La fotónica de silicio es actualmente la tecnología mejor posicionada para reemplazar las conexiones electrónicas tanto dentro de los mismos chips, como entre ellos mismos, con el fin de mejorar su rendimiento. Las principales ventajas de la tecnología fotónica de silicio residen en su bajo coste y en su compatibilidad con las actuales técnicas de fabricación desarrolladas por la industria microelectrónica. Dicha compatibilidad permitiría fabricar tanto chips ópticos como chips híbridos que incluyan componentes ópticos y electrónicos. Los moduladores y los conmutadores optoelectrónicos resultan dispositivos fundamentales en aplicaciones de telecomunicaciones. Las principales funciones de los conmutadores y moduladores optoelectrónicos son el enrutamiento y la transmisión de datos de alta velocidad. Esta tesis aborda el diseño y la optimización de la parte eléctrica y óptica (en menor medida) con el fin de optimizar el rendimiento de tales dispositivos desde el punto de vista optoelectrónico. Además, también se tratará la introducción de nuevos materiales compatibles con el silicio y sus procesos de fabricación, como el dióxido de vanadio o el titanato de bario con el fin de demostrar sus propiedades y aplicarlas a los dispositivos optoelectrónicos con el fin de mejorar su rendimiento. / Silicon photonics is nowadays the most promising technology to replace electrical inter- and intra-connections of the chips, increasing the performance in this way. The main advantages of silicon photonics technology lie on its low cost and its compatibility with the fabrications processes of microelectronics industry developed during years which allows the mass production of silicon photonics chips as well hybrid electronic and photonic devices in the same chip. Optoelectronics switches and modulators are key building blocks in photonic devices for tele/datacom applications. Such switches and modulators are devices which provides routing functionalities and the transmission of high speed data respectively. The work of this thesis delves with the design and optimization of silicon based switches and modulators spotlighting the electrical elements. Additionally, the work of this theses deals with the introduction of new silicon-compatible materials as vanadium dioxide and barium titanate, with the aim of demonstrating its functionalities and develop high-performance optoelectronic devices. / La fotònica de silici és actualment la tecnologia millor posicionada per a reemplaçar les connexions electròniques tant dins del propis xips, com entre ells mateixos, amb la finalitat de millorar el seu rendiment. Els principals avantatges de la tecnologia fotònica de silici resideixen en el seu baix cost i en la seua compatibilitat amb les actuals tècniques de fabricació desenvolupades per la indústria microelectrònica. Aquesta compatibilitat permetria fabricar tant xips òptics com a xips híbrids que incloguen components òptics i electrònics. Els moduladors i els commutadors optoelectrònics resulten dispositius fonamentals en aplicacions de telecomunicacions. Les principals funcions dels commutadors i moduladors optoelectrònics són l'encaminament i la transmissió de dades d'alta velocitat. Aquesta tesi aborda el disseny i l'optimització de la part elèctrica i òptica (en menor mesura) amb la finalitat d'optimitzar el rendiment de tals dispositius des del punt de vista optoelectrònic. A més, també es tractarà la introducció de nous materials compatibles amb el silici i els seus processos de fabricació, com el diòxid de vanadi o el titanato de bari amb la finalitat de demostrar les seues propietats i aplicar-les als dispositius optoelectrònics amb la finalitat de millorar el seu rendiment. / Rosa Escutia, Á. (2018). High-efficient electrodes for novel optoelectronic devices in silicon photonics [Tesis doctoral]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/110364

Thesis (MDF)--Stellenbosch University, 2011. / ENGLISH ABSTRACT: Deforestation, increasing pollution levels, diminishing non-renewable energy reserves, the resulting global warming, and climate change are areas of concern to environmentalists and the whole global village. It appears that the solution lies in the exploitation of renewable, clean and sustainable energy resources. Solar energy is one of the renewable, clean and environmentally friendly energy resources readily available in most tropical countries of the world, including Namibia. The research was conducted in the Rocky Crest suburb of Windhoek, Namibia. The research focused on the exploration barriers in the diffusion of solar water heaters (SWHs) for generating hot water for Rocky Crest residents. The investigation involved data collection from the stakeholders, including the residents of Rocky Crest suburb, SWH suppliers, financial institutions, non-governmental organisations (NGOs) and the Ministry of Mines and Energy (MME) in Namibia. The results of this study introduce information that can largely benefit the Rocky Crest residents, MME, NGOs, financial institutions and relevant stakeholders. It can also act as a departure point for further studies on the subject of renewable energy sources, their exploitation and the impact thereof. Furthermore, solutions to the current problems of diminishing non-renewable energy reserves and the impact of pollutant energy sources can be identified and implemented.

Thesis (MBA)--Stellenbosch University, 2015. / ENGLISH ABSTRACT: South Africa is experiencing an energy shortage and volatile supply of electricity. This situation is placing pressure on businesses and citizens and is opening avenues into the renewable sector. This study investigates servicisation as a potential means to assist in the alleviation of energy consumption on the national power grid, and answers whether servicisation in the solar water heating sector could pose as a viable business venture. The main research goal was to investigate whether servicisation within a housing estate could be favourably received. The majority of residents in this high-income bracket were more willing to invest their own capital in renewables rather than being provided with a solar water heater through servicisation. Knowledge of solar water heating is extremely poor amongst consumers, and this contributes to the lack of penetration of solar water heaters in the industry to date. To further exacerbate the situation, installations are often poorly executed, leading to negative experiences by consumers. Initially it was assumed that post 2012, all homes built would be installed with solar geysers or heat pumps, due to legislation. However, surprisingly this was not the case, as a large portion of homes built between 2012 & 2013 have not complied with this legislation.

Les défis environnementaux et l’augmentation de la population viennent en preuve de l’importance de réfléchir à d’autres moyens de production tout en maintenant la sécurité et la fiabilité du système électrique. La sûreté du système électrique exige à tout moment que la production soit égale à la demande des consommateurs, pour ça, différentes solutions sont déjà mises en place, ces solutions consistent à mettre en marche des moyens de pointes couteux et polluants pendant les périodes de pointes, mais comme les moyens de production son insuffisants et vue la difficulté d’exploitation de nouveaux moyens de production, une nouvelle réflexion sur la gestion de la demande est apparue; celle-ci se base sur la possibilité à gérer la demande du consommateur final au lieu de la satisfaire.L’objectif de la thèse est d’étudier la possibilité à rendre des services au système électrique en appliquant des actions de contrôle dites de DR (Demand Response), sur différents types de charges électriques. Ces actions de DR représentent des interruptions partielles appliquées sur les charges électriques de type thermique. Notre choix s’est basé sur ces types de charges parce que celles-ci emmagasinent de la chaleur respectivement dans l’air et dans l’eau; qui peut être restituée pendant la période de contrôle ou d’interruption. Néanmoins, il existe un effet négatif qui suit le contrôle de ces charges car l’énergie effacée de ces charges est reportée à l’instant de reconnexion de celles-ci; ce report prend la forme d’un pic de consommation nommé CLPU (Cold Load Pick-Up) et qui apparait au moment de la reconnexion. Le CLPU représente un problème qui doit être géré, et sa magnitude dépend des types d’actions de contrôle qu’on veut implanter et aussi des conditions du système électrique (contingence, défaillance d’une unité de production ou besoin de réserve de puissance). Pendant la thèse, le CLPU est contrôlé et optimisé ainsi que la puissance effacée. Un cas d’étude est présenté sur la contribution des actions de gestion de la demande à l‘ajustement entre la demande et la production et l’effet généré sur le réglage secondaire de fréquence. / Environmental challenges and the increasing in electric demand show the importance of considering other form of production while maintaining the safety and reliability of the electrical system. The electrical power systems stability lays on a fundamental constraint: supply and demand must be equal at each instant, so, different solutions are already in place, these solutions include controlling generators’ production during peak periods. But, power units (mainly nuclear, thermal, hydro) capacities are not always sufficient and flexible to follow the demand variations during these periods; an alternative solution to this insufficiency is to make the demand following the electrical power generation by providing bulks of electrical power to the power system by curtailing consumer’s electric load consumption. Such a solution that represents a new organization in the power system industry can be done by Demand Side Management (DSM) actions. The aim of the thesis is to study the possibility to offer services to the electrical system by applying control actions called DR (Demand Response) on different types of electric loads. These DR actions represent partial interruptions of electrical loads’ consumption and especially thermal loads’ consumption.Our choice was based on the thermal electric loads because they store heat respectively in air and water, which can be restored during the control period or interruption. However, there is a negative effect that follows the control of these type of loads because the reduced energy during curtailment period is deferred at the time of reconnection, this deferred power takes the form of a power peak named CLPU (Cold Load Pick-Up), which appears at the time of reconnection. The CLPU is a problem that must be managed, and its magnitude depends on the type of control actions and on the electric system conditions (ie: contingency or failure of a generating unit). In the thesis, the CLPU is controlled and optimized as well as the load reduction during curtailment period. The contribution of control actions in balancing mechanisms and the effect produced on the secondary control of frequency are analyzed.

Graduation date: 2003 / Best scan available on figures. Original figures are dark.

Concern with global climate change has led to the interest in the use of natural refrigerants, such as carbon dioxide, as replacements in heat pump systems. When operating in a transcritical cycle, carbon dioxide heat pumps are well suited for use in high temperature water heating heat pumps. In this work, four systems are analyzed: with and without the use of a suction line heat exchanger, and two water heating schemes. These two schemes involve the heating of water to its desired temperature at a low water flow rate in a single pass through the heat pump, and the heating of water at a high water flow rate, but requiring multiple passes. The performance and resulting heat exchanger size of these four systems is analyzed through the development of an overall system model. This system model uses component-level models that were developed based upon heat exchanger geometry and subsequently validated through experimental testing on a test facility developed for this purpose.

Made available in DSpace on 2016-04-01T17:54:39Z (GMT). No. of bitstreams: 0 Previous issue date: 2007-08-10. Added 1 bitstream(s) on 2016-04-01T18:00:20Z : No. of bitstreams: 1 000505772.pdf: 2673100 bytes, checksum: 0b1ec10e248621594ebb61317344d2af (MD5) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / Este estudo apresenta uma análise numérica dos campos de temperaturas e velocidades d'água durante seu processo de aquecimento via calor sensível no interior de um armazenador térmico cilíndrico, aquecido lateralmente e adiabático em seu topo e base, visando o estudo da condição de operação de um aquecedor de água coletor solar-armazenador integrados (ICSSWH - Integrated Collector-Storage Water Heater). Em uma segunda análise a influência de um defletor interno é estudada pela definição dos campos de velocidades e temperaturas da água. A abordagem numérica é realizada a partir de um modelo bidimensional, transiente, não linear e em coordenadas cilíndricas, discretizada pela técnica de elementos finitos. A construção do modelo é obtida numericamente através de um código computacional desenvolvido em linguagem de programação C. Os resultados numéricos são validados. Análises transientes dos campos de velocidades e temperaturas bem como das temperaturas de mistura e velocidade de carregamento, com e sem parede interna direcionada (defletor interno) são realizadas com a finalidade de estudar a inlfuência da referida parede na convecção livre nessas condições. / This study shows a numerical analysis of the temperature and speed fields of water during the process of heating through sensible heat in the interior of a cylindric thermal storage, heated laterally and with adiabatics top and base, in order to study the operational conditions of an integrated collector-storage solar water heater (ICSSWH). In a second analysis a model with an internal baffle is created and temperature and velocity fields are analysed. The numerical study is done taking into consideration a bidimensional, transient non linear research in cylindric coordenates, discretized by the technique of finite elements. Its solution is obtained numerically through a computational code developed in a C programming language. The numerical results are validated. A transient analysis of the spped and temperature fields so as of the mixing temperatures and the charging speed, with or without the infernal baffle are carried out taking into account the aim of studying the influence of the so called wall in the free convection of those conditions.

Diversos procedimentos têm sido utilizados para destoxicação da torta de mamona. Entre esses a solubilização das substâncias responsáveis pelo caráter tóxico desse resíduo, ricina e ricinina, em água quente e/ou soluções salinas aquecidas. Foram desenvolvidos algo ritmos para simular o aquecimento solar da água como estratégia para baixar custos no processo de destoxicação da torta de mamona, originária do processo de produção de biodiesel. Para isto foi utilizada a ferramenta computacional Simulink/MATLAB@. Foram então analisadas várias situações com base na proposta de aquecimento direto, por se tratar de uma forma de transferência de calor menos dispendiosa. São propostos modelos dinâmicos em diferentes graus de complexidade para uma avaliação prévia do processo de aquecimento da água por meio de energia solar. Apresentam-se os diagramas de blocos dos modelos computacionais, correspondentes a cada uma das etapas de elaboração. Os modelos matemáticos propostos proporcionaram importantes previsões para valores de temperatura nas diferentes fases de elaboração. apresentando-se como importante ferramenta de trabalho para uma próxima etapa que é a de validação experimental do modelo final / Algorithms have been developed in arder to simulate the water solar heating as a strategy for lowering castor bean pie destoxication costs, among from the biodiesel oil for production extraction processo Diverse procedure, substances solubilization, this residue toxic caracter factor, found in hot water and in some saline solutions, motivated this water heating modeling work, through solar energy, since this procedure type can and low cost to the above-mentioned methods, on account of this, one has used computational smulink/matlab in arder to simulate and to arise favorable conditions for this technique use strategies elaboration. One has, then, analized several situation, departing from a termal heating proposal, since this is a less expensive heat transference formo Of this form an objective function was proposal to create O variable that esteem the behavior of the system and better define the excellent conditions for the considered processo .Among these, the established variable as parameters for the simulated conditions, are presented the results, taking itself in account values of income for the process, existing in literature. One porpuses dynamic models, under complexity different degress, for a water heating process previous evaluation, through solar energy. Temperature variations, in the process diferrent stages, have been simulated, with simulink/matlab aid for the above-mentioned system behaviour analysis one presents computational models. blocks diagrams, correspondent to each one of the elaboration stage. Proposed mathematical models provided important previsions for temperature values, in the above-mentioned system different components, resulting as a work important tool for a next stage which is that one of the optimization

Submitted by JOSÉ APARECIDO SILVA DE QUEIROZ null (jqueiroz@unilins.edu.br) on 2016-06-28T17:33:24Z No. of bitstreams: 1 TESE FINAL JOSÉ QUEIROZ.pdf: 1990890 bytes, checksum: 8dbd46996efdf66f13c164f994bd6087 (MD5) / Approved for entry into archive by Juliano Benedito Ferreira (julianoferreira@reitoria.unesp.br) on 2016-06-29T20:20:08Z (GMT) No. of bitstreams: 1 queiroz_jas_dr_bot.pdf: 1990890 bytes, checksum: 8dbd46996efdf66f13c164f994bd6087 (MD5) / Made available in DSpace on 2016-06-29T20:20:08Z (GMT). No. of bitstreams: 1 queiroz_jas_dr_bot.pdf: 1990890 bytes, checksum: 8dbd46996efdf66f13c164f994bd6087 (MD5) Previous issue date: 2016-04-29 / O principal objetivo deste estudo é avaliar, com bases em resultados experimentais, um sistema de aquecimento solar constituído de mangueira de polietileno que permite a transferência do calor gerado pela radiação solar direta e/ou difusa (Energia Solar Térmica) para a água. O sistema foi dimensionado para atender a demanda de um Centro de Ressocialização com capacidade para 220 internos. Justifica-se a escolha do tema pelo fato de que consiste em um assunto atual de grande relevância, principalmente porque vive-se uma crise energética em nível mundial. O estudo comprova através de um experimento a viabilidade do aquecedor solar de baixo custo, considerando-se sua aplicabilidade em locais que demanda grande volume de água aquecida para banho. Os resultados demonstraram que o sistema alternativo proposto atendeu de forma eficiente e econômica a demanda solicitada, o que pode ser adotada pelo poder público em qualquer um de seus segmentos que necessite de água aquecida, com objetivo de reduzir custos e contribuir com o sistema energético brasileiro. O sistema foi analisado para atuar em fluxo continuo e fluxo intermitente, ambos objetivando aquecer a água a temperaturas superiores a 37 °C no inverno. Os resultados alcançados atenderam as expectativas coletando grandes volumes, com temperaturas médias acima de 42 °C. / The aim of this study is to evaluate, with bases on experimental results, a solar heating system consists of polyethylene hose that allows the transfer of heat generated by direct solar radiation and / or diffuse (Solar Thermal Energy) to the water. The system has been designed to meet the demand of a Rehabilitation Center with a capacity for 220 inmates. Justified the choice of the theme for the fact that consists of a current subject of great importance, especially because it lives in an energy crisis worldwide. The study proves through an experiment the viability of solar heater low cost, considering their applicability in places that demand large volume of heated water for bathing. The results showed that the alternative system proposed met efficiently and economically the requested demand, which can be adopted by the government in any of its segments that need heated water, in order to reduce costs and contribute to the Brazilian energy system. The system was analyzed to operate in continuous flow, intermittent flow, both aiming at heating the water to temperatures above 37 °C in winter. The results achieved met the expectations collecting large volumes, with average temperatures above 42 °C.

Orientador: Alcides Padilha / Banca: Vicente Luiz Scalon / Banca: Ricardo Fortes de Miranda / Resumo: Este estudo apresenta uma análise numérica dos campos de temperaturas e velocidades d'água durante seu processo de aquecimento via calor sensível no interior de um armazenador térmico cilíndrico, aquecido lateralmente e adiabático em seu topo e base, visando o estudo da condição de operação de um aquecedor de água coletor solar-armazenador integrados (ICSSWH - Integrated Collector-Storage Water Heater). Em uma segunda análise a influência de um defletor interno é estudada pela definição dos campos de velocidades e temperaturas da água. A abordagem numérica é realizada a partir de um modelo bidimensional, transiente, não linear e em coordenadas cilíndricas, discretizada pela técnica de elementos finitos. A construção do modelo é obtida numericamente através de um código computacional desenvolvido em linguagem de programação C. Os resultados numéricos são validados. Análises transientes dos campos de velocidades e temperaturas bem como das temperaturas de mistura e velocidade de carregamento, com e sem parede interna direcionada (defletor interno) são realizadas com a finalidade de estudar a inlfuência da referida parede na convecção livre nessas condições. / Abstract: This study shows a numerical analysis of the temperature and speed fields of water during the process of heating through sensible heat in the interior of a cylindric thermal storage, heated laterally and with adiabatics top and base, in order to study the operational conditions of an integrated collector-storage solar water heater (ICSSWH). In a second analysis a model with an internal baffle is created and temperature and velocity fields are analysed. The numerical study is done taking into consideration a bidimensional, transient non linear research in cylindric coordenates, discretized by the technique of finite elements. Its solution is obtained numerically through a computational code developed in a C programming language. The numerical results are validated. A transient analysis of the spped and temperature fields so as of the mixing temperatures and the charging speed, with or without the infernal baffle are carried out taking into account the aim of studying the influence of the so called wall in the free convection of those conditions. / Mestre