Lecture Notes on Identification of Media and Structures by Inversion of Mechanical Wave Propagation-Experimental Challenges

Published

October 16, 2008

Author(s)

Nelson N. Hsu, N

Abstract

EXPERIMENTAL ASPECTS OF ULTRASONIC INVERSE MEDIUM PROBLEMS This chapter provides an overview of the experimental aspects of inverse medium problems. We describe the components of quantitative as well as a more typical ultrasonic measurement system which are used to make the measurements and we consider the variety of solutions which are sought. Finally we provide an overview of the other accompanying lectures. ULTRASONIC TRANSDUCERS FOR INVERSE MEDIA PROBLEMS We focus in this lecture on the critical elements in any ultrasonic system and, in particular, that which is used to generate the ultrasonic waveform data which is used as input to an algorithm for solving an inverse problem. That element is the transducer. CHARACTERIZING HOMOGENEOUS, ANISOTROPIC ELASTIC MEDIA We describe in the inversion of ultrasonic wave speed measurements on a solid to determine its anisotropy and the appropriate number of elastic constants needed to represent its elastic properties. SYNERGESTIC APPROACHES FOR SOLVING INVERSE MEDIUM PROBLEMS We describe in this chapter a synergistic ultrasonic measurement system in which the sensing and processing of elastodynamic signals is used to model the characteristics of the medium. Specifically, we shall summarize some of the approaches which resemble intelligent, nature-like signal processing procedures to solve a number of inverse media problems. Characteristic of these approaches is the use of a set of training signals to develop a memory which can subsequently be utilized to process the detected signals to optimally recover information related to the medium. We shall illustrate this approach using a multi-layered, feed-forward neural network or alternatively, a multidimensional regression approach, called an automatic modeler. Examples of ultrasonic measurements using these approaches are shown and some of the challenges for the future indicated.

Citation

Lecture Notes on Identification of Media and Structures by Inversion of Mechanical Wave Propagation-Experimental Challenges

Pub Type

Others

Keywords

anisotropic elastic constants, inverse media problem, semi-inverse techniques, ultrasonic measurement system, ultrasonic transducers

Citation

Hsu, N. (2008), Lecture Notes on Identification of Media and Structures by Inversion of Mechanical Wave Propagation-Experimental Challenges, Lecture Notes on Identification of Media and Structures by Inversion of Mechanical Wave Propagation-Experimental Challenges (Accessed April 25, 2024)