激光雷达大气湍流测量方法研究

 报道了一种用激光雷达方法测量大气湍流的技术，利用发射激光束在空间所需位置产生一个聚焦光斑，通过此光斑处的大气分子瑞利散射机制形成一个空间的人造散射光源，接收系统对此光源的散射光进行探测，测量出从地面到此空间散射光源之间的大气湍流参数。给出了对武汉上空大气湍流测量的初步结果。得到了不同高度层的大气相干长度随时间的变化特性、平均值和起伏均方差，并对实验测量和模型计算的大气折射率结构常数在相应高度段的积分值进行了比较，二者积分值都在10-12量级，得到的结果基本相符。这种测量方法的实现，为测量空间不同方位、不同距离的大气湍流提供了一种新的手段。     

Swarm Dynamics of a Group of Mobile Autonomous Agents

We propose a simple swarm model to study collective behaviour of a group of mobile autonomous agents interacting through a long range attraction and short range repulsion function. It is shown that the individuals (agents) will aggregate and eventually form a cohesive cluster of finite size around the swarm centre in a finite time, and the size depends only on the parameters of the swarm model. Furthermore, it is also shown that all the individuals will converge to equilibrium positions of the swarm model, and thus the configuration of the swarm converges to a constant constellation. Numerical simulations are also worked out to illustrate the analytical results.     

弹性力学的复变量无网格方法

在移动最小二乘法的基础上，提出了复变量移动最小二乘法.复变量移动最小二乘法的优点是采用一维基函数建立二维问题的逼近函数，所形成的无网格方法计算量小.然后，将复变量移动最小二乘法应用于弹性力学的无网格方法，提出了复变量无网格方法，推导了复变量无网格方法的公式.与传统的无网格方法相比，复变量无网格方法具有计算量小、精度高的优点.最后给出了数值算例. 关键词： 移动最小二乘法 复变量移动最小二乘法 无网格方法 弹性力学 复变量无网格方法     

A time domain correction method for Doppler-distortion signal from acoustic moving source

Doppler effect widely exists in the signal from the moving acoustic source. In order to solve such problems as frequency shift and frequency band expansion, a time domain cor- rection method is presented in this paper. First, the discrete time vector for interpolation and the amplitude restoration formula is derived based on the moving relationship and the Morse acoustic theory, then the amplitude weights are corrected and the distortion signal is interpolated. Every point of the discrete signal is operated separately in time domain. Compared with the existing frequency domain methods, this method does not need to know the characteristic frequency beforehand and would not be influenced by the blending of the frequency band. Hence, this method can be employed to correct multiple frequency signals and it is also a simple and effective Doppler effect reduction method.     

AA bilayer graphene on Si-terminated SiO2 under electric field

The AA-stacked bilayer graphene/α-SiO2 （001） interfaces with Si terminated atoms are studied in the presence of an electric field F with different intensities by first principles. AA-stacked bilayer graphene is slightly mis-oriented on SiO2 substrate without electric field and the band gap is 0.557 eV. However, as F increases, the AA-stacked bilayer graphene has its layers gradually vertically shifted with each other and, finally, transfers into AB-stacked bilayer graphene and the band gap reduces to 0.252 eV under 0.015 Hartree.     

移动微课《 物理文化与教育》建设的实践探索

面向科技发展的新文化背景, 打造通识课程《 物理文化与教育》 , 通过数年的探索, 取得了初步的成功. 首先介绍《 物理文化与教育》通识课程的意义; 其次介绍课程内容与理念; 第三介绍《 物理文化与教育》移动微课及 其反响     

手征和运动介质界面异常光自旋霍尔效应

文章讨论了偏振高斯光束在空气-手征介质界面的反射和折射问题,发现了反射和折射光束的异常自旋霍尔效应.在某些特定的角度下,反射高斯光束重心的移动可以达到几十个波长的量级,通过调节手征参数,甚至会出现折射光重心移动方向由正到负的转变.文章还讨论了任意偏振高斯光束在空气-运动介质界面的反射和透射问题,当介质垂直于入射平面运动时,反射和透射光束的横向移动可以达到几个波长的量级,甚至在某些运动速度下可以实现移动方向正负的改变.这些研究对控制光的自旋霍尔效应提供了可能的途径.     

Decrease in Hurst exponent of human gait with aging and neurodegenerative diseases

In this paper the decrease in the Hurst exponent of human gait with aging and neurodegenerative diseases was observed by using an improved rescaled range （R/S） analysis method. It indicates that the long-range correlations of gait rhythm from young healthy people are stronger than those from the healthy elderly and the diseased. The result further implies that fractal dynamics in human gait will be altered due to weakening or impairment of neural control on locomotion resulting from aging and neurodegenerative diseases. Due to analysing short-term data sequences rather than long datasets required by most nonlinear methods, the algorithm has the characteristics of simplicity and sensitivity, most importantly, fast calculation as well as powerful anti-noise capacities. These findings have implications for modelling locomotor control and also for quantifying gait dynamics in varying physiologic and pathologic states.     

点对点移动水声通信技术研究

点对点移动水声通信是实现由活动和静止节点共同构成的水声数据通信网的关键技术之一. 对移动水声通信声信道特性进行了分析,指出不同途径到达的声线对应的多普勒频偏不一致,进一步加大了多途扩展产生的码间干扰的复杂性,不利于水声通信. 提出单阵元被动式相位共轭镜信道均衡技术,可实时自动补偿多普勒频偏,并聚焦多途信号. 将单阵元被动式相位共轭应用于Pattern时延差编码移动水声通信系统,进行了移动水声通信试验,湖试结果验证了其消除码间干扰性能及本文水声通信系统的鲁棒性. 关键词： 移动水声通信 被动式相位共轭镜 时变信道 码间干扰