Higher order symmetrizer and application to an unusual transport equation

We study a class of stationary transport equation with nonlocal low-order tems We obtain the existence and uniqueness of a solution in sobolev spaces     

求解复杂湍流的非线性涡黏性系数模型和代数应力模型

非线性涡黏性系数模型和代数应力模型联系了线性涡黏性系数湍流模型和完整的微分 雷诺应力模型.随着它们受到日益关注,其形式也越来越多样化.本篇综述的目的是对这些模 型加以总结并比较它们之间的共同点及不同之处,指出它们与完整微分雷诺应力模型之间的 关系,以及相对于线性涡黏性系数模型而言它们在预报流场上所具有的优势.     

Intensification of the peroxide macroradical formation in polytetrafluoroethylene under action of mixed (n,γ)-radiation in the vicinity of recoil atom tracks

Formation of peroxide macroradicals in PolyTetraFluoro Ethylene (PTFE) under γ-rays, protons (100 MeV), heavy Xe-ions (1 MeV/ nucleon), and mixed (n,γ)-irradiation has been investigated. An unusually high value of the macroradical formation yield in the case of reactor irradiation (G(R)_n,γ=(7.04±0.18)×10⁻² 1/100 eV) as well as unusual increase of G(R) in the first three cases with growing linear energy transfer (LET) values has been explained as an evidence for synergetic effects that may appear during radiation degradation of PTFE in the fields of mixed ionizing radiation.     

Determination of electron affinity of carbonyl radicals by means of negative ion mass spectrometry

Appearance energies of [M-H](-) ions from carbonyl compounds R-CO-R' (R,R' = H, CH(3), NH(2), OH) have been measured by means of negative ion mass spectrometry in resonant electron capture mode. Values of electron affinity of the corresponding radicals, CH(2)&dbond;C(X)O, NH&dbond;C(X)O and O&dbond;C(X)O, have been determined. Copyright 1999 John Wiley & Sons, Ltd.     

Parametric oscillations of liquid in communicating vessels

It is well known that a periodic change in the equilibrium or flow parameters of an incompressible liquid exerts a material influence on the hydrodynamic stability. As an example we may quote the parametric excitation of surface waves (gravitational-capillary [1], electrohydrodynamic [2], magnetohydrodynamic [3]) and the oscillations of liquid in communicating vessels [4, 5]. The chief object of the foregoing experimental investigations was that of determining the boundaries of the regions of unstable equilibrium with respect to small perturbations. In the present investigation we made an experimental study of the parametric resonance and finite-amplitude parametric oscillations arising in a liquid-filled U-tube subject to alternating vertical overloadings. We shall describe two forms of oscillations in the liquid, and we shall determine the corresponding ranges of unstable equilibrium with respect to small random perturbations (self-excitation) and also to finite-amplitude perturbations. We shall study nonlinear modes of excitation and mutual transitions between the two forms of oscillations. We shall find the ranges of existence of steady-state oscillations.Translated from Izvestiya Akademii Nauk SSSR, Mekhanika Zhidkosti i Gaza, No. 2, pp. 36–42, March–April, 1976.The authors wish to thank G. I. Petrova and the participants in his seminar for useful discussions, and S. S. Grigoryan for valuable advice.     

Interaction of the thermovibrational and thermocapillary convection mechanisms

Thermal convection in microgravity induced by the combined action of thermocapillary forces and vibrations is considered. In the high-frequency approximation the thermovibrational forces are written for the case in which isothermal mixing of the fluid is unimportant. The authors' own work and new results of investigating the effect of vibration on thermocapillary instability, of numerically modeling the heat and mass transfer in open cavities and of experiments on the vibrational suppression of surface deformation are reviewed. The prospects for the practical application of the results obtained are discussed.     

The multi-functional aspect of scanning holographic microscopy: a review(Invited Paper)

Recent developments in scanning holographic microscopy that offer the prospects of new quantitative tools and imaging modalities in bio, micro, and nano sciences are reviewed. The versatility of the method is emphasized. Scanning holography can operate in an incoherent mode for fluorescence imaging, in a coherent mode for quantitative phase imaging, or in a tomographic mode for axial sectioning and rejection of the out-of-focus haze. Possible applications are illustrated with examples, and future prospects ...     

Faraday Ripples, Parametric Resonance, and the Marangoni Effect

In general, the combined actions of two destabilizing mechanisms do not simply add to each other. Here we show that there is a subtle interplay between parametric excitation and thermal gradients leading to interfacial instability, overstability, and generation of surface waves. The case studied refers to the stability of a liquid layer with an open free surface subjected to a transverse temperature gradient (with the Marangoni effect) and also subjected to the simultaneous action of periodic vibrations normal to the layer. Stability is examined in the weak viscosity approximation by applying a multiscale method. To a first approximation, whatever the imposed thermal gradient, vibrations with fairly large amplitude are responsible for excitation of ripples with half the imposed vibration frequency, but their amplitude depends on the Marangoni number. However, as the Marangoni number increases, the critical amplitude decreases from the excitation threshold of Faraday ripples, and after passing through a minimum it monotonically increases with increasing thermal gradient. Another salient finding is that the threshold of the Marangoni overstability is found to be independent of the imposed vibration frequency and amplitude. Copyright 2001 Academic Press.