农村雷电灾害现状分析及防护措施

防雷减灾,利国利民。在我国广大的农村地区既是雷电灾害的多发区,又是防雷灾害的薄弱区。本文通过对雷灾事故的调查与分析,进而提出了农村雷电防范措施,以期提高农村防雷意识,科学防范雷灾事件的发生。     

闪电定位系统在防灾减灾中的应用分析

雷暴天气是最严重的气象灾害之一,潮州市每年由于雷电引起的人身伤亡、电力系统和通信设备的破坏等各种雷击事故频频发生,因此加强闪电监测定位系统在雷电预警、雷灾调查与鉴定中的运用,是十分必要的。利用闪电监测定位系统能够实时快速地探测和记录数百公里以内的闪电活动,并得到每一雷击的发生时间、地理位置、强度、极性等特点、本文叙述了闪电监测定位系统在雷电预警、雷灾调查与鉴定中的应用情况。     

宁夏一次雷击事故鉴定及防御对策研究

文章根据宁夏中卫市的一次雷击事故,从气象资料、闪电定位监测数据、周边环境、目击情况、剩磁测试5个方面进行了取证分析。鉴定结果表明,本次事故是直击雷对空旷区域独立树木闪击,以接触电压和反击的方式泄放雷电流,造成人员受伤。同时结合宁夏雷电灾害发生统计结果,对农村地区防雷减灾工作存在的问题进行分析,并提出解决对策。     

基于ATP-EMTP的110kV杆塔反击耐雷水平影响因素分析

输电线路在运行过程中易遭受雷击事故,雷击容易造成输电线路故障,威胁电力系统安全运行。而在雷击事故中,杆塔反击的概率较高,对电力系统的威胁最大,因此,研究如何提高杆塔反击耐雷水平具有重要意义。现以南方电网江门供电局110 kV输电线路为例,采用ATP-EMTP仿真分析方法,研究了接地电阻、杆塔呼高、绝缘子模型对反击耐雷水平的影响,给工程实践中输电线路防雷措施的实施提供了理论指导。     

25kV电力牵引网防雷计算

由于电气化铁路高速发展,雷击25k V电力牵引网的事故逐渐增多。耐雷水平和雷击跳闸率是用来评价一条供电线路遭受雷击的主要指标。供电线路可能经过直击雷和感应雷遭受雷击。过电压从而导致线路故障。在进行防雷设计和采取防雷措施时,必须考虑到该地区的雷电活动情况。本文提出了分别利用避雷针和避雷线改进25k V电力牵引网防雷水平的方法,通过计算,来分析电力牵引网的耐雷水平的改善。     

政府办公楼、公寓楼综合防雷整改工程设计浅析

为了落实遭受雷击建筑物进行综合防雷整改,通过合理、有效的手段将雷电流的能量尽可能引入到大地,注重防止雷电和其它形式的过电压侵入设备,分别对建筑物进出各保护区的电缆、金属管道等安装过电压保护器进行保护并做良好接地。文章通过雷击事故分析,对办公楼、公寓楼进行了直击雷、管线和设备的综合防雷防护,降低和减少了因雷电而产生的影响。     

浅谈输电线路引雷塔的特性及综合防雷效果

架空输电线路纵横延伸,地处旷野,易受雷击,雷击导致的输电线路跳闸事故在电网总事故中占比很大,现基于佛山地区近几年线路跳闸情况分析,阐述目前佛山地区已有的常规防雷措施,并重点探讨引雷塔的雷击特性及综合防雷效果。     

浅析汽车制造行业的危险性

汽车制造行业属于机械加工行业,大批量的流水线生产,其致灾因素复杂,事故后果严重,对社会的影响大,本文主要从汽车生产流程中涉及的冲压、焊接、涂装、总装以及安全管理等方面分析汽车生产过程中存在的危险有害因素,并提出了相应的安全控制措施,有助于汽车制造企业更好的进行安全管理,达到预防和控制事故的目的。     

汽车安全技术前瞻

未来新一代汽车的安全理念是在不增加车重、不影响实用性、不削弱驾驶者自主控制的前提下,能够有效预防事故发生,而在事故发生无法避免时能够显著降低对驾乘人员的伤害。在此,笔者罗列了几项前所未见的安全技术。预防性安全车身结构该技术是用来应对侧面碰撞用的,藏在车门内部的防撞梁平时就像一张被卷起来的充气垫。而一旦侧面雷     

错误接线导致上升极限开关失效

<正>1事故经过2009年某月,吉林省某市某造船厂船体成型车间有1台电动葫芦桥式起重机,额定起重量为10t,吊钩到达上升极限位置后,上升极限开关失     

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.