Some useful definitions

Finally, a number of useful definitions of quantities directly or indirectly involved in the study of the surface area and porosity of both particulate and massive solids are given in Table 1.6. 

Open pore Cavity or channel communicating with the surface of the solid. 

Closed pore Cavity not communicating with the surface. 

True density Mass of the solid divided by the volume of the solid excluding open and closed pores. 

Effective solid The density of the solid as determined by a given liquid 

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Capacity Definitions In any analysis, the capacity per unit time of dynamic equipment (such as conveyors and bagging machines), as well as the rates at which they ac tuaUy perform, must be defined more precisely and realistically than by a mere statement of kilograms or pounds per hour. Some useful definitions employed by the equipment industi y are the following ... 

Table 9-1. Some useful definitions of oxidation and reduction which are of use in different circumstances.

This multipart question question illustrates material balance calculations used, for example, in formulating polyurethanes. Refer to Section 1.5.4 for some of the reactions of isocyanate groups. This problem is an extension of the concepts mentioned in Section 3.1.5 on end-group determinations. Some useful definitions follow ... 

Table 2.6 Some useful definitions for solving electrochemical problems.

When simple Hquids like naphtha are cracked, it may be possible to determine the feed components by gas chromatography combined with mass spectrometry (gc/ms) (30). However, when gas oil is cracked, complete analysis of the feed may not be possible. Therefore, some simple definitions are used to characterize the feed. When available, paraffins, olefins, naphthenes, and aromatics (PONA) content serves as a key property. When PONA is not available, the Bureau of Mines Correlation Index (BMCI) is used. Other properties like specific gravity, ASTM distillation, viscosity, refractive index. Conradson Carbon, and Bromine Number are also used to characterize the feed. In recent years even nuclear magnetic resonance spectroscopy has been... 

This appendix contains a glossary of nearly 200 common and uncommon terms and phrases used in ISO/TS 16949 and the Rules for Achieving lATF Recognition. It contains many terms and phrases not defined in ISO 8402 or ANSI/ASQC A3. Some alternative definitions are provided for clarification. The explanations are given for the context in which the terms are used. 

The rate of a chemical reaction can be described in any of several different ways. The most commonly used definition involves the time rate of change in tlie amount of one of the components participating in tlie reaction tliis rate is usually based on some arbitrary factor related to tlie reacting system size or geometry, such as volume, mass, or interfacial area. Tlie definition shown in Eq. (4.6.7), wliich applies to homogeneous reactions, is a convenient one from an engineering point of view. 

Tables IV and V contain appropriate balance equations for nonisothermal free-radical polymerizations and copolymerizations, which are seen to conform to equation 2k. Following the procedure outlined above, we obtain the CT s for homopolymerizations listed in Table VI. Corresponding CT s for copolymerizations can be. obtained in a similar way, and indeed the first and fourth listed in Table VII were. The remaining ones, however, were derived via an alternate route based upon the definitions in Table VI labeled "equivalent" together with approximate forms for pj, which were necessitated by application of the Semenov-type runaway analysis to copolymerizations, and which will subsequently be described. Some useful dimensionless parameters defined in terms of these CT s appear in Tables VIII, IX and X.

Current chemical information systems offer three principal types of search facility. Structure search involves the search of a file of compounds for the presence or absence of a specified query compound, for example, to retrieve physicochemical data associated with a particular substance. Substructure search involves the search of a file of compounds for all molecules containing some specified query substructure of interest. Finally, similarity search involves the search of a file of compounds for those molecules that are most similar to an input query molecule, using some quantitative definition of structural similarity. 

GP 2] [R 2] The definition of space-time yield in a micro reactor depends on the definition of the reactor volume . Owing to the large amoimt of construction material relative to the reaction channels and the neglect of some reactor parts ( abstraction to the real reaction zone ), several more or less useful definitions can be made. In the following, two definitions concerning the time yield divided by the pure reaction channel volume and the platelet volume were used. 

In analytical practice, some methods using definitive measurements, in principle, are also caUbrated in an experimental way (e.g. spectrophotometry, polarography) to provide reliable estimates of S. 

Using the definitions above many vector identities can be derived and these are listed in many sources e.g. [10]. Some useful identities are... 

Some of the commonly used definitions related to fires and explosions are given in what follows. These definitions are discussed in greater detail in later sections. 

The technique of risk assessment is used in a wide range of professions and academic subjects. Accordingly, in this introductory section some basic definitions are necessary. 

An architectural description is an abstraction there are many such abstractions that contribute to understanding a system, each one focused on one aspect and omitting other details. As with any model, there is some definition of conformance—that is, does a given implementation conform to that architecture Some views are more focused on the design and development-time activities others are relevant when you re testing or running the system still others focus on deployment and upgrade activities. Table 12.1 shows some useful architectural views and the system parts each one focuses on. 

Analytieal EM using electron-stimulated eharacteristic x-rays is a well-known ehemieal eomposition characterization teehnique for analysing materials. High spatial resolution chemical analyses (from areas of a few nm or less) using electron nanoprobes are now possible in a modern EM and can provide information of the catalyst composition at the subnanometre level. Details of EDX in the EM are described by Goldstein et al (1984) and some important definitions are highlighted in the following seetions. 

The second type of impurity, substitution of a lattice atom with an impurity atom, allows us to enter the world of alloys and intermetallics. Let us diverge slightly for a moment to discuss how control of substitutional impurities can lead to some useful materials, and then we will conclude our description of point defects. An alloy, by definition, is a metallic solid or liquid formed from an intimate combination of two or more elements. By intimate combination, we mean either a liquid or solid solution. In the instance where the solid is crystalline, some of the impurity atoms, usually defined as the minority constituent, occupy sites in the lattice that would normally be occupied by the majority constituent. Alloys need not be crystalline, however. If a liquid alloy is quenched rapidly enough, an amorphous metal can result. The solid material is still an alloy, since the elements are in intimate combination, but there is no crystalline order and hence no substitutional impurities. To aid in our description of substitutional impurities, we will limit the current description to crystalline alloys, but keep in mind that amorphous alloys exist as well. 

Remember that Table 11.3 contains some useful numerical values of k at different concentrations of various electrolytes. Equation (10) is the basic relationship of the Debye-Hiickel theory and may be integrated as follows. The variable x is introduced with the following definition ... 

In performing such experiments on isotropic materials, one is accustomed to express the elastic stiffness parameters in the experimentally more readily accessible technical parameters E (Young s modulus) and v (Poisson ratio). The relative change in length, in the direction of the tensile stress a is, by definition, given by (Al/t)i — a/E, whereas v = (Af/ )x/( A / )u. For several magnetostrictive films and substrates, E and v values are listed in table 1. Some useful relations are ... 

There are some common characteristics for gas-phase reaction systems that form the basis for understanding and describing the chemical behavior. In this section we will discuss some basic definitions and terms that are useful in kinetics, such as reaction order, molec-ularity, chain carriers, rate-limiting steps, steady-state and partial equilibrium approximations, and coupled/competitive reactions. 

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