线膛炮身管内表面光整加工的方案研究

火炮身管珩磨中存在着阴线表面及阳线棱边加工不到的问题,在对火炮射击精度要求越来越高的今天,采用新方法对火炮身管进行精密加工变得越来越迫切。通过分析身管内表面对射击过程的影响后,提出了3种精密加工的方法,分别是强制螺旋流法、高压水射环流法、磁流变液法。设计了相应的实施机构,并分析了加工的原理、材料去除的机理。这些具体的实施身管内表面光整加工的方案可为火炮制造提供参考。     

美式箱变、户外环网柜交流无间隙氧化锌避雷器选用

文章针对美式箱变、户外环网柜配用的交流无间隙氧化锌避雷器主要电气指标的选择,从国家相关标准的规定和运行经验的角度,分析和对比了国产和进口两系列产品,说明了避雷器应优先采用符合国家标准的国产品,若确实需要用进口产品时则应选择能满足我国国标各项指标要求的且残压较小的产品。     

圆筒形薄钢壳物体纵向磁化状态的简化建模方法

积分方程法计算过程中,所得到的系数矩阵是稠密矩阵,随着剖分单元的增多,计算资源的需求将快速增长,可能会在一些实际工程问题的计算中造成一些障碍.根据薄钢板的磁化特点,将圆筒形薄钢壳物体的纵向磁化等效为圆环形体磁化强度分布和圆环形线磁荷分布2种形式,可将原有的二维轴对称问题简化为一维形式,用于快速地建立圆筒形薄钢壳物体纵向磁化状态的数学模型.圆环形体磁化强度分布和圆环形线磁荷分布与三维积分方程法相比,可以得到几乎相同的磁化强度和外部磁场分布,只存在很小的误差.计算结果表明,所得到的新方法只需要少量剖分单元就可以满足计算精度要求,且大大减少了计算资源,加快了计算速度,非常适用于工程计算.     

Effect of contact detecting method on pre‐heating time and tensile strength in A6061, A2017 aluminium alloy to SUS304 stainless steel friction welding

This study investigated the electrode life and the electrode degradation mechanism during alternate resistance spot welding of galvannealed steel sheets and bare steel sheets. As a result, it was found that the electrode life in this type of welding was extremely short in comparison to welding of only galvannealed steel sheets. The reason for this short life is explained by the sticking of the alloy layers formed on the electrode top to the bare steel sheet surface, so that the narrower and sharper shape the original electrode top is the better to prolong the life. Although the ring-shaped nuggets were not formed during alternate resistance DC welding, the electrode degradation mechanism is similar to that during the resistance DC welding of only galvannealed steel sheets.     

世茂国际广场电气设计工程总结

介绍了世茂国际广场的工程概况,对电源供电、电力配电、照明、消防报警及联动控制、楼宇自动化、防雷及接地、选用节能设备部分作了较系统的阐述。该工程引进35kV电源,设置35kV变电站;供电采用35/6kV、6/0.4kV二次降压;在249.5m高度的主体建筑内,6kV配电采用环网开环配电方式;采用6kV高压冷冻机及高压就地补偿。     

注射模环形型芯抽芯机构设计

介绍了塑料管注射模的环形型芯抽芯机构。论述了该机构的工作原理及主要结构零件的设计要点。     

离子刻蚀尼龙1010样品的电镜研究

研究了扫描电镜观察用尼龙１０１０样品的离子刻蚀条件，观察到尼龙１０１０正环状球晶的晶片结构为中心放射生长，晶片扭曲、支化。     

Cryptanalysis of Chen et al.’s multi-secret visual cryptography scheme

Abstract

In a (k, n) visual cryptographic scheme (VCS), a secret image is encrypted into n shadow images in such way that any k or more shadows can be superimposed to visually decode the secret, and less than k shadows cannot obtain any information on the secret image. Most VCSs only share one secret image. A (k, n, s) multi-secret VCS (MVCS) is a (k, n)-VCS, which can share s secret images. Recently, Chen et al. introduced a novel (2, 2, 4)-MVCS. However, their scheme is insecure. The threshold property of Chen et al.’s (2, 2, 4)-MVCS is compromised. In this paper, we show how an attacker retrieves the secret information of Chen et al.’s (2, 2, 4)-MVCS from one shadow image.     

银川地区SDH电力光纤环网的建设

根据银川供电局近4年来SDH光纤环网施工实践,就光纤通信组网和建设中网络拓扑结构、光缆选型、设备选型、电路配置和网络应用等关键性问题进行了探讨.     

大直径圆筒楔环联接结构的研究与设计

以试验为基础, 确定大直径圆筒楔环联接结构中楔环的受力状况, 并以此为依据, 设计出利用中小工厂的现有设备、材料即可加工的楔环联接结构, 使它的广泛推广成为可能。