检索结果-南通市图书馆

在线全文

学校读者我要写书评

暂无评论

东北漫岗黑土区春季冻融期浅沟侵蚀

山地学报 2006年第3期24卷 306-311页

作者：张永光伍永秋刘宝元北京师范大学沙漠与沙区资源研究所北京师范大学环境演变与自然灾害教育部重点实验室北京师范大学地理与遥感科学学院

浅沟侵蚀是东北漫岗黑土区农耕地上常见的水蚀类型,往往对坡耕地造成严重的破坏。2.05年春季,通过对两个小流域浅沟侵蚀的调查测量,发现该区浅沟侵蚀相当严重,两流域分别形成浅沟14条、16条,浅沟总长度分别达3 2.9 m、2.146 m,浅沟密度... 详细信息

浅沟侵蚀是东北漫岗黑土区农耕地上常见的水蚀类型,往往对坡耕地造成严重的破坏。2.05年春季,通过对两个小流域浅沟侵蚀的调查测量,发现该区浅沟侵蚀相当严重,两流域分别形成浅沟14条、16条,浅沟总长度分别达3 2.9 m、2.146 m,浅沟密度分别为908 m/km2.766 m/km2.侵蚀深度分别为0.17 mm、0.16 mm,侵蚀模数分别达181.8 t/km2.173.6 t/km2.2.05年春季两流域浅沟侵蚀期的径流深分别是6.8 mm、7.7 mm。分析表明,研究区在春季表层土壤解冻、地表裸露和存在季节性冻土层的条件下,春季融雪及强降水易造成强烈的浅沟侵蚀。在分布上,浅沟一般位于坡面的中下部,而且多发育在瓦背状坡面的集流水路上。另外,耕作措施对浅沟的形成和发展也有重要影响。

关键词：黑土区强降水冻融浅沟侵蚀

Regularizing kernel-based BRDF model inversion method for ill-posed land surface parameter retrieval using smoothness constraint

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Regularizing kernel-based BRDF model inversion method for il...

Spatial Distribution of Land Cover and Vegetation Activity along Topographic Gradient in an Arid River Valley, SW china

中国科学院地质与地球物理研究所2.08学术年会

作者： Yanfei Wang,Changchun Yang,and Xiaowen Li 1 Institute of Geology and Geophysics,Chinese Academy of Sciences, beijing,china. 2.State Key Laboratory of {2. sensing Science and research center for {2. sensing and gis,beijing normal university,beijing,china.

[1]In this paper,we consider the problem how to solve the kernel-based bidirectional reflectance distribution function(BRDF) models for the retrieval of land surface albedos. The above problem is an ill-posed inverse *** will employ a new regularization technique to alleviate the *** Tikhonov regularization has been discussed for BRDF model inversion,however,much study has to be done before applying it in practice(Wang et al,2.07).In this paper,we thoroughly investigate this method,and propose a discrepancy method for a posteriori choice of the regularization parameter and several options for choosing the regularizing *** proposed method can alleviate difficulties in numerical computation when the discrete kernel is badly conditioned and the number of observations is *** the proposed method can always find a set of suitable BRDF coefficients for poorly sampled *** proposed method is an improvement of the traditional least squares error algorithm in AMBRALS(Algorithm for MODIS(Moderate Resolution Imaging Spectroradiometer) Bidirectional Reflectance Anisotropies of the Land Surface),see Strahler et al.(1999),and is comparable to the regularized singular value decomposition method developed by Wang et al.(2.07).Hence the proposed method can be considered as a supplemental algorithm for the robust estimation of the land surface BRDF/*** performance is given in this paper for the widely used field-based 18 data sets among the 73 data sets(see Li et al.,2.01) and for the satellite data.

关键词：

来源： cnki会议评论

在线全文

cnki会议

学校读者我要写书评

暂无评论

Journal of Mountain Science 2009年第3期6卷 274-285页

作者： LIU Wen XU Xianli LUO Jiancheng SHEN Zhanfeng ZHONG Qiuhai department of Automatic Control School of Automation Beijing Institute of Technology Beijing 100081 China State Key Laboratory of Urban and Regional Ecology Research Center for Eco-Environmental Sciences Chinese Academy of Sciences Beijing 100085 China Institute of remote sensing Applications Chinese Academy of Sciences Beijing 100101 China Centre for Hydrology Micrometeorology and Climate Change Department of Civil and Environmental Engineering University College Cork Cork Ireland

Anthropogenic activities have become more and more important in characterizing the landscape, but their impacts are still restricted by natural environments. This paper discusses the interactions of anthropogenic activity, vegetation activity and topography through describing the spatial distribution of land cover and vegetation activity (represented by normalized Difference Vegetation Index, NDVI) along topographic gradient in a mountainous area of southwestern china. Our results indicate that the existing landscape pattern is controlled by anthropogenic activities as well as topographic factors. Intensive anthropogenic activities mainly occur in areas with relatively low elevation, gentle and concave slopes, as these areas are easy and convenient to attain for human. Because of the destruction by human, some land cover types (mainly grassland and shrub) are only found in relatively harsher environments. This study also finds that topographic wetness index (W) used in other places only reflects runoff generation capacity, but not indicate the real spatial pattern of soil water content in this area. The relationships between NDVI and W, and NDVI and length slope factor (LSF) show that runoff and erosion have complex effects on vegetation activity. Greater values of W and LSF will lead to stronger capacity to produce runoff and transport sediment, and thereby increase soil water content and soil deposition, whereas beyond a certain threshold runoff and erosion are so strong that they would destruct vegetation growth. This study provides information needed to successfully restore native vegetation, improve land management, and promote sustainable development in mountainous areas, especially for developing regions.

关键词： Vertical distribution of land cover Anthropogenic activity Vegetation activity Environmental variability china

GPS和gis进行短期沟蚀研究初探——以东北漫川漫岗黑土区为例

在线全文

学校读者我要写书评

暂无评论

水土保持学报 2004年第4期18卷 16-19,41页

作者：胡刚伍永秋刘宝元谢云北京师范大学沙漠与沙区资源研究所北京100875 北京师范大学环境演变与自然灾害教育部重点实验室

随着现代技术发展,利用GPS野外数据采集,结合DEM的生成来研究切沟侵蚀得到愈来愈广泛的应用。复杂的地形地貌对DEM的生成有着特殊的要求,以Arc/Info为工作平台对DEM的建立进行了概括,同时结合数次野外GPS采样实践以及DEM的生成要求,对GP... 详细信息

随着现代技术发展,利用GPS野外数据采集,结合DEM的生成来研究切沟侵蚀得到愈来愈广泛的应用。复杂的地形地貌对DEM的生成有着特殊的要求,以Arc/Info为工作平台对DEM的建立进行了概括,同时结合数次野外GPS采样实践以及DEM的生成要求,对GPS的野外应用进行了初步探讨。

关键词： GPS gis 短期沟蚀东北地区黑土区

EXTRACTION OF BIOCHEMICAL COMPONENTS IN WINTER WHEAT BY CANOPY HYPERSPECTRUM

在线全文

学校读者我要写书评

暂无评论

EXTRACTION OF BIOCHEMICAL COMPONENTS IN WINTER WHEAT BY CANO...

Analysis and Modeling on the Spatial Structure of Urban Land Use: A Case of Jinan, china

Progress of Information Technology in Agriculture

作者： Huang Wenjiang Wang Jihua Liu Liangyun Zhao Chunjiang Huang Muyi Wang JindiNational Engineering research center for Information Technology in Agriculture {2. Post Code:100089 chinaresearch center for remote sensing and gis {2. normal university {2. Post Code:100875 china

＜正＞ Winter wheat canopy spectrum is affected by wheat canopy （leaf area index, leaf biochemical components, leaf angle distribution,canopy shadows, et al.）, soil, weeds, environment and their interactions. So the uncertainties for crop canopy spectral information become a fatal problem for the canopy biochemical and biophysical variables extraction. Recent studies have demonstrated the application of spectral indices from hyperspectral data for crop biochemical and biophysical variables. These indices are the compositive response to variations of several vegetation and environmental properties. Canopy chlorophyll content, an indicator of photosynthesis activity, which is related the nitrogen concentration in green vegetation and serves as a measure of the crop response to nitrogen application. The combination of NDVI and PRI can reduce the effect of LAI and soil background. The index （CCII） was proved to be sensitive to chlorophyll concentration and very resistant to the variations. This paper introduced the application of the ratio TCARI/OSAVI to make accurate predictions of winter wheat chlorophyll content under different varieties, and the application of SIPI for canopy biochemical indicators inversion by minimizing foliar inner structure effect. It indicated that the canopy chlorophyll content and nitrogen concentration could be evaluated by some new combination vegetation indices.

关键词： winter wheat canopy spectrum uncertainties information extraction

来源： cnki会议评论

在线全文

cnki会议

学校读者我要写书评

暂无评论

Chinese Journal of Population,Resources and Environment 2007年第2期5卷 34-40页

作者： Zhao Huixia1, 3, Zhang Zulu2. Jiang Luguang 1 1. Institute of Geographical Sciences and Natural Resources research, Chinese Academy of Sciences, beijing 100101,{2. 2. College of Population, Resources and Environment, Shandong normal university, Jinan Shandong 2.0014,{2. 3. Graduate School of the Chinese Academy of Sciences, beijing 100039,{2. Institute of Geographical Sciences and Natural Resources research Chinese Academy of Sciences College of Population Resources and Environment Shandong Normal University Graduate School of the Chinese Academy of Sciences

Based on the data of urban land use obtained by remote sensing interpretation from aero images in 1986 and 2.04, the spatial structure of Jinan is studied in this paper with the method of Geographic Information System ({2.). According to the proportion of land for residence, industry and commerce, the urban district can be distinguished into three rings. Compared with the traditional theory of the ring structure in Western coun- tries, they have many distinctive characteristics. The main func- tions of the inner ring include residence, business and banking, but the proportion of residential land (more than 50%) is considerably higher than that of the cities in Western countries. The land proportion for residence and industry in the intermediate ring is equal on the whole. The main land of the outside ring is for industrial use. From 1986 to 2.04, great changes have taken place on the land proportion of different types of use. In the inner ring, the land for residential and industrial use has shrunk much while the land for commercial use has increased. In the intermediate ring, the changes of the three types of land use were not very much and the temporal variation was relatively stable. On the contrary, the structure in the outside ring varies acutely. Though most of it is also for industrial use, the proportion of residential land has in- creased much. The three rings can also be divided into several sectors respectively, according to the function of land use clusters. New trends and mechanisms of the changes of land use impacting the urban structure were proposed in the end of the paper.

关键词： urban land use ring structure sector structure Jinan

Satellite SAR interferometric observations of displacements associated with urban subsidence in Suzhou, Eastern china

在线全文

学校读者我要写书评

暂无评论

Progress in Natural Science:Materials International 2002年第10期 80-82+84页

作者： WANG Chao, ZHANG Hong, LIU Zhi, CHENG Suozhong and LU Guonian(1. LARSIS, Institute of remote sensing Applications, Chinese Academy of Sciences, {2. 100101, china 2. department of geography, Nanjing normal university, Nanjing 2.0097, china) LARSIS Institute of Remote Sensing Applications Chinese Academy of Sciences Beijing 100101China department of geography Nanjing Normal University Nanjing 210097 China

SAR interferometry (InSAR) has a high potential for surface displacement mapping in the range from millimeter to meter. In this paper the potential of ERS-1/2.SAR interferometry for mapping subtle land subsidence has been investigated. A time series of ERS-1/2.SAR data from February 1993 to February 2.00 is collected from measurements taken in Suzhou city, Jiangsu Province, china, eight ERS-1/2.SAR images are used to create seven interferograms, and three differential interferograms are produced using the three-pass method, which clearly show the spatial extent of land subsidence. The deformation maps are validated by leveling surveys, the correlation coefficient and standard deviation between them are 0. 943 and 0.1706 respectively. Based on seven benchmarks, the subsidence rates are estimated, the overall trends are in close agreement with InSAR results. The results of study show that for the mapping of land subsidence in urban environments InSAR has a strong potential due to its cost-saving, high res

关键词： SAR interferometry land subsidence Suzhou.

research on Wireless Sensor Node for Measurement of Vegetation Structure Parameters

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Research on Wireless Sensor Node for Measurement of Vegetati...

亚洲精细农业与计算机农业应用联合大会

作者： QU Yonghua 1 SUN Gang 2.1. State Key Laboratory of remote sensing Science Jointly Sponsored by{2. and the Institute of remote sensing Applications of Chinese Academy of Sciences beijing china. 100875 2. College of Information and electric engine china Agriculture university beijing china. 100083

Based on WSN（Wireless Sensor Network）technology, this article designed a wireless sensor network node for vegetation parameter’s measurement, which can be used at large space scale and in long temporal series measurement activity. Preliminary validation of the wireless sensor network node’s algorithm and performance are presented in this article. The results indicated that the algorithm can estimate the vegetation parameters accurately from the measurement of transmittance of radiance through the canopy. The relative error of estimated LAI（Leaf Area Index） is 5%, and the LIDF（Leaf Inclination Distribution Function）agree with that of real vegetation structure basically. The sensitivity of designed wireless sensor network node is tested by measuring transmitted light intensity of projected direct LED light to leaves which have been punched with different density hole. The results indicted that the measured transmittance of leaves has high correlation with the holes density though it was also found that value of the former was slightly lower than that of the latter.

关键词： Wireless sensor node vegetation Structure parameters

来源： cnki会议评论

在线全文

cnki会议

学校读者我要写书评

暂无评论

基于分形特征的网络异常检测方法研究

计算机工程与应用 2004年第22期40卷 34-36页

作者：刘峰胡昌振帅艳民北京理工大学机电工程学院北京100081 北京师范大学地理与遥感科学学院北京100875

网络连接同许多其它现象一样,呈现出一种统计自相似性。论文根据此特征提出了一种基于分形特征的网络异常检测方法,该方法能够根据网络连接分形维数的变化,有效地检测网络拒绝服务攻击和端口扫描等异常情况,并通过模拟实验证明了该方法... 详细信息

网络连接同许多其它现象一样,呈现出一种统计自相似性。论文根据此特征提出了一种基于分形特征的网络异常检测方法,该方法能够根据网络连接分形维数的变化,有效地检测网络拒绝服务攻击和端口扫描等异常情况,并通过模拟实验证明了该方法的可行性。

关键词：网络安全分形自相似