有关地面布标几个问题的探讨     

郭宪强 《北京测绘》1992,(2):25-28

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碳酸盐胶结砂岩中的指形反应前锋     

汪筱林 Wei  C 《世界地质》1993,12(2):73-86

水—岩相互作用前锋的形态可以自组织成非平面形,如指形和扇形。这是由于外界流体驱动下的聚流作用而形成的。对于碳酸盐胶结的砂岩,这种现象用一组反应—运移方程来模拟,设计一套计算机程序解此方程组,并用以预测这种现象的时间演化。该程序含有许多特别的数值算法,以使计算迅速收敛。文中阐明了前锋成指形、扇形、指尖分裂形和帽形的效应。文中研究了流速、流渠宽度、以及围岩中胶结物(方解石或白云石)的变化的影响。本文讨论了这种模拟对于加深认识成岩作用和石油工程的潜在重要性。  相似文献   

汽车用GPS天线     

《全球定位系统》2006,31(1):49

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SAR图像保留边缘多窗口相干斑滤除方法     

庞晓红  王贞松 《遥感学报》1998,2(4):259-263

在处理合成孔径雷达（ＳＡＲ）图像中,精确地估计图像的局部统计特性和尽可能多地滤除相干斑都需要较大的窗口尺寸,而这与图像边缘和纹理结构的检测需要较小的窗口尺寸相矛盾。一般滤波器都是二者窗口尺寸的均衡,这必然导致二者都不能取得很好的效果。本文提出的新方法有效的解决了这一矛盾。此方法使处理后的ＳＡＲ图像既保存了边缘和纹理结构,避免了以往滤波器中使边缘变模糊的问题,又有效地滤除了相干斑噪声。  相似文献   

微带发夹型滤波器的设计     

李君  杜国宏 《成都信息工程学院学报》2007,22(Z1):43-47

微带发夹型滤波器具有结构紧凑,尺寸小、重量轻和成本低等优点.根据微波电路设计的基本理论,利用微波电路ADS软件,设计了一个微带发夹型滤波器,其中心频率为2.3GHz时,通带带宽为200MHz,通带内插损小于1.7dB.仿真结果表明所设计的滤波器不仅尺寸小,而且性能优越,具有很高的实用价值.  相似文献   

全胶结注浆法在煤矿采空区治理工程中的应用     

潘立文  伍松 《中国地质灾害与防治学报》2010,21(1):47-52

由于煤矿采空区块段顶板基本保持悬空状态,上部岩体易产生沉陷变形,影响地表建筑物地基基础的稳定。全胶结注浆法,就是将水泥粉煤灰浆液直接注入采空区及其上覆岩体裂隙中,浆液固化后胶结岩体裂隙,同时采空区内的浆液形成的结石体对其上覆岩体形成支撑作用,阻止上覆岩体的进一步冒落,保证上部建筑物地基的稳定。山西省晋城富晋精密工业有限公司二期生产项目A区煤矿采空区治理工程应用该技术取得很好的治理效果,全胶结注浆法具有施工简单,安全性高,施工工艺成熟,施工易于管理,质量检测手段简便易行等优点,在同类型矿山采空区的治理中有较大的应用推广价值。  相似文献   

融合自适应最优邻域和卷积神经网络的三维点云分类     

张清波  严加栋 《测绘通报》2023,(7):177-182

针对点云分类中提取单个点自身特征所需的邻域尺寸选择,以及低层次特征设计烦琐且表达地物属性能力较弱等问题,本文提出了一种自适应选择单点最优邻域尺寸及学习泛化能力更强的深层次特征的三维点云分类方法。首先基于自适应最优邻域尺寸选择获得每个点的最优局部邻域信息,继而基于局部邻域信息提取点云低层次特征;然后设计一种以待分类点低层次特征为输入的卷积神经网络模型,学习能反映目标地物内在属性的深层次特征并实现分类;最后采用拓普康公司三维点云数据集进行试验,该数据集通过一个配备TOPCON GLS-2200三维激光扫描仪的移动平台获得。试验结果表明,本文方法分类的总体精度达90.48%,优于文中其他点云分类方法。  相似文献   

Sediment records of environmental changes in the south end of the Zhejiang-Fujian coastal mud area during the past 100 years     

王琳淼  李广雪  高飞  刘玲  刘勇 《中国海洋湖沼学报》2014,32(4):899-908

Previous studies carried out in the East China Sea （ECS） mud area focused on long-term environmental changes in sedimentary records during the Holoeene, especially during the mid-Holocene high-stand water levels period. These results indicate that sensitive grain size groups can be used as a sedimentary proxy to reconstruct the evolution of the East Asian Winter Monsoon （EAWM）. The studies have been carried out mainly in the northern and middle portions of the Zhejiang-Fujian coastal mud, however, similar research in the southern portion and the comparison between sedimentary proxy and modern measured data of EAWM are lacking. In this paper, we focused on a sedimentary record of the past 100 years with an enhanced resolution of 1.8 years. Investigations of the southern end of the Zhejiang-Fujian coastal mud area were conducted on the basis of 21~Pb chronology, grain-size analysis and chemical element analysis. The correspondence between the mean grain size （Mz） of sediment sensitive grain size and the measured EAWM was confirmed for the first time. We found that during the recent 100 years, the variation of the mean grain size of the sensitive population in the southern portion of the Zhejiang-Fujian mud was mainly controlled by the EAWM intensity changes; and not directly related to changes in the sediment discharge from Datong station of the Changjiang River （DTSD）. Finally, recent changes in the content of heavy metals in study area reflect the impact of human activities on the environment.  相似文献   

Characterizing landscape spatial heterogeneity in multisensor images with variogram models     

Bingwen Qiu  Canying Zeng  Chongcheng Cheng  Zhenghong Tang  Jianyang Gao  Yinpo Sui 《中国地理科学(英文版)》2014,24(3):317-327

Most evaluation of the consistency of multisensor images have focused on Normalized Difference Vegetation Index （NDVI） products for natural landscapes, often neglecting less vegetated urban landscapes. This gap has been filled through quantifying and evaluating spatial heterogeneity of urban and natural landscapes from QuickBird, Satellite pour l＇observation de la Terre （SPOT）, Ad- vanced Spacebome Thermal Emission and Reflection Radiometer （ASTER） and Landsat Thematic Mapper （TM） images with variogram analysis. Instead of a logarithmic relationship with pixel size observed in the corresponding aggregated images, the spatial variability decayed and the spatial structures decomposed more slowly and complexly with spatial resolution for real multisensor im- ages. As the spatial resolution increased, the proportion of spatial variability of the smaller spatial structure decreased quickly and only a larger spatial structure was observed at very coarse scales. Compared with visible band, greater spatial variability was observed in near infrared band for both densely and less densely vegetated landscapes. The influence of image size on spatial heterogeneity was highly dependent on whether the empirical sernivariogram reached its sill within the original image size. When the empirical semivariogram did not reach its sill at the original observation scale, spatial variability and mean characteristic length scale would increase with image size; otherwise they might decrease. This study could provide new insights into the knowledge of spatial heterogeneity in real multisen- sor images with consideration of their nominal spatial resolution, image size and spectral bands.  相似文献   

Distributional characteristics of grain sizes of surface sediments in the Zhujiang River Estuary   总被引：1，自引：0，他引：1  

JIANG Siyi  XU Fangjian  LI Yan  LIU Xiling  ZHAO Yongfang  XU Wei 《海洋学报(英文版)》2014,33(4):30-36

Distributions of the parameters of sedimentary grain sizes and their correlations were studied to trace the sources of silts and their movement trends in the Zhujiang River Estuary based on the analyses of grain sizes from more than 1080 sedimentary samples. The distributions of the median diameter, public value, quartile deviation, and skewness of sediments were complex in the Zhuiiang River Estuary mainly because of the impact of the matter source regions, distances from the source regions, and hydrodynamic conditions, such as waves, tidal currents, and coastal currents. Analyses of the parameters of the grain sizes for the various types of sediments showed that the distributions of the surface sediments in the Zhujiang River Estuary were controlled by many factors. Their matter sources were mainly the sediments discharged from the runoffs and ebb tidal currents, and from the open sea. The sediments mainly moved by suspension movement. The silts formed a large area of sediments with suspended fine silts in the Zhujiang River Estuary by internal adjustment transportation in the area, and moved toward the western coast of the Zhujiang River Estuary under the effect of Coriolis forces and coastal currents.  相似文献