Maurício Cordeiro Mancini

Estimation of the total efficiency of metabolizable energy utilization for maintenance and growth by cattle in tropical conditions

Data of 320 animals were obtained from eight comparative slaughter studies performed under tropical conditions and used to estimate the total efficiency of utilization of the metabolizable energy intake (MEI), which varied from 77 to 419 kcal kg-0.75d-1. The provided data also contained direct measures of the recovered energy (RE), which allowed calculating the heat production (HE) by difference. The RE was regressed on MEI and deviations from linearity were evaluated by using the F-test. The respective estimates of the fasting heat production and the intercept and the slope that composes the relationship between RE and MEI were 73 kcal kg-0.75d-1, 42 kcal kg-0.75d-1 and 0.37. Hence, the total efficiency was estimated by dividing the net energy for maintenance and growth by the metabolizable energy intake. The estimated total efficiency of the ME utilization and analogous estimates based on the beef cattle NRC model were employed in an additional study to evaluate their predictive powers in terms of the mean square deviations for both temperate and tropical conditions. The two approaches presented similar predictive powers but the proposed one had a 22% lower mean squared deviation even with its more simplified structure.

Secagem de fatias de abóboras (Cucurbita moschata, L.) por convecção natural e forçada

Besides its low price, Pumpkin (Cucurbita moschata, L.) is an important source of provitamin-A, and when dehydrated it offers different options of utilizations and consumption. Natural and forced convection drying were compared according to the drying degree shrinkage as a function of temperature, and air velocity and product dimensions. The obtained results showed that slices with the volume of 6.25 cm3 in forced convection oven at 50 °C and at the velocity of 5.5 x 10-4 ms-1 resulted in a lower shrinkage products, so these conditions were recommended.

Multi-objective dynamic optimization of fixed bed dryers: simulation and experiments

Abstract It is very important a thorough understanding of the drying operation (confident mathematical model) for solving the problems related to the optimization of a dehydration plant, which basic objective is the removal of water up to a certain desired level. Pareto optimization, which improves the performance of dryers for being appropriate to work with conflicting objectives, was implemented through simulation and experimental studies, using a fixed bed alumina drying unit.

ESTUDO DAS ISOTERMAS DE EQUILÍBRIO DAS SEMENTES DO PINHÃO-MANSO (Jatropha curcas L)

O oleo do pinhao-manso e uma das promissoras materias-primasutilizadas para a producao de biodiesel. Como a umidade presente na semente e uma importante variavel, que influencia na quantidade de oleo extraido, o objetivo deste trabalho foi obter as isotermas de equilibrio, realizar a modelagem matematica e validar o modelo selecionado. As isotermas foram obtidas atraves do medidor de atividade de agua AquaLab 4TE, nas temperaturas de 30, 40 e 50 °C. A analise estatistica provou que somente a atividade de agua apresentou influencia significativa nos dados das isotermas. Entre os modelos matematicos testados, o que melhor descreveu o comportamento higroscopico das isotermas foi o de Smith, para o qual todos os parâmetros foram significativos, apresentando o menor desvio relativo medio de 14,72%.

Optimization Studies of an Oil Well Drilling Process

Abstract Noninferior or Pareto sets of optimal solutions were determined for the dual objectives of maximizing the annulus solid concentration and minimizing mud invasion into the reservoir or migration of reservoir fluids into the well annulus. The following set of time varying control inputs to the process were analyzed: choke valve opening index, pump mixture mass flow rate or mud density and drilling rate. The formulation of the oil well drilling control problem as a multiobjective optimization problem and solving the Pareto set was the most appropriate way to understand all the competitions among the various objectives.

Efeito da secagem em leito de jorro bidimensional sobre as propriedades físicas e tecnológicas do feijão preto (Phaseolus vulgaris, L.)

A two-dimensional spouted bed dryer was used to study the drying process of black beans (Phaseolus vulgaris, L). The equipment dimensions were: height of 100 cm, width of 10 cm and length of 40 cm. A blower of 7 cv was used to supply the air necessary for the spout formation on the apparatus and no additional heat was necessary. The temperature at the air inlet was around 50o C. The experiments were carried out according to factorial planning, with a complementary experiment set. In this work the effects of the drying time, and the apparatus air velocity were evaluated in relation to mass grain capacity of each batch as well as cooking time, water absorption, particle diameter and particle density. It also fitted the acquired data from experimental runs into the correlations based on the variables: drying time, air velocity and mass of particulated material used in the dryer. The drying rate was studied. The experimental results led to the conclusion that the conditions process studied did not significantly affected the physical and technological properties of beans and reduced the grain moisture content to 40 % of the initial value.