FVCOM model estimate of the location of Air France 447   总被引：2，自引：0，他引：2  

Changsheng Chen  Richard Limeburner  Guoping Gao  Qichun Xu  Jianhua Qi  Pengfei Xue  Zhigang Lai  Huichan Lin  Robert Beardsley  Breck Owens  Barry Carlson 《Ocean Dynamics》2012,62(6):943-952

On June 1, 2009, Air France AF447 disappeared in the Equatorial Atlantic Ocean en route from Rio de Janeiro, Brazil, to Paris, France. On June 6–19, 2009, bodies and debris from the aircraft were recovered floating in the equatorial ocean. This paper describes efforts on using the global–local nested finite volume community ocean model (FVCOM) to model reversely the tracks of bodies and debris back to the time of the crash and to help searchers locate the cockpit voice and flight data recorders and learn why this tragic accident occurred. To validate the reliability and reality of FVCOM, eight surface drifters were deployed by the French Bureau d’Enquêtes et d’Analyses pour la sécurité de l’aviation civile (BEA) near the last known position in early June 2010 for a period of 3?weeks. These drifter data were used to optimize the spatial and temporal correlation scales of the adaptive sampling data assimilation method of FVCOM. Applying an optimized FVCOM system to assimilate all available drifter- and float-tracking-derived currents in May–June 2009 under three different wind conditions, we reproduced the June 2009 current fields in the area near the LKP and used these fields to reversely track bodies and debris from locations where they were found to the time when the crash occurred. Possible locations for the crashed plane were suggested based on our model results and were made available to the French investigators and the Woods Hole Oceanographic Institution REMUS autonomous underwater vehicle Operations Group who successfully located the aircraft debris field in April 2011 on the seafloor at a depth of 3,900?m.  相似文献   

Plant Species Richness Affected Nitrogen Retention and Ecosystem Productivity in a Full‐Scale Constructed Wetland     

Si‐Xi Zhu  Peili Zhang  Hai Wang  Han‐Liang Ge  Jie Chang  Scott Chang  Zhi Qiu  Hongbo Shao  Ying Ge 《洁净——土壤、空气、水》2012,40(4):341-347

The effects of plant species richness (SR; i.e., 1, 2, 4, 8, and 16 species per plot) on substrate nitrate and ammonium retention and ecosystem productivity in a full‐scale constructed wetland (CW) with high nitrogen (N) input were studied. Substrate nitrate (0.1–16.4 mg kg^?1) and ammonium concentrations (1.3–9.2 mg kg^?1) in this study were higher than those in other comparable biodiversity experiments. Substrate nitrate concentration significantly increased while ammonium concentration significantly decreased with the increase of plant SR (p = 0.008 and 0.040, respectively). The response of ecosystem productivity to increasing SR was unimodal with four species per plot achieving the greatest productivity. Transgressive overyielding, which was compared to the most productive of corresponding monocultures, did not occur in most polycultures. We conclude that substrate N retention was enhanced by plant SR even with high N input, and plant SR could be managed to improve the efficiency of N removals in CWs for wastewater treatment.  相似文献   

Environmental and Health Impacts of Successive Mineral Fertilization in Egypt     

Ahmed A. Abdelhafez  Hassan H. Abbas  Rafat S. Abd‐El‐Aal  Nabil F. Kandil  Jianhua Li  Wahballah Mahmoud 《洁净——土壤、空气、水》2012,40(4):356-363

Excessive amounts of mineral fertilizers are unnecessarily applied to agricultural soils in Egypt to increase crop yield. The current study aims at assessing the impacts of fertilization with different mineral fertilizers for different cultivation periods on the accumulation of heavy metals in soils and plants grown thereon. In addition, human risks resulted due to the exposure to these metal ions through ingestion, and dermal routes were evaluated. Soil and plant samples were collected from several locations in El‐Behira Governorate, Egypt and their heavy metal contents were measured. The result indicated that there is a continuous accumulation of heavy metals in the soils and the plants grown thereon. Calculation of the hazard index (HI) revealed that humans, especially children, have a potential health risk for both Pb and Cd, which have levels greater than the safe level (1). Finally, the obtained results showed that the continuous application of mineral fertilizers containing high levels of heavy metals pose a potential health threat.  相似文献   

大比例尺成矿预测中高精度立方格预测模型快速构建算法     

李楠  肖克炎  丁建华  娄德波 《吉林大学学报(地球科学版)》2013,43(4):1301-1308

立方格模型是一种常用的大比例尺三维可视化预测模型。在计算机三维图形学中,立方格模型又被称为块段模型,该模型比较适合表示非均匀体数据的空间分布,在矿山大比例尺深边部成矿预测、三维反演、矿山储量估算等领域得到广泛应用。目前,构建高精度立方格预测模型的一般方法是将已有地质体、地表、构造等三维地学对象进行栅格化。针对栅格化过程中遇到的2个关键问题,即体形的空间形态复杂和需要计算的长方体数量大（≥10⁶）,应用三维网格分割与种子填充（flood-fill）思想实现快速构建三维复杂体的立方格模型算法,其时间复杂度为O(n)。该算法的主要优点是花费相对小的空间代价高效地解决大量三角面与长方体的相交和空间查询计算问题。同时,应用该算法得到的立方格预测模型的长方体被划分为边界、内部和外部,便于开展预测要素综合模拟、矿山储量计算以及三维空间分析等其他后续地质应用。特别是将种子填充思想应用于高精度立方格模型构模,具有一定的创新性。本算法不仅适用于矢量体的快速栅格化,也适用于空间非自相交曲面（例如数字高程模型）的快速栅格化。  相似文献   

Spatial distributions of organic carbon and nitro-gen and their isotopic compositions in sediments of the Changjiang Estuary and its adjacent sea area     

GAO Jianhua  WANG Yaping  PAN Shaoming  ZHANG Rui  LI Jun  BAI Fenglong 《地理学报》2008,18(1):46-58

The spatial distribution patterns of total organic carbon and total nitrogen show significant correlations with currents of the East China Sea Shelf. Corresponding to distribu-tions of these currents, the study area could be divided into four different parts. Total organic carbon, total nitrogen, and organic carbon and nitrogen stable isotopes in sediments show linear correlations with mean grain size, respectively, thus “grain size effect” is an important factor that influences their distributions. C/N ratios can reflect source information of organic matter to a certain degree. In contrast, nitrogen stable isotope shows different spatial distri-bution patterns with C/N and organic carbon stable isotope, according to their relationships and regional distributions. The highest contribution (up to 50%) of terrestrial organic carbon appears near the Changjiang Estuary with isolines projecting towards northeast, indicating the influence of the Changjiang dilution water. Terrestrial particulate organic matter suffers from effects of diagenesis, benthos and incessant inputting of dead organic matter of plankton, after depositing in seabed. Therefore, the contribution of terrestrial organic carbon to par-ticulate organic matter is obviously greater than that to organic matter in sediments in the same place.  相似文献   

多点激励下结构随机地震反应分析的反应谱方法   总被引：9，自引：3，他引：6  

李杰  李建华 《地震工程与工程振动》2004,24(3):21-29

基于随机振动理论,提出了多点激励作用下线性系统随机地震反应分析的均值反应谱方法,给出了结构峰值反应的均值、标准差以及反应平均频率的反应谱组合公式。这可以将反应谱方法推广应用到多点激励结构的抗震可靠度分析中。鉴于组合公式中谱参数和相关系数需要由烦琐的数值积分得到,本文进一步针对它们给出合理的简化计算式,从而使得建议的反应谱方法的计算效率大大增加。最后,以一个双塔斜拉桥为例,对本文方法进行了验证。基于建议方法的计算结果与Monte Carlo模拟结果吻合较好。与经典的多点激励反应谱方法(MSRS法)比较,本文方法具有其无法比拟的计算效率。  相似文献   

Multi-point source identification of sudden water pollution accidents in surface waters based on differential evolution and Metropolis–Hastings–Markov Chain Monte Carlo     

Haidong Yang  Dongguo Shao  Biyu Liu  Jianhua Huang  Xianbao Ye 《Stochastic Environmental Research and Risk Assessment (SERRA)》2016,30(2):507-522

Sudden water pollution accidents in surface waters occur with increasing frequency. These accidents significantly threaten people’s health and lives. To prevent the diffusion of pollutants, identifying these pollution sources is necessary. The identification problem of pollution source, especially for multi-point source, is one of the difficulties in the inverse problem area. This study examines this issue. A new method is designed by combining differential evolution algorithm (DEA) and Metropolis–Hastings–Markov Chain Monte Carlo (MH–MCMC) based on Bayesian inference to identify multi-point sudden water pollution sources. The effectiveness and accuracy of this proposed method is verified through outdoor experiments and comparison between DEA and MH–MCMC. The average absolute error of the sources’ position and intensity, the relative error and the average standard deviations obtained using the proposed method are less than those of DEA and MH–MCMC. Moreover, the relative error and the sampling relative error under four different standard deviations of measurement error (σ = 0.01, 0.05, 0.1, 0.15) are less than 2 and 0.11 %, respectively. The proposed method (i.e., DEMH–MCMC) is effective even when the standard deviation of the measurement error increases to 0.15. Therefore, the proposed method can identify sources of multi-point sudden water pollution accidents efficiently and accurately.  相似文献   

大兴安岭南端红山子盆地流纹岩的成因:元素和Sr-Nd-Pb同位素制约   总被引：1，自引：0，他引：1  

巫建华  解开瑞  祝洪涛  吴仁贵  刘帅 《吉林大学学报(地球科学版)》2016,46(6):1724-1739

红山子晚侏罗世早期火山盆地位于西拉木伦河-长春缝合带以南、康宝-围场-赤峰-开原断裂带以北的辽源地块,其中赋存铀钼矿床的流纹岩为肉红色流纹岩和灰白色流纹岩。为了查明流纹岩的物质来源和形成的构造背景,本文分析了流纹岩的主量元素、微量元素、稀土元素和Sr-Nd-Pb同位素组成。分析结果显示：流纹岩具有高SiO₂、K₂O和Fe₂O₃/FeO值,低Al₂O₃、CaO和MgO的特征,肉红色流纹岩比灰白色流纹岩的SiO₂含量略低、（K₂O+Na₂O）含量高和Fe₂O₃/FeO值略高;肉红色流纹岩和灰白色流纹岩均有较高的稀土含量,明显富集轻稀土,显著亏损铕;高场强元素Nb、Ta、Zr、Hf、Ce、Y、Ga和大离子亲石元素Rb、Th、U的含量较高,但大离子亲石元素Ba、Sr的含量低且变化较大,具有A₁型流纹岩、低Sr-Ba流纹岩和板内拉张构造流纹岩的微量元素特征;具有较小的（⁸⁷Sr/⁸⁶Sr）_i、较高的ε_Nd（t）、较年轻的T_DM2和较低的（²⁰⁶Pb/²⁰⁴Pb）_i、（²⁰⁷Pb/²⁰⁴Pb）_i、（²⁰⁸Pb/²⁰⁴Pb）_i,指示流纹岩是源于EMⅠ富集地幔的中元古代年轻下地壳部分熔融的产物,并在岩浆过程中经历了结晶分异。肉红色流纹岩和灰白色流纹岩的差异可能与年轻下地壳物质的成分差异有关。  相似文献   

新疆矿山环境遥感监测成果综述   总被引：6，自引：6，他引：0       下载免费PDF全文

强建华  于浩 《中国地质调查》2016,3(5):28-34

为进一步发挥遥感技术在矿山环境监测中的优势,采用多类型、多时相遥感数据,在充分分析监测区矿产开发状况、矿山地质环境和矿产资源规划执行情况等相关资料的基础上,从矿山辅助设施、道路、矿堆、矸石及地裂缝、采空塌陷等的宏观和微观形态特征出发,运用计算机自动分类和人机交互解译相结合的方法,首次对新疆矿山地质环境问题进行了全面的遥感调查与监测, 获取了全区矿山开发中土地占用与损毁、矿山地质灾害、矿山环境污染以及恢复治理状况等方面丰富翔实的基础数据,分析了矿山地质环境与不同矿种、不同开发方式之间的关系。为新疆矿山环境的保护与治理提供了重要的基础数据和技术支撑,再次显示了遥感技术为矿山管理“一张图”工程做贡献的巨大潜力。  相似文献   

中国南方大陆海岸线时空变迁   总被引：1，自引：0，他引：1  

杨磊  李加林  袁麒翔  徐谅慧  卢雪珠  王明月  赵斯 《海洋学研究》2014,32(3):42-49

海岸线变迁对于海岸带生态环境变化乃至全球变化研究具有重要意义。通过对5个时相TM影像的人机交互解译,获取1990年,1995年,2000年,2005年和2010年中国南方大陆海岸线信息,分析了各时段岸线变迁特征及变迁原因。结果表明:(1)中国南方大陆海岸线的长度和分形维度保持相对稳定,但岸线长度存在总体缩短和局部增长的演化趋势。(2)岸线海向推进的岸段占据主要部分,陆向缩退岸线仅发生在少部分岸段。(3)长江口—杭州湾南岸和珠江三角洲两个典型岸段的分析表明中国南方大陆岸线的时空变化速率与强度在不断加强。(4)在1990—2010年期间,引起中国南方大陆海岸线时空变迁的人为因素的作用比自然因素显著,并导致人工岸线比重不断增大,自然岸线比重不断下降。  相似文献