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941.
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   
942.
For the equationdy (t)/dt=Ay(t) + p, t [0, ), where A is a closed linear operator on a Banach space , p is an unknown parameter from , we consider the problem
  相似文献   
943.
Asymptotic expansions with respect to a small parameter e are constructed for a fundamental system of solutions of a linear singularity perturbed system of equations of the form
  相似文献   
944.
The excitation of instability of the boundary layer on a curved surface in the limit R (R is the Reynolds number) is analyzed.Translated from Izvestiya Akademii Nauk SSSR, Mekhanika Zhidkosti i Gaza, No. 1, pp. 176–179, January–February, 1990.I am grateful to O. S. Ryzhov for his interest in the work.  相似文献   
945.
It is shown, in particular, that if n k when n k, Re n > 0, and , then an entire function F that is bounded on the real line and represented by a Dirichlet series dn exp (nz) that is uniformly and absolutely convergent on each compactum in is identically zero.Translated from Ukrainskii Matematicheskii Zhurnal, Vol. 42, No. 7, pp. 882–888, July, 1990.  相似文献   
946.
We study the algebra of functions on the set of natural numbers with respect to the generalized convolution, generated by the generalized translation operator Tnf(k)=f(max (n, k)), n, k. With the help of the generalized Fourier transform, connected with this convolution, we establish numerous identities and recurrence relations, connecting, in particular, sums of powers of natural numbers.Translated from Ukrainskii Matematicheskii Zhurnal, Vol. 42, No. 3, pp. 372–377, March, 1990.  相似文献   
947.
Ordinary differential equations with impulse action are considered at fixed moments of time when finite limits points are admitted to the set of moments of the shocks. The topological structure of this set is clarified: it must be resolvable, in particular nowhere dense in R.Translated from Ukrainskii Matematicheskii Zhurnal, Vol. 42, No. 3, pp. 378–383, March, 1990.  相似文献   
948.
The 1H spin-lattice relaxation curves of water in samples of natural porous media can be thought of as "fingerprints" of the porous samples. Also the whole of traditional petrophysical properties (permeability, irreducible water saturation, etc.) can be thought of as "fingerprints" of the porous samples. The characteristics of the pore space determine on one hand the relaxation curve shape, and on the other the petrophysical properties. The understanding of this correspondence can contribute to a better definition of the concept of the architecture of a porous medium. At this purpose we have obtained 1H spin-lattice relaxation curves from a collection of standard sandstone cores of known petrophysical properties and characterized by the same surface properties. The results corroborate the idea that the structure of relaxation curves contains information on the distance scale and on the architecture of the pore space, even if it is difficult to extract it without ambiguities. Different methods of curve fitting were performed and compared with the aim of getting the maximum information from the relaxation curves. Several aspects of this kind of investigation indicate the analogies between 1H response of water confined in porous media and in biological tissues.  相似文献   
949.
A general form of chronological ordering is proposed, based on introduction of relativistically invariant multipoint step functions (x1, ..., xn). A system of recursive relations is established for these functions, which guarantees that the scattering matrix is unitary, covariant, and causal. The explicit form of the first four -functions is found. A comparative analysis of the known methods of chronological ordering is given.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 5, pp. 70–73, May, 1990.  相似文献   
950.
The simplest gauge theory of an elastic-plastic medium is considered in this paper that takes account of just translational plasticity. The equations of motion for such a model turn out to be linear and permit the normal modes spectrum of a medium to be obtained. Taking account of plasticity results in a cardinal transformation of the elastic branches of the spectrum and the appearance of a group of plasma oscillations of a dislocation gas.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 6, pp. 64–68, June, 1990.  相似文献   
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