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Predictive method

The first step in developing a QSPR equation is to compile a list of compounds for which the experimentally determined property is known. Ideally, this list should be very large. Often, thousands of compounds are used in a QSPR study. If there are fewer compounds on the list than parameters to be fitted in the equation, then the curve fit will fail. If the same number exists for both, then an exact fit will be obtained. This exact fit is misleading because it fits the equation to all the anomalies in the data, it does not necessarily reflect all the correct trends necessary for a predictive method. In order to ensure that the method will be predictive, there should ideally be 10 times as many test compounds as fitted parameters. The choice of compounds is also important. For... [Pg.243]

In unsupervised learning, the outcome is usually a hypothesis to then be tested, often usiag classification or prediction methods. If the unsupervised learning process suggests the presence of distinct clusters, the hypothesis can be tested by applyiag a classification method to the data. A low number of misclassified samples would tend to reinforce the hypothesis. [Pg.424]

Controversy over test methodology, and concern with the welfare of test animals, has been highly pubhci2ed in the last decade, and various states have proposed legislation to ban animal tests. Significant effort has been devoted to developing nonanimal alternative tests and predictive methods. Progress has been made, but no entirely satisfactory substitute has been found to date (142). [Pg.539]

EmpiricalEfficieny Prediction Methods. Numerous empirical methods for predicting plate efficiency have been proposed. Probably the most widely used method correlates overall column efficiency as a function of feed viscosity and relative volatiHty (64). A statistical correlation of efficiency and system variables has been developed from numerous plate efficiency data (65). [Pg.170]

In the most general sense, a molecular-based property prediction method can be thought of as any method in which the physical features of a molecule (or... [Pg.247]

Myers, K. H., Thermodynamic and Transpori Properiy Prediction Methods for Or ganometallic Compounds, M.S. Thesis, The Pennsylvania State University, University Park, PA, 1990. [Pg.383]

Prediction Methods Two methods have gained almost universal acceptance for prediction of the vapor pressure of pure hydrocarbons. [Pg.390]

There are no reliable prediction methods for solid heat capacity as a function of temperature. However, the atomic element contribution method of Hurst and Harrison,which is a modification of Kopp s Rule, provides estimations at 298.15 K and is easy to use ... [Pg.395]

Variables a andZ are specific constants reported by Tsonopoulos for some alcohols and water (e.g., methanol a = 0.0878, b = 0.0560 and water a = 0.0279, b = 0.0229). Tsonopoulos also gives specific prediction methods for haloalkanes and water pollutants. [Pg.399]

Liquid Density Prediction Methods for the prediction of pure saturated hydrocarbons and nonhydrocarbon organics, compressed hydrocarbon hquids, and defined and undefined hydrocarbon mixtures were evaluated. Only the most accurate and convenient methods are included here. [Pg.402]

For both polar and nonpolar nonhydrocaihon gaseous mixtui es at low pressui es, the most accurate viscosity prediction method is the method of Brokaw. The method is quite accurate but requires the dipole moment and the Stockmayer energy parameter (e/A ) for polar components as well as pure component viscosities, molecular weights, the normal boding point, and the hq-uid molar volume at the normal boding point. The Technical Data Manual should be consulted for the fidl method. [Pg.408]

Experiment diffusion coefficients are scarce and not highly accurate, especially in the liquid phase, leading to prediction methods with marginal accuracy. However, use of the v ues predicted are generally suit le for engineering calculations. At concentrations above about 10 mole percent, predicted values should be used with caution. Diffu-sivities in liquids are lO -lO times lower than those in gases. [Pg.414]

Flash points, lower and upper flammability limits, and autoignition temperatures are the three properties used to indicate safe operating limits of temperature when processing organic materials. Prediction methods are somewhat erratic, but, together with comparisons with reliable experimental values for families or similar compounds, they are valuable in setting a conservative value for each of the properties. The DIPPR compilation includes evaluated values for over 1000 common organics. Detailed examples of most of the methods discussed are available in Danner and Daubert."... [Pg.418]

The method of Shebeko et al. " is the preferred flash point prediction method. The formula of the compound, the system pressure, and vapor pressure data for the compound must be available or estimable. Equation (2-174) is the basic equation. [Pg.418]

Generahzed prediction methods for fci and Hi do not apply when chemical reaction occurs in the liqmd phase, and therefore one must use ac tual operating data for the particular system in question. A discussion of the various factors to consider in designing gas absorbers and strippers when chemical reac tious are involved is presented by Astarita, Savage, and Bisio, Gas Treating with Chemical Solvents, Wuey (1983) and by Kohl and Ricseufeld, Gas Purification, 4th ed., Gulf (1985). [Pg.620]

Empirical Predictive Methods Two empirical correlations which have found wide use are the one of Drickamer and Bradford... [Pg.1380]

Theoretical Predictive Methods Tbe approach to equilibrium on a plate may be defined as tbe ratio of tbe aclual change in gas composition as it passes through tbe plate to tbe change that would have occurred if tbe gas bad reached a state of equibbrium with tbe liqmd. If a point on plate n is considered, this definition leads to tbe point efficiency ... [Pg.1381]

In hen of careful independent checks of predictive accuracy, the results of the comprehensive theoretical work will not be presented here. Simpler, more easily understood predictive methods, for certain important limiting cases, will be presented. As a check on the accuracy of these simpler methods, it will perhaps be prudent to calculate the bubble diameter from the graphical representation by Mersmann (loc. cit.) of the resiJts of Kumar et al. (loc. cit.). [Pg.1417]

For conditions approaching constant pressure at the orifice entrance, which probably siiTuJates most industri appheations, there is no independently verified predictive method. For air at near atmospheric pressure sparged into relatively inviscidhqiiids (11 - 100 cP), the correlation of Kumar et al. [Can. J. Chem. Eng., 54, 503 (1976)] fits experimental data well. Their correlation is presented here as Fig. 14-92. [Pg.1417]

David W. Taylor Model Basin, Washington, September 1953 Jackson, loc. cit. Valentin, op. cit.. Chap. 2 Soo, op. cit.. Chap. 3 Calderbank, loc. cit., p. CE220 and Levich, op. cit.. Chap. 8). A comprehensive and apparently accurate predictive method has been publisned [Jami-alahamadi et al., Trans ICE, 72, part A, 119-122 (1994)]. Small bubbles (below 0.2 mm in diameter) are essentially rigid spheres and rise at terminal velocities that place them clearly in the laminar-flow region hence their rising velocity may be calculated from Stokes law. As bubble size increases to about 2 mm, the spherical shape is retained, and the Reynolds number is still sufficiently small (<10) that Stokes law should be nearly obeyed. [Pg.1419]

To design deep-bed contactors for mass-transfer operations, one must have, in general, predictive methods for the following design parameters ... [Pg.1425]

Interfacial Area This consideration in agitated vessels has been reviewed and summarized by Tatterson (op. cit.). Predictive methods for interfacial area are not presented here because correlations are given for the overall volumetric mass transfer coefficient liquid phase controlhng mass transfer. [Pg.1425]

Prediction methods attempt to quantify the resistances to mass transfer in terms of the raffinate rate R and the extract rate E, per tower cross-sectional area Af, and the mass-transfer coefficient in the raffinate phase and the extract phase times the interfacial (droplet) mass-transfer area per volume of tower a [Eqs. (15-32) and (15-33)]. [Pg.1464]

There are many types of phase diagrams in addition to the two cases presented here these are summarized in detail by Zief and Wilcox (op. cit., p. 21). Solid-liquid phase equilibria must be determined experimentally for most binaiy and multicomponent systems. Predictive methods are based mostly on ideal phase behavior and have limited accuracy near eutectics. A predic tive technique based on extracting liquid-phase activity coefficients from vapor-liquid equilib-... [Pg.1990]

A recent survey analyzed the accuracy of tliree different side chain prediction methods [134]. These methods were tested by predicting side chain conformations on nearnative protein backbones with <4 A RMSD to the native structures. The tliree methods included the packing of backbone-dependent rotamers [129], the self-consistent mean-field approach to positioning rotamers based on their van der Waals interactions [145],... [Pg.288]

Wastewater Deep Well Injection. This is an alternate wastewater disposal procedure and requires some treating prior to injection, such as filtration or pFI adjustment. Permits for this procedure require long lead times. Reference 4 gives prediction methods for refinery wastew ater, generation. [Pg.229]


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See also in sourсe #XX -- [ Pg.115 ]




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