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911.
Applying tight-binding approximation and spin pairing of like charge carriers in a pair of excitons created in a lattice, the possibility of forming a bound exciton-exciton state is studied. It is found that, provided there exists strong exciton-lattice interaction, such a bound state may be formed and its energy may lie within the valence band deforming the material into a crystalline solid with no energy gap. Lowering of the energy is calculated in naphthalene and anthracene crystals where some experimental results are known. The excess energy released after the formation of such bound state can be adequate, depending on the material, to desorb neutral atoms or eject of electrons from surfaces. 相似文献
912.
913.
V. N. Likhachev 《Journal of Applied Mathematics and Mechanics》1989,53(6):750-756
The method of combined asymptotic expansions is used to solve the problem of the focusing of a shock wave (in a weakly compressible medium of high viscosity. Asymptotic forms of the solution are constructed in a number of spatial zones. The focusing zone is described by its asymptotic form obtained by combining it with the solution corresponding to viscous geometrical acoustics. The reflection of a shock wave formed as a result of velocity jump near one of the foci of the ellipsoid of revolution is discussed as an example. Analytical relationships descrbing the focusing zone around the second focus are obtained. It is shown that at the focus itself the wave profile has an antisymmetric form, and the compression wave is followed by a rarefaction wave of the same form. 相似文献
914.
A new singular integral equation is obtained that describes the elastic equilibrium of a strip with both an inner and an edge slit (crack) and has a considerable advantage over existing equations /1–9/, etc.) from the viewpoint of a numerical realization and clarification of the analytical relationship with an analogous equation for a half-plane. Numerical results are given of a computation of the stress intensity coefficients at the tips of the inner and edge cracks that refine data in the literature. 相似文献
915.
O. V. Gusev V. V. Krivykh P. V. Petrovskii M. I. Rybinskaya 《Russian Chemical Bulletin》1987,36(7):1532-1534
Conclusions The allyl ligand in neutral molybdenum and cobalt complexes is readily exchanged by dienes in the presence of a strong protic acid with the formation of cationic complexes. This exchange is facilitated by an increase in the basicity of the starting compounds.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 7, pp. 1655–1657, July, 1987. 相似文献
916.
N. V. Krasnikov 《Theoretical and Mathematical Physics》1987,73(2):1184-1190
917.
M.V. Devyaterikova 《Operations Research Letters》2006,34(2):149-154
In the present paper we develop our approach for studying the stability of integer programming problems. We prove that the L-class enumeration method is stable on integer linear programming problems in the case of bounded relaxation sets [9]. The stability of some cutting plane algorithms is discussed. 相似文献
918.
In the multidimensional case, for the Tikhonov regularization, two new families of stabilizers containing the norms of the Lipschitz spaces and the norms of the Sobolev spaces with fractional derivatives are suggested. Theorems of convergence of Tikhonov regularized approximate solutions and their discrete approximations are proved. Detailed step-by-step investigation of the solving algorithm is performed by the example of an integral Fredholm equation of the first kind. 相似文献
919.
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
920.
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