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排序方式: 共有5107条查询结果,搜索用时 921 毫秒
991.
In this note, we clarify a technical point of Ref. 1, devoted to studying a constrained approximate controllability for the heat equation. 相似文献
992.
利用谱表示理论和微扰展开法,从理论上给出了适合于一般微结构复合体系的有效非线性响 应的一般表示式,并结合有效媒质近似(EMA),在弱非线性条件下研究了由三阶非线性组 分(体积分数为p)和线性组分构成的非线性复合体系的有效非线性响应,讨论了复合 体系的有效介电常数ε~e=εe+χe|E0|2+ηe|E0| 4中的有效三次非线性响应χe和有效高次非线性响应ηe与体积分数p和 退极化因子L之间的关系,分析了非线性组分的介电常数为复数情形时体系的有效高阶非线 性响应,从理论上说明了组分的高次非线性响应对整个复合体系的有效介电常数的影响.
关键词:
非线性复合介质
有效非线性响应
谱表示理论 相似文献
993.
We solve the inverse spectral problem of recovering the singular potential from W−12(0,1) of a Sturm-Liouville operator by its spectra on the three intervals [0,1], [0,a], and [a,1] for some a∈(0,1). Necessary and sufficient conditions on the spectral data are derived, and uniqueness of the solution is analyzed. 相似文献
994.
S. Lototsky 《Statistical Inference for Stochastic Processes》2003,6(1):65-87
A two-dimensional parameter is estimated from the observations of a random field defined on a compact manifold by a stochastic parabolic equation. Unlike the previous works on the subject, the equation is not necessarily diagonalizable, and no assumptions are made about the eigenfunctions of the operators in the equation. The estimator is based on certain finite-dimensional projections of the observed random field, and the asymptotic properties of the estimator are studied as the dimension of the projection is increased while the observation time is fixed. Simple conditions are found for the consistency and asymptotic normality of the estimator. An application to a problem in oceanography is discussed. 相似文献
995.
E. D. V. Nagesh G. Santosh Babu V. Subramanian V. Sivasubramanian V. R. K. Murthy 《Pramana》2005,65(6):1115-1120
We report the use of low dielectric constant materials to form two-dimensional microwave band-gap structures for achieving
high gap-to-midgap ratio. The variable parameters chosen are the lattice spacing and the geometric structure. The selected
geometries are square and triangular and the materials chosen are PTFE (ε = 2.1), PVC (ε = 2.38) and glass (ε = 5.5). Using the plane-wave expansion method, proper lattice spacing is selected for each structure and material. The observed
experimental results are analyzed with the help of the theoretical prediction 相似文献
996.
997.
We investigate the problem of bound states for bosons and fermions in the framework of the relativistic configurational representation with the kinetic part of the Hamiltonian containing purely imaginary finite shift operators e±ihd/dx instead of differential operators. For local (quasi)potentials of the type of a rectangular potential well in the (1+1)-dimensional case, we elaborate effective methods for solving the problem analytically that allow finding the spectrum and investigating the properties of wave functions in a wide parameter range. We show that the properties of these relativistic bound states differ essentially from those of the corresponding solutions of the Schrödinger and Dirac equations in a static external potential of the same form in a number of fundamental aspects both at the level of wave functions and of the energy spectrum structure. In particular, competition between ? and the potential parameters arises, as a result of which these distinctions are retained at low-lying levels in a sufficiently deep potential well for ? ? 1 and the boson and fermion energy spectra become identical. 相似文献
998.
Spontaneous edge currents are known to occur in systems of two space dimensions in a strong magnetic field. The latter creates
chirality and determines the direction of the currents. Here we show that an analogous effect occurs in a field-free situation
when time reversal symmetry is broken by the mass term of the Dirac equation in two space dimensions. On a half plane, one
sees explicitly that the strength of the edge current is proportional to the difference between the chemical potentials at
the edge and in the bulk, so that the effect is analogous to the Hall effect, but with an internal potential. The edge conductivity
differs from the bulk (Hall) conductivity on the whole plane. This results from the dependence of the edge conductivity on
the choice of a selfadjoint extension of the Dirac Hamiltonian. The invariance of the edge conductivity with respect to small
perturbations is studied in this example by topological techniques
Mathematics Subject Classification (2000). 81Q10, 58J32 相似文献
999.
1000.