J. H. Martins

Comportamento de variáveis climáticas em sistemas de ventilação mínima para produção de pintos de corte

During the creation process of poultry, the initial or heating phase, is characterized as the most delicate period due to physiological immaturity of the birds. Thus, environmental factors stand out to infer, directly, in the growth, on the performance and maintenance of life of these animals. Based on these considerations, the aim of this study was to study the effect of three different systems of minimum ventilation (positive pressure, negative and natural) on environmental variables (air temperature, relative humidity and wind velocity) of broiler sheds during the heating phase. According to results obtained, it was verified that the heating system used was inadequate to maintain the air temperature and relative humidity within the standards deemed appropriate, thus exposing the birds to periods of heat stress by cold. In contrast, there were negative influences regarding ventilation rates applied to the two ventilation systems positive and negative. Wind velocity also remained at levels considered non-stressful for young chickens.

Efeitos de diferentes estratégias de controle no ambiente de armazenamento de grãos em regiões tropicais e subtropicais.

In this work, control strategies for grain aeration based on timer, thermostat and thermostat combined with humidistats were compared to the AERO controller. In spite of the simplicity of the first three strategies, they are widely used, resulting in reliable control and high acceptance by farmers. AERO was developed at the Federal University of Vicosa to spread and facilitate the use of more sophisticated strategies by farmers. This controller is based on real time data acquisition and process simulation. The results showed that aeration time, as well as final grain deterioration rates, temperatures and moisture contents were similar among the four strategies, when considering the best set-points of the three simple controllers. However, AERO resulted in a more effective control, cooling the grain mass more quickly and reducing temperature and moisture content oscillations during the aeration process. Another advantage of AERO is its capacity of automatically adjust its set-points according to the weather conditions of the region where the aeration system is operating.

Racionalização do uso de força motriz em fábrica de ração

A falta de investimento no setor energetico, aliada a sazonalidade de recursos naturais necessarios para a geracao de energia hidroeletrica, faz da racionalizacao do uso de energia eletrica uma ferramenta de apoio imprescindivel para o crescimento do Pais. A racao animal pode representar entre 70 e 80% do custo de producao da criacao de animais. Sendo assim, e importante o estudo da racionalizacao do uso de energia em processos que utilizam intensivamente forca motriz, tais como as fabricas de racao. Na fabrica de racao estudada, os motores eletricos sao utilizados principalmente para moagem e mistura de granulados e transporte. Com o objetivo de racionalizar o uso da energia eletrica, foi realizado estudo de adequacao de forca motriz dos equipamentos da fabrica de racao da Industria Pif Paf Alimentos. O indice de carregamento medio dos motores eletricos estudados foi de 48,6%. O potencial estimado total de economia com energia eletrica anual, utilizando-se sempre da melhor opcao de adequacao de forca motriz foi de R

Numerical Simulation Techniques for Optimizing Thermodynamic Efficiencies of Cereal Grain Dryers

24.426,50 ao ano (23,9%). Para que essas medidas sejam efetivadas, devem-se adequar tambem: (i) as exigencias eletricas do circuito, como ajuste de reles e escolha de fusiveis; (ii) o horario de funcionamento, e (iii) necessidade de implantacao de sistema de armazenamento de racao.

A new computational method for hepatic fat microvesicles counting in histological study in rats.

As a first objective, this study addresses a novel approach to drying efficiency analysis through transient models based on both the first and second laws of thermodynamics. As a second objective, we developed a numerical meshless scheme based on cubic radial basis functions to solve the associated nonlinear coupled advection-dominated set of partial differential equations. The simulated results showed excellent accuracy when compared with available literature data on drying. Finally, and most significantly, this study presents an original methodology for optimizing dryers based on energy and exergy efficiencies and the associated controllable operational parameters: drying air velocity (flowrate) and temperature.

Avaliação da transmissão de dados de temperatura no sistema 1-wireTM

Liver steatosis was once believed to be a benign condition, with rare progression to chronic liver disease. Thus, in both clinical and experimental practice, it is fundamental to have a reliable and objective method for its precise quantification. An image analysis algorithm was developed and validated for automatically and rapidly quantifying hepatic fat microvesicles. The image processing algorithms automatically segmented interstitial steatosis areas and analyzed the threshold region. Automatic quantifications did not significantly differ from manual evaluations of means of the same areas. Comparison of our image analysis quantifications with staging of histologic evaluations of liver steatosis presented significant correlations that are based on the distribution patterns and on the area quantity of steatosis, respectively. The use of algorithms for analysis and image processing is a sensitive, precise, objective and reproducible method of quantifying hepatic fat microvesicles, which complements semi-quantitative histologic evaluation systems.

Tarifa binômia para o custo de água pressurizada em perímetros irrigados

A necessidade de sistemas de monitoramento automatico versateis e de baixo custo que possam auxiliar o produtor agricola na otimizacao dos processos produtivos, e evidente. Este trabalho foi realizado com o objetivo de pesquisar as limitacoes e as potencialidades de aplicacao do sistema 1-wireTM na transmissao de dados de temperatura em instalacoes agricolas. O sistema 1-wireTM e uma rede de transmissao de dados que possibilita a comunicacao digital entre um computador e dispositivos da serie 1-wireTM, tais como os sensores de temperatura DS1820. A transmissao de dados de temperatura nesse sistema foi avaliada em funcao do tipo dos condutores e do numero de sensores DS1820. Com base nos resultados, concluiu-se que o aumento do numero de sensores de temperatura DS1820 no sistema 1-wireTM incrementa a carga capacitiva de maneira distinta para cada um dos tipos de condutores estudados, podendo causar interrupcoes na transmissao de dados.The need of versatile and low cost automatic monitoring systems for the optimization of the agricultural productive processes is evident. This work was carried out to evaluate the limitations and potentialities of the 1-wireTM system for temperature data transmission in agricultural buildings. The 1-wireTM system is a data transmission network, which makes possible the digital communication between a computer and devices of the 1-wireTM series, such as the temperature DS1820 sensors. The temperature data transmission in this system was evaluated as a function of types of conductors and the number of DS1820 sensors. Based on the results, it was concluded that, by increasing the number of the DS1820 temperature sensors in the 1-wireTM system, the capacitive load increases in a different way for each conductor and can cause interruptions during temperature data transmission.

Modeling and Simulation of the Transient Response of Temperature and Relative Humidity Sensors with and without Protective Housing

In irrigation districts, the variable cost tariff have being depended only on the amount of water consumed, and not in the energy and the demand for electric power to supply the water pressure and flow rate recommended by the irrigation system. This way of charge the irrigation water is nonsense, since the less efficient participants subsidized the more efficient ones. Thus, this work proposes that the water tariffs not only consider the amount of water consumed in the month, but also the pressure, since the hydraulic power demand is a function of the product of flow rate times the pressure. The study compared the water cost for participants that consume the same amount monthly for the present situation and the proposed methodology. It was verified, also, the effect of isolated irrigations or simultaneous ones and their implications on the water costs. The results showed that the implementation water tariff that charges the volume of water may reduce the costs for the participants at low pressures up to 66%. On the other hand, high pressure participants may have their water bill increased up to 133%. The simultaneity on the water use also influences its cost due to electrical power demand variation.

Electric motor efficiency as parameter for sizing a directly connected into transformer feeder cable.

Based on the necessity for enclosure protection of temperature and relative humidity sensors installed in a hostile environment, a wind tunnel was used to quantify the time that the sensors take to reach equilibrium in the environmental conditions to which they are exposed. Two treatments were used: (1) sensors with polyvinyl chloride (PVC) enclosure protection, and (2) sensors with no enclosure protection. The primary objective of this study was to develop and validate a 3-D computational fluid dynamics (CFD) model for analyzing the temperature and relative humidity distribution in a wind tunnel using sensors with PVC enclosure protection and sensors with no enclosure protection. A CFD simulation model was developed to describe the temperature distribution and the physics of mass transfer related to the airflow relative humidity. The first results demonstrate the applicability of the simulation. For verification, a sensor device was successfully assembled and tested in an environment that was optimized to ensure fast change conditions. The quantification setup presented in this paper is thus considered to be adequate for testing different materials and morphologies for enclosure protection. The results show that the boundary layer flow regime has a significant impact on the heat flux distribution. The results indicate that the CFD technique is a powerful tool which provides a detailed description of the flow and temperature fields as well as the time that the relative humidity takes to reach equilibrium with the environment in which the sensors are inserted.

Sistema automático para secagem de produtos agrícolas em camada fina

O dimensionamento de condutores de energia eletrica nao leva em consideracao criterios de racionalizacao do uso de energia eletrica. O estudo abrangeu uma avaliacao sobre o dimensionamento de condutores alimentadores de energia eletrica de motores conectados diretamente a transformadores utilizados na eletrificacao rural. No dimensionamento dos condutores alimentadores, indica-se que, alem do atendimento a norma tecnica (dimensionamento em funcao da capacidade de corrente do condutor e da queda de tensao admissivel), tambem sejam considerados: (i) o numero de horas de funcionamento; (ii) as caracteristicas eletricas e preco de condutores; (iii) as caracteristicas da instalacao, como comprimento do ramal e potencia do motor. Provou-se que, em algumas situacoes, e vantajoso aumentar a bitola do condutor alem daquela exigida pela norma tecnica, a fim de se economizarem energia e gastos pela menor perda no alimentador e maior rendimento do motor eletrico