(From Xu Delong of Ultrasonic Physics and Exploration Lab) On May.13, Prof. Lu Jianyu, the co-president of 2008 IEEE IUS (International Ultrasonics Symposium), visited IACAS and gave a lecture titled "Theoretical Development of Ultrasonic X Waves and Its Applications". Academician Ying Chongfu, Prof. Wang Xiuming, Prof. Zhang Hailan, Prof. Qian Zuwen, Prof. He Shitang and Prof. Yang Jun et al attended the seminar, which was presided over by Lin Weijun.

Prof. Lu, Director of Ultrasonic Laboratory of Toledo University in the U.S., engaged in theoretical and applied research of ultrasonic X wave for many years. In his report, Prof. Lu introduced the mechanism of X wave and its propagation characteristics and showed the application of X wave in biomedical ultrasonic imaging. X wave, named after its conformation, might be used in communication and biomedical ultrasonic imaging because it did not diffuse easily in long distance. The Ultrasonic imaging devices based on X wave developed by Prof. Lu have the advantages of high frame rate and big depth of field. According to Lu, the phase velocity and group velocity of X wave can be faster than the acoustic velocity of the medium. Academician Ying and Prof. Qian discussed the X theory and future application with Prof. Lu.

After the seminar, Prof. Zhang Chunhua, the associate director of IOA, Prof. Zong Jian, the associate director of Society of Acoustics in China, Prof. Zhang Hailan, another co-president of 2008 IEEE IUS, etc. discussed with Prof. Lu about the preparation of 2008 IEEE IUS which will be held from Nov. 2 to Nov. 5 in Beijing.