Dengue is an important arboviral disease transmitted to humans through the bite of female mosquito Aedes aegypti. As there is no vaccine available, the control of disease occurs, mainly, by the reduction of mosquito population and personal protection to prevent contact between hosts and vectors. Given the increasing process of chemical resistance to insecticides, natural products emerge as safer alternatives for integrated control of endemic diseases. The aim of this work was to evaluate the larvicidal and repellent activities of essentials oils extracted from Xylopia laevigata, Xylopia frutescens and Lippia pedunculosa and of their majority compounds, piperitenone oxide and r-limonene. The larvicidal activity was investigated by exposure of third instar larvae to different concentrations of essentials oils. After 24 hours of exposition, larvae showing lack of mobility or inability to move to water s surface were considered as dead. The repellency effect was based on the suppression of mosquitoes landing on human skin. Essentials oils were diluted in ethanol and applied directly over the volunteer s skin. For each essential oil were performed 12 tests, in which oils concentrations ranged from 0.1 to 10%. The essential oil of L. pedunculosa and its major volatile compounds were shown to be toxic for Ae. aegypti larvae, with CL50 lower than 60 ppm. In the other hand, plants of Xylopia genus just proved to be toxic to Ae. aegypti when in concentrations higher than 1000 ppm. This fact make their use in large-scale unfeasible. All plants tested provided some degree of protection against mosquitoes landing. However only the essential oil of L. pedunculosa and piperitenone oxide provided 100 % of protection against mosquito landings when tested in concentrations lower than 1%. Although its performamnce against dengue mosquitoes, the essential oil of L. pedunculosa shows toxicity the human skin. Therefore, further studies are required to get formulations which are able to provide longer time protection. / A dengue é uma importante arbovirose transmitida ao homem por meio da picada do mosquito fêmea Aedes aegypti. Como não há vacinas, o controle da transmissão da doença se dá, principalmente, com a redução da população de mosquitos e a adoção de medidas de proteção individual que impeçam o contato entre hospedeiros e vetores. Diante do agravamento do processo de resistência aos inseticidas químicos, os produtos de origem vegetal se apresentam como alternativas mais seguras para o controle integrado de doenças vetoriais endêmicas. O objetivo deste trabalho foi avaliar a atividade repelente e larvicida dos óleos essenciais extraídos das plantas Xylopia laevigta, Xylopia frutescens e Lippia pedunculosa, bem como seus constituintes voláteis, óxido de piperitenona e r-limoneno sobre mosquitos Ae. aegypti. A atividade larvicida foi investigada a partir da exposição de larvas de terceiro estádio às diferentes concentrações dos óleos essenciais e componentes voláteis. Após 24 horas de exposição foram contabilizadas as larvas mortas, considerando mortalidade a ausência de mobilidade ou incapacidade da larva em se mover até a superfície da água. A ação repelente foi observada a partir da supressão de pousos dos mosquitos sobre a pele humana. Os óleos essenciais e compostos químicos foram diluídos em etanol e aplicados diretamente sobre a pele dos voluntários. Para cada produto foram realizados doze testes, nos quais as concentrações variavam de 0,1 à 10%. Tanto o óleo essencial obtido a partir da L. pedunculosa quanto os seus principais compostos voláteis mostraram-se tóxicos para larvas de Ae. aegypti, apresentando CL50 inferior à 60 ppm. Em contrapartida, as plantas do gênero Xylopia apenas mostraram-se tóxicas para as larvas quando em concentrações superiores à 1000 ppm, fato que inviabiliza a sua utilização em larga escala. No que diz respeito à ação repelente, todos os produtos avaliados forneceram algum grau de proteção contra pouso de mosquitos adultos sobre a pele humana. Entretanto, apenas o óleo essencial da L. pedunculosa e o óxido de piperitenona foram capazes de fornecer 100% de proteção, quando testados em concentrações inferiores a 1%. Apesar de eficaz na repelência contra o mosquito transmissor da dengue, o óleo essencial da L. pedunculosa apresentou toxidade sobre a pele humana. Portanto, mais estudos fazem-se necessários a fim de que sejam elaboradas formulações de uso tópico capazes de veicular adequadamente os constituintes químicos dos óleos por um prolongado período de tempo.

Made available in DSpace on 2016-08-17T16:54:34Z (GMT). No. of bitstreams: 1 Tese Jose Gomes de Matos.pdf: 8310310 bytes, checksum: b4d88d65be5edbb4f214f9dd09ed8f3b (MD5) Previous issue date: 2014-03-31 / Conselho Nacional de Desenvolvimento Científico e Tecnológico / This work proposes a new strategy to control the generated power in an alternating current autonomous microgrid that has distributed generators and battery banks. There are no restrictions regarding the type of generator to be connected, however in this particular study the effectiveness of the proposed strategy is analyzed by considering that the power source is a wind turbine coupled to a permanent magnet synchronous generator. The microgrid analyzed consists of at least one bidirectional electronic converter powered by a battery bank, which has the function of forming the microgrid; an electronic converter connected to a wind turbine generator, which operates as a power supplier to the microgrid; loads, and other peripheral systems of control and maneuver. The main objective of the proposed strategy is to maintain the terminal voltages of battery banks under control and below its upper limit, even when momentarily the power demanded by the loads connected to the microgrid is less than the power sources generation capacity. The proposed strategy controls the terminal voltage of the battery banks, controlling the power output that comes from the generators. This is done without the use of dump loads or any physical communication between the electronic converters connected to the battery banks and the electronic converters connected to the generators. A modified droop control technique, based on the grid frequency, is used to inform to the power generator electronic converters on the amount of energy they need to generate in order to maintain the state of charge of the battery banks below their limits. The work also presents the methodology to design and tuning the controllers of the associated variables of the generation system. This includes the voltage and frequency grid, the active and reactive power generated by the generators, the DC bus voltages in all electronic power converters and the terminal voltage of the battery banks. All controllers are designed in the discrete domain. A strategy to decouple the effects of the input disturbances is incorporated, into each controller. Special attention is given to the grid voltage controller due the fact that the effect of the load current disturbance is very significant for the grid power quality. Issues x related to the operation of the wind turbine on its maximum power point are also addressed in the control of the power electronic converter connected to the generator. The control strategy proposed in this study is validated through experimental results obtained using a microgrid prototype of 15 kW rated power. / Este trabalho propõe uma nova estratégia para controle da potência gerada em uma microrrede isolada, que opera em corrente alternada e que dispõe de geradores e bancos de baterias distribuídos ao longo da mesma. Embora não haja restrições quanto ao tipo de gerador a ser conectado à microrrede, neste estudo a aplicabilidade da estratégia proposta é analisada considerando a fonte de potência como sendo uma turbina eólica acoplada a um gerador síncrono a imãs permanentes. A microrrede estudada é composta de um conversor eletrônico bidirecional, alimentado por um banco de baterias, que tem a função de formar a microrrede; um conversor eletrônico ligado ao gerador da turbina eólica e que funciona como alimentador da microrrede; além das cargas e demais sistemas periféricos de controle e manobra. O principal objetivo dessa estratégia é controlar a tensão terminal dos bancos de baterias abaixo de um determinado valor limite, mesmo quando momentaneamente a potência demandada pela carga conectada à microrrede seja inferior à capacidade de geração das fontes de potência. A estratégia proposta controla a tensão dos bancos de baterias, controlando a energia gerada que vem dos geradores. Isto é feito sem a utilização de carga auxiliar para consumir o excesso de energia e sem comunicação física entre os conversores eletrônicos dos bancos de baterias e os conversores eletrônicos conectados aos geradores. Uma técnica de controle droop modificada, com base na frequência da microrrede, é usada para informar aos conversores dos geradores sobre a quantidade de energia que eles estão liberados para gerar, a fim de manter a tensão dos bancos de baterias abaixo dos seus valores limites. O trabalho ainda apresenta as sistemáticas de projeto e sintonia dos controladores das variáveis associadas com o sistema de geração. Isso compreende o controle da tensão e da frequência da microrrede, o controle das tensões nos barramentos de corrente contínua de todos os conversores eletrônicos de potência e o controle da tensão terminal dos bancos de baterias. Todos os controladores são projetados no domínio discreto. Uma estratégia de desacoplamento dos efeitos das entradas de perturbações é incorporada a cada controlador. Nesse enfoque, é dada atenção especial ao controlador de tensão da microrrede, cujo efeito da viii perturbação da corrente da carga é muito significativo para a qualidade de energia do sistema de geração. As questões relativas à maximização do aproveitamento energético das fontes renováveis são contempladas no controle do conversor da turbina eólica. A estratégia de controle proposta neste trabalho é validada a partir de resultados experimentais obtidos com um protótipo de microrrede de potência nominal 15 kw.

La première thématique développée dans ce mémoire vise à développer de nouveaux algorithmes pour la commande des éoliennes reposant sur une machine asynchrone à double alimentation et des convertisseurs multi niveaux. Deux stratégies de contrôle direct du courant, basées sur l’Hystérésis à Zones Carrées et l’Hystérésis à Zones Circulaires (HZCi) ont été proposées. Celles-ci consistent à appliquer des vecteurs de tension appropriés pour contrôler les puissances actives et réactive générées et permettent également d’équilibrer les tensions du bus continu interne des convertisseurs. Des résultats de simulation et d’expérimentation montrent que la stratégie basée sur l’HZCi est meilleure en termes de forme d’onde et de contenu harmonique des tensions de sortie.La seconde concerne la supervision et la gestion des puissances active et réactive dans une ferme éolienne au vu de son intégration dans un réseau électrique. Cette supervision centralisée est assurée par un algorithme qui distribue les consignes de puissance aux éoliennes de la ferme de manière proportionnelle. Ces références sont fonction de la capacité maximale de production de l’éolienne. Pour cela, une analyse des transits de puissance dans le système éolien à base de la machine asynchrone à double alimentation a été effectuée. Elle a permis de déterminer la caractéristique (P, Q) du générateur et de calculer ses limites de compensation en termes de puissance réactive. Une gestion locale des puissances de chaque éolienne a été développée permettant ainsi une répartition des puissances entre le stator de la machine et le convertisseur coté réseau en considérant plusieurs modes de fonctionnement du système éolien / This research work deals with two topics conditioning the large scale development of wind turbines into electrical grids. The first is devoted to the development of new algorithms for the control of Doubly Fed Induction Machine (DFIM) based wind energy conversion systems. Two direct current control strategies have been proposed and are based on the hysteresis square areas (HZCA) and hysteresis circular areas (HZCI). Both strategies apply an appropriate voltage vector to control the active and reactive powers delivered to the grid, and also, to balance the voltages of the inner DC bus converter. Simulation and experimental results show that the HZCI strategy is better than HZCA in terms of output voltage waveforms and harmonic contain.The second topic is dedicated to the active and reactive powers supervision in a wind farm in order to supply prescribed power references from the grid operator. This supervision is ensured by a centralized algorithm that distributes power references between wind turbines in a proportional way. These references are calculated according to the maximum production capacity of wind turbines. An analysis of the power flow in the DFIM based wind energy system has been made to identify the (P, Q) characteristic and to calculate limits in terms of reactive power compensation. The local power management of each wind system has been developed allowing the powers distribution between the stator of the DFIM and the grid side converter by considering several operating modes of the wind generator

En 2005-6, le virus du chikungunya, transmis par les moustiques Aedes albopictus, touche 38% des habitants de La Réunion. Cette épidémie marque la fin de l'usage systématique des insecticides et la refonte des politiques de santé. Les pouvoirs publics enrôlent les citoyens et les moustiques dans l'élaboration de nouvelles frontières, matérielles et symboliques, entre les deux espèces. Cette thèse a pour objectif d'interroger les effets de ces changements de pratiques sur les rapports sociaux de pouvoir en contexte post-colonial, et sur les relations entre humains et moustiques. Pour saisir les dynamiques socio-naturelles à l'œuvre, une ethnographie combinatoire a permis d'observer les co-constructions de savoirs et de pratiques dans plusieurs espaces où s'organise la mise à distance des moustiques. Elle s'est appuyée sur le recueil de discours et l'observation de pratiques au sein du service de lutte contre les moustiques, au cœur d'une équipe de recherche sur la Technique de l'insecte stérile (visant à relâcher des moustiques stériles sur l'île) et auprès de non professionnels de la lutte. Une collecte d'articles de presse et d'archives a achevé de constituer le corpus de données. L'enjeu de cette thèse est de montrer que bien loin d'opérer une simple séparation entre humains et moustiques, les nouvelles pratiques de lutte ont intensifié leurs interactions. En parallèle, elle propose une réflexion sur les dynamiques liées à la coexistence de plusieurs systèmes interprétatifs, permettant d'appréhender – ou non – collectivement la prise en charge du risque épidémique. C'est l’occasion de réfléchir aux relations entre l'État, les scientifiques et les citoyens. / In 2005-6, the chikungunya virus, transmitted by the Aedes albopictus mosquito, affects 38% of the inhabitants of Reunion Island. This outbreak marks the end of the systematic use of insecticides and the consolidation of health policies. Public authorities enlist citizens and mosquitoes in the development of new frontiers, material and symbolic, between the two species. This thesis aims to examine the effects of these changes in practices on the social relations of power in post-colonial context, and the relationship between humans and mosquitoes.To apprehend the socio-natural dynamics at work, a combinatorial ethnography allowed to observe the co-construction of knowledge and practices in several areas where the distancing mosquitoes gets organized. It was based on the collection of speeches and observing practices in the vector control service, in the heart of a research team on the Sterile insect technique (to release sterile mosquitoes on the island) and from non-control professionals. A collection of articles and archives finalized to constitute the body of data.The aim of this thesis is to show that far from making a simple separation between humans and mosquitoes, new management practices have intensified their interactions. In parallel, it proposes a reflection on the dynamics associated with the coexistence of several interpretive systems, allowing to understand - or not - the collective management of epidemic risk. This is an opportunity to reflect on the relationship between the state, scientists and citizens

The thesis is focused on the issue of sensorless vector control of a synchronous motor with permanent magnets in the low-speed range. In the first part, there is a brief description of the synchronous motor and the necessary transformations for the application of vector control. This is followed by the overview of sensorless methods for position estimation by injecting a high-frequency harmonic signal. The practical part is devoted to the implementation of a control algorithm to develop kit STM32NUCLEO-L476RG, which is preceded by the identification of all engine parameters. As part of the implementation, a structure including current, speed and position control was designed. The functionality and robustness of the settings have been successfully tested due to the different inertia and load.

This master thesis deals with the modern algorithms of the asynchronous induction machine and permanent magnet induction machine. It focuses at vector control, direct torque control and input-output feedback linearization. It also describes a library creation and its usages in the Matlab – Simulink environment. The final part of this thesis contains an implementation of chosen algorithms on the DSC Freescale 56F800E family.

This master„s thesis elaborates with EC motors problematic. There are described essential features of brushless DC motors, their principles, construction and methods for rotor position detection. There are mentioned commonly used control algorithms of EC motors including theory of three-phase convertors. This thesis also contains a complex design of the universal convertor for EC motor and its practical implementation. Power parts losses calculation, heat-sink calculation and measurements at the convertor prototype are also described in this thesis.

Hlavným cieľom tejto práce je vytvorenie simulácií rôznych algoritmov riadenia asynchrónneho motora a vzájomné porovnanie ich vlastností. Zaoberá sa taktiež možnosťami konfigurácie náhradného zapojenia na T-článok, -článok a -článok. Obsahuje jednak teoretický rozbor, a taktiež aj simulácie jednotlivých spôsobov riadenia spolu s podrobným návodom na ich realizáciu. Celkovo budú vykonané 3 simulácie – simulácia vektorového riadenia s orientáciou na rotorový tok, vektorového riadenia s orientáciou na statorový tok a simulácia takzvaného prirodzeného riadenia. Ide o úplne nový typ riadenia, ktorého autorom je vedúci tejto diplomovej práce. Jeho simulácia bola vôbec prvým pokusom o funkčnú realizáciu tohto typu riadenia.

PhD (Mathematics) / Department of Mathematics and Applied Mathematics / In this study, we developed multiscale models of vector-borne diseases. In general, the transmission of vector-borne diseases can be considered as falling into two categories, i.e. direct transmission and environmental transmission. Two representative vector-borne diseases, namely; malaria which represents all directly transmitted vector-borne diseases and schistosomiasis which represents all environmentally transmitted vector-borne diseases were studied. Based on existing mathematical modelling science base, we established a new multiscale modelling framework that can be used to evaluate the effectiveness of vector-borne diseases treatment and preventive interventions. The multiscale models consisted of systems of nonlinear ordinary differential equations which were studied for the provision of solutions to the underlying problem of the disease transmission dynamics. Relying on the fact that there is still serious lack of knowledge pertaining to mathematical techniques for the representation and construction of multiscale models of vector-bone diseases, we have developed some grand ideas to placate this gap. The central idea in multiscale modelling is to divide a modelling problem such as a vector-bone disease system into a family of sub-models that exist at different scales and then attempt to study the problem at these scales while simultaneously linking the sub-models across these scales. For malaria, we formulated the multiscale models by integrating four submodels which are: (i) a sub-model for the mosquito-to-human transmission of malaria parasite, (ii) a sub-model for the human-to-mosquito transmission of malaria parasite, (iii) a within-mosquito malaria parasite population dynamics sub-model and (iv) a within-human malaria parasite population dynamics sub-model. For schistosomiasis, we integrated the two subsystems (within-host and between-host sub-models) by identifying the within-host and between-host variables and parameters associated with the environmental dynamics of the pathogen and then designed a feedback of the variables and parameters across the within-host and between-host sub-models. Using a combination of analytical and computational tools we adequately accounted for the influence of the sub-models in the different multiscale models. The multiscale models were then used to evaluate the effectiveness of the control and prevention interventions that operate at different scales of a vector-bone disease system. Although the results obtained in this study are specific to malaria and schistosomiasis, the multiscale modelling frameworks developed are robust enough to be applicable to other vector-borne diseases. / NRF

MPH / Department of Public Health / Background: Malaria is a public health issue killing more than 435 000 people in Sub Saharan Africa. In South Africa, malaria is endemic in 3 provinces namely: Limpopo, Mpumalanga and Kwazulu Natal. Limpopo Province contributes more cases than the other provinces in the country. Purpose: The purpose of the study was to assess community knowledge and prevention practices of malaria at Masisi village, in Mutale Municipality, Vhembe District. The study was conducted at Mutale municipality, Vhembe District. Methodology: A quantitative cross-sectional descriptive approach was used. Data was collected using a questionnaire with open and close ended questions. The targeted population was made up of males and females between the ages of 18 to 75. Validity and reliability have been ensured in the study and the results for reliability were 0.85. Pretesting was done in 5 household at Sanari village which is near Masisi village as they share the same characteristics. A sample of 152 participants was selected from the target population by means of systematic sampling and then select them randomly. Questionnaires were used to collect data. There after Data were analyzed using SPSS version 24.0. The analyzed data were presented in tables, graphs, and in percentages. Results: The findings revealed that majority of the participants 103(67.8%) have secondary education, and most of them, 103(67.8%) are unemployed. The study revealed that about 77% have knowledge regarding malaria transmission. About 130(85.5%) indicated that malaria is caused by a mosquito bite. About 57(38.51%) indicated that they use mosquito coils and nets in their household. Conclusion: Malaria still poses a threat to the lives of people living in malaria endemic areas. Community members at Masisi village have better insight regarding malaria transmission, causes and signs and symptoms. Although the community shows a better understanding of the prevention method they still has to put this into practice in order to eliminate malaria in the area. Health workers are doing a great job in educating the community regarding malaria related issues. / NRF