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The free vibration characteristics of laminated composite and sandwich plates with embedded and/or surface-bonded piezoelectric layers is studied, where a hybrid plate theory is proposed for modelling the structural system. It involves a problem of coupled electro-mechanical field. The variation of mechanical/structural displacements across the thickness are modelled by an efficient plate theory, which ensures inter-laminar shear stress continuity as well as stress free condition at the plate top and bottom surfaces. At the same time, this plate model has the distinct advantage of involving unknowns at the reference plane (plate mid-plane) only. For the electrical potential, the through thickness variation is modelled by the layer-wise theory, where the unknowns are taken at all the interfaces including top and bottom surfaces of the plate. However, the degrees of freedom for the electric potential are finally eliminated from the element matrices through condensation. In order to have generality in analysis, the finite element technique is used to approximate the in-plane variation of displacement parameters at the reference plane and electric potential at the different interfaces. For this purpose, an attempt has been made to develop a simple and efficient rectangular element, which satisfies C1 continuity of transverse displacement at the inter-element boundaries. To validate the proposed model, some numerical examples are solved and the results obtained are compared to the published results. As the number of such published results is not sufficient, new examples covering various features are solved to study different aspects of the proposed model. 相似文献
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Steel-fiber reinforced concrete is increasingly being used day by day as a structural material. The complete stress–strain curve of the material in compression is needed for the analysis and design of structures. In this experimental investigation, an attempt has been made to generate the complete stress–strain curve experimentally for steel-fiber reinforced concrete for compressive strength ranging from 30 to 50 MPa. Round crimped fibers with three volume fractions of 0.5%, 0.75% and 1.0% (39, 59, and 78 kg/m3) and for two aspect ratios of 55 and 82 are considered. The effect of fiber addition to concrete on some of the major parameters namely peak stress, strain at peak stress, the toughness of concrete and the nature of the stress–strain curve is studied. A simple analytical model is proposed to generate both the ascending and descending portions of the stress–strain curve. There exists a good correlation between the experimental results and those calculated based on the analytical model. Equations are also proposed to quantify the effect of fiber on compressive strength, strain at peak stress and the toughness of concrete in terms of fiber reinforcing parameter. 相似文献
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Sanjay Chatterji Tanaya Mukherjee Sarkar Pragati Dhang Samhita Deb Sudeshna Sarkar Jayshree Chakraborty Anupam Basu 《Language Resources and Evaluation》2014,48(3):443-477
Dependency grammar is considered appropriate for many Indian languages. In this paper, we present a study of the dependency relations in Bangla language. We have categorized these relations in three different levels, namely intrachunk relations, interchunk relations and interclause relations. Each of these levels is further categorized and an annotation scheme has been developed. Both syntactic and semantic features have been taken into consideration for describing the relations. In our scheme, there are 63 such syntactico–semantic relations. We have verified the scheme by tagging a corpus of 4167 Bangla sentences to create a treebank (KGPBenTreebank). 相似文献
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An alternative control scheme based on finite element method has been developed to solve optimal control problems in space and time domains. The nonlinear Lagrangian is expanded about a given trajectory configuration in terms of a correction vector. The equations of motion are derived retaining only upto quadratic terms. The cost function comprises of total absolute torsional impulse and equations of motion are the constraints. The control of simple and double inverted pendulums is presented here to show the validity of this method. These problems are also solved using the classical Riccati method for comparison. 相似文献
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A significant improvement in sensing speed over the half-V DD bit-line precharge sensing scheme is obtained by precharging the bit line to approximately 2/3 V DD. The 2/3-V DD sensing scheme also results in higher-bit-line capacitance, asymmetrical bit-line swing, and higher power consumption. However, the speed advantage of 2/3-V DD sensing may outweigh the disadvantages and can significantly improve DRAM performance. For the unboosted word-line case, symmetrical bit-line swing can be retained by limiting the bit-line downward voltage swing through a clamping circuit added to the sense amplifier, resulting in almost no loss of stored charge in a cell. The authors show that the 2/3-V DD sensing with a limited bit-line swing has several distinct advantages over the half-V DD sensing scheme and is particularly suitable for high-performance high density CMOS DRAMs 相似文献
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