Errors in relative

Although the error in the absolute spin concentration will vary from one type of study to another, a reasonable value is about 20%. The error in relative concentrations between samples having identical line shapes is probably closer to 2%. In the latter case the relative amplitude of the derivative spectrum may be used hence, the troublesome double integration may be avoided. 

Table 6-12 Mean Absolute Errors in Relative Energies of Structural Isomers... 

Some forms of disorder common in adsorbed layers are islands of clustered adsorbates leaving patches of bare substrate domains in which different patches of the overlayer have identical structure but do not match at their junction because of an error in registry, i.e., an error in relative positioning parallel to the surface periodicity errors, in which individual adsorbates do not fit in the periodic arrangement of the surrounding... 

The J=2-l, v=0 emissions of ZBSiO,Z9SiO, and 30SiO from Villi Oph, NML Tau, and X Cyg were observed with the Nobeyama 45-m telescope in Jaunuary 19871 At 86 GHz, the half-power beamwidth was 20 , and the aperture efficiency 0.37. The three lines were simultaneously observed using two receivers with instantaneous bandwidths of 2 GHz and 0.5 GHz to reduce errors in relative intensities due to pointing and intensity calibration errors. The intensity scale reported here is the antenna temperature T, corrected for atmospheric and ohmic losses. 

Figure 14-42 shows that errors in relative volatility are a problem only at low relative volatilities for a > 1.5 to 2.0, VLE errors have negligible direct impact on tray efficiency. 

FIG. 14-42 Direct effect of errors in relative volatility on error in tray efficiency. (From H. Z. Kister, Distillation Design, copyright 1992 by McGraw-Hill reprinted by permission.)... 

The x-y diagram should be examined for pinching both for design conditions and for some deviations (variation in feed temperature, feed composition, errors in relative volatility, etc,), For deviations, a simple construction (e,g, a q-line with a slightly different slope) on the design conditions x-y diagram is usually sufficient. When the threat of a pinched region is detected, a more detailed analysis (e.g., a computer run for the deviated conditions) is warranted. 

Errors in relative volatility are the most underrated factor that affects both tray and packing efficiency. The effects are direct when VLE errors affect separation stage requirement at a constant reflux ratio, and indirect when VLE errors affect the reflux ratio requirement (which in turn affects the stage requirement). Since higher relative volatility lowers both stage and reflux requirements (and vice versa), the direct and indirect effects complement each other and do not counteract each other. The discussion below applies to hoth tray and packed towers. 

Figure 7.9 Direct effect of errors in relative volatility on erroT in tray effidancy.

As can be seen in Table I, systematic errors in relative SCF energies favor the sp excited state. The SCF energy is also biased against the d +2 and d"+ s configurations for the last half of the transition series. To make the situation even more difficult, most atomic L,S states require several Slater determinants to express the Hartree-Fock wavefunction. 

Source Wanke et al. (2001). Average error, in relative % applies to Mars Pathfinder roeks and soils. Source Clark et al. (1982). 

Nitrogen sorption/desorption isotherms of membrane samples (carefully dried at room temperature) were obtained by Micrometries Instrument Corp., Norcross, Georgia. About 1.5g of each membrane samples was used for measurements of BET surface areas, 21 point sorption and 22 point desorption isotherms. The Instrument used was DigiSorb 2500 with fully automated control. The most significant experimental error introduced was from saturation pressure variation of about + 1.5 mm Hg (that is, about 0.2% error in relative pressure). 

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