Deviation, average

The spectroscopic methods, NMR and mass spectrometry for predicting cetane numbers have been established from correlations of a large number of samples. The NMR of carbon 13 or proton (see Chapter 3) can be employed. In terms of ease of operation, analysis time (15 minutes), accuracy of prediction (1.4 points average deviation from the measured number), it is... 

Values of the flux ratio n /N21 were also compared with the theoretical value (Mj/Mj ), and the average deviation of the experimental points from this value was found to be + 6.64 over the whole pressure range. 

A statistical measure of the average deviation of data from the data s mean value (s). 

Di is equal to read from Fig. 2-38 if Z > 0.27 and Di is eqiial to Di, read from Fig. 2-39 if Z < 0.27. At reduced temperatures less than 0.9, Dj can be taken as 0. The density is then c culated from Eq. (2-76). All families of organic compounds except mercaptans and carboxylic acids are predicted within an average deviation of 5 percent. 

For air-hydrocarbon systems, average deviations do not exceed 9 percent. For general nonhydrocarbon gas systems, the average deviation is about 6 percent. 

Accuracies of 3 percent average deviation are typical when using this method. 

Values for hydrocarbons other than alkynes and alkadienes can be predicted by the method of Suzuki et al. The best model includes the descriptors T, P, the parachor, the molecular surface area (which can be approximated by the van der Waals area), and the zero-order connectivity index. Excluding alkynes and alkadienes, a studv for 58 alkanes, aromatics, and cycloalkanes showed an average deviation from experimental values of about 30 K. 

Lee-Thodos presented a generahzed treatment of self-diffusivity for gases (and liquids). These correlations have been tested for more than 500 data points each. The average deviation of the first is 0.51 percent, and that of the second is 17.2 percent. 8 = PyVr, s/cm and where G = (X - X)/(X - 1), X = p,/T h and X = p /T evaluated at the solid melting point. 

Sun-Chen examined tracer diffusion data of aromatic solutes in alcohols up to the supercritical range and found their data correlated with average deviations of 5 percent and a maximum deviation of 17 percent for their rather hmited set of data. 

Catchpole-Kinp examined binaiy diffusion data of near-critical fluids in the reduced density range of 1 to 2.5 and found that their data correlated with average deviations of 10 percent and a maximum deviation of 60 percent. They observed two classes of behavior. For the first, no correction fac tor was required R = 1). That class was comprised of alcohols as solvents with aromatic or ahphatic solutes, or carbon dioxide as a solvent with ahphatics except ketones as solutes, or... 

T] Check of 132 data points showed average deviation 14.6% from theory. Johnstone and Pig-ford [Ref. 105] correlation (5-22-D) has exponent on Nue rounded to 0.8. Assume gauze packing is completely wet. Thus, = a, to calculate Hq and Same approach may be used generally applicable to sheet-metal packings, but they will not be completely wet and need to estimate transfer area. 

For banks of in-line tubes,/for isothermal flow is obtained from Fig. 6-43. Average deviation from available data is on the order of 15 percent. For tube spacings greater than 3D(, the charts of Gram, Mackey, and Monroe (Trans. ASME, 80, 25—35 [1958]) can be used. As an approximation, the pressure drop can be taken as 0.32 velocity head (based on V ) per row of tubes (Lapple, et al.. Fluid and Paiiicle Mechanics, University of Delaware, Newark, 1954). 

Data quality assessment requirements are related to precision and accuracy. Precision control limits are established, i.e., 4-10% of span value, as calculated from Eq. (15-1). The actual results of the may be used to calculate an average deviation (Eq. 15-3) ... 

Data Source. The correlation constants were determined from a least-squares fit of data from the literature.-- - In most cases, average deviations between calculated and reported data were less than 0.6kjoules/g-mol. 

Referenced to 806 data points for binary systems. Equation 8-70A gives absolute deviation of 13.2%, which is about as accurate, or perhaps more so, than other efficiency equations. Equation 8-70B uses the same data and has an absolute average deviation of 10.6%. See Example 8-13 for identification of dimensionless groups. 

This is the drop occurring when the vapor passes through the holes on the tray. The relation below [25] correlates the data of several of the m or investigators with a maximum deviation of less than 20% and an average deviation of 10%. 

Relations expressing the fractional voids in a ring packed bed are useful in estimated the e values for a/e determinations [47]. The average deviation is 2.6%. 

Correlation Average Deviation Absolute Average Deviation Bias Maximum Deviation... 

Deviation Variation from the a specified dimension or design requirement, usually defining the upper and lower limits. The mean deviation (MD) is the average deviation of a series of numbers from their mean. In averaging the deviations, no account is taken of signs, and all deviations whether plus or minus, are treated as positive. The MD is also called the mean absolute deviation (MAD) or average deviation (AD). 

The group contributions are given in Table 6. The group values were used to predict the enthalpy of formation of every compound in Tables 1-5 (except for those containing nitrogen). The estimated values were then compared to the experimental values. The agreement was usually to within about 10 kJ mol f The worst cases were for butyl methyl sulfone, t-butyl methyl sulfone and l-methyl-4-(l-methylethenylsulfonyl)benzene, for which the deviations were 12.4, 14.0 and 12.3 kJ mol-1, respectively. The average deviation was 4.4kJ mol-1. 

Tests were performed at 75°C using a University of Texas Model 500 spinning drop tensiometer. Active surfactant concentration in the aqueous phase prior to oil addition was 0.50% wt. The Kem River crude oil was from the Patricia Lease. The pH of the deionized water surfactant solutions was 8. The pH of the aqueous NaCl surfactant solutions was 9.5 unless otherwise noted. values represent the average deviation of two or three measurements at different times (0.75-1 h apart). D.I., deionized. 

The surface area of the crushed Berea sandstone was 1.50 m2/g. b% branching of parent olefin. cAverage value average deviation. 

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