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A synthetic aperture radar sea surface distribution estimation by n-order Bézier curve and its application in ship detection

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Acta Oceanologica Sinica 2016年第9期35卷 117-125页

作者： LANG Haitao ZHANG Jie WANG Yiduo ZHANG Xi MENG Junmin School of Science Beijing University of Chemical Technology Jiangsu Key Laboratory of Big Data Analysis Technology/B-DAT Nanjing University of Information Science &Technology The First Institute of Oceanography State Oceanic Administration

To dates,most ship detection approaches for single-pol synthetic aperture radar（SAR） imagery try to ensure a constant false-alarm rate（CFAR）.A high performance ship detector relies on two key components：an accurate estimation to a sea surface distribution and a fine designed CFAR ***,a novel nonparametric sea surface distribution estimation method is developed based on n-order Bézier *** estimate the sea surface distribution using n-order Bézier curve,an explicit analytical solution is derived based on a least square optimization,and the optimal selection also is presented to two essential parameters,the order n of Bézier curve and the number m of sample ***,to validate the ship detection performance of the estimated sea surface distribution,the estimated sea surface distribution by n-order Bézier curve is combined with a cell averaging CFAR（CA-CFAR）.To eliminate the possible interfering ship targets in background window,an improved automatic censoring method is *** experiments prove that in terms of sea surface estimation performance,the proposed method is as good as a traditional nonparametric Parzen window kernel method,and in most cases,outperforms two widely used parametric methods,K and G0 *** terms of computation speed,a major advantage of the proposed estimation method is the time consuming only depended on the number m of sample points while independent of imagery size,which makes it can achieve a significant speed improvement to the Parzen window kernel method,and in some cases,it is even faster than two parametric *** terms of ship detection performance,the experiments show that the ship detector which constructed by the proposed sea surface distribution model and the given CA-CFAR algorithm has wide adaptability to different SAR sensors,resolutions and sea surface homogeneities and obtains a leading performance on the test dataset.

关键词： Bézier curve nonparametric method ship detection sea surface distribution synthetic aperture radar

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Structural insights into the assembly of the 30S ribosomal subunit in vivo： functional role of S5 and location of the 17S rRNA precursor sequence

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Protein & Cell 2014年第5期5卷 394-407页

作者： Zhixiu Yang Qiang Guo Simon Goto Yuling Chen Ningning Li Kaige Yan Yixiao Zhang Akira Muto Haiteng Deng Hyouta Himeno Jianlin Lei Ning Gao Ministry of education Key Laboratory of Protein Sciences Center for Structural Biology School of Life Sciences Tsinghua University Beijing 100084 China Department of-Biochemistry and Molecular Biology Faculty of Agriculture and Life Science Hirosaki University Hirosaki 036-8561 Japan

The in vivo assembly of ribosomal subunits is a highly complex process, with a tight coordination between protein assembly and rRNA maturation events, such as folding and processing of rRNA precursors, as well as modifications of selected bases. In the cell, a large number of factors are required to ensure the efficiency and fidelity of subunit production. Here we characterize the immature 30S subunits accumulated in a factor-null Escherichia coil strain （ArsgAArbfA）. The immature 30S subunits isolated with varying salt concentrations in the buffer system show interesting differences on both protein composition and structure. Specifically, inter- mediates derived under the two contrasting salt condi- tions （high and low） likely reflect two distinctive assembly stages, the relatively early and late stages of the 3＇ domain assembly, respectively. Detailed structural analysis demonstrates a mechanistic coupling between the maturation of the 5＇ end of the 17S rRNA and the assembly of the 30S head domain, and attributes a unique role of S5 in coordinating these two events. Furthermore, our structural results likely reveal thelocation of the unprocessed terminal sequences of the 17S rRNA, and suggest that the maturation events of the 17S rRNA could be employed as quality control mech- anisms on subunit production and protein translation.

关键词： RsgA RbfA ribosome assembly cryo-EM,quantitative mass spectrometry

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Endpoint Estimates for Marcinkiewicz Integrals on Weighted Weak Hardy Spaces

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Acta Mathematica Sinica,English Series 2015年第3期31卷 430-444页

作者： Yan LIN Mei XU School of Sciences China University of Mining and Technology

In this paper, we obtain the（W Hω^1, W Lω^1） type estimate for the Marcinkiewicz integral and the（W H1 b,ω, W L1ω） type estimate for the commutator generated by a BMO function and the Marcinkiewicz integral, w... 详细信息

关键词： μΩ boundedness kernel inequality logarithmic satisfying endpoint maximal Lebesgue proof

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Fabrication and characterization of anodic oxide nanotubes on TiNb alloys

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Rare Metals 2016年第2期35卷 140-148页

作者： Ming Jin Xin Lu Yi Qiao Lu-Ning Wang Alex A.Volinsky School of Materials Science and Engineering University of Science and Technology Beijing State Key Laboratory for Advanced Metals and Materials University of Science and Technology Beijing Department of Mechanical Engineering University of South Florida

Titanium and its alloys have been extensively used as implant materials owing to their high specific strength, good biocompatibility and excellent corrosion resistance. Oxide nanotubular array layer can be formed on Ti alloy surface by electrochemical anodization treatment. In this work, the morphology of nanotubes formed on Ti-Nb alloys（Nb content of 5 wt%, 10 wt%, 20 wt%, 30 wt% and40 wt%） was investigated using an electrolyte containing ethylene glycol and NH_4 F. Oxide layers consisting of highly ordered nanotubes with a range of diameters（approximately40-55 nm for the inner diameter and 100-120 nm for the outer diameter） and lengths（approximately 10-20 lm） can be formed on alloys in the Ti-x Nb system, independent on the Nb content. The nanotubes formed on the Ti-Nb alloy surface were transformed from the anatase to rutile structure of titanium oxide. The oxide nanotubular surface is highly hydrophilic compared with the intact Ti Nb foil. The surface wettability varies with the nanotube diameter. As the nanotube diameter increases while the nanotube layer thickness remains constant, the capillary wetting of the nanotube surface decreases and the surface becomes less *** changes the nanotubular surface wettability further and establishes less hydrophilic surface conditions due to the removal of hydroxyl groups and residue fluoridecontaining species. It is believed that the surface wettability is changed due to the decreasing content of hydroxyl groups in ambient atmosphere. This work can provide guidelines for improving structural and environmental conditions responsible for changing surface wettability of Ti Nb surfaces for biomedical applications.

关键词： Ti-Nb alloy Anodization Nanotubes Wettability Implants

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Free vibration of size-dependent magneto-electro-elastic nanoplates based on the nonlocal theory

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Acta Mechanica Sinica 2014年第4期30卷 516-525页

作者： Liao-Liang Ke Yue-Sheng Wang Jie Yang Sritawat Kitipornchai Institute of Engineering Mechanics Beijing Jiaotong University School of Civil Engineering The University of QueenslandSt Lucia QLD 4072 Australia School of Aerospace Mechanical and Manufacturing EngineeringRMIT University

In this paper, the free vibration of magneto- electro-elastic （MEE） nanoplates is investigated based on the nonlocal theory and Kirchhoff plate theory. The MEE nanoplate is assumed as all edges simply supported rectan gular plate subjected to the biaxial force, external electric potential, external magnetic potential, and temperature rise. By using the Hamilton＇s principle, the governing equations and boundary conditions are derived and then solved analytically to obtain the natural frequencies of MEE nanoplates. A parametric study is presented to examine the effect of the nonlocal parameter, thermo-magneto-electro-mechanical loadings and aspect ratio on the vibration characteristics of MEE nanoplates. It is found that the natural frequency is quite sensitive to the mechanical loading, electric loading and magnetic loading, while it is insensitive to the thermal loading.

关键词： Magneto-electro-elastic materials Nanoplates ·Nonlocal theory Vibration

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Convection of Maxwell fluid over stretching porous surface with heat source/sink in presence of nanoparticles:Lie group analysis

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Applied Mathematics and Mechanics(English Edition) 2016年第4期37卷 433-442页

作者： Limei CAO Xinhui SI Liancun ZHENG Department of Applied Mathematics School of Mathematics and PhysicsUniversity of Science and Technology Beijing

The convection of a Maxwell fluid over a stretching porous surface with a heat source/sink in the presence of nanoparticles is investigated. The Lie symmetry group transformations are used to convert the boundary layer equations into coupled nonlinear ordinary differential equations. The ordinary differential equations are solved numerically by the Bvp4c with MATLAB, which is a collocation method equivalent to the fourth-order mono-implicit Runge-Kutta method. Furthermore, more attention is paid to the effects of the physical parameters, especially the parameters related to nanoparticles, on the temperature and concentration distributions with consideration of permeability and the heat source/sink.

关键词： Lie group Maxwell fluid porous stretching surface heat sink or source

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Local discrimination scheme for some unitary operations

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Science China(Physics,Mechanics & Astronomy) 2016年第9期59卷 39-45页

作者： TianQing Cao Fei Gao GuoJing Tian ShuCui Xie QiaoYan Wen State Key Laboratory of Networking and Switching Technology Beijing University of Posts and TelecommunicationsBeijing 100876China State Key Laboratory of Cryptology Beijing 100878China School of Science Xi'an University of Posts and TelecommunicationsXi'an 710121China

It has been shown that for two different multipartite unitary operations U_1 and U_2, when tr(U_1~?U_2) = 0, they can always be perfectly distinguished by local operations and classical communication in the single-run scenario. However, how to find the detailed scheme to complete the local discrimination is still a fascinating problem. In this paper, aiming at some U_1 and U_2 acting on the bipartite and tripartite space respectively, especially for U_1~?U_2 locally unitary equivalent to the high dimensional X-type hermitian unitary matrix V with trV = 0, we put forward the explicit local distinguishing schemes in the single-run scenario.

关键词： unitary operations local discrimination local numerical range

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Strenghening mechanism of graphene/Ni nanolayered composite nanowires under uniaxial compression

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Science China(Physics,Mechanics & Astronomy) 2016年第3期59卷 107-108页

作者： Zhen Yu Yang Jian Sun Zi Xing Lu Wen Jun Hu Institute of Solid Mechanics Beihang University Institute of Structure Mechanics China Academy of Engineering Physics

Dear Editors,Graphene exhibits excellent mechanical properties and at- tracts great attention and intensive study in applied physics and material science [1]. In particular, the extreme sur- face-to-volume ratio of graphene makes it possible to be an ideal reinforcement for nanocomposites. Over the past dec- ade, researchers have synthesized graphene-based nano- composites with superior mechanical properties [2]. Kim et al. [3] recently successfully fabricated Cu- and Ni- matrices nanolayered composites reinforced by only a single layer of graphene and the experiments showed that the strength of the composites can be highly enhanced. As a consequence, the strengthening mechanisms of graphene/metal nanolay- ered composites aroused great interest in recent years.

关键词：纳米线石墨压缩机制纳米复合单轴复合材料镍材料科学

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Minimum best success probability by classical strategies for quantum pseudo-telepathy

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Science China(Physics,Mechanics & Astronomy) 2014年第7期57卷 1244-1249页

作者： GAO Fei FANG Wei WEN QiaoYan State Key Laboratory of Networking and Switching Technology Beijing University of Posts and Telecommunications

Quantum pseudo-telepathy(QPT)is a new type of game where the quantum team can win with certainty while the classical one *** means the advantages of quantum participants over classical ones in ***,there has been no systematic and formal analysis on the QPT game *** we present the formal description of the QPT game and the definition of the most simplified *** on the above definitions,we simplify a famous QPT game,*** Cabllo ***,according to some instances,we analyze the minimum best success probability by classical strategies of the two-player QPT,which reflects the advantage of the quantum ***,we prove the best success probability by classical strategies for the most simplified QPT is totally related to the number of all possible question combinations.

关键词： quantum game pseudo-telepathy quantum strategy

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A survey on the security of cyber-physical systems

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Control Theory and Technology 2016年第1期14卷 2-10页

作者： Guangyu WU Jian SUN Jie CHEN School of Automation Beijing Institute of Technology Beijing 100081 China Key Laboratory of Intelligent Control and Decision of Complex Systems Beijing Institute of Technology Beijing 100081 China

Cyber-physical systems （CPSs） are integrations of computation, communication, control and physical processes. Typical examples where CPSs are deployed include smart grids, civil infrastructure, medical devices and manufacturing. Security is one of the most important issues that should be investigated in CPSs and hence has received much attention in recent years. This paper surveys recent results in this area and mainly focusses on three important categories： attack detection, attack design and secure estimation and control. We also discuss several future research directions including risk assessment, modeling of attacks and attacks design, counter-attack strategy and testbed and validation.

关键词： Security cyber-physical systems attack detection secure estimation and control

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