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991.
C Bhattacharya M Rousseau C Beck V Rauch R M Freeman R Nouicer F Haas O Dorvaux K Eddahbi P Papka O Stezowski S Szilner D Mahboub A Szanto de Toledo A Hachem E Martin S J Sanders 《Pramana》2001,57(1):203-207
The possible occurrence of highly deformed configurations is investigated in the 40Ca and 56Ni di-nuclear systems as formed in the 28Si + 12C, 28Si reactions by using the properties of emitted light charged particles. Inclusive as well as exclusive data of the heavy
fragments and their associated light charged particles have been collected by using the ICARE charged particle multidetector
array. The data are analysed by Monte Carlo CASCADE statistical-model calculations using a consistent set of parameters with
spin-dependent level densities. Significant deformation effects at high spin are observed as well as an unexpected large 8Be cluster emission of a binary nature. 相似文献
992.
Experimental Mechanics - Digital image correlation (DIC) is a powerful experimental technique to determine displacement and strain fields. DIC methods usually require a large number of high... 相似文献
993.
P. S. Ghosh N. P. Ghosh S. Bhattacharya L. K. Samanta 《Crystal Research and Technology》1991,26(1):121-124
Using various Q switching techniques the performance potential of some Nd: glass rods have been analysed and compared with that of a standard rod. Second harmonics generated from such a Q-switched system have been separated from the fundamental using suitable dispersive element. 相似文献
994.
We present systematic studies of the temperature dependence of linewidths and lifetimes of excitonic transitions in quantum wells grown by molecular beam epitaxy using both photoluminescence(PL) and optical absorption. The temperature ranged from 6K to room temperature. Samples under investigation were lattice-matched GaAs/AlGaAs and InGaAs/InAlAs, and strained InGaAs/GaAs and InGaAs/AlGaAs quantum wellssystems. In addition, the effects of well-size variations in GaAs/AlGaAs quantum wells were measured and analyzed. In all cases we were able to observe the excitonic transitions up to room temperature. By a careful fitting of the experimental data we separated the exciton transitions from band-to-band transitions. By deconvoluting the excitonic transitions we obtained the homogeneous and inhomogeneous linewidths. The homogeneous linewidths were used to calculate the exciton lifetimes as a function of temperature using the Heisenberg uncertainty principle. We found the lifetime decreases significantly with temperature and increases with increasing well size. These results are interpreted in terms of the exciton-phonon interaction and are expected to be very useful for the design of semiconductor optical devices operating at different temperatures. 相似文献
995.
A new method that combines phase shifting photoelasticity and transmission Coherent Gradient Sensing (CGS) is developed to
determine the tensorial stress field in thin plates of photoelastic materials. A six step phase shifting photoelasticity method
determines principal stress directions and the difference of principal stresses. The transmission CGS method utilizes a standard
four step phase shifting method to measure the x and y first derivatives of the sum of principal stresses. These stress derivatives are numerically integrated using a weighted
preconditioned conjugate gradient (PCG) algorithm, which is also used for the phase unwrapping of the photoelastic and CGS
phases. With full-field measurement of the sum and difference of principal stresses, the principal stresses may be separated,
followed by the Cartesian and polar coordinate stresses using the principal stress directions. The method is demonstrated
for a compressed polycarbonate plate with a side V-shaped notch. The experimental stress fields compare well with theoretical
stress fields derived from Williams solution for a thin plate with an angular corner. 相似文献
996.
C. Thinaharan D. K. Aswal A. Singh S. Bhattacharya N. Joshi S. K. Gupta J. V. Yakhmi 《Crystal Research and Technology》2004,39(7):572-576
We have grown single crystals of recently discovered thermoelectric oxide material NaxCoO2 using NaCl flux. Crystals of sizes upto 1.5 x 1.5 x 1.5 mm3 having different morphological habits were reproducibly grown. The atomic force microscopic studies show that along c‐axis crystals grow via 2D layer‐by‐layer mechanism. The X‐ray diffraction analyses show that grown crystals are rich in Na content as compared to the starting charge indicating that NaCl flux also acts as a source of Na. The resistivity of the crystals exhibited a linear temperature dependence in the region between 30 and 300 K. © 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim 相似文献
997.
998.
L. Tian L. Tevet-Deree G. deBotton K. Bhattacharya 《Journal of the mechanics and physics of solids》2012,60(1):181-198
The coupled electromechanical response of electroactive dielectric composites is examined in the setting of small deformation and moderate electric field. In this setting, the mechanical stress depends quadratically on the electric field through a combination of material electrostriction and Maxwell stress. It is rigorously shown that the macroscopic mechanical stress of the composite also depends quadratically on the macroscopic electric field. It is further demonstrated that the effective electromechanical coupling can be computed from the examination of the uncoupled electrostatic and elastic problems. The resulting expressions suggest that the effective electromechanical coupling may be very large for microstructures that lead to significant fluctuations of the electric field. This idea is explored through examples involving sequential laminates. It is demonstrated that the electromechanical coupling – the macroscopic strain induced in the composite through the application of a unit electric field – can be amplified by many orders of magnitude by either a combination of constituent materials with high contrast or by making a highly complex and polydisperse microstructure. These findings suggest a path forward for overcoming the main limitation hindering the development of electroactive polymers. 相似文献
999.
Somesh Kr. Bhattacharya Anjali Kshirsagar 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2008,48(3):355-364
Density functional calculations of structural and electronic properties
of stoichiometric and nonstoichiometric
CdTe clusters, containing up to few tens of atoms, are carried out
using projector augmented wave method.
Molecular dynamics has been performed
for Cd12Te12 and Cd15Te15
to predict the structure corresponding to global energy minimum.
Cage type structures and bulk fragments, both in zinc blende and
wurtzite structures, are used as starting geometries and
conjugate gradient method is used to locate the local energy minima for other clusters.
The aim of these calculations is to get the energetically favorable probable
structures, to be compared with the experimentally known
structures. Clusters are relaxed both in vacuum and in
the presence of surface passivating ligands and the resulting structural
rearrangement is analyzed. As expected, passivation increases the stability of an
individual cluster, as indicated by specific properties like binding energy,
vertical detachment energy, electron affinity etc.
Passivation also locks the symmetry for three-dimensional structures but the small
CdnTen (1 ≤ n ≤ 6) clusters, which are planar, attain higher
symmetry structures on passivation.
We observe `self-healing' mechanism viz., opening of optical
gap on relaxation without the aid of passivating ligand, in CdTe clusters as
observed in CdSe clusters [A. Puzder et al., Phys. Rev. Lett. 92,
217401 (2004)]. However, we note that 'self-healing' is a stoichiometry dependent
phenomenon. Te atoms are found to achieve a total coordination of 4 on passivation,
a fact useful in chemical synthesis of nanoclusters. 相似文献
1000.
Subhra Bhattacharya Subenoy Chakraborty 《The European Physical Journal C - Particles and Fields》2017,77(8):558
The scalar–tensor f(R) theory of gravity is considered in the framework of a simple inhomogeneous space-time model. In this research we use the reconstruction technique to look for possible evolving wormhole solutions within viable f(R) gravity formalism. These f(R) models are then constrained so that they are consistent with existing experimental data. Energy conditions related to the matter threading the wormhole are analyzed graphically and are in general found to obey the null energy conditions (NEC) in regions around the throat, while in the limit \(f(R)=R,\) NEC can be violated at large in regions around the throat. 相似文献