Hadamard transform based fast codeword search algorithm for high-dimensional VQ encoding

An efficient nearest neighbor codeword search algorithm for vector quantization based on the Hadamard transform is presented in this paper. Four elimination criteria are derived from two important inequalities based on three characteristic values in the Hadamard transform domain. Before the encoding process, the Hadamard transform is performed on all the codewords in the codebook and then the transformed codewords are sorted in the ascending order of their first elements. During the encoding process, firstly the Hadamard transform is applied to the input vector and its characteristic values are calculated; secondly, the codeword search is initialized with the codeword whose Hadamard-transformed first element is nearest to that of the input vector; and finally the closest codeword is found by an up-and-down search procedure using the four elimination criteria. Experimental results demonstrate that the proposed algorithm is much more efficient than the most existing nearest neighbor codeword search algorithms in the case of problems of high dimensionality.     

A hyperplane based indexing technique for high-dimensional data

In this paper, we propose a novel hyperplane based indexing method to support efficient processing of similarity search queries in high-dimensional spaces. The main idea of the proposed index is to improve data partitioning efficiency in a high-dimensional space by using a hyperplane, which further partitions a subspace and can also take advantage of the twin node concept used in the key dimension based index. Compared with the key dimension concept, the hyperplane is more effective in data filtering. High space utilization is achieved by dynamically performing data reallocation between twin nodes. In addition, a post processing step is used after index building to ensure effective filtration. Extensive experiments based on two types of real data sets are conducted and the results illustrate a significantly improved filtering efficiency. Because of the feature of hyperplane, the proposed indexing method is only suitable to Euclidean spaces.     

基于混合遗传算法的多播路由多目标优化

互联网不断增长的多媒体应用引发人们研究如何满足这些应用的服务质量(QoS)约束.目前网络中多主机之间的多播通信一般需要严格的多个QoS保证,文中描述了一种适应于研究多播QoS路由多目标优化的网络模型,在此基础上提出了基于遗传算法和禁忌搜索混合策略的,具有多目标的多播路由QoS优化方法,以克服遗传算法的爬山能力差以及不成熟收敛等问题.此外还采用了改进的多播树编码方法及高效的遗传操作,同时还优化时延、丢包率和带宽利用率等不同的参数.实验结果表明,该算法为多播路由QoS多目标优化问题的求解提供了一种有效的新途径.     

汉语分词词典设计

汉语分词词典是中文信息处理系统的重要基础,词典算法设计的优劣直接关系着分词的速度和效率。论文采用动态TRIE索引树的词典机制,设计并实现了汉语分词词典,有效地减少了词典空间。实验结果表明该词典具有较高的查询性能。     

互信息医学图像配准研究与局部极值的克服

研究了基于互信息的三维医学图像配准，并克服了的局部极值问题。改进了互信息和归一化互信息的公式，减小了计算量：对Powell算法的方向替换策略进行矫正，最大限度地保持原搜索方向；采用预谩旋转量的方法有效解决了插值赝像局部极值问题。采用背景阚值策略，减小了互信息的计算区域，应用形态学方法，去除了PET图像的背景伪迹，使用了多分辨率策略，有效地提高了配准的速度。实验表明，用谊改进的算法进行三雏医学图像配准可以达到亚像素精度，且在速度上有了明显的提高。     

XPath中的文本查询研究

介绍了一种能够统一地索引全文数据与XML树型结构数据的模型——互关联后继树，提出了后继模式树的概念，使用后继模式树有效地处理了XPath中的正则查询问题。在后继模式树的基础上提出了XPath中节点与文本的联合查询方法。结果表明该方法能够有效地提高XPath中节点与文本联合查询的效率。     

基于内容的电影动画素材检索

传统的电影动画素材检索，通常采用基于索引的方法。素材库中的动画素材数量巨大，采用这种方法会造成人力和时间的浪费，达不到满意的效果。MPEG-7标准是多媒体内容描述的接口，该文将MPEG-7标准运用到电影动画素材的检索中，缩短了制作周期，提高了工作效率。     

Composite Distance Transformation for Indexing and k-Nearest-Neighbor Searching in High-Dimensional Spaces

Due to the famous dimensionality curse problem, search in a high-dimensional space is considered as a ＂hard＂ problem. In this paper, a novel composite distance transformation method, which is called CDT, is proposed to support a fast κ-nearest-neighbor （κ-NN） search in high-dimensional spaces. In CDT, all （n） data points are first grouped into some clusters by a κ-Means clustering algorithm. Then a composite distance key of each data point is computed. Finally, these index keys of such n data points are inserted by a partition-based B^＋-tree. Thus, given a query point, its κ-NN search in high-dimensional spaces is transformed into the search in the single dimensional space with the aid of CDT index. Extensive performance studies are conducted to evaluate the effectiveness and efficiency of the proposed scheme. Our results show that this method outperforms the state-of-the-art high-dimensional search techniques, such as the X-Tree, VA-file, iDistance and NB-Tree.     

基于本体的智能检索系统的研究

由于传统的搜索引擎是基于关键词的检索,检索结果无论是在召回率还是在精确度上都不能令人满意,然而基于本体的智能检索系统是以概念语义为核心来实现信息检索,能改善传统的搜索引擎在语义理解方面的不足。     

热轧带钢轧制批量计划优化模型及算法

基于奖金收集车辆路径问题模型建立了热轧带钢生产批量计划多目标优化模型．模型综合考虑了生产工艺约束、用户合同需求以及综合生产指标优化等因素．利用加权函数法将多目标优化模型转换为单目标优化模型,针对模型特点设计了蚁群优化求解算法,算法中嵌入了单向插入和2-opt局部搜索过程．引用某钢铁企业热轧生产轧制批量计划编制的实际问题对模型和算法进行了验证,结果表明模型和算法的优化效果和时间效率是令人满意的．