Decoupled three-dimensional finite element computation of thermoelastic damping using Zener’s approximation

We consider three dimensional finite element computations of thermoelastic damping ratios of arbitrary bodies using Zener’s approach. In our small-damping formulation, unlike existing fully coupled formulations, the calculation is split into three smaller parts. Of these, the first sub-calculation involves routine undamped modal analysis using ANSYS. The second sub-calculation takes the mode shape, and solves on the same mesh a periodic heat conduction problem. Finally, the damping coefficient is a volume integral, evaluated elementwise. In the only other decoupled three dimensional computation of thermoelastic damping reported in the literature, the heat conduction problem is solved much less efficiently, using a modal expansion. We provide numerical examples using some beam-like geometries, for which Zener’s and similar formulas are valid. Among these we examine tapered beams, including the limiting case of a sharp tip. The latter’s higher-mode damping ratios dramatically exceed those of a comparable uniform beam.     

Performance limit for base-excited energy harvesting,and comparison with experiments

Nonlinear Dynamics - We consider the theoretical maximum extractable average power from an energy harvesting device attached to a vibrating table which provides a unidirectional displacement...     

Kinetic market models with single commodity having price fluctuations

We study here numerically the behavior of an ideal gas like model of markets having only one non-consumable commodity. We investigate the behavior of the steady-state distributions of money, commodity and total wealth, as the dynamics of trading or exchange of money and commodity proceeds, with local (in time) fluctuations in the price of the commodity. These distributions are studied in markets with agents having uniform and random saving factors. The self-organizing features in money distribution are similar to the cases without any commodity (or with consumable commodities), while the commodity distribution shows an exponential decay. The wealth distribution shows interesting behavior: gamma like distribution for uniform saving propensity and has the same power-law tail, as that of the money distribution, for a market with agents having random saving propensity.     

Sub-barrier fission fragment angular distributions for the system19F+232Th

The measurements of fission fragment angular distributions for the system¹⁹F+²³²Th have been extended to the sub-barrier energies of 89.3, 91.5 and 93.6 MeV. The measured anisotropies, within errors are nearly the same over this energy region. However, the deviation of the experimental values of anisotropies from that of standard statistical model predictions increases as the bombarding energy is lowered.     

Determination of heavy metals in industrial wastes by SXRF method

Samples of the raw input material and industrial wastes collected at different processing stages of lead smelting units have been analyzed using the synchrotron induced X-ray fluorescence method to detect and estimate the presence of heavy metals. Heavy metals such as Sb, Cd, Sn, Pb are found to be present in significant amounts.     

On use of ghost-less beam splitter in reversal shear interferometer for measurement of spatial coherence of large cross-section laser beam

A configuration of reversal shear interferometer suitable for measurement of spatial coherence of high average power, large cross-section laser beam has been discussed. Ghost-less beam splitters in which unwanted multiple reflections from the surfaces have been suppressed by total internal reflection are used for beam splitting and re-combination. Advantages and drawbacks of this configuration have been discussed.     

Effects of screening on quark-antiquark cross sections in quark-gluon plasma

Lowest-order cross sections for qq? production and annihilation can be approximately corrected for higher-order QCD effects by using a corrective K-factor. For energies where quark masses cannot be ignored, the K-factor is dominated by the wave function distortion arising from the initialor final-state interaction between the quark and the antiquark. We evaluate this K-factor for qq? production and annihilation in a quark-gluon plasma by taking into account the effects of Debye screening through a color-Yukawa potential. We present the corrective K-factor as a function of dimensionless parameters which may find applications in other systems involving attractive or repulsive Yukawa interactions. Prominent peaks of the K-factor occur for an attractive q-q? color-Yukawa interaction with Debye screening lengths of 0.835 and 3.23 times the Bohr radius, corresponding to two lowest s-wave qq? bound states moving into the continuum to become qq? resonances as the Debye screening length decreases. These resonances, especially the cc? and the bb? resonances, may be utilized to study the quark-gluon plasma by examining the systematics of the temperature dependence of heavy-quark pair production just above the threshold.