数控系统现场总线通信效率的改进

根据数控系统对现场总线通信的可靠性和效率需求,在分析传统通信机制的实时性和效率问题及其产生根源的基础上,提出一种基于硬件链路层重发机制的高效可靠通信机制,将其应用到数控系统中,消除了层间协议转换和操作系统的中断延迟等开销。实验结果表明,该机制具有较高的实时性和通信效率,能够满足高档数控系统的应用需求。     

基于相似负载的iSCSI透明可靠多播

提出一种针对iSCSI网络计算系统的I/O加速策略——基于相似负载的iSCSI透明可靠多播。通过对I/O请求数据块进行相似负载判定以及对原有iSCSI协议进行扩展,在iSCSI网络计算系统中构建数据传输双路径——iSCSI协议数据包路径和相似负载的多播路径,以提高网络计算数据的加载速度。测试结果表明,该策略能有效提升多个客户主机的并发I/O性能。     

Implementing uniform reliable broadcast with binary consensus in systems with fair-lossy links

When implementing multivalued consensus using binary consensus, previous algorithms assume the availability of uniform reliable broadcast, which is not implementable in systems with fair-lossy links. In this paper, we show that with binary consensus we can implement uniform reliable broadcast directly in systems with fair-lossy links, and thus the separate assumption of the availability of uniform reliable broadcast is not necessary. We further prove that, when binary consensus instances are available only as black boxes, any implementation of uniform reliable broadcast in the fair-lossy link model requires the invocation of an infinite number of binary consensus instances even if no process ever broadcasts any messages, and this is true even when multivalued consensus is used.     

基于流媒体的隐蔽通信可靠传输机制的研究

首先分析了原有流媒体隐蔽通信系统模型在传输机制上存在的问题.在此基础上改进了原有的传输方案,提出了一种新的基于流媒体的隐蔽通信的可靠传输机制,并进行实现和实际测试.实验结果表明,对于只有当载体满足一定条件时才可以嵌入的隐藏算法,新的传输机制也能保证可靠传输,性能较以前的方法也有长足的改善.     

无线传感器网络中能量均衡可靠路由度量方法

针对无线传感器网络的资源限制以及对传输可靠性的特殊要求,提出一种能量均衡路由度量方法EBETX。以ETX值作为路由度量的同时,兼顾网络中节点能量消耗情况,保证网络各节点能量均衡消耗,延长网络的生存时间,实现高效路由与能量均衡的有效权衡。通过NS2仿真实验验证了该方法的可行性。     

发布／订阅范型中信息可靠投递的研究

以发布／订阅范型在时间维度上解耦导致的不确定性为出发点,采用时序分析方法,研究范型中信息投递的可靠性保障。在定义投递信息可用性的基础上,给出保证信息向订阅者可靠投递系统应满足的基本计算条件,探讨底层通信设施对可靠性的影响。针对发布／订阅范型中信息可靠投递的问题,提出必要的计算条件。分析结果表明,信息的可靠投递与订阅活跃期、订阅延迟、发布传播延迟密切相关。     

A new approach to robust reliable H∞ control for uncertain nonlinear systems

This paper focuses on the optimal robust reliable H_∞ control for a class of uncertain nonlinear systems with actuator faults. A new method of annihilating uncertain matrix is proposed. Based on this approach, a new method of disposing of the phenomenon of uncertain matrices multiplication is provided. In accordance with the method, the optimal robust reliable H_∞ control problem for uncertain nonlinear systems is settled by employing state feedback, in terms of linear matrix inequality (LMI). Finally, two illustrative examples are given to show the feasibility and validity of the proposed method.     

A Simultaneous Mixed LQR/H∞ Control Approach to the Design of Reliable Active Suspension Controllers

This paper is concerned with the synthesis of reliable controllers for quarter‐car active suspension systems. By a simultaneous mixed LQR/H_∞ control approach, a static output feedback controller is derived for guaranteeing good suspension performance under possible sensor fault or suspension component breakdown. The considered simultaneous mixed LQR/H_∞ control problem is a nonconvex optimization problem; therefore, the linear matrix inequality approach is not applicable. Based on the barrier method, we solve an auxiliary minimization problem to get an approximate solution for the simultaneous mixed LQR/H_∞ control problem. Necessary conditions for the local optimum of the auxiliary minimization problem are derived. Moreover, a three‐stage solution algorithm is developed for solving the auxiliary minimization problem. The simulation shows that the obtained static output feedback suspension controllers can improve suspension performance in nominal mode and all considered failure modes.     

MANET 中基于链路稳定性路由的跨层传输控制协议

在MANET中,通信节点的移动会造成端到端通信路由的时常中断.传统TCP协议只有拥塞控制机制,对由于节点移动造成的数据包传输丢失和超时也作为拥塞处理,使得端到端传输性能低下.为解决这一问题,采用跨层设计思想,将传输控制与链路稳定性路由结合,提出了一种基于链路生存时间概率的传输控制协议(transmissioncontrol protocol based on probability of link residual lifetime,简称TCP-PLRT).该协议通过在路由稳定时跨层收集路由层链路生存时间概率信息来实现对端到端连接稳定性的认知,并针对路由不稳定、路由中断、路由恢复,分别制定了路由切换、数据存储转发、ACK再确认三大机制.这使得TCP-PLRT协议具有对由移动造成的路由中断进行提前预判和有效处理的能力.仿真结果表明,TCP-PLRT协议能够极大地减小由节点移动带来的端到端传输性能的下降,减少分组重传,提高端到端的吞吐量.     

异质环境中可靠组播的代理结构

文章提出了一种适于异质网络环境的可靠组播代理结构。这种代理结构将网络环境相异的可靠组播会话分解成若干个网络环境相似的子会话,从而缓解了异质网络环境的异构问题。不仅如此,通过在可靠组播代理中引入应用程序的语义,实现了语义可靠性,即应用程序能够根据语义控制它所需要的数据可靠性。