Space–Time Structure of Energetic Electron Precipitations according to the Data of Balloon Observations and Polar Satellite Measurements on February 1–6, 2015

Cosmic Research - The results of an analysis of the space–time characteristics and dynamics of precipitations of magnetospheric electrons with energies in the range from 0.1 to 0.7 MeV are...     

导流锥结构参数对燃气弹射筒内压力冲击平滑效果影响研究

针对导流锥结构参数对内弹道流场耦合影响问题，基于动态分层动网格技术，构建了含导弹运动和二次燃烧的内弹道数值模型，并验证了模型可靠性。解耦分析了导流锥半径、高度及冲击高度对内弹道流场特性和载荷的影响。结果表明：导流锥的结构直接决定燃气飞溅现象的产生和流场结构的紊乱程度，导流锥的半径、高度和冲击高度的改变会对燃气反射点的位置、二次燃烧的区域以及剧烈程度产生影响;结构优化后的导流锥，较大程度地缓解了冲击现象，获得了较好的平滑效果，筒底压力较实验装置降低了24.5%。     

Mapping mean lake surface from satellite altimetry and GPS kinematic surveys

Lake water height is a key variable in water cycle and climate change studies, which is achievable using satellite altimetry constellation. A method based on data processing of altimetry from several satellites has been developed to interpolate mean lake surface (MLS) over a set of 22 big lakes distributed on the Earth. It has been applied on nadir radar altimeters in Low Resolution Mode (LRM: Jason-3, Saral/AltiKa, CryoSat-2) in Synthetic Aperture Radar (SAR) mode (Sentinel-3A), and in SAR interferometric (SARin) mode (CryoSat-2), and on laser altimetry (ICESat). Validation of the method has been performed using a set of kinematic GPS height profiles from 18 field campaigns over the lake Issykkul, by comparison of altimetry’s height at crossover points for the other lakes and using the laser altimetry on ICESat-2 mission. The precision reached ranges from 3 to 7 cm RMS (Root Mean Square) depending on the lakes. Currently, lake water level inferred from satellite altimetry is provided with respect to an ellipsoid. Ellipsoidal heights are converted into orthométric heights using geoid models interpolated along the satellite tracks. These global geoid models were inferred from geodetic satellite missions coupled with absolute and regional anomaly gravity data sets spread over the Earth. However, the spatial resolution of the current geoid models does not allow capturing short wavelength undulations that may reach decimeters in mountaineering regions or for rift lakes (Baikal, Issykkul, Malawi, Tanganika). We interpolate in this work the geoid height anomalies with three recent geoid models, the EGM2008, XGM2016 and EIGEN-6C4d, and compare them with the Mean Surface of 22 lakes calculated using satellite altimetry. Assuming that MLS mimics the local undulations of the geoid, our study shows that over a large set of lakes (in East Africa, Andean mountain and Central Asia), short wavelength undulations of the geoid in poorly sampled areas can be derived using satellite altimetry. The models used in this study present very similar geographical patterns when compared to MLS. The precision of the models largely depends on the location of the lakes and is about 18 cm, in average over the Earth. MLS can serve as a validation dataset for any future geoid model. It will also be useful for validation of the future mission SWOT (Surface Water and Ocean Topography) which will measure and map water heights over the lakes with a high horizontal resolution of 250 by 250 m.     

面向战略导弹的新一代惯性系统

自主式惯性制导系统是战略导弹"威慑可信、反击可靠"的保障,针对我国已装备的战略导弹惯性系统在高精度、高可靠、实战化等方面存在的不足,系统阐述了位置捷联、位置平台和速率捷联的工作特点和局限性,首次提出了一种可同时满足高精度、全姿态、小型化的新一代惯性系统——速率平台.该惯性系统既具备速率捷联系统小型化、全姿态的特点,又兼顾了位置平台系统隔离角运动的功能.针对战略级惯性系统冗余不足引起的可靠性问题,在速率平台的基础上从智能化的角度提出了具备导航级故障诊断和自主重构的新体制惯性系统,该惯性系统将首次具备了自主导航、自主控制与自主重构的能力.     

基于北斗三号的长基线共视时间比对

卫星导航共视时间比对一直是远距离时间比对的重要方法之一。使用我国最新发射的北斗三号全球导航卫星，基于中科院国家授时中心（NTSC）和捷克光电研究院（TP）各自的时间产生和保持系统，开展了中捷北斗三号长基线共视时间比对试验。本文对中捷两站各自的北斗卫星可视数及其卫星高度角情况进行了统计分析，利用Vondark滤波对时间比对结果进行了降噪处理，最后将北斗三号共视时间比对结果与北斗二号及GPS共视时间比对结果进行了比较。结果表明：北斗三号在当前全球组网阶段中捷共视可视卫星数比北斗二号还少的情况下，其共视时间比对精度达到1.16ns，较北斗二号提升约19%，与GPS更为接近。     

某机载探测系统自主回收技术的实现

针对某机载探测系统探头回收自动化程度低的问题，提出了在无需操作员干预情况下实现探头自主回收的技术方法。采用了先进的控制算法，将缆位角与探头、缆长进行结合并引入了绞车控制系统，使绞车对探头的回收速度及缆长可进行实时调整，并给出了3种不同缆位角摆动条件下缆长与探头回收速度的控制曲线关系。研发了自主回收装置，设计了能够实现自主回收功能的探头回收机构。实验验证表明：在无需人为干预的条件下，在缆位控制系统及自主回收机构的配合下，系统实现了对探头快速、安全的回收。     

高超声速飞行器再入段LQR自抗扰控制方法设计

针对高超声速飞行器(HSV)再入过程中强非线性、强耦合、气动参数变化剧烈的不确定性的特点，提出一种基于线性二次型调节器(LQR)和自抗扰控制(ADRC)的高超声速飞行器再入段的姿态控制方法。首先，建立高超声速飞行器再入段线性化模型，并采用LQR方法完成了状态反馈控制律设计。然后，结合自抗扰控制技术，设计了扩张状态观测器(ESO)对系统的模型不确定性和外部干扰进行补偿，大幅增强了系统的扰动抑制能力。最后，将得到的高超声速飞行器再入段LQR自抗扰姿态控制器(LQRADRC)应用于高超声速飞行器六自由度仿真，仿真结果表明本文所提出的控制方法能够快速、精确地跟踪角位置指令，并且对系统不确定性具有强鲁棒性。     

The Role and Contributions of Energetic Neutral Atom (ENA) Imaging in Magnetospheric Substorm Research

Energetic Neutral Atom (ENA) imaging has contributed substantially to substorm research. This technique has allowed significant advances in areas such as observation and quantification of injected particle drift as a function of energy, observation of dynamics in the tail that are directly related to the effects of imposed (growth phase) and induced (expansion phase) electric fields on the plasma, the prompt extraction of oxygen from the ionosphere during substorms, the relationship between storms and substorms, and the timing of substorm ENA signatures. We present discussion of the advantages and shortcomings of the ENA technique for studying space plasmas. Although the technique is in its infancy, it is yielding results that enrich our understanding of the substorm process and its effects.     

Progress in battery technology since the first CSULB annual batteryconference and prospects for the future

Significant advances in and applications of battery technology are outlined. Factors driving future developments are identified