The research thesis is based on the study of Kaohsiung MRT Orange Line. On condition that bilateral power is supplied during the target year, make two-minute interval as the background simulation, and use MATLAB & Simulink software for analysis tools. Through the establishment of the equivalent in the stray current model, discuss the original ground construction of Kaohsiung MRT Orange Line, and change the resistance of the track structure, in order to analyze whether that affects stray currents. Besides, simulate the maximum stray current density and its length in each station. To study cathode corrosion of underground metal pipeline due to stray current, the equivalent circuit model is applied for computer simulation. By changing the distance between the underground metal pipelines and MRT rail tracks the voltage potential of the pipe lines introduced by the stray current of MRT system is derived. The mitigation strategy of cathode corrosion due to stray current is also proposed in the thesis.

Platinum (Pt) alloy nanoparticles are used as catalysts in electrochemical cells to reduce oxygen to water and to oxidize hydrogen; the overall reaction converts chemical energy into electrical energy. These nanocatalysts are deposited on a carbon substrate and their catalytic function takes place in acid medium. This harsh environment causes an undesired reaction, which is the dissolution of the metal atoms into the acid medium; thus affecting the catalyst life. This dissertation aims to investigate the dissolution mechanism of fuel cell cathode catalysts at the atomic level starting from the oxygen reaction intermediates on the cathode catalyst surface and propose guidelines to improve cathode catalysts durability based on our proposed mechanism. Density functional theory is employed to study various possible scenarios with the goals of understanding the mechanism of the metal atom dissolution process and establishing some guidelines that permit a rational design of catalysts with better stability against dissolution. A thermodynamic analysis of potential metal dissolution reactions in acid medium is presented first, using density functional theory calculations to explore the relative stabilities of transition metals in relation to that of Pt. The study is performed by comparing the change in reaction Gibbs free energies for different metals in a given dissolution reaction. Then, a series of density functional theory studies, tending to investigate the adsorbed atomic oxygen absorption process from cathode catalyst surface into its subsurface, includes: 1) the oxygen adsorption on various catalyst surfaces and oxygen absorption in subsurface sites to figure out the minimum energy pathway and energy barrier of on-surface oxygen migration and absorption into subsurface; 2) the oxygen coverage, the other oxygen reduction reaction intermediates, and water effects on the oxygen absorption process according to reaction pathways, energy barriers, and thermodynamic analysis; 3) the oxygen absorption process on several Pt-based alloys with various compositions and components to find out the best alloy to inhibit atomic oxygen absorption including both kinetic and thermodynamic analyses, and the effects of such alloyed species on the inhibition process.

In this research, we studied the effect of different structures of organic precursors on the performance of LiFePO4/C composite by co-precipitation route. The composite material¡¦s electrochemical and physical properties were characterized by CV, XRD, SEM, PSA, BET-surface area, TGA, and Raman spectroscopy.

For the last two decades, solid oxide fuel cells (SOFCs) have been operated in high temperatures > 1000¢XC. Recently, more efforts have been concentrated on the intermediate temperature SOFCs in which Ba0.5Sr0.5Ce0.8Fe0.2O3-£_ (BSCF) is a very promising cathode material capable of working in this intermediate temperature range of 500~700¢XC. In this work, both glycine and citric acid methods were employed to prepare BSCF powders. Preparation parameters such as concentration of organic components and calcination temperature were varied to obtain powders of different morphologies and particle sizes. Slurries containing the prepared powders were then used to print BSCF cathode films on electrolyte disks. The impedances of the resultant cathodes were measured and analyzed to evaluate the effects of powder preparation parameters and film microstructures. The results show that the BSCF cathode derived from the powder prepared by the modified citric acid method and then sintered at 900¢XC has the best electrochemical performance. With high porosity and well dispersed pores, this cathode has interfacial area specific resistance (ASR) values as low as 0.78 £[cm2 at 500¢XC, 0.10 £[cm2 at 600¢XC and 0.018 £[cm2 at 700¢XC, which are significantly lower than that obtained from the unmodified citric acid or glycine method.

A glow discharge using a solution as the cathode was investigated to add to the understanding of the operating mechanism and characteristics of such systems. The intensities and vertical distributions of emission from several analytes and background species were observed and compared with the vertical distribution of Fe excitation and OH rotational temperatures, as well as to electrical characteristics. The effects of the discharge gap size, the pH and conductivity of the solution, the applied current and the solution flow rate on these distributions were also studied. Detection limits for this system were found to be comparable to those of similar systems and mostly in range of tens of parts per billion.

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No description available.

Diss. (D. Ing.)--Technische Hochschule zu Berlin. / Lebenslauf. "Literaturzusammenstellung": p. 62-64.

Thèse - Paris. / "1re thèse." "2e thèse - Propositions données par la Faculté." p.[64].

Thesis (M.S.)--Virginia Polytechnic Institute and State University, 1991. / Vita. Abstract. Includes bibliographical references (leaves 71-75). Also available via the Internet.