This paper constructs a system dynamics model on macroscopic management of a college which is based on an actual system operation of the college. The students, staff, fixed capital, finance, teaching and research as sectors are included in the model. Facing several important problems influencing development of the college various policy experiments are operated on the model. The experimental results show that the key factors influencing the system and what the possible approaches solving these problems are.
The rapid growth caused very serious environmental pollutions in Taiwan. This paper attempts to use the system dynamics methodology to construct a simple model to study the trade-offs between economic growth and environmental pollutions. The model is structured with feedback loops among three sectors; The government, the general public, and the industries. Environmental regulations with various implementation times and strengths are tested in the model to examine their effects on the smoothness of the economy and pollution changing pattern. The results show that a timely not-so-strict environmental regulation combined with an environmental education measure focused on lowering expectation on economic rate may be a better choice for Taiwan to go through the tough time more smoothly.
Inflation is one of the most troublesome problems China is recently faced with in the course of the economy reform. The inflation takes place in the form of general price rising. It becomes more serious and is greatly obstructing the healthy development of China’s economy. This situation results from many factors including the biased trend of the reform strategy, the deviations in implementation policies, the defects of the economic system, etc. The conventional theory about money amount has been used to analyze inflation before. This analytic method specially indicates the view point that inflation with no exception is a kind of money phenomenon by stressing the causal relationships between money amount and general price level, but it considers money supply as an exogenous variable controlled by the government’s policies and ignores the effect and restrictions from other economic factors. Therefore there are some limitations of this method in real uses. For this reason a new approach of system dynamic is put forward in the present paper. A dynamic model composed of a monetary market section, a commodity market section and a regulation section is developed. On the model a series of policy tests mainly concerning the two economy levers of price and interest rate are simulated with the consideration of china’s special situation. The cause and mechanism of suggestions are also made for elimination or controlling the inflation. The results of the paper may provide worthful references for China’s further economy reform.
In recent years, increased public awareness of the health and productivity costs associated with the use of cocaine and its potent derivative “crack” has served to heighten concern and renew debate over the most effective strategies for managing the drug problem. This paper presents a preliminary system dynamics model of the international cocaine trade. The initial model incorporates the various stages of the cocaine system from source country production to final consumption including: primary resource allocation and production; cocaine production; cocaine production and export; and U.S. demand, import, pricing, and consumption. The model is used to examine an ensemble of policies proposed by the National Strategy for Drug Control (White House 1989). Simulation results show the capacity of the system to exhibit a wide array of behavior modes depending on the type of intervention being applied and the aspect of the problem being targeted. Of particular interest from a policy standpoint is the implication of delays in physical and information flows for generating divergent short and long term policy results. Findings suggest a comprehensive approach combining demand and supply side policy leverage represents the most effective management strategy.
A System Dynamics model of an ecological system consisting of two patchily distributed populations is constructed to study the effects of inter-patch colonization on the persistence of the species. The model structure is primarily composed of the negative feedback loops dominant in local (within-patch) population regulation and a regional positive feedback loop coupled with two negative loops which regulate the inter-patch species colonization.The simulation results show that with colonization the population system always persists if at least one of the populations is larger that a minimum viable population size (MVP). If the species has sufficiently large colonizing ability, the populations are always able to reach the carrying capacity. Otherwise, the population with below MVP, there are two possibilities depending on the magnitude of species colonization ability: (1) both stabilize at the carrying capacity level and (2) both go extinct. The simulations also demonstrate that delays in colonization and population regulation may have distinctive impacts on species persistence and dynamics of the population system. The study may provide useful information for species conservation and design of nature reserves.
The last decade has been the accelerated development of what Yadav and Chand term “Organization Support Systems”- large scale, complex and extremely expensive computer based information systems (Yadav, 1989). The cost associated with such systems has increased the requirement for a sound methodology to evaluate the expected operational benefits and drawbacks resulting from their implementation, at as early a stage in the system life cycle as possible.An extensive survey of the literature in the field of information system evaluation, with a particular focus in the methodologies, tools and performance measures being used in practice, preceded the development of the methodology reported in this paper, and is presented in full elsewhere(Watts 1990).This paper comments on the findings from the review and reports on the development of a system dynamics based methodology for the assessment of proposed computer-based information systems (CIS), in terms of their potential to support organizational objectives.The methodology has been evaluated by application to two military CIS, at different stages in the system life cycle. These cases are reported separately(Watts and Wolstenholme, 1990; Henderson and Wolstenholme, 1990), but the indications are that the methodology can contribute throughout the system life cycle y providing a continuing reminder of the relevance of the CIS to the real-world system which is intended to support.
The appearance of Thomas Kuhn’s Structure of Scientific Revolutions engendered considerable discussion about the nature of scientific change. Kuhn challenges the prevailing view of science as a continuous, logical enterprise by attempting to debunk science’s myth of rationalism. As an historian as well as philosopher of science, he attempts to explain science’s extraordinary success not by developing methodological cannons divorced form scientific practice, but by looking at how scientists actually work.( Lakatos and Musgrave 1970, 236-237).Acknowledging the philosophical importance of actual scientific practice is controversial. Kuhn’s critics question both his characterization of science as mostly “puzzle –solving”, as well as his claim that such practice is necessary for scientific development. It will not be the task of this essay to rehearse these still unresolved debates. That is better left to the historians and philosophers. Rather, I would like to recognize another important contribution to the discussion, one that is orthogonal to any other that I know of. In “The Growth of Knowledge: Testing a Theory of Scientific Revolutions with a Formal Model,” John Sterman has built a model of Kuhn’s account of scientific change. He asks not whether Kuhn’s theory is dynamically consistent. He is interested in whether the behavior Kuhn describes (i.e. , paradigm emergence, normal science, crisis and revolution) actually follows logically from the assumptions Kuhn makes. To do so he constructs a system Dynamics computer model.
This paper examines the role that building and using a System Dynamics model plays in developing consensus within the management teams facing key strategic decisions. It considers the concept of the shared view that emerges within the team as their individual views of the company, its industry, and the socioeconomic climate are articulated and compared as part of the model development process. Examples are given based on two actual consulting assignments in which differing views held with the team concerning the competitive environment and the general outlook for the business initially pointed to quite different strategies. During these studies the emergence of the consensus and an agreed strategy was considered a major benefit alongside the forecasts and quantitative evaluations the model provided. By adding to the commitment of the team, by assisting in the communication with others and in improving human resource management and organization design, the approach also offers further benefits in the implementation phase of strategy management.In its analysis and use of examples drawn form consulting situations, this paper has emphasized the dual benefit of this approach in the hard sense of providing forecasts and an objective framework for quantitative evaluations, and the soft sense in terms of building consensus in the management team.
Since the mid 1970s, System Dynamics has contributed to the resolution of a wide range of business and legal disputes including contract claims and re-negotiations, management prudency hearings for nuclear power programs, and inquiries into the effects of government regulations on various industries. In these settings, a System Dynamics model can provide an objective, “transparent” view if a complex and emotional situation. The model can represent what happened and why, and what would have happened if certain events or conditions had not occurred. It can provide a basis for determining responsibility for delays, cost escalation, poor product performance, reliability and safety problems, complex situations are easier to understand and evaluate. The models and analyses become frameworks for debate and settlement.This paper describes the context, processes, and behaviors associated with many business-related legal disputes. The role of System Dynamics is dispute resolution is discussed in general terms, and then illustrated with a recent example. The example is a large contract claim for “delay and disruption.” That term refers to the indirect, secondary, or ripple effects of events or conditions (e.g., design changes) impacting an aerospace, shipbuilding, software development, or similar program. Delay and disruption impacts can be very substantial. They are the most difficult aspect of a change negotiation or claim to handle, and are the source of the most acrimony and disagreement in such disputes. The background of this case, the lawsuit, how the model was introduced into the legal proceedings, and how it helped to achieve a settlement, are described in detail. The paper concludes with a discussion of the practical results obtained from using System Dynamics in dispute resolution.
This article presenting a summary and analysis of the theory and method of System Dynamics on the author’s experience in planning of the coordinated development of science, technology, economy and social advancement in such cities as Beijing, llarbin, Anshan and Baotou, is aimed to find out the advantage disadvantage of the S.D approach to urban planning as well as to improve upon it.System Dynamics which is considered in this article to draw on system theory, information science and cybernetics, especially the feedback control principle and computer simulation, is a scientific theory and method that can find an effective application to improving and planning a multi-factor, non-linear, dynamic and/or strategy. In actual planning of coordinated development of the Chinese policy or strategy. In actual planning of coordinated development of the Chinese cities and regions, S.D is found superior in six (6) points while left five (5) respects to be desired, so the idea of establishing the S.D. dominated comprehensive model system is this developed to enhance and strengthen the above planning process.
This paper describes the application of a system dynamics based three-stage methodology (Wolstenholme, 1990) for the assessment of computerized information (CIS), to a proposed military logistics information system.The system in question was nearing the end of the Requirements Definition phase of the System Life Cycle process. A Benefit Assessment had been carried out by the consultants responsible for the design of the system. The Tools used by them had, however, encouraged the conclusion that any improvement in the information system must have a positive effect on organizational effectiveness directly proportional to that level of improvement, and that the overall level of improvement is the sum of individual gains. No study of the interaction of the physical operation and the information system had been carried out.
A system dynamics model of socio-economic development of Harbin in China has been Presented in the framework of the integrated economy-energy-environment system planning.The model simulates the activity mechanism of national economy of Harbin by taking the fixed capital of each industrial sectors as a major variable and controls the system behavior by taking the gap of energy supply and the gap of energy investment as feedback signals. Therefore the pre-established development targets of national economy can be reached by readjusting the investment allocation and production structure towards elimination of the energy and investment gaps.Through a series of policy stimulation, several socio-economic development planning scenarios of Harbin for year 2000 have been Compared with each other by examining some key issues, such as growth rate, investment ratio, investment allocation tenancy and production structure readjustment ad well as the improvement of scientific, technical and managemental level, etc. the resulted policy suggestions were proposed with much attention being paid by decision maker authority.This model can run on the personal computer under the support of the Professional DYNAMO Plus software, and try to connect SD model to other technical model, such as energy forecasting model, multi-object optimum energy supple model, etc. An idea which is about SD co-operated with other methods has been presented and that is the direction of the system dynamics method development.
Nonlinearity is the source of complexity. It gives rise to the change of the system behaviors, the evolution of structures and such phenomena as bifurcation, catastrophe, and even chaos. It is these phenomena, dovetailed with others, that weave out our multicolor and multifold world synergentically. With the development of science and technology, people become more and more interested in and capable of the study of nonlinearity so as to shed light on the nature of the world. In order to deal with nonlinearity more systematically, this paper elaborates a comprehensive description for the dynamical system. Then, we focus on the relationships between the characters of nonlinearity. We have successfully expounded some controversial concepts, cast new light on some important relations, and unified several concepts which are the central topics of many modern theories.
By means of system dynamics, main development modes and strategies on entire coordinated development of science, technology, economy and society of China have been studied. The paper studies the existed development mode and the long term possible obstacles, unfavorable factors and some constraints to the development in its different stages are analyzed quantitatively in the paper. Some long term and short term strategies and policies for continuous and entire coordinated development are presented, based on the system simulation and quasi-optimization.
This paper study how to develop education, technology and economy coordinativetly in central cities. It outlines the kind of issues which analyze and study the ways of describing science and technology level. The importance of the paper has two points: out is an new method being applied to calculate industry output, another is the study guiding line to the three sectors(science and technology, education and economy) in their entirety. The policy suggestions will have significant reference to make central cities’ long term development strategies.
This paper is focusing on study of influence of China’s recent economic adjustments and industrial structure changes on enterprises, particularly on these engaging in manufacturing. The paper analyzes major difficulties facing Shanghai, the largest industrial centre of China, and, using it as background, studies the decision-making strategy of a typical enterprise of Shanghai.
A simulation model of education and economy is used to analyze the education investment strategy in a region of China. The simulation results show the proportion of educational fees and investments must be suited to the economic developing level. Thus, it is necessary to continuously increase the proportions with economic growth. In order to be convenient for decision makers, a functional simulation support system is proposed.
In the paper, a system dynamics model of the Dutch health care system will be discussed. The description of the model will start with so called ‘patients flows’. It will be followed by a description of the most important factors that affect the patient’s flows and the costs generated by the system. Having outlined the system dynamics model, the outcomes of three policy alternatives aimed at reducing the costs of health care will be examined. They will serve to demonstrate that the system dynamic model does have the potential to be used in workshops to elicit and increase the knowledge policy makers have regarding the problem of rising costs of health care.
Many system dynamics modelers consider the process of model-building more important than the model itself. Model-building is supposed to generate considerable learning about a policy problem. Not only at the individual level but also at the organizational level. From the point of view of empirical evaluation research the question is how the occurrence of organizational learning as a consequence of a model-building process might be established. In this paper we will explore some of the key issues and difficulties involved in establishing organizational learning from model-building empirically.
A key issue in building computer models for decision support with client groups is the elicitation of knowledge from the mental models of participants. The system dynamics model-building process is quite complex and consists of several stages each demanding different types of knowledge to be elicited from the client group. In this paper we discuss a structured approach, employing various techniques, for the elicitation of knowledge in formulating and analyzing a system dynamics model of the Dutch Health Care System.
System modeling and simulation is a complex technological activity, which methodological and conceptual analysis could suggest some new and interesting perspectives about the philosophical subject of the relationships between knowledge and reality.Of the three kinds of knowledge involved in the system dynamics model building process (mental models, reference modes and operational knowledge), mental models look like specially important, because they let us to express the ideas we have about the internal interactions we find in a real system and that produce a known behavior. From this mental model, we build the formal model, the system dynamics model.But, after that, it is very difficult to find out formal restrictions that let us to select a single model, because a behavior can be generated by different structures ( Searle 1980,1984; Zeigler 1976,1984). The internal realism of Hilary Putnam (Putnam 1981,1983,1987) allows us to understand why there is not an unique model able to pick up every single aspect of a real system and to clarify the interactive character of the modeling process and the important role that mental models, as a kind of knowledge, play.
In this paper we present a program package which combines System Dynamics Simulation with programs for Interactive Multicriteria Optimization (IMO)The program package incorporates conventional well tested routines for nonlinear optimization, that do not require previous computations of derivatives, and methods to optimize a set of objective functions by progressive articulation of the user preferences between different criteria.To facilitate the user interaction, a special purpose man-machine interface have been included in the package. By means of this interface, the user can impose the required preferences structure by only expressing, in a linguistic way, his/her opinion about each objective in the current solution of the Interactive Multicriteria Optimization algorithm.The program package can be used to optimize a set of objective functions both in problems concerning the estimation of model parameters from historical data, and problems related with the search of optimal policies.The man-machine interface and optimization programs have been written in C and linked with the DYNAMO continuous systems simulation language to configurate the program package. The package can be used in IBM PC (or compatible) with a hard disk.
This report is based on results of the TERC Modeling Project funded by the National Science Foundation grant MDR-8550373. Any options, findings, or recommendations expressed herein are those of the authors and do not necessarily reflect the views of the Foundation.We gratefully acknowledge the support of Apple Computer, Inc.Apple, Macintosh are trademarks of Apple Computer, Inc.Stella is a trademark of High Performance Systems, Inc.Excel is a trademark of Microsoft, Inc.
We have investigated the complex dynamic phenomena, which arise when the economic long wave model is perturbed by a sinusoidal variation in the orders for capital to the goods sector. The modulation represents a coupling to more short term oscillatory modes in the macroeconomic system. As the period of the external forcing is changed, a devil’s staircase of frequency -locked oscillations develops. For higher amplitudes of the perturbing signal, period-doubling bifurcations, simultaneously existing periodic solutions and deterministic chaos can be observed. The distribution of modes is determined as a function of the frequency and amplitude of the external signal. The phase diagram reveals characteristic bumps on the Arnol’d tongues, where they approach each other. The Lyapunov exponents are calculated, and the influence of noise is discussed in terms of the lock-in time for the periodic solutions.
Over the past thirty years the black rhinoceros (Diceris bicornis) population in Africa has declined from about 30,000 to less than 3,000. In contrast the South African population has increased four-fold to 600 over the same period. The recently developed national conservation strategy for black rhino has as it main goal the increase of the current population to at least 2,000 in as short a period as possible. To achieve this, the growth rate of the population as a whole will have to be maximized. This involves removing animals from areas where the population is approaching the ecological carrying capacity and establishing new viable populations in other suitable reserves.A model, incorporating what is known about the population biology of black rhino, was developed to give guidance to managers on the most appropriate harvesting strategy to adopt for their populations; in particular, to determine the rate of removals and the age and sex of individuals to be removed to attain a 2,000 strong Southern African population as soon as possible.
This paper attempts to highlight how system dynamics methodology is useful in modeling and testing the dynamics involved in group interaction process to explain its behavior over time. Out of the prominent group models, Gladstein’s model of groups in context is taken as reference model. The SD model of group structure which is a system component consists of six modules; roles, goal clarity, specific work norms, task control, size and formal leadership. This paper deals in detail, the module of formal leadership, and studies how the interrelations and interdependence influence the system behavior.
This paper describes a System Dynamic approach to the study of the relationship between people participation in Agricultural Land Reform Cooperative performance and the economic performance over time. Two Cooperatives are examined- “successful” and “non-successful” -and policy changes are discussed in terms of the performance of these two Cooperatives.
This paper reports on the annual summer training program of children’s creative development conducted since 1986. The training targets per program are between 80-100 children aged between 9-14 years coming from various urban and rural parts of Thailand to join the 8-10 day program for moral and technical development. The program is planned and coordinated by the author with considerable inputs from Buddha’s teaching in self-reliance: the potential of human being prevent their defilement; and from people who expertise in architecture and technology. The method approached for explaining human performance in nature, is a simulation game designed by the author with the help of her colleague in computers. The model concept is derived from a system dynamics method as a tool for dissemination of the law of cause-effect action in Buddhism. The children evaluated joyfully and rapidly understand the mechanism of mind in decision making whether to conduct good or bad actions according to the Buddha’s principle by playing and thinking themselves with this simulation game in a better way than they do in the traditional method of lectures by monks or teachers. The game simulates the interaction relationship between a human’s performance and his life expectancy. Later the workshop practice of the electronic application is approached for systematic problem-solving about peoples’ needs in terms of technological development in relation to promotion of moral values.
In this paper, first of all, a qualitative analysis is done on a general infections disease SD model, and a new epidemic threshold value and an epidemic scale forecasting formula are proposed. Then in consideration of the properties of type-A hepatitis and its eruptive spread SD model is put forward. A lot of work in various aspects is done, for example: the problem to simulate the type-A hepatitis incubation period is solved practically; the simulation results fitted in with the reality are achieved; through simulation analysis and qualitative analysis, the reason for that the predicted 2nd peak of this spread didn’t appear is found out; the short-term and long-term prospects of Shanghai type-A hepatitis situation are brought forward; especially, hypotheses about the mechanisms of the periodic epidemic and the eruptive spread of type-A hepatitis are put forward. These results are imbued with guiding significance for prevention and control of the type-A hepatitis and other infectious diseases.
An integrated system dynamics policy model was developed for a state level economic activity, population, energy demand, supply, and price with realistic feedback mechanisms. Environmental impacts and influences on technical and economic efficiency were also modeled. The model and its use to perform a joint analysis of several interacting policies, including electric and gas utility least cost planning and the construction of an interstate natural gas pipeline are described. A number of interesting results from a variety of perspectives are presented. These include an evaluation of the economic development; air quality and energy efficiency impacts of the pipeline proposal; their sensitivity to fuel prices; and some novel observed feedback relationships between energy price and air quality. The lessons learned in model development, implementation and utilization in both policy and regulatory arenas are discussed. The benefits of fully integrating economic and environmental impacts for policy modeling are evaluated.
Advances in computer software allow modelers to design, with relative ease, sophisticated, realistic educational tools. With these advances, new issues arise about how to make this educational software productive and stimulating, without limiting the freedom of the user or creating simply a computerized workbook.Such simulation games have great educational potential for people who play video and home computer games, and sometimes for students in classrooms. The games must address three information levels: (1) real-world details, (2) simulation of model, and (3) conceptual understanding of structure and dynamics. The systems viewpoint on the particular model must be clearly explained; otherwise users will have much fun but learn little. Feedback during the game teaches this system understanding without requiring textbook readings. Such feedback requires new modes of “expert” computer analysis which need to be developed. Other tools need to be developed to help in creation of simulation games and to give the games abilities that they do not yet have, such as access to database of models, pictures, and text, and connections between simulation games.
Japanese old age population is gradually increasing and this tendency weakens economic conditions of Japanese welfare annuity system. Therefore it is important for us to study future conditions of this system.This model contains 4 sectors: Demography, total premium income, total pension expenditure and reserve of the welfare annuity system.The demographic sector covers populations of 5 three-year age groups under 14 years of age and 13 five-year age groups above 15 years of age. This sector was first formulated for a simulation model of dental diseases and is now applied to this model. Total premium income for the welfare annuity system is the sum of premiums of workers, employer contribution and government contribution, for which populations of five-year age groups are used. Total pension expenditure is the sum of base pensions and earning related pensions. Here is used population of 60-64 age group. Total premiums plus interest income of the reserves of the welfare annuity system minus total pension expenditures flow into the reserves of the welfare annuity system.The length of the simulation is 63 years from 1963 to 2025.This study is a research project of the Japan Productivity Center.
The paper suggests a novel approach to policy design in system dynamics models. The approach is based on optimal control theory to evolve synthetic policy structures and then design realistic policies for the famous production - distribution model of Forrester. New policy sets have been presented for purchase decision rate at retail and distributor sectors and manufacturing decision rate at factory. It is shown that the suggested policy sets show a marked improvement of model behavior over that obtained by Forrester. The approach suggested here will enhance the art of policy design.
Eroding competitiveness, declining productivity growth, explosive technological, political and environmental change, and dissolution of market and national boundaries form the familiar litany of problems which threaten traditional organizational structures and management practices. In the turbulence at the close of the century it is widely argued that organizations must change more rapidly than ever before.
The automobile fuel market in Italy is appreciably different from that in other European countries and even more unlike the American context.As a matter of fact, the alternative and available automobile fuels in this country are the following: -gasoline (petrol),-gas oil (diesel oil),-liquefied gas (LPG), plus a very small amount of natural gas, each with its own price. In addition, price differences are considerably greater than in other countries.In view of the fact that gasoline is the most expensive fuel and gas oil the least expensive, the Italian Government has adopted a peculiar tax called “Superbollo” meant to penalize car owners with diesel powered engines and those with both gasoline and LPG powered engines, but to a different degree.The alternatives access by drivers (car-users) to different fuel resources has influenced and countries to influence the automobile industry’s approach to the Italian market.On the other hand, the different fuel prices, plus the varying annual amount of the ‘Superbollo” tax, influences the motorist’s decision in buying and using differently powered cars.The decision is obviously affected by the consumption rate for each type of fuel and the driver’s expected mileage per year.This paper aims to underline and analyze the hypothesis on the mix of the three main fuels used in Italy, trying to give results principally on the basis of: -price-changing of each fuel, -tax-value of “Supperbollo”, -different driver-mileage taking into account the pollution-cost of each of the three fuel solutions. The system, which is the subject of the study, will be analyzed using System Dynamics methodology, with a dynamic model.
The close similarity between the Indian census, Government of India and U.N. population estimates and those from the Constrained Coalition and Logistic Model (CCLM) has been demonstrated which enhances the usage of differential equation modeling for studies on population growth processes. The CCLM incorporates the legitimate requirement of an upper bound for the aggregate population thereby implying the rate of natural increase to reach the zero level. The numerical value assumed for the upper bound is based on food supply - arable land availability, and accounts for advances in agriculture productivity. However, other factors such as quality of life, environmental degradation, per capita income, etc. can also be used to arrive at an upper bound. The model holds good promise for usage for other developing countries.
The use of computer tools to aid in decision-making and problem-solving activities suggests a view of negotiation in which parties collaborate to improve the quality of the information and knowledge on which they base their joint decisions. In this view, negotiation is characterized as a process of discovery and design. The effectiveness of negotiation is defined in three dimensions: legitimacy, feasibility, and efficiency. Computer tools are discussed in the context of information strategies, or ways in which negotiators use information in their efforts to ‘discover and design’ solutions.
This paper presents results of extended experimentation with selected models of social phenomena widely used by the system dynamicists in their studies on deterministic chaos. The models selected include various versions of a simple model of migratory dynamics and a model of resource allocation in a firm, and a simple model of long-term economic fluctuations. Chaotic modes seem to appear in each of the experimented model, either due to non-robust or unrealistic rate formulation, or from unrealistic parameter or input specifications or both. Minor changes on the models experimented with, which improve their correspondence to reality, eliminate chaotic modes. The paper raises the issue of the relevance of the chaotic models to real-world phenomena and policy design for system improvement.
This paper suggests that the possibility to experiment with relationships using system dynamics should lend the method easily to introducing practicum in the theory-based disciplines. This would however, require modifying teaching formats and creating new text materials and user-friendly computer programs suitable for use by students with little computer or mathematical expertise. A simulation laboratory consisting of a text and a user-friendly simulation program developed recently by the author on issues of economic development is presented as an example of material needed for integrating practicum with teaching.
The paper considers how students learn commodity production and circulation via gaming experiments. We review two of them.In the first, players run into reproduction on a decreasing scale aggravated if not caused by their non-cooperative behavior. In this economy social and private benefits and costs diverge. Undertaking an investment a capitalist firm chooses typically that technique which maximizes profitability, while the society is interested in that which requires the minimum input of labor.In the second, players bring up extended reproduction receiving incompatible norms and setting new priorities with associated strategies of cooperative behavior. Social and individual interests draw together consequently.
The problems we are facing at all levels in the world today are growing more intractable. In particular, our problems are becoming increasingly resistant to unilateral solutions. I will argue that this growing resistance and intractability result from the fact that while the evolving web of interdependencies, of which we all are part, is rapidly tightening, the development of our capacity for thinking in terms of dynamic interdependency has not kept pace. As the gap between the nature of our problems, and our ability to grok this nature grows, the planet will face increasing peril on a multitude of fronts. System Dynamics and System Thinking -- the larger framework of which it is a subset -- are an important part of an effective strategy for closing the gap between challenge and capacity for addressing challenge. Unfortunately, we as System Dynamacists and Systems Thinkers have been woefully inadequate in transferring our framework, skills and technology to the population at large. Although we have “seen the light” for some thirty years now, we have not opened the door to our inner sanctum wide enough to let others share in our insight- generation capabilities with respect to the inner workings of closed-loop systems. In order to be more effective in transferring our very valuable capabilities to a broader swath of humanity, we need to see more clearly precisely what these capabilities really are, and also to understand the forces driving the evolution of the education system into which these capabilities -- if they are to be transferred on a board scale -- must be assimilated. My purpose in writing this paper is to shed some (hopefully new) light on both what it is we have to bestow, and also on where the educational system that is to receive our bounty is headed. My intended audience therefore is both Systems Thinkers and educators. My highest hope for the paper is that it will serve to further eradicate the distinction between the two.
Successful welfare reform is difficult to achieve in practice and to study in theory because the linkages between policy reforms and the actions of clients of the system are many, long, and loose. Reformers can change organizational structure, funding amounts and requirements, as well as mandates. They hope that these reforms will change the behavior of workers who will implement the reforms. In turn, changed behavior of employees and welfare agencies are presumed to change the behavior of clients. Evaluating welfare reforms requires that information about policy changes, organizational changes, changed behavior by workers, and ultimately changed client behavior all be examined empirically and the results combined into a coherent whole.This paper proposes that system dynamics models may be a new tool in the analyst’s toolchest that can help to create integrated theories of welfare reform as well as help to integrate results from empirical studies of welfare reform. Below we present a first cut system dynamics model of the implementation of portions of the welfare reform legislation of 1988. This effort is designed to illustrate how system changes, changes in worker behavior, and client behavioral choices might be simultaneously analyzed within the context of a singe feedback system. Of course, the hard work of elaborating and empirically validating the structure of this simple model still remains before us.
In previous papers, various approaches to studying the relationships between an aggregate dynamic model and an underlying, stochastic system have been reported. These approaches include the use of a Master Equation model to derive the aggregate model from stochastic hypotheses, and the summation over a population of dynamic sub-models to estimate the aggregate behavior. In this paper, a commodity cycle model is re-formulated as a stochastic, discrete simulation model to study the effects of stochasticity on the aggregate behavior of the system. Global variables provide aggregate information links to control the arrival and departure of new entities (commodity units and capacity units). A comparison of the aggregate dynamics of the stochastic and the equivalent system dynamics models is made under conditions in which the dynamic models is made under conditions in which the dynamic model is oscillatory and undergoing period-doubling bifurcations leading to chaos.
PASION is a process- and event-oriented simulation language designed for those who already know and use PASCAL. The language has a two level (process/event) structure and permits the use of all the Pascal Structures. It also offers the main features of object-oriented programming. PASION provides necessary facilities to handle sequences of random events, queues and quasi-parallel processes, both discrete and continuous. A PASION source program consists of a sequence of process declarations and a main segment which initializes the simulation. At run time the program generates objects which represent model processes due to the process declarations. PASION provides tools which facilitate the building of complex models by the mechanism of inheritance.
Building large dynamic simulation model of an industry requires sound organizing principles and appropriate tools combined with a thorough understanding of the industry being modeled. In this paper I will describe how we build a simulation model for a client’s business to answer the client’s key strategic questions.The models are large because they are based on physical, observable phenomena in the industry. They must take into account the stocks and flows of product and money as well as represent managers’ decision-making processes and the key variables that impact each producer’s decisions. Most corporate decisions are based on physical or financial parameters, so the model structure is clearly understandable to the final user.At Federal Group we use an effective methodology for building large-scale structural dynamic simulation models to address the real world problems of business decision makers. This paper presents how we have successfully constructed such models for oligopolistic, capital-intensive industries. However, our methodology can be generalized to a broad range of other business environments.
Behavioral simulation models of OPEC have typically been built on the assumption that OPEC price changes are determined by capacity utilization. We evaluate this model by examining its empirical and behavioral justifications, and by observing how it performs in a simple world oil market model. We also briefly explore and evaluate alternative behavioral rules for OPEC.
The paper presents some results of research regarding the relationship between the centralization degree and the efficiency of economic systems. A simple system dynamics model has been used in these studies. The model has applied certain J.Kornai’s ideas concerning economic systems. Simulation experiments have confirmed the viewpoint that overall economic behavior arises from within feedback loops creating microstructure of each system. Two basic kinds of microstructure have been distinguished: centralized and decentralized. Macro behavior generated by them is close to these observed in planned and market economies. The paper is divided into four parts. In the first one, basic Kornai’s ideas are outlined. In the second part, model is presented, whereas in the third one, some results of simulation are analyzed. Conclusions drawn from the experiments are presented in the fourth part.
In this study, a decision support system for system dynamics modeling is designed. The intelligent part of the system is composed of a knowledge base, a data base and an inference engine. The function part of the system is composed of some modules for model construction, model generation, model simulation, model interpretation, model management, and PD interface. The proposed system is a production system written in PROLOG, and it can join up with the professional Dynamo plus software by means of the PD interface. Whole process from modeling to simulation can be realized by the support of the system. An application example is given in this paper.
Negotiating group can use generic computer tools to aid decision-making and problem solving activities in negotiation management. In attempting to create, apply, and evaluate such computer tools, the authors have had to address the issue of user acceptance. This paper reviews the basic framework of negotiation management and locates the issue of user acceptance within that framework. Focusing on system dynamic simulation models as tools for negotiators, the paper analyzes the reactions of potential and prospective users.
The issue of global warming has sparked debate among scientists and policy makers over the last two years. Many studies have been undertaken in the U.S. and other nations to determine the potential severity of global climate change and appropriate policy responses.The U.S. Department of Energy is now conducting one such study of energy technology and policy options to mitigate greenhouse gas emissions. The study is an attempt to assess the emissions reductions potential and costs of several policies, using the FOSSIL2 integrated energy model. This paper focuses on preliminary results of a subset of eight policy cases. It discusses the modeling methodology, the formulation of these policies, draft results and some policy insights gained.