Showing papers by "International Institute for Applied Systems Analysis published in 1981"
TL;DR: In this article, an ensemble of acceptable parameter vectors for the model is identified by reference to a partly qualitative and somewhat vague definition of system behaviour in terms of allowable ranges, and then used for the simulation of a multitude of future systems behaviour patterns, so that the uncertainty in the initial data and assumptions is preserved, and thus the predicted future systems response can be interpreted in a probabilistic manner.
78 citations
TL;DR: The current state of the work in the Public Facility Location Task (formerly the Normative Location Modeling Task) at IIASA has three main aims: first, to build a general framework for location problems; second, to use this framework to unify existing location models; and, third, to develop new, more general, and more meaningful location models.
Abstract: This paper, a condensed report of the present state of the work in the Public Facility Location Task (formerly the Normative Location Modeling Task) at IIASA, has three main aims: first, to build a general framework for location problems; second, to use this framework to unify existing location models; and, third, to use the framework to develop new, more general, and more meaningful location models. Suggestions are also given on how to introduce multiple services and multiple time periods in location problems. The multiactivity dynamic location models that this perspective generates is the subject of future research in the Public Facility Location Task. This first part of the paper gives a nontechnical description of the proposed general framework for analyzing location problems. The second part will describe mathematical models for static, single-service, facility location problems and their possible extensions and improvements, and will appear in the next issue.
74 citations
TL;DR: The second part of a two part description of the modelling activities associated with the Bedford Ouse Study, concentrates on the theme of water quality modelling as mentioned in this paper, where recursive estimation techniques such as the extended Kalman filter have been applied to daily water quality data to determine models for dissolved oxygen, biochemical oxygen demand, chloride and nitrate.
48 citations
TL;DR: In this paper, the authors describe mathematical models for static, single-service, facility location problems and their possible extensions and improvements, and give a non-technical description of the proposed general framework for analyzing location problems.
Abstract: This second part of the paper describes mathematical models for static, single-service, facility location problems and their possible extensions and improvements. The first part that appeared in the last issue (pages 1001–1028) gave a nontechnical description of the proposed general framework for analyzing location problems.
42 citations
TL;DR: The paper argues, in particular, that there is an intimate relationship between prediction and model calibration, which is especially important in accounting for uncertainty in the development and use of models.
34 citations
TL;DR: In this article, it was shown that the Alonso model is equivalent to one of Wilson's four standard models depending on the assumption at the outset about which of the total outflows and/or inflows are known.
Abstract: This paper compares the system of equations underlying Alonso's theory of movement with that of Wilson's standard family of spatial-interaction models. It is shown that the Alonso model is equivalent to one of Wilson's four standard models depending on the assumption at the outset about which of the total outflows and/or inflows are known. This result turns out to supersede earlier findings—inconsistent only in appearance—which were derived independently by Wilson and Ledent. In addition to this, an original contribution of this paper—obtained as a byproduct of the process leading to the aforementioned result—is to provide an exact methodology permitting one to solve the Alonso model for each possible choice of the input data.
32 citations
TL;DR: In this paper, the authors examined the feasibility and discusses the potential of applications of on-line real-time state estimation and prediction in operational control of the activated sludge process, in particular, the dynamics of nitrification are considered with reference to the activation unit at the Norwich Sewage Works in eastern England.
27 citations
TL;DR: Using four detailed and complex simulation models, a framework for predicting behavior of any defoliating insect/forest system is derived and four qualitatively different classes of system behavior arise from the equilibrium structures.
Abstract: Using four detailed and complex simulation models we derive a framework for predicting behavior of any defoliating insect/forest system. The framework uses simple and easily gathered biological information on four sets of state variables, each with a characteristic temporal scale, to predict presence, absence or form of key ecological processes acting on or between the variables. The combination of these key processes enables prediction of system equilibrium structure and this structure can be used to derive the temporal behavior of the system. Four qualitatively different classes of system behavior arise from the equilibrium structures.
The framework is tested against twelve other systems and field invalidation experiments are outlined. Forest defoliator research and management implications are discussed.
25 citations
01 Apr 1981
TL;DR: The author analyzes the stochastic process describing the marginal expected value of perfect information (EVPI) about the future of the system and demonstrates two intuitively obvious properties of this marginal EVPI process: its values are completely predictable at each actual decision point and its expected values tend to decline over the future.
Abstract: Methodological research into optimization problems and techniques has a long history in the System and Decision Sciences Program at IIASA. Most recently, effort -- of which this paper forms a part -- has concentrated on the analysis of stochastic systems.
For a very general model of a stochastic optimization problem with an infinite planning horizon of discrete time, the author analyzes the stochastic process describing the marginal expected value of perfect information (EVPI) about the future of the system. He demonstrates two intuitively obvious properties of this marginal EVPI process: that its values are completely predictable at each actual decision point and that its expected values tend to decline over the future since information is potentially worth more the sooner it is available. The author is currently working on continuous time analogs of these results, which are unfortunately fraught with technical difficulties.
This work should be viewed as a theoretical prolegomenon to computational studies aimed at estimating the value of perfect or partial information in the control of stochastic systems. The central observation here is that the extra complexity and computational burden of introducing random parameters into planning or control models may sometimes be unnecessary. The (marginal) EVPI at decision points is the natural measure by which their modeling efficacy can be evaluated.
24 citations
TL;DR: In this article, a mathematical formulation of a multi-objective trajectory optimization problem is presented, with an interpretation as a semi-regularization procedure for ill-posed problems, and examples of actual applications.
23 citations
TL;DR: In this article, it was shown that the ambiguous conclusions of Freeman and Schmalensee about the sign of option value are the result of two special strong assumptions not imposed by Schmalense.
TL;DR: A 1976 Social Accounting Matrix for Egypt is presented and the methods of estimation used are described briefly as mentioned in this paper, some of the implications of the accounting are discussed and the information on the distribution of taxes and subsidies indicates that the latter are the major source of progressiveness in the fiscal system.
TL;DR: This article presented a new argument for the convergence of the age structure, one that is self-contained, and that brings the mechanism behind convergence into full view, and showed that population dynamics define a smoothing or averaging process over the generations, a process comfortable to our intuition.
Abstract: A large part of mathematical demography is built upon one fundamental theorem, the "strong ergodic theorem" of demography. If the fertility and mortality age-schedules of a population remain unchanged over time, its age distribution, no matter what its initial shape, will converge in time to a fixed and stable form. In brief, when demographic behavior remains unchanged, the population, it is said, converges to stability.
This short paper presents a new argument for the convergence of the age structure, one that is self-contained, and that brings the mechanism behind convergence into full view. The idea is simple. Looked at directly, the dynamics of the age-distribution say little to our normal intuition. Looked at from a slightly different angle though, population dynamics define a smoothing or averaging process over the generations -- a process comfortable to our intuition. This smoothing and resmoothing turns out to be the mechanism that forces the age structure toward a fixed and final form.
TL;DR: An integrated model is proposed to capture economic and demographic interactions in a system of regions via functions describing consumption and migration patterns and migration rates are determined jointly with labor force participation rates and unemployment rates.
Abstract: An integrated model is proposed to capture economic and demographic interactions in a system of regions. This model links the interregional economic model of Isard (1960) and the interregional demographic model of Rogers (1975) via functions describing consumption and migration patterns. Migration rates are determined jointly with labor force participation rates and unemployment rates. (EXCERPT)
TL;DR: A method is described for the automatic calculation and graphical reproduction of isochrones around emergency medical centers in large cities that permits a rapid evaluation of coverage standards under different operating conditions.
Abstract: A method is described for the automatic calculation and graphical reproduction of isochrones around emergency medical centers in large cities. The isochrones are set for different time standards and for varying traffic conditions. The technique is based on the concept of a velocity field. It permits a rapid evaluation of coverage standards under different operating conditions.
TL;DR: In this article, the authors present a multiregional optimization model for the allocation of private and public investment, production, employment, and population over economic sectors and regions by choosing appropriate objective functions, the model may be used for either planning or forecasting purposes.
TL;DR: This paper examines ORASA by describing and then qualifying seven 'near-truths' about the subject; each is sufficiently accurate to be accepted by many OrASA practitioners, but equally each contains the seeds of dangerous misconceptions and distortions if its limitations are not recognized.
TL;DR: An integration of feedforward and feedback control loops is developed in order to meet the specific characteristics of a system in which "environment" can be viewed as the "input," and to provide the adaptive, learning capability which is required by the situation of insufficient data, ignorance of underlying mechanisms, and continuing change.
Abstract: After a brief review of the nature of strategic planning, and the problem of defining health service objectives, the paper concentrates on the question of decision making and "strategic control," in the context of a regional health authority, a system at the level of the organization. The purpose of monitoring is defined in detail. A critical review of concepts of control in various disciplines considers their suitability to the health authority context. An integration of feedforward and feedback control loops is developed in order to meet the specific characteristics of a system in which "environment" can be viewed as the "input," and to provide the adaptive, learning capability which is required by the situation of insufficient data, ignorance of underlying mechanisms, and continuing change.
TL;DR: In this article, an accelerator-supported decentralized system of small nuclear heat sources characterized by versatility and long-term sustainability is investigated, where neutrons produced by high energy proton-induced spallation reactions are used both for repeated in-situ rejuvenation of spent nuclear fuel and for the reduction of nuclear waste by fission product transmutation.
TL;DR: The methode dite de '' l'amalgame '' prevue par la loi for repartir entre les provinces les sieges au Parlement canadien.
Abstract: Cet article explique en termes strictement operatoires la methode dite de » l'amalgame « prevue par la loi pour repartir entre les provinces les sieges au Parlement canadien.
L'histoire politique canadienne et le sens commun suggerent quelques principes fondamentaux d'equite qui devraient s'appliquer a toute methode de repartition des sieges an Parlement. Malheureusement, le methode de l'amalgame ne repond a aucun de ces principes.
Il y a une seule methode qui reponde a tons ces criteres: elle est beaucoup plus simple que celle de l'amalgame, et c'est fondamentalement la methode originellement incorporee a l'Acte de l'Amerique du Nord Britannique de 1867.
Cet article explique en termes strictement operatoires la methode dite de » l'amalgame « prevue par la loi pour repartir entre les provinces les sieges au Parlement canadien.
L'histoire politique canadienne et le sens commun suggerent quelques principes fondamentaux d'equite qui devraient s'appliquer a toute methode de repartition des sieges an Parlement. Malheureusement, le methode de l'amalgame ne repond a aucun de ces principes.
Il y a une seule methode qui reponde a tons ces criteres: elle est beaucoup plus simple que celle de l'amalgame, et c'est fondamentalement la methode originellement incorporee a l'Acte de l'Amerique du Nord Britannique de 1867.
TL;DR: The International Institute for Applied Systems Analysis (IIASA) in Laxenburg, Austria as mentioned in this paper assessed the potential of liquid fuels for the next fifty years and found that the world needs from 100 to 160 × 10 6 BPD (barrels per day) of liquid fuel.
TL;DR: In this paper, the authors deal with the socioeconomic dimension of creativity in technology organization and economy, and they find evidence that creativity is a wasted resource in the development of social systems, but they also identify obstacles to creativity in the following stages: formation of creative personalities, creation period, and realization period.
Abstract: This paper deals with the socioeconomic dimension of creativity in technology organization and economy. Creativity is decisive for the development of social systems, but one finds evidence that creativity is a wasted resource. Obstacles to creativity have been identified over the following stages: formation of creative personalities, creation period, and realization period; and on four levels: growth of productive forces, economic relations and interests, institutions, and mental or ideological factors. World, society, organizations, groups, and individuals and their interaction are the objects of social creativity research. Measurement of creativity in the stages research, development, and introduction and improvement uses four dimensions: results, process, personal characteristics, and level of participation. Creativity is closely connected with its counterpart: routine experience. In an organization the innovation potential plays an important role, together with such determinants as strategic orientation, capacity for current production operations, and level of cooperation and coordination.
TL;DR: In this paper, the authors report on methodology and results of a study of the economic consequences of a discontinuation of the Swedish nuclear program by means of a computable general equilibrium model and is focused on the impact on real income as well as on the sectoral allocation of production and employment.
01 Jan 1981
TL;DR: In this article, the authors introduce concepts useful in the application of O.R. to strategic problems and apply them to the resolution of two contemporary issues in European integration: economic expansion to maintain employment, and problems of polarisation and regional imbalance.
TL;DR: An exploratory study was carried out as a collaborative effort between IIASA and several external institutions as discussed by the authors, aimed at generating a methodological outline of a multidisciplinary approach to the problem in order to provide practical prospects for dealing with nitrate pollution of water resources caused by agricultural activities.
Abstract: An exploratory study was carried out as a collaborative effort between IIASA and several external institutions. The study was aimed at generating a methodological outline of a multidisciplinary approach to the problem in order to provide practical prospects for dealing with nitrate pollution of water resources caused by agricultural activities. Main ideas of the methodological outline and a related Task Force Meeting are summarized.
TL;DR: An approach is described which permits the investigation of a set of linked subsystems without explicitly building any integrated model, based on the smooth version of the sequential unconstrained minimization techniques (SUMT).
Abstract: The problem of computer linkage of different mathematical models into a whole system in order to investigate their joint behavior with more common criteria and constraints seems to receive more and more consideration. Many works on analyzing the behavior of complex systems are based on building large-scale integrated models and sequentials using decomposition and aggregation procedures. In this article an approach is described which permits the investigation of a set of linked subsystems without explicitly building any integrated model.
This article represents a description of a particular approach which might be referred to as "distributed modeling". It deals with conceptual systems in general, which might be used to model concrete systems at any level. The use of the method is illustrated by the practical application of the development of a system of regional models. This approach, based on the smooth version of the sequential unconstrained minimization techniques (SUMT), can be considered from a mathematical point of view as realization of the general decomposition scene.
01 Jan 1981
TL;DR: In this paper, the authors present an algorithm for providing an easy way of obtaining the solution of the initial primal problem keeping all advantages of the dual one, which is the main idea of this paper.
Abstract: Partial or complete dualization of extremum problems often allows the decomposition of initially large-scale problems into smaller ones with some coordinating program of a moderate size This idea underlies many known schemes of decomposition and the common difficulty often encountered is the problem of restoring the solution of the primal problem The main idea of this paper is to present an algorithm for providing an easy way of obtaining the solution of the initial primal problem keeping all advantages of the dual one
01 Jan 1981
TL;DR: In this article, a scale model of the area in a hydrodynamic tank has been built in order to both analyze the dynamic and thermodynamic structure of the air flow and to study air pollutants dispersion.
Abstract: Field surveys have been done in the La Spezia complex site and a scale model of the area in a hydrodynamic tank has been built in order to both analyze the dynamic and thermodynamic structure of the air flow and to study air pollutants dispersion. Results from the field experiments made it possible to describe relevant meteorological processes such as formation of sea and land breezes, evolution of the diurnal and nocturnal inversion and others. The physical model proved to simulate the air flow of the site in satisfactory agreement with the observations. Hence, it was also operated to simulate dispersion of air pollutants under different air flow regimes. In spite of the high scale factors, the hydraulic model gave realistic simulations of the hourly average ground level concentration caused by the local thermal power plant. The physical model was then complemented by a Gaussian model in order to simulate the seasonal air pollution trend. The parameterization of the Gaussian climatological model was done by taking into account the results from the field experiments. Validation of the model through comparison with measured values over eight seasons showed that the adopted parameterization was relevant to the achievement of a satisfactory agreement with the observations and that the Gaussian model could integrate the physical model in the establishment of air quality strategies in the considered area.