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排序方式: 共有1109条查询结果,搜索用时 296 毫秒
1.
长期连续完整的历史气温资料是震前气温异常判别研究的重要数据基础。本文考虑了参考站与缺测站之间的距离,建立改进的线性回归模型。利用该模型插补缺测和错误的气温整点值数据,在一定程度上解决了长期连续观测数据缺测的情况。通过对收集的唐山观测站气温整点值数据进行插补,并应用插补完整的数据分析研究了2012年5月28日唐山4.8级地震前兆异常。结果表明:①插补值与其前后观测值衔接吻合,插补后完整连续数据符合夏高冬低的年变规律;②插补误差在±0.5℃范围内的比例为60.2%,在±0.8℃范围内的比例为80.3%,其误差绝对值大于1.0℃的比例为9.6%,平均绝对误差为0.84℃,插补值与观测值的相关系数大部分在0.9以上;③从3月27日起出现增温异常,特别是震前2天增温幅度约8℃。 相似文献
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Beijing, Tianjin and Hebei each contributed to the comprehensive governance of bulk coal to treat bulk coal pollution in a mutually beneficial way in 2017. The cooperative game theory is used in this paper to study the environmental benefits and cost effectiveness brought about by this comprehensive governance strategy, primarily focusing on the issue of how to maximize the environmental benefits by choosing an appropriate strategy since the benefits to Beijing, Tianjin and Hebei are closely related. Therefore, the linear optimization, game theory and Shapley value method in the cooperative game model are used to find the ways to minimize the total governance cost of bulk coal in the three areas. In addition, the issues of how to carry out rational distribution and transfer of governance capital among the three places are explored according to the actual amounts of consumption of bulk coal, the influence of the coal burning on the PM2.5 and the actual cost of coal governance in Beijing, Tianjin and Hebei in 2017. The results show that the governance task in Hebei Province is the most onerous, and requires more investment than the other two cities. Thus, it requires the support from other two cities, with the amount of increased capital required of about 600 million Yuan. At the same time, the cost saved after optimization in Tianjin is calculated to be the largest, which thus can be adjusted appropriately and allocated to Hebei for the governance of bulk coal. The model constructed in this paper can not only be used to solve the issues related to bulk coal consumption in Beijing, Tianjin and Hebei, but also to carry out the effective distribution of capital, by which a win-win scenario among the three places can be achieved. 相似文献
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Data-based modelling approach for variable density flow and solute transport simulation in a coastal aquifer 总被引:1,自引:1,他引:0
Data-based models, namely artificial neural network (ANN), support vector machine (SVM), genetic programming (GP) and extreme learning machine (ELM), were developed to approximate three-dimensional, density-dependent flow and transport processes in a coastal aquifer. A simulation model, SEAWAT, was used to generate data required for the training and testing of the data-based models. Statistical analysis of the simulation results obtained by the four models show that the data-based models could simulate the complex salt water intrusion process successfully. The selected models were also compared based on their computational ability, and the results show that the ELM is the fastest technique, taking just 0.5 s to simulate the dataset; however, the SVM is the most accurate, with a Nash-Sutcliffe efficiency (NSE) ≥ 0.95 and correlation coefficient R ≥ 0.92 for all the wells. The root mean square error (RMSE) for the SVM is also significantly less, ranging from 12.28 to 77.61 mg/L. 相似文献
5.
A geometric-based approach for road matching on multi-scale datasets using a genetic algorithm 总被引:1,自引:0,他引:1
Alireza Chehreghan 《制图学和地理信息科学》2018,45(3):255-269
Object matching is used in various applications including conflation, data quality assessment, updating, and multi-scale analysis. The objective of matching is to identify objects referring to the same entity. This article aims to present an optimization-based linear object-matching approach in multi-scale, multi-source datasets. By taking into account geometric criteria, the proposed approach uses real coded genetic algorithm (RCGA) and sensitivity analysis to identify corresponding objects. Moreover, in this approach, any initial dependency on empirical parameters such as buffer distance, threshold of spatial similarity degree, and weights of criteria is eliminated and, instead, the optimal values for these parameters are calculated for each dataset. Volunteered geographical information (VGI) and authoritative data with different scales and sources were used to assess the efficiency of the proposed approach. According to the results, in addition to an efficient performance in various datasets, the proposed approach was able to appropriately identify the corresponding objects in these datasets by achieving higher F-Score. 相似文献
6.
针对船舶线性横摇系统,设计了一种基于执行依赖启发式动态规划(ADHDP)方法的在线学习最优减摇鳍控制器.在设计过程中直接使用输入输出数据获取系统状态值.利用评价网络来逼近针对船舶减摇鳍控制系统设计的性能指标函数,并通过执行网络获得最优控制律,这两个网络都是多层前馈神经网络,即反向传播(BP)神经网络.在训练过程中,这两个神经网络不仅可以使用实时测量数据,也可以减少船舶横摇模型的内部误差和不确定性干扰的影响,从而提高系统的鲁棒性.最后,仿真结果表明所提出的ADHDP控制器对于降低船舶横摇有很好的控制效果. 相似文献
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This study was to detect dryland degradation coupling linear spectral unmixing model of Landsat images with syndrome concept in temperate dryland system, Minqin, China. The phenological contrast and complementation between green vegetation fraction in summer, sandland fraction and saline land fraction in spring, was firstly structured to quantify degradation characteristics by simple correlation analysis with ground data. The spatiotemporal patterns of the three degradation indicators were interpreted with the help “dust bowl” syndrome, qualitatively deciphered the degradation causal clusters, loops and important consequences in the study area. The results indicate water-using and distribution pattern was changed, agricultural intensity and productivity increased, salinization lessened in oasis, whereas sandification risk heightened. This approach developed in this study, has the potentially broad applicability, for dryland system monitoring and modelling. 相似文献
9.
在最小二乘平差准则基础上,把病态平差问题转化为无约束的二次规划问题,并利用优化理论分析病态对平差解的影响。通过共轭梯度搜索算法在可行域中寻找最优步长因子,自动寻找最速下降方向,并给出迭代初值的设置方法。分析近似计算中病态问题与局部最优解的关系,讨论局部最优解的快速迭代方法,并通过实例验证算法的有效性,计算迭代的速度。由于整个过程没有对法方程系数矩阵进行求逆计算,该算法可用于处理大规模系数矩阵高病态的平差问题。 相似文献
10.
Urban stormwater thermal gene expression models for protection of sensitive receiving streams 下载免费PDF全文
Thermal impact of typical high‐density residential, industrial, and commercial land uses is a major concern for the health of aquatic life in urban watersheds, especially in smaller, cold, and cool‐water streams. This is the first study of its kind that provides simple easy‐to‐use equations, developed using gene expression programming (GEP) that can guide the assessment and the design of urban stormwater management systems to protect thermally sensitive receiving streams. We developed 3 GEP models using data collected during 3 years (2009–2011) from 4 urban catchments; the first GEP model predicts event mean temperature at the inlet of the pond; the second model predicts the stormwater temperature at the outlet of the pond; and the third model predicts the temperature of the stormwater after flowing through a cooling trench and before discharging to the receiving stream. The new models have high correlation coefficients of 0.90–0.94 and low prediction uncertainty of less than 4% of the median value of the predicted runoff temperatures. Sensitivity analysis shows that climatic factors have the highest influence on the thermal enrichment followed by the catchment characteristics and the key design variables of the stormwater pond and the cooling trench. The general method presented here is easily transferable to other regions of the world (but not necessarily the exact equations developed here); also through sensitivity and parametric analysis, we gained insight on the key factors and their relative importance in modelling thermal enrichment of urban stromwater runoff. 相似文献