基于Hilbert模量频谱分析的异步电动机转子故障在线监测与诊断方法

Hilbert 变换是数字信号处理中的一种理想的移相方法。对某一信号进行这种变换,可得到其共轭信号。该文将Hilbert模量定义为原始信号与其共轭信号的平方和,并在此基础上提出了一种基于定子电流Hilbert模量频谱分析的异步电动机转子故障在线监测与诊断方法。理论分析和实验结果表明该方法可以有效地诊断鼠笼式异步电动机的转子故障。与需要同时采样三相电流的扩展的Park捠噶糠椒ㄏ啾?该方法大大节省了硬件和软件开销。

基于Hilbert模量频谱分析的异步电机转子断条故障研究

转子绕组断条是异步电机最常见故障之一。在分析当前主要诊断方法的基础上,提出Hilbert模量频谱分析方法对异步电机转子断条故障进行研究。将Hilbert模量定义为原始信号与其共轭信号的平方和,利用Hilbert模量将原相电流中的基波分量转变为直流分量,原频谱分析的转绕组断条的故障特征分量转变为频率为二倍转差频率的电流分量,决了相电流频谱分析方法中断条故障特征成分容易被基波湮没而难以突出故障特征的问题。文中研究了Hilbert模量频谱分析方法的原理和实现方法,并对偏心故障电机和转子断条电机分别进行仿真和实验研究。仿真分析和实验结果均表明,该方法对异步电机转子断条故障诊断具有较高的诊断精度和很好的频率分辨率,能克服传统的电流频谱法主频泄漏的影响,且工程实现方便。

基于Hilbert模量频谱分析的转子断条检测

针对定子电流频谱难以突出故障特征分量的弱点,提出了基于Hilbert模量频谱分析的转子断条检测方法。通过对定子电流的Hibert模量作傅立叶变换,将定子电流的故障特征频率分量转换为低频分量,再采用数字滤波和频谱细化的方法准确得出特征分量的幅值和频率。仿真结果表明,在转差率很小时,该方法可以有效避免故障特征分量被基频分量淹没,并能准确提取故障特征分量的信息。

基于解析小波变换和Hilbert模量频谱分析的感应电动机转子断条故障诊断

针对感应电动机转子断条故障诊断会受负荷波动影响以及故障频率容易被基波成分湮没的问题,本文提出基于解析小波变换和Hilbert模量频谱分析的感应电动机转子断条故障诊断方法。首先对感应电动机的定子电流信号进行解析小波变换,判断负荷是否波动;然后根据负荷波动的定位信息提取位于负荷平稳时间段内的定子电流信号,构造此负荷平稳时间段内的定子电流信号的Hilbert模量,对其做频谱分析,判断是否含有2sf_1频率分量,以确定感应电动机是否发生转子断条故障。仿真结果表明了这种基于解析小波变换和Hilbert模量频谱分析的感应电机转子断条故障诊断方法的有效性。

基于Hilbert模量与改进BP神经网络的电机转子断条故障诊断

为了更加快速准确识别感应电机转子断条故障,文中提出一种基于定子电流Hilbert模量与混沌粒子群算法(Chaos Particle Swarm Optimization,CPSO)优化BP神经网络的感应电机转子断条故障诊断方法。该方法首先通过定子电流Hilbert模量进行故障特征提取,然后采用CPSO-BP神经网络进行故障状态的自动识别。Hilbert模量可以将定子电流中的基波信号转化为直流分量,降低其对特征提取的干扰,从而凸显故障特征。而CPSO-BP神经网络方法相比BP神经网络具有更好的权值系数,可以进一步提高故障识别率。经实例验证,基于Hilbert模量与改进BP神经网络的电机故障诊断方法性能良好。

Hilbert模量与MUSIC相结合的感应电机转子断条故障检测方法

为了提高异步电动机转子断条故障检测的及时性与准确性,将Hilbert模量与多重信号分类(Multiple Signal Classification,MUSIC)相结合用于异步电机转子断条故障检测。Hilbert模量可以巧妙地转工频分量为直流分量,消除工频分量的不良影响。而MUSIC能够快速而准确地检测故障特征分量的频率大小,即使对于短时采样信号也有良好的性能,从而减少计算量。最后,通过仿真和以Y132M-4型感应电机进行试验验证了基于Hilbert模量与MUSIC相结合的异步电动机转子断条故障检测方法的有效性。

一种新的感应电动机转子断条故障检测方法

该文提出一种基于Hilbert模量频谱分析的感应电动机转子断条故障诊断的新方法.该方法是将Hilbert变换和小波分析方法相结合,得到解析小波变换,以准确判定负荷波动发生时刻,消除了负荷波动对断条故障特征频率的影响.将Hilbert模量定义成原始信号与其共轭信号的平方和,利用Hilbert模量将原相电流中的基波成分转换成直流成分,将转子断条的故障特征分量——(1-2s)f1转变为频率为的电流分量,解决了相电流频谱分析方法中断条故障特征分量很容易被基波淹没而难以突出故障特征分量的问题.仿真分析表明,该方法能克服传统的电流频谱分析法的缺点,对感应电动机转子断条故障给出正确无误的诊断结果.

Dynamic failure mode and energy-based identification method for a counter-bedding rock slope with weak intercalated layers

The dynamic failure mode and energybased identification method for a counter-bedding rock slope with weak intercalated layers are discussed in this paper using large scale shaking table test and the Hilbert-Huang Transform(HHT) marginal spectrum.The results show that variations in the peak values of marginal spectra can clearly indicate the process of dynamic damage development inside the model slope.The identification results of marginal spectra closely coincide with the monitoring results of slope face displacement in the test.When subjected to the earthquake excitation with 0.1 g and 0.2 g amplitudes,no seismic damage is observed in the model slope,while the peak values of marginal spectra increase linearly with increasing slope height.In the case of 0.3 g seismic excitation,dynamic damage occurs near the slope crest and some rock blocks fall off the slope crest.When the seismic excitation reaches 0.4 g,the dynamic damage inside the model slope extends to the part with relative height of 0.295-0.6,and minor horizontal cracks occur in the middle part of the model slope.When the seismic excitation reaches 0.6 g,the damage further extends to the slope toe,and the damage inside the model slope extends to the part with relative height below 0.295,and the upper part(near the relative height of 0.8) slides outwards.Longitudinal fissures appear in the slope face,which connect with horizontal cracks,the weak intercalated layers at middle slope height are extruded out and the slope crest breaks up.The marginal spectrum identification results demonstrate that the dynamic damage near the slope face is minor as compared with that inside the model slope.The dynamic failure mode of counter-bedding rock slope with weak intercalated layers is extrusion and sliding at the middle rock strata.The research results of this paper are meaningful for the further understanding of the dynamic failure mode of counter-bedding rock slope with weak intercalated layers.

PT Symmetric Quantum Models Living in an Auxiliary Pontryagin Space

In the traditional theoretical descriptions of microscopic physical systems （typically, atoms and molecules） people strongly relied upon analogies between the classical mechanics and quantum theory. Naturally, such a methodical framework proved limited as it excluded, up to the recent past, multiple, less intuitively accessible phenomenological models from the serious consideration. For this reason, the classical-quantum parallels were steadily weakened, preserving still the basic and robust abstract version of the key Copenhagen-school concept of treating the states of microscopic systems as elements of a suitable linear Hilbert space. Less than 20 years ago, finally, powerful innovations emerged on mathematical side. Various less standard representations of the Hilbert space entered the game. Pars pro toto, one might recall the Dyson＇s representation of the so-called interacting boson model in nuclear physics, or the steady increase of popularity of certain apparently non-Hermitian interactions in field theory. In the first half of the author＇s present paper the recent heuristic progress as well as phenomenologieal success of the similar use of non-Hermitian Ham iltonians will be reviewed, being characterized by their self-adjoint form in an auxiliary Krein space K. In the second half of the author＇s text a further extension of the scope of such a mathematically innovative approach to the physical quantum theory is proposed. The author＇s key idea lies in the recommendation of the use of the more general versions of the indefinite metrics in the space of states （note that in the Krein-space case the corresponding indefinite metric P is mostly treated as operator of parity）. Thus, the author proposes that the operators P should be admitted to represent, in general, the indefinite metric in a Pontryagin space. A constructive version of such a generalized quantization strategy is outlined and found feasible.

Krein space representation and Lorentz groups of analytic Hilbert modules

This paper aims to introduce some new ideas into the study of submodules in Hilbert spaces of analytic functions. The effort is laid out in the Hardy space over the bidisk H^2(D^2). A closed subspace M in H^2(D^2) is called a submodule if ziM ? M(i = 1, 2). An associated integral operator(defect operator) CM captures much information about M. Using a Kre??n space indefinite metric on the range of CM, this paper gives a representation of M. Then it studies the group(called Lorentz group) of isometric self-maps of M with respect to the indefinite metric, and in finite rank case shows that the Lorentz group is a complete invariant for congruence relation. Furthermore, the Lorentz group contains an interesting abelian subgroup(called little Lorentz group) which turns out to be a finer invariant for M.

A simple construction of optimal estimation in multivariate marginal Cox regression

The multivariate extension of the Cox model proposed by Wei,Lin and Weissfeld in 1989 has been widely used for analyzing multivariate survival data.Under the model assumption,failure times from an individual are assumed to marginally follow their respective proportional hazards regression relation,leaving the joint distribution completely unspecified.This paper presents a simple approach to efficiency improvement through segmentation of stochastic integrals in the marginal estimating equations and incorporation of the limiting covariance structure.It is shown that when partition of the time interval is done at a suitable rate,the resulting estimator is consistent and asymptotically normal.Through the reproducing kernel Hilbert space arising from the covariance function of the limiting Gaussian process,it is also shown that the proposed estimator is asymptotically optimal within a reasonable class of estimators under marginal specification.Simulations are conducted to assess the finite-sample performance of the proposed method.