Points of View

A classic in its field, giving a splendid survey of solution physical chemistry from a chemist s point of view. While seriously out of date, it nevertheless provides physical insight into how molecules "behave" in mixtures. 

Because of the differences existing between the quality of different distillation cuts and those resulting from their downstream processing, it is useful to group them according to a major characteristic. That is, they are grouped into the three principal chemical families which constitute them paraffins, naphthenes and aromatics. From a molecular point of view, their chemical reactivities follow this order ... 

Consider the molecule below. From an atomic point of view, an atom common to two structures, aromatic and naphthenic, or aromatic and paraffinic or still further naphthenic and paraffinic will be considered first of ill aromatic, then naphthenic, then paraffinic 2... 

M = molecular weight dCp = reduced Cp correction calculated fromthe Lee and Kesler model From a practical point of view, as for liquids, it is possible to calculate dC... 

For vehicles, special attention is most often focused on the knocking potential encountered at high motor speeds in excess of 4000 rpm for which the consequences from the mechanical point of view are considerable and lead very often to mechanical failure such as broken valves or pistons, and rupture of the cylinder head gasket. Between RON and MON, it is the latter which better reflects the tendency to knock at high speeds. Conversely, RON gives the best prediction of the tendency to knock at low engine speeds of 1500 to 2500 rpm. 

One remaining possibility that is less costly from an energy point of view but needs to be carefully controlled is to incorporate additives called flow improvers. These materials favor the dispersion of the paraffin crystals and in doing so prevent them from forming the large networks which cause the filter plugging. The conventional flow improvers essentially change the CFPP and pour point, but not the cloud point. They are usually copolymers, produced, for example, from ethylene and vinyl acetate monomers ... 

It should be noted finally that adding gasoline to diesel fuel which was sometimes recommended in the past to improve cold behavior conflicts with the flash point specifications and presents a serious safety problem owing to the presence of a flammable mixture in the fuel tank airspace. Adding a kerosene that begins to boil at 150°C does not have the Scune disadvantage from this point of view. 

New analytical methods. From this point of view, the development of instrument technology is emphasized that provides either gains in productivity or quality, or more advanced analyses. 

The production phase commences with the first commercial quantities of hydrocarbons ( first oil ) flowing through the wellhead. This marks the turning point from a cash flow point of view, since from now on cash is generated and can be used to pay back the prior investments, or may be made available for new projects. Minimising the time between the start of an exploration campaign and first oil is one of the most important goals in any new venture. 

The contractor is paid per foot drilled. Whilst this will provide an incentive to make hole quickly, the same risks are involved as in the turnkey contract. Footage contracts are often used for the section above the prospective reservoir where hole conditions are less crucial from an evaluation or production point of view. 

Subsea production systems provide for large savings in manpower as they are unmanned facilities. However, these systems can be subject to very high opex from the well servicing and subsea intervention point of view as expensive vessels have to be mobilised to perform the work. As subsea systems become more reliable this opex will be reduced. 

Sections 13.1 to 13.8 will deal mainly with the economics of a field development. Exploration economics is introduced in Section 13.8. The general approach to this section will be to look at an investment proposal from an operator s point of view. 

From the oil company s point of view, the balance of the money absorbed by the project (capex, opex) and the money generated (the oil company s after-tax share of the profit) yields the project cashflow. 

In statistical terms, a perceptual improvement is therefore obtained if the amplitude distribution in the filtered signal (image) is more concentrated around zero than in the raw data (contrast enhancement). A more concentrated amplitude distribution generally means smaller entropy. Thus, from an operator perception point of view, interesting results should be obtained if the raw data can be filtered to yield low entropy amplitude distributions. However, one should note that the entropy can be minimized by means of a (pathological) filter which always outputs zero or another constant value. Thus, appropriate restrictions must be imposed on the filter construction process. 

In contrast to a direct injection of dc or ac currents in the sample to be tested, the induction of eddy currents by an external excitation coil generates a locally limited current distribution. Since no electrical connection to the sample is required, eddy current NDE is easier to use from a practical point of view, however, the choice of the optimum measurement parameters, like e.g. the excitation frequency, is more critical. Furthermore, the calculation of the current flow in the sample from the measured field distribution tends to be more difficult than in case of a direct current injection. A homogenous field distribution produced by e.g. direct current injection or a sheet inducer [1] allows one to estimate more easily the defect geometry. However, for the detection of technically relevant cracks, these methods do not seem to be easily applicable and sensitive enough, especially in the case of deep lying and small cracks. 

However there is an other point of view one can consider that the data acquired while moving the probe are a mixture... 

For observers, evaluation from the point of view of software and man-machine interface was good. Less than two hours were necessary for training. 

Sealed metal-ceramic X-ray tubes are in use since the sixties. Whereas glass tubes still are the most common known form of X-ray tubes in the public, and are certainly the most used technology firom point of view of sold tubes per year, metal-ceramic X-ray tubes in lots of applications are state-of-the-art. 

From the technical and practical points of view, the efficient monitoring of rivers and water basins is a very difficult problem. This is due to the fact, that it is necessary not only to carry out a big number of water condition parameters measurements, but to follow the physical-chemical changes going on in the water as well. Such changes have a strong influence on the future state of the water basins. 

The most eomprehensive object from the diagnostic point of view still remains the human being with the variety of diagnostic parameters of his different organs, ills and ete. 

Derive Eq. II-3 using the surface tension point of view. Suggestion Consider the sphere to be in two halves, with the surface tension along the join balancing the force due to AP, which would tend to separate the two halves. 

The interface between a solid and its vapor (or an inert gas) is discussed in this chapter from an essentially phenomenological point of view. We are interested in surface energies and free energies and in how they may be measured or estimated theoretically. The study of solid surfaces at the molecular level, through the methods of spectroscopy and diffraction, is taken up in Chapter VIII. 

In the second picture, an interfacial layer or region persists over several molecular diameters due to a more slowly decaying interaction potential with the solid (note Section X-7C). This situation would then be more like the physical adsorption of vapors (see Chapter XVII), which become multilayer near the saturation vapor pressure (e.g.. Fig. X-15). Adsorption from solution, from this point of view, corresponds to a partition between bulk and interfacial phases here the Polanyi potential concept may be used (see Sections X-7C, XI-1 A, and XVII-7). 

These concluding chapters deal with various aspects of a very important type of situation, namely, that in which some adsorbate species is distributed between a solid phase and a gaseous one. From the phenomenological point of view, one observes, on mechanically separating the solid and gas phases, that there is a certain distribution of the adsorbate between them. This may be expressed, for example, as ria, the moles adsorbed per gram of solid versus the pressure P. The distribution, in general, is temperature dependent, so the complete empirical description would be in terms of an adsorption function ria = f(P, T). 

Statistical Thermodynamics of Adsorbates. First, from a thermodynamic or statistical mechanical point of view, the internal energy and entropy of a molecule should be different in the adsorbed state from that in the gaseous state. This is quite apart from the energy of the adsorption bond itself or the entropy associated with confining a molecule to the interfacial region. It is clear, for example, that the adsorbed molecule may lose part or all of its freedom to rotate. 

Vibrational energy states are too well separated to contribute much to the entropy or the energy of small molecules at ordinary temperatures, but for higher temperatures this may not be so, and both internal entropy and energy changes may occur due to changes in vibrational levels on adsoiption. From a somewhat different point of view, it is clear that even in physical adsorption, adsorbate molecules should be polarized on the surface (see Section VI-8), and in chemisorption more drastic perturbations should occur. Thus internal bond energies of adsorbed molecules may be affected. 

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