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local and global structure preserving based feature selection

NEUROCOMPUTING 2012年 89卷 147-157页

作者： Ren, Yazhou Zhang, Guoji Yu, Guoxian Li, Xuan S China Univ Technol Sch Comp Sci & Engn Guangzhou 510006 Guangdong Peoples R China S China Univ Technol Sch Sci Guangzhou 510640 Guangdong Peoples R China George Mason Univ Dept Comp Sci Fairfax VA 22030 USA

Feature selection is of great importance in data mining tasks, especially for exploring high dimensional data. Laplacian Score, a recently proposed feature selection method, makes use of local manifold structure of samples to select features and achieves good performance. However, it ignores the global structure of samples and the selected features are of high redundancy. To address these issues, we propose a feature selection method based on local and global structure preserving, LGFS in short. LGFS first uses two graphs, nearest neighborhood graph and farthest neighborhood graph to describe the underlying local and global structure of samples, respectively. It then defines a criterion to prefer the features which have good ability on local and global structure preserving. To remove redundancy among the selected features, Extended LGFS (E-LGFS) is introduced by taking advantage of normalized mutual information to measure the dependency between a pair of features. We conduct extensive experiments on two artificial data sets, six UCI data sets and two public available face databases to evaluate LGFS and E-LGFS. The experimental results show our methods can achieve higher accuracies than other unsupervised comparing methods. (c) 2012 Elsevier B.V. All rights reserved.

关键词： Laplacian Score local and global structure Redundancy Normalized mutual information

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Variational autoencoder based bipartite network embedding by integrating local and global structure

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INFORMATION SCIENCES 2020年第0期519卷 9-21页

作者： Jiao, Pengfei Tang, Minghu Liu, Hongtao Wang, Yaping Lu, Chunyu Wu, Huaming Tianjin Univ Ctr Biosafety Res & Strategy Tianjin Peoples R China Tianjin Univ Coll Intelligence & Comp Tianjin Peoples R China Tianjin Univ Ctr Appl Math Tianjin Peoples R China

As a powerful tool for machine learning on the graph, network embedding, which projects nodes into low-dimensional spaces, has a variety of applications on complex networks. Most current methods and models are not suitable for bipartite networks, which have two different types of nodes and there are no links between nodes of the same type. Furthermore, the only existing methods for bipartite network embedding ignore the internal mechanism and highly nonlinear structures of links. Therefore, in this paper, we propose a new deep learning method to learn the node embedding for bipartite networks based on the widely used autoencoder framework. Moreover, we carefully devise a node-level triplet including two types of nodes to assign the embedding by integrating the local and global structures. Meanwhile, we apply the variational autoencoder (VAE), a deep generation model with natural advantages in data generation and reconstruction, to enhance the node embedding for the highly nonlinear relationships between nodes and complex features. Experiments on some widely used datasets show the effectiveness of the proposed model and corresponding algorithm compared with some baseline network (and bipartite) embedding techniques. (C) 2020 Elsevier Inc. All rights reserved.

关键词： Bipartite network embedding local and global structure Variational autoencoder Nonlinear structure

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local, global and electronic structure of supported gold nanoclusters determined by EXAFS, XRD and XPS methods

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SUPERLATTICES AND MICROstructureS 2009年第1-2期46卷 141-148页

作者： Aldea, Nicolae Rednic, Vasile Pintea, Stelian Marginean, Petru Barz, Bogdan Gluhoi, Andreea Nieuwenhuys, Bernard E. Neumann, Manfred Xie Yaning Matei, Florica Univ Missouri Columbia MO 65211 USA Leiden Univ Leiden Inst Chem NL-2300 RA Leiden Netherlands Univ Osnabruck Fachbereich Phys D-49069 Osnabruck Germany Bejing Elect Positron Collider Natl Lab Beijing Synchrotron Radiat Facil Beijing Peoples R China Univ Agr Sci & Vet Med Cluj Napoca Romania

We analyze gold nanoclusters as supported catalysts by extended X-ray absorption fine structure, X-ray diffraction and X-ray photoelectron spectroscopy in order to determine their local, global and electronic structure. The present study points out a strong deformation of the local structure of the metal due to its interaction with oxide supports. We determine the particle size distribution and microstrain functions of the Au nanoclusters by X-ray diffraction method. Based on X-ray absorption fine structure spectroscopy analysis we show that the entire local structure of the investigated systems is strongly distorted regarding the average Au-Au coordination number. The distances between atoms are practically the same as standard Au foil. The strong metal-support interaction is confirmed by the change in shape of the electron transition probability densities that appear in the Au L(III)-edge. From XPS investigations we find electronic states corresponding to gold as well as to the oxide supports. (C) 2009 Published by Elsevier Ltd

关键词： Supported gold catalysts X-ray diffraction X-ray absorption spectroscopy X-ray photoelectron spectroscopy Metal-support interaction local and global structure

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Effect of local and global Structural Order on the Performance of Perylene Diimide Excimeric Solar Cells

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ACS APPLIED MATERIALS & INTERFACES 2013年第22期5卷 11844-11857页

作者： Ye, Tengling Singh, Ranbir Butt, Hans-Juergen Floudas, George Keivanidis, Panagiotis E. Fdn Ist Italiano Technol Ctr Nanosci & Technol PoliMi I-20133 Milan Italy Max Planck Inst Polymer Res D-55128 Mainz Germany Univ Ioannina Dept Phys GR-45110 Ioannina Greece

Herein, we present a detailed study of the structure-function relationship in the organic photovoltaic (OPV) blend film composed of N,N'-bis(1-ethylpropyl)-perylene-3,4,9,10-tetracarboxylic dii-mide (EP-PDI) and the low energy gap copolymer of poly[4,8-bis-substituted-benzo[1,2-b:4,5-b'] dithiophene -2,6-diyl-alt-4-substituted-thieno[3,4-b]thiophene-2,6-diyl] (PBDTTT-E-O). The hierarchical organization in the photoactive layers and in extruded fibers of PBDTTT-E-O:EP-PDI was studied by fluorescence optical microscopy, atomic force microscopy, and wide-angle X-ray scattering (WAXS). WAXS revealed a nanophase-separated structure where PBDTTT-E-O domains of 4.3 nm in size coexist with EP-PDI domains of 20 nm size. Thermal annealing results in an increase of the PBDTTT-E-O domains, but it does not affect the size of the EP-PDI domains. Only the length of the EP-PDI columns in each domain is increased by thermal treatment. The photophysical characterization of the PBDTTT-E-O:EP-PDI layers and the electrical characterization of the corresponding OPV and unipolar carrier devices were performed. The quenching of the EP-PDI excimer luminescence is correlated with the photocurrent generation efficiency of the OPV devices. At high annealing temperatures the EP-PDI columnar length becomes larger than the previously reported diffusion length of the PDI excimer, and fewer excimers dissociate at the EP-PDI/polyrner interfaces, leading to reduced photocurrent generation. The charge transport properties of the PBDTTT-E-O:EP-PDI blend film were studied as a function of the active layer microstructure that was tuned by thermal treatment. Thermal processing increases electron mobility, but the poor connectivity of the EP-PDI domains keeps hole mobility six times higher. In respect to the as-spun OPV device, a 3-fold increase is found in the power conversion efficiency of the device annealed at 100 degrees C. The high surface roughness of the PBDTTT-E-O:EP-PDI photoactive layer impedes

关键词： perylene diimides excimer organic solar cells nonfullerene acceptors local and global structure charge transport extraction

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Crystalline and electronic structure of Ni nanoclusters supported on Al₂O₃and Cr₂O₃ investigated by XRD, XAS and XPS methods

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SUPERLATTICES AND MICROstructureS 2009年第1-2期46卷 130-136页

作者： Pintea, Stelian Rednic, Vasile Marginean, Petru Aldea, Nicolae Tiandou, Hu Wu, Zhonghua Neumann, Manfred Matei, Florica Natl Inst R&D Isotop & Mol Technol Cluj Napoca 400293 5 Romania Beijing Electron Positron Collider Natl Lab Beijing Synchrotron Radiat Facil Beijing Peoples R China Univ Osnabruck Fachbereich Phys D-49069 Osnabruck Germany Univ Agr Sci & Vet Med Cluj Napoca Romania

In this paper, we investigate the crystalline and electronic structure of Ni nanoclusters supported on Al2O3 and Cr2O3 obtained at different reduction temperatures. Their physical properties were characterized by powder X-ray diffraction, X-ray absorption spectroscopy and X-ray photoelectron spectroscopy techniques. The global parameters of the active metal nanostructure such as average crystallite size and the microstrain are obtained by the generalized Fermi function for fitting the experimental X-ray line profiles. By X-ray absorption spectroscopy we evidenced a diminution of the coordination number in the first shell of the nickel atoms. In order to characterize the electronic structure of the active metal, X-ray photoelectron spectroscopy measurements were performed. Our results give additional information about the strong interaction between the metal clusters and oxide supports. (c) 2009 Published by Elsevier Ltd

关键词： Supported nickel catalysts local and global structure Electronic structure XRD EXAFS XPS

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Intensifying graph diffusion-based salient object detection with sparse graph weighting

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MULTIMEDIA TOOLS AND APPLICATIONS 2023年第22期82卷 34113-34127页

作者： Wang, Fan Peng, Guohua Xian Shiyou Univ Sch Sci Xian 710065 Shaanxi Peoples R China Northwestern Polytecn Univ Sch Math & Stat Xian 710129 Shaanxi Peoples R China

Salient object detection based on the diffusion process on the graph has achieved considerable performance. It mainly depends on the affinity matrix construction considering the local structure. This paper aims to depict the local and global structures from image features, intensifying the graph-based diffusion model by simultaneously integrating the sparse graph matrix and affinity graph matrix. The contribution work computes the affinity graph matrix and delivers an affinity matrix by incorporating the sparse representation and diffusion process. It estimates a sparse graph matrix by integrating sparse representation and laplacian smoothness. To this end, a two-stage graph-based diffusion model has been constructed by embedding the manifold smoothness and manifold reconstruction. The first stage follows the boundary-prior to generate a coarse saliency map. After, the second stage combines the saliency map and Harris convex hull to obtain the foreground seeds. Extensive experiments on six benchmark datasets have demonstrated the superiority of the proposed method compared to other state-of-the-art methods.

关键词： Salient object detection Graph-based diffusion Sparse graph matrix Affinity graph matrix local and global structure

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Investigation of nanostructured Fe₃O₄ polypyrrole core-shell composites by X-ray absorbtion spectroscopy and X-ray diffraction using synchrotron radiation

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JOURNAL OF NANOPARTICLE RESEARCH 2009年第6期11卷 1429-1439页

作者： Aldea, Nicolae Turcu, Rodica Nan, Alexandrina Craciunescu, Izabella Pana, Ovidiu Yaning, Xie Wu, Zhonghua Bica, Doina Vekas, Ladislau Matei, Florica Natl Inst Res & Dev Isotop & Mol Technol Cluj Napoca Romania Natl Lab Beijing Synchrotron Radiat Facil Beijing Beijing Peoples R China Romanian Acad Timisoara Branch Magnet Fluids Lab Timisoara Romania Agr Sci & Med Vet Univ Cluj Napoca Romania

In this article, we focus on the structural peculiarities of nanosized Fe3O4 in the core-shell nanocomposites obtained by polymerization of conducting polypyrrole shell around Fe3O4 nanoparticles. The local structure of Fe atoms was determined from the Extended X-ray Absorption Fine structure analysis using our own package computer programs. An X-ray diffraction method that is capable to determine average particle size, microstrains, as the particle size distribution of Fe3O4 nanoparticles is presented. The method is based on the Fourier analysis of a single X-ray diffraction profile using a new fitting method based on the generalized Fermi function facilities. The crystallites size obtained by X-ray diffraction spectra analysis was estimated between 3.2 and 10.3 nm. Significant changes in the first and the second Fe coordination shell in comparison with standard bulk were observed. The global and local structure of the nanosized Fe3O4 are correlated with the synthesis conditions of the core-shell polypyrrole nanocomposites.

关键词： X-ray spectroscopy Synchrotron radiation local and global structure Magnetite

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Preparation and structural characterization by XRD and XAS of the supported gold catalysts

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JOURNAL OF OPTOELECTRONICS AND ADVANCED MATERIALS 2008年第9期10卷 2244-2251页

作者： Lazar, M. Almasan, V. Pintea, S. Barz, B. Ducu, C. Malinovschi, V. Yaning, X. Aldea, N. Univ Missouri Columbia MO 65211 USA Natl Inst Res & Dev Isotop & Mol Technol Cluj Napoca 400293 Romania Univ Pitesti Adv Mat Dept Pitesti Romania Coordinat Lab Natl Ctr Nanosci & Nanotechnol Synchroton Radiat Facil Beijing Electron Positron Beijing Peoples R China

A series of supported gold catalysts were studied by X-ray diffraction (XRD) in order to determine the Au average particle size, microstrain information and probability of faults. The gold catalysts samples (up to 5 wt.% gold content) were prepared by two methods - impregnation of the oxidic support with aqueous solution of HAuCl4 center dot 3H(2)O and homogeneous deposition-precipitation using urea as precipitating agent. The following metal oxides, with high specific surface area were used as supports: Cr2O3, CeO2, TiO2, SiO2, Al2O3 and ZrO2. The XRD method is based on the deconvolution of the experimental Xray line profiles (XRLP) (111), (200), (220) and (311) using Fourier transform procedure. The global structure is determined by fitting the XRLP with the generalized Fermi function. The X-ray diffraction data was collected at room temperature, using Bragg-Brentano (BB) geometry installed on DRON 2 set up, connected with a PC. The samples were next analyzed by extended X-ray absorption fine structure (EXAFS) of the Au L-III-edge using synchrotron radiation in order to determine their local structure that explains the strong deformation of the metal due to its interaction with the oxide supports.

关键词： supported gold catalysts local and global structure metal support interaction X-ray diffraction synchrotron radiation

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Temporal-Spatial global locality Projections for Multimode Process Monitoring

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IEEE ACCESS 2018年 6卷 9740-9749页

作者： Song, Bing Shi, Hongbo East China Univ Sci & Technol Minist Educ Key Lab Adv Control & Optimizat Chem Proc Shanghai 200237 Peoples R China

Multimode is an important feature of modern processes, since various manufacturing strategies are needed to satisfy different demands of markets. Direct application of traditional multivariate statistical process monitoring methods cannot obtain satisfactory results, as the data set collected from multimode processes always follows multimodal distribution. To construct a single model which can monitor multimode processes directly, this paper proposes an original algorithm named temporal-spatial global locality projections. First, given that both temporal and spatial neighbors can express the similarity, the determination of the neighborhood is conducted in both the temporal and spatial scale. Second, an optimization objective function which preserves not only the local structure but also the global structure is defined. Third, the monitoring statistic is established via the local outlier factor. To certify the effectiveness, a numerical example, the multimode Tennessee Eastman process, and the CE117 process which is proposed by TecQuipment for process control are studied.

关键词： Multimode process monitoring temporal and spatial scale local and global structure temporal-spatial global locality projections

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Turing patterns in a reaction-diffusion model with the Degn-Harrison reaction scheme

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JOURNAL OF DIFFERENTIAL EQUATIONS 2015年第5期259卷 1990-2029页

作者： Li, Shanbing Wu, Jianhua Doug, Yaying Shaanxi Normal Univ Coll Math & Informat Sci Xian 710062 Shaanxi Peoples R China NW Univ Xian Sch Math Xian 710069 Shaanxi Peoples R China

In this paper, we consider a reaction-diffusion model with Degn-Harrison reaction scheme. Some fundamental analytic properties of nonconstant positive solutions are first investigated. We next study the stability of constant steady-state solution to both ODE and PDE models. Our result also indicates that if either the size of the reactor or the effective diffusion rate is large enough, then the system does not admit nonconstant positive solutions. Finally, we establish the global structure of steady-state bifurcations from simple eigenvalues by bifurcation theory and the local structure of the steady-state bifurcations from double eigenvalues by the techniques of space decomposition and implicit function theorem. (C) 2015 Elsevier Inc. All rights reserved.

关键词： Degn-Harrison Fundamental properties Stability Nonexistence local and global structure

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