Slowing-down

In spite of considerable development of thermodynamics and molecular theory, most of the methods used today are empirical and their operation requires knowledge of experimental values. However, the rate of accumulation of experimental data seems to be slowing down even though the need for precise values is on the rise. It is then necessary to rely on methods said to be predictive and which are only estimates. 

The pour point of crude oils is measured to give an approximate indication as to their pumpability . In fact, the agitation of the fluid brought on by pumping can stop, slow down or destroy the formation of crystals, conferring on the crude additional fluidity beyond that of the measured pour point temperature. 

When drilling through normally pressured formations, the mud weight in the well is controlled to maintain a pressure greater than the formation pressure to prevent the influx of formation fluid. Atypical overbalance would be in the order of 200 psi. A larger overbalance would encourage excessive loss of mud Into the formation, slow down... 

Once the bubble point is reached, solution gas starts to become liberated from the oil, and since the liberated gas has a high compressibility, the rate of decline of pressure per unit of production slows down. 

By plotting the cumulative resource weighting against time, the planned progress of the project can be illustrated, as shown in Figure 12.8. This type of plot Is often referred to as an S -Curve, as projects often need time to gain momentum and slow down towards completion (unlike the example shown). 

A considerable percentage (40% - 85%) of hydrocarbons are typically not recovered through primary drive mechanisms, or by common supplementary recovery methods such as water flood and gas injection. This is particularly true of oil fields. Part of the oil that remains after primary development is recoverable through enhanced oil recovery (EOR) methods and can potentially slow down the decline period. Unfortunately the cost per barrel of most EOR methods is considerably higher than the cost of conventional recovery techniques, so the application of EOR is generally much more sensitive to oil price. 

Forward recoil spectrometry (FRS) [33], also known as elastic recoil detection analysis (ERDA), is fiindamentally the same as RBS with the incident ion hitting the nucleus of one of the atoms in the sample in an elastic collision. In this case, however, the recoiling nucleus is detected, not the scattered incident ion. RBS and FRS are near-perfect complementary teclmiques, with RBS sensitive to high-Z elements, especially in the presence of low-Z elements. In contrast, FRS is sensitive to light elements and is used routinely in the detection of Ft at sensitivities not attainable with other techniques [M]- As the teclmique is also based on an incoming ion that is slowed down on its inward path and an outgoing nucleus that is slowed down in a similar fashion, depth infonuation is obtained for the elements detected. 

Near critical points, special care must be taken, because the inequality L will almost certainly not be satisfied also, cridcal slowing down will be observed. In these circumstances a quantitative investigation of finite size effects and correlation times, with some consideration of the appropriate scaling laws, must be undertaken. Examples of this will be seen later one of the most encouraging developments of recent years has been the establishment of reliable and systematic methods of studying critical phenomena by simulation. 

TlyperCi hem updates the screen diirin g a trajectory at regular in ter-vals so yon can visiiali/e the irajectory. Since this screen update may slow down a trajectory If it occurs too frequently, yon c.an specify the duration of the Screen Refresh period At.,. The screen updates at ilines tQ, Iq + Atj, to + 2Atj, etc. The Screen Refresh period is specified in the Molecular Dynamics options dialog box by n 5 data steps, i.e. as a m iiliiplc of the data collection period, At5 = n 5 At2-... 

Deuterium is used as a moderator to slow down neutrons. Tritium atoms are also present but in much smaller proportions. Tritium is readily produced in nuclear reactors and is used in the production of the hydrogen (fusion) bomb. It is also used as a radioactive agent in making luminous paints, and as a tracer. 

One way in which the step of the reaction in which the proton is lost might be slowed down, and perhaps made kinetically important (with i), would be to carry out nitration at high acidities. Nitration of pentadeuteronitrobenzene in 97-4% sulphuric acid failed to reveal such an effect. In fact, nitrations under a variety of conditions fail to show a kinetic isotope effect. 

The rate of ring flipping can be slowed down by lowering the temperature At tern peratures on the order of — 100°C separate signals are seen for the axial and equatorial protons of cyclohexane... 

The concentrations of both A and B, hence the reaction slows down as the conversion to polymer progresses, and. ... 

Inhibitors and retarders differ in the extent to which they interfere with polymerization, and not in their essential activity. An inhibitor is defined as a substance which blocks polymerization completely until it is either removed or consumed. Thus failure to totally eliminate an inhibitor from purified monomer will result in an induction period in which the inhibitor is first converted to an inert form before polymerization can begin. A retarder is less efficient and merely slows down the polymerization process by competing for radicals. 

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