黄、东海毗邻海域悬浮体与水团的对应关系及影响因素   总被引：2，自引：0，他引：2  

杨作升  郭志刚  王兆祥  徐景平  高文兵 《中国海洋大学学报(自然科学版)》1991,(3)

对黄、东海毗邻海域由陆架到深海的悬浮体进行了大量加密取样,获得了较准确的结果。给出了悬浮体含量及其三维分布,确定它们与水团及其边界有良好的对应关系。并从物源、动力和成因等解释了这种对应,提出了水团对悬浮体研究的重要意义。研究表明黑潮次—中层混合爬升水及其混合水形成悬浮体含量最低值区,横亘在陆架与深海之间,形成阻隔含有大部分悬浮体的陆架中、下层水体向深海输送的洁净“水障”,台湾暖流北上的顶托也起类似作用,并分析了影响悬浮体含量的各种因素及有关机制。  相似文献   

High parallelization efficiency in barotropic-mode computation of ocean models based on multi-grid boundary ghost area   总被引：1，自引：0，他引：1  

Hiroshi Ishizaki  Ichiro Ishikawa 《Ocean Modelling》2006,13(3-4):238-254

In general, barotropic-mode computation requires the largest communication time in ocean models because of its iterative nature, when parallel computation is performed based on regional partitioning. In this study, reduction in the overhead time included in the communication in the parallel computation of the barotropic mode is considered to achieve a high parallelization efficiency of ocean models. We verify that the reduction in the communication frequency based on the multi-grid boundary ghost area reduces the total communication time. We find that this is because the sum of several kinds of overhead time for communication occupies a fairly large part of the total communication time. We discuss the trade-off between the decrease in communication time and the increase in computation time due to increased boundary area in such cases, leading to a determination of a suitable width of the multi-grid boundary that minimizes the total required time. We also discuss the efficiencies of the one- and two-dimensional partitioning of the model domain, when a multi-grid boundary is used. In general, two-dimensional partitioning is more efficient than one-dimensional for large partitioning numbers.  相似文献   

正交距离圆曲线拟合方法   总被引：2，自引：0，他引：2  

丁克良  刘全利  陈翔 《测绘科学》2008,(Z1)

在分析圆曲线拟合准则基础上,提出采用正交最小二乘法拟合圆曲线。该方法以圆曲线正交距离残差平方和极小为准则。基于间接平差原理详细推导了相关模型和算法,并以实际算例说明了该方法的效果。  相似文献   

基于MODIS数据的浒苔信息提取方法研究   总被引：6，自引：0，他引：6  

刘振宇  江涛 《测绘科学》2008,(Z1)

浒苔是一种大型绿藻,大量浒苔爆发会严重影响景观,干扰旅游观光和水上运动的进行。本文利用NASA提供的MODIS02的250m分辨率影像,分别采用了比值法、归一化植被指数法和监督分类中的最小距离分类,提取了浒苔的信息,实验结果表明,三者都可以提取浒苔信息,但是比值法提取的结果最好,最小距离分类很难与薄云区分,必须加入人工目视解译,归一化植被指数可以区分出薄云,但是遗漏较多。  相似文献   

GPS在计算导弹脱靶量中的应用研究     

周立锋  马斌  谢志博 《全球定位系统》2008,33(6):33-36

将GPS技术应用于导弹靶试脱靶量测量,并对计算过程作了较为详细的分析和探讨。试验证明：利用GPS测定脱靶量,测量精度高,简单易行,可以在靶场逐步试验推广。  相似文献   

低渗透储层水平井—直井联合布井极限注采井距研究     

侯晓春  陆程  蔡文  郑兴范 《现代地质》2008,22(1)

低渗透储层水平井—直井联合布井技术具有广泛的应用前景,其布井方式至关重要。首先利用劈分流场的方法直观地给出常规储层水平井—直井联合布井的产能评价方法;然后针对低渗透储层的渗流特点,在考虑启动压力梯度条件下建立新的井网渗流物理模型并求解得到产能评价公式;最后经分析计算给出启动压力梯度影响的面积井网极限注采井距关系曲线。研究结果为低渗透储层部署水平井—直井联合井网提供理论依据。  相似文献   

Group K-Nearest Neighbors queries in spatial network databases     

Maytham Safar 《Journal of Geographical Systems》2008,10(4):407-416

This paper addresses the problem of Group K-Nearest Neighbors (GKNN) queries in spatial network databases, and suggests a novel approach based on real network distances. This approach essentially uses network Voronoi diagram properties together with a progressive incremental network expansion for determining the inner network distances that are needed to obtain GKNN queries.   相似文献   

K-L变换与NDBI指数法提取ASTER影像城市用地信息的比较     

秦鹏  陈健飞 《测绘与空间地理信息》2008,31(5)

运用K-L变换和NDBI(Normalized Difference Barren Index)指数法,对试验区--沧州市及其周边地区的ASTER遥感影像进行处理,然后分别对两种方法处理后的图像采用最小距离法监督分类,提取城市用地信息,并对分类后的图像进行对比,结果表明:NDBI指数法对城市用地信息提取的效果较好.  相似文献   

Uncertainty as the overlap of alternate conditional distributions     

Olena Babak  Clayton V. Deutsch 《Computational Geosciences》2008,12(4):503-512

An important task in modern geostatistics is the assessment and quantification of resource and reserve uncertainty. This uncertainty is valuable support information for many management decisions. Uncertainty at specific locations and uncertainty in the global resource is of interest. There are many different methods to build models of uncertainty, including Kriging, Cokriging, and Inverse Distance. Each method leads to different results. A method is proposed to combine local uncertainties predicted by different models to obtain a combined measure of uncertainty that combines good features of each alternative. The new estimator is the overlap of alternate conditional distributions.  相似文献   

一种基于双重距离的空间聚类方法   总被引：10，自引：1，他引：9  

李光强  邓敏  程涛  朱建军 《测绘学报》2008,37(4):0-520

传统聚类方法大都是基于空间位置或非空间属性的相似性来进行聚类,分裂了空间要素固有的二重特性,从而导致了许多实际应用中空间聚类结果难以同时满足空间位置毗邻和非空间属性相近。然而,兼顾两者特性的空间聚类方法又存在算法复杂、结果不确定以及不易扩展等问题。为此,本文通过引入直接可达和相连概念,提出了一种基于双重距离的空间聚类方法,并给出了基于双重距离空间聚类的算法,分析了算法的复杂度。通过实验进一步验证了基于双重距离空间聚类算法不仅能发现任意形状的类簇,而且具有很好的抗噪性。  相似文献