Search results for "Names"
showing 10 items of 6843 documents
A Divergence-Free High-Resolution Code for MHD
2001
We describe a 2.5D numerical code to solve the equations of ideal magnetohydrodynamics (MHD). The numerical code, based on high-resolution shock-capturing (HRSC) techniques, solves the equations written in conservation form and computes the numerical fluxes using a linearized Riemann solver. A special procedure is used to force the conservation of magnetic flux along the time.
Exact results for the homogeneous cooling state of an inelastic hard-sphere gas
1998
The infinite set of moments of the two-particle distribution function is found exactly for the uniform cooling state of a hard-sphere gas with inelastic collisions. Their form shows that velocity correlations cannot be neglected, and consequently the 'molecular chaos' hypothesis leading to the inelastic Boltzmann and Enskog kinetic equations must be questioned. © 1998 Cambridge University Press.
The time-harmonic Maxwell equations
1996
In this chapter we shall see that the solution of the time-harmonic Maxwell equations with real coefficients can be transformed to time independent partial differential equations with complex coefficients. Then we introduce a finite element approximation proposed in [Křižek, Neittaanmaki, 1989]. A similar technique is analyzed in [Křižek, Neittaanmaki, 1984b], [Monk, 1992a] (for fully time dependent problems see, e.g., [Monk 1992b,c]).
Maxwell’s Equations
2012
The empirical basis of electrodynamics is defined by Faraday’s law of induction, by Gauss’ law, by the law of Biot and Savart and by the Lorentz force and the principle of universal conservation of electric charge. These laws can be tested – confirmed or falsified – in realistic experiments. The integral form of the laws deals with physical objects that are one-dimensional, two-dimensional, or three-dimensional, that is to say, objects such as linear wires, conducting loops, spatial charge distributions, etc. Thus, the integral form depends, to some extent, on the concrete experimental set-up. To unravel the relationships between seemingly different phenomena, one must switch from the integ…
Stability of Relativistic Hydrodynamical Planar Jets: Linear and Nonlinear Evolution of Kelvin-Helmholtz Modes
2004
Some aspects about the stability of relativistic flows against Kelvin-Helmholtz (KH) perturbations are studied by means of relativistic, hydrodynamical simulations. In particular, we analyze the transition to the fully nonlinear regime and the long-term evolution of two jet models with different specific internal energies.
Transport Properties of Correlated Electrons in High Dimensions
2003
We develop a new general algorithm for finding a regular tight-binding lattice Hamiltonian in infinite dimensions for an arbitrary given shape of the density of states (DOS). The availability of such an algorithm is essential for the investigation of broken-symmetry phases of interacting electron systems and for the computation of transport properties within the dynamical mean-field theory (DMFT). The algorithm enables us to calculate the optical conductivity fully consistently on a regular lattice, e.g., for the semi-elliptical (Bethe) DOS. We discuss the relevant f-sum rule and present numerical results obtained using quantum Monte Carlo techniques.
Identification of spatially confined states in two-dimensional quasiperiodic lattices.
1995
We study the electronic eigenstates on several two-dimensional quasiperiodic lattices, such as the Penrose lattice and random-tiling lattices, using a tight-binding Hamiltonian in the vertex model. The infinitely degenerate states at E=0 are especially investigated. We present a systematic procedure which allows us to identify numerically the spatially strongly localized so-called confined states.
On the theory of domain structure in ferromagnetic phase of diluted magnetic semiconductors
2006
Abstract We present a comprehensive analysis of domain structure formation in ferromagnetic phase of diluted magnetic semiconductors (DMS) of p-type. Our analysis is carried out on the base of effective magnetic free energy of DMS calculated by us earlier [Yu.G. Semenov, V.A. Stephanovich, Phys. Rev. B 67 (2003) 195203]. This free energy, substituting DMS (a disordered magnet) by effective ordered substance, permits to apply the standard phenomenological approach to domain structure calculation. Using coupled system of Maxwell equations with those obtained by minimization of above free energy functional, we show the existence of critical ratio ν cr of concentration of charge carriers and ma…
General measurement technique of the ratio between chromatic dispersion and the nonlinear coefficient
2021
Measuring the nonlinear coefficient γ of any guiding medium, regardless of the sign and magnitude of its group-velocity dispersion parameter β 2 , is challenging because of the lack of general solutions of the nonlinear Schrodinger equation (NLSE). Indeed, existing approaches typically need to disregard chromatic-dispersion effects to determine γ [1] . Here we propose an all-encompassing approach to measure the ratio β 2 /γ and prove our method in polarization-maintaining (PM) and single-mode (SM) fibers with positive and negative β 2 .
Systems of Linear Equations
2016
A linear equation in \(\mathbb {R}\) in the variables \(x_1,x_2,\ldots ,x_n\) is an equation of the kind: