Effects of diethyl ether introduction in emissions and performance of a diesel engine fueled with biodiesel-ethanol blends

Biofuels provide high oxygen content for combustion and do modify properties that influence the engine operation process such as viscosity, enthalpy of vaporization, and cetane number. Some requirements of performance, fuel consumption, efficiency, and exhaust emission are necessary for the validation of these biofuels for application in engines. This work studies the effects of the use of diethyl ether (DEE) in biodiesel-ethanol blends in a DI mechanical diesel engine. The blends used in the tests were B80E20 (biodiesel 80%-ethanol 20%) and B76E19DEE5 (biodiesel 76%-ethanol 19%-DEE 5%). Fossil diesel (D100) and biodiesel (B100) were evaluated as reference fuels. The results revealed similar engine efficiencies among tested fuels at all loads. The use of B100 increased CO and NOx and decreased THC compared to D100 at the three loads tested. B80E20 fuel showed an increase in NOx emission in comparison with all fuels tested, which was attributed to higher oxygen content and lower cetane number. THC and CO were also increased for B80E20 compared to B100 and D100. The use of B76E19DEE5 fuel revealed reductions in NOx and CO emissions, while THC emissions increased. The engine efficiency of B76E19DEE5 was also highlighted at intermediate and more elevated engine load conditions.This work had the financial support of Energy Laboratory of Bahia Federal University (UFBA) and CAPES (Coordination for the Improvement of Higher Education Personnel)

O Cinema na Requisição das Mitologias da Pós-Modernidade

Podemos procurar as razões pelas quais o fenómeno cinemático também reflete inusitado sucesso na pós-modernidade. Diversos fatores permitiram o libertar do homem das grilhetas espácio-temporais, ajudando partilhas em permanência. Hipoteticamente facilitada uma necessidade antropológica, paradigma do pós-moderno. O cinema requisita uma superior capacidade de expressão para o próprio. Damos assim início a uma procura de entendimento do pensamento humano até ao contemporâneo, pela história, pela filosofia, pelo social, pela expressão, pela compreensão do período pós-moderno. Em sequência, partiremos sustentadamente para a tomografia do cinema, crentes na constatação da sua inclusão ou comprometimento social, formativo, estético e filosófico com tal período. Esse será o nosso Fitzcarraldo. Seremos ajudados na necessidade da Ficção Científica sempre ter demonstrado a procura de identidade, de género, dado que a mesma demostra imediatas imbricações com o nosso propósito, pelo que faremos apontada análise a três seus representantes: 2001, Odisseia no Espaço, A.I., Inteligência Artificial e Eu, Robot.We look for reasons why the cinematic phenomenon also reflects unusual success in post-modernity. Several factors led to the freeing of man from the fetters of space and time, helping shares continuously. Hypothetically facilitated a anthropological paradigm of the postmodern. The film ordering a superior ability to self expression. We therefore initiated a search for understanding of human thought to the contemporary, by history, philosophy, social, speech, understanding of the post-modernist. In response, we depart for sustained tomography film, believers in recognition of its inclusion or social commitment, training, aesthetic and philosophical in that period. This will be our Fitzcarraldo. It will help us in need of science fiction have always shown the search for identity, gender, since it demonstrates immediate overlaps with our purpose, so we pointed to three representatives analysis: 2001, A Space Odyssey, AI, Artificial Intelligence and I, Robot

Características psicométricas de una escala para caracterizar la motivación por la lectura académica

Las competencias asociadas con la lectura académica, en especial los aspectos motivacionales ligados a esta actividad, son una clave fundamental en el éxito académico de los estudiantes universitarios. La motivación es un tema emergente, que ha dado lugar a muchos estudios y, sin embargo, la motivación por la lectura de textos académicos continúa siendo un tema poco abordado y estudiado. Para brindar apoyo efectivo al proceso de aprendizaje, se hace necesario un diagnóstico capaz de informar de manera fina, válida y confiable sobre los aspectos motivacionales de la actividad de lectura en contexto académico. En el artículo se presentan los resultados del proceso de construcción y validación de la Escala de Motivación por la Lectura Académica (EMLA), construido a partir del modelo de Expectancy & Value de Jacqueline Eccles y Allan Wigfield (2002), en adelante EyV. Este instrumento proporciona pistas de intervención motivacional para incentivar la lectura en un contexto académico. Del mismo modo, se reporta la estructura del instrumento, sus fundamentos teóricos, así como su estructura factorial y confiabilidad; características psicométricas que hacen del EMLA un instrumento sólido, válido y confiable

Comparison of the improved X Farmer's system of growing cowpea

Estudos de fatores isolados em caupi (Vigna unguiculata (L.) Walp) na Serra do Mel, RN, num período de três anos, definiram cultivares mais produtivas, espaçamentos adequados, métodos de controle de pragas e viabilidade da adubação orgânica. Para verificar o desempenho desses fatores, agregados nos seus melhores níveis, e confrontá-los com o sistema de cultivo do produtor, foi instalada uma unidade de demonstração de resultados, ao nível de propriedade com parcelas de 0,25 ha. Os sistemas comparados foram: 1. sistema utilizado pelo produtor, cultivar Feijão-Vermelho, espaçamento 1,10 m x 1,10 m e sem controle de pragas; 2. sistema melhorado, cultivar Lisão, espaçamento 1 m x 0,50 m, com duas plantas por cova e controle de pragas; 3. idem, sistema 2, mais adubação com esterco de curral na dosagem de 12 t/ha. Foram contabilizados os custos adicionais para os sistemas melhorados, em relação ao sistema do produtor. Com o sistema 2 foram obtidos 132% dos rendimentos do sistema 1, porém, o lucro relativo cobriu apenas os custos adicionais para a relação de preços vigentes na colheita. O sistema de melhor desempenho foi o 3, com produtividade de 944 kg/ha, 283% da produção obtida com o sistema 1 e com taxa de retorno superior a Cr$2,00 por cruzeiro adicional investido, em três relações de preços usados.Field experiments of cowpea Vigna unguiculata (L.) Walp. were carried out at Serra do Mel, RN, Brazil, studying isolated factors for three agricultural years, defining more productive cultivars, appropriate spacing, methods of insect control and the viability of cattle manure. Intending to verify the performance of these factors, utilizing their best previous results, and to compare them with the cropping system used by farmers, a demonstration unit of the results was set up, with plots of 0.25 ha. The systems compared were: 1. system used by farmer, Feijão -Vermelho cultivar, spacing of 1.10 m x 1.10 m with three or four plants/hill, without insect control; 2. improved system, Lisão cultivar, spacing of 1 m x 0.50 m with two plants/hill and insect control; 3. the improved system plus fertilization with 12 t/ha of cattle manure. The additional costs for the improved system in relation to the farmer's system were accounted for. System 2 showed a 32$ 2.00 per cruzeiro invested, in three price ratios used

A notch methodology to estimate fretting fatigue strength

The aim of this work is to propose a methodology to estimate the fatigue limit of cylindrical contacts under a partial slip regime. Taylors point stress method, usually applied to estimate fatigue limit for notched structures, was associated with the Modified Wöhler Curves to define the fretting crack initiation thres hold methodology. Twenty-nine tests on cylindrical contacts were selected from the literature and considered to evaluate the quality of the estimates. The results agree well for twenty-three experimental data. As the fatigue limit under fully reversed bending is the fatigue parameter usually available for most metallic alloys, it was also showed how the second fatigue limit needed to calibrate the proposed procedure could be estimated by taking full advantage from other standard predictive methodologies previously devised to estimate the mean stress effect under uniaxial fatigue loading

Níveis de máxima eficiência econômica de esterco de curral no cultivo do caupi

Experiments were carried out to define the maximum economic efficiency level on the yield of cowpeas (Vigna unguiculata (L.) Walp) and to observe the residual effect in the colonization project area of the Serra do Mel, RN, Brazil. Two experiments were established during the agricultural years of 1981 and 1982, in a soil of the Red-Yellow Alic Latosol type, where manure was applied the first year and the residual effect was assessed the second year. The experimental design was randomized complete blocks with four replications of eight treatments. The treatments were based on the manure levels which ranged from zero to 42 t/ha (dry basis), in intervals of 6 t/ha. In relation to the price ratio for 1981, the maximum economic efficiency level was 14 t/ha of manure with a yield of 337kg of grain/ha. In 1982 this level was 16 t/ha manure with a yield of 1539 kg of grain/ha. Among the yield components studied, only the number of pods per area reacted to different levels of cattle manure. One year after the application of manure, the levels of phosphorus and potassium in the soil were 15 ppm and 65 ppm, corresponding to five and two times more than the initial levels, respectively.Realizou-se o presente trabalho como objetivo de determinar o nível de esterco de máxima eficiência econômica e a resposta ao efeito residual na produção do caupi (Vigna unguiculata (L.) Walp), na área de colonização da serra do Mel, RN. Foram instalados dois ensaios em solo do tipo Latossolo Vermelho-Amarelo Álico, nos anos de 1981 e 1982. O adubo foi aplicado no primeiro ano e o efeito residual avaliado no segundo. Os ensaios foram delineados em blocos casualizados completos com oito tratamentos e quatro repetições. Os tratamentos foram constituídos de doses de esterco, que variaram de 0 a 42 t/ha (base seca), em intervalos de 6 t/ha. A preços vigentes em 1981, ano de chuvas escassas e mal distribuídas, o nível de máxima eficiência econômica foi de 14 t/ha de esterco de curral com produtividade de caupi estimada em 337 kg de grãos/ha. Em 1982, o nível econômico de esterco foi de 16 t/ha com produtividade de 1.539 kg de grãos/ha. Dos componentes de produção, somente o número de vagens por área respondeu às diferentes dosagens de esterco aplicadas. Um ano após a aplicação do adubo, os teores de fósforo e potássio disponíveis no solo foram de 15 ppm e 65 ppm, respectivamente, cinco e duas vezes maiores que os teores iniciais

Electromagnetic energy harvesting using magnetic levitation architectures: a review

Motion-driven electromagnetic energy harvesters have the ability to provide low-cost and customizable electric powering. They are a well-suited technological solution to autonomously supply a broad range of high-sophisticated devices. This paper presents a detailed review focused on major breakthroughs in the scope of electromagnetic energy harvesting using magnetic levitation architectures. A rigorous analysis of twenty-one design configurations was made to compare their geometric and constructive parameters, optimization methodologies and energy harvesting performances. This review also explores the most relevant models (analytical, semi-analytical, empirical and finite element method) already developed to make intelligible the physical phenomena of their transduction mechanisms. The most relevant approaches to model each physical phenomenon of these transduction mechanisms are highlighted in this paper. Very good agreements were found between experimental and simulation tests with deviations lower than 15%. Moreover, the external motion excitations and electric energy harvesting outputs were also comprehensively compared and critically discussed. Electric power densities up to 8 mW/cm^3 (8 kW/m^3) have already been achieved; for resistive loads, the maximum voltage and current were 43.4 V and 150 mA, respectively, for volumes up to 235 cm^3. Results highlight the potential of these harvesters to convert mechanical energy into electric energy both for large-scale and small-scale applications. Moreover, this paper proposes future research directions towards efficiency maximization and minimization of energy production costs.in publicatio