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《仪表技术与传感器》2016,(11)
为了提高磁轴承转子故障诊断结果的可靠性,提出了基于D-S信息融合的故障诊断方案:首先选择轴心轨迹作为初步判断,然后以EEMD为基础,分别对多组振动信号的边际谱进行特征频段能量的计算,采用BP神经网络进行故障识别,其结果再经过D-S证据理论做决策融合,最终确定磁轴承转子的故障类型。实验结果表明该方案提高了故障诊断结果的准确性,充分显示了其应用在磁轴承转子故障诊断系统中的可行性。 相似文献
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为实现对不同工况下的齿轮皮带系统中不同齿轮故障的诊断与分类,将不同故障状态的齿轮和不同松紧程度的皮带组合进行多状态模拟实验,采集各种状态下的齿轮振动信号,提取具有明确物理意义的振动信号倍频能量作为特征向量,最后分别采用径向基函数(Radial Basis Function,RBF)神经网络和支持向量机(Support Vector Machine,SVM)对不同皮带张紧状态下齿轮故障进行诊断分类,并将两种方法诊断的结果进行比较。研究结果表明,振动信号的倍频能量能够较好地反映齿轮的故障特征,RBF神经网络和SVM都能有效地识别齿轮的故障类型,SVM对于齿轮皮带系统的故障诊断准确率相对更高。 相似文献
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《仪表技术与传感器》2015,(12)
故障诊断信息融合过程可表述为检测层、特征层和决策层的信息融合。文中根据磁轴承转子振动分析的特点,提出了信息融合的故障诊断方案:检测层的融合创新性采用了基于小波分析的加权算法,特征层以希尔伯特-黄变换(HHT)分析法为基础,对边际谱进行特征频段能量的计算,采用BP神经网络对磁轴承转子故障类型进行特征层的识别诊断。决策层采用经典的D-S证据理论,对特征层获得的多个诊断结果做决策融合处理,最终确定磁轴承转子的故障类型。实验结果表明该方法有效地提高了故障诊断结果的可靠性,充分显示了该系统方案的有效性。 相似文献
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对滚动轴承的故障类型识别已有很多研究,但很少涉及到其故障等级,即损伤程度的检测与识别。文中采用小波包多层分解的方法,提取滚动轴承的振动信号的能量谱,经归一化后,结合RBF为核函数的支持向量机,对美国Case Western Reserve大学的轴承数据中心的滚动轴承规范数据集进行研究测试,取得很好的实验效果。 相似文献
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结合切片谱和RBF神经网络提出一种切片谱RBF神经网络旋转机械故障诊断方法。该方法以信号的切片谱为故障特征量,以RBF神经网络为分类器,进行旋转机械故障诊断。轴承故障的诊断结果表明,该方法是可行和有效的。 相似文献
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《计算机集成制造系统》2017,(10)
有效特征向量的提取与故障诊断方法是实现航空发动机转子故障快速正确诊断的关键。首先根据航空发动机转子振动信号的非平稳及非线性的特点,应用小波变换和Hilbert-Huang变换方法提取振动信号的有效值、边际谱重心和小波变换最大能量层的功率谱重心三个特征向量,然后应用双阶自适应小波聚类方法对航空发动机转子进行多类型混合故障诊断。结果表明双阶自适应小波聚类方法能快速准确地实现故障分类与识别,尤其对于密度分布不均匀的多类型混合数据,诊断精度显著高于传统的小波聚类方法。 相似文献
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针对变负载情况下滚动轴承故障信息难以提取、故障诊断精度低等问题,提出了一种基于包络谱灰色关联度的集合经验模态分解(EEMD)、核主元分析(KPCA)与径向基神经网络(RBF)相结合的滚动轴承故障诊断方法。该方法首先采用包络谱灰色关联度算法选择EEMD分解后的有效IMF分量,并对IMF分量进行加权,然后计算出加权后IMF分量的能量、峭度、偏度组成特征集,最后采用KPCA对特征集进行降维并将去除冗余后的特征集输入RBF中进行故障程度识别,实验结果表明此方法可以在变负载情况下有效的实现滚动轴承的故障程度的识别。 相似文献
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Clarence W.DE SILVA 《Instrumentation》2019,(4):72-84
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... 相似文献
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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. 相似文献
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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... 相似文献
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分布动态载荷识别的抗噪处理 总被引:2,自引:2,他引:0
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. 相似文献
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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。 相似文献
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J. A. Williams 《Lubrication Science》1997,3(3):267-306
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. 相似文献
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M. Stedman 《Journal of microscopy》1988,152(3):611-618
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. 相似文献
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Fractional order nonsingular terminal sliding mode control for flexible spacecraft attitude tracking
This paper investigates a fractional terminal sliding mode control for flexible spacecraft attitude tracking in the presence of inertia uncertainties and extern... 相似文献
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以德士古气化炉耐火砖的内壁蚀损检测设备为基础,对采集到的点云数据做了进一步处理.通过对数据的筛选和剔除,实现了数据点的平滑降噪细化和精简.然后利用点云对整、网格划分和分色显示等方法,最终完成了内壁腐蚀情况的三维建模.重点讨论了点云数据的预处理及后处理的方法,并根据内壁耐火砖的腐蚀阈值,提出了一种气化炉内壁腐蚀区域的识别与分割方法.对耐火砖的腐蚀分析、气化炉的生产与维修提供了可靠依据,并在工程应用中获得了一致认可. 相似文献