Generalized maximum-likelihood estimation of variance components with inverted gamma prior   总被引：2，自引：2，他引：0  

J. Grodecki 《Journal of Geodesy》1999,73(7):367-374

A new method for the estimation of variance components is presented. The proposed method combines the concept of maximum-likelihood estimation with the Bayesian approach and facilitates computationally efficient introduction of prior information into the estimation process. Received: 22 April 1998 / Accepted: 19 April 1999  相似文献   

Correlation of CYP1A1 induction, as measured by the P450 RGS biomarker assay, with high molecular weight PAHs in mussels deployed at various sites in San Diego Bay in 1993 and 1995     

J. W. Anderson  J. M. Jones  S. Steinert  B. Sanders  J. Means  D. McMillin  T. Vu  R. Tukey 《Marine environmental research》1999,48(4-5)

In 1993 collections of marine mussels (Mytilus galloprovincialis) were deployed 1 m from the water surface at six sites in San Diego Bay for 88 days. A similar mussel deployment was conducted in 1995, except the animals were deployed 1 m off the bottom and only for 32 days. After recovery from the sites, tissue was extracted with dichloromethane and the solvent extracts analyzed for chemical contaminant content and the ability to produce CYP1A1 induction in a transgenic cell line (TV101L cells). The cells used in the assay (P450 RGS) are stably transfected with a plasmid containing firefly luciferase linked to human CYP1A1 promoter sequences. Induction (fold increase compared to control) was determined by luminometry 16 h after application of small volumes (2–10 μl) of solvent extracts to cultured cells. Small mussels deployed in the Naval Station (NAV) in 1993 exhibited very high bioaccumulation of polycyclic aromatic hydrocarbons (PAHs; 52 μg/g) and polychlorinated biphenyls (PCBs), in addition to very strong induction of CYP1A1 measured by reporter gene system (RGS) responses. Large mussels deployed at the NAV station in 1993 and intermediate-sized animals placed at three stations within the NAV station in 1995 accumulated 13–29 μg PAH/g and exhibited relatively high RGS responses. Correlation of RGS responses for all mussel samples to the measured PAH concentrations was 0.85 (r²). When the concentrations of seven specific PAHs found in the samples are converted to benzo[a]pyrene equivalents, from previously derived toxic equivalency factors (TEFs) for this test system, and compared to measured RGS responses, the correlations are approximately 0.9. The results of these studies indicate that the RGS biomarker can be used as a screening tool for detection of CYP1A1-inducing compounds in tissues, and an estimate of potential human health or ecological risk from ingestion of contaminated organisms. Positive RGS responses can be followed by detailed chemical analyses of PAHs and coplanar PCBs using the same extract.  相似文献   

Integration of principal components analysis and cellular automata for spatial decisionmaking and urban simulation   总被引：2，自引：0，他引：2  

黎夏  叶嘉安 《中国科学D辑(英文版)》2002,45(6):521-529

This paper discusses the issues about the correlation of spatial variables during spatial decisionmaking using multicriteria evaluation (MCE) and cellular automata (CA). The correlation of spatial variables can cause the malfunction of MCE. In urban simulation, spatial factors often exhibit a high degree of correlation which is considered as an undesirable property for MCE. This study uses principal components analysis (PCA) to remove data redundancy among a large set of spatial variables and determine ‘ideal points’ for land development. PCA is integrated with cellular automata and geographical information systems (GIS) for the simulation of idealized urban forms for planning purposes.  相似文献   

河北西大洋水库沉积物中多环芳烃的分布、来源及生态风险评价   总被引：3，自引：0，他引：3  

赵健  周怀东  富国  赵高峰  陆瑾  王雨春  袁浩 《湖泊科学》2011,23(5):701-707

分析了河北西大洋水库沉积物中16种多环芳烃的含量及分布状况,并对其来源和生态风险进行了分析和评估.结果表明,表层沉积物多环芳烃总含量范围在422.36 - 1052.90 ng/g之间,且由库区上游到坝前逐渐升高.水库剖面沉积物中多环芳烃总含量在388.81 - 1205.56 ng,/g之间,自底层20 cm到表层多...  相似文献   

河北王快水库沉积物多环芳烃的分布、来源及生态风险评价   总被引：6，自引：2，他引：4  

赵健  周怀东  陆瑾  王雨春 《湖泊科学》2009,21(5):647-653

对王快水库沉积物中16种多环芳烃含量进行了检测,结果表明,王快水库沉积物多环芳烃含量处于中等污染水平.多环芳烃总含量由库区上游到坝前逐渐升高,多环芳烃总含量在沉积物纵向上的总体分布趋势是随着剖面深度的增加而降低,低环的萘和菲,高环的荧蒽、苯并[b]荧蒽、屈和芘是沉积物中主要的优势化合物,表层和剖面沉积物中多环芳烃的含量与有机碳含量呈正相关关系,相关系数分别为0.8154和0.9534.王快水库沉积物中多环芳烃主要来源化石燃料及生物质的燃烧,风险评价结果表明,严重的多环芳烃生态风险在王快水库沉积物中不存在,但是芴化合物含量超过了风险评价低值,可能存在着对生物的潜在危害.  相似文献   

判识水氡地震前兆的方法——以甘肃清水温泉水氡异常为例     

苏鹤军  曹玲玲  张慧  李晨桦  周慧玲 《地震》2020,40(4):198-213

地震前兆异常性质的准确判断是提高地震预测水平的前提。 据国内外相关统计, 真正具有地震预测意义的地震前兆异常数量十分有限。 因此, 厘清震前异常与地震的关系对今后异常识别意义重大。 2017年8月8日九寨沟M_S7.0地震前4个月, 甘肃清水温泉水氡出现大幅波动异常变化。 为了判断这次异常与九寨沟地震的关系, 在异常持续期间, 通过抽水实验、 水化学组分以及氢氧同位素组成分析, 并结合九寨沟地震发震构造以及其他前兆异常空间分布特征, 对水氡异常成因机理进行了深入分析。 结果表明: 对于水氡与水位的变化关系, 实验与实际观测结果一致, 都呈正相关变化; 实验中水氡变化幅度与实际观测的相当; 水化学组分以及氢氧同位素测试结果显示清水温泉水氡异常期间, 来自地壳深部的流体并未增加; 清水温泉区其他前兆没有出现明显的短期异常变化; 在空间上清水温泉与九寨沟地震震源区被两条深大断裂隔开。 因此, 清水温泉水氡大幅异常变化并非九寨沟地震的短期前兆异常, 而是企业抽水开始时间、 持续时间以及用水量不固定引起的。 该实例为地震前流体前兆异常性质的准确判定提供了更为可靠的方法和思路。  相似文献   

Fragility function development and seismic loss assessment of expansion joints     

Yu Otsuki  Masahiro Kurata  Konstantinos A. Skalomenos  Yoshiki Ikeda  Motoki Akazawa 《地震工程与结构动力学》2019,48(9):1007-1029

Expansion joints are used as a special connection equipment between adjacent buildings to accommodate the relative motions generated by wind, thermal, or earthquake loads, but they often exhibit damage during severe earthquakes. The level of damage and safety factors required to avoid loss of function are not well considered in current design practices. The objective of this paper is to provide quantitative information on the seismic damage probability of common expansion joints and the associated repair costs. The designer and engineer can refer to this information as a basis for decision making in the selection of expansion joints. Four common types of expansion joints are considered: high- and standard-performance floor and wall expansion joints, whose damage states have been evaluated recently by the authors through shaking table tests. First, the fragility functions of expansion joints for seven damage patterns are developed utilizing the test results. Next, the vulnerability of expansion joints installed between adjacent building models is assessed via incremental dynamic analysis. The recommended level of safety factor to ensure the function of expansion joints is discussed. Finally, a procedure for cost-effective selection of expansion joints is introduced, where case studies are examined using buildings with different characteristics. The presented results are deemed to be beneficial for improving the design practice of expansion joints and for reducing future seismic loss.  相似文献   

Fingerprinting petroleum hydrocarbons in plankton and surface sediments during the spring and early summer blooms in the Galician coast (NW Spain) after the Prestige oil spill   总被引：1，自引：0，他引：1  

Salas N  Ortiz L  Gilcoto M  Varela M  Bayona JM  Groom S  Alvarez-Salgado XA  Albaigés J 《Marine environmental research》2006,62(5):388-413

Plankton samples (20-350 microm and >350 microm) collected at three transects along the Galician coast (NW Spain) were analysed for individual aliphatic and aromatic hydrocarbons by GC-MS. Sample collection was performed in April-July 2003, after the Prestige oil spill (November 2002), to determine whether the hydrocarbons released into the water column as a consequence of the spill were accumulated by the planktonic communities during the subsequent spring and early summer blooms. Surface sediments were also collected to assess the presence of the spilled oil, removed from the water column by downward particle transport. Plankton concentrations of PAHs (Sigma14 parent components) were in the range of 25-898 ng g(-1)dw, the highest values being close to coastal urban areas. However, the individual distributions were highly dominated by alkyl naphthalenes and phenanthrenes, paralleling those in the water dissolved fraction. The detailed study of petrogenic molecular markers (e.g. steranes and triterpanes, and methyl phenanthrenes and dibenzothiophenes) showed the occurrence of background petrogenic pollution but not related with the Prestige oil, with the possible exception of the station off Costa da Morte in May 2003, heavily oiled after the accident. The dominant northerly wind conditions during the spring and early summer 2003, which prevented the arrival of fresh oil spilled from the wreck, together with the heavy nature of the fuel oil, which was barely dispersed in seawater, and the large variability of planktonic cycles, could be the factors hiding the acute accumulation of the spilled hydrocarbons. Then, with the above exception, the concentrations of PAHs found in the collected samples, mostly deriving from chronic pollution, can be considered as the reference values for the region.  相似文献   

Hyperspectral analysis of soil polluted with four types of hydrocarbons     

Laura A. Reséndez-Hernández  Daniel Prudencio-Csapek 《国际地球制图》2019,34(9):925-942

In this study, a high spectral resolution GER-2600 spectroradiometer was used to obtain the spectral data of soil samples that were polluted with four different types of petroleum–hydrocarbons products: Diesel, Gasoline, Crude Oil and Fuel Oil. The polluted soil samples were prepared in the laboratory at five concentrations levels: unpolluted soil, 2500, 100,000, 250,000 ppm and pure pollutant. Spectral data were pre-processed and then analysed with various approaches: Principal Components Transformation and ANOVA, Spectral Angle Mapper (SAM), Hydrocarbon Index (HI) and Spectral Mixture Analysis (SMA). The results showed that it was possible to determine the different spectral response between clean soil and some of the polluted soils: crude oil at concentrations higher than 100,000 ppm were the easiest to recognize; while samples polluted with gasoline at concentrations below 250,000 ppm were the most difficult to distinguish from non-polluted samples.  相似文献   

加权整体最小二乘的验后估计在三维坐标转换中的应用     

王祝安  陈义  毛鹏宇 《大地测量与地球动力学》2018,38(2):216-220

在求解三维小角度坐标转换EIV模型的过程中，顾及到两套坐标系下点坐标初始单位权方差可能不同导致定权不准确的问题，应用Helmert方差分量估计方法，对加权整体最小二乘的随机模型进行验后估计，从而重新分配观测向量和系数矩阵的权，使得解算模型更加合理。算例证明，利用该方法求解坐标转换参数的精确度有所提高，参数估值更接近真值。  相似文献