基于改进形态分量分析的滚动轴承包络分析方法

滚动轴承出现局部损伤时,其振动信号既包含轴承自身原因引起的谐振分量,也包含故障信息的冲击分量和噪声分量。谐振分量为信号中的相对平滑部分,其品质因子较高;冲击分量表现为信号中的瞬态成分,其品质因子较低。针对这一特点,利用可调品质因子小波变换稀疏表示信号,提出一种改进形态分量分析方法,并将其应用于滚动轴承的包络分析中。采用可调品质因子小波作为稀疏表示字典,实现不同分量的分离,并对冲击分量进行包络分析,判断滚动轴承故障。滚动轴承故障实验表明,该方法能够有效提取故障特征,诊断轴承出现的故障类型。     

基于小波降噪与RSSD的滚动轴承故障特征提取技术研究

滚动轴承故障振动信号呈现出非线性、非平稳性及噪声背景较强等特点,为了有效提取故障特征,提出了一种小波降噪与共振稀疏分解(Resonance-based sparse signal decomposition,RSSD)相结合的振动信号特征提取技术。共振稀疏分解是基于品质因子可调小波变换与形态分量分析的一种新的信号分解方法,与常规的基于频带划分的信号分解方法不同,它依据信号各分量的振荡形态不同对信号进行分解。先通过小波阈值降噪方法明显减小信号中的噪声,随后对降噪后的信号进行共振稀疏分解,将信号分为不同共振特性的分量,即具有持续振荡特性的高共振分量和具有瞬态冲击特性的低共振分量。最后通过对分解所得到的低共振分量采用Hilbert包络解调方法提取冲击故障特征。将该方法分别应用于仿真信号和轴承实验台故障冲击性实例,验证了该方法的有效性。     

基于形态分量分析和包络谱的轴承故障诊断

滚动轴承出现局部损伤时,其振动信号往往由包含轴承自身振动的谐振分量、包含轴承故障信息的冲击分量及随机噪声分量构成。提出了基于形态分量分析和包络谱的滚动轴承故障诊断方法。该方法根据轴承振动信号中各组成成分的形态差异,利用改进的形态分量分析对滚动轴承故障振动信号中的谐振分量、冲击分量和噪声分量进行分离,然后对冲击分量进行Hilbert包络解调分析,根据包络谱诊断滚动轴承故障。算法仿真和应用实例表明,该方法能有效提取滚动轴承故障特征。     

基于最优 IMF 分量和 K-SVD 的滚动轴承故障声音信号特征提取

针对滚动轴承声音信号中周期性冲击故障特征难提取的问题,提出了基于最优 IMF 分量与 K-SVD 字典学习相结合的轴承故障特征提取方法。首先,利用 VMD 分解原始信号获得一系列 IMF 分量;其次,利用 SAF 指标自适应选取最优 IMF 分量,并作为训练信号;最后,利用 K-SVD 字典学习方法训练出字典库,通过正交匹配追踪算法( OMP )对原始信号处理得到稀疏信号,并对稀疏信号进行包络谱分析。仿真及实验结果表明,对比传统 K-SVD 字典学习方法,该方法得到的稀疏信号信噪比( SNR )更高,能更准确地提取滚动轴承周期性冲击,增强了轴承故障特征。     

声信号形态分量分析在轴承故障诊断中的应用

滚动轴承是工业领域旋转机械中最重要的零部件,也是机器中最易损坏的零件之一,其工作表面发生局部缺陷时会产生异常声响。实际的滚动轴承故障声信号信噪比差,成分复杂,信号中的冲击成分、谐振成分及噪声无法被任意单一的字典充分表示。在分析该信号时频特性的基础上,提出了一种基于声信号MCA和Hilbert谱分析的轴承故障诊断新方法。该方法通过构建一个冗余字典来逼近故障声信号,利用形态分量分析稀疏分离出故障声信号中的冲击分量、谐振分量和噪声分量三种成分,并对冲击分量进行Hilbert谱分析。经仿真和实例分析,得出该方法能准确识别滚动轴承故障的结论。     

盲解卷积和频域压缩感知在轴承复合故障声学诊断的应用

针对时域盲解卷积算法对单一故障机械声信号有效,及传统稀疏分量分析对声信号分析失效等问题,提出一种盲解卷积、形态滤波和频域压缩感知重构的稀疏分量分析相结合的轴承复合故障声学诊断方法。通过时域盲解卷积算法优选分量结果,提取声信号的冲击成分。使用形态滤波滤除背景噪声。使用模糊C均值聚类估计混合矩阵,重构传感矩阵,并运用稀疏度自适应匹配追踪基算法(Sparsity adaptive matching pursuit,SAMP)的频域压缩感知重构分离信号。双通道滚动轴承故障声信号分析结果表明该方法能够有效分离和提取滚动轴承故障特征。     

基于形态分量分析与能量算子解调的齿轮箱复合故障诊断方法

针对齿轮箱复合故障的故障特征分离,提出了一种基于形态分量分析与能量算子解调的齿轮箱复合故障诊断方法。该方法先根据振动信号中各组成成分形态的差异,采用形态分量分析方法构建不同形态的稀疏表示字典进行故障成分分离,将齿轮箱复合故障信号分解为包含齿轮故障信息的谐振分量、包含轴承故障信息的冲击分量和噪声分量,然后分别对谐振分量和冲击分量进行能量算子解调分析,最后根据各解调谱诊断齿轮和轴承故障。算法仿真和应用实例表明该方法能有效地分离齿轮箱复合故障振动信号中齿轮与轴承的故障特征。     

基于共振稀疏分解的滚动轴承早期微弱故障诊断

传统方法很难对滚动轴承的早期微弱故障进行有效诊断.共振稀疏分解是一种基于多字典库的稀疏分解方法,可以同时分解出滚动轴承故障信号中的瞬态冲击成分及其持续震荡成分(工频及其谐频成分).该方法在对滚动轴承早期微弱故障信号进行自适应滤波降噪(采用Ensemble Empirical Mode Decomposition,EEMD方法)基础上,对处理后的信号进行共振稀疏分解分析,分别构建高、低品质因子小波基函数字典库,并利用形态学分析方法建立信号稀疏表示的目标函数,进而实现对滚动轴承发生故障时具有低品质因子的瞬态故障成分及其他持续振荡高品质因子噪声成分的成功分离.对分离得到的低品质因子信号成分进行包络解调分析,进而得到较好的故障提取特征结果.通过实验验证了所述方法的有效性.     

改进辛几何模态分解的滚动轴承故障特征提取

针对滚动轴承故障冲击信号难以提取的问题,提出了一种改进辛几何模态分解（Improved Symplectic Geometry Modal Decomposition,ISGMD）滚动轴承故障特征提取方法。首先将振动信号进行辛几何模态分解,然后,利用k均值聚类的方法对分解得到的辛几何分量进行聚类,通过包络谱稀疏度指标筛选出故障特征明显的聚类辛几何分量（Cluster Symplectic Geometry Component,CSGC）并进行重构,对重构分量进行包络解调,提取出故障特征。将该方法运用到轴承故障仿真和实验信号,结果表明,这里提出的方法能够有效提取出滚动轴承故障特征。     

基于过完备字典的基追踪法在轴承故障诊断中的应用

滚动轴承故障具有信号复合和环境噪声大的特点。通过构建一个对复合信号敏感的过完备字典,利用基追踪法对故障信号进行最优化的稀疏表示,获得简洁的故障冲击时频特征结构,并实现阈值降噪。通过对重构信号谱分析后得到明确的故障特征频率及其倍频。仿真与实验结果表明:该方法具有良好的降噪功能,能够准确地提取信号中的冲击特征。     

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...     

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.     

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.     

Application of Feature Extraction through Convolution Neural Networks and SVM Classifier for Robust Grading of Apples

This paper proposes a novel grading method of apples,in an automated grading device that uses convolutional neural networks to extract the size,color,texture,an...     

分布动态载荷识别的抗噪处理

针对正交多项式频域法在用多种响应对矩形薄板进行载荷识别中抗噪性较差的问题,综合运用平均法、矩阵预处理和奇异值截断法等方法对之进行改善,并引入空间映射的思想,将该方法的应用范围拓展为复杂的模型.利用仿真算例,证实了该方法具有较好的抗噪性.     

基于MELTAC-N平台的核电厂安全级DCS环网研究与测试

针对工程实践中环网通讯相关问题的处理缺乏理论基础及国产化安全级DCS平台的开发缺乏成熟经验借鉴问题,对基于MELTAC-N平台核电厂安全级DCS环网的软硬件实现进行了研究。提出了安全级DCS环网双环网冗余设计、光切换开关设计等硬件设计方法,以及以RPR协议为基础,采用全数据收发策略的软件设计方法。在CPR1000安全级DCS平台上对安全级DCS环网的可靠性及实时性进行了评价,并进行了容错能力、响应时间及响应时间稳定性测试验证实验。结果表明,基于MELTAC-N平台安全级DCS环网软硬件设计具有较好的容错能力及响应时间稳定性。     

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....     

The laboratory simulation of abrasive wear

Abrasive wear has long been recognised as one of the most potentially serious tribological problems facing the operators of many types of plant and machinery; several industrial surveys have indicated that wear by abrasion can be responsible for more than 50% of unscheduled machine and plant stoppages. Locating the operating point of a tribological contact in an appropriate operational ‚map’︁ can provide a useful guide to the likely nature and origins of the surface degradation experienced in use, though care must be exercised in choosing the most suitable parameters for the axes of the plot. Laboratory testing of materials and simulations of machine contacts are carried out for a number of purposes; at one level for the very practical aims of ranking candidate materials or surface hardening treatments in order of their wear resistance, or in an attempt to predict wear lives under field conditions. More fundamentally, tests may be aimed at elucidating the essential physical mechanisms of surface damage and loss, with the longer term aim of building an analytical and predictive model of the wear process itself. In many cases, component surface damage is brought about by the ingress of hard, particulate matter into machine bearing or sealing clearances. These may be running dry although, more usually, a lubricant or service fluid is present at the interface. A number of standardised wear test geometries and procedures have been established for both two- and three-body wear situations, and these are briefly described. Although abrasive wear is often modelled as following an ‚Archard’︁ equation (i.e. a linear increase in material loss with both load and time, and an inverse dependence on specimen hardness) both industrial experience and laboratory tests of particularly lubricated contacts show that this is not always the case: increasing the hardness differential in an abrasively contaminated lubricated pair may not always reduce the rate of damage to the harder surface.     

Limits of topographic measurement by the scanning tunnelling and atomic force microscopes

Parameters describing the topographic character of a surface (height, surface wavelength, slope and curvature) can be derived from equivalent sinusoidal profiles. The response of a surface-measuring instrument may be modelled in terms of instrument parameters such as stylus radius, and scanning range and resolution. The performance of the instrument may then be mapped as a zone in amplitude-wavelength (AW) space to show the sinusoidal profiles it is capable of measuring. In a first-order analysis the STM and AFM are considered as equivalent to contact-stylus instruments with a notional stylus radius equal to the tip radius plus the gap. Comparisons between different instruments and types of instrument are readily made by mapping in AW space. The error arising from convolution of the sinusoidal profile with that of the finite tip may be quantified and plotted as contours in AW space.