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Application of ensemble kalman filter to geophysical parameters retrieval in remote sensing:A case study of kernel-driven BRDF model inversion

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Science China Earth Sciences 2006年第6期49卷 632-640页

作者： QIN Jun1, YAN Guangjian1, LIU Shaomin1, LIANG Shunlin2, ZHANG Hao1, WANG Jindi1 & LI Xiaowen1 1. State Key Laboratory of Remote Sensing Science, School of Geography and Remote Sensing, Research Center for RS&GIS, Beijing Normal University, Beijing 100875, China 2. Department of Geography, 2181 Lefrak Hall, University of Maryland, College Park, MD20742, USA 1. State Key Laboratory of Remote Sensing Science School of Geography and Remote Sensing Research Center for RS&GIS Beijing Normal University Beijing 100875 China 2. Department of Geography 2181 Lefrak Hall University of Maryland College Park MD20742 USA

The use of a priori knowledge in remote sensing inversion has great implications for ensuring the stability of inversion process and reducing uncertainties in retrieved results, especially under the condition of insufficient observations. Common optimization algorithms have difficulties in providing posterior distribution and thus cannot directly acquire uncertainties in inversion results, which is of no benefit to remote sensing application. In this article, ensemble Kalman filter (EnKF) has been introduced to retrieve surface geophysical parameters from remote sensing observations, which has the capability of not merely obtaining inversion results but also giving its posterior distribution. To show the advantage of EnKF, it is compared to standard MODIS AMBRALS algorithm and highly effi-cient global optimization method SCE-UA. The inversion abilities of kernel-driven BRDF models with different kernel combinations at several main cover types are emphatically discussed when observa-tions are deficient and a priori knowledge is introduced into inversion.

关键词： remote sensing inversion, a priori knowledge, posterior distribution, ensemble kalman filter, BRDF, kernel-driven model, albedo.

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A new compensation current real-time computing method for power active filter based on double linear construction algorithm

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Science China(Technological Sciences) 2006年第4期49卷 485-512页

作者： LI Zicheng SUN Yukun College of Electrical and Information Engineering of Jiangsu University Zhenjiang 212013 China College of Electrical and Information Engineering of Jiangsu University Zhenjiang 212013 China

Considering the detection principle that “when load current is periodic current, the integral in a cycle for absolute value of load current subtracting fundamental active current is the least”, harmonic current real-time detection methods for power active filter are proposed based on direct computation, simple iterative algorithm and optimal iterative algorithm. According to the direct computation method, the amplitude of the fundamental active current can be accurately calculated when load current is placed in stable state. The simple iterative algorithm and the optimal iterative algorithm provide an idea about judging the state of load current. On the basis of the direct computation method, the simple itera- tive algorithm, the optimal iterative algorithm and precise definition of the basic concepts such as the true amplitude of the fundamental active current when load current is placed in varying state, etc., the double linear construction idea is proposed in which the amplitude of the fundamental active current at the moment of the sample is accurately calculated by using the first linear construction and the condition which disposes the next sample is created by using the second linear construction. On the basis of the double linear con- struction idea, a harmonic current real-time detection method for power active filter is proposed based on the double linear construction algorithm. This method has the char- acteristics of small computing quantity, fine real-time performance, being capable of ac- curately calculating the amplitude of the fundamental active current and so on.

关键词： power active filter, harmonic current, active current, reactive current.

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Effect of the Design Parameters on the Performance of Inner-Recycling Continuous Sand filter

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Journal of Donghua University(English Edition) 2002年第3期19卷 40-44页

作者：陈志强温沁雪吕炳南 School of Municipal and Environmental Engineering Harbin Institute of TechnologyHarbin150090

A novel integrated water treatment facility, inner-recycling continuous sand filter, is discussed. The theory of micro-flocculation is applied in the sand-washing circulation system with continuous filtration and backwashing. The design and operation parameters, which affect the performance of the filter, are discussed. The key design parameters are provided as follows: diameter of filter material is 0.7 to 1.0 mm, depth of filter bed is 0.6 m, filtration velocity is less than 12 m/h, ratio of gas to water is 9:11 and sand recycling rate is 2 to 4 mm/min.

关键词： Internal recycling continuous sand filter, filter design parameters, micro-flocculation, size of filter material,thickness of filter bed, filtering velocity, ratio of gas to water,sand recycling rate.

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Theoretical analysis on convergence behavior of rank filters

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Science China Mathematics 2004年第2期47卷 209-219页

作者： YE Wanzhou Department of Mathematics Shanghai Jiaotong University Shanghai 200240 China

This paper systematically studies the convergence behavior of rank filters. The problem of convergence behavior of rank filters has been solved completely for bounded sequences. Moreover, some properties of its limiti... 详细信息

关键词： rank filter, root of rank filter, recurrent sequence.

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Fast density peak-based clustering algorithm for multiple extended target tracking

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Journal of Systems Engineering and Electronics 2019年第3期30卷 435-447页

作者： SHEN Xinglin SONG Zhiyong FAN Hongqi FU Qiang National Key Laboratory of Science and Technology on ATR College of Electronic ScienceNational University of Defense Technology

The key challenge of the extended target probability hypothesis density (ET-PHD) filter is to reduce the computational complexity by using a subset to approximate the full set of partitions. In this paper, the influence for the tracking results of different partitions is analyzed, and the form of the most informative partition is obtained. Then, a fast density peak-based clustering (FDPC) partitioning algorithm is applied to the measurement set partitioning. Since only one partition of the measurement set is used, the ET-PHD filter based on FDPC partitioning has lower computational complexity than the other ET-PHD filters. As FDPC partitioning is able to remove the spatially close clutter-generated measurements, the ET-PHD filter based on FDPC partitioning has good tracking performance in the scenario with more clutter-generated measurements. The simulation results show that the proposed algorithm can get the most informative partition and obviously reduce computational burden without losing tracking performance. As the number of clutter-generated measurements increased, the ET-PHD filter based on FDPC partitioning has better tracking performance than other ET-PHD filters. The FDPC algorithm will play an important role in the engineering realization of the multiple extended target tracking filter.

关键词： fast density peak-based clustering (FDPC), multiple extended target, partition, probability hypothesis density (PHD) filter, track.

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A novel two-layer compact electromagnetic bandgap (EBG) structure and its applications in microwave circuits

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Science China(Technological Sciences) 2003年第4期46卷 439-447页

作者：杨宁陈志宁王蕴仪 ChiaM.Y.W. State Key Laboratory of Millimeter Waves Southeast University InstituteforInfo Comm Research Institute for Info Comm Research

This paper presents a novel two-layer electromagnetic bandgap (EBG) structure. The studies on the characteristics of the cell are carried out numerically and experimentally. A lumped-LC equivalent circuit extracted from the numerical simulation is used to model the bandgap characteristics of the proposed EBG structure. The influences of geometric parameters on the operation frequency and equivalent LC parameters are discussed. A meander line high performance bandstop filter and a notch type duplexer are designed and measured. These EBG structures are shown to have potential applications in microwave and RF systems.

关键词： electromagnetic bandgap, microstrip line, filter, duplexer.

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Resolution method for overlapping peaks based on the fractional-order differential

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Science China Chemistry 2007年第6期50卷 797-805页

作者： LI YuanLu1, YU ShengLin2 & ZHENG Gang2 1 College of Information & Control, Nanjing University of Information Science & Technology, Nanjing 210044, China 2 College of Automation Engineering, Nanjing University of Aeronautics and Astronautics, Nanjing 210016, China 1. College of Information & Control Nanjing University of Information Science & Technology Nanjing 210044 China 2. College of Automation Engineering Nanjing University of Aeronautics and Astronautics Nanjing 210016 China

Equations between the differential order and the maximum of the fractional-order differential for the specified peak signals are developed based on the variation of the maximum of the specified peak signals at different orders. Also, equations between the differential order and the zero-crossing of the fractional-order differential of the specified peak signals are proposed according to the variation of the zero-crossing of the specified peak signals at different orders. Characteristic paramters of the Gaus- sian peak, Lorentzian peak, and Tsallis peak can be estimated using estimator I and estimator II which are obtained by the equations above. As a result, a new method is presented to resolve the overlapped peaks signal. Firstly, a fractional-order differential of the specified peak signals is obtained with the fractional-order differentiation filter. Then, characteristic paramters of the specified peak signals can be extracted using estimator I and estimator II. Finally, the Tsallis peak is used as a model to assign the overlapping peak signals correctly. Experimental results show that the proposed method is efficient and effective for the simulated overlapping peaks and detected overlapping voltammetric peak signals.

关键词： fractional-order differentiation filter, fractional-order differential, overlapping peaks, voltammetric peak

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Implementation of broadband low-sidelobe beamforming in time domain

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声学技术 2003年第z1期22卷 19-23页

作者： YANG Yixin~1, SUN Chao, MA Yuanliang (Institute of Acoustic Engineering, Northwestern Polytechnical University, Xi’an 710072, China) School of Electrical and Electronic Engineering Nanyang Technological university Singapore 639798 Institute of Acoustic Engineering Northwestern Polytechnical University Xi'an 710072 China

In modern active and passive sonar systems, broadband beamforming for acoustic arrays is widely used to suppress unwanted interference and to detect target signals of interest. A broadband low sidelobe beamforming scheme in time domain is proposed in this paper. The first step of this scheme is to delay the outputs of each element in the acoustic array by a tapped-delay-line (TDL) to accomplish the integer part of the time delay need to form a beam. Then, finite impulse response (FIR) digital filters are used to implement the fractional part of the time delay. The weighting coefficients for all array elements at different frequencies to realize the low sidelobe beams are also implemented with the FIR digital filters. Finally, the outputs of the digital filters are summed up to yield the time domain beam output. The design of low sidelobe beam pattern and that of the FIR digital filters are two crucial technical issues in this beamforming procedure. The low sidelobe beams of each sub-band are designed using the optimized beam synthesis approach based on the principle of MVDR beamforming. An improved adaptive approach are used for the design of FIR digital filters, and the design requirements of these filters were specified by the weights of low sidelobe beams of each sub-band over the broad frequency band. Results of computer simulation for a twelve-element arc array show that the beamforming scheme is very effective in forming low sidelobe broadband beam.

关键词： broadband beamforming, low sidelobe level, FIR filter, time domain, sonar

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