基于振弦式传感器的测频系统设计

为了满足大型结构安全监测中振弦式传感器的数据采集需求,提出了一种用等精度测频实现振弦式传感器频率测量的实用方法,并给出了具体的硬件电路,系统硬件分为3部分:激振电路、测振电路、温度补偿电路.应用AT89C52单片机实现等精度测频的原理、实用电路,具有测频范围宽和测量精度高等特点,且应用AT89C52单片机实现激振频率可控.测频系统具有硬件电路简单,激振可靠、激振频率可控,温度补偿可以减小温度对振弦式传感器频率测量的影响,提高测量精度.     

激光自混合测振技术在声共振探雷实验中的应用

利用激光自混合干涉测振技术,研究一种非接触式声共振探雷方法.在论述激光自混合测振技术原理的基础上,以69式防坦克塑壳地雷、72式防坦克金属地雷、58式防步兵橡胶地雷和砖块作为测量对象,构建其声学特征测量实验系统,设计并搭建地雷在埋设情况下的探测实验系统,利用激光自混合测振技术研究不同类型埋设地雷及同一地雷在不同埋深和土...     

流致振动差压式测振装置的研究

为解决管束流致振动试验中,现有接触式振动测量方法的应用局限性,提出一种基于测量受激对象换热管两侧压差脉动频率原理的测振装置,即差压式测振装置。差压式测振装置解决了传统接触式传感器对换热管外部流场的干扰问题以及安装空间受限的问题。为了验证差压式测振装置的有效性,分别进行了单管和换热管束两类流致振动测试试验。试验结果表明,差压式测振装置能在复杂的流动环境中准确捕捉到换热管受到的各类激振形式的频率,而且单管流致振动试验结果表明差压式测振装置所测得的周期性涡激振动频率与理论值偏差在5%以内。因此,差压式测振装置的研制与应用对于流致振动试验的测试以及换热管振动的长期监测均有很重要的意义。     

基于Labview光纤测振系统的研究

提出的光纤非接触式测振系统,能克服传统测试手段在高频粘接与悬接时对被测物损坏等不足;借助hbview软件,消除了检测中被测材质、表面粗糙度、环境温度等因素对测振系统的影响;实现了高频微信号的精准测量,对超声振动测量具有促进作用.     

无线传输技术在工业测振中的应用和发展

介绍无线测振技术的原理、应用现状及效果,并结合实例进行说明。详细介绍无线技术的工业应用领域及测量系统的实现过程。基于无线网络技术的测振系统具有传统监测系统所不具备的优势,能较好地解决传统测振监测系统中存在的布线搬迁等问题,非常适用于复杂工业现场环境的参数监测应用。     

基于多周期测量方法的气压传感器信号采集

利用电激励谐振筒式气压传感器测量气压,电激励谐振筒式气压传感器输出信号的频率与气压呈非线性关系,且与环境温度有关。利用多周期测量方法,通过对信号进行分频准确测量出信号的周期和频率,利用P89LPC935内部的AD转换器测量环境温度进行温度补偿,用曲线拟合法准确计算出气压,气压测量的范围为45~110kPa,测量误差小于0.03kPa。用多周期测周的方法快速准确测量信号的频率(周期)基于2个条件:信号是连续信号;P89LPC935的晶振必须使用外接的高精度、高稳定晶体振荡器(准确度优于5×10-6)。     

激光反馈测振方法的研究

本文介绍采用激光反馈原理进行振动测量的研究,讨论了激光反馈原理,分析了影响激光反馈测振的因素。实验证明,最大测量速度达到1.2米/秒,对应最高频率为4MHz。最后给出现场测量结果和误差分析。     

全场高速纳米振动测量技术研究

项目负责人:乐开端所在单位:西安交通大学项目批准号:59905020项目简介对于小型结构或大物体的高频振动,由于其振动很小（如纳米级）,普通的测振技术（如加速度传感器,激光多普勒）由于测量原理及探测器容易影响被测对象等原因往往对这种微小振动的测量无能为力。本项目研究的纳米振动测量系统集激光散斑技术、计算机图像处理技术、高压电路相移技术于一体,实现了宽带、微振幅、非接触全场快速测量。从而使得振动幅     

精密孔径测量仪计量检定方法研究

精密孔径测量仪是一台以长光栅为标准,利用光电瞄准技术进行非接触绝对测量的高精度测长仪器;主要用于测量内孔直径,还可以用于测量轴径、两平行平面距离及玻璃尺刻线间距等。文中主要研究测量范围为(0~200)m m,分辨力为0.1μm的精密孔径测量仪的检定方法。     

转子测振表面机械、电气跳动问题探讨

非接触式测振仪的应用是现代工业测振技术的进步,是精确监测高速旋转机器振动的可靠保证。影响测振表面的因素主要为机械跳动和电气跳动两个方面。如何保证机械和电气的加工精度,提高旋转机器振动检测的准确性,我们对测振表面加工方法和修正方法进行了研究和探讨,结合我厂实际情况确定了与测振表面相关问题的处理方法。     

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.     

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....     

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.     

ANGULAR DISTORTION ALLOWABLE VALUE AND ASSESS METHOD OF WELD ON COKE TOWER

A graph as the new engineering method for estimate the safety of bulging deformation of coke tower is proposed. Through stresses analysis of circumferential weld of coke tower and comparing the stresses produced by pressure with heat stress of steady state, residual stress, bending stress produced by both itself weight and wind loads, it showed that the stresses produced by pressure on the angle distortion are the main factor of equivalent stress of the combined stress. After comparing four kinds of stress controlling conditions, the relation to stress with depth of angular distortion, grade of curvature of angular distortion and half of region of angular distortion has been inferred. Graph of deformation allowable value of coke tower for different condition by angular distortion and half of region of angular distortion has been plotted. The five steps for its engineering use have been explained. The lighter the grade of curvature is, the larger of bulge allowance, may be, and the bigger of depth of angular distortion may pose too. For the coke tower with a popular structure of Dg 5 400 mm×28 mm, the result by graph is nearly more than the result of two formulas formed by other research, the error is less than 7.0%. But, the graph can be easily applied to different size of angular distortion.