基于ARM的坩埚气泡动态智能检测系统

为了得到石英坩埚透明层气泡的形态参数及数量。搭建了一种基于ARM的石英坩埚气泡动态智能检测平台。首先利用STM32作为机械臂的控制单元,搭载电子放大镜采集坩埚气泡图像;其次对采集的气泡进行增强处理并且提出一种融合霍夫变换气泡轮廓提取算法,利用凹点提取分割算法分割重叠气泡。最后基于ARM开发了实时检测系统。实验结果显示,设计的系统对气泡信息定位准确,单张图像检测时间仅为0.1 s,实现了动态获取气泡直径、数量的功能。     

多尺度气泡尺寸分布数字图像测量方法研究

鼓泡塔是一种广泛应用于能源和环境领域的多相流反应器,鼓泡塔中气泡的大小和浓度对于研究鼓泡塔中"三传一反"过程具有重要意义。采用高速摄像法和数字图像处理技术开展了鼓泡塔中内多尺度气泡尺寸分布测量研究,针对气泡识别过程中密集气泡易发生重叠的问题,提出基于曲率计算的凹点匹配与圆周拟合的重叠气泡分割与轮廓重构算法。搭建了鼓泡塔反应器实验装置,针对星型、均匀和方形3种不同进气孔形态的气泡分布器开展了实验研究,分析了不同尺度气泡的尺寸分布规律。试验结果表明:该算法不仅能够有效地从图像中提取轮廓清晰完整的气泡,而且能够对图像粘连重叠的气泡进行准确分割,从而可精确地获得多尺度气泡尺寸分布。随着气体流量的增加,小气泡的数量急剧增加,同时产生更大的气泡;气泡的最大直径和Sauter平均直径均随气体流量的增加而增大,且两者的比值基本保持不变,即分布器形式对气泡尺寸分布均匀性有影响,方形分布器产生气泡最均匀,气含率相对其他两种分布器更高。实验结果证明了图像分割与轮廓重构方法在气液两相流中气泡参数在线测量的可行性。     

基于地电流的重力流排水管道泄漏检测

重力流排水管道的泄漏会带来诸多不良后果,但由于重力流排水管道的特殊性,导致许多现有的管道泄漏检测方法难以适用。针对这一问题,提出了一种基于地电流的检测方法,该方法利用泄漏孔联通管道内外,通过测量在管道内移动的电极和固定在地面电极之间电流来确定泄漏,阐述了该方法的基本工作原理,基于该方法设计了检测系统,搭建了实验平台测试了检测效果。检测10 m长的埋地管道时,最大定位误差约0.4 m,表明该检测系统能较准确地定位泄漏位置,若配合更好的探头定位方法,误差将进一步减小。根据测得的尖峰电流值,能明显分辨9个直径梯度为0.5 mm的圆形泄漏孔,使用测得的9组数据训练神经网络模型,大致得到了尖峰电流值与泄漏孔大小的映射关系,表明根据检测结果能大致估计泄漏孔的大小。     

基于机器视觉的航空接头气密性全自动检测仪

气密性是航空接头合格与否的关键.应用机器视觉原理实现对航空接头气密性的高精度检测.图像采集系统对从航空接头泄漏到煤油中的微小气泡进行放大成像,并转换成数字图像输入到计算机,再由检测软件进行预处理和目标智能识别,依据图像中目标的参数给出判定结果.检测软件具有图像处理、数据分析、自动控制等功能.因此能够自动消除光源和煤油中杂质等因素影响,捕获并识别出泄漏气泡;具有精度高、可靠性好以及操作简单等特点.     

承压零件气密性视觉检测系统的研发

采用视觉检测技术检测承压零件的气密性,通过提取零件承压时图像中有无气泡的产生,来判定零件是否存在泄漏,解决了传统的气密性检测方法检测效率低、准确性差的问题。以视觉检测技术和计算机数字图像处理技术为基础,设计了一套承压零件气密性检测的视觉检测系统。采用机械传动与气动相结合的传动方式,多工位检测,提高了气密性检测的效率。     

飞机非封闭组件的气漏超声检测技术研究

因大飞机中非封闭组件的气密性检测是在整机装配后以封闭的形式进行,在部装阶段尚无有效的气密性检测方法。基于超声波检测原理提出了一种面向大飞机非封闭组件气体泄漏检测的方法,设计了飞机非封闭组件气体负压泄漏的超声波检测试验系统,对泄漏孔径、检测距离对超声声压和泄漏量的关系进行了试验分析。研究结果表明,该方法可以在飞机部装阶段有效检测0.4 m范围内、泄漏孔径1 mm以内的飞机非封闭组件的气体泄漏,能够准确、快速地获取泄漏孔径和泄漏量,为大幅降低整机装配后的气密性检测时间和成本提供了一种有效便捷的方法。     

基于多层Hopfield神经网络的X射线焊缝气泡检测

提出利用Hopfield神经网络来分割X射线焊缝图像以判断焊缝是否存在气泡,将焊缝图像的分割问题转化为一个优化问题进行处理.针对焊缝图像噪声大、气泡出现位置随机的特点,构造Hopfield神经网络的能量函数.通过试验计算,确定能量函数系数的选取原则.在此基础上,提出基于神经网络的X射线焊缝图像分割算法,算法结合中值滤波和神经网络以便有效地去除噪声和检测气泡.对某实际生产线的焊缝图像进行处理的结果表明,中值滤波结合多层Hopfield神经网络可以准确地检测到焊缝中的气泡.     

真空注型气泡监控方法的研究

针对现有真空注型设备气泡检测和消除方法存在的问题,结合机器视觉和图像处理等技术,研究气泡实时监控方法。首先采用直接图像(DI)法利用CCD数字相机实现真空注型气泡检测,并通过VC++线程技术实现气泡图像连续采集;然后研究适合真空注型气泡图像处理算法,特别针对高重叠、大变形的气泡特征提取,提出一种气泡边缘像素比例算法,较好地解决了重叠气泡的信息丢失问题;最后给出了该方法的具体实现过程,并通过实验,验证其可行性和有效性。     

微滴制备及其均一性检测

文中基于电磁力振动原理,采用蒸馏水作为微滴喷射材料,搭建了微滴发生器,利用高速摄影机采集微滴下落过程图像,并基于MATLAB图像处理技术研发了用于计算微滴几何参数的微滴检测系统。实验结果表明:在喷嘴孔径和气压分别为0.33 mm和0.7 kPa条件下,扰动频率分别为600、800、900 Hz时,可获得均一微滴;公式法计算得到的平均直径和微滴检测系统计算的平均直径之间的最大误差为2.5%,通过误差传递公式计算出球形度的最大误差为5.89%,说明基于MATLAB设计的微滴检测系统具有较高的可靠性。     

基于互谱矩阵估计的泄漏源超声阵列定位技术研究

针对天然气站场微小泄漏源准确定位的难题,分析了基于时延估计的波达方向计算原理;提出了基于互谱矩阵的延迟估计方法;设计了三角形超声阵列泄漏检测系统,根据西气东输某压气站真实背景噪声下的模拟泄漏测试数据,对比分析了互相关、广义互相关和互谱矩阵3种算法的定位精度,结果表明,超声阵列泄漏检测系统在探测半径为20 m范围内时,基于互谱矩阵算法的泄漏源定向误差均值小于2°,2个超声阵列传感器空间交汇定位误差为0.61 m,显著优于互相关和广义互相关经典算法。系统抗干扰能力强,具有在正常生产工况下对2 mm口径微小泄漏准确定位的能力,研究成果为天然气站场泄漏点准确定位提供了一种切实可行的技术方案。     

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.