(From XU Delong of Ultrasonic Physics and Exploration Laboratory) On March 22, the thirteenth activity of the serial academic activities organized by Ultrasonic Physics and Exploration Laboratory (UPEL) was held in Room 218 of Dezhao Building. Academician Ying Chongfu, Prof. Li Mingxuan, Prof. Wang Xiuming, Prof. Liu Yinbin et al attended the seminar presided over by Lin Weijun.

Prof. Mao Jie and Associate Porf. Lian Guoxuan gave their lectures titled "The application of resonance frequency for distinguishing a thin film under a multi-layered system in the ultrasonic testing" and "The ultrasonic value of adhesion intensity by pilot plant study", respectively.

In Mao's lecture, the application of resonance frequency for distinguishing a thin film under a multi-layered system in the ultrasonic testing was introduced through the research background, the theoretical analysis and experimental study. In theoretical analysis, the sensitivity function was put forward and its physical meaning was explained accordingly. By using the function, the single-parameter and double-parameter inversions were carried out. In the experimental study, the error-transferring coefficient was used to analyze the testing result. At last, it was founded that the theoretical and experimental results coincided with each other very well.

In Lian's lecture, the meaning and target of ultrasonic value of adhesion intensity, the design and result of tensile intensity and shear intensity pilot plant were introduced. AS it was well known that the research faced big challenges, but the results were encouraging. To make this research better, Lian brought forward some new ideas for the next step work in the end of his report.

The serial academic activities held by UPEL began in January 2007. During one more year, thirteen activities had been held. The young researchers learned a lot from these activities. In the new year, the colorful activities will be held further and better.