Randomization efficiency

The solution Xh(t) of the linearized equations of motion can be solved by standard NM techniques or, alternatively, by explicit integration. We have experimented with both and found the second approach to be far more efficient and to work equally well. Its handling of the random force discretization is also more straightforward (see below). For completeness, we describe both approaches here. 

As an alternative to the random selection of particles it is possible to move the atom sequentially (this requires one fewer call to the random number generator per iteration) Alternatively, several atoms can be moved at once if an appropriate value for the maximun displacement is chosen then this may enable phase space to he covered more efficiently. 

Randomly choose a trial move for the system. This could be moving all atoms, but it more often involves moving one atom or molecule for efficiency reasons. 

Combinatorial Hbraries are limited by the number of sequences that can be synthesized. For example, a Hbrary consisting of one molecule each of a 60-nucleotide sequence randomized at each position, would have a mass of >10 g, weU beyond the capacity for synthesis and manipulation. Thus, even if nucleotide addition is random at all the steps during synthesis of the oligonucleotide only a minority of the sequences can be present in the output from a laboratory-scale chemical DNA synthesis reaction. In analyzing these random but incomplete Hbraries, the protocol is efficient enough to allow selection of aptamers of lowest dissociation constants (K ) from the mixture after a small number of repetitive selection and amplification cycles. Once a smaller population of oligonucleotides is amplified, the aptamer sequences can be used as the basis for constmcting a less complex Hbrary for further selection. 

Plates and random packings have much the same efficiency and capacity. 

Structured packing efficiency is about 1.5 times that of plates or random packing. 

The efficiency advantage of structured packing over random packings and plates decreases from 1.5 to 1.2 as the parameter increases from 0.1 to 0.3... 

The random packing appears to have the highest capacity and efficiency, and structured packing the least capacity and efficiency. 

Lucas and Porter (U.S. Patent 3,370,401, 1967) developed a fiber-bed scrubber in which the gas and scrubbing liquid flow vertically upward through a fiber bed (Fig. 17-55). The beds tested were composed of knitted structures made from fibers with diameters ranging From 89 to 406 [Lm. Lucas and Porter reported that the fiber-bed scrubber gave substantially higher efficiencies than did venturi-type scrubbers tested with the same dust at the same gas pressure drop. In similar experiments, Semrau (Semrau and Lunn, op. cit.) also found that a fiber-bed contactor made with random-packed steel-wool fibers gave higher efficiencies than an orifice contactor. However, there... 

The structured packing efficiency is about 50% higher than either the trays or the random packing. 

Efficiency and capacity for the trays, the random packing, and the structured packing decline with a rise in flow parameter. 

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