地球信息科学的研究与发展     

于冬梅 《海岸工程》2002,21(2):59-65

信息时代的召唤,地球信息科学应运而生.经过10a左右的发展,地理信息科学已见雏形.总结了10a来地球信息科学的研究结果,并介绍了地球信息科学的研究内容和发展前景.  相似文献   

花尾胡椒鲷养殖群体遗传多样性的等位酶研究   总被引：5，自引：1，他引：5  

丁少雄  王军  苏永全  全成干  张纹  郭丰  马梁 《台湾海峡》2001,20(2):224-227,T002

应用聚丙烯酰胺凝胶电泳（PAGE）技术对取自厦门火烧屿海水网箱的花尾胡椒鲷人工鱼养殖群体的遗传多样性进行等位酶分析。结果表明：所检测的16种同工酶的24个基因座位中，在XDH和GCDH基因座位上发现多态性，其平均多态位点比例为8．33％，基因座位有效等位基因的平均数Ne为1.083，平均杂合度的观测值Ho为0．00556，预期值He为0．00537,Hardy-Weinberg遗传偏离指数（D)为0．035。与其他鱼类相比较说明了其遗传多样性处于较低水平，文中对此进行了探讨并提出相应的种质资源管理保护措施。  相似文献   

Ice-Induced Fatigue Analysis by Spectral Approach for Offshore Jacket Platforms with Ice-Breaking Cones     

岳前进刘圆  张日向屈衍 王瑞学 《中国海洋工程》2007,21(1):1-10

The spectral methods and ice-induced fatigue analysis are discussed based on Miner's linear cumulative fatigue hypothesis and S-N curve data.According to the long-term data of full-scale tests on the platforms in the Bohai Sea,the ice force spectrum of conical structures and the fatigue environmental model are established.Moreover,the finite element model of JZ20-2MSW platform,an example of ice-induced fatigue analysis,is built with ANSYS software.The mode analysis and dynamic analysis in frequency domain under all kinds of ice fatigue work conditions are carried on,and the fatigue life of the structure is estimated in detail.The methods in this paper can be helpful in ice-induced fatigue analysis of ice-resistant platforms.  相似文献   

"有序样品的Fisher聚类"对中华绒螯蟹渔获物的分析     

王宇庭  高天翔  史为良  郑有刚  赵睿 《中国海洋大学学报(自然科学版)》2005,35(2):297-300

为探讨河蟹生长特点以及渔获物与放养规格的关系，用有序样品的Fish聚类分析法首次对中华绒螯蟹的渔获物组成进行分析。结果显示，黄河三角洲广南水库沉砂池2000年河蟹渔获物可以分为3个群体，与其放养的3个不同规格群体相对应；据此推算了不同放养规格的回捕率；并对雌、雄生长和性成熟的差异以及合理的放养规格进行了探讨。  相似文献   

Stress Sharing Behavior and Its Mechanism during Consolidation Process in Composite Ground Improved by Sand Compaction Piles with Low Replacement Area Ratio     

S. -K. You  K. Oda  T. -H. Kim 《Marine Georesources & Geotechnology》2006,24(4):287-304

In order to accurately design a sand compaction pile (SCP) with low replacement area ratio, it is important to understand the mechanical interaction between the sand pile and clay ground and its mechanism during consolidation process in composite ground. In this article, therefore, a series of numerical analyses on composite ground improved by SCP with low replacement area ratio were carried out. The applicability of numerical analyses, in which an elasto-viscoplastic consolidation finite element method was applied, were confirmed by comparing the results obtained from a series of laboratory model tests with the composite ground improved by SCP. Through the results of the numerical analyses, mechanical behavior of the sand pile and clay in composite ground during consolidation is elucidated, together with a stress sharing mechanism between sand pile and clay.  相似文献   

Determination of phospholipid fatty acid structures and stable carbon isotope compositions of deep-sea sediments of the Northwest Pacific, ODP site 1179   总被引：1，自引：0，他引：1  

Christopher T. Mills  Robert F. Dias  Dennis Graham  Kevin W. Mandernack   《Marine Chemistry》2006,98(2-4):197-209

Sediment samples ranging from 0.05 to 278 m below sea floor (mbsf) at a Northwest Pacific deep-water (5564 mbsl) site (ODP Leg 191, Site 1179) were analyzed for phospholipid fatty acids (PLFAs). Total PLFA concentrations decreased by a factor of three over the first meter of sediment and then decreased at a slower rate to approximately 30 mbsf. The sharp decrease over the first meter corresponds to the depth of nitrate and Mn(IV) reduction as indicated by pore water chemistry. PLFA-based cell numbers at site 1179 had a similar depth profile as that for Acridine orange direct cell counts previously made on ODP site 1149 sediments which have a similar water depth and lithology. The mole percentage of straight chain saturated PLFAs increases with depth, with a large shift between the 0.95 and 3.95 mbsf samples. PLFA stable carbon isotope ratios were determined for sediments from 0.05 to 4.53 mbsf and showed a general trend toward more depleted δ¹³C values with depth. Both of these observations may indicate a shift in the bacterial community with depth across the different redox zones inferred from pore water chemistry data. The PLFA 10me16:0, which has been attributed to the bacterial genera Desulfobacter in many marine sediments, showed the greatest isotopic depletion, decreasing from − 20 to − 35‰ over the first meter of sediment. Pore water chemistry suggested that sulfate reduction was absent or minimal over this same sediment interval. However, 10me16:0 has been shown to be produced by recently discovered anaerobic ammonium oxidizing (anammox) bacteria which are known chemoautotrophs. The increasing depletion in δ¹³C of 10me16:0 with the unusually lower concentration of ammonium and linear decrease of nitrate concentration is consistent with a scenario of anammox bacteria mediating the oxidation of ammonium via nitrite, an intermediate of nitrate reduction.  相似文献   

Spatial patterns of mesozooplankton distribution in the Southwestern Atlantic Ocean (34{degrees}-41{degrees}S) during austral spring: relationship with the hydrographic conditions     

Marrari  Marina; Vinas  Maria Delia; Martos  Patricia; Hernandez  Daniel 《ICES Journal of Marine Science》2004,61(4):667-679

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The role of schizogenesis in population dynamics of Timarete filigera (Polychaeta: Cirratulidae): 2-years observations in the Port of Bari (South Adriatic Sea)     

Miriam Gherardi  Margherita Sciscioli  Elena Lepore  Giuseppina Todisco  & Adriana Giangrande 《Marine Ecology》2007,28(2):306-314

Different aspects of reproductive biology of the polychaete Timarete filigera (Delle Chiaje) were studied during a period of 2 years (from September 2002 to August 2003 and from September 2004 to August 2005). Timarete filigera specimens were collected monthly in the port of Bari (South Adriatic Sea, Mediterranean Sea). For population analysis, regenerating and entire specimens were separately analyzed, the regenerating individuals were assigned to different categories related to the region of the body from which they derived. Regenerating individuals were present throughout the year. There were three to four times more individuals deriving from the middle part than the anterior and posterior regenerating portions. From the high percentage of regenerating individuals observed in the T. filigera population, it can be supposed that this species reproduces mainly asexually by schizogenesis. However, histological analysis revealed the presence of female gametes in a few individuals. In contrast, males were never collected, probably due to the limited number of reproductive individuals collected. The abundance has shown wide fluctuations during the year, with a decrease from Winter to Spring. The analysis of the size‐frequency histograms has shown a growing phase of whole specimens from Spring to Winter. The life cycle of the investigated species is discussed with the hypothesis that strategies could be linked to the colonized environments, agamic reproduction coupled with sexual reproduction assures the presence and expansion of the population after the colonization by a limited number of larvae.  相似文献   

基于塑性极限分析理论和神经网络响应面的结构系统可靠性分析     

闫宏生  胡云昌 《海洋工程》2003,21(2):1-7

根据多层神经网络映射存在定理，提出了基于神经网络响应面和塑性极限分析理论的结构系统可靠性分析的新方法。数值试验表明，该方法可以快速、高质量地求出结构系统可靠性指标，是一个具有发展前景的新方法。  相似文献   

一种基于BP算法学习的小波神经网络   总被引：2，自引：1，他引：2  

陈哲  冯天瑾  陈刚 《中国海洋大学学报(自然科学版)》2001,31(1)

为发展 Szu的基于信号表示的小波神经网络 ,提出一种多输入多输出的小波网络模型 ,网络隐层采用框架小波函数、输出层采用 Sigmoid激励函数 ,并选用“熵误差函数”以加速网络的学习速度。奇偶判别和混沌时间序列预测例子的实验结果表明了它具有良好的函数逼近能力和推广能力 ,收敛速度和均方误差均优于相同结构的多层感知器模型。  相似文献