航空发动机双冗余架构传感器信息通道故障诊断方法研究

传感器数据的高可靠性是航空发动机控制系统可靠工作的基础,故障诊断就十分重要;基于传感器双冗余结构,综合利用神经网络预测和传感器冗余性信息变化判断进行故障诊断是一种新的故障诊断新方法;该方法先用RBF神经网络对传感器输出进行预测,若预测值与输出值发生较大的偏差,进一步考察传感器之间的冗余性信息变化情况来判断传感器是否发生故障,若发生故障,进行故障定位,进而采用对应的诊断策略;仿真实验结果表明该方法能够有效地解决双冗余架构传感器信息通道的故障诊断问题。     

柴油机供油系统状态的朴素贝叶斯诊断方法研究

针对朴素贝叶斯方法的缺点,提出了基于主分量分析方法的柴油机供油系统朴素贝叶斯诊断技术;该方法利用历史诊断记录,通过主分量分析方法对训练样本的输入维数进行约简,将高维相关的特征信号转换为低维相互独立的特征信号,并在此基础上进行贝叶斯诊断分析,从而改善了贝叶斯方法中要求的属性信息之间的独立性限制,实验结果表明,基于主成分分析方法的贝叶斯故障诊断技术对于简化诊断模型,减少算法执行时间,提高诊断速度具有重要作用。     

The effects of container size, frequency and extended horizontal reach on maximum acceptable weights of lifting for female industrial workers

In the development of our present manual materials handling (MMH) guidelines (Snook, S.H., Ciriello, V.M., 1991. The design of manual tasks: revised tables of maximum acceptable weights and forces. Ergonomics 34, 1197-1213), the assumption was made that the effects of frequency on maximum acceptable weights (MAWs) of lifting with a large box (hand distance, 38 cm from chest) were similar to that of lifting with a small box (hand distance, 17 cm from chest). The first purpose of the present experiment was to investigate this assumption with female industrial workers. The second purpose was to study the effects of extended horizontal reach lifting (hand distance, 44.6 cm from chest) on MAWs as a confirmation of the results of a previous studies on this variable with males (Ciriello, V.M., Snook, S.H., Hughes, G.J., 1993. Further studies of psychophysically determined maximum acceptable weights and forces. Hum. Factors 35(1), 175-186; Ciriello, V.M., 2003. The effects of box size, frequency, and extended horizontal reach on maximum acceptable weights of lifting. Int. J. Ind. Ergon. 32, 115-120). Lastly, we studied the effects of high frequency (20 lifts/min) on MAWs of lifting. Ten female industrial workers performed 15 variations of lifting using our psychophysical methodology whereby the subjects were asked to select a workload they could sustain for 8h without "straining themselves or without becoming unusually tired weakened, overheated or out of breath". The results confirmed that MAWs of lifting with the large box was significantly effected by frequency. The frequency factor pattern in this study was similar to the frequency pattern from a previous study using the small box (Ciriello, V.M., Snook, S.H., 1983. A study of size distance height, and frequency effects on manual handling tasks. Hum. Factors 25(5), 473-483) for all fast frequencies down to one lift every 2 min with deviations of 7%, 15%, and 13% for the one lift every 5 and 30 min tasks and the one lift in 8h task, respectively. The effects of lifting with an extended horizontal reach decreased MAW 22% and 18% for the mid and center lift and the effects of the 20 lifts/min frequency resulted in a MAW that was 47% of a 1 lift/min MAW. Incorporating these results in future guidelines should improve the design of MMH tasks for female workers.     

Physiological and psychophysical responses in handling maximum acceptable weights under different footwear--floor friction conditions

A study on combined manual materials-handling tasks performed on floors under three friction levels was conducted. Eight male subjects participated in the study. The maximum acceptable weight of handling, including lifting, carrying for 3m, lowering, and walking 3m back at twice per minute was determined. The subject then performed the same tasks for 10 min. Heart rate, Vo2, energy efficiency, perceived sense of slip, and rating of perceived exertion for whole body strain were measured. The results showed that the effects of friction level on the maximum acceptable weights of handling, perceived sense of slip, Vo2, and energy efficiency were statistically significant (p相似文献   

一种新的容错ATM交换机结构的冗余路径分析

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增强前馈神经网络对多点断路故障的容错能力

神经网络在发生多点断路故障时,网络中的多个隐层神经元及其相关的连接权同时失效。该文针对陷层神经元可以动态增加的一类前馈神经网络,提出了一种三阶段方法T3。T3先对网络进行一次训练,然后用验证集进行测试以确定网络的故障曲线拐点,在此基础上通过第二次训练自适应地增加冗余隐层神经元。实验表明,T3使用较小的冗余量就可以显著改善网络对多点断路故障的容错性,在网络的容错能力和结构复杂度之间较好地达成了折衷。     

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Fault diagnosis is very important for modern production technology and has received increasing theoretical and practical attention during the last few years. This paper presents a model-based diagnostic method for industrial systems. An online, real-time, deep knowledge based fault detection system has been developed by combining different development environments and tools. The system diagnoses, predicts and compensates faults by coupling symbolic and numerical data in a new environment suitable for the interaction of different sources of knowledge and has been successfully implemented and tested on a real hydraulic system.     

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飞机余度舵机系统鲁棒故障诊断

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