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- Type:
- Document
- Date Created:
- 1995
- Collection:
- System Dynamic Society Records
- Collecting Area:
- University Archives
- Collection ID:
- ua435
- Parent Record(s):
- b83f2ce2912343b559f967dd985da515, 23d738ba88f8333bc39725f9cb5bd0b8, and 12420ec6bd5f758d2b4dea59aabd75a9
- Description:
- This essay provides a mathematical definition of the causal diagram and the flow diagram. It also elaborates the idea that the level-rates system is the key to solving the problem in System Dynamics. The essay will make a combination to the knowledge of model conceptualization and formulation and improve modeling practice.
-
- Type:
- Document
- Date Created:
- 1995
- Collection:
- System Dynamic Society Records
- Collecting Area:
- University Archives
- Collection ID:
- ua435
- Parent Record(s):
- b83f2ce2912343b559f967dd985da515, 23d738ba88f8333bc39725f9cb5bd0b8, and 12420ec6bd5f758d2b4dea59aabd75a9
- Description:
- Over the past several years, faculty at Trinity College have engaged in a number of project to develop their modelling skills, to incorporate modelling into established courses, to use modelling as foundation for new interdisciplinary courses, to develop modelling skills in our students, and to reach out to pre-college educators to support their development in similar directions. Our more successful experiments share at least one common element: They begin with a conceptually simple theme, and then systematically and progressively build complexity, realism, and connections to more diverse fields, around the central theme. Such structure allows the development of entire course on foundation of system dynamic modelling, rather than episodic modeling exercises common in many other educational settings. An additional benefit is that several of our experiments have begun to provide unexpectedly reinforcing support for other experiments. In this contribution we briefly describe these recent experiments which, together, can provide significant support to pre-college educators and educational systems seeking to enhance the system dynamic components of the curricula. Our efforts to provide initial modeling training for teachers rested upon a graded sequence of modeling exercises progressively developing more complex, realistic models of human population growth, then connecting the population dynamics to the other topics of interest to the teachers. Recognizing this strategy as an effective one for building modeling skills, we have used it as conceptual foundation for an interactive computer-based tutorial for the building of STELLA II models. This Tutorial can support independent learning of this language, serve as a self-paced adjunct to more traditional modeling instruction, or provide a means to convey basic skills and concepts to students using models within a particular course. Following these successes, we developed in 1993 an interdisciplinary (primary biology, history, and economic) college course (Plagues and People) in which a simple model disease transmission served as the core model with which to develop diverse scenarios addressing historical, social, and economical factors of disease in setting ranging from ancient Greece to the modern case of AIDS. A more recent course was based on initially simple models of human population growth and explored how human population dynamics have influenced migration and settlement patterns, was and conquest, resource exploitation, disease, and development pf social and economic systems.
-
- Type:
- Document
- Date Created:
- 1995
- Collection:
- System Dynamic Society Records
- Collecting Area:
- University Archives
- Collection ID:
- ua435
- Parent Record(s):
- b83f2ce2912343b559f967dd985da515, 23d738ba88f8333bc39725f9cb5bd0b8, and 12420ec6bd5f758d2b4dea59aabd75a9
- Description:
- The purpose of this paper is to present the characteristic, functions and program structure of system dynamics simulation - DYNAMOX that can be used on XENIX operation system. This software is mainly composed of six parts. (1) dispatch management module, (2) parameter modify module, (3) model compiler module, (4) model run module, (5) database access module, (6) model library access module. In order to illustrate out software, we give a simple example about the organism relationship model between deers, beasts and grass in Kaibab plateau.
-
- Type:
- Document
- Date Created:
- 1995
- Collection:
- System Dynamic Society Records
- Collecting Area:
- University Archives
- Collection ID:
- ua435
- Parent Record(s):
- b83f2ce2912343b559f967dd985da515, 23d738ba88f8333bc39725f9cb5bd0b8, and 12420ec6bd5f758d2b4dea59aabd75a9
- Description:
- The process of research and development (R&D) in the pharmaceutical industry has become increasingly unproductive during the last few decades. One reason, among others, for this development is the diminishing level of performance reached by research technologies. In the following study the term 'performance' is limited to an output measurement which is reflected by the number of new drugs launched into the market by which therapeutic improvements can be realized. The purpose of this study is to analyze the decreasing performance of traditional technologies in order to partly explain the reduction in R&D productivity. Subsequently, the potential impact of new technologies upon research performance will be simulated by using System Dynamics. Broad-scale random screening is the main technological process traditionally used to discover chemical substances for new drugs. This study reveals the random screening can be adequately modelled by the statistical formula Poisson function. The function is used to calculate the probability of discovering new drugs. Empirical data from the German pharmaceutical industry from the 1950s onwards were out into the formula. The results show that the probability of discovering new drugs has decreased strongly by using random screening. Furthermore, the risk involved in research with random screening can be measured by Poisson distribution functions. In can be seen that risk has risen significantly since the 1950s. The Poisson formula also provides a formal framework for forecasting the impact of new technologies on the rate of drug recovery. The high potential performance of new biotechnologies, especially genetic engineering, could increase research success rates significantly. A System Dynamics model has been constructed in a prototype version to generate scenarios for future output rates. The high uncertainly in predicting research successes can be estimated by a best, a worst and an intermediate forecast based upon varying assumptions. The software application Vensim has been used for modelling and simulating. The model is partly based on hypothetical data and is, therefore, a first step towards forecasting the impact of genetic engineering on research performance in the pharmaceutical industry.
-
- Type:
- Document
- Date Created:
- 1995
- Collection:
- System Dynamic Society Records
- Collecting Area:
- University Archives
- Collection ID:
- ua435
- Parent Record(s):
- b83f2ce2912343b559f967dd985da515, 23d738ba88f8333bc39725f9cb5bd0b8, and 12420ec6bd5f758d2b4dea59aabd75a9
- Description:
- The assessment of and planning for agricultural system sustainability is a difficult task not adequately handled by conventional methods of farm management analysis. Sustainability is appropriately considered as multi-dimensioned phenomenon incorporating ecological, economic and sociological aspects. An holistic perspective is necessary to consider these dimensions. The inherent complexity of real world agricultural system implies an inductive, rather than deductive analytical approach. As an inductive modelling procedure, system dynamics is able to represent the underlying feedback processes that define those ecological economic processes relevant to an understanding of sustainability. Through such an understanding, the analyst is able to facilitate change towards the ultimate goal of holistic system sustainability. A case study model is developed to indicate the relevant modelling procedure and outline some guidelines for interpretation.
-
- Type:
- Document
- Date Created:
- 1995
- Collection:
- System Dynamic Society Records
- Collecting Area:
- University Archives
- Collection ID:
- ua435
- Parent Record(s):
- b83f2ce2912343b559f967dd985da515, 23d738ba88f8333bc39725f9cb5bd0b8, and 12420ec6bd5f758d2b4dea59aabd75a9
- Description:
- All socioeconomic systems are characterised by a complexity of interacting influence patterns that would usually incorporate institutional, environmental, technological, and behavioural relationships. The challenge for management is to develop a sufficiently detailed understanding of these influences in order to develop effective opportunities and mechanism for control. This challenge is heightened by the tradition of 'partial' or non-holistic thinking that continues as the conventional wisdom in the management field. Though the imperative for holistic thinking is intuitively supported by most mangers, the difficulties associated with implementing these ideas into management practice may be perceived as being 'too hard' or 'open ended' for practical application. System dynamics modelling is an appropriate process for developing an holistic understanding of any socio economic system. A realistic model can be applied to the development of management strategies and decision support. To a novice modeller, however, model construction can be intimidating process lacking in the kind of systematic procedural support seemingly offered by the more conventional, non-holistic management school. To a large degree, the integration of the qualitative social fabric matrix with quantitative system dynamics presents a more system modelling process for practical application. The proposed amalgamation also yields some added conceptual insights into the nature of management processes and prospects for control.
-
- Type:
- Document
- Date Created:
- 1995
- Collection:
- System Dynamic Society Records
- Collecting Area:
- University Archives
- Collection ID:
- ua435
- Parent Record(s):
- b83f2ce2912343b559f967dd985da515, 23d738ba88f8333bc39725f9cb5bd0b8, and 12420ec6bd5f758d2b4dea59aabd75a9
- Description:
- This abstract extends the merger and acquisition (M&A) model of Georgantzas, Schmid, & Walton (1994), showing the dynamic evolution of markets into hierarchies or other transactional exchange governance (TEG) forms resulting from the creation of a climate of trust and its effect on the internalization cost of control. The extended M&A model offsets the shortcomings of transaction cost economics (TCE) and points to the potentially rich contribution of system dynamics to exploring governance structures beyond the ideal-type forms of markets and hierarchies that dominate the TCE literature.
-
- Type:
- Document
- Date Created:
- 1995
- Collection:
- System Dynamic Society Records
- Collecting Area:
- University Archives
- Collection ID:
- ua435
- Parent Record(s):
- b83f2ce2912343b559f967dd985da515, 23d738ba88f8333bc39725f9cb5bd0b8, and 12420ec6bd5f758d2b4dea59aabd75a9
- Description:
- To comply with accreditation standards of the American Association of Collegiate Schools of Business (AACSB), B-schools in the United States have to maintain a low student to faculty ratio. AACSB standards also affect the process of reviewing full-time faculty (FTF) members for promotion and tenure (P&T), so that the P&T review process safeguards the continued development of educational and intellectual activities in US B-schools. AACSB requires the FTF of its members to enhance the reputation of their B-schools through research and publications. This essay extends the work of Georgantzas, Hamilton, & Drobnis (1994) on the implementation of AACSB standards through feedback-loop planning, showing how a system dynamics simulation model complete with computed scenarios has been helping a small but prestigious B-school assess its future in term of student to faculty ratios.
-
- Type:
- Document
- Date Created:
- 1995
- Collection:
- System Dynamic Society Records
- Collecting Area:
- University Archives
- Collection ID:
- ua435
- Parent Record(s):
- b83f2ce2912343b559f967dd985da515, 23d738ba88f8333bc39725f9cb5bd0b8, and 12420ec6bd5f758d2b4dea59aabd75a9
- Description:
- A firm's end-product waste problem motivated us to investigate the structure underlying a polymer coating process (PCP) by combining system dynamics simulation modeling with statistical process control (SPC). Our bipartisan approach proved to be rather powerful: not only it provides insight about the negative feedback-loop structure between temperature distribution and polymer thickness but also allows assessing the potential affects of leverage points on the stability of the polymer manufacturing process directly from the process capability and control charts. The new knowledge gained yields a dramatic improvement in the firm's end-product quality and productivity. Worth nothing is our transforming of the heat control equations--which correspond to the gelling operations of polymer foam and be solved using standard Runge-Kutta methods. Consequently, our essay illustrates how to effectively handle parabolic partial differential equations using conventional system dynamics simulation software.
-
- Type:
- Document
- Date Created:
- 1995
- Collection:
- System Dynamic Society Records
- Collecting Area:
- University Archives
- Collection ID:
- ua435
- Parent Record(s):
- b83f2ce2912343b559f967dd985da515, 23d738ba88f8333bc39725f9cb5bd0b8, and 12420ec6bd5f758d2b4dea59aabd75a9
- Description:
- The World Bank has recently published a 390 page study, "The East Asian Miracle" to try to shed some light on the role of government intervention in the development of East Asian economies. Could we better understand this phenomenon participate in an extensive study into the factors behind the Bangkok, Thailand real estate economy, we developed a casual loop diagram to help explain the factors responsible for the boom and eventual slow down. This process revealed some of the leverage points a similar process of understanding, the lessons learned should be applicable to other developing nations.