http://hdl.handle.net/10397/57 Search the Channel search http://repository.lib.polyu.edu.hk/jspui/simple-search http://hdl.handle.net/10397/5230 Title: Energy-saving controller for three-phase induction motors<br/><br/>Authors: Cheng, K. W. Eric; Xue, Xiangdang<br/><br/>Abstract: The present invention relates to an energy-saving system for three-phase induction motors and is based on the principle of variable voltage control at constant speed. It is composed of a microprocessor, exampling circuit, sensing circuit, acquiring circuit, firing circuit, and AC to AC converter. The system is to automatically adjust the voltage to the induction motor with the variation in the motor load, in order to obtain high operating power factor and efficiency. The system will result in considerable energy-savings when a three-phase induction motor runs under constant light-load or variable-load with low duty ratio. http://hdl.handle.net/10397/5041 Title: Microhole-structured long period fiber grating<br/><br/>Authors: Wang, Dongning; Wang, Ying; Yang, Minwei<br/><br/>Abstract: An optical fiber with long period fiber gratings includes an optical fiber axis, a core region extending along the fiber axis, the core region having a core refractive index, a cladding region surrounding the core region, the cladding having a cladding refractive index, and a plurality of microholes perpendicular to the fiber axis with a portion of the core region removed, the plurality of microholes are spaced apart by a grating period. http://hdl.handle.net/10397/4898 Title: Phase lead compensation network, power supply converter and closed-loop control system = 相位超前补偿网络、电源转换器及闭环控制系统<br/><br/>Authors: Chan, Wai-lok (陳偉樂); Tsang, Kai-ming (曾啟明)<br/><br/>Abstract: The invention discloses a phase lead compensation network, a power supply converter and a closed-loop control system. The phase lead compensation network is arranged in the closed-loop control system of the power supply converter. The closed-loop control system also comprises a power supply converter and a control module, wherein the power supply converter receives input voltage, generates output voltage and feeds back the output voltage to the control module. The power supply converter comprises an inductor, wherein the power supply converter finishes energy transformation by controlling the current of the inductor; the control module inputs reference voltage and the output voltage of the power supply converter, generates a control signal to the power supply converter and is used for regulating the dynamic response of the power supply converter; and the phase lead compensation network is connected with the inductor of the power supply converter in parallel, and a phase lead network comprises a capacitor and a resistor which are connected in series. The invention can realize the detection of the current of the inductor of the power supply converter with low cost and high efficiency and enhance the stability of the closed-loop control system of the power supply converter.; 本发明公开了一种相位超前补偿网络、电源转换器及闭环控制系统，该相位超前补偿网络设置于电源转换器闭环控制系统内，闭环控制系统还包括：电源转换器和控制模块，其中，电源转换器，接收输入电压，并产生输出电压，并将所述输出电压反馈至所述控制模块，电源转换器包括-电感，电源转换器通过控制所述电感电流来完成能量转换；控制模块，输入参考电压和所述电源转换器的输出电压，产生一控制信号至所述电源转换器，用以调节所述电源转换器的动态响应；相位超前补偿网络与所述电源转换器的电感并联，相位超前网络包括串联的电容和电阻。本发明能实现低成本高效率的电源转换器电感电流检测，并提高该电源转换器闭环控制系统的稳定性。 http://hdl.handle.net/10397/4851 Title: Method and system for bonding electrical devices using an electrically conductive adhesive<br/><br/>Authors: Or, Derek Siu-wing<br/><br/>Abstract: A system for bonding electrical devices using an electrically conductive adhesive to adhere the electrical devices together, the system comprising: an ultrasonic transducer to generate an ultrasonic vibration; and an ultrasonic to thermal energy apparatus operatively attached to and covering an operational end of the ultrasonic transducer, the ultrasonic to thermal energy apparatus damping the ultrasonic vibration to minimize ultrasonic vibration transmitted to a first electrical device and causing the conversion of the ultrasonic vibration to a heating pulse which is conducted through the first electrical device to the adhesive; wherein the adhesive is softened by the heating pulse to bond the electrical devices together.