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Introduction Numerous devices are available for measuring the thickness of coatings. Unfortunately most prospective users are not instrument specialists and often experience difficulty in selecting the best device for the application. Due to lack of knowledge or time, moreover, he is often placed in the difficult position of being able to purchase only in order to eliminate an immediate problem and therefore is not able to fully assess future or continuing needs in parallel to this immediate and urgent problem.

Rohrback Cosasco Systems have gained a high reputation in the field of corrosion monitoring. In this article we examine two areas of its activities, plus some examples of instruments and equipment available from the company.

Aircraft flight pressurization/depressurization cycling causes the skin to inflate and deflate, stressing it around the rivets that fasten it to the airframe. The resulting strain, exacerbated by corrosion, drives the growth of initially microscopic cracks. To avoid catastrophe, aircraft are inspected periodically for cracks and corrosion. The inspection technology employed is ∼90 percent naked‐eye vision. We have developed and demonstrated robotic deployment of both remote enhanced 3D‐stereoscopic video instrumentation for visual inspection and remote eddy current probes for instrumented inspection. This article describes the aircraft skin inspection application, how robotic deployment may alleviate human performance problems and workplace hazards during inspection, practical robotic deployment systems, their instrumentation packages, and our progress toward developing image enhancement and understanding techniques that could help aircraft inspectors to find cracks, corrosion, and other visually detectable damage.

AN ancient fable tells of strong brothers destined to great things. But one lay quietly, in his youth, applying goose grease to his muscles while the others disported among themselves in contest of strength. When the day of trial came it was the lone one, Atlas, who took the weight of the world upon his shoulders. The Greeks were neither fools nor strangers to work study.

Previous articles in this series have described some of the techniques that are used to characterise paint film properties. In many instances results from such tests are used predictively, that is they yield information on the likely performance of the coating during service. It is however, widely accepted that the most accurate way of determing performance is to actually subject the coating‐substrate combination to the service conditions it will meet in practice, or a close approximation to them. Suitability can then be assessed by periodic inspection and/or by taking measurements of some appropriate parameter which might be expected to change with time. A great many techniques have been developed and refined over the years that are intended to replicate service environments in some simplified and reproducible way; an indication of the range of test methods that can be employed to this end can be seen in a recent article by El‐Sawy. Many of these techniques are suitable for the laboratory and range from simple immersion tests in appropriate solutions through to exposure testing in controlled environment cabinets. Because of the problems of interpreting the results from laboratory simulation testing though, exposure of test panels in the natural environment is also widely practiced. This, the last article in this series, will consider some of the recent literature concerning environmental testing, with particular reference to techniques appropriate for assessing the weather, marine and corrosion resistance of coatings.

Design features and characteristics of conventional, modified and shielded total‐pressure probes are briefly discussed, and compared with new shielded instruments of simple construction which combine smallness of size with adequately fast response to pressure changes. Tests at air speeds up to 280 ft./sec. showed that a probe featuring a total‐traversing cylinder with single orifice inside a tubular shield will register total pressure to within 1 per cent of the dynamic pressure up to inclinations of the flow of ±28 deg., the error in the range ±22 deg. being less than 0.5 per cent. The response time of the instrument under a suddenly applied air pressure of 500 mm. W.G. was less than 60 seconds when linked to a Betz projection manometer. If the inner cylinder is replaced by a central sting, the range of insensitivity to flow inclinations is increased to ±45 deg., the error being less than 0·5 per cent of the dynamic pressure. The response time of this probe under 500 mm. W.G. air pressure was approximately 100 seconds. Still simpler versions of the instruments described are under development.

A survey is made of the instruments and methods used to measure total and static pressure and direction in three‐dimensional flow. Comparative tests in a towing tank of two designs of live‐orifice pitot‐type probe showed the advantage, within a limited range of flow inclination, of the instrument with independent static pressure orifices. Speed and angle of flow characteristics are Riven for these two probes, which differed in the shape of head.

Latest instruments from Wells‐Krautkramer A new ultrasonic probe has been introduced by Wells‐Krautkramer Ltd., Blackhorse Road, Letchworth, Herts SG6 1HF, which halves the minimum measuring thickness of their DM2 instrument from 1.2mm (0.048in.) to 0.6mm (0.024in.) in steel. Used with a flaw detector, thicknesses in steel down to 0.3mm (0.012in.) can be measured. The performance of this probe is claimed to be better than any other corrosion thickness gauge probe currently available, and being small in size and easy to use, is particularly suited to on‐site measurement.

The paper aims to discuss design, fabrication, testing and simulation of a novel tactile probe used for measuring the stiffness of biological soft tissues/materials with a view to medical and surgical applications.

Both finite element modeling and experimental approach were used in this research. The novel tactile probe capable of recording force-deformation feedback is accompanied with the tactile-status-display which is a custom-designed user-friendly interface. This system can evaluate the stiffness in each part of force-deformation status.

The new system named novel tactile probe was fabricated, and the results on artificial materials (with different stiffnesses) and the sheep kidney (containing a hard object) were reported. Recording different stiffnesses, detecting hard object embedded in soft tissue and predicting the exact location of it are the main results that have been extracted through the diagrams obtained by the novel tactile probe system.

The designed and fabricated system can be modified and miniaturized to be used during different minimally invasive surgeries in the future.

The most distinguishing feature of this novel tactile probe is its applicability during different laparoscopic surgeries, so the in vivo data can be obtained.

For the first time, a tactile probe has been designed and tested in the form of laparoscopic instrument which upgrades the efficiency of available laparoscopic instruments. Also, the novel tactile probe can be used in both in vivo and in vitro experimental setups for measuring the stiffness of sensed objects.

When in 1947 Elcometer launched the 101 it was the first hand held coating thickness gauge, the first of thousands; the launch was followed by a tidal wave of competitors, it is to the credit of this very British company that they are still, forty years later, one of the market leaders; it is even more remarkable that the original instrument, with only a few cosmetic changes is still liked and bought by their customers. In the intervening years many new techniques for coating thickness measurement have emerged, some simple, many complicated and the market has divided into fairly clearly defined sectors with unit prices as diverse as the intrinsic value of the end products. As yet no one instrument meets all needs.