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Particle selectivity of filtering by C. elegans

Theoretical & Applied Mechanics Letters 2019年第2期9卷 61-65页

作者： Yuki Suzuki Kenji Kikuchi Keiko Tsuruta-Numayama Takuji Ishikawa Graduate School of Engineering Tohoku University

A nematode Caenorhabditis elegans(C. elegans) is a filter feeder, which draws a suspension of bacteria and separates bacteria from the solvent by using pharyngeal pumping motions and specific mouth parts. This mechanism has not been fully understood. We investigated the mechanism of filtering of bacteria in the pharynx of C. elegans by visualization by fluorescent particles and dyed E. coli. We succeeded in quantifying the selectivity of bacteria-sized particles by C. elegans. The most accumulated particles were those of 0.5 μm in diameter. The quantity of accumulated particles of 0.2 μm or 1.0 μm in diameter was about one third of that of particles of 0.5μm in diameter. The least accumulated particles were those of 0.05 μm in diameter. These results suggest that the pharyngeal structures of C. elegans would be suitable for eating bacteria because the size of bacteria ingested by C. elegans worms is about 0.5 μm in diameter. We also succeeded in visualizing pharyngeal structures and pumping motions and flow in the pharynx. We found that there were phase differences in the motions among procorpus, metacorpus and isthmus. This result suggests filtering would occur at the two tips of procorpus and isthmus by the phase differences. We found that bacteria-sized particles and bacteria were flowed and trapped in the channels, which existed along the central lumen from tip of procorpus to isthmus. From our results, we proposed the novel mechanism of filtering of bacteria through the channels for flowing and trapping. In future, this selective filtering mechanism of C. elegans would be applied to development of microfluidic filtration devices for medical and biological equipment.

关键词： Nematode C.elegans Pharynx Pumping filtering Selectivity

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Code acquisition method based on wavelet transform filtering

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Journal of Systems Engineering and Electronics 2015年第6期26卷 1169-1176页

作者： Chao Wu Luping Xu Hua Zhang Wenbo Zhao School of Aerospace Science and Technology Xidian University

In order to improve the acquisition probability of satellite navigation signals, this paper proposes a novel code acquisition method based on wavelet transform filtering. Firstly, the signal vector based on the signal passing through a set of partial matched filters （PMFs） is built. Then, wavelet domain filtering is performed on the signal vector value. Since the correlation signal is low in frequency and narrow in bandwidth, the noise out-of-band can be filtered out and the most of the useful signal energy is retained. Thus this process greatly improves the signal to noise ratio （SNR）. Finally, the detection variable when the filtered signal goes through the combination process is constructed and the detection based on signal energy is made. Moreover, for the better retaining useful signal energy, the rule of selection of wavelet function has been made. Simulation results show the proposed method has a better detection performance than the normal code acquisition methods under the same false alarm probability.

关键词： code acquisition wavelet transform filtering detection probability.

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Kalman filtering for Delayed Singular Systems with Multiplicative Noise

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IEEE/CAA Journal of Automatica Sinica 2016年第1期3卷 51-58页

作者： Xiao Lu Linglong Wang Haixia Wang Xianghua Wang Key Laboratory for Robot and Intelligent Technology of Shandong Province Shandong University of Science and Technology College of Transportation Shandong University of Science and Technology

Kalman filtering problem for singular systems is dealt with, where the measurements consist of instantaneous measurements and delayed ones, and the plant includes multiplicative noise. By utilizing standard singular value decomposition, the restricted equivalent delayed system is presented, and the Kalman filters for the restricted equivalent system are given by using the well-known re-organization of innovation analysis lemma. The optimal Kalman filter for the original system is given based on the above Kalman filter by recursive Riccati equations, and a numerical example is presented to show the validity and efficiency of the proposed approach, where the comparison between the filter and predictor is also given.

关键词： Kalman filtering filtering estimation reorganization of innovation analysis singular value decomposition

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Novel polarimetric SAR speckle filtering algorithm based on mean shift

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Journal of Systems Engineering and Electronics 2013年第2期24卷 222-233页

作者： Bo Pang Shiqi Xing Yongzhen Li Xuesong Wang School of Electronic Science and Engineering National University of Defense Technology

For better interpretation of synthetic aperture radar（SAR） images,the speckle filtering is an important issue.In the area of speckle filtering,the proper averaging of samples with similar scattering characteristics is of great importance.However,existing filtering algorithms are either lack of a similarity judgment of scattering characteristics or using only intensity information for similarity judgment.A novel polarimetric SAR（PolSAR） speckle filtering algorithm based on the mean shift theory is proposed.As polarimetric covariance matrices or coherency matrices form Riemannian manifold,the pixels with similar scattering characteristics gather closely and those with different scattering characteristics separate in this hyperspace.By using the range-spatial joint mean shift theory in Riemannian manifold,the pixels chosen for averaging are ensured to be close not only in scattering characteristics but also in the spatial domain.German Aerospace Center（DLR） L-Band Experiment SAR（E-SAR） data and East China Research Institute of Electronic Engineering（ECRIEE） PolSAR data are used to demonstrate the efficiency of the proposed algorithm.The filtering results of two commonly used speckle filtering algorithms,refined Lee filtering algorithm and intensity driven adaptive neighborhood（IDAN） filtering algorithm,are also presented for the comparison purpose.Experiment results show that the proposed speckle filtering algorithm achieves a good performance in terms of speckle filtering,edge protection as well as polarimetric characteristics preservation.

关键词： speckle filtering mean shift polarimetric synthetic aperture radar（PolSAR）.

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Single-Layer Symmetrical Full-Port Quasi-Absorptive filtering Phase Shifter

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China Communications 2023年第12期20卷 30-40页

作者： Qingxiang Dong Yongle Wu Weijuan Chen Yuhao Yang Weimin Wang School of Integrated Circuits Beijing University of Posts and TelecommunicationsBeijing 100876China School of Electronic Engineering Beijing University of Posts and TelecommunicationsBeijing 100876China

In this article,a single-layer symmetrical full-port quasi-absorptive filtering phase shifter is presented.The proposed phase shifter is composed of a main quasi-absorptive filtering branch,a reference quasi-absorptive filtering branch,and two delay lines.The proposed phase shifter achieves both phase controlling function and quasi-absorptive filtering function for the first time.Each quasi-absorptive filtering branch can realize the quasi-absorptive filtering function.Meanwhile,the constant phase shift can be obtained by combining the two quasi-absorptive filtering branches and the two delay lines.The design formulas can be derived from the even-and odd-mode network analysis,and then two quasi-absorptive filtering phase shifters can be devised easily and quickly.For verification,a 90°quasi-absorptive filtering phase shifter,which is critical for circularly polarized antenna systems,is simulated,manufactured,and measured.

关键词： filtering phase shifter(PS) quasiabsorptive reflectionless symmetrical

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Gabor Order Tracking filtering Technology in Rotary Machinery

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Chinese Journal of Mechanical Engineering 2010年第5期23卷 613-619页

作者： LI Ning QIN Shuren MAO Yongfang YANG Jiongming College of Mechanical Engineering Chongqing University Chongqing 400044 China Goldwind Science and Technology Co. Ltd. Wulumuqi 830026 China

Order analysis is one of the most important technique means of condition monitoring and fault diagnosis for rotary machinery.The traditional order analyses usually employ the Vold-Kalman filtering,however this method is confined to the expensive hardware equipments.This paper starts from Gabor transform and applies the Gabor time-frequency filtering to vibration signal.The order component＇s time-frequency coefficients are extracted by mask operation.The order component is reconstructed from the obtained coefficients.The following four key technologies,such as smoothing rotary speed curve,defining filtering band width,constructing the mask operation matrix and reconstructing signal component,are also deeply discussed.Moreover,the technique to smooth the rotary speed curve based on polynomial approximation,the method to determine filtering band width,the arithmetic to constitute mask array and the iterative algorithm to reconstruct signal based on minimum mean square error are specifically analyzed.The 4th order component is successfully gained by using the methods that Gabor time-frequency filter,and the validity and feasibility of this method are approved.This method can solve the problem of order tracking filter technologies which used to depend on hardware and efficiently improve the accuracy of order analysis.

关键词： Gabor transform order tracking filtering component extraction

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A 2-Stage Strategy for Non-Stationary Signal Prediction and Recovery Using Iterative filtering and Neural Network

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Journal of Computer Science & Technology 2019年第2期34卷 318-338页

作者： Feng Zhou Hao-Min Zhou Zhi-Hua Yang Li-Hua Yang School of Information Science Guangdong University of Finance and Economics Guangzhou 510320 China School of Mathematics Georgia Institute of Technology Atlanta GA 30332 U.S.A. Guangdong Province Key Laboratory of Computational Science Guangzhou 510275 China School of Mathematics Sun Yat-sen University Guangzhou 510275 China

Predicting the future information and recovering the missing data for time series are two vital tasks faced in various application fields.They are often subjected to big challenges,especially when the signal is nonlinear and nonstationary which is common in practice.In this paper,we propose a hybrid 2-stage approach,named IF2FNN,to predict(including short-term and long-term predictions)and recover the general types of time series.In the first stage,we decompose the original non-stationary series into several“quasi stationary”intrinsic mode functions(IMFs)by the iterative filtering(IF)method.In the second stage,all of the IMFs are fed as the inputs to the factorization machine based neural network model to perform the prediction and recovery.We test the strategy on five datasets including an artificial constructed signal(ACS),and four real-world signals:the length of day(LOD),the northern hemisphere land-ocean temperature index(NHLTI),the troposphere monthly mean temperature(TMMT),and the national association of securities dealers automated quotations index(NASDAQ).The results are compared with those obtained from the other prevailing methods.Our experiments indicate that under the same conditions,the proposed method outperforms the others for prediction and recovery according to various metrics such as mean absolute error(MAE),root mean square error(RMSE),and mean absolute percentage error(MAPE).

关键词： iterative filtering factorization machine neural network time series data recovery

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A 1-Dimensional Nonlinear filtering Problem

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Acta Mathematica Sinica,English Series 2010年第3期26卷 555-560页

作者： Guang Yu LI Ke WANG Department of Mathematics Oujiang College Wenzhou Univercity Wenzhou 325027 P. R. China Department of Mathematics Harbin Institute of Technology Weihai 264209 P. R. China

We will concentrate on a 1-dimensional nonlinear filtering problem, which allows an explicit solution in terms of a stochastic differential equation for Xt.

关键词： Ito＇s formula filtering stochastic differential equation

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Stokes identification in an atomic ensemble using a filtering system

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Chinese Physics B 2009年第11期18卷 4702-4706页

作者：罗霄鸣宁波陈丽清周玥钟志萍蒋硕 Physics Department Tsinghua University Physics Department Nanjing University College of Physical Sciences Graduate University of Chinese Academy of Sciences

Polarization filtering and atomic cell filtering are applied in the identification of Stokes signals in an atomic ensemble, and reduce the noise to a level of 10-5 and 10-4 respectively. Good Stokes signals are then obtained. In this article the two filtering systems and the final Stokes output are presented, and the optimization of the polarization filtering system is highlighted.

关键词： quantum communication Stokes filtering

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H-infinity filtering for discrete-time switched linear systems under arbitrary switching

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控制理论与应用（英文版） 2011年第2期9卷 261-266页

作者： Ding, Dawei Yang, Guanghong Li, Xiaoli University of Science and Technology Beijing Beijing 100083 China College of Information Science and Engineering And State Key Laboratory of Integrated Automation for Process Industry Northeastern University Shenyang 110004 China

This paper is concerned with the problem of H-infinity filtering for discrete-time switched linear systems under arbitrary switching laws.New sufficient conditions for the solvability of the problem are given via switched quadratic Lyapunov functions.Based on Finsler's lemma,two sets of slack variables with special structure are introduced to provide extra degrees of freedom in optimizing the guaranteed H-infinity performance.Compared to the existing methods,the proposed one has better performances and less conservatism.An example is given to illustrate its effectiveness.

关键词： Switched systems Switched quadratic Lyapunov function Finsler's lemma filtering Linear matrix inequality (LMI)

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