Surface roughness 78-80 average values obtained from

The output of an electrical profilometer is plotted as shown in schematic form in Figure 4.5, and in actual form in Figure 4.6. A quantitative interpretation of surface roughness can be obtained from this plot in one of two ways by the rms value and by the arithmetic average. 

All substrates prepared according to our new procedure yielded the same roughness value of 2.4 0.1 A, which is also the value determined on the Ca-segregated surfaces. Because the relaxation and rumpling are both very small, slightly different values were found on the different substrates. The average values of p = (-0.56 0.35) %, and e = (1.07 0.5) % are thus given, with the error bar estimated from the uncertainties of each fit, and from the different values obtained. 

Cox et al. [101] used several kinds of enhanced tubes to improve the performance of horizontal-tube multiple-effect plants for saline water conversion. Overall heat transfer coefficients (forced convection condensation inside and spray-film evaporation outside) were reported for tubes internally enhanced with circumferential V grooves (35 percent maximum increase in U) and protuberances produced by spiral indenting from the outside (4 percent increase). No increases were obtained with a knurled surface. Prince [102] obtained a 200 percent increase in U with internal circumferential ribs however, the outside (spray-film evaporation) was also enhanced. Luu and Bergles [15] reported data for enhanced condensation of R-113 in tubes with helical repeated-rib internal roughness. Average coefficients were increased 80 percent above smooth-tube values. Coefficients with deep spirally fluted tubes (envelope diameter basis) were increased by 50 percent. 

The experimental values obtained for the average force of adhesion of longitudinally positioned particles are lower than the calculated values by a factor of 2-5 for particles with a transverse position with respect to the surface asperities, the experimental values are 5-10 times the calculated values. This means that the actual positions of the particles relative to the surface asperities do vary from longitudinal (Fig. V.9.B) to transverse (see Fig. V.9. A) these two positions may be regarded as the extreme positions of cylindrical particles on a rough surface. These positions correspond to minimum and maximum forces of adhesion the actual adhesive force will be greater than or equal to the minimum force, and less than or equal to the maximum force of adhesion. 

For surfaces with isotropic roughness characteristics, the PSD(f, fp can be simplified to a 2D-isotropic PSD by transforming into polar coordinates and averaging over all polar angles. By integration of the PSD, the root mean square roughness R is obtained. The R is the standard deviation of the surface topography data from the mean value. 

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