Electromagnetic interactions in a cluster of cylinders

We present a rigorous multiple-scattering method to calculate the interaction energies due to electromagnetic field fluctuations in a cluster of parallel cylinders. Various kinds of cluster structure with both isotropic and anisotropic materials are considered. It is shown that Casimir interactions are sensitive to the positions of the cylinders in the cluster or the structure of the system. The sign of the interaction energy cannot only be changed by tuning the parameters of anisotropic materials, it can also be caused by changing the cylinders configuration of the system.     

Physically Realizable Broadband Acoustic Metamaterials with Anisotropic Density

Transformation acoustics are concentrated for the purpose of designing novel acoustic devices to tailor acoustic waves to achieve desirable characteristics. However, these devices require fluid or fluid-like materials with an anisotropic density that generally does not exist in nature. Therefore, we introduce pentamode metamaterials into an alternating multilayer isotropic medium model to build fluid-like metamaterials with an anisotropic density. A 2D acoustic bending based on transformation acoustics is established and investigated to verify our method. This idea provides a method to design broadband and physically realizable acoustic metamaterials with an anisotropic density and is meaningful for the design of acoustic metamaterials.     

Conformal anisotropic relativistic charged fluid spheres with a linear equation of state

We obtain two new families of compact solutions for a spherically symmetric distribution of matter consisting of an electrically charged anisotropic fluid sphere joined to the Reissner–Nordstrom static solution through a zero pressure surface. The static inner region also admits a one parameter group of conformal motions. First, to study the effect of the anisotropy in the sense of the pressures of the charged fluid, besides assuming a linear equation of state to hold for the fluid, we consider the tangential pressure p _⊥ to be proportional to the radial pressure p _r , the proportionality factor C measuring the grade of anisotropy. We analyze the resulting charge distribution and the features of the obtained family of solutions. These families of solutions reproduce for the value C=1, the conformal isotropic solution for quark stars, previously obtained by Mak and Harko. The second family of solutions is obtained assuming the electrical charge inside the sphere to be a known function of the radial coordinate. The allowed values of the parameters pertained to these solutions are constrained by the physical conditions imposed. We study the effect of anisotropy in the allowed compactness ratios and in the values of the charge. The Glazer’s pulsation equation for isotropic charged spheres is extended to the case of anisotropic and charged fluid spheres in order to study the behavior of the solutions under linear adiabatic radial oscillations. These solutions could model some stage of the evolution of strange quark matter fluid stars.     

受限导致硬椭球液体的取向有序

Monte Carlo模拟研究了两平行硬墙受限下各向异相的硬椭球液体形成的有序结构. 墙壁对椭球粒子的过量吸附和椭球的长短径之比有关;对于高密度的椭球液体,它在一个临界的长短径之比 a/b=2.9处达到最大值,表明在墙表面附近发生了取向有序. 墙表面附近的密度分布和取向序参量进一步证实这结论. 相同密度条件下体相中的取向序参量计算表明体相结构均为各向同性,这是由于体系的密度依然低于各向同性相向相列向转变的临界密度. 该受限椭球液体中墙表面的取向有序是由墙面的几何受限所导致的.     

Design of an acoustic bending waveguide with acoustic metamaterials via transformation acoustics

Transformation acoustics is employed to design an acoustic bending waveguide. A two-dimensional square area with anisotropic and homogeneous material properties is transformed into a fan-shaped area with anisotropic and inhomogeneous material properties to rotate the direction of beam propagation. An alternating layered structure is considered to approximate a medium with anisotropic material properties. From the calculation results, the transformation medium can be realized by an alternating layered structure consisting of water and fluid with negative mass density. We propose that an acoustic metamaterial composed of three layers in water background can be designed to replace negative mass density fluid. The effective mass density and bulk modulus of the system that is composed of the acoustic metamaterial and water are dependent on the incident frequency and the geometric size of the acoustic metamaterial. We tune the geometric size of the acoustic metamaterial to approach the corresponding mass density distribution of the negative mass density fluid at a specific frequency. Thereby, the acoustic bending waveguide designed by using transformation acoustics can be achieved by the acoustic metamaterials.     

Effects of charge on gravitational decoupled anisotropic solutions in f(R) gravity

This paper is devoted to studying charged anisotropic static spherically symmetric solutions through gravitationally decoupled minimal geometric deformation technique in f(R) gravity. For this purpose, we first consider the known isotropic Krori–Barua solution for f(R) Starobinsky model in the interior of a charged stellar system and then include the effects of two types of anisotropic solutions. The corresponding field equations are constructed and the unknown constants are obtained from junction conditions. We analyze the physical viability and stability of the resulting solutions through effective energy density, effective radial/tangential pressure, energy conditions, and causality condition. It is found that both solutions satisfy the stability range as well as other physical conditions for specific values of charge as well as model parameter and anisotropic constant. We conclude that the modified theory under the influence of charge yields more stable behavior of the self-gravitating system.     

各向异性超导体的Ginzburg-Landau理论

本文内容主要有二个方面：1）由各各同性均匀系的BCS理论扩展到各向异性非均匀系，并给出各种异性非均匀系的完整的GL方程式，定出了各个宏微观参量间的关系式。2）结合层状结构氧化物超导体的导电层在导电层相间的特征等，用有效调制势模型和电子有效质量近似，交各向同性均匀系的BCS理论较具体的扩展到各向异性非均匀系并进行深化研究，扩展理论所给出的临界温度和能隙方程公式，主要的热力学性质和电磁性质公式等应用到YBaCuO超导体上，理论结果与实验结果均相符，并也给出各向异性非均匀系的完整的GL方程式，与上面1所给出的形式相同，也定出了各个宏微观参量间的关系，应用到YBaCuO超导体的一些主要性质上也与实验结果相符。     

On the motion of a particle with anisotropic mass

On the basis of the hypothesis that particle mass is anisotropic rather than isotropic, we investigate the relativistic motion of a particle within the framework of flat space-time. Assuming that the mass anisotropy is associated with the photon cloud of the particle, we argue that the self-energy of a particle is of the order of magnitude |δ m/M ₀|?0.0005, for which conventional quantum electrodynamics, however, gives an infinite value.     

各向异性超导体的Ginzburg-Landau理论

本文内容主要有二个方面 :1 )由各向同性均匀系的BCS理论扩展到各向异性非均匀系 ,并给出各向异性非均匀系的完整的GL方程式 ,定出了各个宏微观参量间的关系式。2 )结合层状结构氧化物超导体的导电层与非导电层相间的特征等 ,用有效调制势模型和电子有效质量近似 ,将各向同性均匀系的BCS理论较具体地扩展到各向异性非均匀系并进行深化研究。扩展理论所给出的临界温度和能隙方程公式 ,主要的热力学性质和电磁性质公式等应用到YBaCuO超导体上 ,理论结果与实验结果均相符 ,并也给出各向异性非均匀系的完整的GL方程式 ,与上面 1所给出的形式相同 ,也定出了各个宏微观参量间的关系 ,应用到YBaCuO超导体的一些主要性质上也与实验结果相符。     

Stability of Quark Star Models

In this paper,we investigate the stability of quark stars with four different types of inner matter configurations;isotropic,charged isotropic,anisotropic and charged anisotropic by using the concept of cracking.For this purpose,we have applied local density perturbations technique to the hydrostatic equilibrium equation as well as on physical parameters involved in the model.We conclude that quark stars become potentially unstable when inner matter configuration is changed and electromagnetic field is applied.     

Theoretical investigation of Stoneley-wave attenuation and dispersion in a fluid filled fracture in transversely isotropic formation

The wave motion in a fluid-filled fracture embedded in an anisotropic medium is investigated using the technique of partial waves. A model is derived to calculate the complex dispersion relation of the Stoneley-wave mode in a fluid layer between two infinite transversely isotropic half-spaces. The effect of the anisotropic parameters on the Stoneley-wave in the fracture is investigated. The numerical results indicate that the velocity of the Stoneley-wave mode has significant dependence on the transversely isotropic constants. For a weakly anisotropic medium, the Stoneley-wave dispersion is almost the same as in an isotropic medium.     

Dynamics of charged anisotropic spherical collapse in energy-momentum squared gravity

This paper investigates the dynamics of charged spherical collapse with anisotropic matter configuration in the context of energy-momentum squared gravity. This newly developed proposal resolves the big-bang singularity and yields the physically viable cosmological results in the early time universe. We establish dynamical equations through Misner-Sharp technique and analyze the effects of charge, anisotropy, effective matter variables and dark source terms on the collapse rate. A relation between Weyl scalar, fluid parameters and dark source terms is also established. The spacetime is not conformally flat due to the presence of anisotropic pressure, multivariate functions and their derivatives. In order to obtain conformally flat spacetime, we consider a specific model of this gravity, neglect the impact of charge and assume the isotropic matter distribution which yields homogeneity of the energy density and conformally flat spacetime. We conclude that positive dark source terms, anisotropy and charge yield the action of a repulsive force which enhances the stability of the system and hence diminishes the collapse rate.     

Singularity-free dark energy star

We propose a model for an anisotropic dark energy star where we assume that the radial pressure exerted on the system due to the presence of dark energy is proportional to the isotropic perfect fluid matter density. We discuss various physical features of our model and show that the model satisfies all the regularity conditions and is stable as well as singularity-free.     

Elliptic incoherent spatial solitons and their interactions in strongly nonlocal media with an anisotropic nonlocality

We investigate the propagation and interaction of elliptic incoherent spatial solitons (EISS) in strongly nonlocal kerr media with an anisotropic nonlocality based on the coherent density approach. An exact analytical solution of such EISS is obtained; the results show that such EISS can form with both isotropic and anisotropic coherence. Moreover, we find that the interaction properties of EISS are very similar to that of their coherent counterpart. Some numerical examples are presented and pertinent physics features are addressed.     

The Temperature Dependence of Nitroxide Spin–Label Interaction Parameters: a High-Field EPR Study of Intramolecular Motional Contributions

High-field W-band electron paramagnetic resonance (EPR) spectroscopy was utilized to study the temperature dependence of the magnetic interaction parameters (g-, hyperfine-, quadrupole tensors) of two types of doublet-state nitroxide spin probes in glass-forming ortho-terphenyl solution: a five-membered ring system of pyrroline type (model for the commonly used methane thiosulfonate spin label) and a six-membered ring system of piperidine type (model for the commonly used TOAC spin label). The analysis of the g- and hyperfine tensors in terms of their isotropic and anisotropic parts reveals at least two mechanisms of motion that are responsible for the temperature dependence of the interaction parameters. The first mechanism is attributed to the overall small-angle motion of the nitroxide molecule in the glassy matrix; it leads to an averaging of the anisotropies of the EPR parameters. The second mechanism originates in an intramolecular out-of-plane motion of oxygen in the nitroxide group. This type of motion is evidenced by comparing the experimental findings for the spin-interaction parameters with the results of density functional theory calculations. The harmonic oxygen out-of-plane vibrations result in a variation of both the isotropic and anisotropic parts of the g- and hyperfine tensors. In contrast, the quadrupole tensor is not influenced by this vibration mechanism in the temperature range under study (90–240 K). Consequences of the applicability of such typical nitroxide radicals for probing details of their protein environment and for studying librational dynamics in frozen solutions are discussed.     

Phosphorescence from the two triplet states of p-benzoquinone and toluquinone vapour

Molecular formulae for the isotropic and anisotropic scattering are derived by considering the internal field acting upon a molecule within a dense medium and its fluctuation caused by density fluctuations. The anisotropic scattering formula of classical theory is retained but modified by the factors of the internal field. The new formula for the isotropic scattering depends sensitively on the principal values of the optical polarizability tensor and on the parameters describing the anisotropic internal field. Assuming the internal field to be given by the semimacroscopic approach of the Onsager-Scholte model with an ellipsoidal cavity, comparison of the calculated isotropic Rayleigh factor with the experimental value allows a prediction of the degree of the cavity anisotropy for different liquid densities.     

Radiating gravitational collapse with shear viscosity revisited

A new model is proposed to a collapsing radiating star consisting of an isotropic fluid with shear viscosity undergoing radial heat flow with outgoing radiation. In a previous paper we have introduced a function time dependent into the g _rr , besides the time dependent metric functions and . The aim of this work is to generalize this previous model by introducing shear viscosity and compare it to the non-viscous collapse. The behavior of the density, pressure, mass, luminosity and the effective adiabatic index is analyzed. Our work is compared to the case of a collapsing shearing fluid of a previous model, for a star with 6 . The pressure of the star, at the beginning of the collapse, is isotropic but due to the presence of the shear the pressure becomes more and more anisotropic. The black hole is never formed because the apparent horizon formation condition is never satisfied. An observer at infinity sees a radial point source radiating exponentially until reaches the time of maximum luminosity and suddenly the star turns off. The effective adiabatic index has a very unusual behavior because we have a non-adiabatic regime in the fluid due to the heat flow.     

Radiating gravitational collapse with an initial inhomogeneous energy density distribution

A new model is proposed to a collapsing star consisting of an initial inhomogeneous energy density and anisotropic pressure fluid with shear, radial heat flow and outgoing radiation. In previous papers one of us has always assumed an initial star with homogeneous energy density. The aim of this work is to generalize the previous models by introducing an initial inhomogeneous energy density and compare it to the initial homogeneous energy density collapse model. We will show the differences between these models in the evolution of all physical quantities that characterizes the gravitational collapse. The behavior of the energy density, pressure, mass, luminosity and the effective adiabatic index is analyzed. The pressure of the star, at the beginning of the collapse, is isotropic but due to the presence of the shear the pressure becomes more and more anisotropic. The black hole is never formed because the apparent horizon formation condition is never satisfied, in contrast of the previous model where a black hole is formed. An observer at infinity sees a radial point source radiating exponentially until reaches the time of maximum luminosity and suddenly the star turns off. In contrast of the former model where the luminosity also increases exponentially, reaching a maximum and after it decreases until the formation of the black hole. The effective adiabatic index is always positive without any discontinuity in contrast of the former model where there is a discontinuity around the time of maximum luminosity. The collapse is about three thousand times slower than in the case where the energy density is initially homogeneous.