一种基于向量空间模型的文本聚类方法

研究了一种基于向量空间模型的文档聚类方法.提出了一个新的聚类模型,即在传统聚类模型的基础上增加一个文档特征向量调整模块;给出了一个特征评价函数用以进行特征提取;对一种基于相似度的平面划分聚类算法做了一些改进.实验结果表明本文提出的聚类模型是可行的.     

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。     

向量空间模型在医学文献相关性研究中的应用

为提高医学文献检索的效率和检索结果输出的有效性，快速客观地为科研人员提供高信度、低冗余的参考文献，实现检索结果按相关度排序输出，就基于向量空间模型的文献相关度计算方案进行探讨，提出基于相关度的医学文献聚类分析和相关度排序。     

Image compression on a VLSI neural-based vector quantizer

A self-organization algorithm for image compression and the associated VLSI architecture are presented. A frequency upper-threshold is effectively used in the centroid learning method. Performances of the self-organization networks and traditional nonself-organization algorithms for vector quantization are compared. This new algorithm is quite efficient and can achieve near-optimal results. A trainable VLSI neuroprocessor based upon this new self-organization network has been developed for high-speed and high-ratio image compression applications. This neural-based vector quantization design includes a fully parallel vector quantizer and a pipelined codebook generator which obtains a time complexity O (1) for each quantization vector. A 5 × 5-dimensional vector quantizer prototype chip has been designed and fabricated. It contains 64 inner-product neural units and an extendable winner-take-all block. This mixed-signal chip occupies a compact silicon area of 4.6 × 6.8 mm² in a 2.0-μm scalable CMOS technology. It provides a computing capability as high as 3.33 billion connections per second. It can achieve a speedup factor of 110 compared with a SUN-4/75 workstation for a compression ratio of 33. Real-time adaptive VQ on industrial 1024 × 1024 pixel images is feasible using multiple neuroprocessor chips. An industrial-level design to achieve 104 billion connections per second for the 1024-codevector vector quantizer can be fabricated in a 125 mm² chip through a 1 μm CMOS technology.     

矢势（A）在经典物理与量子物理中的作用

矢势（A）在量子物理中具有磁场（B）所不能替代的重要作用,然而在经典物理的电磁理论中矢势（A）却只是磁场（B）的辅助矢量,且无直接观测的物理意义.从经典物理与量子物理的不同视角全面认识矢势（A）具有的作用,对于正确理解矢势（A）的意义、更好地掌握电磁场理论以及对于分析和解决实际的电磁场问题都具有重要的指导意义.     

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。     

稀土交流永磁电机数学模型及控制

对稀土交流永磁电机的结构特点进行了分析,研究了电机的数学模型.充分利用转子位置检测器的转子检测信号,进行特殊的逻辑处理以完成复杂的矢量控制,使定子电流和感应电势同相,从而达到用电流来控制电磁转矩的目的.文章给出了具体工作电路和特殊问题的处理方法.     

Classification of power quality combined disturbances based on phase space reconstruction and support vector machines

Power Quality （PQ） combined disturbances become common along with ubiquity of voltage flickers and harmonics. This paper presents a novel approach to classify the different patterns of PQ combined disturbances. The classification system consists of two parts, namely the feature extraction and the automatic recognition. In the feature extraction stage, Phase Space Reconstruction （PSR）, a time series analysis tool, is utilized to construct disturbance signal trajectories. For these trajectories, several indices are proposed to form the feature vectors. Support Vector Machines （SVMs） are then implemented to recognize the different patterns and to evaluate the efficiencies. The types of disturbances discussed include a combination of short-term disturbances （voltage sags, swells） and long-term disturbances （flickers, harmonics）, as well as their homologous single ones. The feasibilities of the proposed approach are verified by simulation with thousands of PQ events. Comparison studies based on Wavelet Transform （WT） and Artificial Neural Network （ANN） are also reported to show its advantages.     

中国燃料油价格国际市场相关性的实证研究

上海燃料油期货合约上市之后,在参照新加坡市场走势的同时,也参照了国际原油市场的走势,价格发现功能得到一定程度发挥,改变了过去新加坡市场在国内燃料油现货市场独一无二的作用,上海燃料油期货价格成为上海、新加坡、NYMEX等多方作用的结果。本文采用协整理论、基于向量自回归(VAR)的Granger因果关系检验以及向量误差修正模型(VECM),从多变量的角度对燃料油期货上市前后国内外燃料油价格的相关性进行实证分析。协整检验结果显示:燃料油期货上市后,新加坡燃料油价格波动对国内燃料油价格波动的影响显著减小,弹性从燃料油期货上市前的0.68减少到上市后的0.57,同时NYMEX原油期货对国内燃料油价格的价格影响也有所体现(弹性值为0.22)。这说明燃料油期货上市后,市场定价机制得到一定改善,但是上海燃料油市场价格仍然不能摆脱国际市场的影响;要使其充分反映国内的供求情况,必须要在增加国家软实力的基础上,不断完善期货市场价格发现体系。     

Social Contradictions in Informational Capitalism: The Case of Finnish Wage Earners and Their Labor Market Situation

Along with the diffusion of information and communication technologies (ICTs), work processes are becoming ever more knowledge intensive. In keeping with this trend, the number of informational (or knowledge) workers in Finland has more than tripled from 12% in 1988 to 39% in 2000. What makes the Finnish case unique and interesting is the exceptional speed with which the information sector of the economy has grown. A few years after facing the most severe economic recession in its history in the early 1990s, Finland is now considered to have an advanced information economy. However, our empirical analysis--based on survey data from 1988, 1994, and 2000--yields a somewhat more critical picture of the Finnish information society than what usually comes across in the mainstream media. The opportunities for social equality offered by the growth of informational work are far more limited than was the case with the transition from agricultural to industrial production.