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41.
神经网络专家系统在电源系统诊断中的应用 总被引:1,自引:0,他引:1
为了解决卫星这类复杂系统采用单一的智能故障诊断技术的诊断局限性问题,提出一种基于模糊综合评判的神经网络和专家系统相结合的诊断方法。选用改进的BP神经网络,添加动量因子和可变学习速率,并通过计算十个相同结构神经网络输出的标准差获得诊断结果的可信度。采用基于可信度的专家系统不确定性推理,给出了可信度计算方法。采用代数积与代数和模糊算子对两种诊断方法的结果进行综合评判。成功地应用于某卫星电源系统的故障诊断中。结果表明诊断的可信度和诊断的正确率得到提高。 相似文献
42.
分析讨论电位器的质量与产品部件发生颤抖的关系,为排除产品故障提供依据。由产品故障的再现试验和对电位器结构及工作环境的分析,认为电阻元件表面粗糙是引起产品部件发生颤抖的主要因素,当电刷在粗糙的电阻元件表面上快速运动时,触点发生弹跳和接触不良,电位器的输出电压发生掉电,导致控制电路发出不正常的控制信号,产品部件随之发生颤抖故障。通过对电位器的质量、工作过程及产品部件运动特点的分析,为排除产品故障提供了理论依据。 相似文献
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This paper studies an electronic counter-counter measures (ECCM) scheme combating against deceptive electronic counter measure (ECM) techniques.An adaptive detector exploiting generalized likelihood ratio test (GRLT) criterion is applied to detect the presence of deceptive jamming in fractional Fourier transform (FrFT) domain.First,the generating mechanism of spurious frequencies is analyzed based on the Volterra serial.The proposed nonlinear distortion model based on power amplifier behavior is robust in distortion analysis when the memory effect is considered.Second,a modified adaptive beamformer orthogonal rejection test (ABORT) like detector in closed form is built.The proposed detector can discriminate the echo and deceptive jamming adaptively by exploiting primary data and secondary data.This ECCM scheme is capable of guaranteeing the performance without the restriction of orthogonality,which is essential for the ABORT detectors.The expansion to radar network is discussed as a special case at the final part of this paper.Numerical simulations demonstrate the effectiveness of the proposed method. 相似文献
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导弹武器系统中有很多是多次使用的可修复杂系统。对于这种复杂系统,尤其是其寿命周期,预防维修时间及事后维修时间为离散分布时,其最佳预防维修周期难以用一般方法求得。针对这种情况,本文利用蒙特卡罗随机模拟法建立了系统计算模型,并通过模拟计算,得出了最佳预防维修周期的数字仿真结果。此结果可为制定导弹武器最佳修复策略提供依据。 相似文献
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文章基于水凝物粒子尺寸与THz波长的大小关系,分别利用Rayleigh近似、Mie理论以及几何光学方法计算了降雨和云雾引起THz波辐射的散射衰减。比较了不同强度的降雨和不同能见度、含水量的云雾对THz波的散射衰减。结果表明,随着频率的增大,THz波段雨衰减先增大后减小;在整个THz波段,含水量较小或能见度较低的云雾的衰减随频率的增大而单调增加,含水量较大或能见度较大的云雾的衰减随频率先增大后减小;在THz波段云雾衰减随能见度的减小和含水量的增加而增大,温度对THz波段的云雾衰减影响不大,在整个THz波段并不存在明显的规律。在THz波频率高端云雾影响较降雨要严重的多。 相似文献
49.
Wei Wang Bin Zhao Qi Wang Shaomin Yang 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2012
The Crustal Movement Observation Network of China (CMONOC) is one of the major scientific infrastructures, mainly using Global Positioning System (GPS) measurements, to monitor crustal deformation in the Chinese mainland. In this paper, decade-long coordinate time series of 26 continuous GPS sites of CMONOC are analyzed for their noise content using maximum likelihood estimation (MLE). We study the noise properties of continuous GPS time series of CMONOC for the unfiltered, filtered solutions and also the common mode signals in terms of power law plus white noise model. In the spatial filtering, we remove for every time series a common mode error that was estimated from a modified stacking of position residuals from other sites within ∼1000 km of the selected site. We find that the common mode signal in our network has a combination of spatially correlated flicker noise and a common white noise with large spatial extent. We demonstrate that for the unfiltered solutions of CMONOC continuous GPS sites the main colored noise is a flicker process, with a mean spectral index of ∼1. For the filtered solutions, the main colored noise is a general power law process, indicating that a major number of the filtered regional solutions have a combination of noise sources or local effects. The velocity uncertainties from CMONOC continuous GPS coordinate time series may be underestimated by factors of 8–16 if a pure white noise model is assumed. In addition, using a white plus flicker noise model, the median values of velocity errors for the unfiltered solutions are 0.16 (north), 0.17 (east) and 0.58 (vertical) mm/yr, and the median values for the filtered solutions are 0.09 (north), 0.10 (east) and 0.40 (vertical) mm/yr. 相似文献
50.
《中国航空学报》2023,36(4):268-285
It is of great significance to reasonably distribute the slung load to each helicopter while considering difference in power consumption, relative position and interaction comprehensively. Therefore, the load distribution strategy based on power consumption and robust adaptive game control is proposed in this paper. The study is on a “2-lead” multi-lift system of four tandem helicopters carrying a load cooperatively. First, based on the hierarchical control, the load distribution problem is divided into two parts: the calculation of expected cable force and the calculation of the anti-disturbance cable force. Then, aimed at minimizing the maximum equivalent power of helicopter, an optimization problem is set up to calculate the expected cable force. Specially, the agent power model is trained by BP neural network, the safe distance constraint between helicopters is set to 2.5 rotor diameters to reduce aerodynamic interference, and the helicopters with different performance can be considered by introducing the equivalent power factor into the objective function. Next, considering the difference and interaction between helicopters, the robust adaptive differential game control is proposed to calculate the anti-disturbance cable force. Particularly, to solve the coupled Hamiltonian equations, an adaptive solving method for value function is proposed, and its stability is proved in the sense of Lyapunov. The simulation results indicate that the proposed load distribution method based on power consumption is applicable to the entire flight trajectory even there are differences between helicopters. The game control can consider interaction between helicopters, can deal with different objective functions, and has strong robustness and small steady-state error. Based on the entire strategy, the cable force can be reasonably allocated so as to resist disturbance and improve the flight performance of the whole system. 相似文献