Petri nets were one of the earliest contributions to the theory of parallel computations and appear to be a natural way to represent the coordination of asynchronous events. Petri nets, however, are not restricted to modelling coordinates in computer systems. Any system where there are loosely connected essentially independent processes that proceed in an asynchronous marner can be modelled using Petri nets and should be useful in modelling business systems and biological systems. (MCW)

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This report is about fire research and safety and the present sate of the legislation.

MOS radiation detectors with memory have been used to time resolve a portion of an alectron beam pulse from a 704 Febetron. These detectors have the three functions of detection, memory, and readout all integrated into a single device so that time resolved detection can be performed without the requirement of realtime diagnostics. Good agreement was obtained between the waveshapes of the time resolved signal of the MOS radiation detector with memory and a real time MOS radiation detector used as a reference monitor of the Febetron's pulse. The time resolution of the detector system was 6.6 nsec. No effort was made to calibrate the output of the MOS detectors with radiation dose. (auth)

The present status of thc study of hadronic atoms using stopping kaon beams is reviewed. The kaonic atom system is chiefly discussed. Kaon - nucleus interactions from x rays, nuclear gamma rays, and electromagnetic interactions are covered. (JFP)

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From Gordon Conference; Tilton. New Hampshire, USA (22 Aug A brief discussion of magnetic field generation in laser-pellet interactions is given. Proposed target experiments to study these interactions are described in detail. Some data from typical laser--pellet interactions are theoretically derived. The data are given for various experimental parameters. (MOW)

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The Prandtl--Reuss equations used in the HEMP elastic-plastic computer program are satisfied exactly for elastic, perfectly plastic materials, and are less exact for materials that strain harden. A new method is described for incorporating strain hardening into the flow law that is exact for linear strain hardening and very nearly exact for nonlinear strain hardenlng. A tensile test of a strain-hardening material is simulated using the present method and the previous method. The original approximate method has an accumulated error of less than 2% when compared with the present method. The present method agrees with exact calculations to within 0.05%. (auth)

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ABS>The U. S. Geological Survey has identified 1.5 million acres (2800 square miles) of western lands as having a significant potential for geothermal development.'' The LASL for the past 2 years has been actively investigating the potential for and preblems associated with extracting geothermal energy from the much more numerous regions of the western United States containing hot, but essentially dry, rock at moderate depths. A recent survey reveals that about 7% of the 13-state area comprising the Western Heat Flow Province---about 95,000 square miles--is underlain, at a depth of 5 km (16,400 ft), by hot rock at temperature levels above 290 deg C (>550 deg F). In the Los Alamos concept a man- made geothermal reservoir would be formed by first drilling into suitably hot rock, and then creating a very large surface area for heat transfer using conventional hydraulic fracturing techniques developed by the oil industry. After forming a circulation loop by drilling a second hole into the top of the fractured region, the heat contained would be convected to the surface by the buoyant circulation of water, without the need for pumping. The water in the Earth loop would be maintained as a liquid throughout by pressurization …

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