Atomic Physics for Atmospheric Composition Measurements

The atomic physics relevant to the interpretation of solar spectra produced by plasmas at temperatures ≳ 105 K are discussed. Methods for determining relative abundance ratios are presented and examples provided from the Coronal Diagnostic Spectrometer on board SOHO. In particular, the Fe/Si ratio in the corona is found to be close to photospheric; the Mg/Ne ratio in the transition region is found to vary by an order of magnitude in different solar features. The Mg/Ne ratios in supergranule cell centres and the network are separated for the first time, although no significant differences are found. This revised version was published online in June 2006 with corrections to the Cover Date.     

机载适航标准DO-178B/C软件开发过程研究

介绍了DO-178B/C标准的发展历程,结合对DO-178B/C标准机载软件生命周期过程的研究,分析了机载软件开发过程需求、设计、编码和集成子过程的关系及输入输出数据,在分析机载软件需求、设计、编码及集成子过程的目标、活动和转换准则的基础上,给出了各子过程的过程模型.展望了DO-178B/C标准的未来研究方向.     

韧性材料的冲蚀损伤数值仿真综述

砂尘造成韧性材料的冲蚀损伤现象和损伤演化规律是冲蚀机理研究的重要内容，基于相应冲蚀试验和数值仿真的分析 方法是揭示冲蚀机理的重要手段。回顾了砂尘冲蚀损伤研究的缘起和发展经历，在介绍砂尘冲蚀损伤机理的基础上，总结了当前 数值仿真研究的3种主流方法：有限元方法、无网格方法和计算流体动力学方法。从数值仿真角度针对砂尘对韧性材料造成的破 坏模式、砂尘冲击姿态、砂尘冲击速度和形状、砂尘破碎对材料去除机制的影响等4个方面综述了影响冲蚀损伤机理的主要因素 和当前研究进展。砂尘对韧性材料造成的破坏模式通常分为材料凹陷、滑动、犁削、切削等4种不同机制；砂尘的冲击姿态决定了 材料的损伤模式；砂尘的冲击速度和砂尘的形状决定了材料的损伤严重程度；砂尘破碎现象对材料的去除机制有一定影响。     

UVCS/SOHO Observations of H I Lyman Alpha Line Profiles in Coronal Holes at Heliocentric Heights Above 3.0 R⊙

The Ultraviolet Coronagraph Spectrometer (UVCS) on the Solar and Heliospheric Observatory (SOHO) has been used to measure spectral line profiles for H I Lyα in the south polar coronal hole at projected heliocentric heights from 3.5 to 6.0 R_⊙ during 1998 January 5–11. Observations from 1.5 to 2.5 R_⊙ were made for comparison. The H I Lyα profile is the only one observable with UVCS above 3.5 R_⊙ in coronal holes. Within this region the outflowing coronal plasma becomes nearly collisionless and the ionization balance is believed to become frozen. In this paper, the 1/e half widths of the coronal velocity distributions are provided for the observed heights. The velocity distributions include all motions contributing to the velocities along the line of sight (LOS). The observations have been corrected for instrumental effects and interplanetary H I Lyα. The half widths were found to increase with projected heliographic height from 1.5 to 2.5 R_⊙ and decrease with height from 3.5 to 5 R_⊙. This revised version was published online in June 2006 with corrections to the Cover Date.     

产品设计以三维实体建模为基础，建立单一数据源，实现企业级信息集成——关于进一步推进CAD／CAM技术应用的意见

从总结洪都航空工业集团10年来在普及计算机应用和推进企业数字化信息系统建立方面取得长足进展人笔，论述了该集团公司计算机应用和信息管理工作必须从产品设计三维实体建模数字化抓起。建立单一数据源，实现以产品为对象的企业级信息集成管理。     

后掠翼身交接区流动结构及参数影响研究

在水槽中利用激光片光源及荧光素钠染色液显示方法 ,研究了圆柱、机翼与平板交接区及后掠圆柱、后掠机翼变迎角情况下的干扰流场结构、特性及参数影响规律。结果表明 ,除Re数之外模型迎角、后掠角等参数对干扰区马蹄涡特性有很大影响。研究发现后掠圆柱及后掠机翼在一定条件下存在一类既不同于马蹄涡也不同于卡门涡的空间稳定发展的三维旋涡系即背涡。讨论了干扰背涡产生的机制及其与马蹄涡的相互关系。     

求解最小费用最大流问题的一种方法

介绍了最大流问题的多解，提出了通过调整圈来求解最小费用最大流的方法。     

Be／X射线双星LSI＋61°303的光谱研究

给出了１９９２－１９９５年Ｂｅ／Ｘ射线双星ＬＳＩ＋６１°３０３每年的光谱观测结果，分析了光谱发射线轮廓及其变化，观测显示Ｈβ发射线轮廓具有典型的气壳吸收，表明观测视线与Ｂｅ星赤道平面平行，同时发现Ｈα发射线参数发等值宽度和双峰强度之比也具有类似射电流量的周期性变化，但其变化与射电玫光学光度的变化不同，因此认为此变化可能与中子星周期的吸积盘及其轨道交食有关。     

信息化制造技术在航天制造企业的应用

结合企业在实际生产中综合运用CAD/CAM/DNC系统完成曲面工件的加工实例,介绍了CAD/CAM/DNC系统在信息化制造过程中各自起的作用,以及通过综合运用对企业信息化制造和企业制造技术所产生的影响。     

High-efficiency aircraft antiskid brake control algorithm via runway condition identification based on an on-off valve array

The aircraft antiskid braking system is an important hydraulic system for preventing tire bursts and ensuring safe take-off and landing. The brake system adjusts the force applied on the brake discs by controlling the brake pressure. Traditional aircraft antiskid braking systems achieve antiskid performance by controlling the braking pressure with an electrohydraulic servo valve. Because the pilot stage of an electrohydraulic servo valve is easily blocked by carbonized hydraulic oil, the servo valve would become a dangerous weak point for aircraft safety. This paper proposes a new approach that uses an on-off valve array to replace the servo valve for pressure control. Based on this new pressure control component, an efficient antiskid control algorithm that can utilize this discontinuous feature is proposed. Furthermore, the algorithm has the ability to identify the runway circumstances. To overcome the discontinuity in the process of using an on-off valve array, the Filippov framework is introduced. The conditions of convergence of the system are also discussed. The results of the digital simulations and the hardware-in-the-loop (HIL) braking experiments are used to verify the efficiency and stability of the proposed control algorithm. The method also proves that the on-off valve array can replace the servo valve perfectly as a new type of antiskid braking pressure control component.