Construção de um aparato experimental para monitoramento in situ da deposição de filmes finos de titânio por magnetron sputtering

The technique of surface coating using magnetron sputtering is one of the most widely used in the surface engineering, for its versatility in obtaining different films as well as in the micro / nanometric thickness control. Among the various process parameters, those related to the active species of the plasma are of the most fundamental importance in the mechanism and kinetics of deposition. In order to identify the active species of the plasma, parameters such as gas flow, pressure and density of electric power were varied during titanium coating on glass substrate. By flowing argon gas of 10, 20, 30, 40 and 50 sccm (cubic centimeters per minute) for each gas flow a sequential scan of the electric current of 0.10, 0.20, 0.30, 0.40 , 0.50 A. The maximum value of 0.50 A was chosen based both on literature data and on limitations of the equipment. The monitoring of plasma species present during the deposition was carried out in situ by the technique of optical emission spectroscopy (OES) through the spectrometer Ocean Optics USB2000 Series. For this purpose, an apparatus was developed to adapt the OES inside the plasma reactor to stay positioned closest to the target. The radiations emitted by the species were detected by an optical fiber placed behind the glass substrate and their intensities as a function of wavelength were, displayed on a monitor screen. The acquisition time for each condition of the plain parameters was related to the minima of spectral lines intensities due to the film formed on the substrate. The intensities of different emission lines of argon and titanium were then analyzed as a function of time, to determine the active species and estimate the thickness of the deposited films. After the deposition, the coated glasses thin films were characterized by optical transmittance through an infrared laser. It was found that the thickness and deposition rate determined by in situ analysis were consistent with the results obtained by laser transmittance

Estudo da aplicação de molas magnéticas na recolha da energia de fontes renováveis

Dissertação de Mestrado, Engenharia Elétrica e Eletrónica, Especialização em Sistemas de Energia e Controlo, Instituto Superior de Engenharia, Universidade do Algarve, 2016

Valoración de la Electrificadora del Meta S.A. ESP – EMSA ESP

El objetivo del presente estudio es establecer el valor de la Electrificadora del Meta SA ESP EMSA ESP, para ello se hace una revisión general del departamento del Meta, el sector eléctrico Colombiano, y la EMSA ESP, se revisa la forma como la actividad empresarial de EMSA ESP en su papel de distribuidor y comercializador de energía eléctrica ha influido en el desarrollo y crecimiento de las comunidades del departamento del Meta -- El análisis finalmente establece el valor económico de EMSA ESP mediante el uso de la metodología de flujos de caja descontados tomando como base la información pública disponible de la Compañía y las proyecciones de los estados financieros necesarios para realizar la valoración; dado que se trata de una valoración externa e independiente de algún interés particular se presenta este ejercicio para que sirva como herramienta para la toma decisiones de inversión, pues se concluye que EMSA ESP es atractiva para los inversionistas si se tiene en cuenta los desarrollos económicos que se están presentando en el departamento del Meta y la Orinoquia Colombiana que genera una expectativa positiva en cuanto a su viabilidad económica y financiera para los próximos 10 años

Análisis del impacto de ampliar la cobertura de la oferta de energía prepago en Antioquia

El presente documento muestra un análisis sobre las decisiones, ventajas y desventajas asociadas con la ampliación de la cobertura de la oferta de energía prepago que tiene el Grupo EPM -- Todo esto evidenciado desde un punto de vista financiero y social que permitan conocer en detalle las implicaciones de esta decisión -- El Grupo EPM tiene en su propósito, la construcción de territorios sostenibles en todos los lugares donde tenga presencia -- Antioquia representa su mercado natural de origen, donde tiene el mayor porcentaje de usuarios y en sus objetivos siempre ha estado presente realizar intervenciones que permitan mejorar las condiciones de vida a través de soluciones de acceso y comprabilidad -- El Grupo siempre está en una constante búsqueda de generar valor agregado a los usuarios y desarrollar ofertas que permitan el disfrute de los servicios públicos domiciliarios, entendiendo las diferentes realidades y circunstancias que se viven en los territorios -- Una de las alternativas más exitosas desarrolladas por la empresa y en la cual ha sido líder en el mercado, es el esquema de energía prepago implementado desde el 2006 -- La energía prepago fue estructurada como una oferta que generaría beneficio para el Grupo representado en unos menores costos en los servicios de reconexión, suspensiones, cortes y unas mejoras en los índices de recaudo, para los usuarios les daba un mayor control sobre sus consumos y poder tener una forma de pago que se ajustara a la forma como reciben los ingresos -- La iniciativa ha dejado unos resultados positivos, sin embargo en las diferentes investigaciones y encuestas de satisfacción se identifica una oportunidad de mejora, debido a que algunos usuarios manifestaban el deseo y necesidad de hacer parte de esta oferta pero se les negaba el acceso debido a que no cumplían con las condiciones de entrada, razón por la cual se decidió realizar un análisis de estas condiciones de entrada y revisar la posibilidad de implementar algunos cambios -- El objetivo de esta investigación será hacer un análisis de la oferta de energía prepago actual de EPM para inferir algunos impactos económicos, sociales y regulatorios que tendría para el Grupo aumentar la cobertura de su mercado objetivo, contribuyendo así a mejorar la situación de comprabilidad de las comunidades vulnerables del Departamento de Antioquia -- Para ello se realiza un análisis de factibilidad de ampliar el esquema de energía prepago a partir de un modelo financiero y los resultados de talleres e investigaciones de percepción de los usuarios atendidos bajo esta modalidad

Modelagem e análise de um dispositivo mitigador de flecha para linhas de transmissão de energia elétrica baseado em ligas com memória de forma

Dissertação (mestrado)—Universidade de Brasília, Faculdade de Tecnologia, Departamento de Engenharia Mecânica, 2016.

Packaging and Deployment of Large Planar Spacecraft Structures

This thesis presents a set of novel methods to biaxially package planar structures by folding and wrapping. The structure is divided into strips connected by folds that can slip during wrapping to accommodate material thickness. These packaging schemes are highly efficient, with theoretical packaging efficiencies approaching 100%. Packaging tests on meter-scale physical models have demonstrated packaging efficiencies of up to 83%. These methods avoid permanent deformation of the structure, allowing an initially flat structure to be deployed to a flat state.

Also presented are structural architectures and deployment schemes that are compatible with these packaging methods. These structural architectures use either in-plane pretension -- suitable for membrane structures -- or out-of-plane bending stiffness to resist loading. Physical models are constructed to realize these structural architectures. The deployment of these types of structures is shown to be controllable and repeatable by conducting experiments on lab-scale models.

These packaging methods, structural architectures, and deployment schemes are applicable to a variety of spacecraft structures such as solar power arrays, solar sails, antenna arrays, and drag sails; they have the potential to enable larger variants of these structures while reducing the packaging volume required. In this thesis, these methods are applied to the preliminary structural design of a space solar power satellite. This deployable spacecraft, measuring 60 m x 60 m, can be packaged into a cylinder measuring 1.5 m in height and 1 m in diameter. It can be deployed to a flat configuration, where it acts as a stiff lightweight support framework for multifunctional tiles that collect sunlight, generate electric power, and transmit it to a ground station on Earth.

Energy harvesting from hydroelectric systems for remote sensors

Hydroelectric systems are well-known for large scale power generation. However, there are virtually no studies on energy harvesting with these systems to produce tens or hundreds of milliwatts. The goal of this work was to study which design parameters from large-scale systems can be applied to small-scale systems. Two types of hydro turbines were evaluated. The first one was a Pelton turbine which is suitable for high heads and low flow rates. The second one was a propeller turbine used for low heads and high flow rates. Several turbine geometries and nozzle diameters were tested for the Pelton system. For the propeller, a three-bladed turbine was tested for different heads and draft tubes. The mechanical power provided by these turbines was measured to evaluate the range of efficiencies of these systems. A small three-phase generator was developed for coupling with the turbines in order to evaluate the generated electric power. Selected turbines were used to test battery charging with hydroelectric systems and a comparison between several efficiencies of the systems was made. Keywords

Avoided losses on LV networks as a result of microgeneration

In the scope of the discussions about microgeneration (and microgrids), the avoided electrical losses are often pointed out as an important value to be credited to those entities. Therefore, methods to assess the impact of microgeneration on losses must be developed in order to support the definition of a suitable regulatory framework for the economic integration of microgeneration on distribution networks. This paper presents an analytical method to quantify the value of avoided losses that microgeneration may produce on LV networks. Intervals of expected avoided losses are used to account for the variation of avoided losses due to the number, size and location of microgenerators, as well as for the kind of load distribution on LV networks.

Assessing the contribution of microgrids to the reliability of distribution networks

The emergence of microgeneration has recently lead to the concept of microgrid, a network of LV consumers and producers able to export electric energy in some circumstances and also to work in an isolated way in emergency situations. Research on the organization of microgrids, control devices, functionalities and other technical aspects is presently being carried out, in order to establish a consistent technical framework to support the concept. The successful development of the microgrid concept implies the definition of a suitable regulation for its integration on distribution systems. In order to define such a regulation, the identification of costs and benefits that microgrids may bring is a crucial task. Actually, this is the basis for a discussion about the way global costs could be divided among the different agents that benefit from the development of microgrids. Among other aspects, the effect of microgrids on the reliability of the distribution network has been pointed out as an important advantage, due to the ability of isolated operation in emergency situations. This paper identifies the situations where the existence of a microgrid may reduce the interruption rate and duration and thus improve the reliability indices of the distribution network. The relevant expressions necessary to quantify the reliability are presented. An illustrative example is included, where the global influence of the microgrid in the reliability is commented.