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91.
求解核主成分分析模型的技术关键是确定核矩阵端部的较大特征对。把求解大规模对称矩阵端部特征对问题的基本方法--Lanczos算法应用于核主成分分析模型的求解,设计了大样本核主成分分析模型求解的实用算法。在clapack和nu TRLan两个软件包的基础上,开发了大样本核主成分分析模型求解算法的VC++程序。用高光谱遥感图像数据进行模型求解算法的应用试验研究,证明了大样本核主成分分析模型求解算法的实用性。 相似文献
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Landslides - Flow-like landslide is one of the most catastrophic types of natural hazards due to its high velocity and long travel distance. In 2019, a large catastrophic landslide was triggered by... 相似文献
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采用RAMAC/GPR探地雷达对机场跑道传力杆进行探测试验,取得了令人满意的效果,为机场工程质量检测提供了一种有效手段。 相似文献
96.
Sensitivity of MM5 and WRF mesoscale model predictions of surface winds in a typhoon to planetary boundary layer parameterizations 总被引:1,自引:1,他引:1
Sea surface winds and coastal winds, which have a significant influence on the ocean environment, are very difficult to predict.
Although most planetary boundary layer (PBL) parameterizations have demonstrated the capability to represent many meteorological
phenomena, little attention has been paid to the precise prediction of winds at the lowest PBL level. In this study, the ability
to simulate sea winds of two widely used mesoscale models, fifth-generation mesoscale model (MM5) and weather research and
forecasting model (WRF), were compared. In addition, PBL sensitivity experiments were performed using Medium-Range Forecasts
(MRF), Eta, Blackadar, Yonsei University (YSU), and Mellor–Yamada–Janjic (MYJ) during Typhoon Ewiniar in 2006 to investigate
the optimal PBL parameterizations for predicting sea winds accurately. The horizontal distributions of winds were analyzed
to discover the spatial features. The time-series analysis of wind speed from five sensitivity experimental cases was compared
by correlation analysis with surface observations. For the verification of sea surface winds, QuikSCAT satellite 10-m daily
mean wind data were used in root-mean-square error (RMSE) and bias error (BE) analysis. The MRF PBL using MM5 produced relatively
smaller wind speeds, whereas YSU and MYJ using WRF produced relatively greater wind speeds. The hourly surface observations
revealed increasingly strong winds after 0300 UTC, July 10, with most of the experiments reproducing observations reliably.
YSU and MYJ using WRF showed the best agreements with observations. However, MRF using MM5 demonstrated underestimated winds.
The conclusions from the correlation analysis and the RMSE and BE analysis were compatible with the above-mentioned results.
However, some shortcomings were identified in the improvements of wind prediction. The data assimilation of topographical
data and asynoptic observations along coast lines and satellite data in sparsely observed ocean areas should make it possible
to improve the accuracy of sea surface wind predictions. 相似文献
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Ju Weimin Fang Hongliang Tian Xiangjun Jiang Fei Zhan Wenfeng Liu Yang Wang Zhengxing He Jianfeng Wang Shaoqiang Peng Shushi Zhang Yongguang Zhou Yanlian Jia Binghao Yang Dongxu Fu Yu Li Rong Liu Jingxian Wang Haikun Li Guicai Chen Zhuoqi 《地球科学进展》2016,31(11):1105-1110
The Paris agreement signed in April, 2016 aims to balance global anthropogenic carbon emissions and terrestrial carbon sinks by the middle of the 21st century. To fulfill this goal, it is necessary to calculate carbon fluxes of different regions reliably. The global carbon assimilation system is an effective technique for achieving this goal. The Ministry of Science and Technology of China supports the project entitled as study on the global carbon assimilation system based on multisource remote sensing data through the national key research and development programs for global change and adaptation during the thirteen-five period. This project will develop synergic inversion techniques for retrieving key parameters of biological and atmospheric cycles and for assimilating multisource remote sensing and ground based data. Then, the high resolution global carbon assimilation system coupled with an ecological model will be constructed. This system is able to assimilate jointly multisource observation data and to optimize key model parameters, photosynthesis and respiration carbon fluxes of global terrestrial ecosystems, and anthropogenic carbon emission fluxes of key regions. This system will be used to study quantitatively the spatial and temporal patterns of carbon fluxes of global terrestrial ecosystems and anthropogenic carbon emission fluxes of key regions and to identify the mechanisms driving the global terrestrial carbon sinks and sources. The outputs of this study will be helpful for the fulfillment of the key research and development programs for global change and adaptation and provide valuable data and technical support for the decision-making in China. 相似文献
99.
SUN Dong LIU Xin-ze YANG Hai-jun CAO Nan ZHANG Zhi-peng CHEN Yin-song LI Da-meng 《地下水科学与工程》2014,7(3):195-213
Studying the influence of shale gas exploration and development on groundwater environment is the basis of guiding water environment protection in the process of shale gas exploration and development. Groundwater environmental pollution is concealed, complex and persistent. Once it is difficult to control the pollution, the current commercial shale gas development zones in Sichuan Basin that are mostly located in karst areas and highly sensitive to groundwater will be vulnerable to the impact of shale gas exploration and development. Based on the hydrogeological conditions of shale gas exploration and development area and combined with engineering analysis of exploration and development, various risk pathways that may affect the groundwater environment during process of shale gas exploration, mining well construction, mining operations and other stages were identified in this paper. Some existing risk pathways were proved by verification of typical areas and should not be ignored. Based on the actual situation of typical areas, the countermeasures of groundwater environmental protection in the process of shale gas exploration and development in karst areas were discussed. It is believed that the ground-water environment can be better protected by strengthening administration, research and application of new technologies, precise design, hydrogeological conditions, and research and feedback of groundwater environmental protection. 相似文献
100.
Cities are not only major contributors to global climate change but also stand at the forefront of climate change impact. Quantifying and assessing the risk potentially induced by climate change has great significance for cities to undertake positive climate adaptation and risk prevention. However, most of the previous studies focus on global, national or regional dimensions, only a few have attempted to examine climate change risk at an urban scale and even less in the case of a recent literature review. As a result, a quantitative assessment of climate change risk for cities remains highly challenging. To fill this gap, the article makes a critical review of the recent literature on urban-scale climate change risk assessment, and classifies them into four major categories of studies which jointly constitute a stepwise modelling chain from global climate change towards urban-scale risk assessment. On this basis, the study summarizes the updated research progresses and discusses the major challenges to be overcome for the seamless coupling of climate simulation between different scales, the reproduction of compound climate events, the incorporation of non-market and long-lasting impacts and the representation of risk transmission insides or beyond a city. Furthermore, future directions to advance quantitative assessment of urban-scale climate change risk are highlighted, with fresh insights into improving study methodology, enriching knowledge of climate change impact on city, enhancing abundance and accessibility to data, and exploring the best practice to provide city-specific climate risk service. 相似文献