Following a given classi®cation of geomagnetic activity, we obtained aa index values for the Maunder minimum (1645±1715). It is found that the recurrent and ̄uctuating activities were not appreciable and that the shock activity levels were very low. The aa index level was due almost entirely to the quiet days. Calculated average solar-wind velocities were 194.3 km s from 1657 to 1700 and 218.7 ...

We used N-body dynamical simulations to analyze the conditions for the gravitational stability of a three-dimensional stellar disk in the grav-itational field of two rigid spherical components — a bulge and a halo, whose central concentrations and relative masses vary over wide ranges. The number of point masses N in the simulations varied from 40 to 500 thousands and the evolution of the simul...

SUMMARY Traveltime data together with known spacing between sources and receivers for seismic transmission tomography can be used to determine rigorous constraints on the minimum and maximum wave speeds in the propagating medium. These constraints lead to a new minimum variance criterion on inversion algorithms. These results do not improve the velocity reconstructions directly , but provide ri...

This paper is concerned with semi-batch foams generated by injecting gas bubbles in a vertical column containing a liquid phase at rest. Its aim is to better understand the physical mechanisms responsible for foam formation at the liquid free surface and to predict the superficial gas velocity for onset of foaming. The model for predicting the onset of foaming is derived from the one-dimensiona...

Miniaturized thermal flow sensors have opened the doors for a large variety of new applications due to their small size, high sensitivity and low power consumption. Theoretically, very small detection limits of air velocity of some micrometers per second are achievable. However, the superimposed free convection is the main obstacle which prevents reaching these expected limits. Furthermore, exp...

the growth rate of stem cells in mobius cellready 3l bioreactor has been studied using comsol multi-physics simulation software in order to find out the best operational parameters for secure cell growth. the bioreactor geometry was defined according to the emd millipore issued information while turbulent and unsteady state solid-liquid 2-phase fluid flow equations were used for modelling the b...