bluuebunny/crossref_metadata_2025_split huggingface dataset:
Bifurcations and chaotic behavior in a simple model of the economic long wave
Authors: Rasmussen Steen , Mosekilde Erik , Sterman John D. 
Published: July 2007

AbstractThis paper presents a formal stability analysis of a simplified Kondratieff wave model. For normal parameter values the model has a single unstable equilibrium point which, combined with nonlinear constraints in the model's table functions, creates a characteristic limit cycle behavior. For other parameter values, the model generates damped oscillations instead of the limit cycle or overwhelms the nonlinear constraints and exhibits sustained exponential growth or total collapse.By linear stability analysis we first determine the conditions for a Hopf bifurcation, the transition from a stable to an unstable equilibrium. Using global analysis, we outline the phase portrait of a fully developed limit cycle. By the same method we examine the conditions under which the nonlinear functions fail to contain the system so that exponential runaway or collapse occurs. We then develop a DYNAMO program to calculate the Lyapunov exponents of the system during a simulation and discuss how these can be measures of the divergence or convergence of nearby trajectories. Finally, we illustrate how subsequent period doublings and chotic behavior can occur if the model is driven exogennously by a weak sine wave, representing, for instance, the shorterm business cycle.
Aggregation in system dynamics
Authors: Rahn R. Joel 
Published: July 2007

AbstractStochastic aspects of systems have generally been ignored in most system dynamics studies except for purposes of sensitivity testing. Yet any model that claims to be more than simply a phenomenological description of a system must treat the underlying stochasticity explicitly in terms of its contribution to the dynamics. Recent work in chemical, biological, and hydrodynamic systems has shown that the aggregation of stochastic effects can lead to novel behavior (self‐organization in dissipative systems).In this paper, an analogy between models of these physical systems and system dynamics models is developed, in which dynamic models are seen to be an approximation (to lowest order in an expansion in system size) to a stochastic model for the system. The theoretical results derived for the physical system models are evaluated for their application to system dynamics models. A research strategy to elaborate this approach to analyzing a more general class of systems is proposed.
Algorithmic control modules for system dynamics models
Authors: Wolstenholme E. F. 
Published: July 2007

AbstractThis paper describes a framework for policy analysis and design in soft, complex systems based on the transfer to such systems of control modules developed for harder (more easily quantified), simpler systems. The framework is demonstrated by outlining the development of a dynamic allocation algorithm within a system dynamics model of an engineering system and describing its application in a much larger scale management system. The potential use of this algorithm is demonstrated in two other systems, and a generalized form is presented that highlights its isomorphic qualities. It is suggested that this framework, which treats the physical and control structure of a system as a unified whole, can provide a useful contribution to policy analysis.
The dynamics of a fledgling high‐technology growth market: Understanding and managing growth cycles
Authors: Morecroft John D. W. 
Published: July 2007

AbstractThis paper presents a system dynamics model of the fledgling market for automated storage and retrieval AS/RS systems based on a case study of a leading firm in the industry. The model examines how marketing effort, capacity expansion, and industry reputation interact to produce growth cycles of eight to nine years' duration in demand and capacity for AS/RS systems. A series of partial model simulations is used to explain how the growth cycles are generated by the feedback structure and behavioral assumptions of the model. A policy experiment is presented to show how a mature firm in the industry can influence the growth cycles to improve its financial performance. Finally, the feedback structure governing market diffusion and capacity expansion is generalized to other high‐technology products and markets.
The economic long wave: Theory and evidence
Authors: Sterman John D. 
Published: July 2007

AbstractThe economic crisis of the 1980s has revived interest in the economic long wave or Kondratiev cycle. Since 1975 the System Dynamics National Model has been the vehicle for the development of a dynamic, endogenous, integrated theory of the economic long wave. This paper describes the integrated theory that has now emerged from extensive analysis of the full National Model and from simple models. Simulations of the model are presented to show the wide range of empirical evidence accounted for by the model, including many of the symptoms of the present economic crisis. In particular, the theory suggests that the long wave arises from the interaction of two fundamental facets of modern industrial economies. First, firms contain inherently oscillatory structures. Second, self‐reinforcing processes amplify the instability. The relative strengths of these mechanisms and the amplification of the long wave through their interactions are discussed, as are the linkages of the longwave theory of innovation, technological progress, social innovation, and political value change.
The role of credit in a rural economy: The case of Thailand
Authors: Ambali Jayaprakashan , Saeed Khalid 
Published: July 2007

AbstractRural credit schemes have formed an essential part of the rural development programs implemented in the developing countries over the past few decades, although a high default rate has made it difficult to continue to support them. This paper analyzes the high loan default rate in the rural areas of Thailand and attributes the problem to the distribution pattern of land ownership. The availability of credit may help to fuel investments into farm inputs which increase land productivity. However, when most of the land is absentee‐owned, a large share of the benefits of improved productivity is siphoned away by the landlords while the farmers are left with the responsibility of servicing the loan. Since the farmers' financial capacity is limited, a high rate of loan repayment default results. The analysis of the paper is based on a system dynamics model of a dual rural economic system, often encountered in the developing countries. It is shown that the lack of credit facilities is not a fundamental impediment to rural development.
A system dynamics model for estimating heroin imports into the United States
Authors: Gardiner L. Keith , Shreckengost Raymond C. 
Published: July 2007

AbstractA small system dynamics model of the heroin supply in the United States has proved useful in estimating heroin imports and anticipating effects of changes in imports. This paper describes the structure of the model and its application to import data over a ten‐year period. Of particular interest is the way in which the model has been used to flag inconsistencies and fill gaps in federal data.
System dynamics models: A tool for strategic planning of flexible assembly systems
Authors: Zahn Erich , Bunz Andreas , Hopfmann Lienhard 
Published: July 2007

AbstractNotes and Insights is a forum for discussion and debate about current issues in the philosophy and application of the system dynamics approach, and a marketplace for the exchange of information about current research, policy issues, and teaching experiences. Manuscripts treating material particularly suited to presentation in short form (less than 2,000 words) should be sent to Erich Zahn, Betriebswirtschaftliches Institut, Abt. IV, Universität Stuttgart, Keplerstr. 17, 7000 Stuttgart 1, West Germany.
Instabilities and chaos in nonlinear dynamic systems
Authors: Mosekilde Erik , Aracil Javier , Allen Peter M. 
Published: July 2007

AbstractIncreasing computational power in the last decade has led to a breakthrough in the understanding of nonlinear dynamic systems. Deterministic chaos, a distinct mode of behavior qualitatively different from linear modes, can arise in systems with instabilities constrained by nonlinearities.This article overviews this new field. It is observed that deterministic chaos is associated with the presence of a basic instability, often associated with a negative loop with high‐gain and significant delay, that allows small random fluctuations to be amplified and eventually dominate the behavior of the system.The mathematical tools of qualitative analysis of nonlinear systems are applied to familiar models of urban dynamics. Spatial disaggregation in an urban migration model is shown to yield a route to chaos through period‐doubling. Alternative routes to chaos are discussed. Examples from the natural and social sciences are used to demonstrate the applicability of the tools and the ubiquity of such complex nonlinear dynamic phenomena.
Qualitative analysis of system dynamics ecological models
Authors: Toro Miguel , Aracil Javier 
Published: July 2007

AbstractThis article deals with the application of qualitative analysis techniques to system dynamics ecological models. Examples include the predator‐prey and the Kaibab plateau models. In the former, we study the appearance of periodic motions. Bifurcation analysis allows us to determine the essential parameter that controls the appearance of the limit cycle through a Hopf bifurcation. We also study the limit case in which the model tends to be of the Lotka‐Volterra type.The Kaibab plateau model shows a collapse related to the limited availability of resources in a finite habitat. When we combine the structure of the predator‐prey and Kaibab models, we obtain a model representing the chain predator‐prey‐food. Such a model can show a huge variety of behavior modes, including chaos, which we analyze.
A note on migratory dynamics
Authors: Richardson George P. , Sterman John D. 
Published: July 2007

AbstractNotes and Insights is a forum for discussion and debate about current issues in the philosophy and application of the system dynamics approach, and a marketplace for the exchange of information about current research, policy issues, and teaching experiences. Manuscripts treating material particularly suited to presentation in short form (less than 2,000 words) should be sent to Erich Zahn, Betriebswirtschaft‐liches Institut, Abt. IV, Universität Stuttgart, Keplerstr. 17, D‐7000 Stuttgart 1, F.R.G.
The dynamics of shortening working hours
Authors: Zietemann Ulrich D. 
Published: July 2007

AbstractUnemployment is at present one of the main economic problems in most Western countries. Shortening working hours and lowering retirement age have both been proposed as useful means of reducing this problem. Discussion of these measures has been conducted mainly at the macroeconomic level, however, and the consequences of such policies on the labor market have been evaluated differently by employers' groups and labor unions. These different evaluations clearly reflect conflicting political viewpoints but may also arise from the fact that little economic research has been performed in this field. To assess the economic implications of shortening working hours, the author has undertaken a microeconomic investigation to identify the dynamic consequences, especially on staff recruitment and on labor‐capital substitution. This article describes the basic structure of the system dynamics model applied in the study.
Synthetic data experiments using system dynamics models: A survey of results and a research agenda
Authors: Crawford Catherine M. , Andersen David F. , Richardson George P. 
Published: July 2007

AbstractIn this section the System Dynamics Review presents problems having the potential to stimulate system dynamics research. Articles may address real‐world dynamic problems that could be approached fruitfully from the system dynamics perspective, or methodological problems affecting the field. A paper submitted to the Research Problems section should concisely motivate and define a problem and start a process of conceptualization or formulation that can open the way for further studies. Manuscripts not exceeding 2,000 words should be sent to George P. Richardson, Milne 308, Rockefeller College, S.U.N.Y., Albany, NY 12222, U.S.A.
Interfuel substitution in OECD‐European electricity production
Authors: Moxnes Erling 
Published: July 2007

AbstractFuel substitution in OECD‐European electricity production is described by a putty‐clay formulation. At the time of investment, fuel shares are determined according to a logit model. These fuel shares are maintained throughout the lifetime of the power plants. However, a significant share of capacity is assumed to be flexible. Short‐term fuel switching is described by a logit model. An attempt has been made to formulate the model such that all parameters have a real‐life interpetation. This enables the use of a priori data about all parameters. The model gives a very good fit to historical time series for oil, gas, and coal demand when fuel premiums are calibrated. The most striking finding is that there is a strong preference for the use of coal. Because of the a priori data, the model is not very sample‐dependent. Thus, it should be well suited for policy studies or for predictions. The model should be used with caution if very high fuel prices are expected.
A petroleum life cycle model for the United States with endogenous technology, exploration, recovery, and demand
Authors: Davidsen Pål I. , Sterman John D. , Richardson George P. 
Published: July 2007

AbstractThis article describes a model of the life cycle of the petroleum resource in the United States. Expanding on prior system dynamic models of petroleum resources, the model endogenously generates the complete life cycle of the resource. It treats endogenously petroleum demand; the development of technology for, and investment in, exploration and recovery; discovery and production of petroleum; and the development of petroleum substitutes. With only two exogenous variables, GNP and the international petroleum price, the model portrays the evolution of the U.S. petroleum resource, and the associated industry, starting in 1870. The correspondence between simulated and actual data is examined through a variety of statistical measures. The model is used to show how the interaction between technological progress, depletion, imports, and the development of substitutes creates the life cycle by altering the dominance of the feedback processes in the system.
A system dynamics approach to predator‐prey modeling
Authors: Swart Johan 
Published: July 2007

AbstractNotes and Insights is a forum for discussion and debate about current issues in the philosophy and application of the system dynamics approach, and a marketplace for the exchange of information about current research, policy issues, and teaching experiences. Manuscripts treating material particularly suited to presentation in short form (less than 2,000 words) should be sent to Erich Zahn, Betriebswirtschaft‐liches Institut, Abt. IV, Universität Stuttgart, Keplerstr. 17, D‐7000 Stuttgart 1, F.R.G.
Computer‐based case studies and learning laboratory projects
Authors: Graham Alan K. , Senge Peter M. 
Published: July 2007

AbstractIn this section the System Dynamics Review presents problems having the potential to stimulate system dynamics research. Articles may address real‐world dynamic problems that could be approached fruitfully from the system dynamics perspective, or methodological problems affecting the field. A paper submitted to the Research Problems section should concisely motivate and define a problem and start a process of conceptualization or formulation that can open the way for further studies. Manuscripts not exceeding 2,000 words should be sent to George P. Richardson, Milne 308, Rockefeller College, S.U.N.Y., Albany, NY 12222, U.S.A.
Methodologia oeconomiae et systematis dynamis
Authors: Radzicki Michael J. 
Published: July 2007

AbstractAfter enduring years of criticism from members of the economics profession, many system dynamicists have concluded that economists do not like system dynamics. This article outlines the methodologies of both neoclassical and institutional economics and demonstrates that the system dynamics modeling process is strikingly similar to the latter. Because a majority of economists trained in the West are neoclassicals, system dynamicists should not be surprised if many economists label system dynamics models unscientific. And since the institutional approach and the system dynamics approach are similar, it is argued, system dynamics should be used to strengthen and extend institutional economics.
Philosophical roots of model validation: Two paradigms
Authors: Barlas Yaman , Carpenter Stanley 
Published: July 2007

AbstractSystem dynamics models, as causal models, are much like scientific theories. Hence, in evaluating such models, we assume certain norms of scientific inquiry. Most critics hold that the system dynamics approach does not employ formal, objective, quantitative model validation tests. This article argues that this type of criticism presupposes the traditional logical empiricist philosophy of science, which assumes that knowledge is an objective representation of reality and that theory justification can be an objective, formal process. According to the more recent relativist philosophy of science, knowledge is relative to a given society, epoch, and scientific world view. Theory justification is therefore a semiformal, relative social process. We show that relativist philosophy is consistent with the system dynamics paradigm and discuss the practical implications of the two philosophies of science for system dynamics modelers and their critics.
Endogenous safety processes: A model of regulation and safety in industrial firms
Authors: Crawford Catherine M. 
Published: July 2007

AbstractA model of safety and of the impact of the Occupational Safety and Health Administration (OSHA) on safety in industrial firms is described in this article. The model incorporates safety feedback processes in U.S. manufacturing firms, including the relations between safety programs, safety equipment, and accidents. Monte Carlo‐like simulations were produced, with 1,000 firms simulated sequentially. The firms were distributed among the 20 standard industrial sectors and the five size categories that comprise the manufacturing industry. Each firm's safety behavior was simulated for a four‐year period, and each firm was inspected once by OSHA. Injury rates across all firms were measured to determine if OSHA's actions had a measurable effect upon safety in firms. The model captures important underlying assumptions regarding safety regulation that have typically been excluded from evaluations of the impact of safety regulation in the United States. These assumptions may in fact be central to understanding the relations between intervention.
What are we publishing? a view from the editor's desk
Authors: Richardson George P. 
Published: July 2007

AbstractNotes and Insights is a forum for discussion and debate about current issues in the philosophy and application of the system dynamics approach, and a marketplace for the exchange of information about current research, policy issues, and teaching experiences. Manuscripts treating material particularly suited to presentation in short form (less than 2,000 words) should be sent to Erich Zahn, Betriebswirtschaft‐liches Institut, Abt. IV, Universität Stuttgart, Keplerstr. 17, D‐7000 Stuttgart 1, Germany.
Diagnosing surprise model behavior: A tool for evolving behavioral and policy insights (1981)
Authors: Mass Nathaniel J. , Sterman John D. 
Published: July 2007

AbstractFounded in the mid‐1950s, the field of system dynamics has intellectual roots reaching much further into the past. The Archives section of the Review seeks to publish material from that past which can contribute to current theory and practice. The section welcomes previously unpublished but deserving system dynamics work, classics from past system dynamics literature that should receive renewed attention, and previously published articles from other disciplines of particular significance to current system dynamicists. Contributions emphasizing the philosophy and theory of model building, validation, implementation, education, and generic structures are particularly encouraged. Submissions may range in length from notes to main articles but may be edited. Send suggested material, together with a brief introduction placing it in historical and current contexts, to John D. Sterman, System Dynamics Group. MIT E40‐294, Cambridge, MA 02139, U.S.A.
Slicing a complex problem for system dynamics modeling
Authors: Saeed Khalid 
Published: July 2007

AbstractNotes and Insights is a forum for discussion and debate about current issues in the philosophy and application of the system dynamics approach, and a marketplace for the exchange of information about current research, policy issues, and teaching experiences. Manuscripts treating material particularly suited to presentation in short form (less than 2,000 words) should be sent to Erich Zahn, Betriebswirtschaft‐liches Institut, Abt. IV, Universitat Stuttgart, Keplerstr. 17, D‐7000 Stuttgart 1, Germany.Since formal modeling requires having a model boundary encompassing finite complexity so that deductive logic is possible, complex problems must be partitioned into simpler parts before being analyzed. There are many ways to slice a complex problem but not all create partitions that keep together processes contributing to effective policy design. This paper explores ways in which a complex problem may be appropriately sliced so that the models of partitions can serve as effective tools for policy design.
Benchmarking the system dynamics community
Authors: Scholl Greg J. 
Published: July 2007

AbstractIn this section the System Dynamics Review presents problems having the potential to stimulate system dynamics research. Articles may address real‐world dynamic problems that could be approached fruitfully from the system dynamics perspective, or methodological problems affecting the field. A paper submitted to the Research Problems section should concisely motivate and define a problem and start a process of conceptualization or formulation that can open the way for further studies. Manuscripts not exceeding 2,000 words should be sent to George P. Richardson, Milne 308, Rockefeller College, S.U.N.Y., Albany, NY 12222, U.S.A.
Bringing experimental learning to the social sciences: A simulation laboratory on economic development
Authors: Saeed Khalid 
Published: July 2007

AbstractThis article explores the possibility of introducing experimental learning into the social science disciplines through use of custom‐built experimental media drawing on the system dynamics method. Such learning would essentially require integration of interactive simulation with text materials. A simulation laboratory consisting of a book on issues of economic development and user‐friendly simulation software, developed by the author, is presented as an example of such media. This package may be suitable for use as a graduate text that integrates theory and practicum or as a professional reference tool. The integration of practicum into the teaching of the social sciences would, however, not only require creating new text materials and software suitable for use by students with little computer or mathematics expertise but also modifying teaching formats to accommodate practicum.