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Search Results: 1 - 10 of 322451 matches for " N. K. Sharma "
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Surface Wave Characteristics at the Interface of Welded Elastic Halfspaces  [PDF]
J. N. Sharma, K. K. Sharma, Ashwani Kumar
Open Journal of Acoustics (OJA) , 2011, DOI: 10.4236/oja.2011.11001
Abstract: The present article concentrates on the propagation of generalized surface acoustic waves in a composite struc- ture consisting of piezoelectric and non-piezoelectric semiconductor media. The mathematical model of the problem is depicted by a set of partial differential equations of motion, Gauss equation in piezoelectric and elec- tron diffusion equation in semiconductor along with boundary conditions to be satisfied at the interface. The secular equation that governs the propagation of surface waves has been derived in compact form after obtaining the formal solution. The analytic expressions for displacements, stresses, piezoelectric potential and electron concentration during the surface wave propagation at the interface have also been obtained. The numerical solu- tion of the secular equation is carried out for the cadmium selenide and silicon composite by employing fixed point functional iteration numerical method along with irreducible Cardano method. The computer simulated results with the help of MATLAB software in respect of dispersion curves, attenuation coefficient, displace- ments, stresses, carrier concentration and piezoelectric potential are presented graphically. This work may be useful in surface acoustic wave (SAW) devices and electronic industry.
Acute pancreatitis and acute renal failure following multiple hornet stings
Sharma, N.;Balamurugeshan, P. K.;Sharma, A.;
Journal of Venomous Animals and Toxins including Tropical Diseases , 2006, DOI: 10.1590/S1678-91992006000200012
Abstract: hymenoptera is a class of insects that sting in order to subdue their prey. humans coming into accidental contact with these insects results in stings that may cause from mild local reaction like weal formation around the sting site to severe systemic reactions such as intravascular hemolysis, acute renal failure, pulmonary edema, cerebral edema, and rarely pancreatitis. we report here the clinical course of a patient who developed concurrent acute pancreatitis and pigment-induced acute renal failure after multiple hornet stings.
Synthesis and Characterization of LPCVD Polysilicon and Silicon Nitride Thin Films for MEMS Applications
N. Sharma,M. Hooda,S. K. Sharma
Journal of Materials , 2014, DOI: 10.1155/2014/954618
Abstract: Inherent residual stresses during material deposition can have profound effects on the functionality and reliability of fabricated MEMS devices. Residual stress often causes device failure due to curling, buckling, or fracture. Typically, the material properties of thin films used in surface micromachining are not very well controlled during deposition. The residual stress, for example, tends to vary significantly for different deposition conditions; experiments were carried out to study the polysilicon and silicon nitride deposited by Low Pressure Chemical Vapor Deposition (LPCVD) method at wide range of process conditions. High temperature annealing effects on stress in case polysilicon are also reported. The reduced residual stress levels can significantly improve device performance, reliability, and yield as MEMS devices become smaller. 1. Introduction The deposition of thin films is an important field of Micro Electro Mechanical Systems (MEMS) or micro system technology. Most of the thin films exhibit stress after deposition. This stress has many different causes. Most films are deposited at elevated temperature. If the thermal expansions of the film and substrate are not identical there will be stress between them after cooling. Other sources are lattice mismatch, crystallization, atomic peening, incorporation of foreign atoms, microscopic voids, variation of interatomic spacing with crystal size, crystallite coalescence at grain boundaries, phase transformations, and texture effect. Sometimes this stress is called internal stress or residual stress. This stress may cause problem for thin film technology. It changes the behavior of the thin films often in an uncontrolled manner (Figure 1 shows the one of the structure under stress), reducing the yields and long term durability and sometimes causing fracture. Many researchers had investigated the mechanical response of thin films, for example. Frequently, each particular investigation involving MEMS tends to be device dependent; type of film used and deposition methods adopted, and introduces new fundamental questions. Progress in this field has leaned towards providing more specific technological solutions rather than generating a basic understanding of mechanical behavior. Figure 1: Effect of residual stress on free standing structure. In the recently developed technology of microsystem, more and more standing thin film structures are used, for example, resonator, movable parts in surface micromachining, thin film membranes, and cantilever beams in transduction [1, 2]. For these applications, the
Four-tangle for pure states
S. Shelly Sharma,N. K. Sharma
Physics , 2009, DOI: 10.1103/PhysRevA.82.012340
Abstract: An expression for four-tangle is obtained by examining the negativity fonts present in a four-way partial transpose under local unitary operations. An alternate derivation of three tangle is also given.
Quantum coherences, K-way negativities and multipartite entanglement
S. Shelly Sharma,N. K. Sharma
Physics , 2007, DOI: 10.1103/PhysRevA.77.042117
Abstract: A characterization of N-partite states, based on K-way (K = 2 to N) negativities, is proposed. The K-way partial transpose with respect to a subsystem is defined so as to shift the focus to K-way coherences instead of K subsystems of the composite system. For an N-partite system the fraction of K-way negativity, contributing to global negativity, is obtained. The entanglement measures for a given state ${\rho}$ are identified as the partial K-way negativities of the corresponding canonical state.
q-deformed pairing-vibrations
S. Shelly Sharma,N. K. Sharma
Physics , 1994, DOI: 10.1103/PhysRevC.50.2323
Abstract: Boson creation operators constructed from linear combinations of q- deformed zero coupled nucleon pair operators acting on the nucleus (A,0), are used to derive pp-RPA equations. The solutions of these equations are the pairing vibrations in (A${\underline{+}}$2) nuclei. For the $0^+_1$ and $0^+_2$ states of the nucleus $^{208}$Pb, the variations of relative energies and transfer cross-sections for populating these states via (t,p) reaction, with deformation parameter $\tau$ have been analysed. For $\tau=0.405$ the experimental excitation energy of 4.87MeV and the ratio $\frac{\sigma(0^+_2) }{\sigma(0^+_1)}=0.45$ are well reproduced. The critical value of pairing interaction strength for which phase transition takes place, is seen to be lower for deformed zero-coupled nucleon pair condensate with $\tau$ real, supporting our earlier conclusion that the real deformation simulates the two-body residual interaction. For $\tau$ purely imaginary a stronger pairing interaction is required to bring about the phase transition. The effect of imaginary deformation is akin to that of an antipairing type repulsive interaction. Using deformed zero coupled quasi-particle pairs, a deformed version of Quasi-boson approximation for $0^+$ states in superconducting nuclei is developed. For the test model of 20 particles in two shells, the results of q-deformed boson and quasi-boson approximations have been compared with exact results. It is found that the deformation effectively takes into account the anharmonicities and may be taken as a quantitative measure of the correlations not being accounted for in a certain approximate treatment.
Local Unitary Invariants for N-qubit Pure State
S. Shelly Sharma,N. K. Sharma
Physics , 2010, DOI: 10.1103/PhysRevA.82.052340
Abstract: We obtain local unitary invariant polynomials for N qubit quantum state from first principles. A basic unit of entanglement, referred to as negativity font, is defined as a two by two matrix of probability amplitudes that determines the negative eigen value of a four by four submatrix of partially transposed state operator. Transformation properties of determinants of negativity fonts under local unitary (LU) transformations are exploited to obtain multi qubit invariants written in terms of such determinants.
Partial K-way negativities and three tangle for three qubit states
S. Shelly Sharma,N. K. Sharma
Physics , 2008, DOI: 10.1103/PhysRevA.78.012113
Abstract: We obtain, analytically, the global negativity, partial $K-$way negativities (K=2, 3), Wooter's tangle and three tangle for the generic three qubit canonical state. It is found that the product of global negativity and partial three way negativity is equal to three tangle, while the partial two way negativity is related to tangle of qubit pairs. We also calculate similar quantities for the state canonical to a single parameter (0
Quantum mutual entropy for two-level ion in a q-analog trap
S. Shelly Sharma,N. K. Sharma
Physics , 2001,
Abstract: Quantum mutual entropy is used as a measure of information content of ionic state due to ion-laser interaction in a q-analog trap. The initial state of the system is a Schrodinger cat state. It is found that the partial mutual entropy is a good measure of the entanglement and purity of the ionic state at $t>0$.
The BCS theory of q-deformed nucleon pairs - qBCS
S. Shelly Sharma,N. K. Sharma
Physics , 2000, DOI: 10.1103/PhysRevC.62.034314
Abstract: We construct a coherent state of q-deformed zero coupled nucleon pairs distributed in several single-particle orbits. Using a variational approach, the set of equations of qBCS theory, to be solved self consistently for occupation probabilities, gap parameter Delta, and the chemical potential lambda, is obtained. Results for valence nucleons in nuclear degenerate sdg major shell show that the strongly coupled zero angular momentum nucleon pairs can be substituted by weakly coupled q-deformed zero angular momentum nucleon pairs. A study of Sn isotopes reveals a well defined universe of (G, q) values, for which qBCS converges. While the qBCS and BCS show similar results for Gap parameter Delta in Sn isotopes, the ground state energies are lower in qBCS. The pairing correlations in N nucleon system, increase with increasing q (for q real).
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