Presentation problems

Case-Based Reasoning. Case-Based Reasoning (CBR) systems base their solutions on previously solved problems (cases) which are stored in a case-base [Watson Marir, 1994]. When a new problem is presented to a CBR system a similar case(s) is/are retrieved from the case-base. Depending on the differences between the retrieved and the presented problem the retrieved solution may have to be more or less adapted to obtain a solution to the new problem. The solved problem may be retained in the case base if deemed useful. 

Comparison with the PY equation shows that the HNC equation is nonlinear, and this does present problems in numerical work, as well as preventing any analytical solutions being developed even m the simplest of cases. 

While we can make the trans nitro-alkene B easily enough, the cis-nitro alkene A would present problems, so let s try route b ... 

Some work has been done on the nitration of polyphenyls the case of -terphenyl presents problems in connection with isomer distributions similar to those met with that of biphenyl. 

Using standard-state potentials to construct a ladder diagram can present problems if solutes are not at their standard-state concentrations. Because the concentrations of the reduced and oxidized species are in a logarithmic term, deviations from standard-state concentrations can usually be ignored if the steps being compared are separated by at least 0.3 A trickier problem occurs when a half-reaction s potential is affected by the concentration of another species. For example, the potential for the following half-reaction... 

Sample Preservation Without preservation, many solid samples are subject to changes in chemical composition due to the loss of volatile material, biodegradation, and chemical reactivity (particularly redox reactions). Samples stored at reduced temperatures are less prone to biodegradation and the loss of volatile material, but fracturing and phase separations may present problems. The loss of volatile material is minimized by ensuring that the sample completely fills its container without leaving a headspace where gases can collect. Samples collected from materials that have not been exposed to O2 are particularly susceptible to oxidation reactions. For example, the contact of air with anaerobic sediments must be prevented. 

We might be tempted to equate the forces given by Eqs. (9.61) and (3.38) and solve for a from the resulting expression. However, Eq. (3.38) is not suitable for the present problem, since it was derived for a cross-linked polymer stretched in one direction with no volume change. We are concerned with a single, un-cross-linked molecule whose volume changes in a spherically symmetrical way. The precursor to Eq. (3.36) in a more general derivation than that presented in Chap. 3 is... 

Equation (1.34) gives the probability that a molecule will be displaced a distance x after v steps of length 1. Adapting this to the present problem, we use Eq. (9.81) to replace u and write... 

There are, however, continuing difficulties for catalytic appHcations of ion implantation. One is possible corrosion of the substrate of the implanted or sputtered active layer this is the main factor in the long-term stabiHty of the catalyst. Ion implanted metals may be buried below the surface layer of the substrate and hence show no activity. Preparation of catalysts with high surface areas present problems for ion beam techniques. Although it is apparent that ion implantation is not suitable for the production of catalysts in a porous form, the results indicate its strong potential for the production and study of catalytic surfaces that caimot be fabricated by more conventional methods. 

Ethjlben ne Synthesis. The synthesis of ethylbenzene for styrene production is another process in which ZSM-5 catalysts are employed. Although some ethylbenzene is obtained direcdy from petroleum, about 90% is synthetic. In earlier processes, benzene was alkylated with high purity ethylene in liquid-phase slurry reactors with promoted AlCl catalysts or the vapor-phase reaction of benzene with a dilute ethylene-containing feedstock with a BF catalyst supported on alumina. Both of these catalysts are corrosive and their handling presents problems. 

Although the reaction rate of ethylene and various copolymers differs substantially, the reaction constants can be estabUshed by using an arbitrary value of 1 for ethylene (5). Thus, a value of 0.1 would indicate that the comonomer reacts at 10 times the rate of ethylene. However, the wide range of reaction rates can present problems not only in determining the comonomer content of the final product but also in producing a homogeneous product (4,6). 

Most new patent cases of interest are pubHshed by at least one of the U.S., European, or Japanese patent offices, and WIPO (PCT). Japan presents problems for those not able to read Japanese, but the U.S. Official Ga tte (with representative claims) and PCT Ga tte (with English-language abstracts) can be in one s hands within a week of patent pubHcation. Similar timing is available for the European Patent Office bulletin which contains trilingual tides and the on-line EPAT file and various CD-ROM products. A highly effective alerting program can be developed from a combination of these methods. 

Spectroscopy. Infrared spectroscopy (48) permits stmctural definition, eg, it resolves the 2,2 - from the 2,4 -methylene units in novolak resins. However, the broad bands and severely overlapping peaks present problems. For uncured resins, nmr rather than ir spectroscopy has become the technique of choice for microstmctural information. However, Fourier transform infrared (ftir) gives useful information on curing phenoHcs (49). Nevertheless, ir spectroscopy continues to be used as one of the detectors in the analysis of phenoHcs by gpc. 

When the dryer is seen as a heat exchanger, the obvious perspective is to cut down on the enthalpy of the air purged with the evaporated water. Minimum enthalpy is achieved by using the minimum amount of air and cooling as low as possible. A simple heat balance shows that for a given heat input, minimum air means a high inlet temperature. However, this often presents problems with heat-sensitive material and sometimes with materials of constmction, heat source, or other process needs. AH can be countered somewhat by exhaust-air recirculation. 

The most widely used austenitic stainless steel is Type 304, known as 18—8. It has excellent corrosion resistance and, because of its austenitic stmcture, excellent ductihty. It may be deep-drawn or stretch formed. It can be readily welded, but carbide precipitation must be avoided in and near the weld by cooling rapidly enough after welding. Where carbide precipitation presents problems. Types 321, 347, or 304L may be used. The appHcations of Types 304 are wide and varied, including kitchen equipment and utensils, dairy installations, transportation equipment, and oil-, chemical-, paper- (qv), and food-processing (qv) machinery. 

Fig. 10. Two materials, A and B, have statistically similar LD q values but, because of differences ia the slopes of the dose—mortaUty regression lines, there are significant differences ia mortaUty at the LD q and LD jq levels. Material A is likely to present problems with acute overexposure to large numbers of iadividuals ia an exposed population when lethal levels are reached. With Material B, because of the shallow slope, problems may be encountered at low...

Other 2,3-Diphosphoglycerate Pocket Cross-Linkers. The reactivity of the valine NAl(l)a and lysine EF6(82)p residues in the 2,3-DPG pocket shown by NFPLP and (bis-PL)P4 has stimulated the search for other reagents that react similarly but have potential for greater efficiency and ease of scaleup. The systematic study of four different dicarboxyhc acid derivatives, cross-linked in both oxygenated and deoxygenated conditions, has been reported (92). Each of these derivatives presents problems in purification, and proof of the sites of reaction is tedious. 

According to Phannacopoeia, methods of dmg quality control must be validated. But now there no justified acceptability criteria and standai dized validation procedures. It presents problems for analysts during method development. 

For most applications, the balanced, o-ring cartridge seal will adequately handle every pump, liquid, and condition in a modern industrial process plant. There are, however, some industrial pumping applications that will present problems to even the best of mechanical seals. Should one of these applications cause the seal to give less than desirable performance, the next step to take in extending the service life of the seal (and ultimately the pump) is to install some type of environmental control to protect and isolate the seal components from the fluid. Let s consider some difficult sealing applications. 

Field coating of welds has always presented problems. Straw and jute with a greasy material was employed in 1910, but this later saponified in the soil. By chance the pharmacist Schade of Berlin learned of this problem and recommended the use of petroleum jelly in a bandage-like application. Hot-applied bitumen bands, as used by pipe works since 1928. proved to be most durable. Since 1930, electrical measuring methods have played an important part in research into insulation bands and pipe coverings carried out by the Gas Institute in Karlsruhe, the present-day Engier-Bunte Institute 18). 

The wire cable may present problems using either manual or automated assembly. 

Unfortunately, the design of the wire could not be changed to a more simple arrangement, for example using a spade connector integrated with a recess for the O-ring. The wire is part of the customer s requirements and will inevitably present problems using... 

The loeation of the persons required in the team ean also present problems. Not only are designers and produetion engineers found in different funetional departments, but they ean frequently be on different sites and are in the ease of sub-eontraetors in different eompanies. 

This equipment presents problems in estimating preliminary costs, since there is seldom enough information in-house to make good correlations. Vendors are by far the best source of costs. Guthrie (Reference 23) discusses the complexities of estimating high-pressure equipment and presents some cost data. 

Fluorination presents problems of the other extreme. Both steps in the substitution chain reaction are so exothermic that the reaction is violent if not performed under carefully controlled conditions. Furthermore, fluorine atoms are capable of cleaving carbon-carbon bonds ... 

Butane itself is eonsidered to be insoluble in water. Exposures of up to 5% for 2 hours appear not to present problems. The TLV is 800 ppm. The relationship between pressure and temperature is given by Figure 9.6. 

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