稳态等离子体推力器磁场设计与数值分析

首先分析了稳态等离子体推力器性能对磁场的要求，据此介绍了磁路系统的工程设计原则和方法；然后，采用ANSYS大型有限元分析软件对一个具体的稳态等离子体推力器在额定工况下的磁场进行了计算，获得了满意的结果，通过对结果的分析获得了对有关现象的直观深入的认识，为所计算具体推力器的改进设计提供了线索；同时，也证实了以ANSYS为软件平台的稳态等离子体推力器磁路系统计算机数值仿真辅助设计的可行性和有效性。     

Characterization and Calibration of the CheMin Mineralogical Instrument on Mars Science Laboratory

A principal goal of the Mars Science Laboratory (MSL) rover Curiosity is to identify and characterize past habitable environments on Mars. Determination of the mineralogical and chemical composition of Martian rocks and soils constrains their formation and alteration pathways, providing information on climate and habitability through time. The CheMin X-ray diffraction (XRD) and X-ray fluorescence (XRF) instrument on MSL will return accurate mineralogical identifications and quantitative phase abundances for scooped soil samples and drilled rock powders collected at Gale Crater during Curiosity’s 1-Mars-year nominal mission. The instrument has a Co X-ray source and a cooled charge-coupled device (CCD) detector arranged in transmission geometry with the sample. CheMin’s angular range of 5^° to 50^° 2θ with <0.35^° 2θ resolution is sufficient to identify and quantify virtually all minerals. CheMin’s XRF requirement was descoped for technical and budgetary reasons. However, X-ray energy discrimination is still required to separate Co?Kα from Co?Kβ and Fe?Kα photons. The X-ray energy-dispersive histograms (EDH) returned along with XRD for instrument evaluation should be useful in identifying elements Z>13 that are contained in the sample. The CheMin XRD is equipped with internal chemical and mineralogical standards and 27 reusable sample cells with either Mylar^? or Kapton^? windows to accommodate acidic-to-basic environmental conditions. The CheMin flight model (FM) instrument will be calibrated utilizing analyses of common samples against a demonstration-model (DM) instrument and CheMin-like laboratory instruments. The samples include phyllosilicate and sulfate minerals that are expected at Gale crater on the basis of remote sensing observations.     

空间目标轨道确定专家系统

空间目标轨道确定专家系统的面向空间监测需求开发的大型交互式应用软件。它的功能面向空间监测和信息分析中广泛的业务需求，基础是轨道计算软件，数据库支持和一些辅助支持软件。本文详细地介绍了空间目标轨道确定专家系统软件的设计方案。     

Quasiperiodic oscillations of the sub-mHz band in near-sun plasma according to the coherent radio occultation data

In 2013 and 2015, investigations of the internal solar wind were carried out using the method of two-frequency radio sounding by signals from the Mars Express European spacecraft. The values of the S- and X-bands’ frequency and the differential frequency were registered with a sampling rate of 1s at the American and European networks of ground-based tracking stations. The spatial distribution of the frequency fluctuation’s level has been studied. It has been shown that the intensity of frequency fluctuation considerably decreases at high heliolatitudes. In some radio sounding sessions, quasiperiodic oscillations of sub-mHz band have been observed in the temporal spectra of frequency fluctuations; they are supposed to be associated with the density inhomogeneities, the sizes of which are close to the turbulence outer scale.     

Observational Aspects of Particle Acceleration in Large Solar Flares

Solar flares efficiently accelerate electrons to several tens of MeV and ions to 10 GeV. The acceleration is usually thought to be associated with magnetic reconnection occurring high in the corona, though a shock produced by the Coronal Mass Ejection (CME) associated with a flare can also accelerate particles. Diagnostic information comes from emission at the acceleration site, direct observations of Solar Energetic Particles (SEPs), and emission at radio wavelengths by escaping particles, but mostly from emission from the chromosphere produced when the energetic particles bombard the footpoints magnetically connected to the acceleration region. This paper provides a review of observations that bear upon the acceleration mechanism.     

多模式柔索驱动航天员训练机器人力控制

为解决长期在失重环境下生活和工作的航天员的康复训练问题,针对现有的航天员训练设备功能单一、训练效果不理想的现状,研制了多模式柔索驱动航天员训练机器人。基于模块化、可重构的机器人构型,通过机器人模拟重力环境的负载特征,把相应的载荷施加到人体上,实现航天员在失重环境下进行跑步、卧推和负重深蹲等体育训练,帮助航天员减轻或者克服空间适应综合征带来的不利影响;在此基础上提出一种机器人双闭环力控制策略,人机跑步训练实验结果表明,本文研制的多模式航天员训练机器人构型合理,控制策略有效,可以辅助在失重环境下生活和工作的航天员开展体育训练。     

BHM3碳纤维及其氰酸酯基复合材料耐原子氧侵蚀性能

利用原子氧暴露地面模拟实验装置,分别对BHM3型高模量碳纤维及其增强的氰酸酯基复合材料进行了原子氧暴露模拟实验,采用SEM、XRD、XPS技术分析了原子氧对碳纤维及其氰酸酯复合材料的侵蚀行为。结果表明,经过1×10 21 atoms/cm 2剂量的原子氧暴露后,碳纤维及其氰酸酯复合材料质量损失率均低于1%,纤维表面形貌及组成不变,碳纤维/氰酸酯复合材料的层间剪切强度降低16%。     

Deducing Electron Properties from Hard X-ray Observations

X-radiation from energetic electrons is the prime diagnostic of flare-accelerated electrons. The observed X-ray flux (and polarization state) is fundamentally a convolution of the cross-section for the hard X-ray emission process(es) in question with the electron distribution function, which is in turn a function of energy, direction, spatial location and time. To address the problems of particle propagation and acceleration one needs to infer as much information as possible on this electron distribution function, through a deconvolution of this fundamental relationship. This review presents recent progress toward this goal using spectroscopic, imaging and polarization measurements, primarily from the Reuven Ramaty High Energy Solar Spectroscopic Imager (RHESSI). Previous conclusions regarding the energy, angular (pitch angle) and spatial distributions of energetic electrons in solar flares are critically reviewed. We discuss the role and the observational evidence of several radiation processes: free-free electron-ion, free-free electron-electron, free-bound electron-ion, photoelectric absorption and Compton backscatter (albedo), using both spectroscopic and imaging techniques. This unprecedented quality of data allows for the first time inference of the angular distributions of the X-ray-emitting electrons and improved model-independent inference of electron energy spectra and emission measures of thermal plasma. Moreover, imaging spectroscopy has revealed hitherto unknown details of solar flare morphology and detailed spectroscopy of coronal, footpoint and extended sources in flaring regions. Additional attempts to measure hard X-ray polarization were not sufficient to put constraints on the degree of anisotropy of electrons, but point to the importance of obtaining good quality polarization data in the future.     

Tomographic reconstruction of the ionospheric electron density as a function of space and time

Electron density distribution is the major determining parameter of the ionosphere. Computerized Ionospheric Tomography (CIT) is a method to reconstruct ionospheric electron density image by computing Total Electron Content (TEC) values from the recorded Global Positioning Satellite System (GPS) signals. Due to the multi-scale variability of the ionosphere and inherent biases and errors in the computation of TEC, CIT constitutes an underdetermined ill-posed inverse problem. In this study, a novel Singular Value Decomposition (SVD) based CIT reconstruction technique is proposed for the imaging of electron density in both space (latitude, longitude, altitude) and time. The underlying model is obtained from International Reference Ionosphere (IRI) and the necessary measurements are obtained from earth based and satellite based GPS recordings. Based on the IRI-2007 model, a basis is formed by SVD for the required location and the time of interest. Selecting the first few basis vectors corresponding to the most significant singular values, the 3-D CIT is formulated as a weighted least squares estimation problem of the basis coefficients. By providing significant regularization to the tomographic inversion problem with limited projections, the proposed technique provides robust and reliable 3-D reconstructions of ionospheric electron density.