一种基于访问图优化的缓存替换算法

针对目前数据库缓存替换算法替换策略单一,无法预测即将执行SQL语句的不足,提出了一种基于访问图优先的缓存替换算法CG-ABR(Call Graph Optimizing Adaptive Buffer Replacement).该算法通过查询优化器获得当前数据访问类型,自动调整缓存替换算法以适应实时变化的访问类型,改进了缓存访问的管理方法,并根据SQL语句的应用逻辑执行顺序来构造访问图Call Graph,基于Call Graph以预测将要执行的SQL语句,替换出未来不会被访问的页面缓存,以达到缓存空间优化的目的.实验结果与分析表明,CG-ABR算法是有效的,对实时变化的访问类型有较好的缓存命中率,具有良好的应用价值.     

基于FPGA的一种新型8通道数据采集系统

以FPGA为核心控制模块,搭载MAX1300为数据采集模块,完成8通道、16位精度数据采集系统。采集数据在FPGA内部储存,DSP在适当时刻对其进行读取以完成伺服控制工作。针对以往数据采集系统的局限,FPGA内部对所采集数据进行预处理,减轻了CPU数据处理强度和负担。详细介绍了各芯片硬件电路设计,给出FPGA内部各功能模块逻辑图。     

Machining activity extraction and energy attributes inheritance method to support intelligent energy estimation of machining process

An energy-efficient intelligent manufacturing system could significantly save energy compared to traditional intelligent manufacturing systems that do not consider energy issues. Intelligent energy estimation of machining processes is the foundation of the energy-efficient intelligent manufacturing system. This paper proposes a method for machining activity extraction and energy attributes inheritance to support the intelligent energy estimation of machining processes. Fifteen machining activities and their energy attributes are defined according to their operating and energy consumption characteristics. Activities and energy attributes are extracted mainly from NC program supplemented with blank dimensional information. An effective extraction method of activities and energy attributes is the basis for the intelligent energy calculating of machining process. Based on an investigation on the extraction procedure of activities and energy attributes, energy attributes inheritance method is further discussed. Four types of energy attribute inheritance rules are summarized according to the different inheritance characteristics. Based on these four types of inheritance rules, the energy attributes can be transmitted from activity to Therblig as effective inputs of Therblig-based energy model of machining processes. The proposed methodology is finally demonstrated through two machining cases.     

基于MVC模式的ITHelp在线服务模块设计与实现

分析了ITHelp在线服务模块的建设需求,对ITHelp进行了功能分解和详细设计。研究了MVC开发模式,提出了基于SSI的ITHelp实现方案。结果表明, ITHelp模块功能完备、实用性强,提高了信息化工作效率,实现了信息在线共享。     

Performance of SOR methods on modern vector and scalar processors

The building-cube method (BCM) is a new generation algorithm for CFD simulations. The basic idea of BCM is to simplify the algorithm in all stages of flow computation to achieve large-scale simulations. Calculation of a pressure field using the Successive Over Relaxation (SOR) method consumes most of the total execution time required for BCM. In this paper, effective implementations on modern vector and scalar processors are investigated. NEC SX-9 and Intel Nehalem-EX are the latest vector and scalar processors. Those processors have much higher peak performances than their previous-generation processors. However, their memory bandwidth improvement cannot catch up with the performance improvement of processors. This is the so-called memory wall problem. In our paper, we discuss optimization techniques for implementation of the SOR method based on architectural characteristics of these modern processors, and evaluate their effects on the sustained performances of these processors for BCM.     

Substructure based approach to finite element model updating

A substructure-based finite element model updating technique is proposed in this paper. A few eigenmodes of the independent substructures and their associated derivative matrices are assembled into a reduced eigenequation to recover the eigensolutions and eigensensitivities of the global structure. Consequently, only the concerned substructures and the reduced eigenequation are re-analyzed in the optimization process, thus reducing the computational load of the traditional model updating methods which perform on the global structure. Applications of the proposed substructure-based model updating to a frame structure and a practical bridge demonstrate that the present method is computationally effective and efficient.     

基于NANDFlash的嵌入式文件系统μC／FS的实现

介绍了基于NANDFlash的嵌入式文件系统的实现,其硬件平台是嵌入式芯片SEP4020与NANDFlash结合的高性能嵌入式存储系统,其软件基础是嵌入式FAT文件系统μC／FS。     

基于因特网的连续媒体交互技术研究

对基于因特网的多媒体会议系统的传输特性、要求和协议标准等进行了系统地研究。通过对因特网上多媒体会议系统的特殊需求和支持多媒体网络协议存在问题的分析,提出了因特网多媒体会议系统的总体设计方案,并在此基础上对连续媒体中音频会议系统的实现进行了试验。     

一种基于神经网络和系统调用的异常入侵检测方法*

提出了一种利用多层BP神经网络建立进程正常运行轮廓的思想,基于1998年DARPA入侵检测系统评估的审计数据源,通过与K近邻分类、带(频率)门限的Stide(TStide)算法的性能比较表明,所提出的算法具有较高的检测率,同时维持了一个较低的误警率。