Interdaily Variations of Three Wind Velocity Components Retrieved from Long-Term Continuous Minisodar Measurements in the ABL

Russian Physics Journal - Statistical analysis of results of long-term continuous 8-day measurements of three components of wind velocity vector with a minisodar in the atmospheric boundary layer...     

Diurnal Dynamics of Standard Deviations of Three Wind Velocity Components in the Atmospheric Boundary Layer

Russian Physics Journal - Diurnal dynamics of the standard deviation (SD) of three wind velocity components measured with a minisodar in the atmospheric boundary layer is analyzed. Statistical...     

Multistable Spatiotemporal Dynamics in the Driven Frenkel-Kontorova Lattice

Spatiotemporal dynamics of the damped dc-driven Frenkel-Kontorova lattice is studied. Multistable topologies are shown. Intermittency of the dynamical contraction factor is found, and this behavior is a consequence of the collisions of kinks and antikinks. Fast kinks and antikinks are unstable. The transition from the localized kink to the whirling mode is found to be a temporal bifurcation cascade of generations of kink-antikink pairs and the collision-induced avalanche dynamics. Noise-induced topology transition is observed and discussed.``     

Multistable Spatiotemporal Dynamics in the Driven Frenkel-Kontorova Lattice

Spatiotemporal dynamics of the damped dc-driven Frenkel-Kontorova lattice is studied. Multistable topologies are shown. Intermittency of the dynamical contraction factor is found, and this behavior is a consequence of the collisions of kinks and antikinks. Fast kinks and antikinks are unstable. The transition from the localized kink to the whirling mode is found to be a temporal bifurcation cascade of generations of kink-antikink pairs and the collision-induced avalanche dynamics. Noise-induced topology transition is observed and discussed.     

Monte Carlo Transition Dynamics and Variance Reduction

For Metropolis Monte Carlo simulations in statistical physics, efficient, easy- to-implement, and unbiased statistical estimators of thermodynamic properties are based on the transition dynamics. Using an Ising model example, we demonstrate (problem-specific) variance reductions compared to conventional histogram estimators. A proof of variance reduction in a microstate limit is presented.     

Particle Velocity Measurements in Dense Fluidized Beds

The average local velocity of the upward of particles motion was determined in a dense fluidized bed by the means of a fibre optical probe. The probe consists of two independent light gates. The particles passing in front of the light gates reflect the light, generating sign sequences that are analysed by computer. From the average time difference of the sign sequences and from the distance of the light gates, the average local velocity can be calculated. The average local velocity of the particles along the height and diameter of the fluidized bed and also as a function of the fluidization air velocity was examined. It was concluded that the average local velocity is closely correlated with the local porosity of the dense fluidized bed and depends mainly on the fluidization air velocity. Using a fibre optical probe, the optimum range of the fluidization air velocity can be determined.     

Diurnal Dynamics of the Kinetic Energy in the Atmospheric Boundary Layer Retrieved from Minisodar Measurements

Russian Physics Journal - Based on the results of postprocessing of minisodar measurements of three wind velocity components and their variances in the lower 200-meter layer of the atmosphere, the...     

Dynamics of the Kinetic Energy in the Atmospheric Boundary Layer from the Results of Minisodar Measurements

Russian Physics Journal - Based on acoustic remote measurements of vertical profiles of three wind velocity components in a 200-meter boundary layer of the atmosphere, values of the kinetic energy...     

激光雷达数据应用于海气界面气体传输速率的估算

选取2007年1、4、7、10月4个月夜间无云的云-气溶胶激光雷达和红外探测者观测卫星(CALIPSO)星载激光雷达Version 3.01数据,提取532nm激光海面后向散射系数并计算海面波浪均方斜率。同时选用准同步AMSR-E海面风速数据,利用Wanninkhof等于2009年提出的包含线性、平方、立方项的海面风速与气体传输速率混合关系模型计算海水施密特数为660时的海气界面气体传输速率k660。通过回归分析,得到由星载激光雷达数据反演k660的关系模型。将激光雷达数据反演结果与采用4种典型海面风速关系模型的计算结果进行比较,给出由星载激光雷达数据反演的4个月平均的海气界面气体传输速率全球分布图和纬度分布图。研究表明,CALIPSO星载激光雷达532nm单脉冲测量数据可用于反演海气界面气体传输速率。     

Hugoniot实验的粒子速度测量不确定度分析

 不确定度评定是Hugoniot实验的一项重要工作,针对飞片撞击法和对比法两类主要Hugoniot实验进行了粒子速度的测量不确定度分析。根据直接测量量和间接输入量及其不确定度,用不确定度传递律表述了粒子速度的不确定度,并给出了冲击压强（p）、压缩密度（ρ）和压缩比容（v）的评定方法。对于样品和基板为不同材料的非对称碰撞及对比法实验,不确定度评定除A类评定外还应包括B类评定,应考虑用Hugoniot镜像线近似二次冲击绝热线或卸载线而导入的不确定度。在Hugoniot实验中应尽量避免涉及B类评定的其它因素,如同种材料初始密度的显著差异、飞片击靶前的温升等情况。     

基于最小方差的声速测量实验数据不确定度分析尺度

物理实验的不确定度分析是大学物理实验中的重点、难点内容。通过对声速测量实验中波长的测量不确定度进行分析,得出测量数据无偏估计和有偏估计时,测量次数对测量结果的影响。     

Measurements of Flow Velocity in the Plasma Generator PSI‐2

The plasma flow velocity in the Plasma Generator PSI‐2 has been investigated by using of Mach probe. PSI‐2 is a stationary high‐current arc discharge in which the quasi‐neutral plasma expands along the magnetic field lines. The low‐temperature (T_e < 20 eV), medium density (n_e ∼ 10¹⁸— 10¹⁹ m^—3 ) plasma in the discharge is similar to the plasma in the divertor region of tokamaks. From the ratio of ion saturation currents collected from opposite sides of the probe the flow velocities (Mach numbers) in argon and hydrogen discharges are obtained.     

Ultraviolet Rayleigh Lidar for Wind and Temperature Measurements

A new method of simultaneous remote sensing of atmospheric wind and temperature by a ultraviolet Rayleigh lidar is described. This technique uses two narrowband filters located at either side of the wings of the Rayleigh backscatter spectrum to analyze Rayleigh backscattering signals. These filters are selected to be greatly sensitive to both velocity and temperature. By measuring the ratio and the sum of the two normalized filtered signals, the line-of-sight wind velocity and temperature profiles can be retrieved. A lidar system is proposed for the wind velocity and temperature measurements in the middle atmosphere, and the simulation results show that the accuracies of velocity and temperature are about 1 m/s and 2 K at the height of 30 km, respectively. The influence of aerosol component has been estimated for clear weather conditions, and with an uncertainty of aerosol component of 15% the errors are about 0.1 m/s and 2 K above the troposphere, respectively.     

Velocity of Electric Wind and Efficiency of Electric Energy Conversion

The results of the theoretical and experimental studies of the electric wind velocity and efficiency are considered. The experiments are carried out in air at atmospheric pressure using the electrode system as a flat multispike electrode–two parallel tube.     

角度调谐的多普勒激光雷达硬目标转速测量

利用角度调谐方法确定直接探测多普勒测风激光雷达的初始工作点,角度调节精度可达10 μrad.在此工作点处使用频率稳定性为10-7,单纵模出现概率大于98%的Nd:YAG激光器,通过偏振分光光路测得参考信号与回波信号.配合目标准确放置到准直镜的焦距上,分别测量了配合目标静止,正转和反转时的参考信号与回波信号.利用配合目标静止时测得参考信号与回波信号的关系可得参考信号的角度矫正因子为1.1949,使用该矫正因子测得硬目标在正转和反转时转速与真实转速之间的误差小于0.5 m/s.