嵌入式PC核能谱数据采集系统

以PC／104为平台的核心能谱数据采集系统体积小、功耗低、重量轻、功能强、电路设计简单、工作稳定、能满足野外原位无损测量的要求。     

Substrate damage and recovery after giant clam shell mining at remote coral reefs in the southern South China Sea

Giant clam shell mining(GCSM),a unique phenomenon occurring at remote coral reefs in the southern South China Sea(SCS),forms striking scars on the reef flats and damages the reef flat substrate.Through image analyses at three times(2004.02.02,2014.02.26,and 2019.04.10)and in situ surveys at Ximen Reef,a representative site that has experienced GCSM,we quantified the GCSM-generated substrate damage and the corre-sponding recovery.GCSM was estimated to have occurred sometime between 2012 and 2014,causing reduction in live coral subarea and formation of micro-relief as trenches and mounds.GCSM-generated damage was restricted to the reef flat.After GCSM,coral and algae subarea increased,and the trenches and mounds tended to be filled and eroded,rep-resenting a natural recovery of the substrate.The legal prohibition on human disturbances at the coral reefs contributed to substrate recovery at Ximen Reef.This case also implied that recovery of the other coral reefs that suffered from GCSM is possible.     

基于PDA的嵌入式土地执法系统的设计与实现

系统研究了以PDA为平台的土地执法系统的设计思路,详细介绍了各个模块的功能和关键技术的实现方法。在Windows Mobile操作系统下设计并实现了基于PDA的嵌入式土地执法系统,系统集成了"3S"优势,又有移动执法的功能,从而提高了土地执法工作中的效率和精度。     

流域水环境监测管理系统设计与应用——以云南松华坝流域为例

流域水环境监测管理系统建设将对当地水环境信息化建设和业务部门工作效率提高起到促进作用,为水环境管理与保护决策提供必要依据。文章对信息采集、传输、主要技术和系统总体结构做了研究.介绍了系统功能和实现方法。系统本着低成本、开发简单、快捷、方便的原则,采用可视化开发工具、GIS组件、Access数据库集成模式,开发C/S结构的应用系统。系统实现了基本GIS功能、信息管理、水质模拟、水环境容量计算、污染源分析等功能,满足当前业务数据分析管理需要,达到了一定辅助决策的目的。     

Effects of the dynamic cross-interaction in the seismic analysis of multiple embedded foundations

A boundary element formulation of the substructure deletion method is presented for the seismic analysis of the dynamic cross-interaction between multiple embedded foundations. This approach is particularly suitable for three-dimensional foundations of any arbitrary geometrical shape and spatial location, since it requires only the discretization of the foundations’ surfaces. The surrounding soil is represented by a homogeneous viscoelastic half-space while the foundations are assumed to be rigid and subjected to incoming SH-, P-, and SV-waves arbitrarily inclined in both the horizontal and vertical planes. The proposed methodology is tested for the case of two identical embedded square foundations for different values of the foundations’ embedment and distance. The effects of the cross-interaction are outlined in the components of the impedance matrix and of the foundation input motion. © 1997 John Wiley & Sons, Ltd.     

山东半岛东北部滨浅海区表层沉积物粒度及矿物成分

对山东半岛东北部滨浅海区海底表层沉积物的粒度和矿物组分进行了分析,探讨了其物源及其粒度分布特征与沉积动力条件的关系。结果表明,本区表层沉积物主要来源于现代黄河物质,底质类型主要有黏土质粉砂、砂质粉砂和粉砂质砂3种类型,其中黏土质粉砂约占该区沉积物分布面积的60%以上,呈“Y”形由西北向东南展布。研究区沉积作用的主控因素是黄海沿岸流,各粒级组分的分布和粒度参数特征与海流的方向和强弱有明显的相关性。     

尺度叠加高斯相关模型在GRAPES-RAFS中的应用

背景误差水平相关模型影响着分析增量的结构,同时也决定着不同尺度上分析增量信息的多少.为了提高中小尺度系统的分析质量,研究尺度叠加高斯相关模型的特征及其在三维变分同化系统中的应用效果.通过分析高斯模型和尺度叠加高斯模型的空间特征,以及它们的拉普拉斯算子和谱响应函数的特征,同时依据统计的背景误差特征来改进背景误差水平相关模...     

ESTIMATING INFILTRATION PARAMETERS FROM BASIC SOIL PROPERTIES

Infiltration data were collected on two rectangular grids with 25 sampling points each. Both experimental grids were located in tropical rain forest (Guyana), the first in an Arenosol area and the second in a Ferralsol field. Four different infiltration models were evaluated based on their performance in describing the infiltration data. The model parameters were estimated using non-linear optimization techniques. The infiltration behaviour in the Ferralsol was equally well described by the equations of Philip, Green–Ampt, Kostiakov and Horton. For the Arenosol, the equations of Philip, Green–Ampt and Horton were significantly better than the Kostiakov model. Basic soil properties such as textural composition (percentage sand, silt and clay), organic carbon content, dry bulk density, porosity, initial soil water content and root content were also determined for each sampling point of the two grids. The fitted infiltration parameters were then estimated based on other soil properties using multiple regression. Prior to the regression analysis, all predictor variables were transformed to normality. The regression analysis was performed using two information levels. The first information level contained only three texture fractions for the Ferralsol (sand, silt and clay) and four fractions for the Arenosol (coarse, medium and fine sand, and silt and clay). At the first information level the regression models explained up to 60% of the variability of some of the infiltration parameters for the Ferralsol field plot. At the second information level the complete textural analysis was used (nine fractions for the Ferralsol and six for the Arenosol). At the second information level a principal components analysis (PCA) was performed prior to the regression analysis to overcome the problem of multicollinearity among the predictor variables. Regression analysis was then carried out using the orthogonally transformed soil properties as the independent variables. Results for the Ferralsol data show that the parameters of the Green–Ampt and Kostiakov model were estimated relatively accurately (maximum R² = 0.76). For the Arenosol, use of the second information level together with PCA produced regression models with an R² value ranging from 0.38 to 0.68. For the Ferralsol, most of the variance was explained by the root content and organic matter content. In the Arenosol plot, the fractions medium and fine sand explained most of the observed variance.     

台湾海峡鱼类8种寄生线虫幼虫的特征排序

本文对中国台湾海峡鱼类寄生线虫幼虫的形态特征进行了聚类分析和主成份分析。针对目前鱼类寄生线虫形态分类中存在的问题,尤其是难以区分是形态学差异还是个体间变异,以及主成份分析在分类学中运用应注意的问题进行探讨 。