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Passive Geometry Fluctuation in Minkowski Vacuum
Chun-Hsien Wu 한국물리학회 2004 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.45 No.1
The quantum uctuation of the stress tensor of a quantum field are discussed, as are the resulting spacetime metric uctuations. In the case of the Minkowski vacuum these were calculated explicitly and the operational signicance of metric uctuations are discussed using a test particle method. A test particle undergoes Brownian motion induced by an electromagnetic vacuum energy uctuation. The induced position uncertainty is considerable when measured in one unit of the Planck time and is supressed when the time scale is larger than a few units of the Planck time.
Hsien-Tang Tsai,Shi-Zheng Huang,Chun-Hsien Wang 기술경영경제학회 2015 ASIAN JOURNAL OF TECHNOLOGY INNOVATION Vol.23 No.3
The concept of the cross-border collaboration network has been recognised as a useful way toobtain external R&D knowledge resources in the biotechnology industry. Drawing on socialcapital theory, this study explores how two types of network position (centrality andstructural holes) and cross-border collaborative ties affect the cross-border R&Dcollaborative alliance of the biotechnology firms and how these effects are contingent onexploratory collaboration with their collaboration partners. Analysis of the data collectedfrom 174 cross-border collaboration partners in the emerging biotechnology sector indicatesthat the two types of network position differ in the extent to which they contribute to thecross-border R&D collaborative alliance. By investigating the contingent role of exploratorycollaboration, we find that exploratory collaboration weakens the impact of networkcentrality on the cross-border R&D collaborative alliance but strengthens the effect ofstructural holes on the establishment of cross-border R&D collaborative alliance. Resultsconfirm that biotechnology firms’ cross-border R&D knowledge resources need to extendbeyond their industry and regional boundaries. More specifically, this study contributes tothe debate on whether network centrality and structural holes are complementary and thusenrich contextual cross-border alliance literature
Chun-An Cheng,Chien-Hsuan Chang,Hung-Liang Cheng,Tsung-Yuan Chung,Ching-Hsien Tseng,Kuo-Ching Tseng 전력전자학회 2016 JOURNAL OF POWER ELECTRONICS Vol.16 No.4
This study proposes a single-stage light-emitting diode (LED) tube lamp driver with input-current shaping for T8/T10-type fluorescent lamp replacements. The proposed AC–DC LED driver integrates a dual-boost converter with coupled inductors and a half-bridge series-resonant converter with a bridge rectifier into a single-stage power conversion topology. This paper presents the operational principles and design considerations for one T8-type 18 W-rated LED tube lamp with line input voltages ranging from 100 V rms to 120 V rms. Experimental results for the prototype driver show that the highest power factor (PF = 0.988), lowest input current total harmonic distortion (THD = 7.22%), and highest circuit efficiency (η = 92.42%) are obtained at an input voltage of 120 V. Hence, the proposed driver is feasible for use in energy-efficient indoor lighting applications.
A Novel Single-Stage LED Driver with Coupled Inductors and Interleaved PFC
Chun-An Cheng,Chien-Hsuan Chang,Hung-Liang Cheng,Ching-Hsien Tseng 전력전자학회 2015 ICPE(ISPE)논문집 Vol.2015 No.6
This paper proposes a novel single-stage lightemitting diode (LED) driver with coupled inductors and interleaved power-factor correction (PFC), suitable for streetlight applications. The presented LED driver integrates an interleaved boost PFC converter with coupled inductors and a half-bridge-type series-resonant converter cascaded with a full-bridge rectifier into a single-stage power-conversion circuit. Coupled inductors inside the interleaved boost PFC converter sub-circuit are designed to operate in discontinuous-conduction mode (DCM) for achieving input-current shaping, and the half-bridge-type series-resonant converter cascaded with a full-bridge rectifier is designed for obtaining zero-voltage switching (ZVS) on two power switches to reduce their switching losses. Analysis of operational modes and design equations for the presented LED driver are described and included. In addition, the proposed driver features high power factor, low total-harmonic distortion (THD) of input current and soft-switching. Finally, a prototype 165W-rated LED driver is developed and tested with a utility-line input voltage of 110V. Satisfactory outcomes from experimental results demonstrate the feasibility of the proposed circuit.
Chun-Yu Hsiao,Yu-Hsien Wang 제어·로봇·시스템학회 2022 International Journal of Control, Automation, and Vol.20 No.4
This paper describes the application of a self-tuning fuzzy sliding mode controller (STFSMC) to design the control signal of an electro-hydraulic actuator under standard road excitation based on ISO 8608. The proposed damper was designed to achieve effective vibration isolation with an actuator force. The proposed damper was incorporated into a quarter-car system through experiments for the subsequent dynamic analysis of the suspension system. A single-input single-output (SISO) fuzzy inference was strategically used to regulate the slope of a sliding surface. In addition, the fuzzy control methodology was applied to achieve self-tuning online output of the scale factor of the fuzzy sliding mode controller. The comfortable riding time and ride comfort level were also evaluated based on ISO 2631-1. Experimental results revealed that the proposed controller demonstrated evident improvements in vehicle vibration suppression and the ride quality in comparison with passive and fuzzy logic controller control systems.
Cheng, Chun-An,Chang, Chien-Hsuan,Cheng, Hung-Liang,Chung, Tsung-Yuan,Tseng, Ching-Hsien,Tseng, Kuo-Ching The Korean Institute of Power Electronics 2016 JOURNAL OF POWER ELECTRONICS Vol.16 No.4
This study proposes a single-stage light-emitting diode (LED) tube lamp driver with input-current shaping for T8/T10-type fluorescent lamp replacements. The proposed AC-DC LED driver integrates a dual-boost converter with coupled inductors and a half-bridge series-resonant converter with a bridge rectifier into a single-stage power conversion topology. This paper presents the operational principles and design considerations for one T8-type 18 W-rated LED tube lamp with line input voltages ranging from 100 V rms to 120 V rms. Experimental results for the prototype driver show that the highest power factor (PF = 0.988), lowest input current total harmonic distortion (THD = 7.22%), and highest circuit efficiency (η = 92.42%) are obtained at an input voltage of 120 V. Hence, the proposed driver is feasible for use in energy-efficient indoor lighting applications.