基于时频分布的盲信号分离方法研究长骨中的多模式导波信号

由于超声导波对长骨皮质骨的材料特性及厚度变化非常敏感,因此用导波评价长骨状况的研究已成为近年来的一个研究热点。在接收到的导波中,往往多种模式混叠在一起,使得进一步求取每种导波模式的群速度等与骨质状况密切相关的参数时遇到困难。本文采用基于时频分布的盲信号分离(TFBSS)方法对长骨中混叠的多模式进行分离,然后对分离后的单一导波模式求取群速度。研究结果表明TFBSS方法能够准确的分离出混叠的多模式导波,且实验测量的群速度与其理论值吻合。利用导波的群速度就可以得到长骨皮质骨的厚度,这对诊断其骨质状况具有重要意义。

Study on the multiple guided waves in long bones using spatial time-frequency based blind source separation method

Ultrasonic guided waves are very sensitive to the material's characteristics and the change of the cortical thickness in long bones.Therefore,it has been a great interest of using guided waves to assess long bones.However,it's a challenge to acquire the group velocity and other parameters from the long bone because of the mixed multiple modes in the received signals.In the study,the spatial time-frequency based blind source separation(TFBSS)method was employed to separate the mixed signals and then calculate the group velocities of each single mode.The result showed that the TFBSS method can separate the mixed signals correctly,and the experimental measured group velocities are agreed with theory values very well.The cortical thickness could be acquired based on the group velocities,which is quite significant to assess the properties of long bones.