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Relative value

Equation (5.8) tends to predict vapor loads slightly higher than those predicted by the full multicomponent form of the Underwood equation. The important thing, however, is not the absolute value but the relative values of the alternative sequences. Porter and Momoh have demonstrated that the rank order of total vapor load follows the rank order of total cost. [Pg.137]

In all these methods, the accuracy depends on the sulfur concentration in relative value, the error is estimated to be about 0.1%. [Pg.32]

Finally, in the case of solids, there is the difficulty that surface atoms and molecules differ in their properties from one location to another. The discussion in Section VII-4 made clear the variety of surface heterogeneities possible in the case of a solid. Those measurements that depend on the state of surface atoms or molecules will generally be influenced differently by such heterogeneities. Different methods of measuring surface area will thus often not only give different absolute values, but may also give different relative values for a series of solids. [Pg.574]

The magnitudes of e i =1, )contam the Fresnel factors from equation Bl.5,34. equation B1,5,35 and equation B 1,5.36. which depend on the incident, reflected and polarization angles. Experimentally, one approach is to fix the input polarization and adjust the analyser to obtain a null in the SFl signal [ ]. By choosing distinct configurations such that the corresponding tliree equations from equation B 1.5.40 are linearly independent, the relative values of Xs lim = inferred. This method has... [Pg.1283]

From what has been said, it is clear that both physical and mathematical aspects of the limiting processes require more careful examination, and we will scare this by examining the relative values of the various diffusion coefficients and the permeability, paying particular attention to their depec dence on pore diamater and pressure. [Pg.37]

Provided that the balance is functioning correctly, the main source of error is in the weights themselves these should be calibrated by one of the standard methods so that their relative values are known, and they should be carefully cleaned with tissue paper and checked from time to time. To make the best use of the balance, weighing should be carried out by the method of swings, but for this purpose it is necessary first to determine the sensitivity of the balance. [Pg.465]

The phenomenon under consideration is complicated and the theory developed in the last section is fairly simple-involved, but not really difficult. We have successfully discovered that the transition from Newtonian to pseudoplastic behavior is governed by the product 77, or the relative values of the shear rate and the rate of molecular response. [Pg.100]

The numbers computed usiag this approach are only as good as the failure rate data for the specific equipment. Frequendy, failure rate data are difficult to acquire. For this case, the numbers computed only have relative value, that is, they are useful for determining which configuration shows iacreased reUabiUty. [Pg.477]

A low temperature of approach for the network reduces utihties but raises heat-transfer area requirements. Research has shown that for most of the pubhshed problems, utility costs are normally more important than annualized capital costs. For this reason, AI is chosen eady in the network design as part of the first tier of the solution. The temperature of approach, AI, for the network is not necessarily the same as the minimum temperature of approach, AT that should be used for individual exchangers. This difference is significant for industrial problems in which multiple shells may be necessary to exchange the heat requited for a given match (5). The economic choice for AT depends on whether the process environment is heater- or refrigeration-dependent and on the shape of the composite curves, ie, whether approximately parallel or severely pinched. In cmde-oil units, the range of AI is usually 10—20°C. By definition, AT A AT. The best relative value of these temperature differences depends on the particular problem under study. [Pg.521]

Relative values for the various TBP distribution coefficients of the feed constituents are as follows ... [Pg.205]

Pattemators may comprise an array of tubes or concentric circular vessels to coUect Hquid droplets at specified axial and radial distances. Depending on the pattemator, various uniformity indexes can be defined using the accumulated relative values between the normalized flow rate over a certain sector or circular region and a reference value that represents a perfectly uniform distribution. For example, using an eight-sector pie-shaped coUector, the reference value for a perfectly uniform spray would be 12.5%. The uniformity index (28) could then be expressed as foUows, where is the normalized volume or mass flow rate percentage in each 45-degree sector. [Pg.331]

Tables 14 and 15 show historical U.S. prices for nitration- and commercial-grade toluene, respectively, from 1976 to 1995. The minimum price for the toluene used in chemicals is set by its value in unleaded gasoline, which is the principal use. The ceiling price is set by the relative values of benzene and toluene. When the value of benzene is such that the differential between benzene and toluene exceeds the cost of converting toluene to ben2ene, then the price of toluene is set by its value for the conversion to benzene. A differential of 91.00/t (ca 0.30/gal) is generally needed to make conversion of toluene to benzene economically attractive. Tables 14 and 15 show historical U.S. prices for nitration- and commercial-grade toluene, respectively, from 1976 to 1995. The minimum price for the toluene used in chemicals is set by its value in unleaded gasoline, which is the principal use. The ceiling price is set by the relative values of benzene and toluene. When the value of benzene is such that the differential between benzene and toluene exceeds the cost of converting toluene to ben2ene, then the price of toluene is set by its value for the conversion to benzene. A differential of 91.00/t (ca 0.30/gal) is generally needed to make conversion of toluene to benzene economically attractive.
The relative value of the two potentials reveals the destabdization action of salts added to the emulsion. Addition of an electrolyte to the continuous phase causes a reduction of the electric double-layer repulsion potential, whereas the van der Waals potential remains essentially unchanged. Hence, the reduced electric double-layer potential causes a corresponding reduction of the maximum in the total potential, and at a certain concentration of electrolyte the maximum barrier height is reduced to a level at which the stabdity is lost. [Pg.199]

The resonance integral of the 7r-bond between the heteroatom and carbon is another possible parameter in the treatment of heteroatomic molecules. However, for nitrogen compounds more detailed calculations have suggested that this resonance integral is similar to that for a C—C bond and moreover the relative values of the reactivity Indices at different positions are not very sensitive to change in this parameter. [Pg.5]

Since aromaticity is, at best, a relative value, the problem of the aromaticity of pyrazole, compared to other azoles, is to be found in Section 4.01.1.2, in which the authoritative review by Cook et al. (74AHC(17)255) is summarized. [Pg.208]

FIG. 14-12 Effects of reagent-concentration and reagent-conversion level upon the relative values Kca in the C02-Na0H-H 0 system. [Adapted from Eckeii et at, Ind. Eng. Chem., 59f2h 41 (1967).]... [Pg.1365]

While the carbon dioxide/caiistic test method has become accepted, one should use the results with caution. The chemical reaction masks the effect of physical absorption, and the relative values in the table may not hold for other cases, especially distillation applications where much of the resistance to mass transfer is in the gas phase. Background on this combination of physical and chemical absorption may Be found earher in the present section, under Absorption with Chemical Reaction. ... [Pg.1398]

The switch from feed to displacer changes M roots, generating M boundaries. All of these boundaries are self-sharpening, except the boundary associated with the transition from to Oti that can be self-sharpening or diffuse depending on the relative value of these... [Pg.1537]

The known models for describing retention factor in whole variable space ar e based on three-phase model and containing from three to six par ameters and variety combinations of two independent factors (micelle concentration, volume fraction of organic modifier). When the retention models are comparing or the accuracy of fitting establishing, the closeness of correlation coefficient to 1 and the sum of the squared residuals or the sum of absolute deviations and their relative values is taken into account. A number of problems ar e appear in this case ... [Pg.45]

As shown by Eq. (6) the PME is the reversible work done by the average force. It is possible to express relative values of the PME between different solute configurations X i and X2 using Eq. (6) and the reversible work theorem [4] ... [Pg.137]

Whether or not a polymer is rubbery or glass-like depends on the relative values of t and v. If t is much less than v, the orientation time, then in the time available little deformation occurs and the rubber behaves like a solid. This is the case in tests normally carried out with a material such as polystyrene at room temperature where the orientation time has a large value, much greater than the usual time scale of an experiment. On the other hand if t is much greater than there will be time for deformation and the material will be rubbery, as is normally the case with tests carried out on natural rubber at room temperature. It is, however, vital to note the dependence on the time scale of the experiment. Thus a material which shows rubbery behaviour in normal tensile tests could appear to be quite stiff if it were subjected to very high frequency vibrational stresses. [Pg.45]

The curves provide relative values for the standard enthalpy (Methylene Group)... [Pg.58]

Different portions of the standard free energy of distribution can he allotted to different parts of a molecule and, thus, their contribution to solute retention can be disclosed. In addition, from the relative values of the standard enthalpy and standard entropy of each portion or group, the nianner in which the different groups interact with the stationary phase may also be revealed. [Pg.61]

It is seen from equation (22) that there will, indeed, be a temperature at which the separation ratio of the two solutes will be independent of the solvent composition. The temperature is determined by the relative values of the standard free enthalpies of the two solutes between each solvent and the stationary phase, together with their standard free entropies. If the separation ratio is very large, there will be a considerable difference between the respective standard enthalpies and entropies of the two solutes. As a consequence, the temperature at which the separation ratio becomes independent of solvent composition may well be outside the practical chromatography range. However, if the solutes are similar in nature and are eluted with relatively small separation ratios (for example in the separation of enantiomers) then the standard enthalpies and entropies will be comparable, and the temperature/solvent-composition independence is likely be in a range that can be experimentally observed. [Pg.123]


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