Searches Organization

As explained in Chapter 9, a branch-and-bound enumeration is nothing more than a search organized so that certain portions of the possible solution set are deleted from consideration. A tree is formed of nodes and branches (arcs). Each branch in the tree represents an added or modified inequality constraint to the problem defined for the prior node. Each node of the tree itself represents a nonlinear optimization problem without integer variables. 

It makes little sense to search organic and metal organic structures database if the material from which powder diffraction data were collected is inorganic, and vice versa. 

Usually an Internet user learns after a while where to go for specific information The Browser provides a bookmark tlmction where all these addresses can be organized by different subjects Typical bookmark folders are Societies, Companies, Journals, Institutes, Databases, Search engines The NDTnet Journal provides a virtual library that makes it easy for newcomers to find NDT sites. Unfortunately, some sites provide a lot of information but do not offer a search function. 

On NDTnet both retrieval methods are optimally combined, however that is only successfully because the content on the server is extensive and valuable (Table 2). A full text search with all advanced search features is available and the site also provides a table of contents for each month and archives are organized in subjects together with an alphabetical index. 

Most database users do not know how the data are organized in a database system (DBS) they depend solely on the application programs. This is sufficient for most database searches where users can receive large amounts of results quickly and easily, e.g., on literature or other information. Nevertheless, a basic knowledge on where and how to find deeper or more detailed information is quite useful. Due to their complex nature, comprehensive searches (e.g., for processes or patents) are not recommended for beginners. However, most local (in-house), online, and CD-ROM databases provide extensive tutorials and help functions that are specific to the database, and that give a substantial introduction into database searching. 

As can be seen in Figure 5-17, some search fields (e.g., POW [= Power]) do not need any input in the search mask this means that all entries with any content of those Helds are retrieved. However, other fields always demand an input. In case the input is omitted (for example for the decadic logarithm of the partition coefficient), a corresponding error message results. Since the PCB are more soluble in the organic phase, the input of that Field is restricted to positive values. 

Woodruff and co-workers introduced the expert system PAIRS [67], a program that is able to analyze IR spectra in the same manner as a spectroscopist would. Chalmers and co-workers [68] used an approach for automated interpretation of Fourier Transform Raman spectra of complex polymers. Andreev and Argirov developed the expert system EXPIRS [69] for the interpretation of IR spectra. EXPIRS provides a hierarchical organization of the characteristic groups that are recognized by peak detection in discrete ames. Penchev et al. [70] recently introduced a computer system that performs searches in spectral libraries and systematic analysis of mixture spectra. It is able to classify IR spectra with the aid of linear discriminant analysis, artificial neural networks, and the method of fe-nearest neighbors. 

Some of the other features of this program are the ability to compute transition states, coordinate driving, conformation searches, combinatorial tools, and built-in visualization. The builder includes atoms and fragments for organics, inorganics, peptides, nucleotides, chelates, high-coordination geometries, and... 

A major trend in organic synthesis, however, is the move towards complex systems. It may happen that one needs to combine a steroid and a sugar molecule, a porphyrin and a carotenoid, a penicillin and a peptide. Also the specialists in a field have developed reactions and concepts that may, with or without modifications, be applied in other fields. If one needs to protect an amino group in a steroid, it is advisable not only to search the steroid literature but also to look into publications on peptide synthesis. In the synthesis of corrin chromophores with chiral centres, special knowledge of steroid, porphyrin, and alkaloid chemistry has been very helpful (R.B. Woodward, 1967 A. Eschenmoser, 1970). 

The Novosibirsk Institute of Organic Chemistry has developed a method for computer-aided retrieval of stmctural information from H-nmr using its database of 50,000 spectra (72). Eraser WUHams Ltd. (Scientific Systems) has special software to search its E-nmr database (73). Protein nmr data have been compiled into a relational database at the University of Wisconsin (74). 

REACCS is organized iato six operational modes MAIN and BUILD, which are used to draw molecular stmctures, build reactions, and constmct graphic queries and SEARCH, VIEWLIST, PLOT, and EORMS, which are used to create custom forms to display data associated with reactions and molecules. Each of the modes provides a characteristic menu and a set of options, which normally perform tasks that relate to the general function of that mode. 

The following chemical databases are available for searching in MACCS-II. ChemicalDirectoy Database contains a combined catalogue of 66 commercial suppHers of more than 77,000 organic chemicals. AL4.CCS-II Drug Data eport based on the Prous Dmg Data Report, includes 39,000 compounds with information on therapeutic indication, biological action, phase of development, related patents, and Hterature references. MUSE Database the tutorial database for MACCS-II, contains over 100 compounds. 

Polyphenyl Ethers. These very stable organic stmctures have been synthesized in a search for lubricants to meet the needs of future jet engines, nuclear power plants, high temperature hydrauHc components, and high temperature greases (49). A typical formula is C H (—OC H ... 

The wide range of soHd lubricants can generally be classified as either inorganic compounds or organic polymers, both commonly used in a bonded coating on a matching substrate, plus chemical conversion coatings and metal films. Since solid-film lubricants often suffer from poor wear resistance and inabihty to self-heal any breaks in the film, search continues for improved compositions. 

Infringement Searching. An individual or organization found to be infringing the patent rights of others is subject to penalties that can be extremely costiy. It is essential for anyone contemplating a commercial venture that is technology-dependent to find out first whether or not the proposed venture falls within the area covered by adversely held patents. 

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