- Dr. Alexander H. Levis is University Professor Emeritus of Electrical and Computer Engineering in the Volgenau School... moreDr. Alexander H. Levis is University Professor Emeritus of Electrical and Computer Engineering in the Volgenau School of Engineering, George Mason University. He was educated at Ripon College where he received the AB degree (1963) in Mathematics and Physics and then at MIT where he received the BS (1963), MS (1965), ME (1967), and Sc.D. (1968) degrees in Mechanical Engineering with control systems as his area of specialization. For the last ten years, his areas of research have been multi-formalism modeling to address national security strategic issues, architecture design and evaluation, and resilient architectures. He is a Life Fellow of IEEE, a Fellow of AAAS, and INCOSE, and an Associate Fellow of AIAA. From 2001 to 2004 he served as the Chief Scientist of the US Air Force.edit
In this section, the IEEE Control Systems Society publishes reviews of books in the control field and related areas. Readers are invited to send comments on these reviews for possible publication in the Technical Notes and Correspondence section of this TRANSACTIONS. The S-CS does not necessarily...more
16. OISTKISUTION STATEMENT /of!his Report) Approved for public release, distribution unlimited 7 DISTRIBUTION STATEMENT (0f the abstrc entered in Bock 20. it different from Report) DI E FLECTE FERt "- 11E 'I E(Y NORDS (Continue... more
16. OISTKISUTION STATEMENT /of!his Report) Approved for public release, distribution unlimited 7 DISTRIBUTION STATEMENT (0f the abstrc entered in Bock 20. it different from Report) DI E FLECTE FERt "- 11E 'I E(Y NORDS (Continue in reverie side if ncesaerY and identify by block number)
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Résumé/Abstract Science descriptive et théorie de la décision psychologique. Analyse des décisions en utilisant l'analyse de la valeur. Analyse de la décision et mathématiques floues. Acquisition et utilisation de... more
Résumé/Abstract Science descriptive et théorie de la décision psychologique. Analyse des décisions en utilisant l'analyse de la valeur. Analyse de la décision et mathématiques floues. Acquisition et utilisation de l'information dans la prise de décision. Théorie de l' ...
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: Results are reported of the first phase of a mathematical theory which is intended to explain, and aid in the review of, organizations of men and machines in general and of command and control systems in particular. Starting from... more
: Results are reported of the first phase of a mathematical theory which is intended to explain, and aid in the review of, organizations of men and machines in general and of command and control systems in particular. Starting from relatively broad assumptions regarding the abilities and limitations of organization members, the theory develops a method by which the optimal structure and doctrine of the organization can in principle be synthesized. The results of the synthesis are in good agreement with experience in practice.
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ALINET, a network model of the US food processing and distribution sector, has been designed as a tool for analyzing energy use and for evaluating specific energy conserving technologies. The model is operational and has been used in the... more
ALINET, a network model of the US food processing and distribution sector, has been designed as a tool for analyzing energy use and for evaluating specific energy conserving technologies. The model is operational and has been used in the analysis of wheat processing. The results of a pilot study in which an alternative technology - microwave drying - is introduced in the pasta making process are described, and the impact on energy and on specific fuel use is analyzed.
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THESE PAPERS DEAL WITH THE CONTROL OF THE POSITIONS AND VELOCITIES OF HIGH-SPEED VEHICLES IN A SINGLE GUIDEWAY. (THE SECOND ONE LISTED ABOVE IS ESSENTIALLY THE SAME AS THE FIRST EXCEPT THAT IT CONTAINS AN APPENDIX WITH A DETAILED LISTING... more
THESE PAPERS DEAL WITH THE CONTROL OF THE POSITIONS AND VELOCITIES OF HIGH-SPEED VEHICLES IN A SINGLE GUIDEWAY. (THE SECOND ONE LISTED ABOVE IS ESSENTIALLY THE SAME AS THE FIRST EXCEPT THAT IT CONTAINS AN APPENDIX WITH A DETAILED LISTING OF THE COMPUTER ALGORITHMS USED.) EACH AND EVERY VEHICLE MEASURES ITS POSITION AND VELOCITY EVERY T SECONDS. THE APPROPRIATE ACCELERATIONS TO BE APPLIED TO EACH VEHICLE ARE CONSTRAINED TO BE CONSTANT DURING THE SAMPLING INTERVAL THE CONTROL COST-FUNCTION PENALIZES THE SYSTEM FOR ANY DEVIATIONS FROM THE DESIRED HEADWAY AND VELOCITY. THE REQUIRED CONTROL ACCELERATIONS ARE OBTAINED BY DERIVING THE SYSTEM EQUATIONS IN DISCRETE-TIME. THROUGH THE USE OF AVAILABLE RESULTS IN THE THEORY OF DISCRETE OPTIMAL CONTROL, THE OPTIMAL LINEAR TIME-INVARIANT SAMPLED-DATA FEEDBACK CONTROL SYSTEM IS DETERMINED. THE GENERAL RESULTS ARE PRESENTED AND ARE USED TO STUDY THE EFFECT OF CHANGING THE SAMPLING TIME T UPON THE CONTROL-SYSTEM PERFORMANCE. SINCE, IN GENERAL, THE C...
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AGRIMOD is a dynamic simulation model of the U.S. food production system designed for the analysis of (a) the implications of alternative national policies on the food supply, (b) the effects of possible natural resource and energy... more
AGRIMOD is a dynamic simulation model of the U.S. food production system designed for the analysis of (a) the implications of alternative national policies on the food supply, (b) the effects of possible natural resource and energy constraints on food supply and prices, (c) the impacts of policies on imports, exports, and reserves, and (d) the effects of technological change. The model consists of seventeen submodels fully integrated through material and information flows into four sectors and three markets. This report contains a description of AGRIMOD's submodels with particular emphasis on the modifications and enhancements made to increase the model's capabilities for carrying out analyses of the impacts of alternative energy conservation strategies on agricultural and food production. Also included is a baseline scenario for the period 1975 to 1990 with several energy alternatives. The effects of increasing energy costs on the agricultural sector and on food prices are ...
Research Interests: Economics, Energy Conservation, Energy Consumption, Alternative Energy, System Design, and 13 moreInformation Flow, Technological change, Food supply, Dynamic Simulation, Food Industry, Government Policy, Mathematical Model, Natural Resource, Food Products, Food Price, Energy Cost, AGRICULTURAL SECTOR, and Conservation strategies
: The long range objective of this project is the development of a methodology for assessing the effectiveness of naval organizational structures supported by command, control, and communications systems. The specific research was... more
: The long range objective of this project is the development of a methodology for assessing the effectiveness of naval organizational structures supported by command, control, and communications systems. The specific research was motivated by the need to relax certain assumptions so that a theory currently under development for the design and evaluation of C3 systems could be applied to more realistic organizational structures. The research effort was organized into three tasks: (1) Qualitative Differences in the Tasks of an Organization; (2) Asynchronous Protocols for Information Processing in Organizations; (3) Effectiveness Analysis of C3 System Designs.
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The generation of the tactical picture for the battle group commander from data obtained from organic and non-organic sensors is the particular problem addressed to demonstrate the trade-off between accuracy and timeliness. A colored... more
The generation of the tactical picture for the battle group commander from data obtained from organic and non-organic sensors is the particular problem addressed to demonstrate the trade-off between accuracy and timeliness. A colored Petri net model, representing in an aggregated form the architecture for the generation of the tactical picture, is used to formulate the trade-off problem. An illustrative example is used to show the kind of analysis that can be carried out.
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AGRIMOD is a dynamic simulation model of the U.S. food production system designed for the analysis of the implications of alternative national policies on the food supply, the effects of possible natural resource and energy constraints on... more
AGRIMOD is a dynamic simulation model of the U.S. food production system designed for the analysis of the implications of alternative national policies on the food supply, the effects of possible natural resource and energy constraints on food supply and prices, the impacts of policies on imports, exports, and reserves, and the effects of technological change. The model consists of seventeen submodels fully integrated through material and information flows into four sectors and three markets. In this report, the Pre-production Sector, the Farm Input Market, and the Crop Production Sectors are described in detail. Included are the submodels for regional land development and use, the crop producer's resource allocation problem, expected prices, fertilizer demand, farm input market, and realized crop production. The basic inputs considered are land, fertilizer, capital, labor, fuel and energy. Also included is a stochastic model for evaluating crop/location specific effects of weat...
Research Interests: Economics, Life Sciences, Resource Allocation, System Design, Information Flow, and 15 moreTechnological change, Land Development, Food supply, Dynamic Simulation, Land Use, Crop Production, Food Industry, Government Policy, North America, Mathematical Model, Product Life Cycle, Natural Resource, Production System, Food Products, and Stochastic Model
Development of ALINET (Alimentary Industry Network) to analyze energy use in the food processing sector and to evaluate specific energy conserving technologies is described. Chapters II and III discuss the data system and the flow graph... more
Development of ALINET (Alimentary Industry Network) to analyze energy use in the food processing sector and to evaluate specific energy conserving technologies is described. Chapters II and III discuss the data system and the flow graph generator. The simulation system, discussed in Chapter IV, accepts the structural specification of the network from the flow graph generator through the shared network data base. The considerations that influenced the implementation decisions on the data system were based on a preliminary assessment of the processing and distribution networks for several crops and livestocks products. This information is presented in chapters discussing livestock products, wheat, corn, soybeans, rice, and poultry, and eggs. (MCW)
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The study was motivated by the interest in developing a high-speed ground-transport (HSGT) system for the Northeast Corridor. The report contains general methods for controlling the spacing, velocity, and acceleration of individual... more
The study was motivated by the interest in developing a high-speed ground-transport (HSGT) system for the Northeast Corridor. The report contains general methods for controlling the spacing, velocity, and acceleration of individual vehicles in a tightly-packed string of high-speed trains. The control of vehicles moving in a string can be divided into four functions: The control of the starting and stopping operations; The injection and ejection of vehicles from the main guideway; The normal operation of a string of vehicles (far from stations) at essentially constant velocity and separation; and the control in emergency situations. (Author)
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ALINET (Alimentary Industry Network) is a dynamic network model of the food processing and distribution sector, designed for the analysis of energy use in food production and the evaluation of the effectiveness of energy conserving... more
ALINET (Alimentary Industry Network) is a dynamic network model of the food processing and distribution sector, designed for the analysis of energy use in food production and the evaluation of the effectiveness of energy conserving technologies. This report documents the second phase of the model development. It contains descriptions of: (a) the structure of the wheat system at the state, regional, and national levels; (b) the software for constructing material flow graphs at the various levels of aggregation, as well as the procedures for aggregation and data verification; and (c) the facility data base supporting the flow graph generation.
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Dimensional analysis is a method used in the design and analysis of experiments in the physical and engineering sciences. When a functional relation between variables is hypothesized, dimensional analysis can be used to check the... more
Dimensional analysis is a method used in the design and analysis of experiments in the physical and engineering sciences. When a functional relation between variables is hypothesized, dimensional analysis can be used to check the completeness of the relation and to reduce the number of experimental variables. The approach is extended to include dimensions pertaining to cognitive processes so that it can be used in the design of multi-person experiments. The proposed extension is demonstrated by applying it to a single decisionmaker experiment already completed; new results from that experiment are described. It is then applied to the design of a multi-person experiment.
AGRIMOD is a dynamic simulation model of the U.S. food production system designed for the analysis of the implications of alternative national policies on the food supply, the effects of possible natural resource and energy constraints on... more
AGRIMOD is a dynamic simulation model of the U.S. food production system designed for the analysis of the implications of alternative national policies on the food supply, the effects of possible natural resource and energy constraints on food supply and prices, the impacts of policies on imports, exports, and reserves, and the effects of technological change. The model consists of seventeen submodels fully integrated through material and information flows into four sectors and three markets. In this report, the Pre-production Sector, the Farm Input Market, and the Crop Production Sectors are described in detail. Included are the submodels for regional land development and use, the crop producer's resource allocation problem, expected prices, fertilizer demand, farm input market, and realized crop production. The basic inputs considered are land, fertilizer, capital, labor, fuel and energy. Also included is a stochastic model for evaluating crop/location specific effects of wea...
Research Interests: Economics, Life Sciences, Resource Allocation, System Design, Information Flow, and 15 moreTechnological change, Land Development, Food supply, Dynamic Simulation, Land Use, Crop Production, Food Industry, Government Policy, North America, Mathematical Model, Product Life Cycle, Natural Resource, Production System, Food Products, and Stochastic Model
The purpose of mathematical organization theory is to explain in a reasonably quantitative fashion some of the basic characteristics which are observed in organizations of man and/or machines in practice. Such a theory is outlined below.... more
The purpose of mathematical organization theory is to explain in a reasonably quantitative fashion some of the basic characteristics which are observed in organizations of man and/or machines in practice. Such a theory is outlined below. It is based on the assumption that many organizations are designed to execute certain complex tasks which exceed the capacities of their components. With these capacities suitably defined, one is in fact led to organizations whose structures and standard operating procedures bear a remarkable resemblance to those observed in practice.
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The optimal control problem for sampled-data processes in which sampling is not triggered by a timer, but occurs when one or more outputs attain preset threshold values is formulated as an adaptive optimal sampled-data regulator problem.... more
The optimal control problem for sampled-data processes in which sampling is not triggered by a timer, but occurs when one or more outputs attain preset threshold values is formulated as an adaptive optimal sampled-data regulator problem. Both open loop and closed loop solutions are determined and a comparison of a system’s performance with adaptive and with periodic sampling is presented.
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Description/Abstract AGRIMOD is a dynamic simulation model of the US food production system designed for the analysis of (a) the implications of alternative national policies on the food supply,(b) the effects of possible natural resource... more
Description/Abstract AGRIMOD is a dynamic simulation model of the US food production system designed for the analysis of (a) the implications of alternative national policies on the food supply,(b) the effects of possible natural resource and energy constraints on food ...
Research Interests: Economics, Energy Conservation, Energy Consumption, Alternative Energy, System Design, and 13 moreInformation Flow, Technological change, Food supply, Dynamic Simulation, Food Industry, Government Policy, Mathematical Model, Natural Resource, Food Products, Food Price, Energy Cost, AGRICULTURAL SECTOR, and Conservation strategies
The report deals with the control of the positions and velocities of high-speed vehicles in a single guideway. It is assumed that each and every train measures its position and velocity every T seconds. The appropriate accelerations or... more
The report deals with the control of the positions and velocities of high-speed vehicles in a single guideway. It is assumed that each and every train measures its position and velocity every T seconds. The appropriate accelerations or decelerations to be applied to each vehicle are constrained to be constant during the sampling interval. Through the use of a control costs functional, which penalizes the system for any deviations from the desired headway and velocity, the required control accelerations and decelerations are obtained by deriving the system equations in discrete-time and, through the use of available results in the theory of discrete optimal control, the optimal linear time-invariant sampled-data feedback control system is determined. The general results, as well as the general purpose digital computer programs, are presented and are used to study the effect of changing the sampling time T upon the control-system performance. Since, in general, the cost of the communi...
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