2014 We study shear flow instabilities in nematic liquids of planar geometry (molecules parallel to the plates limiting the sample) and where molecules are aligned (along Ox) perpendicular to the shear flow direction (along Oy). An external magnetic field reinforces the alignement imposed by surface effects. We develop a bidimensional model which takes into account exactly boundary conditions o...

The non-linear loads include rectifiers, blenders, electric drills, UPS, computer, printer, TV’s, variable speed drivers, arc furnaces and high power electronic equipment comprising high power semiconductors i.e thyristorised Converters, Inverters etc. It is well known that any deviation from a perfect sin-wave is an indication of the presence of harmonics in the power system. Hence, a pure alt...

The current near a right-angled comer on a perfectly conducting flat scatterer illuminated by a plane wave is expressed as a sum of three currents. The first is the physical optics (PO) current, which describes the surface effect. The second is the fringe wave (FW) current, which is found from the half-plane solution and accounts for the distortion of the current caused by the edges. The third ...

S U M M A R Y Sensitivity kernels for fundamental mode surface waves at finite frequency for 2-D phase speed and 3-D shear wave speed are constructed based on the Born and Rytov approximations working with a potential representation for surface waves. The use of asymptotic Green’s functions for scalar wave equations provides an efficient way to calculate the Born or Rytov kernels. The 2-D sensi...

a) Develop the nonlinear acoustic theory of poroelastic media using Biot’s semilinear model and physical model of contact nonlinearity, b) Measure the nonlinear parameter of sediments in laboratory tank, c) Study the effect of sediment parameters (grain size distribution, free gas content, porosity) on nonlinear acoustic properties of the sediments, d) Evaluate the nonlinear absorption and dist...

We theoretically study and experimentally report the propagation of nonlinear hysteretic torsional pulses in a vertical granular chain made of cm-scale, self-hanged magnetic beads. As predicted by contact mechanics, the torsional coupling between two beads is found to be nonlinear hysteretic. This results in a nonlinear pulse distortion essentially different from the distortion predicted by cla...