多队列共享内存空间通用算法研究

在分析传统队列的基础上,提出了多个队列共享内存空间的一种通用算法,以提高内存空间利用率。     

基于多代理和多优先队列的短信实时并发算法

针对Modem发送短信在实时性、并发性及完整性等性能上存在的缺陷,提出基于多代理、多优先级队列的短信实时并发算法。该算法采用多代理、多优先级队列、线程池等技术手段保证短信控制的实时性、并发性及数据完整性,在算法中使用优先级,使某些信息能够优先发送。通过改造排队论模型和实验对算法进行验证,并将该算法应用于SMAS系统,系统运行结果表明,该算法大幅提高了其发送和接收短信的速度与效率,实现了短信实时性和并发性的目标,优化了SMAS系统的整体性能。     

一种数字取证完整性方案

设计了一种数字取证的完整性方案,该方案使用SHA算法生成取证信息的摘要值,将摘要值和本地系统时间作为取证信息的验证数据,采用秘密共享机制将验证数据进行秘密分割,从而使方案除了可以完成完整性验证,也具有容错性。     

一种抽象的数字取证模型

介绍了数字取证和数字取证模型的概念,然后通过对基于刑事侦查和基于企业内部网的数字取证异同点的比较,结合数字取证在非数字化犯罪领域应用中的特点,在前人工作的基础上,提出了一种不局限于特定数字取证类型、以取证实施者为中心、使用状态转换图描述的抽象数字取证模型,采用取证循环的形式描述了数字取证的过程和特征。     

一种面向Web服务复合的多agent协同系统设计

本文主要设计了一种新的Internet系统模型,面向Web服务复合的多agent协同系统（CoWEB）.首先,通过阐述＂Web服务复合＂这种新的分布计算应用所具有的特点和需求,提出了使用agent构建CoWEB系统的优势.然后,通过对CoWEB三个功能层的主要结构设计,以及系统所具有特点的分析,表明了该系统能较好地适应Web服务环境.并通过解决Web服务特有的异构、自治和动态性问题,实现了一种可靠的、灵活的Web服务复合.     

网络协同取证计算研究

网络取证面临着复杂多样的网络入侵环境,尤其是对于复合攻击的取证,为此提出了网络协同取证计算新概念.通过对传统的函数依赖关系理论的扩展,提出了以一定概率相依赖的概率函数依赖关系及其分析方法与算法,进而结合贝叶斯网络理论、报警关联分析技术和对K2算法的改进,提出了一种网络协同取证分析算法,算法通过对元报警事件的聚类和综合不同的网络取证数据源,能够直观地再现复杂网络攻击的犯罪场景,有效地实现网络取证分析;而且即使在部分数据缺失情况下,算法也可推理攻击的发生过程.     

一种多微粒群协同进化算法

受自然界共生现象的启发,将微粒群算法和协同进化相结合,提出了一种多微粒群协同进化算法。进化过程中,粒子不仅要与本子群的其他微粒交换信息,还要受其他子群体的影响。通过对三个标准函数优化的实验结果表明,此算法在一定程度上避免了陷入局部极值点并且提高了收敛精度。     

一种基于多物种协同进化的神经网络优化方法

论文在阐明了遗传算法和神经网络结合的必要性之后,分析了一般遗传算法在神经网络结构优化过程中存在的不足,并根据多物种之间相互竞争和相互适应的机理提出了一种基于多物种协同进化的优化方法。该方法既可以有效地避免神经网络结构寻优过程中解搜索空间过大以及进化规则复杂等问题,还可以起到对网络的结构和权值同时进化的作用。仿真实验表明该方法是可行并且有效的。     

混合交通环境车辆队列协同控制

车辆队列在提高驾驶安全性、提升交通流量、改善燃油经济性方面具有巨大潜力,但现有研究多针对完全由智能网联车辆组成的队列,难以适用于现实中的混合交通环境.为此,文章研究了人工驾驶车辆与智能网联车辆的混合队列协同控制方法,在智能网联车辆控制设计中引入后车信息,并分析了其对队列稳定性、跟踪性能、燃油经济性的影响.首先构建了一种...     

PRED:一种配合队列调度的RED算法

论文讨论了队列管理和队列调度的关系,提出了一种新的基于势的RED机制:PRED,以增强SPFQ调度机制的公平性,来达到整个报文处理系统的性能改善。通过严格的仿真验证,同其他的队列管理机制相比,PRED同SPFQ的结合能够最大限度地利用系统资源,提高服务的公平性。     

Reducing run queue contention in shared memory multiprocessors

The performance of parallel processing systems, especially large systems, is sensitive to various types of overhead and contention. Performance consequences may be serious when contention occurs for hardware resources such as memory or the interconnection network. Contention can also occur for software resources such as critical data structures maintained by either system or application software. A run queue is one such critical data structure that can affect overall system performance. There are two basic types of run queues, centralized and distributed. Both present performance problems. There are also several techniques to mitigate their drawbacks, but none is completely satisfactory. Instead, the author proposes a different run queue organization, a hierarchical organization that inherits the best features of the centralized and the distributed queue organizations while avoiding their pitfalls. Thus, the hierarchical organization is suitable for building large-scale multiprocessor systems     

A new memory allocation method for shared memory multiprocessors with large virtual address space

This paper proposes a new memory allocation method for shared memory multiprocessors with large virtual address spaces. An evaluation of its performance is also presented. For effective use of shared memory multiprocessors, it is important that no processor's execution is blocked. If several processors simultaneously access a shared variable, their processes are blocked and access to the variable is serialized. Thus, frequent access to shared variables reduces the parallelism. In particular, the parallelism is significantly reduced when a special shared variable – the ‘allocation pointer’ – is frequently accessed in the dynamic object allocation by an application program. In this paper, we propose a new method for allocating physical memory pages where the allocation pointer is monotonically increased in the virtual address space in contrast to the conventional method. This allows the critical sections for access to the allocation pointer to be executed effectively and atomically by using the fetch-and-add primitive. Our method improves the application program's parallelism by access to the allocation pointer with considerably short blocking time to the process. © 1997 John Wiley & Sons, Ltd.     

Parallel evolutionary algorithms based on shared memory programming approaches

In this work, two parallel techniques based on shared memory programming are presented. These models are specially suitable to be applied over evolutionary algorithms. To study their performance, the algorithm UEGO (Universal Evolutionary Global Optimizer) has been chosen.     

基于QoS的路由器队列管理

新一代互联网必然要满足服务质量(QoS)的要求，本文讨论了新一代互联网路由器输入端缓冲区队列管理和内存管理的一个方案，提出了二级队列的基本结构拥塞控制与门限值的设定方法，使所提方案能够支持多级QoS和动态内存分配。     

Novel parallel method for association rule mining on multi-core shared memory systems

Association rule mining (ARM) is an important task in data mining with many practical applications. Current methods for association rule mining have shown unstable performance for different database types and under-utilize the benefits of multi-core shared memory machines. In this paper, we address these issues by presenting a novel parallel method for finding frequent patterns, the most computational intensive phase of ARM. Our proposed method, named ShaFEM, combines two mining strategies and applies the most appropriate one to each data subset of the database to efficiently adapt to the data characteristics and run fast on both sparse and dense databases. In addition, our newlock-free design minimizes the synchronization needs and maximizes the data independence to enhance the scalability. The new structure lends itself well to dynamic job scheduling resulting in a well-balanced load on the new multi-core shared memory architectures. We have evaluated ShaFEM on 12-core multi-socket servers and found that our method run up to 5.8 times faster and consumes memory up to 7.1 times less than the state-of-the-art parallel method. For some test cases, ShaFEM can save up to 4.9 days of execution time over the compared method.     

基于图像序列期望特征的阈值分割方法*

针对单幅图像自适应阈值分割算法复杂度高、实时性不足的问题,提出了一种基于图像序列期望特征的阈值分割方法。以图像期望背景区域面积特征为例阐述了方法原理和实现流程。通过与传统(Ostu)算法对比,论述了方法在处理具有强一致性特征样本序列时所具有的易调试性、实时性优势。结合列车车厢钩尾螺栓图像特征提取实例进行定量分析,验证了方法的有效性。     

基于S排队的被动队列管理算法

为了解决网络拥塞问题,基于“弃头”方式建立了一种新的被动队列管理算法（DFSQ）。该算法首先利用S排队推导网络队长的数学表达式,并提出丢包概率和丢包策略。同时,通过仿真实验深入研究了影响网络队长的关键因素,并将DFSQ与随机早期检测算法(RED)、“弃尾”算法进行对比分析,结果表明DFSQ算法性能更优。     

基于队列计数的固态存储器热数据识别方法*

目前较常用的热数据识别方法主要关注于数据的访问频繁度,却没有有效地体现出访问次数随时间的变化关系,从而造成了较高的错误识别率。针对这种不足,设计了基于队列计数的热数据识别方法,通过使用先进先出规则淘汰过时的数据,并赋予队列中每个位置所存放元素不同的权值来表示不同时刻各数据的热状态;同时结合Flash读写等特性,引入了热区域概念,使其所需存储空间大大降低。通过理论分析以及实验证明,此方法在热数据识别和均衡效果方面达到了较好的性能,从而提高了垃圾回收的效率以及延长了存储器的使用寿命。     

基于多体动力学的火箭飞行仿真

火箭飞行过程伴随着质量、质心、惯性矩的变化和控制力的调整,其模拟仿真是个非常复杂的学术和技术问题.基于多体动力学软件Adams,建立火箭箭体的三维模型,编制火箭飞行过程仿真的流程控制子程序、重力变化子程序、控制力子程序和气动力函数,搭建火箭的飞行仿真平台,实现火箭飞行过程中的质量、质心变化的仿真,并且给出关键功能的验证和应用算例.     

Synchronised execution on shared memory multiprocessors

Threads provides a mechanism for simulating the execution of parallel algorithms on a simplified model of a shared-memory multiprocessor. The algorithms can be expressed in a high-level block-structured language, which supports multiple threads of execution within a common body of program code. Results show an ability to achieve good speedup for small problems using algorithms derived by simple modifications of sequential algorithms. As well, a sibling thread synchronisation feature provides the basis for the synchronous execution of threads. k-parallel algorithms tailored to the machine size and implemented as synchronously executing iterations, can provide near linear speedup as the problem size is increased. The techniques described in this paper seem to promise an effective synchronous execution mode for shared-memory MIMD architectures.