Thesis (MScEng)--Stellenbosch University, 2013. / ENGLISH ABSTRACT: This thesis documents the research conducted into the control of the feeder subsystem of a Reconfigurable Assembly System (RAS). The research was motivated by a new set of modern manufacturing requirements associated with an aggressive and dynamic global market. The motivation can be more specifically attributed to the need for selective automation, through the installation of reconfigurable systems, in the South African manufacturing industry. The objective of the research was to implement and evaluate Multi-Agent Systems (MASs) and IEC 61499 function block systems as potential control strategies for reconfigurable systems. The control strategies were implemented for the control of the feeder subsystem of an experimental RAS at Stellenbosch University. The subsystem's hardware consisted of a singulation unit with a machine vision camera, part magazines and a six DOF pick-'n-place robot. The structure of the control strategies is based on the ADACOR holonic reference architecture. The mapping of the subsystem holons to the structures of the control strategies is explained. The development and implementation of the control strategies, along with the accompanying lower level software, is described in detail. A system reconfigurability assessment was performed and the results are discussed. The assessment was performed at two levels – the Higher Level Control (HLC) (where the control strategies were implemented) and the low level control and hardware. The assessment was done through four reconfiguration experiments. The evaluation of the HLC was done through both quantitative and qualitative performance measures. The implications of the reconfiguration, involved in each of the respective experiments, on the low level software and hardware are discussed. The experimental results show that agent-based control adds more reconfigurability to the feeder subsystem than IEC 61499 function block control, and that agents have more advantages regarding customizability, convertibility and scalability than IEC 61499 function blocks. Also, the ability of agent-based control to implement reconfiguration changes during subsystem operation makes it more suitable to the case study application. / AFRIKAANSE OPSOMMING: Hierdie tesis dokumenteer die navorsing gedoen in die beheer van die voerder sub-stelsel vir 'n herkonfigureerbare monteringstelsel. Die navorsing was gemotiveer deur „n nuwe stel vereistes vir moderne vervaardiging wat met 'n aggresiewe en dinamiese globale mark geassosieer word. Die motivering kan meer spesifiek toegeskryf word aan die behoefte tot selektiewe outomatisasie, deur middel van die implimentering van herkonfigureerbare stelsels, in the Suid-Afrikaanse vervaardigingsnywerheid. Die doel van die navorsing is om multi-agent stelsels en IEC 61499 funksie-blok stelsels, as potensiële beheerstrategiëe vir herkonfigureerbare stelsels, te implementer en evalueer. Die beheerstrategiëe was geïmplementeer vir die voerder sub-stelsel van „n eksperimentele herkonfigureerbare monteringstelsel by Universiteit Stellenbosch. Die hardeware behels „n skeier-eenheid (singulation unit) met „n masjienvisie kamera, onderdeelmagasyne en „n ses-vryheidsgraad gearktikuleerde optel-en-plaas robot. Die struktuur van die beheerstrategiëe is gebaseer op die ADACOR holoniese verwysingsargitektuur. Die afbeelding van die sub-stelsel holons na die struktuur van die beheerstrategiëe word verduidelik. Die ontwikkeling en implementering van die beheerstrategiëe, asook die gepaardgaande laer-vlak programmatuur, word in detail beskryf. Die stelsel se herkonfigureerbaarheid was geassesseer en die resultate daarvan word bespreek. Die assessering was op twee vlakke gedoen – die hoër-vlak beheer (waar die beheerstrategiëe geimplementeer was) en die lae-vlak beheer en hardeware. Die assessering was gedoen deur middel van vier herkonfigurasie eksperimente. Die hoër-vlak beheer was geëvalueer deur beide kwalitatiewe en kwantitatiewe metings. Die implikasies van die herkonfigurasie, betrokke by die onderskeie eksperimente, op die lae-vlak beheer en hardeware word beskryf. Die eksperimentele resultate wys dat agent-baseerde beheer meer herkonfigureerbaarheid tot die voerder sub-stelsel toevoeg as IEC 61499 funksie-blok beheer. Dit is geïdentifiseer dat agente meer voordele inhou ten opsigte van aanpasbaarheid, skakelbaarheid en skaalbaarheid as IEC funksie-blokke. Agent-baseerde beheer laat ook toe dat herkonfigurasieveranderinge tydens sub-stelsel werking geïmplimenteer kan word – dus is dit meer geskik vir aanwending in die gevallestudie.

L'objectif de cette thèse s'inscrit dans la cadre général du développement d'une stratégie de contrôle intelligent distribué en robotique collective. En effet, dans un avenir proche, de nombreux robots vont progressivement intégrer notre environnent aussi bien dans les milieux industriel que domestique. L'objectif de ces robots sera de fournir, de manière autonome, des services aux êtres humains afin de leurs faciliter la vie quotidienne comme par exemple dans le cas de robots compagnons. Ces services pourront être le résultat du travail d'un robot ou bien la conséquence de la coopération de plusieurs robots homogènes et/ou hétérogènes regroupés au sein d'un réseau. Dans ce contexte, si les progrès technologiques permettent sans problème de communiquer et d'échanger des données entre deux agents artificiels distants, la conception de stratégies de contrôle permettant l'auto-organisation de plusieurs robots dans le but de réaliser une tâche précise est encore aujourd'hui un verrou scientifique important. Cette thèse a donc pour but de proposer des pistes pour élaborer des stratégies de contrôle intelligent pour des systèmes multi-robots dans le cadre plus particulier de la logistique industrielle. En effet, le domaine de logistique industrielle nécessite l'utilisation de nombreux robots mobiles comme par exemple des AGV (Automatic Guided Vehicles) pour transporter et stoker des marchandises. Dans ce contexte, nous pensons que le domaine de la logistique peut tirer bénéfice de l'utilisation de systèmes multi-robots. Dans un premier temps, cette thèse aborde donc la problématique de transport d'objet volumineux et encombrant par une formation de robot. Effectivement, il semble que la solution qui consiste à utiliser un ensemble de robots identiques pour transporter des charges de grandes envergures soit, d'une part, très intéressante d'un point de vue économique et, d'autre part, plus robuste et flexible d'un point vue technologique. Dans un deuxième temps, cette thèse aborde l'utilisation d'un réseau de robots hétérogènes qui sont capables de s'organiser afin de réaliser une tâche précise dans un milieu dynamique. Les travaux effectués dans le cadre de la présente thèse doctorale ont donc abouti à la proposition des stratégies viables de contrôle intelligent pour des systèmes multi-robots. Une étude d'application des concepts étudiés a été réalisée, implantée et validée dans le cadre plus particulier de la logistique industrielle. Elle a concerné d'abord le contexte d'un groupe multi-robots homogène, puis a été étendue au contexte d'un système multi-robots hétérogènes. Les points forts des travaux réalisés peuvent être résumés comme ceci :- Proposition, conception, réalisation et validation expérimentale d'une stratégie de contrôle adaptatif par l'apprentissage artificiel pour un robot non-holonomique. Quatre publications internationales ont valorisé cette partie des travaux.- Proposition, conception, réalisation et validation expérimentale d'une stratégie de contrôle hybridant la vision artificielle et l'apprentissage artificiel pour un groupe de robots homogènes. Deux publications internationales ont valorisé cette partie des travaux.- Proposition, conception, réalisation et validation expérimentale d'une stratégie de contrôle hybridant la vision artificielle et l'apprentissage artificiel pour un groupe de robots hétérogènes. Deux publications internationales ont valorisé cette partie des travaux. Il est pertinent de souligner que les travaux relatifs aux aspects précités ont été couronnés par le prix : ″Innovation Award 2011″ de Industrial Robot / In this thesis, it concentrated the multi robot team navigating in an unknown environment. In our multi robot team, there is a humanoid robot as a leader and a team of two-wheel nonholonomic robots which form a vertical formation. Besides, a top camera and a computer which is a supervisor are the auxiliary robots in the multi robot team. The main purpose of the thesis is to propose an online and an offline navigation strategy for the closed and open area respectively. The core of navigation strategies is the same and it included path planning part and control part. Both the two parts constructed on the virtual structure of the formation robot team. In the former part, it improved the path planning part by the reinforcement Q learning and the image processing to acknowledge the unknown environment. And it applied the Adaptive Neural Fuzzy Inference System (ANFIS) algorithm to control of both the single nonholonomic robot and formation robot team. Furthermore, the strategies are applied to the formation robot team and the multi robot team in both closed and open environment. Simulations and real experiments are provided in the detail in the thesis. The strong points of the contribution are :- Proposition, conception, realization and experimental validation of machine learning based adaptive control for a nonholonomic single robot (in a group of robots). Four international publications have valorized this part of the doctoral Works. - Proposition, conception, realization and experimental validation of an adaptive intelligent control strategy hybridizing Artificial vision and Machine Learning for a group of nonholonomic homogeneous robots. Two international publications have valorized this part of the doctoral Works.- Proposition, conception, realization and experimental validation of an adaptive intelligent control strategy hybridizing Artificial vision and Machine Learning for a group of heterogeneous robots. Two international publications have valorized this part of the doctoral Works. It is pertinent to emphasize the investigations relative to the above-mentioned works have been awarded by: ″Innovation Award 2011″ of Industrial Robot

A leishmaniose visceral zoonotica (LVZ) e uma das mais importantes doenc¸as parasitárias emergentes. Em particular, o Brasil é considerado um dos principais centros endêmicos para esta doença. Apesar da publicação de manuais de controle da leishmaniose visceral e dos investimentos aplicados na organizacão de serviços e no desenvolvimento de atividades preventivas e de controle, os vetores e os reservatórios em áreas urbanas são os maiores desafios para os programas de controle. Isto se deve (1) `a necessidade por melhor compreensão do comportamento do vetor no meio urbano; (2) `as dificuldades operacionais para realizar atividades em tempo suficiente para obter resultados de impacto; e (3) ao alto custo envolvido nessas atividades. O principal objetivo deste estudo foi elaborar um modelo de otimização para o controle da leishmaniose, baseado em 5 parâmetros de controle que correspondem `as seguintes estratégias: (I) controle vetorial, (II) eliminação de cães positivos, (III) uso de coleiras impregnadas com inseticida, (IV) vacinação canina e (V) tratamento canino. Este modelo foi construído a partir de um sistema composto por 17 equações diferenciais, sendo que 4 representam a dinâmica da doenc¸a sobre a população humana (humanos suscetíveis (xh), latentes (lh), clinicamente doentes (yh) e recuperados (zh)), 10 para a populacão de cães (cães suscetíveis (xd e xCd ), latentes (ld e lCd ), clinicamente doentes (yd e yCd ), recuperados (zd e zCd ) e vacinados (vd e vCd ), onde o índice C representa as categorias com a aplicação da coleira inseticida) e 3 para a população de vetores (mosquitos não-infectados (s1), infectados (mas não-infectivos) (s2), infectados e infectivos (s3)). Para a an´alise econômica dessas estratégias, foram estimados os custos de cada uma delas por cão (ou, no caso do controle vetorial, por casa tratada). Considerando a simulação sem a introdução das estratégias de controle, as densidades de equilíbrio endêmico para as categorias foram: xh = 0, 394, lh = 0, 0305, yh = 0, 00167, zh = 0, 574, xd = 0, 314, ld = 0, 165, yd = 0, 0163, zd = 0, 505, s1 = 0, 709, s2 = 0, 0858 e s3 = 0, 205. No estado de equilibrio endêmico, o número de reprodutibilidade basal foi estimado em R0 = 4, 50 e o n´umero diário de casos humanos notificados, em R = 3, 58 × 10-6/dia. Considerando a avaliação do impacto das estratégias de controle, o controle vetorial mostrou ser a estrat´egia que causa a diminuição mais rápida sobre o núumero diário de casos humanos notificados e, consequentemente, foi tambem a que mais reduz os custos m´edico-hospitalares. Entretanto, ´e a estratégia que exige o maior investimento. Por outro lado, a estrat´egia de eliminar cães positivos foi considerada a de menor custo. Dado que essas estratégias de controle atuam em pontos distintos na cadeia epidemiológica, o planejamento de um controle envolvendo a ação simultânea delas poderia não apenas apresentar resultados de controle mais interessantes, como tambem poderia otimizar ainda mais os investimentos sobre o controle da leishmaniose visceral / Zoonotic visceral leishmaniasis (ZVL) is one of the most important emerging parasitic diseases. Brazil, in particular, is considered one of the countries in which this disease is most endernic. Despite the publication of visceral leishmaniasis control guidelines and the investment in health services and controljpreventive activities, the vectors and reser- voirs in urban areas are the major challenge for those control programs. This is due to (1) the need for better comprehension regarding the vector behavior in the urban envi- ronment; (2) the operating difficulties in perforrning the activities in time to reach good results; and (3) the high cost of those activities. The main objective of this study was to elaborate an optirnization model for leishmaniasis control. This model is based on 5 con- trol parameters that correspond to the following strategies: (I) vector population control, (11) elirnination of positive dogs, (111) use of insecticide-impregnated dog collars, (IV) dog vaccination and (V) dog treatment. This model was elaborated using an equation system, composed of 17 differential equations, 4 of which represent the disease dynarnic on hu- man population (susceptible (Xh), latent (Ih), clinically ill (Yh) and recovered humans (Zft)), 10 for dog population (susceptible (Xd and xcd), latent (ld and Icd), clinically ill (Yd and Ycd), recovered (Zd and zcd) and vaccinated dogs (Vd and vcd), where C represents the categories using the insecticide-impregnated dog collars) and 3 for vector population (non-infected (SI), infected but not infective (S2), infected and infective sandflies (S3)). For econornic analysis of those control strategies, we estimated the cost of them per dog (in the case of vector control population, it was estimated per treated house). Regarding the nume- rical simulations without the control strategies, the endernic equilibrium densities were: Xh = 0.394, Ih = 0.0305, Yh = 0.00167, Zh = 0.574, Xd = 0.314, Id = 0.165, Yd = 0.0163, Zd = 0.505, SI = 0.709, S2 = 0.0858 and S3 = 0.205. In endernic equilibrium state, the basic reproduction number and the rate of reported human cases per day were estimated as 1%0 = 4.50 and R = 3.58 x 1O-6/day, respectively. Considering the impact evaluation of controI strategies, the vector population control was the strategy that resulted in a fas- ter decrease in the rate of human reported cases per day and, consequently, in the larger reduction of medical and hospital costs too. However, the investment (that is, the cost) of the vector population control was the highest one. On the other hand, the investment in elirninating positive dogs was considered the lowest one. Since those control strategies operate at different points within the epiderniological chain, the planning a control, while taking into account the simultaneous action of these strategies, could not only result in a more interesting control strategy, but could also improve the optirnization of investments on visceralleishmaniasis control

In robotic rehabilitation therapies, knowledge of human joint torques is important for patient safety, to provide a reliable data for clinical assessment and to increase control performance of the device, nevertheless, its measurement can be complex or have a highcost implementation. The most of techniques for torque estimation have been developed for upper limb robotic rehabilitation devices, in addition, they typically require detailed anthropometric and musculoskeletal models. In this dissertation is presented the ankle torque estimation for the Anklebot robot, the estimation uses an ankle/Anklebot dynamic model that consider the ankle joint angular displacement and velocity measurement, its mechanical impedance parameters are obtained through a second-order modeled mechanical impedance of the ankle and an identification of frictional and gravitational torques. Three approaches for the ankle torque estimation were proposed to be implemented in the Anklebot robot, the Generalized Momentum, the Kalman filter and finally a combination of both the above mentioned approaches. The validation of such approaches was developed first on a physical mockup configured to reproduce the human ankle joint movement, by assessing its performances, the Kalman filter approach was selected to be implemented on a voluntary subject. A set of experiments were performed considering the physical activity that the subject may realize when interacting with the Anklebot, the developed ankle torque estimation proved to be successful for passive torque and in most of the proposed scenarios where active torque is performed. / Em terapias de reabilitação robótica, o conhecimento dos torques da articulação humana é importante para a segurança do paciente, para fornecer dados confiáveis na avaliação clínica e aumentar o desempenho de controle do dispositivo, no entanto, sua medição pode ser complexa ou costoso de implementar. A maioria das técnicas de estimativa de torque tem sido desenvolvidas para dispositivos de reabilitação robótica de membros superiores, além disso, eles normalmente requerem modelos antropométricos e musculoesqueléticos detalhados. Nesta dissertação é apresentada a estimativa do torque do tornozelo no robô Anklebot, a estimação utiliza um modelo dinâmico tornozelo + Anklebot o qual considera a medição da posição e velocidade angular do tornozelo, os parametros de impedancia mecânica do tornozelo são obtidos por meio de um modelo simples de segunda ordem e são identificados os torques gravitacionais e de atrito. Três abordagens para a estimativa de torque de tornozelo foram propostas para serem implementadas, o momento generalizado, o filtro de Kalman e, finalmente, uma abordagem que combina tanto o momento generalizado e o filtro de Kalman. A validação de tais abordagens foi desenvolvida primeiro em um mock-up físico configurado para reproduzir o movimento articular do tornozelo humano, avaliando seus desempenhos. A segunda abordagem proposta foi selecionada para ser implementada em um usuário voluntário. Um conjunto de experimentos foi realizado considerando a atividade física que o sujeito pode realizar ao interagir com o Anklebot, a estimativa desenvolvida de torque de tornozelo demostrou ser bem sucedida para o torque passivo e na maioria dos cenários propostos onde o torque ativo é realizado.

A leishmaniose visceral zoonotica (LVZ) e uma das mais importantes doenc¸as parasitárias emergentes. Em particular, o Brasil é considerado um dos principais centros endêmicos para esta doença. Apesar da publicação de manuais de controle da leishmaniose visceral e dos investimentos aplicados na organizacão de serviços e no desenvolvimento de atividades preventivas e de controle, os vetores e os reservatórios em áreas urbanas são os maiores desafios para os programas de controle. Isto se deve (1) `a necessidade por melhor compreensão do comportamento do vetor no meio urbano; (2) `as dificuldades operacionais para realizar atividades em tempo suficiente para obter resultados de impacto; e (3) ao alto custo envolvido nessas atividades. O principal objetivo deste estudo foi elaborar um modelo de otimização para o controle da leishmaniose, baseado em 5 parâmetros de controle que correspondem `as seguintes estratégias: (I) controle vetorial, (II) eliminação de cães positivos, (III) uso de coleiras impregnadas com inseticida, (IV) vacinação canina e (V) tratamento canino. Este modelo foi construído a partir de um sistema composto por 17 equações diferenciais, sendo que 4 representam a dinâmica da doenc¸a sobre a população humana (humanos suscetíveis (xh), latentes (lh), clinicamente doentes (yh) e recuperados (zh)), 10 para a populacão de cães (cães suscetíveis (xd e xCd ), latentes (ld e lCd ), clinicamente doentes (yd e yCd ), recuperados (zd e zCd ) e vacinados (vd e vCd ), onde o índice C representa as categorias com a aplicação da coleira inseticida) e 3 para a população de vetores (mosquitos não-infectados (s1), infectados (mas não-infectivos) (s2), infectados e infectivos (s3)). Para a an´alise econômica dessas estratégias, foram estimados os custos de cada uma delas por cão (ou, no caso do controle vetorial, por casa tratada). Considerando a simulação sem a introdução das estratégias de controle, as densidades de equilíbrio endêmico para as categorias foram: xh = 0, 394, lh = 0, 0305, yh = 0, 00167, zh = 0, 574, xd = 0, 314, ld = 0, 165, yd = 0, 0163, zd = 0, 505, s1 = 0, 709, s2 = 0, 0858 e s3 = 0, 205. No estado de equilibrio endêmico, o número de reprodutibilidade basal foi estimado em R0 = 4, 50 e o n´umero diário de casos humanos notificados, em R = 3, 58 × 10-6/dia. Considerando a avaliação do impacto das estratégias de controle, o controle vetorial mostrou ser a estrat´egia que causa a diminuição mais rápida sobre o núumero diário de casos humanos notificados e, consequentemente, foi tambem a que mais reduz os custos m´edico-hospitalares. Entretanto, ´e a estratégia que exige o maior investimento. Por outro lado, a estrat´egia de eliminar cães positivos foi considerada a de menor custo. Dado que essas estratégias de controle atuam em pontos distintos na cadeia epidemiológica, o planejamento de um controle envolvendo a ação simultânea delas poderia não apenas apresentar resultados de controle mais interessantes, como tambem poderia otimizar ainda mais os investimentos sobre o controle da leishmaniose visceral / Zoonotic visceral leishmaniasis (ZVL) is one of the most important emerging parasitic diseases. Brazil, in particular, is considered one of the countries in which this disease is most endernic. Despite the publication of visceral leishmaniasis control guidelines and the investment in health services and controljpreventive activities, the vectors and reser- voirs in urban areas are the major challenge for those control programs. This is due to (1) the need for better comprehension regarding the vector behavior in the urban envi- ronment; (2) the operating difficulties in perforrning the activities in time to reach good results; and (3) the high cost of those activities. The main objective of this study was to elaborate an optirnization model for leishmaniasis control. This model is based on 5 con- trol parameters that correspond to the following strategies: (I) vector population control, (11) elirnination of positive dogs, (111) use of insecticide-impregnated dog collars, (IV) dog vaccination and (V) dog treatment. This model was elaborated using an equation system, composed of 17 differential equations, 4 of which represent the disease dynarnic on hu- man population (susceptible (Xh), latent (Ih), clinically ill (Yh) and recovered humans (Zft)), 10 for dog population (susceptible (Xd and xcd), latent (ld and Icd), clinically ill (Yd and Ycd), recovered (Zd and zcd) and vaccinated dogs (Vd and vcd), where C represents the categories using the insecticide-impregnated dog collars) and 3 for vector population (non-infected (SI), infected but not infective (S2), infected and infective sandflies (S3)). For econornic analysis of those control strategies, we estimated the cost of them per dog (in the case of vector control population, it was estimated per treated house). Regarding the nume- rical simulations without the control strategies, the endernic equilibrium densities were: Xh = 0.394, Ih = 0.0305, Yh = 0.00167, Zh = 0.574, Xd = 0.314, Id = 0.165, Yd = 0.0163, Zd = 0.505, SI = 0.709, S2 = 0.0858 and S3 = 0.205. In endernic equilibrium state, the basic reproduction number and the rate of reported human cases per day were estimated as 1%0 = 4.50 and R = 3.58 x 1O-6/day, respectively. Considering the impact evaluation of controI strategies, the vector population control was the strategy that resulted in a fas- ter decrease in the rate of human reported cases per day and, consequently, in the larger reduction of medical and hospital costs too. However, the investment (that is, the cost) of the vector population control was the highest one. On the other hand, the investment in elirninating positive dogs was considered the lowest one. Since those control strategies operate at different points within the epiderniological chain, the planning a control, while taking into account the simultaneous action of these strategies, could not only result in a more interesting control strategy, but could also improve the optirnization of investments on visceralleishmaniasis control

This thesis focuses on one important component of the energy system - the window. Windows are installed in buildings mainly to create visual contact with the surroundings and to let in daylight, and should also be heat and sound insulating. This thesis covers four important aspects of windows: antireflection and switchable coatings, energy simulations and optical measurements. Energy simulations have been used to compare different windows and also to estimate the performance of smart or switchable windows, whose transmittance can be regulated. The results from this thesis show the potential of the emerging technology of smart windows, not only from a daylight and an energy perspective, but also for comfort and well-being. The importance of a well functioning control system for such windows, is pointed out. To fulfill all requirements of modern windows, they often have two or more panes. Each glass surface leads to reflection of light and therefore less daylight is transmitted. It is therefore of interest to find ways to increase the transmittance. In this thesis antireflection coatings, similar to those found on eye-glasses and LCD screens, have been investigated. For large area applications such as windows, it is necessary to use techniques which can easily be adapted to large scale manufacturing at low cost. Such a technique is dip-coating in a sol-gel of porous silica. Antireflection coatings have been deposited on glass and plastic materials to study both visual and energy performance and it has been shown that antireflection coatings increase the transmittance of windows without negatively affecting the thermal insulation and the energy efficiency. Optical measurements are important for quantifying product properties for comparisons and evaluations. It is important that new measurement routines are simple and applicable to standard commercial instruments. Different systematic error sources for optical measurements of patterned light diffusing samples using spectrophotometers with integrating spheres have been investigated and some suggestions are made for how to avoid such errors.

Until the developments in computer technology, linear test administrations within classical test theory framework is mostly used in testing practices. These tests contain a set of predefined items in a large range of difficulty values for collecting information from students at various ability levels. However, placing very easy and very difficult items in the same test not only cause wasting time and effort but also introduces possible extraneous variables into the measurement process such as possibility of guessing, chance of careless errors induced by boredom or frustration. Instead of administering a linear test there is another option that adapts the difficulty of test according to the ability level of examinees which is named as computerized adaptive test. Computerized adaptive tests use item response theory as a measurement framework and have algorithms responsible for item selection, ability estimation, starting rule and test termination. The present study aims to determine the applicability of computerized adaptive testing (CAT) to Turkish Pupil Monitoring System&rsquo / s (PMS) mathematics assessments. Therefore, live CAT study using only multiple choice items is designed to investigate whether to obtain comparable ability estimations. Afterwards, a Monte Carlo simulation study and a Post-hoc simulation study are designed to determine the optimum CAT algorithm for Turkish PMS mathematics assessments. In the simulation studies, both multiple-choice and open-ended items are used and different scenarios are tested regarding various starting rules, termination criterion, ability estimation methods and existence of exposure/content controls. The results of the study indicate that using Weighted Maximum Likelihood (WML) ability estimation method, easy initial item difficulty as starting rule and a fixed test reliability termination criterion (0.30 standard error as termination rule) gives the optimum CAT algorithm for Turkish PMS mathematics assessment. Additionally, item exposure and content control strategies have a positive impact on providing comparable ability estimations.

No description available.

La topologie modulaire multiniveaux est une structure d'électronique de puissance construite par la mise en série de sous-modules identiques, composés chacun d'une cellule de commutation et d'un condensateur. Un tel système de conversion pouvant comporter un grand nombre de cellules permet d'augmenter le rendement global et la qualité des signaux en sortie. De plus, il permet d'utiliser des composants basse tension présentant un meilleur comportement dynamique et un rapport qualité-prix bien supérieur aux composants moyenne tension. Il permet également, par rapport aux structures conventionnelles, une grande souplesse pour la conception et la fabrication du fait de son aspect modulaire, tout en s'affranchissant d'un transformateur volumineux et onéreux en entrée. Comparé aux autres types de topologies, avantageuses avec un nombre limité de niveaux, le convertisseur modulaire multiniveaux semble être mieux adapté aux applications en moyenne et haute tensions, qui sont tributaires de l'association des composants de puissance. Néanmoins, pour la variation de vitesse, un certain nombre de défis technologiques ont été mis en évidence, compte tenu du fonctionnement particulier de l'onduleur modulaire multiniveaux et des contraintes imposées par l'opération en très basse fréquence. En le fonctionnement normal, la forme d'onde des courants internes, contrairement aux autres types de topologies, n'est pas symétrique en raison de la distribution du courant direct dans chaque bras. Cela entraîne une disparité significative en termes de dissipation thermique parmi les interrupteurs constituant un sous-module. Avec le choix d'une technologie de packaging 3D, la possibilité de refroidir les puces semi-conductrices en double-face offre une meilleure capacité de refroidissement et une nouvelle perspective de conception des modules pour cette application. Un nouveau concept de report de puces est présenté et un prototype de tel module a été réalisé, modélisé et caractérisé. Il permet d'équilibrer globalement la chaleur dissipée par les puces sur les deux faces du module, problème inhérent à l'emploi de structure 3D. Conjugué à la mutualisation d'un interrupteur par deux puces en parallèle, la nouvelle architecture a aussi pour objectif d'équilibrer le refroidissement double-face dans le temps. En effet, pour les opérations en basse fréquence, les interrupteurs fonctionnent en régime instationnaire avec de forte variation de température, il n'est donc plus possible de compenser les effets thermomécaniques de chaque composant l'un par l'autre, comme en régime stationnaire et avec un positionnement planaire des puces. D'autre part, d'un point de vu systémique, la stratégie de commande et le dimensionnement des condensateurs flottants de l'onduleur modulaire multiniveaux sont deux aspects intimement liés. En effet, les condensateurs flottants sont le siège d'ondulations de tension de très forte amplitude. Cela a pour effet de déstabiliser l'onduleur, voire de provoquer la destruction des composants en atteignant des niveaux de tension trop élevés. Ainsi, des contrôleurs judicieusement conçus permettent de réduire les ondulations indésirables, et a fortiori, d'embarquer des capacités moins importantes dans le système, tant que ces dernières sont inversement proportionnelles à l'ondulation de la tension. Afin d'avoir une compréhension approfondie sur les dynamiques régissant le convertisseur modulaire multiniveaux, un modèle dynamique global basé sur la représentation d'état a été établi. Bien que cette représentation soit limitée à l'harmonique 2 des grandeurs caractéristiques, elle permet une fidèle interprétation du mécanisme de conversion sans passer par des modèles énergétiques bien plus complexes à exploiter, et de proposer des lois de commande montrant leur efficacité notamment autour de la fréquence nominale. Cela a été vérifié sur une maquette de puissance réalisée dans le cadre de cette thèse. / Multilevel modular topology converts energy between two direct and alternative endings. This structure is constructed by the series connection of identical sub-modules, composed of a switching cell and a floating capacitor, and with arm inductors. Such a conversion system may reach a large number of levels increases the overall efficiency and quality of the output signals. In addition, it allows the use of low voltage components with better dynamics and cost effectiveness above the high voltage components. It also allows flexibility in the work of design and manufacture due to its modularity, while avoiding a bulky and expensive input transformer, regarding the conventional technology. Compared with other types of topologies, advantageous with a limited number of levels, the modular multilevel converter seems to be more suited for medium and high voltage applications, which are dependent on the association of power components. However, for variable speed drive application, a certain number of technological challenges have been highlighted, given the specific functional characteristics of the modular multilevel inverter and the constraints imposed by the very low frequency operation. On the one hand, for the normal operation of a multilevel modular converter, the waveform of the internal currents, in contrast to other types of topologies, is not symmetrical due to the distribution of the direct current in each phase leg. This may entail a significant disparity in terms of heat dissipation within the switching devices constituting a sub-module. Therefore, the problem of thermal management of active components is emphasized in the use of a modular multilevel converter. With the choice of a 3D packaging technology, interconnection by bumps, the ability to cool the semiconductor chips through the both sides of a module offers better cooling effects and a new perspective to design the power module for the studied structure. The concept of laying chips on both the two substrates of module without facing each other provides overall balanced dissipation in the space and permit to overcome the unbalanced heat distribution induced by bumps. Combined with the sharing of a switch by two chips in parallel, the proposal of the new architecture for 3D power module also aims to balance the double-sided cooling in the time range. Indeed, for the very low frequency operation, the switches operate in unsteady state where each switch has its own thermal behavior, it is no longer possible to compensate the thermo-mechanical constraints over each component with the help of the others, as in steady state and with a planar chips positioning scheme. On the other hand, from a systemic point of view, the control strategy and the dimensioning of floating capacitors of modular multilevel inverter are two interrelated aspects. Because the floating capacitors, having the role of energy sources, are loaded / unloaded through the modulation period, which causes very high voltage ripples across those capacitors with a very low frequency. This will destabilize the inverter and even provoke the destruction of components by approaching too high voltage levels. Thus, wisely designed controllers reduce unwanted ripples and, furthermore, allow embarking much smaller capacity in the system, as they are inversely proportional to the voltage ripple. In order to have a thorough understanding on the dynamics governing the modular multilevel converter, a comprehensive dynamic model based on state-space representation was established. Although this representation is limited to the second harmonic of characteristic variable, it allows a faithful interpretation of the conversion mechanism without using energy models, more complex to operate, and control laws can also be proposed and their effectiveness around the nominal frequency has been underlined. Concerning the very low frequency operations, another solution has been proposed and is ongoing patent pending.

Le raccordement des systèmes PV ou des systèmes de recharge des VE au réseau peut avoir des impacts sur le fonctionnement du réseau:• Variation de tension• Déséquilibre de tension entre phases• Impact du caractère intermittent de la ressource solaire• Impact du caractère aléatoire des systèmes de recharge des VE• Injection d'harmoniques de découpage au réseau si les onduleurs ne sont pas munis de filtres efficaces• Interactions harmoniques entre onduleurs à travers le réseau• Injection de courant continu au réseau• Courants de fuite• Impact sur les pertes• Impact sur la congestion en cas de recharge des VE…C'est pourquoi, l'objectif de cette thèse est de développer les stratégies de contrôles/commandes intelligents pour les onduleurs PV et les systèmes de recharge des VE de afin de- réduire le coût total du système PV ou du système de recharge,- augmenter la performance des onduleurs PV raccordés au réseau- augmenter le taux de pénétration des systèmes PV ou de recharge des VE- assurer la continuité de service- participer au réglage de tension et de fréquence du réseau- contribuer à la stabiliser le réseau en cas nécessaire- améliorer la qualité de l'énergie- éviter les congestions…Dans le cadre du travail, la définition des services apportés par systèmes PV ou les systèmes de la recharge des VE est nécessaire. Ces services que les systèmes PV ou les systèmes de recharges qui peuvent apporter au réseau, sont élaborés dans un but prospectif : respect du plan de tension par régulation, absorption/production de puissance réactive selon le besoin, tenue aux creux de tension, amélioration de la qualité.Les études concernées :- Etude des interactions (impacts) entre les onduleurs PV et le réseau- Etude des interactions (impacts) entre les onduleurs de la recharge des VE et le réseau- Définition des services apportés par ces systèmes- Développement et modélisation d'un onduleur bidirectionnel- Développement des systèmes de contrôle/commande intelligent pour ces services:o Réglage de tension. Gestion de congestion. Amélioration de la qualité (ex : harmoniques). Capacité de tenue aux creux de tension. / The connection of PV systems or EV charging systems may impact on the operation of the electrical network:• Voltage variation• Voltage unbalance between phases• Impact of the intermittent nature of the solar resource• Impact of the random nature of EV charging systems• Harmonic injection in the network• DC injection network• Leakage currents• Impact on loss• Impact on congestion in case of EV charging ...Therefore, the objective of this thesis is to develop strategies to control / intelligent controls for PV inverters and charging systems for EVs to- Reduce the total cost of the PV system or charging system,- Increase the performance of PV inverters connected to the network- Increase the penetration of PV or EV charging- Ensure continuity of service- Participate in the regulation of grid voltage and grid frequency- Contribute to stabilize the grid- Improving the quality of energy- Avoid congestions...As part of the work, the definition of services provided by PV systems or EV charging systems is required. These services PV systems or systems that can provide to the network, are developed in a prospective: regulation of the voltage plan, absorption / reactive power as needed, withstand voltage dips, improving quality. Studies concerned:- Study of interactions (impacts) between PV inverters and network- Study of interactions (impacts) between the inverters and EV charging network- Definition of the services provided by these systems- Development and modeling of a bidirectional inverter- Development of control systems / intelligent control for these services: Voltatge controlo Management of congestiono Improved quality (eg harmonics). Ability to ride-through voltage dips.