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

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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

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Secure network coding in the presence of eavesdroppers

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Science china(information sciences) 2010年第3期53卷 648-658页

作者： LUO MingXing1,2,3, YANG YiXian1,2,3, WANG LiCheng1,2,3 & NIU XinXin1,2,3 1information security center, State Key Laboratory of Networking and Switching technology, beijing University of Posts and Telecommunications, beijing 100876, china 2Key Laboratory of Network and information Attack and Defence technology of MOE, beijing University of Posts and Telecommunications, beijing 100876, china 3National engineering Laboratory for Disaster Backup and Recovery, beijing University of Posts and Telecommunications, beijing 100876, china 1. information security center State Key Laboratory of Networking and Switching Technology Beijing University of Posts and Telecommunications Beijing 100876 China2. Key Laboratory of Network and Information Attack and Defence Technology of MOE Beijing University of Posts and Telecommunications Beijing 100876 China3. National Engineering Laboratory for Disaster Backup and Recovery Beijing University of Posts and Telecommunications Beijing 100876 China

Our concern, in the paper, is to construct information-theoretic secure network coding in the presence of eavesdroppers. Based on the generalized attack model and all-or-nothing transformation, the security of network coding in the generalized combination network can be characterized by the network capacity and the min-cut bound of wiretapping set from the source. Furthermore, it can be extended to any directed acyclic networks with single source. Compared with the traditional results, we construct information-theoretic secure network coding without additional encryptions and giving up any capacity.

关键词： all-or-nothing transformation secure network coding eavesdropping

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基于TPM虚拟单调计数器的电子钱包方案的分析和扩展

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通信学报 2009年第S1期30卷 1-8页

作者：刘冬梅卿斯汉杨涛李小群中国科学院软件研究所基础软件国家工程研究中心北京100080 中国科学院研究生院北京100039 中国科学院软件研究所信息安全技术工程研究中心北京100080 中国科学院计算机网络信息中心e-Science应用推进总体组北京100190

针对一种基于虚拟单调计数器的电子钱包方案存在的不足,对其进行了扩展,原方案商品原子性无法得到满足,且不能够防止货币消失的问题,即其货币原子性只能得到部分满足。在原方案的基础上,将货物的交换过程考虑进来,扩展后的方案既满足货... 详细信息

针对一种基于虚拟单调计数器的电子钱包方案存在的不足,对其进行了扩展,原方案商品原子性无法得到满足,且不能够防止货币消失的问题,即其货币原子性只能得到部分满足。在原方案的基础上,将货物的交换过程考虑进来,扩展后的方案既满足货币原子性,又满足商品原子性,同时能够为顾客提供隐私保护。

关键词：电子现金电子支付可信计算 TPM 公平性原子性匿名性

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改进的基于漫游场景的认证密钥交换协议

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通信学报 2009年第S2期30卷 61-68页

作者：周涛徐静中国科学院研究生院信息安全国家重点实验室北京100190 信息安全共性技术国家工程研究中心北京100190 中国科学院软件研究所信息安全国家重点实验室北京100190

由于动态性和易受攻击的结构特性,无线网络环境下认证协议的设计面临新的挑战。2006年,全球移动网络漫游场景下的2个双向认证密钥交换协议被提出。经过分析发现,这2个协议都会遭受到一些实际的攻击。进一步的,2个改进的协议被提出用于... 详细信息

由于动态性和易受攻击的结构特性,无线网络环境下认证协议的设计面临新的挑战。2006年,全球移动网络漫游场景下的2个双向认证密钥交换协议被提出。经过分析发现,这2个协议都会遭受到一些实际的攻击。进一步的,2个改进的协议被提出用于抵御这些攻击。这2个协议不仅保留了原方案的优点,还提高了第2个方案的效率。

关键词：无线通信漫游认证密钥交换匿名性

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Web应用服务器:新一代中间件

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计算机科学 2004年第1期31卷 1-4页

作者：范国闯陈宁江钟华中国科学院软件研究所软件工程技术中心

Web应用服务器是Web计算环境下产生的新一代中间件,为创建、部署、运行、集成和管理事务性Web应用提供一个跨平台运行环境,是我国企业信息化的基础软件设施。诸多国际知名IT企业纷纷推出其各自的Web应用服务器产品和系统。本文全面系统... 详细信息

Web应用服务器是Web计算环境下产生的新一代中间件,为创建、部署、运行、集成和管理事务性Web应用提供一个跨平台运行环境,是我国企业信息化的基础软件设施。诸多国际知名IT企业纷纷推出其各自的Web应用服务器产品和系统。本文全面系统地对Web应用服务器进行综述,主要包括传统中间件的发展及其挑战,Web应用服务器的定义、主要功能、分类、研究内容和评测标准。根据评测标准,对若干主流Web应用服务器从功能和性能两个方面进行分析和比较。此外,指出了Web应用服务器目前存在的不足以及未来发展趋势。

关键词： Web应用服务器企业信息化中间件可靠性数据库

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基于时间约束的认证字典分类方法

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计算机科学 2004年第7期31卷 20-22页

作者：周永彬卿斯汉薛源刘娟中国科学院软件研究所云南民族大学历史系昆明650031

认证字典是一类重要的数据结构,它在众多研究领域郝具有重要的理论和应用价值,诸如科学数据挖掘、地理数据服务器、Internet上的第三方数据发布以及PKI中的证书撤销等。本文介绍了认证字典的基本概念与原理;首次在认证字典模型中引入了... 详细信息

认证字典是一类重要的数据结构,它在众多研究领域郝具有重要的理论和应用价值,诸如科学数据挖掘、地理数据服务器、Internet上的第三方数据发布以及PKI中的证书撤销等。本文介绍了认证字典的基本概念与原理;首次在认证字典模型中引入了时间约束,并据此给出了一种新的认证字典分类方法,探讨了认证字典的实现技术。最后,简要讨论了认证字典在PKI/WPKI中的应用。

关键词：时间约束认证字典分类法公钥基础设施 PKI/WPKI

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Perturbed solution of sea-air oscillator for the El Nino/ La Nina-Southern Oscillation mechanism

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Acta Oceanologica Sinica 2009年第3期28卷 1-4页

作者： ZHOU Xianchun LIN Yihua WANG Hui MO Jiaqi College of Electronic and information engineering Nanjing University of information Science and Technology Nanjing 210044 China Division of Computational Science E-Institutes of Shanghai Universities at SJTU Shanghai 200240 China State Key Laboratory of Numerical Modeling for Atmospheric sciences and Geophysical Fluid Dynamics Institute of Atmospheric Physics Chinese Academy of Sciences Beijing 100029 China National Marine Environmental Forecastins center Beijing 100081 China Department of Mathematics Anhui Normal University Wuhu 241000 China

A class of coupled system of the E1 Nino/La Nina-Southern Oscillation （ENSO） mechanism is studied. Using the perturbed theory, the asymptotic expansions of the solution for ENSO model are obtained and the asymptotic... 详细信息

关键词： nonlinear perturbation theory E1 Nino/La Nina-Southern Oscillation model

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Efficient DPCA SAR imaging with fast iterative spectrum reconstruction method

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Science china(information sciences) 2012年第8期55卷 1838-1851页

作者： FANG Jian1,ZENG JinShan1,XU ZongBen1&ZHAO Yao2 1M inistry of Education Key Lab for Intelligent Networks and Network security Xi'an Jiaotong University,Xi'an 710049,china 2N ational Key Laboratory of Science and technology on Microwave Imaging&Institute of Electronics,chinese academy of sciences,beijing 100049,china 1. Ministry of Education Key Lab for Intelligent Networks and Network security Xi’an Jiaotong University Xi’an 710049 China2. National Key Laboratory of Science and Technology on Microwave Imaging & Institute of Electronics Chinese Academy of Sciences Beijing 100049 China

The displaced phase center antenna(DPCA)technique is an effective strategy to achieve wide-swath synthetic aperture radar(SAR)imaging with high azimuth ***,traditionally,it requires strict limitation of the pulse repetition frequency(PRF)to avoid non-uniform ***,any deviation could bring serious ambiguity if the data are directly processed using a matched *** break this limitation,a recently proposed spectrum reconstruction method is capable of recovering the true spectrum from the nonuniform ***,the performance is sensitive to the selection of the *** regularization based imaging may provide a way to overcome this *** existing time-domain method,however,requires a large-scale observation matrix to be built,which brings a high computational *** this paper,we propose a frequency domain method,called the iterative spectrum reconstruction method,through integration of the sparse regularization technique with spectrum analysis of the DPCA *** approximately expressing the observation in the frequency domain,which is realized via a series of decoupled linear operations,the method performs SAR imaging which is then not directly based on the observation matrix,which reduces the computational cost from O(N2)to O(N log N)(where N is the number of range cells),and is therefore more efficient than the time domain *** sparse regularization scheme,realized via a fast thresholding iteration,has been adopted in this method,which brings the robustness of the imaging process to the PRF *** provide a series of simulations and ground based experiments to demonstrate the high efficiency and robustness of the *** simulations show that the new method is almost as fast as the traditional mono-channel algorithm,and works well almost independently of the PRF ***,the suggested method can be accepted as a practical and efficient wide-swath SAR imaging technique.

关键词： displaced phase center antenna sparse regularization iterative thresholding spectrum reconstruction

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Intelligent Intrusion Detection System Model Using Rough Neural Network

Intelligent Intrusion Detection System Model Using Rough Neu...

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The 1st chinese Conference on Trusted Computing and information security

作者： YAN Huai-zhi,HU Chang-zhen, TAN Hui-min information security and Counter-Measure technology research center, beijing Institute of technology, beijing 100081, china National Key Laboratory of Mechatronics engineering and Control, beijing Institute of technology , beijing 100081, china

＜正＞ A model of intelligent intrusion detection based on rough neural network （RNN）. which combines the neural network and rough set, is presented. It works by capturing network packets to identify network intrusions or malicious attacks using RNN with sub-nets. The sub-net is constructed by detection-oriented signatures extracted using rough set theory to detect different intrusions. It is proved that RNN detection method has the merits of adaptive, high universality, high convergence speed, easy upgrading and management.

关键词： network security neural network intelligent intrusion detection rough set

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Web链接结构信息研究综述

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计算机科学 2003年第4期30卷 95-98,138页

作者：李剑金蓓弘中科院软件所软件工程技术中心北京100080

As the size of WWW is growing at an incredible rate, there is some limitation in the methods that only analyzes the Web pages' information. This paper presents a basic model of Web link structure. Then it classifies the algorithms that analyze the Web link structure information and their applications. At last, it presents the practical approach of analyzing Web link structure information.

关键词：网络搜索引擎网页内容 Web链接结构信息计算机网络

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