抗差估计的初值选择     

王振杰  欧吉坤  曲国庆 《大地测量与地球动力学》2001,21(3):32-35

对L1 范估计的平差值和LS估计的平差值作为抗差估计的初值进行了比较 ,指出在 ρ函数是严凸函数时 ,二者无明显的区别。因为LS估计简单且易于计算 ,因此建议用LS估计的平差值作为抗差估计的初值。  相似文献   

APPLICATION OF MAP AND FILE INFORMATIONVISUALIZATION SYSTEM TO COMPREHENSIVEDIVISION OF NATURAL DISASTERS- Takingthe ChangjiangValleg as an Example     

HU Bao-qing    JIANG Mei-xin  JUN Su-lan  ZENG Qiao-song 《中国地理科学(英文版)》2001,(4)

In recent years，scholars at home and abroad have method，and that vanous disasters would be analyzed assynthetically studied natural dlsaste‘theoretically and an Integral．SHI Peilun（1991）putforwad a scientificmethodologlcally，as well as its cases analys。s（CND，term—regional disaster system，which Indicates that1987； MA et al，1990； MARBLE，1990； NE et al，the situation of a disaster（calamity loss）results from1999； PATAK et al，1982； SHI，1991；VAN et al，h…  相似文献   

山东龙口市大磨曲家金矿地质特征及找矿方向探讨          下载免费PDF全文

刘晓煌  耿书杰  马树江  高池兴  赵新峰 《山东国土资源》2001,17(3):69-75

大磨曲家金矿位于玲珑金矿田东风矿床主脉的NE延伸部位.矿区内已发现矿脉25条.通过对玲珑金矿田的成矿条件分析和东风矿床的综合研究,认为本区有很好的找矿前景.  相似文献   

EFFECT OF LIGHT INTENSITY ON THE TOTAL LIPID AND FATTY ACID COMPOSITION OF SIX STRAINS OF MARINE DIATOMS     

梁英麦康森  孙世春于道展 《中国海洋湖沼学报》2001,19(3):249-254

The effect of light intensity ( 1500 Ix and 5000 Ix) on the total lipid and fatty acid composition of six strains of marine diatoms Cylindrotheca fusiformis (B211 ), Phaeodactylum tricornutum (Bl14, Bl18 and B221) Nitzschia closterium (B222) and Chaetoceros gracilis (B13) was investigated.The total lipids of B13, Bl14, and B211 grown at 5000 Ix were lower than those grown at 1500 Ix. No evident changes were observed in Bl18, B221 and B222. Fatty acid composition changed considerably at different light intensity although no consistent correlation between the relative proportion of a single FA and light intensity. The major fatty acids of the 6 strains were 14:0, 16:0, 16:l(n- 7) and 20:5(n-3) . Cylindrothecafusiformis had high percentage of 20:4n - 6 (9.2 - 10.9% ) . The total polyunsaturated fatty acid /rl all 6 strains decreased with increasing light intensity. The percentage of the highly unsaturated fatty acid eicosapentaenoic acid (EPA) decreased with increasing light intensity in all strains except Chaetoceros gracilis.  相似文献   

Urban tourism research methodology     

Tao Wei  Zhong Wen-hui  Hong Yan 《中国地理科学(英文版)》2005,15(2):173-178

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维生素E醋酸酯对鱼油脂肪酸含量变化的影响     

刘立鹤  郑石轩  周永奎  董爱华  吴建开  陈立侨 《广东海洋大学学报》2005,25(6):18-24

新鲜鱼油中添加05、0、2505、00 mg/kg 4种不同浓度的维生素E醋酸酯,在实验的第6、14、28、36和68天测定鱼油中的脂肪酸含量。结果表明:在500 mg/kg添加量内,维生素E醋酸酯对鱼油中脂肪酸含量没有显著性影响(P>0.05)。在实验期间,EPA(C20:5)、DHA(C22:6)、亚油酸(C18:2)含量明显下降,ARA(C20:4)、亚麻酸(C18:3)先升后降,棕榈酸(C16:1)逐步上升;C14含量逐渐增加,C17则先降后升,C16和C18在实验后期有较大提高。维生素E醋酸酯对鱼油中不饱和脂肪酸效用系数大小依次为:ARA>EPA>DHA>C18:3>0>C16:1>C18:2>C18:1,对ARA抗氧化效用最大,效用系数达到10.193%,C20:5为0.490%,C22:6为0.364%;维生素E醋酸酯对饱和脂肪酸效用系数大小依次为:C14>C17>0>C18>C16。  相似文献   

Early warning research on salt-alkalization desertification in western Songnen Plain     

BIAN Jian-min  LIN Nian-feng  TANG Jie College of Environment  Resources  Jilin  University  Changchun  Jilin  China 《东北亚地学研究》2005,(Z1)

Desertification is an environmental issue in the world. The salt-alkalization desertification land area formed by both primary and secondary salt-alkalization has extended in a large scale, which has become a significant eco-environmental problem. Based on the characteristics of eco-environment and the situation of desertification in western Songnen plain, this paper reports the analyzes of its formation in background and cause. An early warning system on the salt-alkalization desertification is established and the GIS technology is used to abstract the information of desertification evaluation index. Supported by the integrated technology of the GIS and ANN, the orientation and quantitative result of desertification are gained, which is helpful to the eco-environment protection and resource development in western Songnen Plain.  相似文献   

VPN技术在浙江省气象网络中的应用   总被引：2，自引：0，他引：2  

吴孟春  马奇蔚  周必高  周捷  周翔 《成都信息工程学院学报》2006,21(4):551-554

随着浙江省气象业务的不断发展，网络数据交换日益增多，同时更多基于网络的气象业务的增加，如网络视频会商、自动站数据传输等，使目前浙江省气象系统专线网络运行已达到极限，所以需要建立VPN网以对现有的网络作链路上的备份，而VPN的建立同时还可以实现移动办公，领导能在远程调用内网的资料进行远程决策服务和汇报工作。主要介绍VPN技术并叙述VPN技术在浙江省气象系统网络中的具体应用。  相似文献   

大气层对GPS信号传播影响的规律之探讨──关于广州地区大气层对GPS系统定位定时影响问题研究之二     

吴必军 《时间频率学报》1996,(1)

大气层对ＧＰＳ信号的传播有时间延迟作用，时廷将影响ＧＰＳ系统的定位和定时精度，且随气象因素的变化而变化．本文根据３年有关的气象资料，采用大气指数模型分析了广州地区大气层随昼夜变化、季节变化和太阳活动变化对ＧＰＳ信号传播时延影响的变化规律．分析得知，在信号垂直传播时，大气层对ＧＰＳ信号传播的影响，用距离表示．最大时为２．６９１ｍ，最小时也会产生１．９９３ｍ的误差；如果信号斜传播，误差因仰角因素将更大．  相似文献   

凤太矿田层控铅锌(铜)矿床的成矿物质来源探讨     

隗合明  吕仁生 《地球科学与环境学报》1990,(1)

秦岭凤太矿田层控铅锌(铜)矿床的金属物质、硫和成矿溶液主要来自深部基底的岩石,属海底喷流—沉积成因矿床。从这一理论认识出发可进一步分析控矿地质条件及今后在该区有效地寻找同类矿床。  相似文献