检索结果-南通市图书馆

Loose architecture of multi-level massive geospatial data based on virtual quadtree

在线全文

学校读者我要写书评

暂无评论

science china(Technological sciences) 2008年第S1期51卷 114-123页

作者： YANG ChongJun,WU Sheng,REN YingChao,FU Li,ZHANG FuQing,WANG Gang,TAN Jian,LIU DongLin,MA ChaoJi & LIANG Li State key laboratory of Remote Sensing science,Jointly Sponsored by the Institute of Remote Sensing Applications of Chinese Academy of sciences and beijing Normal University,beijing 100101,china 1. State key laboratory of Remote Sensing science Jointly Sponsored by the Institute of Remote Sensing Applications of Chinese Academy of Sciences and Beijing Normal University Beijing 100101 China

This paper proposed a virtual quadtree (VQT) based loose architecture of multi-level massive geospatial data for integrating massive geospatial data dispersed in the departments of different hierarchies in the same sector into a unified GIS (Geographic information System) platform. By virtualizing the nodes of the quad-tree,the VQT separates the structure of data organization from data storage,and screens the difference between the data storage in local computer and in the re-mote computers in network environment. And by mounting,VQT easily integrates the data from the remote computers into the local VQT so as to implement seam-less integration of distributed multi-level massive geospatial data. Based on that mode,the paper built an application system with geospatial data over 1200 GB distributed in 12 servers deployed in 12 cities. The experiment showed that all data can be seamlessly rapidly traveled and performed zooming in and zooming out smoothly.

关键词： massive geospatial data virtual quadtree loose architecture

The Application of Software Radio Receiver in GPS

在线全文

学校读者我要写书评

暂无评论

The Application of Software Radio Receiver in GPS

Pilot-aided channel estimation for CDD-OFDM systems

2005全国博士生学术论坛（交通运输工程学科）

作者： Xujingjing, Chen Houjin, Cheng Yinhang, Luo Rui (School of Electronics and information Engineering, beijing Jiaotong University, beijing 10004. key laboratory of all Optical network and advanced Telecommunication network, Ministry of Education, china, Institute of Lightwave technology, beijing Jiaotong University, beijing 10004.)

＜正＞ The paper describes Software Radio and its application in Global Positioning System （GPS） . Modern Software Defined Radio （MSDR） technology enables to digitalize and process radio signals in programmable digital micro-processor instead of analog or digital devices .The application of Software Radio technology mainly enables the system to get easier upgrade and higher speed in signal processing. The paper will give some figures to illustrate the principle of MSDR Receiver. The benefits and lacks of Software Radio Receiver in GPS are also brought up to discuss in comparison with conventional GPS Receiver. The architecture of one type of GPS Receiver named GpSrx is introduced. GpSrx is a real - time software radio receiver invented by Dennis M, Akos and others in the GPS laboratory Stanford University . GpSrx, which now is under researching, can process real - time signal on the frequency L1 . At the end of this paper, based on many researches, the author estimates the value of Software Radio Receiver and the foreground of its application in Chinese market.

关键词： modern software radio receiver intelligent transportation system (ITS) global Positioning system (GPS) DSP GpSrx

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

science china(information sciences) 2010年第2期53卷 379-389页

作者： FAN JianCun , YIN QinYe & WANG WenJie MOE key laboratory for Intelligent networks and network Security, Institute of information Engineering, Xi’an Jiaotong University, Xi’an 710049, china 1. MOE key laboratory for Intelligent networks and network Security Institute of Information Engineering Xi’an Jiaotong University Xi’an 710049 China

Cyclic delay diversity (CDD) is a low-complexity transmit diversity technique for coded orthogonal frequency division multiplexing (OFDM), which transforms a multiple-input channel into an equivalent singleinput channel with increased frequency selectivity and provides additional frequency diversity. However, it makes channel estimation more difficult due to the increased frequency selectivity. In this paper, focusing on the direct estimation of the equivalent single-input channel for CDD-OFDM systems, a cyclic cross-correlation channel estimation method based on the equispaced constant-modulus pilot structure is first proposed. Using the statistical parameters of the channel and noise derived by the cyclic cross-correlation channel estimation, an improved channel estimation method based on the Wiener filter is proposed to reduce the estimation error further. Lastly, computation simulations are given to demonstrate the effectiveness of two proposed channel estimation methods for CDD-OFDM systems.

关键词： channel estimation cyclic delay diversity OFDM systems cyclic cross-correlation Wiener filter

Proactive Content Delivery for Vehicles over Cellular networks:the Fundamental Benefits of Computing and Caching

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

china Communications 2018年第7期15卷 88-97页

作者： Jiping Jiao Xuemin Hong Jianghong Shi Department of Communications Engineering School of Information Science and Technology Xiamen University key laboratory of Underwater Acoustic Communication and Marine information technology Ministry of Education of China Xiamen University

The emergence of self-driving technologies implies that a future vehicle will likely become an entertainment center that demands personalized multimedia contents with very high quality. The surge of vehicular content demand brings significant challenges for the fifth generation(5G) cellular communication network. To cope with the challenge of massive content delivery, previous studies suggested that the 5G mobile edge network should be designed to integrate communication, computing, and cache(3C) resources to enable advanced functionalities such as proactive content delivery and in-network caching. However, the fundamental benefits achievable by computing and caching in mobile communications networks are not yet properly understood. This paper proposes a novel theoretical framework to characterize the tradeoff among computing, cache, and communication resources required by the mobile edge network to fulfill the task of content delivery. Analytical and numerical results are obtained to characterize the 3C resource tradeoff curve. These results reveal key insights into the fundamental benefits of computing and caching in vehicular mobile content delivery networks.

关键词： content delivery mobile edge network vehicular network

Frequency hopping sequences based on d-form functions

在线全文

学校读者我要写书评

暂无评论

The Journal of china Universities of Posts and Telecommunications 2010年第4期17卷 58-62页

作者： KE Pin-hui,ZHANG Sheng-yuan key laboratory of network Security and Cryptology,Fujian Normal University,Fuzhou 350007,china [a] key laboratory of network Security Cryptology Fujian Normal University Fuzhou 350007 China

By using d-form function, a new construction of frequency hopping sequence with optimal Hamming correlation is presented in this article, which generalizes the results presented by Ding （2007）. Furthermore, a new class of non-power function style d-form function is proposed and an upper bound of the Hamming autocorrelation of the corresponding sequence is also derived.

关键词： frequency hopping sequence hamming correlation d-form function spread spectrum communication

Monitoring Glacier and Supra-glacier Lakes from Space in Mt. Qomolangma Region of the Himalayas on the Tibetan Plateau in china

在线全文

学校读者我要写书评

暂无评论

Journal of Mountain science 2009年第3期6卷 211-220页

作者： YE Qinghua ZHONG Zhenwei KANG Shichang Alfred Stein WEI Qiufang LIU Jingshi key laboratory of Tibetan Environment Changes and Land Surface Processes Institute of Tibetan Plateau Research Chinese Academy of Sciences (CAS) Beijing 100085 China State key laboratory of Remote Sensing science Jointly Sponsored by the Institute of Remote Sensing Applications of Chinese Academy of Sciences and Beijing Normal University Beijing 100101 China International Institutefor Geo-information science and Earth Observation (ITC) PO Box 67500 AA Enschede The Netherlands

Because of the large number and remoteness, satellite data, including microwave data and optical imagery, have commonly been used in alpine glaciers surveys. Using remote sensing and Geographical information System （GIS） techniques, the paper presents the results of a multitemporal satellite glacier extent mapping and glacier changes by glacier sizes in the Mt. Qomolangma region at the northern slopes of the middle Himalayas over the Tibetan Plateau. Glaciers in this region have both retreated and advanced in the past 35 years, with retreat dominating. The glacier retreat area was 3.23 km2 （or o.75 km^2 yr^-1 during 1974 and 1976, 8.68 km^2 （or 0.36 km^2 yr^-1 during 1976 and 1992, 1.44 km^2 （or 0.12 km^2 yr^-1） during 1992-2ooo. 1.14 km^2 （or 0.22 km^2 yr^-1 during 2000-2003, and 0.52 km^2 （or 0.07 km^2 yr^-1 during 2003-2008, respectively. While supra-glacier lakes on the debris-terminus of the Rongbuk Glacier were enlarged dramatically at the same time, from 0.05 km^2 in 1974 increased to 0.71 km^2 in 2008, which was more than 13 times larger in the last 35 years. In addition, glacier changes also showed spatial differences, for example, glacier retreat rate was the fastest at glacier termini between 5400 and 5700 m a.s.l than at other elevations. The result also shows that glaciers in the middle Himalayas retreat almost at a same pace with those in the western Himalayas.

关键词： Glacier lake Remote Sensing Mr. Qomolangma region Himalayas Tibetan Plateau

Selective Ensemble Extreme Learning Machine Modeling of Effluent Quality in Wastewater Treatment Plants

在线全文

学校读者我要写书评

暂无评论

International Journal of Automation and computing 2012年第6期9卷 627-633页

作者： Li-Jie Zhao 1,2 Tian-You Chai 2 De-Cheng Yuan 1 1 College of information Engineering,Shenyang University of Chemical technology,Shenyang 110042,china 2 State key laboratory of Synthetical Automation for Process Industries,Northeastern University,Shenyang 110189,china 1. College of information Engineering Shenyang University of Chemical Technology Shenyang 110042 China 2. State key laboratory of Synthetical Automation for Process Industries Northeastern University Shenyang 110189 China

Real-time and reliable measurements of the effluent quality are essential to improve operating efficiency and reduce energy consumption for the wastewater treatment *** to the low accuracy and unstable performance of the traditional effluent quality measurements,we propose a selective ensemble extreme learning machine modeling method to enhance the effluent quality *** learning machine algorithm is inserted into a selective ensemble frame as the component model since it runs much faster and provides better generalization performance than other popular learning *** extreme learning machine models overcome variations in different trials of simulations for single *** ensemble based on genetic algorithm is used to further exclude some bad components from all the available ensembles in order to reduce the computation complexity and improve the generalization *** proposed method is verified with the data from an industrial wastewater treatment plant,located in Shenyang,*** results show that the proposed method has relatively stronger generalization and higher accuracy than partial least square,neural network partial least square,single extreme learning machine and ensemble extreme learning machine model.

关键词： Wastewater treatment process effluent quality prediction extreme learning machine selective ensemble model genetic algorithm.

Construction of Convolutional network Coding for Cyclic Multicast networks

在线全文

学校读者我要写书评

暂无评论

Construction of Convolutional Network Coding for Cyclic Mult...

SECURE AUTHENTICATION AND AUTHORIZATION SCHEME FOR MOBILE DEVICES

2010 IEEE 2nd Symposium on Web Society

作者： Qin Guo~(1,2,3),Mingxing Luo~(1,2,3),Lixiang Li~(1,2,3),Licheng Wang~(1,2,3),Yixian Yang~(1,2,3) 1 information Security Center,State key laboratory of networking and Switching technology, beijing University of Posts and Telecommunications,beijing 100876,china 2 key laboratory of network and information Attack and Defence technology of MOE, beijing University of Posts and Telecommunications,beijing 100876,china 3 National Engineering laboratory for Disaster Backup and Recovery, beijing University of Posts and Telecommunications,beijing 100876,china.

＜正＞In this paper,we present a practical algorithm to construct the convolutional multicast network coding over any finite directed cyclic *** dual line graph of a directed cyclic graph is considered as a *** regarding the global encoding kernels in the original graph as the corresponding inputs or outputs of some subsystem and the local encoding kernels in original graph as gains of channels,we can construct the convolutional network code through randomly choosing the local encoding kernels of the directed cycles in *** using Mason formula,the construction becomes very efficient.

关键词： Convolutional network code convolutional multicast dual line graph Mason formula

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

SECURE AUTHENTICATION AND AUTHORIZATION SCHEME FOR MOBILE DE...