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T J McAvoy

Publications and source records attributed to T J McAvoy.

3 recordsLinked to original sources

Modeling human operators using neural networks.

Often in the process industries, human operators rather than mathematically based advanced algorithms are used to achieve product control. Typically, if there are three shifts of operators per day, one shift achieves superior control. If the expertise of the best operator can be captured easily and economically and made available to the other operators, significant economic benefits would accrue. This paper discusses a methodology that uses artificial neural networks for capturing the knowledge of process operators. For many operator tasks, only readily available information obtained from a process control computer is required. Once a converged network is available, a stripping technique can be employed to simplify the net and to gain knowledge about what a good operator is doing compared to a poor one. It is felt that the proposed approach is superior to traditional expert system techniques employing knowledge extraction approaches.

Humans↗

The biologic half-life of heparin.

Half-lives (t1/2s) varying from 23 min to 2.48 hr have been reported for heparin. It is shown that much of the discrepancy between authors can be attributed to methods used to analyze data. It is suggested that three terms should be carefully used, the t1/2 of bioassayed heparin concentration, the t1/2 of the extension of the clotting time, and the t 1/2 of the clotting time to differentiate among the various methods of analyzing the raw data.

Biological Assay↗

Pharmacokinetic modeling of heparin and its clinical implications.

Experimental work on heparin has indicated that its half-life increases with dose. Two models to describe heparin's pharmacokinetic behavior are proposed, and the parameters in the models are fitted to experimental data. Both models exhibit an apparent first-order decay with a "half-life" that increases with dose. It is shown that, even though both models exhibit a bolus half-life of from 1 to 2 hr, over 2 days can be required for true steady-state conditions to be achieved in these models when a constant intravenous infusion of drug is given. The clinical implications of these models are discussed. Suggestions are made for further research on heparin kinetics.

Half-Life↗