共查询到20条相似文献,搜索用时 93 毫秒
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爆破振动信号是典型的短时非平稳随机信号。应用多分辨率特点的小波包变换对爆破振动信号进行多层分解,得到信号能量分布的细节信息。根据建立在概率统计基础上的信息熵概念,推导得到爆破振动信号能量熵计算方法。分析了4种类型爆破振动信号的能量熵,熵值由大到小为:隧道爆破、管道爆炸、台阶爆破、塌落振动。结果表明,能量熵能够反映不同类型爆破对振动信号的影响。提出将能量熵作为爆破振动信号的新特征量,为爆破振动信号特征提取、不同爆破类型振动信号识别和爆破振动预测提供一种新思路。 相似文献
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论述了小波包分解及其能量谱处理超越离合器故障的原理与方法,应用小波包分解及其能量谱直观地识别出故障的特征频带,并进行了量化分析,结果表明,小波包及小波包分解能量谱比传统的傅里叶分析方法具有更大的优越性及实用价值。 相似文献
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小波变换具有良好的局部特性和空间频率特性,并且具有描述非平稳图像信号的能力和适应人眼视觉特性的良好性能。嵌入式零树小波编码(EZW)算法是小波图像编码研究的一个里程碑。针对EZW不足,提出一种有效的EZW算法改进方案。 相似文献
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On the background of economic globalisation, market competition is no longer the competition between enterprises, but it is the competition between supply chains. Supplier selection is the basis of supply chain cooperation, and is also the key factor to improve the competitive power of a supply chain. A novel method, which combines entropy weight and an improved ELECTRE-III method, is proposed to deal with supplier selection of supply chains. The research states at home and abroad are firstly analysed, and on the foundation of the relative literature, the indicator systems are constructed and the corresponding objective weight of each indicator based on entropy is calculated. Then the threshold is confirmed and the harmoniousness index and the unharmoniousness index are calculated. Next, the outranking relation is calculated and evaluated. Last, the suppliers are ranked based on the net advantage value of each project. Finally, the case analysis proves that the process of this method is clear and the application of it is convenient. 相似文献
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Due to the importance of electrical grid reliability, analysis and evaluation of human error in the maintenance of electrical networks should be also considered seriously. The root causes of these errors must be identified and prioritized to plan for human error reduction. One of the objectives of the present study is to identify and predict these roots for power transmission maintenance groups from organizational, job position, communication, individual, and supervision aspects along with the relationships between these factors. In particular, this paper demonstrates that supervisor behavior as an external factor has a significant effect on maintenance personnel error. For this reason, special attention has been paid to identifying and controlling human factors from a supervisory point of view in this study. This paper also provides a method for detecting the extent of the expected influence of these roots on each personnel, since human error has a random nature. This is done based on the law of mathematical expectation. Finally, a method is suggested to rank roots based on greater effectiveness and evaluate personnel with higher error expectations. The proposed method is a combination of intermediate methods, Shannon entropy, and technique for order of preference by similarity to ideal solution (TOPSIS). The origins of the four human errors between 2014 and 2018 related to the two experts of Fars Electricity Maintenance Contractor Company are compared by the proposed method. 相似文献
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基于广义解调时频分析的多分量信号分解方法 总被引:1,自引:0,他引:1
广义解调时频分析方法是一种新的信号处理方法,该方法将广义解凋和最大重叠离散小波包变换相结合对复杂信号进行分解,得到若干个瞬时频率和瞬时幅值都具有物理意义的单分量信号,从而获得原始信号完整的时频分布。本文在介绍广义解调时频分析方法的基础上,将该方法用于多分量信号的分析,对该方法进行了改进,给出了由改进的广义解调时频分析方法分解多分量信号的具体步骤,从而由改进后的广义解调时频分析方法不仅可以得到原始信号中各个分量的时域波形,而且还可以得到相同的时频分布。采用改进后的广义解调时频分析方法对仿真信号进行了分析,同时和其它时频分析方法进行了比较,结果表明了该方法的有效性。最后,对广义解调时频分析方法中的相位函数选择问题进行了讨论。 相似文献
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将功率谱和神经网络相结合,应用于高海况、低信噪比条件下,水中目标信号的特征提取中.文中首先对信号进行功率谱估计,利用目标信号功率主要集中在低频部分的特点,提取低频信号的能量作为特征,然后利用人工神经网络对目标信号进行检测.利用不同浪级情况下海洋水压场的仿真信号数据,对某型目标舰船的水压信号进行了检测计算,验证了该方法的有效性,尤其是达到了在高海况、低信噪比条件下,对目标信号检测率比较高、虚警率比较低的效果. 相似文献
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Pedestrians are the most vulnerable road users, and pedestrian safety has become a major research focus in recent years. Regarding the quality and quantity issues with collision data, conflict analysis using surrogate safety measures has become a useful method to study pedestrian safety. However, given the inequality between pedestrians and vehicles in encounters and the multiple interactions between pedestrians and vehicles, it is insufficient to simply use the same indicator(s) or the same way to aggregate indicators for all conditions. In addition, behavioral factors cannot be neglected.To better use information extracted from trajectories for safety evaluation and pay more attention on effects of behavioral factors, this paper develops a more sophisticated framework for pedestrian conflict analysis that takes pedestrian-vehicle interactions into consideration. A concept of three interaction patterns has been proposed for the first time, namely hard interaction, no interaction, and soft-interaction. Interactions have been categorized under one of these patterns by analyzing profiles of speed and conflict indicators during the whole interactive processes. In this paper, a support vector machine (SVM) approach has been adopted to classify severity levels for a dataset including 1144 events extracted from three intersections in Shanghai, China, followed by an analysis of variable importance. The results revealed that different conflict indicators have different contributions to indicating the severity level under various interaction patterns. Therefore, it is recommended either to use specific conflict indicators or to use weighted indicator aggregation for each interaction pattern when evaluating pedestrian safety.The implementation has been carried out at the fourth crosswalk, and the results indicate that the proposed method can achieve a higher accuracy and better robustness than conventional methods. Furthermore, the method is helpful for better understanding underlying levels of safety from the behavioral perspective, which can also provide evidence for targeted traffic education on proper behaviors. 相似文献