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Study on NDVI-T_s space by combining LAI and evapotranspiration

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Science china Earth Sciences 2006年第7期49卷 747-754页

作者： HAN Lijuan1,2,3, WANG Pengxin4. YANG Hua1,2,3, LIU Shaomin1,2,3 & WANG Jindi1,2,3 1. Research Center for Remote Sensing and GIS, School of Geography, beijing Normal university, beijing 100875, china 2. State Key Laboratory of Remote Sensing Science, beijing 100875, china 3. beijing Key Laboratory for Remote Sensing of Environment and Digital Cities, beijing 100875, china 4. department of information management, college of information and electronic engineering, china agricultural university, beijing 100083. china 1. Research Center for Remote Sensing and GIS School of Geography Beijing Normal University Beijing 100875 China 2. State Key Laboratory of Remote Sensing Science Beijing 100875 China 3. beijing Key Laboratory for Remote Sensing of Environment and Digital Cities Beijing 100875 China 4. department of information management College of Information and Electronic Engineering China Agricultural University Beijing 100083 China

This paper focuses on interpreting the different spatial relationships between NDVI and Ts, a triangular or a trapezoid, and on analyzing transformation conditions, the physical and ecological meanings of the vegetation index-surface temperature space as well. Further, we use the Tempera-ture-Vegetation Dryness Index (TVDI) to explain the existent meaning of a triangular space after NDVI reaches its saturated state by employing the relationships between NDVI, LAI and evapotranspiration. The specific relations between NDVI and Ts are useful for describing, validating and updating land surface models.

关键词： NDVI, land surface temperature, evapotranspiration, leave area index.

A fast stereoscopic video coding algorithm based on JMVM

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Science china(information Sciences) 2011年第6期54卷 1218-1226页

作者： DENG ZhiPin 1,2 , JIA KeBin 1 , CHAN YuiLam 2 , FU ChangHong 2 & SIU WanChi 2 1 department of electronic information & Control engineering, {4. university of Technology, {4. 100124. china 2 department of electronic information engineering, Hong Kong Polytechnic university, Hong Kong, china 1. department of electronic information & Control engineering Beijing University of Technology Beijing 100124 China2. Department of Electronic Information Engineering Hong Kong Polytechnic University Hong Kong China

In order to exploit the intra-view and inter-view dependencies in stereo video coding, a fast joint motion and disparity estimation algorithm is proposed in this paper. An efficient search strategy based on the motion-disparity constraint is developed, in which both the motion and disparity vectors can be obtained simultaneously with low complexity. Moreover, a credible initial predictive vector set is designed with the aid of the temporal and spatial neighboring blocks so that the coding efficiency can be further enhanced. The experimental results demonstrate that the proposed algorithm can reduce more than 96% coding time compared with the JMVM full search with a negligible quality drop.

关键词： H.264 stereoscopic video coding disparity estimation motion estimation

electronic structure and magnetism of Fe-doped SiC nanotubes

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Science china(Physics,Mechanics & Astronomy) 2010年第9期53卷 1582-1589页

作者： ZHANG WeiHu1,2,3,ZHANG FuChun3,ZHANG ZhiYong4.LU ShuYuan5 & YANG YanNing3 1 Xi’an Institute of Optics and Precision Mechanics,Chinese Academy of Sciences,Xi’an 710068,china 2 Graduate university of Chinese Academy of Sciences,beijing 10004.,china 3 {4. of Physics and electronic information,Yan’an university,Yan’an 716000,china 4.information Science and Technology Institution,Northwest university,Xi’an 710127,china 5 department of Telecommunications,Xi’an Institute of Posts and Telecommunications,Xi’an 710121,china 1. Xi’an Institute of Optics and Precision Mechanics Chinese Academy of Sciences Xi’an 710068 China2. Graduate University of Chinese Academy of Sciences Beijing 100049 China3. College of Physics and Electronic Information Yan’an University Yan’an 716000 China4. Information Science and Technology Institution Northwest University Xi’an 710127 China5. Department of Telecommunications Xi’an Institute of Posts and Telecommunications Xi’an 710121 China

The electronic structure and magnetic properties of Fe-doped SiC nanotubes are investigated by using the first-principles method based on density functional theory(DFT) in the local spin density approximation(LSDA).The calculation results indicate that the SiC nanotube of Fe substitution for C exhibits antiferromagnetism while ferromagnetism features prominently when Fe substitutes *** is a kind of half-metal magnetic *** formation energy calculation results show that the formation energy of ferromagnetic structure is 3.2 eV lower than that of antiferromagnetic *** atoms are more likely to replace Si ***-orbit coupling induces electron spin polarization in the ground ***,the doping Fe atoms make relaxation towards the outside of the tube to some extent and larger geometric distortion occurs when Fe substitutes C,but the whole geometric structure of SiC nanotubes is not damaged due to the *** is revealed in the calculation of energy band structure and density of states that more dispersed distribution of energy levels is produced near the Fermi *** Fe substitution for Si,obviously there are spin-split and intense p-d hybrid effects by Si 3p electron spins and Fe 3d electron spins localized at the exchanging interactions between magnetic transitional metal(TM) *** electronic density results indicate that system magnetic moments are mainly generated by the unpaired 3d electrons of Fe *** these results show that the transition metal doping SiC nanotube could be a potential route to fabricating the promising magnetic materials.

关键词： SiC nanotube the first-principles doped magnetic properties

Sequence-based localization algorithm with improved correlation metric and dynamic centroid

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Science china(information Sciences) 2011年第11期54卷 2349-2358页

作者： YU Ying 1,JIANG ChunXiao 2,ZHAO XiaoJie 2,YUN LiJun 1,LI ZhiHua 2 & REN Yong 21 college of information,Yunnan Normal university,Kunming 650500,china 2 {4. of electronic engineering,Tsinghua university,beijing 100084.china 1. college of information Yunnan Normal University Kunming 650500 China2. Department of Electronic Engineering Tsinghua University Beijing 100084 China

Ecolocation (error controlling localization technique) is a novel sequence-based RF localization algorithm.A key feature of the Ecolocation algorithm is that it constructs a constraint table based on RSSI values and compares data between two ***,the definitions of the constraint and the centroid in the Ecolocation algorithm are imperfect,and result in poor localization *** improve the localization accuracy,a new algorithm based on weighted rank order correlation coefficient and dynamic centroid method is *** results indicate that compared with the Ecolocation,the localization accuracy and robustness of the new algorithm are distinctly raised.

关键词： WSNs (wireless sensor networks) localization sequences constraint table rank order correlation coefficient

Feature combination for classifying single-trial ECoG during motor imagery of different sessions

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Progress in Natural Science:Materials International 2007年第7期17卷 851-858页

作者： Wei Qingguo~(1,2) Meng Fei~1 Wang Yijun~1 Gao Xiaorong~1 Gao Shangkai~(1**) (1.department of Biomedical engineering,School of Medicine,Tsinghua university,beijing 100084.{4. 2.department of electronic engineering,School of information,Nanchang university,Nanchang 330029,{4.) [a]department of Biomedical engineering School of Medicine TsinghuaUniversity Beijing China [b]department of electronic engineering School of Information Nanchang University Nanchang China

The input signals of brain-computer interfaces(BCIs)may be either scalp electroencephalogram(EEG)or electrocor- ticogram(ECoG)recorded from subdural *** make BCIs practical,the classifiers for discriminating different brain states must have the ability of session-to-session *** paper proposes an algorithm for classifying single-trial ECoG during motor imagery of different *** features,derived from two physiological phenomena,movement-related potentials(MRP)and event-related desynchronization(ERD),and extracted by common spatial subspace decomposition(CSSD)and waveform mean,are combined to per- form classification *** specific signal processing methods utilized are described in *** algorithm was successfully applied to Data SetⅠof BCI CompetitionⅢ,and achieved a classification accuracy of 91% on test set.

关键词： brain-computer interface(BCI) electrocorticogram(ECoG) session-to-session transfer feature combination movement-related potentials(MRP) event-related desynchronization(ERD)

Building a next generation Internet with source address validation architecture

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Science in china(Series F) 2008年第11期51卷 1681-1691页

作者： WU JianPing1,3,REN Gang1,3 & LI Xing2,3 1 department of Computer Science,Tsinghua university,beijing 100084.china 2 department of electronic engineering,Tsinghua university,beijing 100084.china 3 Tsinghua National Laboratory for information Science and Technology(TNList) ,beijing 100084.china department of Computer Science Tsinghua University Beijing 100084 China department of electronic engineering Tsinghua University Beijing 100084 China Tsinghua National Laboratory for information Science and Technology (TNList) Beijing 100084 China

The IP packet forwarding of current Internet is mainly destination based. In the forwarding process, the source IP address is not checked in most *** causes serious security, management and accounting problems. Based on the drastically increased IPv6 address space, a ＂source address validation architecture＂（SAVA） is proposed in this paper, which can guarantee that every packet received and forwarded holds an authenticated source IP address. The design goals of the architecture are lightweight, loose coupling, ＂multi-fence support＂ and incremental deployment. This paper discusses the design and implementation for the architecture, including inter-AS, intra-AS and local subnet. The performance and scalability of SAVA are described. This architecture is deployed into the CNGI-CERNET2 infrastructure a large-scale native IPv6 backbone network of the china Next Generation Internet project. We believe that the SAVA will help the transition to a new, more secure and dependable Internet.

关键词： IP source address validation network architecture network security

Mapping and overlapping based carrier frequency searching technique for rapid GNSS long PN-code acquisition

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Science china(information Sciences) 2010年第12期53卷 2642-2652页

作者： LI Hong ,LU MingQuan & FENG ZhenMing department of electronic engineering,Tsinghua university,{4. 100084.china 1. department of electronic engineering Tsinghua University Beijing 100084 China

In global navigation satellite systems(GNSS),because of the long period and high chip rate of long pseudo-noise(PN) code,the rapid acquisition is hard to *** speed up search process,in the paper,a mapping and overlapping based carrier frequency searching technique is *** mapping incoming signals of the same interval to different carrier frequency cells and overlapping together the mapped incoming signals that correspond to the same code phase,the technique reduces the number of the cells to be *** effect of the technique on detection and mean acquisition time performance is *** is shown that the technique reduces the cells to be searched and shortens mean acquisition time at the expense of degrading detection *** technique is fit to the previously published acquisition methods and is capable of improving their mean acquisition time *** and simulation results validate the analysis.

关键词： carrier frequency cells mapping overlapping acquisition performance

Computer simulation on reliability of retention index with FDG-PET and optimization of dual-time-point imaging protocol

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Progress in Natural Science:Materials International 2008年第8期18卷 931-937页

作者： Rui Jia a, Jing Bai a,*, Lingfeng Wenb,c, Dagan Fengb,c a department of Biomedical engineering, Tsinghua university, Room B209, Building of Medical Science, beijing 100084. {4. b School of information Technologies, university of Sydney, NSW 2006, Australia c department of electronic and information engineering, Hong Kong Polytechnic university, Hong Kong department of Biomedical engineering Tsinghua University Room B209 Building of Medical Science Beijing 100084 China School of information Technologies University of Sydney NSW 2006 Australia department of electronic and information engineering Hong Kong Polytechnic University Hong Kong

The inherent noise in positron emission tomography (PET) leads to the instability of quantitative indicators, which may affect the diagnostic accuracy for differentiating malignant and benign lesions in the management of lung cancer. In this paper, the reliability of retention index (RI) is systematically investigated by using computer simulation for the dual-time-point imaging protocol. The area under the receiver operating characteristic (ROC) curve is used to evaluate the optimal protocol. Results demonstrate that the reliability of RI is affected by several factors including noise level, lesion type, and imaging schedule. The RIs with small absolute values suffer from worse reliability than those larger ones. The results of ROC curves show that over delayed second scan cannot help to improve the diagnostic performance further, while an early first scan is expected. The method of optimization based on ROC analysis can be easily extended to comprise as many lesions as possible.

关键词： Reliability Retention index PET (positron emission tomography) Simulation ROC (receiver operating characteristic)

Simulation study on the efficiencies of MOET nucleus breeding schemes applying marker assisted selection in dairy cattle

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Science china(Life Sciences) 2009年第3期52卷 296-306页

作者： LUO WeiZhen,WANG YaChun & ZHANG Yuan department of Animal Genetics & Breeding,college of Animal Science and Technology,china agricultural {4.,beijing 100094.china 1. department of Animal Genetics & Breeding College of Animal Science and Technology China Agricultural University Beijing 100094 China

Advantages of breeding schemes using genetic marker information and/or multiple ovulation and embryo transfer(MOET) technology over the traditional approach were extensively evaluated through *** yield was the trait of interest and QTL was the genetic marker *** dairy cattle breeding scenarios were considered,i.e.,traditional progeny testing breeding scheme(denoted as STANPT),GASPT scheme including a pre-selection of young bulls entering progeny testing based on their own QTL information,MOETPT scheme using MOET technology to generate young bulls and a selection of young bulls limited within the full-sib family,GAMOPT scheme adopting both QTL pre-selection and MOET technology,COMBPT scheme using a mixed linear model which considered QTL genotype instead of the BLUP model in GAMOPT,and three non-progeny testing schemes,*** MOET,GAMO and COMB schemes,corresponding to MOETPT,GAMOPT and COMBPT with progeny testing being part of the *** were selected based on their breeding value which was estimated under an animal model *** selection over 17 years was performed in the simulations and 30 replicates were designed for each *** influences of using QTL information and MOET technology on favorable QTL allele frequency,true breeding values,polygenetic breeding values and the accumulated genetic superiority were extensively evaluated,for five different populations including active sires,lactating cows,bull dams,bull sires,and young *** results showed that the combined schemes significantly outperformed other approaches wherein accumulated true breeding value *** difference between schemes exclusively using QTL information or MOET technology was not *** STANPT scheme was the least efficient among the 8 *** schemes using MOET technology had a higher polygenetic response than others in the 17th *** increases of frequency of the favorable QTL allele varied more greatly across t

关键词： dairy cattle marker-assisted selection two-stage selection MOET QTL