Evaluation of force implementation in pseudopotential-based multiphase lattice Boltzmann models

The Lattice Boltzmann method (LBM) has proven to be a promising approach in handling multiphase flow problems. In the most widely applied pseudopotential-based LBM multiphase models, multiphase effects can be added in the form of forces, which is further divided into two aspects of force incorporation scheme and force expression. However, the effect of both aspects on coexistence densities and spurious current has not been evaluated systematically. In this paper, Modified Yuan-type and Zhang-type force expressions are chosen, and then they are incorporated into the lattice Boltzmann equation by the Shan–Chen and exact difference method force incorporation scheme to recover the Carnahan–Starling equation of state (EOS) with an additional surface tension term. Based on the computational results of two phases coexisting at a steady state, it can be observed that the force incorporation scheme affects the coexistence densities implicitly with different relaxation times and does not lead to a large difference in values. Force expression is found to greatly affect the achievable highest density ratio, of which the discrete gradient operator of the pseudopotential plays a crucial role. Spurious current is observed to be related to both the force expression and force incorporation scheme, and in our simulation a different force incorporation scheme brings about a large difference. Moreover, our modification on Yuan-type force expression not only improves the accuracy in capturing coexistence densities at low temperatures, but also provides the possibility of tuning the density ratio and surface tension independently at high density ratios.     

Spin-polarized current generated by magneto-electrical gating

We theoretically study spin-polarized current through a single electron tunneling transistor (SETT), in which a quantum dot (QD) is coupled to non-magnetic source and drain electrodes via tunnel junctions, and gated by a ferromagnetic (FM) electrode. The I–V characteristics of the device are investigated for both spin and charge currents, based on the non-equilibrium Green's function formalism. The FM electrode generates a magnetic field, which causes a Zeeman spin-splitting of the energy levels in the QD. By tuning the size of the Zeeman splitting and the source–drain bias, a fully spin-polarized current is generated. Additionally, by modulating the electrical gate bias, one can effect a complete switch of the polarization of the tunneling current from spin-up to spin-down current, or vice versa.     

Heat Modulation on Target Thermal Bath via Coherent Auxiliary Bath

We study a scheme of thermal management where a three-qubit system assisted with a coherent auxiliary bath (CAB) is employed to implement heat management on a target thermal bath (TTB). We consider the CAB/TTB being ensemble of coherent/thermal two-level atoms (TLAs), and within the framework of collision model investigate the characteristics of steady heat current (also called target heat current (THC)) between the system and the TTB. It demonstrates that with the help of the quantum coherence of ancillae the magnitude and direction of heat current can be controlled only by adjusting the coupling strength of system-CAB. Meanwhile, we also show that the influences of quantum coherence of ancillae on the heat current strongly depend on the coupling strength of system—CAB, and the THC becomes positively/negatively correlated with the coherence magnitude of ancillae when the coupling strength below/over some critical value. Besides, the system with the CAB could serve as a multifunctional device integrating the thermal functions of heat amplifier, suppressor, switcher and refrigerator, while with thermal auxiliary bath it can only work as a thermal suppressor. Our work provides a new perspective for the design of multifunctional thermal device utilizing the resource of quantum coherence from the CAB.     

Study of Top Quark FCNC

We study the one-loop contribution of the effective flavor changing neutral couplings (FCNC) tcZ on the charm quark electric dipole moment. Using the known limits on the top and charm quarks electric dipole moments, we place limits on these FCNC anomalous couplings.     

Knotted Topological Phase Singularities of Electromagnetic Field

In this paper, knotted objects (RS vortices) in the theory of topological phase singularity in electromagnetic field have been investigated in details. By using the Duan's topological current theory, we rewrite the topological current form of RS vortices and use this topological current we reveal that the Hopf invariant of RS vortices is just the sum of the linking and self-linking numbers of the knotted RS vortices. Furthermore, the conservation of the Hopf invariant in the splitting, the mergence and the intersection processes of knotted RS vortices is also discussed.     

电极构型及其耦合模式对有机分子电输运性质的影响

选取两种不同的电极构型及其耦合模式,利用从头算理论和弹性散射格林函数的方法,对有机分子对苯二甲氰的电输运性质进行理论研究和对比分析.计算结果表明,不同构型及其耦合在分子的耦合属性、电子输运谱、开启电压位置、电导平台的分布以及电流的响应等方面存在明显不同,改变电极间距也会对各种构型分子体系的耦合系数、电导平台高度和电流的大小产生影响.     

模拟心电原理与变化电场的紧密联系

论述了心电向量环与模拟心电的紧密联系,突出了实验装置盘中心电向量环的医学意义及模拟心电的物理含义,论述了模拟心电原理与变化电场的紧密联系,阐述了实验盘综合变化电场形成的过程,详述了模拟心电图形成的物理机制。     

Corrosion Behavior of Aluminum in Non‐Uniform Electric Fields

The present paper discusses the effect of the geometrical structure of the electric fieldon the corrosion of aluminum cathodes by electrolysis of aqueous solutions of sodium chloride. A correlation between the mass of the aluminum dissolved from the cathode and the factors electric current density, distance between the electrodes, electrolysis time and sodium chloride concentration by electrolysis with direct current in electric fields of various geometries was found.     

Microwave Diagnostics in Diffusive and Constricted Medium-Pressure Discharges

The high-frequency (HF) electron current induced in a dc discharge plasma bysuperimposing a HF electric field presents a useful tool for the diagnosticsof the time-dependent electron behavior of the plasma. This response to theHF field has been recently studied in diffusive discharge plasmas at lowergas pressures and discharge currents. These studies are extended tomedium-pressure plasmas operating in the diffusive as well as in theconstricted mode. In particular, the impact of the electron–electroninteraction on the phase delay between the HF field and electron current inconstricted column plasmas has been experimentally and theoreticallyanalyzed. Furthermore, the problem has been studied if, under the conditionsof pronounced electron–electron interaction, the determination of theelectron density will further on be possible by using the phase delay. Themeasurements of the delay have been performed by means of the microwaveresonator method in a medium-pressure krypton glow discharge operating inthe diffusive as well as the strongly constricted mode. In addition, thedelay has been theoretically determined by treating the appropriatetime-dependent electron kinetic equation at high frequencies of thesuperimposed microwave field.