退化量有缺失的无失效小样本轴承可靠性评估

针对有试验性能退化量参数记录、且(或)有部分数据缺失情况的小样本无失效轴承试验问题,通过由Taylor和Thompson提出的数据模拟法实现补全样本退化量,结合Bootstrap自助法扩大样本量,再根据基于性能退化轨迹的补充信息方法来进行其可靠性评估。选取7组受试轴承的振动退化量,对比在完整数据和带有缺失数据情况下的分析结果,发现可合理利用原舍弃不合规试验的部分有效信息,使之增加可靠性评估的样本数,从而得到较不用这些数据更为准确的结果,且所得结果较用完整数据结果绝对值相差在01以内。对比由极大似然估计法和加权E-Bayes法分析试验寿命数据的结果,发现该方法所得评估结果更优,与试验实际相比误差在10%以内,对于提高评估精度及降低试验成本有积极的实际意义。     

基于I~2C总线的CPU温度监控系统

随着高性能、高功耗器件在嵌入式领域中广泛应用,温度监控已成为高可靠嵌入式领域研究的热点,采用ADI公司的测温电路ADT7461设计了面向高性能PowerPC处理器的温度监控系统。介绍了ADT7461芯片的功能原理,描述了整个硬件电路的结构。在软件部分阐述了I2C总线协议以及基于I2C总线协议实现的ADT7461寄存器读/写基本操作,针对应用中会面临的实际问题给出了具体解决方法。设计方法对于同类温度监控系统设计有一定的参考意义。     

细长杆降低超声速客机气动噪声的数值分析

在超声速客机机头加装适当的细长杆可以降低飞行噪声。本文借助基于AUSM+格式的准三维数值模拟手段对7组13种细长杆方案做了分析比较,总结出了近场气体参数与远场气体参数之间的关系的规律。文章还从气体动力学理论和激波理论出发,对数值模拟结果作了解释,并揭示了细长杆降噪效果与细长杆外形的内在联系,以及近场、远场两者关系的经验公式。文章从各种方案中选取了降噪效果较好的细长杆方案做三维流场分析,并通过流固耦合计算对其结构强度做了校核,验证了方案的可行性。     

提高航班签派或放行中的天气评估能力

在实际航班运行中,导致返航备降的各类原因里,天气因素占首位,因此,为保证航班安全、正常地运行,飞行签派员务必在航班签派或放行中做好天气的评估工作。     

小波技术在组合导航系统故障诊断中的应用

针对组合导航系统中存在的故障类型和特点，提出一种新的基于信号处理的故障检测方法。该方法利用小波分析技术对含有故障信息的系统信号进行分析处理，并将此方法应用于SINS／GPS组合导航系统。仿真结果分析表明，小波分析技术能很好地及时检测出组合导航系统的硬故障，且更加简便灵活，从而可以将小波分析技术应用于组合导航系统的故障检测。     

Experimental investigation and correlation development of jet impingement heat transfer with two rows of aligned jet holes on an internal surface of a wing leading edge

Extensive experimental studies on the heat transfer characteristics of two rows of aligned jet holes impinging on a concave surface in a wing leading edge were conducted, where50000 Rej 90000, 1.74 H/d 27.5, 66° a 90°, and 13.2 r/d 42.03. The finding was that the heat transfer performance at the jet-impingement stagnation point with two rows of aligned jet holes was the same as that with a single row of jet holes or the middle row of three-row configurations when the circumferential angle of the two jet holes was larger than 30°. The attenuation coefficient distribution of the jet impingement heat transfer in the chordwise direction was so complicated that two zones were divided for a better analysis. It indicated that: the attenuation coefficient curve in the jet impingement zone exhibited an approximate upside-down bell shape with double peaks and a single valley; the attenuation coefficient curve in the non-jet impingement zone was like a half-bell shape, which was similar to that with three rows of aligned jet holes; the factors,including Rej, H/d and r/d, affected the attenuation coefficient value at the valley significantly.When r/d was increased from 30.75 to 42.03, the attenuation rates of attenuation coefficient increased only by 1.8%. Consequently, experimental data-based correlation equations of the Nusselt number for the heat transfer at the jet-impingement stagnation point and the distributionof the attenuation coefficient in the chordwise direction were acquired, which play an important role in designing the wing leading edge anti-icing system with two rows of aligned jet holes.     

航天软件中多重中断程序的动态检测方法研究

随着控制系统软硬件平台的设计复杂度不断增加,特别是飞行控制系统中集成的传感器不断增多,中断数量也随之不断增加.本文根据飞控系统的具体特点,使用标记迁移系统对多重中断并发程序进行建模,提出了原子性违背和数据竞争的形式化描述,运用动态偏序化简算法对程序的状态空间进行化简,并设计实现了多重中断控制系统程序的动态检测工具,实验结果表明该检测算法可以在满足对多重中断并发程序错误检测的基础上,大大的缩短检测时间.     

10 Differences between Shenzhou 8 and Shenzhou 9 Missions

Generally, the Shenzhou 8 and Shenzhou 9 spaceships were similar in technology status. As the Shenzhou 9 spaceship implemented the manned rendezvous and docking mission, the program was appropriately modified. There are 10 primary differences between the two missions.