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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 production of cement pays the most important role in all the construction activities in the country. Due to rapid growth in the industrialisation and the development there is fast growing internal demand of cement. However, cement industry in India has not been able to cope up with the demand. Therefore, it is essential to study the demand and production aspects in order to evolve strategies to meet the demand. For this purpose, a System Dynamics model for cement production is developed. The production model is run for 16 years covering a period from 1974 to 1990 at three conditions, such as basic, optimistic and pessimistic. The different sensitivity runs are also carried out by changing the different parameters influencing the production. Different scenarios are generated and the gap between demand and production is analysed at different conditions. It is observed that this gap is closed under certain conditions.
-
- 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:
- In order to study the long term behaviour of complex systems, such as industrial enterprises, it is necessary to use reduced models with a limited number of variables. Here we investigate theoretically the relationship between these “mesoscopic” models and more detailed, “microscopic” models of the same physical systems. When the relevant variables evolve more slowly than the irrelevant degrees of freedom, a powerful projection technique is presented (Adiabatic Elimination Procedure). A pedagogical example is discussed, dealing with a large company in the field of computer science, which wants to increase its presence in a particular market segment by starting a cooperation with a small but aggressive company, already in that market segment.
-
- 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 summarizes the purpose, design, and initial results of the New Management Style Project.
-
- 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:
- Businessmen, bankers, private citizens, and government officials share deep concerns over the high values of interest rates in today’s economy. Of particular concern has been real interest rate, the rate of interest adjusted for inflation. Although nominal interest rates have followed a generally declining trend over the past year, this decline has generally lagged declining inflation and has failed to keep pace with the drop in inflation. This paper is the first of two on the problem of high real interest rates. It focuses on developing a theoretical framework for understanding the role played by real interest rates in the long wave. The second part of the study will focus on the effects of government deficits and alternative monetary policies. The primary purpose of this study is to show that the downturn of the long wave can cause rising real interest rates even with no government deficit or change in monetary policy.
-
- 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 methodology which this article deals with, is the fruit of the experience gathered thanks to the contributions of experts in the fields of programming, personnel and organisation. The willingness of such people has given rise to the instruments now available in the field of Industrial Dynamics. It is thus possible to design a methodology and simulation models which, with the help of a computer, offer an instrument which can answer the needs of those involved in the planning of human resources in a company environment. This model has so far been applied with satisfactory results in two technically different realities. At the present time, other applications are in progress which confirm the validity of this instrument.
-
- 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:
- There is a conspicuous gap in the literature about feedback and circular causality between intuitive statements about shifts in loop dominance and precise statements about how to define and detect such important nonlinear phenomena. This paper provides a consistent, rigorous, and useful set of definitions of loop polarities, dominant polarity, shift in dominant polarity, and shift in loop dominance, and illustrates their application in a range of system dynamics models. Consistent with the usual intuitive definitions, the polarity of a first-order feedback loop involving a level x and a single inflow ẋ is defined to be the sign dẋ/dx. Loop polarity is shown to depend upon the sign of parameters not usually considered part of the loop itself. This expression of loop polarity is then applied to multi-loop first-order systems to define the polarity of such systems. All positive loops with gain less than one, such as economic multipliers, are shown to be multi-loop systems with dominant negative polarity. The shifts in loop dominance that occur in nonlinear systems arise naturally as changes in the sign of the dominant polarity. Examples applying the notion of dominant polarity reveal a useful geometric characterization of shifts in loop dominance in nonlinear first-order systems. The concepts developed in the paper are then applied to simple higher-order nonlinear feedback systems. The final application to a bifurcating system suggests that all bifurcations in continuous systems can be understood as consequences of shifts in loop dominance at equilibrium points.
-
- 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 presents a total stability analysis of a simplified Kondratieff-wave model. The purpose is to show how such an analysis can be carried out and to illustrate the kind of information one obtains. For normal parameter values the Kondratieff wave model has a single unstable equilibrium point. Combined with non-linear constraints in the model's table-functions, this instability creates a characteristic limit cycle behavior. For other parameter values, however, the model is stable and generates damped oscillations instead of the limit cycle. For yet other combinations of parameters, the non-linear constraints yield to the instability, and sustained exponential growth or total collapse result. By means of linear stability analysis we first determine the conditions for the transition between a stable and an unstable equilibrium to take place. This transition is known as a Hopf-bifurcation. Using global analysis we outline the phase-portrait of a fully developed limit cycle. By the same method, we examine the conditions under which the non-linear functions fail to contain the system so that exponential run-away or collapse occur. A DYNAMO-program is then developed which calculates the Lyapunov exponents of the system during a simulation, and we discuss how these exponents can be used as a measure of the divergence or convergence of nearby trajectories. Finally, we illustrate how subsequent period doublings and chaotic behaviour can occur if the model is driven exogenously by a weak sine-wave, representing for instance the short term business cycle.
-
- 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:
- During the summer of 1982 the author made predictions of wood pulp prices for the period 1982 to 1986. The predictions were part of a decision on whether to sell a large pulping plant in Norway. This paper presents the predictions and the basis on which they were made. Next, the predictions are compared with actual data for the period 1982 to 1984.
-
- 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 dynamic simulation model of the Indian economy has been developed which captures the important linkages between economic growth and the development of various forms of energy. Non-commercial forms of energy which supplied the bulk of total energy requirements of the economy so far have clearly reached their saturation limits. Capital costs for coal and petroleum increase with resource depletion. The cost of hydroelectricity increases as the cheaper and more accessible resources are exhausted. The costs of renewable energy sources such as solar, wind and biomass decrease with cumulative production due to technical progress. Such sources of energy become more important sources in the future though their current share of the total energy production is negligible. The thesis examines the dynamics of the transition to the new era as well as responses of the economy to energy shocks such as steep increases in international oil prices. It investigates the possibility of an interim crisis if the domestic energy industry is slow to develop or if the response of energy demand to rising energy prices is sluggish. Such a difficult transition may be marked by persistent import dependence, high energy prices and high outlays in the energy sectors that reduce the resources available to the non-energy sectors for consumption and growth. An aggregate production function utilizing capital, labour and energy as factor inputs has been utilized for the economy along with a neo-classical formulation for consumption and saving in the economy. The model generates the energy demand of the economy endogenously and incorporates the adaptation of energy intensity to rising real energy prices through more efficient new capital equipment as well as retrofits of inefficient equipment. The model has been calibrated using Indian data. Where parameters or assumptions are based on uncertain facts, sensitivity tests have been carried out. The effect of government policies such as taxation of energy or emphasis on conservation have been investigated.
-
- 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 emergence of powerful personal computers and CAD/CAM machines offers a new opportunity for DYNAMO. Although users are generally satisfies with the language, a survey shows they want expanded simulation capabilities including single simulations, eigenvalue analysis, sensitivity analysis, and the optimization by multiple simulation and hill climbing. Novices want easier access to models and simulation. The modular version of DYNAMO now in development will meet these goals. It will break DYNAMO’s normal functions into separate programs that users can reassemble in different ways. For example, one compiler will translate both conventional models and games. The simulation controller will work with a regular rerun, a game, or a sensitivity analysis package. The report generator will display output from any of these packages. These modules will communicate through standard data files, which users can also access for other purposes such as statistical analysis.