基于YOLOv3的轴表面荧光磁粉缺陷检测

在荧光磁粉缺陷检测中,为快速有效地对金属轴上的点状、线型以及摩擦型缺陷进行分类检测,引入了深度学习技术,并与图像处理技术结合设计了一种改进型金属轴表面缺陷检测系统,克服了传统识别方式人工选定处理区域的局限性。利用基于YOLOv3算法的神经网络模型,对CCD相机获取的轴表面图像数据集进行训练和测试,对不同缺陷进行精确目标识别;采用图像处理技术对识别的目标进行缺陷定量分析。实验结果表明:该方法对不同缺陷类型能进行有效识别,在检测精度与检测效率上具有较高的提升。     

基于不同识别分子的表面等离子体共振技术在农药检测中的研究进展

表面等离子体共振传感器具有灵敏度高、无需标记、简单成本低、可实时监测等优点。在生命科学、新药开发、食品安全、环境污染检测及国家安全等方面都得到了广泛的应用。而识别分子是SPR技术的重要组成,它决定其检测的专一性及灵敏度,因此识别分子的发展非常重要。本文简要综述了基于不同识别分子的表面等离子共振技术近10年来在农药监测方面中的应用。包括抗原-抗体识别技术、乙酰胆碱酯酶识别技术、表面分子印记技术等。最后分析了不同分子识别技术的优缺点,并展望了其他分子识别技术在农药检测领域的应用前景。     

磁记忆技术在管件裂纹检测中的应用

基于金属磁记忆效应的原理,研究了利用磁记忆技术检测管件裂纹,虚拟仪器系统和漏磁传感器是检测系统的核心.试验表明,运用该技术检测管件裂纹是完全可行和有效的.     

基于静电感应的金属接触损伤诊断研究

提出了基于静电感应的金属接触损伤诊断技术和方法.分析了金属接触损伤致电机理和感应模型,利用小波单支重构和短时傅立叶变换方法验证了该技术的可行性,借助传感器阵列和智能算法实现了接触损伤位置的定位.基于因子分析和支持向量机神经网络,对不同损伤程度的试验样本实现了定量识别.该诊断技术和方法可以有效识别金属接触损伤的位置和程度.     

基于巨磁电阻(GMR)效应的生物分子识别器件研究

对基于巨磁电阻(GMR)效应的生物分子识别器件的结构和微加工,以及检测原理、检测方法进行了介绍,构建了对应于这种生物分子识别器件的信号检测和处理系统.采用微细加工的方法制成了基于巨磁电阻(GMR)效应的生物分子识别器件,生物分子识别器件的结构是多个磁隧道结组成的传感器阵列,单个磁隧道结尺寸为10μm×20μm,退火后磁阻效应可达86.5‰,检测灵敏度可达8×10-4 A/m,采用厚度小于100nm的PDMS作为器件的生物适应层,可将检测信号提高27倍以上.基于巨磁电阻(GMR)效应的生物分子识别器件主要应用于基因分析、医学诊断、免疫分析和药物筛选等领域.     

对置螺线管线圈的多功能检测模型及灵敏度研究

为丰富螺线管型传感器对液压油污染物的检测内容,提出并制作一种基于微流体芯片的对置螺线管型多功能检测传感器。理论推导了对置螺线管线圈的金属颗粒电感检测模型和非金属颗粒电容检测模型。为进一步提高检测灵敏度,试验对比分析了硅钢片对对置螺线管线圈的电感检测和电容检测的灵敏度。试验结果表明,硅钢片能够显著提升对置螺线管线圈的金属颗粒检测灵敏度,60～70μm铁颗粒和160～170μm铜颗粒的检测信噪比分别提升127.44%、222.07%,也能提高对置螺线管线圈的非金属颗粒检测灵敏度,但不显著,140～150μm水滴和240～250μm气泡的检测信噪比分别提升21.92%、7.95%。该研究对提高螺线管型传感器的液压油污染物检测能力提供了技术支撑,对液压系统健康状态监测以及故障诊断具有重要意义。     

基于特征光谱识别的光纤化学传感技术

本文针对目前光纤化学传感器普遍存在的提高选择性和灵敏度的困难,研究和建立了一种基于人工神经网络的特征光谱识别技术。将这种技术与传统的光纤传感器技术相结合,有效的降低了传感器对化学识别器选择性和灵敏度的要求,提高了传感器的识别能力和检测范围,有助于光纤化学传感器的工程实现和实际应用。     

分布式光纤管道泄漏检测及预警技术研究

介绍了一种基于Mach-Zehnder光纤干涉仪原理的分布式光纤管道泄漏检预警技术,利用与管道同沟敷设的光缆中的3条单模光纤构成分布式光纤微振动传感器检测管道沿线的振动信号,可以有效地检测管道沿线所发生的泄漏和异常事件.阐述了检测系统的组成和工作原理,分析了检测系统定位结构和方法.采用小波软阈值消噪对现场检测信号进行处理,可以有效地消除噪声和提高检测灵敏度.理论分析和测试结果表明,该测试技术具有较高的测试灵敏度和定位精度.     

基于电涡流的金属种类识别技术的理论与实验研究

通电线圈与其附近的金属导体之间将产生电涡流效应，由于不同种金属有着不同的电导率和磁导率，从而使得相应的探测线圈等效阻抗的变化量互不相同。本文用电容三点式振荡电路将线圈等效阻抗的变化转换成电压信号，通过离线训练的方法获得神经网络辨识模型，以此来进行金属种类的识别。本文设计了一套基于微机检测系统为核心的电涡流金属种类识别的实验装置，选用实验室易获得的吸铁、黄铜和铝合金3种金属为对象展开实验研究，结果表明利用电涡流技术以及神经网络辨识的方法能有效的识别金属种类，为智能金属探测器的推广应用奠定了理论基础。     

基于ESPI技术的物体缺陷自动识别技术

电子散斑干涉技术是变形和缺陷检测的重要技术方法,具有非接触、动态特性好、灵敏度高等优点.在缺陷检测中,以变形为载体,通过变形分布上的异常判别缺陷是否存在和大致位置.在这个过程中,如何摆脱人的主观判断,实现缺陷的自动识别,一直是一个技术难点.本文以实现缺陷自动识别为目标,探讨了电子散斑干涉技术的物体缺陷识别技术.总结了ESPI实现系统和变形测量的主要算法,包括时域相移干涉仪中算法、空域载波相移干涉仪中算法及空域相移干涉仪中算法,分析了各自的特点并进行了归类.描述了变形与缺陷之间的关系.讨论和总结了缺陷的时域识别方法和空域识别方法.分析了基于变形梯度的缺陷识别方法,并进行了改进.改进的方法引入了调节因子,提高了缺陷区与非缺陷区之间的界限,从而提高了该方法的缺陷识别能力.     

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.