Big Chemical Encyclopedia

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

Articles Figures Tables About

Theories categories

The theoretical methods used commonly can be divided into three main categories, semi-empirical MO theory, DFT and ab-initio MO theory. Although it is no longer applied often, Hiickel molecular orbital (HMO) theory will be employed to introduce some of the principles used by the more modem techniques. [Pg.376]

Theoretical Models of the Response Surface Mathematical models for response surfaces are divided into two categories those based on theory and those that are empirical. Theoretical models are derived from known chemical and physical relationships between the response and the factors. In spectrophotometry, for example, Beer s law is a theoretical model relating a substance s absorbance. A, to its concentration, Ca... [Pg.675]

The values of d and n are given in Table 3 typical values for can be found in Table 4. The exponent of 0.5 on the Schmidt number (l-L /PiLj) supports the penetration theory. Further examples of empirical correlations provide partial experimental confirmation of equation 78 (3,64—68). The correlation reflecting what is probably the most comprehensive experimental basis, the Monsanto Model, also falls in this category (68,69). It is based on 545 observations from 13 different sources and may be summarized as... [Pg.36]

Kinetic theories of adsorption, desorption, surface diffusion, and surface reactions can be grouped into three categories. (/) At the macroscopic level one proceeds to write down kinetic equations for macroscopic variables, in particular rate equations for the (local) coverage or for partial coverages. This can be done in a heuristic manner, much akin to procedures in gas-phase kinetics or, in a rigorous approach, using the framework of nonequihbrium thermodynamics. Such an approach can be used as long as... [Pg.439]

The demand-related exposure is the historical number of demands for change of state experienced by the equipment population. In theory, the evaluation of this demand exposure is rather simple. In practice, the number of demands on a piece of equipment can originate from four different sources testing, automatic and manual initiation, failure related maintenance, and interfacing maintenance. The contribution each of these categories makes to demand related exposures is summarized below ... [Pg.223]

For more than two decades researchers have attempted to overcome the inadequacies of Flory s treatment in order to establish a model that will provide accurate predictions. Most of these research efforts can be grouped into two categories, i.e., attempts at corrections to the enthalpic or noncombinatorial part, and modifications to the entropic or combinatorial part of the Flory-Huggins theory. The more complex relationships derived by Huggins, Guggenheim, Stavermans, and others [53] required so many additional and poorly determined parameters that these approaches lack practical applications. A review of the more serious deficiencies... [Pg.19]

Appendix B provides a brief listing of information sources currently available on the World Wide Web (WWW), subject-sorted into a total of 91 WWW Universal Resource Locator (URL) links in 16 categories. Other links and information may be obtained from CA-related newsgroups such as comp, theory. cell-auto, comp.ai, comp.ai.alife and comp.ai.genetic. Additional resources may be found at the author s website at the Center for Naval Analyses http //www.cna.org/isaac. [Pg.723]

Having discussed some equilibrium properties of a crystal, we now outline and contrast the bases of the growth theories which will be dealt with in more detail later. The theories may be broadly split into two categories equilibrium and kinetic. The former [36-42] explain some features of the lamellar thickness, however the intrinsic folding habit is not accounted for. Therefore, at best, the theory must be considered to be incomplete, and today is usually completely ignored. We give a brief summary of the approach and refer the interested reader to the original articles. The kinetic theories will be the topic of the remainder of the review. [Pg.233]

Nonbenzenoid cyclic conjugated hydrocarbons are conveniently classified into two categories conjugated hydrocarbons composed of odd-membered rings called, in terminology of molecular orbital theory, nonalternant hydrocarbons, and cyclic polyenes currently known as annulenes. [Pg.4]

Among the theories of limited applicability, those of heterogeneous catalysis processes have been most developed (4, 5, 48). They are based on the assumption of many active sites with different activity, the distribution of which may be either random (23) or thermodynamic (27, 28, 48). Multiple adsorption (46, 47) and tunnel effects (4, 46) also are considered. It seems, however, that there is in principle no specific feature of isokinetic behavior in heterogeneous catalysis. It is true only that the phenomenon has been discovered in this category and that it can be followed easily because of large possible changes of temperature. [Pg.462]

The last category is the pressure-driven gas flows, which are typical in micro gas fluidic and micro heat transfer systems. Because the channel diameter or width in micro gas fluidic systems is in the scale of sub-micrometer or less, ultra-thin gas lubrication theory plays an important role in... [Pg.114]

The large deformability as shown in Figure 21.2, one of the main features of rubber, can be discussed in the category of continuum mechanics, which itself is complete theoretical framework. However, in the textbooks on rubber, we have to explain this feature with molecular theory. This would be the statistical mechanics of network structure where we encounter another serious pitfall and this is what we are concerned with in this chapter the assumption of affine deformation. The assumption is the core idea that appeared both in Gaussian network that treats infinitesimal deformation and in Mooney-Rivlin equation that treats large deformation. The microscopic deformation of a single polymer chain must be proportional to the macroscopic rubber deformation. However, the assumption is merely hypothesis and there is no experimental support. In summary, the theory of rubbery materials is built like a two-storied house of cards, without any experimental evidence on a single polymer chain entropic elasticity and affine deformation. [Pg.581]

Let us stress here that the applications of the above framework to noncommutative operators Ay and A2 could result in wrong reasoning in light of the property that operator (27) is non-self-adjoint and scheme (26) does not fall within the category of two-layer iteration schemes lying in the fundamentals of the general theory. [Pg.722]

It is hardly possible to predict that a general theory will ever be evolved which will cover all possible types of industrial emulsions and foams. However, it seems that if the information described were gathered in a systematic fashion, the data could be classified in a logical order for different types of emulsions. Hence, cosmetic-type emulsions, salad dressing, and mayonnaise-type emulsions would each fall into its own individual category. The suggestion therefore is made that a repository of such information be made available to all who are interested. [Pg.71]

The therapeutic goal in autoimmune diseases such as RA is to control disease, to establish remission, and eventually to cure. In theory, this goal can be achieved using either Ag-specific approaches, for example, elimination of self-reactive T cells (assuming that a finite number of key Ags can be identified as the target of the autoimmune process in RA), or the non-Ag-specific approaches, for example, blockade of cytokines as in the case of TNF-a neutralization. Currently, only the latter types of approaches have yielded clinical benefit, and it is in this category that approaches to block chemokines or receptors may be included. Despite their appeal in terms of effectiveness, non-Ag-specific approaches carry a higher risk of immunosuppression and opportunistic infections (48). [Pg.170]

Ho Ping-Yu and Joseph Needham. Theories of categories in early mediaeval Chinese alchemy. J Warburg CourtauldInsts 22 (1959) 173-210. [Pg.329]


See other pages where Theories categories is mentioned: [Pg.82]    [Pg.82]    [Pg.302]    [Pg.82]    [Pg.82]    [Pg.302]    [Pg.465]    [Pg.437]    [Pg.11]    [Pg.85]    [Pg.235]    [Pg.334]    [Pg.342]    [Pg.407]    [Pg.324]    [Pg.247]    [Pg.182]    [Pg.216]    [Pg.334]    [Pg.293]    [Pg.71]    [Pg.111]    [Pg.327]    [Pg.113]    [Pg.129]    [Pg.166]    [Pg.261]    [Pg.153]    [Pg.793]    [Pg.76]    [Pg.147]    [Pg.75]    [Pg.26]    [Pg.243]    [Pg.401]    [Pg.458]   
See also in sourсe #XX -- [ Pg.3 ]




SEARCH



Concepts of Category Theory

Some Structure Theory of Categories

© 2024 chempedia.info