基于事件逻辑的改进Needham-Schroeder协议安全性证明

安全协议是现代网络安全的基础,密码协议的安全性证明是一个挑战性的问题。事件逻辑是一种描述分布式系统中状态迁移的形式化方法,用于刻画安全协议的形式化描述,是定理证明的基础。用事件序语言、事件类和一个表示随机数、密钥、签名和密文的原子类,给出身份认证协议可以被形式化定义和强认证性证明理论。利用该理论对增加时间戳的Needham-Schroeder协议安全性进行证明,证明改进的Needham-Schroeder协议是安全的。此理论适用于类似复杂协议形式化分析与验证。     

模糊专家理论在炮兵指挥控制系统中的运用

针对炮兵指挥控制系统在作战训练中遇到的问题,在科学地分析了影响效果和相关因素的基础上,依据模糊专家理论的方法和原理,设计了相关的运用决策框架,并提出了运用规则。     

基于贝叶斯的服务通告改装经济性决策方法

改装类服务通告的经济性决策是航空维修企业工程人员的一项重要工作内容。设计了改装类服务通告经济性决策程序;通过服务通告对飞机运营的经济性影响分析构建了成本分解结构,并对不同的成本项目建立了成本评估模型;针对模型的成本影响参数MTBUR和MTBF的估计采用了贝叶斯方法以解决小样本问题;通过投资回收期方法获得评价指标以决定是否进行服务通告改装投资。最后通过实例对决策方法的应用进行说明。此方法能够为航空企业的维修改装决策提供有效的技术支持。     

Complementary Effects of Information Technology Investment on Firm Profitability: The Functional Forms of the Complementarities

Abstract

This paper focuses on developing economic theory on the interrelation between information technology investment components. Three functional forms to model the joint effects between components of investment on firm accounting profitability are identified and empirically tested. The results suggest that the complementarities between components of IT investment can be best modeled by using the multiplicative functional forms, providing a framework to model the joint effects of different factors that impact firm profitability.     

A suboptimal joint bandwidth and power allocation for cooperative relay networks＂ a cooperative game theoretic approach

In commercial networks, user nodes operating on batteries are assumed to be selfish to consume their resources (i.e., bandwidth and power) solely maximizing their own benefits (e.g., the received signal-to-noise ratios (SNRs) and datarates). In this paper, a cooperative game theoretical framework is proposed to jointly perform the bandwidth and power allocation for selfish cooperative relay networks. To ensure a fair and efficient resource sharing between two selfish user nodes, we assume that either node can act as a source as well as a potential relay for each other and either node is willing to seek cooperative relaying only if the datarate achieved through cooperation is not lower than that achieved through noncooperation (i.e., direct transmission) by consuming the same amount of bandwidth and power resource. Define the cooperative strategy of a node as the number of bandwidth and power that it is willing to contribute for relaying purpose. The two node joint bandwidth and power allocation (JBPA) problem can then be formulated as a cooperative game. Since the Nash bargaining solution (NBS) to the JBPA game (JBPAG) is computationally difficult to obtain, we divide it into two subgames, i.e., the bandwidth allocation game (BAG) and the power allocation game (PAG). We prove that both the subgames have unique NBS. And then the suboptimal NBS to the JBPAG can be achieved by solving the BAG and PAG sequentially. Simulation results show that the proposed cooperative game scheme is efficient in that the performance loss of the NBS result to that of the maximal overall data-rate scheme is small while the maximal-rate scheme is unfair. The simulation results also show that the NBS result is fair in that both nodes could experience better performance than they work independently and the degree of cooperation of a node only depends on how much contribution its partner can make to improve its own performance.     

Rough membership function based illumination classifier for illumination invariant face recognition

This paper proposes a face recognition system to overcome the problem due to illumination variation. The propose system first classifies the image's illumination into dark, normal or shadow and then based on the illumination type; an appropriate technique is applied for illumination normalization. Propose system ensures that there is no loss of features from the image due to a proper selection of illumination normalization technique for illumination compensation. Moreover, it also saves the processing time for illumination normalization process when an image is classified as normal. This makes the approach computationally efficient. Rough Set Theory is used to build rmf illumination classifier for illumination classification. The results obtained as high as 96% in terms of accuracy of correct classification of images as dark, normal or shadow.     

灾害中生活类物资的供应分析——以汶川地震重灾区物资供应为例

救灾生活类物资在供应中面临着优化运输路线、降低运输成本、缩短运输时间3个难题。文章采用相关机会多目标规划模型,以汶川地震为例,总结并完善了自然灾害救助中的多物资的协作供应模式,为突发性重大灾害中多物资的协作供应的组织、实施、管理提供参考支持。     

“信息论与编码”双语教学课程建设与实践

近年来,随着信息技术的飞速发展和对外交流的日益频繁,我校和中国其他高校一样在双语教学方面做了一系列的探索与实践。文章就我校开展的《信息论与编码》双语教学课程的特点,提出了在本科教学中的双语教学课程建设与教学改革方案并在教学中取得了良好的效果,具有一定的借鉴意义。     

Apache Web服务器中基于LTI模型的多服务类别比例延迟控制

通过系统辨识建立了Apache Web服务器的线性时不变(LTI>模型,用于描述两类Web客户连接的连接延迟比与服务线程比间的关系,并针对此L"I'I模型,设计了一个控制器。此控制器通过动态分配服务于不同类别连接的服务线程的数量,可实现Wcb服务器端的比例延迟保证,并进一步将此区分服务的控制模型扩展到了面向多个连接类别,通过多个控制器实现了相部两个客户连接类别的比例延迟保证。仿真表明,即使过载状态下并发客户连接的数目急剧变化,闭环系统中的Wcb服务器也能为多个客户连接类别提供比例延迟保证。     

红外图像统计闭值分割方法

经典的统计阈值方法采用某种形式的类方差和作为阈值选择的准则,未考虑实际图像的特性,对目标和背景具有相似统计分布的图像的分割效果不甚理想。为此,利用阈值分割后两个类的标准偏差定义了一个新的阈值选择准则,并通过最小化此准则选择出最佳分割阈值。通过一系列实际图像上的实验结果表明,与现有的几种经典阈值分割方法相比,本方法分割图像的效果更好,尤其是对红外图像分割的效果更为明显。