The efficiency of the fuel cell depends on both the kinetics of the electrochemical process and performance of the components. The main aim of this research is to analysis the reliability of the cracked Ag-SU8 interface on the channel wall in a micro-PEMFC. An existed surface crack on the channel wall subjected to the flow induced compressive stresses and shear stresses will propagate and lead to the spall formation. The results show that as the crack length increases, the value of KI will increase, but the value of KII decreases slightly. The reliability analysis of the interfacial crack between Ag and SU8 on the Micro-channel wall in PEMFC is discussed in this thesis.

ABSTRACT Taitung area was commonly seen as a particularly clean environment. But the air quality has diminished lately similar to that seen in some parts of the populated western area in Taiwan, with ozone (O3) concentration levels rising every year. Because ozone is a byproduct of photochemistry, its accumulation is not only related to the discharge of local pollutants such as nitrogen oxide compounds (NOx), volatile organic compounds (VOC) and the introduction of external pollutants, but also related to the meteorological conditions. This research began with comparing the long-term trends of ozone concentration level and related pollutants in the Taitung area with those found in other survey stations spread in Taiwan. Through factor analysis, the relationship between air pollutants and meteorological parameters are analyzed. Finally, a screening of the events of abnormal ozone concentrations, followed with detailed analysis of the hourly data during these events and the discussion of the possible reasons for the comparatively poor air quality during these events and their correlations with seasons and meteorological conditions. Analysis of the trends in monthly averaged concentration of ozone shows that the annual rate of change (AR) is increasing at all stations under this study, except the Guanyin station being -0.18%. Taitung station has relatively higher levels every spring (March - May) and fall (October ¡V November); the annual rate of change is higher than other east area in Taiwan and the Hengchun station. These seasonal variation (SV) shows a progressively increasing north to south trend, Hengchun station being the highest and Taitung station being the second highest, indicates that concentrations of ozone are influenced by seasonal changes. By using the method of factor analysis to analyze the relation among ozone concentrations, meteorological parameters and pollution parameters, resulted in a direct relationship to the wind speeds over the four seasons. The results show a negative relationship to the atmospheric pressure during summer. The ozone concentrations of the Taitung station show a direct relationship to the Hualian station, which indicates the north to south dispersion relationship. The Analysis of the abnormal event also shows that typhoons may be an important carrier for transporting external pollutants into the area.

This thesis presents the design and implementation of a single-stage with high power factor asymmetrical half-bridge converter. The main structure combines a boost converter with an asymmetrical half-bridge. An Asymmetrical half-bridge converter has many advantages such as soft-switching properties and fewer components. Therefore it is suitable for DC/DC cell. The boost converter is used in a PFC cell that operating in discontinuous condition mode have innate ability of power factor correction without additional controller. In this thesis, the complete analysis of operation principle and design of controller for the equivalent circuits of a single-stage AC/DC converter in every operating stage have been described in detail. Finally, we construct the single-stage circuit and experimental result show that it can reach the expected goal for power-factor correction.

The thesis aims to the research of active power factor correction (PFC) circuit and develop a DSP-based digital controller. In the thesis, PI controller is the control core for the voltage loop¡Band current loop, and then achieve the function of the power factor correction of boost converter. Finally, we develop a boost converter and connect it to a DSP-based controller to measure the waveforms and verify the power factor correction. Furthermore, the research can be extended to a simulating platform which we can verify the power factor correction by just changing the control law on DSP .

¡@¡@The motivation of this research is to construct a Composite Index of funds which can help investors to choose funds with better ¡§future¡¨ performance. ¡@¡@The Composite Index in this thesis includes 14 kinds of indexes, such as Sharpe, Treynor, Sortino, and etc. Each kind of index is calculated by 4 different time lengths, they are 1 month, 3 months, 6 months, and 1 year. Therefore, there are 56 indexes in the Composite Index (CI). ¡@¡@Factor analysis method was used to analyze fund performance from 1998/01 to 2000/12, and the perfect weight combination to make 56 indexes become one CI was found out. In order to prove the performance of the CI in selecting funds, funds were distributed into 5 groups by their Composite Index scores every month. Therefore, we had group A to E from high CI score to low CI score. We calculated these funds¡¦ returns in the next month, and cumulated them by group from 2001/01 to 2005/12. After calculating, the cumulative returns of group A are 74.47% higher than group E, annual returns are 11.99%, and Sharpe index is 1.41. It shows that Composite Index can really distinguish the future, at least in one month, performance of stock funds. Investors are recommended to change their fund portfolios by latest CI scores once a month. Therefore, the Composite Index is more suitable for fund-of-fund manager, because their transaction costs are lower. ¡@¡@This thesis was awarded by ¡§Industry-University Cooperative Research Project¡¨ of National Science Council, and is going to be developed in PRISS system, a financial analysis software of Folion Financial Technology Co., Ltd. Therefore, a more systemized, programmed, and efficient environment for this kind of research is expectable.

The concentrations of atmospheric carbonyls were studied by the LpDNPH-Cartridge and the microcomputer air sampling device at Nanzi and Siaogang sites in Kaohsiung city. Source apportionment was determined by the factor analysis. The results showed that the highest concentrations of carbonyls was acetaldehyde (27.83 £gg/m3) at Nanzi, followed by formaldehyde (5.03 £gg/m3). At Siaogang, the highest concentrations of carbonyls was acetaldehyde (28.91 £gg/m3), followed by formaldehyde (6.92 £gg/m3). The concentrations of total carbonyls was higher at Siaogang (57.86 £gg/m3) than those at Nanzi (49.74 £gg/m3) . The concentrations of total carbonyls at Nanzi were 65.42 £gg/m3 in summer and 25.06 £gg/m3 in winter, and were 85.09 £gg/m3 in summer and 37.12 £gg/m3 in winter at Siaogang, due to the fact that summer has stronger photochemical activities than in winter. Additionally, peak rush hours of the traffics, either in the morning or at night, would result in increased concentration of Carbonyls was higher. The concentrations of atmospheric carbonyls were studied by the LpDNPH-Cartridge and the microcomputer air sampling device at Nanzi and Siaogang sites in Kaohsiung city. Source apportionment was determined by the factor analysis. The results showed that the highest concentrations of carbonyls was acetaldehyde (27.83 £gg/m3) at Nanzi, followed by formaldehyde (5.03 £gg/m3). At Siaogang, the highest concentrations of carbonyls was acetaldehyde (28.91 £gg/m3), followed by formaldehyde (6.92 £gg/m3). The concentrations of total carbonyls was higher at Siaogang (57.86 £gg/m3) than those at Nanzi (49.74 £gg/m3) . The concentrations of total carbonyls at Nanzi were 65.42 £gg/m3 in summer and 25.06 £gg/m3 in winter, and were 85.09 £gg/m3 in summer and 37.12 £gg/m3 in winter at Siaogang, due to the fact that summer has stronger photochemical activities than in winter. Additionally, peak rush hours of the traffics, either in the morning or at night, would result in increased concentration of Carbonyls was higher. Source apportionment analysis using factor analysis shows that the principle sources at Nanzi were traffic exhausts (motor, diesel, and gasoline vehicle) and stationary sources (industry, restaurant and chemical processes). The main sources at Siaogang were traffic exhausts (motor and gasoline vehicle), stationary sources (industry and restaurant) and secondary photo-chemical reactions.

The long-term trends of PM10, O3 and NOx concentrations were analyzed using Holland model (without meteorological-adjusted) and MM-Regression model (with meteorological-adjusted) based on the data of ten EPA air quality stations from 1997 to 2006 in Kao-Ping area. The aim of this study was to determine the impact of meteorological factors on the trends of these pollutants in Kao-Ping. The annual variations (AV) of O3 was −0.496 % in Kaohsiung county, −0.200 in Pingtung county, and 0.277 % in Kaohsiung city, showing different characteristics in Kao-Pin area. On average, the annual variations (AV) influenced by meteorological factors were: PM10: 0.205 %, O3: −0.127 %, and NOx: 0.338 %. After being adjusted by meteorological factors, the seasonal variations (SV) were about 1, indicating little seasonal change. In Kao-Ping region, the influence by meteorological factors was 9.566 %, 8.026 % and 7.351 % in PM10, O3, NOx, respectively. In total, the average influence was 8.314% in Kao-Ping region, with 7.791% in Kaohsiung city (8.481% at Cianjin, the most influenced area), 9.439% in Kaohsiung County (10.368% at Linyuan, the most influenced area), and 7.110% in Pingtung County (7.516% at Chaojhou, the most influenced area). PM10 was influenced most by meteorological factors (PM10: 9.566 %, O3: 8.026 %, NOx: 7.351 %) in Kao-Ping area.. In Kao-Ping region, the contributions by individual meteorological factors were 70.78% in wind speed, 38.23% in total cloudiness, 36.56% in sunshine hour, 19.86% in temperature, 12.40% in atmospheric pressure, 5.96% in relative humidity and 1.27% in wind direction. The influences by the wind speed were 66.62 %, 72.35 % and 72.31 % on the concentrations of PM10, O3, NOx, respectively. Wind speed was the most important factor controlling concentration trends in Kao-Ping area.

The work presented in this dissertation can be grouped around three major themes. The first theme relates to risk, the second theme relates to asset pricing, whereas the third theme relates to serial correlation of asset returns. The three chapters of this dissertation investigate these themes Chapter Two analyses the behavior over time of market risk, aggregate idiosyncratic risk and correlations in portfolio of Taiwan listing stocks and studied pattern of aggregate correlation between the 3 most important Taiwan stock index and Taiwan value-weighted index. We find (1) Idiosyncratic risk is trended upwards; (2) The conditional stock returns correlation process is asymmetric. The implication of our finding is (1) It takes more stocks to achieve a given level of diversification; (2) Diversification strategies perform poorly in bear markets. Chapter Three investigates the role of the asset co-skewness and conditioning information in asset pricing. First, I estimate long-run predictive regressions of asset returns to test whether aggregate idiosyncratic risk is a price factor of industrial returns. Then I use data on Taiwan 19 industry portfolios to fit various assets pricing models. I find (1) the cross-sectional ctional correlation between 2 i £] (the gamma coefficient from the 3M-CAPM equation) and 3 i ϕ (the interaction coefficient from the CCAPM equation) is positive and fairly large. (2) The firm-level volatility is a good proxy for cay as conditioning information variable. (3) The gamma coefficient can pick up the extent of beta co-vary with the market wide excess-return over the business cycle. (4)among 19 industrial returns, the 2 industrial returns can be explained by 3M-CAPM; the 7 industrial returns can be explained by CCAPM; the 5 industrial returns can be explained by 3M-CAPM+CCAPM, Others can¡¦t be explained by either of three models. Chapter Four examines the impact of positive feedback trading behavior of the investors on the short-term dynamics of return for four Taiwan index futures contracts by utilizing the framework of the model developed by Sentana & Wadhwani(1992). Use of the Asymmetric Nonlinear Smooth Transition GARCH Model demonstrates that positive feedback trading of investors is the main determinant of short-term dynamics of return for Taiwan index futures contracts. Moreover, it shows that positive trading is more intense during market declines than it is during market advances due to extensive use of spot-loss trading for investors. Finally it is shown that the sophisticated professional investors intend to take positive feedback trades wave so that they lead to increase positive feedback trading in Taiwan index futures since the government opened the enterprises for managed futures.

The main aim of this study is to develop three dimensional models for micro flow-field plate of PEMFC and use numerical simulations to discuss the reliability of micro flow-field plate which works in real. A crack exists in the plate is loaded by the shear force, which is produced by the fuel H2 enter from inlet, and will propagate. The Ag, which is used to collect the electrons, will peel off and the efficiency of fuel cell will decrease. The commercial package software ANSYS was used to simulate the stress state around crack tip. Three modes of stress intensity factors K£L, K£L£L and K£L£L£L, were calculated in order to describe the stressed behavior of crack. Finally, the inlet pressure, geometry of crack and channel size is changed and Taguchi method with ANOVA is used to find the factors which influence the stressed behavior of crack most. The simulation results show that K£L and K£L£L are influenced most by geometry of crack and K£L£L£L is influenced more by geometry of crack and channel size

Level densities and spin cut-off factors have been investigated within the microscopic approach based on BCS Hamiltonian. In particular the spin cut-off parameters have been calculated at neutron binding energies over a large range of nuclear mass using the BCS theory. The results are compared with their corresponding macroscopic values. It is found that the values of spin cut-off parameter do not increase smoothly with A as expected based on macroscopic theory. Instead, the values of spin cut-off parameter show structures re&deg / ecting the angular momentum of the shell model orbitals near the Fermi energy. The spin cut-off parameter has also been computed from the knowl- edge of nuclear level density, at neutron binding energy, Bn and the average s-wave neutron spacing. The values of spin cut-off parameter are compared with their corresponding values from the model calculations. The in&deg / uence of the isospin in nuclear level density in particular the isospin cut-off parameter has also been investigated and are compared with their corre- sponding spin cut-off parameters.