On the morning of Aug.6, 2007, Professor Guo Chengbing of our institute and Dr. Zeng Zhengwen of North Dakota University gave us wonderful academic lectures, respectively.

The lecture Prof. Guo Chengbin gave us titled "Automatic ultrasonic flaw detection system of the hollow axle in High-speed train". As we all know, the high-speed trains are very convenient for the passengers, which are made up of some sections driven by self-provided power and some without. Prof. Guo was also invited to participate into the check of the "Automatic ultrasonic flaw detection system of the hollow axle in high-speed train" program in Jul this year. In this report, he first introduced the function of the hollow axle and stressed the importance of checking the fatigue situation of the hollow axle. Prof. Guo analyzed the structure of the automatic ultrasonic flaw detection system and its work going by many pictures. At last, he gave his comments on the advantages and disadvantages of the system. Prof. Guo's report enriched our knowledge and broadened our horizon.　 　 

The report Dr. Zeng gave us titled "CO₂ phase transition induced acoustic velocity change in porous media". His report put emphasis on the environmental geophysics. He pointed out that since 1960s the global temperature has been rapidly increasing because of the vast emission of CO_2. Now many countries of the whole world were devoted to find the ways to diminish this kind of pollution. And now the more popular one was piping the collected CO₂ into the underground medium. So the research on the rock physical parameter in the high-temperature and high-pressure situation is an important part of the whole process. So in his report, he introduced the related measuring system and analyzed the experimental results.　　

Prof. Guo Chengbing

Dr. Zeng Zhengwen