Browsing by Author "Hu, J"

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A self-calibrated speaker tracking system using both audio and video data
(2002)
Hu, J
;
Su, TM
;
Cheng, CC
;
Liu, WH
;
Wu, TI
In this paper, a self-calibrated speaker tracking system applied on both image tracking and sound source detection is proposed. The sound source estimated by microphone system is used to supply video tracking system. On the other hand, the direction of speaker detected by image tracking system is fed back to calibrate the phase distortion between microphones. Some experiments using actual devices are also done to test the performance of the proposed method. It is shown that significant improvement in source localization accuracy is possible when the camera and the microphone system are well calibrated.
Analysis and design of one-bit noise-shaping quantizer using variable structure control approach
(2005-09-01)
Hu, J
;
Yu, SH
;
電控工程研究所
;
Institute of Electrical and Control Engineering
This paper offers a straightforward analysis of a one-bit noise-shaping quantizer based on variable structure control methods. The method uses the concept of equivalent control to access the bound on the state signals when the sliding condition is reached. For a stable loop filter, the global stability can be proved to exist by using the Lyanpunov stability theory. For an unstable loop filter, this paper proposes a state constraint approach to ensure that the sliding condition is achieved. Simulation examples and an experimental circuit constructed using off-the-shelf electronic components are given to demonstrate the correctness of the theoretical analysis.
Energy-dispersive x-ray diffraction and Raman scattering of Zn1-xMnxSe bulk crystals at high pressure
(1999-06-15)
Yang, CS
;
Ro, CS
;
Chou, WC
;
Lin, CM
;
Chuu, DS
Energy-dispersive x-ray diffraction experiments were carried out to investigate the structure of phase transitions under high pressure. It was found that the zinc blende (B-3) to rock salt (B-1) phase transition pressures of Zn0.93Mn0.07Se and Zn0.76Mn0.24Se bulk crystals are found 11.8+/-1.5 and 9.9+/-0.5 GPa, respectively. The respective bulk moduli are 61.8+/-0.8 and 60.5+/-0.8 GPa. The pressure-induced zinc blende (ZB) to rock salt (RS) structure phase transition is interpreted as a signature of the semiconductor to metal transition for Zn1-xMnxSe. The above interpretation is further corroborated by the observation of the disappearance of the longitudinal optical phonon at the pressure where the ZB to RS structure transition occurs. (C) 1999 American Institute of Physics. [S0021-8979(99)05312-8].