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Acta Mechanica Sinica 2008年第1期24卷 91-99页

作者： Xuesong Long Xianghe Peng Wenli pi Department of Engineering Mechanics Chongqing University Chongqing 400044 China

A pearlitic steel is composed of numerous pearlitic colonies with random orientations, and each colony consists of many parallel lamellas of ferrite and cementite. The constitutive behavior of this kind of materials may involve both inherent anisotropy and plastic deformation induced anisotropy. A description of the cyclic plasticity for this kind of dual-phase materials is proposed by use of a microstructure-based constitutive model for a pearlitic colony, and the Hill＇s self-consistent scheme incorporating anisotropic Eshelby tensor for ellipsoidal inclusions. The corresponding numerical algorithm is developed. The responses of pearlitic steel BS 11 and single-phase hard-drawn copper subjected to asymmetrically cyclic loading are analyzed. The analytical results agree very well with experimental ones. Compared with the results using isotropic Eshelby tensor, it is shown that the isotropic approximation can provide acceptable overall responses in a much simpler way.

关键词： Pearlitic steel Hill's self-consistent scheme Eshelby tensor Cyclic plasticity Microstructure-basedanalysis

Ensemble kernel method：SVM classification based on game theory

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Journal of Systems Engineering and Electronics 2016年第1期27卷 251-259页

作者： Yufei Liu Dechang pi Qiyou Cheng College of Computer Science and Technology Nanjing University of Aeronautics and Astronautics Nanjing 210016 China Department of Computer Science and Technology Tangshan College Tangshan 063000 China Collaborative Innovation Center of Novel Software Technology and Industrialization Nanjing 211106 China China Helicopter Research and Development Institute Jingdezhen 333001 China

With the development of the support vector machine（SVM）,the kernel function has become one of the cores of the research on *** a large extent,the kernel function determines the generalization ability of the classifier,but there is still no general theory to guide the choice and structure of the kernel *** ensemble kernel function model based on the game theory is proposed,which is used for the SVM classification *** model can effectively integrate the advantages of the local kernel and the global kernel to get a better classification result,and can provide a feasible way for structuring the kernel *** making experiments on some standard datasets,it is verified that the new method can significantly improve the accuracy of classification.

关键词： game theory classification radial basis kernel polynomial kernel.

Density-based trajectory outlier detection algorithm

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Journal of Systems Engineering and Electronics 2013年第2期24卷 335-340页

作者： Zhipeng Liu Dechang pi Jinfeng Jiang College of Information Science and Technology Nanjing University of Aeronautics and Astronautics College of Computer Science and Techonology Nanjing University of Posts and Telecommunications

With the development of global position system（GPS）,wireless technology and location aware services,it is possible to collect a large quantity of trajectory *** the field of data mining for moving objects,the problem of anomaly detection is a hot *** on the development of anomalous trajectory detection of moving objects,this paper introduces the classical trajectory outlier detection（TRAOD） algorithm,and then proposes a density-based trajectory outlier detection（DBTOD） algorithm,which compensates the disadvantages of the TRAOD algorithm that it is unable to detect anomalous defects when the trajectory is local and *** results of employing the proposed algorithm to Elk1993 and Deer1995 datasets are also presented,which show the effectiveness of the algorithm.

关键词： density-based algorithm trajectory outlier detection(TRAOD) partition-and-detect framework Hausdorff distance

High resolution wide swath revisit synthetic aperture radar imaging mode and algorithm

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Journal of Systems Engineering and Electronics 2015年第2期26卷 274-281页

作者： Weihua Zuo Yiming pi Rui Min School of Electronic Engineering University of Electronic Science and Technology of China Department of Physics and Information Engineering Huaihua University

Based on the squint mode, a high resolution wide swath revisit synthetic aperture radar （SAR） imaging mode is pro- posed. The transmitting antennas are configured as the single phase center multiple azimuth beams （SPC MAB）. The formed two beams point to two different directions to obtain two images of the observed scenario. The receiving antennas are configured as displaced phase center multiple azimuth beams （DPC MAB） to decrease the required pulse repetition frequency （PRF）. The de- creased PRF can ensure the high resolution wide swath imaging. Based on the analysis of the character of the return signal, a pro- cessing method named multiple beam multiple channel algorithm （MBMCA） is proposed to separate the aliased sub-beams＇ echoes. The separated echoes are focused respectively to get the revisit imaging to the observed scenario. The simulation experiments ve- rify the validity and correctness of the proposed imaging mode and processing algorithm.

关键词： synthetic aperture radar(SAR) high resolution wide swath revisit

Density Functional Theory Study on the Oxidation of Hydrosilylated Silicon Nanocrystals

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Journal of Materials Science & Technology 2014年第7期30卷 639-643页

作者： Xiaodong pi Rong Wang Deren Yang State Key Laboratory of Silicon Materials and Department of Materials Science and Engineering Zhejiang University

As a leading surface modification approach, hydrosilylation enables freestanding silicon nanocrystals （Si NCs） to be well dispersed in a desired medium. Although hydrosilylation-induced organic layers at the NC surface may somehow retard the oxidation of Si NCs, oxidation eventually occurs to Si NCs after relatively long time exposure to air. We now investigated the oxidation of hydrosilylated Si NCs in the frame work of density functional theory （DFT）. Three oxygen configurations that may be introduced by the oxidation of a Si NC are considered. It is found that a hydrosilylated Si NC is less prone to oxidation than a fully H-passivated Si NC in the point of view of thermodynamics. At the ground state, backbond oxygen （BBO） and hydroxyl （OH） hardly change the gap between the highest occupied molecular orbital （HOMO） and the lowest unoccupied molecular orbital （LUMO） of a hydrosilylated Si NC. At the excited state, the decrease in the HOMO-LUMO gap induced by the introduction of doubly bonded oxygen （DBO） is more significant than that induced by the introduction of BBO or OH. We have correlated the changes in the optical absorption （emission） of a hydrosilylated Si NC after oxidation to those of the HOMO-LUMO gap at the ground state （excited state）.

关键词： Silicon nanocrystals Density functional theory Hydrosilylation Oxidation Electronic properties Optical properties

BiCoO3-doped （Ko.47sN ***）（N bo.8Tao.2）03 lead-free piezoelectric ceramics

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Frontiers of Materials Science 2012年第4期6卷 311-318页

作者： Ke-pi CHEN Zhe ZHANG School of Energy Power and Mechanical EngineeringNorth China Electric Power UniversityBeijing 102206China

（1-x）（***）（***0.2）O3-xBiCoO3 （KNLNT-BC） lead-free piezoelectric ceramics were prepared by the conventional solid-state sintering method. Effects of the BC content on the phase structure, microstructure and electrical properties of KNLNT-BC ceramics were investigated. XRD patterns reveal that all the ceramic samples are in the pure perovskite-type structure, and the phase structure changes from the tetragonal to pseudo-cubic phase with the increase of the BC content. After the substitution of BC, the grain size is significantly reduced and relaxer behaviors are induced. By adding a small amount of BC to KNLNT ceramics, piezoelectric properties are improved, while further addition of BC makes the piezoelectric properties deteriorate markedly. The optimized electrical properties atx= 0.005 are as follows： d33 = 194 pC/N, kp = 0.44.

关键词： lead-free ceramic potassium sodium niobate BiCo03 piezoelectric property

PT-symmetry berry phases,topology and PT-symmetry breaking

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Communications in Theoretical Physics 2020年第4期72卷 45-51页

作者： Jinghui pi NingNing Sun Rong Lü Department of Physics Tsinghua UniversityBeijing 100084China Frontier Science Center for Quantum Information BeijingChina State Key Laboratory of Low-Dimensional Quantum Physics BeijingChina

We study the complex Berry phases in non-Hermitian systems with parity-and time-reversal(PT)*** investigate a kind of two-level system with PT *** find that the real part of the the complex Berry phases have two quantized values and they are equal to either 0 orΠ,which originates from the topology of the Hermitian *** also find that if we change the relative parameters of the Hamiltonian from the unbroken-PT-symmetry phase to the broken-PT-symmetry phase,the imaginary part of the complex Berry phases are divergent at the exceptional *** exhibit two concrete examples in this work,one is a two-level toys model,which has nontrivial Berry phases;the other is the generalized Su-Schrieffer-Heeger(SSH)model that has physical loss and gain in every *** results explicitly demonstrate the relation between complex Berry phases,topology and PT-symmetry breaking and enrich the field of the non-Hermitian physics.

关键词： PT symmetry Berry phases topology PT symmetry breaking

A field study of advanced municipal wastewater treatment technology for artificial groundwater recharge

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Journal of Environmental Sciences 2006年第6期18卷 1056-1060页

作者： pi Yun-zheng WANG Jian-long Laboratory of Environmental Technology Institute of Nuclear and New Energy Tsinghua University Beijing 100084 China

Field studies were conducted to investigate the advanced treatment of the municipal secondary effluent and a subsequent artificial groundwater recharge at Gaobeidian Wastewater Treatment Plant, Beijing. To improve the secondary effluent quality, the combined process of powdered activated carbon adsorption, flocculation and rapid sand filtration was applied, which could remove about 400 dissolved organic carbon （DOC） and 70% adsorbable organic halogens. The results of liquid size exclusion chromatography indicate that in the adsorption unit the removed organic fraction was mainly low molecular weight compounds. The fractions removed by the flocculation unit were polysaccharides and high molecular weight compounds. The retention of water in summer in the open recharge basins resulted in a growth of algae. Consequently, DOC increased in the polysaccharide and high molecular weight humic substances fraction. The majority of the DOC removal during soil passage took place in the unsaturated area. A limited reduction of DOC was observed in the aquifer zone.

关键词： artificial groundwater recharge soil aquifer treatment dissolved organic carbon

The Stability of Imitation Dynamics with Continuously Distributed Delays

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Journal of Systems Science & Complexity 2023年第5期36卷 2067-2081页

作者： FANG Caiya YANG Hui pi Jinxiu WU Wenjun School of Mathematics and Statistics Guizhou UniversityGuizhou 550025China Guizhou Provincial Key Laboratory for Games Decision Making and Control SystemsGuiyang 550025China

This paper investigates imitation dynamics with continuously distributed *** realistic technological,economic,and social environments,individuals are involved in strategic interactions simultaneously while the influences of their decision-making may not be observable *** shows that there exists a time delay *** distributions of delay are further considered to efficiently lucubrate the stability of interior equilibrium in the imitation dynamics with continuous distributions of delay in the two-strategy game ***,when the delay follows the uniform distributions and Gamma distributions,the authors present that interior equilibrium can be asymptotically ***,when the probability density of the delay is general density,the authors also determine a sufficient condition for stability derived from the expected *** but not least,the interested but uncomplicated Snowdrift game is utilized to demonstrate our theoretical results.

关键词： Continuous distributed delay evolutionary games imitation dynamics stability

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Nursing care in old patients with heart failure： current status and future perspectives

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Journal of Geriatric Cardiology 2016年第5期13卷 387-390页

作者： Hong-Ying pi Xin HU Nursing Department Chinese PLA General Hospital Beijing China Vasculocardiology Department Chinese PLA General Hospital Beijing China

The prognosis of heart failure （HF） patients has significantly improved in the last 20 years, given the advent of therapies such as angiotensin-converting enzyme （ACE） inhibitors/angiotensin receptor blockers （ARBs）, beta-block- ers, and implantable cardioverter-defibrillator （ICD）/cardiac resynchronization therapy devices （CRT）. In addition to these promising therapies, proper nursing-care is also important. Here we summarize recent progress of nursing-care strategies in older HF patients, including routine nursing care, transitional care model, self-care, and role of exercise training in old patients with HF.

关键词： Heart failure Nursing care Tai Chi The elderly