公开(公告)号：US11366152B2

公开(公告)日：2022-06-21

申请号：US16666428

申请日：2019-10-29

Applicant: University of Electronic Science and Technology of China

Inventor： Dong Liu ,  Yan Yan ,  Xiaoting Xiao ,  Bin Gao ,  Guiyun Tian

IPC: G01R29/22 ,  H03H9/17 ,  H03H9/19

Abstract: 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.

公开(公告)号：US10229486B2

公开(公告)日：2019-03-12

申请号：US15608320

申请日：2017-05-30

Applicant: UNIVERSITY OF ELECTRONIC SCIENCE AND TECHNOLOGY OF CHINA

Inventor： Bin Gao ,  Xiaoqing Li ,  Guiyun Tian

IPC: G06T7/00 ,  G06F17/18 ,  G06T7/162

Abstract: 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 ki of total pixel number Si of group i, finds the maximum absolute value of ki, i.e. |ki|max, where i is expressed as imax; if imax is the last group, Wn is regarded as threshold T, otherwise, Wimax+1 is selected as threshold T. The pixels that less than threshold T are removed to obtain the defect image in ECPT.