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991.
南海东北部高磁异常带成因的地球物理反演研究 总被引:5,自引:1,他引:4
南海东北部的高磁异常带是南海北部磁场最显著的特征,目前对其成因尚有不同推测.选取一条穿越该异常带的剖面,在多道地震解释及相关地质资料的约束下进行地球物理反演研究,验证其晚中生代俯冲增生带模式的可行性.结果表明,在东沙隆起带的前新生代基底中2.5-6km的深度上、宽约150km、密度2.65 g·cm-3、剩余磁化强度700×10-3A·m-1的中生代中酸性火山岩带可产生南海东北部的高磁异常带,与浙闽东部高磁异常带的成因相同,与晚中生代古太平洋向东亚陆缘的俯冲有关. 相似文献
992.
生态脆弱区社会—生态景观恢复力时空演变及情景模拟 总被引:3,自引:0,他引:3
从最具操作性的景观尺度探究社会—生态系统恢复力的时空分异及其演变,对于揭示人类活动变化对生态环境及其景观服务的影响机制,促进区域可持续发展意义重大。以黄土丘陵沟壑区米脂县作为典型案例地,从生态、社会、生产3个系统维度构建社会—生态景观恢复力评价指标体系,分析研究区各子系统和整体社会—生态景观恢复力时空演变及其相互关系。结果显示:① 研究区2000-2015年社会—生态景观3子系统恢复力空间分异显著且都有增强。其中,“退耕还林”第1阶段(2000-2009年)增强突出,生态、社会、生产三系统恢复力指数分别上升0.134、0.048、0.028;第2阶段(2009-2015年)增强相对减缓,生态、社会、生产三系统恢复力指数分别上升0.038、0.017、0.021。② 总体社会—生态景观恢复力空间分异同样显著,其恢复力指数上升11.60%,呈现中间高东西低的空间格局。③ 子系统与整体景观系统恢复力变化之间有主导性正向关系,且3个子系统恢复力变化协同关系显著,两个或三个系统协同率达到90%以上。最后,运用有序加权平均法,基于干扰指标与适应能力指标的不同权重设置情景偏好,绘制出“不可持续导向型”“维持现状型”和“可持续导向型”3种情景下的社会—生态景观恢复力模拟图,为区域景观适应性管理提供决策支持。 相似文献
993.
Measuring Chinese Marine Environmental Efficiency: A Spatiotemporal Pattern Analysis 总被引:1,自引:0,他引:1
Environmental efficiency standards are often used to evaluate the costs of oceanic economic development. A variety of statistical analyses were applied in this study to quantify the marine environmental efficiency of 11 Chinese coastal provinces and municipalities between 2000 and 2014. Results initially reveal that environmental efficiency measures that incorporate undesirable outputs are more consistent with real production conditions and thus the use of marine economic and environmental efficiencies supplement and complement one another. Second, overall marine environmental efficiency across China tends to be low and can be spatially characterized by a transformation such that the inefficiencies noted in 2000 have subsequently been transformed to comprise a three-tiered structure that encompasses northern, central, and southern cores. Third, variation in absolute and relative marine environmental efficiency differences for the coastal regions of China have been consistent over time; values initially decreased before increasing again in a fluctuating manner over the time period of this analysis. Fourth, data show that the Pearl River Delta area has experienced the highest rate of change in marine environmental efficiency over time when economic zones are used as basic research units, although values have nevertheless fluctuated significantly. Fifth, values for total factor productivity as well as technical efficiency and change across the Chinese marine economy all fluctuated over time but increased. Data show that changes in marine environmental efficiency across China can primarily be attributed to progress in marine science and technology. Finally, levels of capital investment and marine industrial pollution intensity are not significantly correlated with marine environmental efficiency. Indeed, both marine industrial structural levels and environmental protection technologies have had a positive effect on environmental efficiency while levels of investment in marine scientific research as well as the scale of economic development, the marine economy, and the degree of external openness have all exerted negative effects on this key variable. 相似文献
994.
南京城市户籍贫困人口的时空分异格局 总被引:1,自引:1,他引:1
以城市居民最低生活保障统计数据为基础,运用ESDA的方法,探讨2000—2017年南京城市户籍贫困人口的时空分异格局,并从居住空间分异的视角出发,归纳总结出南京城市户籍贫困空间格局的演化过程与机制。研究表明:① 贫困人口的空间分布沿袭了2000年“大分散,小集中”的特点,且分布状态进一步趋于分散,空间集聚则呈现出“核心-边缘”结构,“核心”即热点区域基本都位于绕城公路以内;② 未成年、无业、有就业能力(尚未正式就业)和刑释解教的贫困群体,尤其是刑释解教且无业的贫困群体,是当下城市贫困空间治理重点关注对象;③ 相比于2000年,目前南京城市户籍人口的贫困地域产生了明显分异,可划分为隐蔽型、安置型和复合型三种类型贫困人口聚居区;④ 在政府职能、市场机制和社会行为的交织作用下,南京城市户籍贫困空间重构的同时,也经历了从显性到隐性的转向。 相似文献
995.
996.
A study of estuarine flows during a neap tide was performed using 13-hour roving acoustic Doppler current profiles (ADCP)
and conductivity-temperature-depth (CTD) profiles in the Altamaha River estuary, Georgia, U.S.A. The least-squared harmonic
analysis method was used to fit the tidal (M2) component and separate the flow into two components: the tidal and residual (M2-removed) flows. We applied this method to depth-averaged data. Results show that the M2 component demonstrates over 95% of the variability of observation data. As the flow was dominated by the M2 tidal component in a narrow channel, the tidal ellipse distribution was essentially a back-and-forth motion. The amplitude
of M2 velocity component increased slightly from the river mouth (0.45 m/sec) to land (0.6 m/sec) and the phase showed fairly constant
values in the center of the channel and rapidly decreasing values near the northern and southern shoaling areas. The residual
flow and transport calculated from depth-averaged flow shows temporal variability over the tidal time scale. Strong landward
flows appeared during slack waters which may be attributed to increased baroclinic forcing when turbulent mixing decreases. 相似文献
997.
Di Zhu Ximeng Cheng Fan Zhang Xin Yao Yong Gao 《International journal of geographical information science》2020,34(4):735-758
ABSTRACTSpatial interpolation is a traditional geostatistical operation that aims at predicting the attribute values of unobserved locations given a sample of data defined on point supports. However, the continuity and heterogeneity underlying spatial data are too complex to be approximated by classic statistical models. Deep learning models, especially the idea of conditional generative adversarial networks (CGANs), provide us with a perspective for formalizing spatial interpolation as a conditional generative task. In this article, we design a novel deep learning architecture named conditional encoder-decoder generative adversarial neural networks (CEDGANs) for spatial interpolation, therein combining the encoder-decoder structure with adversarial learning to capture deep representations of sampled spatial data and their interactions with local structural patterns. A case study on elevations in China demonstrates the ability of our model to achieve outstanding interpolation results compared to benchmark methods. Further experiments uncover the learned spatial knowledge in the model’s hidden layers and test the potential to generalize our adversarial interpolation idea across domains. This work is an endeavor to investigate deep spatial knowledge using artificial intelligence. The proposed model can benefit practical scenarios and enlighten future research in various geographical applications related to spatial prediction. 相似文献
998.
999.
Francesco Giuseppe Carollo Costanza Di Stefano Vito Ferro Vincenzo Pampalone 《水文研究》2015,29(17):3802-3811
The traditional direct method (i.e. metric ruler and rillmeter) of monitoring rill erosion at plot scale is time consuming and invasive because it modifies the surface of the rilled area. Measuring rill features using a drone‐based technology is considered a non‐invasive method allowing a fast field relief. In the experimental Sparacia area a survey by a quadricopter Microdrones md4‐200 was carried out, and this relief allowed the generation of a Digital Elevation Model (DEM), with a mesh size of 1 cm and a resolution elevation equal to 2 mm, for three plots (L, G and C) affected by rill erosion. At first for the experimental L plot, which is 44 m long, the rill features were surveyed by a ‘manual’ method which was carried out by drawing on the PC screen the rill paths obtained by a visual orthophoto interpretation. This manual method was not applicable for the plots in which rills of limited depth occurred and were not detectable. Then, for both L plot and the other experimental plots having a length ranging from 22 to 44 m, an ‘automatic’ extraction method of rills from DEM was applied. Using an appropriate calculation routine, a vector coverage of transects orthogonal to the main flow direction (i.e. the maximum slope steepness path) was generated. The intersection of each plot DEM with the transect coverage allowed to obtain both the cross sections and the main rill morphological features. For the L plot the comparison between the rill morphological features obtained by the two different methods (manual, automatic) was carried out. Finally, the length–volume relationship and a dimensionless relationship proposed in literature were tested for all studied experimental plots. Copyright © 2015 John Wiley & Sons, Ltd. 相似文献
1000.