Thesis (Ocean E)--Massachusetts Institute of Technology, Dept. of Ocean Engineering, 1980. / MICROFICHE COPY AVAILABLE IN ARCHIVES AND ENGINEERING. / Includes bibliographical references. / by Joseph Anthony Carnevale, Jr. / Ocean E

Thesis (B.S.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 1979. / MICROFICHE COPY AVAILABLE IN ARCHIVES AND ENGINEERING. / Includes bibliographical references. / by Fred James Williams. / B.S.

Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 1980. / MICROFICHE COPY AVAILABLE IN ARCHIVES AND ENGINEERING. / Includes bibliographical references. / by Li-Moon Wann. / M.S.

No description available.

Nous nous interrogeons sur la pertinence de considérer les concepts de "diversité culturelle" {DC) et/ou de "capital social" {CS) comme des facteurs explicatifs de la capacité d'ïnnovation {Cl) des organisations et des territoires. Nous partons des travaux de Reagans & Zuckerman (2001), qui montrent qu'à l'échelle des groupes de travail {GT), la DC n'a pas d'impact direct sur la CI, mais plutôt un impact indirect via deux variables de CS : la cohésion et la portée externe.Nous proposons que le concept de "capital social sécant-cohésif" (CSSC) - combinaison des 2 variables- constitue un facteur explicatif pertinent de la Cl des GT. Nous montrons à travers une revue de littérature. pourquoi et comment ce schéma complexe d'interactions peut être étendu à l'échelle des organisations, des territoires et des territoires-industries (Tl). Nous menons deux analyses empiriques pour tester cette modélisation. La première se situe à l'échelle des Tl et mobilise des données brevet pour reconstituer des réseaux de co-invention de 85 Tl de I'UEI dans l'industrie des équipements électriques. Nous évaluons le CSSC et la Cl de chaque Tl, et testons économétriquement leur relation. Les résultats confirment l'impact positif du CSSC sur la Cl et montrent que la cohésion stimule la quotité de brevets déposés, tandis que la portée externe favorise l'orientation collective et durable des innovations. La seconde se situe à l'échelle des organisations et mobilise des données primaires, collectées auprès d'un échantillon de 104 PME françaises. Les résultats confirment globalement nos hypothèses, bien que te cadre empirique ne permette de tester le modèle que partiellement. / We investigate whether tt is salient to çonsider the concept of "cultural diversity" (CD) and/or "social capital" (SC) as explanatory factors of organisations' and territories' innovative capacity (IC). The starting point of our demonstration is Reagans & Zuckerman's article (2001), who shows that at the level of work groups, CD does not have a direct impact on IC but rather an indirect impact, mediated by two variables of SC cohesion and external range. We propose that the concept of "bonding-and-bridging social capital"' (BBSC)- combination of the two SC variables- constitutes a salient explanatory factor of work group's IC. Through an interdisplinary literature review we show how and why this more complex pattern interaction can be extended at the level of organisation, territories, and territory -industry (Tl). We carry out two empirical analyses to test our hypotheses. The first study concerns Tl level. lt uses EPO patent date to reconstitute the co-inventor's network of 85 Tls of the EUI5 in the electric equipment industry. We evaluate BBSC and IC in each TI, and we test their interaction econometrically. Result.s confirm the existence of a positive impact of BBSC on Cl, and show thal cohesion stimulates the quantity or patents, while extemal range stimulate the sustainable and collective orientation of patents. The second analysis concerns organisation level. It uses a set of unique data collected from 104 French SMEs. Results broodly confirm our hypotheses although the empiricaI frame allows to test only a small part of the model.

A contract was awarded to the Virginia Power Electronics Center to compare two battery discharger topologies for use on the Earth Observing System. The following report is the result of the optimal design, build and test of Voltage-Fed, Push-Pull Autotransformer battery discharger topology. The main thrust of this document is to achieve an optimal efficiency. The list of available parts is restricted to only those that are approved. Derating guidelines restrict the choice of power stage semiconductors in a manner that degrades efficiency so efficiency gains are sought by optimization of the power stage magnetics. A second goal of the design is to achieve optimal small and large signal performance. / Master of Science

Equipment availability is the most significant factor in the productivity of many mines and processing plants. Machine breakdowns are not only expensive in terms of production losses but also important in meeting production schedules. In a complex piece of machinery like a shearer or a powered support system in a highly automated longwall face, such breakdowns can be due to one of the large number of possible faults. A large proportion, up to 80% of the down time is spent in locating the fault. For this reason, a need for an automated diagnostic method to assist the operator in the diagnosis process is felt. In this study, a diagnostic system is developed by modeling the partially known or imprecise relations and poorly defined variables found in a diagnostic environment. Logic of fuzzy sets and systems theory finds an interesting application in this area. This study presents a diagnostic algorithm, which relates the possible causes of failure to their respective symptoms through fuzzy logic paths. Applications of the diagnostic method are illustrated through examples of a compressor and a shearer. / Master of Science

This study addresses the lag in effective usage of scanner-derived information in managerial decision-making. The purpose of this research is to clarify the informational needs of the various levels of management in a retail grocery firm and to develop an informational management system to deliver such information. The four specific objectives of this project are: (1) to identify the decision-making roles of the various levels of management in a firm, (2) to identify the present usage of scanner-derived information in decision-making, (3) to identify specific scanner-derived information which could facilitate the decision-making process, and (4) to develop a firm-wide information management system which would provide each management level with the information it needs and would coordinate total firm operations, but would not burden a particular level with large volumes of unnecessary data. The information used for meeting the objectives of this research was largely collected through open-ended discussions with various levels of management within seventeen cooperating retail grocery firms. The discussions placed emphasis on the current usages of scanner-derived data and on how to facilitate the use of scanner-derived data in managerial decision-making. This research substantiated the hypothesis that little use had been made of scanner-derived data for managerial decision-making in retail grocery firms. Also, barriers to the effective use of scanner-derived data were documented. The specific informational needs of the various levels of management, as discovered through the discussions with managers of the cooperating firms, were used as the basis for the information management system. / M.S.

Comprehensive analyses, including dc, small-signal and large-signal analyses, of the dynamics of various spacecraft power systems are performed. Systems' dynamics are analyzed for various operating modes, such as the shunt, battery-charge and battery-discharge modes, as well as the transition mode. Computer models using the EASY5 program are developed for the Direct Energy Transfer (DET) system, solar array switching system and partial shunt system to facilitate design, analysis and performance verification. Large-signal analyses are performed to identify stability conditions and to predict large-signal dynamic behavior for each mode of operation. The equivalent source and load characteristics of a solar array power system with a constant-power load, shunt regulator, battery charger and discharger, are identified to predict large-signal dynamic behavior. Employing the equivalent source and load, the state trajectories of shunt failure, battery discharger failure and solar array/battery lockup are predicted and verified through time-domain simulations. Small-signal analyses of the DET system are performed for the three modes of operation. The system loop gain is defined. Design guidelines for the feedback control loop of the shunt regulator, battery charger and discharger are developed to shape the system loop gain for the optimum bus dynamic performance and stability of the system. Designed subsystems are simulated both in frequency-domain and time-domain to verify the design concept. Various spacecraft power systems, such as solar array switching systems, a partial shunt system, a peak power tracking system and the COBE (Cosmic Background Explorer) power system are analyzed and simulated. Design guidelines of the power conditioning equipment for each system are provided. / Ph. D.

A comprehensive large-scale power system modeling is developed to facilitate the design and analysis of present and future spacecraft power systems. A two-port coupling method is utilized to provide a modularity in model building and analysis of the system. The modular approach allows the model to be flexible, verifiable and computationally efficient. A methodology for the system level analysis is presented with the ability to focus on the performance characteristics of an arbitrary component or subsystem. The system performance parameters are derived explicitly in terms of the two-port hybrid g-parameter representation of the component or subsystem, and impedances of its terminating subsystems. From this, the stability of the system is analytically determined and the subsystem interaction criteria is observed. Also presented is a model development from the empirical data employing the complex curve fitting technique. The technique is especially powerful for large scale system modeling and analysis where certain components and subsystems are viewed as black boxes with measurable terminal characteristics. The technique can also be used to realize a reduced order model of a complex subsystem. The Direct Energy Transfer (DET) spacecraft power system is modeled to demonstrate the versatility of the comprehensive system model by performing various DC, small-signal and large-signal analyses. Of particular interest is the analysis of the large-signal behavior of the nonlinear solar array system by employing the state-plane method. The analysis of the solar array system operation focused on the transition mode between the shunt mode and the battery discharging mode is presented. The subsystem interaction problems in the local component and global system are illustrated. A methodology for the design and trouble-shooting of a system dealing with the interaction problems using the g-parameters is described. Finally, a system level analysis of the DET system using an empirical data modeling technique is performed. / Ph. D.