共查询到20条相似文献,搜索用时 62 毫秒
1.
2.
鉴于传统故障诊断技术在飞机发动机故障诊断中不能较好吸收人类经验的缺点,文章运用模糊推理技术,模拟专家的故障诊断推理过程,建立了某型军用飞机发动机转速摆动故障的模糊故障诊断模型,并运用模糊神经网络对该模型进行了改进。仿真结果表明,所建立的模型可以很好地吸收维护人员的故障诊断经验,对故障原因可做出准确判断,训练完成的模糊神经网络模型可实现模糊模型的故障诊断功能,解决其不能自学习的问题。 相似文献
3.
4.
针对航空发动机故障诊断的实际问题,给出了模糊Petri 网的定义,同时在各类模糊式规则的基础上,建立了故障诊断
推理方法及故障原因判断准则。通过对航空发动机滑油系统最小滑油压力信号灯燃亮故障的实例分析,将Delphi 法与模糊Petri
网结合,综合2 种方法的优势,采用反向故障诊断,用Delphi 法计算出所有可能的故障原因的置信度,验证了Delphi- 模糊Petri
网在故障诊断方面的有效性与所建立模型的可行性,为航空发动机的故障定位与故障原因推理提供了1种可行方法。 相似文献
5.
通过分析测试设备故障诊断专家系统的目的和任务,将模糊神经网络理论与专家系统结合后用于测试设备故障诊断,建立了故障诊断专家系统的模型。探讨了故障诊断专家系统中知识库的构建及维护、不精确推理等问题。用面向对象分析方法分析测试设备故障诊断专家系统,并用软件加以实现。 相似文献
6.
7.
针对纯定性SDG(Signed Directed Graph,符号有向图)模型的诊断方法因定量知识的缺失导致虚假解多、分辨率低的问题,将SDG定性模型与定量知识相结合,通过在定性模型中加入模糊隶属度与模糊相容度等定量知识,形成了定性定量集成模式的FSDG(Fussy Signed Directed Graph,模糊符号有向图)深层知识模型;并在此基础上,提出一种基于定性定量知识集成模式的故障诊断方法;最后应用该方法建立了某测站下行信道系统的FSDG诊断模型,并进行了故障诊断仿真.结果表明:该方法有效提高了诊断分辨率,具有诊断结果完备、准确性高的优点. 相似文献
8.
9.
在剖析航空装备故障诊断特点的基础上,提出了基于模糊神经网络的航空装备故障诊断专家系统框架结构,并阐明了专家系统和模糊神经网络相结合的推理机制、模糊神经网络生成方法、知识获取和自学习等关键技术.系统框架的提出为航空装备故障诊断研究提出了新的思路. 相似文献
10.
为减小航空发动机多工况的工作特性和分布式控制系统非线性网络环境对故障诊断系统的影响,针对航空发动机分布式控制系统,提出一种基于T-S模糊KPCA模型的传感器故障诊断方法。首先采用C均值模糊聚类法,以油门杆角度为样本标签,对样本空间进行模糊分类,再通过模糊相似矩阵剔除各样本子空间的野值点;其次建立标称工况的KPCA模型,并利用训练样本对非标称工况的隶属度函数进行辨识,得到全工况T-S模糊KPCA模型;最后利用统计量T 2和SPE对传感器故障进行检测,并采用数据重构方法对故障传感器进行隔离定位。仿真结果表明该方法对发动机的任意稳定工况具有自适应能力,能够在非线性网络环境下对正常样本和故障样本保持较低的虚警率和漏报率。当多个传感器同时发生故障时,能够准确找到故障源,实现对故障传感器的隔离。 相似文献
11.
The effect of inlet conditions on the flow and heat transfer in multiple rotating cavity with axial throughflow 总被引:1,自引:0,他引:1
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. 相似文献
12.
Research on Auto-detection for Remainder Particles of Aerospace Relay Based on Wavelet Analysis 总被引:2,自引:0,他引:2
GAO Hong-liang ZHANG Hui WANG Shu-juan 《中国航空学报》2007,20(1):75-80
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. 相似文献
13.
14.
YANG Fen ZHANG Xue-jun TIAN Fang WU Xu GAN Fu-xing 《中国航空学报》2007,20(2):181-186
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. 相似文献
15.
Effects of Mo on the Microstructure and Hydrogen Sorption Properties of Ti-Mo Getters 总被引:1,自引:0,他引:1
ZHOU Hong-guo WEI Xiu-ying MAO Chang-hui XIONG Yu-hua QIN Guang-rong 《中国航空学报》2007,20(2):172-176
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 ℃). 相似文献
16.
超声速燃烧数值模拟中的湍流与化学反应相互作用模型 总被引:1,自引:0,他引:1
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。 相似文献
17.
适于低轨卫星IP网络的单核共享树组播算法(英文) 总被引:1,自引:0,他引:1
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。 相似文献
18.
Jet Vectoring Control Using a Novel Synthetic Jet Actuator 总被引:3,自引:1,他引:2
LUO Zhen-bing XIA Zhi-xun XIE Yong-gao 《中国航空学报》2007,20(3):193-201
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. 相似文献
19.
Nonlinear Adaptive Slewing Motion Control of Spacecraft Truss Driven by Synchronous V-gimbaled CMG Precession 总被引:1,自引:0,他引:1
Zhou Di Zhou Jingyang 《中国航空学报》2007,20(4):332-338
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. 相似文献
20.
LI Yue-jun YAN Chao 《中国航空学报》2007,20(3):202-209
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. 相似文献