Big Chemical Encyclopedia

Chemical substances, components, reactions, process design ...

Articles Figures Tables About

Some Supplementary Observations

The example presented above successfully illustrates hotv we develop and use the EVOP method for a discontinuous process. When we have a continuous process, it is suggested to transform it artificially into a discontinuous process. For this purpose, we must take into consideration all the factors of the process representing flow rates according to a fixed period of time. With these transformations we can control the effect of the random factors that influence the continuous process. If, for example, we consider the case of a continuous reactor, then, the conversion can be obtained from the analysis of 5 to 6 samples (each selected at a fixed period of time), when the corresponding input and output quantities are related to the [Pg.413]

In all experimental process investigations, where the final decision is the result of the hypotheses based on a comparison of the variances, we must know whether the observed variances are related to the process or to the experimental analysis procedure. Indeed, it is quite important to determine, when an experimental research is being carried out, whether we have to use a method or an instrument of analysis that produces an artificially high variance on the measured parameters. [Pg.414]

Before the era of modern computers, the EVOP process investigation was used successfully to improve the efficiency of many chemical engineering processes. Now its use is receding due to the competition from process mathematical modelling and simulation. However, biochemical and life processes are two large domains where the use of the EVOP investigation can still bring spectacular results. [Pg.414]

The objective of the statistical analysis of variances is to separate the effects produced by the dependent variables in the factors of the process. At the same time, this separation is associated with a procedure of hypotheses testing what allows to reject the factors (or groups of factors) which do not significantly influence the process. The basic mathematical principle of the analysis of variances consists in obtaining statistical data according to an accepted criterion. This criterion is complemented with the use of specific procedures that show the particular influence or effects of the grouping criterion on dependent variables. [Pg.414]

Besides, after identifying the effects, it is necessary to compare variances of the process produced by the variation of the factors and the variances of the process produced by the random factors [5.5, 5.8, 5.29-5.31]. [Pg.414]


During withdrawal, some patients may experience symptoms of steroid withdrawal (eg, joint or muscular pain, lassitude, depression) despite maintenance or even improvement of respiratory function. Encourage continuance with the inhaler, but observe for objective signs of adrenal insufficiency (eg, fatigue, lassitude, weakness, nausea and vomiting, hypotension). If adrenal insufficiency occurs, increase the systemic steroid dose temporarily and continue further withdrawal more slowly. During periods of stress or severe asthma attack, transfer patients will require supplementary systemic steroids. [Pg.744]

Beneficial and Harmful Effects. At low levels, sulfur dioxide in the atmosphere is not harmful to crops, but damage can occur at excessive levels (305—309). Crops differ gready in their sensitivity. Forest damage attributed to acid rain is often cited but the observed symptoms seem to have multiple causes and the contribution of sulfur acids is unspecified. The sulfur in precipitation is, up to a point, beneficial to plant growth because sulfur is an essential nutrient. Lessening the sulfur content of the atmosphere requires that supplementary sulfur be provided in fertilizer to some crops some crops already require supplementary sulfur. Sulfur dioxide itself has been found useful in drip irrigation systems (310,311) and in calcareous soils (308). Small field generators have been developed for this purpose. [Pg.148]

In the line giving the name of the solvent, or just below it, alternative names of the solvent are shown, and also its melting point.if this is higher than some of the CST. Similarly, the critical temperature of the solvent is listed if it is a pertinent factor in the observations. Also listed are references to the supplementary tables. This furnishes an index to them. [Pg.7]

While we have chosen to proceed here by reducing representations for the full group D3h, it would have been simpler to take advantage of the fact that D3h is the direct product of C3u and C where the plane in the latter is perpendicular to the principal axis of the former. The behaviour of any atomic basis functions with respect to the C3 subgroup is trivial to determine, and there are only two classes of non-trivial operations in C3v. In more general cases, it is often worthwhile to look for such simplifications. It is seldom useful, for instance, to employ the full character table for a group that contains the inversion, or a unique horizontal plane, since the symmetry with respect to these operations can be determined by inspection. With these observations and the transformation properties of spherical harmonics given in the Supplementary Notes, it should be possible to determine the symmetries spanned by sets of atomic basis functions for any molecular system. Finally, with access to the appropriate literature the labour can be eliminated entirely for some cases, since... [Pg.110]

In some cases, the formation of para adduct is doubtful. For example, Gilbert reported the formation of para adduct from 168 [234-236] however, supplementary experiments done by Cornelisse concluded the observed product by Gilbert had been meta adduct [232]. [Pg.165]

The first-order rate coefficient, k, of this pseudo-elementary process is assumed to vary with temperature according to an Arrhenius law. Model parameters are the stoichiometric coefficients v/ and the Arrhenius parameters of the rate coefficient, k. The estimation of the decomposition rate coefficient, k, requires a knowledge of the feed conversion, which is not directly measurable due to the complexity of analyzing both reactants and reaction products. Thus, a supplementary empirical relationship is needed to relate the feed conversion (conversion of A) to some experimentally accessible variable (Ross and Shu have chosen the yield of C3 and lighter hydrocarbons). It is observed that the rate coefficient, k, is not constant and decreases with increasing conversion. Furthermore, the zero-conversion rate coefficient depends on feed specifications (such as average carbon number, hydrogen content, isoparaffin/normal-paraffin ratio). Stoichiometric coefficients are also correlated with conversion. Of course, it is necessary to write supplementary empirical relationships to account for these effects. [Pg.264]

H, CHj, NHz, OH, 0CH3, F, NO2, CN, CHO, CF3, Li, O", NH, and NH3" ). Some of the work reported herein has been previously published (6,8-11) but a large part of our discussion refers to previously unpublished data accumulated over a number of years from several different laboratories. The primary goal of this study has been to draw together this wide body of computational data and to attempt to understand the diverse behavior observed within a relatively simple PMO (7) framework. There are undoubtedly other frameworks within which the results could be analyzed and we make no claim that our interpretation is necessarily unique. However, regardless of the qualitative picture of substituent effects which we develop here, the quantitative data stand on their own and hopefully may be utilized by other workers to prove or disprove alternative or supplementary hypotheses concerning substituent effects in aromatic systems. [Pg.3]


See other pages where Some Supplementary Observations is mentioned: [Pg.413]    [Pg.413]    [Pg.13]    [Pg.249]    [Pg.10]    [Pg.492]    [Pg.18]    [Pg.665]    [Pg.364]    [Pg.526]    [Pg.148]    [Pg.265]    [Pg.111]    [Pg.171]    [Pg.473]    [Pg.517]    [Pg.311]    [Pg.312]    [Pg.68]    [Pg.238]    [Pg.56]    [Pg.146]    [Pg.298]    [Pg.386]    [Pg.158]    [Pg.77]    [Pg.59]    [Pg.393]    [Pg.238]    [Pg.5]    [Pg.412]    [Pg.761]    [Pg.549]    [Pg.67]    [Pg.393]    [Pg.540]    [Pg.69]    [Pg.35]    [Pg.453]    [Pg.299]    [Pg.298]    [Pg.173]    [Pg.174]   


SEARCH



Some Observations

Supplementary

© 2024 chempedia.info