基于静态和动态混合分析的内存拷贝类函数识别

缓冲区溢出等内存错误漏洞的产生往往来自对内存拷贝类函数的不当使用. 对二进制程序中的内存拷贝类函数进行识别有利于发现内存错误漏洞. 目前针对二进制程序中内存拷贝类函数的识别方法主要借助静态分析来提取函数的特征、控制流、数据流等信息进行识别, 具有较高的误报率和漏报率. 为了提高对内存拷贝类函数识别的效果, 提出一种基于静态和动态混合分析的技术CPSeeker. 所提方法结合静态分析和动态分析各自的优势, 分阶段对函数的全局静态信息和局部执行信息进行搜集, 对提取到的信息进行融合分析, 进而识别二进制程序中的内存拷贝类函数. 实验结果表明, 尽管CPSeeker在运行时间上有所增加, 但在内存拷贝类函数识别的效果上, 其F1值达到了0.96, 远优于最新的工作BootStomp、SaTC、CPYFinder以及Gemini, 并且不受编译环境(编译器版本、编译器种类、编译器优化等级)的影响. 此外, CPSeeker在真实的固件测试中也有更好的表现.     

记忆合金在弹箭引信安全系统中的应用研究

研究利用Ti—Ni记忆合金的记忆效应，设计制作了引信安保机构原理样机，并对样机进行了解除保险可靠性试验、勤务处理安全性试验和气体炮试验。经一系列试验研究证明，记忆合金在弹箭引信安全系统中做保险件，具有保险、延期解除保险和驱动负载的综合能力。为引信多样化的安全设计提供了一种新的途径。     

基于时间约束的优化编码传输算法

考虑到对数据包延迟等服务质量要求比较高的流媒体应用,文章研究了在有记忆接收节点模型也即接收节点可以缓存多个数据包的前提下,数据包有延迟约束的无线网络中基于网络编码的广播调度问题,目标在于最小化超过延迟约束数据包的数目。本文提出一种利用着色图的方法来进行编码调度的算法,可以显著减少超过延迟约束数据包的数目,为以后针对QoS需求的网络编码问题提供了参考。模拟实验表明相比于接收节点丢弃暂时无用数据包的无记忆模型,在有记忆模型下我们的算法可以在很多情况下有效地降低超出延迟约束率,这对时间关键的应用非常重要。     

二维磁性材料与自旋系统研究进展

自旋系统是一类基于电子自旋工作的器件,具有高速、低功耗等优点,其中磁存储器被认为是下一代存储器的领跑者之一。二维材料有着天然的界面性能优势,接近微缩极限的尺寸特点,以及二维结构带来的物理特性,在自旋系统中有望得到广泛运用。本文概述了二维材料在自旋领域的最新研究进展,介绍了一些常见的二维磁性材料,讨论了基于二维材料的二维自旋器件,以及回顾了基于二维材料的磁性调控,最后总结了这一领域仍然面临的挑战,并对未来发展进行了展望。     

申威处理器硬件数据预取技术的实现

硬件数据预取技术可以有效提升处理器的访存性能,是申威处理器性能优化过程中亟需突破的一项技术。硬件开销和处理器架构的制约是硬件预取技术实现中的主要难点。借鉴学术界对硬件预取技术的研究成果和工业界的应用现状,紧密结合申威处理器的结构特点,研究了申威处理器硬件预取技术的实现方法。以流预取为例,在处理器核心面积增加0.97%的情况下,硬件预取技术的应用可以将目前申威处理器的整数性能平均提升5.17%,最高提升28.88%;浮点性能平均提升6.39%,最高提升30.11%。     

巨型浮吊船电力系统动态响应的联想记忆识别

巨型浮吊海洋工程船的作业依赖于船舶电力系统的稳定运行。这类船上大功率变频器、大功率交流电机等设备的大量应用,使得控制系统受干扰影响严重,检测到的动态响应常常含有干扰成分,给电力自动化设备的反馈控制带来了困难。联想记忆具有按信息内容检索的功能,可以模仿人脑进行联想,处理缺损和不确定的信息,具有容错功能。根据联想记忆原理,运用Hopfield网络结构,对Hebb学习规则进行了改进,构建了自联想离散Hopfield网络。该网络通过对动态响应标准样本进行学习,得到了稳定模式,在受干扰污染、信息缺损的巨型浮吊船电力系统动态响应的识别中表现出了良好的滤除干扰的能力。     

Phase change memory alloys: GST cell array characterization using picosecond ultrasonics

Phase change random access memory alloys (PRAM or PCM) are a class of non-volatile memory that is thought as viable alternatives to flash memory technology or to supplement other memory technologies depending on the end applications and its key performance requirements. Ge₂Sb₂Te₅ alloy (GST) is the most widely used chalcogenide material for PCM application, and has many unique properties, including strong temperature-dependent film properties, low thermal conductivity, and high electrical resistivity. Picosecond ultrasonics was used to make non-contact, non-destructive measurements of GST films on blanket wafers and directly on product wafers. On-product wafer measurements were made on various via array (0.5 μm and 1 μm between cell edges with CD size from 250 to 800 nm). Measurements have shown excellent correlation to cross-section SEM and were consistent with CMP polish times for both blanket and pattern wafer measurement. Excellent repeatability based on extensive measurements demonstrates the capability and reliability of picosecond ultrasonic technology. Picosecond ultrasonic measurements also provide rapid characterization across the whole wafer at production-worthy throughputs.     

The thermochemical behavior of some binary shape memory alloys by high temperature direct synthesis calorimetry

The standard enthalpies of formation of some shape memory alloys have been measured by high temperature direct synthesis calorimetry at 1373 K. The following results (in kJ/mol of atoms) are reported: CoCr (−0.3 ± 2.9); CuMn (−3.7 ± 3.2); Cu₃Sn (−10.4 ± 3.1); Fe₂Tb (−5.5 ± 2.4); Fe₂Dy (−1.6 ± 2.9); Fe₁₇Tb₂ (−2.1 ± 3.1); Fe₁₇Dy₂ (−5.3 ± 1.7); FePd₃ (−16.0 ± 2.7); FePt (−23.0 ± 1.9); FePt₃ (−20.7 ± 2.3); NiMn (−24.9 ± 2.6); TiNi (−32.7 ± 1.0); TiPd (−60.3 ± 2.5). The results are compared with some earlier experimental values obtained by calorimetry and by EMF technique. They are also compared with predicted values on the basis of the semi empirical model of Miedema and co-workers and with ab initio calculations when available. We will also assess the available information regarding the structures of these alloys.     

Martensitic transformation of Ti50Ni30Cu20 alloy prepared by powder metallurgy

Phase transformation behavior of Ti50Ni30Cu20 shape memory alloys prepared by powder metallurgy is analyzed with respect to the duration of mechanical alloying. The processed blends were studied by differential scanning calorimetry and room temperature X-ray diffraction. The martensitic transformations evidenced by thermal scans are discussed in correlation with the relative phase content obtained from the refinement of the X-ray diffraction patterns.