Yahalom协议的分析及改进方案

Yahalom协议及BAN对Yahalom协议的改进协议都存在着安全缺陷.采用串空间模型,运用"理想"和"诚实"作为工具对Yahalom协议的安全性进行了分析并找出了该协议遭受攻击的主要原因,同时提出了Yahalom协议的一种改进方案.     

认证测试方法在安全协议分析中的应用

系统研究了认证测试方法的应用原理，并将该方法应用于包含两方主体的Needham -Schroeder和包含三方主体的Woo—Lam认证协议的分析。最后通过比较认证测试方法和BAN逻辑在安全协议分析的应用说明了认证测试方法具有分析过程简捷、形式化描述规范的优点。     

基于串空间的KryptoKnight协议分析及与逻辑化方法的比较

网络安全在信息时代非常重要,而网络安全的关键问题之一是安全协议.本文通过串空间模型对KryptoKnight协议进行了分析,得出该协议是安全的.并对串空间模型和BAN逻辑方法进行了比较.     

Multimedia displays for conceptual discovery: information seeking with strand maps

This article explores the use of a multimedia search interface for digital libraries based on strand maps developed by the American Association for the Advancement of Science. As semantic-spatial displays, strand maps provide a visual organization of relevant conceptual information that may promote the use of science content during digital library use. A study was conducted to compare users' cognitive processes during information seeking tasks when using a multimedia strand maps interface, versus the textual search interface currently implemented in the Digital Library for Earth System Education. Quantitative and qualitative data from think-aloud protocols revealed that students were more likely to engage with science content (e.g., analyzing the relevance of science concepts with regard to task needs) during search when using the strand maps interface compared to those using textual searching. In contrast, students using a textual search interface engaged more frequently with surface-level information (e.g., the type of a resource regardless of its science content) during search and retrieval. As a multimedia search interface for digital libraries, strand maps appear to be promising tools to promote conceptual discovery and learning through content-based processes that promote learner engagement with relevant science knowledge.     

合金钢方坯连铸机铸圆坯改造实践

总结了鄂钢电炉厂合金钢连铸机方坯改铸圆坯的实践。通过改造，使该台连铸机同时具备生产圆坯和方坯的条件，对拓宽市场、加大钢坯生产量提高经济效益和降低生产成本有着非常重要的意义。     

A methodological approach for finite element modeling of pretensioned concrete members at the release of pretensioning

This paper presents a methodological approach for finite element simulation of pretensioned concrete members. The three-dimensional analysis presented in this paper involves a rectangular [150 mm (6 in.) tall × 150 mm (6 in.) wide × 2440 mm (96 in.) long] concrete member hosting one 15-mm (0.6 in.) diameter 7-wire low-relaxation Grade 1860 MPa (270 ksi) prestressing strand. The finite element models are divided into two general classifications: (i) concentrically pretensioned, and (ii) eccentrically pretensioned. The finite element models are analyzed based on elastoplastic material behaviors as well as mesh sensitivity. Two approaches are examined for finite element modeling of the pretensioned concrete specimens: (i) the extrusion technique utilizing friction-based contact simulations, and (ii) the embedment technique simulating equivalent responses while being a computationally less expensive solution. A comparative analysis is presented to measure the validity as well as accuracy of the findings by the finite element techniques against the commonly used closed-form solutions based on elastic beam theory. The validity of the finite element approach is further verified by comparative analysis of the analytical data against the experimental findings. The paper concludes that the embedment technique provides an accurate and numerically efficient alternative in comparison with the extrusion method for the simulation of the pretensioned concrete members. While the extrusion technique provides more detailed information corresponding to the regions located immediately around the prestressing strands, including the interface overstresses and bond slippage, the embedment technique appears to have the ability to simulate the overall response of the concrete members with comparable accuracy.     

~(60)Coγ射线诱发的中国田鼠V_(79)细胞和小鼠胸腺细胞DNA单链断裂及其修复的研究

本文对~(60)Co γ射线诱发的中国田鼠肺成纤维细胞(V79)和小鼠离体胸腺细胞 DNA 单链断裂及其重接修复进行了实验研究。实验结束表明,两种细胞 DNA 单链断裂的程度分别在30Gy 和10Gy 剂量范围内与剂量呈线性相关;V79细胞 DNA 单链断裂的重接修复包含有快修复和慢修复过程;在不加血清的 TC199培养液中 V79细胞 DNA 断链仍能重接修复,而离体小鼠胸腺细胞在不加血清的 TC199或 RPM11640培养液中其 DNA 断链均不能重接修复,表明不同细胞 DNA 断链的重接修复所要求的细胞培养条件不同。     

基于伪ID的RFID认证协议及串空间证明

安全有效的认证协议是对RFID系统安全的有力保障,适宜的形式化分析方法能为RFID认证协议提供有效的证明。设计了基于伪ID的RFID认证协议,伪ID由标签ID、标签认证数值和随机数产生。标签ID不出现在协议执行过程中,减少了系统遭受攻击的可能性。协议通过标签ID、标签认证值和随机数的Hash运算实现认证。利用串空间模型对协议进行形式化分析,建立认证协议的串空间模型丛图,证明了协议的保密性和匿名性。通过分析常规的基于Hash函数的认证协议的性能可知,该协议在使用较低运算成本的情况下可以抵抗多种攻击,并能够完成标签和读写器之间的双向认证。     

SWRH82B钢Φ14 ~ 15 mm盘条的生产实践

采用Cr、V微合金化技术开发了抗拉强度≥1180 MPa的SWRH82B钢Φ14～15 mm盘条(/%:0.79～0.82C,0.15～0.35Si,0.60～0.90Mn,≤0.025P,≤0.006S,≤0.015As,0.26～0.32Cr,0.04～0.07V)。水钢用100 t转炉-LF精炼-160 mm×160 mm连铸(结晶器带电磁搅拌)-铸坯缓冷-高速线材轧制-Stellmor风冷的工艺流程生产的SWRH82B钢Φ14～15 mm盘条组织的索氏体化率达到了95%。盘条的抗拉强度为1 180～1 270 MPa,断面收缩率为27.0%～37.5%。盘条满足大规格高强度矿用钢绞线的要求。     

特殊非对称型12流35 t中间包的水模拟试验和控流装置的优化

通过几何相似比1:3的水模型试验分析了钢厂特殊非对称型12流200 mm×285 mm铸坯的35 t中间包的结构特点,得出原中间包不对称度较大,结构不合理,整体混匀效果和各流的一致性较差,需要设计有效的控流装置以改善其内部流动。水模拟结果表明,通过所设计的相对较大的冲击区和两个导流孔的优化方案,使得中间包的整体混匀效果和各流一致性都得到明显改善,其总体死区比例相对原型的27.96%降至8.94%;其各流平均停留时间的标准差降低74%。