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Frequency/time hopping sequence sets with optimal partial Hamming correlation properties

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Science china(Information Sciences) 2012年第10期55卷 2207-2215页

作者： NIU XianHua 1,2,PENG DaiYuan 1 & ZHOU ZhengChun 3 1 The Provincial Key Laboratory of Information Coding and Transmission,Institute of Mobile Communications,Southwest Jiaotong university,chengdu 610031,china 2 The School of Mathematics and Computer Engineering,Xihua university,chengdu 610039,china 3 The College of Maths,Southwest Jiaotong university,chengdu 610031,china The Provincial Key Laboratory of Information Coding and Transmission Institute of Mobile Communications Southwest Jiaotong University Chengdu China The School of Mathematics and Computer Engineering Xihua University Chengdu China The College of Maths Southwest Jiaotong University Chengdu China

Frequency hopping/time hopping(FH/TH) sequences have found wide applications in various modern FH/TH spread spectrum communications,such as digital cellular mobile communication,short-range wireless communication,personal communication,and multi-user radar,sonar *** order to evaluate the goodness of FH/TH sequences design,the periodic Hamming correlation function is used as an important ***,the length of correlation window is shorter than the period of the chosen FH/TH sequence,so the study of the partial Hamming correlation of FH/TH sequence is particularly *** this paper,a new class of FH/TH sequence sets with good partial Hamming correlation properties is proposed and *** construction of new FH/TH sequence sets is based upon the generalized m-sequence and generalized Gordon-Mills-Welch sequence over a polynomial residue class *** is shown that new FH/TH sequence sets are optimal with respect to the partial Hamming correlation bound.

关键词： frequency hopping/time hopping(FH/TH) sequence partial Hamming correlation optimal FH/TH sequence set

Centroid-based semi-fragile audio watermarking in hybrid domain

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Science china(Information Sciences) 2010年第3期53卷 619-633页

作者： WANG HongXia & FAN MingQuan School of Information Science and technology, Southwest Jiaotong university, chengdu 610031, china School of Information Science and technology Southwest Jiaotong University Chengdu China

Many previous (semi-) fragile audio watermarking schemes adopt binary images as watermarks, which reduce the security of watermarking systems. On the other hand, the content-based or feature-based second generation digital watermarking has limited applicability, and its partial feature points may be damaged by watermarking operations and various common signal processing. To overcome these problems, in this paper, a novel centroid-based semi-fragile audio watermarking scheme in hybrid domain is proposed. The theoretical lower limit of signal to noise ratio (SNR) for objective evaluation of the imperceptibility of watermarked audio signal is deduced, and the watermark embedding capacity and the tamper detection ability are theoretically analyzed. In the proposed scheme, first, the centroid of each audio frame is computed, then Hash function is performed on the obtained centroid to get the watermark, after that, the audio sub-band which carries centroid of audio frame is performed with discrete wavelet transform (DWT) and discrete cosine transform (DCT), and finally the encrypted watermark bits are embedded into the hybrid domain. Theoretical analysis and experimental results show that the proposed scheme is inaudible and applicable to different types of audio signals. Furthermore, its ability of tamper detection and tolerance against common signal processing operations are excellent. Comparing with the existing schemes, the proposed scheme can effectively authenticate the veracity and integrity of audio content, and greatly expand the applicability of the content-based audio watermarking scheme.

关键词： semi-fragile audio watermarking centroid inaudibility tamper detection

A new grid-associated algorithm in the distributed hydrological model simulations

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Science china(Technological Sciences) 2010年第1期53卷 235-241页

作者： XU Rui1,2,HUANG XiaoXue1,LUO Lin1 & LI ShaoCai3 1 State Key Laboratory of Hydraulics and Mountain River Engineering College of Architecture and Environment,Sichuan university,chengdu 610065,china 2 College of Electronic Engineering,Guilin university of Electronic technology,Guilin 541004,china 3 College of Life Sciences,Sichuan university,chengdu 610065,china State Key Laboratory of Hydraulics and Mountain River Engineering College of Architecture and Environment Sichuan University Chengdu China College of Electronic Engineering Guilin University of Electronic Technology Guilin China College of Life Sciences Sichuan University Chengdu China

This paper presents a new grid-associated algorithm to improve the performance of a D8 algorithm based distributed hydrological model *** algorithm is based on the well known single-flow D8 algorithm of grid *** algorithm allocates calculation priorities according to the distance between the units and the outlet,then carries out the ergodic computations of the hydrological units according to the priority *** the parallelized algorithm,a standard thread-level shared memory system for parallel programming(OpenMP-Open specifications for Multi Processing) was introduced,and the parallel coding was implemented in C lan-guage.A case study showed that the absolute speed-up ratio of the grid-associated algorithm is 1.64 over the original D8 algorithm,and the linear speed-up ratio of the parallel associated algorithm is 2.42 under 4 *** parallel grid-associated algorithm can be applied to a variety of research fields that use the grid method.

关键词： distributed hydrological model grid-association algorithm OpenMP parallel computing

Research on paleo-fluid sources and hydrocarbon preservation conditions in marine carbonates inthe central Yangtze,china

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Petroleum Science 2011年第3期8卷 239-250页

作者： Wang Guozhi Xu Guosheng Yuan Haifeng Hu Xiaofeng Zou Can State Key Laboratory of Oil and Gas Reservoir Geology and Exploitation Chengdu University of Technology Chengdu 610059 China School of Earth Science Chengdu University of Technology Chengdu 610059 China Research Institute of Petroleum Exploration and Development Jianghan Oilfield Company SINOPEC Qianjiang Hubei 433124 China College of Foreign Languages ＆ Cultures Chengdu University of Technology Chengdu 610059 China

^87Sr/^86Sr, δ^18O and δ^13C ratios of calcite, dolomite, gypsum filling vugs and fissures in marine carbonates and their host rocks from the Sinian to the middle Triassic, are employed to trace the possible source and migration path of key fluids related to development of hydrocarbon, hydrocarbon preservation condition are then discussed further. Comprehensive research, based on the paleo-fluid, the property of formation water and the deformation intensity etc., indicates that the preservation conditions in the Shizhu synclinorium zone and Fangdoushan anticlinorium zone are the most predominant in the central Yangtze. Three sets of fluid systems in the Shizhu synclinorium zone are identified. Little fluid exchange occurs between the upper-middle fluid system and the lower fluid system, so two independent preservation units have developed. Both the Permian and the Triassic in the upper preservation units and the Dengying Formation of the Sinian and the lower Cambrian in the lower preservation units have good preservation conditions. The preservation condition in the lower association （Z-S） located in the Huaguoping synclinorium zone in the western Hubei and Hunan is better than that in other tectonic units, where the fluids in the lower association migrated vertically across strata when the fluid isolating intervals were destroyed, the regional seals are absent and the conditions for the preservation of hydrocarbon accumulations are totally destroyed. The preservation condition is increasingly more favorable from the western Jiangxi and Hunan to the western Hubei ＆ eastern Chongqing on the whole.

关键词： The central Yangtze marine carbonate fluid, ^87Sr/^86Sr geochemistry trace preservation condition

Adaptive detection for distributed targets in Gaussian noise with Rao and Wald tests

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Science china(Information Sciences) 2012年第6期55卷 1290-1300页

作者： SHUAI XiaoFei,KONG LingJiang & YANG JianYu School of Electronic Engineering,university of Electronic Science and technology of china,chengdu 610054,china School of Electronic Engineering University of Electronic Science and Technology of China Chengdu China

The problem of adaptively detecting a range distributed target or targets in Gaussian interference is considered in this *** is assumed that a set of secondary data is ***,we derive the adaptive Rao and Wald tests with one-step detection algorithm,and find that both of them are of the same asymptotic performance as the GLRT ***,the Rao and Wald tests are derived by resorting to the two-step design *** our surprise,our derivations show that all the Rao,Wald and GLR tests in the two-step design strategy are ***,the property assessments are *** is shown that these new detectors guarantee CFAR property with respect to the Gaussian ***,simulation results show that these results are accurate.

关键词： Rao and Wald tests adaptive detection distributed targets maximum likelihood estimator

Top 10 Influential Events in carbon neutrality and climate change response for 2023

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Frontiers in Energy 2024年第1期18卷 1-3页

作者： Research Institute of Carbon Neutrality of Shanghai Jiao Tong university Research Institute of Carbon Neutrality Shanghai Jiao Tong UniversityShanghai 200240China

In 2023, the global community intensified its efforts towards achieving carbon neutrality and addressing climate change, witnessing several impactful events. Research Institute of Carbon Neutrality, Shanghai Jiao Tong university compiled the Top 10 Events (in chronological order) in the field of global carbon neutrality and climate change response for 2023, to share with readers these significant moments that document the ongoing ambition and collective efforts of human society.

关键词： neutral collective intensified

On the maximum likelihood method for target localization using MIMO radars

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Science china(Information Sciences) 2010年第10期53卷 2127-2137页

作者： XIA Wei , HE ZiShu & LIAO YuYu School of Electronic Engineering, university of Electronic Science and technology of china, chengdu 611731, china School of Electronic Engineering University of Electronic Science and Technology of China Chengdu China

A multiple-input multiple-output (MIMO) radar uses multiple antennas to simultaneously transmit multiple independent probing signals, and uses multiple antennas to receive the backscattered signals. The modeling of MIMO radar with transmit spatial diversity and coherent reception is addressed herein. The maximum likelihood (ML) method for parameter estimation using MIMO radars is considered, and two approximate ML algorithms are proposed. In the uniform noise scenario, one of the proposed algorithms performs similarly to the delay-and-sum beamformer which is optimal in the ML sense in single target case, while it outperforms the other proposed approximate ML algorithm at the cost of more computational load. In the non-uniform noise scenario, the proposed approximate ML algorithms both outperform the delay-and-sum beamformer. The efficiency of the proposed methods is validated by the simulation results.

关键词： maximum-likelihood multiple-input multiple-output (MIMO) radars parameter estimation

Land Use of the Three Gorges Reservoir Area and the Effect on Its Landscape Pattern in the Recent 50 Years

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Wuhan university Journal of Natural Sciences 2006年第4期11卷 910-914页

作者： HUANG Zhiqin 1,2,3 , ZHOU Wancun 1 ,ZHOU Jieming 4 , ZHU Mingcang 3,5 1. Institute of Mountain Hazards and Environment, Chinese Academy of Sciences , chengdu 610041, Sichuan, china 2. Graduate university of Chinese Academy of Sciences, Beijing 100049, china 3. Sichuan Institute of Land Resource Management, chengdu 610041, Sichuan , china 4. Department of Resources and Environment Science, Sichuan Normal university , chengdu 610061, Sichuan, china 5. College of Information Engineering, chengdu university of technology, chengdu 610059, Sichuan, china Institute of Mountain Hazards and Environment Chinese Academy of Sciences Chengdu Sichuan China Graduate university of Chinese Academy of Sciences Beijing China Sichuan Institute of Land Resource Management Chengdu Sichuan China Department of Resources and Environment Science Sichuan Normal University Chengdu Sichuan China College of Information Engineering Chengdu University of Technology Chengdu Sichuan China

The paper makes detailed analysis on the changing processes of the main types of land use in Three Gorges Reservoir Area through the techniques of RS （Remote Sense） and GIS （Geography Information System）. Based on the theory of landscape ecology, many types of landscape pattern indexes are calculated and made correlation analysis. The results indicate that： in 1995 the ecological environment of Three Gorges Reservoir Area was the most vulnerable in the recent 50 years, but resumed in 2002; the landscape pattern diversity index, fractal dimension index and fragmentation index has close correlation with the area of land use/cover change （LUCC）. The research also releases that the increase of the cultivated land, grassland and construction land deteriorates the landscape ecological pattern, while the increase of forest land area will help restore the landscape ecological pattern to its original state. The rapid change of grassland is an important index of the change of landscape pattern, because it has the most effect on change of landscape pattern index.

关键词： the Three Gorges Reservoir Area land use/cover change landscape pattern.

Single-channel blind separation of overlapped multicomponents based on energy operator

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Science china(Information Sciences) 2010年第1期53卷 147-157页

作者： CAI QuanWei, WEI Ping & XIAO XianCi College of Electronic Engineering, university of Electronic Science and technology of china, chengdu 610054, china College of Electronic Engineering University of Electronic Science and Technology of China Chengdu China

A method utilizing single channel recordings to blind separate the multicomponents overlapped in both time and frequency domains is proposed in this paper. The main idea of the method is based on using the energy operator and differential energy operator to estimate instantaneous frequencies and amplitudes of each component and then to reconstruct these components. This method, due to the good time resolution of the energy operator and differential energy operator, as well as the very low computational complexity, is very useful in real time processing and practical applications. Simulation results demonstrated the effciency of this method.

关键词： single channel time frequency overlap multicomponents separation energy operator differential energy operator