DeltaV控制系统与西门子PLC基于ModbusRTU协议通讯

本文以西门子S7-341PLC与艾默生公司的DeltaV控制系统通信为实例,通过对软件组态及串行通信参数的设置,介绍Modbus通讯协议、DCS控制系统与PLC系统进行通讯所需要的通讯卡件、各卡件为实现通讯所要进行的设置以及二者之间的通讯和以Modbus RTU通信协议为基础的串行通信的具体实现方法.     

电动执行机构总线控制器在广西石化的应用

本文通过对ROTORK电动执行机构总线控制器与横河DCS之间串口通讯的具体实现方法的分析,结合实际工作中存在的问题,详细描述了基于串口通讯协议的冗余控制方式及组态方案。ROTORK总线控制器在广西石化储运罐区的的使用中,运行良好。     

汕尾电厂4号炉磨煤机出口温度自适应控制策略研究与实施

为了提高锅炉运行经济性,广东红海湾发电有限公司4号炉采用智能外挂系统来提高磨煤机出口温度,并进行自适应控制运行。智能外挂控制系统与DCS通过OVATION的LC卡进行双向通讯,智能控制器从DCS读取磨煤机及锅炉有关运行参数,并将控制指令发送至DCS。煤种及煤质数据从信息平台的煤质掺烧系统读取,并以4mA～20mA的物理隔离后送至智能控制器。外挂控制系统接入DCS系统,在DCS系统上实现监视与控制投切。对制粉系统运行控制进行优化,在保证机组安全运行的前提下,根据燃用不同煤种,自适应控制系统自动设置磨煤机出口温度,降低锅炉排烟温度,提高锅炉效率,达到节能效果。     

锅炉侧主蒸汽温度值比汽机侧主蒸汽温度值偏低的原因分析及解决方法

针对火力发电厂锅炉侧主蒸汽温度显示值比汽机侧主蒸汽温度显示值明显偏低的异常现象,进行分析判断,找出故障原因。通过采取更换温度元件和DCS卡件等办法,最终达到了主蒸汽温度准确测量的目的。     

S7300PLC在稀油润滑站中的应用

介绍了以S7300PLC为中央控制器,实现整个润滑油站自动启停,报警和重故障停减速机;在现场用触摸屏对整个润滑油站的压力、温度、液位、流量以及减速机的温度等进行实时监视并显示报警信息等;中控DCS和S7300PLC采用Profibus协议进行通讯,只用一根总线来对现场进行实时的监视与控制。     

基于Modbus协议的变频控制系统的设计与研究

采用Modbus通讯协议完成PLC和变频器的变频控制系统设计,可实现对变频器运行控制、工作状态的远程监控以及参数设置和调整。基于通讯方式设计的变频控制系统,不仅提高了变频器的抗干扰性和工作可靠性,同时减少系统的接线,便于实现联网和集中控制,降低生产成本,提高产品竞争力,在实现系统集成化和远程设置方面具有重要意义。     

基于多种通讯的土壤切削实验台监控系统

为了实现土壤切削实验台监控系统的远程监控和测量,提高系统的可维护性及各设备高效运行要求,设计了一套基于多种通讯方式的土壤切削实验台监控系统。根据土壤切削监控系统组成,介绍了以太网通讯、PPI通讯、Modbus通讯以及OPC通讯在监控系统中的应用。进行了硬件组态及OPC客户端程序设计,实现了通讯和实验。结果显示,系统自建立运行以来,设备运转正常,数据传输可靠; 同时,由多种通讯方式在土壤切削中的应用,证明了该实验通讯的稳定性和多种通讯方式之间良好的兼容性。     

PLC与变频器在环形生产线中的应用

在生产现场中,采用三菱系统,运用PLC、人机界面以及变频器,组成了一条环形生产线.该条生产线用RS-485组网,可以实现对每条皮带的控制与监视状态.详细说明了硬件接线与通讯格式的设置,并对控制程序作了简要说明.     

KEITHLEY2700在高精度温度控制系统中的应用

基于KEITHLEY2700表测量的铂电阻阻值,设计了高精度的温度控制系统.对KEITHLEY2700表的系统设置、串口通讯和控制命令进行研究,在.NET平台下用C#语言完成了温度数据的实时采集和即时处理,并用模糊-PID控制算法实现了高精度的控制功能.     

基于PC机与单片机分布式温度采集系统的设计

针对分布式温度采集系统,提出了一种温度测量方案,并给出了具体的硬件电路和系统软件。系统硬件分为3部分:DS18B20温度测量模块、单片机多机通讯模块、PC机与单片机通讯接口电路;在软件方面,用单片机汇编语言与VB相结合并利用PC机串口通讯技术,编写了一个上位机程序。系统的测温精度可以达到±0.01℃,并且能稳定的与单片机和PC机通讯。     

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.