Determining the maximum density of sands by pluviation

Experiments have been carried out to find the maximum dry density taken up by sands during pluviation. These experiments were facilitated by use of a flow divider that permitted very low depositional intensities. It was found that the maximum dry density occurred at an optimum pluviation time. Careful observation of the pluviating sand reveals that compaction takes place within an “energetic layer” of 3 to 4 grains in thickness and that maximum dry density requires the full and continuous development of this layer. Further experiments were conducted to compare simple pouring without diffuser meshes with pluviation: it is shown that at very slow rates of pour, pouring gives the same density as pluviation.<br/

NEW ROVIBRATIONAL DATA FOR MgOH AND MgOD, AND THE INTERNUCLEAR POTENTIAL FUNCTION OF THE GROUND ELECTRONIC STATE

$^{1}$ P. Jensen, J. Mol. Spectrosc. 128, 478-501 (1988); J. Chem. Soc. Faraday Trans. 2 84, 1315-1340 (1988); in: ""Methods in Computational Molecular Physics'' (S. Wilson and G.H.F. Diercksen, Eds.), Plenum, New York, 1992.Author Institution: National Research Council of Canada, Ottawa, Ontario, Canada K1A 0R6; Bergische Universität, Gesamthochschule Wuppertal, D-42097 Wuppertal, Germany.; Arizona State University, Tempe, AZ 85287-1604, U.S.A.; The University of California, Santa Barbara, CA 93106, U.S.A.Using millimeter wave absorption spectroscopy we have recorded pure rotation spectra of MgOH for the ground vibrational state and for six excited vibrational states. We have also determined a large number of bending vibrational energies, and the MgO stretching frequency, using dispersed fluorescence studies of both MgOH and MgOD. By a weighted least squares optimized fitting to this data using the variational approach $MORBID^{1}$ Morse Oscillator Rigid Bender Internal Dynamics), with a basis set of Morse oscillator stretching functions and rigid bender functions, we have derived the full ground state potential surface in an analytical form. Although the equilibrium structure is determined to be linear, the bending part of the potential is rather flat and symptoms of quasilinearity are present; for example in the $\nu_{2} = 2$ state the l = 2 component is below the l = 0 component

A novel study on high-powered ultrasonic penetrators in granular material

This work investigates the effects of high-powered ultrasonics in granular material. The aim is to facilitate penetration in granular material in low mass/low gravity environments. The results show that the weight on bit requirement for penetration is significantly reduced on application of direct ultrasonic vibration, especially in high relative density substrates