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-
- Type:
- Document
- Date Created:
- 1995
- Collection:
- System Dynamic Society Records
- Collecting Area:
- University Archives
- Collection ID:
- ua435
- Parent Record(s):
- 23d738ba88f8333bc39725f9cb5bd0b8, 6214ef14bd960d7be5cd8a816a71dc52, and 12420ec6bd5f758d2b4dea59aabd75a9
- Description:
- The paper reviews ideas on validation in both mainstream OR/MS simulation and SD. A tetrahedron model derived from the former literature is adapted to SD and proposed in a new form; the Folding Star. This framework structures ideas on the elements of SD activities as well as the roles and validation measures required. Further structuring using a tabular and hierarchical format results in an interpretation of current SD validity test and the proposal of two extensions, concerning cultural and operational issues. The framework is able to demonstrate the validity aspirations of different SD activities and to indicate areas for future development in validation test. It also shows the respective strengths and weaknesses of different SD activities and leads to the proposal of a new form, Extended SD, an engagement between SD and 'soft' OR which aspires to a comprehensive notion of validity.
-
- Type:
- Document
- Date Created:
- 1995
- Collection:
- System Dynamic Society Records
- Collecting Area:
- University Archives
- Collection ID:
- ua435
- Parent Record(s):
- 23d738ba88f8333bc39725f9cb5bd0b8, 6214ef14bd960d7be5cd8a816a71dc52, and 12420ec6bd5f758d2b4dea59aabd75a9
- Description:
- In order to express the radical changes in the way technology has been and continues to be developed, applied, and commercialized over time, the concept of a techno-paradigm shift is used. The techno-paradigm shift is distinguished into five dimensions: innovation pattern, and societal diffusion of technology. In order to obtain a comprehensive understanding of these dynamic characteristics of technology, we have to orchestrate a unique blends of scholarly tools- case studies, formal modeling, and insightful observations.
-
- Type:
- Document
- Date Created:
- 1995
- Collection:
- System Dynamic Society Records
- Collecting Area:
- University Archives
- Collection ID:
- ua435
- Parent Record(s):
- 23d738ba88f8333bc39725f9cb5bd0b8, 6214ef14bd960d7be5cd8a816a71dc52, and 12420ec6bd5f758d2b4dea59aabd75a9
- Description:
- Traditionally system dynamists used two kinds of modelling approach; top-down approach and bottom-up approach. With top-down modelling approach (feedback loop thinking) modellers first draw a causal loop diagram and then details it down to the stock and rate variables and then auxiliary. Top-down approach forces a modeller to see forest rather than trees, while bottom-up approach forces a modeller to construct forest by planting trees incrementally. In general, system dynamics use both approach in modelling processes simultaneously or sequentially. However, most of previous softwares for SD modelling have focused on the bottom-up approach. The 'operational thinking' concept of Barry Richmond is most typical in this trend. In this paper, a hierarchical modelling is introduced as a new modelling approach which can integrate top-down approach and bottom-up approach. A hierarchical modelling approach extends the sector view concept proposed recently by Barry Richmond. In the hierarchical modelling approach, a sector can contain many sub-sectors which also can have their own sub-sector. A modeller can use a bottom-up approach or operational thinking in a sector. When a modeller wants to connect variable across sector or to extend a variable into a sector, he can use a top-down approach. In this paper, a hierarchical modelling approach is implemented with an object-oriented programming method. This paper explains why an object-oriented programming is necessary in implementing the hierarchical modelling approach and discusses some problems which should be resolved for developing a more easy and transparent hierarchical modelling approach.
-
- Type:
- Document
- Date Created:
- 1995
- Collection:
- System Dynamic Society Records
- Collecting Area:
- University Archives
- Collection ID:
- ua435
- Parent Record(s):
- 23d738ba88f8333bc39725f9cb5bd0b8, 6214ef14bd960d7be5cd8a816a71dc52, and 12420ec6bd5f758d2b4dea59aabd75a9
- Description:
- Since the Rome Club published its report. "Limits To Growth", the following have been accepted by the present generations as common goals to create a better world for future generations: the efficient use of our limited natural resources, and the control of the growth of population which shows a tendency to ever consume more and faster. This movement has so far led to variety of revolutionary changes in energy-saving technology as well as the adoption of birth control by governments in Asia, such as China, India, and Indonesia. Since the end of the Cold War, a typical representation of confrontation and competition, the concept of coexistence and co-prosperity have become more viable and acceptable. The goals we wish to accomplish may be difficult, especially, if we proceed with the present method and style of consumption-oriented economic activities and with the burden of an ever growing population. As barriers among nations, economic and otherwise, are being removed, it not only eliminates the conceit of an otherwise isolated nation but it helps to make one nations problem a shared and more easily and quickly solvable world problem. As we approach the twenty-first century, people have started accepting the idea of a common goal of creating a world where people thrive towards coexistence and co-prosperity beyond religious, political and ideological differences. In a world of limited resources, desires extravagant and beyond its permissible level would always lead to a state contrary to coexistence and co-prosperity. Therefore, unless we resolve the problem of shortage, we will not be able to firmly establish coexistence and co-prosperity. When we consider the phrase "soft landing into the twenty-first century," it is apparent that we accomplish the following: resolve the problems in our current education system, provide the technology to replace the consumption based economic activities with that of resource-recovery and recycling, and provide fundamental solutions to environment, food production, health care, and energy, all of which are presenting threats to humankind. Our present approach, the application of effective microorganism, has started gaining wide attention as the only technology available now. It has been applied in a wide variety of areas in environment, food production, medicine, energy, and industry. It is expected to be a breakthrough technology promising a soft landing for the people into twenty-first century.
-
- Type:
- Document
- Date Created:
- 1995
- Collection:
- System Dynamic Society Records
- Collecting Area:
- University Archives
- Collection ID:
- ua435
- Parent Record(s):
- 23d738ba88f8333bc39725f9cb5bd0b8, 6214ef14bd960d7be5cd8a816a71dc52, and 12420ec6bd5f758d2b4dea59aabd75a9
- Description:
- To create more effective learning environments for a strategic management, system dynamics modelers have recommended the use of computer simulation models as a supplement to conventional case studies. Although custom designed simulation games provide students with the opportunity to investigate the effects of alternative actions, their creation involves considerable development efforts. Moreover, available simulations provide on direction for using case information to discover systems thinking issues and solutions. In this paper we demonstrate how instructors can introduce feedback concepts to students via conventional case discussion. Specifically, we show how feedback processes can be woven into a case discussion involving issues of corporate diversification and restructuring.
-
- Type:
- Document
- Date Created:
- 1995
- Collection:
- System Dynamic Society Records
- Collecting Area:
- University Archives
- Collection ID:
- ua435
- Parent Record(s):
- 23d738ba88f8333bc39725f9cb5bd0b8, 6214ef14bd960d7be5cd8a816a71dc52, and 12420ec6bd5f758d2b4dea59aabd75a9
- Description:
- This paper discusses the successful use of System Dynamics in the electric power industry. It begins with a list of studies and articles documenting extensive use of System Dynamics to aid corporate and government planners around the world. I then speculate on why this particular industry has been the focus of so many System Dynamics project for Bonneville Power Administration in the Pacific Northwest region of the United States. Reflecting on the Bonneville project, I observe two important trends. The first is a trend toward interactive models that are easier for group operation. The second is a trend toward more attention on the consumers of electric power. The paper concludes with results from a recent study of the world aluminum industry, an industry that consumes a tremendous amount of electric power.
-
- Type:
- Document
- Date Created:
- 1995
- Collection:
- System Dynamic Society Records
- Collecting Area:
- University Archives
- Collection ID:
- ua435
- Parent Record(s):
- 23d738ba88f8333bc39725f9cb5bd0b8, 6214ef14bd960d7be5cd8a816a71dc52, and 12420ec6bd5f758d2b4dea59aabd75a9
- Description:
- Much of the science and policy debate around global climate change has focused on models. Most models focus is a single aspect of climate change- atmospheric physics and chemistry, macroeconomic effects of abatement policies, or impacts on land cover from changing temperature and rainfall for example. Only a few models attempts to make climate change fully endogenous by including both the influence of human activities on climate and the impact of climate change on human activity. The best-known climate-economy model is William Nordhaus' DICE model. The model is a conventional macroeconomics Ramsey growth model with simple carbon and temperature subsystems added. These create a negative feedback loop which tends to reduce economic output due to climate impacts on economic activity. Experiments with the model suggest that only limited effort should be addressed to carbon dioxide emissions abatement. While the DICE model meets some of the exogenous, such as the growth of population and emissions reduction technology. Output is generated by optimization, rather than by simulation with explicit decision rules. This paper explores the impact of structural changes to the model specification that attempts to bring it closer to the system dynamics paradigm. The impact of exogenous population and the technology drives is explored. Carbon flows are made more explicit, to demonstrate the importance of sink constraints and temperature feedbacks to the carbon cycle. A path dependent energy sector with endogenous technology is tested. Bounded rational decision rules are substituted for optimization. These tests generally yield results suggesting substantially higher abatement levels than Nordhaus concludes are necessary.
-
- Type:
- Document
- Date Created:
- 1995
- Collection:
- System Dynamic Society Records
- Collecting Area:
- University Archives
- Collection ID:
- ua435
- Parent Record(s):
- 23d738ba88f8333bc39725f9cb5bd0b8, 6214ef14bd960d7be5cd8a816a71dc52, and 12420ec6bd5f758d2b4dea59aabd75a9
- Description:
- This paper presents the generic framework for a national-level model of sustainability. The basic assumption is that there is not one model (or condition) but multiple possibilities; not one path, but a multiplicity of options. The countries of this world are diverse indeed, and the challenges facing them are both generic and idiosyncratic. In appreciation of the complexity and diversity of development, our approach is to depict underlying structural and functional linkage representing the profile of states, with the objective of exploring possible paths over time in response to structural conditional as well as policy choices.
-
- Type:
- Document
- Date Created:
- 1995
- Collection:
- System Dynamic Society Records
- Collecting Area:
- University Archives
- Collection ID:
- ua435
- Parent Record(s):
- 23d738ba88f8333bc39725f9cb5bd0b8, 6214ef14bd960d7be5cd8a816a71dc52, and 12420ec6bd5f758d2b4dea59aabd75a9
- Description:
- As we approach the turn of the millennium and pass the 50th anniversary of the Breton Woods and the United Nations institutions, none of our major development agencies have a comprehensive sustainable development model. The Millennium Institute, after a decade of assisting countries in long-term sustainable development studies, has developed a multidisciplinary national sustainable development model called Threshold 21. The model integrates economic production, national accounts, demography, agriculture, energy, health, education, nutrition, and environment in a single model based on the principles and methodology of system dynamics. It simulates the dynamic interactions of these variables for a period of 50 years. Threshold 21 is written in the Vensim simulation environment. The model is being applied first in an analysis of alternative futures for Bangladesh. The Millennium Institute, in collaboration with development partners, is planning applications in several countries, including Australia, China, and the United States.
-
- Type:
- Document
- Date Created:
- 1995
- Collection:
- System Dynamic Society Records
- Collecting Area:
- University Archives
- Collection ID:
- ua435
- Parent Record(s):
- 23d738ba88f8333bc39725f9cb5bd0b8, 6214ef14bd960d7be5cd8a816a71dc52, and 12420ec6bd5f758d2b4dea59aabd75a9
- Description:
- Experimenting further with the World3 model, this paper attempts to formulate the operational means to implement the critical recommendations of the "Limits to Growth" study. Using feedback as the organizing principle and the work of Daly (1991), Page (1997) and Saeed (1985) as guidelines, additional policy space was built into the model for self-regulating its critical policy parameters. The policies so created not only appeared to lie within the scope of the existing and potentially feasible regulatory institutions, they were insensitive to their receptive behavioral parameters and also the timing to intervention. The operational policy design procedures adopted in the paper is also seen to create an important heuristic for policy design in general, which should strive to create operational rather than power-cased intervention.