Thesis (M.S.)--Oregon State University, 2005. / Printout. Includes bibliographical references (leaves 97-100). Also available on the World Wide Web.

Thesis (Ph. D.)--Oregon State University, 2006. / Printout. Includes bibliographical references (leaves 70-72). Also available on the World Wide Web.

Thesis (M.S.E.C.E.)--University of Delaware, 2007. / Principal faculty advisor: Fouad Kiamilev, Dept. of Electrical and Computer Engineering. Includes bibliographical references.

Thesis (M.Phil.)--Hong Kong University of Science and Technology, 2007. / Includes bibliographical references (leaves 68-71). Also available in electronic version.

The efficiency of low voltage scanning electron microscopy, which presents near-surface information, has been well known for a long time. However, it is not widely known that the high resolution capability can only be achieved when the surface reveals the original characteristics of the materials without any deterioration due contamination. Therefore, initial attention in this study is directed at clarifying the efficient use of the ultra high resolution, low voltage SEM (UHRLV SEM), (Ultra55, Zeiss). The SEM images and the selected electrons for detection, and damage that occurs through UHRVL SEM observation are also researched. Subsequently, the most efficient specimen preparation technique, which is appropriate for the characteristics of the individual materials, is investigated for galvanized steel, ultrasonically welded alloys of Al6111 and AZ31 alloy, Ti6Al4V alloy honeycomb structure and a ceramic sensor. The outcomes of appropriate specimen preparation technique and use of the extremely Low-Voltage below 2.0 kV, are presented in the results section. The study also presented the challenge of improving the low compositional contrast for the dissimilar materials of aluminium and magnesium, and to reduce charging effects in an insulating material comprising a ceramic sensor. As an application of the surface prepared by the process in this study, 3D tomography is also introduced.

No description available.

<p> In past years, wireless technology has seen an incredible boom. As a result, industry has gone to great lengths to make wireless devices cheaper, smaller, faster and less power- hungry. This has prompted a significant interest in the research world to design circuit components that would facilititate these goals. However, much of the focus has been on wireless technology for communications applications, such as wireless telephony and wireless computer networking. More recently, there has been a focus on developing circuits for other wireless applications, one of which is wireless sensor networks. Such applications would demand extremely low-power operation, especially from the RF front-end. We have concentrated on achieving low-power operation for one of the important building blocks of the RF transceiver, which is the frequency downconversion mixer. </p> <p> In this thesis, we describe the design and results of two mixers, both designed in CMOS O.l8J.Lm technology offered by the Canadian Microelectronics Corporation (CMC). The first design uses the body terminal of the transistor as one of the inputs. This method allows for the radio-frequency (RF) and local oscillator (LO) stages in traditional switching mixers to be collapsed into one stage, thereby allowing for operation at lower supply voltages and lower power comsumption levels. This mixer was designed to downconvert a 1.9GHz RF signal to a 250MHz intermediate-frequency (IF) signal. The measured performance characteristics resulted in a power consumption of 400J.LW from a 0.8V supply, a conversion gain of 1dB, a single sideband (SSB) noise figure of 1ldB, and an input-referred 3rd-order intercept point (IIP3) of -9dBm. </p> <p> The second mixer design used a folding architecture to reduce the supply voltage headroom needed, as well as distribute the current appropriately for high-gain and lowpower operation. This mixer was designed to downconvert a 2.4GHz RF signal to a 100MHz IF signal. The simulated performance characteristics showed a power consumption of 640).1 W from a 1 V supply, a conversion gain of 4dB, a SSB noise figure of 19dB, and an IIP3 of -6.5dBm. </p> / Thesis / Master of Applied Science (MASc)

In order to meet demands for faster and more efficient data processing, modern microprocessors are being designed with lower voltage implementations. The processor voltage supply in future generation processors will decrease to 1.1 V ~ 1.8V. More devices will be packed on a single processor chip, and processors will operate at higher frequencies, beyond 1GHz. Therefore, microprocessors need aggressive power management. Future generation processors will draw current up to 50 A ~ 100 A [2]. These demands, in turn, will require special power supplies and Voltage Regulator Modules (VRMs) to provide lower voltages with higher currents and fast transient capabilities for microprocessors. This work presents several low-voltage high-current VRM technologies for future generation data processing, communication, and portable applications. The developed advanced VRMs with these new technologies have advantages over conventional ones in power density, efficiency, transient response, reliability, and cost. The multi-module interleaved quasi-square-wave VRM topology achieves a very fast transient response and a very high power density. This topology significantly reduces the filter inductance and capacitance, while having small output and input ripples. The analysis, design, and experimental verification for this new topology are presented in this work. The current sensing and current sharing techniques are developed with simple and cost-effective implementations. With this technique, traditional current transformers and sensing resistors are not required, and the inductance value, MOSFET on resistance and other parasitics have no effect on current sharing results. The design principles are developed and experimentally verified. A generalized approach and an extension of the novel current sharing control are presented in this work. The techniques for improving VRM light load efficiency are developed in this work. By utilizing the duty cycle signal, VRMs can be implemented with advanced power management functions to reduce further the power consumption at light loads to extend the battery-operation time in portable systems or to facilitate the compliance with various "energy star" ("green" power) requirements in office systems. Four improved approaches are presented and verified with experimental results. The high-input-voltage VRM topology, push-pull forward converter, can be used in high-bus-voltage distributed power systems. This converter has a high efficiency, a high power density, a fast transient response, and can be easily packaged as a standard module. The circuit design and experimental evaluation are addressed to demonstrate the operation principles and advantages of this topology. / Ph. D.

The ultimate goal of this research was to gain a more fundamental understanding of the effects of “active"? alloying elements on the performance of low voltage, aluminum, sacrificial anodes. We have developed an overview of elemental trends and a comparison with literature, in support of a larger program on predicting anode behavior. The broader impact of this work was to enhance the ability to control corrosion and reduce the likelihood of hydrogen embrittlement induced by cathodic protection on ships and marine structures. As compared to high voltage anodes, low voltage, aluminum, sacrificial anodes reduce the likelihood of causing hydrogen embrittlement or stress corrosion cracking when used to protect high strength steels. In this study, open circuit potential, potentiostatic, galvanostatic and Tafel tests were performed on eleven high-purity aluminum-based binary and ternary alloys containing Bi, Ga, In and Zn in an effort to understand the individual effects of each element and the interactions between these elements. The microstructures of the as-cast alloys and the corrosion surfaces after testing were characterized using electron microscopy. Current capacities and current capacity efficiencies were calculated from potentiostatic and galvanostatic data. Galvanic coupling data from Druschitz et al was plotted with average values from potentiostatic and galvanostatic tests on Tafel curves for all alloys. [1] Variance of weight loss, average galvanostatic current, and average potentiostatic potential of the Al-0.57 wt% Zn-0.55 wt% Bi alloy was evaluated. Indium and gallium had the most significant effect on corrosion behavior (per wt% added), followed by zinc and bismuth. Bismuth had only a small effect on the weight loss, galvanostatic current and potentiostatic potential. However during potentiostatic testing Al-Bi alloys showed a steady increase in current with time, indicating that larger effects may be seen at longer periods of time. In Al-Zn alloys preferential dissolution of the zinc-rich interdendritic regions was observed. The Al-5.3 wt% Zn alloy showed high current values, but also exhibited high weight loss and more adherent corrosion products. Interdendritic corrosion also occurred with the Al-5.3 Zn-0.011 In alloy. Also, non-uniform dissolution of the remaining primary aluminum dendrites by the formation of small holes was observed, possibly due to indium precipitates. Grain boundary attack and severe intra-granular pitting was observed in Al-In alloys. Small holes were also evident on the surface of pits, similar to those seen on dendrites with the Al-5.3 Zn-0.011 In alloy. The addition of Indium greatly shifted voltages to more negative values (-0.802 to -0.858 VSCE at 9 A/m²) and significantly increased the observed currents (42-83 A/m² at -0.730 VSCE). High potentiostatic current capacities were exhibited by Al-In alloys, Al-0.1 wt% Ga, Al-5.3 wt% Zn-0.011 wt% In, and Al-0.57 wt% Zn-0.55 wt% Bi. However some calculated current capacity values were actually above the theoretical values, possibly due to corrosion products affecting the weight loss measurements. / Master of Science

Thesis (M. App. Sc.)--Carleton University, 2004. / Includes bibliographical references. Also available in electronic format on the Internet.