RM算法的运行时开销研究与算法改进

RM算法是经典的固定优先级实时调度算法.而在嵌入式实时系统中,系统的工作负荷往往是由很多频率快、执行时间较短的任务组成.因此,直接使用RM算法进行任务调度会由于实时操作系统中任务的上下文切换开销而导致嵌入式系统资源利用率的降低.分析了基于RM算法调度的任务之间的抢占关系,并建立了以任务属性为参数的上下文切换开销模型.在该模型的基础上,通过优化任务的释放时间来降低RM算法导致的系统运行时任务切换开销.最后的实验结果验证了该策略的有效性.     

基于分布式入侵检测的负载平衡调度算法

分布式入侵检测的工作由系统中的多台计算机来进行分担可以极大地提高系统的可靠性,但在各个网络节点之间的负载不平衡问题制约了其工作效率的充分发挥.文中提出了一种使网络间平衡负载的调度算法,该算法把入侵检测系统的规则当作线程,通过本地调度和在网络中通信使得负载在网络间平衡分布.     

QoS‐Guaranteed Multiuser Scheduling in MIMO Broadcast Channels

This paper proposes a new multiuser scheduling algorithm that can simultaneously support a variety of different quality‐of‐service (QoS) user groups while satisfying fairness among users in the same QoS group in MIMO broadcast channels. Toward this goal, the proposed algorithm consists of two parts: a QoS‐aware fair (QF) scheduling within a QoS group and an antenna trade‐off scheme between different QoS groups. The proposed QF scheduling algorithm finds a user set from a certain QoS group which can satisfy the fairness among users in terms of throughput or delay. The antenna trade‐off scheme can minimize the QoS violations of a higher priority user group by trading off the number of transmit antennas allocated to different QoS groups. Numerical results demonstrate that the proposed QF scheduling method satisfies different types of fairness among users and can adjust the degree of fairness among them. The antenna trade‐off scheme combined with QF scheduling can improve the probability of QoS‐guaranteed transmission when supporting different QoS groups.     

基于改进人工鱼群-蛙跳算法优化LSSVM参数短期负荷预测

短期电力负荷预测在电力系统安全调度、经济运行方面起到关键作用。在用最小二乘支持向量机进行负荷预测时,参数选择将直接影响预测精度。为了提高LSSVM负荷预测精度,文中提出一种基于Levy变异自适应视野人工鱼群-蛙跳算法对LSSVM进行参数优化的方法。以某县负荷、天气等历史数据对LSSVM进行训练,建立LAVAFSA-SFLA-LSSVM、AFSA-LSSVM、LAFSA-SFLA-LSSVM共3种预测模型,对该地区某日24 h的电力负荷进行预测。算例结果表明,LAVAFSA-SFLA-LSSVM预测精度比AFSA-LSSVM和LAFSA-SFLA-LSSVM更高,预测误差更小。     

Scheduling sensor activity for information coverage of discrete targets in sensor networks

In this paper, we study the problem of scheduling sensor activity to cover a set of targets with known locations such that all targets can be monitored all the time and the network can operate as long as possible. A solution to this scheduling problem is to partition all sensors into some sensor covers such that each cover can monitor all targets and the covers are activated sequentially. In this paper, we propose to provide information coverage instead of the conventional sensing disk coverage for target. The notion of information coverage is based on estimation theory to exploit the collaborative nature of geographically distributed sensors. Due to the use of information coverage, a target that is not within the sensing disk of any single sensor can still be considered to be monitored (information covered) by the cooperation of more than one sensor. This change of the problem settings complicates the solutions compared to that by using a disk coverage model. We first define the target information coverage (TIC) problem and prove its NP‐completeness. We then propose a heuristic to approximately solve our problem. Simulation results show that our heuristic is better than an existing algorithm and is close to the upper bound when only the sensing disk coverage model is used. Furthermore, simulation results also show that the network lifetime can be significantly improved by using the notion of information coverage compared with that by using the conventional definition of sensing disk coverage. Copyright © 2008 John Wiley & Sons, Ltd.     

嵌入式Linux下串口应用开发

串口具有价格便宜、编程方便等优点,在嵌入式系统中有着广泛的应用。Linux是嵌入式系统应用最广的操作系统。针对嵌入式Linux的特点,分析在Linux系统下串口应用开发的方法,介绍了如何制作串口开发所需的Linux内核和根文件系统。通过查询和接收SIGIO（信号驱动I／O）信号两种方式分别实现嵌入式Linux系统与微机系统的串口通信,并总结了串口通信程序主要设计步骤。     

基于FPGA的多通道串行A／D转换器的控制器设计

在低成本、多通道数据采集系统中,串行接口A/D转换器得到了广泛的应用,但是通道的轮换以及串行数据的传输会降低数据采集的速度和CPU的工作效率。以ADS7844为例介绍基于FPGA和VHDL语言的A/D控制器设计方法,并通过计算机时序仿真结果验证了该控制器的正确性。该控制器具有输入通道自动转换、数据并行输出等特点,提高了采集速度和CPU的工作效率。     

Task scheduling mechanisms in cloud computing: A systematic review

Today, cloud computing has developed as one of the important emergent technologies in communication and Internet. It offers on demand, pay per use access to infrastructure, platforms, and applications. Due to the increase in its popularity, the huge number of requests need to be handled in an efficient manner. Task scheduling as one of the challenges in the cloud computing supports the requests for assigning a particular resource so as to perform effectively. In the resource management, task scheduling is performed where there is the dependency between tasks. Many approaches and case studies have been developed for the scheduling of these tasks. Up to now, a systematic literature review (SLR) has not been presented to discover and evaluate the task scheduling approaches in the cloud computing environment. To overcome, this paper presents an SLR‐based analysis on the task scheduling approaches that classify into (a) single cloud environments that evaluate cost‐aware, energy‐aware, multi‐objective, and QoS‐aware approaches in task scheduling; (b) multicloud environment that evaluates cost‐aware, multi‐objective, and QoS‐aware task scheduling; and (c) mobile cloud environment that is energy‐aware and QoS‐aware task scheduling. The analytical discussions are provided to show the advantages and limitations of the existing approaches.     

544智能通讯计算机在电子战和雷达系统中的应用

道德论述了串行通信在电子战和雷达系统中的重要地位,接着以某电子战系统为例详细介绍了其串行通讯的硬件组成和软件,讨论了串行通信和所遇到的干扰问题和采取的抗干扰措施。     

红外图像中人体目标检测技术研究

针对红外序列图像中人体目标检测问题,采用了基于特征点的特征区域提取方法,先用FAST算法快速提取特征点,然后基于提取出的特征点,使用LBP算法提取特征区域,在得到感兴趣的特征区域（ROI区域）后,用对ROI区域进行基于离散小波变换的小波熵特征提取,并采用复合分类方法对ROI区域进行分类,利用此方法有效地将人体目标从红外序列图像中检测出来。