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- Type:
- Document
- Date Created:
- 1994
- Collection:
- System Dynamic Society Records
- Collecting Area:
- University Archives
- Collection ID:
- ua435
- Parent Record(s):
- 23d738ba88f8333bc39725f9cb5bd0b8, c060552994c1527f70693734935660f1, and fe35db792b573af835d96e6eba4759cd
- Description:
- Most system dynamicists have used a simple shower model to explain feedback and to introduce cyclical dynamics behavior characteristic of a balancing loop. The damped system's temperature is relatively easy to manage. But what if we assume the existing of the two showers sharing the same limited supply of hot water? It turns out- as one might expect - that it is much harder to control the water temperature because a person managing one shower is unaware of the other shower or it's occupant, yet must react to the aggregate temperature outcome resulting from a joint 'management' effort. We discuss how a single two-shower model can provide a useful metaphor for a wide range of real managerial problems. The model is used to illustrate the causes and consequences of interdependence in processes of resources allocation, competition within and among organization.
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- Type:
- Document
- Date Created:
- 1994
- Collection:
- System Dynamic Society Records
- Collecting Area:
- University Archives
- Collection ID:
- ua435
- Parent Record(s):
- 23d738ba88f8333bc39725f9cb5bd0b8, c060552994c1527f70693734935660f1, and fe35db792b573af835d96e6eba4759cd
- Description:
- A system dynamics model is presented to analyze fiscal and monetary policies. The model describes an economy which suffers from infrastructure shortage. Further, government is responsible for the development of infrastructure. The model demonstrates the contradiction between fiscal policy and monetary policy in offsetting the rise of inflation. The contradiction can be addressed in terms of time horizon—from a short-run and a long-run perspective. In order to control inflation, a monetary policy may suggest a reduction in the rate of increase in money supply. This can be done by restricting dudget deficit based on inflation. In contrast, a fiscal policy may suggest that in order to control inflation, aggregate supply (of goods) must be increased. An increase in aggregate supply requires infrastructure; thus, budget deficit expansions is unavoidable. The model also shows that a policy which restricts new project initiation based on government budget availability causes a lower inflation rate, particularly in the long run, without decreasing the production growth rate.
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- Type:
- Document
- Date Created:
- 1994
- Collection:
- System Dynamic Society Records
- Collecting Area:
- University Archives
- Collection ID:
- ua435
- Parent Record(s):
- 23d738ba88f8333bc39725f9cb5bd0b8, c060552994c1527f70693734935660f1, and fe35db792b573af835d96e6eba4759cd
- Description:
- The work described in this paper was carried out as part of a study into occupational health and safety information systems, and the simulation package used was Powersim. Systems thinking and practice are tools which can contribute greatly to better safety management (Waring 1990). The paper presents a generic model to illustrate the life cycle of a workplace hazard, from its conception to its final control. The greater the number of uncontrolled hazards in a working environment at any one time, the greater the likelihood of accidents being generated. The rate at which hazards can be identified and controlled will have a great bearing on the overall safety of the workplace. The exclusive use of a reactive approach to hazard control in the following system models proves not to be sufficient in substantially controlling hazards.
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- Type:
- Document
- Date Created:
- 1994
- Collection:
- System Dynamic Society Records
- Collecting Area:
- University Archives
- Collection ID:
- ua435
- Parent Record(s):
- 23d738ba88f8333bc39725f9cb5bd0b8, c060552994c1527f70693734935660f1, and fe35db792b573af835d96e6eba4759cd
- Description:
- System dynamics modeling is used in many disciplines to examine the various ways in which dynamic system function. At the University of Stirling system dynamics has been used since 1978 to model environment processes and contribute to the management of environmental problems. These two aspects of environmental research haven been reinforced by new developments in computing technology and by greater awareness of the importance of environmental problems by both politicians and lay people. At present, however, system dynamicists have remained aloof from many developments in computing technology and it will be argued that that could be failing to make a major contribution to the understanding and resolution of environmental problems. The main thrust of this paper is to argue that system dynamics needs to be extended into a more general framework so that detailed investigations of major environmental problems can be undertaken. In particular it is suggested that system dynamics needs to develop dynamic models to interact with several areas of information technology, especially database, quantitative methods, geographical information system (GIS) and experts systems in order to contribute further to the understanding and management of environmental problems. This argument is illustrated with a description of a prototype, integrated and general environmental research and management system (GERMS) developed explicitly to address the problem of modeling and management water quality in the forth estuary, Scotland. Some of the results of this research and its implications for environmental management are discussed. It is suggested that further development along these lines could be made to ensure that system dynamics make an even greater contribution to try to resolve many of the environmental problems which surrounds us.
-
- Type:
- Document
- Date Created:
- 1994
- Collection:
- System Dynamic Society Records
- Collecting Area:
- University Archives
- Collection ID:
- ua435
- Parent Record(s):
- 23d738ba88f8333bc39725f9cb5bd0b8, c060552994c1527f70693734935660f1, and fe35db792b573af835d96e6eba4759cd
- Description:
- Management games are very powerful teaching and training devices which however, sometimes suffer from a direct and usually one-to-one interaction between player and the model. The paper presents a management simulator for decisions occurring during the innovation process. Several groups of players represent the boards of directors of virtual enterprises that compete with each other. The computer model serves only as a clearing device to coordinate the decision consequences on the supply side and on customer demand. Technically, the game is based on a simulation model written in Professional Dynamo. It has an interface for the preparation of the simulation results and the communication with the players, that was realizes using Microsoft Excel. A simulation model for generating data for management gaming must comprise a realistic structure and stable policy rules. The players should be able to use their professional knowledge and their business experience. The computer-model in the paper represents a microworld for testing different strategies, to experience different forms of behavior, and for improving the understanding og the consequences of decision making in a dynamic environment.
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- Type:
- Document
- Date Created:
- 1994
- Collection:
- System Dynamic Society Records
- Collecting Area:
- University Archives
- Collection ID:
- ua435
- Parent Record(s):
- 23d738ba88f8333bc39725f9cb5bd0b8, c060552994c1527f70693734935660f1, and fe35db792b573af835d96e6eba4759cd
- Description:
- In the conventional view, planning is a process in which various goals for the future are set and action programs are formulated to achieve those goals. Future goals and appropriate plans are formulated based on analysis of environment forces and audits of internal conditions or strengthens and weaknesses. Then, plans are implemented to achieve the goals. But, in the System Dynamics view planning is a decisive formulation of policies or decision making riles which will enable the system to evolve from its present state to the desired one. The design of decision making rules is within a framework of feedback and based on consideration of the fact that new conditions will lead to new decisions and actions as the based on consideration of the fact that new condition will lead to new decisions and actions as the system moves towards it's desired states. The implication of these two views in planning is discussed with respect to management of a company within a growing market.
-
- Type:
- Document
- Date Created:
- 1994
- Collection:
- System Dynamic Society Records
- Collecting Area:
- University Archives
- Collection ID:
- ua435
- Parent Record(s):
- 23d738ba88f8333bc39725f9cb5bd0b8, c060552994c1527f70693734935660f1, and fe35db792b573af835d96e6eba4759cd
- Description:
- We have developed several models linking land use changes and transportation for different regions with populations ranging from 100,000 to 2,000,000. The models are uses to long-term planning for land use, transportation, and air quality. The level of detail desired by clients requires that the models have a high degree of spatial disaggregation, typically several hundred zones. The spatial detail is a strength of the models, but it is achieved at cost. Model development is time-consuming and expensive. Even on the fastest microcomputers, model run time is measured in hours. Testing new models structures and making structural enhancement is slow and difficult. The complexity of the models inhibits experimentation and learning by clients. Simpler models are needed to aid in prototype development and in communication and training. We compared results of policy simulations from regional models with three levels of spatial disaggregation. The most detailed models are as described above. For a highly-aggregated example, we developed a system dynamics model with two concentric rings using STELLA software. Finally we evaluate two simplified grid models with intermediate levels of spatial disaggregation models. The STELLA model is able to demonstrate some of the policy results, and is an excellent tool for model development. In some ways the grid model combine the worst of both worlds. They are neither simple nor fully detailed. The detailed models exhibit the most rich behaviors. We are developing techniques to move from STELLA structures directly to the more disaggregated model
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- Type:
- Document
- Date Created:
- 1994
- Collection:
- System Dynamic Society Records
- Collecting Area:
- University Archives
- Collection ID:
- ua435
- Parent Record(s):
- 23d738ba88f8333bc39725f9cb5bd0b8, c060552994c1527f70693734935660f1, and fe35db792b573af835d96e6eba4759cd
- Description:
- The purpose of this paper is to improve the results obtained by Fernandez and Mantel (1989), referred to the price control inconvenience in the application of a stabilization plan for Argentina's hyperinflation in the Eighties. For the model's correct translation is checked by replications of the original experiments. Secondly, an intuitive policy suggested by the shape of the original experiments, that proposes a timely starting of the original price control policy is tested, achieving better results. Finally, an optimization process, currently available in Vensim programme, penalizes, on the one hand, the oscillations which are shown by the path that the instantaneous inflation follows to reach the equilibrium inflation rate; on the other hand, the slowness to reach that equilibrium point. Vensim's advise nearly matches previous intuituve timing for starting to control prices.
-
- Type:
- Document
- Date Created:
- 1994
- Collection:
- System Dynamic Society Records
- Collecting Area:
- University Archives
- Collection ID:
- ua435
- Parent Record(s):
- 23d738ba88f8333bc39725f9cb5bd0b8, c060552994c1527f70693734935660f1, and fe35db792b573af835d96e6eba4759cd
- Description:
- Traditional models of innovations diffusion ignore the complexity and dynamics underlying the process of diffusion. Usually these models consider only a single management decisions variable, e.g., price of advertising, but they assume these variables to be exogenous elements. The models seek for strategies to optimize the cumulative profits without consideration of the highly independent influencing elements. Their aim is normative decision support, but they use models, which do not appropriately represent the structural fundamentals of the problem. The use of the system dynamics methodology allows the development of more complex and detailed models to investigate the process of innovations diffusion. These models can enhance the insight in the problem structure and increase understanding of the complexity, the dynamics and the impact of management decisions. But the development of adequate system dynamics models requires expert knowledge and plenty of time. The paper presents a knowledge-based approach to System Dynamics Modeling to shorten the process model building and to make the knowledge about innovation management available for many users. It consists of two parts: A knowledge based system with the traditional components for dialog, explanation, knowledge representation and inference is used to configure System Dynamics Models, and a modelbase of different modules that represent the generic structures of typical innovation management problems. The knowledge about the innovation problems is included in the different modules and in the knowledge base of the knowledge-based system. In dialog with the user the knowledge based system analyses the problem structure, chooses the relevant modules and finally configures the model that then can be used for further analysis through the problem owner.
-
- Type:
- Document
- Date Created:
- 1994
- Collection:
- System Dynamic Society Records
- Collecting Area:
- University Archives
- Collection ID:
- ua435
- Parent Record(s):
- 23d738ba88f8333bc39725f9cb5bd0b8, c060552994c1527f70693734935660f1, and fe35db792b573af835d96e6eba4759cd
- Description:
- Evaluating optimization model based decision support system is a complex task. Once an optimization model is built, one is not sure how to compare the effectiveness of two competing optimization models. One is also not sure how the model results will fare when they are actually implemented in practice. This paper lays out a procedure for evaluating optimization models in the framework of a system dynamics based game. Using the suggested procedure, a number of optimization model based system are evaluated. Investigations are then carried out on the effect of such decisions support system on the performance of the game participants. The proposed procedure opens up the possibilities of developing realistic and credible optimizations models by testing them for their effectiveness in the context of a specific problem situation.