空间VLBI的研究现状

评述了过去近三十年中空间VLBI的发展．其内容包括空间VLBI的简短发展历史,空间VLBI与地面VLBI的不同、空间VLBI的目前状况和空间VLBI的未来展望。着重介绍了作为首次空间VLBI的VSOP的各个方面情况,并给出了VSOP的连续谱、谱线普查样本,供参考。     

多星混合资料的定轨

在空间目标光学观测资料定轨中常常会遇到多个目标的观测被标记为同一个目标的情况,由于包含了多个目标的数据,定轨过程无法收敛或者完全错误.从极大似然估计角度,采用EM(Expectation Maximum)方法提出一种将轨道改进和识别过程相互融合的处理方法,并在具体实现过程中给出一种稳健估计方法.数值模拟表明方法简便、有效、可行.采用站间差历元差的手段,对当前电离层变化值进行求解与预测,可以将电离层延时误差的变化控制在一定范围,满足频率传递的要求.     

Strange quark matter attached to string cloud in Bianchi type-III space time

We have obtained Bianchi type-III cosmological model with strange quark matter attached to the string cloud in general relativity. For solving the Einstein’s field equations the relation [C=A ⁿ ] between metric coefficients C and A is used. Also, some physical and kinematic properties of the model are discussed.The results are analogous to results obtained by Yilmaz (Gen. Rel. Grav. 38:1397–1406, 2006).     

GEO空间碎片光度测量标定方法的研究

基于GEO卫星、太阳和观测站的空间几何关系,建立了消除太阳赤纬角对地球同步轨道( Geostationary Orbit,GEO)卫星光学特性的影响的方法.以三轴稳定GEO盒状卫星缩比模型为研究样本,在不同太阳赤纬角下进行仿真实验光度测量,研究太阳赤纬角和相位角的空间几何关系,得出消除太阳赤纬角对其辐亮度值以及以相位角...     

Fractal Dimensions as Chaos Indicators

The correlation dimension D ₂ is used to develop a method of classification for phase space orbits. D ₂ depends only on the mutual distances of the orbits points, therefore the time development of the orbit is reflected in the time development of the correlation dimension approximants. It is shown, that this technique allows to investigate the dynamical properties of a phase space orbit, a classification of chaotic and regular orbits and a detection of sticky orbits.     

银河系中球状星团的空间运动

球状星团是银河系中最古老的天体类型之一,其累积光度很大,是银晕中重要的示踪天体。已以发现的银河系球状星团有１４０多个,其中１２０个银心距Ｒ〈４０Ｋｐｃ的星团已被准确地测定了视向速度。根据结数据以及球状星团金属度的统计分析,可以把球状星团次系再进一步分成某些不同的族群。目前已经测定过绝对自行的球状星团只有３８个,尽管这些自行的精度比视向速度和距离的精度差很多,然而,由此可以得出三维的空间速度,在统计     

On the extraction of extended structure from Herschel-SPIRE scanning observations in the presence of 1/f noise

We present results from a study of the impact of uncorrelated 1/ f noise on the extraction of spatial structure, on a range of scales, from sky mapping observations made using the Herschel-SPIRE (the spectral and photometric imaging receiver) photometer in the scan-map mode. These studies were carried out using a detailed instrument simulator, and the output reduced using the map-making algorithm to be implemented in the SPIRE data pipeline. The influence of source size scale, telescope-scanning rate and 1/ f noise knee frequency is investigated, and operational bounds to the expected losses are presented, using the case of zero 1/ f (white) noise as a benchmark. Both cross-linked and non-cross-linked observing options are studied. The results presented here represent the best current estimate of the sensitivity of the SPIRE photometer to emission on arbitrary scales. The data presented are general and scalable to any SPIRE observation made using the scanning mode.     

Comparison of Meteoroid Flux Models for Near Earth Space

Over the last decade several new models for the sporadic interplanetary meteoroid flux have been developed. These include the Divine-Staubach and the Dikarev model. They typically cover mass ranges from 10⁻¹⁸ g to 1 g and are applicable for model specific Sun distance ranges between 0.1 AU and 20 AU Near 1 AU averaged fluxes (over direction and velocities) for all these models are tuned to the well established interplanetary model by Grün et al. However, in many respects these models differ considerably. Examples are the velocity and directional distributions and the assumed meteoroid sources. In this paper flux predictions by the various models to Earth orbiting spacecraft are compared. Main differences are presented and analysed. The persisting differences even for near Earth space can be seen as surprising in view of the numerous ground based (optical and radar) and in situ (captured Inter Stellar Dust Particles, in situ detectors and analysis of retrieved hardware) measurements and simulations.     

Research activities on land-use/cover change in the past ten years in China using space technology

１　ＩＮＴＲＯＤＵＣＴＩＯＮＴｈｅｒｅｃｅｎｔａｎｄｆｕｔｕｒｅｄｅｖｅｌｏｐｍｅｎｔｏｆｓｐａｃｅｂａｓｅｄｒｅｍｏｔｅｓｅｎｓｉｎｇｔｅｃｈｎｏｌｏｇｙｈａｓｂｒｏｕｇｈｔａｒｅｆｏｒｍａｔｉｏｎｔｏｒｅｓｅａｒｃｈｗｏｒｋａｓｗｅｌｌａｓｆｏｒｍｕｌａｔｉｎｇｓｕｉｔａｂｌｅｐｏｌｉｃｙｆｏｒｐｏｐｕｌａｔｉｏｎ,ｒｅｓｏｕｒｃｅｓ,ｅｎｖｉｒｏｎｍｅｎｔａｎｄｄｅｖｅｌｏｐｍｅｎｔ．Ｔｈｒｏｕｇｈｒｅａｌｔｉｍｅａｎｄｐｅｒｉｏｄｉｃｏｂｓｅｒｖａｔｉｏｎｓｏｆａｌａｒｇｅａｒ…