The dependence of mixing efficiency on time-varying forcing is studied by direct numerical simulation (DNS) of Kelvin-Helmholtz (KH) instability. Timedependent forcing fields are designed to mimic a breaking internal wave by solving the equations of motion in a tilted coordinate frame and allowing the tilt angle to vary in time. Mixing efficiency Γc is defined as the ratio of potential energy g...

The application of arti® cial intelligence planning techniques to real world problems is a very di cult task which usually implies overcoming expressiveness and e ciency handicaps. Expressiveness in order to cope with the great amount of knowledge involved in these problems and also to obtain results directly, or almost directly, applicable in the ® eld of study. E ciency to achieve a good c...

The entrainment across a stably stratified interface forced by convective motions is discussed in the light of the mixing efficiency of the entrainment process. The context is the convectively driven atmospheric boundary layer and we focus on the regime of equilibrium entrainment, i.e. when the boundary-layer evolution is in a quasi-steady state. The entrainment law is classically based on the ...

To achieve high mixing efficiency in microfluidic devices, complex designs are often required. Microfluidic devices have been evaluated with light and confocal microscopy, but fluid-flow characteristics at different depths are difficult to separate from the en face images produced. By using optical coherence tomography (OCT), an imaging modality capable of imaging 3D microstructures at micromet...

The strength of diapycnal mixing by small-scale motions in a stratified fluid is investigated through changes to the mean buoyancy profile. We study the mixing in laboratory experiments in which an initially linearly stratified fluid is stirred with a rake of vertical bars. The flow evolution Ž . depends on the Richardson number Ri , defined as the ratio of buoyancy forces to inertial forces. A...

The zero-dispersion wavelength map of an optical fiber can be obtained from measurement of end-to-end four-wave mixing efficiency at various wavelengths. A fast and unambiguous algorithm for reconstruction of the zero-dispersion wavelength map of an optical fiber by measurement of four-wave mixing efficiency is proposed. This method can produce high-resolution results in a few seconds. We also ...

We constructed hydrodynamical model atmospheres for mid M-type main-, as well as pre-main-sequence (PMS) objects. Despite the complex chemistry encountered in these cool atmospheres a reasonably accurate representation of the radiative transfer is possible, even in the context of time-dependent and three-dimensional models. The models provide detailed information about the morphology of M-type ...

We illustrate two As2S3 waveguide designs for four-wave mixing, which can generate 3.03 μm mid-infrared light from a 1.55 μm near-infrared signal source and a 2.05 μm pump source. Through simulations, we verify that four-wave mixing phase-matching efficiencies up to 100% can be achieved using dispersion engineering to maintain the dispersion at 2.05 μm near to zero. The best conversion efficien...

Ž . The interaction of high-intensity short pulse fs lasers with atomic or molecular vapors permits the conversion of visible light to intense coherent radiation in the vacuum ultraviolet spectral region. We demonstrate sum frequency mixing of a Ž . Ž . high-intensity short pulse fs laser with a conventional long pulse ns laser to extend the accessible wavelength range of harmonic generation. T...

We examine the vertical mixing induced by the swimming of microorganisms at low Reynolds and Péclet numbers in a stably stratified ocean, and show that the global contribution of oceanic microswimmers to vertical mixing is negligible. We propose two approaches to estimating the mixing efficiency, η, or the ratio of the rate of potential energy creation to the total rate-of-working on the ocean ...