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ABSTRACT: The influence of the horizontal component of the temperature gradient on nonlinear regimes of oscillatory convection developed
under the joint action of buoyant and thermocapillary effects in a multilayer system, is investigated. The nonlinear two-dimensional
convective regimes are studied by the finite difference method. The interfaces are assumed to be non-deforming. The rigid
heat-insulated lateral walls are considered. Transitions between different oscillatory and steady flow regimes have been studied.
Specifically, it is shown that the horizontal component of the temperature gradient leads to the violation of the symmetry
conditions and the appearance of the asymmetric oscillatory flows. The cavities with different lengths have been considered.
KeywordsInterfacial convection–Instabilities–Multilayer system
Microgravity - Science and Technology 04/2012; 23:25-34. · 0.59 Impact Factor
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ABSTRACT: The nonlinear development of oscillatory instability under the joint action of buoyant and thermocapillary effects in a multilayer
system, is investigated. The nonlinear convective regimes are studied by the finite difference method. The rigid heat-insulated
lateral walls, are considered. Transitions between the motions with different spatial structures are investigated. Specific
types of flows, symmetric and asymmetric oscillations, have been found. It is shown that the oscillatory motion takes place
in an interval of the Grashof number values bounded both from below—by the mechanical equilibrium, and from above—by the steady
state.
KeywordsMultilayer system-Interfaces-Instabilities
Microgravity - Science and Technology 04/2012; 22(3):257-263. · 0.59 Impact Factor
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ABSTRACT: A quantitative autocalibrated high-resolution schlieren technique for quantitative measurement of reflective surface shape is proposed. It combines the schlieren principle with the phase-shifting technique that is generally used in interferometry. With an appropriate schlieren filter and appropriately tailored setup, some schlieren fringes are generated. After application of the phase-shift technique, the schlieren phase is calculated and converted into beam deviation values. Theoretical and experimental demonstrations are given. The technique is validated on a reference target, and then its application in a fluid physics experiment is demonstrated. These two examples show the potential of the phase-shifting schlieren technique that in some situations can become competitive with interferometry but with a much better dynamic range and with variable sensitivity. The technique can also be used to measure refractive-index gradients in transparent media.
Applied Optics 10/2003; 42(25):5046-53. · 1.41 Impact Factor
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ABSTRACT: Linear-correlation amplitude changes when the intensity level of the input image is modified. As recognition is often based on the correlation-peak level, a change of the input illumination may result in a false recognition. We propose an illumination-change compensation by a post processing of the correlation distribution that is based on statistical measures of the correlation histograms. The theoretical background and simulation results are provided in the frame of an actual application in biology.
Applied Optics 07/2002; 41(17):3453-60. · 1.41 Impact Factor
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ABSTRACT: Cancer cell motility and invasion are critical targets for anticancer therapeutics. Whereas in vitro models could be designed for rapid screening with a view to investigate these targets, careful consideration must be given to the construction of appropriate model systems. Most investigations focus on two-dimensional (2-D) assays despite the fact that increasing evidence suggests that migration across rigid and planar substrates fails to recapitulate in vivo behavior. In contrast, few systems enable three-dimensional (3-D) cell migration to be quantitatively analyzed. We previously developed a digital holographic microscope (DHM) working in transmission with a partially spatial coherence source. This configuration avoids the noise artifacts of laser illumination and makes possible the direct recording of information on the 3-D structure of samples consisting of multiple objects embedded in scattering media, such as cell cultures in matrix gels. The software driving our DHM system is equipped with a time-lapse ability that enables the 3-D trajectories of living cells to be reconstituted and quantitatively analyzed.
Journal of Biomedical Optics 11(5):054032. · 3.16 Impact Factor
