Two-dimensional steady-state general solution for isotropic thermoelastic materials with applications. II. Green’s function for two-phase infinite plane

Green’s function for isotropic thermoelastic two-phase infinite plane under a line heat source is established in this paper. By virtue of the fourth compact general solutions in Part I which is expressed in three harmonic functions, six new suitable harmonic functions with undetermined constants are constructed for the two semi-infinite planes of the two-phase infinite plane, respectively. The corresponding thermoelastic field can be obtained by substituting these harmonic functions into the general solution, and the undetermined constants can be determined by compatibility conditions and the equilibrium conditions. Numerical results are given graphically by contours.     

Broadband efficient light absorbing in the visible regime by a metananoring array

The broadband efficient light‐absorbing property of a metamaterial‐based subwavelength nanoring array in visible regime is reported. The nanoring array can absorb light efficiently with an average absorptivity of 0.97 over the whole visible waveband. In addition, it is found that this kind of super light‐absorbing capability is independent of the incoming light polarization state and can maintain an average of 0.9 for an incident angle as large as ±60° under TM illumination. The perfect absorbing property of the metamaterial‐based nanoring array is attributed to the synergetic effect of the Fabry–Perot resonance and the localized surface plasmon resonance enhancement.     

Non-invasive imaging of shallow bubble columns using electrical capacitance tomography

This paper deals with application of non-invasive electrical capacitance tomography to study the hydrodynamics of shallow bed bubble columns. Two bubble columns with different height to diameter ratio were used. Air–kerosene system that represents dielectric two-phase mixture was investigated. The ECT provided good measurement of the gas holdup at different gas velocities compared to the classical pressure measurements. The ECT was able to provide the gas hold up and the bubble velocities distribution across the column diameter at different gas velocities. The study revealed that spatial gas holdup and bubble velocity distributions are sharp with parabolic shape in the small bubble column (H_D/D_C = 5). However, in the large bubble column (H_D/D_C = 4) the gas holdup and bubble velocity profiles were flatter indicating improvement in the mixing homogeneity and leading to well-mixed reactor. 3D graphical visualization of the flow regimes and transition points were also examined using the ECT. In the small bubble column flow regimes were heterogeneous to slugs flow especially at high flow rate, resulted in downward flow near the walls and imperfect mixing.     

中国证券市场知情交易概率的动态马尔科夫状态转移模型研究

对指令驱动市场知情交易的研究是近年来的热点问题。常用的EKOP模型存在一些缺陷,本文放宽了EKOP模型关于日内信息均匀释放以及交易者行为独立性的假设,用动态的马尔科夫状态转移模型对该模型进行了改进,并检验了改进后的知情交易概率模型在中国证券市场的适用性。通过模拟数据以及对中国证券市场交易数据的实证研究发现动态的马尔科夫状态转移模型克服了EKOP模型受买卖方数据影响而产生的系统偏误,估计的知情交易概率更符合事后检验。     

Linear response of heat conductivity of normal-superfluid interface of a polarized Fermi gas to orbital magnetic field

Using perturbed Bogoliubov equations, we study the linear response to a weak orbital magnetic field of the heat conductivity of the normal-superfluid interface of a polarized Fermi gas at sufficiently low temperature. We consider the various scattering regions of the BCS regime and analytically obtain the transmission coefficients and the heat conductivity across the interface in an arbitrary weak orbital field. For a definite choice of the field, we consider various values of the scattering length in the BCS range and numerically obtain the allowed values of the average and species-imbalance chemical potentials. Thus, taking Andreev reflection into account, we describe how the heat conductivity is affected by the field and the species imbalance. In particular, we show that the additional heat conductivity due to the orbital field increases with the species imbalance, which is more noticeable at higher temperatures. Our results indicate how the heat conductivity may be controlled, which is relevant to sensitive magnetic field sensors/regulators at the interface.     

垂直圆管氮气-磁性液体两相流电磁感应现象

基于磁性液体与非磁性气泡磁导率的差异,理论分析与实验研究了氮气-磁性液体两相流的电磁感应现象。以颗粒体积浓度为3.83%的水基Fe₃O₄磁性液体为工质,同时采用物性与其相近的去离子水进行流型的可视化对比研究。研究结果表明,当管内为泡状流、弹状流、搅拌流时均能产生毫伏级的感应电压,且感应电压的峰峰值随着气体流量的增加而增大,另外根据感应电压随时间变化的波形可以辨识出管内的流型。     

Investigation of the effect of pressure on thermodynamic properties and thermoelastic phase transformation of CuAlNi alloys: A molecular dynamics study

Thermoelastic phase transformations and thermodynamic properties of CuAlNi alloys at 0, 1, 2 and 3 GPa pressures were investigated by using MD simulation in this study. The interactions between atoms were modelled by Sutton-Chen type of embedded atom method (SCEAM) that is based on many-body interaction. It was observed that thermoelastic phase transformation in the ternary alloy system occurred at the end of thermal process. Radial distribution function (RDF) was used in order to analysis the structures obtained from MD simulation using the simulation techniques’ thermodynamic parameters. The transformation temperatures, enthalpy and entropy of the ternary alloy system have been observed to be changing with the applied pressure. In addition, it was found that the elastic energy has been decreased about 22% by applied pressure whereas Gibbs free energy has been increased about 60% by applied pressure. The values of the thermodynamical parameters obtained in this study were observed to be in close agreement with the experimental study.     

Optimal stopping of Markov switching Lévy processes

We consider a finite time horizon optimal stopping of a regime-switching Lévy process. We prove that the value function of the optimal stopping problem can be characterized as the unique viscosity solution of the associated Hamilton–Jacobi–Bellman variational inequalities.     

A thermoelastic system of memory type in noncylindrical domains

In this paper, we consider a hyperbolic thermoelastic system of memory type in domains with moving boundary. The problem models vibrations of an elastic bar under thermal effects according to the heat conduction law of Gurtin and Pipkin. Global existence is proved by using the penalty method of Lions.     

Atomic beam splitter from a mixture of atoms in the Bragg regime

We investigate the interaction of a standing-wave light field with the beam of two-level atoms moving in the Bragg regime. The atomic beam consists of two different isotopes and the density is sufficiently small so that at most one atom is inside the cavity at any time. The experimental setup is such that both the isotopes have the same momenta. The momentum transfer between the atoms and photons in the process essentially effects the center-of-mass motion of the atoms, thus separating the isotopes in different directions after specific interaction times.