Enhanced heat transfer in electronic hardware by direct, small-scale actuation is investigated experimentally in two test bed configurations. The first configuration exploits the unsteady motions induced by a vibrating reed embedded within a heated duct (in contact with hardware that needs cooling) to enhance forced convection transport heat from the duct surfaces. The flow within the duct is either exclusively driven by the reed or, for higher heat flux, is augmented by an induced core flow. The time harmonic motion of the reed results in the regular shedding of vortical structures that interact with the inner surfaces in the absence and presence of a core flow. The second configuration focuses on the effects of small scale motions induced by a synthetic jet on heat transfer within an advanced heat sink. The synthetic jets emanate directly through the base of the heat sink and induce a recirculating flow between the fins, resulting in a lower thermal resistance than what is typically achieved with traditional fans. The unsteady flow characteristics in both configurations are investigated using particle image velocimetry (PIV). Of particular interest are the effects of small-scale motions and enhanced mixing on heat transfer compared to conventional time-invariant flows at similar or higher Reynolds numbers.

<p>In this thesis the sink-effect in indoor materials wasstudied using mathematical modelling and experimental studies.The sink-effect is a concept which is commonly used tocharacterise the ability of different indoor materials to sorbcontaminants present in the indoor air. The sorption process ismore or less reversible, i.e. molecules sorbed in materials athigh contaminant concentrations may again be desorbed at lowerconcentrations. Knowledge of the sorption capacity of materialsand the rate at which sorption and desorption takes place is offundamental importance for mathematical simulation of indoorair quality. The aim of this work is to contribute withknowledge about how the sink-effect can be described inmathematical terms and how the interaction parametersdescribing the sorption capacity and sorption/desorptionkinetics can be determined. The work has been of amethodological nature. The procedure has been to set upphysically sound mathematical models of varying complexity andto develop small-scale chamber experiments. Two differentdynamic chamber methods have been used. One is based on amodified standard FLEC-chamber while the other uses a chamberwith two compartments, one on each side of the material. The"twin-compartment" method was designed due to the observationthat the contaminant readily permeated straight through theselected materials, which resulted in uncontrolled radiallosses in the FLEC-chamber. In order to be useful forcomparison between experiments and calculations and parameterfitting, the boundary conditions in the chambers must beprecisely known and controlled. This matter has shown to be themost crucial and difficult problem in the research. A varietyof mathematical models for the sink-effect have been proposed.In some models advanced fluid simulations were used in order totest the influence ofill-defined flow boundary conditions. Theaim of the modelling is to find a formulation with a minimum ofinteraction parameters, which is generally useful, i.e. both insmall-scale laboratory environments and in full-scale like anoffice room. Estimated model parameters are shown to be able toyield a reasonably good fit to experimental data for thesorption process but a less satisfactory fit for the desorptionprocess.</p><p><b>Keywords:</b>sink-effect, sorption, adsorption, diffusion,indoor air quality, volatile organic compounds, VOC,contaminants, building materials</p>

A key challenge for three dimensional (3D) integrated circuits (ICs) is thermal management. There are two main thermal challenges in typical 3D ICs. First, in the homogeneous integration with multiple high-power tiers, an effective cooling solution that scales with the number of dice in the stack is needed. Second, in the heterogeneous integration, an effective thermal isolation solution is needed to ‘protect’ the low-power tier from the high-power tier. This research focuses to address these two thermal challenges through hybrid microfluidic cooling and thermal isolation technologies. Within-tier microfluidic cooling is proposed and demonstrated to cool a stack with multiple high-power tiers. Electrical thermal co-analysis is performed to understand the trade-offs between through silicon via (TSV) parasitics and heat sink performance. A TSV-compatible micropin-fin heat sink is designed, fabricated and thermally characterized in a single tier, and benchmarked with a conventional air-cooled heat sink. The designed heat sink has a thermal resistance of 0.269 K·cm2/W at a flow rate of 70 mL/min. High aspect ratios TSVs (18:1) are integrated in the micropin-fins. Within-tier microfluidic cooling is then implemented in 3D stacks to emulate different heating scenarios, such as memory-on-processor and processor-on-processor. Air gap and mechanically flexible interconnects (MFIs) are proposed for the first time to decrease the vertical thermal coupling between high-power (e.g. processor) and low-power tiers (e.g. memory or nanophotonics). A two-tier testbed with the proposed thermal isolation technology is designed, fabricated and tested. Compared with conventional 3D integration approach, thermal isolation technology helps reduce the temperature at a fixed location in the low-tier by 12.9 °C. The resistance of a single MFI is measured to be 46.49 mΩ.

The sediment budget and paleogeography was reconstructed for the Maastrichtian fluvial to coastal plain Lance Formation (>200m thick) that developed coevally with the shoreline/shelf Fox Hills Sandstone (>200m thick) and deep-water Lewis Shale (>750m thick) in a complete source-to-sink system in the Washakie and Great Divide Basins of south central Wyoming. The system initiated during the final Western Interior Seaway (WIS) transgression and the onset of the Laramide Orogeny rapid subsidence (>2km in 1.9 My) that largely outpaced sediment flux into the basin so the system became and remained a deep-water (>500m water depth) basin beyond the Lance-Fox Hills shelf prism. The active tectonic setting and rapid subsidence caused the Lance fluvial and coastal plain deposits to aggrade and accumulate behind the generally rising shoreline trajectory of the Fox Hills Sandstone. The depositional succession is subdivided into 15 clinothem units and the Lance Formation is best exposed in outcrops in clinoforms 10, 11, and 12. Subsurface analysis correlates key stratigraphic surfaces across the basin to define the sediment budget and clinoform architecture. Field analysis along clinoform 12 on the east side of the basin details facies and paleohydraulic dimensions. Sediment partitioning shows the regressive and transgressive systems tracts (RST and TST) form complementary wedges such that the RST thickens basinward and the TST thins basinward, reflecting the preferential storage of sediment. Channels measured in the field and subsurface datasets are similar in thickness (2m-16m) and suggest braided channel morphology with channel belts from 6.2-8.4km. N/NE paleocurrent trends departing from the subsurface dataset and previous studies of the system provide evidence of possible tidal influences in a developed shoreline embayment or an east to west supply from the basement-cored Rawlins and Sierra Madre Uplifts in the east. The fluvial Lance Formation paleogeography associated with the RST and TST is primarily driven both by modest, Late Cretaceous relative sea level changes and sediment supply linked to the tectonic setting and climate. / text

This thesis numerically studied mass transfer during fully confined liquid jet impingement on a rotating target disk of finite thickness and radius. The study involved laminar flow with jet Reynolds numbers from 650 to 1500. The nozzle to plate distance ratio was in the range of 0.5 to 2.0, the Schmidt number ranged from 1720 to 2513, and rotational speed was up to 325 rpm. In addition, the jet impingement to a stationary disk was also simulated for the purpose of comparison. The electrochemical fluid used was an electrolyte containing 0.005moles per liter potassium ferricyanide (K3(Fe(CN6)), 0.02moles per liter ferrocyanide (FeCN6?4), and 0.5moles per liter potassium carbonate (K2CO3). The rate of mass transfer of this electrolyte was compared to Sodium Hydroxide (NaOH) and Hydrochloric acid (HCl) electrochemical solutions. The material of the rotating disk was made of 99.98% nickel and 0.02% of chromium, cobalt and aluminum. The rate of mass transfer was also examined for different geometrical shapes of conical, convex, and concave confinement plates over a spinning disk. The results obtained are found to be in agreement with previous experimental and numerical studies. The study of heat transfer involved a microchannel for a composite channel of trapezoidal cross-section fabricated by etching a silicon wafer and bonding it with a slab of gadolinium. Gadolinium is a magnetic material that exhibits high temperature rise during adiabatic magnetization around its transition temperature of 295K. Heat was generated in the substrate by the application of magnetic field. Water, ammonia, and FC-77 were studied as the possible working fluids. Thorough investigation for velocity and temperature distribution was performed by varying channel aspect ratio, Reynolds number, and the magnetic field. The thickness of gadolinium slab, spacing between channels in the heat exchanger, and fluid flow rate were varied. To check the validity of simulation, the results were compared with existing results for single material channels. Results showed that Nusselt number is larger near the inlet and decreases downstream. Also, an increase in Reynolds number increases the total Nusselt number of the system.

Kyoto University (京都大学) / 0048 / 新制・課程博士 / 博士(農学) / 甲第19051号 / 農博第2129号 / 新制||農||1033 / 32002 / 京都大学大学院農学研究科農学専攻 / (主査)教授 白岩 立彦, 教授 奥本 裕, 准教授 中﨑 鉄也 / 学位規則第4条第1項該当

This thesis investigates near-field wireless power transfer using multiple transmitters or multiple receivers. First, transmitter diversity is investigated in terms of the power transfer efficiency (PTE). It is found that an improvement in the PTE can be achieved by increasing the number of transmitters. Furthermore, a region of constant PTE can be created with the proper arrangement of transmitters. Next, receiver diversity is investigated in detail. An improvement in the PTE can be also achieved by increasing the number of receivers. However, it is shown that when two or more receivers are closely located, the PTE is reduced due to mutual coupling between receivers. This is termed a ‘sink’ phenomenon, and it is investigated through measurement and simulation. Finally, to account for more general situations of multiple transmitters and multiple receivers, Monte-Carlo simulation is applied. The cumulative distribution function (CDF) is used to interpret the results of the Monte-Carlo simulation. The transmitter and receiver diversity gain can be found based on the CDF. Moreover, the sink phenomenon can be observed by analyzing the CDF curve. Several strategies for positioning receivers are introduced to reduce the sink phenomenon. The results of the Monte-Carlo simulation also show that a saturation in the transmitter or receiver gain is reached when the number of transmitters or receivers is increased. Therefore, increasing the number of transmitters or receivers beyond a certain number does not help increase the PTE. / text

The objective of this research was to design aluminum powder metallurgy (PM) alloys and processing strategies that yielded sintered products with thermal properties that rivaled those of the cast and wrought aluminum alloys traditionally employed in heat sink manufacture. Research has emphasized PM alloys within the Al-Mg-Sn system. In one sub-theme of research the general processing response of each PM alloy was investigated through a combination of sintering trials, sintered density measurements, and microstructural assessments. In a second, the thermal properties of sintered products were studied. Thermal conductivity was first determined using a calculated approach through discrete measurements of specific heat capacity, thermal diffusivity and density and subsequently verified using a transient plane source technique on larger specimens. Experimental PM alloys achieved >99% theoretical density and exhibited thermal conductivity that ranged from 179 Wm-1K-1 to 225 Wm-1K-1. Thermal performance was largely dominated by the amount of magnesium present within the aluminum grains and in turn, bulk alloy chemistry. Data confirmed that the novel PM alloys were highly competitive with even the most advanced heat sink materials such as wrought 6063 and 6061. Two methods of thermal analysis were employed in order to determine the thermal conductivity of each alloy. This first consisted of individual analysis of the specific heat capacity (Cp), thermal diffusivity (?) and density (?) as a function of temperature for each alloy. The thermal conductivity (K) was subsequently determined through the relationship: K=C_p ??. The second means of thermal analysis was a direct thermal conductivity measure using a transient plane source (TPS). The thermal diffusivity and density of samples were both found to decrease with temperature in a linear fashion. Conversely, the specific heat capacity was found to increase with temperature. The only measured thermal property that appeared to be influenced by the alloy chemistry was the thermal diffusivity (and subsequently the calculated thermal conductivity). Both means of thermal analysis showed high thermal conductivity in alloys with low concentrations of magnesium, demonstrating the significance of having alloying elements in solid solution with aluminum. Overall, several alloys were developed using a press and sinter approach that produced higher levels of thermal conductivity than conventional aluminum heat sink materials. The highest thermal conductivity was achieved by alloy Al-0.6Mg-1.5Sn with a calculated value of 225.4 Wm-1K-1. This novel aluminum PM alloy was found to exceed both wrought 6061 and 6063 (195 and 217 Wm-1K-1 respectively). Furthermore, PM alloy Al-0.6Mg-1.5Sn was found to have a significant advantage over die-cast A390 (142 Wm-1K-1).

Quantifying how hillslopes respond to river incision and climate change is fundamental to understanding the geomorphic evolution of tectonically uplifting landscapes during glacial-interglacial cycles. Hillslope adjustment in the form of deep-seated bedrock landslides can account for a large proportion of the regional sediment yield and denudation rates for rapidly uplifting landscapes. However, the timing and magnitude of the response of hillslopes to climatic and tectonic forcing in moderate uplift temperate maritime catchments characteristic of many active margins worldwide is not well quantified. This study seeks to investigate how hillslopes respond to climate-modulated river incision and to quantify the magnitude of the sediment flux from this response in a typical active margin setting. The non-glacialWaipaoa Sedimentary System (WSS) on the East Coast of the North Island of New Zealand consists of river catchments, coastal foothills to uplifting mountain ranges, and terrestrial and marine sediment depocentres collectively underlain by relatively young (Cretaceous and younger) sedimentary rocks within a tectonically active setting and temperate maritime climate. These attributes make theWSS similar to many coastal catchments on oceanic-continental convergent margins worldwide. However, because of widespread destruction of primary forests for conversion to pasture lands by the mid 20th Century, theWSS is currently a globally significant source of sediment to the world’s oceans. Because of these factors, theWSS was selected as one of two global study sites for the international, NSF supported, MARGINS Source-to-Sink initiative designed to investigate the transfer of sediment from terrestrial source to marine sink. Previous studies on theWSS have shown a strong link between climate change and geomorphic response in the system. River incision since the last glacial coldest period has generated a significant amount of topography, leaving small remnants of the ca.18,000 cal. yr BP last glacial aggradation terrace scattered up to 120 m above modern rivers. In this study, the hillslope response to river incision is quantitatively examined using new high resolution topographic data sets (lidar and photogrammetry) in combination with 3 field mapping and tephrochronology. Hillslopes are found to be coupled to river incision and adjusted to rapid incision through the initiation and reactivation of deep-seated landslides. In the erodible marine sedimentary rocks of the terrestrialWSS, post-incision deep-seated landslides can occupy over 30% of the surface area. Many of these slides show evidence of multiple “nested” failures and landslide reactivation. The ages of tephra cover beds identified by electron microprobe analysis show that following an initial 4,000 to 5,000 year time lag after the initiation of river incision, widespread hillslope adjustment started between the deposition of the ca. 13,600 cal. yr BPWaiohau tephra and the ca. 9,500 cal. yr BP Rotoma tephra. Tephrochronology and geomorphic mapping analysis indicates that river incision and deep-seated landslide slope adjustment is synchronous between mainstem rivers and headwater tributaries. Tephrochronology further shows that many slopes have continued to adjust to channel incision into the late Holocene. Hillslope response in the catchment can involve the entire hillslope from river to ridgeline, with some interfluves between incising sub-catchments being dramatically modified through ridgeline retreat and/or lowering. Using the results of the landform tephrochronology and geomorphic mapping, a conceptual time series of hillslope response to uplift and climate change-induced river incision is derived for a timeframe encompassing the last glacial-interglacial cycle. Using the same high resolution topography datasets, in-depth field analysis, and tephrochronology, the 18,000 year sediment yield from terrestrial deep-seated landslides in theWSS is estimated in order to investigate the magnitude of hillslope response to climate-modulated, uplift driven river incision. This completes one of the first processbased millennial time-scale sediment budgets for this class of temperate maritime, active margin catchments. Fluvial and geomorphic modelling is applied to reconstruct pre 18,000 cal. yr BP topography in 141 km2 of detailed study area and the resulting volumetric estimates from 207 landslides are used to estimate deep-seated landslide sediment flux for the broader system. An estimated 10.2 km3 of deep-seated landslidederived sediment with a multiplicative uncertainty of 1.9 km3 (+9.2 km3, -4.8 km3) was delivered to terrestrial and marine sinks. This accounts for between 10 and 74% of the total mass of the terrestrialWSS budget of ca. 91,000 Mt (+37,000 Mt, -26,000 Mt). Combining the deep-seated landslide results with other studies of terrestrial sediment sources and terrestrial and shelf sinks, the estimated terrestrial source load ranges from 4 Abstract 1.2 to 3.7 times larger than the mass of sediment sequestered in terrestrial and shelf depocentres. This implies that off-shelf transport of sediment is important in this system over the last 18,000 cal. yr BP, as it is today for anthropogenic reasons. Based on the derived sediment budget, the denudation rate for the terrestrialWSS of 0.8 mm yr-1 (+0.3 mm yr-1, -0.2 mm yr-1) is indistinguishable from the average terrestrialWaipaoa late Quaternary uplift rate, indicating an approximate steady-state balance between denudation and uplift. This thesis provides a quantitative analysis of the role of deepseated landslides in an active margin catchment that is used to improve the understanding of landscape and terrestrial source-to-marine-sink sediment transfer dynamics.

The natural instability of hydrothermal vents creates variable environmental conditions among habitat patches. Habitat differences correspond to phenotypic variation in Ridgeia piscesae, the only ‘vent tubeworm’ on the spreading ridges of the Northeast Pacific. Ridgeia piscesae that occupy high fluid flux habitats have rapid growth rates and high reproductive output compared to tubeworms in habitats with low rates of venting fluid delivery. As recruitment occurs in all settings, worms in the “optimal habitat” may act as source populations for all habitat types. Ridgeia piscesae is a foundation species in the Endeavour Hydrothermal Vents Marine Protected Area of the Juan de Fuca Ridge. The objective of this thesis was to assess fine scale population structure in Ridgeia piscesae within the Endeavour vent system using genetic data. Population structure was assessed by analysis of the mitochondrial COI gene in 498 individuals collected from three vent sites of the Juan de Fuca Ridge; Middle Valley (n=26), Endeavour Segment (n=444) and Axial Volcano (n=28). Genotyping using microsatellite markers was attempted but all loci developed for closely related tubeworm species failed to amplify microsatellites in Ridgeia piscesae. Sequence analysis identified 32 mitochondrial COI haplotypes; one dominant haplotype (68%), three common haplotypes (4%-7%) and the remainder were rare (<2%). Axial Volcano was differentiated from Middle Valley and Endeavour. Within Endeavour, genetic sub-structuring of Ridgeia piscesae occurred among vent fields (Clam Bed, Main Endeavour and Mothra) and habitat types < 10 km apart. Patterns of genetic variation and coalescent based models suggested that gene flow among vent fields moved in a north to south direction in individuals from high flux habitat but from south to north in individuals from low flux habitat. Tubeworms from low flux habitat had more nucleotide polymorphisms and haplotypes than those from high flux habitats. Estimates of the number of immigrants per generation moving from high flux to low flux subpopulations was four times higher than in the reverse direction. The effective population size was estimated to be three times greater in high flux habitat when the generation times for individuals from each habitat type were considered. Demographic tests for population equilibrium identified a recent and rapidly expanding metapopulation at Endeavour. Models of gene flow in Ridgeia piscesae reflected the general oceanographic circulation described at Endeavour. Genetic data illustrate that dispersing larvae exploit the bi-directional currents created through plume driven circulation within the Endeavour axial valley and suggest that adult position on or near chimneys may influence larval dispersal trajectories upon release. Building on known ecological and biological features, this study also showed that Ridgeia piscesae from limited and ephemeral high flux habitat act as sources to the overall metapopulation and that asymmetrical migration and habitat stability sustain high genetic diversity in low flux sinks. The overall metapopulation at Endeavour experiences frequent extinction and recolonization events, differences in individual reproductive success, and source-sink dynamics that decrease the overall effective size and genetic diversity within the population. These factors have important implications for the conservation of a foundation species. / Graduate / 0307 / 0329 / 0369 / lcpuetz@uvic.ca