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.

This research is an effort to revive the use of courtyard housing clusters in a modern context, which were traditionally known for their distinctive passive cooling performance. The goal is to promote energy efficient design in hot-arid climates and temperate climates by reviving the use of courtyard housing clusters. The objective is to introduce a simplified thermal model that simulates the courtyard microclimate, which has been tested with actual field data from a case study house. The case study house was an indigenous courtyard house in Cairo, Egypt that was built around 1400 AD, having an area of about 5000 sq. ft. (i.e., comparable to the size of a single-family house) with heavy thermal mass. To accomplish this, a finite difference thermal network model was created for simulating the case study courtyard microclimate. The finite difference (FD) model showed validity as it calibrated very well against field data. This model allowed running parametric sensitivity studies on the courtyard thermal simulation factors: air change rates, thermal mass, solar absorption, wall and floor emissivity, ground temperature, cloud cover, and ambient air temperature. The results of the parametric analysis showed that the model was sensitive to variations in the air change rates, solar absorptivity, and ambient air (rooftop) temperatures. The courtyard microclimate model was then used in combination with thermal simulation software (DOE-2) to analyze the thermal performance of the case study house, which was also validated with measured field data. The DOE-2 program showed limitations when applied to the case study, non-conditioned building, and showed a convergence deficiency when simulating high thermal mass buildings. The DOE-2 program did not perform well in simulating the impact of changes in thermal mass as compared to previous published field measurements. The proposed combinations of the FD microclimate/DOE-2 simulation did not perform as well as the FD microclimate simulation. The FD courtyard microclimate simulation model with onsite data for calibration is advantageous in introducing for the first time the ability to perform computer simulations on any number of proposed courtyard design alternatives for reaching optimum thermal performance.

As the speed of integrated circuits increases, so does their power consumption. Most of this power is turned into heat, which must be dissipated effectively in order for the circuit to avoid thermal damage. Thermal control therefore has emerged as an important issue in design and management of circuits and systems. Dynamic speed scaling, where the input power is temporarily reduced by appropriately slowing down the circuit, is one of the major techniques to manage power so as to maintain safe temperature levels. In this study, we focus on thermally-constrained hard real-time systems, where timing guarantees must be met without exceeding safe temperature levels within the microprocessor. Speed scaling mechanisms provided in many of today’s processors provide opportunities to temporarily increase the processor speed beyond levels that would be safe over extended time periods. This dissertation addresses the problem of safely controlling the processor speed when scheduling mixed workloads with both hard-real-time periodic tasks and non-real-time, but latency-sensitive, aperiodic jobs. We first introduce the Transient Overclocking Server, which safely reduces the response time of aperiodic jobs in the presence of hard real-time periodic tasks and thermal constraints. We then propose a design-time (off-line) execution-budget allocation scheme for the application of the Transient Overclocking Server. We show that there is an optimal budget allocation which depends on the temporal character istics of the aperiodic workload. In order to provide a quantitative framework for the allocation of budget during system design, we present a queuing model and validate the model with results from a discrete-event simulator. Next, we describe an on-line thermally-aware transient overclocking method to reduce the response time of aperiodic jobs efficiently at run-time. We describe a modified Slack-Stealing algorithm to consider the thermal constraints of systems together with the deadline constraints of periodic tasks. With the thermal model and temperature data provided by embedded thermal sensors, we compute slack for aperiodic workload at run-time that satisfies both thermal and temporal constraints. We show that the proposed Thermally-Aware Slack-Stealing algorithm minimizes the response times of aperiodic jobs while guaranteeing both the thermal safety of the system and the schedulability of the real-time tasks. The two proposed speed control algorithms are examples of so-called proactive schemes, since they rely on a prediction of the thermal trajectory to control the temperature before safe levels are exceeded. In practice, the effectiveness of proactive speed control for the thermal management of a system relies on the accuracy of the thermal model that underlies the prediction of the effects of speed scaling and task execution on the temperature of the processor. Due to variances in the manufacturing of the circuit and of the environment it is to operate, an accurate thermal model can be gathered at deployment time only. The absence of power data makes a straightforward derivation of a model impossible. We, therefore, study and describe a methodology to infer efficiently the thermal model based on the monitoring of system temperatures and number of instructions used for task executions.

The objective of this research was to measure the effect of thermal cycling on the nanoparticle distribution and specific heat of a nanocomposite material consisting of a eutectic of lithium carbonate and potassium carbonate and 1% by mass alumina nanoparticles. The material was subjected to thermal cycling in a stainless steel tube using a temperature controlled furnace. After thermal cycling, the stainless steel tube was sectioned into three equal parts – top, middle and bottom. Composite material samples were taken from the central region and near the wall region of each section. The specific heat of this material in the temperature range of 290°C-397°C was measured using the Modulated Differential Scanning Calorimeter (MDSC) method. The concentration of alumina nanoparticles in this material was measured using neutron activation analysis. The average specific heat of the uncycled material was found to be 1.37 J/g°C.The average specific heat of the thermally cycled material was between 1.7-2.1 J/g°C. It was found that the concentration of the nanoparticle varied along the height of the sample tube. The nanoparticles tended to settle towards the bottom of the tube with thermal cycling. There was also migration of nanoparticles towards the wall of the sample tube with thermal cycling. Despite these gross movements of nanoparticles, there was no significant change in the specific heat of the nanocomposite due to thermal cycling.

In this thesis, thermal effects on Cr4+:YAG fiber are studied through numerical modeling. Crystal fiber was used as the gain medium in amplified spontaneous emission(ASE) light source, lasers, or amplifiers. Because the absorbed pump power can not be completely turned to signal in energy transition, some of the absorbed pumping power will be converted into heat, which raises the fiber temperature. In continuous-wave regime, maximum temperature, the steady-state temperature profile, and thermal stresses in the host material under single end pump are obtained by using the commercial finite elements method software ANSYS. The pump power was propagated with exponential decay inside the fiber. Because more heat was generated at the light incident region, a maximum temperature of 397K was observed from the simulation result at the same region under single-end pump of 3W. Simultaneously, a maximum tensile stress of 39 MPa was reached at the border between YAG and Silica. Finally, temperature profiles and thermal stresses were calculated in the other conditions.

In this study, a two-bed electrically-heated regenerative thermal oxidizer (RTO) was used to test NOx formation characteristics from burning air-laden N, N-dimethyl formamide (DMF) and air-laden DMF mixed with methyl ethyl ketone (MEK). The RTO contained two 0.152 m ¡Ñ 0.14 m ¡Ñ 1.0 m (L ¡Ñ W ¡Ñ H) beds both packed with gravel particles of around 1.11 cm in average diameter to a height of 1.0 m, and the packed section had a void fraction of 0.416. Performances on the thermal destructions of DMF and MEK, the thermal recovery efficiency, as well as the gas pressure drop over the regenerative beds were investigated. Experimental results indicate that, with a valve shifting time (ts) of 1.5 min, gas superficial velocities (Ug) of 0.39-0.78 m/s (evaluated at an influent air temperature of around 30oC), and set maximum destruction temperatures (Tset) of 750-950 oC, there was no NOx in the effluent gas from the RTO with no DMF in the influent air. With only DMF in the influent gas, its destruction efficiencies were 96.3 (750oC), 97.4 (850oC) and 97.9 % (950oC), and increased with increasing influent DMF concentration from 100-250 ppm. Mole ratios of ¡§NOx-N formation/DMF destruction¡¨ were found to be in the range of 0.84-1.20, and the ratio decreased with increasing influent DMF concentration within the experimental range. With both DMF and MEK in the influent gas, no significant influence was found in the NOx formation ratio and the DMF destruction efficiency with influent MEK/DMF ratios of 50/100 - 1500/100 (ppm/ppm) and the set temperatures. The NOx formation ratios were in the range of 0.85-1.07. The Ergun equation was adequate for the estimation of the pressure drop for the gas flowing over the packed regenerative beds in the Ug range of 37-0.74 m/s. It was also found that the thermal recovery efficiency was decreasing with the increasing Ug and invariant with Tset.

The area of advanced gate dielectrics has gained considerable attention recently, and there are significant leakage current and reliability concerns for oxy-nitride in this regime. So it¡¦s an important business to use alternate high-k dielectrics instead of oxy-nitride. Titanium dieoxide shows a high dielectric constant for dielectric applications. Besides, strontium can create additional oxygen vacancies that can enhance dielectric constant. In this study, we prepared SrTiO3 film by liquid phase deposition which is a novel material considered to have high dielectric constant. From several characteristic measurements, we found that SrTiO3 with exhibiting higher dielectric constant and well interface state which is very promising candidates to instead of titanium dieoxide. The physical and chemical properties of SrTiO3 films by means of several measuring instruments, including Fourier transform infrared spectrometer (FTIR), secondary ion spectrometer (SIMS), and X-Ray diffractometer (XRD). An Al / SrTiO3 / Si metal-oxide-semiconductor (MOS) capacitor structure was used for the electrical measurements. To improve the electrical properties, we investigated the characteristics of SrTiO3 films after annealing in oxygen, nitrous oxide, and nitrogen ambient. Including the variations of thickness, structure, dielectric constant, and leakage current were discussed in this work.

In this study, PEEK/SiO2 nanocomposites were fabricated by means of simple compression molding technique. The performances and properties of the resulting PEEK nanocomposites were examined in terms of tensile loading, hardness, dynamic mechanical analysis (DMA), thermal mechanical analysis (TMA), thermogravimetry analysis (TGA), differential scanning calorimetry (DSC), X-ray diffraction (XRD), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). The results indicated that the modified nanosilica was seen to disperse more uniformly than the unmodified counterparty. The XRD patterns of the modified-silica filled PEEK composites reveal a systematic shift toward higher angles, suggesting the smaller d-spacing of the PEEK crystallites. As for the thermal properties of the resulting PEEK nanocomposites, there is no significant difference for the melting and crystallization temperatures, as well as the degree of crystallization between the modified and unmodified silica filled PEEK nanocomposites. The TMA results show that the coefficient of thermal expansion (CTE) becomes lowered when the content of the nanosilica increases. Furthermore, the CTE of the modified-silica filled PEEK nanocomposites shows the higher CTE values, as compared with those of the unmodified counterparts. In addition, the inclusion of the nanosilica could improve the microhardness and the stiffness of the resulting PEEK nanocomposites with the sacrifice of the elongation, as evident from the tension and DMA testing.

In this thesis, we use reactive RF magnetron sputtering to deposit zinc oxide (ZnO) buffer layer and main layer on SiO2/Si substrate at room temperature. After various annealing treatments, the ZnO nanowires can be obtained. The effects of buffer layer on the crystallization of ZnO main layer and the zinc-to-oxygen ratio in the main layer on the growth of the ZnO nanowires are analyzed by PL, SEM, XRD and EDS. Finally, the growth mechanism of the ZnO nanowires is investigated by various annealing temperatures. According to the experimental results, surplus zinc in the main layer is necessary for the ZnO nanowires growth. When the annealing temperature is higher than the melting point of zinc, it will melt and be extruded onto thin film surface as a result of the thermal stress. As soon as the melting zinc on the film surface reacts with the oxygen in the air, ZnO nanowires can be obtained. The optimum ZnO nanowires which possess better morphology and high density are revealed by conventional thermal annealing at 600¢J for 90 minutes.

Recently, there has been increasing demands for high dielectric materials to replace SiO2 for high-density dynamic random access memories with ultralarge scale integration. TiO2 and BaTiO3 are very promising insulators for applications to DRAMs, as they exhibit higher dielectric constant.The growths of TiO2 and BaTiO3 thin films on (100) silicon are studied by MOCVD using Ti(i-OC3H7)4, Ba(DPM)2(tetraene)2 and N2O as precursors. The growth was performed in a cold wall horizontal system in the temperature range of 350~700¢J. The growth rates of TiO2 and BaTiO3 films are affected by the Ti flow rate, growth temperature and reactor pressure. The structures of TiO2 and BaTiO3 films are polycrystalline by X-ray diffraction examinations. The dielectric constant of as-grown TiO2 can reach 85 and BaTiO3 can reach 300 derived by C-V curves with the contact area 3.14¡Ñ10-4 cm2. In addition, the influences of postannealing treatment under an O2 and N2 ambient with different annealing temperature and time on the structural and electrical properties of as-grown TiO2 films will be also studied. However, TiO2 and BaTiO3 films have columnar structures acted the paths of leakage current. We use thermal annealing to reduce the leakage current. In the future, to enhance the dielectric constant and reduce the leakage current of the films is the goal in our study.