粤港澳大湾区水路客运网络特征     

宋旭妍  彭甜甜  张高军 《热带地理》2022,42(2):247-255

以粤港澳大湾区水路客运班线为数据来源,运用复杂网络分析方法,分析水路客运网络的基本特征,评估其小世界特性与无标度特征,分析各节点的重要性,测试其鲁棒性与脆弱性,结果发现：1）大湾区水路客运网络基本健全,节点之间能够自由流动,但网络的层级单一,可达性较低的节点占据多数;2）大湾区水路客运网络具有部分小世界网络特性和无标度特性,节点分布呈现马太效应;3）深圳蛇口港在复杂网络中的综合重要性最为突出,比较重要的节点还有香港中港码头、香港国际机场、珠海九州港、澳门外港;4）大湾区南部的水路客运网络相比北部发达,东部比西部发达,空间发展不均衡;5）大湾区水路客运网络具有鲁棒性,生存能力较强,但网络发育不够完善,稳定性较差,难以经受蓄意攻击。整体上,大湾区水路客运网络还有较大的优化提升空间,应加大核心节点保障能力,增强边缘节点的连通性,提升大湾区北部的水路客运能力。  相似文献   

Study on Polarized Spectral Characteristics of Soil with Different Water Content     

Yang Han  Yunsheng Zhao  Yeqiao Wang 《Journal of the Indian Society of Remote Sensing》2014,42(4):727-732

Moisture is one of the important parameters in soil polarized spectrum. It has great significance in soil remote sensing band selection and image interpretation; it also provides the information for soil investigation and analysis on physical and chemical properties. In this paper we tested and analyzed the soil polarized spectrum with different moisture in 350?~?2,500 nm wavelength, to study on the relationship between soil polarized spectral data and moisture, to determine the spectral response and changes in soil moisture, and establish models between spectral data and soil moisture. We also designed a orthogonal test on the various factors that affect soil polarized spectral characteristics, in which we studied soil moisture, polarized angle, detected angle and azimuth of the various factors and their interactions. The results showed it was most significant that the soil moisture and the interaction of soil moisture and polarized angle, followed by the interaction effect of detected angle and moisture, while the polarized angle had a little impact on the soil polarized spectrum.  相似文献   

Mapping Wetland Areas Using Landsat-Derived NDVI and LSWI: A Case Study of West Songnen Plain,Northeast China     

Zhangyu Dong  Zongming Wang  Dianwei Liu  Kaishan Song  Lin Li  Mingming Jia  Zhi Ding 《Journal of the Indian Society of Remote Sensing》2014,42(3):569-576

Increasing interest in wetlands for environmental management requires an understanding of the location, spatial extent, and configuration of the resource. The National Wetlands Inventory is the most commonly used data source for this information. However, its accuracy is limited in some contexts, such as agricultural and forested wetlands. An large number of studies have mapped wetlands worldwide from the perspective of land use and land cover change. However, information on the actual wetland planting areas annually is limited, which greatly impacts ongoing research. In this case study of the West Songnen Plain, we developed a simple algorithm for the quick mapping of wetlands by utilizing their unique physical features, such as annual display of phenological land-cover change of exposed soils, shallow flooding water, and plants from multi-temporal Landsat images. Temporal variations of the Normalized Difference Vegetation Index (NDVI) and Land Surface Water Index (LSWI) derived from Landsat images in 2010 for wetlands at different growth stages were analyzed. Results show that during the ante-tillering phase, the NDVI value (above zero) is lower than the LSWI value of paddies because of flooding of shallow water; during the reproductive and ripening phases, the NDVI value is higher than the LSWI value (above zero); and during the post-harvest wetland planting phase, the NDVI value is still higher than the LSWI value, but the LSWI value is negative. Wetland areas can be detected using one or two images in the optimum time window. The algorithm based on the difference of NDVI and LSWI values derived from Landsat images was used to extract the actual wetland planting area. Validated alongside statistical data, the algorithm showed high accuracy. Therefore, this algorithm highlights the unique features of wetlands and can help in mapping the actual wetland area annually on a regional scale. Results further indicate that the new method has a classification accuracy of 92 %. In comparison, two traditional methods based on Landsat-7/ETM registered accuracy rates of only 83 % and 87 % respectively.  相似文献   

Impact of GLONASS pseudorange inter-channel biases on satellite clock corrections   总被引：2，自引：2，他引：0  

Weiwei Song  Wenting Yi  Yidong Lou  Chuang Shi  Yibin Yao  Yanyan Liu  Yong Mao  Yu Xiang 《GPS Solutions》2014,18(3):323-333

GLONASS carrier phase and pseudorange observations suffer from inter-channel biases (ICBs) because of frequency division multiple access (FDMA). Therefore, we analyze the effect of GLONASS pseudorange inter-channel biases on the GLONASS clock corrections. Different Analysis Centers (AC) eliminate the impact of GLONASS pseudorange ICBs in different ways. This leads to significant differences in the satellite and AC-specific offsets in the GLONASS clock corrections. Satellite and AC-specific offset differences are strongly correlated with frequency. Furthermore, the GLONASS pseudorange ICBs also leads to day-boundary jumps in the GLONASS clock corrections for the same analysis center between adjacent days. This in turn will influence the accuracy of the combined GPS/GLONASS precise point positioning (PPP) at the day-boundary. To solve these problems, a GNSS clock correction combination method based on the Kalman filter is proposed. During the combination, the AC-specific offsets and the satellite and AC-specific offsets can be estimated. The test results show the feasibility and effectiveness of the proposed clock combination method. The combined clock corrections can effectively weaken the influence of clock day-boundary jumps on combined GPS/GLONASS kinematic PPP. Furthermore, these combined clock corrections can improve the accuracy of the combined GPS/GLONASS static PPP single-day solutions when compared to the accuracy of each analysis center alone.  相似文献   

“天地图·常州”电子地图的设计与实现     

陆藩藩  刘波  宋法奇  李观石 《现代测绘》2014,(4):55-56

本文分析了"天地图·常州"建设背景和现有数据情况,针对常州特色设计了地图内容、2.5维房屋模型、图面效果和生产流程,详细介绍了"天地图·常州"从数据整理、电子地图制作、脱密处理、瓦片库制作到地图审图等一系列实现过程,为其他市县级天地图建设提供可参考的依据。  相似文献   

The Angstrom Project: a microlensing survey of the structure and composition of the bulge of the Andromeda galaxy     

E. Kerins  M. J. Darnley  J. P. Duke  A. Gould  C. Han  Y.-B. Jeon  A. Newsam  B.-G. Park 《Monthly notices of the Royal Astronomical Society》2006,365(4):1099-1108

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鲜水河断裂带现今断层运动短周期事件的发现与初步研究     

周硕愚  施顺英  宋永厚  张鸿旭  刘本培  吴云 《大地测量与地球动力学》1996,(4)

根据鲜水河断裂带上连续动态地壳形变台阵数据，首次揭示了中国大陆板内断层现今运动的短周期现象，包括蠕变阶、蠕变坡和脉动等，其持续时间为数分钟至数十小时。发现其空间分布与断层分段（闭锁或活动段）有关；其时间分布与强地震孕育过程有关。蠕变过程符合Ｌｏｍｎｉｚ提出的对数蠕变函数，可能是断层面不均匀结构中的局部流变行为。断层短周期事件对揭示断层不均匀结构和微破裂过程动力学有重要意义，并可能发展为一种新的地震前兆  相似文献   

胶南地块的隆升-伸展构造     

杨天南  徐惠芬  宋明春  张建新 《山东国土资源》1997,(1)

岩石学及同位素地质学研究均表明，含榴辉岩的胶南地块在高温高压变质后经历过快速降压过程，这一过程在构造上表现为隆升－伸展构造。这种构造在胶南地块有两种形式：其一为地块内部的垂向缩短、水平向伸展构造，以浅色脉体的变形为特征，并反映出从深层次向浅层次的转化；另一为地块边部的正滑型构造带，可分为早期塑性变形和叠加于其上的且分布于地块外侧的晚期脆性－半脆性变形。反映运动矢量的拉伸线理走向呈放射状：北段走向近南北，中西段近东西。这是地块北西侧的变形特点，东南侧情况不明。北部正滑型剪切带中白云母40Ar／39Ar坪年龄表明，伸展构造的时代为146Ma±。这次构造运动可能由俯冲至上地幔的大洋板块与地壳拆离造成的重力均衡所引起，其结果不仅使得大陆地壳上隆，而且还使榴辉岩从下地壳上升至地表。  相似文献   

基于压缩感知原理的L1范数AVO反演算法     

周红伟  林松 《大地测量与地球动力学》2020,40(4):366-370

基于压缩感知稀疏信号采样与重构理论,利用AVO反演方法将传统的L2范数改变为L1范数,反演地下地层在L1范数下的稀疏脉冲反射系数。反演得到的稀疏尖峰将局部地下结构通过有限数量的层状结构的叠加来表示,能够提高纵向精度,与传统的AVO反演算法相比提高了薄层的反演效果且具有一定的抗噪性。数值模型及实际数据的结果表明,基于压缩感知原理的L1范数AVO反演方法更加准确、分辨率更高。  相似文献   

Carrying Capacity of Marine Region in Liaoning Province   总被引：1，自引：1，他引：1  

DI Qianbin  HAN Zenglin  LIU Guichun  CHANG Hongwei 《中国地理科学(英文版)》2007,17(3):229-235

Carrying capacity is one of important studies on coordinating development of population,resources,and environment.At present,the researches on it mainly concentrate on the carrying capacity for population and economy,such as the water resources carrying capacity,the land resources carrying capacity,the environment carrying capacity,etc.Based on the related theories and methods,this paper creatively proposed the concept and meaning of carrying capacity of marine region,and formed the appraisal system.According to the developing situation of marine economy of Liaoning Province in recent years,and by employing the method of the state space,this paper also measured the carrying capacity and carrying state of marine region and discussed the sustainable problems of marine economy of Liaoning.The research results show that the carrying state of marine region of Liaoning is in the state of overloading at present,but taking a favorable turn.  相似文献