地磁定位方法综述

地磁导航具有可用区域广泛、无累积误差、无源和隐蔽性强等优势,是未来定位导航与授时（PNT）体系中潜在的重要导航定位手段之一。地磁导航技术包括磁场信息的测量、地磁基准图的建立和地磁定位方法的设计3个重要内容。本文主要围绕地磁定位方法,调研总结了当前主流的地磁滤波、地磁匹配和磁场同时定位与构图(SLAM)三类方法的原理及技术发展路线,重点分析了不同方法的优缺点、适用场景、时效性、对磁图和传感器的需求,并对地磁定位方法的发展方向进行了展望。     

磁悬浮控制力矩陀螺高速转子高频自激振动的抑制

磁悬浮控制力矩陀螺（CMG）中转子一阶弹性模态自激振动是影响磁悬浮高速转子系统稳定性的关键因素之一.自激振动通常可以采用陷波器（NF）进行抑制,然而引入NF或改变其参数以及转子转速的变化均会改变模态自激频率,因而难以直接准确地确定NF参数.本文提出一种仿真确定NF参数的方法,通过转子弹性模态缩减建模和模态参数确定得到准确的弹性转子动力学模型,进而采用闭环仿真优化确定NF中心频率和极点阻尼.采用该方法设计的NF有效抑制了转子的高频弹性模态自激振动,使得磁悬浮CMG转子可以稳定升速到24000r/min.实验结果验证了该方法的实用性和有效性.     

遥测数据传递介质的选择

遥测数据需要传递 ,传递介质的选择是一个重要问题。对我国遥测数据传递介质的沿革、现状进行了分析 ,对国外的发展趋势作了介绍 ,提出了硬盘记录 ,光盘传递的新思路     

磁净化卫星的磁场控制方法

卫星的磁净化程度对卫星探测磁场的精度起着关键的作用。文章根据国内外的经验,介绍了对有磁净化要求的卫星的磁场进行控制的办法,对我国磁净化卫星的研制有所启迪。     

地球磁尾的电场模式

地球磁层中的电场是磁层等离子体运动的主要驱动力。目前常用的磁层电场为均匀晨昏电场和投影电场。本文假定磁力线为电场的等位线，地球电离层电场看做磁层电场沿磁力线在电离层的投影。利用Tsyganenko磁场模式（T89），沿磁力线反电离层电场投影到磁尾，得到了一个新的磁层电场模式。文中对偶极磁场和T89磁场模式下的投影场作了比较，说明本模式突破了偶极磁场的局限，在磁层有更大的适用范围。     

Advances in space research nonlinear dependence of Dst and AE indices on the electric field of magnetic clouds

Using the Dst and AE geomagnetic index values and parameters of interplanetary magnetic field and solar wind we have examined the geoeffectiveness of transient ejections in the solar wind, namely, magnetic clouds and high-speed streams. It is found that for magnetic clouds the dependences of indices on the solar wind electric field are nonlinear of different kind. In contrast to magnetic clouds, the dependence of Dst and AE geomagnetic index values on the solar wind electric field agrees closely with the linear one for high-speed streams. We suggest approximating formulas to describe dependences obtained taking into account the relation of the electric field transpolar potential to the electric field and dynamic pressure of the solar wind. We suppose that the interplanetary magnetic field fluctuations also contribute to these dependences.     

Saw-tooth substorms: Inconsistency of repetitive bay-like magnetic disturbances with behavior of aurora

The relationships between the magnetic disturbance onsets, aurora dynamics and particles injections at the geostationary orbit have been analyzed in detail for 25 sawtooth substorms. It is shown that inconsistency between the above signatures of the substorms onset is typical of the powerful sawtooth substorms, unlike the isolated (“classical”) magnetospheric substorms. The distinguishing feature of the aurora in case of saw-tooth substorms is permanently high level of auroral activity irrespective of the magnetic disturbance onsets and the double oval structure of the aurora display. The close relationship between the aurora behavior and the particle injections at geostationary orbit is also broken. The conclusion is made, that the classical concept of the substorm development, put forward by Akasofu (1964) for isolated substorms, is not workable in cases of the sawtooth disturbances, when the powerful solar wind energy pumping into the magnetosphere provides a permanent powerful aurora particle precipitation into the auroral zone.     

Comparison of the observed and modeled low- to mid-latitude thermosphere response to magnetic activity: Effects of solar cycle and disturbance time delay

The performance of JB2008 and NRLMSISE-00 models, in describing the response of the thermosphere to magnetic activity are evaluated against total mass density retrieved from accelerometer measurements made onboard CHAMP satellite during 5 years. We show that the global low- to mid-latitude disturbance amplitude is correctly described by the JB2008 model for low solar activity conditions and by both the JB2008 and the NRLMSISE-00 models for high solar activity conditions. For low solar activity conditions, statistics based on almost 3 years of data confirm the large underestimation by the NRLMSISE-00 model quantified by Lathuillère et al. (2008) for the year 2004. We also found that the time delay between low- to mid-latitude global thermosphere disturbance and magnetic activity is statistically well estimated by the NRLMSISE-00 and JB2008 models for disturbed conditions. For moderately disturbed conditions however, the time delay estimated by the JB2008 model is too large by about 3 h. For very disturbed conditions, we found different time delays during day-time and night-time, using new geomagnetic proxies with a 30-min time resolution.     

Feasibility of developing an ionospheric E-region electron density storm model using TIMED/SABER measurements

We present a new technique for improving ionospheric models of nighttime E-region electron densities under geomagnetic storm conditions using TIMED/SABER measurements of broadband 4.3 μm limb radiance. The response of E-region electron densities to geomagnetic activity is characterized by SABER-derived NO⁺(v) 4.3 μm Volume Emission Rates (VER). A storm-time E-region electron density correction factor is defined as the ratio of storm-enhanced NO⁺(v) VER to a quiet-time climatological average NO⁺(v) VER, which will be fit to a geomagnetic activity index in a future work. The purpose of this paper is to demonstrate the feasibility of our technique in two ways. One, we compare storm-to-quiet ratios of SABER-derived NO⁺(v) VER with storm-to-quiet ratios of electron densities measured by Incoherent Scatter Radar. Two, we demonstrate that NO⁺(v) VER can be parameterized by widely available geomagnetic activity indices. The storm-time correction derived from NO⁺(v) VER is applicable at high-latitudes.