Development of compositionally modulated multilayer Zn-Ni deposits as replacement for cadmium

Compositionally modulated multilayer (CMM) Zn-Ni deposits were electrodeposited from single acidic bath (pH = 4.7) by using a potentiostatic sequence. The Zn and Ni composition in the alloy was tailored as a function of distance from the steel substrate. X-ray diffraction studies of the deposit showed the presence of γ-phase with a composition of Ni₅Zn₂₁. The corrosion properties of modulated multilayer coatings were studied in 5% NaCl solution using electrochemical corrosion techniques. The polarization resistance of the deposits varied as a function of Ni content between 1700 and 3440 Ω. CMM Zn-Ni with 20 wt% Ni exposed in ASTM B117 salt spray test did not show any red rust formation after 400 h.     

适用于Android智能手机的灰度均值水印算法

提出了一种适用于Android智能手机的灰度均值数字水印算法。在嵌入阶段,将经过像素重新组织的水印图像嵌入载体图像中;在提取阶段,先提取出初始水印,再判断初始水印是否需要区域替换,如果需要,则进行区域替换,否则不进行;最后,将初始水印还原成所需的水印图像。实验表明,该算法在具有良好水印透明性的同时,对JPEG压缩、加噪声、裁剪等常见的攻击具有鲁棒性。     

利用多维分级Cache替换策略减少对PCM内存写回量

寻找新型存储材料代替DRAM内存是当前的一个研究热点。相变存储PCM因其具有低功耗、高存储密度和非易失性的优点受到广泛的关注,然而PCM的可擦写次数有限,要用作内存必须考虑如何减少对其的写操作。针对该问题,一种有效的解决方法是优化Cache替换策略,减少Cache中脏块被替换出的数量。现有研究主要通过在插入和访问命中时给脏块设定较高的保护优先级来达到给脏块额外保护的目的,但是在降级过程中不再对脏块与干净块进行区分,这导致Cache可能在存在大量干净块的情况下仍然先替换脏块。提出一种新型的Cache替换策略MAC,它通过一个多维分级结构在脏块与干净块之间设置了不可逾越的界限,使得脏块能得到更有力的保护。模拟实验表明,相对LRU替换策略,MAC以较低的硬件开销代价平均减少约25.12%的内存写,同时对程序运行性能几乎没有影响。     

几个签密方案的密码学分析与改进

对六个签密方案进行了安全性分析,指出它们都存在保密性的安全问题,其中两个方案还存在不可伪造性的安全问题。对每一个安全问题都给出了具体的攻击方法,并使用加密部分绑定发送者、签名部分绑定接收者、验证等式不含明文信息和部分私钥生成时绑定公钥的方法对每一个方案给出了改进措施。对改进后的方案给出了随机预言机模型下的安全性证明。安全分析表明,改进方案是安全的。最后提出了设计签密方案时必须注意的几个问题。     

基于原型监测的特高拱坝软弱带置换效果评价

特高拱坝蓄水后所受的总推力巨大,坝肩是关键受力部位,合理评估置换体加固效果将直接影响到工程的安全性和经济性。以原型监测为基础,采用实测值分析与理论推导相结合的方法,对小湾特高拱坝坝肩回填效果进行分析和评价。结果表明：接触带压应力过程线经历了增大和稳定2个阶段;接缝开合度过程线经历了温升压密、温降张开和稳定3个阶段,开合度与温度分段线性相关;围岩呈稳定态势,变形主要集中在前3个月,离洞口6m范围受开挖影响较大,16m为围岩松动圈范围。钢筋温度应力的理论值与实测值偏差较小。综合分析认为：回填体与围岩结合良好,有很好的传力性能;回填体及围岩应力、变形正常;回填效果好。     

木桩固基卵石换填法处理淤泥地基施工技术

木桩固基卵石换填法处理淤泥地基可以大幅减少卵石换填层厚度和换填量,采用该方法对渭南市涧峪水库城市供水应急工程中淤泥地基进行了处理,结果表明:工程基槽开挖量、管槽回填量和换填材料用量均大幅减少,软基处理效果好,取得了良好的经济效益和社会效益。     

An automatic subdigraph renovation plan for failure recovery of composite semantic Web services

A Web service-based system never fulfills a user＇s goal unless a failure recovery approach exists. It is inevitable that several Web services may either perish or fail before or during transactions. The completion of a composite process relies on the smooth execution of all constituent Web services. A mediator acts as an intermediary between providers and consumers to monitor the execution of these services. If a service fails, the mediator has to recover the whole composite process or else jeopardize achieving the intended goals. The atomic replacement of a perished Web service usually does not apply because the process of locating a matched Web service is unreliable. Even the system cannot depend on the replacement of the dead service with a com- posite service. In this paper, we propose an automatic renova- tion plan for failure recovery of composite semantic services based on an approach of subdigraph replacement. A replacement subdigraph is posed in lieu of an original subdigraph, which includes the failed service. The replacement is done in two separate phases, ofltine and online, to make the recovery faster. The ofitine phase foresees all possible subdigraphs, pre-calculates them, and ranks several possible replacements. The online phase compensates the unwanted effects and executes the replacement subdigraph in lieu of the original subdigraph. We have evaluated our approach during an experiment and have found that we could recover more than half of the simulated failures. These achievements show a significant improvement compared to current approaches     

基础换填法在南水北调北汝河倒虹吸工程中的应用

北汝河倒虹吸工程的构筑物建基面位于地表下18m深的粘土岩层上,该岩层的不规则裂隙导致施工降排水效果不佳,该问题一度困扰施工进展.在充分对比、分析及论证的基础上,提出了基础换填方法,有效解决了这一难题,为工程赢得了时间和效益.     

三维地形显示中数据缓存与调度算法研究

存储调度是大规模地形可视化算法的重要组成部分,但近年来对其研究较少。本文重点讨论了可视化实现中比较常用的调度算法:系统调用和操作系统页面置换算法,对其进行了详细的分析,指出两种方法相同的本质:都是依据程序执行的过程中对内存的局部访问特点设计的。可视化过程对内存的需求不同于程序执行的局部性,地形浏览有其特殊性。根据地形浏览的特点,本文提出了一种专门用于地形浏览的预取和替换相结合的存储策略。并用两个评价准则验证了方法的有效性。