基于MRSVD-SVD与VPMCD的交叉滚子轴承故障诊断研究

针对奇异值分解(SVD)提取工业机器人交叉滚子轴承振动信号微弱故障特征分量时,出现奇异值分辨率不足的问题,提出了一种基于最大分辨率奇异值分解(MRSVD)-奇异值分解(SVD)与变量预测模型模式识别(VPMCD)的工业机器人交叉滚子轴承的故障诊断方法。首先,以最大奇异值分辨率原则将一维振动信号构造成了Hankel矩阵,采用奇异值分解方法对Hankel矩阵进行了分解,得到了其奇异值序列,根据奇异值曲率谱理论选择有效奇异值,并进行了重构,得到了经降噪后的高信噪比信号,以重构信号构建了相空间矩阵,进行了二次奇异值分解,得到了其故障特征分量;然后,计算了故障特征分量的特征参数,构建了其特征向量;最后,采用了VPMCD分析了特征向量,完成了对交叉滚子轴承故障类型的识别,并与其它方法进行了识别准确率对比。研究结果表明：采用该方法对工业机器人交叉滚子轴承进行故障诊断,得到的故障类型识别准确率为98.66%,比SVD与共振解调相结合方法提高了9%;该方法通过构建最大奇异值分辨率矩阵提高了奇异值分辨率,可完整提取出工业机器人交叉滚子轴承振动信号的微弱故障特征分量,获得了更高的故障类型识别准确率。     

轴承振动信号中调幅特征的奇异值分解提取方法

滚道损伤会在轴承振动中引起调幅现象,但当损伤较轻微或者噪声干扰较严重时,这种特征难以显现出来.提出利用奇异值分解(Singular value decomposition,SVD)来提取这种调幅特征.在Hankel矩阵方式下,SVD可将信号分解为一系列分量信号的简单线性叠加.利用这一特件,对轴承振动信号构造Hankel...     

IVMD融合奇异值差分谱的滚动轴承早期故障诊断

针对滚动轴承早期故障阶段存在特征信号微弱、故障识别相对困难的问题,提出了融合改进变分模态分解和奇异值差分谱的诊断方法。原始信号经改进变分模态分解方法处理后,被分解为若干本征模态函数分量,利用包络谱稀疏度指标筛选出最佳分量构造Hankel矩阵并进行奇异值分解,求取奇异值差分谱后,根据差分谱中的突变点重构信号,最终通过分析信号的包络谱可判断轴承的故障类型。利用改进变分模态分解融合奇异值差分谱的方法对轴承故障模拟及实测信号进行分析,均成功提取出微弱特征信息,能够实现滚动轴承早期故障的有效判别,具有一定的可靠性和应用价值。     

基于奇异值分解的ERA改进算法及模态定阶

研究了一种基于奇异值分解的ERA改进算法和模态定阶方法。在奇异值分解基础上,根据选定阶次在动态系统中所占比重,提出一种模态定阶指标——奇异值百分比,将该指标应用在改进后的特征系统算法中。首先,利用脉冲响应信号构造初始Hankel矩阵,对此矩阵进行奇异值分解生成去噪后的信号矩阵;其次,根据Cadzow算法重构Hankel矩阵;最后,利用奇异值指标确定模态阶次。通过仿真算例验证了改进后的特征系统实现算法具有良好的抗噪能力,利用定阶指标能有效确定模态阶次、剔除虚假模态,对于阻尼识别精度更高。应用该方法对某三厢车排气系统进行了模态参数识别,通过与LMS系统识别结果比较验证了方法的准确性。     

奇异值差分谱理论及其在车床主轴箱故障诊断中的应用

证明采用Hankel矩阵时奇异值分解(Singular value decomposition,SVD)可以将信号分解为一系列分量信号的简单线性叠加,为了确定其中的有用分量个数,提出奇异值差分谱的概念。差分谱可以有效地描述有用分量和噪声分量的奇异值性质差异,根据差分谱峰值位置可实现对有用分量个数的确定。研究结果表明,当差分谱最大峰值位于第一个坐标时,则表明原始信号存在较大的直流分量,此时根据第二最大峰值位置可以确定有用分量的个数,否则就根据最大峰值位置来确定分量个数。利用差分谱进一步研究Hankel矩阵的结构对SVD降噪效果的影响,指出矩阵列数和噪声去除量存在抛物线状的对称关系。利用基于差分谱的SVD方法对车削力信号进行处理,结果有效地分离出由于主轴箱故障齿轮的振动而引起的调制信号,并根据此信号可靠地定位了故障齿轮。     

奇异值熵和支持向量机的齿轮故障诊断

提出了一种基于总体平均经验模态分解(ensemble empirical mode decomposition,简称EEMD)奇异值熵和支持向量机的齿轮故障诊断方法.首先,通过EEMD方法将非平稳的原始加速度振动信号分解成若干个平稳的本征模式分量,将得到的若干个本征模式分量自动形成初始特征向量矩阵;然后,对该矩阵进行奇异值分解,提取其奇异值作为故障特征向量,并对其进行归一化,求得奇异值熵,根据奇异值熵值大小可以判断齿轮的故障类型;最后,将奇异值故障特征向量作为支持向量机的输入,判断齿轮的工作状态和故障类型.试验结果表明,即使在小样本情况下,基于EEMD奇异值分解和支持向量机的故障诊断方法仍能有效地识别齿轮的工作状态和故障类型.     

基于局部特征尺度分解和奇异值差分谱的滚动轴承故障诊断方法

为有效消除滚动轴承故障振动信号中噪声,更好提取故障特征频率,提出了基于局部特征尺度分解和奇异值差分谱的故障诊断方法。该方法首先利用局部特征尺度分解将非平稳信号分解成若干个不同频带的内禀尺度分量;然后对包含故障特征的分量构造Hankel矩阵并进行奇异值分解并求得奇异值差分谱曲线,利用差分谱最大突变点确定重构信号的阶数并重构信号;最后再求重构信号的包络谱,便可准确获得相应故障特征频率。滚动轴承故障诊断的试验结果证明,该方法能快速准确地提取出故障信息,具有一定的优势。     

VMD和奇异差分谱在齿轮早期故障诊断中的应用

针对齿轮故障振动信号的多分量、多频率调制特性且早期故障振动信号信噪比低,故障特征微弱难以提取的问题,提出了基于变分模态分解(Variational Mode Decomposition,VMD)和奇异值差分谱的故障诊断方法。首先对采集到的齿轮故障振动信号进行VMD分解,得到一系列窄带本征模态分量(band-limited intrinsic mode functions,BLIMFS),由于噪声的干扰,从各个模态分量的频谱中很难对故障做出正确的判断;然后根据相关系数准则,选取与原始信号相关系数较大的分量构建Hankel矩阵并进行奇异值分解,求取奇异值差分谱,从差分谱中确定重构信号的有效阶次对信号进行降噪处理;最后对降噪处理后的信号进行Hilbert包络谱分析,即可从中准确地识别出齿轮的故障特征频率。仿真信号和齿轮箱齿轮故障模拟实验结果表明,该方法能够有效地降低噪声的影响,准确地提取到齿轮微弱的故障特征信息。     

基于EEMD奇异值熵的滚动轴承故障诊断方法

为充分利用振动信号进行故障辨识,提出一种基于集合经验模态分解(ensemble empirical mode decomposition,简称EEMD)奇异值熵判据的滚动轴承故障诊断方法。首先,对滚动轴承的振动信号进行EEMD分解获得若干个本征模态函数(intrinsic mode function,简称IMF),并根据一种IMF分量故障信息含量的评价指标(即峭度、均方差和欧氏距离)选出能够表征原始信号状态的分量进行信号重构;其次,利用奇异值分解技术对重构信号进行处理,结合信息熵算法求取其奇异值熵;最后,利用奇异值熵的大小判断滚动轴承的故障类别。用美国西储大学滚动轴承振动信号对所述方法进行验证的结果表明,相比传统的EMD奇异值熵故障诊断方法,本方法能够清晰的划分出滚动轴承不同工作状态的类别特征区间,而且具有更高的故障诊断精度。     

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。     

Minimal Realization of Linear Graph Models for Multi-physics Systems

An engineering system may consist of several different types of components,belonging to such physical"domains"as mechanical,electrical,fluid,and thermal.It is t...     

Quantum Cooperative Robotics and Autonomy

The intersection of Quantum Technologies and Robotics Autonomy is explored in the present paper.The two areas are brought together in establishing an interdisci...     

考虑进油孔有限长滑动轴承油膜力的近似解析解

针对具有进油孔的有限长滑动轴承油膜力求解问题,采用变分原理和分离变量法,求得了有限长滑动轴承油膜压力分布的近似解析表达式。将油膜压力分布的近似解析表达式在油膜存在区域上进行积分,即得到了油膜力。将提出的计算有限长滑动轴承油膜力方法与无限长轴承模型、有限元方法的计算结果进行了比较,发现了提出的方法与有限元方法的计算结果很接近。最后,研究了进油孔位置和进油压力对油膜存在区域、油膜力等的影响,研究结果表明进油孔位置和进油压力对油膜存在区域和油膜力有较大的影响。     

三绕组变压器的双绕组等效建模及在Matpower中的应用

针对实际电网存在着大量的三绕组变压器,但国际上一些著名商业软件,如BPA仿真软件、Matpower这一权威潮流计算开源软件,均只提供双绕组变压器模型,限制了其在具有三绕组变压器的电力系统中的应用的问题,潮流计算是自主开发的电力系统各种应用软件的核心模块,因此依托国际权威开源程序进行二次开发,是一种较好的选择。对Matpower要求的数据格式进行了归纳,对变压器的一般的等值电路及带理想变压器的等值电路和带标幺值的等值电路进行了分析研究,提出了三绕组变压器转换为双绕组等效模型的建模方法,使得原先只适应双绕组变压器的潮流计算软件可以适用于三绕组变压器电网的潮流计算;最后以Matpower软件为例进行了案例计算,并用PSASP仿真软件进行对比验证。研究结果证明,所提出的建模方法是有效的。     

On the Relation of Load to Average Gap in the Contact Between Surfaces with Longitudinal Roughness

A computer simulation model for the contact between longitudinally-oriented rough surfaces has been formulated. This model closely duplicates the actual surf ace contact deformation behavior by taking into account the elastic interactions between the asperities. There were no assumptions made about the shapes, or any deformation behavior of the asperities, except for their obeying the laws of elasticity. The plastic deformations on the high asperity peaks were taken into account by setting a ceiling on their contact pressures at the material hardness value. The simulations used real surface profiles which were digitized from unworn circumferentially ground steel surfaces. Each pair of these profiles was mathematically combined to form an equivalent rough profile pressing against an infinitely rigid flat and having the appropriately adjusted elastic modulus. A total of 28 different pairs of profiles were used in the simulations. Each contacting pair was subjected to 30 different load levels and the local contact pressures and deformations were calculated. The contact simulations yielded some important mathematical relationships between parameters, such as the real area of contact, average gap, and average asperity load through statistical curve fitting. Two analytical functions were generated to relate the average load to average gap and the real area of contact to load.     

INTEGRAL EQUATION METHOD＇S APPLICATION IN HOLE-EDGE STRESS OF COMPOSITE MATERIAL PLATE WITH DIFFERENT SHAPED HOLES

The strength of composite plate with different hole-shapes is always one of the most important but complicated issues in the application of the composite material. The holes will lead to mutations and discontinuity to the structure. So the hole-edge stress concentration is always a serious phenomenon. And the phenomenon makes the structure strength decrease very quickly to form dangerous weak points. Most partial damage begins from these weak points. According to the complex variable functions theory, the accurate boundary condition of composite plate with different hole-shapes is founded by conformal mapping method to settle the boundary condition problem of complex hole-shapes. Composite plate with commonly hole-shapes in engineering is studied by several complex variable stress fimction. The boundary integral equations are founded based on exact boundary conditions. Then the exact hole-edge stress analytic solution of composite plate with rectangle holes and wing manholes is resolved. Both of offset axis loadings and its influences on the stress concentration coefficient of the hole-edge are discussed. And comparisons of different loads along various offset axis on the hole-edge stress distribution of orthotropic plate with rectangle hole or wing manhole are made. It can be concluded that hole-edge with continuous variable curvatures might help to decrease the stress concentration coefficient; and smaller angle of outer load and fiber can decrease the stress peak value.     

电站锅炉模糊风险评价方法研究与应用

针对电站锅炉风险等级评价问题,将模糊综合评价技术应用到电站锅炉风险等级评价中。开展了电站锅炉失效影响因素及模糊评价因素的重要程度分析,建立了一套科学合理适于在线评价的电站锅炉风险评价体系,提出了模糊综合评价技术与改进的模糊层次分析法相结合的模糊风险评价方法,利用改进的模糊层次分析法计算了指标体系中各层指标权重。对某一台电站锅炉的实际运行工况影响子因素进行了模糊风险评价,采用模糊合成算子进行模糊综合运算得到电了站锅炉运行工况影响子因素的评价向量。研究结果表明:电站锅炉的运行工况影响子因素的风险评价等级为第6级,失效可能性等级为小,该电站锅炉运行工况良好。     

Non-monotonic material contrast in scanning ion and scanning electron images

30 keV Ga⁺ focused ion beam induced secondary electron (iSE) imaging was used to determine the relative contrast between several materials. The iSE signal compared from C, Si, Al, Ti, Cr, Ni, Cu, Mo, Ag, and W metal layers does not decrease with an increase in target atomic number Z₂, and shows a non-monotonic relationship between contrast and Z₂. The non-monotonic relationship is attributed to periodic fluctuations of the stopping power and sputter yield inherent to the ion–solid interactions. In addition, material contrast from electron-induced secondary electron (eSE) and backscattered electron (BSE) images using scanning electron microscopy (SEM) also shows non-monotonic contrast as a function of Z₂, following the periodic behavior of the stopping power for electron–solid interactions. A comparison of the iSE and eSE results shows similar relative contrast between the metal layers, and not complementary contrast as conventionally understood. These similarities in the contrast behavior can be attributed to similarities in the periodic and non-monotonic function defined by incident particle–solid interaction theory.     

Short-Term Relay Quality Prediction Algorithm Based on Long and Short-Term Memory

The fraction defective of semi-finished products is predicted to optimize the process of relay production lines, by which production quality and productivity ar...     

End-to-End Multiview Gesture Recognition for Autonomous Car Parking System

The use of hand gestures can be the most intuitive human-machine interaction medium.The early approaches for hand gesture recognition used device-based methods....