227 resultados para BOMBAS CENTRÍFUGAS


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Prémio em Contraceção 2012 da Sociedade Portuguesa de Contraceção

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Esta dissertação apresenta um sistema de aquacultura que possibilita a sua monitorização e o seu controlo autónomo. O sistema é capaz de ler grandezas como nível, pH, luminosidade, pressão e temperatura, e, posteriormente, ativar ou desativar os atuadores, como as eletroválvulas e as bombas peristálticas, até que se encontrem os valores pretendidos. O GSM é uma parte relevante do sistema desenvolvido, que permite uma interação à distância com o sistema, utilizando um telemóvel. Em qualquer momento, o utilizador pode pedir informações ao sistema, através de uma solicitação efetuada por mensagem de texto. As informações requeridas podem ser relativas ao estado dos atuadores e aos valores que os sensores apresentam. O utilizador pode, ainda, modificar o estado de um atuador, através de mensagem de texto enviada para o sistema. A resposta ao utilizador é uma mensagem com a verificação do que foi pedido. O sistema permite também ser configurado através de mensagem de texto, definindo os limites de cada parâmetro. Tem, ainda, a capacidade de enviar alertas, via mensagem de texto, quando algum valor estiver fora do pretendido. Apresenta uma aplicação em Visual Basic, que permite interagir com o sistema, controlar os limites e os atuadores, visualizar os alertas emitidos e registá-los em base de dados, para guardar o historial e compreender o comportamento através de gráficos.

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O presente trabalho foi desenvolvido na empresa Renault CACIA e tem como fundamento a implementação de um fluxo de abastecimento com 4 horas de autonomia em todas as linhas de montagem no departamento de fabricação de componentes mecânicos. No entanto, estas linhas deverão ter condições para poder armazenar esse abastecimento, pelo que terão de ser implementadas estruturas que o suportem. Com o objetivo de eliminar o excesso de stock existente na linha de montagem de bombas de óleo, a mais crítica da instalação, e as atividades que não acrescentam valor ao produto final, organizar o espaço disponível, melhorar as condições ergonómicas, propõem-se soluções que serão uma mais-valia para as empresas de fabricação. Durante o desenvolvimento do trabalho foi realizado um estudo aprofundado da linha de montagem e dos problemas existentes no processo de abastecimento e, posteriormente, foi determinada a quantidade necessária de embalagens de componentes para a autonomia requerida. Recorreu-se à ferramenta CAD 3D, Solidworks®, para o planeamento das estruturas, e ao software de simulação Arena®, para testar o funcionamento da linha de montagem com a implementação das estruturas para abastecimento. Verificaram-se melhorias conseguidas através da implementação das soluções sugeridas. A linha de montagem ficou mais organizada e arrumada, tendo-se reduzido cerca de 86,96% de stock global existente. Associado a este, existiam atividades realizadas pelo operador de montagem que não acrescentavam valor ao produto final, tendo-se obtido um incremento da produção na ordem de 1%.

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In the last years the need to develop more environmentally friendly and efficient cars as led to the development of several technologies to improve the performance of internal combustion engines, a large part of the innovations are focused in the auxiliary systems of the engine, including, the oil pump, this is an element of great importance in the dynamics of the engine as well a considerable energy consumer. Most solutions for oil pumps to this day are fixed displacement, for medium and high speeds, the pump flow rate is higher than the needs of the engine, this excess flow leads to the need for recirculation of the fluid which represents a waste of energy. Recently, technological advances in this area have led to the creation of variable displacement oil pumps, these have become a 'must have' due to the numerous advantages they bring, although the working principle of vane or piston pumps is relatively well known, the application of this technology for the automotive industry is new and brings new challenges. The focus of this dissertation is to develop a new concept of variable displacement system for automotive oil pumps. The main objective is to obtain a concept that is totally adaptable to existing solutions on the market (engines), both dimensionally as in performance specifications, having at the same time an innovative mechanical system for obtaining variable displacement. The developed design is a vane pump with variable displacement going in line with existing commercial solutions, however, the variation of the eccentricity commonly used to provide an variable displacement delivery is not used, the variable displacement is achieved without varying the eccentricity of the system but with a variation of the length of the pumping chamber. The principle of operation of the pump is different to existing solutions while maintaining the ability to integrate standard parts such as control valves and mechanical safety valves, the pump is compatible with commercial solutions in terms of interfaces for connection between engine systems and pump. A concept prototype of the product was obtained in order to better evaluate the validity of the concept. The developed concept represents an innovation in oil pumps design, being unique in its mechanical system for variable displacement delivery.

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INTRODUCTION: The current study aimed to describe the relational and reproductive trajectories leading to adolescent pregnancy in Portugal, and to explore whether there were differences in this process according to adolescents' place of residence. MATERIAL AND METHODS: Data were collected between 2008 and 2013 in 42 public health services using a self-report questionnaire developed by the researchers. The sample consisted of a nationally representative group of pregnant adolescents (n = 459). RESULTS: Regardless of having had one (59.91%) or multiple sexual partners (40.09%), the majority of adolescents became pregnant in a romantic relationship, using contraception at the time of the conception and knowing the contraceptive failure which led to pregnancy (39.22%). In some regions other trajectories were highly prevalent, reflecting options such as planning the pregnancy (Alentejo Region/ Azores Islands), not using contraception (Centro Region/Madeira Islands) or using it incorrectly, without identifying the contraceptive failure (Madeira Islands). On average, romantic relationships were longer than 19 months and adolescents' partners were older than themselves (> 4 years) and no longer in school (75.16%); these results were particularly significant when the pregnancy was planned. DISCUSSION: The knowledge gained in this study shows that prevention efforts must be targeted according to the adolescents' needs in each region and should include high-risk male groups. CONCLUSION: Our results may enable more efficient health policies to prevent adolescent pregnancy in different country regions and support educators and health care providers on sexual education and family planning efforts.

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Prémio em Contraceção 2012 da Sociedade Portuguesa de Contraceção

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Remifentanil es un nuevo agonista de los receptores, metabolizado rápidamente por las esterasas inespecíficas en la sangre y en los tejidos, sin depender de ningún órgano y sus metabolitos que se producen son inactivos. Debido a su perfil farmacológico único, la anestesia basada en remifentanil combina una anestesia opioide, segura y profunda durante la cirugía, con una recuperación rápida y predecible. Presenta ventajas como la estabilidad hemodinámica, especialmente durante la intuvacion endotraqueal y la incisión cutánea, así como un reducido riesgo de depresión respiraroria en el post-operativo. Comparado con la técnica clásica convencional Fentanil-desfluorano, cuyo límite era el miedo a la sobredosificación de opioides por lo que se realiza control de la anestesia, en base a un inhalatorio, la utilización del remifentanil en bombas de infusión probablemente cambiará nuestros métodos actuales de administración de la anestesia

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One of the challenges to biomedical engineers proposed by researchers in neuroscience is brain machine interaction. The nervous system communicates by interpreting electrochemical signals, and implantable circuits make decisions in order to interact with the biological environment. It is well known that Parkinson’s disease is related to a deficit of dopamine (DA). Different methods has been employed to control dopamine concentration like magnetic or electrical stimulators or drugs. In this work was automatically controlled the neurotransmitter concentration since this is not currently employed. To do that, four systems were designed and developed: deep brain stimulation (DBS), transmagnetic stimulation (TMS), Infusion Pump Control (IPC) for drug delivery, and fast scan cyclic voltammetry (FSCV) (sensing circuits which detect varying concentrations of neurotransmitters like dopamine caused by these stimulations). Some softwares also were developed for data display and analysis in synchronously with current events in the experiments. This allowed the use of infusion pumps and their flexibility is such that DBS or TMS can be used in single mode and other stimulation techniques and combinations like lights, sounds, etc. The developed system allows to control automatically the concentration of DA. The resolution of the system is around 0.4 µmol/L with time correction of concentration adjustable between 1 and 90 seconds. The system allows controlling DA concentrations between 1 and 10 µmol/L, with an error about +/- 0.8 µmol/L. Although designed to control DA concentration, the system can be used to control, the concentration of other substances. It is proposed to continue the closed loop development with FSCV and DBS (or TMS, or infusion) using parkinsonian animals models.

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La relación más importante entre los países está sustentada en el comercio internacional, por lo que su actividad origina una fuerza de desarrollo económico; las importaciones permiten a los inversionistas y empresas adquirir productos que en su país no se fabrican, facilita adquirirlos de acuerdo a las características y atributos específicos, a precios bajos y de buena calidad para enfrentar con éxito a la competencia. La presente investigación plantea el desarrollo de un plan de importación de Sistemas Hidráulicos fabricados en Centro y Sur América que contribuya con información confiable para los inversionistas y empresas ferreteras que deseen incursionar en la comercialización de bombas de agua provenientes de esas regiones, el plan de importación de Sistemas de bombeo de agua procedentes de dichas regiones es una herramienta que brinda los pasos a seguir en el proceso, iniciando desde el momento de inscribirse como importador hasta el despacho de la mercadería, de forma específica para este producto. El plan se desarrolla en tres capítulos de la siguiente manera: En el capítulo uno, el marco teórico contiene características del comercio internacional, comercio exterior, principalmente sus ventajas, se exponen generalidades sobre las importaciones, e información relevante sobre el producto a importar, de igual forma un marco legal que es el que regula las diferentes actividades relacionadas a la importación. En el capítulo dos se desarrolla la metodología de la investigación, tabulación e interpretación de los resultados obtenidos. Además, se describen las conclusiones y recomendaciones derivadas de la investigación. El capítulo tres contiene la propuesta del plan de importación de Sistemas de bombeo de agua que se llevaría a cabo desde Sur América hacia El Salvador, en el cual con la investigación de determino que Brasil, Argentina, Chile y Colombia son los fabricantes de estos productos, se detalla cada paso a seguir en dicha importación, y finalmente, se presenta la bibliografía consultada para el desarrollo del documento y los anexos como soporte de la investigación.

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The system built to characterize electrodes and, consequently, deposited fine films are constituted by a hollow cathode that works to discharges and low pressures (approximately 10-3 to 5 mbar), a source DC (0 to 1200 V), a cylindrical camera of closed borossilicato for flanges of stainless steel with an association of vacuum bombs mechanical and spread. In the upper flange it is connected the system of hollow cathode, which possesses an entrance of gas and two entrances for its refrigeration, the same is electrically isolated of the rest of the equipment and it is polarized negatively. In front of the system of hollow cathode there is a movable sample in stainless steel with possibility of moving in the horizontal and vertical. In the vertical, the sample can vary its distance between 0 and 70 mm and, in the horizontal, can leave completely from the front of the hollow cathode. The sample and also the cathode hollow are equipped with cromel-alumel termopares with simultaneous reading of the temperatures during the time of treatment. In this work copper electrodes, bronze, titanium, iron, stainless steel, powder of titanium, powder of titanium and silício, glass and ceramic were used. The electrodes were investigated relating their geometry change and behavior of the plasma of the cavity of hollow cathode and channel of the gas. As the cavity of hollow cathode, the analyzed aspects were the diameter and depth. With the channel of the gas, we verified the diameter. In the two situations, we investigated parameters as flow of the gas, pressure, current and applied tension in the electrode, temperature, loss of mass of the electrode with relationship at the time of use. The flow of gas investigated in the electrodes it was fastened in a work strip from 15 to 6 sccm, the constant pressure of work was among 2.7 to 8 x 10-2 mbar. The applied current was among a strip of work from 0,8 to 0,4 A, and their respective tensions were in a strip from 400 to 220 V. Fixing the value of the current, it was possible to lift the curve of the behavior of the tension with the time of use. That curves esteem in that time of use of the electrode to its efficiency is maximum. The temperatures of the electrodes were in the dependence of that curves showing a maximum temperature when the tension was maximum, yet the measured temperatures in the samples showed to be sensitive the variation of the temperature in the electrodes. An accompaniment of the loss of mass of the electrode relating to its time of use showed that the electrodes that appeared the spherical cavities lost more mass in comparison with the electrodes in that didn't appear. That phenomenon is only seen for pressures of 10-2 mbar, in these conditions a plasma column is formed inside of the channel of the gas and in certain points it is concentrated in form of spheres. Those spherical cavities develop inside of the channel of the gas spreading during the whole extension of the channel of the gas. The used electrodes were cut after they could not be more used, however among those electrodes, films that were deposited in alternate times and the electrodes that were used to deposit films in same times, those films were deposited in the glass substrata, alumina, stainless steel 420, stainless steel 316, silício and steel M2. As the eletros used to deposit films in alternate time as the ones that they were used to deposit in same times, the behavior of the thickness of the film obeyed the curve of the tension with relationship the time of use of the electrode, that is, when the tension was maximum, the thickness of the film was also maximum and when the tension was minimum, the thickness was minimum and in the case where the value of the tension was constant, the thickness of the film tends to be constant. The fine films that were produced they had applications with nano stick, bio-compatibility, cellular growth, inhibition of bacterias, cut tool, metallic leagues, brasagem, pineapple fiber and ornamental. In those films it was investigated the thickness, the adherence and the uniformity characterized by sweeping electronic microscopy. Another technique developed to assist the production and characterization of the films produced in that work was the caloteste. It uses a sphere and abrasive to mark the sample with a cap impression, with that cap form it is possible to calculate the thickness of the film. Through the time of life of the cathode, it was possible to evaluate the rate of waste of its material for the different work conditions. Values of waste rate up to 3,2 x 10-6 g/s were verified. For a distance of the substratum of 11 mm, the deposited film was limited to a circular area of 22 mm diameter mm for high pressures and a circular area of 75 mm for pressure strip. The obtained films presented thickness around 2,1 µm, showing that the discharge of arch of hollow cathode in argon obeys a curve characteristic of the tension with the time of life of the eletrodo. The deposition rate obtained in this system it is of approximately 0,18 µm/min

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El Archivo del Patrimonio Fotográfico y Fílmico del Valle del Cauca es responsabilidad de la Biblioteca Departamental del Valle Jorge Garcés Borrero, por convenio de cooperación suscrito con la Secretaria del Cultura Departamental, con el fin de aunar esfuerzos para su conservación, preservación y divulgación del Archivo entre la comunidad Vallecaucana, especialmente entre los estudiantes e investigadores que visitan la Biblioteca, propiciando el su uso y consulta permanente. La universidad Icesi es un colaborador en el proceso de difusión, facilitando la tecnología que permite la consulta de las imágenes.

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The petroleum production pipeline networks are inherently complex, usually decentralized systems. Strict operational constraints are applied in order to prevent serious problems like environmental disasters or production losses. This paper describes an intelligent system to support decisions in the operation of these networks, proposing a staggering for the pumps of transfer stations that compose them. The intelligent system is formed by blocks which interconnect to process the information and generate the suggestions to the operator. The main block of the system uses fuzzy logic to provide a control based on rules, which incorporate knowledge from experts. Tests performed in the simulation environment provided good results, indicating the applicability of the system in a real oil production environment. The use of the stagger proposed by the system allows a prioritization of the transfer in the network and a flow programming

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La crisis financiera y social surgida en Occidente durante el 2008 ha supuesto un punto de inflexión que aglutina la acumulación de los diversos defectos ocultos que ya venían incorporando las democracias del viejo continente. La gran recesión habría facilitado el desencadenamiento de protestas sociales, las cuales contienen demandas en contra de los procesos originados por el establishment europeo a través de políticas de contención del gasto social (austeridad), o bien enfatizando desfavorablemente ante el progreso en el proceso de integración europea. Estos reclamos sociales, a su vez, pueden haber propiciado un nuevo escenario de competencia partidista según los casos, con tendencias centrífugas en algunos sistemas de partidos concomitantes de la Unión Europea, lo que habría supuesto la aparición de nuevos actores políticos o, en algunos casos, la vuelta de “siglas resucitadas”. En ambos casos, éstos actores serían ahora capaces de capitalizar electoralmente new issues provocando realineamientos en el electorado. La articulación de estos nuevos potenciales políticos permite, a través de la localización de fallos en el mercado electoral, abrir ventanas de oportunidad en la arena electoral para nuevos actores políticos que estarían modificando sustancialmente los sistemas de partidos en la Unión Europea. Dado este contexto, la siguiente investigación pretende analizar a través de un estudio comparado de cuatro casos seleccionados (España, Grecia, Italia y el Reino Unido), hasta qué punto ciertas variables contribuyen a modificar las preferencias y conductas políticas de la ciudadanía de estos países. Se estudia a través de diversos indicadores e índices la evolución del gasto social en cada caso, la presencia de euroescepticismo, así como la postura y contenidos programáticos de nuevos actores políticos en torno a estos temas. Este estudio pretende centrarse en la figura del partido político, más concretamente en la teoría de los nuevos partidos políticos, en respuesta a las recientes percepciones de volatilidad en algunos países comunitarios. Siendo así que se pretenderá reconocer algunas notas destacables de sus planteamientos programáticos, su fuerza parlamentaria y la incidencia que tienen en el sistema de partidos que integran.

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Introducción. Los trabajadores de los talleres de reparación de automóviles conviven diariamente con la exposición a los solventes orgánicos, exposición que se convierte en un riesgo para su salud que generalmente en el corto plazo se presenta como déficits de concentración, memoria y tiempo de reacción y en el largo plazo produciendo graves repercusiones clínicas como efectos mutagénicos y carcinogénicos. Objetivo. Caracterizar las condiciones higiénicas y de seguridad de trabajadores ocupacionalmente expuestos a solventes orgánicos y determinar los niveles ambientales de benceno, tolueno y xileno (BTX) en talleres de lámina y pintura automotriz de la ciudad de Bogotá. Materiales y métodos. Se hizo un estudio de corte transversal en 60 trabajadores que laboran expuestos a solventes orgánicos en talleres de reparación automotriz en Bogotá. Se realizó una encuesta con variables sociodemográficas, laborales y se determinaron los niveles en aire de benceno, tolueno y xileno. Para los muestreos ambientales, las bombas se colocaron en una posición fija representativa del ambiente general, con el objeto de conocer la distribución de los solventes en el área de trabajo. Se realizó un análisis descriptivo por conteos de frecuencia, medidas de tendencia central y dispersión. Se utilizó prueba de bondad de ajuste para distribución normal (Kolmogorov-Smirnov o Shapiro Wilk), prueba t Student para comparación de medias, o en su defecto prueba U de Mann Whitney para comparación de medianas. Para identificar la relación entre las características sociodemográficas y ocupacionales con la exposición a BTX, se utilizaron pruebas de asociación Chi cuadrado o análisis de correlación según la naturaleza de las variables. El nivel de significancia para cada prueba fue 0.05. Resultados. La edad promedio de los trabajadores fue de 43 años y un tiempo total de exposición a solventes de 20 años. Respecto al uso de protección corporal, 45 (75%) de los trabajadores manifestaron que usaban uniforme, mientras que 14 (23,3%) usaban ropa de calle durante la jornada laboral. El 46,7% manifestaron usar protección respiratoria. La concentración de benceno en aire fue entre 0,1 y 0,45 mg/l (mediana de 0,31 mg/l; DE 0,13 mg/l); la de tolueno estuvo entre 8,25 y 27,22 mg/l (mediana de 14,5 mg/l; DE 6.99 mg/l) y la de xileno entre 19,34 y 150,15 mg/l (mediana de 70,12 mg/l; DE 40,82 mg/l). Conclusión. Los pintores de automóviles están expuestos a niveles elevados de solventes en los lugares de trabajo y no cuentan con condiciones de higiene y seguridad industrial adecuados. Un gran número de pintores son informales lo que les impide el acceso a los beneficios del Sistema de Seguridad Social Integral.