港珠澳大桥沉管隧道基槽异常回淤分析与数值模拟          下载免费PDF全文

何杰  辛文杰 《水科学进展》2019,30(6):823-833

港珠澳大桥沉管隧道E15管节基槽发生异常回淤,海底隧道沉管安装被迫中止。为查明E15管节基槽发生异常回淤的原因,先后开展了现场水文泥沙观测、遥感影像资料分析和数值模拟等多种技术手段。采用水沙数学模型反演了内伶仃岛上游采砂活动形成的浑水团在潮流作用下的扩散输移过程,沙源在数学模型中以面源形式模拟。模拟结果表明,采砂活动形成的浑水团在一个大潮期间的落潮过程中可输移扩散至基槽水域,其中E15—E27管节基槽日淤厚在采砂活动影响下将增加43.8%。数值模拟结果为查明E15管节基槽异常回淤的泥沙来源提供了佐证。E15管节以东基槽水域水沙环境复杂,天然淤积已经接近临界回淤允许值,基槽上游水域的采砂活动对沉管基槽回淤将带来不可控因素,采砂活动对周边水域产生的泥沙回淤影响应引起足够重视。  相似文献   

甘肃临潭冶力关国家地质公园地质遗迹资源及其旅游地学意义     

金文斌  刘海博  辛存林  任文秀  王军  段凯  彭措 《甘肃地质》2019,(1):91-97

地质公园的建设和发展以地质遗迹为核心。甘肃临潭冶力关国家地质公园主要以丹霞地貌、滑坡堰塞湖和西北岩溶地貌为主,集旅游、休闲、探险和科研于一体的综合性地质公园。公园位于西秦岭造山带西段,属中秦岭断褶带,地质遗迹丰富典型且在西北稀有,可分为3大类7类13亚类。通过定量评价可以看出,地质遗迹具有很高的科学研究价值、美学观赏价值和旅游开发价值。区内出露上古生界和新生界地层,以区域大型褶皱构造为主,冶海古滑坡形成的堰塞湖规模巨大,滑坡遗存特征明显,保存完整,发育的丹霞地貌为典型的西北高寒湿润型丹霞地貌,在构造地质学、地层学、灾害地质学、地貌学以及生态学等各领域具有重要的研究价值。本文的研究结果对于正确认识冶力关国家地质公园地质遗迹状况,深入的进行地质遗迹的保护与开发具有一定的参考和借鉴价值。  相似文献   

基于交通轨迹数据的三维动态噪声地图     

付乐宜  艾廷华  黄丽娜  信睿 《地球信息科学学报》2020,22(9):1789-1798

噪声信息具有空间传播和随距离衰减变化的特征,采用三维动态可视化形式表达噪声地图可以体现该特征。本文针对噪声的空间分布与强度变化提出一种噪声地图表达的方法,基于Bertin符号参量分析,以具有高度可变的方柱并配以深浅变化的颜色作为噪声符号,动态传递噪声信息。为进行多尺度地图展示,在不同地图等级下设有相应细节层次的符号尺寸和定位排列方式。噪声地图以Web端Mapbox为展示平台,基于交通噪声模型和GPS轨迹数据,对上海黄浦区某区域一时间段内的噪声情况进行模拟表达,实现噪声数据的立体动态化显示。三维动态的表达扩展了噪声数据的表现维度,多维度、多参量的立体动态符号不仅可准确刻画噪声的分布,而且从视觉观感上提高了受众的兴趣度和专注度,这为研究噪声的热点分布、传递趋势等空间规律提供了可视化参考。  相似文献   

基于LiDAR技术的古建筑复杂曲面三维重建     

辛俊伟  罗艳  程朋根 《测绘与空间地理信息》2017,40(7)

随着信息技术和测绘科学的迅猛发展,传统的空间数据获取模式已经不能满足现在的信息化需求。三维激光扫描技术的出现,推动了现代化测绘技术的发展,其高精度、快速的非接触式扫描测绘方法改变了传统空间数据采集模式。古建筑文化遗产的三维数字化保护是目前社会的研究热点,利用三维激光扫描技术来重建古建筑独特复杂的表面模型,为古建筑数字化管理和修复提供数据参考是一个很有意义的事情。本文以利用地面三维激光扫描系统构建古建筑三维模型为研究对象,通过洞窟类实例对古建筑点云数据处理和NUBRS三维模型复杂曲面重建技术进行研究与探讨。  相似文献   

Gosper地图的非空间层次数据隐喻表达与分析   总被引：2，自引：2，他引：0  

信睿  艾廷华  何亚坤 《测绘学报》2017,46(12):2006-2015

本文借助隐喻地图的思想,研究非空间层次数据的空间隐喻表达与分析,以地图视角对非空间数据进行空间化处理,将抽象数据具象化以降低认知负荷,对地图学相关方法进行综合运用以拓宽其应用外沿。结合制图学经典方法开展地图视觉设计,以自然地貌隐喻数据特征,针对层次数据结构特点,将LOD及Cartogram技术引入隐喻地图的表达分析中,对各层级数据特征进行有效凸显,达到通过地图研究其背后数据规律特征之目的。最后,将本研究提出的方法应用于真实文件层次数据,进行文件数量分布、大文件群落定位、文件纵深分析等试验。结果表明,本研究能够有效表达层次数据,并支持一定的地图分析及数据挖掘工作。  相似文献   

A MODELING STUDY OF PARAMETERIZATION SCHEMES FOR DEPOSITIONAL GROWTH OF ICE CRYSTAL: FOUR RAINFALL CASES OVER TROPICS AND MIDLATITUDES     

辛进  李小凡 《热带气象学报(英文版)》2017,23(3):259-268

Depositional growth of ice crystal is one of the major processes for development of precipitation systems and can be represented by depositional growth of cloud ice from cloud water (PIDW) and depositional growth of snow from cloud ice (PSFI) in cloud-resolving model. Four parameterization schemes are analyzed in the cloud-resolving model simulations of four rainfall cases over the tropics and midlatitudes. The comparison of time and model domain mean data shows that Shen’s scheme produces the closest rainfall simulation to the observation. Compared to Zeng’s scheme, Shen’s scheme improves the mean rain-rate simulation significantly through the dramatic decrease in depositional growth of cloud ice from cloud water. Compared to other schemes, Shen’s scheme produces the better rainfall simulation via the reduction in the mean rain rate associated with the enhanced gain of cloud water and ice.  相似文献   

The international conference on mountain development in a context of global change with special focus on the Himalayas was held successfully in Kathmandu,Nepal     

XIN Liangjie  LIU Linshan 《地理学报(英文版)》2018,28(10):1560-1562

正The international conference on mountain development in a context of global change with special focus on the Himalayas was held in Kathmandu,Nepal on April 21-26.Mountain regions are prone to several disasters,such as earthquakes,landslides,floods and avalanches.In recent years,global climate change not only greatly affects biodiversity and ecosystem services,but also threatens directly or indirectly people living in mountain  相似文献   

Is Larger Scale Better? Evidence from Rice Farming in Jianghan Plain     

WANG Jiayue  XIN Liangjie 《资源与生态学报(英文版)》2018,9(4):352-364

Small-scale household agricultural production has been in conflict with China’s agricultural modernization. In the context of vigorously promoting rural land circulation and moderate scale management nationwide, research on the relationship between farm size and scale efficiency has become increasingly important. In this paper, we use the “DEA-OLS” two stage method to analyze data from 368 surveys of rice farming households in the Jianghan Plain. The scale efficiency of rice farming was calculated, and the relationship between farm size and scale efficiency investigated. The results indicate that (1) the rice farm size is generally small in Jianghan Plain, with an average of 0.77 ha. The average scale efficiency is 0.88, and it is the main factor limiting an increase in comprehensive technical efficiency. Moreover, 88.32% of households are in the stage of increasing returns to scale. (2) There is a stable inverted “U” type relationship between rice farm size and scale efficiency. Considering characteristics of the householder, the household and land quality, the maximum scale efficiency corresponds to a household with 5 ha of rice farm. (3) Among householder characteristics, age has a significant negative influence on scale efficiency, and scale efficiency is lower for a household whose householder is engaged in non-farm work than for one whose householder is devoted to farming. As for land quality, there was a significant positive effect of irrigation on scale efficiency. Among family characteristics, the application of a machine during the seeding process increased scale efficiency by 3.07%. Therefore, we suggest that local government should actively promote rural land circulation, implement a staged-scale management subsidy, and other forms of support for the purchase of agricultural machinery and technical popularization. Increased investment in irrigation improvements and mechanical facilities and encouragement of farmers to enlarge their farm size could improve scale efficiency and farming profit and lead to the development of moderate scale management.  相似文献   

ANALYSING THE CLOUD MICRO- AND MACRO-PHYSICAL PROPERTIES OF THE CYCLONE EYE WALL AND ITS SURROUNDING SPIRAL CLOUD BANDS BASED ON CLOUDSAT AND TRMM DATA     

柴乾明  王文彩  黄忠伟 《热带气象学报(英文版)》2018,24(2):253-262

In this study, the micro- and macro-physical properties, thermal structure and precipitation characteristics of cyclone eye walls and their surrounding spiral clouds were analysed with CloudSat and TRMM data for five tropical cyclones (TCs) in 2013. The results show that the ice-phase clouds of a mature TC are mainly above 5 km. With increasing altitude, the cloud droplet effective radius decreases, and the particle number concentration increases. Ice water content first increases and then decreases with increasing height. In the eye area, in addition to the well-known warm-core area, another warm core is also apparent around the eye at a height of 8 to 15 km. The horizontal distribution of precipitation is characterized by large-scale stratiform precipitation mixed with independent convective precipitation. The height of precipitation is mostly below 7.5 km, and the heavy rain is mainly below 5 km. When the peripheral convective clouds are strong enough, ice particles would be generated, thus providing conditions that are favourable for the formation of precipitation below.  相似文献   

阜康葡萄双层覆膜防寒越冬实验效果分析     

马燕  马洪亮  李奇  马玉英  辛和平 《沙漠与绿洲气象(新疆气象)》2017,11(1):87-94

阜康葡萄双层覆膜防寒越冬实验结果表明：丰雪年雪被保温效果明显,双膜内平均气温增加11.3℃,双膜内最低温度在1.7～-4.5℃间;枯雪年双膜内平均气温增加8.3℃,双膜内最低温度在0.3～-9.2℃之间,葡萄可安全越冬。双膜内20cm处最低温度在丰雪年增温15.0℃,在枯雪年增温14.2℃。影响双膜内温度的主要因子为外界的平均气温、最高气温、最低气温及日照时数等。经分析,选用透光性好的覆盖物促使膜内地温快速回升,揭膜日期提前可避免春季的高温热害。根据天气变化灵活掌握揭膜和覆膜时间可有效避免葡萄遭受倒春寒危害。  相似文献