基于信噪比检验的双参数岭型Kalman滤波及其在BDS星地联合定轨中的应用

将Kalman滤波病态性诊断与处理相结合,提出基于信噪比检验的双参数岭型Kalman滤波。在分析Kalman 滤波的病态性以及岭型 Kalman 滤波的缺陷后,引入信噪比统计量度量每个待估参数受病态性影响的大小,将待估参数区分为涉扰参数和非涉参数,并利用两个岭参数对两类参数进行不同强度的修正,结合广义岭估计思想给出两个岭参数的选取方法。该算法在降低状态参数估计方差的同时尽量减少岭型Kalman滤波引入的偏差。利用STK仿真5颗GEO卫星+24颗MEO卫星+3颗IGSO卫星的北斗卫星星座并进行分布式自主定轨,结果表明提出的新算法能够有效改善病态性对Kalman滤波的不良影响,且相对于岭型Kalman滤波具有更高的定轨精度。     

新疆喀什-乌恰地区的P波速度模型和小震精确定位

利用新疆喀什—乌恰地区记录的数字地震资料,用BLOC86程序初步定位,根据射线追踪原理,给出相对精细的P波速度模型。由此模型,用JHD联合震中定位方法对记到的小震进行精确定位,并对定位精度做初步分析。     

Status of Satellite Orbit Determination and Time Synchronization Technology for Global Navigation Satellite System

In the form of satellite ephemerides and clock parameters, the information of space datum and system time of one global navigation satellite system (GNSS) is transferred to users. With continuously updating of satellite payload such as high precision atomic clocks, monitoring and tracking techniques such as inter-satellite links, and data processing techniques, the accuracy and real-time performance of satellite ephemerides and clock products are steadily improved. Starting from December 27th, 2018, BeiDou Navigation System 3, or BDS-3 has been providing accurate and reliable basic positioning, navigation, and timing (PNT) services to users in the countries within the “one belt and one road”. This paper summarizes the challenges of precise orbit determination and time synchronization faced and specific solutions sought from the regional BDS-2 system to BDS-3 global system at the control segment. It is interesting to compare BDS with other GNSS systems in terms of technical characteristics. Finally, aiming at higher accuracy and more reliable PNT services, a road map of precise orbit determination and time synchronization technique for next generation navigation systems is discussed, which will lead to better and better global navigation satellite systems.     

固相萃取-高效液相色谱-荧光检测法测定海水中的多环芳烃

建立了用固相萃取-高效液相色谱-荧光检测法测定海水中多环芳烃的方法,优化了色谱条件和萃取条件。除苊不能用荧光检测器检出外,其余15种多环芳烃的空白加标回收率在64.5%(苯并[g,h,i],茚并[1,2,3-cd]芘)～88.7%(苯并[a]蒽)之间,相对标准偏差(n=5)为4.9%(荧蒽,苯并[b]荧蒽)～11.1%(苯并[g,h,i],茚并[1,2,3-cd]芘),方法的检出限在0.72(蒽)～14.10 ng/L(荧蒽)之间,基本上达到了痕量分析的要求。利用该方法测得青岛湾表层海水中多环芳烃的浓度在0.125(苯并[k]荧蒽)～25.996 ng/L(萘)之间,但苯并[a]芘未检出。     

基于GPS的汽车稳定性控制系统研究

介绍GPS测姿原理,利用双天线GPS接收机直接测量车身侧偏角等汽车状态参数,采用卡尔曼滤波器融合GPS与INS测量数据。运用滑模控制理论,设计汽车稳定性控制器。运用Matlab/simulink软件仿真在变换车道等各种工况下控制器的控制效果。     

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地下掩埋管道及其地下建筑物压覆矿产边界的确定

地下掩埋管道及其地下建筑物压覆矿产边界,是由建设工程本身抗破坏能力、工程重要性以及矿体特征、开采方式、工程与矿体的相对位置等因素决定的。对于地下矿体,按围护带宽度、上覆各岩层移动角确定压覆矿产边界;对于地表非爆破性采矿,按围护带宽度和地表岩层移动角确定压覆矿产边界;对于地表爆破性采矿,安全爆破距离一般取50m。     

2-D Numerical Simulation of Natural Gas Hydrate Decomposition Through Depressurization by Fully Implicit Method

Natural gas hydrate, as a potential energy resource, deposits in permafrost and marine sediment with large quantities. The current exploitation methods include depressurization, thermal stimulation, and inhibitor injection. However, many issues have to be resolved before the commercial production. In the present study, a 2-D axisymmetric simulator for gas production from hydrate reservoirs is developed. The simulator includes equations of conductive and convective heat transfer, kinetic of hydrate decomposition, and multiphase flow. These equations are discretized based on the finite difference method and are solved with the fully implicit simultaneous solution method. The process of laboratory-scale hydrate decomposition by depressurization is simulated. For different surrounding temperatures and outlet pressures, time evolutions of gas and water generations during hydrate dissociation are evaluated, and variations of temperature, pressure, and multiphase fluid flow conditions are analyzed. The results suggest that the rate of heat transfer plays an important role in the process. Furthermore, high surrounding temperature and low outlet valve pressure may increase the rate of hydrate dissociation with insignificant impact on final cumulative gas volume.     

改进单组CEI基线对卫星定轨精度的影响研究

短基线相位干涉测量是一种被动测角卫星定轨跟踪方法,测量精度高。利用该方法采用单组正交双基线对静地卫星的定轨精度进行了仿真计算,并分别采用物理延长东西基线和东西基线阵列两种方法来考察对卫星定轨精度的改进情况。仿真结果表明,物理延长东西基线可以显著提高定轨精度;若星下点与跟踪网相距较远,则东西向基线阵列可显著提高定轨精度,且该方法对我国北斗卫星群的整体定轨效果很好,能进行几十米级的定轨。