探析网络安全防范体系及设计原理

随着互连网的高速发展,网络技术已经融入到人们生产、生活中的各个领域,但网络安全问题也越来越严重.本文针对网络安全防范的概念、互联网可能存在的风险、以及设计原理进行了一些探析.     

巧用Word替换命令

随着计算机技术迅猛发展并在各个领域应用得到相应推广,Office是目前最流行,Word在字处理方面应用基本上有90%占有率.文字处理方面,对Word简单输入排版,如替换命令,只是用它来查找和替换文字,对其更深层次应用如:替换字符格式、段落标记、分页符等方面还不了解.现谈谈Word中替换命令几点妙用.     

压差矢量水听器阵波束形成的优化

以各向同性噪声作为背景噪声场,对矢量水听器阵波束形成的优化方法进行了系统的研究.在分析各向同性噪声场中声压、振速相关性的基础上,利用最大信噪比准则推导了基阵的最佳增益与噪声场特性和阵列流形之间的关系,提出利用最佳增益权对阵列接收信号进行波束形成处理.通过对矢量水听器阵进行分解,将最佳增益波束形成引入矢量阵信号处理中.以二维压差矢量水听器阵作为接收基阵进行了仿真计算和湖上试验,结果表明,矢量阵的最佳增益波束形成可以获得性能更优的波束和更大的空间处理增益.     

An improved physically-based method for geometric restoration of distorted document images

In document digitization through camera-based systems, simple imaging setups often produce geometric distortions in the resultant 2D images because of the non-planar geometric shapes of certain documents such as thick bound books, rolled, folded or crumpled materials, etc. Previous works have demonstrated that arbitrary warped documents can be successfully restored by flattening a 3D scan of the document. These approaches use physically-based or relaxation-based techniques in their flattening process. While this has been demonstrated to be effective in rectifying the image content and improving OCR, these previous approaches have several limitations in terms of speed and stability. In this paper, we propose a distance-based penalty metric to replace the mass-spring model and introduce additional bending resistance and drag forces to improve the efficiency of the existing approaches. The use of Verlet integration and special plane collision handling schemes also help to achieve better stability without sacrificing efficiency. Experiments on various document images captured from books, brochures and historical documents with arbitrary warpings have demonstrated large improvements over the existing approaches in terms of stability and efficiency.     

Improvements of nonlinear dynamic modeling of hot-film MAF sensor

The operating procedure of engine requires that the mass air flow (MAF) sensor can measure the pulsation air flow accurately. Therefore the MAF sensor must possess fast response speed. It is necessary to study the dynamic characteristic of the MAF sensor. Both the experimental equipments and method used by authors previously are improved to obtain the sensor response data accurately in this paper. The static and dynamic separable modeling method is adopted to build the uniform nonlinear dynamic model of the hot-film MAF sensor in the Hammerstein and Wiener forms, which can describe the large/small flow-rate and positive/negative step responses. The performance indexes are calculated by the actual and model responses.     

球形全景图像的自动拼接

近年来,球形全景的虚拟现实方法开始发展起来.在已有的球形全景图像拼接方法中,基本上都是"半自动"的拼接方法,需要很多人工操作,效率低下、成本高昂.提出一种球面自寻匹配的拼接算法.该算法通过把多幅图像映射到一个合适的球面上,自动调整每幅图像的插入点,使得重合位置的差值图像灰度累积平均值最小,然后球面的图像反映射成平面形式,最终得到拼合图像.该算法可使程序实现完全自动化,使人工操作降至最低,从而降低全景图像的制作成本.     

NAND Flash的驱动程序设计

以三星公司K9F2808UOB为例,设计了NAND Flash与S3C2410的接口电路,介绍了NAND Flash在ARM嵌入式系统中的设计与实现方法,并在U-Boot上进行了验证。所设计的驱动易于移植,可简化嵌入式系统开发。     

Learning Image-Text Associations

Web information fusion can be defined as the problem of collating and tracking information related to specific topics on the World Wide Web. Whereas most existing work on Web information fusion has focused on text-based multidocument summarization, this paper concerns the topic of image and text association, a cornerstone of cross-media Web information fusion. Specifically, we present two learning methods for discovering the underlying associations between images and texts based on small training data sets. The first method based on vague transformation measures the information similarity between the visual features and the textual features through a set of predefined domain-specific information categories. Another method uses a neural network to learn direct mapping between the visual and textual features by automatically and incrementally summarizing the associated features into a set of information templates. Despite their distinct approaches, our experimental results on a terrorist domain document set show that both methods are capable of learning associations between images and texts from a small training data set.     

基于XML中间件的分布式异构数据库的数据分片策略研究

主要研究XML中间件的分布式异构数据库的数据分片策略,以便能够并行处理XML查询。为了描述XML数据分片,提出了对象树、子树的概念,将一棵XML数据树分割成对象树和子树,对象树在各个站点上复制,子树标签化后均匀分片到各个站点上。为了实现用户数据分片查询工作量的均衡,对最大树深的子树采用减治法策略,减治法策略后的子树又分配到一个新的站点上。基于这一思想,提出并实现其算法。实验结果证明：在分布式异构数据库的检索、查询和访问中,基于对象树、子树的数据分片算法的性能要比PSPIB算法性能优越。