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The Ternary Goldbach Problem with Primes in Arithmetic Progressions

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Acta Mathematica Sinica,English Series 2001年第4期17卷 679-696页

作者： Zhen Feng ZHANG Tian Ze WANG state key laboratory of information security, Graduate School, Chinese Academy of Sciences, beijing 100039, P. R. china Depariment of Mathematics, Henan University, Kaifeng 475001, P. R. china Department of Mathematics, Henan University, Kaifeng 475001, P. R. china state key laboratory of information security Graduate School Chinese Acacemy of Sciences Beijing 100039 P. R. China Department of Mathematics Henan University Kaifeng 475001 P. R. China

In this paper, we give an explicit numerical upper bound for the moduli of arithmetic progressions, in which the ternary Goldbach problem is solvable. Our result implies a quantitative upper bound for the Linnik const... 详细信息

关键词： Ternary Goldbach problem Prime Arithmetic progression Circle method

Image-based modeling of inhomogeneous single-scattering participating media

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Science china(information Sciences) 2010年第6期53卷 1141-1150页

作者： HU Yong 1 , QI Yue 1 & TONG Xin 2 1 state key laboratory of Virtual Reality Technology and Systems, Beihang University, beijing 100191, china 2 Microsoft Research Asia, beijing 100080, china state key laboratory of Virtual Reality Technology and Systems Beihang University Microsoft Research Asia

We propose a method to reconstruct inhomogeneous single-scattering participating media, which could preserve fine high-frequency details of density *** data and the ratio of absorption coefficient to scattering coefficient are used to describe the spatial-varying density distribution and optical properties of certain participating media, and a function between the above parameters and captured pixel values is *** the problem of how to find solutions to these parameters is formulated into a nonlinear numerical optimization *** order to reduce large time overheads and numerical instability brought by simultaneously solving large numbers of voxels, we propose an initialization algorithm for enabling the assigned density values to satisfy the regularity of brightness distribution in captured images approximately as well as a progressive refinement algorithm for multi-resolution volumetric ***, we propose a parallel multi-voxel gradient computation algorithm of utilizing hardware acceleration to reduce time overheads in gradient computation for large numbers of *** results indicate that our method is well suited for reconstructing thin smoke, retaining high-frequency details from images captured from multiple viewpoints.

关键词： single-scattering participating media smoke modeling volumetric modeling image based modeling

Differential Hydrological Grey Model (DHGM) with self-memory function and its application to flood forecasting

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Science china(Technological Sciences) 2009年第4期52卷 1039-1049页

作者： CHEN XiangDong1, XIA Jun1,2 & XU Qian3 1 key laboratory of Water Cycle and Related Land Surface Processes, Institute of Geographic Sciences and Natural Resources Research, Chinese Academy of Sciences, beijing 100101, china 2 state key laboratory of Water Resources and Hydropower Engineering Science, Wuhan University, Wuhan 430072, china 3 School of Hydrology and Water Resources, Hohai University, Nanjing 210098, china key laboratory of Water Cycle and Related Land Surface Processes Institute of Geographic Sciences and Natural Resources Research Chinese Academy of Sciences state key laboratory of Water Resources and Hydropower Engineering Science Wuhan University S

This paper addresses a problem of flood forecasting with the self-memory function. Considering flood forecasting’s uncertainty and updating demand, a hybrid hydrological model, namely Differential Hy- drological Grey Model with self-memory function (DHGM-SM), is developed. The model has two fold features. One is to establish a self-memorization equation linked with DHGM, that could extract useful information from past data series and realize updating of hydrological dynamic process. The other is that this model has higher efficiency relative to original hydrological model without self-memory func- tion. This approach was applied to river flow forecasting of two representative basins in Tunxi of South china and Daqinggou of North china. It is shown that this hybrid method has satisfactory forecasting accuracy by examination of both calibration and validation.

关键词： differential grey model the self-memorization principle real-time forecasting faded-memory recursive least square method

Development of silicon-based microelectrode array

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Science china(Technological Sciences) 2009年第8期52卷 2391-2395页

作者： LIN JianHui1,2,3, WU XiaoMing1,2,3,4, HUANG PengSheng1,2, FENG Lei5, REN TianLing1,2 & LIU LiTian1,2 1 Institute of Microelectronics, Tsinghua University, beijing 100084, china 2 Tsinghua National laboratory for information Science and Technology, beijing 100084, china 3 Yangtze Delta Region Institute of Tsinghua University, Jiaxing 314050, china 4 state key laboratory of Transducer Technology, Chinese Academy of Sciences, Shanghai 200050 china 5 Department of Biomedical Engineering, Tsinghua University, beijing 100084, china Institute of Microelectronics Tsinghua University Tsinghua National laboratory for information Science and Technology

This paper introduces in details a kind of silicon-based microelectrode array. MEMS (micro-electromechanical system) technology is used in the fabrication of the microelectrode array, which is designed to perform signal recording and electrical stimulation for nerves in neural engineering. A simple fabrication process is developed. An improved model of microelectrodes is brought forward and successfully validated by the excellent match between circuit simulations and electrical measurements, including both magnitude and phase of microelectrode impedance. Compared with the simple one that is usually used, the improved model is believed to be an advance and more accurate. This modeling helps to improve the design of microelectrodes and understand the behavior of interface between electrode and cell. Furthermore, the microelectrode is proved to be a feasible tool for researches in neural engineering by successfully recording neural activities of sciatic nerve of a bullfrog.

关键词： microelectrode array MEMS neural engineering

An urban traffic environment model

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Journal of Environmental Sciences 1999年第3期11卷 339-343页

作者： Wang Jin\|feng state key laboratory of Resources and Environmental information System, Institute of Geography, Chinese Academy of Sciences, beijing 100101, china. E mail: wangjf@*** 中科院地理所资源与环境信息系统国家重点实验室北京

Urban environment pattern depends heavily upon urban traffic pattern, the balance between traffic (implicit production) and environment leads to the urban sustainable development. An integrated urban traffic environment model consists of three components of urban production variables (population density, GDP, salary, etc. in blocks), urban traffic variables and urban environmental variables; and two links between urban traffic planning variables and urban environment variables, and between spatial interaction model (SIM) and traffic planning variables as well. The model is quite useful in urban environment impact assessment; urban traffic management; urban sustainable development planning; and urban development decision\|making.

关键词： SIM urban environment urban traffic planning decision making.

The Research on Cryptographic Schemes

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ZTE Communications 2007年第4期5卷 1-5页

作者： Zheng Shihui (information security Center of state key laboratory of Networking and Switching Technology, beijing University of Posts and Telecommunications, beijing 100876, china)

Cryptography is an important technology for information security. It mainly includes symmetric and asymmetric cryptographic algorithms and protocols. For the symmetric cryptographic algorithms, it is easy to deduce decryption keys from the encryption keys and vice versa. Because this algorithm encrypts and decrypts data very quickly, it is applicable in situations where large numbers of data have to be protected. However, for the asymmetric algorithm, extracting the secret key from the public key is computationally infeasible. Although the performance speed of the asymmetric algorithm is much slower than that of the symmetric algorithm, the asymmetric algorithm has key distribution and management advantages over the symmetric one. Moreover, it is a perfect digital signature scheme.

关键词： Hash The Research on Cryptographic Schemes

Hydrocarbon Reservoir Model of Glutenite in the Fourth Member of Shahejie Formation in Northern Dongying Depression

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地学前缘 2009年第S1期16卷 136-137页

作者： Hui Liu~(1,2),Yingchang Cao~3,Yanzhong Wang~3 1.state key laboratory of Geological Processes and Mineral Resources,china University of Geosciences,beijing 100083, china. 2.School of Energy Resources,china University of Geosciences(beijing),beijing 100083,china 3.Faculty of Geo-Resources and information,china University of Petroleum,Dongying 257061,china

The glutenite in the fourth member of Shahejie Formation(Es^4) in northern Dongying depression straightforwardly penetrated into the muddy bathyal -abyss *** conditions of reservoir is very superior:(1) the high quality thick bedded oil source rock is developed very well in the Lijin sag and Minfeng sag of the study area,and it has the higher capability of generating hydrocarbon;(2) the

关键词： glutenite hydrocarbon reservoir formation northern Dongying depression fourth member of Shahejie Formation

GIS and ANN model for landslide susceptibility mapping

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Journal of Geographical Sciences 2001年第3期11卷 374-381页

作者： XU Zeng-wang (state key laboratory of Resources and Environment information System, Institute of Geographic Sciences and Natural Resources Research, CAS, beijing 100101, china) state key laboratory of Resources and Environment information System Institute of Geographic Sciences and Natural Resources Research CAS

Landslide hazard is as the probability of occurrence of a potentially damaging landslide phenomenon within specified period of time and within a given area. The susceptibility map provides the relative spatial probability of landslides occurrence. A study is presented of the application of GIS and artificial neural network model to landslide susceptibility mapping, with particular reference to landslides on natural terrain in this paper. The method has been applied to Lantau Island, the largest outlying island within the territory of Hong Kong. A three-level neural network model was constructed and trained by the back-propagate algorithm in the geographical database of the study area. The data in the database includes digital elevation modal and its derivatives, landslides distribution and their attributes, superficial geological maps, vegetation cover, the raingauges distribution and their 14 years 5-minute observation. Based on field inspection and analysis of correlation between terrain variables and landslides frequency, lithology, vegetation cover, slope gradient, slope aspect, slope curvature, elevation, the characteristic value, the rainstorms corresponding to the landslide, and distance to drainage Une are considered to be related to landslide susceptibility in this study. The artificial neural network is then coupled with the ArcView3.2 GIS software to produce the landslide susceptibility map, which classifies the susceptibility into three levels: low, moderate, and high. The results from this study indicate that GIS coupled with artificial neural network model is a flexible and powerful approach to identify the spatial probability of hazards.

关键词： GIS artificial neural network model landslide susceptibility mapping

Multi-channel SAR imaging based on distributed compressive sensing

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Science china(information Sciences) 2012年第2期55卷 245-259页

作者： LIN YueGuan1,2,3,ZHANG BingChen1,2,JIANG Hai1,2,3,HONG Wen1,2 & WU YiRong1,2 1National key laboratory of Science and Technology on Microwave Imaging,beijing 100190,china 2Institute of Electronics,Chinese Academy of Sciences,beijing 100190,china 3Graduate University of Chinese Academy of Sciences,beijing 100049,china National key laboratory of Science and Technology on Microwave Imaging Institute of Electronics Chinese Academy of Sciences Graduate University of Chinese Academy of Sciences

The rapid development of compressive sensing(CS)shows that it is possible to recover a sparse signal from very limited *** aperture radar(SAR)imaging based on CS can reconstruct the target scene with a reduced number of collected samples by solving an optimization *** multi-channel SAR imaging based on CS,each channel requires sufficient samples for separate imaging and the total number of samples could still be *** propose an imaging algorithm based on distributed compressive sensing(DCS)that reconstructs scenes jointly under multiple ***-channel SAR imaging based on DCS not only exploits the sparsity of the target scene,but also exploits the correlation among *** requires significantly fewer samples than multi-channel SAR imaging based on *** multiple channels offer different sampling rates,DCS joint processing can reconstruct target scenes with a much more flexible allocation of the number of measurements offered by each channel than that used in separate CS processing.

关键词： synthetic aperture radar multi-channel synthetic aperture radar compressive sensing distributed compressive sensing