共查询到19条相似文献,搜索用时 427 毫秒
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对观测信号进行小波包分析,从而提取故障信息,建立能够表征系统特征的状态向量,用模式识别的方法对系统进行故障检测与定位,实现系统的故障诊断。 相似文献
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首先介绍了小波包分解与重构算法和支持向量机的分类算法,然后以一个带通滤波器故障诊断为实例,利用小波包提取特征响应向量建立样本集,并利用支持向量机完成滤波器电路的故障诊断,诊断效果良好。 相似文献
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提出了一种基于小波包的变换方法。该方法通过对不同脉内调制方式进行频带能量的提取,并引入支持向量机来完成对辐射源的分类。该小波包变换对信号局部的时频特征具有较好的分辨率。仿真结果表明,文中的小波包变换信号时频特征的分析精度优于传统算法。 相似文献
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随着微电子技术的需求和发展,倒装芯片技术在高密度微型化封装领域得到了快速发展和广泛应用,而现有的一些倒装芯片检测方法存在一定的不足之处。为此,研究了主动红外的倒装芯片缺陷检测方法。实验中使用激光加热对倒装样片施加非接触热激励,通过红外热像仪获取样片温度分布。采用小波分析方法提取包括小波熵在内的信号特征,采用自组织神经网络对不同类型焊球进行聚类识别。研究表明,通过自组织神经网络可以有效地将不同缺陷焊球与参考焊球通过距离映射法映射到不同区域从而区分开,并且可以将未知焊球信号映射到相应的区域实现聚类识别。因此该方法可以有效实现倒装芯片的缺陷检测。 相似文献
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基于小波包能量谱分析方法,研究了压电耦合板结构中微损伤及其损伤程度的检测和识别方法。通过建立压电耦合板的谱有限元模型,数值模拟研究了金属板中微小凹陷损伤发生细微变化时传感器的动态响应;进而采用小波包分析技术对响应信号进行分解,得到一系列子信号的能量谱,分析了不同程度凹陷损伤对各节点能量谱的分布和幅值变化所产生的影响。研究结果表明,小波包能量谱能够对微小凹陷损伤及其损伤程度进行较为灵敏地识别,为实际检测工作提供了参考。 相似文献
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利用小波包理论对车载移动电话的接收信号进行小波包变换,通过设定一合适的阈值对变换后的信号进行量化处理.提取出主要由发动机产生的噪声信号,然后用实际检测信号减去小波包变换信号,得出汽车司机的语音信号.从而达到消除噪声的目的。利用MATLAB的小波工具箱对所提出的方法进行验证,结果表明提取后的信号与驾驶员的声音信号十分相似,误差较小,对发动机噪声有明显的抑制作用。 相似文献
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本文介绍了小波包分析的基本理论以及小波包信号降噪的基本原理,与小波变换相比,小波包变换则是对小波分解中所得到的高频部分再继续细分为一些子频带,具有更精细的信噪分离能力,所以对包含大量中、高频信息的信号能更好地进行时频局部化分析。小波包变换在信号去噪中有着非常重要的应用,因此利用小波包对信号进行消噪也越来越受到科学界的关注。本文的主旨在于研究最优小波包基函数的选取方法,以小波包分析为基础,根据最小代价原理研究信号分解的最佳小波包基,从而在最优小波包基的基础上获得最好的信号增强效果。 相似文献
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Improved ant colony-based multi-constrained QoS energy-saving routing and throughput optimization in wireless Ad-hoc networks简 总被引:3,自引:0,他引:3
In order to establish a route supporting multi-constrained quality of service(QoS), increase network throughput and reduce network energy consumption, an improved ant colony-based multi-constrained QoS energy-saving routing algorithm(IAMQER) is proposed. The ant colony algorithm, as one of the available heuristic algorithms, is used to find the optimal route from source node to destination node. The proposed IAMQER algorithm, which is based on the analysis of local node information such as node queue length, node forwarding number of data packets and node residual energy, balances the relationship between the network throughput and the energy consumption, thus improving the performance of network in multi-constrained QoS routing. Simulation results show that this IAMQER algorithm can find the QoS route that reduce average energy consumption and improves network packet delivery ratio under the end-to-end delay and packet loss ratio constraints. 相似文献
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Analysis of mean packet delay for upstream transmissions in passive optical networks with sleep mode
The sleep mode has been introduced to improve the energy efficiency of passive optical networks (PONs) with interleaved polling with adaptive cycle time (IPACT) as a medium access control (MAC) scheme. For energy saving, the sleep mode of each optical network unit (ONU) is activated based on the packet queue length for upstream traffic. We model such a PON as an N-user M/G/1 queue with reservations and vacations. Based on the framework of M/G/1 queueing analysis with some modification made to incorporate the nature of IPACT as well as the sleep mode, we derive a closed form expression of the mean packet delay. A unique challenge in our analysis is that certain quantities such as the residual time of an on-going sleep period for the upstream channel must be considered from the network's viewpoint while the delay due to the sleep mode experienced by a packet must be considered from the ONU's viewpoint. Simulation experiments are conducted to validate the analytical results and to show that the results are relatively insensitive to packet arrival statistics for large sleep periods. Finally, we demonstrate how a sleep period can be chosen given the quality-of-service (QoS) requirement on the mean packet delay. 相似文献
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《Industrial Informatics, IEEE Transactions on》2009,5(1):3-11
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Energy-efficient packet transmission over a wireless link 总被引:1,自引:0,他引:1
Uysal-Biyikoglu E. Prabhakar B. El Gamal A. 《Networking, IEEE/ACM Transactions on》2002,10(4):487-499
The paper considers the problem of minimizing the energy used to transmit packets over a wireless link via lazy schedules that judiciously vary packet transmission times. The problem is motivated by the following observation. With many channel coding schemes, the energy required to transmit a packet can be significantly reduced by lowering transmission power and code rate and therefore transmitting the packet over a longer period of time. However, information is often time-critical or delay-sensitive and transmission times cannot be made arbitrarily long. We therefore consider packet transmission schedules that minimize energy subject to a deadline or a delay constraint. Specifically, we obtain an optimal offline schedule for a node operating under a deadline constraint. An inspection of the form of this schedule naturally leads us to an online schedule which is shown, through simulations, to perform closely to the optimal offline schedule. Taking the deadline to infinity, we provide an exact probabilistic analysis of our offline scheduling algorithm. The results of this analysis enable us to devise a lazy online algorithm that varies transmission times according to backlog. We show that this lazy schedule is significantly more energy-efficient compared to a deterministic (fixed transmission time) schedule that guarantees queue stability for the same range of arrival rates. 相似文献
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Data aggregation in wireless sensor networks (WSNs) eliminates the data redundancy and is widely accepted as an essential paradigm for energy efficient routing in sensor networks. In this paper, we describe a protocol called RDA which associates a packet's reliability in data transmission with the amount of information it contains and gives the packet containing more information higher reliability in data transmission by adjust the degree of redundancy. Our algorithm is not associated with some special routing schemes, hence it can be used in any kinds of routing schemes for wireless sensor networks especially where data aggregation takes place and ensure a data packet with more information be transmitted more reliably and in that way reliability per energy could be improved. 相似文献
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On energy efficiency of geographic opportunistic routing in lossy multihop wireless networks 总被引:1,自引:0,他引:1
Geographic opportunistic routing (GOR) is an emerging technique that can improve energy efficiency in lossy multihop wireless networks. GOR makes local routing decision by using nodes?? location information, and exploits the broadcast nature and spatial diversity of the wireless medium to improve the packet forwarding reliability. In this paper, our goal is to fully understand the principles and tradeoffs in GOR, thus provide insightful analysis and guidance to the design of more efficient routing protocols in multihop wireless networks. We propose a local metric, one-hop energy efficiency (OEE), to balance the packet advancement, reliability and energy consumption in GOR. We identify and prove important properties about GOR on selecting and prioritizing the forwarding candidates in order to maximize the expected packet advancement. Leveraging the proved properties, we then propose two localized candidate selection algorithms with O(N 3) running time to determine the forwarding candidate set that maximizes OEE, where N is the number of available next-hop neighbors. Through extensive simulations, we show that GOR applying OEE achieves better energy efficiency than the existing geographic routing and blind opportunistic routing schemes under different node densities and packet sizes. 相似文献
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《Wireless Communications, IEEE Transactions on》2008,7(10):3769-3779
Due to the open nature of a sensor network, it is relatively easy for an adversary to eavesdrop and trace packet movement in the network in order to capture the receiver physically. After studying the adversary's behavior patterns, we present countermeasures to this problem. We propose a locationprivacy routing protocol (LPR) that is easy to implement and provides path diversity. Combining with fake packet injection, LPR is able to minimize the traffic direction information that an adversary can retrieve from eavesdropping. By making the directions of both incoming and outgoing traffic at a sensor node uniformly distributed, the new defense system makes it very hard for an adversary to perform analysis on locally gathered information and infer the direction to which the receiver locates. We evaluate our defense system based on three criteria: delivery time, privacy protection strength, and energy cost. The simulation results show that LPR with fake packet injection is capable of providing strong protection for the receiver?s location privacy. Under similar energy cost, the safe time of the receiver provided by LPR is much longer than other methods, including Phantom routing [1] and DEFP [2]. The performance of our system can be tuned through a few system parameters that determine the tradeoff between energy cost and the strength of location-privacy protection. 相似文献