Flash中的二维向量实现

多媒体教学是一种现代化的教学方式.本文以多媒体课件制作中的向量实现为主题,阐述了flash在制作课件中实现向量的可视化,帮助课件制作时解决物理运动真实性的问题.     

利用阵列孔径信息的到达角估计新方法

孔径信息能改善阵列信号参数估计。提出一种利用阵列孔径信息的到达角估计新方法,阵列由三个电磁矢量传感器呈L型排列构成,阵元间距不要求一致,且能超过入射信号最小波长的半波长。解模糊时将矢量叉乘方法获得的方向余弦值与利用孔径信息获得的方向余弦值相比较,通过模糊次数的搜索得到方向余弦的精确估计值。仿真结果证明上述方法的有效性。     

基于最小二乘支持向量机的油罐故障诊断方法

根据油罐故障分析,建立了油罐故障诊断模型。采用新型的支持向量机-最小二乘向量机(LS-SVM)的算法对此诊断模型进行预测,获得了满意的效果。该方法易于使用,很少受不确定性因素的影响,有很高的预测准确性。     

安徽省固定资产投资对经济增长影响的实证分析

基于1990-2013年的时间序列数据,利用协整检验、格兰杰因果检验、向量自回归模型、脉冲响应以及方差分解等方法,对安徽省固定资产投资与经济增长的关系进行动态计量分析。结果发现,安徽省固定资产投资与经济增长存在着长期均衡关系,且固定资产投资是经济增长的格兰杰原因。从脉冲响应函数分析结果来看,固定资产投资在整个考察期内有利于安徽省经济增长,并且时滞也较长。从方差分解结果看,短期内固定资产投资的冲击对经济增长误差的解释能力相对较小,长期则有较强的解释能力。结合分析结果,从增加投资规模、拓展投资来源、调整投资结构、提升投资效率四个方面给予了相应的对策建议。     

Beyond vector space model for hierarchical Arabic text classification: A Markov chain approach

The vector space model (VSM) is a textual representation method that is widely used in documents classification. However, it remains to be a space-challenging problem. One attempt to alleviate the space problem is by using dimensionality reduction techniques, however, such techniques have deficiencies such as losing some important information. In this paper, we propose a novel text classification method that neither uses VSM nor dimensionality reduction techniques. The proposed method is a space efficient method that utilizes the first order Markov model for hierarchical Arabic text classification. For each category and sub-category, a Markov chain model is prepared based on the neighboring characters sequences. The prepared models are then used for scoring documents for classification purposes. For evaluation, we used a hierarchical Arabic text data collection that contains 11,191 documents that belong to eight topics distributed into 3-levels. The experimental results show that the Markov chains based method significantly outperforms the baseline system that employs the latent semantic indexing (LSI) method. That is, the proposed method enhances the F1-measure by 3.47%. The novelty of this work lies on the idea of decomposing words into sequences of characters, which found to be a promising approach in terms of space and accuracy. Based on our best knowledge, this is the first attempt to conduct research for hierarchical Arabic text classification with such relatively large data collection.     

A Query Expansion Framework in Image Retrieval Domain Based on Local and Global Analysis

We present an image retrieval framework based on automatic query expansion in a concept feature space by generalizing the vector space model of information retrieval. In this framework, images are represented by vectors of weighted concepts similar to the keyword-based representation used in text retrieval. To generate the concept vocabularies, a statistical model is built by utilizing Support Vector Machine (SVM)-based classification techniques. The images are represented as "bag of concepts" that comprise perceptually and/or semantically distinguishable color and texture patches from local image regions in a multi-dimensional feature space. To explore the correlation between the concepts and overcome the assumption of feature independence in this model, we propose query expansion techniques in the image domain from a new perspective based on both local and global analysis. For the local analysis, the correlations between the concepts based on the co-occurrence pattern, and the metrical constraints based on the neighborhood proximity between the concepts in encoded images, are analyzed by considering local feedback information. We also analyze the concept similarities in the collection as a whole in the form of a similarity thesaurus and propose an efficient query expansion based on the global analysis. The experimental results on a photographic collection of natural scenes and a biomedical database of different imaging modalities demonstrate the effectiveness of the proposed framework in terms of precision and recall.     

永磁同步电机速度环的滑模变结构控制

在永磁同步电机解耦数学模型的基础上,本文提出了一种把滑模变结构原理用于永磁同步电机的矢量控制系统的方法。首先详细阐述了滑模变结构的基本原理,然后采用速度环的滑模变结构来取代传统的PI控制,并对两个系统进行了仿真分析,仿真结果证明采用速度环的滑模变结构控制系统确有其优越性。     

计算化学反应热的一种数学方法

在热化学中,常需计算反应热。当中间反应个数较少时,例如仅有三、四个反应式,可以用观察法计算反应热,但是当中间反应式个数较多时,观察法则极不适用,可以用系统的数学方法计算化学反应热     

基于核聚类的K-均值聚类（英文稿）

为处理线性不可分、结构复杂的数据集,提出基于核聚类的K 均值聚类(Kernel Clustering based K means Clustering,KCKC).该方法先在原始空间中对模式进行聚类,再由径向基函数(Radial Basis Function, RBF)核把它们映射到核空间,从而保持大部分模式之间的关系.把提出的方法应用到基于RBF的神经网络(RBF based Neural Network,RBFNN)、基于RBF的支持向量机(RBF based Support Vector Machine, RBFSVM)和核最近邻分类器(Kernel Nearest Neighbor Classifier,KNNC)中,结果表明本文提出的算法可以生成更有效的核,节省在核空间中的核生成时间,避免核数目设置的敏感性,并提高分类性能.