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681.
使用了一种处理大型复杂系统可靠性的Monte-Carlo模拟方法,即通过建立系统的故障树(FT)模型,采用直接模拟法随机模拟来获取系统的工作可靠度参量。特别当底事件(BE)为Non-Markov型分布时非常有效。最后,对某型号固体火箭发动机结构系统工作可靠性进行了仿真。 相似文献
682.
黄乡生 《南昌航空工业学院学报》1999,13(4):50-55,88
本文叙述了一个由微型可编程控制器IP-1612构成的温度测控系统,在介绍IP-11612PLC特性的基础上,讨论了用它构成温度测控系统的基本原理、电路结构和编程方法。最后提出有关PLC应用问题的几点看法。 相似文献
683.
Aerodynamic optimization and mechanism design of flexible variable camber trailing-edge flap 总被引:1,自引:0,他引:1
Trailing-edge flap is traditionally used to improve the takeoff and landing aerodynamic performance of aircraft.In order to improve flight efficiency during takeoff,cruise and landing states,the flexible variable camber trailing-edge flap is introduced,capable of changing its shape smoothly from 50% flap chord to the rear of the flap.Using a numerical simulation method for the case of the GA(W)-2 airfoil,the multi-objective optimization of the overlap,gap,deflection angle,and bending angle of the flap under takeoff and landing configurations is studied.The optimization results show that under takeoff configuration,the variable camber trailing-edge flap can increase lift coefficient by about 8% and lift-to-drag ratio by about 7% compared with the traditional flap at a takeoff angle of 8°.Under landing configuration,the flap can improve the lift coefficient at a stall angle of attack about 1.3%.Under cruise state,the flap helps to improve the lift-todrag ratio over a wide range of lift coefficients,and the maximum increment is about 30%.Finally,a corrugated structure–eccentric beam combination bending mechanism is introduced in this paper to bend the flap by rotating the eccentric beam. 相似文献
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Jiwon Seo Todd WalterPer Enge 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2011
Deep and frequent Global Positioning System (GPS) signal fading due to strong ionospheric scintillation is a major concern for GPS-guided aviation in equatorial areas during high solar activity. A GPS aviation receiver may lose carrier tracking lock under deep fading, and a lost channel cannot be used for position calculation until lock is reestablished. Hence, frequent loss of lock due to frequent fading can significantly reduce the availability of GPS aviation. However, the geometric diversity of the satellites can mitigate scintillation impact on GPS aviation depending on the correlation level of deep fades between satellites. This paper proposes a metric to measure the correlation level of two fading channels from the perspective of GPS aviation. Using this metric, the satellite-to-satellite correlation is studied based on real scintillation data. The low satellite-to-satellite correlation shown in this paper envisions notable availability benefit from the geometric diversity of satellites under strong scintillation. In addition, this paper proposes a way to generate correlated fading processes with arbitrary correlation coefficients. Using this correlated fading process model, the availability of Localizer Performance with Vertical guidance (LPV)-200 under severe scintillation scenarios is analyzed. The result emphasizes the importance of a fast reacquisition capability of an aviation receiver after a brief outage, which is not currently mandated by the aviation receiver performance standards. 相似文献
689.
刘振华 《长沙航空职业技术学院学报》2011,11(3):60-62
利用PHP和MYSQL技术开发设计在线学习考试系统,阐述系统的逻辑结构、开发环境、模块功能实现等,该系统能实现企业员工在线学习考试规范、准确、简捷、高效。 相似文献
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通过对复杂性科学系统中最具有生命力与活力的复杂性与适应性进行研究,力求探讨其本质及内涵;并且将其作用于区域规划与区域协调的层面,对于中心城市与周边城市的共同协调、可持续发展具有指导意义,并在此理论的指导下,引导都市圈规划走向良性、有序的发展道路。 相似文献