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101.
The work is related to the problem by P. Erds about the estimation of the numbers
as N.We shall deal with the case where the z
j are all possible roots of the unity ordered in such a way that all the roots of degree n follow the roots of degree n-1. Within the group of roots of degree n, the enumeration can vary. We prove that ln A
N grows like N, and we get estimates of possible values of the lower limit of the ratio (ln A
N
/N as well as exact bounds of the upper limit of this ratio. 相似文献
102.
Mihail?MeganEmail author Adina?Lumini?a?Sasu Bogdan?Sasu 《Integral Equations and Operator Theory》2004,50(4):489-504
The aim of this paper is to give necessary and sufficient conditions for pointwise and uniform exponential dichotomy of linear skew-product flows. We shall obtain that the pointwise exponential dichotomy of a linear skew-product flow is equivalent to the pointwise admissibility of the pair
As a consequence, we prove that a linear skew-product flow on
is uniformly exponentially dichotomic if and only if the pair
is uniformly admissible for . 相似文献
103.
Suppose that
is a 0-symmetric convex body
which denes the usual norm
on
. Let also
be a measurable set of positive upper density .
We show that if the body K is not a polytope, or if it is a polytope with
many faces (depending on ), then the distance set
contains all points t t0 for some positive number t0 . This was proved
by Furstenberg, Katznelson and Weiss, by Falconer and Marstrand and
by Bourgain in the case where K is the Euclidean ball in any dimension
greater than 1. As corollaries we obtain (a) an extension to any dimension
of a theorem of Iosevich and Laba regarding distance sets with respect to
convex bodies of well-distributed sets in the plane, and also (b) a new proof
of a theorem of Iosevich, Katz and Tao about the nonexistence of Fourier
spectra for smooth convex bodies with positive curvature. 相似文献
104.
Connections between uniform exponential expansiveness and complete admissibility of the pair
are studied. A discrete version for a theorem due to Van Minh, Räbiger and Schnaubelt is presented. Equivalent characterizations of Perron type for uniform exponential expansiveness of evolution families in terms of complete admissibility are given. 相似文献
105.
The problem of sound propagation in a spatially inhomogeneous underwater sound channel is considered. The effect of ray escape, i.e., the ray incidence on the absorbing bottom due to the chaotic swing of rays, is studied. With the use of the Poincaré map and maps of escape, the relation of ray escape to the properties of the phase space of the set of ray equations is demonstrated. It is found that the maximum escape occurs under the vertical resonance conditions, i.e., at the resonance of the ray oscillations in the waveguide with the vertical oscillations of the sound velocity perturbation. A qualitative theory of the vertical resonance is developed. It is shown that the ray escape considerably shortens the time spreading of the signal. 相似文献
106.
The morphology and structure of Pt deposited on a WSe2(0 0 0 1) van der Waals surface have been investigated by reflection high energy electron diffraction and scanning tunneling microscopy. At room temperature, the initial growth is characterized by the formation of three-dimensional fcc Pt islands with (1 1 1) orientation. In contrast, at higher temperatures of about 450 °C the formation of a novel chemically ordered Pt-Se alloy is observed. Based on the diffraction patterns, a tetragonal DO22-type structure of a Pt3Se compound is suggested. With increasing Pt thickness, this chemically ordered alloy disappears and an additional superstructure occurs, which is accompanied by the coalescence of the islands. The observed superstructure is attributed to a strong Se diffusion towards the growth surface, forming most likely a PtSe2 alloy with the CdI2-type layered structure on the top surface. Due to the lateral lattice mismatch between the Pt(1 1 1) layers and the PtSe2(1 1 1) top layer, a Moiré pattern with a period of 1.1 nm is created, which might be used as a long-range atomic pattern for further nanostructure growth. 相似文献
107.
V. V. Varlamov M. A. Makarov N. N. Peskov M. E. Stepanov 《Bulletin of the Russian Academy of Sciences: Physics》2014,78(5):412-420
Experimental data on the cross sections of partial photoneutron reactions, obtained for 188,189Os isotopes using quasimonoenergetic annihilation photon beams and neutron multiplicity sorting method, are analyzed. Using special criteria (transition multiplicity functions F i = σ(γ, in)/σ(γ, xn), the ratios of the cross section of the corresponding partial reaction to the total neutron yield reaction’s cross section σ(γ, xn) = σ(γ, 1n)+ 2σ(γ, 2n) + 3σ(γ, 3n) free of the problems associated with experimental neutron multiplicity sorting), it is demonstrated that the data contain significant systematic errors. New data are evaluated for cross sections of partial photoneutron reactions (γ, 1n), (γ, 2n), (γ, 3n) and total photoneutron reaction (γ, sn) for 188,189Os isotopes within an experimental-theoretical approach proposed earlier. It is shown that the significant systematic errors in the experimental cross sections of partial reactions can be attributed to the ambiguity of the relation between the photoneutrons’ multiplicity and their kinetic energy. 相似文献
108.
V. L. Makarov 《Journal of Mathematical Sciences》2001,104(6):1648-1653
In this article, we describe a functional–discrete method (FD>-method) for solving operator equations and abstract eigenvalue problems. The algorithm of the method includes a recurrent solution of a sequence of problems with a fixed operator, which is simpler than the initial one, and a changing right-hand side. We prove that, with fairly general assumptions, the FD-method converges with the rate of a geometric progression, i.e., has exponential convergence rate. 相似文献
109.
O. V. Bakbardina I. Yu. Pukhnyarskaya M. A. Gazalieva S. D. Fazylov E. M. Makarov 《Russian Journal of Applied Chemistry》2006,79(10):1726-1728
S-Amino derivatives of O-alkyldithiocarbonic acid were prepared by oxidative condensation of certain alkaloids with sodium xanthates. Some of the compounds synthesized exhibit fungicidal activity. 相似文献
110.
K. N. Makarov T. N. Abroskina Yu. A. Cheburkov I. L. Knunyants 《Russian Chemical Bulletin》1976,25(4):922-924
1. | The cesium chloride adducts with perfluoroacetone, 1-methyl-2-oxaperfluoroenanthyl fluoride, and perfluoroisobutylene react smoothly with symmetrical dichlorodimethyl ether, replacing both chlorine atoms, with the formation of the corresponding ethers. |
2. | The interaction of,-dihydroperfluoroamyl alcoholate with symmetrical dichlorodimethyl ether leads to the replacement of both chlorine atoms, with the formation of the corresponding ether. |
3. | The reaction of perfluoro-t-butylanion with tris(chloromethyl)amine leads to tris-(1,1-dihydro-perfluoroneopentyl) amine. |
4. | Perfluoro-t-butylanion replaces only one chlorine atom in the molecule of unsymmetrical di-chlorodimethyl ether, forming-chloro- -perfluoro-t-butyldimethyl ether. |