Permit

Short-term exposure. This is the maximum concentration to which workers can be exposed for a period of up to 15 minutes continuously without suffering from (a) intolerable irritation, (b) chronic or irreversible tissue change, or (c) narcosis of sufficient degree to increase accident proneness, impair self-rescue, or materially reduce efficiency, provided that no more than four excursions per day are permitted, with at least 60 minutes between exposure periods, and provided the daily time-weighted value is not exceeded. 

The relations which permit us to express equilibria utilize the Gibbs free energy, to which we will give the symbol G and which will be called simply free energy for the rest of this chapter. This thermodynamic quantity is expressed as a function of enthalpy and entropy. This is not to be confused with the Helmholtz free energy which we will note sF (L" j (j, > )... 

The AEBBL SW ains on the PC. The software uses a menu structure, easy to use by a non expert operator. AEBIL has been designed to operate in DOS environjnent in order to enhance its real-time operation capabilities. The user-interface has been developed so as to permit a window-driven operation. 

In integrated photoelasticity it is impossible to achieve a complete reconstruction of stresses in samples by only illuminating a system of parallel planes and using equilibrium equations of the elasticity theory. Theory of the fictitious temperature field allows one to formulate a boundary-value problem which permits to determine all components of the stress tensor field in some cases. If the stress gradient in the axial direction is smooth enough, then perturbation method can be used for the solution of the inverse problem. As an example, distribution of stresses in a bow tie type fiber preforms is shown in Fig. 2 [2]. 

Automatic Methods with the help of appropriate algorithms permit the calculation of the threshold to segment ultrasonic images. It is this work, this method has been adopted. 

The variation impedance analysis must permit to characterize, to localize and getting dimensions of defects. 

The inductance variation measure with a defect long than the coil length permit to calculate the defect surface. 

The purpose of the nondestructive control consists in detecting local modifications of the material parameters which, by their presence can endanger the quality of the half-finished or finished products. The electromagnetic nondestructive control permits to render evident surface and subsurface discontinuities in the electroconductive material under test. The present tendency of this control is to pass from a qualitative evaluation (the presence or absence of the material discontinuities which give at the output of the control equipment a signal higher or at least equal to that coming from a standard discontinuity whose shape and severity has been prescribed by the product standards) to a quantitative one, which enables to locate as exactly as possible the discontinuity and to make predictions over its shape and severity. 

The eombination in a compact system of an infrared sensor and a laser as excitation source is called a photothermal camera. The surface heating is aehieved by the absorption of the focused beam of a laser. This localisation of the heating permits a three-dimensional heat diffusion in the sample to be examined. The infrared (IR) emission of the surface in the neighbourhood of the heating spot is measured by an infrared detector. A full surface inspection is possible through a video scanning of the excitation and detection spots on the piece to test (figure 1). 

The principle of the photothermal camera is known for decades (see ref. 1) but did not offer sufficient performances to permit this instrument to find an industrial issue. The main reason of that lack of success Is the poor efficiency of the previous configurations when applied on industrial products (figures 3, 4, 5) ... 

A new design of an old concept of thermal surface inspection permits the photothermal camera to be considered as an interesting alternative to NDT methods like penetrant or magnetic testing, particularly when the testing has to be made in a remote or automatic way. 

A major advantage of radioscopy is the flexible inspection perspective that allows an optimum adjustment of beam direction and geometrical magnification to the inspection task at hand it also permits in-motion testing. 

This study has permitted the definition of the minimum requirements to be introduced in RCCM code in order to select properly the dye penetrant product family. 

The removing penetrant test is performed on sanded and cracked reference block defined in standard NFA 09.520 ( see figure 1, annex 1) and permits the evaluation of the washability of penetrants. 

The removal tests show important variations between products which do not influence the results because all penetrant can be washed easily. Resistance test to over washing give an evaluation of the hanging up of the product on the pieee and because the washing is an operation realized by an operator for our applications, they permit to have a good idea on the influency of this operation on the end of the test one operator who washes too much a penetrant increases the probability to make the indications desappear. 

This study permitted to compare products family, on the base of normalized tests all parameters maintained constant during tests. 

These tests permited us to define minimum requirements to obtain for our fabrication applications, and to introduce in our code minimum requirements and method to verify them. 

The pressure equipment directive was adopted by the European Parliament and the European Council in May 1997. It harmonises the national laws of the 15 Member States of the European Union relating to equipment subject to the pressure risk. That directive is one of the series of technical harmonisation directives such as for machinery, medical devices, simple pressure vessels, gas appliances and so on, which were foreseen by the Communities programme for the elimination of technical barriers to trade. It therefore aims to ensure the free placing on the market and putting into service of the equipment concerned within the European Union and the European Economic Area. At the same time it permits a flexible regulatory environment, allowing European industry to develop new techniques increasing thereby its international competitiveness. 

A section view at defect height permits a detailed analysis. Printouts of the front panels are made by clicking. 

The results of corrosion surveys are received by the Surveyor in an agreed format using Forms TMl - TM8, preferably with the LR software freely issued to the approved firms. The report will highlight any areas where corrosion has gone beyond the permitted maximum diminution, which may be as low as 15% of the nominal thickness for a single item, and will also identify areas of "substantial corrosion T.e., any in excess of 75% of the permitted maximum. Corrosion in excess of that permitted means that the item has to be replaced. Any areas of corrosion deemed to be "substantial" are recorded for annual inspection. The Surveyor will review the completed report for verification and confirmation of the completeness of the thickness survey. 

As a general comment, it is fortunate for the study of monolayers that dissolving processes are generally slow enough to permit the relatively unperturbed study of equilib-... 

The treatment may be made more detailed by supposing that the rate-determining step is actually from species O in the OHP (at potential relative to the solution) to species R similarly located. The effect is to make fi dependent on the value of 2 and hence on any changes in the electrical double layer. This type of analysis has permitted some detailed interpretations to be made of kinetic schemes for electrode reactions and also connects that subject to the general one of this chapter. 

There are some subtleties with respect to the physicochemical meaning of the contact angle equation, and these are taken up in Section X-7. The preceding, however, serves to introduce the conventional definitions to permit discussion of the experimental observations. 

A very important but rather complex application of surface chemistry is to the separation of various types of solid particles from each other by what is known as flotation. The general method is of enormous importance to the mining industry it permits large-scale and economic processing of crushed ores whereby the desired mineral is separated from the gangue or non-mineral-containing material. Originally applied only to certain sulfide and oxide ores. 

---