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991.
The nonequilibrium dynamics and aging behavior of a supercooled liquid is investigated from an analysis of the correlation of density fluctuations at two different times. The dynamic correlation functions are computed by solving numerically the equations of nonlinear fluctuating hydrodynamics. The aging time dependence follows a modified stretched exponential form with a relaxation time which is dependent on the aging time. This is similar to the behavior seen in the aging data of dielectric response functions of a typical glass forming liquid. 相似文献
992.
As part of a comprehensive review on molecular oxygen spectroscopy, we have measured rotational spectra of isotopic forms of molecular oxygen in its a(1)Δ(g) electronic state with high-resolution terahertz spectroscopy. The data are recorded in close proximity to predicted positions. Due to the high resolution and good signal-to-noise ratio, the fundamental hyperfine parameters eQq and C(I) are determinable for (17)O-substituted species for the first time. A refined nuclear spin orbit coupling constant, a = -211.9328(283) MHz, was determined, and is roughly two orders of magnitude more precise than values determined from near infrared spectroscopy or electron spin resonance studies. Vibrationally excited oxygen in the a(1)Δ(g) electronic state was also observable with small signal levels for many of the rotational transitions. 相似文献
993.
To elucidate the reactive behavior of RDX crystals at pressures and temperatures relevant to shock wave initiation, Raman spectroscopy and optical imaging were used to determine the pressure-temperature (P-T) stability and the decomposition of γ-RDX, the high pressure phase of RDX. Experiments were performed on single crystals in a diamond anvil cell at pressures from 6 to 12 GPa and at temperatures up to 600 K. Evidence for the direct decomposition of γ-RDX above 6 GPa, without the involvement of other phases, is provided. The upper limit of the P-T locus for the γ-RDX thermal decomposition was determined. A refined P-T phase diagram of RDX is presented that includes the current findings for γ-RDX. The static compression results are used to gain key insight into the shock initiation of RDX, including a determination of the RDX phase at decomposition and understanding the role of pressure and temperature in accelerating shock induced decomposition. This study has established the important role that γ-RDX plays in decomposition of RDX under static and shock compression conditions; thus theoretical modeling of RDX decomposition at high pressures and temperatures needs to incorporate the γ-phase response. 相似文献
994.
In this paper, we study the bivariate lognormal distribution from a reliability point of view. The conditional distribution of X given Y > y is found to be log‐skew normal. The monotonicity of the hazard rates of the univariate as well as the conditional distributions is discussed. Clayton's association measure is obtained in terms of the hazard gradient, and its value in the case of our model is derived. The probability distributions, in the case of series and parallel systems, are derived, and the monotonicity of their failure rates is discussed. Three real applications of the bivariate lognormal distribution are provided, two from financial economics and one from reliability. Copyright © 2012 John Wiley & Sons, Ltd. 相似文献
995.
In this paper, we introduce fuzzy mathematical programming (FMP) for decision-making related to software creation by selecting
optimal commercial-off-the-shelf (COTS) products in a modular software system. Each module in such software systems have different
alternatives with variations in their properties, for example, quality, reliability, execution time, size and cost. Due to
these variations, component-based software developers generally deals with the problem of selecting appropriate COTS products.
The development of COTS-based systems largely depends on the success of the selection process. Various crisp optimization
models of COTS products selection have been proposed in literature. However, in real COTS products selection problem, it is
difficult to estimate precisely the values of various model parameters due to lack of sufficient data and also because of
measurement errors. Hence, instead of crisp optimization model, if we use flexible optimization model then we might obtain
results which are more preferred by the decision maker. In this study, we use multiple methodologies such as quality model,
analytical hierarchy process and FMP to develop fuzzy multiobjective optimization model of the COTS products selection. To
determine a preferred compromise solution for the multiobjective optimization problem, an interactive fuzzy approach is used. 相似文献
996.
Silicon (Si) nanoparticles with average size of 13 nm and orange–red luminescence under UV absorption were synthesized using electrochemical etching of silicon wafers. A film of Si nanoparticles with thickness of 0.75 µm to 2.6 µm was coated on the glass (TiO2 side) of a dye‐sensitized solar cell (DSSC). The cell exhibited nearly 9% enhancement in power conversion efficiency (η) at film thickness of ~2.4 µm under solar irradiation of 100 mW/cm2 (AM 1.5) with improved fill factor and short‐circuit current density. This study revealed for the first time that the Si‐nanoparticle film converting UV into visible light and helping in homogeneous irradiation, can be utilized for improving the efficiency of the DSSCs. (© 2012 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
997.
An analysis for vibration of non-homogenous visco-elastic rectangular plate of linearly varying thickness subjected to thermal
gradient has been discussed in the present investigation. For visco-elastic, the basic elastic and viscous elements are combined.
We have taken Kelvin model for visco-elasticity that is the combination of the elastic and viscous elements in parallel. Here
the elastic element means the spring and the viscous element means the dashpot. The governing differential equation of motion
has been solved by Galerkin’s technique. Deflection, time period and logarithmic decrement at different points for the first
two modes of vibration are calculated for various values of thermal gradients, non homogeneity constant, taper constant and
aspect ratio for non-homogenous visco-elastic rectangular plate which is clamped on two parallel edges and simply supported
on remaining two edges. Comparison studies have been carried out with homogeneous visco-elastic rectangular plate to establish
the accuracy and versatility. 相似文献
998.
M.A. Iqbal G. Gupta A. Diwakar N.K. Gupta 《European Journal of Mechanics - A/Solids》2010,29(4):683-694
Three-dimensional numerical simulations were carried out to study the ballistic resistance of ductile targets subjected to normal impact by the projectiles. 12 mm thick Weldox 460 E steel targets were impacted by 20 mm diameter conical nosed projectiles and 1 mm thick 1100-H12 aluminum targets were impacted by 19 mm diameter ogive nosed projectiles. The internal nose angle of conical projectile was varied (33.4°–180°) and found to have significant effect on the ballistic limit of 12 mm thick Weldox 460 E steel target. Similarly, the caliber radius head (CRH) of ogive nosed projectile was varied (0–2.5) and found to have significant effect on the ballistic limit of 1 mm thick 1100-H12 aluminum target. The ballistic limit of 12 mm thick Weldox 460 E steel target increased almost linearly with the decrease in the projectile nose angle. While the ballistic limit of 1 mm thick 1100-H12 aluminum target increased as the CRH increased from 0 to 0.5 and with further increase in CRH to 1.0, 1.5, 2.0 and 2.5 its values were found to drop quite significantly. ABAQUS/Explicit finite element code was used to carry out the numerical simulations. 相似文献
999.
Raj K Gupta 《Pramana》2001,57(2-3):481-492
The quantum mechanical fragmentation theory (QMFT), given for the cold synthesis of new and superheavy elements, is reviewed
and the use of radioactive nuclear beams (RNB) and targets (RNT) is discussed. The QMFT is a complete theory of cold nuclear
phenomena, namely, the cold fission, cold fusion and cluster radioactivity. Also, the structure calculations based on the
axially deformed relativistic mean field (DRMF) approach are presented which predict new regions of spherical magicity, namely
Z=120 and N=172 or 184, for superheavy nuclei. This result is discussed in the light of recent experiments reporting the cold synthesis
of Z=118 element. 相似文献
1000.
Dhruba Gupta C Samanta R Kanungo P Basu Subinit Roy S Kailas A Chatterjee B J Roy K Mahata A Samant A Shrivastava 《Pramana》2001,57(1):209-213
Inclusive cross sections of α particles and tritons from the breakup of 42 MeV 7Li by 12C and 197Au targets are presented and analysed in the framework of the Serber model. Spectral distortions due to the targets and relevant
reaction mechanisms are discussed. 相似文献