Numerical evaluation of the modulus of longitudinal elasticity in structural round timber elements of the Eucalyptus genus

Currently, the standards that deal with the determination of the properties of rigidity and strength for structural round timber elements do not take in consideration in their calculations and mathematical models the influence of the existing irregularities in the geometry of these elements. This study has as objective to determine the effective value of the modulus of longitudinal elasticity for structural round timber pieces of the Eucalyptus citriodora genus by a technique of optimization allied to the Inverse Analysis Method, to the Finite Element Method and the Least Square Method.

Evaluation of empirical methods to estimate reference evapotranspiration in Uberaba, State of Minas Gerais, Brazil

Evapotranspiration is the process of water loss of vegetated soil due to evaporation and transpiration, and it may be estimated by various empirical methods. This study had the objective to carry out the evaluation of the performance of the following methods: Blaney-Criddle, Jensen-Haise, Linacre, Solar Radiation, Hargreaves-Samani, Makkink, Thornthwaite, Camargo, Priestley-Taylor and Original Penman in the estimation of the potential evapotranspiration when compared to the Penman-Monteith standard method (FAO56) to the climatic conditions of Uberaba, state of Minas Gerais, Brazil. A set of 21 years monthly data (1990 to 2010) was used, working with the climatic elements: temperature, relative humidity, wind speed and insolation. The empirical methods to estimate reference evapotranspiration were compared with the standard method using linear regression, simple statistical analysis, Willmott agreement index (d) and performance index (c). The methods Makkink and Camargo showed the best performance, with "c" values ​​of 0.75 and 0.66, respectively. The Hargreaves-Samani method presented a better linear relation with the standard method, with a correlation coefficient (r) of 0.88.

Evaluation of cotton stalks destroyers

The destruction of the cotton crop residues (cotton stalks) is a mandatory procedure in Brazil for prophylactic issues, but is a subject unexplored by the research and there are few studies that deal with this issue. However, this is not encouraged in recent decades, studies aimed at developing and evaluating equipment for this purpose. The present study had the objective to evaluate six methods for mechanical destruction of cotton crop residues. Each method was defined based on the principle of operation of the active parts of the equipment, which were tested in medium texture soil and in a clayey one. The variables used to evaluate the efficiency of the equipment were the regrowth rate, the theoretical field capacity and energy demand. The equipment with convergent concave disks (DCC) and flat cutters discs from manufacturer A (CPS-a) showed the best results in cotton stalks destruction in both soil types. The harrow disc (GPD) was efficient only in clay soil. It was concluded that the equipment with convergent concave disks, among those tested, was the most efficient to destroy cotton stalks, regardless of soil type, and that the harrow disc was not included among the best performers.

Evaluation of protein extraction methods to obtain protein concentrate from cassava leaf

The cassava leaf, waste generated in the harvest of the roots, is characterized by high content of protein, vitamins and minerals; however, its use is limited due to the high fiber content and antinutritional substances, which can be removed by obtaining protein concentrates. In this context, the objective of this study was to evaluate protein extraction processes, aiming the use of cassava leaves (Manihot esculenta Crantz) as an alternative protein. Four methods were tested: 1) Coagulation of Proteins by Lowering the Temperature, 2) Extraction by Isoelectric Precipitation, 3) Solubilization of Proteins and 4) Fermentation of Filter Leaf Juice. To obtain the concentrates, the use of fresh or dried leaves and extraction in one or two steps were also evaluated. The solubilization of proteins (method 3) showed a higher extraction yield; however, with concentrate of low quality. The fermentation of the juice (method 4) produced concentrates with higher quality and lower costs and the isoelectric precipitation (method 2) promoted the obtention of concentrates in less time, both with good prospects for use. The use of two extraction steps was not advantageous to the process and there was no difference between the use of fresh or dried leaf, and the use of fresh leaves is presented as a good option for the simplicity of the method.

Application of x-ray computed tomography in the evaluation of soil porosity in soil management systems

The study aimed to evaluate a methodology to quantify the porosity of the soil using computed tomography in areas under no-tillage, conventional tillage and native forest. Three soil management systems were selected for the study: forest, conventional tillage and no-tillage. In each soil management system, undisturbed soil samples were collected in the surface layer (0.0 to 0.10 m). The tomographic images were obtained using a X-ray microtomography. After obtaining the images, they were processed, and a methodology was evaluated for image conversion into numerical values. The statistical method which provided the greatest accuracy was the percentile method. The methodology used to analyze the tomographic image allowed quantifying the porosity of the soil under different soil management. The method enabled the characterization of soil porosity in a non-evasive and non-destructive way.