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- Type:
- Document
- Date Created:
- 1986
- Collection:
- System Dynamic Society Records
- Collecting Area:
- University Archives
- Collection ID:
- ua435
- Parent Record(s):
- 8be0def879466bb233ec7ae0e7a56898, a6ba3d432669bb4e7e5d1d631a535030, and 23d738ba88f8333bc39725f9cb5bd0b8
- Description:
- Holland is a little, crowded country with (like most nations in Europe) a high degree of unemployment. On the one hand the government tries to provide an adequate amount of industrial sites in attempting not to obstruct economic growth. On the other hand this puts a high claim on the amount of scenery still extant in our country. Therefore the council of the central province in Holland asked for an investigation about the relationship between the supply of industrial sites and the influence on the increase of employment in each part of the province. As there are six employment-office area's in this province, a partition was made in six regions. Several branches of employment have quite different effects on claims for industrial sites, so there was also a division made in three economic branches. This results in eight teen equations for many of the relationships in the same form, but with different parameters. Therefore the DYNAMO - III -language was used in model-building to take advantage of the array possibility. The final result is a computer-model comprising about fifty array-equations, which allows the calculation of the area of industrial sites in different stages of development in each region and gives the spreading of employment over the province until 1995.
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- Type:
- Document
- Date Created:
- 1986
- Collection:
- System Dynamic Society Records
- Collecting Area:
- University Archives
- Collection ID:
- ua435
- Parent Record(s):
- 8be0def879466bb233ec7ae0e7a56898, a6ba3d432669bb4e7e5d1d631a535030, and 23d738ba88f8333bc39725f9cb5bd0b8
- Description:
- Fundamental to the practice of system dynamics is the identification of feedback. The theory of linear model analysis and model simplification provide tools for doing this in the setting of linear state space models. The application of these tools in the field of system dynamics has been very limited primarily because the tools are inaccessible and difficult to use. Many of the, difficulties can be overcome by linking the analysis more closely with the original nonlinear model. We do this first by using time plots of model variables to describe behavior and second by deriving a nonlinear feedback model that can be used to exhibit the important feedback structure. The theory for doing this is heuristic, but allows the techniques to be automatically applied with interaction only in the domain of the original nonlinear model and its simulation.
-
- Type:
- Document
- Date Created:
- 1986
- Collection:
- System Dynamic Society Records
- Collecting Area:
- University Archives
- Collection ID:
- ua435
- Parent Record(s):
- 8be0def879466bb233ec7ae0e7a56898, a6ba3d432669bb4e7e5d1d631a535030, and 23d738ba88f8333bc39725f9cb5bd0b8
- Description:
- The determination of parameters within a system dynamics model isan important part of the model development and validation process. There are, however, very few useful tools available for working on this. The primary reason for this lack of tools has been the difficulty of applying the theory that has been developed for full feedback estimation. Useful tools can be based upon heuristic application of much of the theory. Rules are outlined that allow the easy determination and application of filtering techniques that deal with the problem of unobservable variables. The attributes of these techniques are discussed in different settings. Application to an example serves to illustrate a number of the issues.
-
- Type:
- Document
- Date Created:
- 1986
- Collection:
- System Dynamic Society Records
- Collecting Area:
- University Archives
- Collection ID:
- ua435
- Parent Record(s):
- 8be0def879466bb233ec7ae0e7a56898, a6ba3d432669bb4e7e5d1d631a535030, and 23d738ba88f8333bc39725f9cb5bd0b8
- Description:
- Inventories of finished goods are added to the static input-output model. This addition allows one to relax the assumption that production can instantaneously track incoming orders. The reformulated input-output model exhibits production-inventory cycles over a wide range of parameter constellations. The model can be used for an extensive dynamic analysis of short-term production-inventory fluctuations in different sectors of the economy. In particular, it can be utilized to understand the extent to which each sector's fluctuations are synchronized and dependent on the fluctuations in the other sectors.The cause for the potentially oscillatory behavior of the model is analyzed. It is shown that the main reason for the oscillations lies in the assumption that the actors in the model do not know why orders are issued. They cannot distinguish whether incoming orders are issued because the recipients want to adjust their inventories or whether they are issued because the recipients have changed their long-term production plans. This result points out that one dimension of a successful stabilization policy might be an improved information policy. It is suggested that an extension of the model could be used to explain the production-inventory fluctuations during business cycles and to achieve a more detailed understanding of the behavior of different sectors during such cycles.
-
- Type:
- Document
- Date Created:
- 1986
- Collection:
- System Dynamic Society Records
- Collecting Area:
- University Archives
- Collection ID:
- ua435
- Parent Record(s):
- 8be0def879466bb233ec7ae0e7a56898, a6ba3d432669bb4e7e5d1d631a535030, and 23d738ba88f8333bc39725f9cb5bd0b8
- Description:
- The time delay θand capital life-time βof economic system must be considered in discussing the system's dynamic behaviour. In this paper a model of economic system with time lag has been proposed to deal with time delay and life-time. The core of this model is investment decision equation, in which the transfer function has been introduced. By selecting appropriate coefficients ai and bj the desired dynamic behaviour can be obtained. The impulse response h( t)of the system is defined by using numerical solution of its characteristic equation. The numerical solutions for proportional and proportional-plus-integral control system with 60 different sets of θ &βhas been calculated. According to the calculating results we use multiple regression analysis to get the regression equation between the critical oscillation parameters (period, amplification coefficient and amplitude) and time delay & life-time. It is convenient to apply these regression equations for choosing parameters.
-
- Type:
- Document
- Date Created:
- 1986
- Collection:
- System Dynamic Society Records
- Collecting Area:
- University Archives
- Collection ID:
- ua435
- Parent Record(s):
- 8be0def879466bb233ec7ae0e7a56898, a6ba3d432669bb4e7e5d1d631a535030, and 23d738ba88f8333bc39725f9cb5bd0b8
- Description:
- A new dynamic modelling methodology, SLlN, allowing for the analysis of systems defined in qualitative or quantitative terms is presented. Simulation of qualitative characteristics is performed by applying a set of logical rules which include base, tactical, strategic and structural change rules. Quantitative simulation applies traditional system dynamics concepts. To make the transition from qualitative into quantitative modes, logical rules are also used. SLIN is advantageously implemented on a very high level language such as PROLOG, as shown in this paper. To illustrate its potential applications, simple water quality models are included.
-
- Type:
- Document
- Date Created:
- 1986
- Collection:
- System Dynamic Society Records
- Collecting Area:
- University Archives
- Collection ID:
- ua435
- Parent Record(s):
- 8be0def879466bb233ec7ae0e7a56898, a6ba3d432669bb4e7e5d1d631a535030, and 23d738ba88f8333bc39725f9cb5bd0b8
- Description:
- The principal objetive of this study is to determine the production trend until 1995, taking into account the future behaviour of the variables which are involved in the explanation of the home market demand as well as exports of footwear. The forecasts have been made using a prospective model. By prospective is meant the effort involved to imagine the different futures which may be caused by the behaviour of the "actors" within the logial limits of the systems through which they act. In this paper a distinction is made between the variables whose dynamics are almost always constant and those which may be affected by the decision of the 'actors' or by unforesceable events. The prospective study seeks to understand the plans which the actos will try to carry out and will affect its future behaviours.These options become especially clear in the construction of partial or complete scenario. Scenario, according to the definition of Fontela (1980) is the script of a theatrical work about the future in which economic and social agents would be involved. To construct a scenario for the future is a creative task in which, implicitly or explicitly, all long-term decision makers play a part.Hence to study a scenario of the development in the next decade is to analyse one of the potential futures, being fully aware of the essentia1 unpredictabi1ity of the future and of our full freedom of choise.
-
- Type:
- Document
- Date Created:
- 1986
- Collection:
- System Dynamic Society Records
- Collecting Area:
- University Archives
- Collection ID:
- ua435
- Parent Record(s):
- 8be0def879466bb233ec7ae0e7a56898, a6ba3d432669bb4e7e5d1d631a535030, and 23d738ba88f8333bc39725f9cb5bd0b8
- Description:
- In the evolving terminology within the field of system dynamics, a "molecule" is the smallest combination of structural elements ("particles" and "atoms") necessary to represent a basic systems concept. A generic structure is the next largest combination of particles, atoms and molecules that conveys the most (or a) general form in which that concept can be identified in and/or represented for real systems. This paper proposes both a molecule and a generic structure for synergy.
-
- Type:
- Document
- Date Created:
- 1986
- Collection:
- System Dynamic Society Records
- Collecting Area:
- University Archives
- Collection ID:
- ua435
- Parent Record(s):
- 8be0def879466bb233ec7ae0e7a56898, a6ba3d432669bb4e7e5d1d631a535030, and 23d738ba88f8333bc39725f9cb5bd0b8
- Description:
- The main purpose of this work is to study the role of the women in different levels of business management. The system under study is composed of: a)business sector, in which women carry out their activities, b) educational subsystem, which provides them with the necessary skills to ascend to different managerial positions, c) cultural and socioeconomic conditions of the country, which influence : the motivation of women for this kind of work, the entrepreneurial attitude to hiring females in firms.The characteristics of the system together with the pursued objective bring us to the choice of System Dynamics as the most adequate method for our study. Using as our starting point a causal diagram of the global system, we have divided it in sectors. These represent the different aspects above mentioned. This is a long-term project from which we hope to obtain partial results to be presented in the 1986 System Dynamics Conference.
-
- Type:
- Document
- Date Created:
- 1986
- Collection:
- System Dynamic Society Records
- Collecting Area:
- University Archives
- Collection ID:
- ua435
- Parent Record(s):
- 8be0def879466bb233ec7ae0e7a56898, a6ba3d432669bb4e7e5d1d631a535030, and 23d738ba88f8333bc39725f9cb5bd0b8
- Description:
- This paper examines the causes and effects that interact to determine the rate the causes and effects that of Systems Dynamics diffusion. The use of Systems Dynamics implies both a way of conceptualizing the models of existing systems and the use of such models to gain a better understanding of the systems' behaviour.Given the high potential of Systems Dynamics to aid in understanding a very wide variety of systems in many areas of human endeavour the Systems Dynamics practitioners worry regularly about its slow propagation and frequently express anxiety about the future of the field. They tend to forget, however, that the potential usefulness of their approach is obvious to them but is hard to appreciate by the would be users and eventual beneficiaries of the improved solutions derived from applications of their expertise.This paper focuses on the causes and effects that in the authors' opinion interact in the diffusion of Systems Dynamics and suggests actions that may eventually help to accelerate the process of its broad adoption.