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41.
42.
A. A. Bormisov E. S. Gudkova F. Kh. Mukminov 《Theoretical and Mathematical Physics》1997,113(2):1418-1430
We consider equations of the form Uxy = U * Ux, where U(x, y) is a function taking values in an arbitrary finite-dimensional algebra T over the field ℂ. We show that every
such equation can be naturally associated with two characteristic Lie algebras, Lx and Ly. We define the notion of a ℤ-graded Lie algebraB corresponding to a given equation. We prove that for every equation under consideration, the corresponding algebraB can be taken as a direct sum of the vector spaces Lx and Ly if we define the commutators of the elements from Lx and Ly by means of the zero-curvature relations. Assuming that the algebra T has no left ideals, we classify the equations of the
specified type associated with the finite-dimensional characteristic Lie algebras Lx and Ly. All of these equations are Darboux-integrable.
Translated from Teoreticheskaya i Matematicheskaya Fizika, Vol. 113, No. 2, pp. 261–275, November, 1997. 相似文献
43.
44.
G. Kh. Panova M. N. Khlopkin N. A. Chernoplekov A. A. Shikov 《Physics of the Solid State》2002,44(7):1218-1223
The specific heats of the Ni2B amorphous system and of its crystal analog were studied in the temperature range 3–270 K. The data obtained permitted us to isolate the contribution due to atomic vibrations from the experimentally measured specific heat, determine the electronic density of states at the Fermi level and the temperature dependence of the characteristic Debye parameter Θ, and to calculate some average frequencies (moments) of the vibrational spectrum. The electronic density of states at the Fermi level increases under amorphization. An analysis of the temperature dependence of the lattice specific heat showed that amorphization brings about a substantial growth in the density of vibrational states at low frequencies, whereas the spectrum-averaged and rms frequencies change very little, which is in good agreement with neutron diffraction measurements. 相似文献
45.
Riemannian manifolds for which a natural curvature operator has constant eigenvalues on circles are studied. A local classification in dimensions two and three is given. In the 3-dimensional case one gets all locally symmetric spaces and all Riemannian manifolds with the constant principal Ricci curvatures r
1 = r
2 = 0, r
3= 0 , which are not locally homogeneous, in general. 相似文献
46.
The energies of negative-parity levels based on two-particle states exhibit a nonlinear behavior at low spins versus the core-rotation energy because the alignment process has not yet been completed for them. This behavior of negative-parity levels in the low-spin region is satisfactorily described upon the inclusion of octupole-octupole interactions. This is demonstrated within the rotational model involving the Coriolis mixing of states for the even-even isotopes 162–168Hf. 相似文献
47.
J. Kh. Nurligareev K. M. Golant V. A. Sychugov B. A. Usievich 《Technical Physics》2006,51(8):1030-1034
The propagation of a pencil beam in a circuital system of tunnel-coupled waveguides is considered. It is shown that the beam periodically focuses into a point when moving along the trajectory. A maximal number of waveguides supporting the propagation of the beam can be estimated in simple terms. The cross-sectional area of the waveguides can be subdivided into three zone with the beam pulsing only in the central one. 相似文献
48.
The potential and polarization distributions in a planar emitting layer of PLZT-9/65/35 ferroelectric ceramic with a set of conductive strip electrodes on the emitting side and a continuous electrode on the opposite side are studied by numerical methods. The state arising immediately after polarization switching at the leading edge of an applied voltage pulse (i.e., before the polarization charges are screened by free charges) is considered. When the pulsed field strength far exceeds the double coercive field, regions with alternating polarization are found to form in the surface layer between the strips. The normal component of the polarization at its maxima is close to saturation. The electric field on both sides of the surface varies as the polarization vector and reaches 200 kV/cm. At surface microirregularities, the electric field strength is much higher. This means that field emission is responsible for electron escape from the ferroelectric ceramic during pulsed polarization switching. 相似文献
49.
50.
B. A. Usievich D. Kh. Nurligareev V. A. Sychugov K. M. Golant 《Optics and Spectroscopy》2006,101(6):930-934
A system of tunnel-coupled rectilinear waveguides is studied. The dependence of the number of modes in this system on the number of waveguides N, the distance between the waveguides, and the number of modes in a separate waveguide is considered. It is shown that the modes of the m = N and N + 1 orders in such a system are Bragg modes; i.e., the angle between the direction of their propagation and the system axis is close to the Bragg angle. The effective refractive indices n * of these modes change stepwise. The step size Δn * is found to be dependent on the distance s between the waveguides and on the number of modes in a separate waveguide. A system of single-mode waveguides with the number of guided modes M = 34 < N = 50 is studied experimentally. It is shown that the Bragg modes of the system lie among the leakage modes of the system and have rather low losses. It is demonstrated that the localization of the Bragg modes among the leakage modes may be favorable for their selection upon light generation. 相似文献