防雷工程中传输线缆的屏蔽方法

介绍几种传输线缆的屏蔽措施和具体做法,在实际防雷工程施工中,可根据具体情况采用不同的方法对传输线缆进行防护处理,几种方法可以灵活运用。     

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鄂尔多斯北部塔巴庙地区的气藏是典型的低压低渗裂缝性砂岩气藏。该区储层具有孔隙度低、渗透率低或致密、储层压力低、毛细管压力高、有效应力高以及储层不均质性强、裂缝和微裂缝发育等特征，简称“三低两高一强”。储层损害机理以储层液锁损害、应力敏感损害以及水敏、盐敏损害等为主。文章在分析储层特征及其损害机理的基础上，研究出了适合塔巴庙地区储层特征的屏蔽暂堵钻井完井液技术。该技术在鄂尔多斯北部塔巴庙、杭锦旗等地区10多口探井、评价井及开发井中进行了现场试验，在储层保护和提高天然气单井产量等方面取得了显著效果。     

Estimation of welded joint strength using genetic algorithm approach

The genetic algorithm approach is extended to the estimation of mechanical properties of the joining of brass materials. The mechanical properties of joint parts can be improved by selecting suitable parameters. The strength of the joint parts is affected by many factors, such as the gap between the parts, the torch angle, the quantity of the shielding gases, the pulse frequencies and the electrode tip angle during welding operations. Since all these factors affect the mechanical properties of the welded joint parts, the effects of these parameters need to be cautiously investigated. The present paper describes the use of the stochastic search process that is the basis of Genetic Algorithms (GA), in developing the strength value of the welded parts. Non-linear estimation models are developed using GAs. Developed models are validated with experimental data. The Genetic Algorithm Welding Strength Estimation Model (GAWSEM) is developed to estimate the mechanical properties of the welded joint for the brass materials. The effects of five welding design parameters on the strength value using the GAWSEM have been examined. The results indicated that the changes of the gap between the joint parts and the torch angle have an important effect on the welded joint strength value and the optimum quantity of the shielding gas and the pulse frequencies exist in the tensile strength of welded joints.     

改进铅浇铸方法提高铅层密实度

针对铅铸屏蔽体存在的缺陷，综合考虑产品的结构、冷却顺序、浇铸方法等，通过工艺改进，采用了熔铅后一次性连续浇铸、防氧化、保温、顺序缓慢冷却的铅浇铸工艺方法，保证了屏蔽体铅层密实度要求。     

Rem—meter correction factor for measuring high energy neutrons outside concrete shielding

Correction factors of both Rem-meters,the 10 inch diameter sigle-sphere Remmeter and the standard A-B Rem-meter,were estimated for measuring high energy neutron dose equivalent outside a concrete shielding wall and the effects that the emitted neutron spectra become remarkably“Harder“ peneetrated through a concrete shielding wall,and the energy response of the Rem-meter were taken in account.The estimated results could be applied in the measurement of neutron dose equivalent for the intermediate energy heavy ion reactions to avoid the difficulty induced by the energy response of the Rem-meters.     

MARS14 deep-penetration calculation for the ISIS target station shielding

The calculation of neutron penetration through a thick shield was performed with a three-dimensional multi-layer technique using the MARS14(02) Monte Carlo code to compare with the experimental shielding data in 1998 at the ISIS spallation neutron source facility of Rutherford Appleton Laboratory. In this calculation, secondary particles from a tantalum target bombarded by 800-MeV protons were transmitted through a bulk shield of approximately 3-m-thick iron and 1-m-thick concrete. To accomplish this deep-penetration calculation, a three-dimensional multi-layer technique and energy cut-off method were used considering a spatial statistical balance. Finally, the energy spectra of neutrons behind the very thick shield could be calculated down to the thermal energy with good statistics, and the calculated results typically agree well within a factor of two with the experimental data over a broad energy range. The ¹²C(n,2n)¹¹C reaction rates behind the bulk shield were also calculated, which agree with the experimental data typically within 60%. These results are quite impressive in calculation accuracy for deep-penetration problem.     

Application of artificial neural network methods for the lightning performance evaluation of Hellenic high voltage transmission lines

Feed-forward (FF) artificial neural networks (ANN) and radial basis function (RBF) ANN methods were addressed for evaluating the lightning performance of high voltage transmission lines. Several structures, learning algorithms and transfer functions were tested in order to produce a model with the best generalizing ability. Actual input and output data, collected from operating Hellenic high voltage transmission lines, as well as simulated output data were used in the training, validation and testing process. The aims of the paper are to describe in detail and compare the proposed FF and RBF ANN models, to state their advantages and disadvantages and to present results obtained by their application on operating Hellenic transmission lines of 150 kV and 400 kV. The ANN results are also compared with results obtained using conventional methods and real records of outage rate showing a quite satisfactory agreement. The proposed ANN methods can be used by electric power utilities as useful tools for the design of electric power systems, alternative to the conventional analytical methods.     

仪表控制系统干扰分析与抗干扰措施

在自动控制系统中,干扰存在于整个控制过程中。经现场测量仪表、导线传输、二次仪表或DCS,完成控制运算等功能,然后输出至气动或电动执行机构,干扰将影响整个仪表控制系统的测量准确性。干扰产生的原因按引入的途径主要分为静电感应、电磁感应等。对DCS信号传输系统的干扰包括对进出DCS系统的信号电缆产生的信号干扰和对DCS系统内部通讯电缆产生的信号干扰。不同的生产装置及所在区域,干扰的来源、类型、强度、分布是不同的,所涉仪表设备要求也不完全相同。因此,应有针对性地选用正确合理的抗干扰措施,对不同的对象和环境,采取不同的抗干扰措施。仪表信号传输过程中常见的抗干扰措施有:隔离、屏蔽、对绞、抑制共模干扰的生成与转化及正确接地等。DCS系统中主要是同轴电缆(通讯电缆)的干扰和CRT安装场所的磁场干扰,霍尼韦尔(HONEYWELL)公司提供了针对DCS系统的抗干扰措施。     

多芯屏蔽视频电缆转移阻抗的测试研究

本文讨论了基于"三同轴法"的多芯屏蔽视频电缆转移阻抗的测试原理和方法,据此方法我们设计给出了使用矢量网络分析仪作为信号源及接收器实现多芯屏蔽视频电缆转移阻抗测试的测量装置和测试结果,最后基于测试结果我们对多芯屏蔽视频电缆的屏蔽效能进行了验证,从而证明了多芯屏蔽视频电缆转移阻抗对信息安全的重要意义.     

电磁骚扰滤波器设计与安装

本文论述了电气滤波器的设计及如何正确安装滤波器,使滤波器发挥最大的作用.