基于扩张观测器的航天器无速度旋量信息姿轨一体化控制

针对在轨飞行期间无法精确获得速度信息（角速度与质心速度）的情况,设计了基于扩张状态观测器的航天器姿轨一体化控制器.首先给出了基于对偶四元数的航天器姿轨一体运动学与动力学模型;然后针对速度旋量信息缺失的情形并考虑模型参数误差与外界扰动设计了扩张状态观测器,并利用Lyapunov稳定性定理分析观测误差的有限时间收敛性;最后基于该扩张观测器设计航天器姿轨一体快速终端滑模控制器,分析该控制系统的有限时间收敛性,并进行数值仿真验证.     

河北邯邢地区盐类矿产的成矿条件和远景分析

通过对文献资料和石油、地质等部门的实际勘查资料综合分析,结合邯邢地区新生代沉积盆地的实际情况,初步认为古近系沙河街组二、三、四段及孔店组上部白云岩段地层是盐类矿产赋存的主要层位,是寻找盐类矿产的前提条件,并提出寻找此类矿床的远景区.     

Silicon and sediment transport of the Changjiang River (Yangtze River): could the Three Gorges Reservoir be a filter?

Water samples were collected from the Changjiang River (Yangtze River) in May 2005, after the impoundment of the Three Gorges Reservoir (TGR), to examine the influence of the TGR and large lakes on material delivery to the estuary of the Changjiang River. The concentrations of suspended particle material (SPM), dissolved silica (DSi) and biogenic silica (BSi) in the main stream were analyzed. The concentrations of DSi and BSi in the main channel of the Changjiang varied between 73 and 100 and 1.1–15 μmol/l, with a distance weighted average of 81 and 8.0 μmol/l, respectively. A calculation shows that live diatom comprises only an average value of 5.2 % of the BSi in the Changjiang River, and most of BSi may come from drainage basin. The concentrations of BSi and the ratios of BSi/SPM were relatively low in the Changjiang River compared to other rivers throughout the world, but the BSi carried in suspension by the Changjiang River was an important component of the rivers silicon load (i.e. ~13 %). SPM, DSi and BSi concentrations as observed in the Changjiang River tend to decrease from the upper sections of the river to the Three Gorges Dam (TGD), reflecting sedimentation associated with BSi trapping and DSi retention in the TGR in the normal-water period. SPM and BSi retention are more strongly influenced by the TGD compared to DSi. About 98 % of SPM, 72 % of BSi and 16 % of DSi were retained within the TGR in May 2005. The fluxes variations of DSi, BSi and SPM suggested that the large lakes and dams had a coupled effect on the transportation of DSi, BSi and SPM in the normal-water period. Such a change in silicon (DSi and BSi) balances of the Changjiang River will affect the ecological environment of the Changjiang estuary and its adjacent sea to some extent.     

济阳拗陷第三纪玄武岩的Nd—Sr同位素研究

本文报道了济阳拗陷29个第三纪玄武岩的Nd，Sr同位素组成。结果表明，该区早、晚第三纪玄武岩的Nd-Sr同位素组成变化且具有一定的区别：早经三纪玄武岩的εNd值为0．70481－0．70830；晚第三纪玄武央的εNd值为0．1－2．3，^87Sr/^86Sr比值为0．70421－0．70530。鉴于εNd与1/Nd有^87Sr/^86Sr与1／Sr之间不存在相关特征，Nb正异常以及SiO2与MgO，Fe2O3 FeO,P2O5呈负相关，与Al2O3呈正相关，但与K2I为不存在相关特征，因此，地壳混染作用并不是第三纪玄武岩同位素组成变化的主要原因。玄武岩^87Sr/^86Sr比值的升高是由热液蚀变造成的，而εNd值的变化而归因于源区混合。如果热液蚀变作用没有发生，这些玄武岩的所有数据点在Nd-Sr相关图上将可能位于地幔系列内部。这表明第三纪玄武岩主要是由DMM和EMI两个端员组分不同程度混合形成，EMII的贡献是次要的。     

1961—2014年中国高温热浪变化特征分析

基于全国1961—2014年716个站点的日最高气温资料和高温阈值与热浪HWMI （Heat-Wave Magnitude Index）指数的新定义,分析了全国高温热浪的高温日、热浪频次、HWMI指数的时空变化特征。结果表明：高温日开始早（晚）的地区结束相对较晚（早）。高温日数突变集中于1990s末至本世纪初期。研究时段内,全国性的严重高温热浪事件从7月上旬持续至9月上旬,各旬热浪频次差异较大;云南地区热浪频发于5月,其他月份热浪少见。除淮河流域热浪年频次呈减小趋势,全国其余地区呈现增加趋势,其中两广、云南和海南地区增加趋势最大。热浪指数从1960s—1980s递减,1990s后递增,且1998年后全国高强度热浪频发,特别是长江以南地区。     

利用Vicon系统进行IMU标定

针对传统IMU标定方法操作复杂、过于依赖转台的问题,本文提出了一种利用Vicon系统进行IMU标定的方法。首先,利用预积分技术将IMU数据与Vicon数据融合,得到IMU残差;然后,将Vicon相邻帧间的状态量相减,得到Vicon残差;最后,将IMU残差和Vicon残差放到同一个状态向量中,并引入边缘化先验信息,建立非线性优化函数,求解得到陀螺仪和加速度计的零偏估计参数。同时本文设计EuRoc数据集测试试验和室内定位对比试验,结果表明,该方法对IMU的标定结果优于传统方法的标定结果,具有更高的精度。     

E+A星系的研究进展

E+A星系的光谱具有很强的巴耳末吸收线,缺乏与恒星形成相关的发射线,将典型的椭圆星系(E)和A型恒星的光谱进行线性组合就能够拟合出这类星系的光谱.它们的颜色、形态、星族年龄等参数介于典型的早型和晚型星系之间.E+A星系近期经历了星暴活动,在星系演化进程中,它们处于晚型到早型的过渡阶段,可能在演变过程中扮演着重要角色.介...     

Precise relative positioning using real tracking data from COMPASS GEO and IGSO satellites

China completed a basic COMPASS navigation network with three Geostationary and three Inclined Geosynchronous satellites in orbit in April 2011. The network has been able to provide preliminary positioning and navigation functions. We first present a quality analysis using 1-week COMPASS measurements collected in Wuhan. Satellite visibility and validity of measurements, carrier-to-noise density ratio and code noise are analyzed. The analysis of multipath combinations shows that the noise level of COMPASS code measurements is higher than that of GPS collected using the same receiver. Second, the results of positioning are presented and analyzed. For the standalone COMPASS solutions, an accuracy of 20 m can be achieved. An accuracy of 3.0 m for the vertical, 1.5 m for the North and about 0.6–0.8 m for the East component is obtained using dual-frequency code only measurements for a short baseline. More importantly, code and phase measurements of the short baseline are processed together to obtain precise relative positioning. Kinematic solutions are then compared with the ground truth. The precision of COMPASS only solutions is better than 2 cm for the North component and 4 cm for the vertical. The standard deviation of the East component is smaller than 1 cm, which is even better than that of the East component of GPS solutions. The accuracy of GPS/COMPASS combination solutions is at least 20 % better than that of GPS alone. Furthermore, the geometry-based residuals of double differenced phase and code measurements are analyzed. The analysis shows that the noise level of un-differenced phase measurements is about 2–4 mm on both B1 and B2 frequencies. For the code measurements, the noise level is less than 0.45 m for B1 CA and about 0.35 m for B2 P code. Many of the COMPASS results presented are very promising and have been obtained for the first time.     

多类型历书对首次定位性能的影响研究

研究了GPS接口文件中规定的高精度历书和中等精度历书两种不同格式历书对接收机捕获卫星信号的影响,比较两种历书与广播星历数据计算的卫星位置和速度之差,分析两种历书带来的码相位和多普勒频移搜索的不确定度,进而估计两种历书对于首次定位时间的影响.利用实际的历书数据在多城市进行一周时间的仿真分析.结果表明:历书数据龄期为一周时,高精度历书的精度无明显变化,能够较为有效地压缩码相位搜索空间,改善首次定位时间;而中等精度历书精度逐渐变差,其首次定位时间逐渐增大.     

利用星载GPS观测数据确定海洋2A卫星cm级精密轨道

系统研究了基于国产星载双频GPS接收机的海洋2A(HY2A)卫星精密定轨问题,并对星载双频GPS接收机天线相位中心进行了校正.结果显示,HY2A卫星径向定轨精度可达1～2 cm,天线相位中心标定精度为mm级.相关成果可应用于我国后续所有搭载双频GPS接收机的对地观测卫星计划.