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Your search keyword '"Qiu, Yanzhang"' showing total 12 results
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12 results on '"Qiu, Yanzhang"'

4. Optimal frequency band design scheme of dyadic wavelet processor array using surface acoustic wave devices

Author

Wen, Changbao, Zhu, Changchun, Ju, Yongfeng, Qiu, Yanzhang, Xu, Hongke, and Lu, Wenke

Subjects
Wavelet transforms -- Analysis, Acoustic surface waves -- Usage, Business, Computers, Electronics, Electronics and electrical industries
Abstract

In this paper, the relationship between the center frequency and radius of bandwidth and its effect on the frequency band characteristics of dyadic wavelet processor array using surface acoustic wave (SAW) devices are studied, and an optimal frequency band design scheme is proposed. For an arbitrary scale wavelet processor, we proposed that the center frequency is defined to three times of the radius of frequency bandwidth. The frequency band design scheme ensures that the frequency band coverage factor is equal to 100% at -3 dB, which avoid the signal loss caused by the discrete frequency band and the device waste caused by the redundant frequency band. With the frequency band design scheme, an experiment of implementing a dyadic wavelet processor array using SAW devices with five scales is presented. Experimental results confirm that the frequency band coverage factor equals 100% at -3 dB without discrete and redundant frequency band. Index Terms--Frequency band, surface acoustic wave (SAW) device, wavelet.

Published
2009

5. Fixed‐frequency adaptive off‐time controlled buck current regulator with excellent pulse‐width modulation and analogue dimming for light‐emitting diode driving applications

Author

Chai Hong, Tong Qian, Changbao Wen, Wu Kaikai, Yang Xiaobing, Li Yanming, and Qiu Yanzhang

Subjects
Engineering, Settling time, business.industry, Automatic frequency control, Electronic engineering, Constant current, Sense (electronics), Electrical and Electronic Engineering, business, 500 kHz, Pulse-width modulation, Diode, Voltage
Abstract

This study presents an ideal synchronous buck current regulator for variety of light-emitting diode (LED) loads from wide input voltage range. By using high-side power switch matched sense, the regulator maintains high current accuracy and high system efficiency. The adjustable current sense threshold provides a full-range analogue dimming and the fast output enable/disable function allows for high-frequency pulse-width modulation (PWM) dimming. In addition, the two dimming methods are easy to implement and have highly linear range. An adaptive off-time control is adopted to regulate an accurate constant current for its fast response and no need for control loop compensation, while its disadvantage of variation of switching frequency is overcome. The proposed circuit has been fabricated with 0.35 μm 40 V bipolar-CMOS-DMOS (BCD) process successfully. The experimental results confirm that the LED driver can operate within 6–40 V input voltage, and can drive a 1–10 output series connected LEDs. The switching frequency is fixed at 500 kHz with a variation of ±2%. The measured system peak efficiency is up to 95% at 1 A LED current and 10 V output voltage. The settling time at the PWM rising edge is

Published
2015
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7. The design of lower limbs rehabilitative training device control system

Author

Wu Xiong, Qiu Yanzhang, and Guo Liang

Subjects
Microcontroller, Engineering, Medical robotics, business.industry, Control system, Training (meteorology), Software design, Control engineering, Servomotor, business, Simulation
Abstract

This paper discussed a control system implementation of a lower limbs rehabilitative training device, which includes the hardware and software design of the MCU system and the servo motor drive system. The prototype achieves the aim of simulating the normal human's sit, stand, exercise, walk and other movements. The circuit structure of the control system is novel, easy to manufacture and can obtain higher precision.

Published
2010
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12. A novel NO2 gas sensor using dual track SAW device

Author

Wen, Changbao, Zhu, Changchun, Ju, Yongfeng, Xu, Hongke, and Qiu, Yanzhang

Subjects
*NITROGEN dioxide, *GAS detectors, *ACOUSTIC surface wave devices, *MICROFABRICATION, *ELECTRONIC equipment design, *QUANTUM perturbations, *WAVELETS (Mathematics), *POVIDONE
Abstract

Abstract: A nitrogen dioxide (NO2) gas sensor using dual track surface acoustic wave (SAW) device was developed and fabricated in this paper. The dual track architecture and the MSCs were skillfully applied to the sensor. The external perturbations were eliminated by the dual track architecture, and the bulk acoustic wave (BAW) was suppressed by Multistrip coupler (MSC). The input IDT apodized by Morlet wavelet function can improve the side lobe rejection compared with uniform IDT. Utilizing Tungsten powders, hydrogen peroxide, absolute methanol and polyvinylpyrrolidone as raw materials, the micro-porous network Tungsten trioxide (WO3) film sensitive to NO2 gas was fabricated in measurement acoustic track of dual track SAW device. Experiments results confirm that the NO2 gas sensor using dual track SAW device has good response characteristics to different concentrations NO2 gas from 0.5ppm to 10ppm. Furthermore, the NO2 gas sensor using dual track SAW device has good reproducibility and stability. [Copyright &y& Elsevier]

Published
2010
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