LD10网格加强肋结构壁板的化学铣切工艺研究

为了寻找到化铣槽液各组分的最佳含量范围,使零件达到稳定化铣侧切率,减少板材铣切厚度差,本研究通过测量对比试片在各组分含量的槽液中铣切壁板的侧切率和均匀度参数来实现.结果表明,当NaOH初始浓度为200 g/L、溶解Al3+为70～110 g/L、温度(90±5)℃的技术条件下能够得到肋条偏差Tw±0.75 mm、壁厚偏差Ts±0.15 mm的较理想的化铣产品.     

Ceramic ChemCam Calibration Targets on Mars Science Laboratory

The ChemCam instrument on the Mars Science Laboratory rover Curiosity will use laser-induced breakdown spectroscopy (LIBS) to analyze major and minor element chemistry from sub-millimeter spot sizes, at ranges of ～1.5–7?m. To interpret the emission spectra obtained, ten calibration standards will be carried on the rover deck. Graphite, Ti?metal, and four glasses of igneous composition provide primary, homogeneous calibration targets for the laser. Four granular ceramic targets have been added to provide compositions closer to soils and sedimentary materials like those expected at the Gale Crater field site on Mars. Components used in making these ceramics include basalt, evaporite, and phyllosilicate materials that approximate the chemical compositions of detrital and authigenic constituents of clastic and evaporite sediments, including the elevated sulfate contents present in many Mars sediments and soils. Powdered components were sintered at low temperature (800?°C) with a small amount (9?wt.%) of lithium tetraborate flux to produce ceramics that retain volatile sulfur yet are durable enough for the mission. The ceramic targets are more heterogeneous than the pure element and homogenous glass standards but they provide standards with compositions more similar to the sedimentary rocks that will be Curiosity’s prime targets at Gale Crater.     

碳纤维表面微观结构的定量化表征方法

通过使用Matlab编程处理日本东丽T300、国产GCF-1和GCF-2等3种碳纤维样品断面的扫描电镜照片,采用二值标签算法获得了碳纤维的直径及圆度等碳纤维物理特征定量数据。建立了采用直线方程切线法寻找并计算碳纤维表面沟槽的数量及尺度的方法,发现3种碳纤维样品的边缘沟槽的深度及宽度的分布均符合Weibull分布的特征。3种碳纤维的表面物理特征随温度变化的规律相同,说明其在结构上存在着一致性。经过不同温度热处理后3种碳纤维样品的圆度值变化不大,平均直径随着热处理温度的升高逐渐减小,并且表面沟槽的数量及分布的变化规律相同,说明其结构存在一致性。3种碳纤维的圆度等表面物理特征存在一定差异,T300的圆度小于国产GCF-1及GCF-2碳纤维。     

用高速摄像系统测量桨尖运动轨迹

本文通过介绍用高速摄像系统测量桨尖运动轨迹的原理和实施,来展望该系统的应用以及一种测量桨叶变形的新方法。     

Solar Wind Electron Proton Alpha Monitor (SWEPAM) for the Advanced Composition Explorer

The Solar Wind Electron Proton Alpha Monitor (SWEPAM) experiment provides the bulk solar wind observations for the Advanced Composition Explorer (ACE). These observations provide the context for elemental and isotopic composition measurements made on ACE as well as allowing the direct examination of numerous solar wind phenomena such as coronal mass ejections, interplanetary shocks, and solar wind fine structure, with advanced, 3-D plasma instrumentation. They also provide an ideal data set for both heliospheric and magnetospheric multi-spacecraft studies where they can be used in conjunction with other, simultaneous observations from spacecraft such as Ulysses. The SWEPAM observations are made simultaneously with independent electron and ion instruments. In order to save costs for the ACE project, we recycled the flight spares from the joint NASA/ESA Ulysses mission. Both instruments have undergone selective refurbishment as well as modernization and modifications required to meet the ACE mission and spacecraft accommodation requirements. Both incorporate electrostatic analyzers whose fan-shaped fields of view sweep out all pertinent look directions as the spacecraft spins. Enhancements in the SWEPAM instruments from their original forms as Ulysses spare instruments include (1) a factor of 16 increase in the accumulation interval (and hence sensitivity) for high energy, halo electrons; (2) halving of the effective ion-detecting CEM spacing from ∼5° on Ulysses to ∼2.5° for ACE; and (3) the inclusion of a 20° conical swath of enhanced sensitivity coverage in order to measure suprathermal ions outside of the solar wind beam. New control electronics and programming provide for 64-s resolution of the full electron and ion distribution functions and cull out a subset of these observations for continuous real-time telemetry for space weather purposes. This revised version was published online in June 2006 with corrections to the Cover Date.     

Ionization processes in the heliosphere — Rates and methods of their determination

The rates of the most important ionization processes acting in interplanetary space on interstellar H, He, C, O, Ne and Ar atoms are critically reviewed in the paper. Their long-term modulations in the period 1974 – 1994 are reexamined using updated information on relevant cross-sections as well as direct or indirect data on variations of the solar wind/solar EUV fluxes based on IMP 8 measurements and monitoring of the solar 10.7 cm radio emission. It is shown that solar cycle related variations are pronounced (factor of 3 between maximum and minimum) especially for species such as He, Ne, C for which photoionization is the dominant loss process. Species sensitive primarily to the charge-exchange (as H) show only moderate fluctuations 20% around average. It is also demonstrated that new techniques that make use of simultaneous observations of neutral He atoms on direct and indirect orbits, or simultaneous measurements of He⁺ and He⁺⁺ pickup ions and solar wind particles can be useful tools for narrowing the uncertainties of the He photoionization rate caused by insufficient knowledge of the solar EUV flux and its variations.     

对转双旋流气动喷嘴出口后流场结构的实验研究

研究了相互逆转双族流气动喷嘴出口后喷雾的流场结构。实验中采用粒子动态分析仪（ＰＤＡ）对喷嘴出口后冷态流场结构进行了测量，给出了平均速度以及瞬时脉动均方根速度的分布情况。结果表明：对转双族流气动喷嘴出口后流场可分为初始的掺混段和后来的扩散段两个阶段，在此两阶段，流场结构存在很大差异。     

断续 CBN 砂轮缓进给磨削 K417 航空叶片材料的研究

 全面比较了用Al2O3和CBN磨削K417铸造高温合金时的磨削效果，指出：Al2O3不适于高效磨削K417之类的航空难加工材料，而CBN是实现该材料高效深切磨削的有效工具。通过大量实验，验证了断续CBN砂轮缓进给磨削K417时的技术优势，解决了树脂结合剂应用于断续磨削时所遇到的新问题。分析显示出该技术具有很好的应用前景和极大的推广价值。     

机敏支撑结构的振动主动控制

 机敏结构是具有传感和执行双重功能的结构形式，无需外界帮助可自适应调节其状态。通过机敏结构建立了三维支撑结构的振动主动控制系统，利用Hamilton原理和变分法中的Euler公式导出了压电机敏结构的离散控制方程，采用加速度反馈实现了支架的振动主动控制。     

非定常风洞壁压特性研究

在低速风洞中用2组后掠角分别为70°和65°的三角翼模型进行过失速非定常运动,测量风洞洞壁上非定常壁压。研究风洞非定常壁压的延迟与频率特性。讨论了模型尺寸、缩减频率、前缘后掠角等对风洞非定常壁压的影响。