Search results for "difference [momentum]"
showing 10 items of 141 documents
Evaluation of radiated EMI in 42 V vehicle electrical systems by FDTD simulation
2007
In this paper a full 3D numerical scheme, based on the finite difference time domain method, is used to predict the electromagnetic radiated interference generated by 42 V vehicle power electronic driven electrical loads. An experimental set-up has been arranged on purpose in order to validate the proposed simulation tool. To this aim, the features of a semi-anechoic electromagnetic chamber have been exploited in order to operate in a shielded test site for the measurement of near field radiated emissions. Two different three-dimensional geometrical configurations of realistic vehicle installations of the loads, are studied. A comparative analysis among measured and computed results is perf…
Finite difference time domain simulation of earth electrodes soil ionisation under lightning surge condition
2008
The non linear effects of soil ionisation on the behaviour of earth electrodes are investigated by a finite difference time domain numerical scheme. A time variable soil resistivity is used in order to simulate the soil breakdown; step by step the resistivity value is controlled by the local instantaneous value of the electric field compared with the electrical strength, fixed for the soil. No a priori hypothesis about the geometrical shape of the ionised zone around the electrodes has to be enforced. Simulation results related to complex earth electrodes of limited extension are reported. The model has been validated by comparing the computed results with data available in technical litera…
Simple algorithms for calculation of the axial‐symmetric heat transport problem in a cylinder
2001
The approximation of axial‐symmetric heat transport problem in a cylinder is based on the finite volume method. In the classical formulation of the finite volume method it is assumed that the flux terms in the control volume are approximated with the finite difference expressions. Then in the 1‐D case the corresponding finite difference scheme for the given source function is not exact. There we propose the exact difference scheme. In 2‐D case the corresponding integrals are approximated using different quadrature formulae. This procedure allows one to reduce the heat transport problem described by a partial differential equation to an initial‐value problem for a system of two ordinary diff…
A generalized finite difference method using Coatmèlec lattices
2009
Generalized finite difference methods require that a properly posed set of nodes exists around each node in the mesh, so that the solution for the corresponding multivariate interpolation problem be unique. In this paper we first show that the construction of these meshes can be computerized using a relatively simple algorithm based on the concept of a Coatmelec lattice. Then, we present a generalized finite difference method which provides a numerical solution of a partial differential equation over an arbitrary domain, using the generated meshes. The accuracy and mesh adaptivity of the method is evaluated using elliptical equations in several domains.
Efficient finite-difference scheme for solving some heat transfer problems with convection in multilayer media
2000
Abstract An efficient finite-difference method for solving the heat transfer equation with piecewise discontinuous coefficients in a multilayer domain is developed. The method may be considered as a generalization of the finite-volumes method for the layered systems. We apply this method with the aim to reduce the 3D or 2D problem to the corresponding series of 2D or 1D problems. In the case of constant piecewise coefficients, we obtain the exact discrete approximation of the steady-state 1D boundary-value problem.
Introductory Quantum Physics Courses using a LabVIEW multimedia module
2007
We present the development of a LabVIEW multimedia module for introductory Quantum Physics courses and our experience in the use of this application as an educational tool in learning methodologies. The program solves the Time Dependent Schrodinger Equation for arbitrary potentials. We describe the numerical method used for solving this equation, as well as some mathematical tools employed to reduce the calculation time and to obtain more accurate results. As an illustration, we present the evolution of a wave packet for three different potentials: the repulsive barrier potential, the repulsive step potential, and the harmonic oscillator. This application has been successfully integrated in…
Coupled Discrete Fractional-Order Logistic Maps
2021
This paper studies a system of coupled discrete fractional-order logistic maps, modeled by Caputo’s delta fractional difference, regarding its numerical integration and chaotic dynamics. Some interesting new dynamical properties and unusual phenomena from this coupled chaotic-map system are revealed. Moreover, the coexistence of attractors, a necessary ingredient of the existence of hidden attractors, is proved and analyzed.
Nonlocal discrete ∞-Poisson and Hamilton Jacobi equations
2015
In this paper we propose an adaptation of the ∞-Poisson equation on weighted graphs, and propose a finer expression of the ∞-Laplace operator with gradient terms on weighted graphs, by making the link with the biased version of the tug-of-war game. By using this formulation, we propose a hybrid ∞-Poisson Hamilton-Jacobi equation, and we show the link between this version of the ∞-Poisson equation and the adaptation of the eikonal equation on weighted graphs. Our motivation is to use this extension to compute distances on any discrete data that can be represented as a weighted graph. Through experiments and illustrations, we show that this formulation can be used in the resolution of many ap…
The Mathematical Modeling of Ca And Fe Distribution In Peat Layers
2015
Bogs have been formed by an accumulation of peat - a light brown-to-black organic material, built up from partial decomposition of mosses and other bryophytes, sedges, grasses, shrubs, or trees under waterlogged conditions. The total peatlands area in Latvia covers 698 918 ha or 10.7% of the entire territory. Knowledge’s of peat metals content are important for any kind of peat using. Experimental determination of metals in peat is very long and expensive work. Using experimental data mathematical model for calculation of concentrations of metals in different points for different layers can help to very easy and fast to find approximately concentration of metals or trace elements. The resul…
Coaxial Slot Antenna Design for Microwave Hyperthermia using Finite- Difference Time-Domain and Finite Element Method
2011
Hyperthermia also called thermal therapy or thermotherapy is a type of cancer treatment in which body tissue is exposed to high temperatures. Research has shown that high temperatures can damage and kill cancer cells, usually with minimal injury to normal tissues. Otherwise, ablation or high temperature hyperthermia, including lasers and the use of radiofrequency, microwaves, and high-intensity focused ultrasound, are gaining attention as an alternative to standard sur- gical therapies. The electromagnetic microwave irradiation applied to the tumor tissue causes water molecules to vibrate and rotate, resulting in tissue heating and subsequently cell death via thermal-induced protein denatur…