Computer codes, software

A CS is no more than a chunk of computer code, but the software is not isolated from the environment in which it operates. Indeed, were there no environment in which to work, the system would have nothing to do. We therefore include both the software and its surroundings among the components of the CS (Figure 9.2). 

Commercial process simulators have added optimization capabilities the specific details of which are naturally proprietary, but the general features of these codes are described in this chapter. Very large scale optimization problems of considerable economic value can be treated as shown by the examples presented earlier, and in the future improvements in power, robustness, speed of execution, and user-friendly interfaces of computers and software can be expected to expand the scope of optimization of large scale problems. 

User requirement specifications (URS) for the computerized system are provided by the pharmaceutical firm to the computer systems vendor. The vendor generates functional and design specifications as a basis for designing and coding software for the computerized system. The system is then built, together with all the interfaces to the hardware, and tested by the vendor. After installation of the computerized system, IQ, OQ, and PQ are performed at the pharmaceutical facility to verify that the system is able to meet the URS and design and functional specifications. 

A series of UTC were investigated using a combination of thermodynamic analysis and experiments. The thermodynamics of alternative cycles were analysed using Outokumpu s HSC 5.0 Chemistry software computer code version 5.11 (Outokumpu, 2002). 

Another aspect of a very different nature also merits attention. For complex reaction schemes, it can be very cumbersome to write the appropriate set of differential equations and their translation into computer code. As an example, consider the task of coding the set of differential equations for the Belousov-Zhabotinsky reaction (see Section 7.5.2.4). It is too easy to make mistakes and, more importantly, those mistakes can be difficult to detect. For any user-friendly software, it is imperative to have an automatic equation parser that compiles the conventionally written kinetic model into the correct computer code of the appropriate language [37-39],... 

Computer models, also known as math models or codes , are now frequently used in engineering, science, and many other disciplines. To run the computer model software, the experimenter provides quantitative values for various input (explanatory) variables. The code then computes values for one or more output (response) variables. For instance, in a model of Arctic sea ice (Chapman et al., 1994), the input variables included rate of snowfall and ice albedo and the code produced values of ice mass, and so on. In circuit-design models (see, for example, Aslett et al., 1998), the input variables are transistor widths and other engineering parameters, and the output variables are measures of circuit performance such as time delays. 

Document tracking CRF correction Data entry Data coding Quality control system Computer system, software Data reporting Record keeping Record retention Training initiatives... 

Although not a tutorial. Chapter 5 contains practical information about the present state of molecular modeling, where it has been, and where it appears to be headed. In the first study of its kind, the literature is analyzed to discern trends in the use of common molecular modeling packages and other computational chemistry programs. This essay, written by Dr. Donald B. Boyd, presents data on the frequency of use of software in papers published in the chemical literature from 1982 to the present. The trends will be of interest to those who develop codes and to those who buy the programs. By assessing the scientific impact of chemistry software products, the essay is a unique analysis of the computational chemistry software arena. 

It is worth noting that parameters identical to those listed in our examples can be expected only when the same computer codes are used to perform full profile refinement due to small but detectable differences in the implementation of the Rietveld method by various software developers. Furthermore, even when the same version of an identical computer program is employed to treat the same set of experimental data, small deviations may occur due to subjective decisions, such as when to terminate the refinement. In the latter case, however, the differences should be within a few least squares standard deviations. 

On the other hand, if you cannot avoid solving a set of simultaneous coupled equations because the set you are working with is tightly coupled in its initial structure and cannot be simplified even by successive substitution of one equation into another, you should read Sec. 2.7, in which computer-aided solutions are discussed. As explained in that section, you can use readily available software in computer center libraries or the computer codes in the pocket in the back of this book to solve sets of independent material balances. 

In the pocket in the back of this book are four simple Fortran generic codes that can be used to solve sets of linear and nonlinear equations on microcomputers or mainframes. Because these programs are simple, and thus may on occasion fell to solve your problem, you may want to use more polished computer codes that are available in your computer center software library. Such codes are more robust, but of course it takes more of your time to understand how to use them proficiently. 

Another attempt to formalize the distribution of software for atomic and molecular physics is the journal Computer Physics Communications which published both scientific papers and computer programs. The first issue of this journal appeared in 1969 with an article by Roberts25 on The publication of scientific FORTRAN programs , which aimed to encourage the exchange of ideas embedded in computer codes. In spite of the continued success of this journal, it has nevertheless has to be observed that none of the quantum chemical packages mentioned in our preamble or indeed similar packages have been published via this mechanism. 

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