Online Content

201. Saeed, Khalid, "Economic Growth and Political Instability in the Developing Countries: A Systems View"

Type:
Document
Date Created:
1983
Collection:
System Dynamic Society Records
Collecting Area:
University Archives
Collection ID:
ua435
Parent Record(s):
23d738ba88f8333bc39725f9cb5bd0b8, cf82ceba47eedd73f41b00918de16477, and b0aa2a699b54f0d19f6a9d93bdbcfa18
Thumbnail Path Ss:
/downloads/47429t633?file=thumbnail
System Modified Dtsi:
2020-01-02T18:37:18Z
Description:
Accelerating the rate of economic growth in developing countries has been the important aim of almost all development policies implemented over the past three decades. Experience has shown that such growth is often not sustainable and is likely to be interrupted due to the occurrence of violent political changes. The paper attempts to identify the organizational factors which limit economic growth and which create conditions conducive to the outbreak of political violence. A mathematical model of the socio-political system of the developing country is developed and its behavior is studied using simulation.

202. Saeed, Khalid with M. A. Satter and Gajendra Singh, "Rice Crop Production Policies and Food Supply in Bangladesh"

Type:
Document
Date Created:
1983
Collection:
System Dynamic Society Records
Collecting Area:
University Archives
Collection ID:
ua435
Parent Record(s):
23d738ba88f8333bc39725f9cb5bd0b8, cf82ceba47eedd73f41b00918de16477, and b0aa2a699b54f0d19f6a9d93bdbcfa18
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System Modified Dtsi:
2020-01-02T18:37:19Z
Description:
This paper examines the role of food producers, population, and the government on the present availability of food in Bangladesh. The study employs a system dynamics model of the population-food-production system for its analysis. This model incorporates mechanisms of production and consumption of food, and population growth. Government policies are considered exogenously. The analysis suggests that, due to the presence of a feedback relationship between food availability and population growth, any policy for improving food supply cannot be considered independently of time. In the long run, none of the policies tested alleviates the shortage, although in the short and intermediate runs, agricultural development and population control policies may improve food consumption per capita. The paper thus seriously questions the rationale of agricultural development policies aimed at increasing food production. However, since many food surplus countries support small populations which are also growing at slow rates, points of entry for policies that effectively alleviate the food shortage should exist. Thus, food policy models for the developing countries should aim at identifying such entry points into the system instead of attempting to increase the food supply.

203. Sancar, Fahriye H., "System Dynamics as a Heuristic for Systems Design"

Type:
Document
Date Created:
1983
Collection:
System Dynamic Society Records
Collecting Area:
University Archives
Collection ID:
ua435
Parent Record(s):
23d738ba88f8333bc39725f9cb5bd0b8, cf82ceba47eedd73f41b00918de16477, and b0aa2a699b54f0d19f6a9d93bdbcfa18
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/downloads/6d570f02r?file=thumbnail
System Modified Dtsi:
2020-01-02T18:37:20Z
Description:
Socio-economic planning primarily addresses the solution of problems relating to inherently indeterminate systems. The class of systems exhibits two sources of complexity which can be conceptualized as the complexity of the idea system and the complexity of the actual physical system. The idea system introduces a multiplicity of available theories, disciplinary differences between the stakeholder roles. The actual system is complex because there usually is not sufficient empirical data relevant to the particular problem since the situational context is unprecedented and non-repeating.It can be argued that problem solving in this context involves designing a new system structure to facilitate social learning, using a heuristic approach. Such a heuristic is different from the more conventional approaches to modeling and problem solving in that it bounds the search space and enhances further inquiry rather than just reflecting the real world conditions. In this paper the main characteristics of this approach are discussed and methodological implications for System Dynamics modeling are drawn.

204. Shreckengost, Raymond C. with Sheryl P. Shreckengost, "An Introduction to System Dynamics in a Non-Traditional Graduate Program"

Type:
Document
Date Created:
1983
Collection:
System Dynamic Society Records
Collecting Area:
University Archives
Collection ID:
ua435
Parent Record(s):
23d738ba88f8333bc39725f9cb5bd0b8, cf82ceba47eedd73f41b00918de16477, and b0aa2a699b54f0d19f6a9d93bdbcfa18
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/downloads/bz60dd968?file=thumbnail
System Modified Dtsi:
2020-01-02T18:37:21Z
Description:
System dynamics has been taught for over two years in two doctoral programs offered by Nova University, Fort Lauderdale , Florida. These programs are designed for working professionals in public and business administration and feature the inverse of the usual arrangement in which instruction is given on the university campus. For this reason, a traditional teaching approach cannot be used. This paper describes the Nova teaching environment, the format and teaching materials used for system dynamics, student characteristics and performance, and the present trends which affect instruction in system dynamics at Nova University.The introduction of the course in system dynamics has generated a positive response among the students and a limited amount of turbulence in the organization and administration of the program.

205. Sedehi, Habib with Paola Valli and Paolo Verrecchia, "Dynamic Models for Planning Tourist Complexes"

Type:
Document
Date Created:
1983
Collection:
System Dynamic Society Records
Collecting Area:
University Archives
Collection ID:
ua435
Parent Record(s):
23d738ba88f8333bc39725f9cb5bd0b8, cf82ceba47eedd73f41b00918de16477, and b0aa2a699b54f0d19f6a9d93bdbcfa18
Thumbnail Path Ss:
/downloads/1831d2596?file=thumbnail
System Modified Dtsi:
2020-01-02T18:37:22Z
Description:
Planning tourist facilities is a highly complex task. It is necessary to evaluate carefully, with an interdisciplinary approach, all the variables of a technical, architectural, commercial, economical and financial nature that may be involved in a given project, without however ignoring the natural resources of the environment where facilities are to be set up. For a correct evaluation, these resources must be considered limited and seen as a wealth that can be exploited but not wasted, used but not destroyed. The approach outlined above is all the more important in countries like Italy, for instance, where there is a risk of over-exploiting the natural resources of the environment. In all but exceptional cases, an evaluation that does not take the above principles into account will result in a tourist enterprise that is ultimately a failure, as it degrades, often irreparably, the natural environment until it ceases to be an adequate source of revenue. This paper describes an integrated approach which provides, by means of simulation techniques, tools for a proper implementation of tourist facilities taking into due account all the variables and constraints involved, and likewise for the assessment by the Public Administration authorities of the wisdom and soundness of projects submitted to them for approval.

206. Senge, Peter M., "System Dynamics: A Possible Artifact for the Systems Age"

Type:
Document
Date Created:
1983
Collection:
System Dynamic Society Records
Collecting Area:
University Archives
Collection ID:
ua435
Parent Record(s):
23d738ba88f8333bc39725f9cb5bd0b8, cf82ceba47eedd73f41b00918de16477, and b0aa2a699b54f0d19f6a9d93bdbcfa18
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/downloads/3r075b838?file=thumbnail
System Modified Dtsi:
2020-01-02T18:37:23Z
Description:
The purpose of this paper is to expand our thinking about the possible role system dynamics may play in the evolution of western thought and society. While such a theme may seem presumptuous when applied to a toll known to only a small fraction of people at present, it is my intention to give it some credibility by showing that western society may already be in the midst of evolving fundamental assumptions, beliefs and perceptions more consistent with a systemic world view. Pulled by this undercurrent, tools like system dynamics can focus the forces of change and bring them to bear more directly on pressing societal problems.

207. Shorb, Alan Mck, "System Dynamics by Visicalc: Simulation Models Using the New Spreadsheet Programs"

Type:
Document
Date Created:
1983
Collection:
System Dynamic Society Records
Collecting Area:
University Archives
Collection ID:
ua435
Parent Record(s):
23d738ba88f8333bc39725f9cb5bd0b8, cf82ceba47eedd73f41b00918de16477, and b0aa2a699b54f0d19f6a9d93bdbcfa18
Thumbnail Path Ss:
/downloads/79408f10k?file=thumbnail
System Modified Dtsi:
2020-01-02T18:37:25Z
Description:
Visicalc, the original spreadsheet program for microcomputers is explored for suitability as a vehicle for system dynamics models. It is shown that Visicalc can support most of the model features that DYNAMO allows, but at the price of some inconvenience and care needed when setting up the model. However, with the widespread distribution of spreadsheet programs among decision makers, there maybe situations where they may be the vehicle of choice for implementing a dynamic model.

208. Simonsen, Carl, "An Application of SD to Military Combat Modelling"

Type:
Document
Date Created:
1983
Collection:
System Dynamic Society Records
Collecting Area:
University Archives
Collection ID:
ua435
Parent Record(s):
23d738ba88f8333bc39725f9cb5bd0b8, cf82ceba47eedd73f41b00918de16477, and b0aa2a699b54f0d19f6a9d93bdbcfa18
Thumbnail Path Ss:
/downloads/mg74r460x?file=thumbnail
System Modified Dtsi:
2020-01-02T18:37:26Z
Description:
The paper discusses an application of SD to the modelling of ground force combat at about Corps level. The model is based on Lanchester’s equation incorporating concepts for the build-up of combat-ready forces and alternative strategies for their commitment in relation to beak-through criteria. These alternative strategies, together with the appropriate tactical rules for force employment and deployment, determine what may be regarded as policies for the use of forces. The model has been used to investigate these policies and the effect of delays in their implementation. Some illustrative results and conclusions are also discussed.Note: There is no paper available.

209. Sterman, John D., "Appropriate Summary Statistics for Evaluating the Historical Fit of System Dynamics Models"

Type:
Document
Date Created:
1983
Collection:
System Dynamic Society Records
Collecting Area:
University Archives
Collection ID:
ua435
Parent Record(s):
23d738ba88f8333bc39725f9cb5bd0b8, cf82ceba47eedd73f41b00918de16477, and b0aa2a699b54f0d19f6a9d93bdbcfa18
Thumbnail Path Ss:
/downloads/df65vs61d?file=thumbnail
System Modified Dtsi:
2020-01-02T18:37:27Z
Description:
System Dynamics models are often faulted for their reluctance to employ formal measures of goodness-of-fit when assessing the historical behavior of models. As a result, the validity of system dynamics models is often questioned even when the model’s correspondence to historical behavior is quite good. This paper argues that the failure to present formal analysis of historical behavior creates an impression of sloppiness and unprofessionalism. After reviewing the concept of validity in simulation modeling, the paper proposes a simple set of summary statistics appropriate for system dynamics models (the root-mean-square error and Theil inequality statistics). The statistics allow the error due to individual behavior modes to be analyzed, do not require the use of formal parameter estimation procedures, and can be conveniently computed. A large model of the U.S. economy is used to illustrate the use of statistics.

210. Sterman, John D., " A Simple Model of the Economic Long Wave"

Type:
Document
Date Created:
1983
Collection:
System Dynamic Society Records
Collecting Area:
University Archives
Collection ID:
ua435
Parent Record(s):
23d738ba88f8333bc39725f9cb5bd0b8, cf82ceba47eedd73f41b00918de16477, and b0aa2a699b54f0d19f6a9d93bdbcfa18
Thumbnail Path Ss:
/downloads/td96kk919?file=thumbnail
System Modified Dtsi:
2020-01-02T18:37:28Z
Description:
Sensitivity testing, according to the glossary of terms in a Congressional manual on simulation modeling, is defined as the “running of a simulation model by successively changing the states of the system…and comparing the model outputs to determine the effects of these changes” (Congress 1975, p. 129). Sensitivity testing is generally viewed as an important part of the modeling process because it helps researchers narrow down those areas where more data gathering would be useful. In our introductory remarks, we argue that detailed sensitivity testing is particularly important in system dynamics modeling efforts, and we list several obstacles that make detailed sensitivity testing difficult. We introduce a set of testing procedures developed at the Los Alamos National Laboratory and verified by the Control Data Corporation that can help system dynamicists perform detailed sensitivity testing on a routine basis. In the body of the paper, we present an illustrative application of the testing procedures, and we list six specific uses of the procedures. We describe the availability of the testing package, and we conclude with a set of practical guidelines for investigators wishing to make use of this unique set of procedures.

211. Thompson, Ray with R. C. Shreckengost, "Using System Dynamics to Improve the Management of Working Capital in a Small Business"

Type:
Document
Date Created:
1983
Collection:
System Dynamic Society Records
Collecting Area:
University Archives
Collection ID:
ua435
Parent Record(s):
23d738ba88f8333bc39725f9cb5bd0b8, cf82ceba47eedd73f41b00918de16477, and b0aa2a699b54f0d19f6a9d93bdbcfa18
Thumbnail Path Ss:
/downloads/kw52js22q?file=thumbnail
System Modified Dtsi:
2020-01-02T18:37:29Z
Description:
Many firms use financial ratio analysis to monitor their control over the operating cycle and to serve as the basis for policy formation. Ratios are based on data produced through the accounting information system which is analyzed according to intuitively plausible concepts in order to make normative judgement about the financial health of the firm. A model is constructed to simulate the operating cycle of a business which generates financial ratios in a manner analogous to the accounting system. It is shown that noise and seasonality produce distortions in the ratio measures are spread throughout the system in a dynamic and complex fashion. Further experiments reveal that plausible control policies based upon financial ratios may make performance worse rather than better. System Dynamics appears to be a useful approach both to redesigning financial ratio measures and testing policies which could enhance out ability to manage such systems.

212. Torrealdea, F.with J. M. Graña, "Some Ideas for a History Dynamics Model"

Type:
Document
Date Created:
1983
Collection:
System Dynamic Society Records
Collecting Area:
University Archives
Collection ID:
ua435
Parent Record(s):
23d738ba88f8333bc39725f9cb5bd0b8, cf82ceba47eedd73f41b00918de16477, and b0aa2a699b54f0d19f6a9d93bdbcfa18
Thumbnail Path Ss:
/downloads/z029pp33j?file=thumbnail
System Modified Dtsi:
2020-01-02T18:37:30Z
Description:
In this paper some of the ideas of Ortega y Gasset about the dynamics of history have been gathered and organized according to the system dynamics diagrams. A cyclic process, characteristic of every normal course of history, is described as well as the dynamics hypothesis responsible for it. Human life, as far as it affects history, is shown as being composed of five age groups each of them covering fifteen years of life. Two of these groups, two generations acting simultaneously in the field of history, are presented as taking the main responsibility for the dynamics of history.

213. Van Buren, Gregory with David H. Goodstein, "Development of a Casual User Interface for Simulation Models"

Type:
Document
Date Created:
1983
Collection:
System Dynamic Society Records
Collecting Area:
University Archives
Collection ID:
ua435
Parent Record(s):
23d738ba88f8333bc39725f9cb5bd0b8, cf82ceba47eedd73f41b00918de16477, and b0aa2a699b54f0d19f6a9d93bdbcfa18
Thumbnail Path Ss:
/downloads/6d570f031?file=thumbnail
System Modified Dtsi:
2020-01-02T18:37:31Z
Description:
:One of the traditional obstacles to effective utilization of simulation models has been the great deal of time spent learning languages in which models are written and keeping track of the specific variable names and equations within models. To remove the excessive psychological burden from busy executives and to refocus attention towards the actual behavior being replicated, Inter/Consult has been researching development of highly supportive user interfaces to models. These interfaces prompt users by stating the nature of the model’s assumptions then asking what changes they would like to make. Through this on-line question-and-answer dialog users can build and compare scenarios without prior knowledge of computer languages and mathematical formulas or specific model components. Our paper presents reactions to the interface by members of the graphic arts industry who have used it. We discuss further improvements which are being made to the interface to make our models more accessible to non-expert users. Finally we explain why we feel that tightly-focused, easy-to-use, dynamic simulation models are of invaluable benefit to any industry such as graphic arts where craft-oriented skills are being replaced by rapidly evolving new technologies.

214. Vasarhelyi , Miklos, "Counterintuitive Economic Consequences of Accounting Policies: A Dynamic Analysis"

Type:
Document
Date Created:
1983
Collection:
System Dynamic Society Records
Collecting Area:
University Archives
Collection ID:
ua435
Parent Record(s):
23d738ba88f8333bc39725f9cb5bd0b8, cf82ceba47eedd73f41b00918de16477, and b0aa2a699b54f0d19f6a9d93bdbcfa18
Thumbnail Path Ss:
/downloads/zc77t792q?file=thumbnail
System Modified Dtsi:
2020-01-02T18:37:32Z
Description:
This paper uses a system dynamics simulation methodology to assess the potential effects of new accounting policies being considered by rule formulating bodies. The key objective of this paper is to demonstrate that current ex-ante intuitive assessment of the effect of proposed accounting rules is inadequate due to the counterintuitive nature of economic consequences in a complex social system. For this purpose a very simplified model of he US economy is developed and its parameters varied to reflect potential accounting policy changes. The effects of these policy changes are shown to be counterintuitive in nature, requiring consideration of second and third harmonics of the feedback loops for adequate ex-ante impact assessment. This paper is divided into six parts: the first part describes alternate approaches to economic consequence assessment and the advantages and disadvantages of utilizing the system dynamics methodology; the second part describes the skeleton of the system dynamics model; the third part examines the measurement problems of rates, levels, and delays as well as reviews the details of their computation for model formulation; the fourth part discusses the problems and results of model validation efforts; the fifth part describes some of the results obtained from application of the model, and their meaning in comparison with traditional methodologies for accounting impact analysis; the sixth part concludes by suggesting the next step for macro-accounting modeling: evaluating the potential and shortcomings of this methodology.

215. Wang, Qifan with John D. Sterman, "A Disaggregate Population Model of China"

Type:
Document
Date Created:
1983
Collection:
System Dynamic Society Records
Collecting Area:
University Archives
Collection ID:
ua435
Parent Record(s):
23d738ba88f8333bc39725f9cb5bd0b8, cf82ceba47eedd73f41b00918de16477, and b0aa2a699b54f0d19f6a9d93bdbcfa18
Thumbnail Path Ss:
/downloads/5999nn005?file=thumbnail
System Modified Dtsi:
2020-01-02T18:37:33Z
Description:
A disaggregate population model of China is presented. The age structure is represented by one-year cohorts. Urban and rural populations are distinguished. Birth and death rates, family size, life expectancy, and other demographic variables are determined endogenously. The model can be used to analyze population problems and to project population size, the age structure, the adult labor force, the elderly population, and so on. The model can be used in two modes. It can be used to project the consequences of various exogenous fertility levels. Alternatively, birth rates and fertility can be determined endogenously by economic inputs such as food supply, GDP, and services. The model incorporates socioeconomic factors important in the demographic transition, such as the effect of perceived life expectancy on fertility, the effects of traditional values, and the ability of government to influence family fertility choices. The model can be used to evaluate policies and programs designed to control population growth, such as delayed marriage age, improved contraception, and restrictions on family size. The model requires industrial, service, and food output per worker as inputs, and also the level of pollution. The model should be thought of as a component of a comprehensive planning model which generates these inputs endogenously. Based on the system dynamics approach to modeling complex systems, the model is implemented in the DYNAMO simulation language.

216. Weil, Henry Birdseye, "What is an Adequate Model?"

Type:
Document
Date Created:
1983
Collection:
System Dynamic Society Records
Collecting Area:
University Archives
Collection ID:
ua435
Parent Record(s):
23d738ba88f8333bc39725f9cb5bd0b8, cf82ceba47eedd73f41b00918de16477, and b0aa2a699b54f0d19f6a9d93bdbcfa18
Thumbnail Path Ss:
/downloads/cj82ks14m?file=thumbnail
System Modified Dtsi:
2020-01-02T18:37:34Z
Description:
Much of the literature on model evaluation focuses on what amount to absolute measures, that are independent of the context in which a particular model is used. This paper argues in favor of situation-dependent measures. Whether or not a model is “good enough” depends on the job it is being asked to do and the mid set of the people who must use the results. The relationships between model adequacy and successful implementation of model-based recommendations are discussed. While rejecting the classical paradigm, the author emphasizes model realism and historical accuracy as important determinants of implementation. The life of the model involves many evaluations of whether it is “worth the costs”, “believable”, “useful”, and “right”. Issues surrounding these judgements are explored. How differences in circumstances can lead to different, but in each case quite adequate, models is illustrated by contrasting two models developed five years apart for the same organization. The paper concludes that successful models are persuasive, not simply to modeling technicians but to high-level decision makers.

217. White , Norman F., "System Models in the Health Sciences"

Type:
Document
Date Created:
1983
Collection:
System Dynamic Society Records
Collecting Area:
University Archives
Collection ID:
ua435
Parent Record(s):
23d738ba88f8333bc39725f9cb5bd0b8, cf82ceba47eedd73f41b00918de16477, and b0aa2a699b54f0d19f6a9d93bdbcfa18
Thumbnail Path Ss:
/downloads/n009wk236?file=thumbnail
System Modified Dtsi:
2020-01-02T18:37:35Z
Description:
In the health sciences, concepts are shifting toward system models which recognize multiple factors interacting to determine health phenomena. The hybrid biomedical disease model has proven insufficient for the analysis of modern health problems. A population perspective and an expansion in the influence of the behavioral and social sciences have required conceptual models with greater breadth, and facility in relations between models. Morbidity is portrayed here as two domains of phenomena, the disease process and the illness state, each seen as part of a socio-ecological dynamic. Applied to major disease problems, the utility of these propositions can be examined. In the McMaster M.D. program, this set of models has been translated into a curricular structure which has the individual in all her/his healthy or morbid aspects as the interface between biological and social systems. Perplexing dilemmas in health care thus become not only understandable but predictable. Adopting this approach creates a new generation of problems. Just as our students have become familiar with the critical appraisal of evidence, the testing of conceptual models becomes a necessary skill. The background of this analysis is the socio-ecological niche of concepts. A model of models is proposed in which concepts interact with problem environments and modern medicine emerges as a case study for socio-ecological epistemology.

218. Wolstenholme Eric F., "Development of System Dynamics into a More Complete Methodology for Practical Systemic Enquiry"

Type:
Document
Date Created:
1983
Collection:
System Dynamic Society Records
Collecting Area:
University Archives
Collection ID:
ua435
Parent Record(s):
23d738ba88f8333bc39725f9cb5bd0b8, cf82ceba47eedd73f41b00918de16477, and b0aa2a699b54f0d19f6a9d93bdbcfa18
Thumbnail Path Ss:
/downloads/rn301j92k?file=thumbnail
System Modified Dtsi:
2020-01-02T18:37:36Z
Description:
The premise of this paper is that System Dynamics has, in the past, been primarily perceived, both by external observers and by most of its own practitioners, as a technique of computer simulation. Although this situation is changing, there is still little wide scale recognition of its true generality and relevance as a complete subject of systemic enquiry. The purpose of this paper is to explore the merits of system Dynamics as a total systems methodology. Specifically the presentation will undertake to review the need for and the requirements demanded of such problem solving methodologies, to briefly explore the dilemma resulting from historic attempts to create them and to present changes to the existing Systems Dynamics method which might improve its conformity and acceptability as such a methodology. These include the formal definition of Qualitative System Dynamics and the presentation of a set of rigorous rules to provide much needed guidance in its application; firstly, Stepwise Influence Diagramming, aimed at enhancing problem exploration and model development and secondly, Qualitative analysis, aimed at identifying critical system components and exploring the effects of change.

219. Wood, William T., "Modeling Stochastic Processes with System Dynamics"

Type:
Document
Date Created:
1983
Collection:
System Dynamic Society Records
Collecting Area:
University Archives
Collection ID:
ua435
Parent Record(s):
23d738ba88f8333bc39725f9cb5bd0b8, cf82ceba47eedd73f41b00918de16477, and b0aa2a699b54f0d19f6a9d93bdbcfa18
Thumbnail Path Ss:
/downloads/fq978c32q?file=thumbnail
System Modified Dtsi:
2020-01-02T18:37:37Z
Description:
System Dynamics as a methodology has traditionally been concerned with the study of processes that can be described by continuous variables. Discrete or integer events, such as the number of sales made in a day or the number of factory closings in a year have either been approximated as continuous variables or else not dealt with. This paper examines another way of dealing with discrete events through the realization that any discrete event has a certain probability of occurance. These probabilities are continuous and conserved quantities and can be modeled as system dynamic levels. Treating probabilities as levels in dynamic simulations is a standard technique in stochastic modeling, markov models being one example. System dynamics' advantage over these other methods is that it can represent the impact of the results of the probabilistic study of the social feedback systems. This paper focuses on examples demonstrating the use of system dynamics to model uncertain events. These examples deal with the simple case of a Poisson process with a time varying event arrival rate. Extensions incorporating conditional and independent probabilities are also considered.

220. Anderson, David F. with David P. McCaffrey, Paul McCold and Doa Hoon Kim,"Regression and Case Studies of Public Programs: Discrepant Findings and a Suggested Bridge"

Type:
Document
Date Created:
1984
Collection:
System Dynamic Society Records
Collecting Area:
University Archives
Collection ID:
ua435
Parent Record(s):
dcf80aca09fd0af264c0472357441115, 23d738ba88f8333bc39725f9cb5bd0b8, and 6e5cbea1fd05527880f389afd8fb85d1
Thumbnail Path Ss:
/downloads/th83mh05p?file=thumbnail
System Modified Dtsi:
2020-01-02T18:37:38Z
Description:
Case studies of regulatory and social programs suggest that policy systems are dynamic. In the systems described, outcomes depend on how variables interact over time, and feedback among variables--“simultaneous” causation over multiple time periods--is more a rule than an exception. However, the most influential evaluations of public programs are studies using multiple regression. A recognized limitation of multiple regression is its relative insensitivity to multiperiod strategies, feedback among variables, and other dynamics. Accordingly, we maintain, the findings of regression-based and case studies commonly conflict. Simulation modeling can serve as a methodological bridge between case studies and regression-based studies of policy systems, improving theoretical models of the system and providing a way to evaluate the robustness of alternative regression models. The results of some early experiments along these lines are presented.

221. Cámara, António S. with José G. A. de Meneses, João P. A. Fernandes, Ana P. N. Amoro and M. Garca Viegas,"Water Resources Management of Algarve-Interfacing System Dynamics and Multiobjective Programming"

Type:
Document
Date Created:
1984
Collection:
System Dynamic Society Records
Collecting Area:
University Archives
Collection ID:
ua435
Parent Record(s):
dcf80aca09fd0af264c0472357441115, 23d738ba88f8333bc39725f9cb5bd0b8, and 6e5cbea1fd05527880f389afd8fb85d1
Thumbnail Path Ss:
/downloads/tm70nd686?file=thumbnail
System Modified Dtsi:
2020-01-02T18:37:39Z
Description:
The Algarve province in southern Portugal has been undergoing a rapid growth due to a large increase in tourist demand. The mismanagement of the region’s water resources is leading those growth trends to halt. This paper introduces a model developed to provide a needed rational framework for Algarve water resources management, interfacing a system dynamics model with multiobjective programming formulations. The definition of water supply and demand sectors, on a spatially disaggregated basis, is an essential component of the model, with attempts to provide a tool to evaluate the effects of different strategies controlling water supply and demand upon a set of impact variables. To select an optimal strategy one has to solve a multiobjective programming problem, where the components of the objective function are the impact variables referred above. Solution methods include the analytic hierarchy process and the value display approach. The model written in Z-BASIC was run using a simulation period of 10 years.

222. Clark, Rolf,"System Dynamics and the User:A View from the Trenches"

Type:
Document
Date Created:
1984
Collection:
System Dynamic Society Records
Collecting Area:
University Archives
Collection ID:
ua435
Parent Record(s):
dcf80aca09fd0af264c0472357441115, 23d738ba88f8333bc39725f9cb5bd0b8, and 6e5cbea1fd05527880f389afd8fb85d1
Thumbnail Path Ss:
/downloads/d504s423d?file=thumbnail
System Modified Dtsi:
2020-01-02T18:37:40Z
Description:
Practitioners of system dynamics working in the government sector will often operate in environments filled with administrative complexities and bureaucratic inconsistencies. Some examples of less than ideal conditions encountered in a fairly large policy planning effort are here offered for the student of system dynamics.

223. Daniels, David with Jane K. Boorstein,"Aid to Families with Dependent Children: A System Dynamics Model"

Type:
Document
Date Created:
1984
Collection:
System Dynamic Society Records
Collecting Area:
University Archives
Collection ID:
ua435
Parent Record(s):
dcf80aca09fd0af264c0472357441115, 23d738ba88f8333bc39725f9cb5bd0b8, and 6e5cbea1fd05527880f389afd8fb85d1
Thumbnail Path Ss:
/downloads/7s75dx53x?file=thumbnail
System Modified Dtsi:
2020-01-02T18:37:41Z
Description:
The purpose of this model is to gain insight into the relationship between poverty and AFDC assistance, to diagnose and explain causes and- on the basis of these findings- to test policy alternatives to alleviate poverty.

224. DiStefano, Julia M.,"Focus on FeedbackApplication of System Dynamics to Public Speaking"

Type:
Document
Date Created:
1984
Collection:
System Dynamic Society Records
Collecting Area:
University Archives
Collection ID:
ua435
Parent Record(s):
dcf80aca09fd0af264c0472357441115, 23d738ba88f8333bc39725f9cb5bd0b8, and 6e5cbea1fd05527880f389afd8fb85d1
Thumbnail Path Ss:
/downloads/zc77t7930?file=thumbnail
System Modified Dtsi:
2020-01-02T18:37:43Z
Description:
The interaction between the speaker and his audience is a subject of universal interest, especially to professionals. It is a subject, moreover, requiring a dynamic method of analysis. This paper presents a conceptual model of public speaking. The purpose of this preliminary study is to identify the essential factors needed for (1) the effective delivery of a prepared speech in a conversational manner and (2) the growth of the speaker's abilities over time. As a result of my preliminary analysis of the feedback loops operating during a technical presentation, my approach to teaching novice speakers has changed. One benefit of my new approach is that it accelerates the process by which novices develop the competencies they need to give successful informative speeches. Further study of the interaction between speaker and audience using System Dynamics will contribute significantly to our understanding of human communication.

225. Forrester, Jay W.,"The System Dynamics National Model--Objectives, Philosophy, and Status"

Type:
Document
Date Created:
1984
Collection:
System Dynamic Society Records
Collecting Area:
University Archives
Collection ID:
ua435
Parent Record(s):
dcf80aca09fd0af264c0472357441115, 23d738ba88f8333bc39725f9cb5bd0b8, and 6e5cbea1fd05527880f389afd8fb85d1
Thumbnail Path Ss:
/downloads/0g354z615?file=thumbnail
System Modified Dtsi:
2020-01-02T18:37:44Z
Description:
The System Dynamics National Model represents a typical, modern, industrial economy. Although parameters have been chosen for the United States, the behavior modes exhibited by the model are those being experienced in most economies in Western developed countries. The National Model incorporates a wide range of dynamic structures that allow its behavior to span from the short-term business cycle of 3-to-7 year periodicity to the much longer-term behaviors represented by growth and by major depressions that recur at intervals of some fifty years. The System Dynamics National Model has been under development for about twelve years. An evolutionary process has been followed during which we have extended the scope of the model, added sectors, identified and corrected misbehavior, and simplified unnecessarily complex structures. There have been more than a thousand modifications and extensions of the Model. The National Model is now close to meeting our primary objectives, and we have started writing four books describing the Model and its implications for economic behavior.

226. Gervasio, Vincenzo,"A System Dynamics Approach to Corporate Modelling"

Type:
Document
Date Created:
1984
Collection:
System Dynamic Society Records
Collecting Area:
University Archives
Collection ID:
ua435
Parent Record(s):
dcf80aca09fd0af264c0472357441115, 23d738ba88f8333bc39725f9cb5bd0b8, and 6e5cbea1fd05527880f389afd8fb85d1
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/downloads/xk81k403n?file=thumbnail
System Modified Dtsi:
2020-01-02T18:37:45Z
Description:
The acronym “MDS” refers to the methodology and a series of computing techniques which are suitable for the simulation of corporate processes. These “Dynamic Models for Corporate Strategies” allow the description of such processes as structures of a unified nature, into which one may insert all the necessary data (real or hypothetical) deriving from the initial and boundary conditions, to clearly define the possible future developments being studied. With respect to other, currently available, decisional aids, MDS differs both by its purely simulative approach and by its use of the basic descriptive structure capable of completely representing the dynamism of corporate phenomena. Compared to a “company microcosm” description using the now classical methods of Industrial Dynamics, MDS offers open and interactive systems also introducing several “corporate variants”. (These correspond both to certain types of sub-division of the complete system into given sub-system, and to relationships which may also be described in the same terms, such as the ‘accounts plan’, for example). The main aim of this paper is to analyse the effects of promotional activity- recently developed in Italy amongst medium and large companies- whose main objective is the introduction of MDS as an imprtant instrument in the practice of corporate planning.

227. Goluke, Ulrich," Towards a General Theory of Adaptive Systems"

Type:
Document
Date Created:
1984
Collection:
System Dynamic Society Records
Collecting Area:
University Archives
Collection ID:
ua435
Parent Record(s):
dcf80aca09fd0af264c0472357441115, 23d738ba88f8333bc39725f9cb5bd0b8, and 6e5cbea1fd05527880f389afd8fb85d1
Thumbnail Path Ss:
/downloads/9019sk403?file=thumbnail
System Modified Dtsi:
2020-01-02T18:37:46Z
Description:
A generic model of adaptive systems behaviour is developed in causal loop form. Examples from many different living systems are given. Living systems do adapt: plants turn towards the light; birds fly south in the winter; people acquire a taste for champagne; revolutionaries become government bureaucrats; and cultures have dealt with horseless carriages and jet travel. Living systems also collapse: lakes get polluted and die; dinosaurs are no more; people commit suicide; there is no more Federalist party; and the Indian Nations of North America have all disappeared. As a system dynamist I am interested in the attribute or, more exactly, the minimal set of attributes of all these systems that can explain the capability to adapt and also the obvious limits to that same capability.

228. Gottschalk, Peter,"System Dynamics Modelling in a Cable Manufacturing Corporation"

Type:
Document
Date Created:
1984
Collection:
System Dynamic Society Records
Collecting Area:
University Archives
Collection ID:
ua435
Parent Record(s):
dcf80aca09fd0af264c0472357441115, 23d738ba88f8333bc39725f9cb5bd0b8, and 6e5cbea1fd05527880f389afd8fb85d1
Thumbnail Path Ss:
/downloads/mw22vp90h?file=thumbnail
System Modified Dtsi:
2020-01-02T18:37:47Z
Description:
The paper describes eight problems within the Cable Division of Standard Telefon og Kablefabrik A/S which are currently being analyzed using system dynamics. Problem 7, concerned with information system projects, is described in detail.

229. Graham, Alan K.,"Introduction to the System Dynamics National Model Structure"

Type:
Document
Date Created:
1984
Collection:
System Dynamic Society Records
Collecting Area:
University Archives
Collection ID:
ua435
Parent Record(s):
dcf80aca09fd0af264c0472357441115, 23d738ba88f8333bc39725f9cb5bd0b8, and 6e5cbea1fd05527880f389afd8fb85d1
Thumbnail Path Ss:
/downloads/fx71b447m?file=thumbnail
System Modified Dtsi:
2020-01-02T18:37:48Z
Description:
The System Dynamics National Model is a large computer simulation model of a typical industrialized economy, with its parameters adjusted to reflect the size and character of the United States. The model's purpose is twofold: understanding the major difficulties of the aggregate economy such as inflation, business cycles, and slowing productivity growth; and to facilitate the evaluation of policies to influence those behaviors. In the existing publications on results from the National Model, the structure of the model is described in a page or two, doing no more than supplying a flavor for the scope of the model. This paper goes to the next stage in describing the content and structure of the model for those readers with some previous exposure to the results of the National Model research. The discussion starts with the overall architecture, then goes through the major connections among the sectors of the model, and concludes with one example of more detailed structure: the interrelations among selected decisions in the corporate sector of the model.

230. Gustafsson, Leif with Miroslaw Wiechowski,"Experiences in Teaching System Dynamics"

Type:
Document
Date Created:
1984
Collection:
System Dynamic Society Records
Collecting Area:
University Archives
Collection ID:
ua435
Parent Record(s):
dcf80aca09fd0af264c0472357441115, 23d738ba88f8333bc39725f9cb5bd0b8, and 6e5cbea1fd05527880f389afd8fb85d1
Thumbnail Path Ss:
/downloads/n009wk24g?file=thumbnail
System Modified Dtsi:
2020-01-02T18:37:49Z
Description:
The scope of this paper is to present our views on teaching System Dynamics and Dynamo in our courses in System Analysis at Uppsala University. We treat the pedagogical aspects as well as the hardware and software system we built around Dynamo. A large part of this article is devoted to ideas and constructive criticism of System Dynamics and Dynamo which we have acquired from our experiences in education and research.

231. Homer, Jack B.,"Worker Burnout: A Dynamic Model with Implications for Prevention and Control"

Type:
Document
Date Created:
1984
Collection:
System Dynamic Society Records
Collecting Area:
University Archives
Collection ID:
ua435
Parent Record(s):
dcf80aca09fd0af264c0472357441115, 23d738ba88f8333bc39725f9cb5bd0b8, and 6e5cbea1fd05527880f389afd8fb85d1
Thumbnail Path Ss:
/downloads/5m60r912g?file=thumbnail
System Modified Dtsi:
2020-01-02T18:37:50Z
Description:
This paper examines the dynamics of “worker burnout”, the process in which a hard-working individual becomes increasingly exhausted, frustrated, and unproductive. The author’s own two-year experience with repeated cycles of burnout is qualitatively reproduced by a small system dynamics model which portrays the underlying psychology of “workaholism”. Model tests demonstrate that the limit cycle seen in the base run can be stabilized through techniques which diminish work related stress or enhance relaxation. These stabilizing techniques also serve to raise overall productivity, since they support a higher level of energy and more working hours on average. One important policy lever is the maximum workweek or “work limit”; an “optimal work limit” at which overall productivity is at its peak is shown to exist within a region of stability where burnout is avoided. The paper concludes with a strategy for preventing burnout which emphasizes the individual’s responsibility for understanding the self-inflicted nature of this problem and pursuing an effective course of stability.

232. Jensen, Klaus Skovbo with Jesper Skavin, Erik Mosekilde, Christian Binder and Stig Pramming,"Simulating the Absorption of Insulin from a Subcutaneous Depot"

Type:
Document
Date Created:
1984
Collection:
System Dynamic Society Records
Collecting Area:
University Archives
Collection ID:
ua435
Parent Record(s):
dcf80aca09fd0af264c0472357441115, 23d738ba88f8333bc39725f9cb5bd0b8, and 6e5cbea1fd05527880f389afd8fb85d1
Thumbnail Path Ss:
/downloads/n296xg780?file=thumbnail
System Modified Dtsi:
2020-01-02T18:37:51Z
Description:
The System Dynamics model described in this paper presents a new approach to the mechanisms of subcutaneous absorption of dissolved insulin. Experimental investigations have shown that the apparent absorption constant varies in time, and that this variation depends both on the volume and the concentration of the injected insulin. Our model assumes that insulin is present in the subcutaneous depot in three forms: (i) a dimeric form, (ii) a hexameric form, and (iii) an immobile form in which the molecules are bound in the tissue. The model describes how diffusion and absorption gradually reduce the insulin concentrations and thereby shift the balance between three forms according to usual laws of chemical kinetics. By assuming that only dimeric molecules can penetrate the capillary wall, we have found that the model can fully account for the observed variations in the absorption rate. At the same time the model can be used to determine at least 5 parameters characterizing the involved processes: the diffusion constant for insulin in the subcutaneous tissue, the absorption constant for dimeric insulin, the equilibrium constant for the dimeric/hexameric polymerization process, the binding capacity for the insulin in the tissue, and the average life time for insulin in bound state. Combined with a simplified model of the distribution and degradation of insulin in the body, the diffusion-absorption model has been used to simulate different insulin delivery schedules, i.e. a single major injection contra dosage with infusion pump. The model has shown that a pump repetition frequency of 1-2/hr can secure a sufficiently constant plasma insulin concentration.

233. Mohapatra, Pratap with Kailas C. Sahu and Madhab C. Bora,"A System Dynamic Study of Commodity Price Stabilization by Buffer Stock and its Effect on Industry Performance: A Case of Indian Tea"

Type:
Document
Date Created:
1984
Collection:
System Dynamic Society Records
Collecting Area:
University Archives
Collection ID:
ua435
Parent Record(s):
dcf80aca09fd0af264c0472357441115, 23d738ba88f8333bc39725f9cb5bd0b8, and 6e5cbea1fd05527880f389afd8fb85d1
Thumbnail Path Ss:
/downloads/tb09jq51b?file=thumbnail
System Modified Dtsi:
2020-01-02T18:37:52Z
Description:
Using System Dynamics as the primary tool of investigation, an attempt has been made in this paper to present (i) a general model of commodity price fluctuation, (ii) a price stabilization policy based on buffer stock, and (iii) the impact of this policy on the long term growth of the commodity industry. The model has been tested for the case of Indian Tea.Average unit cost of the commodity at the point of sale, operating profit margin desired by the sellers (computed on the basis of average quality of supply), actual inventory, and the average sales rate are considered as the chief determinants of the commodity price. Circular relationships among these variables have been considered to generate the price fluctuation over time. While testing the price stabilization policy, the model considers its operation phase. It is shown in this paper that such a price stabilization policy tremendously boosts the overall long term growth of the industry.

234. Mosekilde, Erik with Steen Rasmussen,"An Alternative, Simple Economic Long-Wave Model"

Type:
Document
Date Created:
1984
Collection:
System Dynamic Society Records
Collecting Area:
University Archives
Collection ID:
ua435
Parent Record(s):
dcf80aca09fd0af264c0472357441115, 23d738ba88f8333bc39725f9cb5bd0b8, and 6e5cbea1fd05527880f389afd8fb85d1
Thumbnail Path Ss:
/downloads/5712mq18x?file=thumbnail
System Modified Dtsi:
2020-01-02T18:37:53Z
Description:
The simple two-sector Kondratieff model developed by John Sterman has contributed significantly to our understanding of some of the basic mechanisms underlying the economic long wave. The dynamic hypothesis of this model is that the positive feed-back associated with the so-called self-ordering of capital reinforces and prolongs the characteristic expansions and contractions of the capital sector as it adjusts its capacity to the required production. It is assumed that this feed-back can be strong enough to produce a self-sustained oscillation (a limit cycle) with a period which is about twice as long as usual capital lifetimes. Concentrating on the ordering and production of capital, the Sterman model only depicts a relatively small fraction of our economic system. At least in its original version, the model doesn't deal with several of the basic phenomena involved in the verbal description of the economic long wave, as it is usually presented. There is no account of variations in employment, buying power or political attitudes, for instance, and changes in the rate of innovations are also outside the model boundary. We do not think that one can presently develop a complete and satisfactory model of the economic long wave. We have therefore adopted an alternative starting point by assuming that the alternating phases of economic expansion and stagnation arrise from the succession of technical-economic cultures each characterized by its own infrastructure, leading industrial sectors, typical production methods and main products. Even the geographical location of the dominant political-economic center may shift from wave to wave. This is Mensch's process of metamorphosis. Where the Sterman approach emphasizes the cyclic character of the wave, our model is meant to describe the qualitative changes through which one set of technologies replaces the next. In our model, the economic system has no equilibrium point to oscillate around. As long as technology develops and new discoveries are made, the potential for economic activity continues to grow. A purpose of the model is therefore to show how randomly distributed discoveries can be bunched into waves of innovations with a relatively well defined period.

235. Morecroft , John D. W.,"The Feedback Viewpoint in Business Strategy for the 1980’s"

Type:
Document
Date Created:
1984
Collection:
System Dynamic Society Records
Collecting Area:
University Archives
Collection ID:
ua435
Parent Record(s):
dcf80aca09fd0af264c0472357441115, 23d738ba88f8333bc39725f9cb5bd0b8, and 6e5cbea1fd05527880f389afd8fb85d1
Thumbnail Path Ss:
/downloads/v692tq68m?file=thumbnail
System Modified Dtsi:
2020-01-02T18:37:54Z
Description:
This paper presents a flexible, model-based approach to strategic program design--the process of putting together consistent business programs and policies to support new strategic initiatives. The new approach combines ideas from administrative theory and feedback theory. Administrative theory reveals the organizational and diffusion processes that connect business programs and customers. Feedback theory reveals patterns (feedback loops) in the connections between programs and policies of a business and its market. This conceptual framework is applied to strategic program design in a two-phase analysis which is much more flexible than traditional system dynamics business modeling. Phase 1 is a descriptive analysis that explores business-market structure in terms of organizational and diffusion processes, showing where conflicts of responsibility, confused incentives, misinformation, and administrative inertia may degrade business performance. Phase 2 uses simulation modeling and the descriptive information from phase 1 to debate policy options and program design. The style of analysis is illustrated with business cases and applications projects.

236. Moxnes, Erling,"The Art of Causal Loop Diagramming"

Type:
Document
Date Created:
1984
Collection:
System Dynamic Society Records
Collecting Area:
University Archives
Collection ID:
ua435
Parent Record(s):
dcf80aca09fd0af264c0472357441115, 23d738ba88f8333bc39725f9cb5bd0b8, and 6e5cbea1fd05527880f389afd8fb85d1
Thumbnail Path Ss:
/downloads/00000h381?file=thumbnail
System Modified Dtsi:
2020-01-02T18:37:55Z
Description:
How should a causal loop diagram be drawn to explain structure as clearly as possible? Two basic rules are formulated: Feedback-loops should be drawn with loop-form, and influence should be unidirectional through each variable. An example shows that application of the two rules leads to enhanced clarity. Artistic derivations from the two rules can be used to produce memorable figures. Current practice in causal loops diagramming indicates a potential for improvements.

237. Moxnes, Erling,"Separating Static and Dynamic Effects in an Oil Price Model"

Type:
Document
Date Created:
1984
Collection:
System Dynamic Society Records
Collecting Area:
University Archives
Collection ID:
ua435
Parent Record(s):
dcf80aca09fd0af264c0472357441115, 23d738ba88f8333bc39725f9cb5bd0b8, and 6e5cbea1fd05527880f389afd8fb85d1
Thumbnail Path Ss:
/downloads/gt54m563m?file=thumbnail
System Modified Dtsi:
2020-01-02T18:37:56Z
Description:
A static and a dynamic model of the oil market are compared. Three major differences appear in forecasts. The dynamic model fluctuates around the static mode equilibrium price. The dynamic model shows greater uncertainty in trend development. The dynamic model forecast overshoots the cost level of synthetic oil.

238. Paul, H. with Karen S. Eichman,"Capacity Adjustments in a Textile Division:Management Response to a System Dynamics Study"

Type:
Document
Date Created:
1984
Collection:
System Dynamic Society Records
Collecting Area:
University Archives
Collection ID:
ua435
Parent Record(s):
dcf80aca09fd0af264c0472357441115, 23d738ba88f8333bc39725f9cb5bd0b8, and 6e5cbea1fd05527880f389afd8fb85d1
Thumbnail Path Ss:
/downloads/z890sb87b?file=thumbnail
System Modified Dtsi:
2020-01-02T18:37:57Z
Description:
A division of a large textile company was chosen as the focus of a system dynamics study to determine how management would respond to any capacity adjustment problem. The company produces fabrics for household as well as industrial uses and the annual sales of the company are several billion dollars. The division under study produces yarn and piece dyed draperies, mattress tickings, and upholstery fabrics. The four major manufacturing processes in the division are spinning, yarn preparation, fabric formation and fabric dyeing and finishing. Although not aimed at any particular perceived problems, the study was undertaken with two purposes, firstly to develop a system dynamics model that would describe the performance of the division and secondly to use the mode to investigate the effects of demand changes on various capacity adjustment policies practiced in the division. The study includes interactions among a large number of factors in forecasting and inventory control, raw material supplies, employment, and production capacity. These factors related to some ten points and four processes of the division. Data and other information have been collected by questionnaires and interviews with management. The model has been tested for its validity in representing the actual operations. The model is now being used in testing some of the policies in response to change in customer order rate.

239. Pugh, Alexander L.,"A New Generation of DYNAMOs"

Type:
Document
Date Created:
1984
Collection:
System Dynamic Society Records
Collecting Area:
University Archives
Collection ID:
ua435
Parent Record(s):
dcf80aca09fd0af264c0472357441115, 23d738ba88f8333bc39725f9cb5bd0b8, and 6e5cbea1fd05527880f389afd8fb85d1
Thumbnail Path Ss:
/downloads/w0892v88m?file=thumbnail
System Modified Dtsi:
2020-01-02T18:37:58Z
Description:
The emergence of powerful personal computers and CAD/CAM machines offers a new opportunity for DYNAMO. Although users are generally satisfies with the language, a survey shows they want expanded simulation capabilities including single simulations, eigenvalue analysis, sensitivity analysis, and the optimization by multiple simulation and hill climbing. Novices want easier access to models and simulation. The modular version of DYNAMO now in development will meet these goals. It will break DYNAMO’s normal functions into separate programs that users can reassemble in different ways. For example, one compiler will translate both conventional models and games. The simulation controller will work with a regular rerun, a game, or a sensitivity analysis package. The report generator will display output from any of these packages. These modules will communicate through standard data files, which users can also access for other purposes such as statistical analysis.

240. Raghavendran, P. with Qifan Wang,"Energy Development and Economic Growth in India"

Type:
Document
Date Created:
1984
Collection:
System Dynamic Society Records
Collecting Area:
University Archives
Collection ID:
ua435
Parent Record(s):
dcf80aca09fd0af264c0472357441115, 23d738ba88f8333bc39725f9cb5bd0b8, and 6e5cbea1fd05527880f389afd8fb85d1
Thumbnail Path Ss:
/downloads/z603rg16c?file=thumbnail
System Modified Dtsi:
2020-01-02T18:37:59Z
Description:
A dynamic simulation model of the Indian economy has been developed which captures the important linkages between economic growth and the development of various forms of energy. Non-commercial forms of energy which supplied the bulk of total energy requirements of the economy so far have clearly reached their saturation limits. Capital costs for coal and petroleum increase with resource depletion. The cost of hydroelectricity increases as the cheaper and more accessible resources are exhausted. The costs of renewable energy sources such as solar, wind and biomass decrease with cumulative production due to technical progress. Such sources of energy become more important sources in the future though their current share of the total energy production is negligible. The thesis examines the dynamics of the transition to the new era as well as responses of the economy to energy shocks such as steep increases in international oil prices. It investigates the possibility of an interim crisis if the domestic energy industry is slow to develop or if the response of energy demand to rising energy prices is sluggish. Such a difficult transition may be marked by persistent import dependence, high energy prices and high outlays in the energy sectors that reduce the resources available to the non-energy sectors for consumption and growth. An aggregate production function utilizing capital, labour and energy as factor inputs has been utilized for the economy along with a neo-classical formulation for consumption and saving in the economy. The model generates the energy demand of the economy endogenously and incorporates the adaptation of energy intensity to rising real energy prices through more efficient new capital equipment as well as retrofits of inefficient equipment. The model has been calibrated using Indian data. Where parameters or assumptions are based on uncertain facts, sensitivity tests have been carried out. The effect of government policies such as taxation of energy or emphasis on conservation have been investigated.

241. Randers, Jørgen,"Prediction of Pulp Prices – A Review Two Years After"

Type:
Document
Date Created:
1984
Collection:
System Dynamic Society Records
Collecting Area:
University Archives
Collection ID:
ua435
Parent Record(s):
dcf80aca09fd0af264c0472357441115, 23d738ba88f8333bc39725f9cb5bd0b8, and 6e5cbea1fd05527880f389afd8fb85d1
Thumbnail Path Ss:
/downloads/q811m267d?file=thumbnail
System Modified Dtsi:
2020-01-02T18:38:00Z
Description:
During the summer of 1982 the author made predictions of wood pulp prices for the period 1982 to 1986. The predictions were part of a decision on whether to sell a large pulping plant in Norway. This paper presents the predictions and the basis on which they were made. Next, the predictions are compared with actual data for the period 1982 to 1984.

242. Rasmussen, Steen with Erik Mosekilde and John D. Sterman,"Bifurcations and Chaotic Behaviour in a Simple Model of the Economic Long Wave"

Type:
Document
Date Created:
1984
Collection:
System Dynamic Society Records
Collecting Area:
University Archives
Collection ID:
ua435
Parent Record(s):
dcf80aca09fd0af264c0472357441115, 23d738ba88f8333bc39725f9cb5bd0b8, and 6e5cbea1fd05527880f389afd8fb85d1
Thumbnail Path Ss:
/downloads/8336hk41z?file=thumbnail
System Modified Dtsi:
2020-01-02T18:38:01Z
Description:
This paper presents a total stability analysis of a simplified Kondratieff-wave model. The purpose is to show how such an analysis can be carried out and to illustrate the kind of information one obtains. For normal parameter values the Kondratieff wave model has a single unstable equilibrium point. Combined with non-linear constraints in the model's table-functions, this instability creates a characteristic limit cycle behavior. For other parameter values, however, the model is stable and generates damped oscillations instead of the limit cycle. For yet other combinations of parameters, the non-linear constraints yield to the instability, and sustained exponential growth or total collapse result. By means of linear stability analysis we first determine the conditions for the transition between a stable and an unstable equilibrium to take place. This transition is known as a Hopf-bifurcation. 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 non-linear functions fail to contain the system so that exponential run-away or collapse occur. A DYNAMO-program is then developed which calculates the Lyapunov exponents of the system during a simulation, and we discuss how these exponents can be used as a measure of the divergence or convergence of nearby trajectories. Finally, we illustrate how subsequent period doublings and chaotic behaviour can occur if the model is driven exogenously by a weak sine-wave, representing for instance the short term business cycle.

243. Richardson, George P.,"Loop Polarity, Loop Dominance, and the Concept of Dominant Polarity"

Type:
Document
Date Created:
1984
Collection:
System Dynamic Society Records
Collecting Area:
University Archives
Collection ID:
ua435
Parent Record(s):
dcf80aca09fd0af264c0472357441115, 23d738ba88f8333bc39725f9cb5bd0b8, and 6e5cbea1fd05527880f389afd8fb85d1
Thumbnail Path Ss:
/downloads/2n49tk08w?file=thumbnail
System Modified Dtsi:
2020-01-02T18:38:02Z
Description:
There is a conspicuous gap in the literature about feedback and circular causality between intuitive statements about shifts in loop dominance and precise statements about how to define and detect such important nonlinear phenomena. This paper provides a consistent, rigorous, and useful set of definitions of loop polarities, dominant polarity, shift in dominant polarity, and shift in loop dominance, and illustrates their application in a range of system dynamics models. Consistent with the usual intuitive definitions, the polarity of a first-order feedback loop involving a level x and a single inflow ẋ is defined to be the sign dẋ/dx. Loop polarity is shown to depend upon the sign of parameters not usually considered part of the loop itself. This expression of loop polarity is then applied to multi-loop first-order systems to define the polarity of such systems. All positive loops with gain less than one, such as economic multipliers, are shown to be multi-loop systems with dominant negative polarity. The shifts in loop dominance that occur in nonlinear systems arise naturally as changes in the sign of the dominant polarity. Examples applying the notion of dominant polarity reveal a useful geometric characterization of shifts in loop dominance in nonlinear first-order systems. The concepts developed in the paper are then applied to simple higher-order nonlinear feedback systems. The final application to a bifurcating system suggests that all bifurcations in continuous systems can be understood as consequences of shifts in loop dominance at equilibrium points.

244. Sedehi, Habib,"A Dynamic Model for the Planning of Human Resources"

Type:
Document
Date Created:
1984
Collection:
System Dynamic Society Records
Collecting Area:
University Archives
Collection ID:
ua435
Parent Record(s):
dcf80aca09fd0af264c0472357441115, 23d738ba88f8333bc39725f9cb5bd0b8, and 6e5cbea1fd05527880f389afd8fb85d1
Thumbnail Path Ss:
/downloads/xp68m070t?file=thumbnail
System Modified Dtsi:
2020-01-02T18:38:03Z
Description:
The methodology which this article deals with, is the fruit of the experience gathered thanks to the contributions of experts in the fields of programming, personnel and organisation. The willingness of such people has given rise to the instruments now available in the field of Industrial Dynamics. It is thus possible to design a methodology and simulation models which, with the help of a computer, offer an instrument which can answer the needs of those involved in the planning of human resources in a company environment. This model has so far been applied with satisfactory results in two technically different realities. At the present time, other applications are in progress which confirm the validity of this instrument.

245. Senge, Peter M.,"A Long-Wave Theory of Real Interest Rate Behavior"

Type:
Document
Date Created:
1984
Collection:
System Dynamic Society Records
Collecting Area:
University Archives
Collection ID:
ua435
Parent Record(s):
dcf80aca09fd0af264c0472357441115, 23d738ba88f8333bc39725f9cb5bd0b8, and 6e5cbea1fd05527880f389afd8fb85d1
Thumbnail Path Ss:
/downloads/rj430p323?file=thumbnail
System Modified Dtsi:
2020-01-02T18:38:04Z
Description:
Businessmen, bankers, private citizens, and government officials share deep concerns over the high values of interest rates in today’s economy. Of particular concern has been real interest rate, the rate of interest adjusted for inflation. Although nominal interest rates have followed a generally declining trend over the past year, this decline has generally lagged declining inflation and has failed to keep pace with the drop in inflation. This paper is the first of two on the problem of high real interest rates. It focuses on developing a theoretical framework for understanding the role played by real interest rates in the long wave. The second part of the study will focus on the effects of government deficits and alternative monetary policies. The primary purpose of this study is to show that the downturn of the long wave can cause rising real interest rates even with no government deficit or change in monetary policy.

246. Senge, Peter M.,"Systems Thinking and the New Management Style"

Type:
Document
Date Created:
1984
Collection:
System Dynamic Society Records
Collecting Area:
University Archives
Collection ID:
ua435
Parent Record(s):
dcf80aca09fd0af264c0472357441115, 23d738ba88f8333bc39725f9cb5bd0b8, and 6e5cbea1fd05527880f389afd8fb85d1
Thumbnail Path Ss:
/downloads/ws85b057v?file=thumbnail
System Modified Dtsi:
2020-01-02T18:38:05Z
Description:
This paper summarizes the purpose, design, and initial results of the New Management Style Project.

247. Serra, R. with H. Sedehi and S. Vassalo,"Theoretical Approach to Long Term Company Behavior"

Type:
Document
Date Created:
1984
Collection:
System Dynamic Society Records
Collecting Area:
University Archives
Collection ID:
ua435
Parent Record(s):
dcf80aca09fd0af264c0472357441115, 23d738ba88f8333bc39725f9cb5bd0b8, and 6e5cbea1fd05527880f389afd8fb85d1
Thumbnail Path Ss:
/downloads/wp989384h?file=thumbnail
System Modified Dtsi:
2020-01-02T18:38:06Z
Description:
In order to study the long term behaviour of complex systems, such as industrial enterprises, it is necessary to use reduced models with a limited number of variables. Here we investigate theoretically the relationship between these “mesoscopic” models and more detailed, “microscopic” models of the same physical systems. When the relevant variables evolve more slowly than the irrelevant degrees of freedom, a powerful projection technique is presented (Adiabatic Elimination Procedure). A pedagogical example is discussed, dealing with a large company in the field of computer science, which wants to increase its presence in a particular market segment by starting a cooperation with a small but aggressive company, already in that market segment.

248. Singh, N. with D. Prasad,"A System Dynamics Approach to the Analysis of Indian Cement Industry"

Type:
Document
Date Created:
1984
Collection:
System Dynamic Society Records
Collecting Area:
University Archives
Collection ID:
ua435
Parent Record(s):
dcf80aca09fd0af264c0472357441115, 23d738ba88f8333bc39725f9cb5bd0b8, and 6e5cbea1fd05527880f389afd8fb85d1
Thumbnail Path Ss:
/downloads/9w032k699?file=thumbnail
System Modified Dtsi:
2020-01-02T18:38:07Z
Description:
The production of cement pays the most important role in all the construction activities in the country. Due to rapid growth in the industrialisation and the development there is fast growing internal demand of cement. However, cement industry in India has not been able to cope up with the demand. Therefore, it is essential to study the demand and production aspects in order to evolve strategies to meet the demand. For this purpose, a System Dynamics model for cement production is developed. The production model is run for 16 years covering a period from 1974 to 1990 at three conditions, such as basic, optimistic and pessimistic. The different sensitivity runs are also carried out by changing the different parameters influencing the production. Different scenarios are generated and the gap between demand and production is analysed at different conditions. It is observed that this gap is closed under certain conditions.

249. Sterman, John D.,"An Integrated Theory of the Economic Long Wave"

Type:
Document
Date Created:
1984
Collection:
System Dynamic Society Records
Collecting Area:
University Archives
Collection ID:
ua435
Parent Record(s):
dcf80aca09fd0af264c0472357441115, 23d738ba88f8333bc39725f9cb5bd0b8, and 6e5cbea1fd05527880f389afd8fb85d1
Thumbnail Path Ss:
/downloads/sj139k01r?file=thumbnail
System Modified Dtsi:
2020-01-02T18:38:08Z
Description:
The 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 development of an endogenous, dynamic theory of the economic long wave. The model has now reached the point where an integrated theory of the long wave can be described. The theory incorporates many of he partial theories that have been proposed by others. Simulations of the model are presented to show the wide range of empirical evidence accounted for by the model. In particular, the theory suggests the long wave arises from the interaction of two fundamental facets of modern industrial economies. First, the existence of physical lags in the economy, limited information available to decisionmakers, and bounded rationality in economic decisionmaking creates the potential for inherently oscillatory behavior. Second, a wide range of self-reinforcing processes exist which destabilize the inherently oscillatory tendencies of our economy, leading to the long wave. These processes involve many sectors of the economy including capital investment, labor markets and workforce participation, real interest rates, inflation, debt, savings and consumption, and international trade. The paper discusses the relative strengths of these mechanisms and the amplification of the long wave through their interactions. The linkages of the long wave theory to innovation, technological progress, and political value change are discussed.

250. Wang, Qifan,"Using the Liapunov Principles in the Analysis of System Dynamics Models"

Type:
Document
Date Created:
1984
Collection:
System Dynamic Society Records
Collecting Area:
University Archives
Collection ID:
ua435
Parent Record(s):
dcf80aca09fd0af264c0472357441115, 23d738ba88f8333bc39725f9cb5bd0b8, and 6e5cbea1fd05527880f389afd8fb85d1
Thumbnail Path Ss:
/downloads/xg94j6613?file=thumbnail
System Modified Dtsi:
2020-01-02T18:38:09Z
Description:
A new analytic method combining Piapunov's methods and eigenvalue analysis approach, a technique for identifying dominant loop analysis contributed by Nathan B. Forrester, is developed to search for the feasible and most policies in system dynamics models. The paper briefly introduces the Liapunov methods of stability analysis (the first and second methods of Liapunov). Liapunov's first method, under certain conditions, enables one to arrive at conclusions about a nonlinear system (original system) by studying the behavior of linearized systems. Liapunov's second method gives sufficient conditions for the stability of linear systems. Criteria of Liapunov's first method and Krasovskii's method, an extended method of Liapunov's second method, are both applied in the analytic method. The structure of the method and how the method is used are described. It is expected that the analytic method will become a new approach to testing models in order to seek the best feasible policies automatically in system dynamics.