检索结果-南通市图书馆

A circular zone partition method for identifying Duffing oscillator state transition and its application to BPSK signal demodulation

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Science china(information Sciences) 2011年第6期54卷 1274-1282页

作者： FU YongQing 1 , WU DongMei 1 , ZHANG Lin 2 & LI XingYuan 1 1 college of information and Communication engineering, Harbin engineering university, Harbin 150001, china 2 college of Underwater Acoustic engineering, Harbin engineering university, Harbin 150001, china 1. college of information and Communication engineering Harbin Engineering University Harbin 150001 China2. College of Underwater Acoustic Engineering Harbin Engineering University Harbin 150001 China

When a Duffing oscillator is applied to signal detection, identifying its state transition is indispensable. Due to lack of an effective method for automatically distinguishing the state transition, phase analysis is extensively used. However, it needs ocular estimation to identify phase pattern corresponding to transition of Duffing oscillator. Hence it is not fit for communication signal demodulation. To solve the problem, this paper proposes a method, called circular zone partition (CZP), for partitioning trajectory on the phase plane of Duffing oscillator. First, a computing model for Duffing oscillator is described. Then, the fundamental principle and algorithm for the CZP method are discussed. Meanwhile the equation of a circular zone divider and its realization are presented. Thus, by way of the divider, the two-dimensional phase trajectory pattern of Duffing oscillator driven by an external signal can be transformed into the one-dimensional time signal, whose envelop after being filtered is able to indicate the state transition, i.e. the presence or the absence of external signal. Finally, to verify the effect of the CZP method on binary phase shifted keying (BPSK) signal demodulation, two examples are presented and simulation results show that this CZP method is accurate and valid for BPSK signal demodulation.

关键词： chaos nonlinear oscillators signal detection digital communication receivers

The Contraction-Expansion Algorithm and Its Use in Fitting Nonlinear Equation

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

生物数学学报 1998年第4期13卷 426-434页

作者： Gu Shiliang Hui Dafeng Bian Aihua(Quantitative Genetics Lab,Agricultural college,yangzhou university,yangzhou,225.09) 扬州大学农学院江苏扬州

A new optimization method,contraction-expansion algorithm,is devel-oped and applied to fit nonlinear *** points with equal distance are allocated in the given initial intervals,then the algorithm searches for the points of better objective function one round after another,with contracting and expanding intervals *** step length(l),a critical factor to optimal solution,is determined and adjusted by feedback information of the searching *** experiments with number of simulat-ed and real data sets show that the new algorithm is much easier to the optimization than other *** algorithm does not need to provide derivatives of the *** algorithm can also be used in other ptimization problems.

关键词： Optimization algorithm nonlinear equation fitting contraction-ex-pansion algorithm

QoS-guaranteed multi-relay selection and power allocation optimization in cooperative systems

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

The Journal of china Universities of Posts and Telecommunications 2010年第6期17卷 25-31页

作者： CHEN Dan,JI Hong,LI Xi,LI Yi college of information and Communication engineering,Beijing university of Posts and Telecommunications,Beijing 100876,china [a] college of information Communication engineering Beijing University of Posts Telecommunications Beijing 100876 China

This paper investigates the relay selection and power allocation problem in multi-user based cooperative networks,where intermediate relay nodes help source forward information to destination using decode-and-forward （DF） relaying protocol. Specifically,we propose a novel multi-relay nodes selection strategy taking both instantaneous channel state information （I-CSI） and residual energy into consideration,by which ＇emergence＇ diversity gain can be achieved and the imbalance of resource utilization can be overcome. Besides,using Largangian dual-primal decomposition and subgradient projection approach,an optimal power allocation algorithm at source and cooperative relay nodes is presented with the constraints of each user＇s individual quality of service （QoS） requirements and system total transmit power. Theoretical analysis and simulation results demonstrate that the proposed scheme can significantly improve energy efficiency,while guaranteeing a good balance between achievable data rate and average network lifetime with relatively low implementation complexity.

关键词： cooperative diversity relay selection resource allocation Lagrangian dual-primal decomposition subgradient projection

Newton-conjugate gradient (CG) augmented Lagrangian method for path constrained dynamic process optimization

在线全文

学校读者我要写书评

暂无评论

控制理论与应用（英文版） 2012年第2期10卷 223-228页

作者： Qiang ZHANG, Shurong LI, Yang LEI, Xiaodong ZHANG college of information and Control engineering, china university of Petroleum (East china), Qingdao Shandong 266555, china college of information and Control engineering China University of Petroleum (East China) Qingdao Shandong China

In this paper, a Newton-conjugate gradient （CG） augmented Lagrangian method is proposed for solving the path constrained dynamic process optimization problems. The path constraints are simplified as a single final time constraint by using a novel constraint aggregation function. Then, a control vector parameterization （CVP） approach is applied to convert the constraints simplified dynamic optimization problem into a nonlinear programming （NLP） problem with inequality constraints. By constructing an augmented Lagrangian function, the inequality constraints are introduced into the augmented objective function, and a box constrained NLP problem is generated. Then, a linear search Newton-CG approach, also known as truncated Newton （TN） approach, is applied to solve the problem. By constructing the Hamiltonian functions of objective and constraint functions, two adjoint systems are generated to calculate the gradients which are needed in the process of NLP solution. Simulation examlales demonstrate the effectiveness of the algorithm.

关键词： Dynamic process optimization Constraint aggregation Augmented Lagrangian Newton-CG approach Adjoint formulation

Positioning localities from spatial assertions based on Voronoi neighboring

在线全文

学校读者我要写书评

暂无评论

Science china(Technological Sciences) 2010年第S1期53卷 143-149页

作者： GONG YongXi 1,2,3,LI GuiCai 1,LIU Yu 2 & YANG Jian 1 1 Shenzhen Key Lab of Recycling Economy,Peking university Shenzhen Graduate School,Shenzhen 518055,china 2Institute of Remote Sensing and Geographical information Systems,Peking university,Beijing 100871,china 3college of Urban and Environmental Science,Peking university,Beijing 100871,china Peking Univ Shenzhen Grad Sch Shenzhen Key Lab Recycling Econ Shenzhen 518055 Peoples R China Peking Univ Inst Remote Sensing & Geog Informat Syst Beijing 100871 Peoples R China Peking Univ Coll Urban & Environm Sci Beijing 100871 Peoples R China

With the rapid development of Internet,much spatial information contained in non-structured or semi-structured documents is available on the World Wide *** such documents,localities are always textually described using spatial relationships and named places,instead of numerical ***,extracting positional information from locality descriptions is an important *** this paper,we bridge two aspects of locality descriptions,namely generating locality descriptions and positioning localities,and provide a method to compute probability density according to the selection probability of a reference object to describe the position of the target *** operation on uncertainty field is used to deal with locality description involving multiple reference *** metrics are introduced to measure the results of positioning *** choose the mixed selection probability function based on Euclidean distance and Voronoi stolen-area to compute probability density ***,we use three cases to demonstrate the proposed methods.

关键词： geographic information science positioning locality Voronoi neighboring probability density function

A New (t, n) Threshold Signature Scheme Withstanding the Conspiracy Attack

在线全文

学校读者我要写书评

暂无评论

Wuhan university Journal of Natural Sciences 2005年第1期10卷 107-110页

作者： XIE Qi 1,2, YU Xiu-yuan 3 1.Department of Mathematics, Zhejiang university, Hangzhou 310027, Zhejiang,china 2.School of information and engineering, Hangzhou Teachers college, Hangzhou 310012, Zhejiang, china 3.Hangzhou Teachers college, Hangzhou 310012, Zhejiang, china Zhejiang university Department of Mathematics Hangzhou China (GRID:grid.13402.34) (ISNI:***) Hungzhou Teachers college School of Information and Engincering Hangzhou China (GRID:grid.13402.34) Hangzhou Teachers college Hangzhou China (GRID:grid.13402.34)

A ccmspiracy attack is proposed to show that Wang-Li's scheme is instcure,because any t or more group members can impersonate other t member to sign any message withoutholding the responsibility. To avoid the conspiracy attack, this paper prestentsa new (t,n)threshold signature scheme with traceablt signers. A (t. n) threshold signature scheme allows t ormore group members of the group lo generate a signature on behalf of the group, Any less than tmembers cannot generate a valid signature, andany set of the group cannot impersonate another set ofmembers to sign any message without holding the responsibility. In case of disputes., the thresholdsignature can be opened, so that the original signers ean be traced without repealing the secretkeys.

关键词： cryptography threshold signature conspiracy attack identifier tracing

Practical stabilization of receding-horizon control

在线全文

学校读者我要写书评

暂无评论

Journal of Central South university of Technology 2001年第4期8卷 268-271页

作者： LIU Bi yu,GUI Wei hua,MU Min (college of information Science and engineering, Central South university, Changsha 410083, china) 1. college of information Science and engineering Central South University 410083 Changsha China

The purpose of this work is to propose a scheme to stabilize the predictive control systems in the practical stability sense. In the paper, the authors dealt with a general discrete predictive control system x j+1|t =f(x j|t , u j|t ) by using the Lyapunov direct method combining with receding horizon control technique, and presented a new condition to guarantee the practical stabilization of the systems. With the proposed results, one can design the optimal controllers easily to practically stabilize the predictive control systems.

关键词： receding-horizon control practical stability Lyapunov function nonlinear system optimization

MINIMUN TIME OPTIMAL CONTROL OF STEPPING MOTOR

在线全文

学校读者我要写书评

暂无评论

Journal of Central South university 1995年第2期7卷 54-58页

作者： Luo An(college of information engineering, Central South university of Technology, Changsha, 410083, china) 1. college of information engineering Central South University of Technology 410083 Changsha China

The paper describes a new method of the stepping motor moimun time optimal control with closed-loop control. A mathematical model and optimal control strategy for the optimal control of stepping motor are proposed. ... 详细信息

关键词： optimal control stepping motor microcomputer

A novel method of systematic error compensation for a position and orientation system

在线全文

学校读者我要写书评

暂无评论

Progress in Natural Science:Materials International 2008年第8期18卷 953-963页

作者： Xiuxiao Yuan* School of Remote Sensing and information engineering, Wuhan university, Wuhan 430079, china School of Remote Sensing and information engineering Wuhan University Wuhan 430079 China

A novel method is introduced for self-calibration and elimination of systematic errors for a position and orientation system (POS). The method uses a combined bundle block adjustment with POS data (named the POS-supported bundle block adjustment) without a calibration field. On the basis of delivering strict observation equations for POS data, the specific scheme of compensating the translation and drift systematic errors in a POS is given, and a prototype system WuCAPS is developed. The effects of eliminating POS systematic errors using the POS-supported bundle block adjustment for different ground control conditions are tested using two sets of actual aerial photos. The first set was taken over a flat region in the suburbs of the city of Yingkou in china and tested at a scale of 1:2500. The second set was taken over a high mountainous region in the desert region of Xinjiang in china and tested at a scale of 1:32,000. The empirical results verified that the POS systematic errors can be completely eliminated and the photo elements of exterior orientation obtained by the POS-supported bundle block adjustment can satisfy the requirements of aerial photogrammetric topographic mapping when four full ground control points (GCPs) are emplaced in the corners of the adjustment block for large-scale images of flat regions, but only one full GCP emplaced in the center of the adjustment block is needed for medium-small scale images of mountainous regions. This not only demonstrates the validity of the established mathematical model and the feasibility of the method proposed in this paper, but also avoids the use of a special calibration field. Therefore, it can simplify the existing POS operation rules and dramatically save on practical application costs, laying the theoretical foundation for widespread use of POS.

关键词： Position and orientation system (POS) Systematic error POS-supported bundle block adjustment Self-calibration Accuracy