Roughness values

An abrasion index in terms of kilowatthour input per pound of metal lost furnishes a useful indication. Rough values are quoted in Table 20-3. 

Rough values are given. Microstructure and composition of the material as well as temperature, composition, and flow rate of the medium can substantially influence... 

A variability risk table (as shown in Figure 2.28 for the eover support leg analysis above) is a more elfieient and traeeable way of presenting the results of the first part of the analysis. A blank variability risks results table is provided in Appendix VII. It eatalogues all the important design information, sueh as the toleranee plaeed on the eharaeteristie, the eharaeteristie dimension itself, surfaee roughness value, and then allows the praetitioner to input the results determined from the variability risks analysis, both manufaeturing and assembly. 

Figure 4.31 Failure probability (per application of load) versus safety margin for various loading roughness values (adapted from Carter, 1997)...

Different values of will result if the integral limits (i.e., band width) or modulation transfer function in the integral change. All surface characterization instruments have a band width and modulation transfer function. If rms roughness values for the same surface obtained using different instruments are to be compared, optimally the band widths and modulation transfer functions would be the same they should at least be known. In the case of isotropic surface structure, the spatial frequencies p and q are identical, and a single spatial frequency (/>) or spatial wavelength d= /p) is used to describe the lateral dimension of structure of the sample. 

In practice the friction factors are calculated either by integration of Eq. (4.51) or by reference to a Moody chart. This is based on Eq. (4.51) by using equivalent roughness values representing the sand particle roughness (see Table 4.3). 

TABLE 4.3 Equivalent Roughness Values for Various Materials... 

The surface tension of a mixture is rarely a simple function of composition. However, for hydrocarbons a rough value can be calculated by assuming a linear relationship. 

Precision of analytical methods is usually characterized semi-quantita-tively by giving a rough value of the relative standard deviation (e.g., the precision of arc-excited OES is about 20% ). 

Thus, if we were to use the same pipe material (commercial steel) for the model as in the field, we would also have to use the same diameter (48 in.). This is obviously not practical, but a smaller diameter for the model would obviously require a much smoother material in the lab (because Dm -C Df requires em drawn tubing such as copper or stainless steel, all of which have equivalent roughness values of the order of 0.00006 in. (see Table 6-1). 

Since the roughness values are only approximate, so is this value of Dm. Thus we could choose a convenient size pipe for the model with a diameter of the order of 1.6 in. (for example, from Appendix F, we see that a Schedule 40, in. pipe has a diameter of 1.61 in., which is fortuitous). 

Figure 21 Creep compliance as a function of degree of crystallinity above Tu. Numbers, on curves are rough values of the degree of crystallinity.

The partial pressures and and the rates will be found at conversions of 0, 45% and 90% and Simpsons rule will be applied for a very rough value of the integration. With the data of the table,... 

Roughness values, 15 203 Rough surfaces, mass transfer at,... 

Table II summarizes surface roughness values measured for PMMA and VMCH samples etched for 1.0 minute at 35mTorr at various power densities. Although the measured values of 80 - 105 A fall within the ranges obtained from the interferometer and transition layer theory, there is no significant variation with power density. Differences in surface roughness between pre-etched films of PMMA and VMCH are also negligible according to the stylus measurements.

Depending on the conditions, the constant 0.15 varied from to Figure 5 presents surface roughness values for a variety of land use categories compiled primarily from the reviews of Myrup and Ranzieri (1976) and Hodgin (1980) and presented by McRae et al. (1982). The precision implied by some entries on the figure is deceptive because there is considerable scatter in many of the underlying experimental data. 

Evaluation of the vapor pressure method with normal alkanes disclosed favorable agreement of estimates and data for small, intermediate and large size molecules. Evaluation with other compound types was not performed. If the lower explosive limit (LEL) used in the calculations is estimated, the estimates for flash point should be considered as rough values. 

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