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- Type:
- Document
- Date Created:
- 1983
- Collection:
- System Dynamic Society Records
- Collecting Area:
- University Archives
- Collection ID:
- ua435
- Parent Record(s):
- 23d738ba88f8333bc39725f9cb5bd0b8, cf82ceba47eedd73f41b00918de16477, and b0aa2a699b54f0d19f6a9d93bdbcfa18
- Description:
- This paper deals with the optimality and efficiency of antithetic random variates in estimating output parameters of general complex stochastic systems (e.g., reliability systems, stochastic networks, queues, etc.) with elements linked by multivariate dependence. It is shown that antithetic random variates are much more accurate than the crude Monte Carlo method, requires less CPU time and can be efficiently used by simulation practitions. The validity of the theory is demonstrated by simulation queueings and reliability systems and stochastic networks of different complexity.
-
- Type:
- Document
- Date Created:
- 1983
- Collection:
- System Dynamic Society Records
- Collecting Area:
- University Archives
- Collection ID:
- ua435
- Parent Record(s):
- 23d738ba88f8333bc39725f9cb5bd0b8, cf82ceba47eedd73f41b00918de16477, and b0aa2a699b54f0d19f6a9d93bdbcfa18
- Description:
- It is important to begin any modeling attempt by determining the primary objectives of the decision makers in the field. In forestry there are two interests: production of multiple resources and profit (or cost). Conventional methods of analysis are incapable of handling the two foci adequately; one is always subsumed in the other. The DYNAST model, with the addition of an economic algorithm, provides a means of analyzing the system from both viewpoints without forcing one to dominate the other. This balance is achieved through using capital budgeting techniques such as net present value to represent both the multiple use and profit aspects of money. The economic algorithm can be used to analyze money as one of a host of multiple benefits in comparing management options, or as a method of estimating profitability independent of the context of the model. This latter application makes the algorithm potentially useful in many modeling contexts simulating business investment decisions.
-
- Type:
- Document
- Date Created:
- 1983
- Collection:
- System Dynamic Society Records
- Collecting Area:
- University Archives
- Collection ID:
- ua435
- Parent Record(s):
- 23d738ba88f8333bc39725f9cb5bd0b8, cf82ceba47eedd73f41b00918de16477, and b0aa2a699b54f0d19f6a9d93bdbcfa18
- Description:
- The question at issue before this session is whether the system dynamics paradigm should be expanded to include selected issues from the broader field of systems theory. Although some limited expansion in this direction is desirable and probably inevitable, I will argue that it is not the most fruitful direction for broadening our paradigm to take.
-
- Type:
- Document
- Date Created:
- 1983
- Collection:
- System Dynamic Society Records
- Collecting Area:
- University Archives
- Collection ID:
- ua435
- Parent Record(s):
- 23d738ba88f8333bc39725f9cb5bd0b8, cf82ceba47eedd73f41b00918de16477, and b0aa2a699b54f0d19f6a9d93bdbcfa18
- Description:
- Three types of changes are proposed as being generic to an organization's adaptation to its environment. They are: (a) Change in pattern, (b) Change in Structure, and (c ) Change of elements. The typology is based on Atkin's mathematical structure. The typology attempts to characterize change on the basis of what is changed and what is held constant, instead of on the basis of the effects of the change is done in a number of current typologies. The three types of changes are described and discussed with reference to a problem faced by a diverse and fragmented academic department. The typology provides a framework for a strategist to delineate alternative ways in which an organization can be changed to adapt to its environment, to evaluate the pros and cons of each alternative, and to make a choice.
-
- Type:
- Document
- Date Created:
- 1983
- Collection:
- System Dynamic Society Records
- Collecting Area:
- University Archives
- Collection ID:
- ua435
- Parent Record(s):
- 23d738ba88f8333bc39725f9cb5bd0b8, cf82ceba47eedd73f41b00918de16477, and b0aa2a699b54f0d19f6a9d93bdbcfa18
- Description:
- The relationship between the dynamic behavior of individual components of a large system and the overall behavior of the large system has rarely been analyzed in the system dynamics literature. The usual approach is to treat the large system (e.g. a national economy) as a lumped-parameter version of the component systems. A number of examples from physical systems (plasma instabilities, fluid and chemical-reaction waves) suggest that the lumped parameter approach is not always adequate as a representation of the dynamics of systems or as a cogent explanation of the behavior of aggregate systems. In particular, new collective modes of behavior are found when the stochastic distribution of micro-level systems over internal states is considered. The proper treatment of the aggregation of micro-systems can reveal novel dynamic behavior modes and can indicate under what conditions these modes may become active. The explicit treatment of the aggregation of micro-systems can also clarify the relationships between the structure and parameters of the micro-systems and those of a lumped-parameter representation of the macro-system, thus giving some precision to arguments based on macro-level models of interacting micro-level systems. One approach to the study of the collective behavior of elementary systems uses the concept of a “dissipative structure” as developed by Prigogine and colleagues over the past fifteen years. This paper continues the work of a previous paper on the subject by applying the Master Equation Formulation to several generic models of first and second order (including delays, sigmoid growth, predator-prey and other oscillatory systems). Conditions under which novel aggregate behavior may be expected to appear are determined. Some linear systems do not present any novelty in the theory, most attention is focused on non-linear examples.
-
- Type:
- Document
- Date Created:
- 1983
- Collection:
- System Dynamic Society Records
- Collecting Area:
- University Archives
- Collection ID:
- ua435
- Parent Record(s):
- 23d738ba88f8333bc39725f9cb5bd0b8, cf82ceba47eedd73f41b00918de16477, and b0aa2a699b54f0d19f6a9d93bdbcfa18
- Description:
- Peter Allan’s Intra-urban model is a very appealing application of bifurcation theory for simulating the evolution of an urban spatial structure. It is actually a spatial dynamic model, and it brings together many well-known empirical regularities and well-established theoretic proposals, as logistic growth, economic base theory, distance-decay functions, urban ecology and actor’s behaviour in an urban context. Until now, this model has only been tested in fictitious urban situations and did prove its ability to simulate various urban evolutions, especially of the north-american type. However, it needs to be tested in real-world situations. Main questions are: Until which extent the same set of equations is able to simulate various observed urban evolution; and how many changes in parameters’ values are necessary to reproduce observed evolution in different towns. So we tried to apply the model to a sample of fench metropolitan areas.
-
- Type:
- Document
- Date Created:
- 1983
- Collection:
- System Dynamic Society Records
- Collecting Area:
- University Archives
- Collection ID:
- ua435
- Parent Record(s):
- 23d738ba88f8333bc39725f9cb5bd0b8, cf82ceba47eedd73f41b00918de16477, and b0aa2a699b54f0d19f6a9d93bdbcfa18
- Description:
- In our thesis we show that the advantage of using D.S. methods for the modelling of economic processes. Some practitioners of econometry have already seen the D.S. as a preliminary to the formalisation of model economy subject. In a recent article, we showed how the optimum of production may sometimes not be given primacy in a sector, in a grouping of firms , or a firm and it is sometimes profitable to analyse the weaknesses which can be found in a whole industrial network in order to understand the lack of competitiveness in national products. The aim of this paper is to apply methods of the system dynamics to the analysis and modelling of the process of pricing certain products in the French timber industry.
-
- Type:
- Document
- Date Created:
- 1983
- Collection:
- System Dynamic Society Records
- Collecting Area:
- University Archives
- Collection ID:
- ua435
- Parent Record(s):
- 23d738ba88f8333bc39725f9cb5bd0b8, cf82ceba47eedd73f41b00918de16477, and b0aa2a699b54f0d19f6a9d93bdbcfa18
- Description:
- The Dutch Disease is the name of macroeconomic effects of natural gas income spending in the Netherlands in the 1970’s. Spending resulted in increases in the national wage level, problems for exporting industries and economic instability. A system dynamics model of the Norwegian economy replicates the Dutch Disease for the case of oil income spending in Norway. The underlying causes of the Dutch Disease are discussed, and policies to cure problems are investigated. Subsidies to exporting industries have little effect on the problems in this sector of the economy, and they exacerbate economic instability. A wage freeze has some positive effects on the Dutch Disease. However, this policy causes other problems. An attempt to increase labor mobility has some positive effects. The most effective policy has been found to be a smooth and slow increase in oil income spending, the original cause of the disease. All problems cannot be avoided, and inevitable problems must be balanced against the benefits of oil income spending.
-
- Type:
- Document
- Date Created:
- 1983
- Collection:
- System Dynamic Society Records
- Collecting Area:
- University Archives
- Collection ID:
- ua435
- Parent Record(s):
- 23d738ba88f8333bc39725f9cb5bd0b8, cf82ceba47eedd73f41b00918de16477, and b0aa2a699b54f0d19f6a9d93bdbcfa18
- Description:
- Self-organization denotes a class of instabilities in which a system spontaneously generates structure, diversity and/or specialization. From a thermodynamic point of view, transitions of this kind, which proceed against the general tendency for relaxation towards an unstructured equilibrium, can occur in energetically open systems and under far-from-equilibrium conditions. The exergy required to build up and maintain a non-equilibrium (so-called dissipative) structure can here be extracted from the continuous supply of energy (and/or resources). The interest of self-organizing systems originates in the work on irreversible thermodynamics performed primarily by the so-called Brussels school. According to this school, developments in biological, ecological, and social systems which involve qualitative change, diversification or increased complexity are also to be viewed as self-organizing processes. This applies for instance to the build-up of genetic information, the appearance of new species in an ecological system, the introduction of new techniques in a social system, the adoption of new scientific paradigms, and the penetration of new products. In the present paper we analyse the basic ideas of self-organization in terms of concepts familiar to System Dynamics practitioners. Through a series of relatively simple models it is shown how System Dynamics can be used as an efficient tool for modeling self-organizing systems. As a particular example we consider the evolution of cooperative structures (RNA molecules with their associated enzymes) in a prebiotic system.
-
- Type:
- Document
- Date Created:
- 1983
- Collection:
- System Dynamic Society Records
- Collecting Area:
- University Archives
- Collection ID:
- ua435
- Parent Record(s):
- 23d738ba88f8333bc39725f9cb5bd0b8, cf82ceba47eedd73f41b00918de16477, and b0aa2a699b54f0d19f6a9d93bdbcfa18
- Description:
- Practitioners of Management Science have repeatedly confronted the problem of assessing the impact of variables such as job satisfaction and career aspirations on the performance of organizations. This problem is most acutely felt by service firms where the quality of 'output' is directly determined by factors that, because intangible, are difficult to define and control. In this article the authors use the methodology of System Dynamics to model the behavior of a professional CPA firm. The impact of qualitative variables on the behavior of a typical office is explicitly analyzed and translated into 'hard' economic terms. The results make some interesting observations about the key factors influencing long-term behavior in a people-intensive system, particularly in terms of the relationship between actions at senior levels and consequences further down the system. For instance, the way managers and partners allocate their time between apparently 'competing' activities is a critical factor influencing not only short-term behavior at junior levels but also the process whereby long-term judgments are made about the organization. Each activity has a different return profile (particularly with respect to time) and a different set of associated risks. The study contributes to an understanding of how critical aspects of human resource planning such as management time allocation contribute to the broader, strategic direction of the firm.