基于Delaunay三角网的等高线骨架提取算法

根据等高线数据直接建立不规则三角形网络模型往往会在山顶、山底、山脊和山谷等特殊地区出现＂平三角形＂,导致模型失真。文中基于Delaunay三角网,通过对＂平三角形＂的处理,提取骨架线,并结合地形特征估计其高程值。实验证明该算法能够有效地提取各种地形骨架线,对于建立逼真的数字地面模型和进行数字地形分析具有重要应用价值。     

New technologies and systems for high quality citrus fruit production,labor-saving and orchard construction in mountain areas of Japan

Novel technologies have been necessary for improving fruit quality and productivity of citrus,labor-saving and orchard conservation on steep slope lands since aging of growers and decrease in the number of successors is remarkable in mountain areas of southwestern Japan. The purpose of this paper is to introduce new technologies for improving citrus production that have been developed in recent years. A new fruit quality control system using drip irrigation and liquid fertilization technique combined with year-round plastic mulching was developed, and it enables high quality and stable citrus fruit production. Water and/or nutrient solution is automatically supplied through drip tubes that are laid under the mulching sheets to give adequate water stress, so as to improve sugar and acid content of fruit. A new transportation system for steep sloping citrus orchards, which is a combination of the monorail system and contour narrow paths, was suggested. A small walking cultivator was developed to explain the procedure of narrow path excavation. After introducing the narrow path, working hours for fertilizer and chemicalherbicide application were reduced. Disasterpr evention mapping of citrus orchards on slope landswas developed based on computer-aided seepage estimation and topographic data. The mapping can show zones of both ascending flow and descendingflow of underground water during heavy rains incitrus orchards. The mapping is considered to be effective for the management of orchards andprevention of erosion on slope lands.     

An iterative technique to delineate protection buffers for wetlands in regions subject to intensive groundwater pumping

Wetlands are vulnerable to groundwater extraction, which has proven detrimental to aquatic ecosystems around the planet. As wetlands rank among the world’s most endangered ecosystems, versatile strategies are required to protect them. This paper provides a modelling-based method to delineate protection buffers in wetlands subject to groundwater extraction. The technique is sufficiently flexible to cater to a wide variety of conditions, and simple enough to underpin management decisions on a daily basis. A numerical model is used to obtain a map of the critical rate of groundwater abstraction, based on the distance between wetlands and suitable discharge thresholds. The outcomes determine the allowed pumping rate at any point under steady and transient-state conditions. A new iteration is developed every time a new pumping allowance is made. This procedure is demonstrated by means of hypothetical scenarios, as well as by a case study application in the Valle del Cauca region, Colombia.     

Seasonal and sub-seasonal oxygen and nutrient fluctuations in an embayment of an eastern boundary upwelling system: St Helena Bay

Seasonal, sub-seasonal and spatial fluctuations in bottom dissolved oxygen (DO) were examined in St Helena Bay, South Africa’s largest and most productive embayment, between November 2013 and November 2014. Alongshore bay characteristics were assessed through comparison of variables along the 50-m depth contour. A mean coefficient of variation of 0.35 provided a measure of the relative variability of near-bottom DO concentrations along this contour. Consistently lower DO concentrations in the southern region of the bay in summer and autumn are attributed to enhanced retention. Across-shelf transects captured the seasonal development of hypoxia in relation to the distribution of phytoplankton biomass. Exceptional dinoflagellate blooms form extensive subsurface thin layers preceding the autumn DO minima in the south of the bay, prior to winter ventilation of the bottom waters. The seasonal decline in DO concentrations in the bottom waters was marked by sub-seasonal events of hypoxia, and ultimately anoxia linked to episodic deposition of organic matter, as indicated by increases in bottom chlorophyll-a concentrations. Seasonal changes in bottom water macronutrient concentrations followed trends in apparent oxygen utilisation (AOU), both of which mirrored DO concentrations. In the south of the bay, nitrogen loss through denitrification/anammox in suboxic waters was indicated by a dissolved inorganic N deficit in the bottom waters, which was most pronounced in autumn.     

甘肃省城市化与土地集约利用耦合协调发展

土地集约利用能够促进城市化健康发展,而城市化水平又影响着土地集约利用水平,两者的耦合协调程度是影响城市发展的关键因素。本文对甘肃省12个地级市进行实证研究,构建城市化与土地集约利用的耦合协调发展度模型,定量评价两者之间的耦合协调发展状况,并且利用地理空间分析工具进行空间聚类分析。结果表明:多数市已经从拮抗期过渡到磨合期,但是还没有进入协调期,说明甘肃省城市化与土地集约利用之间还未完全达到完全协调发展的程度;甘肃省城市化与土地集约利用的耦合协调发展度普遍较低,从2003年开始呈现出逐年扩张的趋势。     

中国县域国土空间集约利用计量测度与影响机理

土地利用问题日益成为中国经济发展的重要约束力之一。快速城镇化背景下城镇和乡村的快速扩张吞噬了宝贵的土地资源,粗放非集约的利用方式更加剧了土地资源的浪费。从国土空间集约利用的影响机理出发分析中国县域国土空间集约的影响机理对指导集约利用实践以及宏观集约利用政策瞄准和政策矫正都具有特殊意义。综合运用OLS模型、空间面板滞后模型和空间面板自相关模型以GIS和Matlab为技术平台,构建中国县域发展基础数据库 (1992-2010年),定量刻画中国2286个县级单元的空间集约利用度时空变化格局,计量分析社会经济发展、自然环境本底、区位交通地理、宏观战略政策和历史基础5大类变量17项具体因素的影响机理。研究结果表明,空间面板数据模型的整体显著性和可信度检验略高于一般面板数据OLS模型;在固定相关效应后对各因素的影响机制进行了检验,表明工业化、城镇化、经济发展水平、区位、交通和宏观战略政策等因素对县域国土空间集约利用的影响较为明显。自然环境因素弱于社会经济因素。被忽略的历史因素对县域国土空间集约利用具有极显著的影响。未来县域国土空间集约利用应因势利导,强化有利因素,减小不利因素影响。提高工业化和城镇化发展水平和质量。发挥市场的主导作用,完善土地市场和运行机制。优化国土空间集约利用调控政策和管治手段,制定差别化的空间集约利用政策。以资源环境承载力为基础和约束最大限度地提高投入和产出水平。     

自动计算热带气旋位置和范围的方法研究

本文以卫星云图的热带气旋云系为研究对象,基于Canny边缘检测、contour轮廓提取等方法,研究了通过图像的形状特征和范围大小对热带气旋云系进行自动识别,得到了较好的效果。这种方法有助于提高热带气旋云系识别的自动化程度,实现热带气旋的自动跟踪,从而为热带气旋的预报提供了便利。     

小震密集带与地质活动断裂的关系研究

采用双差地震定位方法对1830年磁县7(1/2)级地震X区及其附近地区小震进行重新定位,划分出小震密集带,根据小震空间分布特征,研究X区范围内断裂构造与小震密集带之间的关系。结果表明,小震主要集中在NE向断裂与磁县—大名断裂交汇处以及断层切割区。     

基于模糊聚类分析的莱州湾南岸地下水化学分布特征研究

针对莱州湾南岸咸水入侵区地下水质连续、渐变和边界模糊的特征,利用规格化变换对莱州湾南岸地下水化学组分数据进行标准化,采用夹角余弦法作为相似系数,用平方法计算传递闭包构造模糊等价矩阵进行模糊聚类分析,将莱州湾南岸地下水划分为3类并绘制其平面分区图.在此基础上,用探索性数据分析技术的箱线图分别识别各类地下水各组分的分位数、中位数、极值等数据分布情况,并结合 Radial 图绘制各类地下水各组分均值;利用基于 CA 舒卡列夫分类方法的 Piper三线图识别了各类地下水的水化学类型;最后在相关分析基础上选取代表性指标绘制等值线图,结合模糊聚类分区探讨了分区各指标的空间结构特征及内在机理.综合上述分析,定义玉区为海水入侵重点治理区,域区为海水入侵综合防范与整治区,芋区为卤水区.     

离散点数据自动绘制等深线方法探究

提出用反距离插值法将多波束离散数据点插值成规则格网DEM数据,再根据海图生产规范自动绘制不等间距相对光滑的DEM。将自动绘制的等深线与一般软件生成的等深线、海底地形图成果等深线进行比较分析得出：文中方法绘制的等深线相比以前有较大改善且更符合地形,可作为人工绘制的参考线。