In this paper, we study first and second order positive numerical methods for the advection equation. In particular, we consider the direct discretization of the model problem and comment on its superiority to the so called method of lines. Moreover, we investigate the accuracy, stability and positivity properties of the direct discretization. The numerical results related to several test probl...

Finite volume methods are a class of discretization schemes that have proven highly successful in approximating the solution of a wide variety of conservation law systems. They are extensively used in fluid mechanics, meteorology, electromagnetics, semi-conductor device simulation, models of biological processes and many other engineering areas governed by conservative systems that can be writt...

The ability of photorefractive crystals such as barium titanate and strontium barium niobate to record spatially phase shifted real time holograms with high diffraction efficiency is the basis of many new optical devices involving coherent amplification. Some examples are unidirectional ring resonators, passive phase conjugate mirrors and coherent image amplifiers. 1 While in the past, most att...

In this work, thermo-optical properties of gold nanoparticle colloids are studied using continuous wave (CW) laser irradiation at 532 nm. The nanoparticle colloids are fabricated by 18 ns pulsed laser ablation of pure gold plate in the distilled water. The formation of the nanoparticles has been evidenced by optical absorption spectra and transmission electron microscopy. The nonlinear optical ...

This paper develops the high-order accurate entropy stable (ES) finite difference schemes for shallow water magnetohydrodynamic (SWMHD) equations. They are built on numerical approximation of modified SWMHD equations with Janhunen source term. First, second-order well-balanced semi-discrete conservative (EC) constructed, satisfying identity given convex function and preserving steady states lak...

The two experimental campaign with lithium gettering of the T-10 chamber were carried out. The experiments were aimed to prove the lithium abilities to obtain high performance discharges with lithium cover of the wall and limiters with reduced recycling of the working gas and the impurities level in ohmic and heated with the high ECR power tokamak discharges. The second goal of the T-10 experim...

In the Quarterly Progress Report of October 15, 1957, page 52, we pointed out that we had devised a feedforward-across-the-limiter technique that could be arranged to suppress whichever of two cochannel FM signals is undesired. A simple experimental model of this system was built and tested (1). Before summarizing the experimental results, we shall present a resume of the appropriate theoretica...