检索结果-南通市图书馆

Approximation of dense-n/2-subgraph and table compression problems

在线全文

学校读者我要写书评

暂无评论

science china Mathematics 2005年第9期48卷 1223-1233页

作者： XU Dachuan~1 HAN Jiye~2 & DU Dongle~3.1. College of Applied sciences,Beijing University of Technology,Beijing 100022,china 2. Institute of Applied Mathematics,Academy of Mathematics and Systems science,Chinese Academy of sciences,Beijing 100080,china 3. Faculty of Administration,University of New Brunswick,P.O.Box 4400,Fredericton,NB E3. 5A3.Canada College of Applied sciences Beijing University of Technology Beijing 100022 China Institute of Applied Mathematics Academy of Mathematics and Systems Science Chinese Academy of Sciences Beijing 100080 China Faculty of Administration University of New Brunswick P.O. Box 4400 Fredericton NB E3B 5A3 Canada

We develop improved approximation algorithms for two NP-hard problems: the dense-n/2-subgraph and table *** on SDP relaxation and advanced rounding techniques,we first propose 0. 5982 and 0. 5970-approximation algorithms respec- tively for the dense-n/2-subgraph problem (DSP) and the table compression problem (TCP). Then we improve these bounds to 0. 6243.and 0. 6708 respectively for DSP and TCP by adding triangle inequalities to strengthen the SDP *** results for TCP beat the 0. 5 bound of a simple greedy algorithm on this problem,and hence answer an open question of Anderson in an affirmative way.

关键词： dense-n/2-subgraph problem(DSP) table compression problem(TCP) SDP approximation ratio

A COLUMN RECURRENCE ALGORITHM FOR SOLVING LINEAR LEAST SQUARES PROBLEM

在线全文

学校读者我要写书评

暂无评论

Journal of Computational Mathematics 1996年第4期14卷 301-310页

作者： J.X. Zhao(department of Mathematics, nanjing University, nanjing {3.) 南京大学数学系江苏南京

A new column recurrence algorithm based on the classical Greville method and modified Huang update is proposed for computing generalized inverse matrix and least squares solution. The numerical results have shown the ... 详细信息

关键词： Math A COLUMN RECURRENCE ALGORITHM FOR SOLVING LINEAR LEAST SQUARES PROBLEM ABS

On-line parallel reversed phase two-dimensional liquid chromatography for high-throughput analysis of complex proteomic samples

在线全文

学校读者我要写书评

暂无评论

science china Chemistry 2006年第6期49卷 527-533页

作者： WANG Zhicong1,3. ZHANG Qinghe2, LI Tong2, ZHAO Zhongyi3.& ZHANG Weibing1 1. Dalian Institute of Chemical Physics, Chinese Academy of sciences, Dalian 116011, china 2. Dalian Elite Analytical Instrument Co., Ltd., Dalian 116011, china 3. Faculty of Material science and Chemical Engineering, china University of Geosciences, Wuhan 43.074, china Dalian Institute of Chemical Physics Chinese Academy of Sciences Dalian China Faculty of Material science and Chemical Engineering China University of Geosciences Wuhan China Dalian Elite Analytical Instrument Co. Ltd. Dalian China

A comprehensive two-dimensional liquid chromatographic system (2D SCX/RP) is con- structed with a 10-port-2-way valve using strong cation exchange chromatography (Hypersil SCX, 100 mm×4.6 mm I.D.) followed by reversed phase chromatography (Hypersil BDS C18, 15 mm×4.6 mm I.D.) to separate the complex peptides from globin peptic hydrolysate. After the sample was loaded on the SCX column, the phosphate buffer (pH 4.0) was used to elute the peptides. Then, elutes flowed through the interface and the peptides focused on the head of the trapping columns (Hypersil BDS C18, 15 mm×4.6 mm I.D.) but salt passed into the waste. After the valve was switched, the samples were flushed with a backward flow into the RP analytical column. The peptides on the SCX were eluted with 12 discontinuous steps linearly increasing salt concentrations. The peptides enriched on the trapping column were desalted and separated by the RP columns. The resolution and the resolved peaks of the 2D SCX/RP system were greatly increased and the total peak capacity reached as high as 2280.

关键词： two-dimensional liquid chromatography, interface, trapping column, proteomics, globin.

Sm-Nd and zircon SHRIMP U-Pb dating of Huilanshan mafic granulite in the Dabie Mountains and its zircon trace element geochemistry

在线全文

学校读者我要写书评

暂无评论

science china Earth sciences 2005年第12期48卷 2081-2091页

作者： HOU Zhenhui1, LI Shuguang1, CHEN Nengsong2, LI Qiuli1 & LIU Xiaoming3.1. School of Earth and Space sciences, University of science and Technology of china, Hefei 23.026, china 2. The Key Laboratory of Continental Dynamics of the Ministry of Education, Northwest University, Xi’an 710069, china 3. Faculty of Earth sciences, china University of Geosciences, Wuhan 43.074, china School of Earth and Space sciences University of Science and Technology of China Hefei China The Key Laboratory of Continental Dynamics of the Ministry of Education Northwest University Xi’an China Faculty of Earth sciences China University of Geosciences Wuhan China

The mafic granulites from Huilanshan are outcropped on the center of the Luotian dome in the northern Dabie Mountains. The Sm-Nd isochron defined by granulite-facies meta-morphic minerals (garnet + clinopyroxene + hypersthene) yields an age of 13. ± 18 Ma indicating the early Cretaceous granulite-facies metamorphism. The cathodoluminescence (CL) images of zircons from the granulite show clearly core-mantle-rim structures. The zircon cores are charac-terized by typical oscillatory zoning and highly HREE enriched patterns, which suggests their magma origin. Some zircon cores among them with little Pb loss give SHRIMP U-Pb ages rang-ing from 753.to 780 Ma, which suggests that the protolith of Huilanshan granulite is Neopro-terozoic mafic rocks. The zircon mantles usually cut across the oscillatory zone of the zircon cores have 3.10 times lower REE, Th, U, Y, Nb and Ta contents than the igneous zircon cores but have high common Pb contents. These characteristics suggest that they were formed by hydrothermal alteration of the igneous zircons. The part of zircon mantles with little Pb loss give a similar SHRIMP U-Pb age (716―780 Ma) to the igneous zircon cores, which implies that the hydrothermal events occurred closely to the magmatic emplacement. In view of the strong early Cretaceous magmatism in the Luotian dome, consequently, the Huilanshan mafic granulite was formed by heating of the Neoproterozoic mafic rocks in mid-low crust, which caused the granu-lite-facies metamorphism underneath the Dabie Mountains. The similarity between the granulite metamorphic age (13. ± 18 Ma) defined by Sm-Nd isochron and K-Ar age of 123.127 Ma given by amphible from the gneiss in Luotian dome suggests a rapid uplifting of the Luotian dome, which may result in further exhumation of the ultrahigh pressure metamorphic rocks in the Dabie Mountains.

关键词： Dabie orogen, granulite, zircon U-Pb ages, Sm-Nd age.

A MODIFIED PROJECTION AND CONTRACTION METHOD FOR A CLASS OF LINEAR COMPLEMENTARITY PROBLEMS

在线全文

学校读者我要写书评

暂无评论

Journal of Computational Mathematics 1996年第1期14卷 54-63页

作者： B.S. He(department of Mathematics, nanjing University, nanjing, {3.) 南京大学数学系江苏南京

Recently, we have proposed an iterative projection and contraction (PC) method for a class of linear complementarity problems (LCP)([4]). The method was showed to be globally convergent, but no statement could be made about the rate of convergence. In this paper, we develop a modified globally linearly convergent PC method for linear complementarity problems. Both the method and the convergence proofs are very simple. The method can also be used to solve some linear variational inequalities. Several computational experiments are presented to indicate that the method is surprising good for solving some known difficult problems.

关键词： Th Pn A MODIFIED PROJECTION AND CONTRACTION METHOD FOR A CLASS OF LINEAR COMPLEMENTARITY PROBLEMS II

Relationships between bacterial-algal proliferating and mass extinction in the Late Devonian Frasnian-Famennian transition:Enlightening from carbon isotopes and molecular fossils

在线全文

学校读者我要写书评

暂无评论

science china Earth sciences 2005年第10期48卷 1656-1665页

作者： GONG Yiming1,2, XU Ran1, TANG Zhongdao1, SI Yuanlan3.& LI Baohua4 1. Faculty of Earth science and State Key Laboratory of Geological Processes and Mineral Resources, china University of Geosciences, Wuhan 43.074, china 2. Institute of Resources & Environments, Henan Polytechnic University, Jiaozuo 454003. china 3. department of Computer science, South-Central University for Nationalities, Wuhan 43.074, china 4. Laboratory of Marine Geology, Tongji University, Shanghai 200092, china china University of Geosciences Henan Polytechnic University South-Central University for Nationalities Tongji University

Studies show positive shifts of inorganic and organic carbon isotope values (δ 13.carb and δ 13.kerogen) from +0.43.(‰ V-PDB) to +3.54 (‰ V-PDB) and from ?29.3. (‰ V-PDB) to ?24.14 (‰ V-PDB), respectively, B* (Ba* = Ba/ (Al2O3.X 15%)) values from 0.015 to 0.144, TOC values from 0.02% to 0.21%, V/Cr values from 0.3.to 2.0, Sr/Ba values from 3.20 to 49.50 in the Late Devonian Frasnian Upper rhenana zone to the top linguiformis zone of the Yangdi sec-tion deposited in carbonate slope facies of Guilin, Guangxi, South china, which indicates that biomass, productivity, organic carbon burial and salinity increase and that oxygenation near the boundary between sediments and waters decreases from the Late Devonian Frasnian Upper rhenana zone to the top linguiformis zone. Abundance of molecular fossils increases and normal alkanes, isoprenoid hydrocarbon, terpanes and steranes are dominated from the Late Devonian Frasnian to the bottom of Famennian, which shows that the predecessors of molecular fossils of the Frasnian-Famennian (F-F) transition are dominated by marine phytoplankton, zooplankton and benthic bacteria with no photosynthesis. Therefore, it is considered that the F-F transitional mass extinction with a multistage, selection and global synchronizing was caused by bacte-rial-algal proliferating, continuing deterioration of the shallow marine ecoenvironment of the mid-dle-lower latitudes. A simple cause and effect chain can be expressed as: appearance of seed plants and multi-storied forests → enhanced chemical and biochemical weathering and pe-dogenesis → wide development of soils → increasing riverine nutrient fluxes in epicontinental sea → from superoligotrophic to eutrophic in epicontinental sea → proliferating of marine phyto-plankton and zooplankton → frequent red tide and anoxia → mass extinction of shallow marine organisms in the middle-lower latitudes. It is worth notice that the factor drawdown of atmos-pheric Pco2, climatic cooling and sea level falling c

关键词： mass extinction, bacteria-algae, carbon isotopes, molecular fossils, biodiversity, Late Devonian, Guangxi, South china.

Study on NDVI-T_s space by combining LAI and evapotranspiration

在线全文

学校读者我要写书评

暂无评论

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 Research Center for Remote Sensing and GIS School of Geography Beijing Normal University Beijing China State Key Laboratory of Remote Sensing science Beijing China Beijing Key Laboratory for Remote Sensing of Environment and Digital Cities Beijing China department of Information Management College of Information and Electronic Engineering China Agricultural University Beijing 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.

Deformation in the Three Gorges Reservoir after the first impoundment determined by GPS measurements

在线全文

学校读者我要写书评

暂无评论

Progress in Natural science:Materials International 2005年第6期15卷 515-522页

作者： DU Ruilin 1,2 , QIAO Xuejun 1,2 *, WANG Qi 1,2 , XING Canfei 1,2 and YOU Xinzhao 1,3.(1. Institute of Seismology, CEA, Wuhan 43.071, china 2. Laboratory of Crustal Movement and Earth Observation, Wuhan 43.071, china 3. Center for Analysis and Prediction, CEA, Beijing 10003., china) Institute of Seismology CEA Wuhan 430071 China Laboratory of Crustal Movement and Earth Observation Wuhan 430071 China Center for Analysis and Prediction CEA Beijing 100036 China

A 6-year long GPS observation (1998—2003. indicates that crustal deformation in the Three Gorges area is less active at a marginally measurable rate of 0—5 mm/a relative to stable South china block. However, the impounding water in June 2003.has induced transient displacement at the Three Gorges dam and the emerging reservoir. GPS measurements after the first stage of water filling of the reservoir demonstrate that vertical subsidence close by Yangtze River is about 10—40 mm, and the horizontal displacement is less than 5—10 mm. The maximum subsidence induced by the impoundment is located in the segment of the reservoir from Maoping to Xiangxi. The water loading-induced deformation diminishes rapidly with the distance from banks of the reservoir. The overall pattern of transient deformation is consistent with the simulation result of Farrell, and is attributed to the elastic response of upper lithosphere crust to overlying water reservoir.

关键词： Three Gorges GPS impoundment deformation.

Wavelet estimation of the diffusion coefficient in time dependent diffusion models

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 Mathematics 2007年第11期50卷 1597-1610页

作者： Ping CHEN~(1,2+) Jin-de WANG~1 1 department of Mathematics,nanjing University,nanjing {3.china 2 School of science,nanjing University of science and Technology,nanjing 210094,china department of Mathematics Nanjing University Nanjing China School of science Nanjing University of Science and Technology Nanjing China

The estimation problem for diffusion coefficients in diffusion processes has been studied in many papers,where the diffusion coefficient function is assumed to be a 1-dimensional bounded Lipschitzian function of the state or the time *** is no previous work for the nonparametric estimation of time-dependent diffusion models where the diffusion coefficient depends on both the state and the *** paper introduces and studies a wavelet estimation of the time-dependent diffusion coefficient under a more general assumption that the diffusion coefficient is a linear growth Lipschitz *** the properties of martingale,we translate the problems in diffusion into the nonparametric regression setting and give the Lr convergence rate.A strong consistency of the estimate is *** this result one can estimate the time-dependent diffusion coefficient using the same structure of the wavelet estimators under any equivalent probability *** example,in finance,the wavelet estimator is strongly consistent under the market probability measure as well as the risk neutral probability measure.

关键词： wavelet estimation time-dependent diffusion coefficient linear growth condition strong consistency