to control the nonlinear numerical instability, throughout the time evolution of the eulerian form of the nonlinear rotating shallow water equations, it is necessary to add numerical diffusion to the solution. it is clear that, this extra numerical diffusion degrades the accuracy of the numerical solution and should be kept as small as possible. in a conventional approach a hyper-diffusion is u...

In this note we study the dynamics of the natural evaluation action of the group of isometries G of a locally compact metric space (X, d) with one end. Using the notion of pseudocomponents introduced by S. Gao and A. S. Kechris we show that X has only finitely many pseudo-components exactly one of which is not compact andG acts properly on this pseudo-component. The complement of the non-compac...

The temperature inversion symmetry, for a non interacting super-symmetric ensemble, at finite volume, is studied. It is found that, the scaled free energy, f (ξ), is antisymmetric under temperature inversion transformation, i.e. f (ξ) = −ξ d f (1 ξ). This occurs for antiperiodic bosons and periodic fermions, in the compact dimension. On the contrary , for periodic bosons and antiperiodic fermio...

the compact finite difference schemes have been found to give simple ways of reaching the objectives of high accuracy and low computational cost. during the past two decades, the compact schemes have been used extensively for numerical simulation of various fluid dynamics problems. these methods have also been applied for numerical solution of some prototype geophysical fluid dynamics problems ...

the aim of this study is 3-d inversion of magnetic data acquired from the sorkheh-dizej iron-bearing region in zanjan province, iran, in order to determine the geometrical distribution of the buried magnetic sources. for this purpose, our program discretizes the subsurface region into vertical right rectangular prisms and uses the nonlinear marquardt-levenberg algorithm to optimize the unknown ...

A three-dimensional (3-D) inversion scheme for fixedoffset ground penetrating radar (GPR) is derived that takes into account the loss in the soil and the planar air–soil interface. The forward model of this inversion scheme is based upon the first Born approximation and the dyadic Green function for a two-layer medium. The forward model is inverted using the Tikhonov-regularized pseudo-inverse ...

We consider the pseudo-inversion operation inspired by a biological event as a result of the partial inversion. We define the pseudoinversion of a string w = uxv to consist of all strings vxu, where uv = λ and consider the operation from a formal language theoretic viewpoint. We show that regular languages are closed under the pseudoinversion operation whereas context-free languages are not. Fu...

in this paper high order multidimensional positive definite advection transport algorithm (mpdata) and compact finite difference methods are applied to one (1-d) and two-dimensional (2-d) advection equation. mpdata methods are designed based on upwind scheme using anti-diffusive velocity that compensates diffusivity of upwind method. in high order compact method one implicit relation between a ...