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- Type:
- Document
- Fecha de Creacion:
- 2005 July 17-2005 July 21
- Collection:
- System Dynamic Society Records
- Collecting Area:
- University Archives
- Collection ID:
- ua435
- Parent Record(s):
- 23d738ba88f8333bc39725f9cb5bd0b8, 3c582e6f5cf305ef0030c7471b499022, and cc5bb0ac12a5b68b26b1583548898dae
- Descripción:
- Multiple objective optimisation (MOO) is an optimisation approach that has been widely used to solve optimisation problems with more than one objective function. The benefit of this approach is that it generates a set of non-dominated solutions which a policy maker can explore and evaluate before making a final optimal selection. This paper demonstrates that MOO can be used to assist policy makers explore a richer set of alternatives when deciding on a range of values for key parameters in their system dynamics model. In order to demonstrate the approach, a well-known case study The Domestic Manufacturing Company is used, and a stock and flow model and a multiple objective optimiser are designed and coded. The results show that valid solutions are generated, and that each of these solutions can be examined independently and hence give greater insight into the problem at hand - before a decision is made as to the most appropriate solution.
-
- Type:
- Document
- Fecha de Creacion:
- 2005 July 17-2005 July 21
- Collection:
- System Dynamic Society Records
- Collecting Area:
- University Archives
- Collection ID:
- ua435
- Parent Record(s):
- 23d738ba88f8333bc39725f9cb5bd0b8, 3c582e6f5cf305ef0030c7471b499022, and cc5bb0ac12a5b68b26b1583548898dae
- Descripción:
- Sustainable use of a natural resource ensures that the ecosystem associated with that use will also provide long term environmental services to society. Such services might include the provision of clean water, removal of excess CO2 from the atmosphere, flood protection, pleasant vistas, or enhanced biodiversity. These benefits are becoming less abundant as inappropriate resource uses hasten environmental degradation. In theory, if beneficiaries pay for the environmental services received, and these payments are given to the resource users/owners to reward, or encourage, sustainable resource use, then such sustainable use will be assured. Schemes to implement such arrangements might be able to support conservation programs, and also supplement income of poor farmers and forest dwellers. Such payments are also seen as a means of encouraging better management of carbon dioxide in our atmosphere, by paying for forest practices which can store CO2. How do such systems actually work? Can payments for environmental services encourage better resource management? Might they also create disincentives for management based on ethics, altruism, and stewardship? A generic system dynamics model was used to examine these questions.
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- Type:
- Document
- Fecha de Creacion:
- 2005 July 17-2005 July 21
- Collection:
- System Dynamic Society Records
- Collecting Area:
- University Archives
- Collection ID:
- ua435
- Parent Record(s):
- 23d738ba88f8333bc39725f9cb5bd0b8, 3c582e6f5cf305ef0030c7471b499022, and cc5bb0ac12a5b68b26b1583548898dae
- Descripción:
- We analyze experimental data from the Beer Game in which the customer orders are constant (4 cases/week) and all the subjects are informed about this fact before the game starts. Even though the experimental settings disfavor oscillation and amplification, we still observe them. To analyze the decisions made by the subjects, we first estimate the decision rule used by Sterman (1989). This analysis suggests that typically subjects do not understand the time delays and the stock and flow structure of the Beer Game. Next, we relax some assumptions of this decision rule and use more sophisticated alternatives. These alternative decision rules do not yield overall improvement in terms of fit to the real data. However, for some subjects, these decision rules lead to significant improvement. Our analysis reveals strong evidence that these subjects were caught up in a reinforcing phantom ordering loop even though the experimental conditions strongly disfavor such behavior.
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- Type:
- Document
- Fecha de Creacion:
- 2005 July 17-2005 July 21
- Collection:
- System Dynamic Society Records
- Collecting Area:
- University Archives
- Collection ID:
- ua435
- Parent Record(s):
- 23d738ba88f8333bc39725f9cb5bd0b8, 3c582e6f5cf305ef0030c7471b499022, and cc5bb0ac12a5b68b26b1583548898dae
- Descripción:
- This paper discusses the benefits of having an interchange standard for system dynamics models, why XML is a good candidate on which to build such as standard, and how the development process may take place through community-wide participation. The paper also presents XMILE, a prototype model interchange standard, as a proof of the concept.
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- Type:
- Document
- Fecha de Creacion:
- 2005 July 17-2005 July 21
- Collection:
- System Dynamic Society Records
- Collecting Area:
- University Archives
- Collection ID:
- ua435
- Parent Record(s):
- 23d738ba88f8333bc39725f9cb5bd0b8, 3c582e6f5cf305ef0030c7471b499022, and cc5bb0ac12a5b68b26b1583548898dae
- Descripción:
- Most dynamic decision making tasks include assumptions which have a huge uncertainty attached to them. Organizations are inherently complex. The combination of uncertainty and complexity results often in a sub-optimal decision. This paper emphasises on the usage of probabilistic system dynamics (SD). The focus of probabilistic SD is to represent the behaviour of uncertain variables in a realistic manner. The information generated by probabilistic SD could produce complete information thereby improving the mental models of decision makers. Many SD models use deterministic values of variables. However, determinism is untrue for real business settings. In order to test the effectiveness of probabilistic SD on managerial decision making, this study aims at conducting a series of rigorous and controlled experiments. Specifically it tests the usefulness of (1) system dynamics itself, (2) model validation techniques and (3) probabilistic system dynamics on decision-making. Furthermore, these experiments are conducted in two settings (1) using a simple model and (2) using a complex model. It is hoped that probabilistic SD would be instrumental in producing relevant information that would help in improving managers mental models, especially in complex scenarios. This in turn will result in better decisions under uncertainty in complex business environments.
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- Type:
- Document
- Fecha de Creacion:
- 2005 July 17-2005 July 21
- Collection:
- System Dynamic Society Records
- Collecting Area:
- University Archives
- Collection ID:
- ua435
- Parent Record(s):
- 23d738ba88f8333bc39725f9cb5bd0b8, 3c582e6f5cf305ef0030c7471b499022, and cc5bb0ac12a5b68b26b1583548898dae
- Descripción:
- If junior doctors are to work significantly fewer hours in the future, how can they still receive full training and continue to provide necessary levels of medical service to patients? Historically, excessive hours have been a way of the life for junior doctors worldwide, but New Deal regulations, a revised junior doctor contract, and the EU Working Time Directive are changing this. A project at Derriford Hospital in Plymouth is researching the nature of quality and effective training, and constructing SD models to yield insights and eventually support operational decision-making. This has already yielded significant insights for those at Derriford wrestling with this seemingly impossible task, including, the circularity between junior doctor training, consultants service and their training-supervision role, and the quality of training provided, and the likely importance of recruiting outside the progression process in addressing service imbalances. It also highlights some of the special challenges in projects where there are many stakeholders, political agendas, and a continuously changing environment.
-
- Type:
- Document
- Fecha de Creacion:
- 2005 July 17-2005 July 21
- Collection:
- System Dynamic Society Records
- Collecting Area:
- University Archives
- Collection ID:
- ua435
- Parent Record(s):
- 23d738ba88f8333bc39725f9cb5bd0b8, 3c582e6f5cf305ef0030c7471b499022, and cc5bb0ac12a5b68b26b1583548898dae
- Descripción:
- Extreme Events are low probability, high consequence events, often resulting in billions of dollars of damage each year in the United States. Natural hazard issues connect experts in the natural science and social science, which complicates the problem for policymakers who may have balance multiple objectives as well as short term and long term goals. The recent devolution revolution trend in government has made its way to natural hazard policy domains. There is more pressure on local communities to create and implement mitigation plans that will promote long term sustainable development at the local level. The conceptual model for this research project explores the primary mitigation policy alternatives and depicts the "false sense of security" trap, with endogenous explanations, in a stock and flow feedback structure.
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- Type:
- Document
- Fecha de Creacion:
- 2005 July 17-2005 July 21
- Collection:
- System Dynamic Society Records
- Collecting Area:
- University Archives
- Collection ID:
- ua435
- Parent Record(s):
- 23d738ba88f8333bc39725f9cb5bd0b8, 3c582e6f5cf305ef0030c7471b499022, and cc5bb0ac12a5b68b26b1583548898dae
- Descripción:
- Our paper presents a model of economic impacts arising from disruptions to critical infrastructures. This model is a component of the Critical Infrastructure Protection Decision Support System (CIP/DSS) which simulates the dynamics of a set of interconnected individual infrastructures. We use factors of production (such as energy, telecommunications, and labor) from the CIP/DSS model to estimate the effects of interruptions to these infrastructures. The system dynamics approach we use is compared to equilibrium-based approaches such as input-output modeling. This method allows an understanding of the economic benefits of various protective measures. We incorporate non-equilibrium dynamics that arise from these disruptions to provide values for various economic impacts such as lost revenues and lost sales. The results from a disruption due to an infectious disease outbreak are presented. We show that the effects of quarantine dominate the overall economic impacts in a number of cases.
-
- Type:
- Document
- Fecha de Creacion:
- 2005 July 17-2005 July 21
- Collection:
- System Dynamic Society Records
- Collecting Area:
- University Archives
- Collection ID:
- ua435
- Parent Record(s):
- 23d738ba88f8333bc39725f9cb5bd0b8, 3c582e6f5cf305ef0030c7471b499022, and cc5bb0ac12a5b68b26b1583548898dae
- Descripción:
- Accounts of the real-world use of system dynamics as a policy evaluation tool in macro-economic management are relatively rare. This paper offers an overview of current research being undertaken for the government of the State of Sarawak in E. Malaysia where an SD model is being formulated to inform the States future economic and social planning to 2020. Although still a work-in-progress, enough has been achieved to enable an interim account of the research to be written. Positive engagement with State government officials at the highest level has put system dynamics on the map in this corner of SE Asia.
-
- Type:
- Document
- Fecha de Creacion:
- 2005 July 17-2005 July 21
- Collection:
- System Dynamic Society Records
- Collecting Area:
- University Archives
- Collection ID:
- ua435
- Parent Record(s):
- 23d738ba88f8333bc39725f9cb5bd0b8, 3c582e6f5cf305ef0030c7471b499022, and cc5bb0ac12a5b68b26b1583548898dae
- Descripción:
- Distribution must make a decision regarding its role in the specialty contracting supply chain. It can continue its historical role as wholesale/retail combination and hope for profitability, or it can choose to manage the channel by providing low cost products and services. Profitability can only come through system productivity. System productivity depends on recognition and elimination of waste in the current operations and can be further improved by operational process innovation. The cost drivers (CDs) of distributors can be impacted by identifying and addressing internal inefficiencies, effects of customer interactions, and the impact of suppliers on price and delivery. By managing the following elements, distributors can improve their bottom line by better than 30%: 1. First-time pass yield of order taking and delivery 2. Identification and reduction of waste 3. Customer point of entry This paper suggests a methodology for improving the system productivity through management of these elements.