油液磨粒检测传感器线圈间距对输出信号的影响

电感式磨粒传感器在机械设备润滑油液磨粒在线监测中具有独特优势,通过测量传感器输出的感应电压信号来获取油液中磨粒的大小、数量以及质量等信息,进而可实现设备磨损程度的判断。为了研究电感式三线圈传感器中相邻两线圈之间的距离对传感器输出感应信号的影响,基于差动式三线圈互感原理建立传感器三维模型;利用JMAG-Designer12.0软件对传感器检测铁磁磨粒的过程进行瞬态电磁仿真,分析线圈间距对传感器输出感应电动势的影响;通过制作传感器进行实验并行验证仿真结果的正确性。研究结果表明,当线圈间距小于2.5 mm时,感应电动势随间距的增加而增大,当线圈间距大于2.5 mm时,感应电动势随间距的增加而减小,线圈间距为2.5 mm时,感应电动势最大,传感器输出信号与理论正弦信号变化趋势接近一致,并且信号干扰最小、信号最为稳定。     

基于在线铁谱图像的磨损机理智能辨识

基于状态的维护(Condition based maintenance,CBM)理念为机器健康状态维护提出了实时监测的新挑战。现有研究由于缺乏在线信息获取手段,磨损状态监测逐渐成为CBM的技术瓶颈。基于特征磨粒的磨损机理判断方法已经被广泛应用在离线磨损分析中,但是在线磨损机理的表征依然是一个很大的问题。针对基于在线铁谱图像的磨损机理开展研究。为了在一副在线铁谱图像中获得分离的磨粒图像,研究磨粒在在线铁谱传感器中的沉积机理。研究结果表明,磨粒链是图像中的主要形态,这是由于先前沉积的磨粒产生的局部磁场所致。设计一种依靠自适应调节沉积时间的在线磨粒沉积方法。运用该方法可以在在线铁谱图像中获得分离的磨粒,为特征磨粒的特征辨识提供了便利。参考分析铁谱知识,提取特征磨粒的4种形态学特征(当量尺寸、长径比、形状因子和分形维数)以综合表征4种典型磨损机理,包括正常、切削、疲劳、严重滑动磨损。采用反馈式人工神经网络构建自动磨损机理辨识模型。采用离线铁谱图像样本验证所建模型,结果表明该模型可以识别在线磨粒图像中的特征磨粒。对在线磨损机理表征方法进行了有意义的探索,所得研究成果将为在线磨损状态表征提供可行方法。     

基于铣床主轴弯扭力学信号的铣刀磨损状态监测方法研究

为了及时检测出急剧磨损的铣刀,提高加工效率,保证工件精度和表面质量,设计了一种基于机床主轴弯矩与扭矩信号的铣刀磨损状态监测方法,利用主轴上的扭矩和弯矩传感器对加工过程中的刀具进行实时在线测量,并对采集到的数据进行处理。试验结果表明,将切削力信号融合提取特征作为输入信号,可以提高刀具磨损状态识别的准确性,能够直接和准确地反映刀具磨损状态。     

机械磨损过程的在线监测

润滑油中含有丰富的机械零件磨损过程的信息,特别是分布在油中的磨粒直接反映了零件磨损量与状态信息,因此通过采集润滑油中的磨粒,可获取机械的磨损过程信息.根据对油中磨粒检测的需要,设计了磨粒传感器,并对其进行了特性试验.同时论述了对油中磨粒检测的检测方法,和检测系统的软/硬件结构.试验及应用表明,根据检测油液中的磨粒的含量和产生速率与预置数据进行对比分析,获取零件的磨损过程信息,可以准确地判断机械的磨损过程.     

基于模糊数据融合的控制棒包壳管磨损状态评估

核电站反应堆控制棒组件在服役期间与导向架摩擦造成包壳管外表面磨损,对反应堆的安全运行造成极大隐患,严重时甚至可能引起核安全事故。利用控制棒包壳管超声和涡流检测信息提取信号特征值对其磨损状态进行评估,因单一特征信号反映的控制棒包壳管状态信息存在局限性,采用模糊数据融合方法对超声、涡流检测特征信号进行融合,获得更加全面、准确的包壳管磨损状态。实验结果表明,基于模糊数据融合的包壳管磨损状态评估比单一传感器对包壳管磨损状态评估更为可靠。     

电感式油液磨粒传感器系统设计

油液中的磨粒可反映发动机等设备的磨损状况,为实现油液金属磨粒的在线监测,基于电磁感应原理建立了三线圈传感器的数学模型,通过仿真分析传感器最佳结构参数(内径、间隙、宽度等),利用相干解调模型提取磨粒信号,并分析磨粒信号产生原理.系统采用多层屏蔽结构,可有效减少外部的磁场干扰,设计的传感器检测系统接入风机齿轮箱油路进行相关试验.试验结果表明,本系统可对磨粒信号进行有效提取,且磨粒信号同时受磨粒速度及磨粒尺寸的影响,可在流量为1～18 L/min的工况下实现187 μm铁磁性金属磨粒和578 μm非铁磁性金属磨粒的检测,后续可结合BP神经网络对油液金属磨粒各特征参数进行自适应判别,对今后油液磨粒在线监测设备的开发提供了理论支撑及技术支持,为机械设备故障诊断提供重要依据.     

电感式磨粒传感器中铁磁质磨粒特性仿真研究

针对机械装置的在线监测传感器,模拟了铁磁质磨粒通过传感器过程中传感器线圈的磁场和感应线圈的感应电压瞬态变化特性.考虑了线圈与铁磨粒的材料、线圈匝数和激励线圈的输入电压等因素,应用Jmag Designer I0.4软件建立了传感器的二维有限元模型.仿真结果揭示了磨粒运动过程中线圈磁场与感应线圈中感应电压的变化规律,获得了感应电压与球形磨粒的直径大小的立方成正比,与磨粒运行速度成正比.研究结果对于电感式磨粒传感器的开发具有重要的指导价值.     

自适应随机共振算法的立铣刀磨损信号检测

在对刀具磨损信号的检测过程中,强噪加工环境使得所需特征信号显得非常微弱,给提取微弱特征信号带来了难题,基于此问题提出了利用自适应随机共振算法对立铣刀在磨损过程中产生的磨损信号进行检测,用加速度传感器和力传感器采集振动信号和切削力信号,再将提取的信号进行时频域的特征值提取,以此来分别建立遗传算法和粒子群算法优化的自适应随机共振模型,最后将这两种模型都用在对立铣刀的磨损检测中。实验结果表明,遗传算法和粒子群算法均可检测出立铣刀转动频率和刀齿切入频率,以及这两种频率下所对应的立铣刀磨损信号,为日后立铣刀磨损状态在线监测系统的建立奠定了基础。     

基于磁电传感器的转子偏心距检测

为了解决现有转子偏心检测方法系统建模复杂、多路信号同步采集存在相位误差的问题，提出了一种基于磁电传感器的偏心检测方法。首先分析了磁电传感器检测机理，得到磁电传感器电压与感应间隙之间的函数关系，改变信号盘结构设置键相信号并推导磁电传感器键相信号电压波形。针对传感器键相信号电压波形，设计转子偏心距检测算法。并以DSP28335微控制器为核心，搭建硬件检测系统对该检测方法进行验证。在不同转速的情况下得到转子偏心距参数。结果表明：该偏心距检测方法能够准确的对转子偏心状态进行检测，对工程具有一定的实践意义。     

基于Faster R-CNN的齿轮箱铁谱磨粒识别

在利用铁谱技术对齿轮箱磨损状态进行评估时,存在磨粒特征提取困难且磨粒识别的数量有限的问题,基于铁谱磨粒图像特性,提出基于Faster R-CNN算法的铁谱磨粒识别。该算法采用ResNet-34网络完成铁谱磨粒特征自动提取,并采用RPN网络实现对图像中多个磨粒的识别。通过实验对Batch_Size和学习率超参数进行优化,使用超参数优化后的Faster R-CNN算法进行实验。结果表明:该方法克服了磨粒交叉引起的识别难点,能识别一副图像中的多个磨粒,能统计各类磨粒数量,且准确率较高;在磨粒背景颜色不同、存在噪声干扰等情况下,该方法仍能够准确判断磨粒类型,具有较好的稳定性。     

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...     

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。     

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.     

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...     

奥氏体不锈钢表面双辉等离子渗锆的动力学

利用双辉等离子渗金属技术在0Cr18Ni9Ti奥氏体不锈钢表面制备了一层均匀、致密、呈良好冶金结合的渗锆合金层,并对1 060℃下的渗锆动力学进行了研究。结果表明:随着距锆合金层表面距离的增加,锆元素的含量呈梯度递减,扩散系数逐渐减小,而扩散激活能逐步增大;在1 060℃采用双辉等离子技术渗锆时,渗锆合金层表层的空位密度为2.945×(1012~1013)cm-2,与相同温度下采用常规渗金属工艺相比,提高了1~2个数量级。     

气化炉三维扫描测量与数据处理

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.