Drop off

Wells may be drilled at a constant angle to the target or dropped off to a lower angle through the reservoir section. To build, maintain or drop the deviation angle stabilisers are run in the bottom hole assembly (Fig. 3.15). A change in deviation used to require a round trip to change the position of those stabilisers in the bottom hole assembly. In recent years, adjustable, hydraulically activated stabilisers have been developed. The... 

The Gaussian, with r in the exponent, drops off faster than the true Is orbital, which has r in the exponent. The Gaussian is too thin at larger distances r from the nucleus (Fig. 8-2). 

Molecular masses up to about 2000 Da are routine above this value, the efficiency of the process drops off, but it is still useful up to about 4000-5000 Da. 

The bulk viscosity of polystyrene (M = 371,000) at 200°C was measured by Graessley and Segalt at different rates of shear. At low rates of shear Tjj = 330,000 P and drops off with 7 approximately as follows ... 

Even with this modification, we note that the model predicts a drop off in modulus which is steeper than observed in the individual steps. This gradual... 

The greater the undercooling, the more rapidly the polymer crystallizes. This is due to the increased probability of nucleation the more supercooled the liquid becomes. Although the data in Fig. 4.8 are not extensive enough to show it, this trend does not continue without limit. As the crystallization temperature is lowered still further, the rate passes through a maximum and then drops off as Tg is approached. This eventual decrease in rate is due to decreasing chain mobility which offsets the nucleation effect. 

Note that the upper limit of the second summation has been shifted from Nq to oo for mathematical reasons. The change is of little practical significance, since Eq. (5.24) drops off for very large values of n. To simplify the summation in Eq. (5.27) consider the following steps ... 

Enthalpies of mixing have their origin in the forces that operate between individual molecules. Intermolecular forces drop off rapidly with increasing distance of separation between molecules. This means that only nearest neighbors need be considered in the model. 

The statistical problem. The relative probability associated with the placement of the two coils such that d = °° is unity The solution is so dilute that we can place the polymer molecules anywhere. It is at smaller d s that the placement probability drops off because of a generally unfavorable AG associated with the overlap. We assume that the decrease in probability is described by the Boltzmann factor and write... 

A report on the continuous flash pyrolysis of biomass at atmospheric pressure to produce Hquids iadicates that pyrolysis temperatures must be optimized to maximize Hquid yields (36). It has been found that a sharp maximum ia the Hquid yields vs temperature curves exist and that the yields drop off sharply on both sides of this maximum. Pure ceUulose has been found to have an optimum temperature for Hquids at 500°C, while the wheat straw and wood species tested have optimum temperatures at 600°C and 500°C, respectively. Organic Hquid yields were of the order of 65 wt % of the dry biomass fed, but contained relatively large quantities of organic acids. 

Properties. A high volatile western Kentucky bituminous coal, the tar yield of which by Fischer assay was ca 16%, gave a tar yield of ca 26% at a pyrolysis temperature of 537°C (146—148). Tar yield peaked at ca 35% at 577°C and dropped off to 22% at 617°C. The char heating value is essentially equal to that of the starting coal, and the tar has a lower hydrogen content than other pyrolysis tars. The product char is not suitable for direct combustion because of its 2.6% sulfur content. 

Some biphenylene end-capped polyquiaolines have been used to make carbon-fiber rekiforced composites (102). However, properties of these composites dropped off significantly when oxidatively aged for 50—100 h at 316°C. 

Generally, recyclables are either coUected at curbside or deposited by consumers at various types of drop-off locations, such as local recycling centers, community service clubs, dealers, and commercial buyback centers. Curbside coUections of recyclables can be accompUshed either in conjunction with the pickup of aU MSW or as a separate activity. Co-coUection systems range from complete commingling of aU waste for later separation at a mixed waste processing facility to transporting essentially source-separated recyclables in the same tmck as MSW. 

Each factor is evaluated on the basis of a score of 0—10. A total score of 80 points or higher statistically has resulted in eight or nine successes out of ten instances. Below 80 points, the success-to-failure ratio for new development drops off sharply. Such analyses can be made not only initially but periodically during an R D project and as the business develops. 

The completion stage is identified by the fact that all the monomer has diffused into the growing polymer particles (disappearance of the monomer droplet) and reaction rate drops off precipitously. Because the free radicals that now initiate polymerization in the monomer-swollen latex particle can more readily attack unsaturation of polymer chains, the onset of gel is also characteristic of this third stage. To maintain desirable physical properties of the polymer formed, emulsion SBR is usually terminated just before or at the onset of this stage. 

These simple velocity profiles do not indicate directly any dependence of the flow pattern efficiency upon the rotational speed of the centrifuge. A dependence on speed is to be expected on the basis of the argument that at high speeds the gas in the centrifuge is crowded toward the periphery of the rotor and that the effective distance between the countercurrent streams is thereby reduced. It can be seen from the two-sheU model that, as the position of upflowing stream approaches the periphery, the flow pattern efficiency drops off from its maximum value. 

The precious-metal platinum catalysts were primarily developed in the 1960s for operation at temperatures between about 200 and 300°C (1,38,44). However, because of sensitivity to poisons, these catalysts are unsuitable for many combustion apphcations. Variations in sulfur levels of as Httle as 0.4 ppm can shift the catalyst required temperature window completely out of a system s operating temperature range (44). Additionally, operation withHquid fuels is further compHcated by the potential for deposition of ammonium sulfate salts within the pores of the catalyst (44). These low temperature catalysts exhibit NO conversion that rises with increasing temperature, then rapidly drops off, as oxidation of ammonia to nitrogen oxides begins to dominate the reaction (see Fig. 7). 

Conversion by a reversible reaction is enhanced by starting out at high temperature and ending at low temperature if equilibrium conversion drops off at high temperature. 

This figure shows an optimum power input below this value efficiency drops off due to reduced interfacial area above this value efficiency decreases due to increased axial mixing of the continuous and dispersed phases. 

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