检索结果-南通市图书馆

Validating global hydrological models by ground and space gravimetry

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 Science Bulletin 2009年第9期54卷 1534-1542页

作者： ZHOU JiangCun1,2,3, SUN HePing1,2 & XU JianQiao1,2 1 Institute of Geodesy and Geophysics, chinese academy of sciences, Wuhan 430077, china 2 Key Laboratory of dynamic geodesy, chinese academy of sciences, Wuhan 430077, china 3 graduate University of chinese academy of sciences, beijing 100049, china Institute of Geodesy and Geophysics Chinese Academy of Sciences Wuhan 430077 China Key Laboratory of dynamic geodesy Chinese Academy of Sciences Wuhan 430077 China graduate University of chinese academy of sciences Beijing 100049 China

The long-term continuous gravity observations obtained by the superconducting gravimeters (SG) at seven globally-distributed stations are comprehensively analyzed. After removing the signals related to the Earth's tides and variations in the Earth's rotation, the gravity residuals are used to describe the seasonal fluctuations in gravity field. Meanwhile, the gravity changes due to the air pressure loading are theoretically modeled from the measurements of the local air pressure, and those due to land water and nontidal ocean loading are also calculated according to the corresponding numerical models. The numerical results show that the gravity changes due to both the air pressure and land water loading are as large as 100×10-9 m s-2 in magnitude, and about 10×10-9 m s-2 for those due to the nontidal ocean loading in the coastal area. On the other hand, the monthly-averaged gravity variations over the area surrounding the stations are derived from the spherical harmonic coefficients of the GRACE-recovered gravity fields, by using Gaussian smoothing technique in which the radius is set to be 600 km. Com-pared the land water induced gravity variations, the SG observations after removal of tides, polar mo-tion effects, air pressure and nontidal ocean loading effects and the GRACE-derived gravity variations with each other, it is inferred that both the ground- and space-based gravity observations can effec-tively detect the seasonal gravity variations with a magnitude of 100×10-9 m s-2 induced by the land water loading. This implies that high precision gravimetry is an effective technique to validate the re-liabilities of the hydrological models.

关键词：重力测量水文模型模型验证和空间地面重力变化季节性波动空气压力

Interannual variability of Antarctic Oscillation and its influence on East Asian climate during boreal winter and spring

在线全文

学校读者我要写书评

暂无评论

Science china Earth sciences 2006年第5期49卷 554-560页

作者： FAN Ke1,2,3 & WANG Huijun2 1. Nansen-Zhu International Research Center, Institute of Atmospheric Physics, chinese academy of sciences, beijing 100029, china 2. Department of Atmospheric Science, Yunnan University, Kunming 650091, china 3. graduate University of the chinese academy of sciences, beijing 100049, china 1. Nansen-Zhu International Research Center Institute of Atmospheric Physics Chinese Academy of Sciences Beijing 100029 China 2. Department of Atmospheric Science Yunnan University Kunming 650091 China 3. graduate University of the chinese academy of sciences Beijing 100049 China

The interannual variability of Antarctic Oscillation (AAO) and its influence on East Asian climate during both boreal winter and spring are addressed. The results show that the positive AAO anomaly decreases the cold activity over East Asia during both boreal winter and spring. AAO-related barotropic meridional teleconnection from Antarctic to Arctic is found through analysis of mean me- ridional circulations. This meridional teleconnection is remarkable over Eurasia during boreal winter and over the Pacific Ocean during boreal spring. The results also show that zonal mean zonal wind at high latitudes in Southern Hemisphere has well positive correlation with that of Eurasia during boreal winter and has negative correlation with Pacific North American teleconnection (PNA) during boreal spring, which again display the meridional teleconnection. Thus, local meridional teleconnection is a possible linkage for interaction of circulations at mid-high latitudes between both hemispheres.

关键词： Antarctic Oscillation, Eurasian west wind, meridional teleconnection, mean meridional circulation.

NEW WIND WAVE GROWTH RELATIONS

在线全文

学校读者我要写书评

暂无评论

Journal of Hydrodynamics 2004年第5期16卷 608-614页

作者： WUShu-ping HOUYi-jun YINBao-shu InstituteofOceanology ChineseAcademyofSciencesQingdao266071China

In the present paper combining the relationship between wave steepness andwave age with the significant wave energy balance equation for wind wave, a new wind wave growthrelation is presented. Comparisons with the other existing wind wave growth relations show that theresults in present paper accord better with the wind wave growth process.

关键词： relationship between wave steepness and wave age wind wave energy balanceequation new wind wave growth relation

Strict constraints on 2D primitive pairs for engineering symbol recognition:Theory and application

在线全文

学校读者我要写书评

暂无评论

Science china(Information sciences) 2012年第5期55卷 1032-1041页

作者： LI Ting 1,2,QIU XianJie 1,HUANG He 1 & WANG ZhaoQi 1 1 Virtual Reality Laboratory,Institute of Computing Technology chinese academy of sciences,beijing 100190,china 2 graduate University of chinese academy of sciences,beijing 100049,china 1. Virtual Reality Laboratory Institute of Computing Technology Chinese Academy of Sciences Beijing 100190 China2. Graduate University of Chinese Academy of Sciences Beijing 100049 China

Geometric constraints on the line-line pair,line-arc pair and arcarc pair are *** con-straints are able to encode the geometric relations between lines,arcs and circles.A geometric proof is presented to demonstrate that the constraints are stable under translation,rotation,uniform scaling or reflection of the primitive *** on the constraints,an algorithm for recognizing symbols in drawings is ***-perimental results show that,compared with three other methods,our method can distinguish more primitive pairs and has higher accuracy in engineering symbol recognition.

关键词： coordinated multi-point transmission multicell cooperation capacity analysis MIMO-OFDM power allocation frequency selective MIMO channel

DNA barcoding:species delimitation in tree peonies

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(Life sciences) 2009年第6期52卷 568-578页

作者： ZHANG JinMei1,2,WANG JianXiu1,2,XIA Tao1,2 & ZHOU ShiLiang1 1State Key Laboratory of Systematic and Evolutionary Botany,Institute of Botany,the chinese academy of sciences,beijing 100093,china 2graduate school of the chinese academy of sciences,beijing 1.0039,china 1. State Key Laboratory of Systematic and Evolutionary Botany Institute of Botany the Chinese Academy of Sciences Beijing 100093 China 2. graduate school of the chinese academy of sciences Beijing 100039 China

Delimitations of species are crucial for correct and precise identification of *** "spe-cies" is more a subjective than an objective concept in taxonomic practice due to difficulties in revealing patterns of infra-or inter-specific *** phylogenetic studies at the population level solve this problem and lay a sound foundation for DNA *** this paper we exemplify the necessity of adopting a phylogenetic concept of species in DNA barcoding for tree peonies(Paeonia ***).We used 40 samples representing all known populations of rare and endangered species and several populations of widely distributed tree *** currently recognized species and major variants have been included in this *** chloroplast gene fragments,***,rps16-trnQ,trnL-F and trnS-G(a total of 5040 characters,96 variable and 69 parsimony-informative characters) and one variable and single-copy nuclear GPAT gene fragment(2093?2197 bp,279 variable and 148 parsi-mony-informative characters) were used to construct phylogenetic relationships among the *** evolutionary lineages revealed by the nuclear gene and the chloroplast genes are inconsistent with the current circumscriptions of ***,***,***,and *** based on *** inconsistencies come from(1) significant chloroplast gene divergence but little nuclear GPAT gene divergence among population systems of *** + ***,and(2) well-diverged nuclear GPAT gene but little chloroplast gene divergence between *** and *** incongruence of the phylogenies based on the chloroplast genes and the nuclear GPAT gene is probably due to the chloro-plast capture event in evolutionary history,as no reproductive barriers exist to prevent inter-specific *** also evaluated the suitability of these genes for use as DNA barcodes for tree *** variability of chloroplast genes among well-defined species or population systems of a specie

关键词： DNA barcoding evolution Paeonia phylogeny species concept

Adaptive quasi-likelihood estimate in generalized linear models

在线全文

学校读者我要写书评

暂无评论

Science china Mathematics 2005年第6期48卷 829-846页

作者： CHEN Xia & CHEN Xiru school of Mathematics and Statistics, Wuhan University, Wuhan 430072, china graduate school, chinese academy of Science, beijing 100049, china 1. school of Mathematics and Statistics Wuhan University 430072 Wuhan China 2. graduate school Chinese Academy of Science 100049 Beijing China

This paper gives a thorough theoretical treatment on the adaptive quasilikelihood estimate of the parameters in the generalized linear models. The unknown covariance matrix of the response variable is estimated by the sample. It is shown that the adaptive estimator defined in this paper is asymptotically most efficient in the sense that it is asymptotic normal, and the covariance matrix of the limit distribution coincides with the one for the quasi-likelihood estimator for the case that the covariance matrix of the response variable is completely known.

关键词： generalized linear models, quasi likelihood estimate, adaptive estimate.

Cloning and roles of goldfish maternal factor β-Catenin cDNA in embryonic development

在线全文

学校读者我要写书评

暂无评论

chinese Science Bulletin 2004年第7期49卷 683-688页

作者： ZHANG Jingpu1,2,WANG Weixian1 & ZHU Shaoxia1 1.Institute of Genetics and Developmental Biology,chinese academy of sciences,beijing 100080,china 2.The graduate school of the chinese academy of sciences,beijing 1.0039,china Correspondence should be addressed to Zhang Jingpu Institute of Genetics and Developmental Biology Chinese Academy of Sciences Beijing 100080 China The graduate school of the chinese academy of sciences Beijing 100039 China

Interaction between nucleus and cytoplasm has been focused in the field of animal embryonic development, in which study of maternal factors is required positively. b-Catenin, an important maternal factor in early embryo-genesis, has been analyzed in its expression pattern and func-tions in this paper. We have cloned goldfish b-Catenin cDNA gene and compared it with zebrafish b-Catenin cDNA. High homology was found in cDNA and in amino acid sequences between them, 93% (2227/2384 bp) and 98.5% (768/780 aa) respectively. The expression pattern of b-Catenin by in situ hybridization and the roles of b-Catenin on embryonic de-velopment by co-injection of anti-sense RNA and reporter gene, EGFP have been investigated in the whole process of goldfish embryonic development. The results suggest that b-Catenin presents dynamic distribution, mainly locates at body axis, dorsal tissues, head and tail structures after being fertilized. The loss of b-Catenin activity would cause serious destruction of embryo in dorsal tissues and in anteroposte-rior axes, and leads embryos to die before larva get hatched.

关键词：胚胎发育母体因子金鱼基因克隆氨基酸序列 cDNA 细胞质细胞核

CBCR:CBC MAC with rotating transformations

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 2247-2255页

作者： ZHANG LiTing 1,2,WU WenLing 1,ZHANG Lei 1 & WANG Peng 21 State Key Laboratory of Information Security,Institute of Software,chinese academy of sciences,beijing 100190,china 2 graduate University of chinese academy of sciences,beijing 100049,china 1. State Key Laboratory of Information Security Institute of Software Chinese Academy of Sciences Beijing 100190 China2. Graduate University of Chinese Academy of Sciences Beijing 100049 China

Message authentication codes (MACs) are widely used to protect data integrity and data origin authentication in *** this paper,we propose a new block-cipher-based MAC algorithm,CBCR,with provable security for arbitrary-length *** adopts rotating operations in the end of cipherblock-chaining structure,and it appends fixed-length prefixes to all messages,which implies flexible usages in *** example,these fixed-length prefixes can be filled with some security parameters,message redundancies,*** also propose CBCR0,a special case of CBCR that sets its prefix to be an all-zero *** with CMAC,a recommended standard by the US National Institute of Standards and Technology (NIST),CBCR0 enjoys all the advantages that CMAC has,but requires less memory;so,in practical applications,CBCR0 behaves as well as CMAC does,and it is even more suitable for environments with limited memory resources,*** cards.

关键词： message authentication code cipher block chaining block cipher provable security

Spatial heterogeneity of the driving forces of cropland change in china

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 2005年第12期48卷 2231-2240页

作者： LIU Xuhua1,2, WANG Jinfeng1, LIU Mingliang4,1 & MENG Bin1,2,3 1. Institute of Geographic sciences and Natural Resources Research, chinese academy of sciences, beijing 100101, china 2. graduate school of the chinese academy of sciences, beijing 1.0039, china 3. College of Arts and sciences of beijing Union University, beijing 100083, china 4. school of Forestry and Wildlife sciences, Auburn University, Auburn, Alabama, AL36849, USA 1. Institute of Geographic sciences and Natural Resources Research Chinese Academy of Sciences 100101 Beijing China 2. graduate school of the chinese academy of sciences 100039 Beijing China 3. school of Forestry and Wildlife sciences Auburn University Auburn AL36849 Alabama USA 4. College of Arts and sciences of beijing Union University 100083 Beijing China

By using digital satellite remote sensing data acquired in 1987―1989 and 1999―2000 and GIS combined with the natural and socio-economic data, this paper drew an integrated zonation of the cropland change and its driving forces in china. The results indicated that the cropland change in the study period was constrained by geographical factors and driven by cli-mate change as well as socio-economic system. Moreover, the regional differences of the drivers for cropland change were significant. In the midwest of china, natural condition changes and geographical background were the main constraints and drivers, while in Eastern china, social and economic changes and economic policies were the main driving forces. The cropland loss was nationwide. The dominant factors to cause this decrease included buildup of developing area to attract foreign capital and technologies, changes of industry structure due to urban in-fluence, the change of employment notions thanks to living standard improvement, rapid ur-banization due to the expansion of cities and towns, the diminished farming net income partly because of the global warming effects, and the rapid economic growth stimulated by the con-venient transportation system. These factors interact and interdepend with each other to cause the cropland loss in china recently. The reasons for the increase of cropland were primarily the cultivation and deforestation by the farmers who want to increase income. This study on the mechnism of LUCC relied on the cropland change integrated classification considering the natural or human factors both inside and outside the region, which provides a new approach to study the integrated regionalization and LUCC mechanism.

关键词： land use change, driving force, integrated classification, spatial statistics, cropland, china.