Power consumption is a critical design issue in embedded processors. As part of our low power processor design project, this thesis work aims to reduce power consumption on two typical processor components: Register File (RF), and Arithmetic and Logic Unit (ALU). Register File is one of the most power hungry components in the processor, consuming about 20% of the processor power. The ALU is the working horse in the processor, responsible for almost all basic computing operations. Although ALU does not consume as high power as the register file, we observe that it can be power intensive in terms of power dissipation per silicon area unit and may result in a thermal hot spot in the processor. Existing approaches to reduce power on the register file and ALU are effective. However, most of them either entail extensive hardware design efforts, or require a significant amount of work on post-compilation software code modification. The approaches proposed in this thesis avoid such problems. We only customize the internal structure of the processor components and keep the components’ interface to other system parts intact, so that the customization to a component is transparent to its external hardware design and no modification/alteration to other hardware components or to the software code is required. This customization strategy is well suitable to our whole low power processor design project and can be applied to any customization of an existing system for a given application. We have applied our customization approaches to a set of benchmarks in a variety of application domains. Our experimental results show that the power savings on register file are in a range from 18.8% to 45.5%, an average of 29.7% register file power can be saved. For the arithmetic and logic unit, the power savings are from 43.5% to 49.6% and the average saving is 46.9% as compared to the original designs. We also combine the customization of both the ALU and the register file. With the customizing of the ALU and the register file simultaneously, the processor power consumption can be reduced from 3.9% to 10.1%; on average, 6.44% processor power can be saved. Most importantly, the power saving achievement is at the cost of neither hardware complexity nor processor performance, and the implementation is extremely straightforward and can be easily incorporated into a processor design environment, such as ASIPMeister (a design tool, to automatically generate a VHDL model for application specificinstruction set processors) used in our research.

Thesis (Ph. D.)--University of Texas at Austin, 2004. / Vita. Includes bibliographical references.

Thesis (Ph. D.)--Virginia Commonwealth University, 2006. / Prepared for: Dept. of Health Administration. Bibliography: leaves 176-192. Also available online.

A magnetic force microscope (MFM) is a special type of scanning force microscope which measures the stray field above a ferromagnetic sample with the help of a ferromagnetic cantilever. The aim of this project was to design and build a MFM head and interface it with a commercial scanning probe electronics controller with the help of an appropriate force sensor. The MFM head and the force sensor were to be designed to work at low temperatures (down to 4 K) and in high vacuum. During this work, a magnetic force microscope (MFM) head was designed. Its design is symmetrical and modular. Two dimensional views were prepared to ensure proper geometry and alignment for the various modules. Based on these views, individual parts in the various modules were manufactured and combined for the final assembly of the head. This MFM head has many essential and advanced features which were incorporated during the design process. Our MFM head has an outside diameter of 5 cm and thus has a low thermal mass. The head operates inside a 100 cm long vacuum can which is kept in a cold bath inside a superinsulated dewar. Other features of this MFM head include thermal compensation of the important parts, flexibility to use commercial MFM cantilevers and a large scan range compared to the previous designs. Some of the anticipated system specifications are: 1) room temperature scanning range of 175?? 175 ??m, 2) low temperature scanning range between 35-50 ??m, 3) smallest detectable magnetic force in the range of one pN and 4) smallest detectable magnetic force gradient in the range of 10-3 to 10 -5 N/m. This MFM head was interfaced to a commercial scanning probe electronics apparatus by designing a fiber-optic interferometer as the sensor for the detection of the cantilever deflection. The fiber-optic sensor also has features of its own such as stability, compactness and low susceptibility to noise because of all-fiber construction. With this MFM head, we hope to image many magnetic samples which were previously impossible to image at Texas A&M.

Canadian construction participants have long recognized that accepting the lowest price bid does not guarantee maximum value. Achieving a value-based procurement approach is a challenge, particularly for the Canadian public sector clients who are limited in their ability to evaluate the competitive bids based solely on the low-bid award system. Bid and cost data from 218 projects from three major public sector construction clients in the Greater Toronto Area are evaluated. Compared to the other clients, the cost escalation is significantly higher for the client that does not have a standard prequalification policy. Increased contractor competition (high number of bids) and a large price gap between low bid and other bids are correlated to higher cost escalation for the non-prequalifying client. Also, the organizational culture of the non-prequalifying client is less results-oriented. The research demonstrates the importance of prequalifying for clients that award based solely on the low bid.

Canadian construction participants have long recognized that accepting the lowest price bid does not guarantee maximum value. Achieving a value-based procurement approach is a challenge, particularly for the Canadian public sector clients who are limited in their ability to evaluate the competitive bids based solely on the low-bid award system. Bid and cost data from 218 projects from three major public sector construction clients in the Greater Toronto Area are evaluated. Compared to the other clients, the cost escalation is significantly higher for the client that does not have a standard prequalification policy. Increased contractor competition (high number of bids) and a large price gap between low bid and other bids are correlated to higher cost escalation for the non-prequalifying client. Also, the organizational culture of the non-prequalifying client is less results-oriented. The research demonstrates the importance of prequalifying for clients that award based solely on the low bid.

In his 1947 work "Theory of Braids" Emil Artin asked whether the braid group remained unchanged when one considered classes of braids under linkhomotopy, allowing each strand of a braid to pass through itself but not through other strands. We generalize Artin's question to string links over orientable surface M and show that under link-homotopy surface string links form a group PBn(M), which is isomorphic to a quotient of the surface pure braid group PBn(M). Surface braid groups and their properties are an area of active research by González-Meneses, Paris and Rolfsen, Goçalves and Guaschi, and our work explores the geometric and visual beauty of this subject. We compute a presentation of PBn(M) in terms of the generators and relations and discuss the orderability of the group in the case when the surface in question is a unit disk D.

Thermal Conductivity studies can provide fundamental information regarding the symmetry of the superconducting energy gap. To perform this kind of experiment, we need to use a very low temperature environment. Also a special mount has been to designed and constructed for the thermal conductivity measurements. This mount will allow holding the sample in different directions with respect to the applied magnetic field. The results are consistent with Wiedemann-Franz law to within 2.5\%. We also discuss a series of thermal conductivity experiments to shed additional light on the symmetry of the superconducting order parameter in the unconventional superconductor PrOs4Sb12.

The aim of this project is to find the optimum growth conditions for growing amorphous Zn1-x-yAlxSny (x=0.02 and 0.2) films with various dopents and high transmittance in visible range. By varying substrate temperatures, working pressures, RF powers and growth modes, amorphous Zn1-x-yAlxSny films with high transmittance were successfully grown at low and room temperatures. Grazing-incident small-angle X-ray diffraction data indicates that low temperature, high working pressure, low RF power and the short deposition period are the key for growing amorphous films in which adatoms on the surface of substrate do not have enough energy for migration and constructing a better crystal structure. As a result of this inadequate energy of adatoms, clusters of grains can be observed on the surface of films by the atomic force microscope. Amorphous Zn1-x-yAlxSny films possess crystalline short range order that opens up the optical and electronic bandgap. In terms of transmittance, a blue shift in the critical transmittance and a higher transmittance in IR range are observed. The high level doping of Al and Sn in ZnO films introduces crystal disordering in films and results in amorphous films even they were grown at room temperature. X-ray absorption near edge spectrum (XANES) discovers that the doped Sn behaves as tetra-valence ions for those Zn1-x-yAlxSny films with high oxygen deficiency. All amorphous films grown in this project exhibits a very low conductivity.

The low NOx burner (LNB) is the most cost effective technology used in coal-fired power plants to reduce NOx. Conventional (unstaged) burners use primary air for transporting particles and swirling secondary air to create recirculation of hot gases. LNB uses staged air (dividing total air into primary, secondary and tertiary air) to control fuel bound nitrogen from mixing early and oxidizing to NOx; it can also limit thermal NOx by reducing peak flame temperatures. Previous research at Texas A&M University (TAMU) demonstrated that cofiring coal with feedlot biomass (FB) in conventional burners produced lower or similar levels of NOx but increased CO. The present research deals with i) construction of a small scale 29.31 kW (100,000 BTU/hr) LNB facility, ii) evaluation of firing Wyoming (WYO) coal as the base case coal and cofiring WYO and dairy biomass (DB) blends, and iii) evaluating the effects of staging on NOx and CO. Ultimate and Proximate analysis revealed that WYO and low ash, partially composted, dairy biomass (LA-PC-DB-SepS) had the following heat values and empirical formulas: CH0.6992N0.0122O0.1822S0.00217 and CH_1.2554N_0.0470O_0.3965S_0.00457. The WYO contained 3.10 kg of Ash/GJ, 15.66 kg of VM/GJ, 0.36 kg of N/GJ, and 6.21 kg of O/GJ while LA-PC-DB-SepS contained 11.57 kg of Ash/GJ, 36.50 kg of VM/GJ, 1.50 kg of N/GJ, and 14.48 kg of O/GJ. The construction of a LNB nozzle capable of providing primary, swirled secondary and swirled tertiary air for staging was completed. The reactor provides a maximum residence time of 1.8 seconds under hot flow conditions. WYO and DB were blended on a mass basis for the following blends: 95:5, 90:10, 85:15, and 80:20. Results from firing pure WYO showed that air staging caused a slight decrease of NOx in lean regions (equivalence ratio, greater than or equal to 1.0) but an increase of CO in rich regions (=1.2). For unstaged combustion, cofiring resulted in most fuel blends showing similar NOx emissions to WYO. Staged cofiring resulted in a 12% NOx increase in rich regions while producing similar to slightly lower amounts of NOx in lean regions. One conclusion is that there exists a strong inverse relationship between NOx and CO emissions.