Generation of simultaneous H+ and He+ band EMIC waves in the nightside radiation belt

Science China Technological Sciences - Previous studies have shown that EMIC waves occur preferentially in the afternoon sector of the magnetosphere. Here we report obliquely propagating H+ and He+...     

Investigation of the mesospheric temperature over Fort Collins region

The nightly mean mesospheric temperature profiles between 80 and 107 km,observed by Na lidar,over Fort Collins,Colorado(41°N,105°W)from 1990 to 2010,are employed to research the temporal and spatial variations and mesopause.We find that the maximum mean temperature is in summer months above 95 km,but reverse below 95 km,and there is a cooler region below 185 K around 97 km in August.The largest seasonal variation is 39.2 K at 81 km,and the minimum is 6.5 K at 96.5 km.The maximum standard derivation in spring and autumn months are larger than other seasons above 105 km,but the temperatures in March,June and September are lower than the other months between 82 km and 100 km where winter is the largest season.Moreover,the seasonal variations of the temperature are about 36,8 and 21 K at 85,95 and 105 km,respectively.winter is colder and summer is warmer above 97.5 km,but reverse below 92 km.The mesopause height is around 102 km in winter,but 84 km in summer,and the mean speed of decreasing or increasing of the mesopause height is about 5 km/month in spring and autumn months which are about 90 km.The lasting time of the mesopause in winter is near 6 months,longer than other seasons,and the mesopause temperature is about 165 K in cool summer,and 185 K in warm winter.     

Correlated observations linking loss of energetic protons to EMIC waves

Electromagnetic ion cyclotron (EMIC) emission is an efficient mechanism for scattering loss of energetic protons. Here, we report an event that provides both in-situ observation of energetic proton differential fluxes in the inner magnetosphere and precipitation of protons at ionospheric altitudes. During the 7–8 September 2015 geomagnetic storm the Van Allen Probes observed strong EMIC waves around L = 5 and a distinct decrement in fluxes of tens of keV protons around pitch angles 0°–45°. Meanwhile, precipitating protons at ionospheric altitudes were found to significantly enhanced (by several orders of magnitude), measured by NOAA 18 and 19 when they magnetically linked to the Van Allen Probe-A. By solving the Fokker-Planck diffusion equation, we show that EMIC waves can efficiently produce loss of energetic protons within about 2 h in the pitch angle range of ∼ 0°–45°, comparable to the satellite observations.

     

六自由度并联机器人的支链选取

提出了六自由度并联机器人的支链选取的系统方法． 并联机器人中有多种类型的支链可以用来实现末端执行器的6自由度运动， 每个支链的驱动关节应当在基座上或靠近基座的地方， 由支链所构成的整个并联机构的自由度应当为6．利用这些条件对并联机器人的支链形式进行筛选可以获得可行的支链形式． 通过这种方法可以去除很多不可行的支链形式, 得到可行的支链形式供后续设计使用．     

Observations of the field-aligned residual flow inside magnetic cloud structure

In this paper, we report two MC events observed by WIND spacecraft with good examples of field-aligned residual flow inside the MC structure. For both events, the co-moving frames are determined through the deHoffman-Teller (HT) analysis and the axial orientations are inferred by the newly developed minimal residue (MR) method. The nature coordinate system for both events are constructed with velocity of the HT frame and the inferred MC axis, the field and flow remaining in the HT frame are analyzed at this coordinate system. As a result, we find that the residual flows in the co-moving HT frame of the two MC events are almost anti-parallel to the helical magnetic field. We speculate that the field-aligned residual flows are large scale coherent hydrodynamic vortices co-moving with the MCs at the supersonic speed near 1 AU. Data analyses show that the event in slow ambient solar wind is expanding at 1 AU and another one in fast solar wind does not show apparent expansion. Proton behaviors for both events are quasi-isothermal. Accelerated HT analysis shows that both events have no suitable HT frame with constant accelerations, which suggests that both events may be moving at the constant speed near 1 AU under the assumptions of the HT analysis. For both events, the ratio of the dynamic pressure to the magnetic pressure is larger than that of the thermal pressure to magnetic pressure, which suggests that the dynamic effects due to the plasma flows remaining in the co-moving HT frame are more important than the thermal effects in the study of MC evolution and propagation. Supported by the National Natural Science Foundation of China (Grant Nos. 40621003, 40804046, 40536029, 40674084 and 40523006), the National Basic Research Program of China (“973” Project) (Grant No. 4902006CB806304), the Specialized Research Fund for State Key Laboratories, and the Open Research Program of the State Key Laboratory of Space Weather, Chinese Academy of Sciences     

一种新型自重构模块的设计

文章论述了自重构机器人的类型,国内外的发展情况,并提出了一种新型自重构模块。讨论并分析了设计模块机构阶段所遇到的问题,特别是离合器的机构设计,以及必须遵守的两种状态。为了使控制简单,采用开关量控制,把旋转面对接机构设计为差动连接,并对该模块机器人的运动形式和步态作了进一步解释。     

Multi-physical field coupling simulation of TCVI process for preparing carbon/carbon composites

To prepare Carbon/Carbon (C/C) composites with advanced performance, the thermal gradient chemical vapor infiltration (TCVI) process has been optimized by simulation. A 2D axisymmetric unstable model was built, which included convection, conduction, diffusion, densification reactions in the pores and the evolution of the porous medium. The multi-physical field coupling model was solved by finite element method (FEM) and iterative calculation. The time evolution of the fluid, temperature and preform density field were obtained by the calculation. It is indicated that convection strongly affects the temperature field. For the preform of carbon/carbon composites infiltrated for 100 h by TCVI, the radial average densities from simulation agrees well with those from experiment. The model is validated to be reliable and the simulation has capability of forecasting the process.     

The influence of various frequency chorus waves on electron dynamics in radiation belts

Science China Technological Sciences - Non-adiabatic behaviour induced by the chorus-electron interaction is an important contributor to the radiation belt dynamics, and largely relies on wave...     

基于分子指纹的中药分子作用网络分析系统的研究与实现

近年来,从传统中药中寻找活性成分成为研发新药的有效途径,而对中药分子作用机制的研究将显著提高筛选的准确性。本文在前期的研究基础上实现了中药成分的靶标预测、根据预测靶标构建成分-靶标网络、利用网络特征实现分子网络的筛选和分析等核心分析方法,设计了一种高效、易用的中药分子作用网络自动化分析系统。用户可以通过 web 的方式方便的获取中药成分数据,并利用本系统对所需的中药数据进行靶标预测和分子网络研究与分析。