Weyl gravity, astrophysical observations, and laboratory measurements

The background for the present knowledge about hydraulic conductivity of clayey till in Denmark is summarized. The data show a difference of 1-2 orders of magnitude in the vertical hydraulic conductivity between values from laboratory measurements and field measurements. This difference is discussed and based on new data, field observations and comparison with North American studies, it is concluded to be primarily due to fractures in the till.

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Laboratory Measurements of Light Scattering by Dust Particles

International Astronomical Union Colloquium ◽

10.1017/s0252921100501948 ◽

1996 ◽

Vol 150 ◽

pp. 409-413

Author(s):

Patrick P. Combet ◽

Philippe L. Lamy

Keyword(s):

Light Scattering ◽

Laser Beam ◽

Mie Theory ◽

Spherical Particles ◽

Dust Particles ◽

Laboratory Measurements ◽

Scattering Function ◽

Hene Laser ◽

Set Up ◽

Good Agreement

AbstractWe have set up an experimental device to optically study the scattering properties of dust particles. Measurements over the 8 — 174° interval of scattering angles are performed on a continuously flowing dust loaded jet illuminated by a polarized red HeNe laser beam. The scattering is averaged over the population of the dust particles in the jet, which can be determined independently, and give the “volume scattering function” for the two directions of polarization directly. While results for spherical particles are in good agreement with Mie theory, those for arbitrary particles show conspicuous deviations.

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Modelling of speleothems failure in the Hotton cave (Belgium). Is the failure earthquake induced?

Netherlands Journal of Geosciences – Geologie en Mijnbouw ◽

10.1017/s001677460002391x ◽

2001 ◽

Vol 80 (3-4) ◽

pp. 315-321 ◽

Cited By ~ 19

Author(s):

J.F. Cadorin ◽

D. Jongmans ◽

A. Plumier ◽

T. Camelbeeck ◽

S. Delaby ◽

...

Keyword(s):

Natural Frequencies ◽

Quantitative Information ◽

Rigid Bodies ◽

Tensile Failure ◽

Future Research ◽

Geometrical Parameters ◽

Laboratory Measurements ◽

Ground Acceleration ◽

Strong Ground

AbstractTo provide quantitative information on the ground acceleration necessary to break speleothems, laboratory measurements on samples of stalagmite have been performed to study their failure in bending. Due to their high natural frequencies, speleothems can be considered as rigid bodies to seismic strong ground motion. Using this simple hypothesis and the determined mechanical properties (a minimum value of 0.4 MPa for the tensile failure stress has been considered), modelling indicates that horizontal acceleration ranging from 0.3 m/s2 to 100 m/s2 (0.03 to 10g) are necessary to break 35 broken speleothems of the Hotton cave for which the geometrical parameters have been determined. Thus, at the present time, a strong discrepancy exists between the peak accelerations observed during earthquakes and most of the calculated values necessary to break speleothems. One of the future research efforts will be to understand the reasons of the defined behaviour. It appears fundamental to perform measurements on in situ speleothems.

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