Planar Rayleigh scattering measurements using an ArF-excimer laser have been performed to investigate helium mixing into air at supersonic speeds. The capability of the Rayleigh scattering technique for flow visualization of a turbulent environment is demonstrated in a large-scale, Mach 6 facility. The detection limit obtained with the present setup indicates that planar, quantitative measureme...

Planar Rayleigh scattering measurements with an argon-fluoride excimer laser are performed to investigate helium mixing into air at supersonic speeds. The capability of the Rayleigh scattering technique for flow visualization of a turbulent environment is demonstrated in a large-scale, Mach-6 facility. The detection limit obtained with the present setup indicates that planar, quantitative measu...

The effect of imperfectly conducting bounding plates on the heat transport in turbulent thermal convection in the Rayleigh-Bénard problem is considered in the context of analytical upper bounds. Beginning with the evolution equations in the fluid in the Boussinesq approximation, coupled through temperature and flux continuity to identical upper and lower conducting plates with diffusive heat fl...

(Received ?? and in revised form ??) We study by a fully nonlinear, three-dimensional pseudospectral, time-splitting simulation the feedback control of a layer of fluid heated from below. The initial condition corresponds to a steady, large-amplitude, preferred convection state obtained at Prandtl number of 7.0 and Rayleigh number of 10 4 , which is about six times the Rayleigh critical value. ...

Super-resolution imaging allows the imaging of fluorescently labeled probes at a resolution of just tens of nanometers, surpassing classic light microscopy by at least one order of magnitude. Recent advances such as the development of photo-switchable fluorophores, high-sensitivity microscopes and single particle localization algorithms make super-resolution imaging rapidly accessible to the wi...

We discuss apparent characteristic features of Rayleigh scattering of elastic waves from cracks. Interpreting these features, we propose a procedure that in some experimental situations may be useful to distinguish generally-shaped cracks from volume defects. For elliptically-shaped cracks, we propose additional procedures that in principle allow the unique specification of crack size, shape an...

We experimentally and numerically tested the separability of two independent equally luminous monochromatic and white light sources at the diffraction limit, using optical vortices (OV). The diffraction pattern of one of the two sources crosses a fork hologram on its center generating the Laguerre-Gaussian (LG) transform of an Airy disk. The second source, crossing the fork hologram in position...