EUV emission from normal galaxies

Using data from the Wide Field Camera EUV all-sky survey, we have established upper limits to the EUV flux from a sample of 30 bright, nearby, non-active spiral galaxies. These galaxies were chosen to be those most likely to be detected in the EUV on the basis of (i) low interstellar absorption within our own galaxy, (ii) brightness in other wavebands, (iii) high star formation activity, and (iv) proximity. The derived EUV upper limits are restrictive, and establish for the first time that the EUV flux escaping from galaxies does not constitute a major component of their bolometric luminosity, and in particular that it cannot be the sink for the energy injected into the interstellar medium by supernova explosions, as had been suggested following the failure to detect this power in the X-ray band.     

基于DRFM的引信干扰技术研究

根据脉冲测距引信的工作原理和DRFM的基本功能,设计了DRFM结构,DRFM通过对脉冲延时,达到对脉冲测距引信进行干扰使其早炸的目的,并提出了延时参数的确定原则。     

A bistatic SAR mission for earth observation based on a small satellite

The authors present a new scientific space mission consisting of a satellite carrying a receiving- only SAR which receives the signal transmitted by the ENVISAT-1 SAR. The integration of ENVISAT-1 SAR and bistatic radar data offers an improved potentiality of surface classification, three-dimensional observation, and the opportunity of advanced scientific experiments in the field of bistatic scattering. The small satellite nominal orbit and the attitude manoeuvres are designed in order to maintain an adequate overlap between the two radar swaths along the whole orbit, taking into account the ENVISAT-1 attitude and pointing. A preliminary satellite design (2-year lifetime) is then performed to evaluate the orbit decay and to determine the appropriate orbit manoeuvres (every 4 days) to control the satellites relative phase. The numerical simulation shows that a spacecraft of about 584kg is able to meet the mission requirements.     

GPS based onboard and onground orbit operations for small satellites

In extension to common applications such as groundtrack displays and antenna steering, the SGP4 orbit model is proposed for operational orbit determination in small satellite missions. SGP4 is an analytical orbit model for Low-Earth orbiting satellites that is widely used for the propagation of NORAD twoline elements. Twoline elements may hence be generated completely independent of NORAD. Their use as exclusive source of orbital information simplifies the operations concept and reduces mission costs through the extensive use of existing low-cost mission support software. Due to small computer resource requirements of 8–10kByte, the SGP4 model may also be applied for onboard orbit computations making use of e.g. a 80186 processor, thus ensuring full compatibility of ground-based and onboard operations. The proposed approach is particularly suited in combination with a space-borne GPS receiver, were the C/A-code navigation solutions are treated as measurements that are adjusted in a least-squares sense using the SGP4 model. As consequence, inherent drawbacks of the pure navigation solutions such as data gaps and scatter as well as limited velocity accuracy are avoided, while the operational navigation activities are kept at a minimum. The feasibility of the concept is illustrated based on real GPS navigation data from the TOPEX/Poseidon and the MIR space station with an inherent data quality of 50–100 m. It is shown that 3 hours of data within a 4 day period are sufficient to keep the position error within 4 km, that is considered sufficient for most applications.     

k-ε-g紊流燃烧模型数值研究

本文对k-ε-g紊流燃烧模型中模型系数C_R,C_(g1),C_(g2)的选定和计算浓度脉动均方值g的不同方法进行数值研究。计算结果表明模型系数值的选定直接与化学反应速率有关,而其中C_R影响最大。g的计算虽然可有不同方法,而其中微分方程求解最佳。并用实验数据来验证计算结果。     

高职生数学学习倦怠的成因及对策

数学学习倦怠在职业院校学生是较为普遍地一个现象，这除了学生自身的有关原因外，数学教学自身也存在着许多有待改进的问题，树立学生学习信心，激发兴趣以及提高课堂教学艺术都是数学教师解决学生学习倦怠的有效办法。     

飞机主操纵系统疲劳试验载荷谱小操纵位移频次问题研究

针对飞机全机主操纵系统疲劳试验载荷谱中小操纵位移频次影响问题进行了分析和讨论,确定了某机全机主操纵系统小操纵位移频次的级别。同时,在原某机全机主操纵系统疲劳试验载荷谱的基础上再次对其小操纵位移频次进行了计算,去掉了这一级别以下对全机主操纵系统疲劳试验无影响的小操纵位移频次,从而完善了主操纵系统疲劳试验载荷谱。另外,对小操纵位移频次问题研究结果在其全机主操纵系统疲劳试验中的实施效果进行了阐述。     

如何为《飞机工程》撰写符合规范又有创新的论文

介绍了科技论文规范表达对收集、储存、处理、加工、检索、利用、交流和传播的作用，结合《飞机工程》投稿的实际，指出了作者在文字、标点、符号、图表、公式、量和单位表达中容易忽视和写错的一些技术细节，给出了科技论文规范表达的撰写格式，以及为《飞机工程》投稿时应注意的事项。     

H-6部件与外挂天平的研制

介绍了H 6部件与外扌圭物测力试验的难点 :一是天平的设计载荷极不匹配 ,如机翼天平的滚转力矩是常规天平的 1 0多倍 ;二是模型尾部是船形尾段。采用常规的支撑方式 ,支杆强度太弱 ,试验不安全 ,同时也不利于多台天平的敷线 ,总体方案采用模型尾部与支杆合为一体的结构形式 ,既保证了试验安全又便于多台天平的敷线。天平设计首先保证试验安全 ,用双电桥提高天平的输出。试验结果表明 :总体试验方案正确 ,天平设计合理 ,支撑刚度好 ,测量精度高。     

热惯性对热冲击半无限体热应力影响非傅立叶效应研究

考虑超快速加热引起传热过程的非傅立叶效应,基于线性热弹性理论和表面热惯性特性,建立了带惯性第一类边界条件的半无限体的动态温度场、热应力场方程组。用拉普拉斯变换法对方程组进行求解。结果表明,快速加热在半无限体内产生温度场和应力场,且热和应力呈波动输运机制。讨论了温升率或热惯性对半空间温度场和应力场的影响,比较弹性波波速与热波波速之比动态热应力的影响。