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Synchronous estimation of DTM and fractional vegetation cover in forested area from airborne LIDAR height and intensity data

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Science china(Technological Sciences) 2008年第S2期51卷 176-187页

作者： BAO YunFei1,2,CAO ChunXiang1,ZHANG Hao1,CHEN ErXue3,HE QiSheng1,2,HUANG HuaBing1,LI ZengYuan3,LI XiaoWen1,4 & GONG Peng1 1 state key laboratory of Remote Sensing Science,jointly sponsored by the Institute for Remote Sensing Applications of Chinese Academy of Sciences and beijing Normal University,beijing 100101,china 2 Graduate University of the Chinese Academy of Sciences,beijing 100049,china 3 Institute of Forest Resource information Technique,the Chinese Academy of Forestry,beijing 100091,china 4 Research Center for Remote Sensing and GIS,Department of Geography and beijing key laboratory for Remote Sensing of Environment and Digital Sites,beijing Normal University,beijing 100875,china state key laboratory of Remote Sensing Science jointly sponsored by the Institute for Remote Sensing Applications of Chinese Academy of Sciences and Beijing Normal University Beijing 100101 China Graduate University of the Chinese Academy of Sciences Beijing 100049 China Institute of Forest Resource information Technique the Chinese Academy of Forestry Beijing 100091 China Research Center for Remote Sensing and GIS Department of Geography and Beijing Key Laboratory for Remote Sensing of Environment and Digital Sites Beijing Normal University Beijing 100875 China

We proposed a method to separate ground points and vegetation points from discrete return,small footprint airborne laser scanner data,called skewness change *** method,which makes use of intensity of laser scanner data,is especially applicable in steep,and forested *** does not take slope of forested area into account,while other algorithms consider the change of slope in steep forested *** ground points and vegetation points can be used to estimate digital terrain model(DTM) and fractional vegetation cover,respectively.A few vegetation points which were classified into the ground points were removed as noise before the generation of *** method was tested in a test area of 10000 square meters.A LiteMapper -5600 laser system was used and a flight was carried out over a ground of 700―800 *** this tested area,a total number of 1546 field measurement ground points were measured with a total station TOPCON GTS-602 and TOPCON GTS -7002 for validation of DTM and the mean error value is -18.5 cm and the RMSE(root mean square error) is ±20.9 cm.A data trap sizes of 4m in diameter from airborne laser scanner data was selected to compute vegetation fraction *** of fractional vegetation cover was carried out using 15 hemispherical photographs,which are georeferenced to centimeter accuracy by differential *** gap fraction was computed over a range of zenith angles 10° using the gap light analyzer(GLA) from each hemispherical *** R2 for the regression of fractional vegetation cover from these ALS data and the respective field measurements is *** this study presents a method for synchronous estimation of DTM and fractional vegetation cover in forested area from airborne LIDAR height and intensity data.

关键词： LIDAR intensity skewness synchronous DTM fractional vegetation cover

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New application methods for word-oriented cryptographic primitives

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Science china(information Sciences) 2012年第9期55卷 2149-2160页

作者： YANG Yang 1,2,ZENG Guang 1,2,JIN ChengHui 1 & QU YunYing 1 1 Zhengzhou information Science and Technology Institute,Zhengzhou 450002,china 2 state key laboratory of information security,Institute of Software,Chinese Academy of Sciences,beijing 100190,china 1. Zhengzhou information Science and Technology Institute Zhengzhou 450002 China2. State Key Laboratory of Information Security Institute of Software Chinese Academy of Sciences Beijing 100190 China

Modern software oriented symmetric ciphers have become a key feature in utilizing word-oriented cryptographic *** the output sequence,in the order of its generation,of a word-oriented cryptographic primitive in the same way as traditional bit-oriented primitives,we can expose the intrinsic weakness of these primitives,especially for word-oriented linear feedback shift registers,T-functions,and so *** new methods for using word-oriented cryptographic primitives are presented in this paper,that is,the extracted state method and cascading extracted coordinate *** a T-function as an example,we research the different cryptographic properties of the output sequences of the original method and the two proposed methods,focusing mainly on period,linear complexity,and k-error linear *** conclusions show that the proposed methods could enhance at low cost the cryptographic properties of the output *** a result,since the new methods are simple and easy to implement,they could be used to design new word-oriented cryptographic primitives.

关键词： stream cipher single cycle T-function linear complexity k-error linear complexity

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Competent predicate abstraction in model checking

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Science china(information Sciences) 2011年第2期54卷 258-267页

作者： LI Li1,2,3, SONG XiaoYu4, GU Ming2,3 & LUO XiangYu2,3 1Department of Computer Science & Technology, Tsinghua University, beijing 100084, china 2key laboratory for information System security, Ministry of Education of china, beijing 100084, china 3School of Software, Tsinghua University, beijing 100084, china 4Department of ECE, Portland state University, Portland, Oregon 97207, USA 1. Department of Computer Science & Technology Tsinghua University Beijing 100084 China2. Key Laboratory for Information System Security Ministry of Education of China Beijing 100084 China3. School of Software Tsinghua University Beijing 100084 China4. Department of ECE Portland State University Portland Oregon 97207 USA

The paper presents a new approach to computing the abstract state and a maximum weight heuristic method for finding the shortest counter-example in verification of imperative programs. The strategy is incorporated in a verification system based on the counterexample-guided abstraction refinement method. The proposed method slashes both the size of the abstract state space and the number of invokes of a decision procedure. A number of benchmarks are employed to evaluate the effectiveness of the approach.

关键词： program model checking predicate abstraction weight heuristic

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A tetrahedral data model for unstructured data management

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Science china(information Sciences) 2010年第8期53卷 1497-1510页

作者： LI Wei & LANG Bo state key laboratory of Software Development Environment, Beihang University, beijing 100191, china 1. state key laboratory of Software Development Environment Beihang University Beijing 100191 China

This paper proposes a tetrahedral data model for unstructured data management. The model defines the four components of unstructured data including: basic attributes, semantic characteristics, low-level features and raw data on its four facets, and the relations between these components. The internal implementation structure of the model and the data query language are designed and briefly introduced. This model provides a unified, integrated and associated description for different kinds of unstructured data, and supports intelligent data services such as associated retrieval and data mining. An example is given to demonstrate how to use the model for describing and manipulating data from a sample video base.

关键词： unstructured data data model query language associated retrieval intelligent services

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Experimental study of gas-water elongated bubble flow during production logging

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Petroleum Science 2011年第2期8卷 157-162页

作者： Lu Jing Wu Xiling key laboratory of Earth Prospecting and information Technology China University of Petroleum Beijing 102249 China state key laboratory of Petroleum Resource and Prospecting China University of Petroleum Beijing 102249 China

In order to improve the interpretation of production log data on gas-water elongated bubble （EB） flow in horizontal wells, a multi-phase flow simulation device was set up to conduct a series of measurement experiments using air and tap water as test media, which were measured using a real production logging tool （PLT） string at different deviations and in different mixed flow states. By understanding the characteristics and mechanisms of gas-water EB flow in transparent experimental boreholes during production logging, combined with an analysis of the production log response characteristics and experimental production logging flow pattern maps, a method for flow pattern identification relying on log responses and a drift-flux model were proposed for gas-water EB flow. This model, built upon experimental data of EB flow, reveals physical mechanisms of gas-water EB flow during measurement processing. The coefficients it contains are the specific values under experimental conditions and with the PLT string used in our experiments. These coefficients also reveal the interference with original downhole flow patterns by the PLT string. Due to the representativeness that our simulated flow experiments and PLT string possess, the model coefficients can be applied as empirical values of logging interpretation model parameters directly to real production logging data interpretation, when the measurement circumstances and PLT strings are similar.

关键词： Horizontal wells elongated bubble flow flow patterns identification drift-flux model,logging interpretation model

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A prototype auto-human support system for spatial analysis

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Progress in Natural Science:Materials International 2006年第9期16卷 954-966页

作者： LI Lianfa and WANG Jinfeng (state key laboratory of Resources & Environmental information System, Institute of Geographical Sciences & Natural Resources Research, Chinese Academy of Sciences, beijing 100101, china) [a]state key laboratory of Resources & Environmental information System Institute of Geographical Sciences & Natural Resources Research Chinese Academy Sciences Beijing China

Spatial analysis is a multidisciplinary field that involves multiple influential factors, variation and uncertainty, and modeling of geospatial data is a complex procedure affected by spatial context, mechanism and assumptions. In order to make spatial modeling easier, some scholars have suggested a lot of knowledge from exploratory data analysis (EDA), specification of the model, fitness and diagnosis of the model, to interpretation of the model. Also an amount of software has improved some functionalities of spatial analysis, e. g. EDA by the dynamic link (GeoDa) and robust statistical calculation (R). However, there are few programs for spatial analysis that can automatically deal with unstructured declarative issues and uncertainty in machine modeling using the domain knowledge. Under this context, this paper suggests a prototype support system for spatial analysis that can automatically use experience and knowledge from the experts to deal with complexity and uncertainty in modeling. The knowledge base component, as the major contribution of the system, in support of the expert system shell, codes and stores declarative modeling knowledge, e.g. spatial context, mechanisms and prior knowledge to deal with declarative issues during the modeling procedure. With the open architecture, the system integrates functionalities of other components, e.g. GIS’ visualization, DBMS, and robust calculation in an interactive environment. An application case of spatial sampling, design and implementation of spatial modeling with such a system is demonstrated.

关键词： spatial analysis automatic support system modeling of spatial data artificial inference for modeling.

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Simulation of dam breach development for emergency treatment of the Tangjiashan Quake Lake in china

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Science china(Technological Sciences) 2008年第S2期51卷 82-94页

作者： WANG GuangQian,LIU Fan,FU XuDong & LI TieJian state key laboratory of Hydroscience and Engineering,Tsinghua University,beijing 100084,china state key laboratory of Hydroscience and Engineering Tsinghua University Beijing 100084 China

The Tangjiashan Quake Lake is the largest quake lake triggered by the 5.12 Wenchuan Earthquake that happened on May 12,2008 in china,posing high risk of catastrophic flash flood hazards to downstream human life and properties.A physics-based numerical simulation approach is proposed for real-time prediction of dam breach development of the Tangjiashan Quake Lake in the case of emergency *** erosion and lateral development of the dam breach are represented through accounting for the underlying physics including selective sediment transport and gravitational *** breach erosion model that involves few parameters enables quick calibration based on the monitored hydrological data in emergency analysis where fully geotechnical information about the barrier dam is not *** process of dam breach development is found to be nonlinear in cascades due to the combined effects of headcutting and bank *** agreement between the simulation results and the observed data shows the applicability of the present approach for emergency analysis of quake *** will arise in the situation where the soil composition of barrier dam is significantly *** of circular arc failure for cohesive soil and lateral seepage in bank slope will also enhance its applicability to complex situations.

关键词： quake lake earthquake dam breach simulation numerical model erosion collapse headcutting

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The C-topology on lattice-ordered groups

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Science china Mathematics 2009年第11期52卷 2397-2403页

作者： YANG YiChuan Department of Mathematics,key laboratory of Ministry of Education for information Mathematics and Behavior,Beihang University,beijing,100191 china 1. Department of Mathematics Key Laboratory of Ministry of Education for Information Mathematics and Behavior Beihang University 100191 Beijing China

Let A be a lattice-ordered group. Gusi? showed that A can be equipped with a C-topology which makes A into a topological group. We give a generalization of Gusi?’s theorem, and reveal the very nature of a “C-group” of Gusi? in this paper. Moreover, we show that the C-topological groups are topological lattice-ordered groups, and prove that every archimedean lattice-ordered vector space is a T 2 topological lattice-ordered vector space under the C-topology. An easy example shows that a C-group need not be T 2. A further example demonstrates that a T 2 topological archimedean lattice-ordered group need not be C-archimedean, either.

关键词： C-topology lattice-ordered group archimedean lattice-ordered group Hausdorff topology vector space 06F30 22A99

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Instantiate Random Oracles in OAEP with Pseudorandom Functions

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Wuhan University Journal of Natural Sciences 2008年第6期13卷 651-656页

作者： JIA Xiaoying LI Hongda LI Bao state key laboratory of information security/Graduate University of Chinese Academy of Sciences Beijing 100049 China

This paper focuses on the instantiation of random oracles in public key encryption schemes. A misunderstanding in the former instantiations is pointed out and analyzed. A method of using this primitive as a substitution of random oracles is also proposed. The partial and full instantiations of random oracles in optimal asymmetric encryption padding （OAEP） implemented by pseudorandom functions are described and the resulted schemes are proven to be indistinguishable secure against adaptive chosen ciphertext attack （IND-CCA2） secure. Using this method, one can transform a practical public key encryption scheme secure in the random oracle model into a standard-model secure scheme. The security of the scheme is based on computational assumptions, which is weaker than decisional assumptions used in Cramer- Shoup like schemes.

关键词： random oracle(RO) model instantiation optimal asymmetric encryption padding(OAEP) indistinguishable securitity against adaptive chosen ciphertext attack (IND-CCA2)

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Study of the structure of unstable nuclei through the reaction experiments

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Science china(Physics,Mechanics & Astronomy) 2011年第S1期54卷 1-5页

作者： CAO ZhongXin & YE YanLin state key laboratory of Nuclear Physics and Technology, School of Physics, Peking University, beijing 100871, china 1. state key laboratory of Nuclear Physics and Technology School of Physics Peking University Beijing 100871 China

Along with the development of the radioactive nuclear beam facility, the study of the structure of unstable nuclei has progressed rapidly over the last few decades. Due to the weakly binding property, the structure information of the unstable nuclei comes primarily from the scattering or reaction experiments. Therefore it would be very important to understand clearly the reaction mechanism involved in the experiment. We outlined here the major reaction mechanisms which are adequate to the study of unstable nuclei, with the focus on the new phenomena and methods in comparison with those with traditional stable nucleus beam. Especially emphasized are the breakup and knockout reactions, developed as accurate tools for spectroscopy investigation into the nuclear structure with low intensity secondary beam. Couplings of the breakup channel to the elastic scattering and the fusion and transfer reactions are also reviewed.

关键词： binaries: unstable nuclei nuclear structure breakup reaction knockout reaction fusion reaction transfer reaction

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