Satellite Constellation Design for Complex Coverage

Most traditional satellite constellation design methods are associated with a simple zonal or global, continuous or discontinuous coverage connected with a visibility of points on the Earth's surface. A new geometric approach for more complex coverage of a geographic region is proposed. Full and partial coverage of regions is considered. It implies that, at any time, the region is completely or partially within the instantaneous access area of a satellite of the constellation. The key idea of the method is a two-dimensional space application for maps of the satellite constellation and coverage requirements. The space dimensions are right ascension of ascending node and argument of latitude. Visibility requirements of each region can be presented as a polygon and satellite constellation as a uniform moving grid. At any time, at least one grid vertex must belong to the polygon. The optimal configuration of the satellite constellation corresponds to the maximum sparse grid. The method is suitable for continuous and discontinuous coverage. In the last case, a vertex belonging to the polygon should be examined with a revisit time. Examples of continuous coverage for a space communication network and of the United States are considered. Examples of discontinuous coverage are also presented.

新疆布尔根碱性花岗岩地球化学特征及其形成演化过程的探讨

笔者收集了大量国内外学者对世界各地碱性花岗岩的研究资料，总结出碱性花岗岩典型的岩石组合主要有以下几种：1、碱性花岗岩、花岗岩、正长岩、辉长岩、斜长岩（BarKer 等 1975）。2、碱性花岗岩、双套花岗岩系列（均为准铝质）、流纹岩、辉长岩、玄武岩（如澳大利亚南部 Collins 等 1982）。3、碱性花岗岩、黄玉流纹岩（准铝或过铝质）（Burt 等 1982）。4、碱性花岗岩、辉长岩、闪长岩、玄武岩' 闪碱流岩等（南大西洋中 Ascension 岛上）（Weis 1983, Harris 等 1982，1983）。新疆现被确认的碱性花岗岩有布尔根碱性花岗岩。黄羊山碱性花岗岩及新源阿拉马勒碱性花岗岩等，这些碱性花岗岩研究程度都不高，有的尚属空白。布尔根碱性花岗岩岩体是 86 年后才发现的。它们被认为是典型的碱性花岗岩。由于研究碱性花岗岩的物质来源及形成方式等问题对花岗研究工作有重要意义。特别是本区域花岗岩的时代及含矿性在阿尔泰花岗岩中更具有特殊意义。因此本文选择布尔根碱性花岗岩为研究对象，并附带其它几个岩体，以弥补这一地区碱性花岗岩研究的空白。