基于振动分析的电机转速测量研究

以鼓风机为典型研究对象,讨论了传统的电机转速检测方法的优劣,提出了直接从振动信号提取电机主轴转速的方法.根据某大型电机在线监测诊断系统的具体情况,在开发在线振动监测系统的过程中综合应用频谱分析、低通滤波等方法,从实测振动信号中精确计算了主轴转速的大小.系统已在实践中得到应用,证明了该方法测量转速的有效性.     

基于虚拟仪器的生物抗体自动包被机自动监测系统研制

以自行研制的包被机伺服进给系统为研究对象,设计了基于虚拟仪器的电机在线监测系统.该监测系统可在线诊断超声波电机堵转状态、实时显示步进电机温度变化、振动幅值及能量.     

振动分析技术在三相异步电机故障诊断中的应用

电动机状态监测及故障诊断是目前电动机运行维保主要发展方向,其中振动监测是电动机状态监测的重要组成部分,电动机故障包括机械故障和电气故障,部分电气故障会导致电机结构振动响应变化,从而为电机故障预测提供依据。列举电机常见电气故障及其特征频谱,并以案例的形式介绍了振动信号分析在三相异步电机故障诊断中的应用。结果表明,振动分析可以为电机电气故障诊断和预测提供技术支撑,从而避免电机非计划故障停机,实现电机的预知性维修。     

水轮机振动在线监测系统设计

水轮发电机组的长期振动将导致机组部件的材料疲劳甚至遭到破坏,严重影响机组的安全运行和发电效率,而水电机组故障一般称为渐变型或耗损型故障,因此对水电机组进行在线状态监测就显得十分必要了.通过对水轮机振动监测内容和现有的振动监测设备的研究分析,结合国内外现有的振动监测仪器的特点,提出采用了具有硬件乘法器的DSP作为前台处理器,实现信号的采集、处理.后台机采用工业控制计算机实现对数据的分析、显示和远传.这样可大大加强系统对数据采集、处理、分析的实时性及稳定性.使用此系统对某电站进行现场测试试验,结果表明:系统完全可以达到振动状态监测的目的.     

煤矿通风机常见故障分析及监测系统优化方案设计

分析了煤矿通风机的结构特点及风机类型,结合实际工况,开展了通风机轴承振动、油系统、电机振动及叶轮振动等因素引起的通风机故障分析,以振动为监测参数,设计了通风机监测系统的监测方案;该监测方案可通过监测通风机振动信号,对通风机产生振动原因进行分析,实现对通风机故障类型的分析与诊断。     

振动信号分析技术在电机故障诊断中的应用

我厂在开展设备状态监测与故障诊断过程中,应用振动信号分析技术.对设备故障进行诊断分析,收到较为显著的效果.下面介绍两个电机故障诊断的实例.一、电机轴承故障诊所煤气鼓风机是我厂生产系统的心脏,一旦发生故障将造成重大损失.为此我厂配置了振通902振动数据采集器/频谱分析仪,对煤气鼓风机进行状态监测.在测试过程中、发现2~#鼓风机电机前、后轴承处八个测点的振动值均呈上升趋势.图1是2~#鼓风机电机测点分布图.从测量数据看出,204测点的速度有效值上升幅度最大,由11月10日的2.97mm/s上升到11月23日的7.27mm/s上升了1.45倍,按ISO2372振动烈度标准,属于C范围,即“还允许范围”.电机后轴承各测点(201、202、203、204)的振动值平均上升幅度为1.78倍;前轴承各测点(205、206、207、208)的振动值平均上升幅度为1.61倍.为了确定故障性质、部位及劣化程度.对电机前、后轴承处都作了振动波形共振解调包络波分析.图2a、b分别是201测点和206测点经过共振解调滤波后的时域波形.图2a中振动信号出现了较大幅度的周期性冲击脉冲信号.滚动轴承出现缺陷时,在运行中就会产生冲击,     

基于VB的岸桥机房电机底座振动快速分析

根据岸桥机房振动测试结果分析出导致机房振动的主要原因,发现提高电机底座横向刚度可以有效抑制振动.基于将系统简化为单自由度强迫振动模型和有限单元法两种计算方法,利用VB分别编制了能将电机及底座参数化的振动快速分析软件.通过分析电机底座不同结构布置形式对其固有频率和最大振动响应速度的影响可知,增大电机底座截面惯性矩可以降低系统振动响应;快速分析软件分析结果与ANSYS计算结果一致,同时比较了用两种方法编制的软件的优缺点.运用所编软件对某岸桥机房电机底座进行了快速优化设计,振动实测数据与分析结果吻合,证明了快速分析软件分析结果的可信度和所用方法的可靠性.     

摩擦驱动型压电叠堆直线电机的工作机理

以一种典型的摩擦驱动型压电叠堆直线电机结构为例,对摩擦驱动型压电叠堆直线电机的振动摩擦驱动机理进行研究.结合电机系统的振动脱离模型,分析了电机定子与动子脱离的力学条件,进而分析电机结构参数和工作参数对椭圆运动和振动脱离性能的影响.对原理样机进行了试验研究,结果表明,压电叠堆的激励电压、激励频率和电机的预压力对电机的振动脱离性能有显著影响.     

大功率电动机群多微机监测与诊断系统

给出了一种大功率电动机群运行多微机监测系统，它可对连续运行中的电动机进行实时监测和诊断。系统采用主从工作方式、主机进行故障分析，从机进行常规监测和振动、，噪声的测量。应用本系统可显著提高电机运行的可靠性和安全性。该系统还可推广应用到其他类似的场合。     

直流电机振动监测系统在电枢绕组短路事故分析中的作用

本文介绍以振动、电参量、温度为主的直流大电机在线监测系统,并分析电枢绕组短路事故。指出对大型电机的故障监测应以电参数为主、机械参数为辅,可为排除电机故障隐患赢得宝贵时间。     

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.     

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....     

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.     

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.