检索结果-内蒙古大学图书馆

A Fast Averaging Synchronization Algorithm for Clock Oscillators in Nonlinear Dynamical Network with Arbitrary Time-delays

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Acta Automatica Sinica 2010年第6期36卷 873-880页

作者： Jie CHEN Miao YU Li-Hua DOU Ming-Gang GAN School of Automation Beijing Institute of Technology Beijing 100081 P.R.China Key Laboratory of Complex System Intelligent Control and Decision of the Ministry of Education Beijing Institute of Technology Beijing 100081 P. R. China

This paper investigates the synchronization problem of clock oscillators in nonlinear dynamical network with arbitrary time-delays. First, a dynamic synchronization algorithm based on consensus control strategy, named fast averaging synchronization algorithm (FASA), is presented to find a solution to the synchronization problem. This algorithm can compensate the clock skew and offset differences between clock nodes, achieving the synchronization of clock nodes in a shorter time as compared to previous synchronization methods. Second, because of the dynamical performance of FASA, it is characterized from the perspective of compartmental dynamical system with arbitrary time-delays. In this case, the algorithm guarantees the states of all clock nodes in dynamical network converge to Lyapunov stable equilibria. Finally, numerical simulations and experimental results demonstrate the correctness and efficiency of the FASA, which means that the clock nodes can reach global consensus, and the synchronization error can reach nanosecond order of magnitude.

关键词： Clock synchronization dynamical network arbitrary time-delays consensus algorithm

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control of Spatially Interconnected systems with Random Communication Losses

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Acta Automatica Sinica 2010年第2期36卷 258-266页

作者： Hui LI Qing-He WU Huang HUANG School of Automation Beijing Institute of Technology Beijing 100081 P. R. China Key Laboratory of Complex System Intelligent Control and Decision (Beijing Institute of Technology) Ministry of Education Beijing 100081 P. R. China

This paper deals with analysis and synthesis problems of spatially interconnected systems where communicated information may get lost between subsystems. Spatial shift operator and temporal forward shift operator are introduced to model the interconnected systems as discrete time-space multidimensional linear systems with Markovian jumping parameters which reflect the state of communication channels. To ensure the whole system s well-posedness and mean square stability for a given packet loss rate, a condition is derived through analysis. Then a procedure of designing distributed dynamic output feedback controllers is proposed. The controllers have the same structure as the plants and are solved within the linear matrix inequality (LMI) framework. Finally, we apply these results to study the effect of communication losses on the multiple vehicle platoon control system, which further illustrates the effectiveness of the proposed model and method.

关键词： Spatially interconnected system communication loss Markovian jump linear system linear matrix inequality (LMI)

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Learning GMM Using Elliptically Contoured Distributions

Learning GMM Using Elliptically Contoured Distributions

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International Conference on Pattern Recognition

作者： Bo Li Wenju Liu Lihua Dou Key Laboratory of Complex System Intelligent Control and Decision Beijing Institute of Technology China National Laboratory of Pattern Recognition Institute of Automation Chinese Academy and Sciences China Beijing Institute of Technology Beijing Beijing CN

Model order selection and parameter estimation for Gaussian mixture model (GMM) are important issues for clustering analysis and density estimation. Most methods for model selection usually add a penalty term in the objective function that can penalize the models and choose an optimal one from a set of candidate models. This paper presents a simple and novel approach to determine the number of components and simultaneously estimate the parameters for GMM. By introducing the degenerating model, the proposed approach overcomes the drawback of likelihood estimate that is a non-decreasing function and can not be used to select the number of components. The degenerating model is a more general form of mixture component density and it can degenerate into the component density or a crater-like density when its parameter K varies from 1 to a bigger value. The likelihood of the crater-like density evaluated for the training data approximates to zero. This characteristic of the degenerating model forms the foundation of the proposed approach. The experimental results show robust and evident performance improvement of the approach.

关键词： Hidden Markov models Training Programming Gaussian distribution Density functional theory Computational modeling Estimation

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A theorem for relationship between the MA process and its inversion for ARMAX identification

A theorem for relationship between the MA process and its in...

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Chinese control Conference (CCC)

作者： Bin Xin Jie Chen Ministry of Education Key Laboratory of Complex System Intelligent Control and Decision Beijing P. R. China School of Automation Beijing Institute of Technology Beijing P. R. China

The paper presents a theorem to show the relationship between the parameters of the Moving Average (MA) process and those of its inversed process. The theorem can be used for the parameter identification of the MA process. It is further shown in this paper that the parameter identification of autoregressive moving average with exogenous variable model (ARMAX), based on the identification of its MA part, can be easily achieved. The approach, at first, achieves the identification of the ARX part by directly using least-square estimations to find out a straightforward relationship between estimated parameters and observed data. Then, the inversed model of the MA part is identified in a similar way. Finally, the noise variance can be computed by using identified MA parameters. Numerical simulations validate the effectiveness and efficiency of the proposed approach.

关键词： Mathematical model Estimation Noise Biological system modeling Computational modeling Accuracy Autoregressive processes

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Evaluation of continuity effectiveness for networked space based information system

Evaluation of continuity effectiveness for networked space b...

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作者： Chen, Chen Chen, Jie Zhang, Juan Department of Automation Tsinghua University Beijing 100084 China School of Automation Beijing Institute of Technology Beijing 100081 China Key Laboratory of Complex System Intelligent Control and Decision Ministry of Education Beijing 100081 China

ISBN: (纸本)9787894631046

As the trend of future space based information system, networked space based information system can acquire and process all sorts of information more quickly and continuously under the user task scheduling. In the background of earthquake relief for applications, working flow and main tasks of the system are analyzed, and continuity effectiveness evaluation index system is constructed in multi-task level. The continuity effectiveness is a measurement of intensive degree of information returned. Evaluation model based on grey evaluation method is constructed and different reference indexes are used for different tasks. Examples are given by using statistical data in simulation, and the integrative evaluation results are obtained. Detailed evaluation results in every specific task level are offered, which are helpful to find out the effectiveness bottleneck factors meanwhile provide guidance in system design and development.

关键词： Information use

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A novel image restore method based on improved genetic algorithm

A novel image restore method based on improved genetic algor...

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作者： Chen, Wenjie Dou, Lihua School of Automation Beijing Institute of Technology Beijing 100081 China Key Laboratory of Complex System Intelligent Control and Decision Ministry of Education Beijing Institute of Technology Beijing 100081 China

ISBN: (纸本)9787894631046

In this paper, aimed at the problem of conventional image restore method faced to unknown reason of image degrading, a new IGA(improved GA) is brought out and applied to image restoration. And aimed at image restoration problem, the operation of heredity, the group strategy, and maintenance the group variety are all improved as a whole. In this algorithm, the Chaos optimization, the mixed selection and elite reservation method are added, so the algorithm of this paper can give attention to both global search ability and convergence speed and it can give out satisfy restoration result.

关键词： Image reconstruction

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Robust control of hypersonic vehicle based on parameter-dependent Lyapunov functions

Robust control of hypersonic vehicle based on parameter-depe...

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作者： Lu, Pingli Liu, Xiangdong School of Automation Beijing Institute of Technology Beijing 100081 China Key Laboratory of Complex System Intelligent Control and Decision Beijing Institute of Technology Ministry of Education Beijing 100081 China

ISBN: (纸本)9787894631046

Model linearization problem is studied for the longitudinal nonlinear dynamics of hypersonic vehicle. Based on parameter-dependent Lyapunov functions, static feedback controller which guarantees the robust tracking performance is designed for the closed-loop system. Finally, the application to numerical example shows the validity of the proposed design approaches.

关键词： Robust control

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Multipath error analysis of carrier tracking loop in GPS receiver

Multipath error analysis of carrier tracking loop in GPS rec...

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作者： Cheng, Lan Chen, Jie Gan, Ming-Gang School of Automation Beijing Institute of Technology Beijing 100081 China Education Ministry Key Laboratory of Complex System Intelligent Control and Decision Beijing Institute of Technology Beijing 100081 China

ISBN: (纸本)9787894631046

The error of Code Tracking Loop(CTL) of GPS receiver influences the error of carrier tracking loop in the presence of multipath. The error models of carrier tracking loop are established in the multipath environment when the non-coherent Early Minus Late(EML) power mode CTL and the non-coherent Dot-product(DOT) power mode CTL are used. The impacts of multipath parameters and correlator spacing on the error of carrier tracking loop are analyzed by simulation. The simulation results show that the two non-coherent CTLs have little difference in affecting the carrier tracking error. Furthermore, the narrow correlator technology cannot reduce the error of carrier tracking loop.

关键词： Global positioning system

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Automatic target tracking algorithm based on NMI feature matching with Position Prediction and its DSP realization

Automatic target tracking algorithm based on NMI feature mat...

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作者： Chen, Wenjie Liu, Jin Gan, Ming-Gang School of Automation Beijing Institute of Technology Beijing 100081 China Key Laboratory of Complex System Intelligent Control and Decision Ministry of Education Beijing Institute of Technology Beijing 100081 China

ISBN: (纸本)9787894631046

Algorithm based on NMI feature matching and Position Prediction for automatic target tracking are develop for realize an DSP based real-time target tracking system. The target is firstly detected with a improved frame-difference method, and then the target area is segmented based on threshold segmentation and region growth. The NMI feature is used for matching. Finally a combining forecast algorithm is used in the tracking system. This tracking system is implemented with a DSP controller and software is accomplished on DSP/BIOS operation system. It is proved that it can be meet the needs of real-time stably tracking and overcome the disturbance brought by attitude variances and short time occlusion.

关键词： Target tracking

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An image mosaicing approach for video sequences based on space-time manifolds

An image mosaicing approach for video sequences based on spa...

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作者： Zou, Li-Hui Chen, Jie Zhang, Juan Dou, Li-Hua School of Automation Beijing Institute of Technology Beijing 100081 China Key Laboratory of Complex System Intelligent Control and Decision Ministry of Education Beijing Institute of Technology Beijing 100081 China

ISBN: (纸本)9787894631046

In order to utilize the repetitive information among the video sequence more reasonably, this paper proposes an image mosaicing approach based on space-time manifolds for the video sequence taking the properties of high-overlapped ratio between neighbor frames and multiple frames into account. Firstly, we iterate Lucas-Kanade optical flow under Gaussian pyramid strategy to compute the motion parameters between neighbor frames with higher accuracy and align the sequence, in the meantime, eliminate the brightness difference among the neighbors combining with the result of motion computation, and then stitch together the whole sequence whose brightness is already uniform into a high resolution image using the space-time manifolds mosaicing technique. It was verified by the experiment that the proposed approach was very effective to video sequences and the mosaicing result was nice.

关键词： Optical flows

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