control systems, adaptation, learning, connectionism---even neural networks!).The authors explain the need for adaptive control: "...the plant to be controlled is too complex and the basic physical processes in it are not fully understood. Control design techniques then need to be augmented with an identification technique aimed at obtaining a progressively better understanding of the plant to be controlled. " Early on (but after your reviewer had left the scene) practitioners of control theory found that they could arrive at the answers to important questions through the use of very sophisticated axiomatic mathematics, complete with theorems and lemmas. This book certainly has its share. It would be unfair to accuse these workers of indulging in pure mathematics; they have been applying their mathematics to serious life-and-death matters, such as preventing helicopters from crashing, for example. If this is what is needed to solve these problems, more power to them.Using these rigorous techniques, the authors of this text delve into the subjects that form their subtitle: Stability, Convergence and Robustness. Upon reading the book, this reviewer forms the impression that the authors are quite proud of their original research results in the use of averaging techniques.There is no doubt that this is a very good book. However, the question naturally arises when one reviews a book for the Journal of the Acoustical Society of America: Is anyone in the Society interested in the subject? After all, to the reviewer's knowledge, the word acoustics seems not to appear anywhere in the text. Well, as a matter of fact, articles on noise control do appear in the Journal, and the authors do employ the methods and results of control theory. I recommend this book for inclusion in the libraries of the practitioners in our midst or anyone else who might be interested. Academic, San Diego, CA, 1989. xix-/-694 pp. Price $84.50. I recommend that this book be in the collection of every serious student and practitioner of ultrasonics. Everyone in the quantitative end of process control should have it also.In terms of the depth of his own knowledge and the amount of material he has amassed and put down cogently and coherently, Lynnworth has produced a monumental work. I highly approve of his assumptions about what to include, and his organization of the material.In particular, Chap. 3 on "Theory and Measurement Techniques" contains exactly the correct balance between the results of theory and the extension to metrology. The process control engineers will be pleased with the presentation, which will serve them well. The readership will extend through the whole spectrum to professors of physics, too, who will tell their students to read Lynnworth for an overview and for a perspective on the real world. The professors will, indeed, look to this book for original references when their computerized databases turn up only the last 10 years or maybe only five. This book may help researchers keep from reinventing the wheel every ten years, an...
