Reasons for

This is the reason for numerous studies that have been conducted with X-ray diffraction, a method not described here. Suffice it to say that X-ray diffraction is useful in providing values of aromaticity, the distances between layers and between aliphatic chains, the thickness of particles, etc. 

Formulation consists of mixing the effluent streams coming from the different refining units in order to obtain products conforming to the specifications. It is also at this point that additives are added, the reasons for which and whose action will be described later. One can easily see that as far as octane numbers are concerned, or for that matter any other parameter, the... 

The potential advantages of LPG concern essentially the environmental aspects. LPG s are simple mixtures of 3- and 4-carbon-atom hydrocarbons with few contaminants (very low sulfur content). LPG s contain no noxious additives such as lead and their exhaust emissions have little or no toxicity because aromatics are absent. This type of fuel also benefits often enough from a lower taxation. In spite of that, the use of LPG motor fuel remains static in France, if not on a slightly downward trend. There are several reasons for this situation little interest from automobile manufacturers, reluctance on the part of automobile customers, competition in the refining industry for other uses of and fractions, (alkylation, etherification, direct addition into the gasoline pool). However, in 1993 this subject seems to have received more interest (Hublin et al., 1993). 

Originally, mud was made from clay mixed with water, a simple system. Today the preparation and treatment of drilling fluid has reached a sophistication which requires specialist knowledge. The reason for this becomes clear if we consider the properties expected. 

Most companies hire a drilling contractor to supply equipment and manpower rather than having their own rigs and crews. The reasons for this are threefold ... 

In gas reservoir engineering, the gas expansion factor, E, is commonly used. However, in oil reservoir engineering it is often more convenient to refer to the gas formation volume factor which is the reciprocal E, and is expressed in units of scf/stb (using field units). The reason for this will become apparent in Section 8. 

The aquifer response (or impact of the water injection wells) may maintain the reservoir pressure close to the initial pressure, providing a long plateau period and slow decline of oil production. The producing GOR may remain approximately at the solution GOR if the reservoir pressure is maintained above the bubble point. The outstanding feature of the production profile is the large increase in water cut over the life of the field, which is usually the main reason for abandonment. Water cut may exceed 90% in the final part of the field life. As water cut increases, so oil production typically declines a constant gross liquids (oil plus water) production may be maintained. 

Facilities for the treatment and compression of gas have already been described in earlier sections. However, there are a number of differences in the specifications for injected gas that differ from those of export gas. Generally there are no technical reasons for specifications on hydrocarbon dew point control (injected gas will get hotter not cooler) although it may be attractive to remove heavy hydrocarbons for economic reasons. Basic liquid separation will normally be performed, and due to the high pressures involved it will nearly always be necessary to dehydrate the gas to avoid water drop out. 

The failure mode of an equipment item describes the reason for the failure, and is often determined by analysing what causes historic failures in the particular item. This is another good reason for keeping records of the performance of equipment. For example, if it is recognised that a pump typically fails due to worn bearings after 8,000 hours in operation, a maintenance strategy may be adopted which replaces the bearings after 7,000 hours if that pump is a critical item. If a spare pump is available as a back-up, then the policy may be to allow the pump to run to failure, but keep a stock of spare parts to allow a quick repair. 

It is good practice to reviewa project on completion and record the reasons for departure between planned and actual performance. Where lessons can be learned, or opportunities exploited, they should be incorporated into project management guidelines. Some companies hold post project sessions with their contractors to explore better ways of handling particular issues, especially when there is an expectation of additional shared activities. 

The physical reasons for the benefits of EOR on recovery are discussed in Section 8.7, and the following gives a qualitative description of how the techniques may be applied to manage the production decline period of a field. 

The reasons for those lowfrequent emission events are flow processes during the child mold filling or friction processes between the casting part and the child mold. Investigations where, using radioscopy, hot tears could be detected show that the time based... 

The main reasons for the application of a pneumatic test in conjunction with an AE are... 

Another reason for a deviation between measured and calculated data is the phase shift along the extension of the crack in z-direction. We will discuss this problem in more detail in the following parts. 

It has become clear that scatter between measurements has to be reduced. At present the work is focused on the understanding of the reason for scatter and how to compensate for it. 

Our company is dedicated solely to metal-ceramic X-ray tubes since 25 years over this time, we have made lots of different tube models especially for tyre inspection systems. The major reasons for the use of metal-ceramic tubes in this inspection technology are robustness, their small and individual shapes, and the frequent need for modifications of their design due to custom designed systems. 

Other limitation for the spatial resolution can be found in the detector. A limited number of pixels in the camera array can be a reason for pure resolution in the case of a big field of view. For example, if field of view should be 10 by 10 nun with camera division 512x512 pixels the pixel size will be approximately 20 microns. To improve the relation of the field of view and the spatial resolution a mega-pixel sensor can be used. One more limitation for the spatial resolution is in mechanical movement (rotation) of the object, camera and source. In the case of a mechanical movement all displacements and rotations should be done with accuracy better than the spatial resolution in any tested place of the object. In the case of big-size assemblies and PCB s it is difficult to avoid vibrations, axle play and object non-planarity during testing. 

The reason for these results is that the intensity of the leakage field and the RMS error used depend strongly on the parameter c and the crack width, and to a lesser extent on the depth profile of the crack. Also, the distribution of the density of the leakage field is measured over the centre of the crack and correspondingly changes more by varying of dj and dj rather than of d, dj, dj and d . 

If the signal features already have been chosen, another important problem is how to optimally combine these features in order to obtain the best estimate of the material property. The physical reasoning will give us ideas of how to combine the features but there will be no guarantee that we are using the chosen features in an optimal way. One reason for this is that we have to take into account the uncertainties that always are present in measurement data. 

Alternatively, those at the other end of the market speak proudly of their own exclusive server But the true financial costs of this can range from US 30-100 thousand annually. Costs increase (rapidly) with the sophistication of functions offered. On the other hand, increased function is the reason for buying a server ... 

In actual practice, a weight W is obtained, which is less than the ideal value W. The reason for this becomes evident when the process of drop formation is observed closely. What actually happens is illustrated in Fig. 11-10. The small drops arise from the mechanical instability of the thin cylindrical neck that develops (see Section II-3) in any event, it is clear that only a portion of the drop that has reached the point of instability actually falls—as much as 40% of the liquid may remain attached to the tip. 

As might be expected, this simple picture does not hold perfectly. The coefficient of friction tends to increase with increasing velocity and also is smaller if the pavement is wet [14]. On a wet road, /x may be as small as 0.2, and, in fact, one of the principal reasons for patterning the tread and sides of the tire is to prevent the confinement of a water layer between the tire and the road surface. Similarly, the texture of the road surface is important to the wet friction behavior. Properly applied, however, measurements of skid length provide a conservative estimate of the speed of the vehicle when the brakes are first applied, and it has become a routine matter for data of this kind to be obtained at the scene of a serious accident. 

Several factors detennine how efficient impurity atoms will be in altering the electronic properties of a semiconductor. For example, the size of the band gap, the shape of the energy bands near the gap and the ability of the valence electrons to screen the impurity atom are all important. The process of adding controlled impurity atoms to semiconductors is called doping. The ability to produce well defined doping levels in semiconductors is one reason for the revolutionary developments in the construction of solid-state electronic devices. 

The perturbation theory described in section Al.5.2,1 fails completely at short range. One reason for the failure is that the multipole expansion breaks down, but this is not a fiindamental limitation because it is feasible to construct a non-expanded , long-range, perturbation theory which does not use the multipole expansion [6], A more profound reason for the failure is that the polarization approximation of zero overlap is no longer valid at short range. 

Perhaps the most intensely studied interface is that between a solid and vacuum, i.e. a surface. There are a number of reasons for this. For one, it is more experunentally accessible than other interfaces. In addition, it is... 

It is important to recognize the approximations made here the electric field is supposed to be sulficiently small so that the equilibrium distribution of velocities of the ions is essentially undisturbed. We are also assuming that the we can use the relaxation approximation, and that the relaxation time r is independent of the ionic concentration and velocity. We shall see below that these approximations break down at higher ionic concentrations a primary reason for this is that ion-ion interactions begin to affect both x and F, as we shall see in more detail below. However, in very dilute solutions, the ion scattering will be dominated by solvent molecules, and in this limiting region A2.4.31 will be an adequate description. 

The reason for this enliancement is intuitively obvious once the two reactants have met, they temporarily are trapped in a connnon solvent shell and fomi a short-lived so-called encounter complex. During the lifetime of the encounter complex they can undergo multiple collisions, which give them a much bigger chance to react before they separate again, than in the gas phase. So this effect is due to the microscopic solvent structure in the vicinity of the reactant pair. Its description in the framework of equilibrium statistical mechanics requires the specification of an appropriate interaction potential. 

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