On-line computers

Figure 6.3.1 Table showing computer on-line calculation.

In both instances Bos employed a Digital Equipment Corporation PDP 11 computer on-line with a Radiometer polarographic stand with drop-life timer, a three-electrode system (DME, reference and Hg pool), two A/D and three D/A converters, together with a DEC writer and a recorder. For the "computer polarograph he used a Radiometer P04 polarograph and an external clock, and the computer had to perform the following functions ... 

In the 1980s, the advent of microprocessors speeded up the processes still further, but efforts had to be made to provide programs to collect and compute data. Today, it is possible to get a data-handhng system up and running in a few days and ensure results are computed on-line. In die area of computing, then, the time element has been greatly reduced. 

The present review is comprehensive Chemical Abstracts has been searched by indexes up to mid 1981 and by a computer on-line substructure search up to Issue 26 of Volume 96. A few more recent references are included directly from the commoner international journals. This review covers 3//-pyrazoles that have been isolated or characterized spectroscopically, although some examples that are only transient intermediates in rearrangement reactions are also mentioned. Compounds having exocyclic double bonds and the benz-fused derivatives, the 3//-indazoles, are considered to be outside its scope. 

Although the 4//-pyrazoles have not previously been reviewed, some aspects of their synthesis and chemistry have been discussed in reviews and treatises2-5 dealing with the 1H compounds. For the present review, the literature has been covered using Chemical Abstracts, by indexes up until mid 1981, and by computer on-line substructure search up to Issue 26 of Volume 96. Some more recent references have been taken directly from the commoner international journals. 

Where necessary and applicable, the specific ozone dose or the specific ozone absorption (best recorded and computed on-line) is recommended as the measure for analyzing process performance. Since in waste water ozonation, the ozone off-gas concentration often increases during the batch-treatment, the specific ozone absorption will not vary linearly with the treatment time. 

The advantage of this criterion is that it can be computed on-line, based only on temperature measurements, without the necessity of a model of the process [9]. The method uses a reconstruction of the phase space using only one state variable. This allows building a warning system for detecting a runaway situation this aspect is presented in Chapter 10. 

In this chapter Chemical Abstracts have been covered by indexes to mid-1980 and by a computer on-line search to September 1981. A few more recent references have been included directly from journals. This review covers 2H- and 3/f-pyrroles that have been isolated or characterized spectroscopically, but protonated pyrroles (which have been reviewed elsewhere ) and transient isopyrrole intermediates in the electrophilic substitution of 1 //-pyrroles are considered to be outside its scope. Pyrroles protonated at the 2-position have been isolated as stable salts. 8 Also excluded are the numerous pyrrolic compounds with exocyclic double bonds and benz-fused compounds (the 2H- and 3//-indoles). 

Reduction treatments in the XPS preparation chamber consisted of heating at 773K for 1 h of the calcined precursors, first under vacuum, to remove most of the contaminants adsorbed on the samples ( H2O, CO2, etc), and then under 10 torr of H2 for another horn at the appropriate temperatures in the range 300K-773K. The spectra were directly recorded and stored in a HP- Vectra 386 computer on line with the spectrometer where they were submitted to background subtraction (Shirley base line) and Factor Analysis to calculate % of Ce in the reduced samples as will be described elsewher[14]. 

Free computers. On-line services have competed for "eyeballs" by giving away or deeply discounting the access tool, a personal computer. 

Since about 1960 a variety of newer mathematical and computational techniques have been introduced. These are sometimes called, collectively, modem control theory . Their application to industrial process control so far has been limited. This is pardy so b use few practitioners are familiar with the technology, and partly because it is not really appropriate for many applications. Study of control systems by these method requires a fairly capable computer on-line implementation usually also requires an on-line computer. Two of the best known approaches are the (1) multivariable ffequency-respcMise method, pioneered by Rosenbrock and associates in England, and (2) the state space or state variable approach, which has been popular for aerospace and military applications. 

The Pascal code was updated to handle four channels. To follow the inspection speed all raw measuring data were captured and stored in the computer. All data for one coil could be stored in the computer memory (RAM) and transferred to the disk before inspection of the next coil. Evaluation of the data could be performed on-line or later using a special evaluation program. 

Manufacturing processes have been improved by use of on-line computer control and statistical process control leading to more uniform final products. Production methods now include inverse (water-in-oil) suspension polymerization, inverse emulsion polymerization, and continuous aqueous solution polymerization on moving belts. Conventional azo, peroxy, redox, and gamma-ray initiators are used in batch and continuous processes. Recent patents describe processes for preparing transparent and stable microlatexes by inverse microemulsion polymerization. New methods have also been described for reducing residual acrylamide monomer in finished products. 

The U.S. government, a primary sponsor of scientific and technological developments that fostered the computer and communications technologies needed by the on-line database industry, also sponsored database development projects, information usage studies, and combined computer database development—usage projects. The successors of some of these projects continue to be prominent and include DIALOG, MEDLINE, BRS, LEXIS, and the Chemical Abstracts Registry System. 

In 1982, the European Space Agency s Information Retrieval Service (ESA/IRS) introduced the ZOOM command, providing users with a mechanism to analy2e retrieved sets. In 1984, service at a baud rate of 2400 was made available by Tymnet and Telenet for pubHc access to on-line databases. In 1985, the first commercial CD-ROM drives for personal computers became available, along with the first commercial CD-ROM databases. 

GORE. The CORE Electronic Chemistry Library is a joint project of Cornell University, OCLC (On-line Computer Library Center), Bell Communications Research (Bellcore), and the American Chemical Society. The CORE database will contain the full text of American Chemical Society Journals from 1980, associated information from Chemical Abstracts Service, and selected reference texts. It will provide machine-readable text that can be searched and displayed, graphical representations of equations and figures, and full-page document images. The project will examine the performance obtained by the use of a traditional printed index as compared with a hypertext system (SUPERBOOK) and a document retrieval system (Pixlook) (6,116). 

EPIDOS issues printed and microfiche compilations of its data in addition, its database can be searched on its own computer or on several on-line host systems. In general, EPIDOS provides the most complete patent family information of any service, although Derwent tends to include more information on inteUectual (nonconvention) famUies, whereas the Erench Patent Office s EDOC file on the Questel system includes information on... 

In the earliest days of on-line databases, all three indexing types coUapsed into the third. Using older manual tools, it was difficult to coordinate more than two or three concepts, but the computer made that easier. Each concept in a search can be represented by a string of synonyms or alternatives, and searching can be done for two such parameters or more. Thus, Boolean logic expressions can easily be constmcted as follows ... 

Most aroma chemicals are relatively high boiling (80—160°C at 0.4 kPa = 3 mm Hg) Hquids and therefore are subject to purification by vacuum distillation. Because small amounts of decomposition may lead to unacceptable odor contamination, thermal stabiUty of products and by-products is an issue. Important advances have been made in distillation techniques and equipment to allow routine production of 5000 kg or larger batches of various products. In order to make optimal use of equipment and to standardize conditions for distillations and reactions, computer control has been instituted. This is particulady well suited to the multipurpose batch operations encountered in most aroma chemical plants. In some instances, on-line analytical capabihty is being developed to work in conjunction with computer controls. 

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