Search results for "finite difference method"
showing 10 items of 63 documents
Mathematical Models and their Solutions for Domains of Compex Form
2014
Promocijas darbā tiek apskatīti dažādi oriģināli modeļi un to risinājumi sarežģītas formas apgabaliem. Intensīvās tērauda rūdīšanas procesi sistēmām ar ribām tiek aprakstīti ar 3D hiperbolisko, kā arī ar klasisko siltuma vadīšanas vienādojumu. Precīzā atrisinājuma iegūšanai izmantota Grīna funkciju metode un tās vispārinājums. Modernajos datoros sastopamajām sistēmām ar dubulsieniņu un dubultribu dota stacionārā un nestacionārā siltumvadīšanas problēma 2D gadījumā. Tās risinājums tiek iegūts ar konservatīvās viduvēšanas metodi, galīgo diferenču metodi un tās modifikāciju robežnosacījumiem. Piedāvāts jauns matemātiskais modelis vītola flautai, problēmas formulējumā izmantojot 1D lineāru viļņ…
Physical modeling of heat and moisture transfer in wet bio-sourced insulating materials.
2018
Simultaneous heat and moisture transfers in bio-sourced insulating materials are significant phenomena in thermal metrology. The present study focuses on these phenomena by experimental and numerical approaches based on the asymmetric hot-plate method. In this paper, a bio-sourced insulating material based on flax fibers is developed. The thermal and hygric properties of the sample are then investigated in the humid atmosphere. The temperature is maintained at 30 °C, and the relative humidity varies between 30% and 90% RH. A physics-based model of simultaneous heat and moisture transfer is developed for thermal conductivity estimation. This model is discretized with finite difference method…
APPLICATION OF 3‐D FINITE DIFFERENCE METHOD FOR INDUCTANCE CALCULATION OF AIR‐CORE COILS SYSTEM
1994
The paper deals with the inductance calculation of air‐core coils system by means of 3‐D analysis of magnetic field of the coils with rectangular cross‐section. The possibility of mutual and self‐inductance calculation is presented. For magnetic field calculation, the Finite Difference Method with application of fast calculating procedures was applied. The method of calculation has been verified by experiments. The obtained difference between calculating and measurement results is equal to a few percent. The computer program is usefull especially for asymmetrical configuration of the coils.
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…
A Numerical Approach to Finite Journal Bearings Lubricated With Ferrofluid
1987
Several cases of cylindrical bearings lubricated with ferrofluid are examined by means of a finite-difference numerical procedure. The subregion of cavitation is determined by imposing mass conservation across the “rupture” and “reformation” boundaries of the complete film. The examined cases refer to bearings confined by sealing rings formed by the lubricant itself, for which there is no need of external supply. In each case the most significant parameters are calculated and it is possible to see that the use of these bearings is favorable when speeds are low, clearances large, and loads light, because in such conditions the magnetic effects are comparable with the pure hydrodynamic ones a…
Accuracy of the finite difference method in stochastic setting.
2006
In this paper we study the accuracy of the finite difference method when the finite difference method is applied to approximately analyze the structure.
Numerical simulation of radiated EMI in 42V electrical automotive architectures
2006
The work is focused on the evaluation of radiated electromagnetic interference generated by dc/dc converters in 42 V systems automotive environment. The results obtained by using the method of moments and the finite difference time domain method, separately, are presented and validated in comparison with those measured in a semi-anechoic electromagnetic chamber. A measurement system set up by the authors is employed. Both the used numerical approaches are proved to be an useful tool for radiated disturbance prediction, and also for electromagnetic compatibility oriented design of the vehicle electrical architecture.
American Option Pricing and Exercising with Transaction Costs
2005
In this paper we examine the problem of finding the reservation option prices and corresponding exercise policies of American options in a market with proportional transaction costs using the utility based approach proposed by Davis and Zariphopoulou (1995). We present a model where the option holder has a constant absolute risk aversion. We discuss the numerical algorithm and propose a new characterization of the option holder's value function. We suggest original discretization schemes for computing reservation prices and exercise policies of American options. The discretization schemes are implemented for the cases of American put and call options. We present the study of the optimal tra…
Controllability method for acoustic scattering with spectral elements
2007
We formulate the Helmholtz equation as an exact controllability problem for the time-dependent wave equation. The problem is then discretized in time domain with central finite difference scheme and in space domain with spectral elements. This approach leads to high accuracy in spatial discretization. Moreover, the spectral element method results in diagonal mass matrices, which makes the time integration of the wave equation highly efficient. After discretization, the exact controllability problem is reformulated as a least-squares problem, which is solved by the conjugate gradient method. We illustrate the method with some numerical experiments, which demonstrate the significant improveme…
The finite element method for the mechanically based model of non-local continuum
2011
SUMMARY In this paper the finite element method (FEM) for the mechanically based non-local elastic continuum model is proposed. In such a model each volume element of the domain is considered mutually interacting with the others, beside classical interactions involved by the Cauchy stress field, by means of central body forces that are monotonically decreasing with their inter-distance and proportional to the product of the interacting volume elements. The constitutive relations of the long-range interactions involve the product of the relative displacement of the centroids of volume elements by a proper, distance-decaying function, which accounts for the decrement of the long-range interac…