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921.
922.
A. A. Ilyin 《Proceedings of the Steklov Institute of Mathematics》2006,255(1):136-149
A two-dimensional Navier-Stokes system with friction is considered in a large rect-angular periodic domain with area on the order of α?1, α → 0. Bounds for the dimension of the attractor are obtained, which are sharp both as α → 0 and v → 0, where v is the viscosity coefficient. 相似文献
923.
Characterizations of the containment of a convex set either in an arbitrary convex set or in the complement of a finite union
of convex sets (i.e., the set, described by reverse-convex inequalities) are given. These characterizations provide ways of
verifying the containments either by comparing their corresponding dual cones or by checking the consistency of suitable associated
systems. The convex sets considered in this paper are the solution sets of an arbitrary number of convex inequalities, which
can be either weak or strict inequalities. Particular cases of dual characterizations of set containments have played key
roles in solving large scale knowledge-based data classification problems where they are used to describe the containments
as inequality constraints in optimization problems. The idea of evenly convex set (intersection of open half spaces), which
was introduced by W. Fenchel in 1952, is used to derive the dual conditions, characterizing the set containments. 相似文献
924.
A. I. Khachaturov 《Technical Physics》2006,51(2):226-230
The contribution of electrons moving at large angles to the barrier junction plane to the tunnel current is calculated. This contribution turns out to be small only if the Fermi energy of the electrons equals several electron volts. Otherwise, specifically, when the Fermi energy is no higher than 1–2 eV, this contribution dominates in high and thin potential barriers. It is found that the tunnel magnetic resistance in ferromagnet-insulator-ferromagnet contacts correlates with this contribution. It is this correlation that is responsible for a decrease in this contribution as the potential barriers get lower and thicker. 相似文献
925.
The theory of dielectric space-charge polarization losses describes well both the model of an inhomogeneous dielectric [1]
and the polarization resulting from mosaic blocks of alkali-halide crystals [2]. The Debye frequency dependences ε*(ω) and
tan δ(ω) with non-Arrhenius relaxation time are calculated in the first approximation of perturbation theory [3, 4] with the
use of a nonlinear system of the Fokker-Planck and Poisson equations for the interlayer polarization with allowance for tunnel
transitions of relaxation oscillators. For the Maxwell mechanism of space-charge relaxation, tan δ(ω) also has the Debye form
[5]. It should be noted that in studies cited above the electric field was considered uniform, and the nonlinearity of the
initial system of equations was not investigated. This paper removes these restrictions and elaborates a theory of relaxation
mechanism.
__________
Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 11, pp. 28–34, November, 2006. 相似文献
926.
A. P. Avdeenko S. A. Konovalova O. N. Ludchenko 《Russian Journal of Organic Chemistry》2006,42(5):683-688
Reactions of halogens with N-arylsulfonyl-1,4-benzoquinone monoimines occur with the formation of a halogenonium ion that either transforms into a carbocation where the first halogen atom adds to the carbon in the ortho-position relative to the carbonyl carbon, or the halogenonium ion adds directly the second halogen atom. 相似文献
927.
S.N. Abdulmadjid M.M. Suliyanti K.H. Kurniawan T.J. Lie M. Pardede R. Hedwig K. Kagawa M.O. Tjia 《Applied physics. B, Lasers and optics》2006,82(1):161-166
We report in this paper the results of an experimental study on hydrogen analysis of solid samples in high pressure helium
ambient gas employing the basic scheme of laser induced breakdown spectroscopy (LIBS). It is shown that the metastable excited
state of helium atom can be utilized to induce delayed excitation of the ablated hydrogen atoms, and thereby avoid the Stark
broadening effect as well as overcoming the undesirable mismatch effect, which are responsible for inefficient excitation
respectively. It is further demonstrated that for samples of high boiling-point materials such as zircaloy, successful hydrogen
analysis can be achieved by a newly introduced double excitation technique employing single laser realized in a modified configuration
of the conventional LIBS method.
PACS 51-52 相似文献
928.
Morphological and chemical properties of both the surface and interface of poly(vinylidene fluoride)/poly(methyl methacrylate)-co-poly(ethyl acrylate) (PVDF/PMMA-co-PEA) blend films have been investigated before and after the samples were exposed to ultraviolet (UV) irradiation using a xenon arc lamp at 50 °C and 9% relative humidity (RH) for 7 months. Surface and interfacial morphologies were studied by atomic force microscopy (AFM). Chemical composition information was obtained by confocal Raman microscopy, attenuated total reflection-FTIR spectroscopy (ATR-FTIR), X-ray photoelectron spectroscopy (XPS), and contact angle measurements. Results show an enrichment of the PVDF material at the air surface, while the acrylic copolymer enriches the interface. Blends having greater than 50% mass fraction of PVDF show little change in the surface morphology after UV exposure for 7 months. However, for a lower PVDF content, blends exhibit significant degradation of PMMA-co-PEA copolymer and a much rougher surface after UV exposure. Microstructural changes in the PVDF spherulites are also observed after UV degradation. It is found that the surface and interfacial morphologies are correlated with the chemical properties. 相似文献
929.
M. Mayr K. -H. Speidel M. Knopp W. Karle T. Faestermann F. Hagelberg H. -J. Simonis P. N. Tandon J. Gerber 《Zeitschrift für Physik A Hadrons and Nuclei》1987,327(2):157-161
[Theg-factor ratio of the first excited 3? and 5? states in40Ca was measured to beg 3/g 5=1.01(10) employing the implantation perturbed angular correlation technique. The static hyperfine fields (SF) in Fe and Gd hosts were used. In addition the lifetime of the 5? state was measured to be τ=426(7)ps. The values of the SF in Gd and Fe hosts were deduced and compared with systematics in this element region. 相似文献
930.