A novel optical burst switching scheme—logical cascaded private subnet with start wavelength assignment policy

Many recent studies have convincingly demonstrated that network traffic exhibits a noticeable self-similar nature, which has a considerable impact on network performance, and most studies of optical burst switching (OBS) networks are under a fundamental assumption that full wavelength conversion is available throughout the network. In practice, however, economic and technical considerations are likely to dictate a more limited and sparse deployment of wavelength converters in the optical network. Therefore, we present a novel scheme for OBS networks, called logical cascaded private subnet (LCPN) with start wavelength assignment policy. We define the concept of canoe relative to cluster in self-similar traffic, and introduce a new device named payload segregator at the edge node as a gateway to the core node in OBS Networks. According to the changes in the edge node framework, we put forward the concept of cluster private subnet and canoe private subnet in the core node correspondingly. A new start wavelength assignment policy is proposed for the absence of (full) wavelength conversion capabilities in the core node of OBS Networks. The performance study indicates that, our new scheme is robust under self-similar traffic and wavelength continuity constraint.     

A discrete-event model to simulate the effect of truck bunching due to payload variance on cycle time,hauled mine materials and fuel consumption

Data collected from truck payload management systems at various surface mines shows that the payload variance is significant and must be considered in analysing the mine productivity,energy consumption,greenhouse gas emissions and associated cost.Payload variance causes significant differences in gross vehicle weights.Heavily loaded trucks travel slower up ramps than lightly loaded trucks.Faster trucks are slowed by the presence of slower trucks,resulting in‘bunching’,production losses and increasing fuel consumptions.This paper simulates the truck bunching phenomena in large surface mines to improve truck and shovel systems’efficiency and minimise fuel consumption.The study concentrated on completing a practical simulation model based on a discrete event method which is most commonly used in this field of research in other industries.The simulation model has been validated by a dataset collected from a large surface mine in Arizona state,USA.The results have shown that there is a good agreement between the actual and estimated values of investigated parameters.     

基于Snort的IPv6入侵检测技术

针对开源入侵检测系统Snort没有提供对IPv6协议的AH和ESP扩展首部支持的问题,提出利用Snort检测ESP加密报文的解决方案。构造ESP检测规则,在Snort协议分析模块加入DecodeESP()函数并添加密钥管理模块,实现Snort对IPv6报文中ESP扩展报头的解析,管理其产生的密钥。给出一种面向ESP的入侵检测系统模型,以验证IPv6加密通信入侵检测的可行性,并给出实验验证过程。     

无人机载荷图像仿真平台的设计与实现

无人机有效载荷图像仿真平台为无人机操作员训练、地面站建设、以及指挥控制和通信系统提供必要的模拟数据和模拟环境，是研制无人机系统及其测控与通信系统的重要部分。该文讨论了如何基于相对低成本的PC机和图像处理与传输技术构建一个完整的无人机有效载荷图像仿真平台。该平台可以接收无人机及其指挥控制系统的各种状态参数以及控制指令，通过图像处理，模拟实际情况生成有效载荷图像数据，并实时下传，以验证无人机及其指挥控制和通信系统的概念结构和工作过程。     

航天器有效载荷系统的半自主Agent设计

航天器有效载荷系统是航天器的重要组成部分,将人工智能的概念引入航天器有效载荷系统的仿真和建模中,提出使用半自主智能主体(Agent)来建立航天器有效载荷系统.利用半自主Agent的自主性和受制性,航天器有效载荷半自主A-gent既具有相对独立的决策能力,又能够受制于主控系统,在主控系统提出使命级命令之后,能够根据有效载荷的优先等级、资源请求和卫星的资源情况,由搜索机调度智能算法,合理安排各个载荷的工作状态,自主地完成对各个有效载荷的操作控制,并且提高对能源的使用效率.从仿真结果来看,该设计是有效的.     

OpenBSD下基于IPSec协议的VPN研究与设计

IPSec提供一种对用户透明的IP层安全服务，包括机密性、完整性、可认证性和数据重放保护。IPSec可用于保护主机间、安全网关间或安全网关－－主机间的一条或多条路径的安全通信。文章对IPSec的结构与组成，IPSec在OPENBSD下的实现进行了较为详细的研究对；并对系统的利弊进行了评价。     

空间辐射环境仿真平台的设计与实现

为提高航天工程系统或有效载荷电子学设备的可靠性、减小任务风险以及便于方案决策．应对系统和有效载荷的空间辐射环境进行准确预估。采用CBS（COTS-BasedSystem）开发方法，通过领域模型评估选取了商业现货软构件，建立了空间辐射环境仿真平台。利用该平台进行了能谱、总剂量、传能线密度、射程等多种空间辐射环境特征参数和屏蔽策略的仿真分析．结果表明仿真数据可靠；该平台能够满足空间任务分析需求，并为电子学设备的可靠性设计和试验提供重要依据。     

一种平面二自由度并联机器人承载能力分析

以一种可实现末端运动平台平动且具有较小运动惯量的平面二自由度并联机器人机构为研究对象,分析其承载能力性能。与传统的分析和优化设计方法不同,综合考虑机器人机构的几何尺寸和运动变量的变化范围,作为机器人机构的运动学参数,利用空间模型理论,建立了机器人机构的设计空间。在设计空间内计算机器人机构的承载能力性能指标并绘制了相应的承载能力性能图谱,并探讨了机构承载能力性能指标与运动学参数之间的关系。这些图谱为设计者评价该机器人机构的承载能力性能和选择优化的运动学参数提供了帮助。提出的新方法也为以移动副为驱动的平面并联机器人分析与优化设计提供了一种有效的新途径。     

海洋二号卫星微波辐射计的动平衡设计仿真与试验

为了实现卫星的高精度姿态控制,需要对以辐射计为代表的大型回转载荷进行严格的动平衡设计仿真与试验。结合海洋二号卫星研制需求,在产品设计初期开展了针对微波辐射计的动平衡设计仿真,以提供优化产品结构和布局的依据。为了评估空气环境对动平衡配平的影响,进行了辐射计动平衡配平的风阻影响分析。考虑了重力因素、在轨热变形和无重力下轴承径向游隙变化对辐射计动平衡的影响。最终在真空环境下开展了针对辐射计的动平衡试验,以很小的配重质量,实现了微波辐射计的配平。     

监控系统中基于RTP的视频处理

本文主要介绍了监控系统中视频捕捉及传输技术。总结了视频捕获现有的几种方法,重点介绍了传输协议的选取以及MPEG-4流的RTP载荷格式,说明了分片原则及相应的示例图,并对其进行了简化。