Collective diffusion in a two-dimensional liquid composed of Janus particles

The collective diffusion of anisotropic particles in liquids plays a crucial role in many processes, such as self-assembly. The patchy particle, which is usually nearly spherical in shape, is an important anisotropic particle with different properties from other anisotropic particles like the ellipsoid liquid crystal particles. In the present study, molecular dynamics simulations are performed to study the collective diffusion of a two-dimensional anisotropic liquid system composed of Janus particles. The static structures and diffusion behaviours of anisotropic and isotropic Lennard-Jones liquids are compared. The long-time diffusion behaviour of an anisotropic liquid of nearly spherical Janus particles is found to be similar to that of an isotropic liquid because the orientation of the particles disappears over long-term averaging. The anisotropic properties of the Janus particles are mainly reflected in the spatial correlation of particle orientations and mid-time diffusion behaviour. The difference between nearly spherical anisotropic particles and rod-like particles is also discussed in this paper.     

介质球的各向异性瑞利散射

基于电磁场的多尺度理论,研究了各向异性介质球内、外电场的规律,导出了各向异性目标散射场的表达式,得到了各向异性介质目标散射振幅、散射截面等的解析表达式,并对其正确性进行了检验.仿真结果表明:各向异性介质球的散射具有偶极辐射的特点,介电常量越大,产生的偶极矩也愈大,散射也越强.其结果可为各向异性目标监测、各向异性光散射研究等提供理论支持.     

电偶极子在磁各向异性介质中的辐射功率

在经典电动力学框架下对磁各向异性介质中的电磁辐射问题进行研究, 得到了电偶极子在磁各向异性介质中的辐射功率表达式. 当介质为磁各向同性时其结果与文献报道的结果相符合, 验证了推导结果的正确性. 利用本文结果可对电偶极子在磁各向异性介质中的辐射效果做出判断, 而且对于进一步研究磁各向异性介质的电磁特性、更有效地开发利用磁各向异性介质具有实际意义.     

各向异性渗透率油藏数值模拟

建立三维三相各向异性油藏渗流数值模拟模型并应用于油藏开发.模型包含完全各向异性渗透率张量,采用十九点有限差分格式和全隐式迭代方法求解.可以描述不同区域不同主方向的各向异性渗透率分布,准确计算各向异性油藏内流体运动过程、剩余油分布和压力分布.     

Anisotropic distribution of quantum‐vacuum momentum density in a moving electromagnetic medium

An isotropic electromagnetic medium becomes gyrotropically anisotropic when it moves, and an anisotropic electromagnetic environment can then be created in this motion‐induced anisotropic medium. One of the most remarkable features is that the quantum vacuum in the anisotropic electromagnetic environment exhibits a nonzero electromagnetic momentum density, since the universal symmetry of the vacuum fluctuation field is broken, and the anisotropic quantum vacuum mode structure is produced because of the symmetry breaking. This would give rise to a noncompensation effect among the four vacuum eigenmodes (i.e., the forward and backward propagating modes as well as their respective mutually perpendicular polarized components), and leads to an anisotropic correction to the vacuum momentum in the moving medium. The physical significance and the potential applications of the anisotropic quantum vacuum are discussed. This quantum‐vacuum effect may be used to develop sensitive sensor techniques and to design new quantum optical and photonic devices.     

Effect of recording conditions on the anisotropic diffraction of volume holographic gratings

The anisotropic Bragg diffraction of the volume holographic gratings in photorefractive crystals are investigated based on the model of anisotropic coupled-wave theory. The effect of the initial intensity ratio and the recording angles of the two recording waves on the anisotropic Bragg diffraction properties is discussed. It is shown that both the ratio of the initial intensity and the incident angles of the recording waves are selective action for the anisotropic Bragg diffraction efficiency of the volume holographic gratings, while these two recording conditions are not selective action for the isotropic Bragg diffraction. Furthermore, the Bragg phase matching condition of anisotropic diffraction is analyzed when the recording angles change.     

各向异性矩形悬臂板稳态热传导解析

应用各向异性稳态热传导解析解分析了三边对流换热、另一边给定不均匀温度的各向异性矩形悬臂板温度场。讨论了各向异性角对温度场分布的影响。各向异性角的增大加剧了温度梯度。数值结果表明各向异性角为0°的悬臂板内温度梯度最小。     

Anisotropic photonic crystals: Generalized plane wave method and dispersion symmetry properties

This article presents a generalized vector plane wave expansion method, applicable to isotropic and anisotropic periodic dielectric media of arbitrary geometry and dimension. The influence of anisotropic material orientation on the symmetry properties of photonic crystal dispersion surface is discussed. It is shown that the overall Brillouin zone symmetry is formed by the intersection of the photonic crystal lattice symmetry and the symmetry determined by the anisotropic material orientation. This work explains how to define the irreducible Brillouin zone of a two-dimensional anisotropic photonic crystal and demonstrates that doing it correctly allows one to avoid erroneous results, when calculating band gap diagrams of anisotropic photonic crystals. With the help of the methods presented, the possibility of controlling the band gaps of anisotropic photonic crystals by means of external electric field is shown.     

Anisotropic conical scattering in photorefractive BaTiO3: diffraction efficiency measurements

The simultaneous presence of beam fanning and anisotropic conical scattering hinders the exact measurements on anisotropic conical diffraction. In this paper, a method is described for the measurement of diffraction efficiency of the gratings responsible for anisotropic conical scattering in a photorefractive BaTiO₃ crystal. Dependence of diffraction efficiency on the angle of incidence of the incident beam and the build-up processes of beam fanning and anisotropic scattering have been studied.     

Effects of Anisotropy on Entanglement in a Two-Qubit Heisenberg XYZ Chain with Intrinsic Decoherence

Taking the intrinsic decoherence effect into account, the entanglement ofa two-qubit anisotropic Heisenberg XYZ chain in the presence of the Dzyaloshinski Moriya （DM） anisotropic antisymetric interaction is investigated in this paper. Concurrence, the measurement of entanglement, is calculated. Compared with the anisotropic in XY plane, the DM interaction is another kind of anisotropic antisymmetrie exchange interaction. It is shown that the intrinsic decoherence obviously suppresses the time evolution of the entanglement. The DM interaction only acts on the time evolution of the entanglement when the initial state is [ψ（0）〉 = cosα｜01〉 ＋ sinα｜10〉 and weakens the degree of entanglement. The anisotropic in XY plane merely impacts on the time evolution of the entanglement when the system ＆ initially in a state ｜ψ（0）〉 = cos α｜00〉 ＋ sin α｜11 〉. The sufficiently weak anisotropic in XY plane can effectively enhance the degree of entanglement.     

Quantitative evaluation of ultrasonic C-scan image in acoustically homogeneous and layered anisotropic materials using three dimensional ray tracing method

Quantitative evaluation of ultrasonic C-scan images in homogeneous and layered anisotropic austenitic materials is of general importance for understanding the influence of anisotropy on wave fields during ultrasonic non-destructive testing and evaluation of these materials. In this contribution, a three dimensional ray tracing method is presented for evaluating ultrasonic C-scan images quantitatively in general homogeneous and layered anisotropic austenitic materials. The directivity of the ultrasonic ray source in general homogeneous columnar grained anisotropic austenitic steel material (including layback orientation) is obtained in three dimensions based on Lamb’s reciprocity theorem. As a prerequisite for ray tracing model, the problem of ultrasonic ray energy reflection and transmission coefficients at an interface between (a) isotropic base material and anisotropic austenitic weld material (including layback orientation), (b) two adjacent anisotropic weld metals and (c) anisotropic weld metal and isotropic base material is solved in three dimensions. The influence of columnar grain orientation and layback orientation on ultrasonic C-scan image is quantitatively analyzed in the context of ultrasonic testing of homogeneous and layered austenitic steel materials. The presented quantitative results provide valuable information during ultrasonic characterization of homogeneous and layered anisotropic austenitic steel materials.     

A new method for determining birefringence dispersion

A method is proposed for the determination of birefringence in thin transparent anisotropic films. The modifications produced by the thin anisotropic films in the channeled spectra of an anisotropic crystal are used. The channeled spectra were recorded on a spectrophotometer provided with a device developed by us.     

记录结构对体光栅各向异性衍射选择特性研究

以静态体光栅各向异性衍射理论分析模型为基础,将与体光栅厚度有关的记录光强调制度引入到各向异性耦合波方程中.利用耦合波理论分析了光折变晶体中体光栅的各向异性衍射性能,研究了在不同初始记录光强比的条件下,记录光入射角的改变对光折变体光栅各向异性布喇格衍射性能的影响.结果表明：记录光入射角和记录光初始光强比均对体光栅的各向异性衍射具有选择性;与此相比,记录光入射角和记录光初始光强比对于体光栅各向同性衍射不具备选择性.     

Hard loop effective theory of the (anisotropic) quark gluon plasma

The generalization of the hard thermal loop effective theory to anisotropic plasmas is described with a detailed discussion of anisotropic dispersion laws and plasma instabilities. The numerical results obtained in real-time lattice simulations of the hard loop effective theory are reviewed, both for the stationary anisotropic case and for a quark-gluon plasma undergoing boost-invariant expansion.     

Reflection of electromagnetic plane waves in a long-wavelength approximation from a multilayer system of anisotropic transparent films on absorbing medium

The propagation of s- and p-polarised electromagnetic plane waves in a N-layer system of anisotropic films on isotropic and homogeneous absorbing substrate is investigated in the long-wavelength limit. The analytical expressions are obtained for the reflection (transmission) coefficients and ellipsometric angles of an anisotropic multilayer system. All analytical results are correlated with the numerical solution of the reflection problem on the basis of rigorous electromagnetic theory for anisotropic layered systems. The possibilities of using obtained approximate formulae for resolving the inverse problem for ultrathin anisotropic dielectric films upon absorbing substrates are discussed.     

Reflection of electromagnetic plane waves in a long-wavelength approximation from a multilayer system of anisotropic transparent films on non-absorbing isotropic medium

The reflection of s- and p-polarised electromagnetic plane waves from an N-layer system of anisotropic dielectric films upon transparent homogeneous substrate is investigated in the long-wavelength approximation. The analytical expressions are obtained for the amplitude reflection (transmission) coefficients, reflectances (transmittances), and ellipsometric angles of an anisotropic multilayer thin-film system. All analytical results are in agreement with the numerical solution of the reflection problem for anisotropic stratified medium. The possibilities of using obtained expressions for resolving the inverse problem for ultrathin anisotropic films upon isotropic substrates are discussed.     

湍流黏性修正在不同孔型气膜计算中的应用

燃气轮机气膜冷却流动中的复杂涡系使得其湍流黏性系数体现出很强的各向异性。本文采用作者提出的代数各向异性湍流黏性系数修正方法(AAEV方法),对不同孔型气膜冷却进行了研究。文中结合平板圆孔、扇形孔气膜冷却实验结果,将传统的湍流模型与修正后的湍流模型获得的模拟结果与实验值进行了比较,得到修正后的结果与实验有较好的吻合度。修正后的湍流模型对不同的孔型有很好的适用性,同时揭示了两种孔不同的三维特性。     

各向异性超常材料的偏振分离特性

提出了一种利用含有负介电常量和磁导率张量的各向异性超常材料实现偏振分离的方法。通过分析电磁波在无损耗各向异性超常材料中的传输性质以及透射率与入射角度的关系,分类比较了由不同符号的介电常量和磁导率张量组合而成具有不同波矢面的各向异性超常材料的偏振分离特性,比较结果表明波矢面为单叶双曲面和椭球双叶双曲面的各向异性超常材料的偏振分离特性强。前者可以实现入射波中的s分量和p分量中某一分量正折射,另一分量负折射,且在一定条件下可以同时全透射,从而实现大角度偏振分离。后者在一定条件下可实现入射波中的s分量和p分量某一分量全反射,另一分量全透射,从而实现偏振分离。最后,对从各向同性介质入射到这两种各向异性超常材料中的高斯光波的传输进行了模拟计算,结果表明这两种各向异性超常材料可以实现很好的偏振分离功能,有潜力成为新型的偏振分离元件。     

Analysis of applying isotropic and anisotropic destruction criteria in simulating the destruction of anisotropic materials

A comparison of the results of the numerical simulation of anisotropic material destruction (using the example of the D16T aluminum alloy) at dynamic loading obtained using isotropic and anisotropic destruction criteria is presented. The Mises-Hill destruction criterion allowing for the anisotropy of a material’s ultimate strength is used as an anisotropic criterion of destruction. For the sake of comparison, the destruction of an anisotropic material at 6.5% accumulated plastic deformation is simulated as well.     

Acoustic source localization in anisotropic plates

The conventional triangulation technique cannot locate the acoustic source in an anisotropic plate because this technique requires the wave speed to be independent of the propagation direction which is not the case for an anisotropic plate. All methods proposed so far for source localization in anisotropic plates require either the knowledge of the direction dependent velocity profile or a dense array of sensors. In this paper for the first time a technique is proposed to locate the acoustic source in large anisotropic plates with the help of only six sensors without knowing the direction dependent velocity profile in the plate. Experimental results show that the proposed technique works for both isotropic and anisotropic structures. For isotropic plates the required number of sensors can be reduced from 6 to 4.