Big Chemical Encyclopedia

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

Articles Figures Tables About

Influence additives modeling

This is a question of reaction prediction. In fact, this is a deterministic system. If we knew the rules of chemistry completely, and understood chemical reactivity fully, we should be able to answer this question and to predict the outcome of a reaction. Thus, we might use quantum mechanical calculations for exploring the structure and energetics of various transition states in order to find out which reaction pathway is followed. This requires calculations of quite a high degree of sophistication. In addition, modeling the influence of solvents on... [Pg.542]

Because of its many assumptions, a population model, especially with all the pre-specification demanded in this framework, is unlikely to be true. However, one can argue that this framework exerts the influence of model misspecification primarily on study power. This is because a misspecified model would generally result in lower power although not larger Type I error. In addition, this approach maintains a more realistic confidence interval width instead of an overly optimistic (short) one. By maximizing the model as much as data can be expected to support, the impact on Type I error is minimized. Therefore, the hypothesis test is made as conservative as possible, and thus suitable for BE assessment. [Pg.429]

The additive model in two factors was Y = and implied that the two factors influenced the response independently and in a magnitude proportional to the two slope coefficients, b and b. The response surface could be depicted as a plane, or as a series of straight line contours. Suppose the effects of impeller speed (X,) and solvent rate each increased... [Pg.154]

In order to produce methodologies that incorporate physical aspects of the system in the analysis, additive weighting systems have been constructed, like UPM (Brand and Gabbot 1993), and Influence Diagram models have been developed to represent dependencies in a more flexible manner (Zitrou and Bedford 2007). In addition, these modelling approaches represent expert judgment in a quantitative maimer and can be used in cases where limited or even no data exists. [Pg.1425]

Determination of flow distribution on the basis of model (40)-(43) for the given scheme and parameters. As a result of this stage the interaction between flows in the scheme branches that cause non-additivity of function F x,d) is fixed, since the flow distribution is the result of this interaction. So far as the scheme is closed, there is no interaction involving constant pressures or flows at nodes of external sources or sinks. Thermal interaction of the circuit described by equation (43) as a whole with the environment remains, but does not influences additivity of the minimized function. Transformation with the fixed interaction (distribution of flows among the branches) of the closed scheme (Fig. 3,a) to the tree (Fig. 3,b), specifying conditional external sources and sinks at break nodes (4, 4, 4", 5, 5, 5"). They make it possible to preserve material balances in the network that were determined at the previous stage. [Pg.53]

To better understand the physical background of the mentioned additional influences, the model of Martin should be briefly commented here, though its equations will not be given, because they are standard and well known from primary hterature (Martin, 1984), handbooks (Martin, 2010), and also from Groenewold (2004) and Groenewold and Tsotsas (2007). Martin s model is a... [Pg.152]

There is some uncertainty connected with testing techniques, errors of characteristic measurements, and influence of fectors that carmot be taken into account for building up a model. As these factors cannot be evaluated a priori and their combination can bring unpredictable influence on the testing results it is possible to represent them as additional noise action [4], Such an approach allows to describe the material and testing as a united model — dynamic mathematical model. [Pg.188]

The interest in vesicles as models for cell biomembranes has led to much work on the interactions within and between lipid layers. The primary contributions to vesicle stability and curvature include those familiar to us already, the electrostatic interactions between charged head groups (Chapter V) and the van der Waals interaction between layers (Chapter VI). An additional force due to thermal fluctuations in membranes produces a steric repulsion between membranes known as the Helfrich or undulation interaction. This force has been quantified by Sackmann and co-workers using reflection interference contrast microscopy to monitor vesicles weakly adhering to a solid substrate [78]. Membrane fluctuation forces may influence the interactions between proteins embedded in them [79]. Finally, in balance with these forces, bending elasticity helps determine shape transitions [80], interactions between inclusions [81], aggregation of membrane junctions [82], and unbinding of pinched membranes [83]. Specific interactions between membrane embedded receptors add an additional complication to biomembrane behavior. These have been stud-... [Pg.549]

The percolation argument is based on the idea that with an increasing Cr content an insoluble interlinked cliromium oxide network can fonn which is also protective by embedding the otherwise soluble iron oxide species. As the tlireshold composition for a high stability of the oxide film is strongly influenced by solution chemistry and is different for different dissolution reactions [73], a comprehensive model, however, cannot be based solely on geometrical considerations but has in addition to consider the dissolution chemistry in a concrete way. [Pg.2725]

The Beckstead-Derr-Price model (Fig. 1) considers both the gas-phase and condensed-phase reactions. It assumes heat release from the condensed phase, an oxidizer flame, a primary diffusion flame between the fuel and oxidizer decomposition products, and a final diffusion flame between the fuel decomposition products and the products of the oxidizer flame. Examination of the physical phenomena reveals an irregular surface on top of the unheated bulk of the propellant that consists of the binder undergoing pyrolysis, decomposing oxidizer particles, and an agglomeration of metallic particles. The oxidizer and fuel decomposition products mix and react exothermically in the three-dimensional zone above the surface for a distance that depends on the propellant composition, its microstmcture, and the ambient pressure and gas velocity. If aluminum is present, additional heat is subsequently produced at a comparatively large distance from the surface. Only small aluminum particles ignite and bum close enough to the surface to influence the propellant bum rate. The temperature of the surface is ca 500 to 1000°C compared to ca 300°C for double-base propellants. [Pg.36]


See other pages where Influence additives modeling is mentioned: [Pg.374]    [Pg.10]    [Pg.250]    [Pg.519]    [Pg.397]    [Pg.1093]    [Pg.869]    [Pg.314]    [Pg.1179]    [Pg.366]    [Pg.973]    [Pg.74]    [Pg.17]    [Pg.133]    [Pg.366]    [Pg.99]    [Pg.36]    [Pg.5742]    [Pg.449]    [Pg.395]    [Pg.207]    [Pg.340]    [Pg.209]    [Pg.336]    [Pg.79]    [Pg.726]    [Pg.154]    [Pg.1457]    [Pg.185]    [Pg.1607]    [Pg.182]    [Pg.345]    [Pg.495]    [Pg.224]    [Pg.372]    [Pg.100]    [Pg.622]    [Pg.255]    [Pg.427]    [Pg.325]    [Pg.513]   
See also in sourсe #XX -- [ Pg.120 , Pg.121 ]




SEARCH



Additive model

Additives modeling

Additivity model

© 2024 chempedia.info