检索结果-南通市图书馆

Recent progress in fingerprint recognition

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Progress in Natural science:Materials International 2006年第3期16卷 231-240页

作者： TIAN Jie, CHEN Xinjian, ZHANG Yangyang, YANG Xin, HE Yuliang, LI Liang, XIE Weihua and ZHENG Zhipeng (Center for biometrics and Security Research, Key Laboratory of Complex Systems and Intelligence science, Institute of Automation, chinese academy of sciences, beijing 100080, China graduate school of the chinese academy of sciences, beijing 100080, China) [a]Center for biometrics and Security Research Key Laboratory of Complex Systems and Intelligence Science Institute of Automation Chinese Academy of Sciences Beijing China [b]graduate school of the chinese academy of sciences Beijing China

Fingerprint recognition has been increasingly used to realize personal identification in civilian' s daily life, such as ID card, fingerprints hard disk and so on. Great improvement has been achieved in the on-line fingerprint sensing technology and automatic fingerprint recognition algorithms. Various fingerprint recognition techniques, including fingerprint acquisition, classification, enhancement and matching, are highly improved. This paper overviews recent advances in fingerprint recognition and summarizes the algorithm proposed for every step with special focuses on the enhancement of low-quality fingerprints and the matching of the distorted fingerprint images. both issues are believed to be significant and challenging tasks. In addition, we also discuss the common evaluation for the fingerprint recognition algorithm of the Fingerprint Verification Competition 2004 (FVC2004) and the Fingerprint Vendor Technology Evaluation 2003 (FpVTE2003), based on which we could measure the performance of the recognition algorithm objectively and uniformly.

关键词： biometrics fingerprint enhancement matching minutia image registration similarity measures.

Suprathermal particle events observed by WIND spacecraft in interplanetary space during 1995―1999 and their classification

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

science China(Technological sciences) 2008年第9期51卷 1542-1553页

作者： SUN LingPeng1,2, WU DeJin1 & WANG DeYu1 1 Purple Mountain Observatory, chinese academy of sciences, Nanjing 210008, China 2 graduate school of chinese academy of sciences, beijing 100049, China Purple Mountain Observatory Chinese Academy of Sciences Nanjing 210008 China graduate school of chinese academy of sciences Beijing 100049 China

Fifty-five suprathermal particle events were selected from WIND observations between 1995 and 1999. based on systematic analysis on the observational characteristics of these events a two-parameter (the rising time and the flux ratio of electrons to protons in each event) classification method was proposed to classify these events. The three clas-sified classes are (1) impulsive electron events with the flux ratio of electrons to protons being bigger than 1 and rising time being shorter than 200 min, (2) impulsive proton events with the flux ratio being smaller than 1 and rising time being shorter than 200 min, and (3) gradual proton events with the flux ratio being smaller than 1 and the rising time being longer than 200 min. In the past, "impulsive solar electron events" were under in-tense research. However, because the selection standards of their velocity dispersions or pitch-angle distributions were inadequate, statistical surveys of selected events were dif-ferent from each other and even some conclusions were not consistent with the theory, for example, the relation of type-III solar radio bursts to the "impulsive solar electron events". The first class of impulsive electron events are associated with type-III radio bursts and with clear velocity dispersions; therefore they ought to originate from the Sun. The second class of the events, which have short continuance time and usually are not associated with type-III radio bursts and without velocity dispersion, are still far away from inter-planetary shocks and most of them do not one-to-one correspond to corrotating interact-ing regions (CIRs); such events are possible results of local interplanetary magnetic field reconnection or electromagnetic disturbances. Finally, about 2/3 gradual proton events of the third class occur with interplanetary shocks, the delay times of which are almost equal to the rising time. Some of these events can be understood as particle accelerations by shocks.

关键词： suprathermal particles solar wind plasma solar eruptive activity interplanetary active regions

维普期刊数据库

Quasi-secure quantum dialogue using single photons

在线全文

学校读者我要写书评

暂无评论

science China(Physics,Mechanics & Astronomy) 2007年第5期50卷 558-562页

作者： YANG YuGuang1,2 & WEN QiaoYan31 College of Computer science and Technology, beijing University of Technology, beijing 100022, China 2 State Key Laboratory of Information Security, graduate University of the chinese academy of sciences, beijing 100049, China 3 school of science, beijing University of Posts and Telecommunications, beijing 100876, China College of Computer science Technology Beijing University of Technology Beijing 100022 China State Key Laboratory of Information Security Graduate University of the Chinese Academy of Sciences Beijing 100049 China school of science Beijing University of Posts Telecommunications Beijing 100876 China

A quasi-secure quantum dialogue protocol using single photons was proposed. Different from the previous entanglement-based protocols, the present protocol uses batches of single photons which run back and forth between the two parties. A round run for each photon makes the two parties each obtain a classical bit of information. So the efficiency of information transmission can be increased. The present scheme is practical and well within the present-day technology.

关键词： quantum dialogue, single photon, quantum secure direct communication

维普期刊数据库

Early ERP effects on the scaling of spatial attention in visual search

在线全文

学校读者我要写书评

暂无评论

Progress in Natural science:Materials International 2008年第4期18卷 381-386页

作者： Ya-Nan Niu a,b, Jing-Han Wei a, Yue-Jia Luo a,c, a Institute of Psychology, chinese academy of sciences, beijing 100101, China b graduate school of chinese academy of sciences, beijing 100049, China c State Key Laboratory of Cognitive Neuroscience and Learning, beijing Normal University, 19 Xin-wai Avenue, beijing 100875, China Institute of Psychology Chinese Academy of Sciences Beijing 100101 China graduate school of chinese academy of sciences Beijing 100049 China State Key Laboratory of Cognitive Neuroscience and Learning Beijing Normal University 19 Xin-wai Avenue Beijing 100875 China

This article describes the examination of the spatial ’scaling’ effect of visual attention with the technique of event-related potential (ERP). Eighteen participants were involved in a visual search task in which the cue-target paradigm was used. The search array was three concentric circles consisting of randomly selected English letters that were equally distributed in each circle. The behavioral and ERP data were recorded, respectively. The behavioral results showed that the response time increased and the response accuracy decreased with the increase of precue size. The ERPs amplitude of P1 and N1 components evoked by search array increased with the reduction of precue size. However, the latencies of these ERP components did not show significant differences between conditions. The hierarchical data of both behavioral assessment and ERPs provided evidence for the spatial ’scaling’ effect of visual attention. The amplitudes of P1 and N1 components may be used as indices to examine the effect of spatial ’scaling’. In different tasks, the display-set size of stimuli and the task complexity may be important factors that affect the attention allocation.

关键词： Visual search Spatial attention ‘Scaling’ effect Event-related potential

Reconstruction of temperature series in China for the last 5000 years

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Progress in Natural science:Materials International 2006年第8期16卷 838-845页

作者： GE Quansheng, WANG Shunbing and ZHENG Jingyun (Institute of Geographical sciences and Natural Resources Research, chinese academy of sciences, beijing 100101, China graduate school of the chinese academy of sciences, beijing 100039, China) [a]chinese academy of sciences Institute of Geographical Sciences and Natural Resources Research Beijing China [b]graduate school of the chinese academy of sciences Beijing China

A temperature series with a 100 year resolution for the last 5000 years in China has been reconstructed by using 31 longterm temperature proxy series selected from recent publications in the last 20 years. The proxy records include pollens, stalagmites, lake-sediments, peat, ice cores and historical documents. The result reveals that in the millennial scale temperature variation it was warm in 3050-250 bC and it was cold in 250 bC-1950 AD. In the above two periods there were many stages of sub-scale temperature fluctuations. The result also shows an obvious temperature discrepancy on the century to multi-century scale between the Eastern Monsoon Region, the Qinghai-Tibet Region and the Northwestern Region in 2850 bC, 2350 bC, 1350 bC, 950-350 bC, 50-250 AD, and 550 AD. A comparison between the reconstructed series of this paper and some North Hemisphere temperature series indicates that in the longterm scale change, the temperature change in China is in phrase with that of the Northern Hemisphere during the last 5000 years, while on the century to multi-century scale there are differences at the beginning and end times, which may imply that temperature change does not occur simultaneously in different regions.

关键词： temperature series the last 5000 years China.

Elemental and isotopic compositions of the hydrothermal sulfide on the East Pacific Rise near 13°N

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

science China Earth sciences 2010年第2期53卷 253-266页

作者： ZENG ZhiGang1,CHEN DaiGeng1,2,YIN Xuebo1,WANG XiaoYuan1,ZHANG GuoLiang1,2 & WANG XiaoMei1,2 1 Seafloor Hydrothermal Activity Laboratory of the Key Laboratory of Marine Geology and Environment,Institute of Oceanology,chinese academy of sciences,Qingdao 266071,China 2 graduate school of chinese academy of sciences,beijing 100049,China 1. Seafloor Hydrothermal Activity Laboratory of the Key Laboratory of Marine Geology and Environment Institute of Oceanology Chinese Academy of Sciences Qingdao 266071 China2. Graduate School of Chinese Academy of Sciences Beijing 100049 China

The mineralogical,elemental,and isotopic characteristics of a hydrothermal sulfide sample from one dredge station (12°42.30’N,103°54.48’W,water depth 2655 m) on the East Pacific Rise near 13°N were *** hydrothermal sulfide was composed mainly of sphalerite,chalcopyrite,and pyrite and was a Zn-rich sulfide;in layer ep-s-1,goethite formed by secondary oxidation was *** concentrations of rare elements,such as Li (0.15×10-6-0.30×10-6),be (0.01×10-6-0.05×10-6),Zr (73.8×10-9-1344×10-9),Nb (8.14×10-9-64.7×10-9),Hf (2.54×10-9-28.0×10-9),and Ta (0.203×10-9-1.21×10-9),were far lower in the hydrothermal sulfide than in the ocean crust,whereas the content of Au was higher and the contents of Co,Ni,Sr,Cs,ba,bi,and U were *** correlations between Zn and Cr,Cd and Ga,Cu and P,P and In (R2 > 0.8) were positive,whereas those between Zn and Fe,Cu,and ba (R2 > 0.8) were distinctly *** low-temperature mineral assemblages to high-temperature mineral assemblages,the spatial distributions of dispersive and rare elements (***,Li,Cs) in the hydrothermal sulfide displayed corresponding *** variations observed in some elements (e.g.,Cd,Cs,P) are controlled by Zn,Fe,and Cu sulfides,*** weathering accounts for the enrichment of V,Mn,and rare earth elements (REE) in the henna sulfide-oxidation layer that bears the secondary oxide mineral,leading to identical REE patterns for this layer (ep-s-1) and *** weathering also distinctly affects the correlations between the element ratios of the hydrothermal *** high-temperature mineral assemblages to low-temperature mineral assemblages,Fe content and δ 34S value of the hydrothermal sulfide increase gradually,and Zn content and lead isotopic ratios decrease gradually on the contrary,which indicate the influences of seawater on elements and the sulfur and lead isotopic compositions enhance gradually during the formation of hydrothermal sulfides.

关键词： variation element isotopic composition hydrothermal sulfide East Pacific Rise 13oN

维普期刊数据库

Content-based similarity for 3D model retrieval and classification

在线全文

学校读者我要写书评

暂无评论

Progress in Natural science:Materials International 2009年第4期19卷 495-499页

作者： Ke Lüa, Ning He b, Jian Xue a a College of Computing & Communication Engineering, graduate University of chinese academy of sciences, Yuquan Road 19(A), beijing 100049, China b school of Mathematical science, Capital Normal University, beijing 100037, China [a]College of Computing & Communication Engineering Graduate University of Chinese Academy of Sciences Yuquan Road 19(A) Beijing 100049 China [b]School of Mathematical Science Capital Normal University Beijing 100037 China

With the rapid development of 3D digital shape information, content-based 3D model retrieval and classification has become an important research area. This paper presents a novel 3D model retrieval and classification algorithm. For feature representation, a method combining a distance histogram and moment invariants is proposed to improve the retrieval performance. The major advantage of using a distance histogram is its invariance to the transforms of scaling, translation and rotation. based on the premise that two similar objects should have high mutual information, the querying of 3D data should convey a great deal of information on the shape of the two objects, and so we propose a mutual information distance measurement to perform the similarity comparison of 3D objects. The proposed algorithm is tested with a 3D model retrieval and classification prototype, and the experimental evaluation demonstrates satisfactory retrieval results and classification accuracy.

关键词： 3D model Retrieval and classification Content-based 3D model retrieval Similarity comparison

Identification of novel SINEs from Cyprinidae and their evolutionary significance

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Progress in Natural science:Materials International 2007年第3期17卷 270-279页

作者： HAN Yawei, HE Slumping and CHEN Yiyu ( Institute of Hydrobiology, chinese academy of sciences, Wuhan 430072, China. graduate school, chinese academy of sciences, beijing 100039, China) [a]Institute of Hydrobiology Chinese Academy of Sciences Wuhan China [b]graduate school Chinese Academy of Sciences Beijing China

Short interspersed nuclear elements (SINEs) are widespread among eukaryotic genomes. They are repetitive DNA sequences that have been amplified by retrotransposition. In this study, a class of SINEs were isolated from the Opsariichthys bidens genome, and named Opsar. Sequence analysis confirmed that Opsar is a new class of typical SINEs derived from tRNA molecules. With the tRNA-derived region of Opsar and through bLASTN search, we further identified Zb-SINEs from the zebrafish genome, which includes two groups: Zb-SINE-A and Zb-SINE-b. The Zb-SINE-A. group comprises subfamilies of -Al--A5, and the Zb-SINE-b group is a dimer of the tRNA -derived region and shares a similar dimeric composition to Alu. Zb-SINEs are composed of three distinct regions: a 5’ end tRNA-derived region, a tRNA-unrelated region and a 3’ end AT-rich region. The flanking regions are AT rich. The average length of Zb-SINEs elements is about 340 bp. Zb-SINEs account for as much as 0.1 % of the whole zebrafish genome. About 70% of the Zb-SINEs are on chromosomes 11, 18, and 19. These Zb-SINEs were characterized by PCR and dot hybridization. The distribution pattern of Zb-SINEs in genome strongly supports the master genes model. The tRNA-derived regions of Opsar and Zb-SINEs were compared with the tRNAAla gene, and they showed 76% similarity, indicating that Opsar and Zb-SINEs originated from an inactive tRNA sequence or a tRNA -like sequence. In view of the evolutionary status of zebrafish in the Cyprinidae, we deduced that Zb-SINEs were a very old class of interspersed sequences.

关键词： short interspersed nuclear elements (SINEs) master gene model Opsar Zb-SINEs and Cyprinidae.

cDNA cloning, expression and antibacterial activity of lysozyme C in the blue shrimp (Litopenaeus stylirostris)

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Progress in Natural science:Materials International 2009年第7期19卷 837-844页

作者： Weijun Mai a,b, Chaoqun Hu a, a Applied Marine biology Laboratory, South China Sea Institute of Oceanology, science academy of China, Guangzhou 510301, China b graduate University of chinese academy of sciences, beijing 100049, China [a]Applied Marine biology Laboratory South China Sea Institute of Oceanology Science Academy of China Guangzhou 510301 China [b]Graduate University of Chinese Academy of Sciences Beijing 100049 China

The gene coding for lysozyme in blue shrimp (Litopenaeus stylirostris) was cloned, sequenced and expressed in pET-32a vector. The deduced amino acid sequence of F. merguiensi lysozyme showed 37–93% similarity with the mouse, human, chicken, and tiger prawn counterparts. The lysozyme was purified to homogeneity and observed as a band of approximately 15 kDa in 15% SDS–PAGE. Semiquantitative RT-PCR analysis demonstrated that mRNA transcripts of lysozyme could be mainly detected in the tissues of haemocytes, gill, gonad and the lymphoid organ of unchallenged shrimps, whereas the expression of lysozyme transcripts was increased in all the tested tissues after the heat-killed Vibrio alginolyticus challenge. The temporal expression of lysozyme mRNA in haemolymph challenged by Micrococcus luteus and V. alginolyticus was both up-regulated and reached the maximum level at 8 and 16 h post-stimulation, respectively, and then dropped back to the original level. bacteriolytic activity of the lysozyme against different bacterial cultures was determined by the solid phase and turbidimetric assays. The results demonstrated that the lysozyme we obtained was not only against Grampositive and Gram-negative bacteria but also against shrimp pathogens V. alginolyticus and V. parahemolyticus. In addition, the study of the inhibition mechanism revealed that the antibacterial activity of the lysozyme was a result of the bactericidal effect.

关键词： Lysozyme C Litopenaeus stylirostris PCR-cloning Expression Antibacterial activity