A phase sensitive measurement technique that permits the simultaneous determination of two independent thermal properties of thin dielectric films is presented. Applying the technique results in a film's thermal diffusivity and effusivity, from which the thermal conductivity and specific heat can be calculated. The technique involves measuring a specimen's front surface temperature response to a periodic heating signal. The heating signal is produced by passing current through a thin layer of nichrome that is deposited on the specimen's surface, and the temperature response is measured with a HgCdTe infrared detector operating at 77 K. The signal that is produced by the infrared detector is first conditioned, and then sent to a lock-in amplifier. The lock-in is used to extract the phase shift present between the temperature and heating signal through a frequency range of 500 Hz-20 kHz. The corresponding phase data is fit to an analytical model using thermal diffusivity and effusivity as fitting parameters. The method has been applied effectively to 1.72 ��m films of Si0��� that have been thermally grown on a silicon substrate. Thermal properties have been obtained through a temperature range of 25��C-300��C. One unanticipated outcome stemming from analysis of the experimental data is the ability to extract both the thermal conductivity and specific heat of a thin film from phase information alone, with no need for signal magnitude. This improves the overall utility of the measurement process and provides a 'clean', direct path with fewer assumptions between data and final results. The thermal properties determined so far with this method are consistent with past work on Si0��� films. / Graduation date: 1998

Zirconium press plates have been developed for the production of melamine coated particle board, using shot-peening to achieve the desired plate (and therefore coated particle board) surface texture. Service temperatures of the press plates approach 200��C. This study examined the microstructural effects of extended exposure of shot-peened zirconium to temperatures of 200��C and 300��C. Softening of the surface may reduce wear resistance and possibly the surface morphology of the plate, affecting the usability of the plates. It was discovered that the shot-peened surface of the plates experienced a loss in hardness from approximately 230 VHN (DPH) to about 220 VHN after 560 hrs at 200��C. The same drop in hardness was experienced after only 5.5 hrs at 300��C. This decrease in hardness was determined from hardness profiles before and after heat treating the zirconium to various times from 0.5 hours to 4458 hrs and 2790 hrs at 200��C and 300��C respectively. The decrease in hardness is believed to be a result of static recovery, the annihilation of point and/or line defects and/or alignment of dislocations into relatively low misorientation substantially relatively close to the shot-peened surface (about 35 ��m), and decreased more modestly over the next 100 ��m until virtually no drop was experienced further than approximately 150 ��m from the surface. The shot-peening hardens the surface region which extends about 150 ��m from the surface. Thus, the level of recovery appears to depend on the stored energy associated with cold work, or ambient temperature deformation. This increases from about 2-3% cold work (equivalent percent cold reduction from rolling) in the bulk of the specimens to near 99% at the surface resulting from shot-peening. The dislocation structure of the shot-peened zirconium was examined in the as-peened as well as the annealed conditions using transmission electron microscopy. / Graduation date: 1997

The thesis has the objective of design a methodological model for evaluate and compare the behaviour of external walls exposed to moisture phenomena. The comparison is related to different variables us for example: thermal conductivity, thermal transmitance, moisture content in the element along the time, P.O. Fanger theory of comfort, risk grouwth of mould among the others parameters. The model is developed in function of two softwares that permit sensibilyze the performance of building elements in relation of the presence of different quantities of moisture inside of them along the year. In this case, the model is probe with the use of TRNSYS 15 and WUFI 3.2 Pro softwares. The results show that there are many differences in the analysis of the different parameters in the cases with the materials in dry and wet state. Also, is possible to realize that the improve of any constructive solutions they are amortized in periods of time that no exceed more than three years in relation to the save of energy for the improvement in the themal conductivity of the materials.

Nichia Corporation announced blue Light Emitting Diodes (LED) by 1993. They were widely used in markets by 1996 after combining blue LED with yellow phosphors to emit white lights. There¡¦re two keys to utilize LED as replacement light energy; one is to increase the chipset brightness, while another is to use LED arrays instead of single LED. Around 15 to 20% of LED illuminant will be transformed to visible light, while up to 85% of the LED illuminant will be transformed to heat. Therefore, before there¡¦s obvious breakthrough on LED constructions to heat, thermal management of LED is relatively important. The purpose of this research is to do value simulation by slightly change the construction of low power LED and increase its power (150, 350mA), to investigate the differences of high power LED in thermal transmission by single LED and LED arrays under different parameters, and learn if the emitted heat can be tolerated by its key materials. This research can be used as the reference to design LED products for engineers. According to the analysis result, under environment temperature of 25 to 80 Celsius Degree, the temperatures of a 0.5W LED chipset, mounted board and packing materials will increase around 3 to 4 Celsius Degrees when the environment temperature will increase one Celsius Degree. If we increase the LED chipset power to be 1W, the temperature increase for chipset and mounted board is around 3 to 4 Celsius Degrees while the temperature increase for packing materials is 3 to 9 Celsius Degrees. Regarding high power LED arrays, according to the analysis result, when the distance between two LEDs is too small, the temperature will increase dramatically; when the P value (see report content) is over 5mm, per 1mm distance increase, the chipset temperature decrease will become 1 to 2.5 Celsius Degrees from initially 3 to 5 Celsius Degrees. If we further increase the two LEDs distance, there¡¦ll be no significant effect from chipset itself but only the mounted board.

Recently Kalman filter has been well applied to the problems of image restoration. In this thesis, we apply Kalman filter to estimate the optical transfer function for an imaging system. The signal model is the optical transfer function obtained from a ratio of the defected and clean pictures in frequency domain. There is thermal noise involved in sampling the optical image signal. We model this thermal noise as the additive measurement noise. We remove the thermal noise by Winner filtering. This filtered image is finally restored by the above estimated the optical transfer function. The experiments are set up by the instruments including the video camera, capture card, and personal computer. Experimental results, including the estimation of gamma and noise power, have demonstrated that the estimated optical transfer function is useful for image restoration.

Heating, Ventilation, and Air Conditioning (HVAC) accounts for about half of the energy consumption in buildings. HVAC energy consumption can be reduced by changing the indoor air temperature setpoint, but changing the setpoint too aggressively can overly reduce user comfort. We have therefore designed and implemented SPOT: a Smart Per- sonalized O ce Thermal control system that balances energy conservation with personal thermal comfort in an o ce environment. SPOT relies on a new model for personal ther- mal comfort that we call the Predicted Personal Vote model. This model quantitatively predicts human comfort based on a set of underlying measurable environmental and per- sonal parameters. SPOT uses a set of sensors, including a Microsoft Kinect, to measure the parameters underlying the PPV model, then controls heating and cooling elements to dynamically adjust indoor temperature to maintain comfort. Based on a deployment of SPOT in a real o ce environment, we nd that SPOT can accurately maintain per- sonal comfort despite environmental uctuations and allows a worker to balance personal comfort with energy use.

Elastin-like polypeptides (ELPs) consist of simple pentapeptide repeats which can be easily modified by substituting various amino acid residues to control its properties. This provides an ideal platform for studying hydrophobic collapse and secondary/tertiary structure formation. In this thesis, the collapse process of ELP was studied with differential scanning calorimetry (DSC). In DSC thermal cycling, a clear conformational transition was observed. Also, a transiently stable state of ELP V5-120 was noted and it was found that the formation of this state was related to temperature, ramping rate and stabilization time. To explain this, a conformational redistribution model is proposed in which there are two conformations in the ELP solution below its transition temperature. However, after the system is heated up and cooled back down, one of the conformations remains the same while the other one changes to two new conformations. After the conformational distribution is done, the ELP stays in a transiently stable state before gradually shifting back to the original, pre-heat-treatment state. Bi-Gaussian fitting was used to fit DSC response curve and monitor the changes of the different conformations in the system. The influence of ramping rate on the process of conformational redistribution was explained through the equilibration time at each temperature point through heating and cooling. Overall, the ELP V5-120 system is in a dynamic conformational equilibrium, and the equilibration time is much longer than earlier expectations.

RELAP5-3D has been coupled with both DAKOTA and STAR-CCM+ in order to expand the capability of the thermal-hydraulic code and facilitate complex studies of desired systems. In the first study, RELAP5-3D was coupled with DAKOTA to perform a sensitivity study of the South Texas Project (STP) power plant during steady-state and transient scenarios. The coupled software was validated by analyzing the simulation results with respect of the physical expectations and behavior of the power plant, and thermal-hydraulic parameters which caused greatest sensitivity where identified: inlet core temperature and reactor thermal power. These variables, along with break size and discharge coefficients, were used for further investigation of the sensitivity of the RELAP5-3D LOCA transient simulation under three difference cases: two inch break, six inch break, and guillotine break. Reactor thermal power, core inlet temperature, and break size were identified as producing the greatest sensitivity; therefore, future research would include uncertainty quantification for these parameters. In the second study, a small scale experimental facility, designed to study the thermal hydraulic phenomena of the Reactor Cavity Cooling System (RCCS) for a Very High Temperature Reactor (VHTR), was used as a model to test the capabilities of coupling Star-CCM+ and RELAP5-3D. This chapter discusses the capabilities and limitations of the STAR-CCM+/RELAP5-3D coupling, and a simulation, on the RCCS facility, was performed using STAR-CCM+ to study the flow patterns where expected complex flow phenomena occur and RELAP5-3D for the complete system. The code showed inability to perform flow coupling simulations and it is unable, at this time, to handle closed loop systems. The thermal coupling simulation was successful and showed congruent qualitative results to physical expectations. The locations of large fluid vortices were located specifically in the pipes closest to the inlet of the bottom manifold. In conclusion, simulations using coupled codes were presented which greatly improved the capabilities of RELAP5-3D stand-alone and computational time required to perform complex thermal-hydraulic studies. These improvements show greatly benefit for industrial applications in order to perform large scale thermal-hydraulic systems studies with greater accuracy while minimizing simulation time.

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.

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.