基于分区间泛化Kriging近似模型的船舶局部结构形状优化     

张干锋  王德禹 《海洋工程》2018,36(6):46-57

为提高Kriging近似模型在船舶结构性能多维度响应预测方面的适用性,对常规Kriging近似模型进行分区间泛化改进:一是对设计样本点的各个维度(分量)进行划区,并在每一个分区间内采用最优拉丁超立方(OLhd)取样;二是引入比例系数w1组合高斯与指数型相关函数提高模型对数据的泛化能力,从而在每个划分的区间内建立泛化的Kriging近似模型。通过SCH测试函数,验证了构造的分区间泛化Kriging模型有效性。结合参数化建模和改进Kriging近似模型对某过渡肘板和舱口角隅边界进行形状优化,优化第一阶段由改进的近似模型通过多岛遗传算法得到全局初步的最优解,第二阶段在初步解的基础上缩小优化变量范围,由少量的FEM计算即可在小范围内搜寻到精确的最优设计变量。结果表明:分区间泛化Kriging近似模型在预测多维度响应时较常规Kriging模型预测精度更高;分阶段的形状优化流程在保证极小误差和缩小计算成本的情况下能够得到理想的应力分布和重量优化结果,有助于船舶结构的轻量化研究。  相似文献   

The use of cartographic control points in the harmonization and revision of MRDBs     

Tadeusz Chrobak  Stanisław Szombara  Dorota Dejniak 《国际地球制图》2019,34(3):260-275

The main purpose of the research is to achieve fully automated approach for supplying multi-resolution databases with linear objects in each scale. Moreover, the proposed solutions maintain the repeatability and accuracy of output data wherever possible according to the input scale. These properties are achieved by keeping the minimal object dimensions as well as the appropriate data pre-processing, based on the classification of source points. The classification distinguishes three classes of points: constant (unchangeable), temporary, and inherited. These classes build a structure of cartographic control points. Based on these solutions, the authors proposed an algorithm for linear object simplification based on minimal object dimensions and cartographic control points. It was also confirmed that the simplification between constant points does not cause geometry discrepancies in relation to the global simplification of the whole line.  相似文献   

概括平差模型的解法探讨   总被引：1，自引：0，他引：1  

史越瑶  赵鑫  卞和方 《测绘信息与工程》2009,34(3):47-48

分析了概括平差模型系数矩阵可能出现非列满秩情况的原因,研究了如何使系数矩阵为列满秩矩阵,避免了系数矩阵为非列满秩时的复杂解算过程。  相似文献   

地理空间数据自动综合方法的研究现状与发展趋势     

黄勇奇  赵追 《测绘科学》2009,34(1)

多年来人们已经报道了很多自动综合方法。这些方法确实解决了地理空间数据自动综合中的很多重要问题,但这些方法也有明显的缺陷和应用范围。本文对这些方法进行了研究,研究内容包括这些方法的分类、原理、优缺点和适用范围,并提出了今后自动综合方法的研究发展趋势。  相似文献   

移动环境中居民地综合算法的应用     

王美珍  沈婕  苏昆 《地球信息科学学报》2008,10(2):171-176

手持设备自身的限制及无线网络环境的特点,要求地图在许多方面进行改革以适应新的技术条件。制图综合作为地图生产与制作的重要环节,是当前移动环境下地图应用必须面临的问题。本文以居民地综合算法为例,探讨了部分算法在移动环境中的执行效率,并进行了可用性验证。尝试将移动环境中用户位置以及用户的当前任务等上下文信息用于综合算法中,设计以用户位置及当前任务为中心的实时制图综合算法,最后以案例证明了算法的可用性。  相似文献   

地图综合中建筑物方向的计算方法及适用性分析     

ZHANG Yan  邓敏  LI Zhi-lin 《地理信息世界》2008,6(2):58-64

建筑物的方向是地图综合过程中的一个基本约束,目前仍没有一个计算建筑物方向的统一方法.本文详细阐述了五种常用的计算方法,分别为最长边法、加权平分线法、统计加权法、最小MBR法和基于墙的均值法.并从其基本原理出发,分析了这五种方法的适用性和局限性.通过两个实验设计和实现,进一步例证了这些方法的适用情况和存在的问题,并发现最小MBR方法较为稳健.  相似文献   

Comparing historical and contemporary maps - a methodological framework for a cartographic map comparison applied to Swiss maps     

Christin Loran  Susette Haegi  Christian Ginzler 《International journal of geographical information science》2018,32(11):2123-2139

Topographic maps are powerful tools for the purpose of identifying land use and cover change (LUCC) as they are among the most reliable representations of past landscapes for the time prior to the existence of aerial photography. In light of the increased availability of historical maps, we argue that there is a need for a standardized process to assess map comparability in a systematic way in order to avoid, or at least minimize, the detection of spurious landscape changes due to incompatible map series. A full understanding of map quality, background and error distributions is fundamental to attain reliable LUCC results. The conceptual framework presented in this study considers the context, distortion and cartographic generalization of topographic maps. Furthermore, it includes an approach to homogenize the level of generalization of landscape elements (e.g. forests) from maps with different scales. To demonstrate its application, we assessed the comparability of seven topographic maps from Canton Zurich covering a time span of 336 years (1664–2000). Overall, for the maps of Canton Zurich, a wall-to-wall comparison of forest cover based on the topographic maps presented here can be problematic for the oldest map from 1664. Based on the results, a wall-to-wall comparison with the later maps is not recommended, due to its substantial distortion. Yet, after re-generalization of natural landscape elements, such as forests, a comparison based on landscape indices is possible, even for the oldest map. Furthermore, our results demonstrate that maps from the mid-19^th century onward possess an acceptable level of accuracy. This framework can be applied to a wide range of maps at regional, national, or global levels, providing the opportunity to look at land cover history over multiple centuries.  相似文献   

特征分类与邻近图相结合的建筑物群空间分布特征提取方法   总被引：2，自引：0，他引：2  

郭庆胜  魏智威  王勇  王琳 《测绘学报》2017,46(5):631-638

建筑物群综合过程中需要对建筑物群空间分布特征进行认知和识别。本文在分析国内外相关研究的基础上,从描述建筑物空间特征的大量指标中,利用主成份分析方法,总结并提出了有代表性的建筑物空间特征指标集:凸包面积、紧密度IPQ指标、边数和最小面积外接矩形方向,并基于这些指标研究了建筑物群的分类。在利用最小生成树邻近图(MST)划分建筑物空间子群时,考虑了建筑物成群与所处地理环境(河流和道路等因素)的关系。另外,基于最邻近图(NNG)、MST、相对邻近图(RNG)和Gabriel图(GG)4种建筑物群邻近图,提出了自动识别具有特定空间排列建筑物子群的方法,并比较分析了识别结果的影响因素和可用性。最后,选择北京某地区建筑物群为试验对象,实现了对建筑物群的分类和空间聚类,并提取了其中直线型空间排列的建筑物子群。  相似文献   

Envelope generation and simplification of polylines using Delaunay triangulation     

Tinghua Ai  Shu Ke  Jingzhong Li 《International journal of geographical information science》2017,31(2):297-319

As a basic and significant operator in map generalization, polyline simplification needs to work across scales. Perkal’s ε-circle rolling approach, in which a circle with diameter ε is rolled on both sides of the polyline so that the small bend features can be detected and removed, is considered as one of the few scale-driven solutions. However, the envelope computation, which is a key part of this method, has been difficult to implement. Here, we present a computational method that implements Perkal’s proposal. To simulate the effects of a rolling circle, Delaunay triangulation is used to detect bend features and further to construct the envelope structure around a polyline. Then, different connection methods within the enveloping area are provided to output the abstracted result, and a strategy to determine the best connection method is explored. Experiments with real land-use polygon data are implemented, and comparison with other algorithms is discussed. In addition to the scale-specificity inherited from Perkal’s proposal, the results show that the proposed algorithm can preserve the main shape of the polyline and meet the area-maintaining constraint during large-scale change. This algorithm is also free from self-intersection.  相似文献   

视觉感知对制图综合的作用   总被引：2，自引：0，他引：2  

游雄 《测绘学报》1992,21(3):224-232

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