管道泄漏检测中的噪声自适应抑制

在供水管道泄漏检测中,干扰和环境噪声直接影响到泄漏检测的有效性和漏点定位的精度,因此有必要对检测信号进行噪声抑制,增强检测信号的信噪比,以保证可靠检测和准确定位.提出一种根据不同带宽信号与噪声自相关长度的差异,利用线性增强器和预测器分别自适应抑制检测信号中的窄带噪声和宽带噪声的方法.该方法不需要任何先验知识就可以自适应抑制与有用信号带宽不同的噪声,处理后数据的信噪比较处理前平均提高4 dB以上,对实际的泄漏检测信号处理后,使得定位误差平均减小0.3m以上,并且降低了误检率.     

抗交串自适应噪声对消系统在管道相关检漏技术的应用

管道相关检漏技术通过对泄漏引发的振动信号的处理来完成检漏工作 ,系统原理和结构都非常简单。但在实际应用中 ,它有应用的局限性。在强噪声环境下 ,传感器接收到的包含独立噪声和公共噪声的信号 ,会导致相关曲线中出现虚假的峰值。为提高该类仪器的抗干扰性能 ,本文引入了一种新型的自适应滤波器结构——抗交串自适应噪声对消系统 (CTRANC)。在 Windows95平台上 ,我们编制了一个相关检漏软件 ,其中加入了 CTRANC模块。仿真的结果是令人满意的。     

管道泄漏检测中自适应时间延迟估计方法的设计

介绍了用自适应时间延迟估计方法设计管道泄漏检测系统的过程,详细阐述了其工作原理、自适应时间延迟估计方法及最小均方(LMS)自适应时间延迟估计算法,简要说明了其工作特点。     

基于EMD与响度的有源噪声控制系统

为了提高有源噪声控制系统的降噪效果,提出了基于经验模态分解( empirical mode decomposition,EMD)和响度的控制系统.该系统首先采用EMD方法对噪声源进行自适应分解,并对分解后的各个固有模态函数(intrinsic mode function,IMF)分量的响度进行计算,然后根据各个分量的响度大小进行残差滤波器的设计.与基于A计权曲线设计的残差滤波器相比,该方法所设计滤波器能更好地抑制响度较小的信号频率成分.对有源噪声控制系统的降噪效果进行了仿真,结果表明,所提出的控制系统比传统滤波-X LMS(filtered-X least mean square)方法和采用基于A计权残差滤波器的系统降噪效果更好.     

基于SVD降噪的机械振动信号经验模式分解及其应用

提出了1种基于奇异值分解降噪的振动信号经验模式分解方法,利用该法对原始振动信号进行相空间重构和奇异值分解,并根据奇异值降噪,再利用经验模式分解法提取降噪后振动信号的基本模式分量,对滤波前和滤波后振动信号进行经验模式分解分析。分析结果表明：奇异值分解能有效地提高信噪比,突出原始振动信号的特征,使降噪后振动信号分解出的基本模式分量具有更明确的物理意义,有利于对柴油机进行精确诊断。     

基于Lyapunov稳定性理论的气体管道泄漏检测技术研究

管道泄漏检测技术已经在长输气体管道安全运行中起到很重要的作用.本文讨论了基于李雅普诺夫稳定性理论的天然气管道泄漏检测技术,建立了气体管道泄漏动态模型,根据李雅普诺夫意义下对非线性系统的稳定性定义,通过对特征值的分析判断泄漏.实验仿真证明该方法具有一定的可行性.     

基于动态压力信号的管道泄漏检测技术研究

本文提出基于压电传感器信号特征的管道泄漏检测方法。比较了基于压电传感器和压力传感器的管道泄漏检测的优缺点，介绍了基于压电式动态压力变送器的管道泄漏检测的系统结构、压电式动态压力变送器的外形特征和内部结构，分析了基于压电式动态压力变送器的管道泄漏信号的时、频域特征，给出了相应的检测和定位方法。实际应用表明，这种方法可以快速、准确地进行泄漏检测和定位，并能可靠地工作。     

Gear fault diagnosis using active noise cancellation and adaptive wavelet transform

Acoustic signal from a gear mesh with faulty gears is in general non-stationary and noisy in nature. Present work demonstrates improvement of Signal to Noise Ratio (SNR) by using an active noise cancellation (ANC) method for removing the noise. The active noise cancellation technique is designed with the help of a Finite Impulse Response (FIR) based Least Mean Square (LMS) adaptive filter. The acoustic signal from the healthy gear mesh has been used as the reference signal in the adaptive filter. Inadequacy of the continuous wavelet transform to provide good time–frequency information to identify and localize the defect has been removed by processing the denoised signal using an adaptive wavelet technique. The adaptive wavelet is designed from the signal pattern and used as mother wavelet in the continuous wavelet transform (CWT). The CWT coefficients so generated are compared with the standard wavelet based scalograms and are shown to be apposite in analyzing the acoustic signal. A synthetic signal is simulated to conceptualize and evaluate the effectiveness of the proposed method. Synthetic signal analysis also offers vital clues about the suitability of the ANC as a denoising tool, where the error signal is the denoised signal. The experimental validation of the proposed method is presented using a customized gear drive test setup by introducing gears with seeded defects in one or more of their teeth. Measurement of the angles between two or more damaged teeth with a high level of accuracy is shown to be possible using the proposed algorithm. Experiments reveal that acoustic signal analysis can be used as a suitable contactless alternative for precise gear defect identification and gear health monitoring.     

基于负压波分析的油管检漏技术研究

通过对负压波产生、流体参数测量及波形模式识别原理的分析，阐述了采用负压波分析的方法对油管泄漏进行检测和诊断的可行性，并提出了与负压波分析相结合的上下文无关文法，最后举例说明了这种方法的实际应用。     

基于EMD和Snakes模型信息融合的表面缺陷检测方法

本文将具有自适应滤波特性的经验模式分解（EMD）方法与Snakes模型相结合，提出了适用于高噪声复杂背景下表面缺陷图像检测的新方法。首先采用改型EMD在整幅图上将缺陷的位置和大致范围从复杂背景下分离出来，然后在缺陷附近用向心搜索法缩小缺陷的检测区域，最后用Snakes模型迭代逼近缺陷边缘。该方法能自动、准确地完成球形金属表面的缺陷检测。实验结果表明，该方法是有效和可靠的。     

FPGA implementations of an ADALINE adaptive filter for power-line noise cancellation in surface electromyography signals

This paper presents FPGA implementations of an adaptive linear neural network (ADALINE) based adaptive filter for power-line noise cancellation in surface Electromyography (sEMG) signals. 10-Tap ADALINE filters in the 16-bit Q0.15 fixed-point format are offered into two categories: small area implementations and high-throughput implementations. The small area ones are optimized by using the resource-sharing technique that considers the interconnect complexity. For the high-throughput ones, we propose the delayed ADALINE (DADALINE) pipelined adaptive filter which is based on the relaxed look-ahead technique. The implementation results on the Xilinx XC3S1200E-4FG320 FPGA show that the smallest implementation achieved the throughput of 1.61 million samples per second (MSPS) and the area of three multipliers, 611 LUTs, and 511 flip-flops, and the fastest implementation achieved 56.15 MSPS and the area of 23 multipliers, 945 LUTs, and 907 flip-flops. Each implementation has been tested on an FPGA board interfaced with an sEMG measurement set.     

Leak detection monitoring system of long distance oil pipeline based on dynamic pressure transmitter

A dynamic pressure transmitter (DPT) is designed in this paper for long distance oil and gas pipeline, of which the design principle and main performance indices are introduced. A novel leak detection monitoring system (LDMS) of long distance oil pipeline based on DPT is designed, and the detection principle and system composition are specified. Dynamic pressure signals along the pipeline can be obtained by the DPT, and then the pipeline leak can be detected by extracting the wavelet packet entropy (WPE) of the signals. The WPE signal feature extraction method for judgment of pipeline leak is explored and developed. In addition, the influence of the wavelet basis and calculating window width on the identification performance of the WPE are further discussed. The application examples show that the DPT has higher detection sensitivity and leak resolution than the traditional pressure transmitter. The system can identify the pipeline leak correctly and reduce false alarm rate effectively. It can also improve detection sensitivity and localization accuracy. The system can correctly detect leaks with a rate of 96.7% and the greatest localization error is 101 m.     

基于动态核独立元统计量的石油管道泄漏检测

石油管道泄漏是受腐蚀、磨损、焊缝缺陷、振动、冲刷以及人为破坏等多种因素影响的连续动态过程,单纯基于压力信号的检测和基于高斯分布假设的信号分析方法不能适应其多变量、强耦合、动态特性。为此,综合考虑与管道泄漏有关的操作参数和环境参数,针对管道监测参数呈现时序自相关性、泄漏检测精度不高的问题,提出一种基于动态核独立分量分析(DKICA)的石油管道泄漏检测方法。首先引入动态特性确定算法(DOD)计算模型最佳参数阶次,解决动态过程导致的监测参数呈现时序自相关性问题;再采用核独立分量分析(KICA)在核主元空间提取独立元;最后通过考察独立元的T2、SPE联合指标判断泄漏发生。通过对某一输送场站采集的数据进行实验验证,结果表明采用联合指标D2的正常样本误检率和泄漏样本漏检率都远低于单独采用T2或SPE统计量;而引入动态特性的2阶DKICA对于正常样本的误检率和泄漏样本的漏检率都低于未引入动态特性的KICA方法。可见,所提出的基于动态核独立分量联合指标的石油管道泄漏检测方法是一种高效且可行的方法。     

基于模糊分类的流体管道泄漏故障智能检测方法研究

本文针对基于负压波法管道泄漏实时检测系统误报高和灵敏度低的问题提出一种流体管道泄漏故障智能检测方法,该方法首先给出管道运行参数的确定模型,然后结合模糊算子给出流体管道状态模糊模型,进而利用该模型实现管道故障分类.以这种智能检测方法为核心设计流体管道故泄漏故障智能诊断系统(leak intelligent diagnosis system for fluid pipeline,LIDSFP),通过对某成品油管道实例仿真和在流体管道测试系统上的试验研究,给出了LIDSFP性能指标,进一步分析表明该系统可以有效完成流体管道的泄漏故障诊断.     

基于噪声白化准则的自适应噪声抵消方法

提高泄漏检测信号的信噪比是提高管道泄漏检测定位性能的重要途径,针对泄漏检测定位的工程实际提出一种新的噪声抑制方法,基于噪声白化准则的自适应噪声抵消方法。用噪声白化准则控制检测信号的线性预测,提取出与干扰噪声相关、与泄漏信号不相关的信号作为自适应噪声抵消器的参考输入,这样能够有效抵消泄漏检测信号中自相关长度小于泄漏信号自相关长度的干扰噪声。实验结果和实际应用表明,该方法能有效抑制泄漏检测信号中的干扰噪声。     

基于EMD和Hilbert解调的齿轮箱故障诊断

针对复杂的齿轮箱振动信号难以提取出故障特征频率的问题,提出了一种将希尔伯特包络解调技术与经验模式分解(EMD)相结合的分析方法。首先对齿轮箱的故障信号进行了EMD分解,得到了本征模态函数(IMF分量),再对IMF分量进行了包络解调,得到了其调制信号,结合调制信号的频率成分可初步判断出齿轮箱中出现故障的齿轮;然后根据IMF分量与初始信号之间相关系数的大小,选择相关系数较大的分量重构信号,相当于对初始信号进行滤波;最后对重构的信号以啮合频率及其倍频为中心频率进行了带通滤波,对得到的信号进行了包络解调分析,再次进行了故障诊断,以验证故障诊断的准确性。整个过程通过对齿轮箱实测故障信号的分析加以验证。研究结果表明,该方法能够准确地提取出齿轮箱的故障特征频率,从而可以对齿轮箱故障进行有效地诊断。     

基于经验模态分解与改进自适应阈值的边缘检测

经验模态分解(Empirical Mode Decomposition)是一种新的自适应的信号分解方法。文中利用二维经验模式分解的算法,通过过滤过程得到固有内模函数,然后利用多尺度分析提取不同尺度下的边缘,并与改进的自适应阈值方法结合对图像进行降噪处理。通过仿真实验,结果表明这种方法不仅能准确地检测出图像边缘,而且还有效地抑制了噪声,其性能优于传统的边缘检测算法。     

Adaptive noise cancellation based on beehive pattern evolutionary digital filter

Evolutionary digital filtering (EDF) exhibits the advantage of avoiding the local optimum problem by using cloning and mating searching rules in an adaptive noise cancellation system. However, convergence performance is restricted by the large population of individuals and the low level of information communication among them. The special beehive structure enables the individuals on neighbour beehive nodes to communicate with each other and thus enhance the information spread and random search ability of the algorithm. By introducing the beehive pattern evolutionary rules into the original EDF, this paper proposes an improved beehive pattern evolutionary digital filter (BP-EDF) to overcome the defects of the original EDF. In the proposed algorithm, a new evolutionary rule which combines competing cloning, complete cloning and assistance mating methods is constructed to enable the individuals distributed on the beehive to communicate with their neighbours. Simulation results are used to demonstrate the improved performance of the proposed algorithm in terms of convergence speed to the global optimum compared with the original methods. Experimental results also verify the effectiveness of the proposed algorithm in extracting feature signals that are contaminated by significant amounts of noise during the fault diagnosis task.     

基于DCPSO的模糊神经网络的管道泄漏检测方法

提出了一种基于发散-收敛PSO(DCPSO)优化模糊神经网络的管道泄漏检测与估计方法。该方法采用广义概率积、广义概率和模糊算子代替普通神经网络中的传递函数,并用DCPSO算法对该模糊神经网络的权值进行优化。通过实际管道泄漏数据对网络进行仿真研究,结果表明文中所述方法在管道泄漏的检测与估计中,不仅比BP算法具有更快的收敛速度,其结果也更优,进而也昭示出该方法在管道泄漏检测与估计中的可用性。     

面向管道泄漏检测应用的嵌入式RTU设计

本文提出了一种基于ARM处理器S3C2410和嵌入式Linux系统的RTU设计方案。同时,利用Linux系统强大的网络功能和开源的应用程序,构建了一个嵌入式ftp服务器。实际应用表明,该系统具有成本低、性能稳定、安全可靠等特点。