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Gives introductory remarks about chapter 1 of this group of 31 papers, from ISEF 1999 Proceedings, in the methodologies for field analysis, in the electromagnetic community. Observes that computer package implementation theory contributes to clarification. Discusses the areas covered by some of the papers ‐ such as artificial intelligence using fuzzy logic. Includes applications such as permanent magnets and looks at eddy current problems. States the finite element method is currently the most popular method used for field computation. Closes by pointing out the amalgam of topics.

Every employer, unless he or she has no pool of applicants or potential applicants to choose from, engages in hiring choices. While the hiring process may vary, both from one employer to another and from one job to another, some form of screening occurs. In recent years, students of management have noted the proliferation of screening practices in the hiring process, especially in bringing new technologies such as medical and drug testing procedures. Testing and other screening practices, while wide‐ranging both with respect to their ends and means, have raised consistent patterns of concern among job‐seekers, public policy makers and managers themselves. In this monograph a variety of methods of screening and issues of public policy raised by screening procedures are discussed. An overview of United States law regulating the screening process is provided, together with future directions in the area of screening in the US.

Examines accelerated methods for the corrosion testing of materials, coatings and surface treatments used in the aerospace and defence industries. The drawbacks with some current accelerated corrosion tests are examined, particularly the problems experienced with neutral salt spray tests. Specific examples are given which identify the acute discrepancy between salt spray and marine exposure in the corrosion testing of metallic coatings on steels. Examines some recent advances in corrosion testing of aerospace materials, pre‐treatments and organic coatings, and outlines some preliminary research conducted at DERA Farnborough in developing more accurate test methods.

Modern electronics is characterised by the increasing level of integration in printed circuit board (PCB) technology and the reduced insulation spacing between adjacent conductors. Surface insulation resistance (SIR) measurement has often been used alone to determine the cleanliness of PCB assembly; however, when proper SIR measurement is used in conjunction with surface leakage current (SLC) measurement, the result can reveal the dynamic nature of surface electrochemical migration (SECM) processes at the microscopic level, and the effect of such processes on product quality and reliability. This paper presents a newly developed measurement methodology, which measures SLC per square unit area at a sampling rate that is orders of magnitude higher than that of conventional SIR measurement methods. It is aimed to capture the transient surge of SLC which is detrimental to the functionality of product.

Eddy current testing is a general term for the inspection of conductive materials using an induced electro‐magnetic field. The flow of this field is affected by the presence of defects within the material and the charges are detected by suitable instruments which reveal their location and nature. This type of testing does not alter the material in any way therefore giving rise to the term non‐destructive testing.

Eddy current testing (ECT) is widely used in the non-destructive evaluation of materials in different industries. In this paper, ECT has been used to detect the presence of cracks in boiler tubes. The most important feature in ECT is the way in which the eddy currents are induced and detected in the sample. The authors have tried to design a new sensor that is effective in detecting cracks in boiler tubes. The purpose of this paper is to study the response of this sensor to cracks of different depths and dimensions.

The designed eddy current sensor is equipped with an exciting and a sensing coil. An alternating current is passed through the exciting coil thus producing eddy currents. The sensing coil scans the outer surface of the boiler tube and looks for abrupt changes in output signals resulting from sharp discontinuities in structure.

The sensor designed can detect the position of the crack. The presence of crack is indicated by a reduction in the induced voltage in the sensing coil. The sensor is also used for characterisation of the cracks, and can distinguish between cracks of varying shape, size and depth. The sensitivity of the sensing coil to cracks is dependent on operating conditions, such as frequency and voltage of the excitation signal.

The new sensor designed is used to detect defects in boiler tubes in power plants. However, the operating conditions, such as excitation frequency and amplitude will vary with composition of the boiler tubes.

The new eddy current sensor designed for crack detection is an E-shaped core coil. The shape of the coil provides a high permeability path to the magnetic field lines, thus reducing the loss of the field produced. This helps in improving the sensitivity of the coil, and makes the detection system effective in detecting hairline cracks.

There are several techniques for producing a magnetic field, one of which is the magnetic flow technique.

The eddy current method of non‐destructive testing uses an alternating current excitation to induce secondary currents in a specimen under test. Flaws within the specimen affect the induced currents, causing changes in the impedance of a test coil. In this paper we present a method for obtaining a solution of inverse problems, in which the parameters of defects are unknown and the excitation function and the eddy current system response are given. The method is based on the use of artificial neural networks, which are trained using measurements. Illustrative examples are given.

Accelerated life tests on avionic PWAs (printed wiring assemblies) showed no relationship between measles and premature electrical failures. For the study, test samples with measles and crazes bridging up to 100% of the distance between adjacent conductors were exposed to different combinations of thermal cycling, humidity and DC voltage bias. The exposures were designed to accelerate electrochemical failure processes such as CAF (conductive anodicfilament) growth between conductors. The study was conducted in two phases. In Phase I, measled and non‐measled sites on six modules (including both epoxy/fibreglass and polyimide/fibreglass PWBs were tested. Bias voltages of 10,100 and 200 volts DC were applied during 10‐day tests and currents were monitored to detect the appearance of electrical shorts between individual conductor pads. Microscopic examination revealed no detectable change in the size or appearance of the measles during the exposure. Currents measured during the exposure were generally in the nanoamp range. They were similar for both measled and control sites and all sites passed the minimum criterion for insulation resistance of 500 megohms. Two of the modules were then tested at 320 and 500 volts. Short circuit failures were produced, but metallographic examination revealed them to be artifacts associated with reworked solder pads. There was no correlation between the incidence of failure and the presence of measles. In Phase II, test sites on two new polyimide/glass modules were exposed at voltages up to 500 V for a series of 5‐ or 10‐day periods, interspersed with precise measurements of insulation resistance under ambient conditions. Although no failures were produced in these tests, the ambient measurements showed some loss in insulation resistance with exposure time. Further testing revealed that the loss of insulation resistance was reversible and was unrelated to the presence or absence of measles.

The paper seeks to propose a specific approach based on Dynamic Analysis and Chaos Theory aiming to emphasize the differences into the eddy current signals obtained by related non‐destructive tests, when the inspected specimens have flaws with different shapes.

Non‐linear eddy current analysis is very useful for flaw detection in many in‐service inspections. State‐of‐the‐art technologies allow one to define position and depth of defects, but the shape identification is still an open problem. In this paper, experimental data have been subjected to a dynamical analysis in order to relate the trend of eddy current signals to the shape of analyzed defect.

In particular, a dynamical reconstruction by means of recurrence plots (RPs) has been carried out in order to detect analogies and differentiations between different eddy current signals. Moreover, cross‐correlation between RPs of a reference benchmark and testing eddy current signals has been applied in order to emphasize a different dynamical behaviour and to detect a particular flaw's shape. In this way, a real‐time algorithm for defect shape classification has been performed.

Proposed approach is very interesting, and it is an innovation in non‐destructive testing procedures. In fact, the shape identification of a flaw is still an open challenge. The proposed approach, based on dynamic analysis, gives the key to solve this particular ill‐posed problem, by introducing a relation between the eddy current measurements and the shape of defect existing in the inspected specimen. Very interesting preliminary results have been obtained.