Field Measurements of a Full Scale Tidal Device

Field testing studies are required for tidal turbine device developers to determine the performance of their turbines in tidal flows. Full-scale testing of the SCHOTTEL tidal turbine has been conducted at Queen’s University Belfast’s tidal site at Strangford Lough, NI. The device was mounted on a floating barge. Testing was conducted over 48 days, for 288 h, during flood tides in daylight hours. Several instruments were deployed, resulting in an expansive data set. The performance results from this data set are presented here. The device, rated to 50 kW at 2.75 m/s was tested in flows up to 2.5 m/s, producing up to 19 kW, when time-averaged. The thrust on the turbine reached 17 kN in the maximum flow. The maximum system efficiency of the turbine in these flows reached 35%. The test campaign was very successful and further tests may be conducted at higher flow speeds in a similar tidal environment.

Three-port DC-DC Converter for Stand-Alone Photovoltaic Systems

System efficiency and cost effectiveness are of critical importance for photovoltaic (PV) systems. This paper addresses the two issues by developing a novel three-port DC-DC converter for stand-alone PV systems, based on an improved Flyback-Forward topology. It provides a compact single-unit solution with a combined feature of optimized maximum power point tracking (MPPT), high step-up ratio, galvanic isolation and multiple operating modes for domestic and aerospace applications. A theoretical analysis is conducted to analyze the operating modes followed by simulation and experimental work. The paper is focused on a comprehensive modulation strategy utilizing both PWM and phase-shifted control that satisfies the requirement of PV power systems to achieve MPPT and output voltage regulation. A 250 W converter was designed and prototyped to provide experimental verification in term of system integration and high conversion efficiency.

Investigations Into the Performance of a Turbogenerated Biogas Engine During Speed Transients

Turbogenerating is a form of turbocompounding whereby a Turbogenerator is placed in the exhaust stream of an internal combustion engine. The Turbogenerator converts a portion of the expelled energy in the exhaust gas into electricity which can then be used to supplement the crankshaft power. Previous investigations have shown how the addition of a Turbogenerator can increase the system efficiency by up to 9%. However, these investigations pertain to the engine system operating at one fixed engine speed. The purpose of this paper is to investigate how the system and in particular the Turbogenerator operate during engine speed transients. On turbocharged engines, turbocharger lag is an issue. With the addition of a Turbogenerator, these issues can be somewhat alleviated. This is done by altering the speed at which the Turbogenerator operates during the engine’s speed transient. During the transients, the Turbogenerator can be thought to act in a similar manner to a variable geometry turbine where its speed can cause a change in the turbocharger turbine’s pressure ratio. This paper shows that by adding a Turbogenerator to a turbocharged engine the transient performance can be enhanced. This enhancement is shown by comparing the turbogenerated engine to a similar turbocharged engine. When comparing the two engines, it can be seen that the addition of a Turbogenerator can reduce the time taken to reach full power by up to 7% whilst at the same time, improve overall efficiency by 7.1% during the engine speed transient.

Runtime Support for Adaptive Power Capping on Heterogeneous SoCs

Power capping is a fundamental method for reducing the energy consumption of a wide range of modern computing environments, ranging from mobile embedded systems to datacentres. Unfortunately, maximising performance and system efficiency under static power caps remains challenging, while maximising performance under dynamic power caps has been largely unexplored. We present an adaptive power capping method that reduces the power consumption and maximizes the performance of heterogeneous SoCs for mobile and server platforms. Our technique combines power capping with coordinated DVFS, data partitioning and core allocations on a heterogeneous SoC with ARM processors and FPGA resources. We design our framework as a run-time system based on OpenMP and OpenCL to utilise the heterogeneous resources. We evaluate it through five data-parallel benchmarks on the Xilinx SoC which allows fully voltage and frequency control. Our experiments show a significant performance boost of 30% under dynamic power caps with concurrent execution on ARM and FPGA, compared to a naive separate approach.

Economic optimization of wind farms in function of the cost of energy produced

Esta tese apresenta um estudo sobre otimização económica de parques eólicos, com o objetivo de obter um algoritmo para otimização económica de parques eólicos através do custo da energia produzida. No estudo utilizou-se uma abordagem multidisciplinar. Inicialmente, apresentam-se as principais tecnologias e diferentes arquiteturas utilizadas nos parques eólicos. Bem como esquemas de funcionamento e gestão dos parques. São identificadas variáveis necessárias e apresenta-se um modelo dimensionamento para cálculo dos custos da energia produzida, tendo-se dado ênfase às instalações onshore e ligados a rede elétrica de distribuição. É feita uma análise rigorosa das características das topologias dos aerogeradores disponíveis no mercado, e simula-se o funcionamento de um parque eólico para testar a validade dos modelos desenvolvidos. Também é implementado um algoritmo para a obtenção de uma resposta otimizada para o ciclo de vida económico do parque eólico em estudo. A abordagem proposta envolve algoritmos para otimização do custo de produção com multiplas funções objetivas com base na descrição matemática da produção de eletricidade. Foram desenvolvidos modelos de otimização linear, que estabelece a ligação entre o custo económico e a produção de eletricidade, tendo em conta ainda as emissões de CO2 em instrumentos de política energética para energia eólica. São propostas expressões para o cálculo do custo de energia com variáveis não convencionais, nomeadamente, para a produção variável do parque eólico, fator de funcionamento e coeficiente de eficiência geral do sistema. Para as duas últimas, também é analisado o impacto da distribuição do vento predominante no sistema de conversão de energia eólica. Verifica-se que os resultados obtidos pelos algoritmos propostos são similares às obtidas por demais métodos numéricos já publicados na comunidade científica, e que o algoritmo de otimização económica sofre influência significativa dos valores obtidos dos coeficientes em questão. Finalmente, é demonstrado que o algoritmo proposto (LCOEwso) é útil para o dimensionamento e cálculo dos custos de capital e O&M dos parques eólicos com informação incompleta ou em fase de projeto. Nesse sentido, o contributo desta tese vem ser desenvolver uma ferramenta de apoio à tomada de decisão de um gestor, investidor ou ainda agente público em fomentar a implantação de um parque eólico.

A data-mining based methodology for wind forecasting

In many countries the use of renewable energy is increasing due to the introduction of new energy and environmental policies. Thus, the focus on the efficient integration of renewable energy into electric power systems is becoming extremely important. Several European countries have already achieved high penetration of wind based electricity generation and are gradually evolving towards intensive use of this generation technology. The introduction of wind based generation in power systems poses new challenges for the power system operators. This is mainly due to the variability and uncertainty in weather conditions and, consequently, in the wind based generation. In order to deal with this uncertainty and to improve the power system efficiency, adequate wind forecasting tools must be used. This paper proposes a data-mining-based methodology for very short-term wind forecasting, which is suitable to deal with large real databases. The paper includes a case study based on a real database regarding the last three years of wind speed, and results for wind speed forecasting at 5 minutes intervals.

Projecto e concepção de instalação frigorífica a NH3, para uma unidade de congelação de frangos em contínuo, na Venezuela

Trabalho Final de Mestrado para obtenção do grau de Mestre em Engenharia Mecânica

A eficácia dos contratos-programa no setor público da saúde na região Norte de Portugal

Em Portugal o sistema de saúde assume uma importante função no desenvolvimento económico e social, na medida em que os serviços prestados pelo mesmo influenciam não só o bem-estar social como também a produtividade. O processo de contratualização alia-se ao setor público da saúde através do contrato-programa, o qual pretende estabelecer uma estratégia a seguir. O presente trabalho pretende verificar se o setor público da saúde respeita os princípios de economia, eficiência e eficácia, de um modo geral, pretende-se perceber se os contratos-programa são cumpridos na sua totalidade. Para tal procedeu-se à recolha da informação descrita nos relatórios de gestão dos quinze Hospitais que pertencem à Administração Regional de Saúde do Norte. A incerteza relacionada com os contratos-programa, a não existência de um modelo linear para a divulgação pública dos resultados no âmbito do contrato-programa, e ainda o facto de a totalidade das entidades não ser obrigada a emitir essa publicação, conduz à possibilidade de que não estejam a ser cumpridos os princípios da economia, eficácia e eficiência.

Development and parametric studies of pulsed nitrogen and d-switched nd:glass lasers and some of their applications

Laser engineering is an area in which developments in the existing design concepts and technology appear at an alarming rate. Now—a-days, emphasis has shifted from innovation to cost reduction and system improvement. To a major extent, these studies are aimed at attaining larger power densities, higher system efficiency and identification of new lasing media and new lasing wavelengths. Todate researchers have put to use all the ditferent Forms of matter as lasing material. Laser action was observed For the first time in a gaseous system - the He-Ne system. This was Followed by a variety of solidstate and gas laser systems. Uarious organic dyes dissolved in suitable solvents were found to lase when pumped optically. Broad band emission characteristics of these dye molecules made wavelength tuning possible using optical devices. Laser action was also observed in certain p-n junctions of semiconductor materials and some of these systems are also tunable. The recent addition to this list was the observation of laser action from certain laser produced plasmas. The purpose of this investigation was to examine the design and Fabrication techniques of pulsed Nitrogen lasers and high power Nd: Glass laserso Attempt was also made to put the systems developed into certain related experiments

Percepción de los trabajadores acerca del sistema de seguridad y salud en el trabajo en un hospital de III nivel, Bogotá-Colombia. 2014.

Objetivo: Evaluar la percepción que tienen los trabajadores acerca del sistema de seguridad y salud en el trabajo en la población asistencial y administrativa en un Hospital de III nivel de atención., Bogotá-Colombia. Materiales y métodos: Estudio de corte transversal en población de trabajadores asistenciales y administrativos. Se aplicó el “Cuestionario Nórdico Sobre Seguridad en el Trabajo NOSACQ 50 Spanish” validado. La muestra fue probabilística estratificada aleatoria, en 308 trabajadores (230 asistenciales y 78 administrativos). Resultados: El promedio de edad fue 39.5± 12 años, con mayor frecuencia de género femenino (74.68%), estado civil soltero (38.96%) y nivel educativo técnico (34.40%). La percepción que tienen los trabajadores acerca del sistema de seguridad y salud en el trabajo fue independiente de su tipo de actividad laboral administrativa y asistencial (p>0.05), la mayor percepción en ambos grupos fue la confianza de los trabajadores en la eficacia del sistema de seguridad (2.71 y 2.77), y las de menor percepción presentaron el empoderamiento de seguridad de gestión (2.35 y 2.46) y la seguridad como prioridad de los empleados y rechazo del riesgo (2.35 y 2.40). Conclusiones: Los trabajadores del Hospital tienen un nivel adecuado de buena percepción acerca de los aspectos de seguridad y salud en el trabajo donde se evidenció que la fortaleza es la confianza de los trabajadores en la eficacia del sistema y la debilidad del sistema se encuentra en la falta de empoderamiento y rechazo al riesgo.

Photovoltaic and solar-assisted ground-source heat pump systems

This review investigates the performance of photovoltaic and solar-assisted ground-source heat pumps in which solar heat is transferred to the ground to improve the coefficient of performance. A number of studies indicate that, for systems with adequately sized ground heat exchangers, the effect on system efficiency is small: about 1% improvement if the heat source is photovoltaic, a 1–2% decline if the source is solar thermal. With possible exceptions for systems in which the ground heat exchanger is undersized, or natural recharge from ground water is insufficient, solar thermal energy is better used for domestic hot water than to recharge ground heat. This appears particularly true outside the heating season, as although much of the heat extracted from the ground can be replaced, it seems to have little effect on the coefficient of performance. Any savings in electrical consumption that do result from an improved coefficient can easily be outweighed by an inefficient control system for the circulation pumps.

Effect of enzymatic pretreatment and increasing the organic loading rate of lipid-rich wastewater treated in a hybrid UASB reactor

This study aimed at evaluating the effect of increasing organic loading rates and of enzyme pretreatment on the stability and efficiency of a hybrid upflow anaerobic sludge blanket reactor (UASBh) treating dairy effluent. The UASBh was submitted to the following average organic loading rates (OLR) 0.98 Kg.m(-3).d(-1), 4.58 Kg.m(-3).d(-1), 8.89 Kg.m(-3).d(-1) and 15.73 Kg.m(-3).d(-1), and with the higher value, the reactor was fed with effluent with and without an enzymatic pretreatment to hydrolyze fats. The hydraulic detention time was 24 h, and the temperature was 30 +/- 2 degrees C. The reactor was equipped with a superior foam bed and showed good efficiency and stability until an OLR of 8.89 Kg.m(-3).d(-1). The foam bed was efficient for solid retention and residual volatile acid concentration consumption. The enzymatic pretreatment did not contribute to the process stability, propitiating loss in both biomass and system efficiency. Specific methanogenic activity tests indicated the presence of inhibition after the sludge had been submitted to the pretreated effluent It was concluded that continuous exposure to the hydrolysis products or to the enzyme caused a dramatic drop in the efficiency and stability of the process, and the single exposure of the biomass to this condition did not inhibit methane formation. (C) 2011 Elsevier B.V. All rights reserved.

Development of a Compact Solar Combisystem

Within the frame of the project REBUS, "Competitive solar heating systems for residential buildings", which is financed by Nordic Energy Research, a new type of compact solar combisystem with high degree of prefabrication was developed. A hydraulic and control concept was designed with the goal to get highest system efficiency for use with either a condensing natural gas boiler or a pellet boiler. Especially when using the potential of high peak power of modern condensing natural gas boilers, a new operation strategy of a natural gas boiler/solar combisystem can increase the energy savings of a small solar combisystem by about 80% compared to conventional operation strategies.

Gestão associada de prestação de serviço público jurisdicional nos juizados especiais federais

Por mais que a informatização esteja avançada (interligação por melO da rede internet de computadores entre os órgãos e entidades públicas pelo Estado), máquina alguma substituirá os dramas do homem contemporâneo, principalmente aqueles que sempre estiveram alijados da cidadania. Os problemas do homem, principalmente os hiposuficientes, dentro do caso concreto, nem sempre podem ser solucionados por máquinas distantes uma da outra e, o pior, em locais distantes, sem permitir o acesso direto ao ser humano que comanda a máquina. Esse cidadão, que tem no princípio da dignidade da pessoa humana sua maior proteção e garantia outorgada pelo Estado de Direito, tem o direito de ser tratado com dignidade pelo Estado que monopoliza a pacificação social através da jurisdição, principalmente quando o réu é o próprio Estado, como é o caso do subsistema dos Juizados Especiais Federais (os réus são a União, ou suas entidades autárquicas, ou empresas públicas federais). A humanização no atendimento do cidadão, que busca e deposita no Estado Judiciário (Federal), no subsistema do Juizado Especial Federal, sua última esperança na resposta de seus direitos violados pelo próprio Estado Administração (Federal), se materializará por uma nova proposta de prestação de serviço público - a unitariedade (concentração de todos os partícipes desse subsistema em um único local - Judiciário e Executivo juntos) - de forma permanente e estática, nas cidades de maior demanda social, pela gestão associada de prestação de serviço público jurisdicional entre o Judiciário e Executivo (Legislativo eventualmente) onde a entrega do bem da vida litigioso ou a pacificação (meios alternativos de solução do conflito, como a conciliação) se dê dentro de um ambiente de respeito ao ser humano, ou seja, dentro de um prazo razoável, com padrões de atendimento de eficiência compatíveis com a contemporaneidade e principalmente de forma efetiva (com efetividade plena). Os Juizados Especiais, que foram criados para serem rápidos, ágeis e efetivos, não podem se banalizar e terem os mesmos estigmas da morosidade, da não efetividade e do desapego a qualidade no atendimento ao usuário. Tal humanização, como proposta na dissertação, desse subsistema judiciário - Juizado Especial Federal - com a unitariedade desse serviço público, atende e concretiza os valores e princípios constitucionais, sem necessidade de mudança legislativa, além de reforçar a legitimidade do Estado e solidificar a cidadania. O que se quer nessa dissertação é retirar o Judiciário do isolamento, o que é fundamental sobretudo no plano da efetividade (execução de suas decisões e prevenção e postergação de litígios criando uma mecanismos de conciliação prévia permanente). A dissertação propõe um novo desenho institucional entre Poderes da República para prestação de serviço público jurisdicional buscando contribuir para o aperfeiçoamento das atividades judiciárias em sentido amplo, ou seja, atividades administrativas ou não jurisdicionais (função atípica do Poder Judiciário). O paradigma proposto, além da valorização do consensualismo, implica a efetividade das normas jurídicas e a eficiência do sistema.

Comparação das respostas fisiológicas entre diferentes testes funcionais em obesos

obesity affects rightly functional capacity diminishing the cardiovascular system efficiency and oxygen uptake (VO2). Field tests, such as, Incremental Shuttle Walking Test (ISWT) and Six Minute Walk Test (6MWT) has been employed as alternative of Cardiopulmonary Exercise Test (CPX), to functional assessing for conditions which transport of oxygen to peripheral is diminished. Nevertheless, the knowing about metabolic variables response in real time and it comparing among different maximal and submaximal tests in obese is absent. Aim: to compare cardiopulmonary, metabolic response during CPX, ISWT and 6MWT and to analyse it influence of adiposity markers in obese. Material e Method: crosssectional, prospective study. Obese included if: (BMI>30Kg/m2; FVC>80%), were assessed as clinical, anthropometric (BMI, body adiposity index-BAI, waist-WC, hip- HC and neck-NC circumferences) and spirometry (forced vital capacity-FVC, Forced expiratory volume-1°second-FEV1, maximal voluntary ventilation-MVV) variables. Obese performed the sequence of tests: CPX, ISWT and 6MWT. Throughout tests was assessed breath-by-breath by telemetry system (Cortex-Biophysik-Metamax3B) variables; oxygen uptake on peak of activity (VO2peak); carbon dioxide production (VCO2); Volume Expiratory (VE); ventilatory equivalents for VO2 (VE/VO2) and CO2 (VE/VCO2); respiratory exchange rate (RER) and perceived effort-Borg6-20). Results: 15 obese (10women) 39.4+10.1years, normal spirometry (%CVF=93.7+9.7) finished all test. They have BMI (43.5+6.6kg/m2) and different as %adiposity (BAI=50.0+10.5% and 48.8+16.9% respectively women and men). Difference of VO2ml/kg/min and %VO2 were finding between CPX (18.6+4.0) and 6MWT (13.2+2.5) but not between ISWT (15.4+2.9). Agreement was found for ISWT and CPX on VO2Peak (3.2ml/kg/min; 95%; IC-3.0 9.4) and %VO2 (16.4%). VCO2(l/min) confirms similarity in production for CPX (2.3+1.0) and ISWT (1.7+0.7) and difference for 6MWT (1.4+0.6). WC explains more the response of CPX and ISWT than other adiposity markers. Adiposity diminishes 3.2% duration of CPX. Conclusion: ISWT promotes similar metabolic and cardiovascular response than CPX in obese. It suggesting that ISWT could be useful and reliable to assess oxygen uptake and functional capacity in obese