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排序方式: 共有521条查询结果,搜索用时 921 毫秒
61.
62.
This paper investigates the flow structure in the wake behind the centrebody of an annular jet using time-resolved stereoscopic
PIV measurements. Although the time-averaged flow field is symmetric, the instantaneous wake is asymmetric. It consists of
a central toroidal vortex (CTV), which closes downstream at the stagnation point. This stagnation point lies off-axis and
hence the axis of the CTV is tilted with respect to the central axis of the geometry. The CTV precesses around the central
axis, corresponding to a Strouhal number of 2.5 × 10−3. The phase averaging technique is used to study this large-scale motion as it can separate the precession from the turbulence
in the flow field. It is found that the precession creates a highly three-dimensional flow field and for instance near the
stagnation point, up to 45% of the rms velocity fluctuations are attributed to it. 相似文献
63.
Maarten de Hoop Gunther Uhlmann Yiran Wang 《Annales de l'Institut Henri Poincaré (C) Analyse Non Linéaire》2019,36(2):347-363
For scalar semilinear wave equations, we analyze the interaction of two (distorted) plane waves at an interface between media of different nonlinear properties. We show that new waves are generated from the nonlinear interactions, which might be responsible for the observed nonlinear effects in applications. Also, we show that the incident waves and the nonlinear responses determine the location of the interface and some information of the nonlinear properties of the media. In particular, for the case of a jump discontinuity at the interface, we can determine the magnitude of the jump. 相似文献
64.
Stochastic integer programs are notoriously difficult. Very few properties are known and solution algorithms are very scarce. In this paper, we introduce the class of stochastic programs with simple integer recourse, a natural extension of the simple recourse case extensively studied in stochastic continuous programs.Analytical as well as computational properties of the expected recourse function of simple integer recourse problems are studied. This includes sharp bounds on this function and the study of the convex hull. Finally, a finite termination algorithm is obtained that solves two classes of stochastic simple integer recourse problems.Supported by the National Operations Research Network in the Netherlands (LNMB). 相似文献
65.
66.
67.
Rubens G. Lintz 《Annali di Matematica Pura ed Applicata》1966,72(1):45-57
Summary We study here conditions under which a homomorphism of Čech groups can be realized by generalized fonctions. 相似文献
68.
Rubens G. Lintz 《Annali di Matematica Pura ed Applicata》1966,72(1):97-103
Summary I give here a theorem of realization of homomorphism in Cech homology theory, which improves some previous results of mine. 相似文献
69.
V. P. Afanasyev D. S. Efremenko A. V. Lubenchenko Maarten Vos Michael R. Went 《Bulletin of the Russian Academy of Sciences: Physics》2010,74(2):170-174
REELS spectra of the electrons reflected off niobium are measured with energy resolution <0.5 eV within the 5–40 eV energy
range of the probing beam. The measurements were performed for the scattering angles θ = 45° and θ = 120° by means of two
electron guns. The process of energy losses is described within the framework of a model with three different energy loss
laws: surface, intermediate, and bulk layers are considered. Differential cross-sections of inelastic scattering are represented
in the form of simple equations. 相似文献
70.
Köhler K Biesheuvel PM Weinkamer R Möhwald H Sukhorukov GB 《Physical review letters》2006,97(18):188301
We study the size of polyelectrolyte multilayer capsules as a function of ionic strength, temperature, and time. A dynamic micromechanical model is developed which successfully describes the experiments. The model includes the polymer-solvent surface tension, an electrostatic force which is strongly ionic strength dependent, and a temperature-dependent mobility parameter. The activation of >50 kT suggests that multiple ion pairs must be broken simultaneously in the process of chain rearrangement. In support of our physical model capsules can repeatedly swell and shrink by varying ionic strength. 相似文献