Thesis (M. S.)--Electrical and Computer Engineering, Georgia Institute of Technology, 2009. / Committee Chair: Cressler, John; Committee Member: Citrin, David; Committee Member: Shen, Shyh-Chiang. Part of the SMARTech Electronic Thesis and Dissertation Collection.

Thesis (Ph. D.)--University of Missouri-Columbia, 1998. / Typescript. Vita. Includes bibliographical references (leaves 240-248). Also available on the Internet.

Thesis (Ph. D.)--University of Missouri-Columbia, 1998. / Typescript. Vita. Includes bibliographical references (leaves 240-248). Also available on the Internet.

Thesis (M.Sc.(Electrical Engineering))--University of Pretoria, 2003. / Summaries in Afrikaans and English. Includes bibliographical references.

Thesis (Ph. D.)--University of Missouri-Columbia, 2000. / Typescript. Vita. Includes bibliographical references (leaves 80-84). Also available on the Internet.

xii, 106 p. : ill. (some col.) / Quantum dots are systems in which all three spatial sizes are comparable to the Fermi wavelength. The strong confinement leads to a discrete energy spectrum. A goal of thermoelectric research is to find a system with a high thermoelectric figure of merit, which is related to the efficiency of solid-state heat engines. The delta-like density of states of quantum dots has been predicted to boost this figure of merit. This dissertation addresses some thermoelectric properties relevant to the thermal-to-electric energy conversion using InAs/InP quantum dots embedded in nanowires. In thermoelectric experiments, a temperature difference must be established and its value needs to be determined. A novel technique for measuring electron temperature across the dot is presented. A strong nonlinearity of the thermocurrent as a function of temperature difference is observed at a small ratio of temperature gradient and cryostat temperature. At large heating currents, a sign reversal is observed. Numerical calculations explore the contribution of the energy dependence of the transmission function to this effect. Depending on the relative contributions from sequential tunneling and co-tunneling, thermovoltages of quantum dots generally have one of two different lineshapes: a sawtooth shape or a shape similar to the derivative of the conductance peak. Here a simple picture is presented that shows that thermovoltage lineshape is accurately predicted from the energy level spacing inside the dot and the width of the transmission function. An important figure of merit of all heat engines is the efficiency at maximum power. Here the thermoelectric efficiency at maximum power of quantum dots is numerically compared to that of two other low-dimensional systems: an ideal one-dimensional conductor (1D) and a thermionic power generator (TI). The numerical calculations show that either 1D or TI systems can produce the highest maximum power depending on the operating temperature, the effective mass of the electron, and the effective area of the TI system. In spite of this, 1D systems yield the highest efficiency at maximum power. / Committee in charge: Dr. Richard Taylor, Chair; Dr. Heiner Linke, Research Advisor; Dr. Dietrich Belitz; Dr. David Johnson; Dr. David Strom

Made available in DSpace on 2014-10-09T12:36:38Z (GMT). No. of bitstreams: 0 / Made available in DSpace on 2014-10-09T13:59:10Z (GMT). No. of bitstreams: 1 01821.pdf: 4038166 bytes, checksum: ede612636a13b46e2d052cfc50e01907 (MD5) / Tese (Doutoramento) / IPEN/T / Instituto de Fisica, Universidade de Sao Paulo - IF/USP

Thesis (MTech (Mechanical Engineering))--Cape Peninsula University of Technology, 2017. / Food and water fuel and sustain life on earth. Since ancient times, their sourcing and preservation have been very important issues to humanity. In modern times, experimentation is a major step in analysing how cold storage problems in the medical and food science technology fields can be addressed. For investigating spoilage of new products and/or growth of pathogens in such cases, it is necessary to do experiments at different low temperatures for prolonged periods and check the effects. While this can be undertaken in a conventional two chambers fridge, it takes a long time to investigate a whole range of feasible storage temperatures. This dissertation describes work intended to treble the samples in such investigations and, therefore, significantly reduce the times. Six well- insulated chambers were constructed from plastic and wood and set at different temperatures. An ordinary deep freezer was used as the main heat sink for the chambers. Experiments were done with different methods to get the best result for the cold air flow into the chambers over period of eight months. The chambers temperatures were set between 0 and 15°C. It was finally established that a properly-designed six-chamber system could successfully be added to an ordinary freezer to provide different medium-to-high refrigeration temperatures without the use of a multi-pressure refrigeration cycle.

Made available in DSpace on 2014-10-09T12:36:38Z (GMT). No. of bitstreams: 0 / Made available in DSpace on 2014-10-09T13:59:10Z (GMT). No. of bitstreams: 1 01821.pdf: 4038166 bytes, checksum: ede612636a13b46e2d052cfc50e01907 (MD5) / Tese (Doutoramento) / IPEN/T / Instituto de Fisica, Universidade de Sao Paulo - IF/USP

The Andean Cordilleran orogenic system stretches over 7,000 km along the western margin of South America and serves as a useful laboratory to evaluate the causes of spatial and temporal variations in orogenic processes. Although the geology of the Andean margin is fundamentally controlled by the subduction of the Nazca plate beneath the South American plate, the style of deformation, basin morphology, exhumation history, and volcanic activity along this margin are remarkably heterogeneous in both time and space. My Ph.D. work presents new data from the Miocene – Pliocene along-strike depocenters bounding the basement block uplifts of the Sierras Pampeanas and the fold and thrust belt of the Andean Precordilleran in the south Central Andes between ca. 27.5°S and 30.5°S. I use new observations from sedimentology, detrital zircon U-Pb data, and low-temperature thermochronology to evaluate the mechanisms driving basin organization, sedimentation, and exhumation. Geohistory analysis supports flexurally controlled basins between ca. 18 and 6 Ma with detritus derived exclusively from the active Precodillera to the west. Accelerated deformation in the Precordillera produced accelerated sedimentation from ca. 10 – 8.5 Ma. A deceleration of sedimentation from ca. 6 – 5 Ma was most likely controlled by heightened aridity. Around the same time, low-temperature thermochronometers record the widespread exhumation of the foreland basin system for over 300 km along strike, this may be driven by dynamically controlled uplift related to Miocene flat-slab subduction. Low-temperature thermochronometers suggest that the geothermal gradient throughout the late Miocene was ca. 35°C/km – 25°C/km and had not been significantly depressed as previously proposed. Granite-cored ranges in the Sierras Pampeanas were sampled for low-temperature thermochronology to constrain the exhumation history of the region. Modeling of both apatite fission track and apatite (U-Th-Sm)/He thermochronometers demonstrates that these rocks have been close to the surface since the late Paleozoic. Reheating during the Cretaceous is attributed to elevated geothermal gradients due to back-arc rifting. Final exhumation (1- 2 km) occurred in the mid to late Miocene and may have been controlled by the onset of flat-slab subduction. These results suggest that the Sierras Pampeanas may have had inherited positive topography that has controlled basin organization and sediment distribution patterns since the Paleozoic.