理论研究B2分子X3Σg-和A3Πu态的光谱性质

采用Davidson修正的内收缩多参考组态相互作用方法及Dunning等的相关一致基aug-cc-pV6Z计算了B₂分子X³∑_g^-和A³Π_u电子态的势能曲线.利用总能量外推公式,将两个电子态的总能量分别外推至完全基组极限.对势能曲线进行核价相关修正及相对论修正计算,得到了同时考虑两种效应修正的外推势能曲线.通过同位素质量识别,得到了主要的同位素分子¹¹B¹¹B和¹⁰B¹¹B的X³Σ_g^-和A³Ⅱ_u电子态的光谱常数T_e,R_e,ω_e,ω_ex_e,ω_ey_e,B_e,β_e和γ_e.求解双原子分子核运动的径向Schr（o|¨）dinger方程,找到了无转动的同位素分子¹¹B₂（X³Σ_g^-,A³Π_u）和¹⁰B¹¹B（X³∑_g^-,A³Π_u）的全部振动态.针对每一同位素分子的每一振动态,分别计算了其振动能级和惯性转动常数等分子常数,它们均与已有的实验结果较为一致.其中,¹⁰B¹¹B（A^Π_u）分子的光谱常数和分子常数属首次报道.     

Ultimate turbulent Taylor-Couette flow

The flow structure of strongly turbulent Taylor-Couette flow with Reynolds numbers up to Re(i)=2×10(6) of the inner cylinder is experimentally examined with high-speed particle image velocimetry (PIV). The wind Reynolds numbers Re(w) of the turbulent Taylor-vortex flow is found to scale as Re(w)∝Ta(1/2), exactly as predicted by Grossmann and Lohse [Phys. Fluids 23, 045108 (2011).] for the ultimate turbulence regime, in which the boundary layers are turbulent. The dimensionless angular velocity flux has an effective scaling of Nu(ω)∝Ta(0.38), also in correspondence with turbulence in the ultimate regime. The scaling of Nu(ω) is confirmed by local angular velocity flux measurements extracted from high-speed PIV measurements: though the flux shows huge fluctuations, its spatial and temporal average nicely agrees with the result from the global torque measurements.     

Multiple filamentation generated by focusing femtosecond laser with axicon

Multiple filamentation has been observed when focusing a femtosecond laser pulse into a methanol solution with an axicon. It is found that multiple long filaments are located on the central spot and ring structures of the quasi-Bessel beam created by the axicon. Since the quasi-Bessel profile is determined by the axicon properties, the axicon has been suggested as a simple optics to control multiple filaments.     

Electric-field control of nonvolatile magnetization in Co40Fe40B20/Pb(Mg(1/3)Nb(2/3))(0.7)Ti(0.3)O3 structure at room temperature

We report a large and nonvolatile bipolar-electric-field-controlled magnetization at room temperature in a Co(40)Fe(40)B(20)/Pb(Mg(1/3)Nb(2/3))(0.7)Ti(0.3)O(3) structure, which exhibits an electric-field-controlled looplike magnetization. Investigations on the ferroelectric domains and crystal structures with in situ electric fields reveal that the effect is related to the combined action of 109° ferroelastic domain switching and the absence of magnetocrystalline anisotropy in Co(40)Fe(40)B(20). This work provides a route to realize large and nonvolatile magnetoelectric coupling at room temperature and is significant for applications.     

Effects of noise on the outer synchronization of two unidirectionally coupled complex dynamical networks

We study the effect of noise on the outer synchronization between two unidirectionally coupled complex networks and find analytically that outer synchronization could be achieved via white-noise-based coupling. It is also demonstrated that, if two networks have both conventional linear coupling and white-noise-based coupling, the critical deterministic coupling strength between two complex networks for synchronization transition decreases with an increase in the intensity of noise. We provide numerical results to illustrate the feasibility and effectiveness of the theoretical results.     

Highly-efficient optical power combiners based on evanescently-coupled micro/nano optical fibers

Novel highly-efficient power combiners based on evanescently-coupled micro/nano optical fibers are proposed and experimentally demonstrated. Experimental results show that the maximum power combing efficiency can be >90%. The combining efficiency is overlap length dependent. As long as the overlap length is long enough (～7 mm), a stable high combining efficiency can always be achieved. The presented optical power combiners with the advantages of easy fabrication, low-loss, low-cost, and wavelength insensitivity can find potential applications in micro/nano photonic devices, optical communications and optical interconnects.     

Analysis of complex axis control loop in satellite laser communications

Satellite laser communication involves communications between GEO satellites and LEO satellites. The optical link can be built by the accurate pointing and tracking, which often employs the combination effect of coarse pointing assembly and fine pointing assembly. In order to achieve this goal with double rotated wedged-plate lenses and fast steering mirror that perform the scanning function of the coarse pointing assembly and the fine pointing assembly, mathematic model of transfer function of control loop is obtained by analyzing the total control loop for such complex axis. One can also get the optimized programs between coarse and fine pointing assembly.     

New method of circle and arc cutting

In practical applications of laser cutting, the quality of the cut surfaces is the critical factor. In this study, a new method for circle and arc cutting is proposed based on optical characteristic of a glass cone. In a laser cutting system, we use a glass cone replace beam-focusing optics to direct the beam to the workpiece, and equipment for moving either the laser beam or the workpiece, or both, to obtain the circle or arc cutting pattern. Theoretical analysis and simulation studies of a glass cone show that, this method solves an issue which the focal depth and focal spot cannot be optimized in the meantime, ensures the strict vertical cut surface and the high cutting quality, greatly reduce the workload caused by the motion of the beam or the workpiece.     

Control analysis of acquirement and locking in inter-satellite laser communications

Process of acquirement and locking-up of compound axis system in inter-satellite laser communication has been studied. The effect of different condition parameters on the process of acquirement and locking-up have also been researched and simulated. Simulation results show that when the system with appropriate bandwidth has been adopted, both fine pointing system and coarse pointing system can satisfy three requirements of step response, stability criterion and dwell time and then finish the acquirement and locking-up of beacon laser beam. The simulation results provide the suited condition parameters for both fine pointing system and coarse pointing system, which is very helpful to the subsequent point and tracking processes.     

基于激光定位的变电站智能巡检机器人导航系统设计

导航和定位是变电站智能巡检机器人完全自主运行的关键,针对巡检机器人现有导航定位方式的不足,将激光定位技术应用于巡检机器人导航,设计了巡检机器人激光导航系统,详细介绍了系统的软硬件结构及实现方法,并在室外环境下对导航系统进行了实验测试;实验结果表明,巡检机器人运行平稳,具有较高的导航控制精度;实验中机器人的运行轨迹重合度较好,直线运行时运动轨迹与路径横向垂直偏差在±15mm以内,航向偏差可控制在±1.5°左右。