The main objective of the study was to determine the effects of enzymes on quality of breads baked in halogen lamp-microwave combination, microwave and conventional oven. It was also aimed to determine the optimum processing conditions in these ovens. In the first part of the study, as independent variables, baking time, baking temperature for conventional oven / microwave power for microwave oven and microwave power and halogen power for combination oven was used. Weight loss, specific volume, firmness and color of the breads were measured during the study. The optimum baking conditions were determined as 13 min at 200&deg / C in conventional oven, 0.75 min at 100% power in microwave oven, 10 min at 60% power in halogen lamp oven, and 3 min at 30% microwave power and 70% halogen lamp power in halogen lamp-microwave combination oven. In the case of combination oven, specific volume and color values of breads were comparable with the conventionally baked breads but weight loss and firmness of them were still higher. The effects of different enzymes (&amp / #945 / -amylase, xylanase, lipase &amp / protease) were studied to reduce the quality problems of breads baked in microwave and halogen lamp-microwave combination oven. The optimum baking conditions determined for each type of oven in the first part of the study were used in the investigation of the functions of enzymes on bread quality during baking and staling. As a control, no enzyme added breads baked at 200&deg / C for 13 min in conventional oven were used. All the enzymes were found to be effective in reducing initial firmness and increasing specific volume of breads baked in microwave and halogen lamp-microwave combination ovens. However, in conventional baking, the effects of enzymes on crumb firmness were seen mostly during storage. The usage of enzyme protease in the bread formulation resulted in breads with higher volume and darker color in all of the ovens. All of the enzymes were found to be effective to retard the staling of breads baked in conventional, microwave and halogen lamp-microwave combination ovens.

The dissertation investigates the starting transient behaviors of metal halide lamps driven by constant currents and constant powers, respectively. Based on the investigation results, three starting scenarios are proposed for shortening the starting time, and an identification strategy is figured out for designing an electronic ballast being capable of driving three small-wattage lamps rated at different powers. A laboratory electronic ballast is designed to drive small-wattage metal halide lamps with a programmable low-frequency square-wave current. Experiments are conducted to examine the effects of the starting current on variations of the light output as well as the lamp voltage and power. From the effects of the applied current on the generated luminance, three starting scenarios are attempted to accelerate the starting transient stage. Experimental evidence shows that the starting time can be effectively shortened by increasing the lamp current during glow-to-arc and warm-up stages. A short interval of over-power operation during the warm-up stage enables the lamp to further enhance the producing of luminance quickly, and hence greatly reduce the starting transient period. According to the starting transient characteristics of metal halide lamps, an identification strategy is figured out to recognize three small-wattage metal halide lamps rated at powers of 20-W, 35-W and 70-W from three world-wide prominent brands, GE, OSRAM and PHILIPS. An electronic ballast is designed to drive the metal halide lamps with the multi-stage constant-power starting scenario. Experimental results evidence that the electronic ballast with the proposed identification strategy can recognize three lamps¡¦ rated powers correctly during the starting transition, and drive the lamp to its rated power before entering the steady-state.

Halogen lamps are mostly applied as a light source to the traditional lamp for medical treatment due to its proper color temperature, but it has its disadvantages such as ultraviolet rays and infrared rays which will be harmful to the patients and faculties in the hospitals under long-term exposure. Consequently, using light emitting diode(LED) as a new light source instead of the traditional halogen lamp will be the trend of the future. The purpose of this study is to design a projective LED dental lamp that can achieve the goals of 200mm¡Ñ100mm for light shape and 11000lux illuminance energy by using the optics simulation software, LightTools. Firstly, a single LED lamp module with a high focusing hollow tubular light guide structure was designed and developed comparing with the solid light guide structure used in many commercial projective dental lamp, the hollow tubular light guide structure can decrease illuminance energy lose due to the absorption by tube material. Because the required objective light shape could not be achieved by using the designed light guide structure only, so a lens component was adopted and designed in order to shrink the output light shape to the required size. Finally, through the specific arrangement of position and angle of each LED lamp module, a projective LED dental lamp with 9 LEDs lamp modules which conform with the required illuminance energy was proposed.

A high efficiency driver is designed for light emitting diode (LED) street lamps in the thesis. The main power conversion circuit employs a phase-controlled rectifier to convert the power from the ac mains of 110/220 V, 60 Hz directly into a dc source, providing the required output current for the street lamps formed by arrayed high brightness white LEDs. The phase-controlled rectifier of the LED driver circuit can be a conventional semi-converter or a rectifier with symmetrical phase control, which makes use of thyristors and power transistors, respectively, to regulate the LED current by means of adjusting the conduction angles in a cycle of the ac line. The phase-controlled rectifiers may exclude the use the bulky electrolyte capacitor with acceptable variation in the chromaticity and the color temperature. Operating at the low frequency, the phase-controlled rectifiers can avoid the problems of electromagnetic interference caused by high-frequency switching and adopt low cost power switches. Furthermore, a relatively high power factor can be achieved when the line source voltage varies within a small allowable range. The research is targeted to a design of a 200 W LED street lamp. To facilitate the changes of the control functions and circuit parameters, the control circuit is realized with a microcontroller. In addition, over-voltage/current protections can be included easily. Experimental results demonstrate that the phase-controlled rectifiers with appropriately designated circuit parameters can approach a power factor of 0.92 and a circuit efficiency of 93% at the rated output.

The background and motivation of this study are based on: (1) Energy saving and carbon emission reduction are the rising issues gaining more awareness and efforts worldwide. (2) Taiwan plans to build ¡§low-carbon cities¡¨ in order to implement the policy of greenhouse gas reduction. (3) The most direct and practical way to reduce carbon emissions is by saving energy. (4) Everyone has to use illumination sources. (5) ¡§Electro-Magnetic Induction Lamps¡¨ is a useful tool to achieve the goal of energy saving and carbon emission reduction. Thus the topic of this study is ¡§The Effectiveness Analysis and Strategy of Energy-efficient Lighting in Developing a Low Carbon City ¡V A Case on Electro-Magnetic Induction Lamps¡¨. The objectives of this study are: 1. To analyze the characteristics of ¡§Electro-Magnetic Induction Lamps¡¨ and their conformity with local and overseas energy-efficient lighting policies. 2. To analyze the effectiveness of lighting economics of the case companies before and after their adoption of ¡§Electro-Magnetic Induction Lamps¡¨. 3. To explore the possible obstacles and their solutions for lighting industry development of ¡§Electro-Magnetic Induction Lamps¡¨ in the public sectors¡¦ strategies to develop low-carbon cities in Taiwan. The main issues of this study are about energy-efficient lighting policies and the economical effectiveness of ¡§Electro-Magnetic Induction Lamps¡¨, which belong to policy research on energy-saving equipment and the lighting industry. Therefore three research methods: Literature Review, Case Study, and In-depth Interview were adopted to collect, compare, and analyze the data. The conclusions of this study are: 1. The characteristics of ¡§Electro-Magnetic Induction Lamps¡¨ are in conformance with energy-efficient lighting policies in Taiwan. 2. To provide the analysis result of the case companies¡¦ economic benefits after its adoption of ¡§Electro-Magnetic Induction Lamps¡¨. 3. To indicate the possible Dilemma of the lighting industry development of ¡§Electro-Magnetic Induction Lamps¡¨ and the energy-efficient lighting policies for the strategies to develop low-carbon cities in Taiwan. According to above research outcomes, three suggestions have been further proposed: 1. Users must change their concepts and habits of lighting usage in order to cultivate good energy-saving habits. 2. Users must select appropriate illumination sources according to their needs in order to achieve most effectiveness of lighting economics. 3. According to the needs of appropriate illumination sources, the government should promote and subsidize the development and use of ¡§Electro-Magnetic Induction Lamps¡¨.

The operating characteristics of metal halide lamps are investigated, including acoustic resonance, spectral energy, and luminous efficacy. To operate metal halide lamps at intended conditions, two test sophisticated ballast circuits are built to drive the lamps with sine-wave current and square-wave current, respectively. One ballast employs the series resonant inverter to output sinusoidal lamp current over a high-frequency range from 20 kHz to 300 kHz. The other makes use of the full-bridge inverter to drive the lamps with square-wave current from 50 Hz up to 300 kHz. For both test circuits, the operating frequency and the magnitude of the lamp current can be controlled independently. On the other hand, the lamp power is adjusted by regulating the DC-link power. Several conclusions are drawn from experimental results: (1) Little difference is found between the lighting spectra of a lamp when driven by sinusoidal current and square-wave current. (2) Luminous efficiency deteriorates as the operating frequency increases. The deterioration is more significant at lower frequencies. (3) Luminous efficiency decreases considerably as the lamp power is reduced. (4) Arc instability from acoustic resonance is highly related to the waveform of the lamp current. The investigated results give better understanding on the steady state operation of metal halide lamps and provide useful information for the design of the electronic ballasts.

Fluorescent lamps are in general driven by ac ballasting currents. The cyclic variation in arc discharging power results in light fluctuation at twice the frequency of the ac current. Light fluctuation may be intolerable when a steady light output is required in some particular applications. To eliminate light fluctuation, an electronic ballast with dc current is proposed to operate the fluorescent lamp at a constant power. The main power conversion of the electronic ballast employs the single-stage high-power-factor inverter, which is originated from a combination of the half-bridge resonant inverter and the buck-boost converter. With such a circuit configuration, the output power can be regulated by asymmetrical pulse-width-modulation. The ac output of the inverter is then rectified and filtered to provide the dc ballasting current. Driven by dc current, however, the fluorescent lamp emits electrons unilaterally from one end leading to wearing out of emission material on the cathode filament. To solve this problem, an inverter is integrated for commutation of the lamp electrodes. Furthermore, a preheating control is included to start the fluorescent lamps with zero glow-current. A prototype is designed and built for the OSRAM T5-80W fluorescent lamp. The dc operating characteristics of starting transient, light fluctuation, lighting spectra, color temperature as well as the light fluctuation are investigated from experiments. Experimental results also show that the electronic ballast is capable of high-power-factor, dimming capability and zero glow-current preheating.

A flash lighting circuit with the fluorescent lamp is designed to produce lighting flicker by means of controlling the operating frequency and the duty-ratio of the lamp voltage and current. The intensity of the flash lighting is adjusted by the DC-link voltage of the electronic ballast circuit. The circuit structure is mainly composed of the class-D series-resonant inverter, the full-bridge rectifier, the LC filter and the commutation circuit. A control circuit with complex programmable logic device (CPLD) is used to accomplish the regulation of the operating frequency and the duty-ratio, which should be carefully controlled to ensure a stable lighting arc. In the meantime, a flash lighting detected circuit is designed to transform the flash lighting into a voltage signal. Experiment tests are conducted to human visual perception to demonstrate the applicability of the flash lighting circuit.

A single-stage high-power-factor electronic ballast is designed for fluorescent lamps with dimming capability. The circuit configuration is originated from the integration of the half-bridge resonant inverter and the buck-boost converter. The buck-boost converter is designed to operate in discontinuous conduction mode (DCM) to provide nearly unit power factor at a fixed switching frequency. With asymmetrical pulse-width-modulation (APWM), the lamp power can be effectively regulated. The power switches of the inverter exhibit either zero-voltage-switching (ZVS) or zero-current-switching (ZCS) over the whole dimming range. Design equations are derived and computer analyses are performed based on a power-dependent lamp model and fundamental approximation. Design guidelines for determining circuit parameters are provided. A prototype circuit for a T8-36W fluorescent lamp is built and tested to verify the analytical predictions.

The metal halide lamp has become an attractive lighting source because of its compact size, good color rendering, long lamp life, and high luminous efficacy. As a member of high-intensity discharge lamps, it has a negative incremental resistance, which claims the necessity of a ballast circuitry. Similar to other gas discharge lamps, the operating performance can be further improved when driven by a high-frequency electronic ballast. However, there are some obstacles in ballasting the metal halide lamp with the high-frequency inverter. For a cold lamp, an ignition voltage up to several kVs is required for breaking down the electrodes during starting period. The breakdown voltage and the equivalent lamp resistance may vary from time to time and lamp to lamp, and is sensitive to the used time. Furthermore, the ignition voltage for restarting a hot lamp can be ten times that for a cold lamp. On the other hand, the lamp driven by a high-frequency electronic ballast may suffer from acoustic resonance. All these make it difficult in the design of an electronic ballast, especially for the applications with hot restarting. In this dissertation, the operating characteristics for both starting transient and steady-state of the metal halide lamp are first investigated. Then, a simple method by measuring the lamp voltage is proposed to detect the happening of acoustic resonance. Based on the investigated results, several electronic ballasts are designed for driving metal halide lamps with capabilities of wide input voltage range, high input power factor, hot restarting, fast transition. In addition, an inverter circuit is configured for ballasting multiple lamps. A buck-boost power-factor-correction circuit is integrated into the load resonant inverter to achieve a high power factor, fast transition, and constant power operation. The extremely high ignition voltage for hot restarting is generated by an auxiliary ignitor. The electronic ballast is precisely operated at the specific frequency at which acoustic resonance will not occur. In addition to these features, a protection circuit is included to prevent from high voltage and/or current stresses on circuit components in case that the lamp fails to be started up or comes to the end of its life-time. For the ballast with multiple lamps, the load circuits with abnormal lamps can be isolated from the others which are under normal operation. Prototypes of the proposed circuits are built and tested. Experimental results present the satisfactory performances.