Intent

As the feed composition approaches a plait point, the rate of convergence of the calculation procedure is markedly reduced. Typically, 10 to 20 iterations are required, as shown in Cases 2 and 6 for ternary type-I systems. Very near a plait point, convergence can be extremely slow, requiring 50 iterations or more. ELIPS checks for these situations, terminates without a solution, and returns an error flag (ERR=7) to avoid unwarranted computational effort. This is not a significant disadvantage since liquid-liquid separations are not intentionally conducted near plait points. 

Calculating the hydrate formation temperature is essential when one needs to guard against equipment and line plugging that can result when wet gas is cooled, intentionally or not, below 30°C. 

Design procedures are developed with the intention of improving the safety of equipment. Tools used in this step are hazard and operability studies and quantitative risk analysis (ORA). The following scheme may be used ... 

The general invariant pattern recognition problem is to construct a system which takes as input an element/of V and computes a value s(f), with the intention that s(f) = c(f) for all f V. 

It can easily be shown that an experimentally generated curve coincides with the synthetically generated DGS curve having applicable corrections (transfer loss and sound attenuation) with acceptable tolerances. However, our intention is not to replace the reference block method by the DGS method. In practical application you may encounter many cases, where only the reference block method can be applied, e.g. ... 

Classification Societies exist to promote the safe construction of ships and to protect that condition throughout the life of the vessel. One of the tools available to shipbuilders, shipowners and surveyors that can be used to achieve these aims is Non-Destructive Examination (NDE). The intent of this presentation is to describe the application of NDE to hull structure during construction and also during periodic surveys as seen from the viewpoint of the Classification Surveyor. 

Our intention is to give a brief survey of advanced theoretical methods used to detennine the electronic and geometric stmcture of solids and surfaces. The electronic stmcture encompasses the energies and wavefunctions (and other properties derived from them) of the electronic states in solids, while the geometric stmcture refers to the equilibrium atomic positions. Quantities that can be derived from the electronic stmcture calculations include the electronic (electron energies, charge densities), vibrational (phonon spectra), stmctiiral (lattice constants, equilibrium stmctiires), mechanical (bulk moduli, elastic constants) and optical (absorption, transmission) properties of crystals. We will also report on teclmiques used to study solid surfaces, with particular examples drawn from chemisorption on transition metal surfaces. 

The acronym LASER (Light Amplification via tire Stimulated Emission of Radiation) defines the process of amplification. For all intents and purjDoses tliis metliod was elegantly outlined by Einstein in 1917 [H] wherein he derived a treatment of the dynamic equilibrium of a material in a electromagnetic field absorbing and emitting photons. Key here is tire insight tliat, in addition to absorjDtion and spontaneous emission processes, in an excited system one can stimulate tire emission of a photon by interaction witli tire electromagnetic field. It is tliis stimulated emission process which lays tire conceptual foundation of tire laser. 

Semiconductors are a class of materials whose conductivity, while highly pure, varies witli temperature as exp (-Ag//cg7), where is tlie size of a forbidden energy gap. The conductivity of semiconductors can be made to vary over orders of magnitude by doping, tlie intentional introduction of appropriate impurities. The range in which tlie conductivity of Si can be made to vary is compared to tliat of typical insulators and metals in figure C2.16.1. 

In n type semiconductors, electrons are tire majority carriers. Holes will also be present tlirough accidental incoriioration of acceptor impurities or, more importantly, tlirough tlie intentional creation of electron-hole pairs. Holes in n type and electrons in p type semiconductors are minority carriers. 

Intrinsic defects (or native or simply defects ) are imperfections in tire crystal itself, such as a vacancy (a missing host atom), a self-interstitial (an extra host atom in an otherwise perfect crystalline environment), an anti-site defect (in an AB compound, tliis means an atom of type A at a B site or vice versa) or any combination of such defects. Extrinsic defects (or impurities) are atoms different from host atoms, trapped in tire crystal. Some impurities are intentionally introduced because tliey provide charge carriers, reduce tlieir lifetime, prevent tire propagation of dislocations or are otlierwise needed or useful, but most impurities and defects are not desired and must be eliminated or at least controlled. 

The JCAMP-DX file format is split into the sections CORE and NOTES with the intention of keeping less important data separated from the essential content. The CORE itself contains CORE HEADER and CORE DATA. NOTES are just between HEADER and DATA (see Figure 4-4 for an example). 

The following table can only give a short overview of the most important or most used databases in Chemistiy and Biochemistry, It has no intention to be comprehensive or complete since the scenery of databases is changing very fast. 

The method for calculating effective polarizabilitie.s wa.s developed primarily to obtain values that reflect the stabilizing effect of polarizability on introduction of a charge into a molecule. That this goal was reached was proven by a variety of correlations of data on chemical reactivity in the gas phase with effective polarizability values. We have intentionally chosen reactions in the gas phase as these show the predominant effect of polarizability, uncorrupted by solvent effects. 

Extensive use of cross-terms is made by Haglcr s quantum mechanically derived force field CFF, because one of the intentions of this type of PEF is to obtain ac-... 

In other approaches, chirahty descriptors were developed with the intention not of measuring chirality but of describing chirality in a way that correlations could be established with observable properties. These descriptors have different values for opposite enantiomers, in order that chirality-dependent properties can be predicted from them. They are usually multidimensional. 

Next, the power and the benefits of reaction center or reaction sub.structurc searching (see Section 3.3) will be illustrated. Figure 10.3-26 shows some of the hits obtained in a search for reactions that form a C-C bond. Intentionally, only the names of the starting materials and products of these reactions are given in order to emphasize that the common feature of these reactions cannot be derived from coding chemical compounds by name. Only a search by reaction center can expose the similarity in these reactions. The next logical steps would then be to explore whether these reactions have more in common than just forming a C-C bond. 

Because of the complexity of the problem and the large amount of program development work that has to go into a synthesis design system, only a few groups worldwide have been active in this area. Here, we mention only a selection of the major ideas and achievements in this area. It is not the intention to give a comprehensive overview. For this, interested readers can consult Chapter X, Section 3.2 in the Handbook. This chapter presents one such system, the WODCA program, in greater detail. 

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