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Thermal properties of ten different seafood were measured in this research. They included bluefish (<i>Pomatomus saltatrix</i>), croaker (<i>Micropogonias undulatus</i>), spanish mackerel (<i>Scomberomorus maculatus</i>), pink salmon (<i>Oncorhynhus gorbuscha</i>), black seabass (<i>Atractoscion nobilis</i>), spot (<i>Leiostomus xanthurus</i>), shrimp(<i>Pandalus borealis</i>), tilapia (<i>Tilapia aurea</i>), grey sea trout(</i>Cynoscion regalis</i>), and yellow fin tuna (<i>Thunnus albacares</i>) (Wheaton, et al. 1985). Thermal properties measured were thermal conductivity, thermal diffusivity, and specific heat from 5 to 30^oC. Enthalpy was measured from -40 to 30^oC. Moisture and fat content were measured. Thermal conductivity and thermal diffusivity were measured by a rapid transient technique using a bead thermistor probe. Specific heat and enthalpy were measured using a differential scanning calorimeter. Moisture content and fat content were measured by the AOAC specified oven dry method and ether extraction method, respectively. The measured thermal properties agreed well with the scarcely available literature values. They were then statistically correlated with moisture and fat content. Based on statistical analysis, mathematical models relating thermal properties and composition were proposed and compared with the models available in the literature. Models for thermal conductivity and specific heat were recommended to predict these properties of meats and fish with similar composition. / Master of Science

In the recent years, there has been a growing interest in droplet-based (digital) microfluidic systems due to their ability to handle multiple discrete samples in a self-contained configuration compared to continuous flow systems. Various methods for droplet manipulation are currently available based on hydrodynamic, electrostatic, chemical, photonic and thermal interactions. High speed, controlled response and minimal thermal loading with least contamination are required in practical applications, especially in chemistry and biology. Although, thermal actuation of droplets has been recognized as an attractive choice due to a wide range of thermomechanical properties that can be exploited, the previous studies yielded limited success in addressing issues such as droplet evaporation, contamination, pinning, hysteresis and irreversibility that are associated with using solid substrate platforms In order to overcome shortcomings of traditional approaches, a novel thermally-actuated droplet manipulation platform based on using an inert liquid film was proposed and its working mechanisms were studied. Droplets at the air-liquid interface of immiscible liquids usually form partially submerged lens shapes (e.g. water on oil). In the thermally-induced motion of droplets on the free surface of immiscible liquid films, lens-shaped droplets move from warm toward cooler regions. In addition to this structure, we showed that droplets released from critical heights above the target liquid can sustain the impact iv and at the end maintain a spherical ball-shape configuration above the surface, despite undergoing large deformation. It was discovered in this study that such spherical droplets migrate in the opposite direction to lens droplets when subject to a thermal gradient; i.e. direction of increasing temperatures. The existence of this metastable spherical state above the free surface and its transition into more stable lens configuration was investigated using optical diagnostic tools and theoretical analysis. Opposite direction of motion observed for droplets at the free surface of immiscible liquids was explained based on droplet shape at the interface and the dynamics of thin liquid films subject to lateral thermal gradients: mainly 1) deformation of the free surface and 2) development of an outward moving flow (hot to cold) at the free surface due to surface tension gradients caused by thermal gradients. A lens droplet moves due to the free surface flow caused by Marangoni convection which is from hot to cold. On the other hand, the spherical droplet moves towards the maximum depression on the free surface, occurring at the hottest region as a result of the balance between gravity and drag forces from the opposing free surface flow. The proposed theoretical models predict experimental observations of droplet motion due to thermal gradients satisfactorily. Opposite responses of thermally-induced motion of lens and spherical droplets on a thin liquid layer, were characterized experimentally and compared to theory by v studying droplet motion in an exponentially-decaying temperature field maintained across the length of a shallow liquid layer. The effect of droplet size and magnitude of thermal gradient (slope) on drop velocity were investigated. The down-scaling effect is prominent, which shows that the proposed concept of droplet manipulation could be used favorably in miniaturized platforms. Based on the theoretical development and measurements obtained from meso-scale experiments, a silicon-based droplet transportation platform with embedded metal film micro heaters was developed. A thin layer of a chemically-inert and thermally stable liquid was chosen as the carrier liquid. Heaters were interfaced with control electronics and driven through a computer graphical user interface. By creating appropriate spatio-temporal thermal gradient maps, transport of droplets on predetermined pathways was demonstrated with a high level of controllability and speed.

yes / The thermal behavior of aluminium oxide-water nanofluid in a double pipe carbon steel heat exchanger was investigated in the present study. The overall heat transfer coefficient, Nusselt, and heat transfer coefficient of nanofluid were compared with the base fluid. The volume fraction of the nanoparticles was 1%. By adding nanoparticles to the fluid, the thermal properties of the base fluid improved significantly. The hot and cold fluid flow was considered counter-current, and the nanofluid was pumped into the inner tube and once into the outer tube, and the flow rate of each fluid was 0.05 kg/s. The convective heat transfer and the overall heat transfer coefficient enhanced 94% and 253% for the hot fluid flow in the outer tube and 308 % and 144% for the hot fluid flow in the inner tube, respectively. The pressure drop calculations also showed that the pressure drop would not change significantly when using nanofluid.

Friction Stir Welding (FSW) process development is very costly, and it is still experimental. A predictive model would optimize the weld by changing parameters and obtaining results that reflect the physical process. Friction is the primary adjustable parameter in FSW modeling. Currently, friction model selection is not physic-based. It is based on what is available and contributes to the best fit between the model and experimental data. The research objective is to characterize the interface tool/base material by studying the effect of tool friction coefficient and thermal properties. This is accomplished by changing welding parameters such as force, rpm, and temperature and studying the effects on dependent variables that contribute to the shear stress produced by friction. The study's findings challenge traditional friction concepts by revealing how the rapid engagement of a tool with the base material significantly reduces the impact of sliding friction. Instead, the observed friction primarily depends on the resistance of the shear layer to the tool's motion. This resistance, in turn, is chiefly influenced by the interface temperature, a factor strongly impacted by the thermal diffusivity of the tool material. Remarkably, thermal diffusivity holds the most influence (49.3%) on interface temperature. The interface of the tool material is characterized by a shear stress equation integrating pressure, RPM, thermal diffusivity, and interface temperature. Additionally, the investigation highlights the critical role of heat extraction, where materials with higher thermal diffusivity exhibit distinct outcomes: heightened torque, reduced surface temperature, minimized layer volumes, and shorter operation times.

Structural applications, including aircraft, ships, and offshore oil drilling platforms, have witnessed a surge in composite material usage. However, exposure to elevated temperatures poses a significant risk to these materials, especially in scenarios such as fires and high-temperature exhaust gas impingement. Despite limited or no visible damage, composite properties can undergo significant degradation, leading to potential in-service failures and jeopardizing operational safety and integrity. It was previously determined that the accuracy of the equipment and methodology used for measuring elevated temperature thermal properties, particularly in predicting composite material thermal properties could not meet the necessary precision. Using an inverse analysis technique to solve for the thermal conductivity and specific heat capacity, the thermal properties of composite materials can be determined. These thermal properties can then be used in a rapid heat damage assessment and failure prediction tool that can be updated based on additional data provided during inspection which takes into account material state changes and damage development due to the elevated temperature exposure and provides a way to incorporate those changes into subsequent structural analyses. / Master of Science / Composite materials are great for structural usage in a wide variety of endeavors. The problem with them is that when exposed to high temperatures, the composite materials properties can change. This can cause failures from seemingly good material which can cause serious bodily harm or even death. My research aims to help bolster the safety and integrity of composite material structures by providing a reliable way to determine their thermal properties. With the thermal properties known, development of a tool that can predict composite material failures which can take into account changes in the material due to thermal damage.

Materials comprising of two or more polymeric components have achieved considerable technological significance in the last decade or so due to the unique properties often not attainable in their homopolymeric counterparts. In the present work, two such systemsone involving modified thermosets and the other involving thermoplastic polymer blends, have been studied with regard to their morphological and thermal properties. Both systems take the advantage of not only the physical interactions between the components involved but also their themooxidative properties, giving rise to novel properties that have both fundamental and practical importance. The network system consists of a phenolic novolac based epoxy cured in the presence of low molecular weight poly (propylene oxide). The resulting morphology of these polymers has been studied with the help of scanning electron microscopy. / Ph. D.

In this dissertation a simplified nondimensional approach for the thermal analysis of power hybrid circuits is presented. The new technique uses only the metallization and the substrate as layers and represents everything below the substrate by an external thermal resistance (expressed as an equivalent convective heat transfer coefficient, h). In this study, the impact on thermal management of thick film metallization and copper cladding on alumina, aluminum nitride, and beryllia ceramic substrates is compared. The thermal conductivity of the substrate material, the thickness of the copper layer, the thermal resistance of the heat sink system, the size of the device, and the spacing between two heat dissipating devices are considered. The model results show that increasing the thickness of the copper layer can significantly decrease the device temperatures on alumina but may increase temperatures on high thermal conductivity substrates. Moreover, the model results show that increasing the thickness of the copper layer requires that the devices be placed farther apart to prevent thermal interaction. The results also demonstrate that the external heat sink resistance can have a significant impact on the heat flow paths and temperatures in the substrate. As the external resistance increases, the spacing required to prevent thermal interaction also increases. In addition to the above, a series of experiments were conducted on various hybrid circuits samples for a low and high heat sink external resistance, i.e., large and small convective heat transfer coefficients, respectively. These samples were constructed using thick film resistors as heat sources on alumina and beryllia substrates. The temperature rise was measured using infrared thermal imaging technique. These experimental results were compared to results predicted by the thermal model. In general, the model underpredicts or overpredicts the experimental temperature rise by 0-2 ·C and the agreement is within the experimental uncertainty of ±2°C. / Ph. D.

Ballistic measurements were made of the critical magnetic fields of superconducting. cylinders of cerium-doped lead. Within the accuracy of our measurements, the introduction of the paramagnetic impurity, cerium, in lead has no effect other than a slight broadening of the transition. The samples, containing 0.00, 0.10, 1.0, and 1.5 atomic percent cerium in lead had been vacuum cast in pyrex tubes. The relative fractions of the cerium in these samples and their final purities were tested by the techniques of neutron activation analysis. / Master of Science