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731.
应用GIS多源信息综合评价找矿方法和技术对南岭中段锡多金属矿产资源相关信息的空间分析找出与锡多金属矿产关系密切的各种变量,建立锡多金属成矿规律及控矿因素找矿评价模型,圈定找矿远景区. 相似文献
732.
为进一步提高雾天交通安全气象保障精细化能力,以江苏、安徽高速公路雾事故多发路段为例,利用2012—2018年事故信息与气象资料,建立一种基于变量选择和特征提取的逐时雾事故判别支持向量机模型。模型参照递归特征消除思路选择事故发生时间、地理位置、气象环境等重要变量,使用主成分分析提取重要变量的主要特征,并以径向基为核函数、以网络搜索确定最优参数。结果表明:结合重要变量选择和主成分分析的支持向量机混合模型能够成功识别出训练集81.4%和测试集83.0%的事故样本,AUC分数均为0.946;判别效果优于支持向量机单独算法,以及仅基于重要变量选择或主成分分析的支持向量机算法;3个典型实例分析也说明该模型对于阶段性或持续性大雾天气下的交通事故发生有一定判识与警示意义。 相似文献
733.
Discriminant analysis of the geomorphic characteristics and stability of landslide dams 总被引:1,自引:0,他引:1
Jia-Jyun Dong Yu-Hsiang Tung Chien-Chih Chen Jyh-Jong Liao Yii-Wen Pan 《Geomorphology》2009,110(3-4):162-171
Landslides can cause the formation of dams, but these dams often fail soon after lake formation. Thus, rapidly evaluating the stability of a landslide dam is crucial for effective hazard mitigation. This study utilizes discriminant analysis based on a Japanese dataset consisting of 43 well documented landslide dams to determine the significant variables, including log-transformed peak flow (or catchment area), and log-transformed dam height, width and length in hierarchical order, which affect the stability of a landslide dam. The high overall prediction power (88.4% of the 43 training cases are correctly classified) and the high cross-validation accuracy (86%) demonstrate the robustness of the proposed discriminant models PHWL (with variables including log-transformed peak flow, and log-transformed dam height, width and length) and AHWL (with variables including log-transformed catchment area, and log-transformed dam height, width and length). Compared to a previously proposed “DBI” index-based graphic approach, the discriminant model AHV – which uses the log-transformed catchment area, dam height, and dam volume as relevant variables – shows better ability to evaluate the stability of landslide dams. Although these discriminant models are established using a Japanese dataset only, the present multivariate statistical approach can be applied for an expanded dataset without any difficulty when more completely documented worldwide landslide-dam data are available. 相似文献
734.
735.
对适用于非等间隔时间序列的一维CLEAN谱分析方法进行了研究。用模拟信号进行了检验,证实了它也适用于有噪声的序列,但谱质量和噪声强度密切相关,把这种方法应用到激变变变星TT Ari的测光资料分析中,检测到近20min周期的准周期振荡。 相似文献
736.
J. P. Narayan 《Geophysical Journal International》1999,139(3):879-887
This paper presents the development of a 2.5-D simulation technique for acoustic wave propagation in media with variable density and velocity. A comparative study of the 2-D and 2.5-D responses of a model reveals the spatially and temporally damped nature of the 2.5-D acoustic wave equations. The simulated results for constant and variable density models show that the density variation affects only the reflectivity of the layer. The computational cost for variable density models is 2.17 and 2.26 times that for constant density models for the 2.5-D and 2-D cases, respectively. Furthermore, the 2.5-D computational cost in the time domain is only about 10–15 per cent more than that for two dimensions, so this modest increase in computational cost can avoid the exorbitant 3-D computational cost.
Snapshots for a crosshole geometry were computed at various times in order to study the effect of heterogeneity on the amplitude and shape of the wave front. Extensive analysis of an oil-bearing reservoir with and without the inclusion of a gas zone was performed using a point source as well as multiple sources. In addition, the effects of the thickness of a low-velocity layer (oil-bearing) and of the location of the source have been studied. It is concluded from the numerical response that the waveguide action of the low-velocity layer depends on its thickness in terms of the dominant wavelength. Trapping of waves was not observed when the source was outside the low-velocity layer. Furthermore, the presence of heterogeneity in the low-velocity layer contributes considerably to the leakage of energy in the adjacent layers due to scattering/diffraction. It was found that, in the 2.5-D numerical simulation, the stability condition and the requirement of the number of grid points per wavelength to avoid grid dispersion are the same as for the 2-D case. 相似文献
Snapshots for a crosshole geometry were computed at various times in order to study the effect of heterogeneity on the amplitude and shape of the wave front. Extensive analysis of an oil-bearing reservoir with and without the inclusion of a gas zone was performed using a point source as well as multiple sources. In addition, the effects of the thickness of a low-velocity layer (oil-bearing) and of the location of the source have been studied. It is concluded from the numerical response that the waveguide action of the low-velocity layer depends on its thickness in terms of the dominant wavelength. Trapping of waves was not observed when the source was outside the low-velocity layer. Furthermore, the presence of heterogeneity in the low-velocity layer contributes considerably to the leakage of energy in the adjacent layers due to scattering/diffraction. It was found that, in the 2.5-D numerical simulation, the stability condition and the requirement of the number of grid points per wavelength to avoid grid dispersion are the same as for the 2-D case. 相似文献
737.
攀西地区层状岩体套叠式韵律的分形研究 总被引:1,自引:0,他引:1
套叠式韵律是攀西层状岩体的重要特征,它在岩相、矿物、结构、元素含量和斜长石牌号等各方面都有表现。本文阐述了套叠式韵律最为明显的岩相和元素含量特征,并采用分形中的关联维方法对白马岩体数据进行计算。从计算结果可知:形成MgO的套叠式韵律需要有5个状态变量控制:SiO2、TiO2、V2O3、S等元素的套叠式韵律的形成受7个状态变量的控制,推测岩体韵律的形成受7个状态变量控制。其中有两个状态变量对MgO影响不大。InC(r)—Inr曲线近似为一直线,表明该岩体韵律可用分形的方法研究 相似文献
738.
739.
景观破碎度在冬小麦面积抽样设计中的应用研究 总被引:4,自引:1,他引:3
将破碎度指标引入到遥感抽样调查中,重点探讨了面积规模指标与破碎度指标在分层抽样中的适用性。实验结果表明:在种植结构破碎区域,面积规模指标与破碎度指标的相关系数均在0.7以上,可以作为分层标志,随着抽样格网不断增加,面积规模指标的相关系数不断增大,而破碎度指标的相关系数则不断减小。当格网小于100m×100m时,破碎度指标作为分层标志效果要优于面积规模指标;在种植结构规整区域,面积规模指标要始终优于破碎度指标,破碎度指标更适合于种植结构破碎、抽样单元较小的遥感抽样调查方案中作为分层标志进行应用。 相似文献
740.