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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:
- The purpose of this paper is to explain, in terms of a simple model, the structure of formal organization, and to show how external events can affect their performance. The conceptual viewpoint used to describe the coordination occurring within organizations, is that decision-making theories of organization design, namely, that organizations are information processing systems with problem solving units connected by a communication network. We begin by modeling a basis coordination structure (functional hierarchy), as set of actors (processors and managers) who are connected together by communication lines. Then, queuing models are employed to analyze the execution of tasks by processors and the processing of result by managers. A production function is defined, which considers the average delay for both processors and managers. Then we introduce the concept of environmental uncertainty. We explain how it relates to structures, and how it can affect the organization's productivity. In order to cope with this uncertainty, we have considered four alternative organizing strategies (Galbraith 1977): (1) creation of slack resources, (2) creation of self-contained tasks, (3) investment in formation systems, and (4) creation of lateral relation. Each of these strategies is applied to the initial coordination structure, and for each we define a production cost equation. In addition to production costs, we also analyze coordination and vulnerability costs. Then, based on these cots we make a comparison of the four strategies, pointing out the trade-offs between them. In conclusion, since we consider management delay time in our model, we are able to explain in more detail the trade-offs between the alternatives strategies.
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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:
- In an attempt to understand the current practices and problems in design projects, a system dynamics model was developed for the management of detailed design process in a civil engineering project. The model took an integrative approach, consisting of four interrelated subsystems: human resources, design production, controlling and planning. Two sets of data were used to initialise and test the model. Some policies and scenarios were then explored to gain insight into the model's behavior and to seek alternatives for better management. The experiments showed the following policy hierarchy: A) In terms of meeting scheduled times, the effectiveness of policies is in order:(1) progress control, (2) manpower allocation, (3) estimation of workload, and (4) realisation of underestimated work. B) In terms of man-days expended or cost reduction, the effectiveness of policies is the order: (1) manpower allocation, progress control, (3) estimation of workload, and (4) realisation of underestimated work. As such, good estimation of workload is essential but not sufficient to bring the project to finish on schedule. Good project control and early perception of real progress are needed to ensure adequate resource allocation and on-time completion.
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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:
- In making models of real world problems or real world processes, the need for transfer of data between model and external files, applications or other devices becomes important. This paper illustrates the use of automatic data transfer in model construction and in process control. In a typical model construction and verification process, real date plays an important role. Once a model is made of the target system, real data is fed into the model, and the model output is compared to the output of the real system. The result of the comparison is used as a basis for refining model structure, model parameters, or both. The Dynamic Data Exchange (DDE) object and the Archive object of POWERSIM may be used in a model to import and export data during simulation. This greatly reduces the amount of work involved in checking model against reality. DDE can also be used to set up a data analysis, for example, by launching a spreadsheet or a statistical program. In combination with the multiple runs feature of POWERSIM, a series of model structures and model parameters can be tested with real data without manual intervention. In a research project aiming at developing a model of the biological process of fish growing in a fish farm, the above tools have allowed for extensive use of data from fish farms in the process of model construction and verification. The basic feedback loop of a process control system, involves measurements (import of data), comparison between measured values and desired values, followed by a controlling action (output of data) aiming at closing the gap between actual and desired process state. The data transfer protocols of POWERSIM make it possible to implement process control systems as POWERSIM models, and linking the models to the physical process. A range of input/output devices for the Windows operating systems supports DDE or Net-DDE, and may therefore be used directly together with POWERSIM.
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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:
- Manufacturing strategy offers a means for integrating operations management decisions and linking them with the firm's business strategy to attain a competitive position. The goal of this paper is to develop a model using System Thinking which can be utilized to better understand what constitutes manufacturing strategy, and why certain decision choices better mesh and lead to a superior competitive position. The model focuses on understanding linkages among operation management decisions which will include the decision areas of process, materials management, quality, workforce management, and maintenance.
-
- 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:
- In virtually every industrialized nation, the human services constitute the largest economic sector. Exploding costs of these services have driven many national budgets to unimaginable deficits. At the same time, there is an ever-increasing demand for health, education, corrections and other social services. Despite the proportions of this industry, there is little or no theoretical foundation for design and management of service delivery systems. Nor is there a sound conceptual basis on which public policy can be raised. This paper grows out of the increasing similarity among human services in the industrialized countries. All such services are driven by population growth and the dynamics of problem "incidence" and "prevalence". They are designed to deal with particular "case mixes" of clients through "arrays of service". The terms in quotations in the previous sentences provide examples of the language the authors use to formulate a general theoretical model of human service systems. The model design is implemented in ITHINK and is identified to human services systems in the United States. Model behavior is analyzed to illustrate general principles of delivery system design policy objectives interact over time. In this way, the model points to important insights which policy markers and human service administrators might consider in their search for solutions to social problems. Although the model in this paper is based on the peculiarities of human services in the United States, the authors make a case for wider applicability. Using health care and education examples from other countries the authors show how major propositions in the general theory are viable in widely differing context. The result is a powerful schema which can guide research, policy making and human service administration.
-
- 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:
- There is an a priori in the system dynamics paradigm which implies that the behavior of a system is tightly related to its structure. A structure specifies the relationship between the elements of the system in term of stocks and flows and feedback loops. The attempt is to explain the behavior of a system based upon the accumulation in a system and its positive and negative feedback loops. This note introduces the concept of implicit loops or pathways, as components of a major loop, to explain how changes in the behavior of a variable of the system occur over time. The note demonstrates that they presence of a negative loop (explicit or implicit) around a positive loop (explicit or implicit) is necessary in order for a system to oscillate. In particular, in explains how a pure positive major loop can oscillate.
-
- 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 paper demonstrates, in a system dynamics framework, the effects maintenance activities have on development of new software. Buoyant demand, rising backlog of work, increased delivery delay, pressure to increase programming productivity, and consequent rise in the number of defects in the software result in a fall of quality image of the company in the eye of its customers. Falling delivery delay and quality images can reverse the trend of orders. Added to this problem is the fact that the software industry today is experiencing large employee turnover. Hiring new programmers affect both productivity and quality of products. The simulation results display cyclic fluctuation of business over a 12-year period. The policy tests indicate that the policy of hiring experienced staff and of being able to retain them for a considerable length of time gives the best system behavior compared to the other policies.
-
- 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 paper suggests that the diagrammatic tools available in the system dynamics methodology are very useful to build external representation schemes for linear programming models. The paper further suggests that these tools can be used for problem conceptualization and model building. An example is cited to demonstrate the power of the system dynamics diagrammatic tools to conceptualize the problem, fix the model boundary, and define the decision variables and the constraints.
-
- 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 aim of our paper is to present a simulation model for training which enables the behaviour of the agricultural business system to be studied in the light if different scenarios and policies. We will show the potential applications of the model developed.
-
- 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 paper presents a complete study of quantitative models to optimize maintenance decisions in a company. The corrective, preventive maintenance with and without previous test are modeled and implemented for several cases. This is a new contribution within the field of maintenance, introducing the possibilities associated to the utilization of these models as a support for the maintenance planning decision making process.