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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,tsinghua National Laboratory for information Science and technology,Department of Automation,tsinghua university,beijing 100084,china 2 institute of Command Automation,PLA university of Science and technology,Nanjing 210007,china State Key Laboratory of Intelligent technology and Systems Tsinghua National Laboratory for Information Science and Technology Department of Automation Tsinghua University Beijing China institute of Command Automation PLA University of Science and Technology Nanjing 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

PROCESS CAPABILITY ANALYSIS AND ESTIMATION SCHEME FOR AUTOCORRELATED DATA

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Journal of Systems Science and Systems Engineering 2010年第1期19卷 105-127页

作者： Jing SUN Shengxian WANG Zhihui FU research Center for Contemporary Management,Key research institute of Humanities and Social Sciences at Universities,School of Economics and Management,tsinghua university,beijing 100084,P.R.china research Center for Contemporary Management Key Research Institute of Humanities and Social Sciences at Universities School of Economics and Management Tsinghua University Beijing P.R. China

Autocorrelation is prevalent in continuous production processes, such as the processes in the chemical and pharmaceutical industries. With the development of measurement technology and data acquisition technology, sampling frequency is getting higher and the existence of autocorrelation cannot be ignored. This paper analyzes five estimation schemes of process capability for autocorrelated data. Comparisons among these schemes are discussed for small sample and large sample. In conclusion, this paper gives a procedure of process capability analysis for autocorrelated data.

关键词： Autocorrelation estimation process capability analysis statistical process control

Adaptive neural control based on HGO for hypersonic flight vehicles

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Science china(information Sciences) 2011年第3期54卷 511-520页

作者： XU Bin 1,2 , GAO DaoXiang 3 & WANG ShiXing 1 1 Department of Computer Science and technology, tsinghua university, beijing 100084, china 2 Autonomous System Lab, ETH Zurich Zurich 8092, Switzerland 3 School of technology, beijing Forestry university, beijing 100083, china Department of Computer Science and technology Tsinghua University Beijing China Autonomous System Lab ETH Zurich Zurich Switzerland School of technology Beijing Forestry University Beijing China

This paper describes the design of adaptive neural controller for the longitudinal dynamics of a generic hypersonic flight vehicle (HFV) which are decomposed into two functional systems, namely the altitude subsystem and the velocity subsystem. For each subsystem, one adaptive neural controller is investigated based on the normal output-feedback formulation. For the altitude subsystem, the high gain observer (HGO) is taken to estimate the unknown newly defined states. Only one neural network (NN) is employed to approximate the lumped uncertain system nonlinearity during the controller design which is considerably simpler than the ones based on back-stepping scheme with the strict-feedback form. The Lyapunov stability of the NN weights and filtered tracking error are guaranteed in the semiglobal sense. Numerical simulation study of step response demonstrates the effectiveness of the proposed strategy in spite of system uncertainty.

关键词： adaptive neural control hypersonic flight vehicle high gain observer output-feedback

Power system low frequency oscillation monitoring and analysis based on multi-signal online identification

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Science china(Technological Sciences) 2010年第11期53卷 2589-2596页

作者： YUAN Ye1,2,SUN YuanZhang2,CHENG Lin2,CHEN Gang2 & WANG Peng3 1 State Nuclear Electric Power Planning Design and research institute,beijing 100032,china 2 State Key Laboratory of Power Systems,Deptment of Electrical Engineering,tsinghua university,beijing 100084,china 3 EEE School,Nanyang Technological university,Singapore State Nuclear Electric Power Planning Design and research institute State Key Laboratory of Power Systems Deptment of Electrical Engineering Tsinghua University

The advance in the wide-area measurement system (WAMS) is driving the power system to the trend of wide-area monitoring and *** Prony method is usually used for low frequency oscillation online ***,the identified amplitude and phase information is not sufficiently *** this paper,the amplitude is adopted to detect the occurrence of the oscillation and to obtain the mode observability of the *** phase is adopted to identify the oscillation generator grouping and to obtain the mode *** time varying characteristics of low frequency oscillations are *** behaviors and the characters of low frequency oscillations are displayed by dynamic visual *** on the "11.9" low frequency oscillation of the Guizhou Power Grid substantiate the feasibility and the validation of the proposed methods.

关键词： wide area measurement system (WAMS) low frequency oscillation Prony algorithm mode observability

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Entropy number and non-linear approximations on multivariate Besov space by manifolds of finite pseudo-dimension

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Progress in Natural Science:Materials International 2006年第3期16卷 260-265页

作者： LONG Jingfan and FANG Gensun (School of Mathematical Sciences, beijing Normal university, beijing 100875, china Department of Computer Science, information technology institute, beijing 100101, china) School of Mathematical Sciences Beijing Normal University Beijing 100875 China Department of Computer Science Information Technology Institute Beijing 100101 China

We determine the asymptotic order of entropy number and optimal non -linear approximations of anisotropic periodic Besov class of Bpθr(Td') (1≤p≤∞,1≤0≤∞) by manifolds of finite pseudo-dimension in the metric Lq... 详细信息

关键词： Pseudo-dimension anisotropic Besov class of functions entropy number nonlinear width.

Scan chain design for shift power reduction in scan-based testing

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Science china(information Sciences) 2011年第4期54卷 767-777页

作者： LI Jia 1,HU Yu 2 & LI XiaoWei 2 1 The School of Software,tsinghua university,beijing 100084,china 2 The institute of Computing technology,Chinese Academy of Sciences,beijing 100190,china The School of Software Tsinghua University Beijing China The institute of Computing technology Chinese Academy of Sciences Beijing China

Test power of VLSI systems has become a challenging issue *** scan shift power dominates the average test power and restricts clock frequency of the shift phase,leading to excessive thermal accumulation and long test *** paper proposes a scan chain design technique to solve the above *** on weighted transition metric (WTM),the proposed extended WTM (EWTM) that is utilized to guide the scan chain design algorithm can estimate the scan shift power in both the shift-in and shift-out ***,the wire length overhead of the proposed scan chain design can also be reduced by the proposed distance of EWTM (DEWTM) *** results confirm that the proposed approach can significantly reduce scan shift power with low wire length overhead.

关键词： low power DfT scan-based testing test power reduction scan chain design

Gas kinetic algorithm for flows in Poiseuille-like microchannels using Boltzmann model equation

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Science china(Physics,Mechanics & Astronomy) 2005年第4期48卷 496-512页

作者： LI Zhihui1,2, ZHANG Hanxin1 & FU Song2 ⒈ National Laboratory for CFD, Hypervelocity Aerodynamics institute,china Aerodynamics research and Development Center,Mianyang 621000,china 2.Department of Engineering Mechanics,tsinghua university,beijing 100084,china National Laboratory for CFD Hypervelocity Aerodynamics Institute China Aerodynamics Research and Development Center Mianyang China Department of Engineering Mechanics Tsinghua University Beijing China

The gas-kinetic unified algorithm using Boltzmann model equation have been extended and developed to solve the micro-scale gas flows in Poiseuille-like micro-channels from Micro-Electro-Mechanical Systems (MEMS). The numerical modeling of the gas kinetic boundary conditions suitable for micro-scale gas flows is presented. To test the present method, the classical Couette flows with various Knudsen numbers, the gas flows from short microchannels like plane Poiseuille and the pressure-driven gas flows in two-dimensional short microchannels have been simulated and compared with the approximate solutions of the Boltzmann equation, the related DSMC results, the modified N-S solutions with slip-flow boundary theory, the gas-kinetic BGK-Burnett solutions and the experimental data. The comparisons show that the present gas-kinetic numerical algorithm using the mesoscopic Boltzmann simplified velocity distribution function equation can effectively simulate and reveal the gas flows in microchannels. The numerical experience indicates that this method may be a powerful tool in the numerical simulation of micro-scale gas flows from MEMS.

关键词： Boltzmann model equation, discrete velocity ordinate method, finite-difference scheme, Couette flow, Poiseuille flow, gas flow in short-microchannel.

Silicon-based microelectrode arrays for stimulation and signal recording of in vitro cultured neurons

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Science china(information Sciences) 2011年第10期54卷 2199-2208页

作者： PAN HaiXian 1,L XiaoYing 1 ,WANG ZhiGong 2,REN TianLing 3,FANG Tao 1,ZHANG Jie 1,ZHOU ChangJian 3 & WANG LiGang 3 1 State Key Laboratory of Bioelectronics,Southeast university,Nanjing 210096,china 2 institute of RF-& OE-ICs,Southeast university,Nanjing 210096,china 3 institute of Microelectronics,tsinghua university,beijing 100084,china State Key Laboratory of Bioelectronics Southeast University Nanjing China institute of RF-& OE-ICs Southeast University Nanjing China institute of Microelectronics Tsinghua University Beijing China

Microelectrode arrays (MEAs) for stimulation and signal recording of in vitro cultured neurons are *** MEA is composed of 60 independent electrodes with 59 working ones and one reference *** electrodes are divided into 30 *** each pair of electrodes,four independent states can be realized to define the accessing modes of neurons cultured on the surface of the electrodes.A total MEA covers an area of 10 mm×10 *** are fabricated in a silicon-based semiconductor *** implemented MEA is bonded on a specially designed printed-circuit-board (PCB) and surrounded by a culture *** impedance measurement has been made to verify the electrical characteristics of *** surface was modified to enhance the biocompatibility.A series of PC12 cells culture experiments validates the effectiveness of the *** extracellular signal recording experiment with acetylcholine (Ach) as a stimulant has been carried out,and the results show the feasibility of MEAs for extracellular action potential *** electrical stimulation and recording experiments have been carried out *** indicate that MEAs can be used for extracellular stimulation,recording,simultaneous stimulation and recording,and isolation of PC12 cells network cultured in vitro.

关键词： microelectrode arrays (MEAs) extracellular recording stimulation and recording neurons net-work in vitro

Measuring-basis-encrypted six-state quantum key distribution scheme

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Progress in Natural Science:Materials International 2006年第1期16卷 84-89页

作者： CHEN Pan1, DENG Fuguo1, WANG Pingxiao1 and LONG Guilu1,2 (Key Laboratory for Quantum information and Measurements and Department of Physics, tsinghua university, beijing 100084, china 2. Key Laboratory for Atomic and Molecular NanoSciences, tsinghua university, beijing 100084, china) Key Laboratory for Quantum information and Measurements and Department of Physics Tsinghua University Beijing 100084 China

A six-state quantum key distribution scheme with measuring-basis encryption technique, which is based on the six-state protocol and the MBE protocol, is proposed. In this modified six-state quantum key distribution protocol, Alice and Bob use a control key to synchronize the use of their measuring-basis so that they always use the same measuring-basis. This modified six-state quantum key distribution protocol retains the advantage of higher security and at the same time has a higher efficiency.

关键词： quantum key distribution measuring-basis encrypted six-state security.