Avaliação de eficiência da implantação de técnica de bioengenharia de solos

O Baixo São Francisco está em constante dinâmica hidroambiental resultante das alterações promovidas na calha do rio, representadas pelos processos geomorfológicos ou por ações antrópicas como a construção das barragens que por sua vez provocou mudanças geomorfológicas resultando na aceleração de processos erosivos nas suas margens. O objetivo deste trabalho foi avaliar a implantação de técnicas de recuperação hidroambiental com uso de bioengenharia de solos na margem do rio São Francisco. A área estudada compreende um trecho do baixo curso do rio São Francisco, localizado no município de Amparo do São Francisco, no estado de Sergipe, nordeste do Brasil, onde técnica de bioengenharia de solos, como enrocamento vegetado, foi implementada no ano de 2011. Três grupos de indicadores individuais foram selecionados que juntos contribuíram para a avaliação da Recuperação da Área Degradada relacionados à qualidade do solo, como resistência do solo à penetração e Velocidade de Infiltração Básica, à recuperação da biodiversidade como banco de sementes e a regeneração natural da área por meio de indicadores como composição e cobertura linear de espécies. A metodologia empregada contempla uma avaliação dos resultados originados do uso da biotécnica a partir da identificação da contribuição da vegetação que auxilia na contenção de taludes, uma vez que a cobertura vegetal protege a superfície do solo contra ações erosivas como o vento e a água da chuva. O reforço mecânico trazido pelo sistema radicular das plantas contra cisalhamento do solo se mostrou pela menor resistência à penetração do solo e maior Taxa de infiltração. Evaluation of efficiency of the implementation of soil bioengineering techniqueA B S T R A C TThe Lower São Francisco is in constant hydro-environmental dynamics resulting from the changes promoted in the river channel, represented by geomorphological processes or by anthropic actions such as the construction of dams that in turn caused geomorphological changes resulting in the acceleration of erosive processes on its banks. The objective of this work was to evaluate the implementation of hydroenvironmental recovery techniques using soil bioengineering on the bank of the São Francisco River. The studied area comprises a stretch of the low course of the São Francisco River, located in the municipality of Amparo do São Francisco, in the state of Sergipe, northeastearn Brazil, where soil bioengineering technique, such as vegetated rockfill, was implemented in 2011. Three groups of individual indicators were selected that together contributed to the assessment of Degraded Area Recovery related to soil quality, such as soil resistance to penetration and Basic Infiltration Speed, to the recovery of biodiversity as a seed bank and the natural area regeneration through indicators such as composition and linear species coverage. The employed methodology includes an evaluation of the results from the use of biotechnology based on the identification of the vegetation contribution that helps to contain slopes, since the vegetation cover protects the soil surface against erosive actions such as wind and rainwater. The mechanical reinforcement brought by the root system against soil shear was shown by the lower resistance to soil penetration and a higher infiltration rate.Keywords: Degraded Areas Recovery, erosion, São Francisco River

Development of a low-cost electromechanical penetrometer to verify resistance to soil penetration

Soil compaction is one of the great obstacles in modern agriculture. With the increase in size, weight and intensity of use of machines in crops in recent decades, the soil has suffered damage to its structure, compromising the productivity of vegetable crops. One of the ways to indirectly obtain the compaction state of the soil is through the resistance to penetration imposed by it on a standardized metal rod. Invariably, commercial equipment for this purpose is expensive. The objective of this study was to develop a low-cost system for evaluating the resistance to soil penetration, using a prototyping platform and specific sensors. The developed equipment, when compared with a calibrated standard equipment, presented a high correlation in the results of resistance to penetration in two soil conditions. The development cost of the proposed equipment was 800% lower than the average value of commercial equipment available on the market, so the measurements met the purpose of the project, showing the possibility of developing low-cost solutions through prototyping platforms, for the assessment of resistance to soil penetration.

The penetration and ricochet of ogive-nosed rigid projectiles obliquely impacting metallic targets

A large number of 3D numerical simulations were performed in order to follow the trajectory changes of rigid CRH3 ogive-nosed projectiles, impacting semi-infinite metallic targets at various obliquities. These trajectory changes are shown to be related to the threshold ricochet angles of the projectile/target pairs. These threshold angles are the impact obliquities where the projectiles end up moving in a path parallel to the target’s face. They were found to depend on a non-dimensional entity which is equal to the ratio between the target’s resistance to penetration and the dynamic pressure exerted by the projectile upon impact. Good agreement was obtained by comparing simulation results for these trajectory changes with experimental data from several published works. In addition, numerically-based relations were derived for the penetration depths of these ogive-nosed projectiles at oblique impacts, which are shown to agree with the simulation results.

Resistance of soil to penetration as a parameter indicator of subsolation in crop areas of sugar cane

Sugarcane is a very important economic crop that relies heavily on agricultural machinery, which contributes to soil compaction and a consequent decline in productivity. Subsoiling operation reduces the problems caused by compression; however, it is necessary to know its location and intensity. Accordingly, the aim of this work is to present a compression diagnostic method based on soil resistance to penetration as the parameter that indicates need for intervention in the subsoil. Measurements of penetration resistance was carried out in areas of sugarcane, located in the municipalities of Goianésia, Barro Alto and Santa Isabel, in the Brazilian state of Goiás. The Falker penetrometer (PLG 1020) was used, adjusted to a maximum depth of 40 cm and adopted as a critical resistance value of 4.0 MPa. The data were interpolated using kriging and adjusted in AutoCAD 2013 (Autodesk). The methodology proved effective in areas of compacted soil, and the surface layer had less resistance. The reduction in soil preparation was 96.54% and when considering the topographic adjustments, the reduction was 74.07%, showing the viability and importance of the diagnosis to show the proper management.

Photoperiod Following Inoculation of Arabidopsis with Pyricularia oryzae (syn. Magnaporthe oryzae) Influences on the Plant–Pathogen Interaction

In plant–pathogen interactions, a proper light environment affects the establishment of defense responses in plants. In our previous experiments, we found that nonhost resistance (NHR) to Pyricularia oryzae Cav. in Arabidopsis thaliana (L.) Heynh. (Arabidopsis), in diurnal conditions, varies with the inoculation time. Moreover, we indicated that the circadian clock plays an important role in regulating time-of-day differences in NHR to P. oryzae in Arabidopsis. However, the involvement of photoperiod in regulating NHR was still not understood. To determine the photoperiod role, we performed the experiments in continuous light and darkness during the early Arabidopsis–P. oryzae interaction. We found that the light period after the inoculation in the evening enhanced the resistance to penetration. However, the dark period after the inoculation in the morning suppressed the penetration resistance. Furthermore, the genetic analysis indicated that jasmonic acid, reactive oxygen species, and tryptophan-derived metabolite(s) contribute to the photoperiod regulation of NHR in Arabidopsis. The present results denote that photoperiod plays an important role in regulating time-of-day differences in NHR to P. oryzae in Arabidopsis.

Force kinematic analysis of the process of needle punching of woven preforms

Описан процесс трансверсального армирования плетеных преформ иглопробивкой. Определен процесс взаимодействия иглы с оплеточными жгутами с учетом деформационных процессов изменения амплитуды переплетения и проскальзыванием жгутов плетеной структуры материала при введении иглы. Приведены экспериментальные данные сопротивления проникновению иглы в преформу и подложку. The process of transverse reinforcement of woven preforms with needle punching is described. The process of interaction of the needle with the braiding cords is determined, taking into account the deformation processes of the change in the weave amplitude and the slippage of the cords of the woven structure of the material when the needle is inserted. Experimental data on resistance to penetration of the needle into the preform and substrate are presented.

Spatial variability of soil penetration resistance in the lowland area cultivated with soybean

ABSTRACT: This study determined the spatial variability of soil penetration resistance and yield of the soybean crop in lowland areas. The soil resistance to penetration at four different depths (0 to 0.10 m; 0.11 to 0.20 m; 0.21 to 0.30 m and 0.31 to 0.40 m), volumetric humidity of the soil at two depths (0 to 0.20 m and 0.21 to 0.40 m) and soybean yield were determined in an area of 1.13 hectares, using a sample mesh of 10 x 10 m. The corresponding data were subjected to descriptive statistical analysis. Pearson’s simple linear correlation analysis (p≤0.05) was conducted and the spatial dependence was assessed by analyzing the isotropic semivariograms using spherical, exponential, linear, and Gaussian models. The results showed that the soil penetration resistance increased with depth, with restrictive values to root growth between 0.05 and 0.35 m. There was no correlation between yield and soil penetration resistance, and the semivariograms did not show a defined ascending region regarding the soil penetration resistance data. For the conditions under which the experiment was conducted, the sample 10 x 10 m mesh was suitable for assessing the spatial variability of soil resistance to penetration in depths exceeding 0.10 m.