RESUMO O desempenho dos subsoladores pode ser influenciado pelos restos culturais no solo através dos diferentes tipos de cobertura vegetal. Em qualquer um desses sistemas de cobertura, o uso de subsoladores para descompactação altera as propriedades físicas do solo. O presente estudo teve como objetivo avaliar os atributos físicos do solo em tipos de manejo sob diferentes velocidades de deslocamento e profundidades na operação de subsolagem. O experimento foi conduzido no IF Goiano, Campus Morrinhos, Goiás, Brasil. O delineamento inteiramente casualizado foi usado em esquema de parcelas subdivididas com 12 tratamentos e cinco repetições, totalizando 60 plarcelas. Os fatores corresponderam a duas áreas de manejo (sequeiro e pastagem), duas velocidades de operação de subsolagem (2,5 e 4,5 km h-1) e três profundidades do solo (0,00-0,015; 0,15-0,30 e 0,30-0,45 m). A parcela principal foi constituída pelas duas áreas de manejo e a subparcela a combinação dos outros dois fatores. Foram avaliados a resistência à penetração, densidade do solo, teor de água, mobilização do solo e expansão volumétrica do solo. Posteriormente, os valores encontrados foram submetidos à análise de variância e teste de Tukey p ≤ 0,05. A resistência à penetração e a densidade aparente foram diferentes antes e após a subsolagem. As velocidades de subsolagem alteraram os valores de resistência à penetração e mobilização do solo. As áreas de pastagem apresentaram maior resistência à penetração das raízes e proporcionaram menor teor de água e favoreceram maior expansão volumétrica do solo.

ABSTRACT Subsoiler performance can be influenced by crop residue in the soil through different types of vegetation cover. In any of these cover systems, the use of subsoilers for decompaction changes soil physical properties. The present study aimed to evaluate soil physical properties in different management systems using several subsoiling speeds and soil depths. The experiment was conducted at IF Goiano, Morrinhos Campus, Goiás state, Brazil. A completely randomized design was used in a split-plot scheme with 12 treatments and five replicates, totaling 60 plots. The factors corresponded to two management areas (rainfed and pasture), two subsoiling speeds (2.5 and 4.5 km h-1) and three soil depths (0.00-0.015; 0.15-0.30 and 0.30-0.45 m). The main plot consisted of the two management areas and the subplot the combination of the other two factors. Penetration resistance, bulk density, water content, soil mobilization and soil volumetric expansion were evaluated. The results were then submitted to analysis of variance and Tukey’s test (p ≤ 0.05). Penetration resistance and bulk density differed before and after subsoiling. The subsoiling speeds altered penetration resistance and soil mobilization. Pasture areas showed greater root penetration resistance, provided lower water content and favored greater soil volumetric expansion.

RESUMO O uso da mecanização na colheita do tomate industrial proporciona maior rendimento e rapidez desta etapa. Entretanto, a intervenção mecânica nesse processo pode alterar a fisiologia dos frutos colhidos. Portanto, objetivou-se com o trabalho mensurar em colhedoras, com diferentes horas de uso, as perdas quantitativas de frutos de tomate e verificar o comportamento físico-químico dos frutos colhidos a partir de análises físico-químicas. Foram utilizadas três colhedoras autopropelidas da mesma marca e modelo com diferentes números de horas de trabalho. Colheu-se os frutos manualmente selecionados ou sem danos; posteriormente, realizou-se a colheita mecanizada. Foram avaliados a firmeza, acidez titulável, teor de sólidos solúveis (°Brix), pH, perda de massa e a classificação quanto ao estado dos frutos proposta pelo Ministério da Agricultura Pecuária e Abastecimento de 2002. As perdas quantitativas foram divididas entre: perdas nas ramas, perdas no solo e perdas totais. Foi constatado que o número de horas trabalhadas pela colhedora não influiu nas perdas quantitativas. A quantidade de danos gerais em uma determinada quantidade de frutos é maior quando a colhedora possui um maior número de horas trabalhadas. A colheita mecanizada afetou os atributos físicos dos frutos, tais como a firmeza e a porcentagem de perda de massa.

ABSTRACT The use of mechanization in the harvesting of industrial tomatoes provides greater yield and speed of this stage. However, mechanical intervention in this process may alter the physiology of harvested fruits. Therefore, the objective of this study was to measure the quantitative losses of tomato fruits and to verify the physico-chemical behavior of fruits harvested based on physicochemical analysis in harvesters with different hours of use. Three self-propelled harvesters of the same brand and model with different working hours were used. Manually selected or undamaged fruits were harvested; afterwards, mechanized harvesting was carried out. Firmness, titratable acidity, soluble solids content (°Brix), pH, weight loss and fruit status classification proposed by the Ministry of Livestock, Agriculture and Food Supply of 2002 were evaluated. Quantitative losses were divided into: losses on vines, losses on soil and total losses. It was found that the number of hours worked by the harvester did not affect the quantitative losses. The amount of overall damage in a certain amount of fruit is greater when the harvester has a greater number of hours worked. Mechanized harvesting affected the physical attributes of the fruits, such as firmness and percentage of weight loss.

ABSTRACT In Brazil, the characterization of wood is carried out in accordance with the premises established by ABNT NBR 7190standard; however, the determination of wood properties requires the use of equipment, which hinders the wood characterization for the construction professional. To circumvent this problem, the properties of wood strength and stiffness can be estimated through regression models using the apparent density as estimator, being the density a physical property of easy determination. This study aimed to determine 4 physical and 13 mechanical properties of “Angico Branco” wood (Anadenanthera colubrina), and with the aid of regression models based on analysis of variance, estimate the strength and stiffness properties as a function of apparent density. Twelve samples were produced for each test, resulting in a total of 204 experimental determinations. The results of mechanical properties showed consistent performance with other wood species studied, demonstrating their potential use in various applications. From the regression models, only the longitudinal modulus of elasticity in parallel compression to the grain showed a significant result, and the best were obtained with the linear model, which provided determination coefficient (R2) equal to 56.32%.

The development of new materials based on industrial wastes has been the focus of much research for a sustainable world. The growing demand for tyres has been every year exacerbating environmental problems due to indiscriminate disposal in the nature, making a potentially harmful waste to public health. The incorporation of rubber particles from scrap tyres into polymeric composites has achieved high toughness and moderate mechanical properties. This work investigates the geometric effects (thickness, width and internal cell angle) of auxetic structures made of recycled rubber composites based on experimental and numerical data. The response surface models integrated with the swarm intelligence and finite element analysis were proposed in order to obtain a range of solutions that provides useful information to the user during the selection of geometric parameters for reentrant cells. The results revealed the cell thickness ranges from 39-40 mm and 5.98-6 mm, and the cell angle range from -0.01 to -0.06º maximize the ultimate strength. The same parameters were able to optimize the modulus of elasticity of rubber auxetic structures, excepting for the angle factor which must be set between -30º and 27.7º. The optimal Poisson's ratio was found when the cell angle ranged from -30º to -28.5º, cell width ranged from 5-5.6 mm and 2 mm in thickness.