Animal communication transmits information using different sensory signals that have particular purposes (e.g. courtship, territorial defense, maintaining groups together and minimizing predation) and are susceptible to habitat pressures (Sensory Drive Hypothesis - SDH). In birds, some studies on acoustic and visual signals showed that song structure is associated with sound transmission capacity in different habitats and some plumage features (e.g. color, brightness and pattern) seem to vary according to light conditions of the environment. In addition to habitat effects, other factors such as energetic limits, predation, and parasitism risk can limit the investment in more than one type of sensory signal. Due to this high cost, it was proposed the existence of an evolutionary trade-off between the different types of sensory signals termed Transfer (TH) or Trade-off hypothesis. Few studies that have tested the TH in birds showed contrasting results, being corroborated only in two studies. Also, there is a low in the number of studies that have considered habitat conditions as covariates (SDH). Here, we assess the TH between acoustic and visual signals, while simultaneously considering potential effects of habitat conditions (SDH) in a diverse group of Neotropical suboscine birds, commonly known as antbirds (Thamnophilidae). Specifically, we integrated a genome-scale phylogeny of the tribe Formicivorini (36 species) with vocal, plumage, ecological, and behavioral data within a phylogenetic comparative framework to simultaneously test the TH and SDH while assessing the influence of mixed-species flocking foraging behavior on the structural diversity of acoustic and visual signals. Whereas in both sexes we found significant trade-offs between some plumage and vocal traits (e.g. dorsal luminance versus frequency slope), providing support for the TH, we found a non-significant opposite trend between plumage and vocal sexual dimorphism. All these relationships are influenced by habitat conditions and behavioral traits as covariates, corroborating the SDH and mixed-species flocking behavior influence in the evolution of visual and acoustic signals / A comunicação animal transmite informações usando diferentes tipos de sinais sensoriais que possuem propósitos específicos (e.g. cortejo, defesa territorial, manutenção de grupos unidos e minimização da predação) e estão suscetíveis a pressões do habitat (Hipótese de Condução Sensorial - HCS). Em aves, alguns estudos de sinais acústicos e visuais demonstraram que a estrutura do canto está associada com a capacidade de transmissão do som em diferentes habitats e alguns aspectos de plumagem (e.g. coloração, brilho e padrão) parecem variar de acordo com as condições de iluminação do ambiente. Além dos efeitos de habitat, outros fatores como limitação energética, risco de predação e de parasitismo podem limitar o investimento em mais de um tipo de sinal sensorial. Devido a esse alto custo, foi proposta a existência de uma demanda conflitante (trade-off) evolutiva entre os diferentes tipos de sinais sensoriais denominada Hipótese de Transferência (HT) ou de \"Trade-off\". Os poucos estudos que testaram a HT em aves apresentaram resultados contrastantes, sendo corroborada apenas em dois trabalhos. Além disso, há uma baixa quantidade de trabalhos que consideraram as condições de habitat como covariáveis. Assim, nós avaliamos a HT entre os sinais acústicos e visuais, considerando simultaneamente os efeitos potenciais das condições de habitat (HCS) em um diverso grupo de aves subóscines neotropicais, comumente conhecidas como papa-formigas (Thamnophilidae). Especificamente, nós integramos a filogenia em escala genômica da tribo Formicivorini (36 espécies) com dados vocais, de plumagem, ecológicos e comportamentais utilizando uma abordagem comparativa filogenética para testar simultaneamente a HT, a HCS e também considerando a influência do comportamento de formação de bandos mistos na diversidade da estrutura dos sinais acústicos e visuais. Enquanto que demandas conflitantes significativas entre algumas medidas de plumagem e de canto foram encontradas em ambos os sexos (e.g. luminância dorsal contra declive de frequência) corroborando a HT, uma tendência oposta não significativa foi encontrada entre o dimorfismo sexual de plumagem e canto. Todas essas relações são influenciadas por condições de habitat e comportamento como covariáveis, corroborando a HCS e a influência do comportamento de bandos mistos na evolução da estrutura dos sinais acústicos e visuais

In industry, adjustable speed drives (ASDs) are widely employed in driving AC motors for variable speed applications due to the high performance and high energy efficiency obtained in such systems. However, ASDs have an impact on the power quality and utilisation of AC power feeds by injecting current harmonics and causing resonances, additional losses, and voltage distortion at the point of common coupling. Due to these problems, electric power utilities have established stringent rules and regulations to limit the effects of this distortion. As a result, efficient, reliable, and economical harmonic mitigation techniques must now be implemented in practical systems to achieve compliance at reasonable cost. A variety of techniques exist to control the harmonic current injected by ASDs, and allow three-phase AC-line-connected medium-power systems to meet stringent power quality standards. Of these, the broadband harmonic passive filter deserves special attention because of its good harmonic mitigation and reactive power compensation abilities, and low cost. It is also relatively free from harmonic resonance problems, has relatively simple structural complexity and involves considerably less engineering effort when compared to systems of single tuned shunt passive filters or active filters and active rectifier solutions. In this thesis, passive broadband harmonic filters are investigated. In particular, the improved broadband filter (IBF) which has superior overall performance and examples of its application are increasing rapidly. During this research project, the IBF operating principle is reviewed and its design principles are established. As the main disadvantage of most passive harmonic filters is the large-sized components, the first proposed design attempts to optimize the size of the filter components (L and C) utilized in the existing IBF topology. The second proposed design attempts to optimize the number and then the size of filter components resulting in an Advanced Broadband passive Filter (ABF) novel structure. The proposed design methods are based on frequency domain modelling of the system and then using a genetic algorithm optimization technique to search for optimal filter component values. The results obtained are compared with the results of a linear searching approach. The measured performance of the optimal filter designs (IBF and ABF) is evaluated under different loading conditions with typical levels of background voltage distortion. This involves assessing input current total harmonic distortion, input power factor, rectifier voltage regulation, efficiency, size and cost. The potential resonance problem is addressed and the influence of voltage imbalance on performance is investigated. The assessment is based on analysis, computer simulations and experimental results. The measured performance is compared to various typical passive harmonic filters for three-phase diode rectifier front-end type adjustable speed drives. Finally, the broadband filter design’s effectiveness and performance are evaluated by involving them in a standard IEEE distribution network operating under different penetration levels of connected nonlinear total loads (ASD system). The study is conducted via detailed modelling of the distribution network and the linked nonlinear loads using computer simulations.

Le développement de l’hypermobilité dans les territoires périurbains et ruraux situés à l’ombre des villes moyennes bretonnes génère de nouveaux besoins de la part des consommateurs en matière de réalisations d’achats. Les commerçants, en premier lieu la grande distribution qui se développe dans ces espaces, vont donc essayer d’apporter une réponse à ces demandes. La tendance y est donc à la transformation des supermarchés en petits hypermarchés dans les périphéries des principales localités et à la diffusion des drives aux principaux carrefours. Cet essor du commerce de transit favorisé par les politiques des communes et de leurs intercommunalités en matière de créations de zones commerciales périphériques contribue à fragiliser encore plus les magasins des centres des petites villes et des bourgs déjà pénalisés par leurs positions géographiques et le manque d’innovation de leurs gérants. Les pouvoirs publics vont donc être confrontés à des problématiques de désertification commerciale. Dans les petites villes les réponses s’effectueront par la mise en place de politiques contractuelles entre la Municipalité, l’intercommunalité, la Région voire, dans des cas plus exceptionnels, l’Etat. Confrontés au mille-feuilles administratif, les autres communes ne bénéficieront bien souvent d’aucune aide lors de la réalisation de leurs actions. Ainsi, dans les gros bourgs, ce sont des opérations menées en régie qui permettent, dans les couronnes les plus rurales, de maintenir un appareil commercial composé du trinôme café – boulangerie – supérette, ou à proximité du pôle urbain de le développer en y permettant l’implantation de nouveaux magasins. Dans les communes les plus rurales, plus isolées mais aussi moins peuplées, les Muncipalités, parfois aidées de citoyens – consommateurs vont œuvrer pour la sauvegarde du dernier bar du bourg grâce à la création de multiservices communaux. / Periurban territories are subject twice to the decline of rural territories and to a metropolitan area spatial growth in connection with the development of mobility. Consequently they are experiencing a significant change in their purchasing practices and in their commercial equipment. Historical shopping centers are disappeared in favor of new stores more urbans and more connected. Among them the drive in shops who set themselves up along the main roads and their intersections. Nevertheless institutional or alternative dynamics are also at the origin of the creation of new more “traditional” stores.

La commande prédictive de type Model Predictive Control (MPC) s’est imposée au fil du temps dans de nombreux domaines industriels. Elle permet en effet d’optimiser avec succès les performances du système contrôlé tout en respectant de nombreuses contraintes propres à l’application visée. Cependant, l’utilisation de la commande MPC dans les domaines de la commande de moteurs et de générateurs demeure problématique. En effet, ces applications à forte dynamique imposent de choisir de faibles périodes d’échantillonnage, or, ce type d’algorithme demande de résoudre pour chaque période d’échantillonnage un problème d’optimisation complexe. Cette difficulté est renforcée car le champ applicatif visé portant sur les applications embarquées aéronautiques où la vitesse de base des machines électriques est très élevée, de même que leur fréquence d’alimentation. De plus, du fait que les systèmes étudiés sont embarqués, il est également très important de minimiser les pertes énergétiques de l’ensemble convertisseur-machine. Dans ce contexte la commande prédictive par approche MPC peut être d’un grand intérêt. De plus, ce type d’application intègre des contraintes supplémentaires liées à l’environnement sévère dans lequel évoluent ces systèmes, contraintes additionnelles de fiabilité qu’il faut bien sûr ajouter dans l’algorithme de commande prédictif. La conséquence immédiate sera de renforcer la complexité des algorithmes et donc rendre plus difficile l’implantation en temps réel. Cependant, les gains attendus en termes de performance et de fiabilité sont importants. Le sujet proposé demande ainsi dans une première partie, de synthétiser une loi de commande prédictive d’un actionneur synchrone aéronautique. Une mission type sera choisie et l’optimisation portera à la fois sur le niveau des performances du contrôle que la minimisation de la dépense énergétique. Par ailleurs, une étude de robustesse sera menée qui prendra en compte l’impact de l’environnement de l’actionneur. L’aspect robustesse sera ainsi intégré à l’étude de la commande. La seconde partie du travail portera sur le portage de l’algorithme sur cible FPGA. Une attention toute particulière sera apportée à la minimisation du temps de calcul sans détérioration des performances, le tout sous contrainte de place. Il faudra privilégier une architecture de type Système-sur-Puce qui allie la flexibilité d’un ou plusieurs cœurs processeurs et de modules matériels dédiés à l’accélération de certaines parties critiques du traitement. / Nowadays, Model Predictive Control (MPC) has emerged in many industrial fields. It allows the optimization of the controlled drive performances while respecting a number of constraints specific to the application. However, the use of MPC in the fields of motors and generators control remains problematic. Indeed, these highly dynamic applications require small sampling periods. However, these types of algorithms necessitate the resolution of complex optimization problems at each sampling period. These difficulties are reinforced in our case as the chosen field is the aeronautical embedded applications where the drive speed, as well as the frequency, is important. In addition, as the systems are embedded ones, it is important to minimize the overall energy losses of the inverter-drive system. In this context, the Model Predictive Control can be of great interest. Moreover, this type of applications integrates additional constraints related to the harsh environment in which the systems evolve, such as the reliability, which must be added in the predictive control algorithm. The immediate consequence of these constraints results in an increase of the complexity of the algorithms and therefore it becomes more difficult to implement in real time. However, the expected gains in performance and reliability are important. The proposed subject requires in the first part, to synthesize a predictive control law of an aeronautical synchronous drive. A typical mission will be selected and the optimization will be performed on both the performance level of the control and the minimization of the energy cost. Furthermore, a robustness study is to be conducted that takes into account the environmental impact of the motor drive. The second part will be on the implementation of the algorithm on FPGA target. Particular attention will be paid to minimizing the computational time without any degradation in the performances. Focus will be upon architectures of the type System-on-chip (SoC) that combines the flexibility of one or more processor cores and dedicated hardware modules for accelerating critical parts of the treatment.

Wind energy has been the fastest emerging renewable energy source over the last decade. The overriding provisos to minimise greenhouse emissions and increasing concerns regarding energy security have been the major inducements for many countries to make a resolute transition to new and non-conventional power sources. Direct-drive systems for wind turbines are potentially a more reliable alternative to gearbox driven systems. Gearboxes are liable to significant accumulated fatigue torque loading with relatively high maintenance costs. It is with this in mind that the primary focus of this research is on direct-drive wind turbines. Generators in direct-drive wind turbines tend to be of large diameter and heavier due to the support structure required to maintain as small air-gap as possible between the stationary and rotating parts of the generator. Permanent magnet generators (PMGs) are the most common type to be used within direct-drive wind turbines nowadays. Generators and other drive-train components in wind turbines experience significant varying loads, which may lead to a bearing failure. These varying loads can lead to misalignment within the drivetrain producing eccentricity between the generator rotor and stator. Rotor eccentricity generates a magnetic force referred to as Unbalanced Magnetic Pull (UMP). The induced UMP for the same rotor eccentricity is much higher in PMGs than induction generators because of the higher permanent magnet magnetic field. UMP is an important issue requiring further research. A part of this study provides a more detailed treatment of UMP under varying rotor eccentricity regimes for various permanent magnet machine topologies. The effect of UMP in direct-drive PMGs on the lifetime of the main bearing is a topic that requires more research aimed at proposing design improvements and solutions. The hope being that the availability of such solutions can be applied to practical reductions in operating costs. In brief, identification of the root causes of failure and impacts on component lifetime remain a subject of research. Establishing analytical tools for studying the impact of UMP on component lifetime in direct drive wind turbines and identifying the prospects for air gap winding machines using single bearing configuration are the two key areas for further research. Firstly, this research aims to establish the relationship between bearing forces and different types of eccentricities and UMP in direct drive machines. It is intended to use such models for predicting bearing wear and fatigue. Secondly, this research aims to establish the analytical tools for studying static, dynamic and tilting eccentricity in air-gap winding direct drive generators. Such tools are used to increase the understanding of the dynamics of direct drive PM generators. The final step of this study is using a multi-body simulation software (SIMPACK) to initiate investigations and comparison by providing assessments of electromagnetic interaction and internal drive-train loading for four possible designs for a proposed 5MW direct-drive wind turbine in response to the loads normally seen by a wind turbine. The four designs include: (a) iron-cored PM direct-drive generator supported by two main bearings, (b) airgap winding PM direct-drive generator supported by two main bearings, (c) iron-cored PM direct-drive generator supported by a single main bearing, (d) airgap winding PM direct-drive generator supported by a single main bearing. An aero-elastic simulation code (HAWC2) is used to extract the hub loads for different wind speeds corresponding to the normal operation of the wind turbine. The dynamic eccentricity and its influence on the electromagnetic interaction and consequential effects on bearing loading for all four designs is examined to determine the most optimal support structural configuration for a direct-drive system. In summary, the main aim of this thesis is studying the effect of different types of rotor eccentricities in different types of direct drive PMGs on the main bearing arrangements. The results show that static rotor eccentricity has the maximum impact compared to the other types of eccentricities. The main result of an eccentricity is the induced UMP which applies directly as an extra force on the bearings. The influence of UMP on bearing wear is studied. This influence is found to be significant in PM machines and should be considered when designing the bearing stiffness. A 20% static rotor eccentricity in a PM machine is found to induce an UMP that roughly equals third the total weight of the machine. A single bearing design for a direct-drive wind turbine is proposed and compared with a conventional two-bearing design. The results show that the Iron-cored PM direct-drive generator supported by two main bearings design and airgap winding PM direct-drive generator supported by a single main bearing design have advantages over the other two designs in this study.

A presente dissertação inscreve-se no campo das conexões entre a psicanálise e a educação e tem como objetivo problematizar o voto pedagógico de prever, controlar e justificar o que (não) se passa entre adultos e crianças. Para tanto, buscamos na obra de Freud uma rede de conceitos capaz de circunscrever aquilo que insiste irredutivelmente no psiquismo e que resiste às investidas ortopédicas que almejam obter supostos indivíduos \"vencedores, felizes e saudáveis\", \"plenamente desenvolvidos\". Dentre as noções da psicanálise que se arriscam a nomear isso que é inominável, elegemos o infantil como fio condutor de nosso trabalho. Este conceito funciona como um operador que nos guia através de uma investigação a respeito dos (des)encontros que acontecem em uma situação educativa, instigando também uma reflexão crítica a respeito das pretensões (psico)pedagógicas de eliminar qualquer inadequação ou desajuste. Na teoria psicanalítica, o infantil relaciona-se com a sexualidade, com o desejo e com a neurose, além de outras noções fundamentais introduzidas por Freud. Trata-se de um \"resto\" não simbolizado resultante de uma situação traumática na qual o infans experimenta um ameaçador excesso de energia pulsional, com o qual seu psiquismo ainda em formação não é capaz de lidar sem a intervenção de um outro, a mãe. São os traços mnêmicos desse desamparo que permanecem ativos no inconsciente, causando efeitos além do princípio do prazer. Nesse sentido, o que a epistemologia psicanalítica pode provocar é um questionamento das ilusões que, alimentadas por princípios (psico)pedagógicos, aspiram à supressão total dos conflitos próprios de uma ex-istência marcada pela insistência do infantil. Por outro lado, a psicanálise permite que compreendamos certas transformações significantes que a linguagem pode operar no sujeito do desejo, inconsciente, sexual e infantil, esclarecendo os efeitos que as palavras endereçadas por um adulto a uma criança podem ter, ainda que estes sejam sempre impassíveis de serem antecipados pelos planejamentos pedagógicos. / This work belongs to the field of possible connections between psychoanalysis and education. It focuses the pedagogical determination to predict, control and justify whatever happens between adults and children. Based on the concepts provided by Freud\'s legacy, we try to circumscribe the most irreductible thing that insist in the unconscious and that resists the orthopedic actions which aim to obtain \"happy, wealthy winners\" and \"fully developed individuals\". With this purpose, we have chosen to work with the psychoanalytical concept of infantile. This notion guides us through an investigation about the misunderstandings that take place in an educational situation. It also rouses a relevant discussion about the (psycho)pedagogical intentions to eliminate all possible crisis and inconsistencies. In psychoanalisysis, the infantile is related to the concepts of sexuality, desire, neurosis, and other key notions presented by Freud. It is a no symbolized remaining that came from a traumatic situation in which the infans experience an excessive and threatening amount of energy that his psyche (still in constitution) can not deal without the intervention of an other (the mother). These memory traces of helplessness prevail actively in the unconscious, causing effects beyond the principle of pleasure. This way, the psychoanalytical epistemology can provoke the questioning of the illusions that, inspired by (psycho)pedagogical basis, wishes to get rid of all infantile conflicts. On the other hand, psychoanalysis allows us to understand certain transformations that the language can operate on the subject. Psychoanalysis also clarifies the effects that the words addressed by an adult to a child can have, even though these effects can never be foreseen by pedagogical planning.

Este trabalho analisa a série televisiva The Wire (EUA, 2002-2008) como forma de investigar os conceitos psicanalíticos de sublimação e realidade. The Wire toma como ponto de partida o tráfico de drogas em Baltimore, nos Estados Unidos, para examinar o funcionamento de diversas instituições da cidade: polícia, sindicato de estivadores, prefeitura, escola e imprensa. Primeiramente, situamos The Wire no contexto das séries televisivas norte-americanas e consideramos sua estrutura formal e aspectos narrativos e visuais. Em seguida, procedemos a uma narrativa comentada das cinco temporadas da série, atentando para os modos de organização do tráfico de drogas em cada uma delas. O capítulo seguinte consiste em uma investigação dos conceitos de sublimação e realidade na obra freudiana, dividida em três seções: a constituição do aparelho psíquico, as pulsões e seus destinos e o mal-estar na cultura. Por fim, relacionamos as duas investigações realizadas anteriormente, chegando à noção de uma sublimação que está a serviço de Tânatos, ou seja, da destruição. O alvo dessa destruição, nas sociedades capitalistas atuais, é o corpo humano e o corpo da Terra a natureza, entendida como recurso infinito a ser explorado. Essa sublimação, em que a pulsão de morte associa-se à de dominação, levou-nos a considerar a realidade a partir de um eixo pulsional: há realidades eróticas e realidades tanáticas / This work looks at television show The Wire (USA, 2002-2008) as a means to investigate the psychoanalytic concepts of sublimation and reality. The Wire takes drug trafficking in Baltimore as a starting point to consider the institutions of the police, the stevedores union, the city government, city schools and the press. This dissertation first situates The Wire within the context of US television and considers its formal structure and visual and narrative aspects. It then proceeds to describe and comment on the five seasons of the show, paying special attention to the modus operandi of drug trafficking in each of them. The following chapter is an investigation of the concepts of sublimation and reality throughout Freuds writings, divided into three sections: the constitution of the psychic apparatus, the drives and their vicissitudes and the civilization and its discontents. Lastly, this work connects the studies of The Wire and Freud conducted in previous chapters and advances the notion of a type of sublimation which is at the service of Thanatos, i.e., destruction. The target of such destruction in current capitalist societies is the body of humans and the body of the Earth namely nature, understood as an array of infinite resources to be exploited. This sublimation, in which the death drive is fused with the domination drive, has prompted the consideration of reality from a drive perspective: there are both erotic and thanatic realities

A tessitura deste texto tem seu início no encontro com a obra de Antonin Artaud e nas inquietações que surgem da experiência de uma leitura que se dá como se uma escuta fosse. Escuta-leitura que recolhe nas construções do poeta efeitos de testemunho acerca do momento de queda do sujeito, de desenlace da estrutura, tempo de soltura entre voz e palavra, quando o que emerge é o grito. Percorro, para isso, um caminho de leitura que se pretende um ensaio de escuta da narrativa de Antonin Artaud. Narrativa depositada nas cartas escritas por ele ao longo do seu período de internamento nos manicômios franceses entre os anos de 1937 e 1946. Leitura que toma as cartas como recorte norteador da pesquisa, mas que se mantém em interlocução com elementos de outras produções do poeta que se enlacem à escrita das correspondências. Diante do enclausuramento manicomial, das camisas de força, do eletrochoque, Artaud resistia amarrado à arte. O teatro irá compor um dos principais espaços fora da lógica manicomial. O artista, nas cartas, no teatro, nos poemas ou nos autorretratos, vive a busca por encontrar uma forma de transcrever o que é da ordem do grito. Este estudo acerca da voz e das tentativas de escritura do inominável conduz a uma pergunta auxiliar sobre o corpo. Questão que emerge na experiência clínica ao encontrar, no lugar de palavras articuladas a uma trama discursiva, algo que dá a ver a história de um sujeito através do que no corpo se cifra. Para compor essa trama entre o texto artaudiano e os interrogantes que emergem da clínica, busco nos fios da psicanálise a lalangue – articulador teórico que, em minhas elaborações, enlaça corpo e palavra, voz e escrita. É a partir de lalangue que me inclino em direção à obra de Artaud. Artaud encenou, desenhou, escreveu, gritou o grito. E assim, o grito, vestígio de real que irrompe na cadeia associativa em razão da desarticulação do discurso, pode fazer algo de uma travessia: do vazio da voz desancorada da palavra em um momento de queda do sujeito para um espaço/tempo de endereçamento e existência. Existência que se sustentará corporificada na obra de Artaud. / The woven of this text has its beginning in the work of Antonin Artaud and in the anxiety that arise from the reading-listen experience as if it were a listening. The listening-reading that gathers in the construction of the poet effects of the testimony regarding the moment of the subject fall, of the structure disconnection, of looseness time between the voice and the word, when what arise is the scream. For that, I laid a reading path that is a listening essay in the narrative of Antonin Artaud. This narrative is found in the letters which were wrote by him in his time as an intern in several French mental asylums, from 1937 to 1946. This reading makes his letters as the research compass, but maintain the connection to other work of this poet. Faced with the mental asylum enclosure, the straitjacket and the electro-shock, Artaud remained bound to the art. The theater will compose one of the spaces out of this asylum logic. In the letters, in the theater, in the poems or in the self-portraits, the artist lives to find a way to transcribe what is an scream instance. This study regarding the voice and the writing attempts of the unnamed, leads an auxiliary question about the body. This question arises in the clinical experience which finds, replacing the words from a discursive plot, something else that makes the subject history cyphered in the body. To compose this plot between the plot between the text from Artaud and the questioners that arise from the clinic, I turn to the threads of the lalanage psychoanalyses – theoretical articulator which in my reasoning, connects body and word, voice and writing. Since lalange that I tend to the work of Artaud. Artaud, played, draw, wrote and shout out the scream. With these actions the scream, trace of the real that irrupts in the association chain due to the disarticulation of the speech, can make the passage: from the voice emptiness unanchored from the word during the moment of the subject fall to a time/space of direction and existence. Existence that sustains itself embodied in the work of Artaud.

Student Number : 0400486V - MSc (Eng) dissertation - School of Electrical and Information Engineering - Faculty of Engineering and the Built Environment / The Voltage Dip Test Facility at the University of the Witwatersrand utilises a resistive load during testing of variable speed drives. This method produces valuable results regarding the performance of drives under dip conditions. It has been shown that load type does influence the performance of drives and this variation cannot be tested under current conditions as only linear loading is attainable with resistive loads. This thesis proposes a programmable load based on the concept of field-oriented control of an induction motor. The concepts involved with field-oriented control are discussed and shown to be suitable for this application. An implementation strategy utilising custom-designed software and an off-the-shelf VSD is developed and executed. The performance of the programmable load is analysed under both steady-state and dynamic conditions.

Wheelchair-bound individuals who have limited or no upper-limb usage have difficulty with picking and placing of objects, opening doors, and other activities of daily living (ADLs), such as turning on a light switch or drinking from a cup. A wheelchair-mounted robot arm (WMRA) would aid individuals with completing ADLs and increase their independence, therefore an improved WMRA has been designed. Building upon previous WMRA research and incorporating research from industrial robot arms, carbon fiber tubing is the main component for the structure of the arm, a novel development for WMRAs. Factors that go into WMRA design include weight, speed, safety, robustness, cost, and the anticipated tasks. Many of these factors, such as weight, speed, and cost, can be improved upon compared to previous WMRAs by using carbon fiber materials. The use of carbon fiber enables the arm to be strong, but also lighter weight than other WMRAs. Testing was conducted on the pultruded carbon fiber tubing to ensure that the structure of the arm could withstand the necessary bending and tensile forces for the arm to hold up to 3.85kg, the standard weight of a gallon of milk, at the end effector. The arm's carbon fiber frame also allows the motor and sensor wiring to run internally, which improves the arm's safety and aesthetics, while protecting it from the arm's external environment. Lightweight high-torque motors, harmonic drives, newly designed carbon fiber frame, and a stand-alone 8-axis motion-control board, allow the arm to weigh less, have a longer overall length, be more robust, and be safer electronically than the previous University of South Florida WMRA, which was shown through prototype testing.