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A Polynomial Prediction Filter Method for Estimating Multisensor Dynamically Varying Biases

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Chinese Journal of Aeronautics 2007年第3期20卷 240-246页

作者： GAO Yu ZHANG Jian-qiu hu Bo Department of Electronics Fudan University Shanghai 200433 China

The estimation of the sensor measurement biases in a multisensor system is vital for the sensor data fusion. A solution is provided for the estimation of dynamically varying multiple sensor biases without any knowledge of the dynamic bias model parameters. It is shown that the sensor bias pseudomeasurement can be dynamically obtained via a parity vector. This is accomplished by multiplying the sensor uncalibrated measurement equations by a projection matrix so that the measured variable is eliminated from the equations. Once the state equations of the dynamically varying sensor biases are modeled by a polynomial prediction filter, the dynamically varying multisensor biases can be obtained by Kalman filter. Simulation results validate that the proposed method can estimate the constant biases and dynamic biases of multisensors and outperforms the methods reported in literature.

关键词： signal processing dynamic bias estimation simulation multisensor Kalman filter

Vibrating Carbon Nanotubes as Water Pumps

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Nano Research 2011年第3期4卷 284-289页

作者： hu qiu Rong Shen Wanlin Guo Institute of Nano Science Nanjing University of Aeronautics and Astronautics Nanjing 210016 China

Nanopumps conducting fluids directionally through nanopores and nanochannels have attracted considerable interest for their potential applications in nanofiltration, water purification, and hydroelectric power generation Here, we demonstrate by molecular dynamics simulations that an excited vibrating carbon nanotube （CNT） cantilever can act as an efficient and simple nanopump. Water molecules inside the vibrating cantilever are driven by centrifugal forces and can undergo a continuous flow from the fixed to free ends of the CNT. Further extensive simulations show that the pumping function holds good not only for a single-file water chain in a narrow （6,6） CNT, but also for bulk-like water columns inside wider CNTs, and that the water flux increases monotonically with increasing diameter of the nanotube.

关键词： Nanopump carbon nanotube nanofluidics centrifugal forces water dynamics

Microstructures and mechanical properties of fiber cells from Echinocactus grusonii cactus spine

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Science China(Technological Sciences) 2014年第4期57卷 706-712页

作者： huANG FengLing qiu hu GUO WanLin State Key Laboratory for mechanics and control of mechanical structures Key Laboratory for Intelligent Nano Materials and Devices of the Ministry of Education and Institute of Nanoscience Nanjing University of Aeronautics and Astronautics Department of Biomedical Engineering College of Automation Engineering Nanjing University of Aeronautics and Astronautics

Spine is the sharpest and hardest part of many plants, which contains highly aligned fiber cells. Here, we report the micro- structures and mechanical properties as well as their correlation of single spine fiber cells （SFCs） from the cactus Echinocactus grusonii. It is found that the SFCs are 0.32-0.57 mm in length and 4.6-6.0 gm in width, yielding an aspect ratio of 53-124. X-ray diffraction and Fourier transform infrared spectrophotometry show that the spine fiber is mainly made up of cellulose I with a crystallinity index up to -76%. Nanoindentation tests show that a natural spine presents a high modulus of -17 GPa. Removing hemicellulose and lignin from the SFC significantly reduces its modulus to -0.487 GPa, demonstrating the critical role of adhesives hemicellulose and lignin in affecting the mechanical properties of the SFCs. This finding sheds light on de- signing novel bio-inspired high-performance composite nanomaterials with aligned nanofibers, such as using hemicellulose and lignin as adhesive in making carbon nanotube fibers.

关键词： spine fibers microstructure indentation modulus

Initiation of dendritic NMDA spikes co-regulated via distance-dependent and dynamic distribution of the spine number and morphology in neuron dendrites

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Science China(Technological Sciences) 2023年第2期66卷 429-438页

作者： CAO YuWei SHEN Chun qiu hu GUO WanLin State Key Laboratory of Tribology Department of Mechanical EngineeringTsinghua UniversityBeijing 100084China State Key Laboratory of Mechanics and Control of Mechanical Structure and Key Laboratory for Intelligent Nano Materials and Devices of the Ministry of Education Institute for Frontier Science and Institute of NanoscienceNanjing University of Aeronautics and AstronauticsNanjing 210016China

Dendritic spines are small membranous protrusions that receive synaptic inputs from other neurons,enabling the initiation of dendritic N-methyl-D-aspartic(NMDA)spikes and somatic action *** learning and memory processes,both the number of spines on a dendrite and the morphology of individual spines are constantly *** individual influence of spine number and morphology on dendritic NMDA spikes has already been revealed,but the functional significance of the coregulation of spine number and morphology on NMDA spikes remains ***,we systematically investigated the initiation of local dendritic NMDA spikes by the dynamic distributions of the spine number and morphology on single dendrites in reconstructed neuron *** from the traditional cognition,we found the threshold number of spines required to generate local dendrite NMDA spikes on distal dendrites is fewer than that on proximal ones,because the thinner distal dendrites own higher *** for the spine morphology,the presence of moreα-amino-3-hydroxy-5-methyl-4-isoxazole-propionic acid(AMPA)receptors on the spine leads to larger NMDA spikes rather than an increase in the spine dimension ***,we first suggested that a single dendrite containing spines with gradually increasing head diameters away from the soma could generate larger NMDA spikes than that irrational distribution of spine morphology containing spines with decreasing head diameters,which can be compensated by the increasing spine ***,the distance-dependent distribution of spine number and morphology co-regulate the intension of dendritic NMDA *** findings about the threshold for NMDA spikes provide novel insights into the role of the irrational dynamic distribution of the spine number and morphology in senescence and disease processes such as Alzheimer’s disease,schizophrenia,and Parkinson’s disease,which causes abnormal neuron firing.

关键词： dendritic spine spine number spine morphology NMDA spikes memory neurological diseases

An analog of Friedel oscillations in nanoconfined water

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National Science Review 2022年第9期9卷 204-211页

作者： Minmin Xue Zhili hu hu qiu Chun Shen Wanlin Guo Zhuhua Zhang Key Laboratory for Intelligent Nano Materials and Devices of Ministry of Education State Key Laboratory of Mechanics and Control of Mechanical Structures and Institute for Frontier Science Nanjing University of Aeronautics and Astronautics

Water confined in nanometer-scale crevices and cavities underpins a wide range of fundamental processes,such as capillary flow,ion transport and protein ***,how water responds within these confined spaces,with prevalent inhomogeneity built in or caused by impurities,is not well ***,we show theoretically that water confined in one-dimensional nano channels with localized perturbation exhibits pronounced density *** oscillations occur vividly like the Friedel oscillations in electron density resulting from defects in metals.A model analysis reveals that the density oscillations result from the perturbation-induced molecular scattering that is augmented by the confinement-enhanced correlation of water *** renders the oscillations a general behavior independent of the channel geometries and specific forms of the *** confinements comparable to biological ion channels,such oscillations can strikingly extend over 10 nm,resulting in non-trivial effects at large distances that,for example,repel all ions from the channels with their long-range *** results deepen the understanding of biological functions and inspire new applications in a variety of domains,such as ionic sensing and seawater desalination.

关键词： ion sieving Friedel oscillations confined water water transport

Laser-Assisted Elastic Electron Scattering from Argon

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Communications in Theoretical Physics 2009年第1期51卷 131-134页

作者： hu qiu-Bo SUN Jin-Feng Department of Mathematics and Physics Luoyang Institute of Science and Technology Luoyang 471003 China College of Physics and Information Engineering Henan Normal University Xinxiang 453007 China Department of Physics Luoyang Normal College Luoyang 471022 China

The second Born approximation （SBA） theory is applied to the study of electron-atom scattering in the presence of a CO2 laser *** absolute differential crass sections of e-Ar scattering are calculated with multiphoton exchange in two special scattering geometries G1 （for small-angle scattering） and G2. For geometry G1, compared with the results of two different model potentials for electron elastic scattering by atoms, it is found that electronatom polarization potential plays an important role in laser-assisted electron-atom scattering. Some calculational results in geometries G2 are given. Our results are found to be better than other theoretical results as compared with the experimental data in geometries G1 and G2.

关键词： atom electron the second Born approximation laser field

Effect of Interaction Potential on Laser-assisted e-Ar Scattering

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Chinese Journal of Chemical Physics 2012年第3期25卷 277-280,373页

作者： Xiao-feiWang qiu-bo hu Jing-feng Sun School of Physics and Engineering Henan University of Science and Technology Luoyang 471023China Department of Mathematics and Science LuoyanE Institute of Science and Technology LuoyanE471023 China College of Physics and Electronic Information LuoyanE Normal College LuoyanE 471022 China

The interaction potentials between electron and atom play an important role in electron- atom scattering. Using three potential models, the absolute differential cross section has been calculated by the second Born approximation theory. Results show that these model potentials are successful in the laser-assisted e-Ar scattering system. The influence of static potential, exchange potential and polarization potential on the absolute differential cross section is also analyzed and discussed.

关键词： Polarization potential Exchange potential Differential cross section Laserfield

Energy Buildup,Flux Confinement and Helicity Accumulation in the Solar Corona

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Chinese Journal of Astronomy and Astrophysics 2006年第1期6卷 77-86页

作者： You-qiu hu Wen Li School of Earth and Space Sciences University of Science and Technology of China Hefei230026

Starting from a dipole field ment of field lines on the photosphere, and a given distribution of footpoint displacewe find axisymmetric, force-free field solutions in spherical coordinates that have the same distribution of normal field on the photosphere and magnetic topology as the dipole field. A photospheric shear is introduced in the azimuthal direction in a region that strides across the equator and ends at latitude λs. The footpoint displacement has a sine distribution in latitude and a peak amplitude of φm. The magnetic energy E, azimuthal flux Fφ, and magnetic helicity lit in the solar corona are then calculated for each force-free field solution. It is found that for a given shear region range λs, all of the three quantities increase monotonically with increasing φm. In particular, both Fφ and HT have a linear dependence on φm. When φm reaches a certain critical value φmc, the force-free field loses equilibrium, leading to a partial opening of the field and the appearance of a current sheet in the equatorial plane. At this point, E, Fφ and HT reach their maximum values, Ec, Fφc and HTo Ec increases, and Fφc and HTc decrease with decreasing λs. It is found that Ec is always smaller than the open field energy, in agreement with the Aly conjecture. Of the three critical parameters, Ec has the weakest dependence on λs. Therefore, if one is interested in the transition of a magnetic configuration from a stable state to a dynamic one, the magnetic energy is probably the most appropriate marker of the transition.

关键词： Sun: magnetic fields -- Sun: force-free fields methods: numerical

FAULT DIAGNOSIS APPROACH BASED ON HIDDEN MARKOV MODEL AND SUPPORT VECTOR MACHINE

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Chinese Journal of Mechanical Engineering 2007年第5期20卷 92-95页

作者： LIU Guanjun LIU Xinmin qiu Jing hu Niaoqing College of Mechatronics Engineering and Automation National University of Defense Technology Changsha 410073 China

Aiming at solving the problems of machine-learning in fault diagnosis, a diagnosis approach is proposed based on hidden Markov model （HMM） and support vector machine （SVM）. HMM usually describes intra-class measure well and is good at dealing with continuous dynamic signals. SVM expresses inter-class difference effectively and has perfect classify ability. This approach is built on the merit of HMM and SVM. Then, the experiment is made in the transmission system of a helicopter. With the features extracted from vibration signals in gearbox, this HMM-SVM based diagnostic approach is trained and used to monitor and diagnose the gearbox＇s faults. The result shows that this method is better than HMM-based and SVM-based diagnosing methods in higher diagnostic accuracy with small training samples.

关键词： Hidden Markov model Support vector machine Fault diagnosis