In this paper an application of the System Dynamics approach in the field of energy supply is presented. Decentralized energy supply is introduced as a new energy system with a high potential for meeting ecological requirements and sustainability targets. System Dynamics models of one power supply unit (PSU) and of the decentralized energy supply (New Energy System Model) are described. The electrical and thermal power flow and the power conversion processes represent the basis for the stock-and-flow diagrams. At any time and for every sub process of the overall system the precise power and energy state can become certain and comprehended for the user. With examples some results of simulation are represented. Investigations of technical and ecological potential of decentralized energy supply systems are the primary objective of the models. The models are also used for education purposes for the elucidation of energetic supply processes with different power station technologies.
On 21 September 1999 at 1:47 am, an earthquake measuring 7.3 on the Richter scale struck central Taiwan, causing serious damage and loss of lives. As of February 2006, only 70% of the reestablishment work has been completed. With rapid advances in urban development, the destruction incurred by earthquake disasters increases both in extent and severity. With the aim to minimize loss in human lives and properties caused by natural disasters, this study probes into the urban disaster prevention mechanism, examines the problems encountered in disaster prevention and strategies for prevention. A system dynamics model is established to simulate changes in the disaster prevention system on the basis of related statistics and survey data of September 21 Earthquake. Strategies for urban planning, development and management are suggested from the perspective of disaster prevention. The simulation analysis can offer valuable insight to policy-makers for assessing and deciding on the most feasible and effective strategies to be implemented.
Modeling contagious diseases has taken on greater importance over the past several years as diseases such as SARS and avian influenza have raised concern about worldwide pandemics. Most models developed to consider projected outbreaks have been specific to a single disease. This paper describes a generic System Dynamics contagious disease model and its application to human-to-human transmission of a mutant version of avian influenza. The model offers the option of calculating rates of new infections over time based either on a fixed reproductive number that is traditional in contagious disease models or on contact rates for different sub-populations and likelihood of transmission per contact. The paper reports on results with various types of interventions. These results suggest the potential importance of contact tracing, limited quarantine, and targeted vaccination strategies as methods for controlling outbreaks, especially when vaccine supplies may initially be limited and the efficacy of anti-viral drugs uncertain.
Why is health reform so difficult to achieve in the US? When it does succeed, what factors contribute to its success? This paper extends a causal model presented last year to include political and other factors that help to answer these questions. The paper examines the experience of several states in the US as they have struggled with a key aspect of health reform, extending insurance coverage to children, families, and other groups that are uninsured. . It also draws from other models that have been applied to understanding political and social change. The causal analysis that is presented emphasizes the importance of making policy choices in shaping proposed reforms that fit within a window of opportunity presented by the states political and economic environment. The paper concludes by suggesting that expanding access must be viewed as an ongoing process in which early successes create opportunities to benefit additional people.
Simulation-based learning environments, often called management flight simulators or Microworlds, are excellent tools for giving people without modeling experience an intuitive understanding of complex systems. Learning environments let them experience the dynamics of complex systems without the hurdle of having to build models from scratch. This workshop will deal with the design of learning environments, their user interfaces, underlying models, and workshop formats for experiencing them. Special attention will be paid to methods of displaying information to help users understand causes of the behavior they encounter and thereby make better decisions and
learn more quickly. The workshop will also emphasize the importance of design based on clear learning objectives that reflect limitations in decisionmakers' mental models, model boundaries consistent with those objectives, stakeholder involvement, early testing of prototypes, and evaluation and ongoing modification of the finished product. The presenter will show a number of examples from his own work from health care, education, the news media, and other fields. He is also eager to make the workshop interactive and would like to hear about other peoples experiences with learning environments and from people with models they are interested in turning into learning environments.
The session on the Dynamics of Health Reform, hosted by the Health Policy Special Interest Group (HPSIG), will focus on factors promoting and resisting change in different countries' health care systems, possible unintended consequences of reform efforts, and potential leverage points for achieving significant reform. The session builds on insights developed in a session at the 2005 ISDC in Boston. This year, the session will begin with brief presentations of a number of papers that address health care system change and reform in several countries and at scales ranging from neighborhoods in cities to regions and states to an entire country. After these presentations, attendees will discuss common features across these several countries and scales, as well as from their own countries, and synthesize some useful "rules of thumb" for health reform that benefit from a dynamic perspective. We hope to also have some local experts from the Netherlands in attendance who can draw on their country's recent experience with reform. The balance of the session will be spent on thinking about next steps for the HPSIG, further development of its web site and Wikipedia, and potential focus for a session at the 2007 ISDC.
Safety reporting systems, e.g. Air Safety Reporting Systems, are extremely efficient components of well-functioning safety schemes. A Cyber Security Reporting System is badly needed, but good information security data is very difficult to gather and many barriers prevent making existing data available for scientific purposes. In the scarcity of real-cases, we argue that Dynamic Stories, i.e. the various narratives that can be derived from system dynamics models of the existing system dynamics studies of information security might help establish a Virtual Information Security Reporting System. We do have an interesting opportunity in our running study of information security risks in the transition to eOperations in the offshore oil & gas sector. Given the importance of security for eOperations and the huge stakes involved, it seems that an umbrella organization such as the Norwegian Oil Industry Association is a potential adopter of a Virtual Information Security Reporting System. Our paper formulates issues that need to be solved in order make our vision of such reporting system a tangible prospect.
This paper presents an attempt to integrate the two major opposing streams of philosophy of science, that is, the traditional reductionist/logical empiricist approach with the more modern relativistic/holistic approach. Even though the two approaches represent opposite views in the philosophy knowledge creation, the combination of the two is possible as they also share common characteristics. As a result the synergetic effects of the combination draw new directions for research methods and model development. The aim of this paper is to combine the explicit knowledge on strategic management stored on the Product Impact of Marketing Strategy (PIMS) database, with the conceptual framework of Systems Thinking, and the simulation capabilities of System Dynamics. The combination is implemented in the form of an integrated generic System Dynamics model, that includes market related factors, quality related factors and system structural factors that influence the success of any management strategy. The integrated generic system dynamics model can serve as a strategic management centre that can be utilized by a Strategic Business Unit in deciding how to compete in an uncertain and rapidly changing environment. Various business scenarios can be tested by simulating organizational operations and environmental processes, whereby effective strategy formulation can be carried out.
Two hypotheses on how tree mortality progresses are proposed in the literature: Manions gradual decline and Bossels sudden death hypotheses. Bossel already formulated a mechanism in his model, BAUMTOD, as the cause of sudden death phenomena. His model, however, cannot be used to generate a causal understanding to Manions hypothesis. Therefore, a causal mechanism for the gradual decline pattern is suggested and incorporated in BAUMTOD; the modified model is called BAUMTOD-M. The suggested mechanism concerns the internal imbalance of respiration demand and available photosynthate supply. The eigenvalue elasticity analysis (EEA) is employed to study the likely structural causes behind tree mortality according to the two hypotheses. The analyses of both models suggest that, in stress-free conditions, a tree functions as an integrated organism. The analyses further suggest that the inability to supply respiration demand plays a crucial role at the onset of mortality. Differences in assumed mechanisms regarding the impact of this inability cause different paths to mortality in each model. This may mean either 1) Bossels hypothesis is a special case of Manions hypothesis or 2) there are truly different mechanisms at work in various observed mortality cases. More data and research is needed to clarify these points.
The purpose of the paper is to discuss the phenomenon why some system dynamics projects fail to generate substantial impact in organizationsdespite the fact that they are based on an apparently valid system dynamics model and are conducted by experts in the field. The approach followed in the paper is a conceptual discussion, extended by a few short case studies. Findings are that the quality of the model and the expertise of the modeler are necessary, but not sufficient requirements for organizational impact. Further research should concentrate on the detailed analysis of additional requirements. Practical implications are an increased embedding of system dynamics projects in organizational intervention architectures. The originality of the paper lies in its focus and discussion of failed projects that are invaluable sources for insight generation.