茂名建设现代化海洋经济体系的现状、问题及路径          下载免费PDF全文

韩建华 《海洋开发与管理》2020,37(5):83-88

在广东实现“四个走在全国前列”的时代需求下，茂名应着力建设现代化海洋经济体系。近年来，茂名海洋经济总量快速增长、海洋经济体系基本形成、海洋创新成果初具规模、海洋生态建设成效显著、海洋管理能力不断增强，奠定了建设现代化海洋经济体系的基础，但也面临着海洋经济规模偏小且结构不够合理、现代化海洋产业进程缓慢、现代化海洋经济发展动力不足且受到制约和缺乏保障等问题。未来应从加快供给侧改革、实施创新驱动、推进开放合作、优化海洋生态系统和完善体制机制等方面寻求茂名建设现代化海洋经济体系的路径策略。  相似文献   

Evaluation of effectiveness of three fuzzy systems and three texture extraction methods for building damage detection from post-event LiDAR data     

Milad Janalipour 《International Journal of Digital Earth》2018,11(12):1241-1268

Building damage maps after disasters can help us to better manage the rescue operations. Researchers have used Light Detection and Ranging (LiDAR) data for extracting the building damage maps. For producing building damage maps from LiDAR data in a rapid manner, it is necessary to understand the effectiveness of features and classifiers. However, there is no comprehensive study on the performance of features and classifiers in identifying damaged areas. In this study, the effectiveness of three texture extraction methods and three fuzzy systems for producing the building damage maps was investigated. In the proposed method, at first, a pre-processing stage was utilized to apply essential processes on post-event LiDAR data. Second, textural features were extracted from the pre-processed LiDAR data. Third, fuzzy inference systems were generated to make a relation between the extracted textural features of buildings and their damage extents. The proposed method was tested across three areas over the 2010 Haiti earthquake. Three building damage maps with overall accuracies of 75.0%, 78.1% and 61.4% were achieved. Based on outcomes, the fuzzy inference systems were stronger than random forest, bagging, boosting and support vector machine classifiers for detecting damaged buildings.  相似文献   

导航卫星天线相位中心误差标定方法研究现状及发展趋势   总被引：1，自引：0，他引：1  

刘伟平  郝金明  邓科 《测绘通报》2018,(3):1-8

卫星天线相位中心误差是影响GNSS高精度定位定轨的重要误差源,实用中需要对其精确标定。随着北斗卫星导航系统的建设发展,如何对卫星天线相位中心误差进行更为精确的标定应引起人们的重视。为此,本文首先简要介绍了各卫星导航系统的卫星天线情况,而后系统总结了导航卫星天线相位中心误差标定方法的发展历程和研究现状,指出了未来卫星天线相位中心误差标定方法的发展趋势,相关研究成果对我国北斗卫星天线相位中心误差的标定方法研究具有参考意义。  相似文献   

利用“L-R”剖分及三角形聚合的近似等面积菱形格网建模     

苑争一  赵学胜  赵静 《测绘通报》2018,(1):107-111

球面菱形格网因其几何结构简单、方向一致、径向对称等特性,在空间操作和数据集成方面有着广泛的应用。本文基于“纬线环法”构建了球面四元三角剖分模型,分析了该方法带来的格网单元面积变形及其位置分布,发现该模型的三角单元面积变形具有“锯齿状”分布特征,即相邻的上下两个格网单元总是一大一小交替分布,而且变形方向一致。据此通过合并上下两个相邻三角形格网单元,构建了一种近似等面积的菱形剖分模型。结果表明,相比较于其他球面菱形格网生成方法,该方法计算简单、格网单元方向一致（长轴沿南北向分布）;同时,格网单元的面积变形更小、分布更加均匀。  相似文献   

一种快速获取GPS控制网精确WGS-84坐标方法   总被引：1，自引：0，他引：1  

郭固良  曾凡河 《北京测绘》2006,(3):44-46,25

详细介绍了一种快速求取GPS控制网的精确WGS-84坐标的方法。首先选择三个天空通视条件较好、分布合理的控制网点,与附近的IGS跟踪站进行长基线相对定位或者直接进行静态精密单点定位,求得三点精确的WGS-84坐标,然后将这三个点作为已知点在WGS-84坐标系下进行三维约束平差,可求得控制网其它点精确的WGS-84坐标,这样求得网点的WGS-84坐标具有厘米级精度。  相似文献   

盾构机轴线方位角解算原理研究     

薄志义  王坡  张楠 《北京测绘》2006,(3):18-21

以德国VMT公司的TMB制导系统SLS-T为例,主要解析了盾构机轴线方位角测量原理,并完整地推导了盾构机姿态参数公式。由于国外导向系统的核心原理不公开,因此本文的研究成果,为隧道施工工程技术人员深入理解激光导向系统原理以及开发国产的自动导向系统提供了理论基础。  相似文献   

基于COMGIS的徐州市报业信息管理系统     

武俊红  周兴付  孙久运 《北京测绘》2006,(4):35-38,49

针对目前国内报业信息管理中存在的问题,在分析了当前软件开发技术的基础上,提出了通过引入GIS可以方便地对报社的日常业务信息进行管理和分析。徐州市报业信息管理系统的实现采用了组件式软件开发技术,选择MapX和ADO控件,在VisualBasic集成环境下进行开发,系统结构采用客户端/服务器模式。本文详细介绍了徐州市报业信息系统的基本功能、空间数据库和属性数据库的建立、专题应用模型的设计等。  相似文献   

Seasonal and Diurnal Variations of Cloud Systems over the Eastern Tibetan Plateau and East China: A Cloud-resolving Model Study     

Jinghua CHEN  Xiaoqing WU  Chunsong LU  Yan YIN 《大气科学进展》2022,39(7):1034-1049

The seasonal and diurnal variations of cloud systems are profoundly affected by the large-scale and local environments. In this study, a one-year-long simulation was conducted using a two-dimensional cloud-resolving model over the Eastern Tibetan Plateau (ETP) and two subregions of Eastern China: Southern East China and Central East China. Deep convective clouds (DCCs) rarely occur in the cold season over ETP, whereas DCCs appear in Eastern China throughout the year, and the ETP DCCs are approximately 20%?30% shallower than those over Eastern China. Most strong rainfall events (precipitation intensity, PI> 2.5 mm h^?1) in Eastern China are related to warm-season DCCs with ice cloud processes. Because of the high elevation of the ETP, the warm-season freezing level is lower than in Eastern China, providing favorable conditions for ice cloud processes. DCCs are responsible for the diurnal variations of warm-season rainfall in all three regions. Warm-season DCCs over the ETP have the greatest total cloud water content and frequency in the afternoon, resulting in an afternoon rainfall peak. In addition, rainfall events in the ETP also exhibit a nocturnal peak in spring, summer, and autumn due to DCCs. Strong surface heat fluxes around noon can trigger or promote DCCs in spring, summer, and autumn over the ETP but produce only cumulus clouds in winter due to the cold and dry environment.  相似文献   

The geography of megatrends affecting European agriculture     

《Global Environmental Change》2022

A range of intensifying pressures is making the future of European agriculture dynamic and contested. Insights into these pressures are needed to inform debates about the future of the sector. In this study, we use a foresight approach to identify, quantify and map megatrends. Megatrends are long-term driving forces which are observable today and will likely have transformational potential in the future. By mapping these megatrends at the regional scale, we establish a geography of megatrends and detect where they coincide. Four megatrends significant for the future of European agriculture at the regional scale are assessed: Climate change, demographic change, (post-) productivism shifts, and increasingly stringent environmental regulations. The direction and intensity of these megatrends differs between regions, which drives regions into different systemic lock-ins or dynamics. In most regions, megatrends converge to destabilize the current system, forewarning impending systemic changes. While the specific megatrends contributing to this instability differ regionally, this result highlights that many regions are on a dynamic rather than stable trajectory, and the governance challenge is to steer these dynamics towards a desirable future. However, some regions are found to be highly persistent, indicating that megatrends reinforce business as usual, and change needs to be triggered through purposeful governance. In a minority of regions megatrends may drive marginalization as the current system becomes increasingly unviable. We argue that research and policies concerning agricultural sustainability transitions should be cognizant of the regional diversity of European megatrends and the pressures they create.  相似文献   

一次模态变异中尺度对流系统的模拟与分析          下载免费PDF全文

汪兰  张述文  柴旺  任星露 《热带气象学报》2022,38(5):671-679

利用NCEP FNL分析资料及南京多普勒雷达观测,借助WRF模式,对2017年8月19日发生在长江中下游地区的一次中尺度对流系统(MCS)进行模拟和诊断分析。此次MCS组织模态PS(Parallel Stratiform)型和TS(Trailing Stratiform)型共存,开始为带状结构,最后演变为强弓状飑线。气旋切变和低空急流是此次过程的重要影响系统,而午后强烈发展的地面锋触发了此次强对流。在垂直风切变和冷池共同作用下,西侧初始对流发展为PS型模态,东侧发展为TS型模态。由于PS型模态的中低层垂直风切变发生转向,导致其消散。TS型模态附近冷池和垂直风切变相配合,且在后向入流(Rear Inflow Jets,RIJ)作用下发展成为强弓状飑线;RIJ受中低层涡旋对影响而发展增强,其中气旋式涡旋主要由涡度方程中拉伸项决定,而反气旋式涡旋则主要由倾侧项决定。   相似文献