空客A320系列飞机空中自动驾驶失效分析

通过对一起A320飞机空中出现自动驾驶失效故障的排除,找出故障原因为起落架空地感应机构内部磨损,为类似故障的排除提供参考。     

一起波音737NG飞机自动驾驶接通后飞行高度波动的故障分析

简单介绍了波音737NG飞机自动驾驶俯仰控制的工作原理,并针对一起由于升降舵自动驾驶作动器失效导致飞机高度摆动故障的排故过程及故障原因进行分析,总结排故经验,为同行排除此类故障提供一些排故思路。     

岸舰导弹自动驾驶仪故障诊断模糊专家系统设计

快速准确排除岸舰导弹自动驾驶仪故障是提高部队技术保障能力的重要途径。文章结合模糊专家系统的发展,设计了用于对岸舰导弹自动驾驶仪进行自动故障排除的模糊专家故障诊断系统,介绍了系统的基本原理和结构体系。该系统结合了专家系统和模糊控制的优点,能实现在复杂战场环境下对故障的快速诊断和排除。     

巧用力学分析解除一起飞行控制系统疑难故障

由于波音737NG飞机的飞行控制系统故障率极低,因此相关的故障处理经验较少。针对一起波音737NG飞机飞行控制系统的机长侧驾驶盘转动至接近止动位时出现异响的这一疑难故障,详细阐述了采用物理力学分析方法排除该故障的过程,为类似故障的排除提供借鉴。     

波音777飞机过某些航路点不能自动转弯故障分析

针对某航空公司波音777飞机在自动驾驶和水平导航接通的情况下经过一些航路点时,飞机不能按照飞行计划自动转弯的故障进行了分析,找到了故障原因,并提出了解决故障的方法。     

飞机操纵"杆力重"故障分析

针对某型飞机驾驶杆纵向操纵最大杆力超规定故障,通过对操纵系统的组成和工作情况进行分析,找出影响因素,提出了解决该故障的方法及预防措施,为排除类似故障提供参考。     

浅谈自动驾驶系统的排故

本文结合飞机自动驾驶系统原理，记录和分析了一起左右通道自驾脱开的排故过程，对容易出现在老龄飞机上的线路故障有一定借鉴作用。     

浅谈AWAVRB-51D型DVOR设备边带缺口告警

本文结合我站DVOR设备实际情况阐述边带缺口告警而其它参数正常、设备自动换枫的故障现象及解决方法，并对故障原因进行分析，以便在今后的工作中更快、更好地排除此类故障。     

MD—82飞机空调系统自动关断的故障分析

本文着重从理论上分析导致ＭＤ８２飞机空调系统自动关断故障的各种可能性，主要从电路控制角度和气路控制角度加以论述；同时引进可以较为简单地排除空调系统自动关断故障的一系列逻辑方法和科学程序。这些方法程序已通过实践证明是非常奏效的，对飞机维护和十分有助。     

航向姿态参考系统磁航向误差偏大故障分析

航向姿态参考系统是飞机上用于测量、计算和提供飞行姿态及航向信息的重要仪表,其指示精度直接影响着飞行员的驾驶操纵和自动驾驶仪的性能。针对某型航向姿态参考系统在测试过程中出现的磁航向误差偏大故障,从理论上对该系统进行机理分析,建立故障树,通过实地操作检测,对底事件进行逐一分析,筛查问题原因,对故障进行定位和排除。结果表明：航向姿态参考系统出现的磁航向误差偏大故障的原因是采用GPS信号修正输出值时混淆了变量含义,在磁航向解算算法的设计上不够严谨,导致误差较大,采用故障树分析方法能够成功定位和排查该故障。     

The effect of inlet conditions on the flow and heat transfer in multiple rotating cavity with axial throughflow

This paper discusses experimental results from two different build configurations of a heated multiple rotating cavity test rig.Measurements of heat transfer from the discs and tangential velocities are presented.The test rig is a 70% full scale version of a high pressure compressor stack of an axial gas turbine engine.Of particular interest are the internal cylindrical cavities formed by adjacent discs and the interaction of these with a central axial throughflow of cooling air.Tests were carried out for a range of non-dimensional parameters representative of high pressure compressor internal air system flows(Re up to 5×106 and Rez up to 2×105).Two different builds have been tested.The most significant difference between these two build configurations is the size of the annular gap between the(non-rotating) drive shaft and the bores of the discs.The heat transfer data were obtained from thermocouple measurements of surface temperature and a conduction solution method.The velocity measurements were made using a two component,LDA system.The heat transfer results from the discs show differences between the two builds.This is attributed to the wider annular gap allowing more of the throughflow to penetrate into the cavity.There are also significant differences between the radial distributions of tangential velocity in the two builds of the test rig.For the narrow annular gap,there is an increase of non-dimensional tangential velocity V/Ωr with radial location to solid body rotation V/Ωr=1.For the wider annular gap,the non-dimensional velocities show a decrease with radial location to solid body rotation.      

Research on Auto-detection for Remainder Particles of Aerospace Relay Based on Wavelet Analysis

Aerospace relay is one kind of electronic components which is used widely in national defense system and aerospace system. The existence of remainder particles induces the reliability declining, which has become a severe problem in the development of aerospace relay. Traditional particle impact noise detection (PIND) method for remainder detection is ineffective for small particles, due to its low precision and involvement of subjective factors. An auto-detection method for PIND output signals is proposed in this paper, which is based on direct wavelet de-noising (DWD), cross-correlation analysis (CCA) and homo-filtering (HF), the method enhances the affectiv-ity of PIND test about the small particles. In the end, some practical PIND output signals are analysed, and the validity of this new method is proved.     

Preparation of Highly Dispersed Antimony-doped Tin Oxide Nano-powder via Ion-exchange Hydrolysis of SnCl4 and SbCl3 and Azeotropic Drying

Antimony-doped tin hydroxide colloid precipitates have been synthesized by hydrolysis of SnCl4 and SbCl3 using: (1) an ion-exchange hydrolysis to remove chlorine ions, and (2) isoamyl acetate as an azeotropic solvent to obviate water. The obtained dried powder is of high dispersivity without any need for further grinding. The size and dispersivity of the final particles are investigated with the aid of TG-DTA, BET, XRD and TEM. After having calcined, the antimony-doped tin oxide nanopowder possesses a tetragonal rutile structure with high dispersivity, uniform particles and low hard agglomeration.     

Effects of Mo on the Microstructure and Hydrogen Sorption Properties of Ti-Mo Getters

The effects of Mo on the microstructure evolution, porosity and hydrogen sorption properties of Ti-Mo getters are investigated in this work. The results show that the addition of Mo prolongs the densification process of Ti-Mo getters and results in a significant amount of sintered pores. With the Mo content increasing, the porosity of getters firstly increases reaching the maximum value as it at- tains about 7.5wt.%, and then drops. At the room temperature, the hydrogen sorption property of getters increases progressively with the Mo content increasing, but the tendency is not very clear before its content lies below 2.5wt.%. When the Mo content achieves about 7.5wt.%, the hydrogen sorption property proves to be the best. The discussion is made about the above mentioned phenomena inclusive of hydrogen sorption properties of getters under different activation conditions (from 500-750 ℃).     

超声速燃烧数值模拟中的湍流与化学反应相互作用模型

高精度数值模拟有助于理解超声速湍流燃烧中湍流与化学反应的相互作用,可为发动机燃烧室等工程应用设计提供可靠的预测模型。除直接数值模拟外,目前在湍流燃烧应用中使用的大涡模拟和雷诺平均Navier-Stokes模拟均需要借助模型模化发生在湍流小尺度上的流动与化学反应过程对湍流大尺度运动的影响。现有的湍流与化学反应相互作用模型大致可分为:火焰面类模型和概率密度函数类模型,2类模型在不同的应用中各自具有优势和局限性。此外,现有模型大都基于低马赫数燃烧,而超声速燃烧中通常会伴随快速混合、局部熄火和再着火以及激波等复杂过程,这为发展其中的湍流与化学反应相互作用模型提出了更多的挑战。     

适于低轨卫星IP网络的单核共享树组播算法(英文)

为了解决低轨卫星IP网络中现有典型源组播算法的信道资源浪费问题,本文提出了一套单核共享树组播算法,即核心群合并共享树(CCST)和加权核心群合并共享树(w-CCST)算法。CCST 算法包括动态近似中心(DAC)选核方法和核心群合并组播路径构建方法。DAC方法专为周期、规律运动的低轨卫星网络提出,不需要复杂的星上计算。在核心群合并方法中,以核节点作为初始核心群,通过核心群和剩余组成员的最短路径方法逐步扩展直至整棵组播树构建完成,从而使得组播树的树代价最小,大大提高了网络的带宽利用率和组播传输效率。w-CCST 算法中所提出的加权因子可以调整树代价和端到端传播时延之间的折衷程度,因此,可以通过调整加权因子来适度增大树代价、降低端到端传播时延以支持某些端到端时延要求苛刻的实时组播业务。最后,与低轨卫星 IP 网络中典型算法进行了性能比较,仿真结果说明,CCST 算法的平均树代价比其它算法显著降低,w-CCST 算法的平均端到端传播时延小于 CCST 算法。     

Jet Vectoring Control Using a Novel Synthetic Jet Actuator

A primary air jet vectoring control system with a novel synthetic jet actuator (SJA) is presented and simulated numerically. The results show that, in comparison with an existing traditional synthetic jet actuator, which is able to perform the duty of either “push” or “pull”, one novel synthetic jet actuator can fulfill both “push” and “pull” functions to vector the primary jet by shifting a slide block inside it. Therefore, because the new actuator possesses greater efficiency, it has potentiality to replace the existing one in various appli- cations, such as thrust vectoring and the reduction of thermal signature. Moreover, as the novel actuator can fulfill those functions that the existing one can not, it may well be expected to popularize it into more flow control systems.     

Nonlinear Adaptive Slewing Motion Control of Spacecraft Truss Driven by Synchronous V-gimbaled CMG Precession

The slewing motion control of a truss arm driven by a V-gimbaled control-moment-gyro (CMG) is a nonlinear control problem. The V-gimbaled CMG consists of a pair of gyros that must precess synchronously. The moment of inertia of the system, the angular momentum of the gyros and the external disturbances are not exactly known. With the help of feedback linearization and recursive Lyapunov design method, an adaptive nonlinear controller is designed to deal with the unknown items. Performance of the proposed controller is verified by simulation.     

An SOR Implicit Time-accurate Scheme in Calculating Unsteady Flows

A new time-accurate marching scheme for unsteady flow calculations is proposed in the present work. This method is the combination of classical Successive Over-Relaxation (SOR) iteration method and Jacobian matrix diagonally dominant splitting method of LUSGS. One advantage of this algorithm is the second-order accuracy because of no factorization error. Another advantage is the low computational cost because the Jacobian matrices and fluxes are only calculated once in each physical time step. And, the SOR algorithm has better convergence property than Gauss-Seidel. To investigate its accuracy and convergency, several unsteady flow computa- tional tests are carried out by using the proposed SOR algorithm. Roe’s FDS scheme is used to discritize the inviscid flux terms. Un- steady computational results of SOR are compared with the experiment results and those of Gauss-Seidel. Results reveal that the numerical results agree well with the experimental data and the second-order accuracy can be obtained as the Gauss-Seidel for unsteady flow computations. The impact of SOR factor is investigated for unsteady computations by using different SOR factors in this algorithm to simulate each computational test. Different numbers of inner iterations are needed to converge to the same criterion for different SOR factors and optimal choice of SOR factor can improve the computational efficiency greatly.