基于动态门限的战术数据链MAC协议

战术数据链（TDL）的作用就是在战场上能够更准确、有效和快速地传递战术情报。随着军事信息技术的发展,战场上的节点数量和传输数据呈现快速增长趋势。传统的战术数据链媒介访问控制（MAC）协议为了保证QoS,一般采用固定资源分配的多址访问算法,如TDMA,在面对大容量、高速率的需求时缺乏灵活性和有效性。为此,研究了基于统计优先级多址访问（SPMA）算法,提出了直接映射和差分趋势两种动态门限方法。仿真结果表明,动态门限比固定门限能够有效提高系统效率,更接近目标信道忙闲比设计,并且在相同负载下网络吞吐量也较固定门限高。     

Influence of lubricants on the performance of journal bearings – a review

ABSTRACT

The lubricant properties have a significant influence on the static and dynamic performance characteristics of journal bearing such as load-carrying capability, minimum fluid film thickness, maximum pressure, lubricant flow rate, damping coefficients, stiffness coefficients, etc. The present document reviews the behaviour of various lubricants such as power-law lubricants, couple stress lubricants, micropolar lubricants, ionic liquid lubricants and space lubricants. The influence of these lubricants on the performance of hydrostatic, hydrodynamic and hybrid journal bearings is discussed. An effort is made to develop the understanding to choose the suitable lubricant for journal bearings for different journal bearing configurations. Journal bearings operated with non-Newtonian lubricants have shown better performance compared to Newtonian lubricants. Ionic liquid lubricants have shown high potential in vacuum applications and extreme temperature environment such as in bearings of spacecraft moving mechanical assemblies.     

分簇无线传感器网络动态时隙分配MAC协议

为降低大规模无线传感器网络的平均能耗,提出了一种基于动态分配的调度型无线传感器网络MAC协议（SDC-MAC）。该协议簇间使用FDMA方式分配无线信道,簇内通过TDMA方式给各个节点分配可变长的时隙。随着簇结构的变化,簇头通过时隙分配通知,对簇内节点的时隙分配进行动态调整,簇成员节点则根据控制信息进行休眠和唤醒。仿真结果显示,该算法有效地降低了网络的平均能耗,当网络流量高时还可降低平均数据包时延。     

A framework for post-disaster communication using wireless ad hoc networks

Disaster management system requires timely delivery of large volumes of accurate messages so that an appropriate decision can be made to minimize the severity. When a disaster strikes, most of the infrastructure for communication gets uprooted. As a result, communication gets hampered. A well designed Internet of things (IoT) can play a significant role in the post-disaster scenario to minimize the losses, and save the precious lives of animals and human beings. In this paper, we have proposed a framework for post-disaster communication using wireless ad hoc networks. The framework includes: (i) a multi-channel MAC protocol to improve the network throughput, (ii) an energy aware multi-path routing to overcome the higher energy depletion rate at nodes associated with single shortest path routing, and (iii) a distributed topology aware scheme to minimize the transmission power. Above proposals, taken together intend to increase the network throughput, reduce the end-to-end delay, and enhance the network lifetime of an ad hoc network deployed for disaster response. A multi-channel MAC protocol permits the transmission from hidden and exposed nodes without interfering with the on-going transmission. We have compared the proposed framework with an existing scheme called Distressnet [1]. Simulation results show that the proposed framework achieves higher throughput, lower end-to-end delay, and an increased network longevity.     

针对SIP的ALG解决方案及实现

SIP是一个很有潜力的基于文本的应用层协议。由于SIP协议本身不能保证SIP信令能安全地穿过NAT和防火墙，从而限制了其在现有广域网上的使用和发展，文中归纳了对该问题的解决方案，重点介绍了ALG的解决方案，并根据SIP的特点提出了SIP ALG的具体实现框架。     

IPv6下动态主机配置协议的研究与设计实现

IPv6下的动态主机配置协议DHCPv6还在研究和制订中，参考相关草案和协议，设计并实现了一套基于客户／服务器的DHCPv6系统，应用于IPv6试验网，并对其中的安全问题作了一些探讨和实践。     

IPv4和IPv6的地址管理及过渡时期的地址共存

论文首先介绍了IPv4地址所面临的问题和现有的一些解决方案,然后介绍了IPv6在地址管理方面所做的工作,随后探讨了在IPv6网络过渡时期IPv4地址和IPv6地址共存的一些问题,最后针对这些问题为IPv6网络的部署提出了一些建议。     

基于ElGamal算法的网络密钥技术

通信链路的脆弱性使计算机网络系统受到严重威胁,采用ElGamal算法的数据加密和数字签名,并设计一个链路加密设备和MAC验证技术,以确保传输信息的私密性,其安全性依赖于计算有限域上离散对数这一难题。本文的加密实现方法类似于Elgamal数字签名的动态密钥系统,并给予改进。     

基于Paradigm IDE开发PC104嵌入式系统的RAM配置方法

描述了ParadigmC++IDE嵌入式系统开发工具的功能和应用范围,并介绍了PC104嵌入式计算机系统的性能和特点,重点说明了在Paradigm环境下开发基于PC104的应用系统的存储空间的设置和实现方法。     

混合有状态和无状态地址自动配置的快速切换

移动IPv6允许移动节点在移动过程中保持与通信节点的正常通信，而无须改变其固有地址。但是，移动节点在切换过程中的时延不能够满足对服务质量要求比较高的应用程序，如VoIP等。如何提高移动节点的切换效率成为移动IPv6应用的关键。文中介绍了IPv6有状态和无状态地址自动配置机制、移动IPv6的切换过程，分析了移动IPv6切换的时延问题。提出了混合有状态和无状态地址自动配置机制的快速切换，并详细说明了其原理。混合机制相比移动IPv6中单独使用无状态地址自动配置机制能够明显降低地址重建的时延，提高移动IPv6的切换性能。