Slow feedback and passive control are the major problems in pure planned economy country. In this paper we compare two kinds of economy control forms which exist now: planned control and market control, prove why our country take economy reform as the main work in the Seventh 5-Year Plan and show what function these reforms will have. The method is based on system dynamics. Simulation tell us: the difference between planned economy and market economy consists in their feedback control form, if we can combine the advantage in market control with our system, our economy system will be improved greatly.
This paper demonstrates on approach to army combat modelling using system dynamics. A model is presented of an enemy ground advance which is used to analyse how various adaptive strategies by the attacker and defender during the advance can lead to different outcomes when the combatants meet. Particular attention is paid to the development of performance measures and to the interpretation of results in terms of the underlying feedback structure of the model.
Models of substitution and adoption of consumer durable technologies typically focus on the level of adoption or the level of cumulative sales of the product. Although these variables may be of interest, decisions on market entry and the judgement of future return on investment are linked to the rate of change in adoption level. The percentage change in the current level of adoption, the growth rate, is more relevant, more meaningful and more sensitive a measure of past and future trends than is the level itself. This is an appeal for system modellers and forecasters to focus their attention on growth in studies of technological diffusion.
With the rapid development and wide application of microelectronics, the electronic industry is playing an ever more important role in modern economies. Backed by the socioeconomic circumstances, a system dynamics model (SDEIC) is constructed to investigate the development of electronic industry andto give a description on the future of microelectronics in China in some way. The analyses and simulation results show that there will be a prosperous period for the development of the electronic industry in the coming twenty years with a vigorous investing requirement and at a relative high growth rate. A notable characteristic is that the development is unbalanced with electronic consumption products dominating the market in terms of volume in the period concerned.
This paper tries to use System Dynamics as a tool to analyze some existing problems in China's energy system. The paper first points out some most severe energy problems in China and the policies that people suggest toward the solving of these problems, then reveals the dynamics of these policies through simulations on an Energy Dynamic Model that we built. The analyses cover the issues of energy production and supply system, energy price, energy shortage, and industrial capital retrofit toward energy conservation, etc.. Some conclusions are derived from the analyses which are valuable for the solving of China's energy problems. And System Dynamics is believed to be an effective approach in energy price analysis in China.
From the viewpoint of system dynamics the whole structure and functions of a system do not simply equal the algebraic sum of the parts which the system consists of. There universally exist mutual relationships between the transmition and exchange of information, energy and material within the whole system, its parts and its environment. The aim of this paper is to study the organic ties among the three of the whole, parts and environment of a system and the transmition involved under specific conditions. In this paper, the logical relationships between the internal and external parts of the system are described. Two concepts of the transmition matrix and the relationship matrix are presented along with the definitions of the grades of the grades of variables. Their concepts and definitions, combining the theory of the model reference self-compensation, are used to form a new method by which the functions of the structures and relationship between the whole system and its parts can be identified. Some satisfied results have been obtained from testing this new method on the Boom-town Dynamic Model.
Since L.V. Bertalanffy first brought forward the general system theory, people have been paying more attention to research work from the systems point of view, thus bringing about the development of some system scientific fields such as systems engineering, operations research and management science, etc. Now, in addition to general system theory, there are many new subjects related to studying system 'dynamic behaviors and self-organization such as synergetics, dissipation structure theory, etc.In this article, we study system dynamics from a philosophic viewpoint and try to study important points and methods that can be introduced by systems theory. We search into the relationships between system dynamics and other fields.
For the use of ecosystems with savage fauna it is essential to dispose of -instruments which can let one to simulate the effects that natural circumstances or human actions could have on them. Because ecosystems are extremely complicated and because we are not able to experiment "in real life" -behavior are irreversible- it becomes necessary- "to experiment in the laboratory" the effects of the different events that may affect its future life. This "laboratory tests" can be done with the construction of an ecosystem (a model is a formal representation in scale) that later will have to be implanted on a bearing, and will be the object of simulation exercices. A good procedure of the construction of the model and the simulation is what we calle “System Dynamics” (DS).The non existence of previous proofs in the use of ecosystem with savage fauna leads conscious of unconsciously to the disappearance of going down of the species in specific ecosystems. The examples of Kaibab's land, the “Urogallo cantábrico" or of the grouse -are paradigmatic. The purpose of this work is to introduce concisely the model and the conclusions obtained from its use, for the study of the evolution of the rabbit population in a plot of 10 hectares in South Spain. The rabbit (Oryctolagus cuniculus, L.) has been chosen for its enormous value as a prey for upper birds of prey (Imperial eagle, Royal kite, Black kite, Linx and Fox, etc. etc.)
In this article we want to predict the dynamic behaviour of a portfolio of assets, i.e., we want to know how quickly it will move towards anew position of equilibrium when an unstable situation has ocurred due to important changes in the risk, (and in some cases in the return) of the securities. In order to carry out this forecast, first we should locate the points of equilibrium, then analyse their stability and lastly determine where, and under what conditions, the discontinuities appear.Changes in the return or in the risk of the securities which make up a portfolio can be smooth and this also brings about a smooth change in the portfolio, which is shown in a readjustment in its composition. However, it sometimes happens that, while the expectation of return remains relatively stable, circumstances arise which considerably increase the risk, in which case a serious discontinuity occurrs in the feature of the portfolio.In this way, we can apply the methodology of Thom's Theory of Catastrophes in order to obtain valid conclusions using the morphology of the butterfly catastrophe for the portfolio's feature (efficient, non-efficient and opportunity or pseudo-efficient), employing four control factors: return, variance, transaction costs and risk aversion.
This paper introduces a new implementation of the System Dynamics simulation Language DYSMAP, a current project at Salford University. A short overview of the history, syntax and features of DYSMAP will be given. The new DYSMAP2 system operates as an interpreter. The relative merits of computer interpretation vs. compilation into FORTRAN will be discussed. An outline of the operation of this new portable package (written in FORTRAN77) will include high level descriptions of the parser, run-time interpreter, the interactive environment, dimensional analyser and the optimiser. The performance of the new DYSMAP2 package will be illustrated.