Cutting classification

In fact, thermodynamics cannot tell us anything about the significance of the various terms on the rhs of relation (1.1), whether or not the system is an ideal gas. On the other hand, by introducing the concept of assimilation, we have a clear-cut classification of the three terms in relation (1.1). This classification is valid, independent of any assumption of ideality. 

It is customary to divide suspensions into two broad categories - fine particle suspensions in which the particles are reasonably uniformly distributed in the liquid with little separation and coarse suspensions in which particles, if denser than the liquid, tend to separate out and to travel predominantly in the lower part of a horizontal pipe (at a lower velocity than the liquid) in a vertical pipe the solids may have an appreciably lower velocity than the liquid. Although, this is obviously not a very clear cut classification and is influenced by the flow rate and concentration of solids, it does nonetheless provide a convenient initial basis for classifying the flow behaviour of liquid-solid mixtures. 

Although it is difficult to predict the possibility of isolating a HSCC, it is probably more a rule than an exception that these species, which are not obvious candidates and which have exotic stoichiometries with respect to conventional titrations ratios in solution, should be crystallized. One has to keep in mind that the solid state has constraints which do not need to match those prevailing in solution. The existence of these chimeras clearly shows that there are borderline cases which resist any clear cut classification. So far, few researchers have extended their studies sufficiently to be able to put themselves in a situation to detect these HSCCs. 

Much surface work is concerned with the local atomic structure associated with a single domain. Some surfaces are essentially bulk-temiinated, i.e. the atomic positions are basically unchanged from those of the bulk as if the atomic bonds in the crystal were simply cut. More coimnon, however, are deviations from the bulk atomic structure. These structural adjustments can be classified as either relaxations or reconstructions. To illustrate the various classifications of surface structures, figure A1.7.3(a ) shows a side-view of a bulk-temiinated surface, figure A1.7.3(b) shows an oscillatory relaxation and figure A1.7.3(c) shows a reconstructed surface. 

Pre-Production Handling. Salt-cured catde hides, when received at the tannery, are individually bundled to prevent excessive moisture loss. The bundles are tied with ropes that are later cut and removed the hides may be sorted for different weight or quaUty classification at this point. It is best to have hides of similar size and thickness in a given production batch to assure an even reactivity of the processing chemicals and to avoid frequent adjustments in the machinery to compensate for size and thickness variations. In the modem large tannery, the size/quaUty classification is not necessary because the hides arrive in carload quantities under specifications as to size, type, and month of slaughter. 

AH three parameters, the cut size, sharpness index, and apparent bypass, are used to evaluate a size separation device because these are assumed to be independent of the feed size distribution. Other measures, usually termed efficiencies, are also used to evaluate the separation achieved by a size separation device. Because these measures are dependent on the feed size distribution, they are only usefiil when making comparisons for similar feeds. AH measures reduce to either recovery efficiency, classification efficiency, or quantitative efficiency. Recovery efficiency is the ratio of the amount of material less than the cut size in the fine stream to the amount of material less than the cut size in the feed stream. Classification efficiency is defined as a corrected recovery efficiency, ie, the recovery efficiency minus the ratio of the amount of material greater than the cut size in the fine stream to the amount of material greater than the cut size in the feed stream. Quantitative efficiency is the ratio of the sum of the amount of material less than the cut size in the fine stream plus the amount of material greater than the cut size in the coarse stream, to the sum of the amount of material less than the cut size in the feed stream plus the amount of material greater than the cut size in the feed stream. Thus, if the feed stream analyzes 50% less than the cut size and the fine stream analyzes 95% less than the cut size and the fine stream flow rate is one-half the feed stream flow rate, then the recovery efficiency is 95%, the classification efficiency is 90%, and the quantitative efficiency is 95%. 

I/s = 0.022 ), high classification capacity at low cut sizes can only be achieved by feeding many cyclones of the same diameter. The manifolding of... 

Separate classifications exist for metal-cutting appHcations and wear parts (8). Classifications that are generally accepted by producers and users are available (9,10). 

Glassification. Classification (2,12,26,28) or elutriation processes separate particles by the differences in how they settle in a Hquid or moving gas stream. Classification can be used to eliminate fine or coarse particles, or to produce a narrow particle size distribution powder. Classification by sedimentation iavolves particle settling in a Hquid for a predetermined time to achieve the desired particle size and size distribution or cut. Below - 10 fim, where interparticle forces can be significant, gravitational-induced separation becomes inefficient, and cyclone and centrifugation techniques must be used. Classification also separates particles by density and shape. Raw material separation by differential sedimentation is commonly used in mineral processiag. 

The model of the ciystallizei and selective removal devices that led to equations 64—66 is referred to as the R-Z crystallizer. It is an obvious idealization of actual crystallizers because of the perfect cuts assumed at and However, it is a useful approximation to many systems and it allows quahtative analyses of complex operations. The R-Z model may also be representative of inadvertant classification, ie, fines or course crystals may be preferentially removed from a crystallizer without installation of specific hardware to accomphsh such an objective. 

Thus the factors vaiy with the type of processing, although the boundaries between the classifications are not clear-cut and considerable judgment is required in selection of the correct factor. 

In kaohn classification, the product is typically measured with a certain percentage less than a given size (example 90 percent or 95 percent less than 1 or 2 lm). Each combination of percent and size cut represents a condition by which the centiifuge would have to tune to yield the product specification. 

More elongated devices are used for slurry thickening whilst those of more squat aspect ratio devices are suitable for product classification by size, as in fines-destruction circuits. The pressure drop in a hydrocyclone varies with the feed rate raised to a power between 2 and 3.3. The cut size is a weak function of pressure drop, varying with for dilute feeds. Large pressure drops are... 

The regions over which the different types of flow can occur are conveniently shown on a Flow Pattern Map in which a function of the gas flowrate is plotted against a function of the liquid flowrate and boundary lines are drawn to delineate the various regions. It should be home in mind that the distinction between any two flow patterns is not clear-cut and that these divisions are only approximate as each flow regime tends to merge in with its neighbours in any case, the whole classification is based on highly subjective observations. Several workers have produced their own maps 4 8. ... 

The hazards of a rigid classification of substances which may modify the course of a free radical polymerization are well illustrated by the examples of inhibitors and retarders which have been cited. The distinction between an inhibitor or retarder, on the one hand, and a co-monomer or a transfer agent, on the other, is not sharply defined. Moreover, if the substance is a free radical, it is potentially either an initiator or an inhibitor, and it may perform both functions as in the case of triphenylmethyl. If the substance with which the chain radicals react is a molecule rather than a radical, three possibilities may arise (i) The adduct radicals may be completely unreactive toward monomer. They must then disappear ultimately through mutual interaction, and we have a clear-cut case of either inhibition or retarda-... 

We want to emphasize that the high point of the graph is not the hitmax. It is the point of best classification, which does not have the same properties as the hitmax (for details see Meehl and Yonce, 1994, p. 1066). For this reason, MAMBAC s method of calculating the taxon base rate is radically different from methods that other CCK procedures use. MAMBAC s approach starts with the assumption that only taxon members lie above the highest cut and only nontaxon members lie below the lowest cut. This is the only assumption of this method, and it should hold if the data set is fairly... 

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