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951.
Conclusion In a planar logarithmic spiral excited at its periphery there simultaneously exist surface, quasieffluent, and radiated waves; the phase velocities of surface and quasieffluent waves are identical and depend on the reduced radius k, which defines the regions of normal and anomalous dispersion; in the region kn the surface wave transforms to a radiated one by means of the quasieffluent; the directional pattern differs little from that for central excitation, with ellipticity coefficient of a spiral open at the center varying from 0.7 to 0.9 over a 1:2 frequency range; the input impedance depends weakly on the presence of reflection at the center of the spiral, is of an oscillating character, and changes more intensely than for central excitation.Khar'kov State University. Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Radiofizika, Vol. 33, No. 1, pp. 78–84, January, 1990. 相似文献
952.
H. -J. Simonis S. Kremeyer F. Hagelberg U. Reuter M. Knopp K. -H. Speidel J. Cub W. Karle P. N. Tandon J. Gerber 《Hyperfine Interactions》1990,61(1-4):1351-1354
From hyperfine interaction studles on free single electron16O(3−) ions. in a time differential mode using the recoil distance technique. It is shown that these ions are polarized when emerging
from magnetized thin layers of Fe. The observed degree of polarization
, however, is smaller than expected from transient field measurements. 相似文献
953.
954.
955.
In this paper, we treat a domain optimization problem in which the boundary-value problem is a Neumann problem. In the case where the domain is in a three-dimensional Euclidean space, the first-order and the second-order necessary conditions which the optimal domain must satisfy are derived under a constraint which is the generalization of the requisite of constant volume.Portions of this paper were presented at the 13th IFIP Conference on System Modelling and Optimization, Tokyo, Japan, 1987. 相似文献
956.
This paper is concerned with the structure of periodic meta-Hamiltonian groups with elementary commutant of rank 2 that have complemented Miller Moreno subgroups. It is proved that there exist four types of such groups.Translated from Ukrainskii Matematicheskii Zhurnal, Vol. 42, No. 2, pp. 168–175, February, 1990.The proof of this assertion will be given in another paper of the authors. 相似文献
957.
N. V. Zorii 《Ukrainian Mathematical Journal》1990,42(4):438-443
For a condenser E in an open set D R
p
, p 3, the problem of the minimum of the Green energy in a class of charges, associated with E, is solved.Translated from Ukrainskii Matematicheskii Zhurnal, Vol. 42, No. 4, pp. 494–500, April, 1990. 相似文献
958.
Wave processes in dissipative-dispersive media with instability described by a fourth-order nonlinear evolution equation are considered. Analytic solutions in the form of solitary and cnoidal waves are obtained. The existence of a critical value of the dispersion coefficient beyond which an initial disturbance (in particular, white noise) is transformed into a structure is demonstrated by numerical modeling.Translated from Izvestiya Akademii Nauk SSSR, Mekhanika Zhidkosti i Gaza, No. 4, pp. 130–136, July–August, 1990. 相似文献
959.
M. N. El Tarazi 《BIT Numerical Mathematics》1990,30(3):484-489
The interpolation problem at uniform mesh points of a quadratic splines(x
i)=f
i,i=0, 1,...,N ands(x
0)=f0 is considered. It is known that s–f=O(h
3) and s–f=O(h
2), whereh is the step size, and that these orders cannot be improved. Contrary to recently published results we prove that superconvergence cannot occur for any particular point independent off other than mesh points wheres=f by assumption. Best error bounds for some compound formulae approximatingf
i
andf
i
(3)
are also derived. 相似文献
960.
We investigate representations of classical noncompact Lie groups induced by representations of the maximal parabolic subgroup. Formulas are obtained for 5O0(2p, 2q)/U(p, q) and U(2p, 2q) Sp(p, q).Translated from Ukrainskii Mathematicheskii Zhurnal, Vol. 42, No. 1, pp. 128–131, January, 1990. 相似文献