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Optimal MAC based cooperative spectrum sensing in cognitive radio networks

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Science China(information Sciences) 2012年第6期55卷 1388-1396页

作者： CHEN Zhong 1,ZHANG XianDa 1 & YANG LanJuan 2.1 State key laboratory of Intelligent Technology and Systems,{2. National laboratory for information Science and Technology,department of Automation,{2. university,beijing 100084,China 2.Institute of Command Automation,PLA university of Science and Technology,Nanjing 2.0007,China 1. State key laboratory of Intelligent Technology and Systems Tsinghua National Laboratory for Information Science and Technology Department of Automation Tsinghua University Beijing 100084 China2. Institute of Command Automation PLA University of Science and Technology Nanjing 210007 China

This paper considers a cognitive radio (CR) system in non-ideal fading wireless channels and pro-poses cooperative spectrum sensing schemes based on coherent multiple access channels (MAC),serving as an alternative way to improve the cooperative spectrum sensing performance and provide space diversity for spec-trum *** statistics are transmitted using a common channel from the secondary users (SUs) to a fusion center (FC) where the global decision is *** optimal scaling factors of the proposed schemes are obtained by maximizing the detection probability under a target false alarm probability and a transmit power *** the proposed optimal MAC scheme has high computational complexity,a sub-optimal solu-tion based on maximization of the deflection coefficient (DC) is also *** results show that the proposed algorithms can significantly improve the spectrum sensing performance and approach the detection baseline.

关键词： cognitive radio (CR) spectrum sensing multiple access channel (MAC) deflection coefficient optimization

A novel method for evaluating and improving the 1H-MRSI glioma data quality

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Progress in Natural Science:Materials International 2005年第8期15卷 765-768页

作者： YUAN Kehong 1,2. LU Hongyu2. BAO Shanglian2., CHEN Qiansheng1, LI Shaowu3 and DUAN Chaijie2.1. key laboratory of Pure and Applied Mathematics, School of Mathematical Sciences, {2. 100871, China 2. The Research Center for Tumor Diagnosis and Therapeutical {2. & the {2. key laboratory of Medical {2. and Engineering, Peking university, {2. 100871, China 3. The Tian Tan Hospital, {2. 100050, China) key laboratory of Pure and Applied Mathematics School of Mathematical Sciences Beijing 100871 China. The Research Center for Tumor Diagnosis and Therapeutical physics & the beijing {2. {2. of Medical physics and Engineering Peking University Beijing 100871 China. The Tian Tan Hospital Beijing 100050 China

Metabolic information obtained by proton magnetic resonance spectroscopic imaging (1H-MRSI) has been approved to be a powerful tool to identify either benign or malignant glioma, as well as to confirm the tumor level. However, 1H-MRSI data are affected by various factors, such as the thermal noise, eddy currents, susceptibility artifacts, and rigid body motion. To get accurate quantitative metabolic information, the {2. problem is to assess the 1H-MRSI data quality. In this paper, we introduce a new evaluating system to filter the data, and a new method, called wavelet denoising method, to improve the data quality under the evaluating system. Experimental results on 1H-MRSI glioma data demonstrate that preprocessing is prerequisite and the proposed algorithm with evaluating system is effective.

关键词： 1H-MRSI evaluating system glioma data quality wavelet denoising

Polynomial analysis of canopy spectra and biochemical component content inversion

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Science China Earth Sciences 2005年第10期48卷 1780-1791页

作者： YAN Chunyan1, LIU Qiang1, NIU Zheng1, WANG Jihua2. HUANG Wenjiang2.& LIU Liangyun 2.1. State key laboratory of Remote Sensing Science, Jointly Sponsored by the Institute of Remote Sensing Applications of Chinese Academy of Sciences and {2. Normal {2., {2. 100101, China 2. National Engineering Research Center for information Technology in Agriculture, {2. 100089, China State key laboratory of Remote Sensing Science Jointly Sponsored by the Institute of Remote Sensing Applications of Chinese Academy of Sciences and {2. Normal {2. {2. China National Engineering Research Center for information Technology in Agriculture beijing China

A polynomial expression model was developed in this paper to describe directional canopy spectra, and the decomposition of the polynomial expression was used as a tool for re-trieving biochemical component content from canopy multi-angle spectra. First, the basic formula of the polynomial expression was introduced and the physical meaning of its terms and coeffi-cients was discussed. Based on this analysis, a complete polynomial expression model and its decomposition method were given. By decomposing the canopy spectra simulated with SAILH model, it shows that the polynomial expression can not only fit well the canopy spectra, but also show the contribution of every order scattering to the whole reflectance. Taking the first scattering coefficients a10 and a01 for example, the test results show that the polynomial coefficients reflect very well the hot spot phenomenon and the effects of viewing angles, LAI and leaf inclination angle on canopy spectra. By coupling the polynomial expression with leaf model PROSPECT, a canopy biochemical component content inversion model was given. In the simulated test, the canopy multi-angle spectra were simulated by two different models, SAILH and 4-SCALE re-spectively, then the biochemical component content was retrieved by inverting the coupled polynomial expression + PROSPECT model. Results of the simulated test are promising, and when applying the algorithm to measured corn canopy multi-angle spectra, we also get relatively accurate chlorophyll content. It shows that the polynomial analysis provides a new method to get biochemical component content independent of any specific canopy model.

关键词： polynomial expression, canopy spectra, decomposition, biochemical component content, inversion.

Sequence-based localization algorithm with improved correlation metric and dynamic centroid

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Science China(information Sciences) 2011年第11期54卷 2349-2358页

作者： YU Ying 1,JIANG ChunXiao 2.ZHAO XiaoJie 2.YUN LiJun 1,LI ZhiHua 2.& REN Yong 2. College of information,Yunnan Normal university,Kunming 650500,China 2.{2. of Electronic Engineering,tsinghua university,beijing 100084,China 1. College of information Yunnan Normal University Kunming 650500 China2. Department of Electronic Engineering Tsinghua University Beijing 100084 China

Ecolocation (error controlling localization technique) is a novel sequence-based RF localization algorithm.A key feature of the Ecolocation algorithm is that it constructs a constraint table based on RSSI values and compares data between two ***,the definitions of the constraint and the centroid in the Ecolocation algorithm are imperfect,and result in poor localization *** improve the localization accuracy,a new algorithm based on weighted rank order correlation coefficient and dynamic centroid method is *** results indicate that compared with the Ecolocation,the localization accuracy and robustness of the new algorithm are distinctly raised.

关键词： WSNs (wireless sensor networks) localization sequences constraint table rank order correlation coefficient

A three-dimensional variational ocean data assimilation system:Scheme and preliminary results

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Science China Earth Sciences 2006年第11期49卷 1212-1222页

作者： ZHU Jiang1,2. ZHOU Guangqing1, YAN Changxiang1, FU Weiwei1 & YOU Xiaobao1,3 1. International Center for Climate and Environment Sciences, Institute of Atmospheric physics, Chinese Academy of Sciences, beijing 10002., China 2. Jiangsu {2. {2. of Meteorological Disaster, Nanjing university of information Science and Technology, Nanjing 2.0044, China 3. beijing Institute of Applied Meteorology, beijing 10002., China 1. International Center for Climate and Environment Sciences Institute of Atmospheric Physics Chinese Academy of Sciences Beijing 100029 China 2. Jiangsu key laboratory of Meteorological Disaster Nanjing University of Information Science and Technology Nanjing 210044 China 3. beijing Institute of Applied Meteorology Beijing 100029 China

A new 3DVAR-based Ocean Variational Analysis System (OVALS) is developed. OVALS is capable of assimilating in situ sea water temperature and salinity observations and satellite altimetry data. As a component of OVALS, a new variational scheme is proposed to assimilate the sea surface height data. This scheme considers both the vertical correlation of background errors and the nonlinear temperature-salinity relationship which is derived from the generalization of the linear balance constraints to the nonlinear in the 3DVAR. By this scheme, the model temperature and salinity fields are directly adjusted from the altimetry data. Additionally, OVALS can assimilate the temperature and salinity profiles from the ARGO floats which have been implemented in recent years and some temperature and salinity data such as from expendable bathythermograph, moored ocean buoys, etc. A 2.-year assimilation experiment is carried out by using OVALS and the Tropical Pacific circulation model. The results show that the assimilation system may effectively improve the estimations of temperature and salinity by assimilating all kinds of observations. Moreover, the root mean square errors of temperature and salinity in the upper depth less than 42. m reach 0.63℃ and 0.34 psu.

关键词： data assimilation, 3DVAR, sea surface height, ARGO floats.

Simulation study of phase retrieval for hard X-ray in-line phase contrast imaging

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Science China(physics,Mechanics & Astronomy) 2005年第4期48卷 450-458页

作者： YU Bin1,2. PENG Xiang1,2. TIAN Jindong1, NIU Hanben1, DIAO Luhong3 & LI Hua3 1. key laboratory of Optoelectronic Devices and Systems of Ministry of Education, Institute of Optoelec- tronics, Shenzhen {2., Shenzhen 518060, China 2. State key laboratory of Precision Measuring Technology and Instruments, Tianjin {2., Tianjin 300072.China 3. key laboratory of Intelligent information Processing, Institute of Computing Technology, Chinese Academy of Sciences, beijing 100080,China 1. key laboratory of Optoelectronic Devices and Systems of Ministry of Education Institute of Optoelectronics Shenzhen University 518060 Shenzhen China 2. State key laboratory of Precision Measuring Technology and Instruments Tianjin University 300072 Tianjin China 3. key laboratory of Intelligent {2. Processing Institute of Computing Technology Chinese Academy of Sciences 100080 Beijing China

Two algorithms for the phase retrieval of hard X-ray in-line phase contrast imaging are presented. One is referred to as Iterative Angular Spectrum Algorithm (IASA) and the other is a hybrid algorithm that combines IASA with TIE (transport of intensity equation). The calculations of the algorithms are based on free space propagation of the angular spectrum. The new approaches are demonstrated with numerical simulations. Comparisons with other phase retrieval algorithms are also performed. It is shown that the phase retrieval method combining the IASA and TIE is a promising technique for the application of hard X-ray phase contrast imaging.

关键词： X-ray optics, phase contrast imaging, phase retrieval, angular spectrum, hard X-ray.

The structural analysis of fuzzy measures

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Science China(information Sciences) 2011年第1期54卷 38-50页

作者： ZHANG Ling1,ZHANG Bo2.& ZHANG YanPing1 1 Computer Science College,Anhui university,Hefei 2.0039,China 2.tate key Lab of Intelligent Technology & Systems {2. National Lab for {2. Science & Technology {2. Science & Technology College,Computer Science & Technology,{2. university,beijing 100084,China 1. Computer Science College Anhui University Hefei 230039 China2. State Key Lab of Intelligent Technology & Systems tsinghua National Lab for information Science & Technology information Science & Technology College Computer Science & Technology Tsinghua University Beijing 100084 China

From quotient space based granular computing theory we explore the fuzzy measures of fuzzy sets. Based on the structural analysis of fuzzy sets,we present an"isotropism"*** this assumption we achieved the following insights:(1)the uniqueness of a fuzzy measure being isotropic on a finite complete semi-ordered set;(2.the necessary and suffcient condition of the isomorphism for fuzzy measure functions in fuzzy mathematics;(3)the necessary and suffcient condition that fuzzy measures have fuzzy and granular monotonicity;(4)under a certain assumption,the analytic expression for fuzzy *** results clarify the relationship between fuzzy measures and granular computing,reveal the essence of fuzzy measures,and provide a simple way of constructing fuzzy measures.

关键词： quotient space fuzzy set fuzzy measure rough set structural analysis

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,{2. {2.,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 12.2.08 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 {2. 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

Magnetic mineralogy of the Hongqiling Cu-Ni sulphide deposit: Implications for ore genesis

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Progress in Natural Science:Materials International 2007年第10期17卷 1192-1198页

作者： Xi Aihua1,2. Ge Yuhui1, Cai Yuanfeng2.and Zhang Xuefeng3(1. Faculty of Resources & Environment, Southwest Petroleum university, Chengdu 610500, China 2. State key {2. for Endogenic Metal Deposit Research, Nanjing university, Nanjing 2.0093, China 3. department of Natural Resources & Technology information, China university of Petroleum, beijing 102.49, China) Faculty of Resources & Environment Southwest Petroleum University Chengdu 610500 China State key laboratory for Endogenic Metal Deposit Research Nanjing University Nanjing 210093 China department of Natural Resources & Technology information China University of Petroleum Beijing 102249 China

Pyrrhotite is one of the common ore minerals in Cu-Ni sulphide deposits, but only monoclinic pyrrhotite is ferromagnetic at room temperature. X-ray and EPA analyses reveal that most pyrrhotite forming sideronitic texture in the Hongqiling Cu-Ni sulphide deposit is monoclinic, but that in the massive ore is a mixture of monoclinic and hexagonal pyrrhotites. Differential thermal and magnetic- thermogravimetric analyses of massive ore indicate a magnetic transition and heat absorption at 32.℃, suggesting that this temperature is the thermomagnetic and phase transition point of pyrrhotite. For massive pyrrhotite ores heated at 400oC for 30 h and then quenched by cool water, the monoclinic pyrrhotite (mpo) transforms completely into the hexagonal pyrrhotite (hpo). However, all the pyrrhotites resulting from slow cooling of the sample in air are mpo. These results indicate that transformation between hpo and mpo depends upon the cooling rate. Therefore, massive ores in this deposit might have been formed via rapid cooling of ore melts. On the other hand, it is significant to study the effect of the ratio of the magnetite in total ores on the genesis of magmatic Cu-Ni suphide deposits.

关键词： pyrrhotite magnetite genesis of Cu-Ni sulphide deposit Hongqiling.