检索结果-南通市图书馆

Balanced multiple description subband coding based on multifilter banks

在线全文

学校读者我要写书评

暂无评论

Science china(Information sciences) 2011年第11期54卷 2359-2372页

作者： WANG Ning 1,LI BaoBin 2.& PENG LiZhong 1 1 LMAM,school of Mathematical sciences,Peking University,{2. 100871,china 2.school of Information Science and Engineering,graduate University of chinese academy of sciences,{2. 100190,china LMAM School of Mathematical Sciences Peking University school of Information Science and Engineering Graduate University of Chinese Academy of Sciences

Multiple description coding is one of the source coding techniques to alleviate the problems of packet loss in *** encoder generates several different descriptions of the source and the decoder can produce a useful reconstruction with any received subset of these *** of the earlier works concentrated on redundancy and the average distortion of the single-description reconstructions,which is insufficient to describe the *** this paper,a metric of the coding system,balance eccentric modulus,is defined to evaluate the difference in quality between the individual *** the discrete wavelet transform becomes trivial polyphase transform when setting the balance eccentric modulus at zero,we introduce a multiwavelet based scheme ***,a sufficient condition for balanced multiwavelet based multiple description coding is presented.

关键词： multiple description coding rate-distortion theory balance eccentric modulus balanced multiwavelet multifilter bank

Effect of sediment resuspension on underwater light field in shallow lakes in the middle and lower reaches of the Yangtze River:A case study in Longgan Lake and Taihu Lake

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 2006年第z1期49卷 114-125页

作者： ZHANG Yunlin, QIN Boqiang, ZHU Guangwei, GAO Guang, LUO Liancong & CHEN Weimin Nanjing Institute of Geography & Limnology, chinese academy of {2., Nanjing 2.0008, china graduate school of chinese academy of {2., beijing 10003., china Nanjing Institute of Geography & Limnology Chinese Academy of Sciences Nanjing China graduate school of {2. academy of sciences Beijing China

Based on three continuous in situ underwater light field measurement under different wind waves conditions in Longgan Lake, Meiliang Bay of Taihu Lake in July 2.03 and littoral zone near TLLER in July 2.04, respectively, the effects of sediment resuspension caused by wind waves on PAR diffuse attenuation, absorption coefficients and euphotic depths are analyzed. In Longgan Lake, PAR diffuse attenuation coefficients during small, middle and large wind waves were 1.74, 2.02.and 2.45 m-1, respectively, and the corresponding PAR spectral diffuse attenuations ranged from 0.98 to 2.97, 1.34 to 3.95 and 1.80 to 5.40 m-1, respectively. In Meiliang Bay, PAR diffuse attenuation coefficients were 2.63, 3.72. 4.37 m-1 during small, middle and large wind waves. PAR diffuse attenuation coefficients increased by 41% and 66% from small to middle, large wind waves, respectively. Absorption coefficients integrated over the range of PAR of CDOM, phytoplankton were 0.2., 0.2. m-1; 0.76, 0.49 m-1, respectively during middle and large wind waves. Absorption coefficients integrated over the range of PAR of non-algal particulate matter and total suspended particulate matter increased from 0.94 to 1.73 m-1, and from 1.70 to 2.2. m-1, respectively during middle and large wind waves. Relative contributions of absorption coefficients of non-algal particulate matter to total absorption coefficient integrated over the range of PAR were 44.14%, 65.05%, respectively, during middle and large wind waves. PAR euphotic depths decreased by 0.40, 0.19, 0.2. m from middle to large wind waves in Longganhu Lake, Meliang Bay and littoral zone near TLLER. Significant correlations were found between transparency, PAR diffuse attenuation coefficients, euphotic depths and total suspended paniculate matter, wind velocity, wave height. Most significant correlations were found between transparency, PAR diffuse attenuation coefficients, euphotic depths and inorganic suspended paniculate matter but low correlations

关键词： shallow lake, Taihu Lake, diffuse attenuation coefficient, absorption coefficient, total suspended particulate matter.

BIFURCATION OF THE NORTH EQUATORIAL CURRENT DERIVED FROM ALTIMETRY IN THE PACIFIC OCEAN

在线全文

学校读者我要写书评

暂无评论

Journal of Hydrodynamics 2006年第5期18卷 620-626页

作者： WANG Qing-ye HU Dun-xin Institute of Oceanology Chinese Academy of Sciences Qingdao 266071 China graduate school of the {2. academy of sciences Beijing 100039 China

The gridded （1/3°＊1/3°） altimetry data from October 1992.through December 2.04 were analyzed to study the seasonal and interannual variabilities of the bifurcation of the North Equatorial Current （NEC） at the surface in the western North Pacific Ocean. Calculations show that on annual average the bifurcation occurs at about 13.4°N at the surface. The geostrophic flow derived from Sea Surface Height （SSH） data shows that the southernmost latitude of the NEC bifurcation at the surface is about 12.9°N in June and the northernmost latitude is about 14.1°N in December. Correlation analyses between the bifurcation latitude and the Southern Oscillation Index （SOl） suggest that the bifurcation latitude is highly correlated with the E1 Nino/Southern Oscillation （ENSO） events. During the E1 Nino years the bifurcation of the NEC takes place at higher latitudes and vice versa.

关键词： bifurcation of the North Equatorial Current altimetry data Pacific Ocean North Equatorial Current (NEC),E1 Nino/Southern Oscillation (ENSO) events

Report of Prionospio complex(Annelida:Polychaeta:Spio-nidae) from china's waters,with description of a new species

在线全文

学校读者我要写书评

暂无评论

Acta Oceanologica Sinica 2009年第1期28卷 116-127页

作者： ZHOU Jin LI Xinzheng Institute of Oceanology. Chinese Aeademy of Sciences Qingdao 266071 China graduate school Chinese Academy of Sciences Beijing 100039 China

Nine species of Prionospio complex are recorded from china＇s waters,including one new species and six newly recorded ***（Prionospio） pacifica ***.,is characterized by having first and forth pairs of branchiae pinnate,second and third pairs of apinnate,ventral crest on Setiger 9 and dorsal crests on Setigers *** kirrae（Wilson,1990）,Prionospio（Aquilaspio） convexa Imajima,1990,Prionospio（Minuspio） multibranchiata Berkeley,192.,Prionospio（Prionospio） bocki Sderstrm,192.,Prionospio（Prionospio） dubia Maciolek,1985 and Prionospio（Prionospio） paradisea Imajima,1990 are recorded for the first time from china＇s waters.

关键词： taxonomy Prionospio complex new species newly recorded species china's waters.

Genesis of ^(2.0)Th excess in basalts from mid-ocean ridges and ocean islands:Constraints from the global U-series isotope database and major and rare earth element geochemistry

在线全文

学校读者我要写书评

暂无评论

Science china Earth sciences 2010年第10期53卷 1486-1494页

作者： ZHANG GuoLiang1,2.& ZENG ZhiGang1 1 Key Laboratory of Marine Geology and Environment,Institute of Oceanology,chinese academy of {2.,Qingdao 2.6071,china 2.graduate University of chinese academy of {2.,beijing 100049,china Key Laboratory of Marine Geology and Environment Institute of Oceanology Chinese Academy of Sciences Qingdao China graduate University of chinese {2. of sciences Beijing China

Based on 2.0Th-2.8U disequilibrium and major element data from mid-ocean ridge basalts(MORBs) and ocean island basalts(OIBs),this study calculates mantle melting parameters,and thereby investigates the origin of 2.0Th excess.(2.0Th/2.8U) in global MORBs shows a positive correlation with Fe8,Po,Na8,and Fmelt(Fe8 and Na8 are FeO and Na2. contents respectively after correction for crustal fractionation relative to MgO = 8 wt%,Po=pressure of initial melting and Fmelt=degree of melt),while 2.0Th excess in OIBs has no obvious correlation with either initial mantle melting depth or the average degree of mantle ***,compared with the MORBs,higher(2.0Th/2.8U) in OIBs actually corresponds to a lower melting *** suggests that the 2.0Th excess in MORBs is controlled by mantle melting conditions,while the 2.0Th excess in OIBs is more likely related to the deep garnet *** vast majority of calculated initial melting pressures of MORBs with excess 2.0Th are between 1.0 and 2.5 GPa,which is consistent with the conclusion from experiments in recent years that DU>DTh for Al-clinopyroxene at pressures of >1.0 *** initial melting pressure of OIBs is 2.2.3.5 GPa(around the spinel-garnet transition zone),with their low excess 2.6Ra compared to MORBs also suggesting a deeper mantle ***,excess 2.0Th in MORBs and OIBs may be formed respectively in the spinel and garnet stability *** addition,there is no obvious correlation of K2./TiO2.with(2.0Th/2.8U) and initial melting pressure(Po) of MORBs,so it is proposed that the melting depth producing excess 2.0Th does not tap the spinel-garnet transition *** and MORBs in both(2.0Th/2.8U) vs.K2./TiO2.and(2.0Th/2.8U) *** plots fall in two distinct areas,indicating that the mineral phases which dominate their excess 2.0Th are ***/Yb-Ce curves of fast and slow ridge MORBs are similar,while,in comparison,the Ce/Yb-Ce curve for OIBs shows more influence from *** mechanism

关键词： excess 2.0Th clinopyroxene garnet spinel-lherzolite mid-ocean ridge ocean island

A formal model of fair exchange protocols

在线全文

学校读者我要写书评

暂无评论

Science in china(Series F) 2005年第4期48卷 499-512页

作者： QING Sihan1,2.3 & LI Gaicheng1,2.3 1. Engineering Research Center for Information Security Technology, Institute of Software, chinese Aca- demy of sciences, {2. 100080, china 2. {2. Zhongke Ansheng Corporation of Information Technology, {2. 100080, china 3. graduate school of the chinese academy of sciences,{12., china Engineering Research Center for Information Security Technology Institute of Software Chinese Aca- demy of Sciences beijing Zhongke Ansheng Corporation of Information Technology graduate school of the {2. academy of sciences

Based on the study of existing fair exchange protocols, this paper sets up an accurate formal model by stepwise refinement. In the process of refinement an unreliable channel is employed to simulate an attack behavior. The model provides a novel formal definition of exchanged items, and presents the formal goals for fairness, accountability, etc., reflecting the inherent requirements for fair exchange protocols across-the-board. In order to check, prove, and design fair exchange protocols effectively and efficiently, the model puts forward a novel property of abuse-freeness which applies to all fair exchange protocols, gives a formal definition for trust strand of the third party, and presents general criteria of designing a secure and effective fair exchange protocol. Taking a typical fair exchange protocol as an example, this paper presents the analysis steps of fair exchange protocols appealing to our model. An unknown attack is uncovered. The analysis reveals the process of a complete attack, discovering deeper reasons for causing an attack. Finally, we modify the flawed protocol and the revised protocol ensures the desirable properties.

关键词： events local causal relation local temporal relation global relation exchanged item security goals.

Autonomous satellite constellation orbit determination using the star sensor and inter-satellite links data

在线全文

学校读者我要写书评

暂无评论

Science china(Physics,Mechanics & Astronomy) 2010年第5期53卷 966-974页

作者： GAN QingBo1,2.MA JianBo1 & XU Jin1 1 Purple Mountain Observatory,chinese academy of {2.,Nanjing 2.0008,china 2.graduate University of chinese academy of {2.,beijing 100049,china chinese academy of {2. Purple Mountain Observatory Nanjing China (GRID:grid.9227.e) (ISNI:***) graduate University of chinese {2. of sciences Beijing China (GRID:grid.458514.9) chinese academy of {2. Purple Mountain Observatory Nanjing China (GRID:grid.9227.e) (ISNI:***)

A method of autonomous orbit determination for a satellite constellation using a star sensor combined with inter satellite links(ISLs) is *** types of simulated observation data,Three-Satellite Constellation ISLs and background stellar observations by a CCD star sensor,are first *** on these data,an observation equation is built for the constellation joint autonomous orbit determination,in which the simulations are *** accuracy of this method with different orbital determination models are analyzed and compared with regard to the effect of potential measurement *** results show that autonomous satellite constellation orbit determination using star sensor measurement and ISLs data is ***,this paper arrives at several conclusions which contribute to extending this method to a more general satellite constellation.

关键词： satellite constellation star sensor inter-satellite links autonomous orbit determination

BUD2.encoding an S-adenosylmethionine decarboxylase,is required for Arabidopsis growth and development

在线全文

学校读者我要写书评

暂无评论

Cell Research 2006年第5期16卷 446-456页

作者： Chunmin Ge~(1,2.*) Xia Cui~(1,2.*) Yonghong Wang~1 Yuxin Hu~3 Zhiming Fu~1 Dongfen Zhang~(1,2. Zhukuan Cheng~1 Jiayang Li~1 ~1State Key Laboratory of Plant Genomics and National Center for Plant Gene Research,Institute of Genetics and Developmental Biology,chinese academy of {2.,beijing 100101,china ~2.5} school,chinese academy of {2.,beijing 100101,china ~3Institute of Botany,chinese academy of {2.,beijing 100093,china State Key Laboratory of Plant Genomics and National Center for Plant Gene Research Institute of Genetics and Developmental Biology Chinese Academy of Sciences Beijing China graduate school Chinese Academy of Sciences Beijing China Institute of Botany Chinese Academy of Sciences Beijing China

Polyamines are implicated in regulating various developmental processes in plants,but their exact roles and how theygovern these processes still remain *** report here an Arabidopsis bushy and dwarf mutant,bud2.which resultsfrom the complete deletion of one member of the small gene family that encodes S-adenosylmethionine decarboxylases(SAMDCs) necessary for the formation of the indispensable intermediate in the polyamine biosynthetic ***2.plant has enlarged vascular systems in inflorescences,roots,and petioles,and an altered homeostasis *** double mutant of bud2.and samdcl,a knockdown mutant of another SAMDC member,is embryo lethal,demonstrat-ing that SAMDCs are essential for plant *** results suggest that polyamines are required for the normalgrowth and development of higher plants.

关键词： BUD2 polyamines embryogenesis plant architecture Arabidopsis

Research on Jiuquan-Jiayuguan-Yumen Region's Dynamic Changing of Urbanization Based on Self-Organizing Model

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

chinese Journal of Population,Resources and Environment 2005年第3期3卷 22-28页

作者： Li Ming 1,2.& Fang Chuanglin 2.1 graduate school of the {2. academy of sciences, beijing 10003.,china 2.Institute of Geographical sciences and Natural Resources Research, CAS, beijing 100101, china graduate school of the {2. academy of sciences Beijing 100039 China Institute of Geographical sciences and Natural Resources Research CAS Beijing 100101 China

Based on the self-organizing modeling principle in the dissipative structure theory, the paper regards the migration coupling between the regions as the influence factor to create the model of regional urbanization simulation and prediction, which is more practical to simulate the space-time and dynamic evolvement characteristics of regional urbanization level. According to the historical data about the population and urbanization of Jiuquan, Jiayuguan andYumen cities, the past 50 years' dynamic evolvement trend is simulated and the following 50 years' dynamic evolvement trend is predicted with the urbanization dynamic evolvement model based on the self-organizing model. The analysis of effective factors such as economic increase, resources exploitation, ecosystem construction, traffic location, national policies, population migration are given, then the reasons of the dynamic evolvement differences of the three cities' urbanization are drawn. The study suggests that the self-organizing model is fit for the simulation of Jiuquan-Jiayuguan-Yumen regional urbanization level in the past 50 years, and the departure between the stimulant and the actual data is under 5%, so it can be used to predict the urbanization future of the three cities. The predicted results show that the regional population will reach 1.074 million and the regional urbanization level will be 72.56%.

关键词： self-organizing urbanization dynamic evolvement Jiuquan-Jiayuguan-Yumen region