in this paper, for the first time we have studied theoretically the effect of exchange-correlation holes around electrons in gaalas/gaas/gaalas nanostructure on the temperature-dependent dynamic dielectric function of two-dimensional electron gas by employing random phase, stls and hubbard approximations. also, we have investigated another interesting system which is coupled quantum wells struc...

Optimum design of structures is achieved while the design variables are continuous and discrete. To reduce the computational work involved in the optimization process, all the functions that are expensive to evaluate, are approximated. To approximate these functions, a semi quadratic function is employed. Only the diagonal terms of the Hessian matrix are used and these elements are estimated fr...

This paper deals with the fundamental problem of estimating the distribution function (df) of the duration of the longest path in the stochastic activity network such as PERT network. First a technique is introduced to reduce variance in Conditional Monte Carlo Sampling (CMCS). Second, based on this technique a new procedure is developed for CMCS. Third, a combined approach of simulation and ap...

co-channel interference is a major factor in limiting the capacity and link quality in cellular communications. as the co-channel interference is modeled by lognormal distribution, sum of the co-channel interferences of neighboring cells is represented by the sum of lognormal random variables (rvs) which has no closed-form expression. assuming independent, identically distributed (iid) rvs, the...

this paper presets a method including a combination of the wavelet transform and fuzzy function approximation (ffa) for high impedance fault (hif) detection in distribution electricity network. discrete wavelet transform (dwt) has been used in this paper as a tool for signal analysis. with studying different types of mother signals, detail types and feeder signal, the best case is selected. the...

the potential function of lippincott and schroeder for linear hydrogen bond has been re-examined and extended to nonlinear hydrogen bond. the parameters originally introduced to the potential function by lippincott and schroeder have been determined from the structural parameters such as 0.. .odistance 0-h bond distance, h.. .o distance and hoo angle. thevalidity of harmonic oscillator approxim...