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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
31

Simulation of direct current microdischarges for microthruster applications

Kothnur, Prashanth Srinivasa, January 1900 (has links) (PDF)
Thesis (Ph. D.)--University of Texas at Austin, 2005. / Vita. Includes bibliographical references.
32

'n Ondersoek na draaiveldmasjiene met elektroniese kommutators vir aandrywing van elektriese voertuie

Loots, Gerhard Waldemar 25 September 2014 (has links)
M.Sc. (Electrical & Electronic Engineering) / The behaviour of alternating current machines being fed from an electronic commutator is investigated. The performance of compound power switches for use in electric vehicle drives are examined. A detailed study on switching losses and base current characteristics based upon experimental measurements was carried out. With further reference to power switches the merit, development and functioning of an electronic commutator is discussed. Because of the close association between this study and electric vehicle drives, a comparative study of the performance of different rotor types within the same machine was executed. Attention is paid to torque and efficiency characteristics in particular. The influence of voltage and current harmonics was established by comparative testing of the machine with sinusoidal and electronic commutator excitation. The study shows that the highest specific power was attained with the alternating current machine with a wound rotor (synchronous machine) while there seems to be merit in the use of permanent magnet rotors for electric drives as well. On the average the use of electronic commutator excitation resulted in an efficiency decrease of approximately 15% for the a.c. machine with different rotor types. Efficiency and torque for an induction machine with solid rotor were disappointing so that there seems to be little application for solid steel rotors. A simple model for the synchronous machine with wound rotor was developed to explain the dependence of torque and efficiency upon speed of rotation and commutation angle. To conclude, guidelines are given for future studies on electric vehicle drives and machine types as primary drive.
33

Electric vehicles as energy processing and conversion systems

Van Niekerk, Hendrik Rudolph 25 September 2014 (has links)
D.Ing. (Electrical & Electronic Engineering Science) / In the light of a history of more than a century, and reviving interest over the last three decades, battery powered electric vehicles are seen as one of the contributing technologies to alleviate transport problems in the future. This thesis is concerned with the use of energy in road transport. In particular, some selected aspects of the application of battery powered road vehicles are addressed. The thesis gives a brief background history and reviews the forces and factors which presently play a role in the developments and future application of battery electric vehicles. The main contribution, however, lies in the field of technical clarification of some aspects of electric vehicle theoretical analysis, which have not been addressed before. The first of these technical subjects is the analysis of energy consumption of vehicles when operating under non-steady driving conditions. The analysis results in simple but relevant expressions for the energy consumption of any moving vehicle during start-stop driving, as well as driving over a hilly route. The potential benefit of kinetic energy recovery can be quantitatively determined. The theory is then applied to battery electric vehicles and the results are compared to actual recorded energy consumption figures. The second technical investigation concerns the optimisation of electric vehicle drive systems with respect to mass. It is shown that optimized drive systems should be designed to suit both the energy density characteristics of the batteries used, as well as the particular characteristics of the drive cycle to which the vehicles will be applied.
34

Live Versus Virtual: Cost Benefit Analysis for Applying Simulation Towards Army Aviator Flight Minimums

Morelle, Dylan 01 January 2016 (has links)
The Longbow Crew Trainer (LCT) is a cost effective, safe alternative to live training in the AH-64D/E Apache helicopter. Current Army doctrine and regulations have provisions for the limited use of simulator in lieu of aircraft hours toward semiannual minimum flight hour requirements. With the defense budget in decline, the Army must find innovative, cost effective methods to conduct realistic, relevant training to sustain proficiency in their warfighting capabilities. The LCT fully replicates the cockpit environment through training scenarios for requisite crew tasks and missions in a realistic, modular, and transportable solution. An attack helicopter crew can safely train in customizable scenarios ranging from basic aviation tasks to crew-level missions and gunneries. The Army is currently aligning one LCT per attack battalion under the Aviation Restructure Initiative. There are 20 Armed Reconnaissance Battalions/Squadrons in the active component with approximately 35 aircrews per battalion. The premise of this study was to review cost benefits of training in a virtual environment over a live environment while exploring the effects on proficiency. The difference in cost per hour between an AH-64D and the LCT is approximately $3,998. Using this figure and the semiannual flight hour requirements from the current Aircrew Training Manual in a weighted average between Flight Activity Category (FAC) 1 and FAC 2 pilot's flight minimum requirements formed the basis for four models: Low, Status Quo (baseline), Moderate, and High Virtual Simulation Models. This study found that while the High Virtual Simulation Model resulted in the greatest cost savings, the current budget and previous literature does not require such drastic measures. The Low Virtual Simulation Model resulted in higher costs. Therefore, the Moderate Virtual Simulation Model, proved most relevant to budget analysts, aviation unit commanders, and pilots by decreasing annual costs by an estimated $76.2 million without degrading proficiency.
35

Information exchange architecture for integrating unmanned vehicles into maritime missions /

Woolsey, Aaron L. January 2004 (has links) (PDF)
Thesis (M.S. in Systems Technology (Joint Command, Control, Communications, and Intelligence (JC4I)))--Naval Postgraduate School, June 2004. / Thesis advisor(s): Orin Marvel. Includes bibliographical references (p. 35-37). Also available online.
36

Simulation of heavy-duty hybrid electric vehicles

Nennelli, Anjali Devi. January 2001 (has links)
Thesis (M.S.)--West Virginia University, 2001. / Title from document title page. Document formatted into pages; contains xvi, 112 p. : ill. (some col.). Includes abstract. Includes bibliographical references (p. 85-87).
37

Design optimization of space launch vehicles using a genetic algorithm

Bayley, Douglas James, January 2007 (has links) (PDF)
Thesis (Ph.D.)--Auburn University, 2007. / Abstract. Vita. Includes bibliographic references (ℓ. 169-175)
38

Design and validation of a chassis dynamometer for present and future vehicle testing and design

Wilson, Robert L. January 2002 (has links)
Thesis (M.S.)--Ohio University, 2002. / Title from PDF t.p.
39

Optimization of vehicle suspensions subjected to random excitation /

Cheema, Rifaquat Ali. January 1984 (has links)
Thesis (M.S.)--Rochester Institute of Technology, 1984. / Typescript. Includes bibliographical references (leaves 75-78).
40

Resume of tests on commercial vehicles on winter surfaces, 1939-1966, National Safety Council Committee on Winter Driving Hazards

Hajela, Gyaneshwar Prasad, January 1966 (has links)
Thesis (M.S.)--University of Wisconsin--Madison, 1966. / eContent provider-neutral record in process. Description based on print version record.

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