Roughness parameters

Using a least-squares fit program, the copper film thickness D and the thickness of the Cu20 film, Ad, densities pn and a (roughness) parameters can be derived from the data. 

The roughness parameters of the various interfaces were also obtained from the model showing that the roughness of the Cu/Cu20 and Cu20/ solution interfaces were little changed during the experiment. 

The effects of small-scale surface irregularities on the boundary layer transfer processes are usually incoiporated only through the surface roughness parameter zo- The range of variation of Zo over different land... 

The small-eddy model applies, if the nondimensional roughness parameter d fulfills ... 

If the roughness parameter d increases beyond 136, the turbulent eddies become larger and begin to feel the limited vertical extension of the water column. As a result, the exponent n in Eq. 1 steadily increases until it reaches a new constant value at 1/2. At this point the eddies have reached the full depth of the river and are thus able to transport water fast between surface and bottom. This is the situation described by the large-eddy model of O Connor and Dobbins (1958). We formulate it in the general form of Eq. 1 ... 

In order to decide which model is relevant for the different river sections, we first calculate the roughness parameters cf (Eq. 20-36) and the element Froude Numbers FE(Eq. 20-37). 

To calculate vPCE a/w we note that for both discharge regimes the nondimensional roughness parameter d (Eq. 20-36) is larger than 136. Thus, we use the large-eddy model (Eq. 20-35) ... 

Table 1 Arrhenius, kinetic, and surface roughness parameters of 1,3 butadiene hydrogenation over Pd/Si02 thin film catalyst. ( ref 16, T=3Q0K, Ph2 = 0.7 kPa and Pc4H6 = 0.2 kPa) / denotes the surface-roughness-to-scan-area ratio.

In Fig. 6, experimentally determined roughness parameters are compared with the calculated roughness. It can be clearly seen that the height roughness (root mean... 

An optimum surface finish of 0.5 /vm c.I.a. is recommended for the substrate for a bonded film. The optimum roughness for a counterface for forming an effective transfer film has not been as well established, but if a similar surface finish is assumed, then the combined roughness parameter will be 0.7 m c.I.a. Under normal circumstances a typical bonded film will have a thickness of between 5 and 10//m, so initially at least there is no risk of asperity penetration. 

If design considerations require it, a much thinner bonded film could be used, or a soft film could be burnished down to much reduced thickness. Under those circumstances it would be possible to use a smoother substrate, but coating performance deteriorates badly if the surface is too smooth, and a miminum acceptable surface roughness would probably be about 0.2 yt/m c.I.a., giving a combined roughness parameter of about 0.3 fjm. It seems probable that in such a case an initial, or a fully-burnished, coating thickness of 1 to 2/>m would give a useful life before any serious problem of asperity penetration arises. 

Module wiA correclitm of urban roughness parameters, displacement height, anthropogenic and storage flux, albedo... 

By AFM analysis, it was shown that the modifications of the surface aspect can be characterized as a function of the irradiation time using the roughness parameters. A correlation between the modifications of the surface and the modifications of the chemical structure of the macromolecules resulting from irradiation showed that the degradation of the surface depends essentially on the decomposition of the hydroperoxides. 

Non-contact laser profilometry has been used to obtain roughness parameters and surface fractal dimension (Ds) of erythromycin acistrate tablets It was expected that tablet surface fractal dimension (Ds) will depend on the compression force used for tabletting. However, tablet surface fractal dimension was found independent of the compression force ranging from 4 to 22 kN. Instead, a surface roughness parameter Rp, which is the maximum distance between the highest point and the average height of the surface profile, indicated the variation of tablet friability as a function of compression force (Fig. 7). 

Fig. 7 Variation of roughness parameter, Rp, and tablet friability with respect to compression force. (From Ref. ()...

F.W. Hyde, M. Alberg and K. Smith, J. Ind. MicrobioL BiotechnoL 19 (1997) 142 SD, surface roughness analysis through AFM surface roughness parameter (algebraic average) = 16.19 nm. 

C.W. Extrand, Y. Kumagai, J. Colloid Interface Set 170 (1995) 515 TP, average surface roughness, surface roughness parameter, determined by AFM, 207 nm, all polymers wiped with methanol before use, other liquid = ethylene glycol. 

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