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An iterative wavefront sensing algorithm for high-contrast imaging systems

Research in Astronomy and Astrophysics 2011年第2期11卷 198-204页

作者： Jiang-Pei Dou 1,2.De-Qing Ren 1,2.3 and Yong-Tian Zhu 1,2.1 National Astronomical Observatories/nanjing Institute of Astronomical Optics & technology,Chinese Academy of {2.s,nanjing 2.0042.china 2.Key Laboratory of Astronomical Optics & technology,nanjing Institute of Astronomical Optics & technology,Chinese Academy of {2.s,nanjing 2.0042.china 3 physics & Astronomy Department,California State University Northridge,18111 Nordhoff Street,Northridge,California 91330-82.8,USA National Astronomical Observatories / nanjing Institute of Astronomical Optics & technology Chinese Academy of Sciences Key Laboratory of Astronomical Optics & technology Nanjing Institute of Astronomical Optics & Technology Chinese Academy of Science

Wavefront sensing from multiple focal plane images is a promising technique for high-contrast imaging ***,the wavefront error of an optics system can be properly reconstructed only when it is very *** paper presents an iterative optimization algorithm for the direct measurement of large static wavefront errors from only one focal plane *** first measure the intensity of the pupil image to get the pupil function of the system and acquire the aberrated image on the focal plane with a phase error that will be *** we induce a dynamic phase on the tested pupil function and calculate the associated intensity of the reconstructed image on the focal *** algorithm will then try to minimize the intensity difference between the reconstructed image and the aberrated test image in the focal plane,where the induced phase is a variable of the optimization *** simulation shows that the wavefront of an optical system can theoretically be reconstructed with high precision,which indicates that such an iterative algorithm may be an effective way to perform wavefront sensing for high-contrast imaging systems.

关键词： techniques: image processing -- methods: numerical -- planetarysystems

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Molecular dynamics simulations on the structures and properties of ε-CL-2.-based PBXs ——Primary theoretical studies on HEDM formulation design

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science china Chemistry 2007年第6期50卷 737-745页

作者： XU XiaoJuan1,2. XIAO JiJun1, HUANG Hui3, LI JinShan3 & XIAO HeMing1 1 Department of Chemistry, nanjing University of science and {2., nanjing 2.0094, china 2.Department of Chemistry, Yancheng Teacher’s College, Yancheng 2.4002. china 3 Institute of Chemical Materials, china Academy of Engineering physics, Mianyang 62.900, china Department of Chemistry Nanjing University of Science and TechnologyNanjing 210094China Department of Chemistry Yancheng Teacher\'s CollegeYancheng 224002China Institute of Chemical Materials China Academy of Engineering PhysicsMianyang 621900

Five polymer bonded explosives(PBXs)with the base explosive epsilon-CL-2.(hexanitrohexaazaisowurtzi-tane),the most important high energy density compound(HEDC),and five polymer binders(Estane 5703,GAP,HTPB,PEG,and F_(2.14))were *** dynamics(MD)method was employed to investigate their binding energies(E_(bind))information and rules were reported for choosing better binders and guiding formulation design of high energy density material(HEDM).According to the calculated binding energies,the ordering of compatibility and stability of the five PBXs was predicted as epsilon-CL-2./PEG 2./ Estane5703 ≈ epsilon-CL-2./GAP 2./HTPB 2./F_(2.14).By pair correlation function g(r)analyses,hydrogen bonds and vdw are found to be the main interactions between the two *** elasticity and isotropy of PBXs based epsilon-CL-2. can be obviously improved more than pure epsilon-CL-2. *** is not by changing the molecular structures of epsilon-CL-2. for each binder to affect the *** safety and energetic properties of these PBXs are mainly influenced by the thermal capability(C_p^(deg))and density(p)of binders,respectively.

关键词： high energy density material (HEDM), hexanitrohexaazaisowurtzitane (CL-2.), polymer bonded explosives (PBXs), molecular dynamics (MD), compatibility, safety properties, mechanical properties, energetic properties

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Large-Eddy Simulations of turbulent flows with lattice Boltzmann dynamics and dynamical system sub-grid models

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science china(Technological sciences) 2009年第3期52卷 670-679页

作者： GUAN Hui1 & WU ChuiJie2.1 Research Center for Fluid Dynamics, PLA University of science and technology, {2. 2.1101, china 2.school of Aeronautics and Astronautics, Dalian University of technology, Dalian 11602., china Research Center for Fluid Dynamics PLA University of Science and Technology school of Aeronautics and Astronautics Dalian University of Technology

In this paper, two sub-grid scale (SGS) models are introduced into the Lattice Boltzmann Method (LBM), i.e., the dynamics SGS model and the dynamical system SGS model, and applied to numerically solving three-dimensional high Re turbulent cavity flows. Results are compared with those obtained from the Smagorinsky model and direct numerical simulation for the same cases. It is shown that the method with LBM dynamics SGS model has advantages of fast computation speed, suitable to simulate high Re turbulent flows. In addition, it can capture detailed fine structures of turbulent flow fields. The method with LBM dynamical system SGS model dose not contain any adjustable parameters, and can be used in simulations of various complicated turbulent flows to obtain correct information of sub-grid flow field, such as the backscatter of energy transportation between large and small scales. A new average method of eliminating the inherent unphysical oscillation of LBM is also given in the paper.

关键词： Large-Eddy Simulation Lattice Boltzmann Method dynamics sub-grid scale model dynamical system sub-grid scale model parallel computation

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Two-dimensional simulation of Poiseuille-Rayleigh-Bénard flows in binary fluids with Soret effect

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Progress in Natural science:Materials International 2007年第12期17卷 1389-1396页

作者： Hu Jun1 and Yin Xieyuan2.1. Institute of Applied physics and Computational mathematics, Beijing 100088, {2. 2. Department of Modern Mechanics, University of science and technology of {2., Hefei 2.002., {2.) Institute of Applied physics and Computational mathematics Beijing 100088 China Department of Modern Mechanics University of Science and Technology of China Hefei 230027 China

Poiseuille-Rayleigh-Bénard flows in binary fluids with Soret effect are directly simulated by a mixed finite element method. A temperature perturbation is used as an initial disturbed source for the basic parallel flows. The whole spatio-temporal evolution of the binary fluid flows is exhibited: initially only the disturbed mode with the wavenumber k=π is amplified while others are damped, and continuously the amplified mode grows further and the nonlinear effect becomes important; after a nonlinear evolution transition the flow system evolves finally into a periodic right traveling wave.

关键词： Poiseuille-Rayleigh-Bénard flow Soret effect through-flow.

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P2. traffic optimization

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science china({2. sciences) 2012年第7期55卷 1475-1492页

作者： ZHANG GuoQiang 1,2.,TANG MingDong 3 ,CHENG SuQi 2.4 ,ZHANG GuoQing 2.,SONG HaiBin 5 ,CAO JiGuang 6 & YANG Jing 7 1 school of Computer science and {2.,nanjing Normal University,nanjing 2.0046,china 2.Institute of Computing {2.,Chinese Academy of sciences,Beijing 100190,china 3.school of Computer science and Engineering,Hunan University of science and {2.,Xiangtan 4112.1,china 4 Graduate University of Chinese Academy of sciences,Beijing 100190,china 5 nanjing R&D Center,Huawei Technologies,nanjing 2.0012.china 6 china Academy of Telecommunication Research of MIIT,Beijing 100191,china 7 china Mobile Research Institute,Beijing 100053,china school of Computer science and {2. Nanjing Normal University Nanjing China Institute of Computing technology Chinese Academy of Sciences Beijing China school of Computer science and Engineering Hunan University of Science and Technology Xiangtan China Graduate University of Chinese Academy of sciences Beijing China nanjing R&D Center Huawei Technologies Nanjing China china Academy of Telecommunication Research of MIIT Beijing China china Mobile Research Institute Beijing China

Peer-to-peer (P2.) based content distribution systems have emerged as the main form for content distribution on the Internet,which can greatly reduce the distribution cost of content providers and improve the overall system ***,the mismatch between the overlay and underlay networks causes large volume of redundant traffic,which intensifies the tension between P2. content providers and ***,how to efficiently use network resources to reduce the traffic burden on the ISPs is crucial for the sustainable development of P2. *** paper surveys the state-of-art P2. traffic optimization technologies from three perspectives:P2. cache,locality-awareness and data *** details,comparison between these technologies and their applicabilities are presented,followed by a discussion of the issues that remain to be addressed and the direction of future content distribution research.

关键词： P2. traffic localization P2. traffic optimization P2. cache locality-awareness network coding content-centric network

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Interhemispheric atmospheric mass oscillation and its relation to interannual variations of the Asian monsoon in boreal summer

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science china Earth sciences 2010年第9期53卷 1343-1350页

作者： LU ChuHan, GUAN ZhaoYong & CAI JiaXi Key Laboratory of Meteorological Disaster of Ministry of Education and College of Atmospheric sciences, nanjing University of {2. science & technology, nanjing 2.0044, china Key Laboratory of Meteorological Disaster of Ministry of Education and College of Atmospheric sciences Nanjing University of Information Science & Technology Nanjing China

Using NCEP/NCAR reanalysis and precipitation records of Chinese stations, we have investigated the relationship of interhemispheric oscillation of air mass (IHO) with global lower-level circulation and monsoon anomalies in boreal summer. Our results show that the summer IHO explains a greater portion of variance in the abnormal distribution of atmospheric mass over 30°S-60°N as well as the Antarctic. The IHO strongly correlates to the variations of sea level pressure (SLP) in these regions. It is shown that IHO has some influences on both atmospheric mass transports and water vapor fluxes over 30°S-60°N in association with three anomalous cyclonic circulations over land areas of the eastern hemisphere, which is in close relation to the changes in summer monsoon intensity in eastern Asia and western Africa. Composites of summer rainfall anomalies in china for high and low IHO-index years indicate that the eastern Asian summer monsoon is more intense, with positive precipitation anomaly centers in northern and northeastern parts of china, as opposed to the negative center over the mid-lower reaches of the Yangtze River (MLRYR) in stronger IHO years. In weak IHO years, a feeble summer monsoon appears in eastern Asia, leading to positive center of precipitation anomalies displaced into the MLRYR. Furthermore, a teleconnection in wind fields between the western African and eastern Asian monsoon regions was observed in the middle and higher troposphere in the scenario of IHO. The anomalous cyclonic (anticyclonic) circulations along the path of this Africa-East Asia teleconnection were found to be just over the diabatic heating (cooling) centers, suggesting that diabatic forcings are responsible for the formation of this Africa-East Asia teleconnection.

关键词： interhemispheric oscillation Asian monsoon precipitation china boreal summer

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Electron surfing acceleration in a current sheet of flares

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science china({2.,Mechanics & Astronomy) 2009年第11期52卷 1810-1812页

作者： WANG DeYu1 & LU QuanMing2.1 Purple Mountain Observatory, nanjing 2.0008, china 2.{2. of Earth and Space sciences, University of science and technology of china, Hefei 2.002., china Purple Mountain Observatory Nanjing China school of Earth and Space sciences University of Science and Technology of China Hefei China

A model of electron acceleration in a current sheet of flares is studied by the analytical approximation solution and the test particle simulation. The electron can be trapped in a potential of propagating electrostatic wave. The trapped electron moving with the phase velocity v p of wave may be effectively accelerated by ev p/c × B z force along the outflow direction in the current sheet, if a criterion condition K > 0 for electron surfing acceleration is satisfied. The electron will be accelerated continuously until the electron de-trap from the wave potential at the turning point S.

关键词： electron acceleration electrostatic wave current sheet

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Contourlet HMT model with directional feature

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science china({2. sciences) 2012年第7期55卷 1563-1578页

作者： WANG XiangHai 1,2.3 ,CHEN MingYing 1 ,SONG ChuanMing 1,2.,XU MengChun 1 & FANG LingLing 3 1 College of Computer and information technology,Liaoning Normal University,Dalian 11602.,{2. 2.State Key Laboratory for Novel Software technology,nanjing University,nanjing 2.0093,{2. 3 Provincial Key Laboratory for Computer information Processing technology,Soochow University,Suzhou 2.5006,{2. College of Computer and information technology Liaoning Normal University Dalian China State Key Laboratory for Novel Software technology Nanjing University Nanjing China Provincial Key Laboratory for Computer information Processing technology Soochow University Suzhou China

According to Shanno's information theory,the directional feature of texture is defined as the value of directional variable when an image signal attains a singularity of random *** terms of this definition,we calculate the texture's directional features using Tamura's method and study the directional probability distribution of Contourlet *** we find that the directional features tend to be conveyed across parent and child *** on this conclusion,we establish a novel probability distribution model of hidden direction variables under the condition of hidden state variable's distribution,named Contourlet HMT model with directional *** structure and training method of the model are presented as ***,an unsupervised context-based image segmentation algorithm is proposed on the basis of the proposed *** effectiveness is verified via extensive experiments carried out on several synthesized images and remote sensing images.

关键词： directional feature Contourlet HMT Contourlet HMT with directional feature unsupervised texture segmentation

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Asymptotic SEP of MIMO beamforming in two-hop AF relaying systems

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science china({2. sciences) 2012年第2期55卷 377-383页

作者： FU YouHua1,HAN YuJie2.YANG LvXi2.ZHU WeiPing3 & LIU Chen1 1school of Electronic science and Engineering,{2. University of Posts and Telecommunications,{2. 2.0003,china 2.0} of information science and Engineering,Southeast University,{2. 2.0096,china 3Department of Electrical and Computer Engineering,Concordia University,Montreal H3G 1M8,Canada school of Electronic science and Engineering Nanjing University of Posts and Telecommunications school of information {2. and Engineering Southeast University

This paper derives an asymptotic average symbol error probability(SEP)expression for multiple-input multiple-output(MIMO)two-hop amplify-and-forward(AF)relay systems with optimal *** analysis at high signal-to-noise ratio(SNR)quantifies the diversity order and array gain,which are valid for any antenna numbers of the terminals and arbitrary channel fading *** is also proved that the system performance is dominated by the relatively degraded one of the two-hop *** results based on the simple expressions provide valuable insights into the performance and practical design considerations of MIMO AF networks.

关键词： MIMO relay networks optimal beamforming symbol error probability(SEP) diversity order

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Distribution characteristics of terrestrial heat flow density in Jiyang depression of Shengli Oilfield, East china

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science china Earth sciences 2004年第9期47卷 804-812页

作者： GONG Yuling1,2. WANG Liangshu1, LIU Shaowen1, LI Cheng1, HAN Yongbing1, LI Hua1, LIU Bo1 & CAI Jingong3 1. Department of Earth sciences, nanjing University, nanjing 2.0093, china 2. Department of Exploration and information technology of East china Institute of technology, Fuzhou 344000, china 3. Earth science Institution of Shengli Oilfield, Dongying 2.7015, china Department of Earth sciences Nanjing University Nanjing China Department of Exploration and information technology of East {2. Institute of technology Fuzhou China Earth science Institution of Shengli Oilfield Dongying China

Based on the geo-temperature data of 13 systematically continuous temperature log curves and 700 testing oil boreholes in Jiyang depression, Shengli Oilfield, and the measured thermal conductivities of 47 rock samples, the terrestrial heat flow densities of 114 boreholes of Jiyang depression and its surrounding areas are determined, including 13 of those data derived from systemically continuous temperature logging. The results show that Jiyang depression has a relatively high background heat flow with an average value (65.8 5.4) mW/m2. The lateral variation of heat flow in basin has negative correlation with basement depth. Moreover, heat flow of uplift areas with shallower basement is high, so are those of regions with volcanic rocks, and those of depression areas with deep basement are relatively low. The heat flow densities of different structural units of Jiyang depression can be summarized as follows: The average heat flow value of Zhanhua sag is (67.4 5.3) mW/m2. higher than that of the whole basin, that of Dongying sag is (66.0 6.1) mW/m2. and that of Chezhen sag is (65.1 3.7) mW/m2. It is apparent that these latter two values are approximate to the average value of the whole Jiyang depression, while the average value of Huimin sag is (63.65.0) mW/m2. lower than that of the whole basin. In fact, the basement depth and the distribution framework of uplift and depression areas are all controlled by the process of lithosphere extension. In addition, the distribution of volcanic rocks in basin is also relatively close to this extension geodynamic process. In summary, the distribution characteristics of terrestrial heat flow of Jiyang depression is determined by the Cenozoic tectono-thermal events of this region.

关键词： Jiyang depression, terrestrial heat flow, thermal conductivity.

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