Thesis (M.S.)--Missouri University of Science and Technology, 2009. / Vita. The entire thesis text is included in file. Appendices A-G included in PDF, not on CD-ROM. Title from title screen of thesis/dissertation PDF file (viewed May 20, 2009) Includes bibliographical references.

Thesis (Ph. D.)--University of Wisconsin--Madison, 1983. / Typescript. Vita. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references (leaves 138-140).

Thesis (Ocean E)--Massachusetts Institute of Technology, Dept. of Ocean Engineering, 1979. / Supervised by Loren R. Haury, Douglas E. Kenyon and Henri O. Berteaux. Includes bibliographical references (leaves 134-137).

Since the discovery of giant magnetoresistance in 1980s, Spintronics became an exciting field which studies numerous phenomena including the spin transport in magnetic heterostructures, magnetization dynamics and the interplay between them. I have investigated different topics during my graduate research. In this dissertation, I summarize all my projects including spin pumping, spin convertance and spin injection into ballistic medium. First, we develop a linear response formalism for spin pumping effect. Spin pumping refers that a precessing emits a spin current into its adjacent nonmagnetic surroundings, which was originally proposed using scattering theory. The newly developed formalism is demonstrated to be identical the early theory in limiting case. While our formalism is convenient to include the effects of disorders and spin-orbit coupling which can resolve the quantitative controversies between early theory and experiments. Second, the spin pumping experiments indicates a much smaller spin Hall angle compared with the results obtained via the spin transfer torque measurements. We found that such issues can be resolved when taking into consideration the effects of non-local conductivity. And we conclude neither of the two methods measures the real spin Hall angle while the spin pumping methods provides much accurate estimations. Third, we developed the spin transport equations in weak scattering medium in the presence of spin-orbit coupling. Before this, all spin dependent electron transport has been modeled by the conventional spin diffusion equation. While recent spin injection experiments have seen the failure of spin diffusion equation. As the experimental fitting using spin diffusion models led to unrealistic conclusions. At last, we study the spin convertance in anti-ferromagnetic multilayers, where the spin information can be mutually transferred between ferromagnetic/anti-ferromagnetic and conduction electrons. Our theory successfully explained the experiment results that the insertion of thin NiO film between YIG/Pt largely enhances the spin Seebeck currents.

This thesis studies the optimal design for a photovoltaic-powered medium-head (30 meters) water pumping system, with the emphasis on improving the efficiency and reducing the maintenance requirements of the electrical subsystem. The reduction of maintenance requirements is realized by replacing the conventional brush-type permanent magnet dc motor with a brushless dc (BLDC) motor. Different BLDC motor control techniques such as position-sensorless operation, sinusoidal and trapezoidal excitations are investigated. The improvement in efficiency is achieved by maximizing the output power from the photovoltaic array and by minimizing the losses in various parts of the electrical sub-system. A microprocessor-based double-loop maximum power tracking scheme is developed for maximization of the photovoltaic array output power. Over 99% utilization factor is achieved for a typical clear day regardless of the season of the year. The system losses are minimized mainly by performing loss analysis and selecting most suitable switching topologies and switching components. Experimental results show that the combined converter-motor efficiency is comparable to those of high-efficiency brush-type dc motor systems. / Applied Science, Faculty of / Electrical and Computer Engineering, Department of / Graduate

Transient pressures subsequent to simultaneous power failure at all pumps of a multistage pumping system are analysed. Distributing pumping stations along a pipeline, rather than placing all of the required pumps within one pumping station, significantly reduces transient pressure fluctuations within the system. A computer program using the FORTRAN language is developed to analyse multistage pumping systems, with appropriate surge controls, in the event of such a power failure. These surge controls consist of valves, vacuum breakers, air chambers and reservoirs; with other controls easily added as they develop. Boundary conditions determining system controls are not developed as a part of this thesis, but are described for completeness. By comparing the maximum and minimum transient pressures occurring within- single stage and multistage systems, the premise that multistage systems give significantly lower transient pressures than single stage systems is substantiated. This reduction in transient pressures allows for possible savings in costs, as pipe wall thicknesses and the size of large, expensive control structures may be reduced. Examples demonstrating the use of the program are included. / Applied Science, Faculty of / Civil Engineering, Department of / Graduate

Spintronics is a research field that focuses on the manipulation of the quantum mechanical spin of charge carriers in solid state materials for future technological applications. Creating large spin currents with large relaxation times is sought after in the field of spintronics which may be aided by combining spintronics with superconductivity. This thesis provides a phenomological study of the effective change in ferromagnetic resonance linewidth, by dynamical spin injection into a permalloy-copper-niobium tri-layer in the superconducting state. The ferromagetic resonance linewidth was measured from 2-14 K. It was observed that there was a change in the behavior of the resonance as well as a change in the linewidth from the between 6-8 K. An observed change in the resonance field, Hr, shows a clear non monotonic behavior as a function of temperature below 7-8 K. The decrease in linewidth was attributed to the suppression of the spin sinking mechanisms due to the superconducting state of niobium.

M.Ing. (Engineering Management) / The purpose of this dissertation was to compare the local manufacturing of liquid pumps in South Africa against the importation of pumps manufactured on the international markets as well as also investigate the capacity limitations of the local pump manufacturers; the technologies available on overseas markets (in terms of electric, solar and wind-powered liquid pumps) and comparing the technologies to those available in South Africa. Five of the leading pump manufacturers were researched in this dissertation namely: KSB; Grundfos; Howden Pumps; Sulzer Pumps Africa and Warman Pumps. South African pump manufacturers are importing most of their pumps from international markets with the primary reason being to meet demands. By comparison, South African pump manufacturers are finding it difficult to produce pumps with equivalent or lower costs than the pumps which are produced on the international markets. Pump manufacturers on international markets offer greater cost savings for South African pump manufacturers which ultimately results in financial savings and a higher yield in profits. Many international pump manufacturers use advanced technology which makes the production costs of pump components as much as twenty percent (20%) less as compared to the South African pump industry. The importation of pumps is a method used to increase the local supply of pumps as the cost of the pump, including import costs, are not as costly as actually manufacturing the pumps in South Africa. While South African pump manufacturers manufacture pumps of relatively high energy consumption and monetary costs; they also produce standard conventional pumps which are required to supply the local demand. Local pump manufacturers were approached to find out exactly how they cope with these stringent requirements by the South African markets, yet still achieve the profits in the industry to remain afloat. Various pump forms were researched specifically relating to the pumps used on the South African markets with regards to their production costs, advantages and disadvantages (wind and solar pump technologies). Standard conventional pumps are preferred on local markets by as much as fifteen percent (15%) with newer technologies (solar and wind powered pumps) being preferred on the international markets. South Africa continues to demand standard conventional pumps (electric-driven pump) although demands for newer technology is on the increase. The international market’s production lines are mature and well established which results in a lower cost of production which leads to these pumps being of more demand as compared to newer pumps which are currently the preference. Local pump manufacturers can satisfy the demand and benefit from the lower importation cost of standard conventional pumps. The preliminary results suggest that the importing of pumps from international markets aid local manufacturers in keeping up with the demand and accquiring sufficient profits. Modern technologies such as solar and wind power is a growing maket in South Africa and is becoming increasingly common. The research approach used in this study involved targeting five of the local pump manufacturers in South Africa. Each manufacturer was asked a series of questions relating to the research questions in order to draw up conclusions regarding the problem statement and hypothesis. Findings from the conducted surveys were compared to the literature which is currently published. Findings show that local pump manufacturers are dependent on imports in order to satisfy the demand for standard conventional pumps rather than manufacturing their own and the use of newer technologies are increasing in the local pump industry.

No description available.

京都大学 / 0048 / 新制・課程博士 / 博士(農学) / 甲第21137号 / 農博第2263号 / 新制||農||1057(附属図書館) / 学位論文||H30||N5111(農学部図書室) / 京都大学大学院農学研究科応用生命科学専攻 / (主査)教授 三芳 秀人, 教授 宮川 恒, 教授 加納 健司 / 学位規則第4条第1項該当 / Doctor of Agricultural Science / Kyoto University / DGAM