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An N/4 fixed-point duality quantum search algorithm

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中国科学：物理学、力学、天文学英文版 2010年第9期53卷 1765-1768页

作者： HAO Liang1,LIU Dan2 & LONG GuiLu1,3 1Key Laboratory for Atomic and Molecular NanoSciences and Department of Physics,Tsinghua university,Beijing 100084,china 2School of Sciences,dalian Nationalities university,dalian 116600,china 3Tsinghua National Laboratory for information Science and technology,Beijing 100084,china Key Laboratory for Atomic and Molecular NanoSciences and Department of Physics Tsinghua University Beijing China School of Sciences Dalian Nationalities University Dalian China Tsinghua National Laboratory for information Science and technology Beijing China

Here a fixed-point duality quantum search algorithm is *** algorithm uses iteratively non-unitary operations and measurements to search an unsorted *** the marked item is found,the algorithm stops *** algorithm uses a constant non-unitary operator,and requires N/4 steps on average(N is the number of data from the database) to locate the marked *** implementation of this algorithm in a usual quantum computer is also demonstrated.

关键词： fixed-point search algorithm duality quantum computing the N4 duality search algorithm

Path Tracking and Trajectory Planning for Nonholonomic Wheeled Mobile Robots

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Path Tracking and Trajectory Planning for Nonholonomic Wheel...

Design,analysis and control of hybrid excited doubly salient stator-permanent-magnet motor

第二十七届中国控制会议

作者： Xie Kewei,Zhuang Yan,Wang Wei research center of information and control,dalian university of technology,dalian 116024,P.R.china

In order to track multiform curves planned for nonholonomic wheeled mobile robots stably,this paper presents an effective trajectory planning scheme and an improved tracking controller using a biological incentive *** trajectory planning scheme,which includes a curvature estimator based on two adjacent points,combines the results of path planning with the policies of tracking..The kinetic restrictions method based on biological incentive model is introduced in backstepping technique to improve the control *** resolves the velocity jump problem existing in some previous tracking controllers and deals with the situations with large tracking *** results demonstrate the effectiveness of tracking capability of the proposed scheme

关键词： Kinetic restriction Trajectory planning Path tracking Nonholonomic wheeled mobile robot

来源： cnki会议评论

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Science china(Technological Sciences) 2010年第1期53卷 188-199页

作者： ZHU XiaoYong1,2 & CHENG Ming1 1 Engineering research center for Motion control of MOE,School of Electrical Engineering,Southeast university,Nanjing 210096,china 2 School of Electrical and information Engineering,Jiangsu university,Zhenjiang 212013,china Engineering research center for Motion control of MOE School of Electrical Engineering Southeast University Nanjing China School of Electrical and information Engineering Jiangsu University Zhenjiang China

In this paper,a new hybrid excited doubly salient stator-permanent-magnet motor is proposed,where both permanent magnets and DC field windings are located in the *** theory,the mathematical model and design method of the motor are *** corresponding output power equation and the relationship between the flux control capability and the extended speed range are deduced in *** using an efficient "one-step" three-dimensional(3D) finite element method,the electromagnetic performances are analyzed,in which the leakage flux outside the stator circumference and end-effect are taken into *** on the operation principle of the motor,the control strategy and scheme are developed and implemented *** experimental results and finite element analysis show that the proposed motor not only maintains the advantages of doubly salient permanent magnet motors,but also offers high energy efficiency over a wide speed range,which makes the motor an interesting candidate for electric vehicles.

关键词： stator permanent magnet motor hybrid excitation doubly salient finite element method flux weakening control

A Nonparametric Adaptive CUSUM Method and Its Application in Source-End Defense against SYN Flooding Attacks

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Wuhan university Journal of Natural Sciences 2011年第5期16卷 414-418页

作者： YU Ming School of information and Communication Engineering Dalian University of Technology Dalian 116024 Liaoning China

Combating DDoS attacks at their sources is still in its infancy. In tttis paper, a noaparametric adaptive CUSUM （cumulative sum） method is presented, which is proven efficient in detecting SYN flooding attacks close to their sources. Different from other CUSUM methods, this new method has two distinct features：（1） its detection threshold can adapt itself to various traffic conditions and （2） it can timely detect the end of an attack within a required delay. Trace-driven simulations are conducted to validate the efficacy of this method in detecting SYN flooding attacks, and the results show that the nonparametric adaptive CUSUM method excels in detecting low-rate attacks.

关键词： adaptive detection nonparametric algorithm CUSUM (cumulative sum) SYN flooding DDoS

Uniqueness and stability in an inverse problem for a Poisson's equation

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Science china Mathematics 2007年第7期50卷 967-976页

作者： Li-xin FENG~(1+) Yan-cheng QU~2 1 School of Mathematical Sciences,Heilongjiang university,Harbin 150080,china 2 research center of control and Inertial technology,Harbin Institute of technology,Harbin 150001,china School of Mathematical Sciences Heilongjiang University Harbin China research center of control and Inertial technology Harbin Institute of Technology Harbin China

Consider the Poisson’s equation Ψ″ (x) = ?e v?Ψ + e Ψ?v ? N(x) with the Dirichlet boundary data, and we mainly investigate the inverse problem of determining the unknown function N(x) from a parameter function fa... 详细信息

关键词： Poisson’s equation well-posedness inverse problem 65N30 35R30

Phase noise floor suppression of the output carrier from double sideband-carrier suppressed modulation system

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Science china(information Sciences) 2011年第6期54卷 1312-1320页

作者： LUO Xin, HAN XiuYou, GU YiYing, LI ShanFeng & ZHAO MingShan School of Physics and Optoelectronic Engineering, dalian university of technology, dalian 116023, china School of Physics and Optoelectronic Engineering Dalian University of Technology Dalian China

A theoretical model of all the influencing factors on the phase noise floor of the output carrier from the double sideband-carrier suppressed (DSB-CS) modulation system is presented. Based on the established DSB-CS modulation system with different cases, the phase noise of the input carrier and the output doubled frequency carrier is measured and calculated using the theoretical model, respectively. The calculation results basically agree with the measurement results. It is shown that the phase noise floor of the output carrier is primarily influenced by the signal-spontaneous beat noise and the relative intensity noise (RIN) of the laser. So the phase noise floor of the output carrier can be minimized by choosing the laser with low RIN and the EDFA with low noise factor.

关键词： microwave photonics double sideband-carrier suppressed modulation phase noise

Energy dispersion of complex non-isolated vortices

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Chinese Science Bulletin 2011年第25期56卷 2713-2717页

作者： LUO ZheXian 1,2 1 Key Laboratory of Meteorological Disaster of Ministry of Education, Nanjing university of information Science and technology, Nanjing 210044, china 2 Wuxi research center of Environmental Science and technology, Wuxi 214031, china Key Laboratory of Meteorological Disaster of Ministry of Education Nanjing University of Information Science and Technology Nanjing China Wuxi research center of Environmental Science and technology Wuxi China

Energy dispersion is a fundamental scientific problem in the study of natural disasters such as typhoons, heavy rain and earthquakes. The problem has been addressed by both multi-discipline research and forecast studies. The dynamics of isolated circular vortex energy dispersion have been solved. However, the disastrous results of typhoons and heavy rain often occur due to non-isolated circular vortices, the dynamics of which are explored in this paper. The energy dispersion characteristics of non-isolated vortices with complex structural patterns are examined using a linearized nondivergent barotropical vorticity equation model. In the initial field, a tropical cyclone (TC) vortex and a meso-scale vortex coexist, forming a complex structural pattern. An analytic solution based on a Fourier transform and simulations using a two-dimensional model show the following. (1) A wave train of TC-G-D may be created by the energy dispersion where the line connecting the three member centers of the wave train is parallel to the x axis in the case of an initial TC vortex without a meso-scale vortex. (2) A wave train of TC-G-D may also be created by energy dispersion. However, the line connecting the three member centers of the wave train would no longer be parallel to the x axis. Instead, they would form a triangle in the presence of the initial TC vortex with the meso-scale vortex. (3) There is a nonlinear relationship between the initial intensity of the meso-scale vortex and the base angle of the triangle. These results have the potential to be applied in the field of typhoon forecasting.

关键词：能量色散非隔离式旋涡非线性关系中尺度涡台风预报结构模式傅立叶变换

Large-eddy simulations and vortex structures of turbulent jets in crossflow

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Science china(Physics,Mechanics & Astronomy) 2007年第1期50卷 118-132页

作者： GUAN Hui1,2 & WU ChuiJie2 1 School of Mechanical and Power Engineering,East china university of Science and technology,Shanghai 200237,china 2 research center for Fluid Dynamics,PLA university of Science and technology,Nanjing 211101,china School of Mechanical and Power Engineering East China University of Science and Technology Shanghai China research center for Fluid Dynamics PLA University of Science and Technology Nanjing China

Using the method of large-eddy simulation, the 3-dimensional turbulent jets in crossflow with stream-wise and transverse arrangements of nozzle are simulated, emphasizing on the dynamical process of generation and evolution of vortex structures in these flows. The results show that the basic vortex structures in literatures, such as the counter-rotating vortex pair, leading-edge vortices, lee-side vortices, hanging vortices, kidney vortices and anti-kidney vortices, are not independent physical substances, but local structures of the basic vortex structure of turbulent jets in crossflow-the 3-D stretching vortex rings originating from the orifice of the nozzle, which is discovered in this study. Therefore, the most important large-scale structures of turbulent jets in crossflow are unified to the 3-D vortex rings which stretch and twist in stream-wise and swing in transverse directions. We also found that the shedding frequencies of vortex rings are much lower than the one corresponding to the appearance of leading-edge and lee-side vortices in the turbulent jets.

关键词： turbulent jet in crossflow coherent structure large-eddy simulation

Identifying heavy hitters in high-speed network monitoring

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Science china(information Sciences) 2010年第3期53卷 659-676页

作者： ZHANG Yu1, FANG BinXing1,2 & ZHANG YongZheng2 1research center of Computer Network and information Security technology, Harbin Institute of technology, Harbin 150001, china 2research center of information Security, Institute of Computing technology, Chinese Academy of Sciences, Beijing 100190, china research center of Computer Network and information Security technology Harbin Institute of Technology Harbin China research center of information Security Institute of Computing Technology Chinese Academy of Sciences Beijing China

Identifying heavy hitters in a network traffic stream is important for a variety of network applications ranging from traffic engineering to anomaly detection such as detection of denial-of-service attacks. Existing methods generally examine newly arriving items in the stream, perform a small number of operations using a small amount of memory, and still provide guarantees on the identifying accuracy. In high-speed network monitoring, the update speed per item is extremely critical. However, so far as we know, there are no identifying algorithms which can provide constant update time (O(1)) in a weighted data stream. In this paper, we present an algorithm named Weighted Lossy Counting (WLC) which is able to identify heavy hitters in a high-speed weighted data stream with constant update time. WLC employs a novel efficient partially ordered data structure which is able to provide a fast per-item update speed while keeping the memory cost relatively low. We compare WLC with state-of-the-art algorithms for finding heavy hitters in real traffic traces. The experimental results show that WLC performs well in accuracy (recall, precision and average relative error) as other algorithms; moreover it has a much higher update speed at the cost of relatively larger memory space used. A theoretical worst-case memory bound of WLC is also derived in this paper; however, experiments with long real traffic traces show that WLC requires much less space than the theoretical bound in practice.

关键词： network traffic monitoring heavy hitter weighted data streams