报告题目：Ultrasonic, vibrating, and oscillating structures for ground exploration
报告人：Prof. Patrick Harkness（英国格拉斯哥大学教授）
The exploration of remote areas (such as the polar regions of the earth, or the surfaces of other planets) require relatively small systems that must penetrate the terrain with small amounts of power and at low levels of force. Different terrains present different problems. Granular materials such as sand behave in surprising ways, and ultrasonic vibration can be used to disrupt the mechanisms by which they resist penetration forces. Ultrasonic vibration can also be superimposed on drill tools, applied to rock, with a positive outcome, but when this technique is applied to ice it may cause melting and then cavitation, which can damage the tool. And, at depth, it becomes more difficult to sustain ultrasonic vibration over a long waveguide, and so the hammer mechanism may be separated from the drill, using either the ultrasonic percussion or hammer percussion mechanism. These first items are only the problems of cutting the terrain. The cuttings, both debris and samples, must be lifted out of the hole if progress is to continue. Ultrasonic techniques are being investigated for this application also, to see if the power and force requirements associated with augering – which is perhaps more difficult than cutting – can be reduced as well. Finally, there are the problems of learning how to explore in space, which is very expensive and does not tolerate mistakes. We will discuss how exploration in analogue environments (such as Antarctica) can be used to gain know-how, and produce scientific results which justify the training expeditions in their own right (especially in the context of environmental research).