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

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,{3.,fredericton,nb e3b 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

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

Approximation of dense-n/2-subgraph and table compression pr...

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中国运筹学会第七届学术交流会

作者： XU Dachuan HAN Jiye DU Donglei College of Applied Sciences, beijing university of Technology,beijing,100022, China Institute of Applied Mathematics, Acedemy of Mathematics and Systems Sciences,Chinese Academy of Sciences, beijing,100080, China faculty of administration,{3.,p.o. box 4400,fredericton,nb e3b 5a3,canada College of Applied Sciences Beijing University of Technology(China Beijing) Institute of Applied Mathematics Academy of Mathematics and Systems SciencesChinese Academy of Scie faculty of administration University of New Brunswick(Canada Fredericton)

针对两个Np难问题:dense n/2-subgraph(DSp)和table compression(TCp),我们给出改进的近似算法.基于SDp松弛和巧妙的舍入技巧,对于DSp和TCp我们分别给出0.5982和0.5970近似算法.通过增加三角不等式,我们分别得到改进的近似比:0.6243.0.... 详细信息

针对两个Np难问题:dense n/2-subgraph(DSp)和table compression(TCp),我们给出改进的近似算法.基于SDp松弛和巧妙的舍入技巧,对于DSp和TCp我们分别给出0.5982和0.5970近似算法.通过增加三角不等式,我们分别得到改进的近似比:0.6243.0.6708.关于TCp的结果改进了贪婪算法导出的0.5近似比,从而解决了Anderson[1]提出的open问题.

关键词： Dense-n/2-Subgraph problem table compression problem SDp approximation ratio.

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Spatiotemporal Modeling of Monthly precipitation in the Upper Shiyang River Watershed in West Central Gansu,Northwest China

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Advances in Atmospheric Sciences 2010年第1期27卷 185-194页

作者：张存杰 C.p.-A.boURQUe 孙兰东 Q.K.HASSAN Cold and Arid Regions environmental and engineering Research Institute Chinese Academy of Sciences Lanzhou Regional Climate Centre faculty of Forestry and environmental Management University of New Brunswick28 Dineen DriveFrederictonNew BrunswickE3B 6C2Canada Department of Geomatics engineering Schulich School of EngineeringUniversity of Calgary2500 University Drive NWCalgaryAlbertaT2N 1N4Canada

This paper outlines a methodology to estimate monthly precipitation surfaces at 1-kin resolution for the Upper Shiyang River watershed （USRW） in northwest China. Generation of precipitation maps is based on the application of a four-variable genetic algorithm （GA） trained on 10 years of weather and ancillary data, i.e., surface air temperature, relative humidity, Digital elevation Model-derived estimates of elevation, and time of year collected at 29 weather stations in west-central Gansu and northern Qinghai province. An observed-to-GA predicted data comparison of 10 years of precipitation collected at the 29 weather stations showed that about 84% of the variability in observed values could be explained by the trained GA, including variability in two independent datasets. point-comparisons of observed and modeled precipitation along an elevation-rainfall gradient demonstrated near-similar spatiotemporal patterns. A precipitation surface for USRW for July, 2005, was developed with the trained GA and input surfaces of surface air temperature and relative humidity generated from Moderate Resolution Imaging Spectroradiometer sensor （MoDIS） products of land surface temperature. Spatial tendencies in predicted maximum and minimum values of surface air temperature, relative humidity, and precipitation within a 2-kin radius circle around selected weather stations were in close agreement with the values measured at the weather stations.

关键词： genetic algorithms model building MoDIS products principal component analysis watershed delineation

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production, Application, and Field performance of Abietiv^(TM),the balsam Fir Sawfly Nucleopolyhedrovirus

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中国病毒学 2007年第2期22卷 163-172页

作者： Christopher J. Lucarotti benoit Morin Robert I.Graham Renée Lapointe Natural Resources canada Canadian Forest Service-Atlantic Forestry Centre PO Box 4000FrederictonNew Brunswick E3B 5P7Canada Population Ecology Group Faculty of Forestry and Environmental Management University of New Brunswick Fredericton New Brunswick E3B 6C2 Canada Natural Resources canada Canadian Forest Service-Atlantic Forestry Centre PO Box 4000FrederictonNew Brunswick E3B 5P7Canada population ecology Group Faculty of Forestry and Environmental Management University of New Brunswick Fredericton New Brunswick E3B 6C2 Canada Sylvar Technologies Inc.p.o.box 63. Stn.AFrederictonNew Brunswick E3B 5A6Canada

beginning in the early 1990s, the balsam fir sawfly (Neodiprion abietis) became a significant defoliating insect of precommercially thinned balsam fir (Abies balsamea (L.) Mill.) stands in western newfoundland, canada. In 1997, a nucleopolyhedrovirus (NeabNpV) was isolated from the balsam fir sawfly and, as no control measures were then available, NeabNpV was developed for the biological control of balsam fir sawfly. In order to register NeabNpV for operational use under the Canadian pest Control products Act, research was carried out in a number of areas including NeabNpV field efficacy, non-target organism toxicology, balsam fir sawfly ecology and impact on balsam fir trees, and NeabNpV genome sequencing and analysis. As part of the field efficacy trials, approximately 22 500 hectares of balsam fir sawfly-infested forest were aerially treated with NeabNpV between 2000 and 2005. NeabNpV was found to be safe, efficacious, and economical for the suppression of balsam fir sawfly outbreak populations. Conditional registration for the NeabNpV-based product, Abietiv?, was received from the pest Management Regulatory Agency (Health canada) in April 2006. In July 2006, Abietiv was applied by spray airplanes to 15 000 ha of balsam fir sawfly-infested forest in western newfoundland in an operational control program.

关键词：生产应用香油锯蝇

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