Flume studies of the transport of pebbles and cobbles on a sand bed

CER61RKF80.December 1961.Includes bibliographical references.Submitted to the Bulletin of Geological Society of America for publication.During experiments on sediment transport and resistance to flow with a uniform 0.33 mm sand, data were taken on the movement of individual rocks having intermediate diameters from about 0.1 to 0.5 foot. The experiments were conducted in a flume 2-foot wide by 80-feet long and for most runs, depth was held constant at 0.5 feet. The experiments showed that rocks on sand bed moved downstream consistently only if the flow was in the upper regime; that is, only if the bed forms were plain bed, standing waves, or antidunes. The rocks moved at velocities that were approximately one half of the average veloc1ty of the water. With all bed forms in the lower flow regime (ripples, ripples superimposed upon dunes, and dunes), the rocks always moved upstream and down into the bed. That is, the rocks moved into a scour pocket that formed at the upstream side of the rock. The movement upstream and down into the bed is limited by and approximately equal to the distance below the original rock position of the minimum bed elevation plus approximately one-half the rock diameter. The data indicate that cross bedded sand deposits formed by the ripple or dune phases of transport would contain few, if any, pebbles or cobbles. Because of the flow, in at least the downstream reaches of most rivers is in the lower regime, the upstream movement and scour into the bed demonstrated in the experiment is an important factor in the sorting process

Separator for Heavy ELement Spectroscopy – velocity filter SHELS

International audienceThe SHELS velocity filter originated upon reconstruction of the VASSILISSA electrostatic separator used for investigations of heavy nuclei produced in complete fusion reactions. The goals of this modernization were to increase the transmission of products of asymmetric reactions and to extend the region of reactions to be investigated up to symmetric combinations. The first tests of the set-up were performed with the beams of accelerated 22 Ne, 40 Ar, 48 Ca, and 50 Ti ions

Separator for Heavy ELement Spectroscopy - velocity filter SHELS

The SHELS velocity filter originated upon reconstruction of the VASSILISSA electrostatic separator used for investigations of heavy nuclei produced in complete fusion reactions. The goals of this modernization were to increase the transmission of products of asymmetric reactions and to extend the region of reactions to be investigated up to symmetric combinations. The first tests of the set-up were performed with the beams of accelerated 22Ne, 40Ar, 48Ca, and 50Ti ions.status: publishe