日改进H—2火箭以期进入国际发射市场

日本宇宙事业开发团（ＮＡＳＤＡ）已开始全面研制３种改进型Ｈ－２运载火箭，这３种火箭依次称为Ｈ－２Ａ、Ｈ－２Ｂ和Ｈ－２Ｃ。其中，Ｈ－２Ａ与Ｈ－２的运载能力相当，它是与阿里安－４同级的运载火箭；Ｈ－２Ｂ和Ｈ－２Ｃ将使用与ＬＥ－７发动机相似的发动机作为捆绑...     

熔盐反应法生长Bi－Pb－Sr－Ca－Cu－O系超导单晶

利用熔盐反应法生长了Ｂｉ－Ｐｂ－Ｓｒ－Ｃａ－Ｃｕ－Ｏ系超导单晶．这种方法容易生长高纯的Ｂｉ２Ｓｒ２ＣｕＯｘ和Ｂｉ２Ｓｒ２ＣａＣｕＯｘ单晶，也已生长了２２１２和２２２３相交生的片状单晶，其中（Ｂｉ，Ｐｂ２Ｓｒ２Ｃａ２Ｃｕ３Ｏｘ相的体积分数约５０％．利用电子衍射图样，ＸＲＤ，ＥＤＡＸ和磁化率的测量对晶体结构、组分和超导电性进行了研究．     

巴西 VLS 运载火箭首次发射失败

巴西ＶＬＳ运载火箭首次发射失败１９９７年１１月２日，巴西自己制造的第一枚“卫星运载火箭”（ＶＬＳ———ＶｅｉｃｕｌｏＬａｎｃａｄｏｒｄｅＳａｔｅｌｉｔｅｓ）进行了首次发射。ＶＬＳ火箭携带了一颗１５０ｋｇ重的ＳＣＤ２Ａ环境数据收集卫星，从巴西的阿尔坎...     

熔盐反应法生长Bi—Pb—Sr—Ca—Cu—O系超导单晶

利用烷盐反应法生长了Ｂｉ－Ｐｂ－Ｓｒ－Ｓｒ－Ｃａ－Ｃｕ－Ｏ系超导单晶，这种方法容易生长高纯的Ｂｉ２Ｓｒ２ＣｕＯｘ和Ｂｉ２Ｓｒ２ＣａＣｕＯｘ单晶，也已生长了２２１２和２２２３相交生的片状单晶，其中（Ｂｉ，Ｐｂ）２Ｓｒ２Ｃａ２Ｃｕ３Ｏｘ相的体积分数约５０％，利用电子衍射图样，ＸＲＤ，ＥＤＡＸ和磁化率的测量对晶体结构、组分和超导电性进行了研究。     

空间环境对漫反射板的影响

光学系统在空间环境条件下的衰变对卫星遥感仪器探测精度有重要影响．漫反射板是星载光学遥感仪器辐射定标的重要工具．本文通过对ＡＤＥＯＳ／ＴＯＭＳ和Ｅａｒｔｈ Ｐｒｏｂｅ／ＴＯＭＳ仪器馒反射板漫反射率衰变特性的比较，分析研究了原子氧和太阳紫外辐射对漫反射板的影晌．结果表明，太阳紫外辐照和原子氧剥蚀引起的漫反射板反射率衰变系数分别为０．０００４９／ｈ和１．２ × １０－１７ｃｍ２，但在卫星入轨初期，太阳紫外辐照的影响可增加约４倍．     

中国向国际电联登记的静止卫星轨道位置表

登记的卫星名称１）国内用的名称轨道位置频段登记情况２）ＳＴＷ－１试验通信卫星１２５°ＥＣＮＳＴＷ－２试验通信卫星１０３°ＥＣＮＣｈｉｎａｓａｔ－１东方红－２甲８７．５°ＥＣＮＣｈｉｎａｓａｔ－２东方红－２甲１１０．５°ＥＣＮＣｈｉｎａｓａｔ－３东方红－２甲９８°ＥＣＮＣｈｉｎａｓａｔ－４东方红－２甲１３０°ＥＣＡＣｈｉｎａｓａｔ－１１银行星１０１．５°ＥＫｕＡＣｈｉｎａｓａｔ－１２银行星１０５°ＥＫｕＡＣｈｉｎａｓａｔ－２１烽火－１１０３°ＥＵＨＦ，Ｃ＊Ｃｈｉｎａｓａｔ－２２烽火－１９８°ＥＵＨ…     

空间扫描

英国“萨利”卫星定于１９９６年１０月升空　它从拜科努尔发射场的一个导弹发射井发射，重１５０ｋｇ。日本推迟Ｈ－２火箭发射　由于Ｈ－２火箭设备问题，先进对地观测卫星－１（Ａｄｅｏｓ－１）、工程试验卫星－７等卫星推迟升空。日本现正努力降低Ｈ－２的发射费用，拟于１９９９年把每次发射费降至０．９亿美元或大约是目前发射费用的一半；还在积极想法提高Ｈ－２的推力，争取达到能把３～４吨重的有效载荷送入静地轨道的水平。俄罗斯拟于明年第一季度发射“自然”舱　如能顺利升空，对接到和平号空间站上，则该空间站将大功告成。俄…     

日本将实施4星气候监测计划

日本宇宙开发事业团（ＮＡＳＤＡ）预计将在２０００年４月开始实施一项包括４颗卫星的全球气候监视计划。ＮＡＳＤＡ目前已申请了大约１．２亿日元（合１００万美元），用于对２颗拟于２００５年发射的全球变化观测卫星（ＧＣＯＭ——ＧｌｏｂａｌＣｈａｎｇｅＯｂｓｅｒｖａｔｉｏｎＭｉｓｓｉｏｎ）进行研究。这笔研究经费尚待日本空间活动委员会的批准。第一颗卫星称为ＧＣＯＭ－Ａ１，其重点任务是大气监测。第二颗卫星是ＧＣＯＭ－Ｂ１，将携带５种遥感器，其重点任务是地球观测。它们的２颗后继星ＧＣＯＭ－Ａ２、Ｂ２，将于２０１０…     

日本的H—2火箭

Ｈ－２火箭是日本宇宙事业开发团（ＮＡＳＤＡ）经过９年的艰苦努力，完全依靠自己的技术力量研制出来的第一枚大推力运载火箭。Ｈ－２火箭采用了现代化的材料、电子设备、计算机和推进系统，是世界上目前最先进的，率先全部使用氢氧发动机的一次性使用运载火箭。Ｈ－２火箭有两级，高５０米，不载有效载荷的起飞重量为２６０吨。第一级由ＬＥ－７主发动机和两枚固体火箭助推器组成；第二级采用ＬＥ－５Ａ主发动机。Ｈ－２火箭能将８８００磅（约４吨）的有效载荷送入地球静止转移轨道，或将４４００磅（约２吨）的有效载荷送入地球静止轨道…     

空间扫描

空间扫描巴西首次卫星发射失败１９９７年１１月２日在位于赤道附近的阿甘达拉发射基地，巴西首次用自行研制的ＶＬＳ－１火箭发射一颗数据采集卫星ＳＣＤ－２Ａ。火箭是在当地时间１０时２５分点火的，６５秒钟后火箭升至３２３０ｍ的高度时，４个助推器中的１个熄火，致...     

Stochastic particle acceleration by the forced interaction of relativistic current sheets

We address the problem of interacting relativistic current sheets in self-consistent kinetic plasma simulations within the framework of the Particle-In-Cell model. The interaction is enforced in head-on collisions of up to 10 current sheets at relativistic bulk speeds. The simulations are motivated by the general problem of Poynting flux dissipation in ‘striped wind’ configurations presumably governing the relativistic outflows pervasive in pulsar winds and gamma-ray bursts. We identify the generation of non-thermal particles and formation of a stable power-law shape in the particle energy distributions f(γ) dγ ∝ γ^−s dγ. In 1D, a spectral index s ∼ 2 is observed and attributed to a stochastic Fermi-type acceleration mechanism. In 2D, the generic index of s ∼ 3–4 is retained as in previous simulations of individual current sheets. Whereas in 2D the high energy cut-off is constrained by the limited dissipation of magnetic energy, in 1D the process converts the bulk motion of current sheets towards directed particle momentum of an exclusive class of non-thermal particles.     

Scaling analysis and model estimation of solar corona index

A monthly average solar green coronal index time series for the period from January 1939 to December 2008 collected from NOAA (The National Oceanic and Atmospheric Administration) has been analysed in this paper in perspective of scaling analysis and modelling. Smoothed and de-noising have been done using suitable mother wavelet as a pre-requisite. The Finite Variance Scaling Method (FVSM), Higuchi method, rescaled range (R/S) and a generalized method have been applied to calculate the scaling exponents and fractal dimensions of the time series. Autocorrelation function (ACF) is used to find autoregressive (AR) process and Partial autocorrelation function (PACF) has been used to get the order of AR model. Finally a best fit model has been proposed using Yule-Walker Method with supporting results of goodness of fit and wavelet spectrum. The results reveal an anti-persistent, Short Range Dependent (SRD), self-similar property with signatures of non-causality, non-stationarity and nonlinearity in the data series. The model shows the best fit to the data under observation.     

Learning in an immersive digital theater

The Houston Museum of Natural Science, in collaboration with Rice University has an outreach program taking portable digital theaters to schools and community sites for over five years and has conducted research on student learning in this immersive environment. By using an external independent evaluator, the effectiveness of NASA-funded Education and Public Outreach (EPO) projects can be assessed. This paper documents interactive techniques and learning strategies in full-dome digital theaters. The presentation is divided into Evaluation Strategies and Results and Interactivity Strategies and Results. All learners from grades 3–12 showed statistically significant short-term increase in knowledge of basic Earth science concepts after a single 22-min show. Improvements were more significant on items that were taught using more than one modality of instruction: hearing, seeing, discussion, and immersion. Thus immersive theater can be an effective as well as engaging teaching method for Earth and Space science concepts, particularly those that are intrinsically three-dimensional and thus most effectively taught in an immersive environment. The portable system allows taking the educational experience to rural and tribal sites where the underserved students could not afford the time or expense to travel to museums.     

Development of a gas chromatography compatible Sample Processing System (SPS) for the in-situ analysis of refractory organic matter in martian soil: preliminary results

In the frame of the 2009 Mars Science Laboratory (MSL) mission a new sample preparation system (SPS) compatible with gas chromatography–mass spectrometry (GC–MS) has been developed for the in situ analysis of complex organic molecules in the Martian soil. The goal is to detect, if they exist, some of the key compounds that play an important role in life on Earth including carboxylic acids, amino acids and nucleobases.     

基于LuGre模型的电液加载系统摩擦补偿

为了提高电液加载系统控制精度,针对摩擦问题提出了基于LuGre摩擦模型的前馈补偿方法.建立了用于摩擦仿真分析和补偿器设计的电液加载系统数学模型;通过实验获取并分析了相关的摩擦数据;基于实验数据进行LuGre模型参数辨识,把LuGre模型和辨识结果引入电液加载系统数学模型,并进行仿真结果与实际摩擦数据的对照,证明了LuGre摩擦模型的准确性.设计前馈补偿器,进行了实验对比,实验结果表明前馈补偿器可将摩擦产生的控制误差有效地降至未补偿时的30%左右.      

CoRoT and Kepler results: Solar-like oscillators

The space-borne observatories CoRoT (Convection Rotation and planetary Transits) and Kepler have provided photometric time series data of unprecedented precision for large numbers of stars. These data have revolutionized the fields of transiting exoplanets and asteroseismology. In this review some important asteroseismic results obtained using data from the CoRoT and Kepler space missions concerning stars that show solar-like oscillations are discussed. These results comprise, among others, measurements of the location of the base of the convection zone and helium second-ionization zone in main-sequence stars, the presence (or not) of core-helium burning in red-giant stars, as well as differential rotation in these stars.     

Radioactivity of the Moon and planets

In this report the main results of the study of radioactivity of the solar sistem bodies are considered. The radioactivity of the Moon and planets was measured by means of vehicles in situ. The radioactivity of the lunar samples, brought to the Earth was studied with laboratory equipment.     

Return to Europa: Overview of the Jupiter Europa orbiter mission

Missions to explore Europa have been imagined ever since the Voyager mission first suggested that Europa was geologically very young. Subsequently, the Galileo spacecraft supplied fascinating new insights into this satellite of Jupiter. Now, an international team is proposing a return to the Jupiter system and Europa with the Europa Jupiter System Mission (EJSM). Currently, NASA and ESA are designing two orbiters that would explore the Jovian system and then each would settle into orbit around one of Jupiter’s icy satellites, Europa and Ganymede. In addition, the Japanese Aerospace eXploration Agency (JAXA) is considering a Jupiter magnetospheric orbiter and the Russian Space Agency is investigating a Europa lander.     

基于最小值原理的冗余度机器人动力学控制

为了解冗余度机器人全局法优化中数值求解的困难,本文讨论了动力学方程的建立,无约束和有约束最优控制问题之间的内在联系,重点分析了求解最优控制问题的数值方法,文中提出了双向异步积分迭代的求解正则方程组的直接迭代法,较好解决了状态方程和协态方程稳定相逆给求解两点这值问题带来的困难。     

基于GPS载波相位的微卫星姿态算法研究

GPS姿态系统是利用GPS载波相位测量来确定载体的航向和姿态角。本文对微卫星的GPS姿态系统进行了研究。重点解决短基线的GPS状态算法，讨论了姿态价格函数的了小化方法。测试结果表明，所提的算法对小于1m的基线是有效的。