铁合金多段速定点浇注自动控制系统的研究

为了实现铁合金多段速定点浇注系统的自动控制,探讨了基于西门子S7-200系列PLC226CN与MM440变频器之间联机实现多段速自动控制系统。论述了PLC系统、变频调速的原理及控制方式、多段速自动控制及系统稳定性等问题,通过工业运行验证该控制系统有抗强磁场干扰、运行稳定的优点,可在铁合金浇注成形设备上推广应用。     

石煤提钒制球工艺的自动化系统设计

在襄阳某厂的石煤提钒制球工艺过程中,污染情况比较严重,对现场操作工人的身体健康造成极大危害,现根据生产设备和工艺要求,结合在工业自动化监控系统中广泛使用的PLC技术,通过PLC"采集数据,分析数据,处理数据"的运行流程来控制设备的运行及参数;利用PLC编程软件SIEMATIC STEP 7模块化编程,并使用梯形图或语句表编写程序,选用Siemens MM440型变频器,对电机进行调速,利用Visual C++编写监控界面,对设备运行状态实时监控,同时运用计算机控制、网络通信、总线传输等技术,实现石煤提钒制球过程的自动化、智能化,进而达到提高生产效益并降低生产成本的目的,而且也可将此系统框架应用于类似的监控场合。     

基于Profibus-DP现场总线的糖厂压榨车间调速控制系统通信设计

提出了一种基于Profibus-DP现场总线调速控制系统通信设计方案,以上位工控机监控整个系统,S7-300 PLC为主站,变频器MM440、直流调速器6RA70为从站,文中主要内容介绍了PLC与上位机、PLC与从站的通信方法.     

交流变频调速特性实验系统设计

在剖析MM440变频调速控制原理基础上,引入电机终端转速反馈系统,设计电机运行闭环控制系统,由给定速度与PLC高速计数模块反馈的实际速度相减产生速度误差,通过PID模块控制转速调节值,由USS协议输出给变频器,驱动电机稳定运行在给定速度。同时,系统通过PC-Access组态PLC,设计上下位机数据通信监控网络,实时显示变频给定与反馈速度特性曲线,以供进一步研究调用。     

基于Modbus现场总线的电动机运行监控网络研究

针对传统变频调速系统中开关量和模拟量控制方式抗干扰性差、不宜远程控制以及多电机同时监控很难实现等问题,通过Modbus现场总线研究将西门子S7-1200、HMI和G120变频器连接起来组成异步电动机变频调速监控网络.研究内容包括控制系统硬件构成、变频器参数设置和PLC控制程序设计.该控制系统成本相对较低,能实现电动机的无级调速,可远程实时监控,值得推广.     

PROFIBUS-DP与PLC异步电机变频调速研究

针对异步电机变频调速系统,阐述了基于PROFIBUS的S7-300硬件组态和MM440从站的数据结构,说明了MM440通讯参数设置,描述了变频器通信数据结构的PPO1类型。详细说明了参数标识符PKW和过程数据PZD。应用系统功能函数SFC14和SFC15对过程数据PZD进行读写。设计了控制电机程序和获取异步电机运行参数程序。描述了电机转速闭环控制结构图。说明了功能块FC106实现量程转换功能。显示了闭环转速曲线。实现了基于Win CC flexible监控画面的设计。     

PLC变频调速在桥式起重机中的应用

将可编程控制器(PLC)应用到桥式起重机的变频调速中,实现了起重机电机的变频调速,并基于PLC的软件编程实现了通讯、PID控制等功能。此系统可实时监控起重机的现场运行状况和查询运行数据,可以通过控制室的人机交互界面启停电机、设定变频器的运行频率等,改善了传统桥式起重机的调速系统,提高了其可靠性和可操作性。     

变频器在电梯控制系统中的应用

当前,随着新工艺新技术的飞速发展,变频调速已经成为了电梯传动的主要控制方式。通过变频器控制电梯的运行速度,首先要合理选择电动机和变频器。介绍了西门子公司生产的MM440型通用变频器的调速原理及选用标准,重点介绍了MM440型变频器在电梯控制系统中的应用。     

触摸屏、变频器与PLC在捻线机控制中的应用

对基于触摸屏、变频器与PLC的捻线机多电机控制系统进行了研究。通过触摸屏、变频器与PLC的通信,对PLC进行编程完成对捻线机各项参数的设置,从而达到捻线生产过程的捻度和锭速无级调节的目的。该系统自动化程度高,人机界面友好、操作方便,并具有实时监控性,提高了生产效率。     

立式节能抽油机的智能控制系统

为解决我国游梁式抽油机成本高、耗电量大,效率低、调整困难等问题,对比分析了智能控制立式抽油机的优点,将立式抽油机代替游梁式抽油机应用到实际中去。开展了针对立式抽油机的高效率可靠性分析,提出了利用西门子PLC和Micromaster变频器来实现具有自适应变频调速和自动进行故障诊断智能控制系统的方法,该控制系统通过选用西门子PLC作为核心控制器去控制变频器,通过改变电动机的运转频率,实时计算了抽油机应该运行的速度,通过计算上、下冲程的时间,来控制变频器的输出电源的频率和电压。实现了电动机的无级调速控制,并做到了运行转矩的适配。研究结果表明,该节能立式抽油机的智能控制系统具有结构简单、无故障运行寿命长并提供远程监控接口等特点。     

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.