvolupat un model dinàmic del sistema d'aire condicionat d'un vehicle elèctric. S'hi inclouen el model tèrmic de la cabina, els bucles hidràulics per a la distribució de la potència tèrmica amb els bescanviadors de calor aigua-aire i els auxiliars elèctrics. La metodologia emprada per al desenvolupament d'aquests models, basada en la combinació d'equacions de conservació amb l'ajust semiempíric dels coeficients globals de transmissió de calor, ha produït excel·lents resultats de validació amb resultats experimentals en un ampli rang de condicions de funcionament. El model del vehicle s'ha emprat per a obtenir la demanda de refrigeració i calefacció d'un minibús elèctric comercial, així com les temperatures de funcionament del sistema. Amb el model d'AMR s'ha dut a terme un ampli estudi d'optimització per determinar els paràmetres de disseny i de funcionament de la refrigeradora esmentada que cobreixen les necessitats de refrigeració del vehicle, una massa del conjunt del sistema i un consum elèctric mínims, incloent el consum dels auxiliars. Addicionalment s'han calculat les prestacions de calefacció de les combinacions òptimes. L'aplicabilitat d'aquest sistema en automòbils s'analitza comparant-la amb la d'un sistema equivalent de compressió de vapor.
Torregrosa Jaime, B. (2016). Modelling and analysis of an air-conditioning system for vehicles based on magnetocaloric refrigeration [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/68503
TESIS
Premiado
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39

Rotunno, Giuliana. "Integrated techniques for the internal logistics analysis and management of complex systems". Doctoral thesis, Università degli studi di Trieste, 2013. http://hdl.handle.net/10077/8531.

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2011/2012
In the context of manufacturing systems management, a decisive role is played by logistics, which may be defined as a planning and organization process aimed at optimizing the flow of material and information within and outside the company. In detail, the internal logistic systems are an important part of the modern industry and their design is challenging due to high complexity and heterogeneity of the manufacturing plants. Moreover, the analysis and management of the logistics in complex manufacturing systems is a widely discussed research topic in the related scientific literature. In this thesis the study of the internal logistic, and specifically application to manufacturing system, is taken into account in relation to the complexity features that characterize such systems. Despite the numerous contributions in the related literature proposing manufacturing logistic management approaches, few attempts were made to propose systematic techniques that, while improving the manufacturing system internal logistics and the related performances, are able to assess the manufacturing dynamics and the corresponding improvement. Therefore, the research results presented in this thesis are focused on the development of twoinnovative strategies and integrated techniques to analyze and manage the internal logistics of complex manufacturing systems. First, we present a novel hierarchical and iterative technique for the analysis and lean management of the internal logistics of discrete manufacturing systems. The technique efficiently integrates the Value Stream Mapping (VSM) tool, the Analytic Hierarchy Process (AHP) methodology and discrete event simulation in order to systematically improve the manufacturing system behaviour by rigorously assessing the system dynamics and corresponding performance indicators. Second, we deal with the scheduling of operations in Steelmaking and Continuous Casting (SM-CC) plants. Despite the numerous contributions, all the published papers in the field two limitations in real applications: (i) they do not consider the detailed description of the complete system from the structural and dynamic viewpoints; (ii) the authors focus on the process of the SM-CC plant and do not consider some peculiar characteristic of the main machines involved on the process, such as the continuous casting machines. In order to face the problem of the management and optimization of the production in the steel making continuous casting we propose an integrated a methodology to describe, assess and improve the logistics of the SM-CC processes: the Unified Modeling Language (UML), the discrete event simulation and the Mixed Integer Linear Programming (MILP) formulation. The application of the techniques to some real cases studies shows the effectiveness of the proposed management and optimization strategies.
XXV Ciclo
1979
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40

Sassi, Kamal M. "Optimal scheduling, design, operation and control of reverse osmosis desalination : prediction of RO membrane performance under different design and operating conditions, synthesis of RO networks using MINLP optimization framework involving fouling, boron removal, variable seawater temperature and variable fresh water demand". Thesis, University of Bradford, 2012. http://hdl.handle.net/10454/5671.

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An accurate model for RO process has significant importance in the simulation and optimization proposes. A steady state model of RO process is developed based on solution diffusion theory to describe the permeation through membrane and thin film approach is used to describe the concentration polarization. The model is validated against the operation data reported in the literature. For the sake of clear understanding of the interaction of feed temperature and salinity on the design and operation of RO based desalination systems, simultaneous optimization of design and operation of RO network is investigated based on two-stage RO superstructure via MINLP approach. Different cases with several feed concentrations and seasonal variation of seawater temperature are presented. Also, the possibility of flexible scheduling in terms of the number of membrane modules required in operation in high and low temperature seasons is investigated A simultaneous modelling and optimization method for RO system including boron removal is then presented. A superstructure of the RO network is developed based on double pass RO network (two-stage seawater pass and one-stage brackish water pass). The MINLP problem based on the superstructure is used to find out an optimal RO network which will minimize the total annualized cost while fulfilling a given boron content limit. The effect of pH on boron rejection is investigated at deferent seawater temperatures. The optimal operation policy of RO system is then studied in this work considering variations in freshwater demand and with changing seawater temperature throughout the day. A storage tank is added to the RO layout to provide additional operational flexibility and to ensure the availability of freshwater at all times. Two optimization problems are solved incorporating two seawater temperature profiles, representing summer and winter seasons. The possibility of flexible scheduling of cleaning and maintenance of membrane modules is investigated. Then, the optimal design and operation of RO process is studied in the presence of membrane fouling and including several operational variations such as variable seawater temperature. The cleaning schedule of single stage RO process is formulated as MINLP problem using spiral wound modules. NNs based correlation has been developed based on the actual fouling data which can be used for estimating the permeability decline factors. The correlation based on actual data to predict the annual seawater temperature profile is also incorporated in the model. The proposed optimization procedure identified simultaneously the optimal maintenance schedule of RO network including its design parameters and operating policy. The steady state model of RO process is used to study the sensitivity of different operating and design parameters on the plant performance. A non-linear optimization problem is formulated to minimize specific energy consumption at fixed product flow rate and quality while optimizing the design and operating parameters. Then the MINLP formulation is used to find the optimal designs of RO layout for brackish water desalination. A variable fouling profile along the membrane stages is introduced to see how the network design and operation of the RO system are to be adjusted Finally, a preliminary control strategy for RO process is developed based on PID control algorithm and a first order transfer function (presented in the Appendix).
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41

Scolan, Simon. "Développement d'un outil de simulation et d'optimisation dynamique d'une centrale solaire thermique". Thesis, Pau, 2020. http://www.theses.fr/2020PAUU3007.

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Dans le contexte climatique et énergétique actuel, des solutions doivent être trouvées pour remplacer progressivement l'usage des énergies fossiles. Le solaire thermique est une ressource disposant d'un fort potentiel encore trop peu exploité en France à l'échelle industrielle. Dans ce contexte, les grandes installations solaires thermiques sont de plus en plus étudiées. Actuellement, la majorité des études porte sur l'optimisation du dimensionnement des centrales en se basant sur des stratégies de pilotage standard. Le présent manuscrit propose une méthodologie de résolution mathématique pour la simulation et l'optimisation dynamique d'une centrale solaire thermique. Ce type d'optimisation permet de prendre en compte la dynamique de ce système, et en particulier la dynamique lente d'un stockage d'énergie thermique, et est réalisée en exploitant les degrés de liberté du problème tel qu'on le pose. Ainsi, en laissant libres certains paramètres de design, l'optimisation dynamique permet d'optimiser simultanément le fonctionnement et le dimensionnement de la centrale. Les différents éléments d'une centrale solaire thermique (champ solaire, échangeur de chaleur, stockage thermique, pompes, canalisations) sont modélisés et forment un système d'équations algébro-différentielles. Nous détaillons la méthode de collocation orthogonale sur éléments finis permettant de discrétiser ces équations et d'obtenir ainsi un système comprenant uniquement des équations algébriques. Différents modèles sont confrontés à des données expérimentales issues de la centrale de Condat-sur-Vézère et leur précision est quantifiée. Le développement d'une méthode par simulations et initialisations successives nous a permis de réaliser la simulation dynamique d'une centrale solaire thermique. Cependant, certaines contraintes de fonctionnement (règles de pilotage nécessaires pour saturer les degrés de liberté) sont difficiles à formuler de façon cohérente et implémentable dans le logiciel GAMS utilisé dans ces travaux. L'intérêt de l'optimisation dynamique est de tirer profit des degrés de liberté du problème afin de minimiser/maximiser une fonction objectif (en respectant les contraintes du problème) sans avoir à formuler des contraintes pour saturer les variables d'intérêt. Un premier problème d'optimisation dynamique a été formulé puis résolu suivant une stratégie orientée-équation. Sur un horizon de temps de cinq jours et avec un dimensionnement de centrale fixé, nous avons maximisé les bénéfices liés à la vente de chaleur solaire à un consommateur en optimisant le fonctionnement de la centrale. Cela a notamment fait ressortir des stratégies parfois contre-intuitives permettant une amélioration significative de la fonction objectif par rapport à des pilotages plus « classiques ». En particulier, l'utilisation d'une inclinaison dynamique des capteurs s'est montrée efficace, d'une part, pour augmenter l'énergie captée par le champ solaire et, d'autre part, pour gérer d'éventuelles surchauffes en défocalisant les capteurs par rapport à la trajectoire de captation maximale. L'utilisation d'un stockage thermique a également été utile pour permettre le déphasage entre la production et la demande. La formulation d'un second problème d'optimisation, sur un horizon de temps d'un an, a permis de minimiser le coût moyen de la chaleur solaire vendue au consommateur (sur la durée du projet) en déterminant le dimensionnement optimal de la centrale et les profils temporels optimaux des variables de fonctionnement en fonction de la courbe de charge. Des difficultés ont été rencontrées, notamment pour conserver un fonctionnement cohérent sur la période d'optimisation. Finalement, nous avons listé un certain nombre de pistes qui pourraient potentiellement améliorer les résultats obtenus
In the current climate and energy context, solutions must be found to gradually replace the use of fossil fuels. Solar thermal energy is a resource with great potential that is still insufficiently exploited in France on an industrial scale. In this context, large solar thermal installations are increasingly studied. Currently, a majority of studies focus on optimizing the sizing of the plants based on standard operating strategies. This manuscript offers a mathematical resolution methodology for the simulation and dynamic optimization of a solar thermal plant. This type of optimization makes it possible to take into account the dynamics of this system and in particular the slow dynamics of a thermal energy storage. It is carried out by exploiting the degrees of freedom of the problem. By leaving certain design parameters free, dynamic optimization makes it possible to optimize the operation and sizing of the plant simultaneously.The different elements of a solar thermal plant (solar field, heat exchanger, thermal energy storage, pumps, pipes) are modeled and form a Differential Algebraic Equation system. We have described the orthogonal collocation method which allows to discretize these equations and thus, to obtain a system comprising only algebraic equations. Different models are confronted with experimental data from a plant located in Condat-sur-Vézère (France). Their precision is quantified. The development of a method by successive simulations and initializations allowed us to carry out the dynamic simulation of a solar thermal plant. However, certain operating constraints (control rules necessary to saturate the degrees of freedom) are difficult to formulate in a coherent and implementable way in the GAMS software used in this work. The interest of using dynamic optimization is to take advantage of the degrees of freedom of the problem in order to minimize / maximize an objective function (while respecting the constraints of the problem) without having to formulate constraints to saturate them.A first dynamic optimization problem was formulated and then solved, using an equation-oriented strategy. Over a five-day time horizon and with a fixed plant sizing, we have maximized the benefits from the sale of solar heat to a consumer by optimizing the operation of the plant. This notably brought to light counter-intuitive operating strategies allowing a significant improvement of the objective function compared to more standard strategies. In particular, the use of a dynamic inclination of the flat-plate collectors (as with a solar tracking device) has proved effective, on the one hand, to increase the energy captured by the solar field and, on the other hand, to handle possible overheating by defocusing the collectors from the maximum energy capture trajectory. The use of a thermal energy storage was also useful to allow the phase difference between production and demand.The formulation of a second optimization problem, over a time horizon of one year, made it possible to minimize the average cost of solar heat sold to the consumer (over the duration of the project) by determining the optimal sizing of the plant and the optimal time profiles of the operating variables as a function of the load curve. Difficulties have been encountered, in particular to maintain consistent operation over the optimization period. Finally, we listed a number of leads that could potentially improve the results obtained
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42

Gonçalves, Da Silva Pinto Wagner José. "Modelling airframe noise : from aerodynamic topology to acoustic efficiency". Thesis, Poitiers, 2019. http://www.theses.fr/2019POIT2289.

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L’influence de la forme de cylindres longs sur leur rayonnement acoustique en écoulement est étudiée. Des simulations bidimensionnelles (2D) sont réalisées à bas nombre de Reynolds (Re=20-200), à l’aide du code de calcul direct (DNS) incompressible incompact3D au moyen d’une méthode de frontière immergée (IBM). Une formule dérivée de l’équation de Curle pour un cylindre compact permet la quantification de l’émission acoustique en 2D. En soufflerie anéchoïque, la signature acoustique d’une trentaine de géométries est mesurée, Re=4,000-53,000 ; l’anémométrie par fil chaud est utilisée pour la description des propriétés axiales de l’écoulement. L’avant corps et l’allongement (AR) sont les plus importantes propriétés géométriques tant pour l’écoulement que pour le rayonnement acoustique en 2D. Les géométries allongées sont généralement les plus silencieuses car les tourbillons sont moins intenses et repoussés vers l’aval et l’apparition de l’instationnarité est retardée. De leur côté, les résultats expérimentaux montrent que les géométries allongées sont les plus bruyantes, ce qui est à l’opposé des conclusions précédentes. Ceci est justifié par une augmentation significative de la cohérence de l’écoulement en envergure pour les AR les plus longs, presque complètement en phase, donc plus efficace acoustiquement. Globalement, cela implique que les géométries dont l’écoulement 2D est faiblement perturbé, marqué par un déclenchement plus tardif de l’instationnarité (Reynolds critique plus élevé), sont aussi plus organisées en 3D aux Re des mesures. La relation sous-jacente entre les transitions successives vers la turbulence nécessite une étude approfondie
The influence of the shape on the sound emission of cylindrical bluff-bodies is studied. Simulations are performed in two-dimensions (2D) at low-Reynolds number (Re=20-200), with the incompressible direct Navier-Stokes (DNS) solver incompact3D, using the Immersed Boundary Method (IBM) formalism; the acoustic emission is evaluated by a single formula derived from Curle’s equation for compact cylinders. In anechoic wind tunnel, the acoustic signature is measured for about 30 geometries, Re=4,000-53,000; hot-wire measurements of the spanwise flow characteristics are performed for a subset of the tested cylinders. The influence of both the shape of the upstream portion of the geometry and the breadth-to-height ratio (AR) are proved to be major features in terms of both the flow and its acoustic emission in 2D. By reducing the strength of the vortices and pushing them downstream and affecting the mechanics of the von Kármán instability (delaying the transition to unsteadiness), stretched shapes (with higher AR) are generally quieter. From the experiments, it is found that the geometries of biggest AR are the loudest, contraposing the results obtained in 2D. The disparity is justified by a significant increase of the spanwise coherence associated with the larger AR’s, practically fully-phased, thus more acoustically efficient. Globally, it is implied that geometries which have weakly perturbed flow in 2D, marked by a later transition to unsteadiness (larger critical Reynolds number), are also more organized in 3D, high-Reynolds number regimes. The underlying relationship between low and high-Reynolds number transitions must be further investigated
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43

Richtr, Jiří. "Využití diskrétní simulace při řízení výrobního procesu". Master's thesis, Vysoké učení technické v Brně. Fakulta podnikatelská, 2011. http://www.nusl.cz/ntk/nusl-223057.

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Simulace výrobních procesů pomáhá optimalizovat výrobu, logistiku a další systémy, díky čemuž dochází ke snižování nákladů a racionalizaci vnitropodnikových procesů. Využitím diskrétní simulace programu Witness Power with Ease se v diplomové práci optimalizuje logistický tok materiálu ve společnosti Hella Autotechnik, s.r.o. Práce přibližuje metody a jednotlivé fáze tvorby modelu včetně jeho validace a navrhuje vylepšení, díky kterému by mělo dojít ke snížení nákladů na dopravní služby o 24 400 Kč měsíčně.
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44

Loos, Florian [Verfasser], Hans-Dieter [Akademischer Betreuer] Ließ i Thomas [Akademischer Betreuer] Apel. "Joule Heating in Connecting Structures of Automotive Electric Devices – Modelling, Simulation and Optimization / Florian Loos. Universität der Bundeswehr München, Fakultät für Bauingenieurwesen und Umweltwissenschaften. Gutachter: Hans-Dieter Ließ ; Thomas Apel. Betreuer: Hans-Dieter Ließ". Neubiberg : Universitätsbibliothek der Universität der Bundeswehr München, 2014. http://d-nb.info/1058176838/34.

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45

Liu, Xing. "Modélisation, analyse et optimisation de la résilience des infrastructures critiques interdépendantes". Thesis, Université Paris-Saclay (ComUE), 2017. http://www.theses.fr/2017SACLC080.

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La résilience concerne une capacité importante d'un système à résister et à se remettre des événements perturbateurs. L'objectif de cette thèse est de construire un cadre d'analyse et d'optimisation de la résilience des infrastructures critiques interconnectées (ICIs). Dans ce travail, les contributions scientifiques originales comprennent: 1) une approche de modélisation générique pour décrire le comportement dynamique et les processus d'échec en cascade dans les ICIs. 2) basé sur le modèle proposé, une approche quantitative d'évaluation de la résilience de ICIs est développée, où les aspects d'atténuation et de récupération sont évalués; 3) afin de réduire le coût de calcul dans le cas de systèmes à grande échelle, trois méthodes Différentes échelle, trois méthodes différentes d'analyse de sensibilité globale (ANN estimation, ensemble-based, given-data estimation), sont mis en place pour identifier les paramètres de modèle les plus pertinents affectant la résilience du système, puis les performances de ces méthodes sont comparées;4) un modèle hiérarchique est développé pour caractériser les facteurs de stratégies d'amélioration de la résilience. Un problème d’optimisations multi-objectif est formulé et résolu par l'algorithme NSGA-II, afin de fournir un plan optimal pour l'amélioration de la résilience du système. Les méthodes proposées sont mises en œuvre dans les applications, par exemple, un réseau d'alimentation en gaz et un réseau électrique
Resilience is the ability of a system to resist to and recover from disruptive events. The objective of this thesis is to build a framework of analysis and optimization of interconnected critical infrastructures (ICIs) resilience. In this work, the original scientific contributions include: 1) a generic modeling approach to describe the dynamic behavior and the physical cascading failure processes in ICIs.2) on the basis of the model, a quantitative resilience assessment approach for ICIs is proposed, where both the mitigation and recovery aspects of system resilience are evaluated; 3) in order to reduce the computational cost in the case of large-scale systems, three different global sensitivity analysis methods (ANN estimation, ensemblebased, give-data estimation) are implemented to identify the most relevant model parameters affecting the system resilience, and then the performance of these methods are compared; 4) a hierarchical model is developed to characterize the factors of resilience improvement strategies. A multi-objectives optimization problem is formulated and solved by NSGA-II algorithm, to provide the optimal plan for system resilience improvement. The methods proposed are implemented to applications, e.g., a gas supply network and an electrical power grid
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46

Ajimotokan, Habeeb A. "A study of trilateral flash cycles for low-grade waste heat recovery-to-power generation". Thesis, Cranfield University, 2014. http://dspace.lib.cranfield.ac.uk/handle/1826/9202.

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There has been renewed significance for innovative energy conversion technologies, particularly the heat recovery-to-power technologies for sustainable power generation from renewable energies and waste heat. This is due to the increasing concern over high demand for electricity, energy shortage, global warming and thermal pollution. Among the innovative heat recovery-to- power technologies, the proposed trilateral flash cycle (TFC) is a promising option, which presents a great potential for development. Unlike the Rankine cycles, the TFC starts the working fluid expansion from the saturated liquid condition rather than the saturated, superheated or supercritical vapour phase, bypassing the isothermal boiling phase. The challenges associated with the need to establish system design basis and facilitate system configuration design-supporting analysis from proof-of-concept towards a market-ready TFC technology are significant. Thus, there is a great need for research to improve the understanding of its operation, behaviour and performance. The objective of this study is to develop and establish simulation tools of the TFCs for improving the understanding of their operation, physics of performance metrics and to evaluate novel system configurations for low-grade heat recovery-to-power generation. This study examined modelling and process simulation of the TFC engines in order to evaluate their performance metrics, predictions for guiding system design and parameters estimations. A detailed thermodynamic analysis, performance optimization and parametric analysis of the cycles were conducted, and their optimized performance metrics compared. These were aimed at evaluating the effects of the key parameters on system performances and to improve the understanding of the performance behaviour. Four distinct system configurations of the TFC, comprising the simple TFC, TFC with IHE, reheat TFC and TFC with feed fluid-heating (or regenerative TFC) were examined. Steady-state steady-flow models of the TFC power plants, corresponding to their thermodynamic processes were thermodynamically modelled and implemented using engineering equation solver (ESS). These models were used to determine the optimum synthesis/ design parameters of the cycles and to evaluate their performance metrics, at the subcritical operating conditions and design criteria. Thus, they can be valuable tools in the preliminary prototype system design of the power plants. The results depict that the thermal efficiencies of the simple TFC, TFC with IHE, reheat TFC and regenerative TFC employing n-pentane are 11.85 - 21.97%, 12.32 - 23.91%, 11.86 - 22.07% and 12.01 - 22.9% respectively over the cycle high temperature limit of 393 - 473 K. These suggest that the integration of an IHE, fluid-feed heating and reheating in optimized design of the TFC engine enhanced the heat exchange efficiencies and system performances. The effects of varying the expander inlet pressure at the cycle high temperature and expander isentropic efficiency on performance metrics of the cycles were significant. They have assisted in selecting the optimum-operating limits for the maximum performance metrics. The thermal efficiencies of all the cycles increased as the inlet pressures increased from 2 - 3 MPa and increased as the expander isentropic efficiencies increased from 50 - 100%, while their exergy efficiencies increased. This is due to increased net work outputs that suggest optimal value of pressure ratios between the expander inlets and their outlets. A comprehensive evaluation depicted that the TFC with IHE attained the best performance metrics among the cycles. This is followed by the regenerative TFC whereas the simple TFC and reheat TFC have the lowest at the same subcritical operating conditions. The results presented show that the performance metrics of the cycles depend on the system configuration, and the operating conditions of the cycles, heat source and heat sink. The results also illustrate how system configuration design and sizing might be altered for improved performance and experimental measurements for preliminary prototype development.
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47

Fabre, Florian. "Conduite orientée ordonnancement d'un simulateur dynamique hybride : application aux procédés discontinus". Thesis, Toulouse, INPT, 2009. http://www.theses.fr/2009INPT023G/document.

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Ce manuscrit présente des travaux visant à intégrer un module d'ordonnancement (ProSched) à l'environnement de modélisation et simulation dynamique hybride PrODHyS dans le but d'automatiser la génération de scénarii de simulation de procédés discontinus sur la base d'une recette et d'une liste d'ordres de fabrication (OF). La méthodologie développée repose sur une approche mixte optimisation/simulation. Dans ce cadre, trois points essentiels ont été développés dans ces travaux : - tout d'abord, concevoir et développer des composants réutilisables (classes de recette) permettant de modéliser de manière hiérarchisée et systématique le déroulement des opérations unitaires. Pour cela, les notions de jeton Task et de macro-place paramétrable ont été introduites dans les RdPDO et permettent de décrire les recettes à réaliser par assemblage de ces composants prédéfinis. - ensuite, définir un modèle mathématique générique d'ordonnancement basé sur un formalisme de représentation bien établi (le R.T.N.) qui permet de modéliser les principales caractéristiques d'un procédé discontinu et de fournir l'ensemble des données d'entrée nécessaires au modèle de simulation. Pour cela, un modèle PLNE basé sur la formulation Unit Specific Event a été mis en œuvre. - enfin, définir l'interface existant entre le modèle d'optimisation et le modèle de simulation, à travers la notion de place de pilotage et de centre de décision au niveau du simulateur. Dans ce cadre, différentes stratégies de couplage sont proposées. Les potentialités de cette approche sont illustrées par la simulation d'un procédé complet
This thesis presents works which aim to incorporate a scheduling module (ProSched) to an environment for modeling and dynamic hybrid simulation PrODHyS in order to automate the generation of scenarios for simulation of batch processes based on a recipe and a list of production orders (OF). The methodology developed is based on a mixed optimization / simulation approach. In this context, three key points have been developed in this work: - First, design and develop reusable components (recipe classes) for the hierarchical and systematic modeling of the sequencing of unit operations. For this, the notions of Task token and macro-place have been introduced in the RdPDO formalism and allow the modeling of recipes by assembling these predefined components. - Secondly, define a generic mathematical model of scheduling based on a well defined graphical formalism (RTN) that models the main characteristics of batch processes and provide all input data necessary to the simulation model. For this, a MILP model based on the Unit Specific Event formulation has been implemented. - Finally, define the interface between the optimization model and the simulation model through the concept of control place and decision-making center at the simulator level. In this context, various strategies of mixing optimization and simulation are proposed. The potential of this approach is illustrated by the simulation of a complete manufacturing process
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48

Gely, Laurent. "Modélisation et optimisation de la gestion opérationnelle du trafic ferroviaire en cas d’aléas". Thesis, Bordeaux 1, 2010. http://www.theses.fr/2010BOR14177.

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La régulation ferroviaire sur de vastes zones est un problème complexe. Elle intervient dans la phase opérationnelle de la production. Son rôle consiste à trouver de nouvelles solutions en termes de planification des mouvements de trains suite à l'apparition d'un incident empêchant la réalisation normale du plan de transport préétabli dans les phases amont de la production.La contribution de ce travail s'organise autour de trois axes.Le premier consiste à définir une formalisation exhaustive du système ferroviaire, associé à une représentation plus cohérente (modèle multiniveau).Le deuxième axe s'articule autour de l'étude des modèles mathématiques pour la régulation du trafic ferroviaire: évolutions d'un modèle en temps continu complet (espacements dynamiques), proposition d'un modèle innovant à temps discret et d'un modèle mixte (continu-discret) adossé au modèle multiniveau.Enfin, le dernier axe traite de la mise en oeuvre concrète au niveau industriel, en particulier des gains attendus du couplage avec un outil de simulation
On-line re-scheduling of trains aims to find accurate solutions after an incident has occurred on the railway network. When we consider a large area, solutions consist in calculating new timetables, sequences and routes of trains. This problem asks for decision support tools based on operational research techniques.This thesis aims to develop solutions toward an operational tool, it articulates around three main parts. The first part defines an exhaustive model of the railway system operations and a multiscalable description of the infrastructure.The second part presents three mathematical models of the rescheduling problem associated with this description. We preset a exhaustive continuous time based model including headways that take into account speeds of trains, plus a discrete time based model and an hybrid model combining both formulations.The last part describes first implementations and the global framework we need to develop in order to solve the real world problem. It emphases on expected synergies, specilaly between simulation and optimization techniques
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49

Hayati, Abolfazl. "Natural Ventilation and Air Infiltration in Large Single‑Zone Buildings : Measurements and Modelling with Reference to Historical Churches". Doctoral thesis, Högskolan i Gävle, Energisystem, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:hig:diva-24612.

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Natural ventilation is the dominating ventilation process in ancient buildings like churches, and also in most domestic buildings in Sweden and in the rest of the world. These buildings are naturally ventilated via air infiltration and airing. Air infiltration is the airflow through adventitious leakages in the building envelope, while airing is the intentional air exchange through large openings like windows and doors. Airing can in turn be performed either as single-sided (one opening) or as cross flow ventilation (two or more openings located on different walls). The total air exchange affects heating energy and indoor air quality. In churches, deposition of airborne particles causes gradual soiling of indoor surfaces, including paintings and other pieces of art. Significant amounts of particles are emitted from visitors and from candles, incense, etc. Temporary airing is likely to reduce this problem, and it can also be used to adjust the indoor temperature. The present study investigates mechanisms and prediction models regarding air infiltration and open-door airing by means of field measurements, experiments in wind tunnel and computer modelling. In natural ventilation, both air infiltration and airing share the same driving forces, i.e. wind and buoyancy (indoor-outdoor temperature differences). Both forces turn out to be difficult to predict, especially wind induced flows and the combination of buoyancy and wind. In the first part of the present study, two of the most established models for predicting air infiltration rate in buildings were evaluated against measurements in three historical stone churches in Sweden. A correction factor of 0.8 is introduced to adjust one of the studied models (which yielded better predictions) for fitting the large single zones like churches. Based on field investigation and IR-thermography inspections, a detailed numerical model was developed for prediction of air infiltration, where input data included assessed level of the neutral pressure level (NPL). The model functionality was validated against measurements in one of the case studies, indicating reasonable prediction capability. It is suggested that this model is further developed by including a more systematic calibration system for more building types and with different weather conditions. Regarding airing, both single-sided and cross flow rates through the porches of various church buildings were measured with tracer gas method, as well as through direct measurements of the air velocity in a porch opening. Measurement results were compared with predictions attained from four previously developed models for single‑sided ventilation. Models that include terms for wind turbulence were found to yield somewhat better predictions. According to the performed measurements, the magnitude of one hour single-sided open-door airing in a church typically yields around 50% air exchange, indicating that this is a workable ventilation method, also for such large building volumes. A practical kind of diagram to facilitate estimation of suitable airing period is presented. The ability of the IDA Indoor Climate and Energy (IDA-ICE) computer program to predict airing rates was examined by comparing with field measurements in a church. The programs’ predictions of single-sided airflows through an open door of the church were of the same magnitude as the measured ones; however, the effect of wind direction was not well captured by the program, indicating a development potential. Finally, wind driven air flows through porch type openings of a church model were studied in a wind tunnel, where the airing rates were measured by tracer gas. At single-sided airing, a higher flow rate was observed at higher wind turbulence and when the opening was on the windward side of the building, in agreement with field measurements. Further, the airing rate was on the order of 15 times higher at cross flow than at single-sided airing. Realization of cross flow thus seems highly recommendable for enhanced airing. Calibration constants for a simple equation for wind driven flow through porches are presented. The measurements also indicate that advection through turbulence is a more important airing mechanism than pumping.   The present work adds knowledge particularly to the issues of air infiltration and airing through doors, in large single zones. The results can be applicable also to other kinds of large single-zone buildings, like industry halls, atriums and sports halls.
Naturlig ventilation är den dominerande ventilationsprocessen i äldre byggnader såsom kyrkor, och även i de flesta småhus i Sverige och övriga delar av världen. Luftinfiltration och vädring utgör viktiga komponenter i naturlig ventilation, där luftinfiltration är luftflöde genom oavsiktliga läckage i byggnadsskalet, medan vädring är avsiktligt luftutbyte genom stora öppningar såsom fönster och dörrar/portar. Vädring kan i sin tur ske ensidigt (genom en öppning) eller som tvärdrag (genom två eller flera öppningar belägna på olika ytterväggar). Det totala luftutbytet påverkar värmeförluster och inomhusluftens kvalité. I kyrkor orsakar avsättning av luftpartiklar en gradvis nedsmutsning av invändiga ytor, inklusive väggmålningar och andra konstföremål. Betydande mängder partiklar avges från besökare, tända ljus, rökelse, o.d. Tillfällig vädring kan minska detta problem, men även användas för att justera innetemperaturen. Föreliggande studie analyserar mekanismer och predikteringsmodeller gällande luftinfiltration och dörrvädring genom fältmätningar, vindtunnelförsök och datorsimuleringar. Luftinfiltration och vädring har samma drivkrafter, d.v.s. vind och termik (inne‑ute temperaturskillnader). Båda dessa drivkrafter är svåra att predicera, särskilt vindinducerade flöden och kombinationen av termik och vind. Två av de mest etablerade modellerna för luftinfiltrationsprediktering i byggnader har utvärderats via mätningar i tre kulturhistoriska stenkyrkor i Sverige. En korrigeringsfaktor av 0,8 föreslås för bättre prediktion av den ena modellen (som gav bäst resultat) gällande höga en-zonsbyggnader såsom kyrkor. En detaljerad numerisk modell är utvecklad för luftinfiltrationsprediktering, där indata baseras på fältundersökningar, inkl. IR-termografering och uppmätt av neutrala tryckplanet (NPL). Modellens funktionalitet har validerats via mätningar i en av fallstudierna och pekar på tämligen god prediktionsprestanda. Vidare utveckling av modellen föreslås, inkl. ett mer systematiskt kalibreringssystem, för olika typer av byggnader och väderförhållanden. Gällande vädring mättes både ensidigt flöde och tvärdrag genom portar i olika kyrkobyggnader med hjälp av spårgas samt direkta lufthastighetsmätningar i portöppning. Mätresultaten jämfördes med erhållna prediktioner från fyra tidigare utvecklade modeller för ensidig ventilation. De modeller som tog hänsyn till vindturbulens gav något bättre resultat. Enligt utförda mätningar medför en timmes ensidig portvädring i en kyrka cirka 50 % luftutbyte, vilket indikerar att detta är en tillämpbar ventilationsmetod, även för så pass stora byggnadsvolymer. Ett särskilt vädringsdiagram presenteras, som syftar till att underlätta uppskattning av erforderlig vädringsperiod. Vidare studerades predikteringsprestanda hos IDA Indoor Climate and Energy (IDA-ICE) simuleringsprogram avseende vädring, där simuleringsdata jämfördes med fältmätningar i en kyrka. Programmets prediktion av ensidigt luftflöde genom en öppen kyrkport var av samma storlekordning som det uppmäta; dock klarade programmet inte av att hantera inverkan av vindriktning så väl, vilket pekar på en utvecklingspotential. Avslutningsvis undersöktes vinddrivet flöde igenom portöppningar i en kyrkmodell i vindtunnel, där luftomsättningen mättes med hjälp av spårgasmetoden. Vid ensidig vädring observerades högre flöde vid högre vindturbulens och när öppningen var på vindsidan av byggnaden, i överensstämmelse med fältmätningarna. Dessutom var vädringsflödet vid tvärdrag i storleksordningen 15 högre än det vid ensidig vädring. Det verkar alltså som att man kan öka vädringstakten avsevärt om man kan åstadkomma tvärdrag. Kalibreringskonstanter presenteras också för en enkel ekvation för vinddrivet flöde genom portar. Vindtunnelstudien indikerar vidare att advektion genom turbulens är en viktigare vädringsmekanism än pumpning. Föreliggande arbete bidrar med kunskap speciellt kring luftinfiltration och vädring genom portar i höga en-zonsbyggnader. Resultaten kan även vara tillämpliga på andra typer av höga en-zonsbyggnader såsom industrihallar, atrier/ljusgårdar och idrottshallar.
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Grandicki, Andreas, i Mattias Lokgård. "Parametric CAD Modeling to aid Simulation-Driven Design : An evaluation and improvement of methods used at Scania". Thesis, Linköpings universitet, Maskinkonstruktion, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-138121.

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This report documents a thesis conducted at Scania CV AB in Södertälje, Sweden. The main purpose of the thesis has been to examine and improve upon current practices of parametric CAD-modeling at Scania, with the ultimate goal of increased design automation and simulation-driven design. The thesis was initiated with a literature study, mainly covering the fields of parametric CAD-modeling, design automation and knowledge-based engineering. Furthermore, a questionnaire and multiple interviews were conducted to assess the awareness and mind-set of the employees. Finally, a case-study was carried out to follow current methodologies, and address any deficiencies found. Some of the most important findings were that while parametric modeling has considerable potential in enabling design automation, it is crucial, and most beneficial in terms of automation efficiency, to start with the fundamentals, namely achieving a uniform modeling practice. With these findings, a new proposed methodology has been introduced, as well as a recommended plan for a widespread implementation of parametric modeling at Scania. Such implementation would allow for shorter lead-times, faster adaptation to changing conditions, and reduced development expenditures.
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