Electro-Mechanical Buckling of a Piezoelectric Annular Plate Reinforced with BNNTs Under Thermal Environment

ABSTRACT In this article, axisymmetric buckling behavior of piezoelectric fiber reinforced polymeric composite (PFRPC) annular plate subjected to electro-thermo-mechanical field is presented utilizing principle of minimum potential energy. Boron-nitride nanotubes (BNNTs) are used as fibers. Full coupling between electrical, mechanical and thermal fields are considered according to a representative volume element (RVE)-based XY piezoelectric fiber reinforce composite (PEFRC) model. Assuming PFRPC material and its composite constituents to be linear, homogenous, orthotropic, and perfectly bonded with uniform applied field, the basic relation for the axisymmetric buckling of a circular plate subjected to radial compression, radial electrical field, and uniform temperature change T are derived. The presented results show that BNNTs can be used as an effective supplement to improve mechanical behavior of polyvinylidene fluoride (PVDF). Also, at normal working conditions, the influence of thermal and mechanical fields is much higher than the electric one on the critical load; hence, this smart structure is best suited for applications as sensors than actuators

Effect of Row Spacing on Competition of Velvetleaf (Abutilon theophrasti Medic.) with Cotton (Gossypium hirsutum L.)

To investigation the yield and yield component of cotton (Gossypium hirsutum L.) planted in conventional and ultra narrow row spacings, in competition with velvetleaf (Abutilon theophrasti Medic.) an experiment was conducted in a completely randomized block design with split plot arrangement of treatments, with three replications at Experimental Station of Gorgan University of Agricultural Sciences and Natural Resources, during 2011 growing season. The treatments were three row spacings (20, 40 and 80cm) of cotton (as main plot) and five densities (0 (control), 1, 3, 5 and 12 plant.m-2) of velvetleaf (as subplot). Results showed that, almost all vegetative characteristics and yield components of the cotton were decreased with decreasing crop row spacing and increase weed density. In contrast, number of bolls per unit area was increased by reducing cotton row spacing. Rectangular hyperbola model was used to describe relation between cotton yield and weed density. The highest yield (4986.73 kg.ha-1) was obtained in 40 cm cotton row spacing and weed free condition. Cotton yield was decreased with increasing weed density. Based on function estimate, cotton yield lose rooted on come of first weed in competition with cotton planted in 20, 40 and 80 cm row spacing was, 15.59, 34.19 and 66.12, respectively. This study showed that, in ultra-row spacing the cotton is more competitor with over velvetleaf density because increasing the plant density lead to increase the crop ability to resource using in compared with weeds. Too, ultra narrow cotton have produced sustainable yield in competition with over weed density in compared with conventional row

A spectroscopical study of H

A noninvasive diagnostic technique relying on optical emission spectroscopy is used for studying plasma confined in a purely toroidal magnetic field. Visible emission lines of molecular hydrogen were specifically targeted. Bi-dimensional structures and poloidal plasma profiles were reconstructed from the emissivity distribution of hydrogen Fulcher system using a tomographic method. A few details concerning the methods employed to capture different emission viewlines, data reduction and tomographic reconstruction techniques are also addressed. We report also the first measurement of the excitation temperature of the $$\text {H}_2$$ [3c] level in the center of the plasma column, $$T_{\mathrm{exc}}=0.67 \pm 0.11$$ eV