Abstract: Point attack tools are being increasingly used as the cutting elements of roadheaders. The paper summarizes the results of recent research at the mining research and development establishment on their behaviour in cutting rock. For comparable cuts, sharp point attack tools require higher forces than sharp wedge-shaped tools. As both types become worn, the ranking order is reversed. For all tools, the deeper the cut the greater the efficiency. In laboratory tests point attack tools made more respirable dust and had a higher potential for producing methane ignitions. Point attack tools may wear better, this attribute being promoted if they rotate in the holders. The rotation produces uniform wear, not "self-sharpening". Tip fracture potential is about the same for both point and wedge types. Point attack tools have value where resistance to abrasive wear is desirable, but a good depth of cut should be taken with them. In any projected use their environmental disadvantages should be considered. A theoretical analysis indicates that the same fundamental mode of rock breakage is invoked by both wedge and point attack tools. (a) (TRRL)

Abstract: Argues that two questions with regard to high solids attrition scrubbing have yet to be answered: What are the effects of shorter scrubbing time, lower temperature, and less sodium carbonate. Would a two-stage approach be advantageous. That is, could you get the major proportion of the bitumen with a mild scrub and apply the high power and temperature only to the refractory portion. Concludes that since mining can yield a 95% recovery of bitumen, heavy oil and tar sands should be mined. A reply notes that by appropriate control of bitumen viscosity in the feed (probably the most important variable for successful separation) the recovery can be accomplished at low digestion temperature and low addition of alkali.

Abstract: This report describes further analysis of British rail's "national passenger accounting and analysis system" data to estimate demand elasticities with respect to rail fares, following a preliminary report of results obtained from a study of passenger flows between 60 towns and central London termini, over distances up to 120 kilometres. A fresh analysis of an enlarged data base (consisting of the original 60 flows plus a further 80 flows) using a modified form of analysis has estimated mean fare elasticities for season, cheap-day and full-fare tickets of -0.50 plus or minus 0.07, -0.65 plus or minus 0.06 and -0.20 plus or minus 0.04 respectively, although the errors on the means probably overstate the accuracy of these estimates because systematic errors may well be present. The latest analyses showed that the estimated elasticities were independent of the size of the passenger flow and of distance from London, except in the case of cheap-day trips where the greater the distance travelled the more elastic the journeys. Journey-time elasticities were estimated for two stations in the western region served by the high speed train; both values were found to be about -0.7 plus or minus 0.3 for off-peak travel. The reduction in mean journey time during the peak, however, was too small to enable elasticities to be estimated. A service frequency elasticity of 0.6 plus or minus 0.3 was obtained for season ticket travel from just one of the stations. (Author/TRRL)