Dendritic cells (DCs) modified by some immunomodulatory genes can stimulate a strong antitumor immunity and improve the treatment of tumor cells on the condition that the sources of tumor-associated antigens (TAAs) are available. IL-6, a pleotropic cytokine, has been found to inhibit CD4+25+ regulatory T (Treg)-cell-mediated immune suppression and decrease activation-induced cell death (AICD) without interfering the process of T-cell activation. To enhance DC-based cancer vaccine, we engineered DCs to express transgene IL-6.<p> We constructed a fiber-modified recombinant adenovirus vector AdVIL-6 expressing IL-6, infected DCs with AdVIL-6, and then investigated the efficacy of antitumor immunity induced by vaccination with DCs engineered to express IL-6 transgene. We demonstrated that DCs infected with the recombinant adenovirus AdVIL-6 induced DC maturation by up-regulation of the expression of MHC class U (Iab), CD40, CD54 and CD80 expression. We also demonstrated that vaccination of OVA-pulsed AdVIL-6-infected DCs (DCOVA/AdVIL-6) was able to stimulate a stronger OVA-specific effector CD8+ cytotoxic T lymphocyte (CTL) response than vaccination with the control virus AdVpLpA-infected DCs (DCOVA/AdVpLpA). More importantly, vaccination of mice with DCOVA/AdVpLpA could protect 100% mice from intravenous (i.v.) challenge of a low dose (0.5~105 cells per mouse, 8/8 mice protected) of OVA-expressing BL6-10OVA tumor cells, but only 63% mice from i.v. challenge of a high dose (1~105 cells per mouse, 5/8 mice protected) of BL6-10OVA tumor cells. However, vaccination of DCOVA/AdVIL-6 induced an augmented antitumor immunity in vivo by complete protection of mice (8/8) from challenge of both low and high doses of BL6-10OVA tumor cells.<p> To study the immune mechanism underlying the result of IL-6 engineered-DC vaccine, we generated the DCOVA/AdVIL-6-activated OTI CD8+ T cells and DCOVA/AdVpLpA-activated OTI CD8+ T cells. We demonstrated that DCOVA/AdVIL-6-activated CD8+ T cells displayed a higher level of CD62L, FasL and perforin than DCOVA/AdVpLpA-activated CD8+ T cells. DCOVA/AdVIL-6-activated CD8+ T cells had a prolonged T cell survival after they were transferred into C57BL/6 mice. Furthermore, the results of the animal study showed that 100% of mice bearing OVA-expressing EG7 tumors (8mm in diameter, 8 mice per group) were tumor-free after they were i.v. treated with DCOVA/AdVIL-6-activated CD8+ T cells (2~106 cells per mouse). However, the control DCOVA/AdVpLpA-activated CD8+ T cells failed in eradication of EG7 tumors in all 8/8 mice.<p> Taken together, Adenovirus-mediated IL-6 transgene engineered DC vaccine stimulates efficient CD8+ T cell responses and antitumor immunity via enhanced T cell cytotoxicity and prolonged T cell survival. DCs engineered to express IL-6 by adenovirus-mediated IL-6 gene transfer may offer a new strategy in production of DC cancer vaccines.

The aim of this thesis is to design a controllable DC-link output voltage for isolated slotless tubular linear generators (STLG), which is capable of directly harnessing wave and solar thermal energies. For supplying stable DC-link voltage to load, a suitable voltage regulation circuit is designed based on the integrate system performance assessment. Electrical and mechanical parameters in this refined STLG design are involved to analyze the operational behaviors through magnetic equivalent circuit analysis at different operating modes. From the theoretical modeling and experimental results, both the AC-side and DC-side properties of generator outputs can then be thoroughly investigated. Finally, based on the performance of controllable rectifier model, a three-phase PWM rectifier has been established, and then the regulated DC-link voltage can be implemented using a DSP-based controller combined with required peripheral circuits.

In this work, we have investigated the effects of temperature and optical illumination on organic thin film transistors (OTFTs) with indium-tin-oxide electrode. Experimental results have shown that the turn-on characteristics of the pentacene OTFT with ITO as source/drain electrodes is dependent on environmental temperatures. In addition, it has been found the pentacene OTFT is one kind of photo-sensitive devices. External stimulations can change the I-V characteristics significantly. For example, our pentacene OTFT show a shift of the onset and threshold voltage with illumination, which recovers slowly in the dark. Therefore, except for the application of switch devices, petacene OTFT exhibits a potential application for image sensors.

This thesis focuses on compact brushless DC fan motor, drive circuit structure of motor is proposed, several functions such as output low current limit circuit and low rotation speed limit are added in order to increase robustness of drive circuit. Besides, speed feedback controller is used to solve several problems such as high frequency full speed exciting noise and high power dissipation which occurs in open loop rotation speed control circuit.With regard to BLDC fan motors generally use Hall sensor to detect rotor position, this research proposes sensorless control technology for the purpose of reducing circuit cost and motor size.

The techniques of optical beam induced current (OBIC) have found wide-spread applications in characterizing many semiconductor and optoelectronic devices. A two-photon confocal microscope is adapted for investigating the dynamics of light emitting devices through the contrast mechanisms of two-photon DC and radio frequency (RF) optical beam induced current (OBIC). For comparison, the 2p-OBIC technique detects the photocurrent signal by exciting the semiconductor sample with a pulsed laser that has a wavelength below the bandgap of the semiconductor. It has high accuracy and spatial resolution. We demonstrate that the bias on the devices (forward and reverse) strongly modifies the DC and RF OBIC signals. Finally we will discuss how to explain this result, and we will provide a program to show the phase distribution of GaP LED.

This thesis focues on the realization of small size brushless DC fan motor driving circuit, adding the protection circuit of commutation to H bridge, in addition, the function of low current limiter, and slow rotation speed limiter are also implemented to the more stable rotation. With regard to the strategy of rotation speed control, we use speed feedback controller to slove noise problem which occurs in high frequency full speed excited and adopt thermistor accompanied with the voltage divided circuit to achieve speed control with temperature. Finally, for the sake of reducing the cost and shrinking the size of system, the design of sensorless mode is proposed and the rotation speed control system is realized under sensorless mode.

Modern arc welding machines utilize controllable high frequency DC/DC power supply with high dynamic and steady state current regulation performance. In the design robustness, small size and low weight, low complexity, and high efficiency are the defining criteria. The most suitable approach for a 5 kW arc welding machine power supply application is the high frequency Full-Bridge Phase-Shifted Zero Voltage Switching (FB-PS-ZVS) DC/DC converter with an isolation transformer. This converter not only gives the advantage of zero voltage switching for a wide load current range, it also provides reduced Electromagnetic Interference (EMI) and reduced component stress compared to standard PWM converters. In this thesis a FB-PS-ZVS DC/DC converter with 5 kW power rating is designed for modern arc welding machine applications. IGBTs are utilized at 50 kHz switching frequency for high efficiency and control bandwidth. The output current of the DC/DC converter is controlled via a Digital Signal Processor (DSP) control platform. The performance of the designed DC/DC converter is evaluated via the computer simulations and the experimental study of the constructed prototype.

In this thesis, a test system is designed and implemented in order to evaluate the basic electrical performance and determine the parameters of ultracapacitors (UC). The implemented UC test system is based on power electronics converters and it is capable of charging and discharging the UC under test with predetermined current profiles. The charging operation is provided by a configuration involving the AC utility grid, a step-down transformer, a diode bridge, and a DC bus filter capacitor followed by a step-down DC-DC converter. The energy stored in the UC under test, as a result of the charging operation, is discharged to a resistor bank through a step-up DC-DC converter and a DC chopper structure. The charging and discharging current applied to the UC under test is provided by means of current mode control of power electronics converters. The control mechanism of the power electronics converters and the transition operations between the charging and discharging phases of the test system is realized via a microcontroller supported hardware structure. In the scope of the thesis study, a UC module composed of five serially connected UC cells is constructed. Constant current and constant power tests are applied to the constructed UC module. The performance of the implemented UC test system is investigated by means of computer simulations and experimental results. Further, basic electrical behaviour of the constructed UC module is evaluated and the parameters are extracted experimentally.

This dissertation is to investigate the power system service quality of a Mass Rapid Transit (MRT) system and derive the proper transformer planning to enhance the system operation efficiency. The transformer loading factor is improved by proper capacity planning by considering the power demand according to the growth of ridership. To mitigate the harmonic distortion, the installation location and capacity of harmonic filters are designed and verified by computer simulation. In this dissertation, the software programs for the AC/DC load flow study and harmonic analysis have been developed and integrated to simulate the MRT power system. To enhance the accuracy of computer simulation for the system operation with multiple trains on the main lines, the effect of voltage fluctuation to the traction effort of a train set is considered in the AC/DC load flow analysis. The mathematical model of 12-pulse uncontrolled rectifiers without interphase transformers has been derived and implemented in the programs to obtain more accurate simulation results. To achieve better cost effective capacity planning of main transformers, the unit commitment is applied to derive the optimal transformer capacity to meet the annual peak demand and provide reserve for service reliability. The power consumption of an MRT system is varied with the train operation modes and the route gradient, curvature of MRT networks. The motion equation of train sets has been applied to find the dynamic power consumption and travel distance for each time snapshot. The AC/DC load flow analysis is performed to find the annual power loading of traction substations and whole Taipei MRT network. The energy loss, investment cost of main transformers, and the system service reliability are used to define the equivalent cost of all feasible states for each dynamic programming stage. According to the computer simulation, significant cost saving has been obtained by the proposed methodology for transformer capacity planning of Taipei MRT network. Due to the dynamic load behavior of train sets, the stochastic harmonic distortion of an MRT system is simulated. The mathematical model of the 12-pulse uncontrolled rectifiers without interphase transformers is considered in the harmonic load flow analysis to solve the power demand and harmonic injection currents at traction substations for each time snapshot. According to the mean values and standard deviation of injection harmonic currents, the stochastic harmonic load flow analysis is executed to find the average value and the confidential interval of harmonic voltage distortion for all system buses. By this method, the system voltage harmonic distortion can be evaluated more accurately to provide better guidance for the strategy of harmonic mitigation. According to the results of the stochastic harmonic load flow, different strategies of harmonic distortion mitigation are investigated. Both the fixed type and switching type of passive filters are considered to be implemented. The cost function of filter investment and the harmonic distortion are used in the objective function by considering the regulation of harmonic distortion and system voltages as the constraints. By performing the nonlinear programming, the proper capacity of harmonic filters for each harmonic order and the corresponding switching time of unit commitment is determined. To further improve the power quality, the hybrid filter is also proposed for better distortion mitigation. The analysis of distortion mitigation by harmonic filters are performed to demonstrate the effectiveness of the hybrid filters to improve the power quality of MRT systems.

Electric propulsion has been studied for a long time. Most of the electrically propelled vehicles that have been developed however have been ground vehicles. Recent research by NASA has promoted the development of electric aircraft. Most aircraft are currently powered by heavy gas turbine engines that require fueling. The development of electric motors to replace gas turbines would be a big step towards accomplishing more efficient aircraft propulsion. The primary objective of this research extends previous work by developing a high power density motor for aircraft propulsion. This design is novel because it does not require a dynamometer to provide the torque to drive the vehicle. Equally important for successful testing of the motor was the design and development of a spin pit interface that was used as a containment vessel during testing. The research led to a designed, fabricated, assembled, modeled, and tested motor. Voltages, currents and power outputs of the motor were measured and used to determine the motor’s efficiency. The gaps between the motor’s magnets were related to the current and power it produced, and modifications were made based on this relation. The vibrations of the motor were also studied and MATLAB codes were written and used to reduce these vibrations. Significant among the objectives was monitoring the temperatures of the motor’s stators due to their close association with the rotating parts. The windage and friction losses between the stators and the magnets provided a challenging hurdle in the research. These windage and friction losses were predicted, analyzed and measured, and modifications were made to reduce them. Finally, results were compiled, tabulated, and analyzed. Results obtained before and after the modifications were compared, and these comparisons were used to assess the necessity and effectiveness of the modifications. The efficiency of the motor was found to be 82.9% and the power density was evaluated as 33.1 W/lb based on a rotor weight of 497 lb. It was concluded that the litz wire used in the motor has high, frequency related impedances that could be reduced but not eliminated.