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- Type:
- Document
- Fecha de Creacion:
- 1984
- Collection:
- System Dynamic Society Records
- Collecting Area:
- University Archives
- Collection ID:
- ua435
- Parent Record(s):
- dcf80aca09fd0af264c0472357441115, 23d738ba88f8333bc39725f9cb5bd0b8, and 6e5cbea1fd05527880f389afd8fb85d1
- Descripción:
- Using System Dynamics as the primary tool of investigation, an attempt has been made in this paper to present (i) a general model of commodity price fluctuation, (ii) a price stabilization policy based on buffer stock, and (iii) the impact of this policy on the long term growth of the commodity industry. The model has been tested for the case of Indian Tea.Average unit cost of the commodity at the point of sale, operating profit margin desired by the sellers (computed on the basis of average quality of supply), actual inventory, and the average sales rate are considered as the chief determinants of the commodity price. Circular relationships among these variables have been considered to generate the price fluctuation over time. While testing the price stabilization policy, the model considers its operation phase. It is shown in this paper that such a price stabilization policy tremendously boosts the overall long term growth of the industry.
-
- Type:
- Document
- Fecha de Creacion:
- 1984
- Collection:
- System Dynamic Society Records
- Collecting Area:
- University Archives
- Collection ID:
- ua435
- Parent Record(s):
- dcf80aca09fd0af264c0472357441115, 23d738ba88f8333bc39725f9cb5bd0b8, and 6e5cbea1fd05527880f389afd8fb85d1
- Descripción:
- The System Dynamics model described in this paper presents a new approach to the mechanisms of subcutaneous absorption of dissolved insulin. Experimental investigations have shown that the apparent absorption constant varies in time, and that this variation depends both on the volume and the concentration of the injected insulin. Our model assumes that insulin is present in the subcutaneous depot in three forms: (i) a dimeric form, (ii) a hexameric form, and (iii) an immobile form in which the molecules are bound in the tissue. The model describes how diffusion and absorption gradually reduce the insulin concentrations and thereby shift the balance between three forms according to usual laws of chemical kinetics. By assuming that only dimeric molecules can penetrate the capillary wall, we have found that the model can fully account for the observed variations in the absorption rate. At the same time the model can be used to determine at least 5 parameters characterizing the involved processes: the diffusion constant for insulin in the subcutaneous tissue, the absorption constant for dimeric insulin, the equilibrium constant for the dimeric/hexameric polymerization process, the binding capacity for the insulin in the tissue, and the average life time for insulin in bound state. Combined with a simplified model of the distribution and degradation of insulin in the body, the diffusion-absorption model has been used to simulate different insulin delivery schedules, i.e. a single major injection contra dosage with infusion pump. The model has shown that a pump repetition frequency of 1-2/hr can secure a sufficiently constant plasma insulin concentration.
-
- Type:
- Document
- Fecha de Creacion:
- 1984
- Collection:
- System Dynamic Society Records
- Collecting Area:
- University Archives
- Collection ID:
- ua435
- Parent Record(s):
- dcf80aca09fd0af264c0472357441115, 23d738ba88f8333bc39725f9cb5bd0b8, and 6e5cbea1fd05527880f389afd8fb85d1
- Descripción:
- This paper examines the dynamics of “worker burnout”, the process in which a hard-working individual becomes increasingly exhausted, frustrated, and unproductive. The author’s own two-year experience with repeated cycles of burnout is qualitatively reproduced by a small system dynamics model which portrays the underlying psychology of “workaholism”. Model tests demonstrate that the limit cycle seen in the base run can be stabilized through techniques which diminish work related stress or enhance relaxation. These stabilizing techniques also serve to raise overall productivity, since they support a higher level of energy and more working hours on average. One important policy lever is the maximum workweek or “work limit”; an “optimal work limit” at which overall productivity is at its peak is shown to exist within a region of stability where burnout is avoided. The paper concludes with a strategy for preventing burnout which emphasizes the individual’s responsibility for understanding the self-inflicted nature of this problem and pursuing an effective course of stability.
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- Type:
- Document
- Fecha de Creacion:
- 1984
- Collection:
- System Dynamic Society Records
- Collecting Area:
- University Archives
- Collection ID:
- ua435
- Parent Record(s):
- dcf80aca09fd0af264c0472357441115, 23d738ba88f8333bc39725f9cb5bd0b8, and 6e5cbea1fd05527880f389afd8fb85d1
- Descripción:
- The scope of this paper is to present our views on teaching System Dynamics and Dynamo in our courses in System Analysis at Uppsala University. We treat the pedagogical aspects as well as the hardware and software system we built around Dynamo. A large part of this article is devoted to ideas and constructive criticism of System Dynamics and Dynamo which we have acquired from our experiences in education and research.
-
- Type:
- Document
- Fecha de Creacion:
- 1984
- Collection:
- System Dynamic Society Records
- Collecting Area:
- University Archives
- Collection ID:
- ua435
- Parent Record(s):
- dcf80aca09fd0af264c0472357441115, 23d738ba88f8333bc39725f9cb5bd0b8, and 6e5cbea1fd05527880f389afd8fb85d1
- Descripción:
- The System Dynamics National Model is a large computer simulation model of a typical industrialized economy, with its parameters adjusted to reflect the size and character of the United States. The model's purpose is twofold: understanding the major difficulties of the aggregate economy such as inflation, business cycles, and slowing productivity growth; and to facilitate the evaluation of policies to influence those behaviors. In the existing publications on results from the National Model, the structure of the model is described in a page or two, doing no more than supplying a flavor for the scope of the model. This paper goes to the next stage in describing the content and structure of the model for those readers with some previous exposure to the results of the National Model research. The discussion starts with the overall architecture, then goes through the major connections among the sectors of the model, and concludes with one example of more detailed structure: the interrelations among selected decisions in the corporate sector of the model.
-
- Type:
- Document
- Fecha de Creacion:
- 1984
- Collection:
- System Dynamic Society Records
- Collecting Area:
- University Archives
- Collection ID:
- ua435
- Parent Record(s):
- dcf80aca09fd0af264c0472357441115, 23d738ba88f8333bc39725f9cb5bd0b8, and 6e5cbea1fd05527880f389afd8fb85d1
- Descripción:
- The paper describes eight problems within the Cable Division of Standard Telefon og Kablefabrik A/S which are currently being analyzed using system dynamics. Problem 7, concerned with information system projects, is described in detail.
-
- Type:
- Document
- Fecha de Creacion:
- 1984
- Collection:
- System Dynamic Society Records
- Collecting Area:
- University Archives
- Collection ID:
- ua435
- Parent Record(s):
- dcf80aca09fd0af264c0472357441115, 23d738ba88f8333bc39725f9cb5bd0b8, and 6e5cbea1fd05527880f389afd8fb85d1
- Descripción:
- A generic model of adaptive systems behaviour is developed in causal loop form. Examples from many different living systems are given. Living systems do adapt: plants turn towards the light; birds fly south in the winter; people acquire a taste for champagne; revolutionaries become government bureaucrats; and cultures have dealt with horseless carriages and jet travel. Living systems also collapse: lakes get polluted and die; dinosaurs are no more; people commit suicide; there is no more Federalist party; and the Indian Nations of North America have all disappeared. As a system dynamist I am interested in the attribute or, more exactly, the minimal set of attributes of all these systems that can explain the capability to adapt and also the obvious limits to that same capability.
-
- Type:
- Document
- Fecha de Creacion:
- 1984
- Collection:
- System Dynamic Society Records
- Collecting Area:
- University Archives
- Collection ID:
- ua435
- Parent Record(s):
- dcf80aca09fd0af264c0472357441115, 23d738ba88f8333bc39725f9cb5bd0b8, and 6e5cbea1fd05527880f389afd8fb85d1
- Descripción:
- The acronym “MDS” refers to the methodology and a series of computing techniques which are suitable for the simulation of corporate processes. These “Dynamic Models for Corporate Strategies” allow the description of such processes as structures of a unified nature, into which one may insert all the necessary data (real or hypothetical) deriving from the initial and boundary conditions, to clearly define the possible future developments being studied. With respect to other, currently available, decisional aids, MDS differs both by its purely simulative approach and by its use of the basic descriptive structure capable of completely representing the dynamism of corporate phenomena. Compared to a “company microcosm” description using the now classical methods of Industrial Dynamics, MDS offers open and interactive systems also introducing several “corporate variants”. (These correspond both to certain types of sub-division of the complete system into given sub-system, and to relationships which may also be described in the same terms, such as the ‘accounts plan’, for example). The main aim of this paper is to analyse the effects of promotional activity- recently developed in Italy amongst medium and large companies- whose main objective is the introduction of MDS as an imprtant instrument in the practice of corporate planning.
-
- Type:
- Document
- Fecha de Creacion:
- 1984
- Collection:
- System Dynamic Society Records
- Collecting Area:
- University Archives
- Collection ID:
- ua435
- Parent Record(s):
- dcf80aca09fd0af264c0472357441115, 23d738ba88f8333bc39725f9cb5bd0b8, and 6e5cbea1fd05527880f389afd8fb85d1
- Descripción:
- The System Dynamics National Model represents a typical, modern, industrial economy. Although parameters have been chosen for the United States, the behavior modes exhibited by the model are those being experienced in most economies in Western developed countries. The National Model incorporates a wide range of dynamic structures that allow its behavior to span from the short-term business cycle of 3-to-7 year periodicity to the much longer-term behaviors represented by growth and by major depressions that recur at intervals of some fifty years. The System Dynamics National Model has been under development for about twelve years. An evolutionary process has been followed during which we have extended the scope of the model, added sectors, identified and corrected misbehavior, and simplified unnecessarily complex structures. There have been more than a thousand modifications and extensions of the Model. The National Model is now close to meeting our primary objectives, and we have started writing four books describing the Model and its implications for economic behavior.
-
- Type:
- Document
- Fecha de Creacion:
- 1984
- Collection:
- System Dynamic Society Records
- Collecting Area:
- University Archives
- Collection ID:
- ua435
- Parent Record(s):
- dcf80aca09fd0af264c0472357441115, 23d738ba88f8333bc39725f9cb5bd0b8, and 6e5cbea1fd05527880f389afd8fb85d1
- Descripción:
- The interaction between the speaker and his audience is a subject of universal interest, especially to professionals. It is a subject, moreover, requiring a dynamic method of analysis. This paper presents a conceptual model of public speaking. The purpose of this preliminary study is to identify the essential factors needed for (1) the effective delivery of a prepared speech in a conversational manner and (2) the growth of the speaker's abilities over time. As a result of my preliminary analysis of the feedback loops operating during a technical presentation, my approach to teaching novice speakers has changed. One benefit of my new approach is that it accelerates the process by which novices develop the competencies they need to give successful informative speeches. Further study of the interaction between speaker and audience using System Dynamics will contribute significantly to our understanding of human communication.
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