University of Electronic Science and Technology of China

Bin Gao

Guiyun Tian

Dong Liu

Yan Yan

Xiaoqing Li

Xiaoting Xiao

A method for measuring equivalent circuit parameters and resonant frequency of a piezoelectric resonator, by which the phase-frequency curve of the piezoelectric resonator is measured, and the resonant frequency and the anti-resonant frequency are obtained. Then, the slopes of the phase-frequency curve at the resonant frequency and the anti-resonant frequency are respectively measured. The resonant angular frequency and the anti-resonant angular frequency are also calculated. Finally, the equivalent circuit parameters of the piezoelectric resonator are obtained by solving a system of nonlinear equations.

Method for measuring equivalent circuit parameters and resonant frequency of piezoelectric resonator

A method automatically separates out the defect image from a thermogram sequence based on the physical characteristics of the defect of a conductive material in electromagnetic field. Defect area radiates more heat than other area, when it is mapped to the histogram of the image to be separated, the defect area is located in the top-end of histogram, and the proportion of defect area is smaller to the background or other area. The method equally divides the histogram of the image to be separated into multi groups, and calculates the first derivative kof total pixel number Sof group i, finds the maximum absolute value of k, i.e. |k|, where i is expressed as i; if iis the last group, Wis regarded as threshold T, otherwise, Wis selected as threshold T. The pixels that less than threshold T are removed to obtain the defect image in ECPT.

Growing community of inventors

Chengdu, China

Bin Gao