端面对轴线垂直度误差的解析评定法

建立了端面对轴线垂直度误差最小二乘和定向最小区域两种评定方法的数学模型，介绍了求解数学模型的数据处理方法，并给出了测量和数据处理实例。     

以相对偏差平方和为指标函数的最小二乘法

就测量中最小二乘法用于静态模型估计的问题,分析了传统最小二乘法在某些实验条件下应用的不合理现象,提出以相对偏差平方和为指标函数的最小二乘法。简记LSR法。给出了该方法的实用公式,分析了数学特征并证明在所给实验条件下具有无偏性、一致性,有效性.给出了用该方法拟合电位差计静态特性方程的例子。证明该方法在测量工作中是有实际意义的。     

1000兆赫≤f≤9400兆赫太阳射电流量与黑子数的关系

本文给出了9400、3750、2800、2000和1000兆赫太阳射电流量与黑子数的统计相关关系式,采用了最小二乘法、百分最小二乘法和复合最小二乘法三种处理方法.结果表明:百分最小二乘法得出的三次方程为最佳拟合关系式.由此得出的宁静太阳射电频谱与用射电干涉仪实测结果符合.      

最小二乘解的唯一性

从最小二乘方法的基本原理出发,用反证法证明了最小二乘解的唯一性,指出了求解过程中的注意事项,特别是病态矩阵的影响。     

卫星定位和精度因子的改进方法

在卫星导航定位系统中,在精度因子计算和采用最小二乘法进行定位求解时,传统上采用测量矩阵直接求逆方法来进行.为了克服矩阵求逆带来的计算量大和数值稳定性差的不足,利用测量矩阵的对称正定性,提出了一种基于矩阵 UTDU 分解的定位解算和精度因子计算方法.改进方法具有严格的数学理论基础,保证了方法的正确性和有效性.数值分析结果表明,相对直接求逆的传统方法而言,在定位解算时,该方法能降低约 60%的运算量,而在精度因子计算中,约能降低36%的运算量.且改进方法能大大降低求解矩阵的条件数,提高了求解的数值稳定性.      

二次代数多项式曲线拟合的一种简易求法——双斜率法

二次多项式曲线拟合是一种最简单的非线性拟合,在仪表、传感器及其元部件的标定试验数据处理中应用较广。使用最小二乘法进行二次多项式曲线拟合,其计算工作量较大,通常需要使用数字计算机和一套专用程序。正如在直线拟合中有一些平均法可用作最小二乘法的近似法一样,本文提出的简易方法也可做为二次多项式最小二乘法曲线拟合的一种近似方法,这种方法远较最小二乘法简单,也比二次插值法简单和优越。在要求中等拟合精度(1%量级)的情况下,用本方法所得结果比较按近最小二乘法的结果。     

五种圆柱度误差电算法的对比

本文简述了五种圆柱度误差的评定方法,(最小条件法、最小二乘法Ⅰ、最小二乘法Ⅱ、最小外接圆法(最大内切圆法,推导了计算公式,编了实用程序,并在 TQ—16机上进行了大量的验算,结果证明最小二乘法Ⅰ较复杂,计算量大,精度与最小二乘法Ⅱ差不多,所以用最小二乘法Ⅱ代替Ⅰ是完全可以的。其它几种方法也都比较简便实用,但各有特点,适应的场合也不同。     

直线度平面度测量平差的研究

为了减小节距法测量直线度和平面度时原始数据的不确定性误差 ,采用最小二乘平差理论解决了直线度测量平差的理论问题 ,并对平面度测量平差的方案进行了对比分析。通过大量实验验证了平差方法的有效性。对平直度测量标准的制定以及提高工程检测准确度有实际应用意义。     

基于补偿最小二乘的航天器轨道确定方法研究

航天器动力学模型误差是降低轨道确定精度的关键因素之一,文章将航天器动力学模型中的模型误差转化为测量模型的系统误差,建立了测量方程的部分线性模型;并根据补偿最小二乘原理,推导了部分线性模型参数估计方法,并证明了相关性质。仿真试验表明:部分线性模型更接近测量数据的真实表现;基于补偿最小二乘的航天器轨道改进方法能有效逼近航天器状态真值,定轨精度显著优于传统最小二乘估计。     

基于氧气A波段临近空间大气温度反演的贝叶斯与最小二乘法对比

基于氧气A波段的临边辐射模拟数据进行临近空间大气温度廓线的反演，分析比较了贝叶斯和最小二乘两种不同反演算法的特点.80km以下，信噪比为66～337时:基于贝叶斯理论反演的三条谱线761.59，762.2，764.05nm的反演误差平均值分别为5.52，3.94，4.73K；采用最小二乘法的反演误差平均值分别为10.57，7.04，8.80K.信噪比为6～34时:基于贝叶斯理论反演的三条谱线的反演误差平均值分别为18.27，12.18，18.27K；采用最小二乘法的反演误差平均值分别为103.18，68.79，85.98K.研究结果表明，基于贝叶斯理论的反演方法，利用先验信息对反演结果进行约束和修正，在有噪声的情况下获得了更合理的解，从而提高了反演精度和抗干扰能力.这为星载探测临近空间大气温度的算法研究和开发提供了参考，也为提高光谱仪器信噪比并进而提高温度反演精度提供了理论基础.      

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.     

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.     

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。