基于压缩传感的混沌二相码雷达成像

压缩传感系统利用信号稀疏表示的先验知识,能从少量的观测值中重构原始信号。由于混沌相位编码信号是一种伪随机码,其越来越多地应用在雷达领域。本文将压缩传感理论应用到混沌二相码雷达系统中,将成像问题转化为字典选择问题来处理,对接收的回波进行线性投影来降低采样频率,通过最小化光滑0范数重构成像。实验结果表明,本文方法在有效降低采样频率的基础上,获得了较高质量的成像效果,并且对噪声具有一定的自适应性。     

斜腹杆体外预应力结构杆索几何非线性耦合分析

采用增量线性化的分析方法,以斜腹杆体外预应力结构为研究对象,通过索单元模型的建立,应用几何关系、物理关系及平衡关系,求得索结点位移增量的结构切线刚度矩阵及腹杆伸缩增量列阵.研究表明,斜腹杆体外预应力结构切线刚度矩阵不仅与索单元杨氏模量、横截面面积、原长、当前的参量相关,还与腹杆当前的参量相关.用牛顿-拉斐逊(Newton-RaPhson)增量迭代法,对索结点位移编制计算程序.斜腹杆体外预应力结构杆索耦合的几何非线性分析,为梁-杆-索组合结构加固设计提供了理论依据.     

预给极点的二元矩阵有理插值

利用矩阵 Samelson逆和分叉连分式 ,给出了矩形网格上含预给极点的二元矩阵有理对角型插值算法 ,以及特征定理和唯一性定理 ,并给出了相应的证明     

月球表面光度行为的地域依赖性分析

月球表面光度行为描述了月表物质反射的太阳光随入射、出射和太阳相角的变化,它取决于月壤颗粒的粒径和形状、孔隙度、粗糙度等物理特性和矿物成分等化学性质．本文利用嫦娥一号干涉成像光谱仪（IIM）2A级辐亮度数据,基于太阳相角一辐亮度二维直方图统计,可将月球表面划分为两种光度行为迥异的地域类型,二者FeO含量分别与月海和高地的值大致吻合．高地（阿波罗16号着陆点）和月海（澄海）区域的IIM数据验证了该划分方法的合理性．本文提出的直接依据IIM2A级数据太阳相角一辐亮度二维直方图的划分方法,可以避免FeO含量划分月表光度单元中由于后期数据处理过程引入的误差．     

Species-specific calls evoke asymmetric activity in the monkey's temporal poles

It has often been proposed that the vocal calls of monkeys are precursors of human speech, in part because they provide critical information to other members of the species who rely on them for survival and social interactions. Both behavioural and lesion studies suggest that monkeys, like humans, use the auditory system of the left hemisphere preferentially to process vocalizations. To investigate the pattern of neural activity that might underlie this particular form of functional asymmetry in monkeys, we measured local cerebral metabolic activity while the animals listened passively to species-specific calls compared with a variety of other classes of sound. Within the superior temporal gyrus, significantly greater metabolic activity occurred on the left side than on the right, only in the region of the temporal pole and only in response to monkey calls. This functional asymmetry was absent when these regions were separated by forebrain commissurotomy, suggesting that the perception of vocalizations elicits concurrent interhemispheric interactions that focus the auditory processing within a specialized area of one hemisphere.     

探月卫星轨道的简单计算

本文以地球为参照系,用最简化的模型来估测从地球发射的探月卫星的轨道,详析了入轨速度对轨道性质及飞行时间的影响,由此引出最小能量轨道概念等。卫星进入月球引力范围之后的变轨及其他行为不在本文谈论范围之内。     

月神及月崇拜探微

古人膜拜天体自然,并演绎了不少神话传说,对月亮的崇拜也是如此。古代月神话与月崇拜大致包括三个方面的内容：古人月神观念产生的原因,认为月神观念的产生和发展,与早期农牧业生产和农牧业社会是分不开的;中国古代神话中的几种月神形象：月母常羲,月神西王母,嫦娥奔月等;月神话的寓意。     

Global inventory of Helium-3 in lunar regoliths estimated by a multi-channel microwave radiometer on the Chang-E 1 lunar satellite

Helium-3 (³He) implanted by solar wind in the lunar regolith is a valuable resource because of its potential as a fusion fuel. On the basis of the Apollo regolith samples, a linear relationship between ³He abundance and solar wind flux, optical maturity and TiO₂ content has been presented. China successfully launched its first lunar exploration satellite Chang-E 1 (CE-1) on October 24, 2007. A multi-channeled microwave radiometer was aboard the satellite with the purpose of measuring microwave thermal emission from the lunar surface layer. From the multi-channel brightness temperature (T_b) observed by CE-1, the global distribution of the regolith thickness was inverted from the multi-channel T_b, and was used to evaluate the total amount of ³He per unit area in the lunar regolith. The global inventory of ³He was estimated as being 6.6×10⁸ kg; 3.7×10⁸ kg for the lunar nearside and 2.9×10⁸ kg for the lunar farside.     

Glassy particles in lunar fines

Most of the Apollo 11 glassy particles differ from those generated by terrestrial volcanism, by meteoritic impacts, or by the condensation of the parent bodies of meteorites. Some of the particles may have been formed by the action of solar flares on the lunar surface.     

钢纤维混凝土电杆试验研究

研究分析了钢筋混凝土电杆产生纵向裂缝的机理，并采用钢纤维来抑制或限制电杆纵向裂缝的发生和发展；进行了电杆纵向裂缝控制措施的试验研究；还对钢筋混凝土和钢纤维混凝土电杆试件进行了抗冻性和抗腐蚀性的对比试验，试验结果对工程应用有重要的参考价值。     

月球探测器软着陆的最优控制

为研究月球探测器从月球泊轨道向月面软着陆的最优控制问题 ,提出了一种两次制动变轨的软着陆方案 :探月器从月球停泊轨道出发 ,启动变轨发动机进行第一次制动后飞向月球 ,在月面附近第二次制动以实现软着陆。在两次制动变轨时 ,对固定推力发动机的情况 ,采用 Pontryagin极大值原理对燃料最省变轨控制问题进行了分析 ,并引入遗传算法数值求解两点边值问题 ,得到了制动变轨的初始、终端位置和发动机推力方向角的最优控制规律     

一个涉及极点重数的亚纯函数正规定则

设F是平面区域D上的亚纯函数族,且族中每个函数的极点至少为k 1级.如果对所有f∈F,z∈D,有f(k) af3≠b,这里a≠0,b为两个有穷复数,则F为D上的正规族.