Considere-construction

The distance between the structure and fixed impressed current anodes is an important factor. The number of anodes has to be small so the anodes need to be relatively large, which will result in too negative a potential if the distance is not sufficiently great. A minimum distance of 1.5 m is prescribed [1-3], but this involves considerable construction effort due to the effects of heavy seas. Besides the so-called restriction on impressed current installations, there is the requirement that the corrosion protection be switched off when diving work is being carried out [14]. This regulation is not justifiable. Work on the underwater region of production platforms takes place continuously, as far as the weather allows if the protection must be switched off each time, the impressed current protection becomes very limited. 

After a considerable construction time the olfactometers became available for use. With these olfactometers and a recently created sniffing room at the IMAG premises, the poultry house odour research was repeated with a panel of eight observers. The necessary diluting air was obtained from a rotary vane compressor. Filtration of the compressed air was applied. The experimental procedures made it possible to use all panel members at the time. As a result, two experimenters were able to complete four odour measurements per day. 

FIG. 13.68 Intrinsic and extrinsic yield points and the Considere construction. 

Yield and necking phenomena can be envisioned usefully with the Considere construction shown in Fig. 11-21. Here the initial conditions are initial gauge length and cross-sectional area /, and /(, respectively and the conditions at any instant in the tensile deformation arc length / and cross-sectional area A, when the force applied is F. The true stress, a, defined as the force divided by the corresponding... 

Equation (14.7) corresponds to the slope of the tangent to the curve cr, vs. e drawn from the point e = -1 or X, = 0. Figure 14.7 shows the true stress versus nominal strain curves for polymer samples A and B. Curves B] and B2 are compatible with curve B of Figure 14.6. The so-called Considere construction, Eq. (14.7), is satisfied with the tangent to the curves drawn from E = — 1. The tangential point corresponds to the maximum observed in the curve vs. and therefore with the maximum load that the specimen can support. In practice, the Considere construction is used as a criterion to decide when a polymer will form an unstable neck or form a neck accompanied by cold drawing. 

Figure 14.7 Considere construction for tensile strain. The maximum and minimum values of a in Figure 14.6 are given by the tangents to the curve of true stress ct, from 8 = -1. Polymer A forms an unstable neck polymers Bj and B2 form stable necks.

This way of considerations constructs the TM s infinite cycle from the programmer s point of view, Self-Observation in an information point of view and a stationary statusfrom the thermodynamics point of view. 

Besides concrete quality, a minimum value of the concrete cover also has to be specified. Eurocode 2 [3] fixes minimum values ranging from 10 mm for a dry environment up to 55 mm for prestressing steel in chloride-bearing environments, as shown in Table 11.5. It should be kept in mind that these values are minimum values that should be increased to obtain nominal values by 10 mm, to also take into consideration construction variability. Besides the protection of steel to corrosion, further requirements of minimum cover depth are fixed to ensure adequate transmission of mechanical forces and fire resistance. 

The mechanism of yielding - cold drawing and the Considere construction... 

Rg. 8.4 The Considere construction. Possible forms of true-stress-strain curves (upper curves), the tangents drawn to them from the point e = -1 on the strain axis and the corresponding nominal-stress-strain curves. The curves are schematic for clarity in showing the construction for real polymers the initial part of the curve would generally be much steeper and the maximum, when it occurs, is generally at a much lower value of strain than that shown. See example 8.1 for a more realistic version of the curves in (c). 

LMC used for FR cooling motivates considerably constructional and thermal scheme of the RI, technical and economical characteristics of the NPP. 

Fig. 10.1 A schematic representation of a Considere construction. At a strain of for which dr/dfi = r, stability is lost and necking can begin. At a strain of for which dr/de = r occurs again, stability is regained and steady-state cold drawing starts.

In terms of the Considere construction, the criterion for a material to neck and cold draw is indicated by the ability to draw a second tangent to the true stress-strain curve from the point = — 1 (Fig. 4). Another important aspect of yielding is that, while there is a clear drop in the engineering stress at (or near)... 

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