ISSN:0228-6203    

DOI:10.1080/02286203.1981.11759712

出版商:Taylor&Francis    

年代:1981

数据来源: Taylor

ISSN:0228-6203    

DOI:10.1080/02286203.1981.11759713

出版商:Taylor&Francis    

年代:1981

数据来源: Taylor

摘要:

AbstractThe aim of this paper is to pinpoint some problems and proposals to improve comprehensive modeling in the social sciences. I will mainly follow the procedures that have been adopted in our present research project HSDMEL(Hierarchical Sequential Decomposition of a system model for Melle area). The prefered approach to describe reality of regional development by a two-level multi-modular model and some remarks on the technical solutions forrunning multi-modular models are discussed

ISSN:0228-6203    

DOI:10.1080/02286203.1981.11759714

出版商:Taylor&Francis    

年代:1981

数据来源: Taylor

摘要:

SummaryResults obtained by simulation usually depend on scalar or matrix mathematical representations of the studied process, on the tool of simulation and on identification an/or data acquirement errors.Generally for linear process, existing canonical matrix representations lead to simulation schemes which allow a correct description of the system working.In non-linear hypothesis, those canonical forms are more difficult to be implemented and moreover can imply incertainties which result of various drifts and propaaation of truncation errors varying with the mode of choosed simulation and the order of the studied system.We propose here an original matrix representation of non-linear systems, closed in a fiability view point to the modal representation used for linear processes and allowina a new simulation method.It consists on a specific decomposition of the n order non-linear system into n interconnected subsystems including (n-1) arbitrarily choosed linear and stable ones.Then the simulation scheme for this decomposition allows an excellent internal attenuation of errors inherent in the type of the used simulation. and also permits an easy to check convergence test of the used algorithms and simulation technics.A power plant simulation is presented to illustrate an extension of the proposed method to interconnected processes simulation.This application concerns the study of the connection on the same electrical network of two power plants.

ISSN:0228-6203    

DOI:10.1080/02286203.1981.11759715

出版商:Taylor&Francis    

年代:1981

数据来源: Taylor

摘要:

AbstractIn this paper primariLy the pecuLiarities of physicaL systems that affect the whoLe process of modeL formation are presented.Approaches to the choice of regression criterion based on numericaL mathematics–theory of approximation–, mathematicaL statistics–theory of point estimates–as weLL as heuristic search are discussed. Attention is paid to the fact how the particuLar approaches affect interpretation of modeL parameters. In simpLe practicaL exampLes it is demonstrated that in some cases the optimaL criterion cannot be chosen beforehand.FinaLLy, a simpLe program for HP 9825 A desk top computer enabLing to soLve generaL regression probLems by using an arbitrary regression criterion is described.

ISSN:0228-6203    

DOI:10.1080/02286203.1981.11759716

出版商:Taylor&Francis    

年代:1981

数据来源: Taylor

摘要:

AbstractThe electromagnetic similitude concept where the real and imaginary parts of the propagation factor, times the linear-dimension squared, are held constant in the simulated and actual media to maintain the same geometric distribution of the field, except for different scale factors, is well known. Such a concept has been effectively utilized in the past to determine experimentally, with a model, the long-range electromagnetic propagation characteristics from sources above or below the earth’s surface for various earth-atmosphere discontinuities. An effective simulation model of the earth-ionosphere waveguide can also be built such that it satisfies the classical simulation of earth-atmosphere interface but only matches the reflection-coefficient at the ionosphere. Theoretical requirements for models for the long-range ELF and VLF propagations, and experimental data obtained from the models for the ideal day-time ionosphere and for ionosphere non-homogeneities resulting from abnormal ionization are presented in this paper. Carbon impregnated foams with different dielectric constants and conductivity distributions and salt water with various salt concentrations to simulate the required conductivity distribution have been used to model the ionospheres.

ISSN:0228-6203    

DOI:10.1080/02286203.1981.11759717

出版商:Taylor&Francis    

年代:1981

数据来源: Taylor

摘要:

AbstractA one dimensional mathematical model has been developed to predict pollutant migration in soil-leachate systems. Adsorption and Ion exchange has been modelled using the Lapidus Amundson linear steady state isotherm. The concept of dispersion as a lumped parameter has been used. The effect of biological organisms has been incorporated in a decay term. The equation and boundary conditions have been nondlmensionalised. Three nondimensional groups have been obtained. These groups relate rate of diffusion. rate of convection, rate of biological transformation and rate of chemical adsorption. Parametric studies have been done to determine the influence of these groups on the pollutant attenuation capability of the soil. Variation of concentration profiles with time have been found. Mass of pollutant diffusing and convecting into the soil layers and relative portions that are chemically adsorped and biologically transformed have been found as functions of time.Experiments have been carried out to determine the pollutant attenuation capability of the soil beneath a specific landfill. Migration patterns of eight different cations (Cu, Zn, Mn, Fe, Cr, Ca, Cd, Co) have been predicted using the mathematical model developed.Parametric studies indicate that the soli-leachate system in which a cation is least mobile corresponds to the case where the rate of convection Is more than ten times the rate of diffusion, the rste of biological transformation Is hundred times or more than the rate of convection and the concentration in the sorbed phase is hundred times more than that in the solution phase.

ISSN:0228-6203    

DOI:10.1080/02286203.1981.11759718

出版商:Taylor&Francis    

年代:1981

数据来源: Taylor

摘要:

AbstractThe characteristic features of a simulation program for continous time systems are described. The program is based on an L-stable single step second order method with step size control. To this method a modular form is given. As a result the simulation of large scale modular systems is facilitated, since each module or the interconnections can be programmed and changed without affecting the other parts of the simulation program.

ISSN:0228-6203    

DOI:10.1080/02286203.1981.11759719

出版商:Taylor&Francis    

年代:1981

数据来源: Taylor

摘要:

AbstractParameter optimization in systems described by differential equations is a demanding task, and can be done efficiently only by using high quality software for integration and optimization. This paper discussea the philosophy of implementing parameter optimization in continuous simulation packages, and gives specific examples of the optimizing options of the FORSIM snd MACKSIM programs.

ISSN:0228-6203    

DOI:10.1080/02286203.1981.11759720

出版商:Taylor&Francis    

年代:1981

数据来源: Taylor

摘要:

AbstractThis paper presents an alternative to the Padéapproximation method of time delay simulation. In digital simulation of control or acoustic systems containing time delays, when the delay is not an integral mUltiple of the discretization interval, large computation time or storage is required [5]. The present method approximates the time delay as a finite impulse response filter hk(τ) of order p. The approximation error,ţ, can be controlled by the choice of p and usually p = 4 is sufficient. In some time delay problems [2], it is required that the cross corrslation between a signal and its delayed version peak at the desired delayτ. It is shown that while hk(τ) minimizesţ2the cross-correlation will not peak atτ. To achieve this a table is provided for selection of a parameterτ(τ,p) such that hk(τ) yields a cross correlation peak atτ.

ISSN:0228-6203    

DOI:10.1080/02286203.1981.11759721

出版商:Taylor&Francis    

年代:1981

数据来源: Taylor