Thermoelectric (TE) module integration into a notebook computer is experimentally investigated in this thesis for its energy harvesting opportunities. A detailed Finite Element (FE) model was constructed first for thermal simulations. The model outputs were then correlated with the thermal validation results of the selected system. In parallel, a commercial TE micro-module was experimentally characterized to quantify maximum power generation opportunity from the combined system and component data set. Next, suitable &ldquo / warm spots&rdquo / were identified within the mobile computer to extract TE power with minimum or no notable impact to system performance, as measured by thermal changes in the system, in order to avoid unacceptable performance degradation. The prediction was validated by integrating a TE micro-module to the mobile system under test. Measured TE power generation power density in the carefully selected vicinity of the heat pipe was around 1.26 mW/cm3 with high CPU load. The generated power scales down with lower CPU activity and scales up in proportion to the utilized opportunistic space within the system. The technical feasibility of TE energy harvesting in mobile computers was hence experimentally shown for the first time in this thesis.

The energy-water nexus represents a complex system of correlated resources, with particular relevance to thermoelectric power plants. Since thermoelectric power plants typically depend on water for cooling, these facilities are prone to water-related challenges. At the same time, large water withdrawals for power plants can adversely impact other water users in a watershed. This work aims to evaluate water impacts on Texas power plant operations and the associated effects these power plants have on water availability. An evaluation of the water impacts on power generation in Texas was completed through four analyses: 1) water availability effects of changing cooling technologies, 2) economic value of drought resiliency through use of alternative cooling technologies, 3) dynamic impacts of reservoir storage on power generation operations, and 4) potential for reclaimed water as a cooling source. Based on the results of these analyses, the following general conclusions were drawn [bulleted list]: [bullet] Use of alternative cooling technologies decreases water withdrawals at the expense of additional energy and water consumption. However, the reduced withdrawals for power plants leaves more water in the stream for other water users, including instream flows. [bullet] Alternative cooling technologies incur additional capital costs, but gain value from reduced water withdrawals. The lower withdrawal requirements make such facilities more resilient to drought, which can have economic value from additional generation during possible drought-related curtailment or suspension. [bullet] Changing surface water reservoir storage at power plants has dynamic impacts on power generation operations, as well as other users in a river basin. Generally, decreasing power plant reservoir storage benefits other users in the basin. Instances arise where both beneficial and detrimental impacts are also observed. [bullet] Reclaimed water can be a technologically and economically feasible cooling source for many existing power plants. The future suitability of using reclaimed water for power plant cooling depends on water pipeline construction costs, reclaimed water flow, and water stress [end of bulleted list]. These general conclusions, along with further details, provide insight into the relationship between water resources and thermoelectric power plants. As resources become increasingly strained, understanding and responding to tradeoffs within the energy-water nexus, through such analyses, might become imperative for sustainable resource management. / text

Titanium dioxide, TiO2, has potential applications as a photoelectrode for photoelectrochemical generation of hydrogen by splitting water using solar energy and as a photocatalyst for water purification. This study is part of the UNSW research program to process TiO2-based oxide semiconductors as high-performance photoelectrodes and photocatalysts. This study investigates the effect of defect disorder on semiconducting properties of polycrystalline TiO2. This study involved the processing of high-purity polycrystalline TiO2 and determination of its semiconducting properties through measurement of electrical conductivity and thermoelectric power at elevated temperatures (1073-1323K) in controlled oxygen activities [1x10-13 Pa < p(O2) < 75 kPa]. The study included two types of experiments: Determination of electrical properties under conditions of gas/solid equilibrium. The data obtained was used to derive defect disorder and related semiconducting properties Monitoring of electrical properties during equilibration. This data was used to determine the chemical diffusion coefficient. The data obtained under equilibrium conditions indicates that oxygen may be used as a dopant to impose controlled semiconducting properties. In reduced conditions TiO2 is an n-type semiconductor and under oxidizing conditions TiO2 is a p-type semiconductor. The n-type behaviour is associated with oxygen vacancies as the predominant defects and titanium interstitials as the minority defects. The p-type behaviour is closely related to titanium vacancies that are formed during prolonged oxidation. Charge transport at elevated temperature was shown to involve substantial contribution from ions. Analysis of electrical properties enabled determination of several defect-related quantities including the activation enthalpy for oxygen vacancy formation, and the activation energy of the electrical conductivity components related to electrons, holes and ions. The kinetic data obtained during gas/solid equilibration enabled determination of the chemical diffusion coefficient which exhibited a complex dependence on nonstoichiometry. In addition, prolonged oxidation showed that equilibration occurred in two kinetic regimes. One for highly mobile oxygen vacancies and titanium interstitials which quickly reached an ??operational equilibrium?? within hours and another slow kinetic regime for equilibration of titanium vacancies over many thousand hours. The determined chemical diffusion coefficient data may be used to select the processing conditions required to impose uniform concentration of defects within a TiO2.

Superfícies de silício (100) foram inicialmente pré-ativadas em uma solução diluída de ácido fluorídrico contendo PdCl2. Após essa etapa, filmes finos de Cu-Ni-P foram quimicamente depositados utilizando-se um banho químico contendo 15g/l NiSO4.6H2O; 0.2 g/l CuSO4.5H2O; 15 g/l Na2HPO2.H2O e 60 g/l Na3C6H5O7.2H2O na temperatura de 80ºC onde foi adicionado NH4OH até que o pH da solução atingisse 8,0. Foi observado que as porcentagens estequiométricas de Ni e Cu variaram substancialmente no intervalo de 1 a 3min, e se tornaram praticamente estáveis em 50% e 35%, respectivamente, quando o tempo de deposição foi superior a 3min. Além disso, a porcentagem de P permaneceu quase constante em torno de 17-18% para todos os tempos de deposição. A distribuição de alturas nas imagens FE-SEM resultou bimodal para tempos na faixa de 1 e 3min onde a predominância do modo de maior altura aumentou substancialmente para o tempo de 3min. Tal fato serviu para corroborar a evolução da morfologia superficial de grãos menores com diâmetros na faixa de 0,02 a 0,1µm, predominantemente compostos de Ni, para grãos maiores, na faixa de 0,1 a 0,3µm e predominantemente compostos de Cu. Após um recozimento a 100oC durante 10min em ambiente 20%O2+80%N2, observou-se uma mudança na morfologia superficial em que os aglomerados de fósforo (Po) desapareceram enquanto que os grãos que compunham a imagem não mudaram substancialmente de tamanho após o recozimento. Apesar do desaparecimento dos aglomerados, a concentração de fósforo ainda apresentou valor semelhante ao valor de antes do recozimento (~17-18%). As análises de difração de raios X (XRD) indicaram o aparecimento de um pico de difração alargado ao redor de 22,6º característico de óxido de fósforo (P2O5) com estrutura vítrea amorfa significando que o fósforo em estado puro foi transformado na sua forma oxidada. Por outro lado, picos substancialmente menos intensos de NiO, Ni3P e Si5P6O25 foram observados. Verificou-se também para os filmes recozidos em N2+O2 que a resistividade aumentou para todos os tempos de deposição e o poder termoelétrico medido resultou quase independente do tempo de deposição e, portanto, foi quase independente da espessura do filme para as diferentes temperaturas medidas na faixa de 40 a 120ºC. / Silicon surfaces (100) were initially pre-activated in a diluted hydrofluoric acid solution containing PdCl2. After this step, Cu-Ni-P thin films were chemically deposited using a chemical bath containing 15g/l NiSO4.6H2O; 0.2 g/l CuSO4.5H2O; 15 g/l Na2HPO2.H2O e 60 g/l Na3C6H5O7.2H2O at the temperature of 80°C where NH4OH was added until the pH of the solution reached 8.0. It was observed that the stoichiometric percentages of Ni and Cu varied substantially for deposition time in the range of 1 to 3min, and became practically invariant at 50% and 35%, respectively, when the deposition time was greater than 3min. In addition, the percentage of P remained almost constant at around 17-18% for all the deposition times. The distribution of heights in the FE-SEM images resulted bimodal for times in the range of 1 and 3min where the predominance of the higher average height mode increased substantially for the time of 3min. This fact allowed one to corroborate the superficial morphology passing from smaller grains with diameters in the range of 0.02 to 0.1µm, predominantly composed of Ni to larger grains in the range of 0.1 to 0.3µm with Cu predominant composition. After an annealing at 100°C for 10min in a 20%O2+80%N2 environment, the phosphorus (Po) agglomerates disappeared while the size of the grains did not change substantially after the annealing. Despite the disappearance of the agglomerates, the phosphorus concentration still remained unchanged (~ 17-18%). X-ray diffraction (XRD) analysis showed a broad diffraction peak around 22.6º, which is characteristic of an amorphous vitreous structure (P2O5). In addition, substantially less intense peaks showing small amounts of NiO, Ni3P and Si5P6O25 were observed. It was also verified for the N2+O2 annealed films that the resistivity increased for practically all the deposition times and the measured thermoelectric power was almost independent of the deposition time and, therefore, was also independent of the film thickness for the various temperatures in the range from 40 to 120ºC.

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It is generally believed that one of the key parameterscontrolling the normal state and superconducting properties ofhigh temperature superconductors is the charge carrierconcentrationpin the CuO2planes.By changing the non-isovalent dopingconcentration on the RE site as well as the oxygen content in(RE)Ba2Cu3O7−δ, an excellent tool is obtained tovary the hole concentration over a wide range from theunderdoped up to the overdoped regime.In the present thesis thefocus is on the doping effects on the structural and normalstate electrical properties in Nd-123 doped with Ca, La, Pr,Ca-Pr, and Ca-Th.T he effects of doping have been investigatedby X-ray and neutron powder diffraction, and by measurements ofthe resistivity, thermoelectric powerS, and Hall coefficient RH.T he thermoelectric power is a powerful tool forstudies of high temperature superconductivity and is highlysensitive to details of the electronic band structure.Sas a function of temperature has been analyzed in twodifferent two band models.The parameters of these models arerelated to charactristic features of the electron bands and asemiempirical physical description of the doping dependence ofSis obtained.So me important results are following: (i)The valence of Pr in the RE-123 family.Results from thestructural investigations, the critical temperature Tc, and thethermoelectric power indicated a valence +4 at low dopingconcentration, which is in agreement with results of chargeneutral doping in the RE-123 family.(ii)Hole localization. The results of bond valence sum (BVS)calculations from neutron diffraction data showed that holelocalization on the Pr+4site was the main reason for the decrease of thehole concentration p.Differ ent types of localization wereinferred by S measurements for Ca-Th and Ca-Pr dopings.(iii)Competition between added charge and disorder. Theresults of RH measurements indicated that Ca doping introduceddisorder in the CuO2planes in addition to added charge.This could bethe main reason for the observed small decrease of thebandwidth of the density of states in the description of aphenomenological narrow band model.(iv) Empirical parabolic relation between γ and p.S data were analyzed and well described by a two-band modelwith an additional linear T term, γT.An empiricalparabolic relation for γ as a function of holeconcentration has been found. <b>Key words:</b>high temperature superconductors, criticaltemperature, resistivity, thermoelectric power, Hallcoefficient, X-ray diffraction, Neutron diffraction, NdBa2Cu3O7−δ, hole concentration,substitution.

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<p>It is generally believed that one of the key parameterscontrolling the normal state and superconducting properties ofhigh temperature superconductors is the charge carrierconcentration<i>p</i>in the CuO₂planes.By changing the non-isovalent dopingconcentration on the RE site as well as the oxygen content in(RE)Ba₂Cu₃O_7−δ, an excellent tool is obtained tovary the hole concentration over a wide range from theunderdoped up to the overdoped regime.In the present thesis thefocus is on the doping effects on the structural and normalstate electrical properties in Nd-123 doped with Ca, La, Pr,Ca-Pr, and Ca-Th.T he effects of doping have been investigatedby X-ray and neutron powder diffraction, and by measurements ofthe resistivity, thermoelectric power<i>S</i>, and Hall coefficient R_H.T he thermoelectric power is a powerful tool forstudies of high temperature superconductivity and is highlysensitive to details of the electronic band structure.<i>S</i>as a function of temperature has been analyzed in twodifferent two band models.The parameters of these models arerelated to charactristic features of the electron bands and asemiempirical physical description of the doping dependence of<i>S</i>is obtained.So me important results are following:</p><p>(i)<i>The valence of Pr in the RE-123 family.</i>Results from thestructural investigations, the critical temperature Tc, and thethermoelectric power indicated a valence +4 at low dopingconcentration, which is in agreement with results of chargeneutral doping in the RE-123 family.(ii)<i>Hole localization</i>. The results of bond valence sum (BVS)calculations from neutron diffraction data showed that holelocalization on the Pr⁺⁴site was the main reason for the decrease of thehole concentration p.Differ ent types of localization wereinferred by S measurements for Ca-Th and Ca-Pr dopings.(iii)<i>Competition between added charge and disorder</i>. Theresults of RH measurements indicated that Ca doping introduceddisorder in the CuO₂planes in addition to added charge.This could bethe main reason for the observed small decrease of thebandwidth of the density of states in the description of aphenomenological narrow band model.(iv) Empirical parabolic relation between γ and p.S data were analyzed and well described by a two-band modelwith an additional linear T term, γT.An empiricalparabolic relation for γ as a function of holeconcentration has been found.</p><p><b>Key words:</b>high temperature superconductors, criticaltemperature, resistivity, thermoelectric power, Hallcoefficient, X-ray diffraction, Neutron diffraction, NdBa₂Cu₃O_7−δ, hole concentration,substitution.</p>