Electromagnetic Nondestructive Evaluation (III)

Within the context of non-destructive testing, the classical `Formulate-Solve-Interpret' model of problem solving becomes `Measure-Recover-Interpret'. But, before one can perform measurements, there must be appropriate instrumentation. In this book on electromagnetic non-destructive evaluation (ENDE) all these aspects (instrumentation, measurement, recovery and interpretation) are treated, though the major emphasis is on the recovery and interpretation aspects. The focus of the book, as explained in the Foreword and the Summary of the Keynote Address, is ENDE for crack detection and maintenance of pipes and pipe networks as are found in nuclear power plants. In many books on NDE, and, in particular, conference proceedings, theory tends to dominate. Here, the tactical research that flows from the theory is the central issue. There is much useful information about ENDE, as well as the practicalities of NDE, in this book. In addition, it represents a valuable guide for the practical ENDE specialist with responsibility for routine crack detection and, especially, in (networks of) pipes. With so many papers (32), it is only possible to summarize them under the categories in which they appear in the book. (a) Probe design and related issues (6). Two of the papers examine properties of the magnetic field sensors. Three of the papers address matters related to the design of electromagnetic probes for the NDE of pipes. The other paper examines the probes designed for local field excitation. (b) Defect evaluation with emphasis on stochastic methods (6). An alternative title for this section would be `crack identification algorithms'. All the papers in this section are concerned with the recovery of information about the size, location and distribution of the cracks. A variety of identification techniques are examined including wavelet and neural networks as well as the more traditional finite element and signal processing. Not all of the techniques discussed have an explicit stochastic aspect. Together, these paper illustrate, in various ways, how some information is pushed into the background at the expense of the particular information being recovered. Some of the techniques are specific to crack shape identification while others optimize the recovery of size and location. (c) Innovative modalities and applications (3). The role of the Hall sensor, spherical harmonic analysis and microwaves are the three innovative modalities examined in this section. (d) Direct modelling with emphasis on numerical techniques (8). This group of papers examines much more specific matters like the detection of deep defects, SQUIDs, the FLUXSET sensor, cracks concealed in surface deposits, eddy current probe design, the behavior of Cecco probes, steam-generating tubes with a supporting plate, and alternating current magnetic flux leakage testing. Much in this section will be of direct interest to the practising ENDE specialist. (e) Defect evaluation with emphasis on deterministic methods (7). The focus of this section is deterministic algorithms for `crack identification'. The issues involved mirror those treated in the section on stochastic methods, though the matters examined tend to be more specific. Two paper are concerned with pipes, one with crack sizing using Hall sensor probes, one with multiple ECT coils, while the remaining three treat more traditional identification matters. (f) Benchmark problems (2). The importance and relevance of benchmarking the performance of algorithms is discussed in two papers which make up the final section of this book. Unlike many conference proceedings, where the quality of the format and presentation of the papers can be variable to the point of being disconcerting, this book represents the standard to which all such texts should strive. It looks like a high-quality text, it reads like a high-quality text, its diagrams, figures and tables are of a uniformly high quality and, in conclusion, it is a high-quality text on the practicalities of ENDE which will be of direct use to the ENDE specialist with a routine responsibility for crack detection. The editors are to be congratulated on the care with which these ENDE proceedings have been compiled.