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1.
In a two-dimensional array of magnetic moments with planar magnetization and relatively weak anisotropy in the basal plane, a stepwise phase transition is induced by an external magnetic field parallel to the easy axis of the system. This transition is similar to the spin flop phase transition in weakly anisotropic Heisenberg antiferromagnets with the significant difference that it is accompanied by the rearrangement of the sublattice structure of the magnet; i.e., it can be interpreted as a topological transition. The transition should manifest itself for arrays of submicron magnetic particles (magnetic dots) on nonmagnetic substrates, which have recently become the object of intensive research. 相似文献
2.
J. Gasser M.A. Ivanov E. Lipartia M. Mojzis A. Rusetsky 《The European Physical Journal C - Particles and Fields》2002,26(1):13-34
We investigate the ground-state energy of the atom (pionic hydrogen) in the framework of QCD + QED. In particular, we evaluate the strong energy-level shift. We perform
the calculation at next-to-leading order in the low-energy expansion in the framework of the relevant effective field theory.
The result provides a relation between the strong energy shift and the pion-nucleon S-wave scattering lengths - evaluated in pure QCD - at next-to-leading order in isospin-breaking and in the low-energy expansion.
We compare our result with available model calculations.
Received: 11 June 2002 / Published online: 9 October 2002 相似文献
3.
A. V. Ivanov M. Yu. Tsentalovich E. G. Kogan L. G. Tomilova N. S. Zefirov 《Russian Chemical Bulletin》2008,57(8):1676-1679
The chlorination of benzene, toluene, and o-xylene with molecular chlorine in the presence of the phthalocyanine complexes of different structures was studied. The transformations
of the catalysts during the reaction were investigated.
Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 8, pp. 1644–1647, August, 2008. 相似文献
4.
Results of measuring the monochromatic sound field with a dipping probe in the deep ocean are presented. The sound speed profile in the region of measurements had a minimum at a depth of 1600 m. The experiment was carried out in the Atlantic Ocean with the use of two vessels separated by a distance of approximately four ray cycles (~240 km). The experimental data are compared with the calculations based on a new concept of the Brillouin waves for describing the vertical structure of the sound field produced by rays. It is shown that a satisfactory agreement between experiment and calculation can be achieved by fitting the parameters of the experiment. Such a procedure allows one to refine or even to determine the experimental conditions, which not are always known. The proposed method of calculation offers an opportunity for solving inverse problems of ocean acoustics. 相似文献
5.
The dependence of the nonlinear reflection coefficient R of a mirror with a wavefront reversing surface on the intensity I
of the reference wave is analyzed in terms of a phenomenological model of a medium having a nonlinear Fresnel reflection amplitude
coefficient φ. Substantial differences are revealed for media having different signs of the nonlinearity coefficient β=(dφ/dI).
It is shown that R is related to the magnitude D of the dynamic range of the wavefront reversing mirror by the expression
RD=Qs' where Qs is a parameter which defines the “quality” of the nonlinear medium.
Far-Eastern State Academy of Communications. Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 8, pp. 68–70,
August, 1997. 相似文献
6.
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
7.
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
8.
9.
S. V. Ivanov V. V. Trachevskii O. S. Titova L. A. Zozulya 《Russian Journal of Applied Chemistry》2006,79(10):1712-1714
Experimental data demonstrate that a study of accelerated aging can enable prognostication of the working capacity and storage life of polymeric formulations used in aircraft components on the basis of changes in thermogravimetric constants of these polymeric formulations. 相似文献
10.
The not-sufficient-enough conductance of semioxidized protonated polyaniline (PANI) is usually attributed to the presence of ordered quasi-metallic domains surrounded by a poorly conducting amorphous phase. The paper presents experimental results testifying to the existence, in semioxidized PANI, of multilevel redox heterogeneity that crucially effects the conductance magnitude in view of specific topology at which higher-oxidized (conducting) domains are surrounded by less oxidized (poorly conducting) domains and because the PANI conduction is extremely sensitive to the oxidation degree. It is shown experimentally that the interphase doping with metals and degenerate semiconductors of a semioxidized salt of PANI and poly(2-acrylamide-2-methyl-1-propanesulfonic acid) (PAMPSA) with a 1: 2 ratio between PANI and PAMPSA raises the PANI-PAMPSA conductivity by 3–8 orders of magnitude due to the formation near the interface of thin layers whose conductance depends on the work function of the material in contact with PANI-PAMPSA and in extreme cases substantially exceeds the conductance of gold and copper at room temperature. 相似文献