Significant variable

Utility operating costs are usually the most significant variable operating cost after raw materials. Utility operating costs include... 

To evaluate the effect of indeterminate error on the data in Table 4.1, ten replicate determinations of the mass of a single penny were made, with results shown in Table 4.7. The standard deviation for the data in Table 4.1 is 0.051, and it is 0.0024 for the data in Table 4.7. The significantly better precision when determining the mass of a single penny suggests that the precision of this analysis is not limited by the balance used to measure mass, but is due to a significant variability in the masses of individual pennies. 

Analysis of such a correlation may reveal the significant variables and interactions, and may suggest some model, say of the L-H type, that could be analyzed in more detail by a regression process. The variables Xi could be various parameters of heterogeneous processes as well as concentrations. An application of this method to isomerization of /i-pentane is given by Kittrel and Erjavec (Ind. Eng. Chem. Proc. Des. Dev., 7,321 [1968]). 

For steam jacketed, agitated closed reactor ketdes, the overall U usually will range from 40-60 Btu/hr (ft ) ( F). Of course, the significant variables are the degree or type of internal wall turbulence and the viscosity and thermal characteristics of the internal fluid. For water or other liquid cooling in the reactor jacket, the U value usually ranges from 20-30. 

As with HjS, the distribution of sulfur among the other FCC products depends on several factors, which include feed, catalyst type, conversion, and operating conditions. Feed type and residence time are the most significant variables. Sulfur distribution in FCC products of several feedstocks is shown in Table 2-4. Figure 2-9 illustrates the sulfur distribution as a function of the unit conversion. 

Polymers have inherently high hydrocarbon ratios, making liquefaction of waste plastics into liquid fuel feedstocks a potentially viable commercial process. The objective is to characterise the thermal degradation of polymers during hydrogenation. LDPE is studied due to its simple strueture. Isothermal and non-isothermal TGA were used to obtain degradation kinetics. Systems of homopolymer, polymer mixtures, and solvent-swollen polymer are studied. The significant variables for... 

In this work, examples are shown of the use of the computerized analytical approach in multicomponent polymer systems. The approach works well for both fractionated and whole polymers. The methodology can (1) permit differentiation to be made as to Whether the given sample conprises one conponent or a mixture of several components (2) allow the NMR spectrum of a polymer mixture to be analyzed in an unbiased fashion (3) give information on mole fractions and reaction probabilities that can be significant variables in understanding catalyst structures or polymerization mechanisms. 

The steric hindrance as MgVol (molar volume) was found to be the most significant variable for this data set. 

As seen, there is significant variability in the estimates. This is the reason why we should avoid using this technique if possible (unless we wish to generate initial guesses for the Gauss-Newton method for ODE systems). As it was mentioned earlier, the numerical computation of derivatives from noisy data is a risky business ... 

Utility operating cost Utility operating cost is usually the most significant variable operating cost after the cost of raw materials. This is especially the case for the production of commodity chemicals. Utility operating cost includes ... 

Since D depends on C(t) to a power of 2, small changes in C(t) will cause significant variability in D. Thus, the analysis should focus on strategies to minimize this variability. Rearranging Eq. (28) gives... 

Physical laws, theories, empirical relations, etc., are normally expressed by equations relating the significant variables and parameters. These equations usually contain a number of terms. For example, the relation between the vertical elevation (z) and the horizontal distance (x) at any time for a projectile fired from a gun can be expressed in the form... 

The expression of a significant gut wall first-pass extraction ratio has several implications for affected drugs. First, oral bioavailability is lower than would be expected from the extent of absorption and the hepatic first-pass extraction. Second, the variability in expression of gut wall metabolic enzymes and transporters can lead to significant variability in gut wall first-pass extraction and thus oral bioavailability. Finally, the site of expression of these enzymes and transporters (i.e., the villus tip) brings them into contact with potentially co-administered drugs or dietary constituents, which could be inhibitors or inducers. Thus, there is the potential for drug-drug interactions at the level of the gut wall. 

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