Processes governing river water quality identified by principal component analysis

The present study demonstrates the usefulness of principal component analysis in condensing and interpreting multivariate time‐series of water quality data. In a case study the water quality system of the lock‐regulated part of the River Neckar (Germany) was analysed, with special emphasis on the oxygen budget. Pooled data of ten water quality parameters and discharge, which had been determined at six stations along a 200 km reach of the river between the years 1993 and 1998, were subjected to principal component analysis. The analysis yielded four stable principal components, explaining 72% of the total variance of the 11 parameters. The four components could be interpreted confidently in terms of underlying processes: biological activity, dilution by high discharge, seasonal effects and the influence of wastewater. From analysing the data of single stations separately, these processes were found to be active throughout the complete reach. Considering the oxygen budget of the river, the variance of biological activity, representing the counteracting processes of primary production and microbial degradation, was found to be most important. This principal component explained 79% of the observed variance of oxygen saturation. In contrast, the analysis of a reduced data set from the 1970s showed that oxygen saturation was then dominated by discharge and temperature variations. The findings indicate that the oxygen budget used to be governed directly by the emission of degradable matter, whereas nowadays eutrophication is most important for extreme oxygen concentrations. Therefore, controlling eutrophication has to be the primary goal, in order to mitigate the rare episodes of pronounced oxygen over‐ and undersaturation in the future. Copyright © 2002 John Wiley & Sons, Ltd.     

STUDY ON FUNCTION OF COMPONENTS OF DYNAMIC SYSTEM OF TOURISM DEVELOPMENT IN DEVELOPED REGION —A Case Study of Foshan in Guangdong Province

In the forming of the Dynamic System of Tourism Development(DSTD)in developed regions from the view of supply side,the Dhlphi Method and the Analytical Hierarchy Process (AHP) are used to count the weight of each component of the DSTD.It has been found that the attraction subsystem is the most important one of the three subsystems at the first hierarchical level of DSTD,which means that tourist attractions are always the principal factors for regional tourism development,even in developed regions.But it is also noteworthy that the significance of the attraction subsystem is not dominant in the DSTD.At the second hierarchical level,the physical attraction subsystem rand No.1,while the weight of the non-physical attraction subsystem is just a little larger than the weight of the hardware subsystem and that of software subsystem.And the weights of the three components in the medium subsystem are similar.The top 3 factors at the third hierarchical level are scenic spot,location and regional economic impact.The result verifies the conclusions of qualitative analysis,which depends on the market research and the study of historical date,that the most important compo-nent of the DSTD in Foshan is the impact of the developed economy.Knowing the weight of each component of the DSTD can be helpful to make out the most useful force,furthermore to determine the future orientation for regional tourism develop-ment.     

Study of time-related variability within the genusAstarte (bivalvia): A multivariate approach

A morphometric analysis of two closely related species Astarte omaliiand Astarte basterotiwas made. Specimens were sampled from three successive stratigraphic levels of the Pliocene deposits of northern Belgium. Two chronological subspecies were distinguished—Astarte omalii omaliiand Astarte omalii basteroti.     

用GPS监测城市地面沉降的可行性研究

研究了用GPS观测取代常规水准测量方法监测城市地面沉降变化的可行性。在宁波市进行了两期GPS测量和水准测量，观测中并采取一定的措施以获得高精度的高程分量。顾及到对流层延迟的影响，采用Saastamcinen模型改正对流层延迟的干分量部分，用分段线性方法来估计对流层的湿分量变化。用Bernese软件对数据进行处理，获得了毫米级的高程精度。实际算例证明，用GPS测量代替水准测量来监测城市地面沉降变化是可行的。     

基于ComGIS的典型地物波谱特性数据库研究

典型地物波谱数据库是遥感定量分析和计算机智能提取地物类型的基础数据,是进行地物识别的重要参照系,可用于遥感技术应用项目的数据分析。本文介绍了典型地物波谱数据库系统软件设计的研究内容,包括系统结构的组织、系统环境的集成、功能设计,系统界面设计以及系统的关键技术分析等。     

抗差Helmert估计在BDS/GPS组合定位权比分配中的应用

BDS与GPS双系统组合定位时,每个子系统需要进行定权,不同系统间的差异性会导致定权不准确。为提升组合定位精度,本文提出一种基于抗差Helmert方差分量估计的组合定位算法（RH算法）。首先,建立Helmert方差分量后验估计模型,区分多类型、不同精度的观测值,实现系统间权值的动态分配;然后,构建基于IGGⅢ方案的改进等价权函数,调整含粗差观测量的权值,解决观测值易存在粗差导致Helmert模型收敛失真的问题;最后,通过测试实际采集的双系统观测数据,验证算法的有效性和准确性。     

地磁逐日比异常电磁学成因的进一步分析

基于地磁逐日比异常期间地磁垂直分量日变化幅度变大或变小的统计结果,发现地磁逐日比高值异常是由异常日的地磁垂直分量日变化幅度变小和异常前一天的日变化幅度变大所致。其中,异常日的日变化幅度变小可能是地磁逐日比异常的主要因素,但异常前一天的日变化幅度变大也是异常成立的重要因素。此外,引用前人感应电流假说,结合统计结果进行了机理解释,研究结论进一步证实了前人对该方法的机理推测。     

基于PCA-SVM算法对稀土元素与稀土判别指标耦合数据集的铀矿床分类

不同类型铀矿床的沥青铀矿/晶质铀矿具有不同的稀土元素组成,其组成可作为判别铀矿床类型的重要指标。采用基于Python语言的主成分分析（principal component analysis,PCA）与支持向量机（support vector machines,SVM）结合的分类模型,对收集到的全球已知6种类型铀矿床的216组沥青铀矿/晶质铀矿稀土元素数据进行研究。以216组数据为训练集,通过数据清洗、特征缩放、PCA特征提取、网格搜索和交叉验证参数寻优构建SVM分类模型,对24组同变质型胡家峪晶质铀矿进行智能识别。研究结果显示：仅使用稀土元素的14维训练集最优模型判定胡家峪晶质铀矿类型的测试准确率为0.4%;由稀土元素、稀土总量、轻重稀土比、铕异常组成的17维训练集最优模型的测试准确率为75.0%,较14维训练集提高74.6%,模型泛化能力强;而通过传统稀土元素配分曲线、w（ΣREE）-（LREE/HREE）_N图解不能有效判定胡家峪晶质铀矿类型。本次研究表明,PCA-SVM算法对增有传统稀土判别指标数据集进行挖掘可有效厘定铀氧化物成因类型,效果明显优于单纯的稀土元素数据集以及传统的稀土配分曲线、w（ΣREE）-（LREE/HREE）_N图解。     

Application of Rare Earth Elements of the Marine Carbonate Rocks in Paleoenvironmental Researches

The pattern, contents and ratios of Rare Earth Elements (REE) from marine carbonates play an important role in the paleo-environmental researches. As result of the REE's source being variable, which includes marine carbonates, detrital input and diagenesis, the overall assessment for the reliability of REE's data is necessary. Furthermore, appropriate analytical method is vital for the reliable contents of REE. This paper reviewed the geochemical properties, analytical and data processing methods, feasibility verification and paleo-environmental application of carbonates REE. The patterns of REE, which provide theoretical basis for the provenance and depositional environment of carbonates, are various with different sources. Cerium, as a redox sensitive element, is a key proxy for the reconstruction of paleo-redox conditions. There are two available analytical methods, acid-leaching method and direct LA-ICP-MS analytical method, to extract REE of seawater preserved in marine carbonate rocks. The contamination from detritus and diagenetic alteration can be detected by the correlations of various elements or element ratios. The REE of marine carbonate has been well applied to reconstruct the environment changes during the Precambrian, Permian-Triassic transition and Cenozoic.     

The start‐up of the Dolomia Principale/Hauptdolomit carbonate platform (Upper Triassic) in the eastern Southern Alps

Wide carbonate platform environments developed on the western passive margin of the Tethys during the Late Triassic, after a major climate change (Carnian Pluvial Episode) that produced a crisis of high‐relief microbial carbonate platforms. The peritidal succession of this epicontinental platform (Dolomia Principale/Hauptdolomit, Dachstein Limestone) is widespread in the Mediterranean region. However, the start‐up stage is not fully understood. The original platform to basin depositional geometries of the system have been studied in the north‐eastern Southern Alps, close to the Italian/Slovenian boundary where they are exceptionally preserved. Sedimentological features have been investigated in detail by measuring several stratigraphic sections cropping out along an ideal depositional profile. The analysis of the facies architecture allowed reconstruction of the palaeoenvironments of the Dolomia Principale platform during its start‐up and early growth stages in the late Carnian. The carbonate platform was characterized by an outer platform area, connected northward to steep slopes facing a relatively deep basin. Southward, the outer platform was connected to inner sheltered environments by a narrow, often emerged shelf crest. Behind this zone, carbonate sedimentation occurred in shallow lagoons and tidal flats, passing inward to a siliciclastic mudflat. The Dolomia Principale platform was initially aggrading and able to keep pace with a concomitant sea‐level rise, and then prograding during the late Carnian. This stratigraphic interval was correlated with the Tuvalian succession of the Dolomites, allowing depiction of the depositional system on a wide scale of hundreds of kilometres. This large‐scale depositional system presents features in common with some Palaeozoic and Mesozoic carbonate build‐ups (for example, the Permian Capitan Reef complex, Anisian Latemar platform), both in terms of architecture and prevailing carbonate producers. A microbial‐dominated carbonate factory is found in the outer platform and upper slope. The recovery of high‐relief microbial carbonate platforms marks the end of the Carnian Pluvial Episode in the Tuvalian of Tethys.