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101.
It is shown that the magnetoresistance (as a function of magnetic field H) in polycrystalline magnetic superconductors has the percolation character which is the consequence of the anisotropy of magnetic susceptibility. The magnetoresistance Rm(H), and the upper critical field Hc2(T) of ErRh4B4 are evaluated and compared with the experimental data. 相似文献
102.
The influence of impurity scattering is studied theoretically in a two-layer model for the high-T
c
superconductor Y1Ba2Cu3O7– with intra- and inter-layer pairing. Two types of impurities are considered: (I) impurities which conserve the reflection symmetry of the two layers and (II) impurities which break it. Impurities of type (I) have no influence on the critical temperature. Type (II) impurities have strong influence onT
c
as well as onH
c2
if there is a pairing interaction between carriers of different layers. The treatment of type (II) impurities is generalized to a periodic layer model appropriate for La2–x
Ba
x
CuO4. Available experiments on impurities in Y1Ba2Cu3O7– and La2–x
Ba
x
CuO4 are interpreted with our theory. 相似文献
103.
Electrical and electrochemical properties of solid LiH2PO4 conductor were investigated in the temperature range from room temperature to 373 K. It was found that high conductivity throughout the temperature range, with activation energy 17.23 kJ/mol, originates from the movement of hydrogen ions (protons). The movement of protons in the correlation with phosphate groups rotation was considered. The slopes of Tafel lines and exchange current densities both for cathodic hydrogen and anodic oxygen evolution were determined (by means of usual electrochemical kinetic methods) at various temperatures. The energy of activation at the equilibrium potentials both for the cathodic and the anodic processes have been assessed to be 17.23 kJ/mol (0.18 eV) and 2.9 kJ/mol (0.03 eV), respectively. 相似文献
104.
Dragan Mašulović 《Order》2007,24(4):215-226
A structure is called homogeneous if every isomorphism between finite substructures of the structure extends to an automorphism
of the structure. Recently, P. J. Cameron and J. Nešetřil introduced a relaxed version of homogeneity: we say that a structure
is homomorphism-homogeneous if every homomorphism between finite substructures of the structure extends to an endomorphism
of the structure. In this paper we characterize homomorphism-homogeneous partially ordered sets (where a homomorphism between
partially ordered sets A and B is a mapping f : A →B satisfying ). We show that there are five types of homomorphism-homogeneous partially ordered sets: partially ordered sets whose connected
components are chains; trees; dual trees; partially ordered sets which split into a tree and a dual tree; and X
5-dense locally bounded partially ordered sets.
Supported by the Ministry od Science and Environmental Protection of the Republic of Serbia, Grant No. 144017. 相似文献
105.
Wei-Ping Zhong Milivoj Belić 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2014,68(11):1-6
An exact (2 + 1)-dimensional spatial optical soliton of the nonlinear Schrödinger equation with a spatially modulated nonlinearity and a special external potential is discovered in an inhomogeneous nonlinear medium, by utilizing the similarity transformation. Exact analytical solutions are constructed by the products of Whittaker functions and the bright and dark soliton solutions of the standard stationary nonlinear Schrödinger equation. Some examples of such composed solutions are given, in which these spatial solitons display different localized structures. Numerical calculation shows that the soliton is stable in propagating over long distances, thus also confirming the validity of the exact solution. 相似文献
106.
J.C. Lasjaunias P. Monceau D. Starešinić K. Biljaković 《The European Physical Journal B - Condensed Matter and Complex Systems》2002,28(2):187-190
Eur. Phys. J. B 24, 315 (2001) In our Reply to the Comment [#!1!#] we refute the “straightforward” interpretation of the excess low-temperature
specific heat, Cp, contribution we have measured in our study of CDW systems K0.3MoO3 and (TaSe4)2I [#!2!#] as originating solely from normal phonon modes. The specific sensitivity of the bump in C
p
/
T
3
at low temperatures to the impurity content is consistent with the increased value of the phason pinning gap while the dispersion
of normal phonons remains unaffected. We ascribe at least this part of the anomaly to the phason contribution. As stated in
reference [3] that the phonon density of states extracted from neutron scattering measurements is the least reliable in this
energy range (<0.5 meV), we conclude that Cp measurements are more accurate for detecting the phason contribution.
Received 17 April 2002 Published online 19 July 2002 相似文献
107.
Dirac cohomology is a new tool to study representations
of semisimple Lie groups and Lie algebras. The aim
of this paper is to define a Dirac operator for a
Lie superalgebra of Riemannian type and show that
this Dirac operator has similar nature as the one
for semisimple Lie algebras. As a consequence, we
show how to determine the infinitesimal character
of a representation by the infinitesimal character
of its Dirac cohomology. 相似文献
108.
S. S. Dragomir 《Acta Mathematica Hungarica》2005,109(4):331-345
Summary General divergence measures for probability distributions are introduced and their main properties established. Connections
with f-divergence corresponding to a convex function fare explored. 相似文献
109.
Sever Silvestru Dragomir 《Numerical Functional Analysis & Optimization》2013,34(5-6):487-491
A simple model optimal control problem for continuous casting with state-space constraints is approximated, as usual, by a penalty method and by a numerical discretization of the nonlinear heat equation. The convergence of the approximate problems directly to the original problem is proven under a stability criterion linking the penalty parameter with the discretization parameters. For this purpose, known discretization error estimates for the Stefan problem are extended for the case of time varying boundary conditions. 相似文献
110.