信号线路浪涌保护器防雷设计

电子线路最有效的防雷措施是在线路上靠近设备侧安装SPD。现对信号型SPD总体设计原理进行分析,然后给出适用于模拟/数字信号线路保护的二线制、三线制、四线制信号线路SPD。主要利用前级的GDT防护电路抑制共模电涌电压,利用GDT与TVS管组成的两级防护电路抑制差模电涌电压。设计了对地细保护信号线路SPD和防爆型信号线路SPD,最后进行了信号线路SPD防护模块热插拔试验。     

电涌保护器在建筑电气设计中的应用分析

电涌保护器是一种能够为各种仪器仪表、电子设备及通讯线路提供安全防护的装置,可以防止电涌对电气系统回路当中的其他设备,造成破坏与损害,保证整个电气系统的完整性、安全性,避免安全事故发生。所以,在现代建筑电气设计中,应正确、合理的应用好电涌保护器。本文首先阐述了电涌保护器的作用效果和工作原理,分析了电涌保护器的不同分类,然后主要就建筑电气设计中电涌保护器的选择及安装进行了探讨。     

雷击电磁脉冲防护器件的正确选型

为了有效抑制雷击电磁脉冲,其防护器件(也叫电涌保护器)的正确选型至关重要,而目前市场上的电涌保护器种类繁多,功能特点各有其针对性,技术参数分布广泛,给防雷工作者的正确选型带来诸多困扰。为此,文章阐明了低压配电系统电涌保护器的选型原则及其主要技术参数的选择要求,并以菲尼克斯防雷保护模块为例,运用所述的选型原则和技术参数要求,给出了内部防雷保护为三级配置的建筑物电涌保护器的安装位置、安装级数、技术参数规格及分类试验等级等,从而给防雷工作者在低压配电系统电涌保护器的正确选型时提供一定的理论依据。     

核电厂火灾报警系统改进及实现

针对核电厂的环境特点,为了保障火灾报警系统能够正常、稳定运行,对火灾报警系统的基本要求进行了论述.对核电厂特殊环境进行了分析,提出了火灾报警系统加装抗电涌保护器,以达到抗雷击的目的,对抗电涌保护器在系统中的设置方式进行了论述.针对电缆沟类感温电缆易被强电磁干扰的情况,通过设置接口模块,提高系统的可靠性,对接口模块的工作...     

石油化工行业中本质安全型电涌保护器的设计与选择

为了提高石油化工电气系统设备接口安全,保证工业系统DCS、PLC的正常运行,对本质安全型接口仪表电涌保护器进行设计与选择。着重讨论了雷电流对控制系统的危害,利用其合理地选择本质安全型电涌保护器来精密保护工业设备,如:变送器、流量计、AI、AO、DI、DO等。重点强调电涌保护器设计原理、工业接口保护的选型方式以及机柜内的合理安装。实际表明:合理选择具有抗浪涌冲击、能力强、残压低、传输精度高的电涌保护器,以及合理的机柜布局与安装,可以更好地保护电气接口设备安全。     

浅谈电涌保护器在仪表中的应用

本文介绍了电涌保护器的工作原理,针对电涌保护器在现场仪表端和控制室端的应用和应用时要注意的问题,给出电涌保护器在茂名地区某化工装置应用上的设置方案。     

浅析电涌保护器的后备保护装置

通过对电涌保护器的分析,进一步探讨了如何选用电涌保护器的后备保护装置。     

电梯防雷的研究

鉴于电梯遭受雷击而发生故障停梯的情况越来越经常发生,通过分析电梯遭受雷击的原因与干扰途径,提出了在电梯机房配电箱安装电涌保护器(SPD)的防雷措施,并设计了TN系统中电梯机房配电箱加装SPD的安装图。     

试论民用建筑电气设计中电涌保护器的选用

电涌保护器的作用是保护建筑内的电子设备不受雷击脉冲的危害。针对建筑构造差异以及整体电压、电容等的不同,我们在设计中需要对电涌保护器进行选择,同时也应该关注电涌保护器在安装施工过程中应该注意的问题,选取最佳的设计方案和措施。本文围绕民用建筑电气设计中电涌保护器的选用展开讨论,实现更好的保护不同的电子设备。     

浪涌保护器原理及应用

由雷击、带负载的开关操作、静电放电产生的电压电涌可能导致系统失灵、设备损坏。浪涌保护器可以有效的限制瞬态过电压和转移浪涌电流,使电子系统免遭雷击及雷击电磁脉冲或操作过电压的损害。因此浪涌保护器的原理及应用的研究,对计算机机房的系统防雷具有重要的意义。     

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.     

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.