Computer programming tasks

Software programs are usually written in a more user-friendly high-level language such as Fortran, Pascal, or C, which facilitates the tedious and labor-intensive task of writing a computer program. 

The essential differences between sequential-modular and equation-oriented simulators are ia the stmcture of the computer programs (5) and ia the computer time that is required ia getting the solution to a problem. In sequential-modular simulators, at the top level, the executive program accepts iaput data, determines the dow-sheet topology, and derives and controls the calculation sequence for the unit operations ia the dow sheet. The executive then passes control to the unit operations level for the execution of each module. Here, specialized procedures for the unit operations Hbrary calculate mass and energy balances for a particular unit. FiaaHy, the executive and the unit operations level make frequent calls to the physical properties Hbrary level for the routine tasks, enthalpy calculations, and calculations of phase equiHbria and other stream properties. The bottom layer is usually transparent to the user, although it may take 60 to 80% of the calculation efforts. 

Definition 2 Knowledge-based systems are computer programs that encode symboHc knowledge about domains and tasks, and solve problems by manipulating this knowledge using quaHtative techniques. 

Rl accomplishes this task correctiy in a fraction of the time it would take for human technicians. The savings in this case are in terms of the number of orders processed, which ultimately translates to doUars. As a final example, consider Prospector, another classic expert system built in the 1970s (4). This computer program, designed to detect commercially viable ore deposits based on geological data, correctiy identified a molybdenum ore deposit worth about 100 million. 

An expert system is a computer program that uses an experts knowledge in a particular domain to solve a narrowly focused, complex problem. An off-line system uses information entered manually and produces results in visual form to guide the user in solving the problem at hand. An on-line system uses information taken direc tly from process measurements to perform tasks automatically or instruct or alert operating personnel to the status of the plant. 

A PSA consists of many tasks and subtasks some tasks are performed in parallel others are in series. The experience of personnel, availability of data, computer programs, and manpower determine the PSA schedule. Other considerations are the age of the plant, its operational status, availability of documentation, peculiarities of the design, and the availability of the analyses of similar fiiants,... 

The IMAS technique described above is useful, in that it addresses aspects of operational skills, that is, diagnostic and problem solving abilities, that are not covered by other techniques. To that extent it can be regarded as a method of cognitive task analysis. It is not essential to use a computer program to obtain useful results. The mental models produced by IMAS can be elicited by pencil and paper methods. Nevertheless interpretation and application of the results require some expertise. 

The calculation is based on the rule of thermodynamics, which states that a system will be in equilibrium when the Gibbs free energy is at a minimum. Cl The objective then is the minimization of the total free energy of the system and the calculation of equilibria at constant temperature and volume or at constant pressure. It is a complicated and lengthy calculation but, fortunately, several computer programs are now available that considerably simplify the task. PI... 

Preference constraints preferred alternatives for equipment to use for certain tasks and for a processing sequence. Experienced operators may prefer some equipment or sequence of operations for reasons that are difficult to specify in a computer program. 

Ideally a computer system for calculation of Pourbaix diagrams would comprise a database for a wide range of compounds coupled to a computer program that would undertake the following tasks. 

But applications usually need a different type of computing environment. The reasoning task, accomplished by AI techniques, often constitutes ten percent or less of the code of an application. The majority of the code is for conventional programming tasks, such as data acquisition, data base access, numerical calculations, and graphics. In each application domain, computer hardware and software has been selected to match the needs of its tasks. In... 

In working through process control examples, we found that many calculations, data checks, rate checks and other computationally intensive tasks are done at the first level of inference. Considerations of computational efficiency led to a design utilizing two parallel processors with a shared memory (Figure 1). One of the processors is a 68010 programmed in C code. This processor performs computationally intensive, low level tasks which are directed by the expert system in the LISP processor. 

There is some disagreement within the AI community as to what qualifies a computer program to be called an "expert system". We use the term to describe a program which has the following characteristics 1) The program performs some task (e.g., HPLC methods design) which requires specialized human expertise. This human expertise often takes the form of heuristics (empirical rules of... 

Although combinatorial chemistry and HTS have offered medicinal chemists a much broader range of possibilities for lead discovery and optimization, the number of chemical compounds that can be reasonably synthesized, which is sometimes called virtual chemistry space , is stiU far beyond today s capability of chemical synthesis and biological assay. Therefore, medicinal chemists continue to face the same problem as before which compounds should be chosen for the next round of synthesis and testing For chemoinformaticians, the task is to develop and utilize various computer programs to evaluate a very large number of chemical compounds and recommend the most promising ones for bench medicinal chemists. This process can be called virtual... 

---