A proof technique for communicating sequential processes

Summary Proof rules are presented for an extension of Hoare's Communicating Sequential Processes. The rules deal with total correctness; all programs terminate in the absence of deadlock. The commands send and receive are treated symmetrically, simplifying the rules and allowing send to appear in guards. Also given are sufficient conditions for showing that a program is deadlock-free. An extended example illustrates the use of the technique.This research was supported in part by the National Science Foundation under grant MCS-7622360.     

Process-water residues in fireclay and magnesia refractory production

Conclusions Particle size analyses of process water residues from fireclay and magnesia refractory production enable settlement rates to be established within water cleaning plant.From wet volume tests on residues it is possible to work out sludge volumes and cleaning cycle times for settlement plantl.Residues consisting of grog, magnesite, chromite, magnesite-chromite mixtures, and grog-clay mixtures with seven-tenths grog or over, should be removed mechanically from a horizontal settling tank after 1 day or longer, e.g., with a bucket crane or similar mechanism. A clay residue should be pumped out, but if it stands for 2 days or more it may be dug out.A coagulated residue of clay or a clay-grog mixture with seven tenths clay or more should be pumped out, but a 73 clay-grog mixture can be removed mechanically after settling for 3 days.Coagulated grog, magnesite, or chromite residues can be moved hydraulically for the first day, but if they stand longer they must be moved mechanically. If sludge is to be moved mechanically from a settling tank the clean water over it must be removed first, and appropriate equipment must be allowed for. If a sludge is to be removed hydraulically it must first be stirred up in some way.Translated from Ogneupory, No. 2, pp. 11–16, February, 1969.