重力异常垂直梯度中央区效应的精密计算

为提高利用重力异常计算重力异常垂直梯度中央区效应的精度,视中央区为矩形域,将重力异常表示成双三次多项式插值形式,引入非奇异变换,推导出了重力异常垂直梯度中央区效应的精密计算公式。以低纬度区域分辨率为2＇×2＇的重力异常数据为背景场进行了仿真分析,结果表明在解算计算点所在的1个网格的中央区效应时,传统公式与本文导出公式计算结果差值的最大值达数E。该导出公式可为重力异常垂直梯度中央区效应的精密计算提供理论依据。     

泉州湾泥沙运移特征的初步研究

泉州湾属于潮流、径流和波浪综合作用下的山地海湾,根据两次(1994年6月和2001年12月)水文泥沙实测资料,分析泉州湾悬浮泥沙和沉积物分布特征,研究其沉积物来源,并探讨北水道的沉积速率。悬浮泥沙含量自河口(湾顶)-湾口-外海逐渐降低。高值区出现在水道和河口,冬季高于夏季,大、中潮高于小潮。泉州湾沉积物分布与水动力强弱环境呈很好的对应关系。晋江携带入海的泥沙是研究区的主要物源：海岸侵蚀来沙与湾外来沙也提供了部分物源。南、北水道分别属于落潮槽与涨潮槽两种不同性质的水道。北水道沉积物较细,以沉积作用为主,其入口处淤积程度较轻,而在上游淤积程度相对较重;南水道流速较大,沉积物较粗,是泥沙输运主要通道,地形变化不明显。     

遥感影像植被信息提取方法研究及思考

从植被光谱特征出发,对植被信息提取的方法和现状进行了综述,其中主要介绍了几种具有代表性的植被提取方法,如:植被指数提取法、NDVI与波段合成法、HIS融合法、分级分类提取法、基于知识库提取法等,对各种方法的原理、特点、优势与限制进行了分析、对比、思考,并展望了下一步研究方向。     

重力垂直梯度的测定及其应用与潜力

近年来,随着重力垂直梯度测量精度的提高及间接推求方法的改善,它在地球科学的研究中的作用日益扩大,本文叙述了利用高精度重力仪直接测量垂直梯度的方法与注意事项,阐明了垂直梯度在地学研究中的意义与作用,其中包括(1)可以更精确测定大地水准面与正高;(2)可以更好探测地下的物质的分布及界面起伏;(3)可根据垂直梯度及形变资料反演场源及解释引起上述变化的动力机制.关于如何进一步发掘其潜力,这里也提出了建议.     

基于ArcGIS Engine与ArcGIS Server的海域定级信息管理系统设计与开发

以Visual Studio 2012为平台,利用ArcGIS Engine强大的空间分析功能,以C#为开发语言结合第三方插件设计开发海域定级决策子系统,实现了不同用海方式海域的自动化定级,对海域定级基础数据、过程数据和结果数据进行综合管理,构建了一个具有一定实用价值的海域定级信息管理系统原型;此外,利用WebGIS将海域定级决策子系统分析生成的结果数据发布成服务,实现海域定级信息共享子系统。本研究为海域定级提供智能化平台,提高对海域定级及评估效率,有利于海洋可持续发展。     

GNSS船姿测量方法及对多波束测深精度的影响分析

GNSS船姿测量以其观测误差不随时间累积的特点得到了广泛研究和应用,本文基于三天线GNSS船姿测量方式,构建了波束脚印误差与姿态误差间的关系模型,设计仿真实验分析了基线长度对姿态误差的影响,以及不同水深环境下姿态误差与GNSS定位误差的关系。为突破传统RTK在测量距离上的限制,本文采用PPP、PPK、MBD (动态参考站差分)三种方法进行GNSS船姿计算,并通过海上实验与高精度惯性导航系统进行对比分析,结果表明使用MBD测姿结果要优于PPK和PPP模式,得到的航偏角、横摇角、纵摇角标准差均在0.1°左右,可满足通常情况下多波束测深对姿态精度的要求。     

Spatial patterns in natural <Emphasis Type="Italic">Picea crassifolia</Emphasis> forests of northwestern China,as basis for close-to-nature forestry

Close-to-nature forest management has been proposed as an effective method for improving the quality of plantation forests. Knowledge of spatial distribution patterns, structure, and succession trajectories in natural forests can provide guidelines for the establishment of close-to-nature forest plantations. Such knowledge is lacking in natural spruce (Picea crassifolia) forests in the Qilian Mountains of China, impeding the establishment of production forests. We conducted a case study in the Qilian Mountains to analyze the relationships between the naturally-formed forest patches and terrain factors, spatial heterogeneity of stand characteristics, and stand structure following harvesting disturbance. Our results suggested that spruce plantations will be effective on the N, NE, and NW slopes, at elevations between 2700 and 3300 m, and on slopes ranging from 15° to 45°. Further, planted forest patches should occupy 64% of the slope area on semi-shady slopes (NE, NW). Spatial patterns in the studied forest exhibited a strong scale-effect, and an area of 0.25 ha could be used as the most efficient plot scale for the management of spruce plantations. Partial logging is an effective method for the conversion of spruce planted forests into nearnatural forests, and the intensity of partial logging can be determined from the negative exponential function relationship between stand density and DBH. Our results provided critical information for the development of spruce plantations and conversion of existing plantations.     

Spatial patterns in natural Picea crassifolia forests of northwestern China,as basis for close-to-nature forestry

Close-to-nature forest management has been proposed as an effective method for improving the quality of plantation forests. Knowledge of spatial distribution patterns, structure, and succession trajectories in natural forests can provide guidelines for the establishment of close-to-nature forest plantations. Such knowledge is lacking in natural spruce(Picea crassifolia) forests in the Qilian Mountains of China, impeding the establishment of production forests. We conducted a case study in the Qilian Mountains to analyze the relationships between the naturally-formed forest patches and terrain factors, spatial heterogeneity of stand characteristics, and stand structure following harvesting disturbance. Our results suggested that spruce plantations will be effective on the N, NE, and NW slopes, at elevations between 2700 and 3300 m, and on slopes ranging from 15° to 45°. Further, planted forest patches should occupy 64% of the slope area on semi-shady slopes(NE, NW). Spatial patterns in the studied forest exhibited a strong scale-effect, and an area of 0.25 ha could be used as the most efficient plot scale for the management of spruce plantations. Partial logging is an effective method for the conversion of spruce planted forests into nearnatural forests, and the intensity of partial logging can be determined from the negative exponential function relationship between stand density and DBH. Our results provided critical information for the development of spruce plantations and conversion of existing plantations.     

天海达工程建设对附近海域水环境影响预测分析

运用三维海洋模型FVCOM(Finite-Volume Coastal Ocean Model),采用有限体积计算方法,引入了"干、湿"判断,建立了天海达工程附近海域的三维潮流和泥沙输移模型,预测分析了天海达工程建设后对附近海域水动力和地形冲淤的影响。结果表明工程建设后对其西侧潮流影响较大,东侧与南侧影响较小,且随着距离的增加,影响程度减小,在距离工程1200 m以外海域流速相对变化值大约在8%以内;工程建设前后,静风条件下,工程附近海域地形变化趋势基本一致,但由于岸线的改变,工程东西两侧500m范围内近岸海域淤积程度增大,淤积增大幅度范围为0.05～0.1 cm/a。     

南海西北陆缘新型多金属结核的发现及意义

近年南海西北陆缘西沙东北海域发现大型多金属结核,尽管其外观与大洋结核别无二致,具有个体大、外部形态规整、层状结构清晰的特点,但其地球化学组成与大洋多金属结核存在明显差别:TMn/TFe的比值小,仅为0.73,富Fe、Si、Al、稀土元素而贫Mn、Cu、Co、Ni。Be同位素质谱法测年和钙质超微生物地层学方法研究表明,结核生长速度达7.41～15.38 mm/Ma,远大于大洋多金属结核的平均生长速率和以前发现于南海北部的多金属结核。依据其综合特征,初步认定其为边缘海区域赋存的一种新型多金属结核。该类型结核所蕴含丰富的边缘海区域古海洋、古气候、古环境信息,有助于探讨新生代末期青藏高原隆升、东亚季风加强、北半球冰期发生等重大地质事件所引起的区域沉积响应。