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Distributed adaptive Kalman filter based on variational Bayesian technique

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Control Theory and Technology 2019年第1期17卷 37-47页

作者： Chen hu Xiaoming hu Yiguang HONG Rocket Force University of engineering Xi'an Shannxi 710025 China epartment of Mathematics Royal Institute of Sweden (KTH) Sweden Institute of Systems Science and University of Chinese Academy of Sciences Chinese Academy of Sciences Beijing 700790 China

In this paper, distributed Kalman filter design is studied for linear dynamics with unknown measurement noise variance, which modeled by Wishart distribution. To solve the problem in a multi-agent network, a distributed adaptive Kalman filter is proposed with the help of variational Bayesian, where the posterior distribution of joint state and noise variance is approximated by a free-form distribution. The con vergence of the proposed algorithm is proved in two main steps: n oise statistics is estimated, where each age nt only use its local information in variational Bayesian expectation (VB-e) step, and state is estimated by a consensus algorithm in variational Bayesian maximum (VB-M) step. Finally, a distributed target tracking problem is investigated with simulations for illustration.

关键词： Distributed Kalman filter adaptive filter multi-agent system variational Bayesian

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NeS cell

Applied Mathematics and Mechanics(english edition) 2022年第12期43卷 1793-1804页

作者： hu DING Yufei SHAO Shanghai Key Laboratory of Mechanics in energy engineering School of Mechanics and Engineering ScienceShanghai UniversityShanghai200072China

A broadband adaptive vibration control strategy with high reliability and flexible versatility is *** high vibration damping performance of nonlinear energy sink(NeS)has attracted ***,targeted energy transfer may cause severe vibration of ***,it is difficult to realize pure nonlinear stiffness without the linear *** a result,the reliability of NeS is not *** low reliability of NeS has hindered its application in *** addition,the performance of NeS depends on its mass ratio of the primary system,and NeS lacks versatility for different vibration ***,this paper proposes the concept of NeS *** advantages of the adaptive vibration control of NeS are applied to cellular *** applying a large number of NeS cells in parallel,the reliability of NeS and its versatility to complex vibration structures are *** elastic beam is used as the primary vibration structure,and a limited NeS is used as the *** relationship between the vibration suppression effect of NeS cells and the number of NeS cell is *** addition,the effect of the distribution of NeS cells on the multi-mode resonance suppression of the beam is also *** summary,the mode of the primary structure can be efficiently controlled by a large number of lightweight NeS ***,the lightweight NeS cell is flexible for vibration control of complex *** addition,it improves the reliability of NeS ***,the distributed application of NeS cells proposed in this paper is a valuable vibration suppression strategy.

关键词： vibration nonlinear energy sink(NeS) NeS cell vibration control clamped beam harmonic balance method(HBM)

Interaction effects of DNA, RNA-polymerase, and cellular fluid on the local dynamic behaviors of DNA

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Applied Mathematics and Mechanics(english edition) 2020年第4期41卷 623-636页

作者： Weipeng hu Zichen DeNG School of Civil engineering and Architecture Xi’an University of TechnologyXi’an 710048China State Key Laboratory of eco-Hydraulics in Northwest Arid Region of China Xi’an University of TechnologyXi’an 710048China School of Mechanics Civil Engineering and ArchitectureNorthwestern Polytechnical UniversityXi’an 710072China

In view of the complex structure and environment,the dynamic analysis on deoxyribonucleic acid(DNA)is a challenge in the biophysics *** the local interaction with ribonucleic acid(RNA)-polymerase as well as the dissipative effect of cellular fluid,a coupling sine-Gordon-type dynamic model is used to describe the rotational motions of the bases in ***,the approximate symmetric form is ***,the wave form and the wave velocity of the kink solution to the proposed dynamic model are investigated by a Runge-Kutta structure-preserving scheme based on the generalized multi-symplectic *** numerical results indicate that,the strengthening of the local interaction between DNA and RNA-polymerase described by the coupling potential makes the form of the kink solution steep,while the appearance of the friction between DNA and cellular fluid makes the form of the kink solution *** addition,the appearance of the friction decreases the velocities of both the symplectic configuration and the anti-symplectic configuration with different *** above findings are beneficial to comprehend the DNA transcription mechanism.

关键词： deoxyribonucleic acid (DNA) dynamics local interaction generalized multisymplectic idea kink solution Runge-Kutta scheme

Role of competing interactions on dynamic relaxation and exchange bias in spin-glass/ferromagnet bilayer

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Journal of Materials Science & Technology 2020年第16期47卷 63-69页

作者： Xiaodan Chi Yong hu Department of Physics College of SciencesNortheastern UniversityShenyang110819China State Key Laboratory of Rolling and Automation Northeastern UniversityShenyang110819China

When a ferromagnet(FM)couples to a spin glass(SG),the hidden nature of SG may imprint on the FM via their interfacial coupling,probably resulting in elongated magnetic relaxation and enhanced unidirectional and uniaxial *** parallel with the study of interfacial roles,*** coupling and matching,we focused on the influence of the competing interactions in SG(JSG)on the magnetic relaxation properties of SG/FM bilayer and the FM magnetization reversal involving exchange bias field(He)and coercivity(HC).A fastest decay of relaxation in SG/FM bilayer is found at an intermediate JSG^5.2 erg/cm2 and the relaxation parameters related to JSG are *** the other hand,a pronounced He of^0.26 kOe is observed at small JSG,and as JSG increases larger than 2.275 erg/cm2,He decreases by an order of magnitude and levels off,i.e.,a net eB *** is sensitive to JSG only at JSG above 2.275 erg/cm2 and exhibits a minimum value at JSG=4.55 erg/cm2,just below 5.2 erg/cm2 where the relaxation decay is the *** analysis unravels that the net magnetization associated with unidirectional magnetic stabilization and the large-area FM-like domains in SG are favored at small JSG,while with increasing JSG,the SG spins spontaneously reverse and thus the energy barriers are smeared out.A high susceptibility and a strong interfacial coupling lead to FM magnetization reversal under weaker fields and thus a decrease in *** too large JSG(exceeding 5.2 erg/cm2),magnetic frustration extends over the domains in SG meanwhile fierce energy competition occurs frequently,resembling enhanced quantum *** a result,dynamic relaxation and statistic coercivity are both *** work tells us that the independent modulations of unidirectional and uniaxial anisotropies are possible in SG-based systems through precisely controlling JSG,which is desired for application in the read/write head in future data storage media.

关键词： Spin glass Competing interaction Magnetic relaxation exchange bias Coercivity Monte Carlo simulation

Spatial heterogeneity of soil respiration in a Larix gmelinii forest and the response to prescribed fire in the Greater Xing0an Mountains,China

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Journal of Forestry Research 2016年第5期27卷 1153-1162页

作者： Haiqing hu Tongxin hu Long Sun College of Forestry Northeast Forestry UniversityHarbin 150040China

This study was conducted in a fire-prone region in the Greater Xing＇an Mountains, the primary forested area of northeastern China. We measured soil respiration and the affecting soil factors, i.e., soil microbial biomass and soil moisture, within an experimental plot of Larix gmelinii Rupr. A low-intensity, prescribed fire was applied as the treatment. Traditional descriptive statistics and geostatistics were used to analyze the spatial heterogeneity of soil respiration and the response of respiration to fire disturbance. Coefficients of variation （CVs） for pre-fire and post-fire soil respiration were 23.4 and 32.0 %, respec- tively. CVs for post-fire soil respiration increased signifi- cantly, with a moderate variation of all CVs. Soil respiration pre-fire was significantly correlated with soil microbial biomass carbon, biomass nitrogen, and soil moisture （W）; post-fire soil respiration was not correlated with these factors. From the geostatistical analyses, the Co ＋ C （sill） for post-fire soil respiration increased sig- nificantly, indicating that the post-fire spatial heterogeneity of soil respiration increased significantly. The nugget effect （nc） of soil respiration and the affecting factors pre-fire and post-fire disturbance were in the range of 12.5-50 %, with strong spatial autocorrelation. Fire disturbance changed the components of spatial heterogeneity, and the proportion of functional heterogeneity increased significantly post-fire. The ranges （a） for pre-fire and post-fire soil respiration were 81.0 and 68.2 m, respectively. The homogeneity of the distribution of post-fire soil respiration decreased and the spatial heterogeneity increased, thus the range for post- fire soil respiration decreased significantly. The fractal dimension （D） for soil respiration increased post-fire, the spatial heterogeneity of soil respiration affected by random components increased, indicating that the change in spatial heterogeneity of post-fire soil respiration should be c

关键词： Prescribed fire - Soil respiration Spatialheterogeneity Larix gmelinii forest

Odd elasticity realized by piezoelectric material with linear feedback

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Science China(Physics,Mechanics & Astronomy) 2021年第11期64卷 108-117页

作者： Wen Cheng Gengkai hu School of Aerospace engineering Beijing Institute of TechnologyBeijing 100081China

The systems exhibiting sustainable external energy exchange are abundant,e.g.,biological organisms’reaction to external stimuli while maintaining a constant energy exchange with the *** a linear mechanical system exhibiting an external energy gain or release,the recently proposed odd elasticity theory can characterize the overall stress and strain ***,realizing the required odd elasticity is still *** this work,we discovered that the smart materials with designed feedbacks can achieve this odd elasticity,thereby providing a practical platform to analyze the phenomenon related to this novel elasticity *** also demonstrated this idea by designing a non-reciprocal Rayleigh wave via odd elasticity and the equivalent piezoelectricity with linear *** underpinned electric energy scenario was also *** work establishes a method to easily realize the materials with odd elastic behaviors and explore the rich phenomena related to nonHermitian systems.

关键词： odd elasticity piezoelectricity feedback Rayleigh wave unidirectional invisibility

Detecting spatio-temporal urban surface changes using identified temporary coherent scatterers

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Journal of Systems engineering and electronics 2021年第6期32卷 1304-1317页

作者： hu Fengming WU Jicang Key Laboratory for Information Science of electromagnetic Waves Fudan UniversityShanghai 200433China College of Surveying and Geo-Informatics Tongji UniversityShanghai 200092China

Synthetic aperture radar(SAR) is able to detect surface changes in urban areas with a short revisit time, showing its capability in disaster assessment and urbanization *** presented change detection methods are conducted using couples of SAR amplitude images. However, a prior date of surface change is required to select a feasible image pair. We propose an automatic spatio-temporal change detection method by identifying the temporary coherent scatterers. Based on amplitude time series, χ^(2)-test and iterative single pixel change detection are proposed to identify all step-times: the moments of the surface change. Then the parameters, e.g., deformation velocity and relative height, are estimated and corresponding coherent periods are identified by using interferometric phase time series. With identified temporary coherent scatterers, different types of temporal surface changes can be classified using the location of the coherent periods and spatial significant changes are identified combining point density and F values. The main advantage of our method is automatically detecting spatio-temporal surface changes without prior information. experimental results by the proposed method show that both appearing and disappearing buildings with their step-times are successfully identified and results by ascending and descending SAR images show a good agreement.

关键词： change detection temporary coherent scatterer multi-temporal interferometric synthetic aperture radar(InSAR) amplitude analysis

Temperature coefficient of seawater pH as a function of temperature,pH,DIC and salinity

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Acta Oceanologica Sinica 2022年第6期41卷 114-118页

作者： Yubin hu Institute of Marine Science and Technology Shandong UniversityQingdao 266237China

pH is a measure of the hydrogen ion activity in a solution,which is a function of *** normal seawater conditions,it is well ***,with an increasing interest in complex environments(e.g.,sea ice),a better understanding of the temperature change on pH under extreme conditions is *** objective of this paper was to investigate the temperature coefficient of the seawater pH(△pH/△T)over a wide range of temperature,pH,dissolved inorganic carbon(DIC)and salinity by a method of continuous pH measurement with the temperature change,and to verify the application of CO2SYS for pH conversion under extreme conditions(on the National Bureau of Standards(NBS)scale and the total proton scale).Both experimental results and CO2SYS calculations showed that△pH/△T was slightly affected by temperature over the range of 0℃ to 40℃ and by pH(at 25℃)from 7.8 to ***,when pH was out of this range,△pH/△T varied greatly with pH *** to the experimental results,changes in DIC from 1 mmol/kg to 5 mmol/kg and salinity from 20 to 105 had no significant effect on△pH/△***2SYS calculations showed a slight increase in△pH/△T with DIC on both the NBS scale and the total proton scale;and underestimated△pH/△T at high salinity(i.e.,beyond the oceanographic range)on the NBS ***,CO2SYS is still suitable for pH conversion even under extreme conditions by simply setting the input values of DIC and salinity in CO2SYS within the oceanographic range(e.g.,DIC=2 mmol/kg and S=35).

关键词： temperature coefficient pH measurement CO2SYS sea ice ocean acidification

A method for quantifying bias in modeled concentrations and source impacts for secondary particulate matter

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Frontiers of environmental Science & engineering 2016年第5期10卷 153-164页

作者： Cesunica e. lvey Heather A. Holmes Yongtao hu James A. Muiholland Armistead G. Russell School of Civil and environmental engineering Georgia Institute of Technology 311 Ferst Drive Atlanta GA 30332 USA Department of Physics University of Nevada Reno 1664 N Virginia St Reno NV 89557 USA

Community Multi-Scale Air Quality （CMAQ） estimates of sulfates, nitrates, ammonium, and organic carbon are highly influenced by uncertainties in modeled secondary formation processes, such as chemical mechanisms, volatilization, and condensation rates. These compounds constitute the majority ofPM2.5 mass, and reducing bias in estimated concentrations has benefits for policy measures and epidemiological studies. In this work, a method for adjusting source impacts on secondary species is developed that provides estimates of source contributions and reduces bias in modeled concentrations compared to observations. The bias correction adjusts concentrations and source impacts based on the difference between modeled concentrations and observations while taking into account uncertainties at the location of interest; and it is applied both spatially and temporally. We apply the method over the US for 2006. The mean bias for initial CMAQ concentrations compared to observations is -0.28 （OC）, 0.11 （NO3）, 0.05 （NH4）, and -0.08 （SO4）. The normalized mean bias in modeled concentrations compared to observations was effectively zero for OC, NO3, NH4, and SO4 after applying the secondary bias correction. Ten-fold cross-validation was conducted to determine the performance of the spatial application of the bias correction. Cross-validation performance was favorable; correlation coefficients were greater than 0.69 for all species when comparing observations and concentrations based on kriged correction factors. The methods presented here address model uncertainties by improving simulated concentrations and source impacts of secondary particulate matter through data assimilation. Secondary-adjusted concentrations and source impacts from 20 emissions sources are generated for 2006 over continental US.

关键词： Particulate matter Source apportionment Secondary particulate matter Chemical transport modeling Receptor modeling