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分形地面与半埋矩形截面目标复合电磁散射FDTD研究 被引量:2
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作者 朱小敏 任新成 《电子测量技术》 2014年第9期23-27,共5页
采用一维带限分形函数模拟实际的粗糙地面,应用时域有限差分法研究了一维分形地面与半埋矩形截面目标复合电磁散射特性,得出了复合散射系数随散射角变化的曲线,分析了分形地面粗糙度参数、土壤介电参数、目标几何参数等对复合散射系数... 采用一维带限分形函数模拟实际的粗糙地面,应用时域有限差分法研究了一维分形地面与半埋矩形截面目标复合电磁散射特性,得出了复合散射系数随散射角变化的曲线,分析了分形地面粗糙度参数、土壤介电参数、目标几何参数等对复合散射系数的影响,得到了分形地面与半埋目标复合电磁散射的特性。数值计算结果表明复合散射系数受地面粗糙度参数影响明显,目标表面散射波对表面镜反射方向复合散射系数影响较大。 展开更多
关键词 复合电磁散射 分形地面 半埋目标 FDTD
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分形地面与埋藏目标宽带电磁散射FDTD研究 被引量:1
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作者 朱小敏 任新成 《河南科学》 2014年第9期1713-1718,共6页
采用一维带限Weierstrass分形函数模拟实际的粗糙地面,运用时域有限差分法研究了脉冲波入射时分形地面与下方埋藏目标复合模型的宽带电磁散射问题,得出了后向复合散射系数的频率响应曲线.数值计算了后向复合散射系数随分形地面分维数、... 采用一维带限Weierstrass分形函数模拟实际的粗糙地面,运用时域有限差分法研究了脉冲波入射时分形地面与下方埋藏目标复合模型的宽带电磁散射问题,得出了后向复合散射系数的频率响应曲线.数值计算了后向复合散射系数随分形地面分维数、高度起伏均方根、土壤湿度、目标尺寸、目标倾角、目标埋藏深度等的变化情况,并做了详细分析与讨论,得到了一维带限Weierstrass分形地面与下方埋藏目标复合模型的宽带电磁散射特性. 展开更多
关键词 时域有限差分法 宽带电磁散射 分形地面 埋藏目标
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一维带限Weierstrass分形分层地面与矩形截面导体柱复合电磁散射FDTD研究 被引量:5
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作者 朱小敏 任新成 郭立新 《计算物理》 EI CSCD 北大核心 2012年第3期399-405,共7页
运用时域有限差分方法研究一维带限分形分层粗糙地面与矩形截面导体柱的复合电磁散射,计算复合电磁散射的双站散射系数,得到复合散射系数随散射角的变化,讨论粗糙面高度起伏均方根、分维、中间层介质、下层介质及矩形截面导体柱的参数... 运用时域有限差分方法研究一维带限分形分层粗糙地面与矩形截面导体柱的复合电磁散射,计算复合电磁散射的双站散射系数,得到复合散射系数随散射角的变化,讨论粗糙面高度起伏均方根、分维、中间层介质、下层介质及矩形截面导体柱的参数等对复合散射系数的影响. 展开更多
关键词 复合电磁散射 一维带限Weierstrass分形地面 分层介质 FDTD
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一维带限Weierstrass分形粗糙地面电磁散射的FDTD研究 被引量:2
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作者 朱小敏 任新成 杨小桐 《电子测量技术》 2012年第7期32-36,共5页
采用一维带限Weierstrass分形函数模拟了实际的粗糙地面,应用时域有限差分方法研究了一维分形粗糙地面电磁散射特性,计算了分形粗糙地面散射的双站散射系数,得出了散射系数随散射角和入射波频率变化的曲线,讨论了高度起伏均方根、分维... 采用一维带限Weierstrass分形函数模拟了实际的粗糙地面,应用时域有限差分方法研究了一维分形粗糙地面电磁散射特性,计算了分形粗糙地面散射的双站散射系数,得出了散射系数随散射角和入射波频率变化的曲线,讨论了高度起伏均方根、分维数、土壤湿度、入射波频率、入射角等参数对散射系数的影响,得到了一维带限Weierstrass分形粗糙地面电磁散射的特性。数值计算结果表明各参数对散射系数均有显著影响,入射波不同极化方式下的散射系数也有明显的变化。 展开更多
关键词 电磁散射 一维带限Weierstrass分形粗糙地面 双站散射系数 FDTD
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一维带限分形Weierstrass地面的宽带电磁散射特性研究
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作者 陈芬芬 田炜 葛菁菁 《延安大学学报(自然科学版)》 2015年第4期44-47,共4页
应用微扰法理论并结合一维带限分形Weierstrass功率谱密度推导出了宽带散射系数的计算公式,然后运用微扰法实现了地面宽带电磁散射问题的计算,得到了散射系数随入射波波长的变化曲线。分析了高度起伏均方根、分维数、土壤湿度、温度对... 应用微扰法理论并结合一维带限分形Weierstrass功率谱密度推导出了宽带散射系数的计算公式,然后运用微扰法实现了地面宽带电磁散射问题的计算,得到了散射系数随入射波波长的变化曲线。分析了高度起伏均方根、分维数、土壤湿度、温度对散射系数的影响结果。结果表明,高度起伏均方根、分维数、土壤湿度对散射系数的影响明显,而温度对散射系数几乎无影响。 展开更多
关键词 宽带电磁散射 分形粗糙地面 微扰法 散射系数
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分形粗糙面与上方导体目标的宽带后向电磁散射研究
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作者 石延梅 武剑 朱小敏 《河南科学》 2016年第3期338-342,共5页
采用一维带限Weierstrass分形函数模拟实际粗糙地面,运用时域有限差分法研究了高斯脉冲波入射时粗糙地面与上方二维等边三角形导体目标的宽带后向电磁散射问题,得到了后向复合散射系数随频率的变化曲线.分析了后向复合散射系数随粗糙地... 采用一维带限Weierstrass分形函数模拟实际粗糙地面,运用时域有限差分法研究了高斯脉冲波入射时粗糙地面与上方二维等边三角形导体目标的宽带后向电磁散射问题,得到了后向复合散射系数随频率的变化曲线.分析了后向复合散射系数随粗糙地面高度起伏均方根、分维数、土壤湿度和三角形边长、倾角、高度的变化情况,得到了分形粗糙地面与上方导体目标复合的宽带后向电磁散射特性. 展开更多
关键词 宽带电磁散射 分形粗糙地面 后向复合散射系数 三角形目标 FDTD
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A terrain openness index for the extraction of karst Fenglin and Fengcong landform units from DEMs 被引量:4
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作者 MENG Xin XIONG Li-yang +2 位作者 YANG Xian-wu YANG Bi-sheng TANG Guo-an 《Journal of Mountain Science》 SCIE CSCD 2018年第4期752-764,共13页
The Fenglin and Fengcong landform units are considered to be an important representation for defining the degree of development of Karst landforms. However, these terrain features have been proven difficult to delinea... The Fenglin and Fengcong landform units are considered to be an important representation for defining the degree of development of Karst landforms. However, these terrain features have been proven difficult to delineate and extract automatically because of their complex morphology. In this paper, a new method for identifying the Fenglin and Fengcong landform units is proposed. This method consists of two steps:(1) terrain openness calculation and(2) toe line extraction. The proposed method is applied and validated in the Karst case area of Guilin by using ASTER GDEM with one arc-second resolution. The openness of both the positive and negative terrain and a threshold were used to extract toe lines for segmenting depressions and pinnacles in Fenglin and Fengcong landforms. A comparison between the extracted Fenglin and Fengcong landform units and their real units from high resolution images wascarried out to evaluate the capability of the proposed method. Results show the proposed method can effectively extract the Fenglin and Fengcong landform units, and has an overall accuracy of 93.28%. The proposed method is simple and easy to implement and is expected to play an important role in the automatic extraction of similar landform units in the Karst area. 展开更多
关键词 DEM Karst landform Fenglin and Fengcong landform Terrain openness Landform units
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Estimation of Ground Deformation Caused by the Earthquake (M7.2) in Japan,2008,from the Geomorphic Image Analysis of High Resolution LiDAR DEMs 被引量:2
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作者 MUKOYAMA Sakae 《Journal of Mountain Science》 SCIE CSCD 2011年第2期239-245,共7页
In this study, a new method for quantitative and efficient measurement for the ground surface movement was developed. The feature of this technique is to identify geomorphic characteristics by image matching analysis,... In this study, a new method for quantitative and efficient measurement for the ground surface movement was developed. The feature of this technique is to identify geomorphic characteristics by image matching analysis, using the intelligent images made from high resolution DEM(Digital Elevation Model). This method is useful to extract the small ground displacement where the surface shape was not intensely deformed. 展开更多
关键词 Ground deformation Ground surface movement Digital Elevation Model(DEM) Geomorphic image analysis JAPAN
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Application of probability integral method in ground deformation prediction 被引量:5
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作者 WANG Zijian LI Guangjie YOU Bing BAO Shuochao 《Global Geology》 2012年第3期237-240,共4页
In order to study the law of mining subsidence and ground movement, to provide the basis of coal mining under building, railway and water, we used the probability integration method to make comprehensive evaluation of... In order to study the law of mining subsidence and ground movement, to provide the basis of coal mining under building, railway and water, we used the probability integration method to make comprehensive evaluation of ground stability. Take Yingcheng Coal Mine of Jiutai as an example. Mining-induced movement and horizontal movement are analyzed on the basis of the measurement data. The resuhs of prediction can pro- vide reference and basis for prevention of coal mining subsidence and future restoration and treatment. 展开更多
关键词 surface deformation probability integration method deformation prediction
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Application of micro-seismic facies to coal bed methane exploration 被引量:5
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作者 Li Donghui Dong Shouhua +2 位作者 Zhang Cong Deng Shuaiqi Li Shujie 《Mining Science and Technology》 EI CAS 2011年第5期743-747,共5页
A neural network is applied to high-quality 3-D seismic data during micro-seismic facies analysis to perform the waveform analysis and training on single reflection events. Modeled seismic channels are established and... A neural network is applied to high-quality 3-D seismic data during micro-seismic facies analysis to perform the waveform analysis and training on single reflection events. Modeled seismic channels are established and the real seismic channels are classified. Thus, a distribution of micro-seismic facies having a high precision over a fiat surface was acquired. This method applied to existing geological data allows the distribution of areas rich in coal bed methane to be clearly defined. A distribution map of the micro-seismic facies in the research area is shown. The data accord well with measured methane con- tents, indicating that the analysis using micro-seismic facies is reliable and effective. This method could be applied to coal bed methane exploration and is of great importance to future exploration work and to an increase in the drilling success rate. 展开更多
关键词 Micro-seismic faciesCoal bed methaneWaveform classificationGas rich area
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Implication of Surface Fractal Analysis to Evaluate the Relative Sensitivity of Topography to Active Tectonics,Zagros Mountains, Iran 被引量:4
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作者 Ali Faghih Ahmad Nourbakhsh 《Journal of Mountain Science》 SCIE CSCD 2015年第1期177-185,共9页
Fractal geometry is increasingly becoming a useful tool for modeling and quantifying the complex patterns of natural phenomena. The Earth's topography is one of these phenomena that have fractal characteristics. T... Fractal geometry is increasingly becoming a useful tool for modeling and quantifying the complex patterns of natural phenomena. The Earth's topography is one of these phenomena that have fractal characteristics. This paper investigates the relative sensitivity of topography to active tectonics using ASTER Global Digital Elevation Model. The covering divider method was used for direct extraction of surface fractal dimension(D surf) to estimate the roughness-surface of topography with aid of geographic information system(GIS)techniques. This evaluation let us highlight the role of the geomorphic and tectonic processes on the spatial variability of fractal properties of natural landforms.Geomorphic zones can be delineated using fractal dimension mapping in which variability of surface fractal dimension reflects the roughness of the landform surface and is a measure of topography texture. Obtained results showed this method can be a quick and easy way to assess the distribution of land surface deformation in different tectonic settings. The loose alluvial deposits and irregularities derived by tectonic activity have high fractal dimensions whereas the competent formations and higher wavelength folded surfaces have lower fractal dimensions.According to the obtained results, the Kazerun Fault Zone has a crucial role in the separation of the Zagros Mountain Ranges into the different lithological,geomorphological and structural zones. 展开更多
关键词 Surface fractal analysis TOPOGRAPHY Active tectonics Kazerun Fault Zone ZAGROS Iran
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Coarse aerosol particle size and shape characteristics near ground level of Shijiazhuang city, China
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作者 WANG Zan-hong ZHANG Yu-liang +4 位作者 ZHAO Zhou ZHANG Su-min ZHANG Wen-zong WANG Yun-xiu WEI Li -tao 《Journal of Environmental Science and Engineering》 2007年第1期48-54,共7页
This research sampled subaerial ambient coarse aerosol particles (〉2μm of equivalent area diameter) in the typical air polluted city of Shijiazhuang to measure the particle size distribution and shape characterist... This research sampled subaerial ambient coarse aerosol particles (〉2μm of equivalent area diameter) in the typical air polluted city of Shijiazhuang to measure the particle size distribution and shape characteristics by the analyzer of CIS-50 and the scan electronic microscope of S-570 in the non-heating period and heating period respectively. The results show that the coarse aerosol particle size distribution mode is 2-4μm in the non-heating period and 3-5μm in the heating period, with the size range of 0.8-120μm, mostly under 10μm; and the square or square like particle shape is dominant, the sphere like lesser, the acute-angle and lathy shape sparse. There exist particle size distribution and shape characteristics differences in the non-heating period and heating period influenced greatly by the ground coal combustion emission and windblown dust. In the heating period, particle size average increases by 53.2%, principally in the size range of 5-10μm, and 20-50μm secondly. Meanwhile, the particle number of quasi-round and round shape group and those with convex-concave fractal edge increase obviously. These quasi-round particles are agglomerate derived from combustion in the SEM images. The relationship between particle size and shape is demonstrated by that the percentage of PM5 and the particle number of the quasi-square and square shape group are positively correlative with r of 0.9458; quasi-round and round shape group negatively correlative with r of-0.9726 respectively. 展开更多
关键词 size distribution shape characteristics coarse aerosol particles Shijiazhuang
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Analysis of the Adjacent Terrain Effect on the Properties of Ground Motion
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作者 Hao Minghui Zhang Yushan 《Earthquake Research in China》 CSCD 2016年第1期74-87,共14页
The explicit finite element analysis method combined with the artificial transmitting boundary theory is performed to evaluate the adjacent terrain effects on ground motion,and the influence of the distance between ad... The explicit finite element analysis method combined with the artificial transmitting boundary theory is performed to evaluate the adjacent terrain effects on ground motion,and the influence of the distance between adjacent terrains on the topographical amplification effects on ground motion is studied. The results show that:( 1) Compared to the case of a single hill,the presence of adjacent hills has little effect on the shape of the spectral ratio curve,but has a significant effect on the value of spectral ratio,which is dependent on the locations of observation points.( 2) The presence of adjacent hills has a greater effect on high-frequency ground motion,and with the increase of the distance between adjacent hills,such an effect weakens gradually,and the effect of the composite topography combined with multiple hills on ground motion gradually approaches that of a single hill. 展开更多
关键词 Adjacent terrain Terrain effect The response spectrum of ground motionTransmitting boundary
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Geomorphological inheritance for loess landform evolution in a severe soil erosion region of Loess Plateau of China based on digital elevation models 被引量:16
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作者 XIONG LiYang TANG GuoAn +3 位作者 YUAN BaoYin LU ZhongChen LI FaYuan ZHANG Lei 《Science China Earth Sciences》 SCIE EI CAS 2014年第8期1944-1952,共9页
The influence of pre-quaternary underlying terrain on the formation of loess landforms, i.e., the geomorphological inheritance issue, is a focus in studies of loess landforms. On the basis of multi-source information,... The influence of pre-quaternary underlying terrain on the formation of loess landforms, i.e., the geomorphological inheritance issue, is a focus in studies of loess landforms. On the basis of multi-source information, we used GIS spatial analysis methods to construct a simulated digital elevation model of a pre-quaternary paleotopographic surface in a severe soil erosion area of the Loess Plateau. To reveal the spatial relationship between underlying paleotopography and modern terrain, an XY scatter diagram, hypsometric curve, gradient and concavity of terrain profiles are used in the experiments. The experiments show that the altitude, gradient and concavity results have significant linear positive correlation between both terrains, which shows a relatively strong landform inheritance relationship, particularly in the intact and complete loess deposit areas. Despite the current surface appearing somewhat changed from the original shape of the underlying terrain under different erosion forces, we reveal that the modern terrain generally smoothes the topographic relief of underlying terrain in the loess deposition process. Our results deepen understanding of the characteristics of geomorphological inheritance in the formation and evolution of loess landforms. 展开更多
关键词 loess landform landform inheritance underlying paleotopography digital elevation model
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