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961.
B. Amaziane M. Goncharenko L. Pankratov 《Mathematical Methods in the Applied Sciences》2005,28(15):1847-1865
We study the asymptotic behaviour of the solution of a stationary quasilinear elliptic problem posed in a domain Ω(ε) of asymptotically degenerating measure, i.e. meas Ω(ε) → 0 as ε → 0, where ε is the parameter that characterizes the scale of the microstructure. We obtain the convergence of the solution and the homogenized model of the problem is constructed using the notion of convergence in domains of degenerating measure. Proofs are given using the method of local characteristics of the medium Ω(ε) associated with our problem in a variational form. Copyright © 2005 John Wiley & Sons, Ltd. 相似文献
962.
963.
In this paper, space adaptivity is introduced to control the error in the numerical solution of hyperbolic systems of conservation laws. The reference numerical scheme is a new version of the discontinuous Galerkin method, which uses an implicit diffusive term in the direction of the streamlines, for stability purposes. The decision whether to refine or to unrefine the grid in a certain location is taken according to the magnitude of wavelet coefficients, which are indicators of local smoothness of the numerical solution. Numerical solutions of the nonlinear Euler equations illustrate the efficiency of the method. 相似文献
964.
A. L. Goldenberg V. N. Manuilov M. Yu. Glyavin 《Radiophysics and Quantum Electronics》2005,48(6):461-465
We describe a nonadiabatic electron gun operated in the mode of a currentconfined by spatial charge and intended for producing
helical electron beams for high-power gyroresonantdevices.Results of numerical simulation of electron trajectories and electron-beam
parameters arepresented. It is shown that for a high operating current, the pitch factor and the electronvelocity spread can
be significantly better than in the conventional adiabatic systems.
__________
Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Radiofizika, Vol. 48,No. 6, pp. 517–522, June 2005 相似文献
965.
V. Boutou M. A. Lebeault-Dorget A. R. Allouche C. Bordas J. Chevaleyre 《Zeitschrift für Physik D Atoms, Molecules and Clusters》1997,40(1):448-453
In this article, we present results obtained on structures of small bare and oxygenated barium clusters produced by the laser vaporization technique. Contrary to the very weak Ba—Ba binding (0.202 eV), the Ba—O binding is rather strong (5.8 eV). As a consequence, extremely small amounts of oxygen in the cluster source are sufficient to induce the nucleation of oxygenated barium clusters. Surprisingly, at least for substoechiometric systems, BanOm clusters exhibit the same icosahedral structure as bare clusters do. Mass spectra seem to indicate that replacing a barium atom with a strongly polar BaO molecule does not affect the geometrical structure of the cluster. This aspect is more easily understandable if we assume that the oxygen atom takes place inside the structure of the Ban cluster without significant distortions. Ab-initio calculations have been undertaken in order to give a satisfactory account of this hypothesis. 相似文献
966.
N. I. Alekseev V. B. Kaplan A. M. Martsinovskii I. I. Stolyarov 《Technical Physics》1997,42(6):599-605
Results are presented from a systematic investigation of the conditions under which anomalously high rates of plasma generation
are observed in the anode region of a low-voltage Knudsen arc in grid plasma switch elements. The phenomenon develops over
a wide range of currents and switched voltages under conditions for which the plasma density in the cathode-grid region is
noticeably higher than the density in the anode region. and its onset is characterized by a pronounced pressure threshold
of ∼2×10−2 Torr. The results are analyzed from the standpoint of the possible mechanisms for anomalous plasma generation — collisional
nonresonance diffusion of electrons in velocity space, leading to enrichment of the distribution function in fast particles,
and the collapse of Langmuir waves in the gap at the high energies of the beam produced when the wires of the grid are bridged
by the quenching pulse and and the current is blocked.
Zh. Tekh. Fiz. 67, 15–21 (June 1997) 相似文献
967.
S. M. Dunaevskii A. L. Malyshev V. A. Trunov V. V. Popov 《Physics of the Solid State》1997,39(10):1636-1637
The results of investigating the temperature dependence of the resistivity, the differential magnetic susceptibility, and
the magnetoresistance of a partially substituted perovskite Sm1−x
SrxMnO3 (x=0.16–0.4) are presented. Colossal intrinsic magnetoresistance, reaching 90% in an external magnetic field of 30 kOe, is discovered
in the compound with x=0.30 at 77 K.
Fiz. Tverd. Tela (St. Petersburg) 39, 1831–1832 (October 1997) 相似文献
968.
969.
We study photoproduction of jets and heavy flavors in a polarized collider mode of HERA and in polarized ep collisions at √S ≈ GeV. We examine the sensitivity of the cross sections and their asymmetries to the proton’s polarized gluon distribution and to the completely unknown parton distributions of longitudinally polarized photons. 相似文献
970.
The relativistic four-quark equations are found in the framework of the dispersion relation technique. The behaviour of the low-energy four-particle amplitude is determined by its leading singularities in the pair invariant masses. The approximate solutions of these equations using the method based on the extraction of leading singularities of the amplitudes are obtained. The mass values of lowest exotic mesons are calculated. 相似文献