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Self-Organizing Tunnel Peers

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计算机工程 2002年第S1期28卷 7-12页

作者： CHEN Maoke , LI Xing (department of electronic Engineering, tsinghua university, {4. 100084.china ) department of electronic Engineering Tsinghua University Beijing 100084China

Tunneling is an important approach in IPv6 transition techniques. The tunnel broker model provides a way to build virtual IPv6 networks without manual ***, neither it adapts performance variation on the IPv4.infrastructure, norit is a scalable solution for a wide-area IPv6 networking environment. In this paper, a self-organizing tunnel peer (SOTP) model is *** peers are clustered in the SOTP system so that optimization is scalable. Four primitive operations related to --cluster constructionarrest,release,division and deathendow the system with the nature of self-organization. Occurrence and behavior of the operations are decided by criteria on the IPv4.end-to-end performance; hence measurement is an indispensable component of the system. The metabolism of cluster relaxes the requirement to accuracy of measurement and optimization.

关键词： S elf-organizationTunnelingEnd-to-end measurementIPv6

Advances and perspectives in environmental health research in china

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Frontiers of Environmental Science & Engineering 2024年第6期18卷 105-113页

作者： Tong Zhu Yingjun Liu Shunqing Xu Guanghui Dong Cunrui Huang Nan Sang Yunhui Zhang Guanyong Su Jingwen Chen Jicheng Gong Guohua Qin Xinghua Qiu Jing Shang haobo wang Pengpeng wang Mei Zheng SKL-ESPC&SEPKL-AERM Department of Environmental HealthCollege of Environmental Sciences and EngineeringPeking UniversityBeijing 100871China Center for Environment and Health Peking UniversityBeijing 100871China School of Life and Health Sciences Huainan UniversityHaikou 570228China Joint International Research Laboratory of Environment and Health(Ministry of Education) Guangdong Provincial Engineering Technology Research Center of Environmental Pollution and Health Risk AssessmentDepartment of Occupational and Environmental HealthSchool of Public HealthSun Yat-sen UniversityGuangzhou 510080China Vanke School of Public Health Tsinghua UniversityBeijing 100084China Research Center of Environment and Health College of Environment and ResourceShanxi UniversityTaiyuan 030006China department of Environmental Health School of Public HealthFudan UniversityShanghai 200032China School of Environmental and Biological Engineering Nanjing University of Science and TechnologyNanjing 210094China Key Laboratory of Industrial Ecology and Environmental Engineering(Ministry of Education) Dalian Key Laboratory on Chemicals Risk Control and Pollution Prevention TechnologySchool of Environmental Science and TechnologyDalian University of TechnologyDalian 116024China department of Occupational and Environmental Health College of Public HealthZhengzhou UniversityZhengzhou 450001China

Environmental health research aims to identify environmental conditions suitable for the healthy living and reproduction of human *** the interdisciplinary research bridging environmental sciences and health/medical sciences,the impacts of physical,chemical,and biological environmental factors on human health are *** includes identifying environmental factors detrimental to human health,evaluating human exposure characteristics to environmental factors,clarifying causal relationships between environmental exposure and health effects,analyzing the underlying biochemical mechanisms,linking environmental factors to the onset and progression of diseases,establishing exposure-response relationships,and determining effect ***,the results of environmental health research can serve as a scientific basis for formulating environmental management strategies and guiding prevention and intervention measures at both the public and individual *** paper summarizes the recent advances and future perspectives of environmental health research in china,as reported by a group of Chinese scientists who recently attended a workshop in Hainan,*** it is not intended to provide a comprehensive review of this expansive field,it offers a glimpse into the significant progress made in understanding the health impacts of environmental factors over the past *** ahead,it is imperative not only to sustain efforts in studying the health effects of traditional environmental pollution,but also to prioritize research on the health impacts of emerging pollutants and climate change.

关键词： Environmental pollution Emerging pollutants Climate change Exposure Mechanism

Ultra-Broad-Band LiNbO3 Electro-Optic Modulators with Novel Complex Electrode

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Chinese Journal of Lasers 2000年第2期9卷 128-133页

作者： ZHOU Weiqin WU Boyu PENG Jihu GU Jinghua HU Jinyang (department of electronic Engineering, tsinghua university, {4. 100084. china) 清华大学北京 100084

The characteristics of Z- cut LiNbO3optical modulators with novel complex electrode are discussed by using the finite element method （FEM） and studied experimentally in this paper. The travelling wave electrode consists of upper and lower parts. It can easily realize phase velocity matching between microwave and optical wave and drastically reduce microwave electrode loss. An electrooptic modulator with larger than 100 GHz bandwidth and half wave voltage 6 V is designed, fabricated and measured. Vπis 5. 1 V and the attenuation coefficient ac is 0. 3 dB/(cm· GHz1/2). The experimental results show that the modulator has great potentiality for expanding bandwidth.

关键词： electro-optic medulator LiNbO3 modulator travelling wave electrode complex electrode

High-speed reconstruction for ultra-low resolution faces

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Science china(Information Sciences) 2012年第9期55卷 2102-2108页

作者： wang Li ,CHEN JianSheng,HE JinPing & SU GuangDa department of electronic Engineering,tsinghua {4.,beijing 100084.china 1. department of electronic Engineering Tsinghua University Beijing 100084 China

In this paper,a learning-based high-speed reconstruction system for ultra-low resolution faces is implemented using a software/hardware co-design *** hardware component working at 60 MHz contains a field programmable gate array,which is reconfigured to contain parallel processing units,and multiple memories to create parallel *** hardware component effectively handles generating and sorting computationally intensive similarity *** solves the processing speed problem in learning-based super-resolution reconstruction for ultra-low resolution *** system can reconstruct faces using 8 × 6,16 × 12,and 32 × 24.sized images,with 4.× 4.8 × 8,or 16 × 16 times *** experimental results verify the effectiveness of our system in terms of both visual effect and low root mean square *** processing speed can be improved up to a maximum of 7900 times faster than a pure software implementation using C.

关键词： neighborhood image parallel computer template matching pixel compensation pipeline

Key parameter estimation for radar rotating object imaging with multi-aspect observations

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Science china(Information Sciences) 2010年第8期53卷 1641-1652页

作者： YE ChunMao, XU Jia , PENG YingNing & wang XiuTan department of electronic Engineering, tsinghua {4., beijing 100084. china 1. department of electronic Engineering Tsinghua University Beijing 100084 China

Rotating object model is commonly used for imaging analysis in high resolution radars such as the inverse synthetic aperture radar (ISAR). For a rotating object, it is known that multi-aspect observations can improve cross-range resolution with the known imaging geometry. For the non-cooperative rotating object with unknown imaging geometry, this paper proposes an integrated scheme to estimate the key parameters, e.g., the rotating velocity and the aspect angle difference between every two observations. Furthermore, convolution back-projection (CBP) method is applied to provide fused imaging result with improved resolution. Also, the accuracy of the ultimate parameter estimation is analyzed, which is strongly related with several important factors like position extraction error of scattering centers and so on. Finally, the results of numerical experiments are provided to demonstrate the effectiveness of the proposed method.

关键词： rotating objects multi-aspect observations fused imaging aspect angle difference

Mapping and overlapping based carrier frequency searching technique for rapid GNSS long PN-code acquisition

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Science china(Information Sciences) 2010年第12期53卷 2642-2652页

作者： LI Hong ,LU MingQuan & FENG ZhenMing department of electronic Engineering,tsinghua university,{4. 100084.china 1. department of electronic Engineering Tsinghua University Beijing 100084 China

In global navigation satellite systems(GNSS),because of the long period and high chip rate of long pseudo-noise(PN) code,the rapid acquisition is hard to *** speed up search process,in the paper,a mapping and overlapping based carrier frequency searching technique is *** mapping incoming signals of the same interval to different carrier frequency cells and overlapping together the mapped incoming signals that correspond to the same code phase,the technique reduces the number of the cells to be *** effect of the technique on detection and mean acquisition time performance is *** is shown that the technique reduces the cells to be searched and shortens mean acquisition time at the expense of degrading detection *** technique is fit to the previously published acquisition methods and is capable of improving their mean acquisition time *** and simulation results validate the analysis.

关键词： carrier frequency cells mapping overlapping acquisition performance

Weak key analysis for chaotic cipher based on randomness properties

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Science china(Information Sciences) 2012年第5期55卷 1162-1171页

作者： YIN RuMing,wang Jian,YUAN Jian,SHAN XiuMing & wang XiQin department of electronic Engineering,{4. university,beijing 100084.china 1. department of electronic Engineering Tsinghua University Beijing 100084 China

Weak key analysis is a key issue in the design of chaotic *** most of the existing research focusing on the degradation of the chaotic sequences which causes weak keys,we point out that the parameters for which the chaotic sequences do not degrade are still possible to be weak *** this paper,we propose a new approach based on the rigorous statistical test to improve the weak key *** weak keys of a specific chaotic cipher are investigated by using our method and a large number of new weak keys are *** results verify that our method is more *** the other hand,although statistical tests are now widely adopted to test the chaos-based bit sequences,there are few reports of analysis results on the weak keys or weak sequences of chaotic *** our work may be helpful for current research on statistical tests of chaotic cipher.

关键词： chaos cryptography statistical test weak keys sequence randomness

Numerically stable method of signal subspace estimation based on multistage Wiener filter

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Science china(Information Sciences) 2010年第12期53卷 2620-2630页

作者： ZHUANG XueBin ,CUI XiaoWei,LU MingQuan & FENG ZhenMing department of electronic Engineering,tsinghua university,{4. 100084.china 1. department of electronic Engineering Tsinghua University Beijing 100084 China

In this paper,a numerically stable method of signal subspace estimation based on Householder multistage Wiener filter(HMSWF) is *** stability of the method lies on the fact that the Householder matrix in HMSWF ensures the unitary blocking operation and significantly strengthens the orthogonality of basis vectors,especially in the finite-precision *** the following,we analyze the numerical stability of HMSWF and MSWF based on the correlation subtractive structure(CSS-MSWF) by establishing the equivalence between the forward recursion of MSWF and the Arnoldi algorithm in numerical linear ***,the equivalence between HMSWF and the Householder QR decomposition(QRD) on the Krylov matrix underlying in MSWF is directly *** on the relationship,two theoretical upper bounds of the orthogonality error of basis vectors in signal subspace are obtained and it is demonstrated that the orthogonality of basis vectors based on HMSWF is perfectly preserved by the numerically well-behaved Householder matrix,and the corresponding signal subspace estimation is much more numerically stable than that based on *** show the numerical stability of the proposed method of signal subspace estimation by HMSWF.

关键词： multistage Wiener filter subspace estimation Householder transform numerical stability Arnoldi algorithm

Parameter estimation for SAR moving target in complex image domain

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Science china(Information Sciences) 2010年第4期53卷 854-866页

作者： ZUO Yu, XU Jia*, PENG YingNing & XIA XiangGen department of electronic Engineering, tsinghua university, {4. 100084. china 1. department of electronic Engineering Tsinghua University Beijing 100084 China

Based on the proposed parametric model of SAR ground moving target in the complex image domain, this paper derives the Cramer-Rao bounds (CRB) for the unknown model parameters estimation and obtains the inherent limitations for the moving target motion estimation in the SAR complex image domain. Firstly, the relationships are analyzed among the estimation performance and the target’s scattering intensity, Doppler parameters, motion parameters, as well as the power spectra of the target and the clutter. Furthermore, the parameter estimation performance is compared in the signal domain and the complex image domain (CID) to draw some useful conclusions. Besides, the reduction resolution processing is proposed to improve the parameter estimation, and its performance improvement is also presented with analytic expressions. For the homogeneous background, it is shown that the accurate parameter estimation and azimuth location may be realized for SAR ground moving target in the complex image domain. Finally, some numerical experiments are provided to demonstrate the effectiveness of the proposed methods.

关键词： synthetic aperture radar (SAR) moving target complex image domain parameter estimation Cramer-Rao bound (CRB) reduce resolution processing (RRP)