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1.
《Comptes Rendus Physique》2015,16(2):227-240
Multiferroics are gathering solid-state matter in which several types of orders are simultaneously allowed, as ferroelectricity, ferromagnetism (or antiferromagnetism), ferroelasticity, or ferrotoroidicity. Among all, the ferroelectric/ferromagnetic couple is the most intensively studied because of potential applications in novel low-power magnetoelectric devices. Switching of one order thanks to the other necessarily proceeds via the nucleation and growth of coupled domains. This review is an introduction to the basics of ferroelectric/ferromagnetic domain formation and to the recent microscopy techniques devoted to domains imaging, providing new insights into the archetypal multiferroic domain morphologies. Some relevant examples are also given to illustrate some of the unexpected properties of domain walls, as well as the way these domain walls can be manipulated altogether thanks to various types of magnetoelectric coupling. 相似文献
2.
给出强Z-连续domain和Z-代数domain的一个刻画及一个范畴性质--余反射性质. 相似文献
3.
Ren-Geng Xiong 《中国化学快报》2013,24(8):681-684
The temperature-dependent,second-order,nonlinear,optical coefficient(x(2)).piezoelectric coefficient (d33),pyroelectric coefficient(Ps) and domains on triglycine sulfate(TGS) reported herein provide a clue for us to investigate these as a typical second-order phase transition.The symmetry breaking occurrence is definitely confirmed by the temperature-dependent x(2) in which x(2) displays a limited value at the ferroelectric phase,indicating the space group(P21) chosen is correct,and when x(2) basically maintains a zero value at the paraelectric phase,indicating the space group should be centric.Interestingly,after normalization of x(2),d33 or Ps,the change trend with temperature is basically overlapped,probably abiding by Landau theory.Moreover,temperature-dependent domains directly show the symmetry breaking occurrence. 相似文献
4.
Zhenkun Huang Sannay Mohamad Chunhua Feng Guorong Cai 《Applied Mathematical Modelling》2010,34(1):80-91
This paper presents new dynamical behavior, i.e., the coexistence of 2N domains of attraction of N-dimensional nonautonomous neural networks with time-varying delays. By imposing some new assumptions on activation functions and system parameters, we construct 2N invariant basins for neural system and derive some criteria on the boundedness and exponential attractivity for each invariant basin. Particularly, when neural system degenerates into periodic case, we not only attain the coexistence of 2N periodic orbits in bounded invariant basins but also give their domains of attraction. Moreover, our results are suitable for autonomous neural systems. Our new results improve and generalize former ones. Finally, computer simulation is performed to illustrate the feasibility of our results. 相似文献
5.
Ioan R. Ionescu Darko Volkov 《Journal of Computational and Applied Mathematics》2008,220(1-2):143-162
We study in this paper an eigenvalue problem (of Steklov type), modeling slow slip events (such as silent earthquakes, or earthquake nucleation phases) occurring on geological faults. We focus here on a half space formulation with traction free boundary condition: this simulates the earth surface where displacements take place and can be picked up by GPS measurements. We construct an appropriate functional framework attached to a formulation suitable for the half space setting. We perform an asymptotic analysis of the solution with respect to the depth of the fault. Starting from an integral representation for the displacement field, we prove that the differences between the eigenvalues and eigenfunctions attached to the half space problem and those attached to the free space problem, is of the order of d-2, where d is a depth parameter: intuitively, this was expected as this is also the order of decay of the derivative of the Green's function for our problem. We actually prove faster decay in case of symmetric faults. For all faults, we rigorously obtain a very useful asymptotic formula for the surface displacement, whose dominant part involves a so called seismic moment. We also provide results pertaining to the analysis of the multiplicity of the first eigenvalue in the line segment fault case. Finally we explain how we derived our numerical method for solving for dislocations on faults in the half plane. It involves integral equations combining regular and Hadamard's hypersingular integration kernels. 相似文献
6.
Tomasz J. Kozubowski Mark M. Meerschaert Anna K. Panorska Hans-Peter Scheffler 《Journal of multivariate analysis》2005,92(2):715-323
Operator geometric stable laws are the weak limits of operator normed and centered geometric random sums of independent, identically distributed random vectors. They generalize operator stable laws and geometric stable laws. In this work we characterize operator geometric stable distributions, their divisibility and domains of attraction, and present their application to finance. Operator geometric stable laws are useful for modeling financial portfolios where the cumulative price change vectors are sums of a random number of small random shocks with heavy tails, and each component has a different tail index. 相似文献
7.
设Ω为Rn中—Lipschitz区域,ST为柱形域的边界Ω×(0,T)本文研究了此区域上的一般二阶常系数抛物方程具Lpq边值的抛物方程边值问题.采用R.Brown和Z.Shen的方法,我们证明了所涉及的双层位势和单层位势算子的可逆性,从而证明了初边值问题的唯一可解性,而且这种解可由位势算子表示. 相似文献
8.
V.V. Moshkin V.I. Ozhogin V.L. Preobrazhensky N.A. Economov 《Journal of magnetism and magnetic materials》1997,170(3):127-288
Non-uniform spin states (stripe domains) are induced by powerful pulse ultrasonic waves in a hematite (-Fe2O3) single crystal. These states are visualized with the help of the Cotton-Mouton effect and quantitatively described in terms of an effective field proportional to the square of ultrasound amplitude. 相似文献
9.
For an arbitrary bounded closed set E in the complex plane with complement Ω of finite connectivity, we study the degree of convergence of the lemniscates in Ω. 相似文献
10.
Andrew Raich 《Mathematische Zeitschrift》2007,256(1):193-220
Let be a subharmonic, nonharmonic polynomial and a parameter. Define , a closed, densely defined operator on . If and , we solve the heat equations , u(0,z) = f(z) and , . We write the solutions via heat semigroups and show that the solutions can be written as integrals against distributional
kernels. We prove that the kernels are C
∞ off of the diagonal {(s, z, w) : s = 0 and z = w} and find pointwise bounds for the kernels and their derivatives.
相似文献