使用多级交换网络进行高性能路由器设计

拓扑结构和路由算法是影响多级交换网络性能的重要因素．在比较多种多级互连拓扑属性的基础上，提出将3D Torus结构应用于大规模交换网络设计．然后针对3D Torus交换网络中报文路由面临的两个关键问题：多路径负载均衡和报文保序，提出一种基于维序的多路径路由算法DMR(dimension-order—based multi—path routing)．该算法可在保证报文顺序的同时在多条路径上平衡负载，提高交换网络吞吐率．最后通过模拟验证了算法的性能，并与维序路由和随机路由算法进行了比较．模拟结果表明，DMR算法的性能优于维序路由算法，能够达到随机路由算法性能水平，同时具有随机路由算法所不具备的报文保序特性．     

基于演化序搜索的混合贝叶斯网络结构学习方法

贝叶斯网络是一种不确定性知识表示与推理的有效工具，学习其结构是利用这一工具进行推理的基础。现有的贝叶斯网络结构学习算法，在智能教育等应用场景中往往面临着难以权衡有效性与高效性的问题。一方面，评分搜索类方法能搜索到高质量的解，但面临着算法复杂度高的挑战。另一方面，混合类方法效率高，但所找到的解的质量不尽如人意。针对上述问题，提出了一种基于演化序搜索的混合贝叶斯网络结构学习方法(EvOS)。该方法首先通过约束类算法构建无向图骨架，然后利用演化算法搜索最优节点序，最后使用该节点序指导贪婪搜索得到贝叶斯网络结构。基于常用基准数据集以及教育知识结构发现任务，验证了所提方法的有效性与高效性。实验结果表明，所提方法相较于评分搜索类方法，能够在保持相仿精度的情况下最高加速百倍，且有效性显著高于混合类方法。     

具有社区结构的无标度网络生成算法

近年来,生成图模型在复杂网络研究中的作用越来越重要。图的生成过程对于研究疾病的蔓延和信息的传播具有重大意义,同时图模型的生成也有助于更深入地研究复杂网络的特性。为了能够生成既符合真实网络特征又具有结构多样性的复杂网络,提出了一种具有社区结构的可调节聚集系数和模块性的无标度网络生成算法——TCMSN(Scale Free Network with Tunable Clustering Coefficient and Modularity)。通过调节混合参数可以调节生成网络的模块性,通过调节社区内连边的概率和混合参数可以对网络聚集系数进行调节。TCMSN采用了合理的连边策略,在不破坏网络结构多样性的情况下,能尽可能维持网络的无标度特性。人工构造数据和真实网络数据的对比实验结果表明,TCMSN算法能够生成可调节聚集系数和模块性的无标度网络模型,且能够生成最接近真实网络社区结构特征的网络模型。     

基于视觉的错序在架图书检测系统

在架图书整理是图书馆的一项常见工作,迫切需要提高自动化水平。本文以尽可能不增加额外投资和设施改造为前提,提出了依靠移动设备获取图像,通过视觉技术构建软件系统以实现对错序图书的自动识别的方法。该方法由移动设备采集在架图书图像,利用LSD算法检测书脊边缘并分割图书图像,进而得到索书号区域,并通过投影分离出索书号区域中的字符。采用前馈连续双卷积CNN网络结构模型并综合使用了Dropout、Re LU激活函数和Softmax回归等技术完成对字符的识别。最后,将组合后的索书号与数据库预存信息进行比较,得到图书的正确排列信息。对系统的实际测试和分析表明,本文的方法可以针对一般索书号在架图书进行较好的错序检测,能为图书的自动化整理提供一种可行的方案。     

基于精密时间协议的时钟同步技术

IEEE 1588协议的精密时间协议提供了一种网络控制系统中主从时钟交换报文达到时钟精准同步的有效方法。基于精密时间协议，在网络驱动中对时戳进行采集和处理，采用最佳主时钟算法选取网络主时钟对从时钟进行同步，使用Java语言和C语言混合编程实现软件网络时钟同步，并采用Allan方差公式对时钟性能进行描述。     

基于混合算法的图书馆个性化推荐系统

随着图书馆藏书数量的逐年增加，对于读者而言，从大量符合基本条件的图书中找出完全满足自己要求的已经越来越难了，特别是在这种检索只是基于标题或者作者等简单关键词的前提下。基于此，文章提出了一个基于混合算法的图书个性化推荐系统。首先研究了协同过滤和基于内容的推荐算法在图书推荐中的应用，包括用户分类及相似度的计算、建立条目评分矩以及构建向量空间模型。并针对高校图书和读者的特点，改进了用户条目评分矩阵，采用聚类方法来缓解数据稀疏性问题，利用混合算法对安庆师范大学图书馆的藏书数据集进行对比实验。结果表明，与传统方法相比，混合方法能提供更准确的建议。最后，利用Hadoop的Spark大数据平台实现个性化图书推荐系统架构设计。     

概率图模型推理方法的研究进展

近年来概率图模型已成为不确定性推理的研究热点,在人工智能、机器学习与计算机视觉等领域有广阔的应用前景.根据网络结构与查询问题类型的不同,系统地综述了概率图模型的推理算法.首先讨论了贝叶斯网络与马尔可夫网络中解决概率查询问题的精确推理算法与近似推理算法,其中主要介绍精确推理中的VE算法、递归约束算法和团树算法,以及近似推理中的变分近似推理和抽样近似推理算法,并给出了解决MAP查询问题的常用推理算法;然后分别针对混合网络的连续与混合情况阐述其推理算法,并分析了暂态网络的精确推理、近似推理以及混合情况下的推理;最后指出了概率图模型推理方法未来的研究方向.     

一种适用于移动对等网络的分簇算法

通过分簇算法减小网络振动效应,延长网络的寿命是移动对等网络的研究重点之一。在研究Kautz图及其特性的基础上,提出一种基于Kautz图的移动对等网络分簇算法。在算法中,定义地址空间树,使用Kautz串作为节点标识,并运用后根序和宽度优先算法遍历地址空间树等一系列技术生成簇。同时设计了相关机制管理和维护簇结构,保证结构一致性。理论证明和实验评估表明,该分簇算法能有效减小振动效应,延长网络寿命。     

基于软件总线的星载系统软件结构的研究与设计

针对目前国内外星载系统软件可重构性较差的问题,提出了一种基于软件总线的星载系统软件结构。首先，介绍了软件总线和软构件的结构。其次，阐述了星载实时多任务操作系统中混合任务调度算法的设计。最后，对这个混合任务调度算法的正确性给出了证明。     

传感器网络中基于区间小波变换的混合熵数据压缩算法

考虑传感器网络的数据特性及小波变换在流数据压缩方面的良好性能，提出了一种基于区间小波变换的混合熵数据压缩方法。理论分析和仿真结果表明，结合传统的DC(Data Centric)算法-DD (Directed Diffusion)路由算法，新算法能对传感器网络中的数据流进行有效压缩，可更大程度地降低DD路由算法下节点数据传输的能耗，从而可进一步延长整个网络的生命周期。     

A Sad SAC Story about the State of the Practice

What's the state of the practice of software engineering? If you look at current software engineering books, journals, and conferences, you won't find much of an answer.     

VB+SQL图书信息功能设计研究

VB(Visual Basic)是可以制作界面的软件开发工具,它拥有图形用户界面,并且使用很方便。SQL(SQL Server)是微软生产的用于数据管理和数据分析的软件产品,在Client/Server、Browser/Server的体系结构中都可以作为后台数据使用。图书信息功能是图书管理系统中的一个功能模块。文章详细介绍了VB+SQL图书信息功能模块的设计原理和具体的操作步骤,包括登录界面、图书信息输入、图书信息修改、图书信息删除和图书信息查询这五个具体功能点,并在此基础上对VB+SQL类开发实践进行了总结。     

珍贵书籍智能检索管理系统

为了实现珍贵图书的智能检索与管理,提出了一个基于无线射频识别技术(RFID)的解决方案。无线识别技术是通过非接触的方式,有效得读取标签相关信息的一个技术。其拥有体积小,识别距离远,安全性高,信息量大等特点。本文针对智能图书检索管理,设计了RFID读写器,能够高效读取图书中所贴标签的信息,并且能够快速检索计算机内相关数据的信息。同时,在此给出了射频识别系统读写器的软硬件设计与流程以及计算机中界面设计与数据库之间的程序设计流程。     

Software metrics: good, bad and missing

The software industry is an embarrassment when it comes to measurement and metrics. Many software managers and practitioners, including tenured academics in software engineering and computer science, seem to know little or nothing about these topics. Many of the measurements found in the software literature are not used with enough precision to replicate the author's findings-a canon of scientific writing in other fields. Several of the most widely used software metrics have been proved unworkable, yet they continue to show up in books, encyclopedias, and refereed journals. So long as these invalid metrics are used carelessly, there can be no true software engineering, only a kind of amateurish craft that uses rough approximations instead of precise measurement. The paper considers three significant and widely used software metrics that are invalid under various conditions: lines of code or LOC metrics, software science or Halstead metrics, and the cost-per-defect metric. Fortunately, two metrics that actually generate useful information-complexity metrics and function-point metrics-are growing in use and importance     

A parameterized multilevel pattern matching architecture on FPGAs for network intrusion detection and prevention

Pattern matching is one of the most performance-critical components for the content inspection based applications of network security, such as network intrusion detection and prevention. To keep up with the increasing speed network, this component needs to be accelerated by well designed custom coprocessor. This paper presents a parameterized multilevel pattern matching architecture (MPM) which is used on FPGAs. To achieve less chip area, the architecture is designed based on the idea of selected character decoding (SCD) and multilevel method which are analyzed in detail. This paper also proposes an MPM generator that can generate RTL-level codes of MPM by giving a pattern set and predefined parameters. With the generator, the efficient MPM architecture can be generated and embedded to a total hardware solution. The third contribution is a mathematical model and formula to estimate the chip area for each MPM before it is generated, which is useful for choosing the proper type of FPGAs. One example MPM architecture is implemented by giving 1785 patterns of Snort on Xilinx Virtex 2 Pro FPGA. The results show that this MPM can achieve 4.3 Gbps throughput with 5 stages of pipelines and 0.22 slices per character, about one half chip area of the most area-efficient architecture in literature. Other results are given to show that MPM is also efficient for general random pattern sets. The performance of MPM can be scalable near linearly, potential for more than 100 Gbps throughput. Supported by the National Natural Science Foundation of China (Grant No. 60803002), and the Excellent Young Scholars Research Fund of Beijing Institute of Technology     

特征加权最小最大概率机

在最小最大概率机中引入Boosting权值确定方法,构造特征加权最小最大概率机(FWMPM)。利用Boosting方法计算各个特征对分类任务的重要度,把此特征重要度作为原始数据各个特征的权重,对核函数中的内积和欧氏距离进行加权计算,从而可以减轻最小最大概率机被一些弱相关的特征影响。实验结果和理论分析表明,该方法比标准最小最大概率机具有更好的分类性能。     

冲击爆炸问题的三维物质点法数值仿真

基于物质点法（Material Point Method,MPM）模拟超高速碰撞和爆炸问题时呈现的特点,概述对MPM及其应用的扩展,包括：将MPM扩展应用于超高速碰撞问题,物质点有限元法（MaterialPoint Finite Element Method,MPFEM）,杂交MPFEM,MPM质点自适应法,基于局部多重背景网格的接触算法和并行MPM算法.在此基础上开发针对冲击爆炸问题的三维显式并行MPM数值仿真软件MPM3D.MPM3D采用C＋＋语言开发,并基于Qt和VTK开发图形用户界面PeneBlast,可在Windows,Linux和Mac OS等多种平台上运行.关于超高速碰撞、侵彻、爆炸、边坡失效和金属切削等问题的大量实例表明MPM3D的可靠性和准确性.MPM3D可作为航天器空间碎片防护、常规武器研发与防护等的有效设计工具.     

利用SQL语言实现馆藏书目清单的导出与排序

图书清查工作是图书馆保证数据库中图书信息与书架上实际图书一致的有效手段之一,而其中重要的一个环节就是从数据库中导出馆藏书目清单,馆藏书目清单的优劣直接影响着图书清查工作的效率与进度。利用SQL中的多表查询及自定义存储过程从数据库中导出了馆藏书目清单,并实现馆藏书目清单中的图书顺序与图书排架次序严格一致,从而方便了图书清查工作。     

Interactions with talking books: phonological awareness affects boys' use of talking books

Abstract Framed by current concerns about boys' attainment in literacy, this paper investigates the potential of talking books software to support the literacy development of male beginning readers. The study primarily considered whether typically developing boys who showed lower levels of attainment in phonological awareness would show a greater degree of improvement in phonological awareness or a change in reading strategy, following a talking books intervention, than boys who were demonstrating higher levels of phonological awareness. It also examined whether the boys' phonological awareness attainment would affect how they used the software to support their attempts at reading, both in terms of their interactions with the computer and the types of speech feedback that they selected. The analysis also considered whether there was any association between the nature of the boys' teaching and learning interactions with the computer and any changes in their reading strategies from pre- to post-test. The findings suggest that the use of the talking books software was particularly beneficial for boys who initially showed lower phonological proficiency, and that the boys in this study utilised the talking books software adaptively depending on their phonological proficiency. Moreover, there was evidence that contact with the talking books affected the reading strategies of the boys who had higher phonological awareness. There was also evidence of an association between the way in which the boys interacted with the software and changes in their reading strategy between pre- and post-test.     

Coupling of finite element method with material point method by local multi-mesh contact method

As a Lagrangian particle method, the material point method (MPM) has the potential to model extreme deformation of materials, where the traditional finite element method (FEM) often encounters mesh distortion and element entanglement which lead to numerical difficulties. However, FEM is more accurate and efficient than MPM for problems with small deformation. It is therefore desirable to model the body with extreme deformation by MPM and the body with small deformation by FEM, respectively. In this paper, a method to handle the contact interaction between the MPM body and the FEM body is proposed, which is implemented on the background grid of MPM. By this method, FEM is coupled with MPM and a hexahedral element is incorporated into our 3D explicit MPM code MPM3D®. Several numerical examples, including plate impact, sphere rolling, perforation of thick plate, and fluid–structure interaction problems, are studied and the numerical results are in good agreement with analytical solution and results available in the literature. The coupling of FEM and MPM offers advantages of both FEM and MPM.