Modelling Short‐Scale Variability and Uncertainty During Mineral Resource Estimation Using a Novel Fuzzy Estimation Technique     

Khan Muhammad  Hylke J. Glass 《Geostandards and Geoanalytical Research》2011,35(3):369-385

For mineral resource assessment, techniques based on fuzzy logic are attractive because they are capable of incorporating uncertainty associated with measured variables and can also quantify the uncertainty of the estimated grade, tonnage etc. The fuzzy grade estimation model is independent of the distribution of data, avoiding assumptions and constraints made during advanced geostatistical simulation, e.g., the turning bands method. Initially, fuzzy modelling classifies the data using all the component variables in the data set. We adopt a novel approach by taking into account the spatial irregularity of mineralisation patterns using the Gustafson–Kessel classification algorithm. The uncertainty at the point of estimation was derived through antecedent memberships in the input space (i.e., spatial coordinates) and transformed onto the output space (i.e., grades) through consequent membership at the point of estimation. Rather than probabilistic confidence intervals, this uncertainty was expressed in terms of fuzzy memberships, which indicated the occurrence of mixtures of different mineralogical phases at the point of estimation. Data from different sources (other than grades) could also be utilised during estimation. Application of the proposed technique on a real data set gave results that were comparable to those obtained from a turning bands simulation.  相似文献   

Application of a vessel monitoring system to advance sustainable fisheries management—Benefits received in Taiwan   总被引：1，自引：0，他引：1  

Shui-Kai Chang 《Marine Policy》2011

Vessel monitoring systems (VMS) are considered important instruments for fisheries monitoring, control and surveillance (MCS) to reverse the current depressed state of the world’s fisheries, and have been mandated worldwide by fishery management agencies. The essential function of the system is to provide near-real time vessel position; the potential applications could, however, be more than that. This study explores the additional benefits, with practical examples, that Taiwan has received from implementing the system: in improving the quantity and quality of logbooks recovered, obtaining access to fishery-independent fishing effort estimates and prompt catch/effort reporting, enabling the possibility of regional management and understanding of both fleet dynamics and vessel behavior, and increasing efficiency of vessel safety protection. For other distant-water fishing nations, Taiwan’s experiences serve to demonstrate how the application of VMS technology can advance sustainable fisheries management.  相似文献   

Defining dynamic pelagic habitats in oceanic waters off eastern Australia     

A.J. Hobday  J.W. YoungC. Moeseneder  J.M. Dambacher 《Deep Sea Research Part II: Topical Studies in Oceanography》2011,58(5):734-745

Although many species in the pelagic ocean are widespread, they are not randomly distributed. These species may have associations with particular water masses or habitats, but to best understand patterns in the ocean, these habitats must be identified. Previous efforts have produced static or seasonal climatologies, which still represent smearing over habitats. The Eastern Tuna and Billfish Longline Fishery (ETBF) targets a range of high trophic level species in oceanic waters off eastern Australia. In this study, dynamic ocean habitats in the region were identified for each month based on cluster analysis of five oceanographic variables averaged at a monthly time scale and a spatial scale of 0.5° for the period 1995-2006. A total of seven persistent habitats were identified off eastern Australia with intra and interannual variation in size and location, indicating the importance of spatial and temporal variation in the dynamics of the region. The degree to which these dynamic habitats were distinguished was tested using (i) stable isotope analysis of top fish predators caught in the region and (ii) estimates of variation in estimated abundance generated from catch data from the fishery. More precise estimates (measured as lower total CV) of isotopic values from swordfish (Xiphias gladius), yellowfin tuna (Thunnus albacares) and albacore (Thunnus alalunga) were obtained for 4 of 6 isotope comparisons using the dynamic habitat groupings, which indicate that stratifying by pelagic habitat improved precision. Dynamic habitats produced more precise abundance estimates for 7 of 8 large pelagic species examined, with an average reduction in total CV of 19% compared to when abundance was estimated based on static habitat stratification. These findings could be used to guide development of effective monitoring strategies that can distinguish patterns due to environmental variation, and in the longer term, climate change.  相似文献   

基于GPS单点测速的海浪测量方法初探     

单瑞  刘焱雄  赵铁虎  冯义楷 《海洋通报》2011,30(5):529-534

首先分析比对了已有的测波方法,阐述了将GPS单点测速应用到测波中的优点.然后讨论了基于多普勒频移的测速方法,并分析了各类误差对测速精度的影响.最后利用静态数据进行动态测速模拟试验和实测动态数据测速与RTK (Real Time Kinematic,实时动态测量系统)位置差分测速进行—致性检验.结果表明,使用静态数据采用...  相似文献   

导航雷达近海回波图像丢帧内插技术研究     

陈壮杰  宋占杰  高成志  齐占辉  张锁平 《海洋技术学报》2011,30(1):68-71

研究了在连续的X波段导航雷达图像序列中丢失一帧图像状态下的一种快速修复算法.该算法主要采用基于运动估计与运动补偿的视频序列修复技术进行插帧修复.具体步骤是根据雷达图像中像素点的运动特点,采用改进的三步搜索算法并结合双向运动估计进行搜索,然后对矢量场进行后续处理,最后内插出重建帧.为了提高图像修复的精度,还引入了亚像素运...  相似文献   

基于广义极值分布的设计波高推算   总被引：1，自引：0，他引：1  

陈子燊  刘曾美  路剑飞  于吉涛 《热带海洋学报》2011,(3)

简介了广义极值分布函数及其3种参数估计方法,包括极大似然(ML)、线性矩(LM)和间隔最大积(MPS)估计的计算方法。使用广义极值分布函数推算了北部湾涠洲岛海域3个波向的年波高极值序列设计波高,并与Weibull分布、Gumbel分布和皮尔逊Ⅲ型分布的推算结果加以对比。分析表明,涠洲岛海域极值波高服从于广义极值Ⅲ型分布,拟合优度检验结果表明广义极值分布能更好地拟合极值波高;MPS方法是一种优良的参数估计法,推算的设计波高可作为海岸环境工程设计的首要参考值。  相似文献   

静态精密单点定位中对流层延迟估计     

李凯锋  欧阳永忠  陆秀平  吴太旗  任来平 《海洋测绘》2011,31(6):12-15

首先介绍了三种对流层误差改正模型,然后把模型改正值作为先验值,将天顶延迟的剩余误差作为待定参数,分别用卡尔曼滤波和最小二乘两种估计方法计算对流层的残余量;实验证明Saastamoinen模型优于后两种模型,并利用实测气象参数计算对流层延迟,结果表明标准模型与实测气象参数对静态精密单点定位中对流层延迟量的计算结果影响不大...  相似文献   

基于MODIS数据定量判识沙尘暴方法的对比研究     

陶然  于曼竹 《地理信息世界》2011,9(3):51-54

利用MODIS数据,结合具体实例,对比研究当前几种利用光谱特征定量判识沙尘暴的方法。从理论上剖析各方法的原理,分析其优劣,并提出一套新的算法的组合方式。研究结果表明,新的组合算法有不小的改进：①大大降低了单一算法在不同时间或地区图像中阈值取值不稳定的影响,减少了图像噪声造成的误判,增强了其通用性和稳定性;②明显减弱了太...  相似文献   

地形湿度指数算法误差的定量评价   总被引：2，自引：0，他引：2  

包黎莉  秦承志  朱阿兴 《地理科学进展》2011,30(1):57-64

地形湿度指数(TWI)能够定量指示地形对土壤湿度空间分布的控制,是一种应用广泛的地形属性.目前基于栅格DEM的TWI计算方法结果各异,因此有必要对'TWI算法进行定量评价.对TWI算法通常是应用实际DEM数据进行评价.但实际DEM中存在的数据源误差会干扰对算法误差的评价.针对该问题,本文介绍了一种用不含数据源误差的人造...  相似文献   

密云水库周边山区滑坡泥石流易发区预估   总被引：4，自引：1，他引：3  

宋杨  程维明  柏延臣  万丛  申元村  蒋艳  刘海江 《地理科学进展》2011,30(3):343-351

滑坡、泥石流等地质灾害的易发度主要是地质灾害自然属性特征的体现,它与孕灾环境的各项因子密切相关。这些因子包括地形地貌、流域水文、构造等内部条件因子以及地震、降雨等外部触发因子。为突出反映滑坡及泥石流主导因子的作用,本文参考了许多研究所采用的评价方法和因子选择,重点选取对该地区滑坡及泥石流发生区域分析评价起一定主导作用的、便于研究区域数据资料与空间资料匹配、关系密切的几个指标,包括地形地貌要素(坡度、坡向、坡形、相对高差、地貌类型)、环境要素(植被指数、河网密度、洪水淹没范围)、构造要素(距断层的距离、断层密度、地质岩性),通过对这些因子的敏感性进行分析,采用专家打分方法确定每种要素及因子的权重,借助因子加权叠加办法得出研究区地质灾害易发程度空间分布,用于表示其可能发生的统计意义上的可能性(概率),该研究对于区域地质灾害预防具有一定的适用价值。  相似文献