Holographic dual of linear dilaton black hole in Einstein-Maxwell-dilaton-axion gravity

Motivated by the recently proposed Kerr/CFT correspondence, we investigate the holographic dual of the extremal and non-extremal rotating linear dilaton black hole in Einstein-Maxwell-Dilaton-Axion Gravity. For the case of extremal black hole, by imposing the appropriate boundary condition at spatial infinity of the near horizon extremal geometry, the Virasoro algebra of conserved charges associated with the asymptotic symmetry group is obtained. It is shown that the microscopic entropy of the dual conformal field given by Cardy formula exactly agrees with Bekenstein-Hawking entropy of extremal black hole. Then, by rewriting the wave equation of massless scalar field with sufficient low energy as the SLL(2, R) x SLR(2, R) Casimir operator, we find the hidden conformal symmetry of the non-extremal linear dilaton black hole, which implies that the non-extremal rotating linear dilaton black hole is holographically dual to a two dimensional conformal field theory with the non-zero left and right temperatures. Furthermore, it is shown that the entropy of non-extremal black hole can be reproduced by using Cardy formula.

Effective response of nonlinear composite under external AC and DC electric field

A perturbation method is used to study effective response of nonlinear Kerr composites, which are subject to the constitutive relation of electric displacement and electric field, D-alpha = epsilon(alpha)E + chi(alpha)vertical bar E vertical bar(2)E. Under the external AC and DC electric field E-app = E-a (1 + sinwt), the effective nonlinear responses and local potentials are induced by the cubic nonlinearity of Kerr materials at all harmonics. As an example in three dimensions, we have investigated this kind of nonlinear composites with spherical inclusions embedded in a host. At all harmonic frequencies, the potentials in inclusion and host regions are derived. Furthermore, the formulae of the effective linear and nonlinear responses are given in the dilute limit.

A theory of nonlinear AC response in coated composites

A method for determining effective dielectric responses of Kerr-like coated nonlinear composites under the alternating current (AC) electric field is proposed by using perturbation approach. As an example, we have investigated the composite with coated cylindrical inclusions randomly embedded in a host under an external sinusoidal field with finite frequency omega. The local field and potential of composites in general consists of components with all harmonic frequencies. The effective nonlinear AC responses at all harmonics are induced by the coated nonlinear composites because of the nonlinear constitutive relation. Moreover, we have derived the formulae of effective nonlinear AC responses at the fundamental frequency and the third harmonic in the dilute limit.

Effective ac response in weakly nonlinear composites

The perturbation method is developed to deal with the problem of determining the effective nonlinear conductivity of Kerr-like nonlinear media under an external ac electric field. As an example, we have considered the cylindrical inclusion embedded in a host under the sinusoidal external field E-1 sin(omegat) + E-3 sin(3omegat) with frequencies omega and 3omega. The potentials of composites at higher harmonics are derived in both local inclusion particle and host regions. The effective responses of bulk nonlinear composites at basic frequency and harmonics are given for cylindrical composites in the dilute limit. Moreover, the relationships between the nonlinear effective responses at the basic frequency and the third harmonics are derived.

Effective dielectric response of nonlinear composites with external ac and dc electric field

The perturbation method is developed to investigate the effective nonlinear dielectric response of Kerr composites when the external ac and dc electric field is applied. Under the external ac and dc electric field E-app=E-a(1+sin omegat), the effective coupling nonlinear response can be induced by the cubic nonlinearity of Kerr nonlinear materials at the zero frequency, the finite basic frequency omega, the second and the third harmonics, 2omega and 3omega, and so on. As an example, we have investigated the cylindrical inclusions randomly embedded in a host and derived the formulas of the effective nonlinear dielectric response at harmonics in dilute limit. For a higher concentration of inclusions, we have proposed a nonlinear effective-medium approximation by introducing the general effective nonlinear response. With the relationships between the effective nonlinear response at harmonics and the general effective nonlinear response, we have derived a set of formulas of the effective nonlinear dielectric responses at harmonics for a larger volume fraction. (C) 2004 American Institute of Physics.

The nonlinear effective dielectric response of graded composites

The perturbation method is developed to deal with the effective nonlinear dielectric responses of weakly nonlinear graded composites, which consist of the graded inclusion with a linear dielectric function of spatial variables of inclusion material. For Kerr-like nonlinear graded composites, as an example in two dimensions, we have used the perturbation method to solve the boundary value problems of potentials, and studied the effective responses of nonlinear graded composites, where a cylindrical inclusion with linear dielectric function and nonlinear dielectric constant is randomly embedded in a homogeneous host with linear and nonlinear dielectric constants. For the exponential function and the power-law dielectric profiles of cylindrical inclusions, in the dilute limit, we have derived the formulae of effective nonlinear responses of both graded nonlinear composites.

海洋复合物的介电特性在海洋遥感中的应用

利用一种摄动方法研究了非线性 Kerr型复合介质的有效性响应。在外加直流电和交流电混合电场的激发下，各谐和频率下的有效非线性响应和相应的电势都可以被这种Kerr型复合介质的立方非线性特性所感应出。研究了背景介质内含这种非线性复合介质球形颗粒的情形；导出了各谐和频率下的球形内、外电势；给出了低浓度下这种有效的非线性和线性的响应的公式。另外，研究了强风引起的海浪破碎对海洋微波遥感的影响。根据白冠层中气泡和水滴随机分布的特点，采用了物理学上的有效介质近似理论，将海浪破碎形成的白冠层看作均匀分布在海面上的一层水滴和气泡等同背景介质的复合介质。在被动遥感方面提出了一个改进的研究海浪破碎产生白冠时海水有效发射率的模式，讨论了白冠层中主要成分为球形气泡和水滴的情况，并着重分析了海－气温差对海水发射率的影响，研究表明海水发射率随着海－气温差的增大而增大。通过计算白冠层中的有效介电常数，该模式考虑到了白冠层的有效粒子的气泡结构、泡沫层厚度等物理参量对海水发射率的影响。在主动遥感方面利用两种随机粗糙面的电磁波散射模型研究了海浪破碎时的海面微波后向散射，讨论了复合海水粒子的形状（如球形、椭球形）和海水的温度等对后向散射系数的影响。数值模拟结果很好的匹配了遥感（实测、实验）数据。证明了本论文采用的微波遥感模式的合理、可行性。最后根据上述模式计算特殊环境（降雨）对微波遥感所产生的影响。

南亚和东南亚龙胆属(龙胆科)的新名称、新组合及分类注释(英文)

本文提出了龙胆属两个种的新名称 (GentianamembranuliferaT .N .Ho,G .nudicaulis Kurz var.as samensisT .N .Ho )和 5个变种的新组合 [(Gentianalateriflora Hemsl.var.uncifolia (H.J.Lam)T.N.Ho,G.sumatranaRidl.var.humifusa (S .Moore)T .N .Ho ,G .quadrifariaBl.var.wightii(Kusnez.)T .N .Ho,G .loerzingiiRidl.var.timida (Kerr)T .N .Ho ,G .membranuliferaT .N .Hovar.recurvata (Kusnez.)T .N .Ho) ]。