Square mesh

FIG. 6-16 Screen discharge coefficients, plain square-mesh screens. Couttesy ofE. I. du Pont de Nemours [Pg.646]

Square-mesh cloth is the conventional type of screen cloth, but there are many types of cloth with an oblong weave. This latter construction provides greater open area and capacity and in addition makes it possible to use stronger wire for the same size of screen opening and for the same percentage of open area. 

As shown in Figure 5, a uniform velocity is imposed on a square mesh in a direction skewed to the coordinate axes, and two different temperatures are imposed along the lefthand and bottom boundaries. Normalized temperatures are used as shown, and the lower-left-hand... 

Aggregates are categorized as elongated when they possess a length which exceeds 1.8 times their nominal size (largest dimension). From a given sized square mesh fraction of... 

Fig. 5.17 The binding energy per atom U as a function of the coordination number for aluminium. The crosses correspond to LDA predictions, whereas the curve is a least-squares fit of the form of eqn (5.72). The lattice types considered are the linear chain ( = 2), graphite ( = 3), diamond ( = 4), two-dimensional square mesh ( = 4), square bilayer ( = 5), simple cubic (x = 6), triangular mesh (x - 6), vacancy lattice (x — 8) and face centred cubic (x = 12). (After Heine eta/. (1991).)...

Eight potatoes of uniform size ( 50-mm square-mesh grading)... 

The discharge coefficient for the screen C with aperture D, is given as a function of screen Reynolds number Re = Ds(Wa)p/p in Fig. 6-16 for plain square-mesh screens, a = 0.14 to 0.79. This curve fits most of the data within 20 percent. In the laminar flow region, Re < 20, the discharge coefficient can be computed from... 

Grootenhuis (Proc. Inst. Mech. Eng. [London], A168, 837—846 [1954]) presents data which indicate that for a series of screens, the total pressure drop equals the number of screens times the pressure drop for one screen, and is not affected by the spacing between screens or their orientation with respect to one another, and presents a correlation for frictional losses across plain square-mesh screens and sintered gauzes. Armour and Cannon (AIChE J., 14,415-420 [1968]) give a correlation based on a packed bed model for plain, twill, and dutch weaves. For losses through monofilament fabrics see Pedersen (Filtr. Sep., 11, 586-589 [1975]). For screens Inclined at an angle 0, use the normal velocity component V ... 

Substrate surface structure exerts a controlling influence upon monolayer electrodeposition, as can be seen by comparing deposition of Ag at I2-pretreated Pt(lll) and Pt(100), all else being equal [41,45] (Fig. 21). The UPD process at Pt(100)(v/2 x x/8)i 45°-I took place in two stages, rather than three, and the electrodeposit structures were related to the square mesh of the Pt(100) substrate in contrast to the hexagonal structures observed at Pt(lll). 

The annealed alloy (111) oxide films yielded distinctive LEED patterns summarized in Fig. 24. Integral index beams, Type 1 in Fig. 24, were not seen when the oxide film was present, demonstrating that the film was continuous and was thicker than a few atomic layers. Thicknesses of about 2 A were typical. Beams were produced by the oxide film, indicative of a hexagonal superlattice mesh having a lattice constant of about 4.9 A and rotated 30° with respect to the mesh of the clean alloy surface (Type 4 of Fig. 24). These are the correct dimensions for the (001) plane of Cr203 in which the oxygen-oxygen vectors are parallel to the interatomic vectors of the alloy. Beams of Type 2 were also present, which were indicative of a square mesh these... 

X-ray investigation has, however, furnished for I3, and especially for I5, structures which deviate appreciably from this. I3" is indeed linear but the asymmetry which was found (I—1 2.82 and 3.10 A) now appears real, in view of the results obtained with N(CH3)4I513. Here the iodine atoms lie on a net with almost square meshes (angle 94°) and an L-shaped ion I5 can be distinguished, formed from an 1 ion at the corner with two 12 molecules at 3.15 A (I—1 2.93 A). The bonding can be regarded as a consequence of resonance between... 

The sieve diameter, for square mesh sieves, is the length of the minimum square aperture through which the particles can pass, though this definition needs modification for sieves which do not have square apertures. 

In finite difference analysis, usually a square mesh is used for simplicity (except when the magnitudes of temperature gradients in the x- and y-directions are very different), and thus Ax and Ay are taken to be the. same. Then Ax - Ay - /, and the relation above simplifies to... 

Taking a square mesh (Ax = Ay = /) and dividing each term by k gives after simplifying. 

Figure 1.12 A square mesh surface, which is two-p>etiodic.

Two-periodic surfaces deserve some comment. The most interesting examples of these surfaces can be visualised as confined between two parallel bounding planes, with a regular network of pores joining the two parallel sheets. We call these surfaces "mesh surfaces", due to their characteristic two-dimensional porous network, which resembles a mesh. A square mesh surface is shown in Fig. 1.12. The mean curvature of these surfaces can be... 

Fig. 4.10 Some square "mesh" surfaces, of differing (nonzero) mean curvature. Like IPMS, these siiHaces are hyperbolic, however, they are cottfined between parallel planes and form two-dimensioiud tunnel networks on one side only of the surface.

An intermediate phase of tetragonal syiiunetry - the T phase - has also been detected in a number of systems. A rod structure related to a square mesh surface was foimd to agree well with X-ray and NMR data on a perfluorinated surfactant-water mixture forming the T phase [22], [34]. These examples demonstrate that surfactant or lipid monolayers lining mesh surfaces as well and bilayers wrapped onto three-periodic minimal surfaces (IPMS) are indeed found in these self-assembled systems. 

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