Copper is a widely used conductor in the manufacture of printed wiring boards (PWB). The trends in miniaturization of electronic devices create increasing challenges to all electronic industries. In particular PWB manufacturers face great challenges because the increasing demands in greater performance and device miniaturization pose enormous difficulties in manufacturing and product reliability. Nanocrystalline and ultrafine grain copper can potentially offer increased reliability and functionality of the PWB due to the increases in strength and achievable wiring density by reduction in grain size. The first part of this thesis is concerned with the synthesis and characterization of nanocrystalline and ultra-fine grain-sized copper for potential applications in the PWB industry. Nanocrystalline copper with different amounts of sulfur impurities (25- 230ppm) and grain sizes (31-49nm) were produced and their hardness, electrical resistivity and etchability were determined. To study the thermal stability of nanocrystalline copper, differential scanning calorimetry and isothermal heat treatments combined with electron microscopy techniques for microstructural analysis were used. Differential scanning calorimetry was chosen to continuously monitor the grain growth process in the temperature range from 40C to 400C. During isothermal annealing experiments samples were annealed at 23C, 100C and 300C to study various potential thermal issues for these materials in PWB applications such as the long-term room temperature thermal stability as well as for temperature excursions above the operation temperature and peak temperature exposure during the PWB manufacturing process. From all annealing experiments the various grain growth events and the overall stability of these materials were analyzed in terms of driving and dragging forces. Experimental evidence is presented which shows that the overall thermal stability, grain boundary character and texture evolution of copper is greatly related to changes in driving and dragging forces, which in turn, are strongly depended on parameters such as annealing temperature and time, total sulfur impurity content and the distribution of the impurities within the material. It was shown that a simple increase in the sulfur impurity level does not necessarily improve the thermal stability of nanocrystalline copper.

The measurement of thermal conductivity is a powerful probe that can be used for identifying the nature of heat and charge carriers and structure of the gap in the superconducting compounds. At low temperature when the effect of phonons in transporting heat becomes smaller, one can obtain information about the quasiparticle distribution and the superconducting gap structure. In order to do a sensitive thermal conductivity measurement, we designed and built a thermal conductivity mount. The charge conductivity was measured through the same leads that we used for making the thermal conductivity measurements. To test the mount, we measured the heat and charge conductivity of a silver wire and determined the accuracy with which we could satisfy the Wiedemann--Franz law within 5 \%. We will report the measurements of thermal and electrical conductivities of two filled skutterudite superconducting compounds, PrRu4Sb12 and PrOs4Sb12 at 1.1--35 K temperature range. The differences and similarities between the transport properties of these compounds in the superconducting and normal states along with the results of investigation of the Wiedemann--Franz law will be discussed in the following chapters.

The measurement of thermal conductivity is a powerful probe that can be used for identifying the nature of heat and charge carriers and structure of the gap in the superconducting compounds. At low temperature when the effect of phonons in transporting heat becomes smaller, one can obtain information about the quasiparticle distribution and the superconducting gap structure. In order to do a sensitive thermal conductivity measurement, we designed and built a thermal conductivity mount. The charge conductivity was measured through the same leads that we used for making the thermal conductivity measurements. To test the mount, we measured the heat and charge conductivity of a silver wire and determined the accuracy with which we could satisfy the Wiedemann--Franz law within 5 \%. We will report the measurements of thermal and electrical conductivities of two filled skutterudite superconducting compounds, PrRu4Sb12 and PrOs4Sb12 at 1.1--35 K temperature range. The differences and similarities between the transport properties of these compounds in the superconducting and normal states along with the results of investigation of the Wiedemann--Franz law will be discussed in the following chapters.

This thesis is a study of impinging jet PV/Thermal collectors. More specifically, the thesis deals with the development of a model for this type of collector and its validation. The model developed for this thesis consists of a series of energy balances at every layer of the collector. The transient effects due to thermal mass of the different layers were taken into account. The resulting differential equations were solved using the backwards Euler method in an iterative manner. The validation of the model was done using a prototype of the collector. The aperture area of the collector was 0.78m2 and the PV cells covered 0.27m2. The collector was tested on 8 different days between January 30th and March 31st 2010. The experiments were conducted with various weather conditions, and parameters (such as mass flow rate and inlet temperature). The data was taken every 0.5 seconds and averaged over 5 minutes. In general, the model was found to work very well. For March 31st, the total modeled heat gain for the day was found to be within 2.1% of the experimental data. The PV electrical energy was found to be within 4.4% of the experimental results. The model was also found to work well with longer time steps than 5 minutes. Furthermore, the model seemed to work relatively well without accounting for the transient effects due to thermal mass.

No description available.

Thermal remediation involves heating subsurface environments and collecting fluids in order to recover contaminants such as tetrachloroethylene (PCE) and trichloroethylene (TCE). While increasing subsurface temperature can lead to changes in the distribution of contaminants between the solid, liquid, and gas phases, there is also an increased potential for PCE and TCE to degrade. This work was performed to determine the rate of PCE and TCE degradation and products formed in laboratory-scale experiments designed to simulate thermal remediation conditions. The conditions during transport of gas-phase TCE were simulated using flow-through experiments in the temperature range from 60 to 800C. Degradation of TCE was not evident at temperatures of less than 240C; however, chloroacetic acids, which comprised less than 0.1% of the influent TCE on a carbon basis, were detected. At temperatures greater than 300C, TCE readily degraded where the identities of the degradation products were a function of oxygen and water content. With oxygen present, TCE degraded to form CO, phosgene, CO2 with minor amounts of hexachloroethane, PCE, and carbon tetrachloride. Increasing the amount of water vapor was found to decrease the amount of TCE degraded. Vapor recovery systems used during thermal treatments are anticipated to capture these TCE degradation products. However, the amount of missing carbon (~17%) in experiments completed at 800C makes the prospect of recovering all TCE degradation products doubtful. Experiments were conducted using hermetically sealed ampules to simulate heating dissolved phase PCE and TCE over periods of up to 75 days. At 120C, the first-order TCE degradation half-life was 330 days and the degradation products included CO and CO2, glycolate, formate, and chloride. The rate of TCE disappearance was increased with the addition of 1% (wt.) goethite, which suggests that the presence of iron bearing soil minerals can increase rates of TCE degradation during thermal treatment. In contaminated field samples, TCE was found to degrade to form cis-1,2-dichloroethylene at 95C coincident with the formation of hydrogen gas. Degradation of PCE was not evident in field samples or in deionized water and is not expected to degrade during thermal remediation at temperatures below 95C.

The purpose of this research is to design and optimize the performance of a unique, inexpensive 6Li neutron-capture pulse-mode ion chamber (LiPMIC) for neutron detection that overcomes the fill-gas contamination stemming from outgas of detector components. This research also provides a demonstration of performance of LiPMICs. Simulations performed with GARFIELD, a drift-chamber simulation package for ion transport in an electrostatic field, have shown that argon-methane mixtures of fill-gas allow maintenance of electron drift velocity through a surprisingly wide range of fill-gas content. During the design stage of LiPMIC development, the thicknesses of lithium metallization layer, the neutron energy conversion site of the detector, and the thickness of neutron moderator, the high-density polyethylene body, are optimized through analytical and MCNPX calculations. Also, a methodology of obtaining the suitable combination of electric field strength, electron drift velocity, and fill-gas mixtures has been tested and simulated using argon-methane gas mixtures. The LiPMIC is shown to have comparable efficiency to 3He proportional counters at a fraction of cost. Six-month long baseline measurements of overall detector performance shows there is a 3% reduction in total counts for 252Cf sources, which provides a good indicator for the longevity of the detector.

A substantial body of work exists to suggest that brain and spinal mechanisms react differently to nociceptive information. The current experiments were design to identify parallels and differences in the way the spinal cord processes nociceptive information, as compared to intact animals. In addition, pharmacological manipulations were employed to identify the opioid receptors activated by continuous shock, and to decipher at what synaptic level (e.g. pre or post synaptically) intermittent shock affects the release of endogenous opioids. A common dependent variable was used in all experiments to assess changes in nociceptive reactivity, the tail-flick test. The results revealed that intermittent and continuous stimulation have an opponent relationship on nociceptive processing in the isolated spinal cord. Continuous stimulation (3, 25-s continuous 1.5 mA tail-shocks) induced an antinociceptive response that was attenuated by prior exposure to brief (80 ms) intermittent shock (Experiment 1). When intermittent shock was given after continuous shock, intermittent shock failed to attenuate continuous shock-induced antinociception (Experiment 2). The impact of intermittent shock on continuous-shock induced antinociception decayed after 24 hours (Experiment 3). Intermittent and continuous shock enhanced the antinociceptive consequences of a moderate dose of systemic morphine (5 mg/kg) (Experiment 4). Continuous shock-induced antinociception was attenuated by equal molar concentrations of CTOP (µ opioid antagonist) and Nor-BNI (κ opioid antagonist), but not naltrindole (δ opioid antagonist) (Experiment 5). Intermittent shock failed to attenuate the antinociception induced by DAMGO (µ opioid agonist) or Dynorphin A (κ opioid agonist).

Thermal properties of one dimensional nanostructures are of interest for thermoelectric energy conversion. Thermoelectric efficiency is related to non dimensional thermoelectric figure of merit, ZT=S^2 o T/k, where S ,o , k and T are Seebeck coefficient, electrical conductivity, thermal conductivity and the absolute temperature respectively. These physical properties are interdependent. Therefore, making materials with high ZT is a very challenging task. However, nanoscale materials can overcome some of these limitations. When the size of nanomaterials is comparable to wavelength and mean free path of energy carriers, especially phonons, size effect contributes to the thermal conductivity reduction without bringing about major changes in the electrical conductivity and the Seebeck coefficient. Therefore, the figure of merit ZT can be manipulated. For example, the thermal conductivities of several silicon nanowires were more than two orders of magnitude lower than that of bulk silicon values due to the enhanced boundary scattering. Among the nanoscale semiconductor materials, Silicon-Germanium(SiGe) alloy nanowire is a promising candidate for thermoelectric materials The thermal conductivities of SiGe core-shell nanowires with core diameters of 96nm, 129nm and 177nm were measured using a batch fabricated micro device in a temperature range of 40K-450K. SiGe nanowires used in the experiment were synthesized via the Vapour-Liquid-Solid (VLS) growth method. The thermal conductivity data was compared with thermal conductivity of Si and Ge nanowires. The data was compared with SiGe alloy thin film, bulk SiGe, Si/SixGe1-x superlattice nanowire, Si/Si0.7Ge0.3 superlattice thin film and also with the thermal conductivity of Si0.5Ge0.5 calculated using the Einstein model. The thermal conductivities of these SiGe alloy nanowires observed in this work are ~20 times lower than Si nanowires, ~10 times lower than Ge nanowires, ~3-4 times lower than Si/SixGe1-x superlattice thin film, Si/SixGe1-x superlattice nanowire and about 3 time lower than bulk SiGe alloy. The low values of thermal conductivity are majorly due to the effect of alloy scattering, due to increased boundary scattering as a result of nanoscale diameters, and the interface diffuse scattering by core-shell effect. The influence of core-shell effect, alloy scattering and boundary scattering effect in reducing the thermal conductivity of these nanowires opens up opportunities for tuning thermoelectric properties which can pave way to thermoelectric materials with high figures of merit in the future.

Chip Multiprocessors (CMPs) have been prevailing in the modern microprocessor market. As the significant heat is converted by the ever-increasing power density and current leakage, the raised operating temperature in a chip has already threatened the system?s reliability and led the thermal control to be one of the most important issues needed to be addressed immediately in chip designs. Due to the cost and complexity of designing thermal packaging, many Dynamic Thermal Management (DTM) schemes have been widely adopted in modern processors. In this study, we focus on developing a simple and accurate thermal model, which provides a scheduling decision for running tasks. And we show how to design an efficient DTM scheme with negligible performance overhead. First, we propose an efficient DTM scheme for multimedia applications that tackles the thermal control problem in a unified manner. A DTM scheme for multimedia applications makes soft realtime scheduling decisions based on statistical characteristics of multimedia applications. Specifically, we model application execution characteristics as the probability distribution of the number of cycles required to decode frames. Our DTM scheme for multimedia applications has been implemented on Linux in two mobile processors providing variable clock frequencies in an Intel Pentium-M processor and an Intel Atom processor. In order to evaluate the performance of the proposed DTM scheme, we exploit two major codecs, MPEG-4 and H.264/AVC based on various frame resolutions. Our results show that our DTM scheme for multimedia applications lowers the overall temperature by 4 degrees C and the peak temperature by 6 degrees C (up to 10 degrees C), while maintaining frame drop ratio under 5% compared to existing DTM schemes for multimedia applications. Second, we propose a lightweight online workload estimation using the cumulative distribution function and architectural information via Performance Monitoring Counters (PMC) to observe the processes dynamic workload behaviors. We also present an accurate thermal model for CMP architectures to analyze the thermal correlation effects by profiling the thermal impacts from neighboring cores under the specific workload. Hence, according to the estimated workload characteristics and thermal correlation effects, we can estimate the future temperature of each core more accurately. We implement a DTM scheme considering workload characteristics and thermal correlation effects on real machines, an Intel Quad-Core Q6600 system and Dell PowerEdge 2950 (dual Intel Xeon E5310 Quad-Core) system, running applications ranging from multimedia applications to several benchmarks. Experiments results show that our DTM scheme reduces the peak temperature by 8% with 0.54% performance overhead compared to Linux Standard Scheduler, while existing DTM schemes reduce peak temperature by 4% with up to 50% performance overhead.