Casualties in dry bulk shipping (1963–1996)     

Stephen E. Roberts  Peter B. Marlow 《Marine Policy》2002,26(6)

In recent years, bulk carriers have been identified with high risks of catastrophic structural failure and foundering, and with heavy loss of human life. This study, based upon Lloyd's of London casualty records, identified four risk factors that had significant, independent effect upon the likelihood of a bulk carrier foundering. The risk of foundering increased with the age of the ship, and was related to the ship's flag of registration. Most importantly, however, increased risks were found for heavy cargoes of iron ore and scrap steel or iron, and for trading routes to the Far East and from Europe to North America. Additional safety measures, in particular regarding ship design and high-risk trades, may well be necessary to reduce the high casualty rates.  相似文献   

Review of resource analysis and related studies: Working group,Mathematical Geology,freie Universität Berlin     

M. Shulman  H. Burger  C. Kliem  W. Skala 《Natural Resources Research》1992,1(1):97-106

The working group Mathematical Geology of the Freie Universität Berlin was formed in 1971. We review quantitative methods used by the working group since 1983 to treat mineral exploration problems. The methods applied vary from elementary statistical analysis of multivariate exploration data to optimal strategies for selecting favorable targets, and from multiobjective decision-making for additional drill hole locations to expert systems in exploration.The methods applied are directly related to the level of information at each stage of the exploration process. Special emphasis was placed on the relationship between and evaluation of subjective and objective data. Case studies illustrating the various methods are presented for different kinds of mineral deposits and exploration environments.  相似文献   

土体微观结构定量分析系统及应用   总被引：8，自引：0，他引：8  

张礼中  胡瑞林  李向全  张永波 《地质科技情报》2008,27(1):108-112

土体微观结构图像的计算机处理是土体微观结构定量化研究的关键技术之一.在分析我国土体微观结构定量研究的进展的基础上,针对土体微观结构图像计算机处理软件对土体微观结构非确定型参数定量分析功能的不足,设计和开发了新版土体微观结构定量分析系统,以太原高阶地黄土为例,通过各夯击次数对应土样的定量化结构效应分析,探讨了其动力固结的微观结构变化规律.该系统的应用对推动我国土体微观结构的研究具有积极意义.  相似文献   

基于GIS的县域土壤重金属生态风险评价   总被引：2，自引：0，他引：2  

刘庆  王静  汪庆华  张建国  张衍毓 《测绘科学》2008,33(3):90-93

为研究经济快速发展区农田土壤中重金属的含量及污染状况,本文以浙江省慈溪市为研究对象,研究土壤中铜、汞、镉、铅、砷、铬、锌七种重金属含量特征,并采用潜在生态危害指数法对其进行评价,并绘制生态风险危害指数分级图。结果表明:土壤中除汞元素含量较高外,其他各元素含量仅稍高于当地土壤背景值。七种元素的单因子污染指数Cfi值均属于中等的污染参数,综合污染指数Cd上限值已处于高污染指数的范围,但平均值为属于中等污染水平。从潜在生态风险评价结果来看,七种元素的单项潜在生态风险参数Eri的值也只有汞达到了强生态危害,七种元素综合潜在生态危害指数RI刚刚达到中等生态危害水平,说明该区农田土壤尚处于较低的生态风险状态。生态危害指数插值结果表明,慈溪市重金属元素的高风险区分布在中南部人类活动较为活跃、城乡工业较发达的区域,在今后的土地利用中,应高度重视人类活动对土壤重金属污染的影响。  相似文献   

Calculating Pollution Indices by Heavy Metals in Ecological Geochemistry Assessment and a Case Study in Parks of Beijing   总被引：4，自引：0，他引：4  

龚庆杰  邓军  向运川  王庆飞  杨立强 《中国地质大学学报(英文版)》2008,19(3)

Pollution index is a powerful tool for ecological geochemistry assessment. The commonly used pollution indices by heavy metals in soils and sediments were classified as two types of single index and integrated index in an algorithm point of view. Four single indices of contamination factor (or concentration factor), ecological risk factor, enrichment factor, and index of geo-accumulation were illustrated, and the reference values for calculating single indices were distinguished into background levels and threshold pollution values. Eight integrated indices were divided into two groups. One group is suitable for the normal distribution single indices including the sum, average, weighted average,vector modulus, and Nemerow pollution indices, and the other for log-normal distribution including the product, root of product, and weighted power product pollution indices. Using background levels as reference values, five contamination classes were divided, and the terminologies are suggested for the single and integrated indices to unify the assessment results. Software of EGAPI was developed in a single document interface to calculate the four single and eight integrated indices by heavy metals to assess the quality of soil and sediment ecological geochemistry. Pollution indices by heavy metals of Cu,Pb, and Zn in soils in parks of Beijing were calculated using EGAPI software, and these five contamination classes and terminologies suggested in this study were evaluated and used. Results ofintegrated indices of Cu, Pb, and Zn in soils indicated that the soil qualities are unpolluted as a whole and varied from low polluted to unpolluted status from the center to the outskirts of Beijing City.  相似文献   

Accuracy assessment of lidar-derived digital elevation models   总被引：2，自引：0，他引：2  

Fernando J.  Aguilar  Jon. P.  Mills 《The Photogrammetric Record》2008,23(122):148-169

Despite the relatively high cost of airborne lidar-derived digital elevation models (DEMs), such products are usually presented without a satisfactory associated estimate of accuracy. For the most part, DEM accuracy estimates are typically provided by comparing lidar heights against a finite sample of check point coordinates from an independent source of higher accuracy, supposing a normal distribution of the derived height differences or errors. This paper proposes a new methodology to assess the vertical accuracy of lidar DEMs using confidence intervals constructed from a finite sample of errors computed at check points. A non-parametric approach has been tested where no particular error distribution is assumed, making the proposed methodology especially applicable to non-normal error distributions of the type usually found in DEMs derived from lidar. The performance of the proposed model was experimentally validated using Monte Carlo simulation on 18 vertical error data-sets. Fifteen of these data-sets were computed from original lidar data provided by the International Society for Photogrammetry and Remote Sensing Working Group III/3, using their respective filtered reference data as ground truth. The three remaining data-sets were provided by the Natural Environment Research Council's Airborne Research and Survey Facility lidar system, together with check points acquired using high precision kinematic GPS. The results proved promising, the proposed models reproducing the statistical behaviour of vertical errors of lidar using a favourable number of check points, even in the cases of data-sets with non-normally distributed residuals. This research can therefore be considered as a potentially important step towards improving the quality control of lidar-derived DEMs.  相似文献   

Formation Dynamics and Quantitative Prediction of Hydrocarbons of the Superpressure System in the Dongying Sag   总被引：1，自引：0，他引：1  

SUI Fenggui  HAO Xuefeng  LIU Qing  ZHUO Qin’gong  ZHANG Shouchun 《《地质学报》英文版》2008,82(1):164-173

Based on the theory of formation dynamics of oil/gas pools, the Dongying sag can be divided into three dynamic systems regarding the accumulation of oil and gas： the superpressure closed system, the semi-closed system and the normal pressure open system. Based on the analysis of genesis of superpressure in the superpressure closed system and the rule of hydrocarbon expulsion, it is found that hydrocarbon generation is related to superpressure, which is the main driving factor of hydrocarbon migration. Micro fractures formed by superpressure are the main channels for hydrocarbon migration. There are three dynamic patterns for hydrocarbon expulsion： free water drainage, hydrocarbon accumulation and drainage through micro fissures. In the superpressure closed system, the oil-driving-water process and oil/gas accumulation were completed in lithologic traps by way of such two dynamic patterns as episodic evolution of superpressure systems and episodic pressure release of faults. The oil-bearing capacity of lithologic traps is intimately related to reservoir-forming dynamic force. Quantitative evaluation of dynamic conditions for pool formation can effectively predict the oil-bearing capability of traps.  相似文献   

基于高分辨率遥感数据的城市居住单元交通环境质量评价——以厦门市为例     

陈志浩 《国土资源遥感》2008,19(4):53-57

居住单元是与人们生活密切相关的社区范围,其交通环境的优劣是衡量居住单元环境好坏的重要标准之一。高分辨遥感影像 的高空间分辨率特点为我们提供了研究居住单元交通环境的可能性。本文从区域交通环境、路网可达性出发,对城市居住单元交通 环境质量的遥感评价方法进行了研究,根据高分辨率遥感影像的特点构建了居住单元交通环境的多级指标评价体系,并对厦门市的 50个居住单元进行了评价分析。实验表明,利用高分辨率影像进行城市交通环境质量评价是一种成本较低,简便可行的方法。  相似文献   

基于GIS的天水市滑坡危险性评价          下载免费PDF全文

白晓华  马金辉  冯乐涛  韩庆宪 《甘肃地质》2008,(4):72-75

本文通过统计学方法提取可能影响该地区滑坡的因子。并依据二元逻辑回归结果．利用GIS空间分析和建模功能,对研究区滑坡进行建模,再由相关性等级分析方法进一步获取相关影响因子对滑坡的影响范围,最终得出该区域滑坡危险性评价图。而在不同分辨率尺度上,对滑坡产生影响的因子有所相同,当分辨率由1000m-60m时,影响因子明显增多。以逻辑回归模型自身精度、滑坡实际发生比和坡度法为模型判定标准,发现120m分辨率下的滑坡发生概率模型能有效表达研究区滑坡发生状况。  相似文献   

长江流域沿江镉异常源追踪与定量评估的方法技术研究:以长江流域安徽段为例   总被引：5，自引：1，他引：4  

赵传冬  陈富荣  陈兴仁  赵和苍  夏威岚  聂海峰  孔牧  刘飞  杨柯 《地学前缘》2008,15(5):179

长江全流域性的Cd异常是被中国正在进行的多目标地球化学调查发现的重大生态环境问题。以长江流域安徽段为研究对象,对沿江镉异常源追踪与定量评估的方法技术进行了系统研究。通过对安徽段长江干流及其主要支流悬浮物中元素含量的测量查明:悬浮物是流域内重金属元素大跨度迁移的主要载体;Cd在悬浮物中的富集程度远远大于其他重金属元素,这或许正是Cd可以形成沿江流域性异常的主要原因;长江干流悬浮物中重金属元素含量的变化明显受到沿江支流的影响。安徽段长江干流及其主要支流重金属元素输出通量定量计算结果表明:秋蒲河是安徽段重金属元素输出通量最大的支流,每年在安徽段长江两岸土壤中沉积下约4.45t的Cd。利用悬浮物加密测量、1∶5万土壤测量和岩石测量对顺安河流域Cd异常源追踪结果显示:内生金属矿床特别是铅锌矿是悬浮物中Cd的最大的供应源。采用河漫滩沉积物分层采样技术和同位素测年技术,初步恢复了研究区Cd等重金属元素沉积和污染的地球化学历史,对研究区Cd等重金属元素异常的未来演变趋势进行了预警预测。  相似文献