车用ABS材料的性能和应用研究

汽车上应用的塑料种类繁多,ABS及其复合材料是其中重要的一种,其用量已经接近汽车塑料总用量的8%。本文首先展示了ABS、PC/ABS、PVC/ABS、PA/ABS等材料的性能和结构,从微观结构研究了这些材料的优良综合性能,然后介绍了他们在汽车工业中的广泛应用,从宏观上叙述了他们的具体应用和发展,从而为ABS及其复合材料的改进与深度应用提供了参考和依据。     

加筋板整体屈曲临界应力计算与分析

利用解析法对加筋板稳定性进行了研究,忽略材料非线性的影响,利用理论方法求解四边简支加筋板的整体屈曲临界应力。对有一根加强筋的加筋板,定义板的挠曲函数,将其代入边界方程和协调方程,求解线性方程组的特征方程得到加筋板的临界应力。对有2根或多根加强筋的规则加筋板,利用能量法导出统一计算的公式得到临界应力。最后,利用有限元软件Abaqus和Nastran进行数值仿真,与理论解比较后得出本文计算方法是正确的,可以准确求解加筋板的稳定性问题。     

Comments on enhanced yoking proof protocols for radio frequency identification tags and tag groups

A radio frequency identification (RFID) yoking proof scheme can generate proofs of simultaneous presence of two tags in the range of a specified reader so that an off-line verifier can verify the proofs later. This proof has found several interesting applications. However, many existing RFID yoking schemes are vulnerable to replay attacks. To overcome the weaknesses, Cho et al. proposed a new RFID yoking proof protocol and a new grouping protocol. Unfortunately, Cho et al.’s schemes are still vulnerable to replay attacks. In this paper, in addition to demonstrating weaknesses, we further discuss the rationale behind these weaknesses to provide a guide line for designing secure RFID yoking schemes. Based on the guide line, we propose a new RFID yoking scheme and a new RFID grouping scheme. Performance evaluation shows that our scheme outperforms its counterparts.     

任意Banach空间强伪压缩算子的Ishikawa迭代程序的稳定性

设Ｅ是任意实Ｂａｎａｃｈ空间，Ｔ：Ｅ→Ｅ是强伪压缩一致连续算子且值域有界。证明了Ｍａｎｎ迭代和Ｉｓｈｉｋａｗａ迭代程序是几乎Ｔ－稳定的。     

闵浦二桥主塔下横梁预应力分析及施工技术

上海闵浦二桥工程是一座公轨两用一体化双层特大桥,主桥为独塔双索面连续钢板桁组合梁双层斜拉桥。该文通过理论模拟分析计算,对主塔下横梁施工过程预应力进行了分析,并介绍了其施工技术。     

Using on-board video data for safety analysis – An analysis of right hook crashes involving large buses at signalized intersections

Bus right hook (BRH) crashes at intersections are one of the most common types of crashes for bus carriers, which accounted for as high as 16% of fatal and injury crashes involving large buses at intersections in Taiwan. A BRH crash occurs when a bus and another vehicle traveling in the same direction head into an intersection, but the bus driver makes a right turn across the path of the through-moving vehicle, and both vehicles collide. This study responds to the research needs to identity factors associated with BRH crashes by utilizing in-vehicle data recorder (IVDR) data. A four step analysis procedure was developed, including (1) video data coding, (2) crash sequence analysis to identify crash contributing factors, (3) a case-control study to examine the relationship between the crash contributing factors and crash occurrence, and (4) modeling crash risk in terms of the crash contributing factors to better understand the crash generating process. This study first identified the existence of driver unattended time as the time between when the driver last checked the right back mirror to finally steering for a right turn, indicating the time period wherein the driver did not track the through vehicle on the right side using the right back mirror. It was found that BRH crashes could be attributed to the concurrence of unattended time and the speed difference between the bus and through vehicle. Several recommendations are discussed based on the results to further develop countermeasures to reduce this type of crash.     

长期服役预应力锚索锈蚀状态检测试验与分析

拉力型无粘结预应力锚索是广东省山区高速公路应用十分广泛的一种边坡永久支护结构。在南方多雨湿热这一典型气候的影响下,锚索的长期耐久性能否满足工程设计和应用要求一直是困扰工程界的一大难题。以京港澳高速公路沿线服役14年的边坡预应力锚索为研究对象,结合现场开挖、锚索拉拔和室内试验等多种方法,对该类锚固结构的病害状况和锈蚀原因进行初步分析和讨论,以期为类似边坡锚固工程的设计和施工提供参考。     

基于超松弛解析迭代方法的多导体传输线电磁脉冲响应计算方法

电磁脉冲会在多导体传输线中感应出较高幅值的感应电压和电流,对传输线端接设备等具有严重威胁。所以,对多导体传输线进行建模,分析多导体传输线电磁脉冲响应对于预测电力线的电磁脉冲效应,研究其保护方法具有重要的意义。在多导体传输线建模方面,传统的链参数矩阵算法由于存在大量的矩阵求逆运算,在存在大量线缆时其计算速度较慢。基于此问题,提出了基于解析迭代方法的多导体传输线电磁脉冲响应计算方法(DARIT-field),该方法在求解每根线缆上的响应时,将临近线缆的串扰耦合效应等效为在临近线缆上均匀分布的激励源,计算过程得到了大幅简化。并对基于不同迭代方法的多导体传输线电磁脉冲响应计算方法进行了对比,最后利用实例对每种方法的优、缺点进行了对比。     

专刊致词

尊敬的读者: 在庆祝北京铁路信号工厂(以下简称北信厂)建厂50周年之际,<铁道通信信号>编辑部与北信厂联合向您呈上<铁道通信信号--北京铁路信号工厂专刊>.专刊收编了北信厂在客运专线建设、列控系统设备产业化技术设计、生产制造、国产化实施、现场服务、质量管理、信息化建设等方面的相关文章,以飨同行与读者.     

生命在平凡中闪光——纪念杨庆文同志

“我们对着茫茫的珠江痛悼您，江水哽咽；我们对着苍翠的青山痛一阵您，群山无言。我们的好同事，您别走……”声声深情呼唤，无法留住他远去的脚步。