Practical classifications

For many wastes, there is no practical classification system for establishing a boundary (e.g., amount of hazardous substances) below which the waste is considered to be nonhazardous. This means that large volumes of waste are managed at considerable cost because the waste cannot be conclusively shown to contain no hazardous substances or, even more difficult, to contain an amount of hazardous substances e.g., uranium) no greater than was initially present in a material before its use by humans. 

Dow s Fire and Explosion Index, Hazard Classification Guide, 7th ed., A Chemical Engineering Progress Technical Manual, AIChE, New York, 1994. This booklet provides excellent practical classification in 74 pages. This popular process safety manual, with a listed price of 45, is designed to help the user quantify the expected damage of potential fire and explosion incidents in realistic terms. 

Elaborate classification of dryers has been presented by Kroll (1978) and Keey (1972) but less comprehensive (but perhaps more practical) classifications are shown in Table 9.1. In this table, the method of operation, physical form of the stock, scale of production, special features, and drying time are presented. Two other classifications of dryers may be found in Perry (1999). One classifies the equipment on the basis of heat transfer (Figure 12-45) and the other on the basis of the material handled (Table 12-9) in Perry. 

Practical classification of the branching types of the biliary tree an analysis of 1,094 consecutive direct cholangiograms. X Amer. Coll. Surg. 

A practical classification of natural polysaccharides Is based on their source. This kind of classification recognizes the following groups ... 

In practice, classification and handling of various occurrences and events of concern ought to rely on the following elements ... 

Apart from the underlying principles, there are the questions of how the data are obtained and their limitations. With the phenetic method, characters used are those for which it is possible to make the necessary quantitative measurements. With the cladistic method, it is rarely possible to determine each branch point, especially where convergent evolution has occurred. The phenetic method produces a practical classification but lacks the deeper philosophical justification of the cladistic method. However, both methods often give similar results, but differences arise, as in the example in Fig. 1.2. Although the crocodile and lizard show greater morphological similarity to one another than to the bird, birds and crocodiles have more recent common ancestors than crocodiles and lizards. 

Irrespective of the type of classification system used, practical classification and identification on a day to day basis must, of necessity, be based on characteristics which are easy and simple to observe and measure. One obvious example is motility, which depends on flagella. Motility/non-motility is a useful differential character, which is easy to observe using simple techniques and is therefore widely used in classification. However, the number and position of the flagella, which may be polar or peritrichous (all round the cell), is also a differential character. To observe these reliably requires an electron microscope, which is not... 

A practical classification of all syntheses especially concerning the erythrinane ring system is based on the idea which of the three alicyclic rings A, B, or C is completed in the final step. Thus in principle two alternatives are conceivable ... 

As shown in Fig. 1, plastics are classified as thermoplastics, elastomers, and duroplastics. In practice, classification is made in accordance with a number of different aspects. In Fig. 1, thermoplastics are categorized in physical terms (according to stmcture), elastomers in chemical terms (double bond), and duroplas-tics according to process pressure. 

The accuracy of the average risk of a classification can be computed in principle if the statistics of the data are known. However, the uncertainties mentioned considerably limit the computation of risk in practical applications. Therefore, the usefulness of a parametric method for a practical classification problem can be examined - as for other classification methods - only empirically. 

Some hesitations may arise with the use of a priori probabilities of classes during classification of unknowns. If the a priori probabilities are taken from the composition of the training set one maximizes the total performance of the classifier, assuming for the unknowns the same a priori probabilities as for the training set. In a practical classification problem (e.g. "does the molecule contain a carbonyIgroup or not ") one should usually presuppose equal a priori probabilities for both classes - otherwise a less frequent class may never be found by the classifier. 

Introduction and classification. Size-reduction equipment may be classified according to the way the forces are applied as follows between two surfaces, as in crushing and shearing at one solid surface, as in impact and by action of the surrounding medium, as in a colloid mill. A more practical classification is to divide the equipment into crushers, grinders, fine grinders, and cutters. 

In Chapters IV and V considerable effort was spent describing strong electrolytes and alternative formulations for their corresponding mean and/or ionic activity coefficients. A strict definition of a strong electrolyte is a species which completely dissociates in water. In reality, very few species fit this definition of strong electrolytes. The following definitions are offered in order to provide a practical classification of electrolytes ... 

Table A.5 — Example of Mapping Prior Design Practice Classification to SIL Levels...

LcAile metal ions react essentially on mixing of the metal ion and ligand solutions, that is, within a few seconds at most Inert metal ions require at least a few minutes for their substitution reactions to be complete. This operational classification provides a useful practical classification that has endured as a qualitative description of the reactivity of a metal ion. 

R.K. Saini, Practical Classification for Determining Electrical Classification, Powermag 3 (March 2007). bttp //www.powermag.com/practical-guidelines-for-determining electrical-area-classification/. 

An additional, and practical, classification is between reactions that convert a C-H bond into a new functional group, which is useful for further bond formation, and reactions that convert a C-H bond directly into a new C-C bond. The latter are obviously more efficient, but may not always be practical in every... 

In biochemistry, the most common and perhaps most practical classification of proteinogenic amino acids is according to the side chain polarity and its ionic forms occurring in neutral solutions, which is related to non-bonding interactions in proteins (see Section 7.6.2.2). The following groups of amino acids are recognised ... 

American Society for Testing and Materials n ASTM. A nonprofit corporation formed for the development of standards on characteristics and performance of materials, products, systems, and services, and the promotion of related knowledge. In ASTM terminology, standards include test methods, definitions, recommended practices, classifications, and specifications. 

Practical Classification of Coalescing Systems. While it has been stated repeatedly that coalescence is highly complex and that scale-up is difficult, not all liquid-liquid systems are complex. A simple way to characterize... 

Tossy JD, Mead NC, Sigmond HM (1963) Acromioclavicular separations usefiil and practical classification for treatment. Clin Orthop 28 111-119... 

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