基于MCKD与CEEMDAN的声信号故障特征提取方法

在双转子轴承状态监测与故障诊断中,信号传递路径复杂,很难通过加速度传感器直接获得信号,而声音信号有非接触式测量的优势,包含大量特征信息.为了能够准确、有效地通过声音信号实现滚动轴承故障诊断,检测出轴承故障,提出了基于自适应噪声完备集合经验模态分解(CEEMDAN)和最大相关峭度解卷积(MCKD)的滚动轴承故障诊断方法.首先运用最大相关峭度解卷积方法增强轴承故障声音信号中的冲击,然后对处理后的信号进行CEEMDAN处理,计算每个经验模态分量的峭度值,根据峭度值选取最优分量并求Hilbert包络谱,以准确提取故障特征频率.文中采用该方法基于声音信号实现滚动轴承故障诊断,为提取最优分量提供了理想筛选标准,一定程度上降低了故障诊断的复杂程度,具有良好的自适应性.     

基于快速峭度图算法与平方包络共振解调的滚动轴承自适应故障诊断方法

针对共振解调技术应用在滚动轴承故障诊断中存在信噪比低和带通滤波器参数需要依靠经验确定的问题,提出了一种基于快速峭度图算法与平方包络共振解调技术相结合的滚动轴承自适应故障诊断方法.根据快速峭度图算法的自适应性,确定带通滤波器的参数,并提取滚动轴承故障振动信号高频共振带中包含的故障特征频段;计算去直流后信号的信噪比,若其信噪比大于1,则利用平方包络方法进行重构,以突出故障特征信号;对重构信号进行频谱分析,得到其故障特征频率,识别出相应的故障类型.通过故障滚动轴承试验,验证了该方法的有效性和准确性.     

基于奇异值分解和共振解调的滚动轴承故障特征提取

针对共振解调方法容易受到噪声干扰,以及带通滤波器参数难以确定,很大程度上依赖经验的问题,提出一种基于奇异值分解和共振解调的滚动轴承故障特征提取方法;利用奇异值分解算法,将轴承振动信号分解成多个奇异值分量,计算各分量的峭度值,选择峭度值最大的分量,利用谱峭度算法确定中心频率和带宽,并对该分量信号进行带通滤波和包络解调分析。结果表明,提取性能以及鲁棒性能实验证明了该方法能够自适应确定滤波频带,降低噪声干扰的影响,并且在带通滤波器失效情况下有良好的稳定性。     

基于EEMD降噪与二次相位耦合的滚动轴承故障诊断

针对滚动轴承出现故障时故障信号常常被强的背景噪声所淹没,故障特征难以准确提取的问题,提出了一种基于总体平均经验模态分解(EEMD)降噪与二次相位耦合的故障诊断方法.对原始信号进行EEMD分解,通过相关系数-峭度值的大小选取EEMD分解后得到的固有模态函数(IMF).对筛选出来的IMF进行了重构从而达到降噪的目的.对重构后的包络信号进行1.5维谱分析,提取二次相位耦合产生的非线性特征,从而得到滚动轴承故障特征频率信息.通过实测滚动轴承数据验证了该方法可以有效地提取轴承内圈和外圈的故障特征,从而识别轴承的故障.     

形态分量分析在滚动轴承故障诊断中的应用

滚动轴承局部故障振动信号中的周期性冲击是识别故障的关键特征.形态分量分析在由多种形态原子组成的过完备字典基础上提取信号中的不同形态成分,基于这种思想提出了一种基于新型过完备复合字典的形态分量分析方法.依据滚动轴承故障振动信号中分量间的形态差异性,改进字典后该方法可以更具针对性地提取出包含故障特征的冲击分量,配合包络谱分析准确提取故障特征频率,诊断滚动轴承局部故障.对比基于快速谱峭度法的轴承故障诊断方法,该方法可以避免人为选择共振带产生的不准确性和非最优问题,提高了故障诊断效果.通过轴承仿真信号和故障实验信号分析验证了该方法的有效性.     

采用改进HVD与Lempel-Ziv复杂性测度的滚动轴承早期损伤程度评估方法

针对滚动轴承早期故障特征微弱难以定量检测的问题,提出一种基于希尔伯特振动分解(HVD)和Lempel-Ziv复杂性测度(LZC)的滚动轴承内外圈损伤程度评估方法。该方法利用HVD将滚动轴承故障信号分解为幅值由大到小、不同瞬时频率的HVD初始分量,基于峭度分析从各HVD初始分量中选出最优分量并重构该故障信号,采用均值符号化方法计算重构信号的LZC指标。关于HVD的端点效应问题,采用镜像延拓方法对其进行改进,仿真分析的结果表明,镜像延拓有效地改进了其端点效应的问题,提高了故障信号的分解精度;在此基础上,将HVDLZC方法应用于不同损伤程度的滚动轴承内外圈故障信号,结果表明该方法能够解除信号非线性、非平稳性干扰,快速提取信号的故障振动模式分量,给出内外圈各损伤状态的HVD-LZC特征区间;采用由遗传算法进行参数寻优的支持向量机(GA-SVM)方法对3种不同损伤状态的内外圈信号的HVD-LZC特征进行测试分析,结果表明HVD-LZC指标在区分轴承内外圈的不同损伤程度上具有优越性,从而为滚动轴承内外圈损伤程度的评估提供了一种有效方法。     

基于集成固有时间尺度分解和谱峭度的滚动轴承故障检测

针对固有时间尺度分解(ITD)方法中固有旋转分量存在局部波动的问题,提出一种集成固有时间尺度分解,将其结合谱峭度法,提高轴承故障检测的准确度。首先运用3次样条插值拟合基线控制点,实现振动信号的自适应频带划分,获得若干个固有旋转分量;然后根据K-L散度准则选取真实分量进行信号重构,使用谱峭度法确定带通滤波器的最优参数;最后分析滤波处理结果的包络谱,得到振动信号的特征信息。研究结果表明:与经验模式分解和单纯包络谱分析方法相比,采用集成固有时间尺度分解和谱峭度的包络方法(EITD-SK)能更好地提取滚动轴承故障特征信息,实现轴承故障的准确检测,结果与实际相符。     

基于形态滤波优化算法的滚动轴承故障特征提取方法

针对轴承故障振动信号的非线性、非平稳性的特点,而且故障信号经常被各种噪声、干扰所淹没,提出了一种基于局部均值分解(local mean decomposition,LMD)与自适应多结构元素多尺寸差值形态滤波器相结合的方法。原始故障信号先经过局部均值分解得到若干乘积函数(product function,PF)分量,然后采用峭度值准则,选取峭度值最大的PF分量,再将其经过自适应多结构元素多尺寸差值形态滤波器进行滤波解调,最后解调结果进行频谱分析,提取故障特征。为了体现其可行性和优越性,与包络解调、LMD-形态闭运算和LMD-形态差值滤波三种方法进行了比较,仿真信号和实测轴承故障信号的分析结果表明,它具有更强的噪声抑制和脉冲提取能力,可以有效地提取滚动轴承故障特征信息,实现故障的精确诊断。     

基于能量峰定位的经验小波变换及在轴承微弱故障诊断中的应用

为了解决经验小波变换在轴承振动信号频谱分割不当的问题,提出了一种基于自适应能量峰定位的经验小波变换。该方法采用Teager能量算子对傅里叶频谱进行能量集中,降低噪声和无关分量影响;利用多尺度寻峰定位算法自适应确定频谱分割边界;通过构建小波滤波器组提取各模态分量。依据峭度指标挑选故障信息最大的模态分量,最后通过Hilbert包络解调提取轴承的故障特征频率。仿真和实验分析结果表明:提出的方法从能量角度入手,鲁棒性更强;频段划分考虑频谱的形状,能自适应识别故障频带;与原始经验小波变换方法相比,改进方法能明显增强早期微弱故障特征,提高轴承早期故障诊断性能。     

基于EEMD与形态滤波的滚动轴承故障诊断方法研究

为从滚动轴承故障信号中提取出包含故障信息的特征频率,提出集合经验模式分解法(EEMD)与形态滤波相结合的解调方法。该方法首先利用EEMD自适应地将信号分解成多个IMF分量,然后计算各IMF分量与原信号的相关系数,选择合适的IMFs进行信号重构,再对重构后的信号进行形态滤波,滤除脉冲干扰,提取出故障特征信息。将该方法应用于滚动轴承故障诊断实例中,并将分析结果与直接对原信号进行包络谱分析解调的结果进行对比。结果表明,该方法提取故障信息的效果较包络谱分析解调的效果要好。     

Characterization of Ordovician carbonate reservoirs, southeastern Saskatchewan, Canada

The discovery of the prolific Ordovician Red River reservoirs in 1995 in southeastern Saskatchewan was the catalyst for extensive exploration activity which resulted in the discovery of more than 15 new Red River pools. The best yields of Red River production to date have been from dolomite reservoirs. Understanding the processes of dolomitization is, therefore, crucial for the prediction of the connectivity, spatial distribution and heterogeneity of dolomite reservoirs.The Red River reservoirs in the Midale area consist of 3～4 thin dolomitized zones, with a total thickness of about 20 m, which occur at the top of the Yeoman Formation. Two types of replacement dolomite were recognized in the Red River reservoir: dolomitized burrow infills and dolomitized host matrix. The spatial distribution of dolomite suggests that burrowing organisms played an important role in facilitating the fluid flow in the backfilled sediments. This resulted in penecontemporaneous dolomitization of burrow infills by normal seawater. The dolomite in the host matrix is interpreted as having occurred at shallow burial by evaporitic seawater during precipitation of Lake Almar anhydrite that immediately overlies the Yeoman Formation. However, the low δ18O values of dolomited burrow infills (-5.9‰～ -7.8‰, PDB) and matrix dolomites (-6.6‰～ -8.1‰, avg. -7.4‰ PDB) compared to the estimated values for the late Ordovician marine dolomite could be attributed to modification and alteration of dolomite at higher temperatures during deeper burial, which could also be responsible for its 87Sr/86Sr ratios (0.7084～0.7088) that are higher than suggested for the late Ordovician seawaters (0.7078～0.7080). The trace amounts of saddle dolomite cement in the Red River carbonates are probably related to "cannibalization" of earlier replacement dolomite during the chemical compaction.     

An Index mechanism for multi-scale view in spatial databases

There are numerous geometric objects stored in the spatial databases. An importance function in a spatial database is that users can browse the geometric objects as a map efficiently. Thus the spatial database should display the geometric objects users concern about swiftly onto the display window. This process includes two operations:retrieve data from database and then draw them onto screen. Accordingly, to improve the efficiency, we should try to reduce time of both retrieving object and displaying them. The former can be achieved with the aid of spatial index such as R-tree, the latter require to simplify the objects. Simplification means that objects are shown with sufficient but not with unnecessary detail which depend on the scale of browse. So the major problem is how to retrieve data at different detail level efficiently. This paper introduces the implementation of a multi-scale index in the spatial database SISP (Spatial Information Shared Platform) which is generalized from R-tree. The difference between the generalization and the R-tree lies on two facets: One is that every node and geometric object in the generalization is assigned with a importance value which denote the importance of them, and every vertex in the objects are assigned with a importance value,too. The importance value can be use to decide which data should be retrieve from disk in a query. The other difference is that geometric objects in the generalization are divided into one or more sub-blocks, and vertexes are total ordered by their importance value. With the help of the generalized R-tree, one can easily retrieve data at different detail levels.Some experiments are performed on real-life data to evaluate the performance of solutions that separately use normal spatial index and multi-scale spatial index. The results show that the solution using multi-scale index in SISP is satisfying.     

A computer generator for randomly layered structures

AcomputergeneratorforrandomlylayeredstructuresYUJia shun1,2,HEZhen hua2(1.TheInstituteofGeologicalandNuclearSciences,NewZealand;2.StateKeyLaboratoryofOilandGasReservoirGeologyandExploitation,ChengduUniversityofTechnology,China)Abstract:Analgorithmisintrod…     

海南岛地体及其毗邻陆缘晚中生代—新生代古地磁研究和构造演化

本文叙述了对海南岛及其毗邻大陆边缘白垩纪到第四纪地层岩石进行古地磁研究的全部工作过程。通过分析岩石中剩余磁矢量的磁偏角及磁倾角的变化,提出海南岛白垩纪以来经历的构造演化模式如下:早期伴随顺时针旋转而向南迁移,后期伴随逆时针转动并向北运移。联系该地区及邻区的地质、地球物理资料,对海南岛上述的构造地体运动提出以下认识:北部湾内早期有一拉张作用,主要是该作用使湾内地壳显著伸长减薄,形成北部湾盆地。从而导致了海南岛的早期构造运动,而海南岛后期的构造运动则主要是受南海海底扩张的影响。海南地体运动规律的阐明对于了解北部湾油气盆地的形成演化有重要的理论和实际意义。     

Exciton Seebeck in Molecular Systems

Various applications relevant to the exciton dynamics,such as the organic solar cell,the large-area organic light-emitting diodes and the thermoelectricity,are operating under temperature gradient.The potential abnormal behavior of the exicton dynamics driven by the temperature difference may affect the efficiency and performance of the corresponding devices.In the above situations,the exciton dynamics under temperature difference is mixed with     

Achieving Unusual States of Matter Under High Pressure

The elongation method,originally proposed by Imamura was further developed for many years in our group.As a method towards O(N)with high efficiency and high accuracy for any dimensional systems.This treatment designed for one-dimensional(ID)polymers is now available for three-dimensional(3D)systems,but geometry optimization is now possible only for 1D-systems.As an approach toward post-Hartree-Fock,it was also extended to     

《Chinese Science Bulletin》SUBJECT INDEX TO VOLUME 59(2014)

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An on-line scaling method for improving scalability of a database cluster

The explosive growth of the Internet and database applications has driven database to be more scalable and available, and able to support on-line scaling without interrupting service. To support more client's queries without downtime and degrading the response time, more nodes have to be scaled up while the database is running. This paper presents the overview of scalable and available database that satisfies the above characteristics. And we propose a novel on-line scaling method. Our method improves the existing on-line scaling method for fast response time and higher throughputs. Our proposed method reduces unnecessary network use, i.e. , we decrease the number of data copy by reusing the backup data. Also, our on-line scaling operation can be processed parallel by selecting adequate nodes as new node. Our performance study shows that our method results in significant reduction in data copy time.     

An improved R-tree based on childnode''s probability

R-Tree is a good structure for spatial searching. But in this indexing structure,either the sequence of nodes in the same level or sequence of traveling these nodes when queries are made is random. Since the possibility that the object appears in different MBR which have the same parents node is different, if we make the subnode who has the most possibility be traveled first, the time cost will be decreased in most of the cases. In some case, the possibility of a point belong to a rectangle will shows direct proportion with the size of the rectangle. But this conclusion is based on an assumption that the objects are symmetrically distributing in the area and this assumption is not always coming into existence. Now we found a more direct parameter to scale the possibility and made a little change on the structure of R-tree, to increase the possibility of founding the satisfying answer in the front sub trees. We names this structure probability based arranged R-tree (PBAR-tree).     

Integrating GIS Web services based on mediating architecture

The geographic information service is enabled by the advancements in general Web service technology and the focused efforts of the OGC in defining XML-based Web GIS service. Based on these models, this paper addresses the issue of services chaining,the process of combining or pipelining results from several interoperable GIS Web Services to create a customized solution. This paper presents a mediated chaining architecture in which a specific service takes responsibility for performing the process that describes a service chain. We designed the Spatial Information Process Language (SIPL) for dynamic modeling and describing the service chain, also a prototype of the Spatial Information Process Execution Engine (SIPEE) is implemented for executing processes written in SIPL. Discussion of measures to improve the functionality and performance of such system will be included.