DroidFAR:一种基于程序语义的Android重打包应用抗混淆检测方法

为了使Android平台重打包应用检测的方法在面向大规模移动应用中既能实现快速、准确地检测重打包应用又能对抗代码混淆攻击,本文提出了一种基于程序语义的重打包应用抗混淆检测方法.该方法首先进行粗粒度的检测,即先将应用的程序依赖图抽象成程序语义特征,通过计算程序语义特征之间的相似性,实现快速的可疑重打包应用检测;然后使用程序依赖图作为应用的特征,完成可疑重打包应用细粒度的准确检测.基于文中的方法设计并实现了原型系统DroidFAR(Fast,Accurate and Robust).实验结果表明,本文方法检测的准确率达到95.1%,误报率低于1.2%,且能够有效地抵御代码混淆攻击.     

Top pair production in the littlest Higgs model with T-parity

In the framework of the littlest Higgs model with T-parity, we study the top pair production at the next generation colliders like LHC and ILC. We find that the order O（αs） corrections to the standard model top pair production cross section at LHC can be very small and the magnitude is below 1%. However, the magnitude of corrections to the standard model top pair production rate at ILC may be over 5% for reasonable values＇of the parameters. Besides this, the corrections to the asymmetry ALR（tt） may be more sizable. Therefore, the top pair production at ILC may serve as a probe of the littlest Higgs model with T-parity, especially the asymmetry ALR（tt）.     

抗尺度变换的矢量地图匹配导航方法

相比于景象匹配导航,矢量地图匹配导航具有无损变换、空间效率和时间效率高等优势。针对矢量地图匹配导航过程中实时图与基准图尺度不一致的情况,提出了一种抗尺度变换的位姿解算算法,并将其应用到矢量地图匹配导航系统中。该算法将尺度因子作为未知参数,与位姿参数一起进行估计,从而避免了尺度差异造成的位姿解算误差较大的问题。仿真结果表明,抗尺度变换的位姿解算算法用于小尺度变换下的矢量地图匹配时,经度标准差和纬度标准差均小于0.06″,航向角标准差小于0.06°。     

6轮数据加密标准的演化分析

采用线性逼近的思想,提出了一种基于Hamming距离的遗传算法适应度函数模型.在此基础上,利用遗传算法对1～6轮数据加密算法的不同模式长度的部分密钥进行了定量的对比分析实验,对6轮数据加密算法进行演化分析可获得21 bit的未知密钥.结果显示:适应度函数设计与密码分析对象的安全强度是影响演化密码分析效果的关键因素;由于演化技术是有指导的随机性或概率性技术.在一定数量的实验中,运行时间和成功率存在较明显差异;在一定程度上增大种群规模,明密文数量或演化代数能够取得更好的分析效果.     

基于三元工质扩散吸收式制冷系统的浓度研究

文中建立以氨-水-氦为工质的扩散吸收式制冷系统。采用对比试验,在三种工质浓度下,对比由于工质浓度不同而对系统温度造成的不同影响,用温度曲线的方式描述了系统各参数的变化,对扩散吸收式制冷系统的浓度设计具有一定的参考价值。     

P507萃取纯化V(Ⅳ)制备草酸氧钒及其物化性能

从钒渣钠化焙烧后的含钒浸液中, 采用2-乙基己基磷酸单-2-乙基己酯(P507)萃取-草酸反萃取-蒸发结晶新工艺制备了草酸氧钒, 优化了草酸反萃取工艺的条件. 研究结果表明, 采用2.0 mol/L草酸溶液, 在水相与有机相体积比V(A):V(O)为1:5时, 于50 ℃下经过三级(理论)反萃取, 钒的反萃取率可达到99.98%, 反萃取液中VOC₂O₄浓度可达290.0 g/L以上. 负载的反萃取液经膜过滤除去残留有机物后, 再经蒸发结晶得到草酸氧钒. 采用X射线衍射、 X射线能谱、 热场发射扫描电子显微镜及同步热分析等手段表征了草酸氧钒的物化性能, 结果表明, 草酸氧钒的结构为VOC₂O₄·2H₂O, 粒度分布均匀, 结晶度高.     

面向SDN的安全威胁及其对抗技术研究

软件定义网络(software-defined networks,SDN)通过逻辑集中的网络控制,提高了网络编程的灵活性,但由此引入的安全威胁若被攻击者利用将会直接危及整个网络架构。针对SDN的特性,将安全威胁分类汇总为入侵攻击、异常攻击、DDoS和DoS攻击、欺骗攻击4类。鉴于DDoS和DoS攻击在SDN环境下比在传统网络环境下更具针对性且危害性更大,因此着重从攻击原理、手段和效果方面进行系统论述。最后根据攻击类型对现有对抗方案进行了介绍,并根据现有技术的不足提出未来的研究方向与发展趋势。     

Modelling Debye Dielectric Relaxation in Monohydroxy Alcohols

The Debye relaxation of dielectric spectroscopy exists extensively in monohydroxy alcohols.We model the relaxation based on the infinite-pseudospin-chain Ising model and the Glauber dynamics,and the corresponding complex permittivity is obtained.The model results are in good agreement with the experimental data of 3,7-dimethyl-1-octanol,2-ethyl-1-hexanol and 5-methyl-2-hexanol in a wide temperature range.Moreover,in the model parameters,the sum of the mean-field interaction energy and two times the orientation is nearly twice the hydrogen bond energy,which further states the rationality of this model.     

介质阻挡放电等离子体中·OH和HO2·自由基的数值模拟计算

在介质阻挡放电等离子体N2/O2/H2O/HCHO体系中通过解Boltzmann方程, 得到电子能量分布函数, 利用得到的电子能量分布函数计算电子-分子碰撞反应速率常数. 然后把有关的反应速率常数带入速率方程, 计算得到该体系在介质阻挡放电时,·OH、HO2·和电子的浓度随时间的演变以及·OH、HO2·浓度随H2O、O2摩尔分数的变化, 并将模拟结果与实验值进行了对比, 两者符合得较好.     

Simulations of the flipping images and microparameters of molecular orientations in liquids according to the molecule string model

The relaxation dynamics of liquids is one of the fundamental problems in liquid physics,and it is also one of the key issues to understand the glass transition mechanism.It will undoubtedly provide enlightenment on understanding and calculating the relaxation dynamics if the molecular orientation flipping images and relevant microparameters of liquids are studied.In this paper,we first give five microparameters to describe the individual molecular string(MS) relaxation based on the dynamical Hamiltonian of the MS model,and then simulate the images of individual MS ensemble,and at the same time calculate the parameters of the equilibrium state.The results show that the main molecular orientation flipping image in liquids(including supercooled liquid) is similar to the random walk.In addition,two pairs of the parameters are equal,and one can be ignored compared with the other.This conclusion will effectively reduce the difficulties in calculating the individual MS relaxation based on the single-molecule orientation flipping rate of the general Glauber type,and the computer simulation time of interaction MS relaxation.Moreover,the conclusion is of reference significance for solving and simulating the multi-state MS model.