The standard way of deriving Euler-Lagrange (EL) equations given a point particle action is to vary the trajectory and set first variation zero. However, if (i) reparameterisation invariant, (ii) generally covariant, I show that one may derive EL by suitably "nullifying" through judicious coordinate transformation. net result this curve remains fixed, while all other geometrical objects in unde...

in this paper, in order to optimize the portfolio consisting of selected industrial stocks of petroleum products, automobiles and parts, electrical industry and extraction of minerals from tehran stock exchange member, first, time – varying conditional covariance matrix has been estimated based on the following multivariate garch models: diagonal-vech (1,1), ccc (1,1) and diagonal -bekk (1,1). ...

Nano-porous silicon were simply prepared from p-type single crystalline silicon wafer by electrochemical etching technique via exerting constant current density in two different HF-Ethanol and HF-Ethanol-H2O solutions. The mesoporous silicon layers were characterized by field emission scanning electron microscopy and scanning electron microscopy. The results demonstrate that the width of nano-p...

In this paper we investigate certain connections between the class Rs,? of rapidly varying sequences (in sense de Haan) and rapid equivalence, selection principles game theory.

Nowadays with increasing use of numerous nonlinear loads, voltage and current harmonics in power systems are one of the most important problems power engineers encounter. Many of these nonlinear loads, because of their dynamic natures, inject time-varying harmonics into power system. Common techniques applied for harmonics measurement and assessment such as FFT have significant errors in presen...