Thesis (MTech (Electrical Engineering))--Cape Peninsula University of Technology, 2017. / This dissertation represents the design and development of a load management system for fixed appliances in a safe direct current (DC) Reconstruction and Development Programme (RDP) house. A combination of valley filling, load shifting and peak clipping load management techniques were employed to assist in reducing the peaks observed in the RDP house load profile during peak hours. A DC RDP house laboratory model was developed. The study is based on the assumption that the normally 220 V alternative current (AC) grid is replaced by a 350 V DC grid. The assumption is thus that 350 V DC is available at the distribution box in the RDP house laboratory model. All theoretical work was based on a 350 V DC system, but due to the lack of a laboratory 350 V DC supply, all physical tests were conducted by making use of a 300 V DC supply which was available. Consequently all calculations were thus based on 300 V DC as well. The geyser was the main fixed appliance focused on since it contributes to a significant portion of the power used. An AC geyser was successfully modified in order to be used in the DC network. Safety of the system was considered in order to interrupt the power in case of overcurrent or to isolate the power. Electronic switches were also developed and implemented to ensure that the DC power could be safely switched on and off and that the low power DC was isolated from the high power DC. LabVIEW allowed all other appliances in the DC RDP house to be virtually represented so that a holistic view of the power use of the house could be represented. This also allowed the system to be successfully simulated before any physical work was conducted. The load management system was successfully implemented by making use of power line communication. This proved to be a cost effective means to apply the load management algorithm. The algorithm consisted mainly of power on / off instructions that were executed during peak and off-peak times. It follows the normal use of timers used in the AC system to help reduce demand. It was found that the load management system successfully reduced the demand during peak hours without compromising the basic needs of the user. The power line communication modem proved to be very reliable in implementing the load management algorithm.

Orientador: Antonio Baldo Geraldo Martins / Banca: José Antonio Alberto da Silva / Banca: Simone Rodrigues da Silva / Resumo: Sendo baixo o florescimento e a alternância de produção um sério problema para os produtores de lichia do mundo todo, se instalou este experimento em plantas do banco de germoplasma da Faculdade de Ciências Agrárias e Veterinárias, UNESP - Jaboticabal, estado de São Paulo. Com o objetivo de estudar o efeito do anelamento de ramos sobre o florescimento, a influência dos quadrantes geográficos no florescimento e, com base nas medidas do fruto nos eixos longitudinal (L) e transversal (T), indicar o período da maturação de variedades de lichia Bengal, Brewster, Mauritius, WB4, Americana e Groff com 9 anos de idade. Foram registrados dados de temperatura, precipitação, o número de flores por ramos e o comprimento dos eixos L e T dos frutos. Efetuou-se o anelamento de ramos com 1 cm de espessura na primeira quinzena do mês de abril de 2007. Os ramos selecionados situavam-se na parte mediana da copa, os 4 ramos anelados foram alternados com as 4 testemunhas completando todo o diâmetro da árvore. As avaliações foram realizadas da primeira quinzena no mês de agosto de 2007 até a primeira semana no mês de outubro de 2008. Nota-se que, para o ano de 2007, as temperaturas foram mais elevadas e isso pode ter desfavorecido o florescimento da variedade Bengal. No entanto, no ano de 2008, em que as temperaturas máximas e mínimas foram mais amenas, foi observado o florescimento para a última variedade. Verificou-se que em 2007 a precipitação média mensal no mês de abril e maio foi mais próxima da recomendada que em 2008 no mesmo período. Houve maior florescimento em ramos anelados em 2007, sendo que a 'Brewster' diferiu significativamente com melhor florescimento neste ano, seguida da 'Mauritius' e 'WB4'. Em 2008 a 'Groff' diferiu significativamente com maior porcentagem de ramos anelados com flores. Foi ... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: Being the low growth and irregular production are problems encountered by producers in the world. This experiment was installed in plants from germplasm bank at Faculty of Agrarian and Veterinary Sciences, UNESP - Jaboticabal, São Paulo state. In order to study the effects of branches girdling was evaluated on flowering, the influence of geographical areas in the flowering and on the fruit basis the longitudinal (L) and transverse (T) axis indicate the best period to maturity varieties of litchi Bengal, Brewster, Mauritius, WB4, Americana and Groff with 9 years old. Data were recorded in temperature, precipitation, number of flowers per branch and the length of L and T axes of the fruit. The girdling with 1 cm of thickness was made in April of 2007. The branches selected were located in the median of the crown; the four girdled branches were alternated with four controls completing the entire tree diameter. The treatments were performed at the same season, the first half of August to first week in the month in October, in 2007 and 2008. Note that, for the 2007 year the temperatures were higher and this may have disadvantaged the flowering of the Bengal variety. However, in the 2008 year where the maximum and minimum temperatures were milder, the flowering was observed for the same variety. In 2007, the average monthly of precipitation in April and May was closer to recommended in 2008 in the same period. The girdled branches in 2007 was higher flowering and the 'Brewster' differed significantly with better flowering in this year, followed by 'Mauritius' and' WB4 '. In 2008 the 'groff' differed significantly with a greater percentage of girdled branches with flowers. The advance of flowering was observed in girdled branches. Brewster and Bengal varieties may be alternating, because the girdling these varieties induced the largest flowering of... (Complete abstract, click electronic access below) / Mestre

Este trabalho descreve a construção e caracterização de um novo transdutor dedicado às medições susceptométricas e ultrassônicas de amostras marcadas com partículas magnéticas. Este transdutor, denominado de magnetoacústico, consiste de um sistema híbrido formado pela junção de um Biossusceptômetro de Corrente Alternada (BCA) e um transdutor ultrassônico. Seu principio básico de funcionamento consiste na medida simultânea da magnetização de um meio material marcado com partículas magnéticas e das microvibrações da estrutura interna deste meio quando excitado por um campo magnético alternado externo gerado pelas próprias bobinas de excitação do BCA. Estudos in vitro foram realizados para auxiliar no desenvolvimento e caracterização do protótipo apresentado neste trabalho. A técnica de medida empregando este transdutor híbrido foi denominada de vibromagnetoacustografia. As amostras utilizadas consistiram de meios fluidos marcados com traçadores magnéticos (micropartículas de ferrita de tamanhos variando entre 30 m e 70 m de diâmetro). Foi avaliada a dependência da resposta do sistema com diferentes parâmetros físicos tais como: viscosidade do material base o qual foi misturado as partículas ferromagnéticas; concentração dessas partículas misturadas ao material base; frequência de oscilação do campo magnético de excitação; tensão nas bobinas de excitação e a distância entre a amostra e o transdutores. A resposta do transdutor magnetoacústico apresentou melhor relação sinal/ruído em torno de 200 Hz de frequência de magnetização, considerando uma concentração de 4% de ferrita. Acima desta concentração a viscosidade do material base era alterada e interferia na medida. As respostas do susceptômetro e do ultrassom Doppler contínuo possuem uma relação linear com o nível de tensão aplicada nas bobinas de excitação e uma dependência quase linear com baixas concentrações de partículas ferromagnéticas ( 4%). Também foi realizado um teste de repetibilidade no protótipo obtendo um desvio relativo de 0,94% e 0,25% nas medições Doppler e susceptométricas, respectivamente. A medida de vibração das micropartículas ferromagnéticas realizadas in vitro, usando um transdutor Doppler contínuo, apresentou alta sensibilidade para baixas concentrações de material ferromagnético inseridos em meio fluido (~ 1%). / This work describes the construction and characterization of a new transducer dedicated to the susceptometrics and ultrasonic measurements of samples labeled with magnetic particles. This transducer, called magneto-acoustic, consists of a hybrid system formed by the junction of an Alternating Current Biosusceptometer (ACB) and an ultrasonic transducer. Its basic operation principle is the simultaneous measurement of the magnetization and the internal structure micro-vibrations of a medium labeled with magnetic particles when excited by an external alternating magnetic field generated by the ACB excitation coils. In vitro measurements were performed to support the prototype development and characterization presented in this work. The measurement technique employing this hybrid transducer was called vibromagnetoacoustography. The samples consisted of fluid medium labeled with magnetic tracers (ferrite micro particles of diameter ranging from 30 m and 70 m). It was evaluated the system response dependence with different physical parameters such as: base material viscosity in which ferromagnetic particles was mixed; the particles concentration in the base material; the oscillation frequency of the magnetic field excitation; the voltage applied on magnetizing coils and the distance between sample and transducers. The magneto-acoustic transducer response showed a better signal to noise ratio for magnetization frequency around 200 Hz and a 4% ferrite concentration. Above this concentration the base material viscosity changed disrupting the measurements. The responses of susceptometer and Doppler ultrasound have a linear dependence with the applied voltage level in the magnetizing coils and an quasi linear dependence with low ferromagnetic particles concentrations (4%). A repeatability test was also performed to the prototype which indicated a deviation of 0.94% and 0.25% in the Doppler and susceptometric measurements, respectively. The vibration measurement of ferromagnetic micro-particles performed in vitro, using a Doppler transducer, showed high sensitivity to low ferromagnetic material concentrations (~1%) immersed in a fluid medium.

Introdução: O Padrão Alternante Cíclico (“CAP”, do inglês - Cyclic Alternating Pattern) é um ritmo fisiológico do sono NREM, que corresponde aos períodos de ativação cíclica expressos por eventos fásicos do sono. O aumento na expressão de taxa do CAP tem sido considerado uma medida de instabilidade e fragmentação do sono. O CAP representa uma condição favorável para a ocorrência de descargas interictais e/ou ictais. A modulação do CAP em pacientes com Epilepsia do Lobo Temporal (ELT) não está bem definida. Objetivos: Analisar a expressão do CAP em pacientes com ELT e comparar com o grupo de controle. Selecionar o grupo de pacientes sem distúrbios do sono que possam influenciar a organização do sono. Métodos: Foi realizado estudo transversal com grupo de controle de comparação. A seleção foi pareada em sexo e idade entre pacientes com ELT e o grupo de controle, obedecendo aos critérios de inclusão e exclusão. Os parâmetros do sono e CAP foram analisados em 13 pacientes com ELT (6 do sexo masculino e 7 do sexo feminino; idade média: 33,8 ± 8,5 anos) e 13 indivíduos sadios (8 do sexo masculino e 5 do sexo feminino; idade média: 26,1 ± 9,2 anos), os quais não apresentaram distúrbios do sono. A comparação dos dois grupos foi realizada através do “teste t” de Student e confirmada pelo “teste U” de Mann-Whitney. Resultados: Os pacientes com ELT apresentaram aumento na taxa de CAP (44,02 ± 5,23 % versus 31,83 ± 3 %; p<0,001) e maior duração do tempo de CAP (133,77 ± 15,56 min. versus 99,38 ± 9,6 min.; p<0,001) em relação aos indivíduos sadios. Não houve diferença na média da duração da fase A (9,27 ± 1,15 seg. versus 8,7 ± 0,61 seg.; p<0,131), e a média da duração da fase B não atingiu diferença significativa (22,92 ± 1,71 seg. versus 21,54 ± 1,78 seg.; p<0,054) entre os dois grupos. A comparação dos parâmetros de sono e de CAP dentro de cada grupo, mostrou não haver diferença entre os gêneros. A análise estatística dos parâmetros do sono em pacientes com ELT evidenciou uma diferença significativa das seguintes variáveis: menor latência ao sono (5,8 ± 2,4 min. versus 14,2 ± 7,6 min.; p=0,002); aumento do número da troca de estágios com média de 91,1 ± 25,7 versus 68,2 ± 12,8; p=0,008; menor duração de estágio IV (30,8 ± 14,8 min. versus 51,4 ± 12,5 min.; p=0,001); maior percentual do estágio III (7,7 ± 2,8% versus 5,7 ± 1,7%; p=0,035); menor percentual do estágio IV (7,9 ± 4% versus 12,9 ± 3,3%; p=0,002) em pacientes com ELT, comparando com o grupo de controle. A análise dos despertares breves demonstrou em pacientes com ELT: maior número de despertares breves em sono (66,5 ± 20 versus 41,8 ± 9; p=0,001); maior número de despertares breves em sono NREM (52,9 ± 19,6 versus 31 ± 9,5; p=0,002); maior duração total de despertares breves em sono (549,1 ± 170,3 seg. versus 357,2 ± 88,5 seg.; p=0,002); maior duração total de despertares breves em sono NREM (436,8 ± 165,7 seg. versus 271,9 ± 95,2 seg.; p=0,006); aumento do índice de despertar breve em sono (10,2 ± 2,9 versus 6,3 ± 1,7; p=0,001); aumento do índice de despertar breve em sono NREM (10,3 ± 3,4 versus 6 ± 2; p=0,001). Não houve diferença significativa de número (13,6 ± 5,6 versus 10,8 ± 3,7; p=0,149), duração total (112,3 ± 48,3 seg. versus 85,3 ± 25,2 seg.; p=0,091) e índice de despertar breve (9,7 ± 3,8 versus 7,4 ± 2,4; p=0,075) em sono REM entre os dois grupos. Todos os pacientes comELT tiveram uma eficiência do sono normal e similar ao grupo de controle (90,4 ± 2,9 % versus 90,6 ± 2,9 %). Conclusões: Os pacientes com ELT apresentam aumento da taxa de CAP e da duração de tempo de CAP em relação ao grupo controle, demonstrando um aumento na instabilidade e fragmentação do sono. O aumento na expressão da taxa de CAP, alterações nos parâmetros de fragmentação e descontinuidade do sono, expressos pelo aumento de número, duração e índice de despertares breves em sono NREM e o número de mudanças de estágios, associados à eficiência normal do sono em nosso grupo de pacientes com ELT, podem sugerir que o CAP tem um papel na modulação do sono. A fragmentação e a instabilidade do sono em pacientes com ELT, provavelmente, ocorrem devido à própria epilepsia e podem refletir a interação do foco epiléptico com os sistemas responsáveis pela manutenção e estabilidade de sono. / Introduction: Cyclic Alternating Pattern (“CAP”) is a NREM sleep physiological rhythm corresponding to periods of cyclical activation expressed by phasic events of sleep. The increase in the CAP rate expression has been considered a measure for sleep instability and fragmentation. CAP offers a favorable condition for interictal and/or ictal discharges. The CAP modulation in patients with Temporal Lobe Epilepsy (TLE) is not well defined. Objectives: Analyze the CAP expression in patients with TLE comparing it with a control group. Select the group of patients without sleep disorders which may interfere with sleep organization. Methods: A transversal study was conducted with a comparing control group. The selection was paired on gender and age between patients with TLE and the control group, in accordance with inclusion and exclusion criteria. The sleep parameters and CAP were analyzed in 13 patients (6 males and 7 females; mean age: 33,8 ± 8,5 years) and 13 healthy individuals (8 males and 5 females; mean age: 26,1 ± 9,2 years) who did not present sleep disorders. The comparison of the two groups was made through Student’s t-test and was confirmed by the Mann-Whitney U test. Results: Patients with TLE showed an increase in the CAP rate (44,02 ± 5,23% versus 31,83 ± 3%; p<0,001) and CAP time was longer (133,77 ± 15,56 min. versus 99,38 ± 9,6 min.; p<0,001) as compared to healthy individuals. There was no difference in the duration average of stage A (9,27 ± 1,15 sec. versus 8,7 ± 0,61 sec.; p<0,131), and the duration average of stage B did not show a significant difference (22,92 ± 1,71 sec. versus 21,54 ± 1,78 sec.; p<0,054) between both groups. The comparison of sleep parameters and CAP within the group showed that there is no difference between the genders. The statistical analysis of sleep parameters in patients with TLE showed a significant difference in the following variables: lower sleep latency (5,8 ± 2,4 min. versus 14,2 ± 7,6 min.; p=0,002); increase in the number of stage shifts with an average of (91,1 ± 25,7 versus 68,2 ± 12,8; p=0,008); lower duration of the stage IV (30,8 ± 14,8 min. versus 51,4 ± 12,5 min.; p=0,001); higher percentage of the stage III (7,7 ± 2,8% versus 5,7 ± 1,7%; p=0,035); lower percentage of the stage IV (7,9 ± 4% versus 12,9 ± 3,3%; p=0,002) in patients with TLE as compared to the control group. The analysis of arousals in patients with TLE showed: a higher number of arousals during sleep (66,5 ± 20 versus 41,8 ± 9; p=0,001); a higher number of arousals during NREM sleep (52,9 ± 19,6 versus 31 ± 9,5; p=0,002); a longer total duration of arousals during sleep (549,1 ± 170,3 sec. versus 357,2 ± 88,5 sec.; p=0,002); a longer total duration of arousals during NREM sleep (436,8 ± 165,7 sec. versus 271,9 ± 95,2 sec.; p=0,006); an increase of arousal index during sleep (10,2 ± 2,9 versus 6,3 ± 1,7; p=0,001); an increase of arousal index during NREM sleep (10,3 ± 3,4 versus 6 ± 2; p=0,001). There was not a significant difference in number (13,6 ± 5,6 versus 10,8 ± 3,7; p=0,149), total duration (112,3 ± 48,3 sec. versus 85,3 ± 25,2 sec.; p=0,091) and arousal index (9,7 ± 3,8 versus 7,4 ± 2,4; p=0,075) during REM sleep between the two groups. All patients with TLE showed a sleep efficiency that is normal and similar to the control group (90,4 ± 2,9% versus 90,6 ± 2,9%).Conclusions: Patients with TLE showed an increase in CAP rate and a longer CAP duration in relation to the control group, demonstrating an increase in the instability and fragmentation of sleep. The increase in the CAP rate expression, alterations in the parameters of sleep fragmentation and discontinuity that as expressed by increase in the number, duration, arousal index during NREM sleep and number of stage shifts, associated with normal sleep efficiency in our group of patients with TLE may suggest that CAP may have influence in the modulation of sleep. Sleep fragmentation and instability in patients with TLE may occur probably due to epilepsy itself, reflecting the interaction of the epileptic foci with the systems responsible for the maintenance and stability of sleep.

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES / Fundação de Apoio a Pesquisa e à Inovação Tecnológica do Estado de Sergipe - FAPITEC/SE / Introduction: Electrical stimulation, a non-pharmacological resource, has been widely used for pain relief. The aussie current has presented analgesic potential effect, however, its form of action is still hypothetical. Objective: to evaluate the effect of aussie current on nociception and motor behavior in an animal model of inflammatory joint pain. Methods: 36 male Wistar rats were used and the inflammation was induced in the knee by intra-articular injection of a mixture of 3% carrageenan and 3% kaolin. The animals, randomly distributed, were separated into six groups: four groups were treated with aussie current with high or low intensity combined with high or low frequency, burst duration of 4 ms and burst frequency of 50 Hz for 20 minutes; negative control group was remained anesthetized during this same period and the positive one was treated with morphine (5 mg/kg), each group consisting of 6 animals. Primary, secondary and thermalv hiperalgesy, as well as the exploratory locomotor activity of the animals were evaluated. A single investigator performed all assessments, in addition to being masked, and the therapist did not interfere in the assessments. The results were expressed as mean ± SEM. Differences between the groups were related by the two-way ANOVA with the post hoc Tukey test. Values of p <0.05 were considered significant. Results: There was a significant reduction of the deep mechanical threshold 24 hours after induction of inflammation when compared to baseline in all groups (p <0.002). No significant differences were observed in the post-treatment evaluations with the aussie current at moments 0h, 2h, 4h, 6h immediately after the first application and after repeated applications for five consecutive days, only the morphine treated group presented reduction of hyperalgesia (p <0.02). Conclusion: the aussie current did not show antinoceptive effect in animal model of inflammatory pain. / Introdução: A estimulação elétrica, um recurso não-farmacológico, tem sido bastante utilizada para alívio da dor. A corrente aussie tem apresentado potencial efeito analgésico, porém, sua forma de ação tem sido pouco estudada. Objetivo: Avaliar o possível efeito da corrente aussie na nocicepção e no comportamento motor em modelo animal de dor articular inflamatória. Métodos: Foram utilizados 36 ratos Wistar machos e a inflamação foi induzida no joelho pela injeção intra-articular de uma mistura de 3% de carragenina e 3% de caolina. Os animais, distribuídos aleatoriamente, foram separados em seis grupos: quatro grupos tratados com a corrente aussie com alta ou baixa intensidade combinada com alta ou baixa frequência, duração de burst de 4 ms e a frequência em burst de 50 Hz, durante 20 minutos; grupo controle negativo que permaneceu anestesiado durante esse mesmo período e o positivo tratado com morfina (5 mg/kg) sendo cada grupo composto por 6 animais. Foram avaliadas hiperalgesia primária, secundária e térmica, além da atividade locomotora exploratória dos animais. Um único pesquisador realizou todas as avaliações, além de ter sido mascarado, e o aplicador da terapia não interferiu nas avaliações. Os resultados foram expressos em média +/- EPM. Diferenças entre os grupos foram analisadas pela ANOVA de duas vias com o teste post hoc de Tukey. Valores de p<0,05 foram considerados significativos. Resultados: Houve redução significativa do limiar mecânico profundo 24 horas após indução da inflamação quando comparado ao momento basal em todos os grupos (p<0,002). Não foram observadas diferenças significativas nas avaliações de hiperalgesia primária, secundária e térmica, nem da atividade locomotora exploratória pós-tratamento com a corrente aussie nos momentos 0, 2, 4 e 6 h imediatamente após a primeira aplicação e após aplicações repetidas por cinco dias consecutivos, apenas o grupo tratado com morfina apresentou redução dessas variáveis avaliadas. Conclusão: A corrente aussie não mostrou efeito antinoceptivo em modelo animal de dor inflamatória. / Aracaju

Orientadores: Maria do Carmo Gonçalves, Celso Aparecido Bertran / Dissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Química / Made available in DSpace on 2018-08-25T06:27:22Z (GMT). No. of bitstreams: 1 Silva_LauraCaetanoEscobarda_M.pdf: 2337508 bytes, checksum: c8a529b70aa1d66dc7e8a4ca0b28ac3e (MD5) Previous issue date: 2014 / Resumo: Membranas para regeneração óssea guiada (GBR) são uma nova classe de membranas utilizadas em cirurgias dentárias, que têm a habilidade adicional de induzir o crescimento ósseo. Neste trabalho, foram preparadas membranas GBR de poli('épsilon'-caprolactona) pelo método de inversão de fases induzida por vapor, que foram modificadas pelo crescimento de fosfato de cálcio em sua superfície para obter propriedades de osteoindução, características de membranas GBR. Para promover a modificação de superfície, inicialmente, moléculas aniônicas foram utilizadas como agentes de nucleação, fixando grupos aniônicos na superfície da membrana. Foram avaliados três agentes de nucleação diferentes: ácido esteárico, hidrogenofosfato de bis(2-etilhexila) e hidrogenofosfato de bis(metacriloiloxietila). As membranas foram imersas alternadamente em soluções de nitrato de cálcio e de hidrogenofosfato de diamônio para que as moléculas aniônicas pudessem atuar como sítios de nucleação e crescimento das partículas de fosfato de cálcio. As propriedades térmicas e mecânicas das membranas de poli(épsilon'-caprolactona) não foram alteradas pela presença de agente de nucleação ou de fosfato de cálcio na superfície. No entanto, devido à redução da massa molar do polímero na presença de hidrogenofosfato de bis(2-etilhexila) e de hidrogenofosfato de bis(metacriloiloxietila), observou-se um discreto aumento no grau de cristalinidade da PCL nesses casos. Foi possível obter partículas de fosfato de cálcio na superfície das membranas utilizando-se os três agentes de nucleação propostos, no entanto, a morfologia e estrutura cristalina dessas partículas mostraram-se dependentes da estrutura química do agente de nucleação. As membranas contendo ácido esteárico ou hidrogenofosfato de bis(metacriloiloxietila) que foram submetidas ao tratamento superficial por ciclos de imersão sequencial apresentaram o melhor desempenho nos ensaios de biocompatibilidade. A nova metodologia desenvolvida neste trabalho, envolvendo o preparo de membranas de poli(?-caprolactona) modificadas superficialmente pelo crescimento de fosfato de cálcio mostrou-se bastante promissora na produção de dispositivos bioreabsorvíveis e osteoindutores com características úteis para aplicação na periodontia / Abstract: Guided bone regeneration (GBR) membranes are a new class of membranes for periodontal surgery that have the additional ability of inducing bone formation. The aim of this study was to produce biodegradable GBR membranes based on poly(épsilon'-caprolactone) by vapour induced phase separation whose surfaces were modified by calcium phosphate growth, in order to achieve the osteoinductive properties, a characteristic of GBR membranes. Anionic molecules were used as nucleating agents to promote these surface modifications and were added to the polymeric membranes to generate anionic groups on the surface. Three different nucleating agents were tested: stearic acid, bis(2-ethylhexyl) hydrogenphosphate and bis(-(methacryloyloxyethyl) hydrogenphosphate. The membranes were immersed alternately in calcium nitrate and diammonium hydrogenphosphate solutions so that the anionic molecules could act as nucleating sites for calcium phosphate growth. The thermal and mechanical properties of the poly(épsilon'-caprolactone) membranes did not change in spite of the presence of the nucleating agents nor the calcium phosphate particles on the surface. Nevertheless the crystallinity degree showed a slight increase, due to a decrease in PCL molar mass, in the presence of bis(2-ethylhexyl) hydrogenphosphate and bis(methacryloyloxyethyl) hydrogenphosphate. The calcium phosphate growth on the membrane surface was successfully achieved by using all of the three different nucleating agents, moreover the particle morphology and crystallinity showed a dependence on the nucleating agent chemical structure. The membranes containing stearic acid or bis(methacryloyloxyethyl) hydrogenphosphate that went through the alternating soaking surface treatment showed the best performance on the biocompatibility essays. The new methodology developed in this work for the preparation of poly(?-caprolactone) membranes with surfaces modified by calcium phosphate growth has proven to have good potential to produce bioresorbable and osteoinductive devices with useful properties in periodontic applications / Mestrado / Físico-Química / Mestra em Química

[pt] Durante vinte anos, ficou em aberto uma conjectura de Mills, Robbins e Rumsey para a contagem de Alternating Sign Matrices (Matrizes de Sinais Alternados). Zeilberger demonstrou a validade das fórmulas em meados da década de 90. Esse texto apresenta outra demonstração, atribuída a Kuperberg, que emprega técnicas de física estatística (Gelo Quadrado). São apresentadas também formulações alternativas que fazem uso de produtos tensoriais matriciais. / [en] For twenty years, a conjecture by Mills, Robbins and Rumsey on the counting of Alternating Sign Matrices remained open. Zeilberger proved the formulas in the mid-90`s. This text presents another proof, attributed to Kuperberg, which uses techniques of statistical physics (square ice). Alternative formulations are also shown, making use of matrix tensor products.

D.Ing. / Alternating current systems employing single-frequency sinusoidal waveforms render optimal service when the currents in that system are also sinusoidal and have a fixed phase relationship to the voltages that drive them. Under unity- power factor conditions, the currents are in phase with the voltages and optimal net-energy transfer takes place under minimum loading conditions, i.e. with the lowest effective values of current and voltage in the system. The above conditions were realised in the earlier years, because supply authorities generated 50 Hz sinusoidal voltages and consumers drew 50 Hz sinusoidal currents with fixed phase relationships to these voltages. Static and rotating electrical equipment like transformers, motors, heating and lighting equipment were equally compatible with this requirement and well-behaved AC networks were more the rule than the exception. The fact that three-phase systems conveyed the bulk of the power from one topographical location to the next did not constrain the utilisation of that concept at all, even though poly-phase transmission systems were necessary to increase the economy of transmission and to furnish non-pulsating power transfer. Also, additional theory had to be developed to handle unbalanced conditions in these multi-phase systems and to take care of complex network analysis and fault conditions. Difficulties begin to manifest themselves when equipment not meeting these requirements is connected to the network and when the currents it draws are not sinusoidal. An increasing number of applications demand DC-voltage supplies from which DC-currents are to be drawn. Because power transmission is carried out by means of AC networks, the DC is furnished by converting or rectifying the AC-supply. Power-electronic circuits, of which the R 2P2 power supplies the AEC employs are no exception, employ line-commutated AC/DC converters in their front-ends, and fall into that category. Although these line-commutated, phase-controlled AC/DC converters are capable of handling giga-watt power levels, line-frequency commutation causes the currents they draw on the AC-side to be distorted, even though still to be periodic. These non-sinusoidal currents, drawn from the source, along the transmission lines and through other distribution system immittances, also give rise to non-sinusoidal voltage drops between the source and the load, which results in distorted voltage waveforms at other nodes and at the load. Harmonic penetration studies are essential to evaluate the performance of transmission systems in the presence of current distortion sources. These sources do not only bring about voltage distortion within the confines of their own borders, but extend their influence outside into those of other consumers as well. Supplyutilities are wary of the distortion introduced into their networks by consumers and initial recommendations have now given way to rigid standards for curbing harmonic pollution by consumers Because conventional steady-state alternating current circuit theory fails in the presence of distortion there are only two ways in which harmonic penetration studies can be carried out. Numerical integration methods are mandatory in the study of transient performance of electrical networks during switching and similar occurrences, but become cumbersome when the networks contain more than just a few nodes and are impossible to use when several tens or hundreds of nodes are encountered. Fortunately, harmonic penetration studies can be confined to steady-state operating conditions in a network in which voltages and currents are distorted but remain periodic and are therefore Fourier transformable. When viewed in the frequency-domain, non-sinusoidal but periodic current and voltage waveforms can be represented by discrete frequency spectra. Frequency-domain analysis offers a number of advantages. From the frequency-domain point of view, distortion can be quantified in terms of complex phasor values of voltages and currents at discrete harmonic frequencies that individually lend themselves to conventional circuit theory, permitting calculations to be carried out in extensive networks. Solutions that apply to these individual harmonic frequencies can then be summated across the spectrum to furnish aggregate or joint parameters of currents, voltages and powers and can also be transformed back into the time-domain for the reconstruction of the relevant time-dependent waveforms. Both the frequency and time-domain waveforms, of voltage and current, constructed in the above manner are concise and convey the same numerical information. When attempting, however, to quantify the circuit behaviour in terms of the classical definitions of active, reactive and apparent power, it is soon discovered that different definitions are possible. The different definitions, unfortunately, lead to divergent results and it is impossible to assess the utility of each different theory on a general basis. Only by applying the different theories in dedicated measurements, can their relative worth be established in terms of specific circumstances. That is the main theme of this dissertation.

M.Ing. (Electrical and Electronic Engineering) / The possibilities and technology of converters with an alternating voltage link are investigated for high specific power conversion at high frequencies. With a view to the functional description of these power converters, s i muLat i on techniques are considered for both system and circuit analysis. A thorough investigation is made into the design of high frequency power transformers, which play an important role in this class of power circuits. This includes a theoretical analysis in conjunction with the 'practical implementation of a design procedure for minimal eddy current losses in the windings as well as experimental work on losses in ferrite cores. For the remainder of the study, attention is focussed on the two pulse inverter which is responsible for the generation of the alternating voltage in the high frequency link. The suitability of bipolar and field effect transistors for power switching, is critically examined and a voltage compensation on the bipolar Darlington, which reduces on-state losses, yielded good results upon application. A study on the feasibility of non-dissipative snubber techniques on the centre tapped inverter is presented, thus supplying a practical way of reducing switching losses without affecting the efficiency of the system. An additional, yet simple, network is added to the snubber circuits of the two pulse inverter which is operational during low load conditions.' in order also to have low switching losses under these circumstances. Finally a 50 k~v, 10 kHz centre tapped inverter was developed and built.

This thesis is a survey of the field of languages over infinite sequences. There is active research going on in this field, during the last year several new results where published. We investigate the language containment problem for infinite sequences, with focus on complementation of Büchi automata. Our main focus is on the approach with alternating automata by Kupferman&amp;Vardi. The language containment problem has been proved to be in EXPSPACE. We identify some cases when we can avoid the exponential blow-up by taking advantage of properties of the input automaton. Some of the algorithms we explain are also implemented in a Sicstus Prolog library.