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Search Results: 1 - 10 of 27621 matches for " Zhenfang Hu "
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Sparse Principal Component Analysis via Rotation and Truncation
Zhenfang Hu,Gang Pan,Yueming Wang,Zhaohui Wu
Computer Science , 2014,
Abstract: Sparse principal component analysis (sparse PCA) aims at finding a sparse basis to improve the interpretability over the dense basis of PCA, meanwhile the sparse basis should cover the data subspace as much as possible. In contrast to most of existing work which deal with the problem by adding some sparsity penalties on various objectives of PCA, in this paper, we propose a new method SPCArt, whose motivation is to find a rotation matrix and a sparse basis such that the sparse basis approximates the basis of PCA after the rotation. The algorithm of SPCArt consists of three alternating steps: rotate PCA basis, truncate small entries, and update the rotation matrix. Its performance bounds are also given. SPCArt is efficient, with each iteration scaling linearly with the data dimension. It is easy to choose parameters in SPCArt, due to its explicit physical explanations. Besides, we give a unified view to several existing sparse PCA methods and discuss the connection with SPCArt. Some ideas in SPCArt are extended to GPower, a popular sparse PCA algorithm, to overcome its drawback. Experimental results demonstrate that SPCArt achieves the state-of-the-art performance. It also achieves a good tradeoff among various criteria, including sparsity, explained variance, orthogonality, balance of sparsity among loadings, and computational speed.
Spectral Sparse Representation for Clustering: Evolved from PCA, K-means, Laplacian Eigenmap, and Ratio Cut
Zhenfang Hu,Gang Pan,Yueming Wang,Zhaohui Wu
Computer Science , 2014,
Abstract: Dimensionality reduction methods, e.g. PCA and Laplacian eigenmap (LE), and cluster analysis methods, e.g. K-means and ratio cut (Rcut), are two kinds of widely-used unsupervised data analysis tools. The former concerns high representation fidelity, while the latter semantics. Some preliminary relations between these methods have been established in the literature, but they are not yet integrated into a unified framework. In this paper, we show that under an ideal condition, the four methods: PCA, K-means, LE, and Rcut, are unified together; and when the ideal condition is relaxed, the unification evolves to a new sparse representation method, called spectral sparse representation (SSR). It achieves the same representation fidelity as PCA/LE, and is able to reveal the cluster structure of data as K-means/Rcut. SSR is inherently related to cluster analysis, and the sparse codes can be directly used to do clustering. An efficient algorithm NSCrt is developed to solve the sparse codes of SSR. It is observed that NSCrt is able to effectively recover the underlying solutions. As a direct application of SSR, a new clustering algorithm Scut is devised. It reaches the start-of-the-art performance among spectral clustering methods. Compared with K-means based clustering methods, Scut does not depend on initialization and avoids getting trapped in local minima; and the solutions are comparable to the optimal ones of K-means run many times. Extensive experiments using data sets of different nature demonstrate the properties and strengths of SSR, NSCrt, and Scut.
Water-Air Mixing Jet Produced by Electro-hydraulic Impulse Technology Strengthening the Quality of Surface of Metal Materials
Water—Air Mixing Jet Produced by Electro—hydraulic Impulse Technology Strengthening the Quality of Surface of Metal Materials

Zhenfang LIAO,Shijin ZHANG,
Zhenfang
,ShijinZHANG

材料科学技术学报 , 2002,
Abstract: Electro-hydraulic impulse water-air mixing jet by which the quality of metal materials can be improved is described in this paper. The experimental results proved that the hardness and the micro-hardness of the surface layer of metal materials can be improved with this method, for example, the microhardness of CrWMn can be increased by 35.62 percent.
Fast evolution of growth hormone receptor in primates and ruminants
Hou Zhenfang,Li Ying,Zhang Yaping
Chinese Science Bulletin , 2005, DOI: 10.1360/982005-85
Abstract: Pituitary growth hormone (GH) evolves very slowly in most of mammals, but the evolutionary rates appear to have increased markedly on two occasions during the evolution of primates and ruminants. To investigate the evolutionary pattern of growth hormone receptor (GHR), we sequenced the extracellular domain of GHR genes from four primate species. Our results suggested that GHR in mammal also shows an episodic evolutionary pattern, which is consistent with that observed in pituitary growth hormone. Further analysis suggested that this pattern of rapid evolution observed in primates and ruminants is likely the result of coevolution between pituitary growth hormone and its receptor.
Research on PrinceDan''s Revenge
《燕丹子》考辨

Ma Zhenfang,
马振方

浙江大学学报(人文社会科学版) , 2010,
Abstract: Different theories have evolved on the year of the completion of Prince Dan's Revenge and its relations with Records of the Historian,which has laid foundation for further academic exploration. Although the specific year in which the book was written cannot be determined by combing through and analyzing the relevant materials,the lower limit of the time can be discerned and a clue can be found as to the developmental course of the legendary history of the same topic. The most direct and reliable approach to...
CORRELATION BETWEEN NUMERAL FRACTURE CHAR-ACTERISTICS AND FRACTURE TOUGHNESS OF MEDIUM-CARBON CrNiMo STEEL

by Zhang Zhenfang,Zhang Tianyi,Liu Minzhi,

金属学报 , 1981,
Abstract:
Research on Information Retrieval System Based on Ant Clustering Algorithm
Peiyu Liu,Zhenfang Zhu,Lina Zhao
Journal of Software , 2009, DOI: 10.4304/jsw.4.9.1032-1036
Abstract: Internet is more and more widely used, which provide a valuable information resource for users. How retrieve the information users prefers rapidly and accurately become the focus nowadays. With introducing ant-based clustering and sorting, it makes a more precise and rapid clustering result. Consequently, it increases the speed and efficiency of information retrieval.
Cloning and functional analysis of the sequences flanking mini-Tn5 in the magnetosome-deleted mutant NM21 of Magnetospirillum gryphiswaldense MSR-1
Feng Li,Ying Li,Wei Jiang,ZhenFang Wang,JiLun Li
Chinese Science Bulletin , 2009, DOI: 10.1007/s11434-009-0235-y
Abstract: A magnetosome-deleted mutant NM21 of Magnetospirillum gryphiswaldense MSR-1 was generated by mini-Tn5 lacZ2 transposon mutagenesis, and a 3073-bp fragment flanking mini-Tn5 lacZ2 in NM21 was cloned by Anchored PCR. Sequencing analysis showed that this fragment involved three putative ORFs; the mini-Tn5 lacZ2 was inserted into ORF1. Functional complementary test indicated that the 3073-bp fragment was required for biosynthesis of magnetosomes in M. gryphiswaldense MSR-1. The majority of proteins, which had homology with the protein encoded by ORF1, were the cation transporter. Transmembrane domain analysis showed that the protein encoded by ORF1 contained four transmembrane domains. It may be a transmembrane protein. The protein encoded by ORF1 contained two putative conserved domains: COG0053 and PRK09509. The MMT1 and FieF, containing conserved domains COG0053 and PRK09509 too, were Fe2+ transporter (cation diffusion facilitator superfamily). It was suggested that the protein encoded by ORF1 might take part in the magnetosomes biosynthesis as Fe2+ transporter.
Cloning and functional analysis of the sequences flanking mini-Tn5 in the magnetosomes deleted mutant NM4 of Magnetospirillum gryphiswaldense MSR-1
Feng Li,Ying Li,Wei Jiang,Zhenfang Wang,Jilun Li
Science China Life Sciences , 2005, DOI: 10.1360/062005-26
Abstract: A magnetosome deleted mutant NM4 of Magnetospirillum gryphiswaldense MSR-1 was generated by mini-Tn5 transposon mutagenesis, and a 5045-bp fragment flanking mini-Tn5 in NM4 was cloned by Anchored PCR. Sequencing analysis showed that this fragment involved six putative open reading frames (ORFs); the mini-Tn5 was inserted into ORF4. Functional complementary test indicated that the 5045-bp fragment was required for biosynthesis of magnetosomes in M. gryphiswaldense MSR-1. The protein encoded by ORF4 had 25% of identity with the chemotaxis protein CheYIII of Caulobacter crescentus CB15, and the protein encoded by ORF4 contained a conserved signal receiver domain that can receive the signal from the sensor partner of the bacterial two-component systems. It was suggested that the protein encoded by ORF4 may take part in the signal transduction relating to biosynthesis of magnetosomes.
A Comparative Analysis of the Knowledge Gap Effects between New Media and Old Media
新旧媒体知识沟效果之比较研究

Wei Lu,Li Zhenfang,
韦路
,李贞芳

浙江大学学报(人文社会科学版) , 2009,
Abstract: 作为影响知识沟形成的一个重要因素,传播媒介差异一直以来都是学者关注的一个焦点.然而,以往研究主要集中在对报纸和电视的知识沟效果的比较,鲜有研究对以因特网为代表的新媒介和传统媒介的知识沟效果的差异进行实证探讨.通过对两组不同时期美国全国性调查数据的分析,发现不同社会经济地位者之间的使用沟在因特网上比在传统媒介上更为明显.更重要的是,因特网上较大的使用沟也导致了更为显著的知识沟,使得数字鸿沟不仅在强度上,更在后果上有甚于传统媒介的使用差异.这些发现一方面有助于我们在理论上加深对知识沟现象及其成因的理解,另一方面也为方兴未艾的数字鸿沟研究的必要性提供了进一步的实证支持.
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