High energy‐efficient and privacy‐preserving secure data aggregation for wireless sensor networks

An efficient data process technology is needed for wireless sensor networks composed of many sensors with constrained communication, computational, and memory resources. Data aggregation is presented as an efficient and significant method to reduce transmitted data and prolong lifetime for wireless sensor networks. Meanwhile, many applications require preserving privacy for secure data aggregation. In this paper, we propose a high energy‐efficient and privacy‐preserving scheme for secure data aggregation. Because of the importance of communication overhead and accuracy, our scheme achieves less communication overhead and higher data accuracy besides providing for privacy preservation. For extensive simulations, we evaluate and conclude the performance of our high energy‐efficient and privacy‐preserving scheme. The conclusion shows that the high energy‐efficient and privacy‐preserving scheme provides better privacy preservation and is more efficient than existing schemes. Copyright © 2012 John Wiley & Sons, Ltd.     

一种基于Web文本聚类的用户兴趣发现模型的研究

研究了一种基于Web文本聚类的用户兴趣发现方法．他通过Web文档信息获取，文本的形式表示，以及Web文本聚类方法最终提取用户兴趣知识，并给出了一个设计模型。     

铁路隧道衬砌极限状态法设计验证研究

为了验证极限状态法在隧道衬砌设计中的可操作性,分别采用极限状态法和破损阶段法对铁路隧道衬砌进行了试设计,并对比分析了两种方法的试设计结果。研究结果表明:(1)当衬砌为素混凝土结构时,极限状态法的计算厚度均比破损阶段法计算厚度大,最大相差20 cm,需对极限状态法抗裂验算公式中的调整系数γ_d重新校核,校核后γ_d=1.55;(2)针对钢筋混凝土衬砌结构及明洞结构,极限状态法的设计结果与破损阶段法设计结果基本相同,钢筋混凝土结构的极限状态方程中相关分项系数及调整系数取值是合理的。(3)采用极限状态法(γ_d=1.55)与破损阶段法试设计工程投资相当,极限状态法较破损阶段法工程投资增加237万元,增加1%。     

Two types of new subliminal channels

Two types of new subliminal channels are constructed respectively based on provable secure public key cryptosystems and identity recognition in some network applications. Research shows that there are some new characteristics which are in favor of covert communication in our constructions. It is hard to make the subliminal channels free, and the channels have large capacity and high transmission efficiency. We also point out that the hardness to make the channels free is disadvantageous to the warden who tries to thwart the covert communication.     

“网络银行安全支付系统”的设计与实现

探讨了“网络银行安全支付系统”方案的设计与实现,提出了这一方案的设计模型,重点讨论了基于公钥密码体制和私钥密码体制的身份鉴别、数据加密、数字签名等现代密码技术在“网络银行安全支付系统”中的应用。     

共同沟天然气管道泄漏报警的模型实验

所谓共同沟,即通常所说的地下综合管沟或管廊,是专门用于集中敷设各种市政管线的地下隧道。与传统直接埋地的敷设方式相比,共同沟是一种先进的敷设方式。按相似原理和“最不利原则”设计模型实验,采用甲烷模拟共同沟（狭长空间）中天然气管道的微小泄漏,分析了甲烷的泄漏量和模型的断面宽度对纵向布置的探头报警时间的影响,提出了“单宽泄漏量”的概念,并得出了模型实验的相似条件。根据实验数据的走势,采用抛物线函数进行数据拟合,最终得出报警响应时间的经验公式。     

Electrode Dependence of Tunneling Electroresistance and Switching Stability in Organic Ferroelectric P(VDF‐TrFE)‐Based Tunnel Junctions

Ferroelectric tunnel junctions (FTJs) are promising candidates for nonvolatile memories and memristor‐based computing circuits. Thus far, most research has focused on FTJs with a perovskite oxide ferroelectric tunnel barrier. As the need for high‐temperature epitaxial film growth challenges the technological application of such inorganic junctions, more easily processable organic ferroelectrics can serve as alternative if large tunneling electroresistance (TER) and good switching durability would persist. This study reports on the performance of FTJs with a spin‐coated ferroelectric P(VDF‐TrFE) copolymer tunnel barrier. The use of three different bottom electrodes, indium tin oxide (ITO), La_0.67Sr_0.33MnO₃, (LSMO), and Nb‐doped SrTiO₃ (STO) are compared and it is shown that the polarity and magnitude of the TER effect depend on their conductivity. The largest TER of up to 10⁷% at room temperature is measured on FTJs with a semiconducting Nb‐doped STO electrode. This large switching effect is attributed to the formation of an extra barrier over the space charge region in the substrate. The organic FTJs exhibit good resistance retention and switching endurance up to 380 K, which is just below the ferroelectric Curie temperature of the P(VDF‐TrFE) barrier.     

ESLD: An efficient and secure link discovery scheme for software‐defined networking

Software‐defined networking simplifies network management by decoupling the control plane from the data plane and centralizing it to the controller. As the brain of the network, the controller gains up‐to‐date holistic network visibility via topology discovery. However, as a key service of topology discovery, the link discovery service opens problems on efficiency and security. On the one hand, sending link discovery packets to all ports wastes not only the limited controller resources (such as CPU and memory) but also control channel bandwidth. On the other hand, attackers may use these packets to create fake links and perform link fabrication attack. Because of the centralized control paradigm, wasting controller resources may degrade network performance, and all the fake links may severely poison the network topology, even causing the denial of service or man‐in‐the‐middle attack. In this paper, we propose an efficient and secure link discovery scheme to improve link discovery performance and resist link fabrication attack caused by the software‐defined networking link discovery service. By adopting port classification technique and directionally transmitting packets to appropriate ports, our approach can reduce or eliminate redundant packets and improve link discovery performance. Meanwhile, we adopt the directional packet transmitting approach and the time‐marked hash‐based message authentication code authenticate scheme to resist the link fabrication attack. A prototype system is implemented on the basis of POX controller and Mininet simulator to evaluate our scheme. Simulation results demonstrate that our scheme can solve the link fabrication problems with less overload of both the control plane and the data plane.     

基于Android的手机恶意代码检测与防护技术

随着通信技术以及移动终端的发展,Android系统由于其本身的开源性,滋生了大量的恶意代码。为了满足Android手机用户的安全需求,文中基于Android,采用SVM机器学习思想,构建了恶意代码检测模型,并开发了一套手机恶意代码检测与防护系统,可以对其进行快速检测和深度检测。系统经Android手机测试结果表明,其具有较好的检测精度以及较低的恶意代码漏报率。     

一种AJAX结合CGI的嵌入式瘦Web服务器的研究

针对AJAX与CGI的嵌入式瘦Web服务器软件结构,产生的HTML文件不易于维护和更新的问题,提出了建立一个AJAX处理机制结合CGI程序的嵌入式Web服务器软件结构.应用AJAX处理机制实现了客户端校验和客户端处理,以及无刷新访问服务器端资源.实现后的嵌入式Web服务器降低了嵌入式Web服务器开销的同时,使得页面文件易于维护和更新,是一种既降低成本又易于维护和更新页面文件的网络服务器设计方法.