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961.
利用黄河源区1977-2006年土地覆盖数据集,分析了土地利用覆盖变化格局。根据高寒草地生态系统的特点,改进了生态功能服务价值系数计算方法,把土地利用的生态效益转化为简单易懂的货币形式,为决策者提供直观的生态信息。同时利用基于案例推理的CA模型模拟黄河源区2018年的土地覆盖情景,并得到其生态服务价值。研究表明:1977-2006年生态系统服务价值由460亿元降至418亿元,其中林地、高覆盖草地与湿地的生态服务价值分别减少10亿元、30亿元和20亿元,中、低覆盖草地生态服务价值提高20亿元,水体与沙(裸)地等变化不大。2006-2018年草地覆盖度将逐步上升,高、中覆盖度草地面积逐渐扩大,低覆盖度草地面积减小,生态服务价值得到较大幅度提升。 相似文献
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Dyutiman Choudhary Bishnu H. Pandit S. P. Kala N. P. Todaria S. Dasgupta Michael Kollmair 《社会与自然资源》2014,27(10):1057-1073
This article highlights the results of an action research to upgrade mountain farmers of bay leaf (Cinnamomum tamala Nees and Eberm) in Udayapur district of Nepal. Farmers received low prices, lacked market information, capacities, and institutional mechanisms, and were exploited by traders. To address these constraints, three independent but interlinked pro-poor value chain (VC) upgrading strategies comprising VC coordination upgrading and horizontal and vertical contractualization were implemented. Information was collected from focus-group discussions with collectors, traders, and facilitators, and a questionnaire was used to collect pre- and postintervention data (n = 120). VC upgrading strategies improved harvesting practices, increased farmers’ bargaining power, and led to a threefold increase in price, which increased household incomes. Results demonstrated improved terms of participation of farmers and a general increase in market price of bay leaf in Udayapur. The study approach can be up scaled to reduce poverty from high value products. 相似文献
964.
根据长白山无人区1∶10000像片控制测量实例,说明利用GPS测量速度快、点间无须通视、迁站方便、测量大地高相对精度较高的特点.采用GPS高程拟合方法,通过高程异常值求解像片控制点的正常高,解决了山区像片控制点的高程测量难题. 相似文献
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兵棋是对作战过程进行逻辑推演研究和评估的军事科学工具,其三大组成要素包括棋盘、棋子和规则。棋盘的经典样式就是六角格兵棋棋盘,计算机兵棋中也常采用六角格棋盘描述战场地形环境,而棋盘的投影变形和坐标转换分别是制约兵棋推演可信度和推演效率的重要因素。首先分析了棋盘所用投影方式的变形规律,提出了个体值法和平均值法对变形进行修正;然后针对经纬度坐标和六角格编码的转换,提出了直接转换和间接转换两种方法,分析其基本转换原理,并给出了坐标转换公式;最后通过实验对所述方法进行验证,结果证实平均值法对于修正投影变形具有很好的实用性,且间接坐标转换法具有更高的转换效率。 相似文献
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Singular value decomposition as a denoising tool for airborne time domain electromagnetic data 总被引:1,自引:0,他引:1
P.-A. Reninger G. Martelet J. Deparis J. Perrin Y. Chen 《Journal of Applied Geophysics》2011,75(2):264-276
Airborne time domain electromagnetic (TDEM) surveys are increasingly carried out in anthropized areas as part of environmental studies. In such areas, noise arises mainly from either natural sources, such as spherics, or cultural sources, such as couplings with man-made installations. This results in various distortions on the measured decays, which make the EM noise spectrum complex and may lead to erroneous inversion and subsequent misinterpretations. Thresholding and stacking standard techniques, commonly used to filter TDEM data, are less efficient in such environment, requiring a time-consuming and subjective manual editing. The aim of this study was therefore to propose an alternative fast and efficient user-assisted filtering approach. This was achieved using the singular value decomposition (SVD). The SVD method uses the principal component analysis to extract into components the dominant shapes from a series of raw input curves. EM decays can then be reconstructed with particular components only. To do so, we had to adapt and implement the SVD, firstly, to separate clearly and so identify easily the components containing the geological signal, and then to denoise properly TDEM data.The reconstructed decays were used to detect noisy gates on their corresponding measured decays. This denoising step allowed rejecting efficiently mainly spikes and oscillations. Then, we focused on couplings with man-made installations, which may result in artifacts on the inverted models. An analysis of the map of weights of the selected “noisy components” highlighted high correlations with man-made installations localized by the flight video. We had therefore a tool to cull most likely decays biased by capacitive coupling noises. Finally, rejection of decays affected by galvanic coupling noises was also possible locating them through the analysis of specific SVD components. This SVD procedure was applied on airborne TDEM data surveyed by SkyTEM Aps. over an anthropized area, on behalf of the French geological survey (BRGM), near Courtenay in Région Centre, France. The established denoising procedure provides accurate denoising tools and makes, at least, the manual cleaning less time consuming and less subjective. 相似文献