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Guneralp, Burak with George Gertner, "Feedback loop dominance analysis of two tree mortality models"
- Type:
- Document
- Date Created:
- 2006 July 23-2006 July 27
- Collection:
- System Dynamic Society Records
- Collecting Area:
- University Archives
- Collection ID:
- ua435
- Parent Record(s):
- f9377a3ac7b50b1fca5e04fb6d679ec2, 23d738ba88f8333bc39725f9cb5bd0b8, and 32937c7b43e3e015509bb71fd40d2054
- Description:
- 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.
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- Type:
- Document
- Date Created:
- 2006 July 23-2006 July 27
- Collection:
- System Dynamic Society Records
- Collecting Area:
- University Archives
- Collection ID:
- ua435
- Parent Record(s):
- f9377a3ac7b50b1fca5e04fb6d679ec2, 23d738ba88f8333bc39725f9cb5bd0b8, and 32937c7b43e3e015509bb71fd40d2054
- Description:
- 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.
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- Type:
- Document
- Date Created:
- 2006 July 23-2006 July 27
- Collection:
- System Dynamic Society Records
- Collecting Area:
- University Archives
- Collection ID:
- ua435
- Parent Record(s):
- f9377a3ac7b50b1fca5e04fb6d679ec2, 23d738ba88f8333bc39725f9cb5bd0b8, and 32937c7b43e3e015509bb71fd40d2054
- Description:
- The overall target of the Swiss Energy Policy is to reduce CO2-emissions and thereby to achieve the vision of an energy-efficient 2000 Watt per Capita Society. A major instrument to contribute to the vision in the residential building sector is standards about energy-efficient building designs. However, new residual houses according to the energy-efficiency standard are not as often constructed as they ought to be. This short-term decision has a long-term consequence. In this paper, a preliminary System Dynamics model about the system residential building environment will be presented with the purpose to explain the development of key variables of the building environment system. The analysis of possible policies put forward that a sound understanding of the decision process of potential building owners is necessary to create a beneficial system design which foster the diffusion of energy-efficient building designs. Furthermore, the paper should enable discussions about the model and methodological issues of the model creation process.
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- Type:
- Document
- Date Created:
- 2006 July 23-2006 July 27
- Collection:
- System Dynamic Society Records
- Collecting Area:
- University Archives
- Collection ID:
- ua435
- Parent Record(s):
- f9377a3ac7b50b1fca5e04fb6d679ec2, 23d738ba88f8333bc39725f9cb5bd0b8, and 32937c7b43e3e015509bb71fd40d2054
- Description:
- An Interactive Learning Environment (ILE) is a tool to convey learning effects about dynamic and complex systems. Information can be packaged and delivered to assigned persons. Several pedagogical objectives are achievable: Teaching the capability to operate dynamic systems, awareness about the effective delays, focusing on the importance of feedback loops and their strengths, and familiarize the learner with the concept of nonlinearities. As an instance, the flight simulator Managing a Consulting Company puts each of two participant groups in the role of a Consulting Companys management board. The ILE is created as a network simulation, which creates a dynamic learning environment and enables greater learning effects than normal single simulation models. By experiencing the simulation, the participants will obtain knowledge about the dynamic resource perspective of strategic management. The simulator, particularly, provides learning effects about management of intangibles and dynamic decision making. In order to facilitate a successful ILE-training session, it is beneficial to reflect about several perspectives connected to the development of ILEs. This is the goal of the paper. It concludes with a heuristics about the different perspectives of an ILE-session.
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- Type:
- Document
- Date Created:
- 2006 July 23-2006 July 27
- Collection:
- System Dynamic Society Records
- Collecting Area:
- University Archives
- Collection ID:
- ua435
- Parent Record(s):
- f9377a3ac7b50b1fca5e04fb6d679ec2, 23d738ba88f8333bc39725f9cb5bd0b8, and 32937c7b43e3e015509bb71fd40d2054
- Description:
- Group model building is nascent the latest years. However, only few educational institutions offer professional education and research in the field. Furthermore, detailed empirical literature about group model building is rather rare. Hence, this paper will serve three purposes connected to group model building. First, it will document and critically reflect upon a group model session and derive lessons learned. Second, it will create a comprehensive group model building framework based on existing streams of research. The result is a framework that includes context and stakeholder analysis as basic preparation tools for a group model building project. In the more modeling session oriented stages, the approaches of Vennix and Andersen et al. will be integrated. And thirdly, it will apply the developed framework to a current research project in which the diffusion of energy-efficient innovations will be modeled. Further research will concentrate on validation and elaboration of the developed framework.
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- Type:
- Document
- Date Created:
- 2006 July 23-2006 July 27
- Collection:
- System Dynamic Society Records
- Collecting Area:
- University Archives
- Collection ID:
- ua435
- Parent Record(s):
- f9377a3ac7b50b1fca5e04fb6d679ec2, 23d738ba88f8333bc39725f9cb5bd0b8, and 32937c7b43e3e015509bb71fd40d2054
- Description:
- Traffic congestion is a significant problem for modern society, but it is a necessary evil. Congestion is the principal mechanism to resolve the surplus demand for road space during peak traffic areas. There is universal agreement that traffic from privately owned vehicles (POVs) will greatly increase in most parts of the world in the next 5-15 years. Acknowledging that traffic congestion will continue to be societys main solution to the competition for scarce road space, this paper proposes additional teleworking facilities with a door-to-door shuttle services with mini-offices. Whether stuck in traffic or not, time spent driving in POVs is unproductive, whereas near office conditions provided in trains, ferries and, nowadays, also in planes make it possible for passengers to stay productive . Teleworking in a door-to-door shuttle service with mini-offices would increase the attractiveness of public transit services in some large cities and, possibly, in larger quasi-urban areas in heavily populated countries. Such condition might provide leverage to deal with heavy traffic, especially traffic congestion. We suggest niches for an experimental transition to door-to-door shuttle services with mini-offices. We propose further systemic studies to find out what kind of industrial synergies would arise and how large societys leverage to deal with heavy traffic could be.
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- Type:
- Document
- Date Created:
- 2006 July 23-2006 July 27
- Collection:
- System Dynamic Society Records
- Collecting Area:
- University Archives
- Collection ID:
- ua435
- Parent Record(s):
- f9377a3ac7b50b1fca5e04fb6d679ec2, 23d738ba88f8333bc39725f9cb5bd0b8, and 32937c7b43e3e015509bb71fd40d2054
- Description:
- Formal model analysis remains an important and challenging area in system dynamics. This paper proposes a method to incorporate eigenvectors to the now more common eigenvalue analysis of dynamic models. We provide a description of the application of the method to a linear system example.
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- Type:
- Document
- Date Created:
- 2006 July 23-2006 July 27
- Collection:
- System Dynamic Society Records
- Collecting Area:
- University Archives
- Collection ID:
- ua435
- Parent Record(s):
- f9377a3ac7b50b1fca5e04fb6d679ec2, 23d738ba88f8333bc39725f9cb5bd0b8, and 32937c7b43e3e015509bb71fd40d2054
- Description:
- As a consequence of faster time-to-market and shorter product life cycles, companies today introduce new products more frequently. While new products can potentially bring tremendous value, they also pose enormous challenges as companies are most vulnerable during new product transitions. Due to the high stakes of new product transitions, planning and execution cannot be overemphasized. Nevertheless, our discussions with product transition teams suggested that a recurring handicap during transitions was the lack of a formal process to guide managerial decisions. This work develops a process to facilitate decision making during new product transitions. The proposed process analyzes the risks impacting a transition, identifies a set of factors across departments tracking those risks, monitors the evolution of these factors over time, and develops a playbook mapping scenarios of risks and responses. Our studies show that the transition process helps level expectations across the organization, lessens the chance and impact of unanticipated outcomes, and helps synchronize responses among different departments.
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- Type:
- Document
- Date Created:
- 2006 July 23-2006 July 27
- Collection:
- System Dynamic Society Records
- Collecting Area:
- University Archives
- Collection ID:
- ua435
- Parent Record(s):
- f9377a3ac7b50b1fca5e04fb6d679ec2, 23d738ba88f8333bc39725f9cb5bd0b8, and 32937c7b43e3e015509bb71fd40d2054
- Description:
- Cancer is a problem that has long been wrought over by philosopher and biologist alike. It provides a tremendous insight into the diversity of complex phenomena, into the ontogeny of order, into the deepest deterministic principles of life itself. Here we try to sketch dynamically the emergence of such a metastatic and invasive process, tying together chemical, molecular, and physiological insights to more clearly define the problem. We follow the progression of small-cell lung cancer in a population of brachial lung cells tracing the molecular, cellular, and systems etiology of this complex disease.
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- Type:
- Document
- Date Created:
- 2006 July 23-2006 July 27
- Collection:
- System Dynamic Society Records
- Collecting Area:
- University Archives
- Collection ID:
- ua435
- Parent Record(s):
- f9377a3ac7b50b1fca5e04fb6d679ec2, 23d738ba88f8333bc39725f9cb5bd0b8, and 32937c7b43e3e015509bb71fd40d2054
- Description:
- Model analysis in system dynamics (SD) entails articulating exactly how the structure of circular, feedback relations among variables in a system determines its performance through time. This article combines disruptive innovation (DI) theory with SD to show the use and benefits of model analysis with the pathway participation metric (PPM), implemented in the Digest® software. The model replicates the hard-disk makers overshoot and collapse dynamics that DI allegedly caused. Multiple insights emerge from the dynamics the model computes. Model analysis shows that, over five distinct time phases, four different feedback loops become most prominent in generating the hard-disk makers population dynamics from 1973 to 1993. And Digest® helps detect exactly how changes in loop polarity and prominence determine system performance.