Directional neighbor discovery in 60 GHz indoor wireless networks

Signal propagation in the 60 GHz band significantly differs from that in the 2.4 and 5 GHz bands. In particular, the signals are often reflected in indoor settings in this band. Directional antennas can help limit the impact of reflection, but make the process of neighbor discovery complex. We consider this problem in this paper. We examine two approaches (a) direct discovery where each node explicitly discovers its neighbors, and (b) gossip-based discovery where nodes exchange information about their already discovered neighbors. We analyze the two approaches and validate our models via simulations. We examine the impact of system parameters such as varying beamwidth and node density.     

Increased Vulnerability to Stress Following Opiate Exposures: Behavioral and Autonomic Correlates.

The authors used rats to study the impact of a history of opiate exposures on behavioral and autonomic responses to restraint stress. Brief restraint (30 min) provoked tachycardia and a pressor response, anxiety (as indexed by social interaction), grooming, and reduced exploration. The pressor response was reduced at 1 day, but not 7 days, after last opiate exposure; tachycardia was unaffected (Experiment 1). Stress-induced anxiety was potentiated 1 and 7 days after last opiate exposure (Experiment 2), and this potentiation was a function of dose (Experiment 3) and duration (Experiment 4) of opiate exposure. The results show that a history of opiate exposures alters vulnerability to stress and has implications for understanding coping, anxiety, and emotionality in former opiate users. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

越流区承压含水层特殊脆弱性评价模型的参数灵敏度分析

承压含水层特殊脆弱性评价中存在着诸多不确定性因素,影响评价结果的可靠性。本文分别运用局部灵敏度分析和Morris法的全局灵敏度分析对承压含水层特殊脆弱性评价模型中的参数进行灵敏度分析,为提高模型评价结果的可靠性奠定了基础。以济宁市承压含水层特殊脆弱性评价为例,对模型中各参数灵敏度进行分析。结果表明：弱透水层厚度、承压水与潜水水头差、弱透水层垂向渗透系数对承压含水层脆弱性评价模型的影响最为显著,弱透水层密度、分配系数与有效孔隙度对模型的影响次之,潜水含水层中污染物浓度与弱透水层弥散度对模型的影响最小;全局灵敏度分析结果显示,除弥散度外的各参数灵敏度系数的绝对值随着承压含水层脆弱等级的升高而降低。     

Indoor Ad Hoc Proximity-Location Sensing for Service Provider Selection

There are protocols that can be used by mobile clients to discover service providers in foreign networks to which they get attached, e.g., SDP of Bluetooth and SLP of IETF. These protocols do address service discovery, but do not address the selection of a service provider among a set of candidates according to a physical proximity of the client and service provider. The goal of the research described in this paper is to integrate proximity-based selection mechanisms to service discovery protocols. We present in this paper protocols that allow nomadic clients to discover and select service providers according to physical proximity.     

基于贝叶斯网络模型的信息检索

贝叶斯网络模型是解决信息检索领域问题的有效手段，因为它可以表示术语间的条件概率和概念语义，并依此预测用户查询和文档间的相似度。本文对信息检索中的贝叶斯网络模型做了若干改进，加入了一些新特征，并用实验结果证明了通过提高贝叶斯网络模型的质量和调整其中的参数，我们的方法取得了较好的检索效果。     

基于战斗部数值仿真系统的杀伤概率计算

通过战斗部威力场和杀伤效能仿真系统,建立了一套空空导弹战斗部杀伤效能评估系统。利用系统分析了两种战斗部对空中典型目标F-35和“战斧”巡航导弹在不同交会条件下的杀伤概率。结果表明,该系统为战斗部的方案选择、结构优化和效能评估提供有效参考。     

Bluetooth scatternets: criteria, models and classification

Bluetooth ad hoc networks are constrained by a master/slave configuration, in which one device is the master and controls the communication with the slave devices. The master and up to seven active slave devices can form a small Bluetooth network called a piconet. In order to build larger network topologies, called scatternets, the piconets must be interconnected. Scatternets are formed by allowing certain piconet members to participate in several piconets by periodically switching between them. Due to the fact that there is no scatternet formation procedure in the Bluetooth specification, numerous different approaches have been proposed. We discuss criteria for different types of scatternets and establish general models of scatternet topologies. Then we review the state-of-the-art approaches with respect to Bluetooth scatternet formation and compare and contrast them.     

网络系统安全脆弱性分析技术研究

计算机网络系统安全问题日益突出,其根本原因在于网络系统存在安全脆弱点,因此在网络系统安全脆弱性被利用之前去识别和减少或消除脆弱性是非常关键的。文章研究了主流的网络系统安全脆弱性分析技术及相关工具软件的工作机制,分析了各种脆弱性分析技术的优缺点。     

MANET中基于移动代理拓扑发现的策略及其仿真

在MANET环境下,讨论了基于多个移动代理的拓扑发现方案。方案的核心在于通过链路关联度来反映网络的拓扑状况,以移动代理的历史路径和节点信息新鲜度来决定移动代理的漫游策略,仿真实验表明:该算法能够在较短的时间内达到收敛状态,同时给出了节点和代理的最优比例。     

计算机网络系统安全漏洞的研究

为了从根本上解决计算机网络中的漏洞问题,从漏洞产生的原因出发进行研究,针对其中的一类漏洞提出了解决方案:即通过对客户端系统中的软件进行特殊的扫描加密方法,使攻击者不能绕过其访问控制,从而避免了访问验证错误引起的漏洞。最后,指出从漏洞产生的原因来解决系统安全漏洞问题必将是漏洞研究的发展趋势。