基于Copula函数的联合概率法在海洋工程中的应用

本文介绍了Copula函数的定义、属性和几种特殊的Copula函数.将Copula函数应用到近海工程中,用其建立了最大有效波高和最大风速的联合分布函数并检验,结果表明:Copula函数能够比较好的模拟实际的联合概率分布。通过Copula方法,可以由边缘分布和一个连接它们的Copula函数来得出联合分布函数,发挥其描述相关性尤其是尾部相关性的优势。该方法在近海工程的工程可靠度、设计标准和失效概率的计算中具有广泛的应用前景。     

我国南海4个青蛤野生群体的形态差异分析

用8个形态性状比较我国南海4个野生青蛤群体间的形态变异。聚类分析表明,湛江群体和汕头群体的形态较接近,海口群体的趋异最大。主成分分析表明,主成分1、2、3的贡献率分别为26.441%、21.104%、15.884%,累计贡献率为63.428%。逐步判别分析结果显示,4个群体形态差异显著(P<0.01)。建立了4群体判别函数,其判别准确率P1为51.4%～71.4%,判别分析准确率P2为60%～75.8%,4群体的综合判别率为64.3%。Mantel-test检验结果表明,我国南海青蛤不同地理群体的欧式距离与地理距离没有明显的相关性(r=0.4227,P=0.3910)。     

A statistical approach for determining the environment impact of surface sediments from the Dongting Lake area,central China

The Dongting Lake, the second biggest freshwater lake in China, consists of three wetlands of national importance, namely the East Dongting Lake, the South Dongting Lake, and the West Dongting Lake. Surface sedi-ments were sampled from 57 locations across the lake. Nutrient concentrations [total organic carbon (TOC), total N (TN) and total P (TP)] and 16 element concentrations (Al, As, B, Ca, Cd, Cr, Cu, K, Fe, Hg, Mn, Ni, Pb, Si, Ti and Zn) in the sediments were measured to investigate the impact of industrialization along the lake's coastline and sev-eral tributaries on the profiles of nutrients and heavy metals in the lake's surface sediments. R-mode cluster analysis (CA) was used to integrate geochemical data. The result showed that euthophication of the Dongting Lake resulted mainly from TN and TOC. The main polluting trace metals are Hg, As, Cd, Zn, Pb and Mn, which are largely ad-sorbed on clay minerals or Fe/Mn oxides, or deposited as carbonates. Principal component analysis (PCA) revealed the source of micropollutants. The worst affected district by heavy metals is the East Dongting Lake, the pollution sources may originate mainly from the Xiangjiang drainage area. The results demonstrated that multivariate methods are the potentially great tools for the interpretation of the environmental data on lake sediments.     

准噶尔盆地玛湖凹陷夏子街扇区三叠系百口泉组绿帘石分布特征及成因*

准噶尔盆地玛湖凹陷夏子街扇区三叠系百口泉组重矿物中绿帘石占绝对优势,且含量变化大。为了解研究区绿帘石的分布特征及其成因,利用重矿物、能谱及扫描电镜等资料,借助聚类分析和相关性分析等多元统计方法,对绿帘石的分布特征及成因进行了系统的研究。结果表明: (1)根据绿帘石含量可将研究区划分为绿帘石高值区、中值区和低值区;(2)绿帘石高值区位于扇三角洲前缘亚相,中值区和低值区主要位于扇三角洲平原亚相,且低值区比中值区更靠近物源;(3)绿帘石高值区不仅有岩浆绿帘石,自生绿帘石也普遍发育,因此绿帘石含量高;中值区绿帘石主要为岩浆绿帘石;低值区地层遭受了抬升剥蚀,溶蚀淋滤作用对搬运沉积的绿帘石破坏强烈,故显示低值。     

北京东郊722土壤垂向剖面重金属污染的磁学响应及其统计意义

对北京城东附近某苗圃内典型的土壤污染剖面进行了环境磁学和地球化学分析,发现某些重金属(Pb、Zn、Sr、Ba、Cu)和磁性参数呈现相同的垂向变化趋势,都在37cm以上显示高值区,磁化率均值达到192.02×10-8m3/kg,如Pb含量达到67.62mg/kg,而在37cm以下,明显属低值区,磁化率均值只有18.38×10-8m3/kg,Pb含量也只有23.43mg/kg.借助于指标聚类分析和主成分分析方法,揭示出各种指标之间的内在联系,表明磁参数与Pb、Zn、Sr、Ba、Cu等元素显著相关,彼此的相关系数都达到0.90以上,属于同一类别的隶属度在80%以上,说明磁指标可以作为这些重金属污染的一种代用指标.利用模糊C均值聚类分析分辨出了土壤上部污染物堆积层和下部未污染土壤背景2种不同的特征段.     

Identifying sources and hazardous risks of heavy metals in topsoils of rapidly urbanizing East China

With rapid economic and social development, soil contamination arising from heavy metals has become a serious problem in many parts of China. We collected a total of 445 samples (0–20 cm) at the nodes of a 2 km×2 km grid in surface soils of Rizhao city, and analyzed sources and risk pattern of 10 heavy metals (As, Cd, Co, Cr, Cu, Hg, Mn, Ni, Pb and Zn). The combination of Multivariate statistics analysis and Geostatistical methods was applied to identify the sources and hazardous risk of heavy metals in soils. The result indicated that Cr, Ni, Co, Mn, Cu, and As were mainly controlled by parent materials and came from natural sources. Cd and Hg originated from anthropogenic sources. Pb and Zn, belonging to different groups in multivariate analysis, were associated with joint effect of parent materials and human inputs. Ordinary Kriging and Indicator Kriging suggested that single element and elements association from the same principal components had similar spatial distribution. Through comprehensive assessment on all elements, we also found the high risk areas were located in the populated urban areas and western study area, which could be attributed to the higher geological background in the western part and strong human interference in the eastern part.     

安徽省地质灾害气象风险预警系统方法研究

地质灾害气象风险预警是地质灾害防范的关键环节,对增强灾害防御能力,变被动救灾为主动防灾避灾具有重要意义。本研究采用确定性系数法和基于CF的权重确定方法,计算了各评价单元的潜势度。通过建立多元回归预测模型,将基于潜势度、预报雨量、有效雨量的气象风险预警系统方法应用于安徽省地质灾害气象风险预警工作中,并建立了一套完整的从数据准备、会商分析、预警制作、签批发布,到预警预报结果反馈信息收集的预警预报工作流程,取得了较好的效果。     

云南思姑锡矿区地质、化探、遥感多元信息综合找矿研究

文章通过对地质、遥感、地球化学等多元地学数据的找矿信息提取和综合处理技术研究,形成了一套多元信息综合找矿的技术.选择Sn、Cu、Pb、Zn、Ag、M0等6个元素,对矿区原生晕进行了R型聚类分析、因子分析等分析,并以传统化探处理方法(平均值+n×标准差)确定异常下限圈定异常区域;将遥感、化探与地质信息融合并进行综合分析,总结出矿区矿体的产出状态和成矿地质特征.经野外工作、探槽及坑道验证,证实了预测的准确性.     

寒区湿地春、夏浮游植物群落划分——以三江平原安邦河湿地为例

运用多元分析方法对安邦河湿地春、夏浮游植物群落进行划分,结果表明,两季节均可分为3个组群:(1)核心区组群,春季为绒毛平板藻.四角盘星藻群落,夏季为四角盘星藻群落;(2)边缘区组群,春季为梅尼小环藻-尖针杆藻群落,夏季为鱼腥藻-铜绿微囊藻.梅尼小环藻群落;(3)莲花池组群,春季为地中尖头藻群落,夏季为银灰平裂藻群落.各群落的种类组成、数量及多样性存在季节差异,与寒区环境因子季节变化相关.     

广东省冬季逐日最低气温的预报方法

为了能结合数值预报产品做好广东省逐日最低气温的预报,利用1998~2007年冬季(11月~次年2月)美国NCEP/NCAR再分析资料和常规气象观测资料,选取20°~27.5°N,107.5°~117.5°E区域内的海平面气压、850 hPa温度、850 hPa相对湿度、850 hPa纬向风(u)、850 hPa经向风分量(v)和500hPa位势高度等6个要素作为预报因子,以韶关、梅州、广州、阳江、汕头等5个站分别作为广东5个部分的代表站,采用能选取"最优"因子的逐步回归方法建立5个代表站的11月~次年2月逐日的最低气温预报方程,并对预报方程进行检验。结果表明:采用逐步回归预报方法建立的广东省5个代表站的逐日最低气温预报方程具有一定的预报能力,但也存在预报结果比实况偏低的不足。