Characterizing Motion with Ultrasound

超声是一种新兴的无损评价方法。超声波的一个潜在优点是可以通过观察返回信号的频移来检测物体的运动。本研究将通过开发利用反射超声信号测量运动参数的程序并确定其局限性来寻求利用这一优势。考虑了广泛的运动类型，从确定单个运动点反射器的运动参数到表征随机反射器集合的运动。程序包括分析、模拟和实验。基本的限制是由于声速、孔径的有限尺寸和噪声的存在。这些限制的影响将通过考虑放置多个换能器和新的信号处理程序来研究。这应该允许将这些物理限制转化为可应用于实际仪器的精度界限。这项研究的结果将增强对声信号探测介质的理解，并确定新一代测量仪器的可行性。

Ultrasound is an emerging method employed for nondestructive evaluation. One potential advantage of ultrasound is that the motion of an object can be detected by observing the frequency shift of the returned signal. This research will seek to exploit this advantage by developing procedures to measure motion parameters with reflected ultrasound signals and by determining their limitations. A wide range of motion types are considered, from determining the motion parameters of a single moving point reflector through characterizing the motion of a collection of random reflectors. The procedures involve analysis, simulation and experiments. The fundamental limitations are due to the speed of sound, the limited size of the apertures, and the presence of noise. The impact of these limitations will be investigated by considering the placement of multiple transducers and novel signal processing procedures. This should allow translation of these physical limitations into bounds on the accuracy that can be applied to practical instruments. The result of this research will enhance the understanding of probing media with acoustic signals and determine the feasibility of a new generation of measuring instrumentation.