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Elastic wave propagation and scattering in prestressed porous rocks

Science China Earth Sciences 2020年第9期63卷 1309-1329页

作者： Li-Yun fu bo-Ye fu Weijia SUN Tongcheng HAN Jianlin LIU Key Laboratory of Deep Oil and Gas China University of Petroleum(East China)Qingdao 266580China Laboratory for Marine Mineral Resources Qingdao National Laboratory for Marine Science and TechnologyQingdao 266071China Key Laboratory of Earth and Planetary Physics Institute of Geology and GeophysicsChinese Academy of SciencesBeijing 100029China Institutions of Earth Science Chinese Academy of SciencesBeijing 100029China College of Earth and Planetary Sciences University of Chinese Academy of SciencesBeijing 100049China

Poro-acoustoelastic theory has made a great progress in both theoretical and experimental aspects,but with no publications on the joint research from theoretical analyses,experimental measurements,and numerical *** key issues challenge the joint research with comparisons of experimental and numerical results,such as digital imaging of heterogeneous poroelastic properties,estimation of acoustoelastic constants,numerical dispersion at high frequencies and strong heterogeneities,elastic nonlinearity due to compliant pores,and contamination by boundary *** poroacoustoelastic theory,valid for the linear elastic deformation of rock grains and stiff pores,is modified by incorporating a dualporosity model to account for elastic nonlinearity due to compliant pores subject to high-magnitude loading stresses.A modified finite-element method is employed to simulate the subtle effect of microstructures on wave propagation in prestressed digital *** measure the heterogeneity of samples by extracting the autocorrelation length of digital cores for a rough estimation of scattering *** conductexperimental measurements with a fluid-saturated sandstone sample under a constant confining pressure of 65 MPa and increasing pore pressures from 5 to 60 *** simulations for ultrasound propagation in the prestressed fluid-saturated digital core of the sample are followed based on the proposed poro-acoustoelastic model with compliant *** results demonstrate a general agreement between experimental and numerical waveforms for different stresses,validating the performance of the presented modeling *** excellent agreement between experimental and numerical coda quality factors demonstrates the applicability for the numerical investigation of the stress-associated scattering attenuation in prestressed porous rocks.

关键词： Poro-acoustoelasticity with compliant pores Elastic waves Prestressed porous rocks Numerical modeling Stressinduced scattering attenuation

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Quadratic Stabilization of Switched Uncertain Linear Systems: A Convex Combination Approach

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IEEE/CAA Journal of Automatica Sinica 2019年第5期6卷 1116-1126页

作者： Yufang Chang Guisheng Zhai bo fu Lianglin Xiong the School of Electrical and Electronic Engineering Hubei University of TechnologyWuhan 430068China the Department of Mathematical Sciences Shibaura Institute of TechnologySaitama 337-8570Japan the School of Mathematics and Computer Science Yunnan Minzu UniversityKunming 650500China

We consider quadratic stabilization for a class of switched systems which are composed of a finite set of continuoustime linear subsystems with norm bounded uncertainties. Under the assumption that there is no single quadratically stable subsystem, if a convex combination of subsystems is quadratically stable, then we propose a state-dependent switching law, based on the convex combination of subsystems, such that the entire switched linear system is quadratically stable. When the state information is not available, we extend the discussion to designing an outputdependent switching law by constructing a robust Luenberger observer for each subsystem.

关键词： Convex combination limear matrix inequalities (LMIs) norm bounded uncertainties output-dependent switching, quadratic stabilization state-dependent switching switched uncertain linear systems(SULS)

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Mode splitting and multiple-wavelength managements of surface plasmon polaritons in coupled cavities

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Chinese Physics B 2022年第1期31卷 350-358页

作者： Ping-bo fu Yue-Gang Chen School of Physics Guizhou UniversityGuiyang 550025China

Resonance cavity is a basic element in optics,which has wide applications in optical *** cavities(CCs)designed in metal-insulator-metal(MIM)bus waveguide are investigated through the finite difference time domain method and coupled-mode *** the CCs,the resonant modes of the surface plasmon polaritons(SPPs)split with the thickness decreasing of the middle *** the coupled-mode theory analysis,it is found that the phase differences introduced in opposite and positive couplings between two cavities lead to mode *** resonant wavelength of positive coupling mode can be tuned in a large range(about 644 nm)through adjusting the coupling strength,which is quite different from the classical adjustment of the optical path in a single *** on the resonances of the CCs in the MIM waveguide,more compact devices can be designed to manipulate SPPs propagation.A device is designed to realize flexible multiple-wavelength SPPs *** coupling in CC structures can be applied to the design of easy-integrated laser cavities,filters,multiple-wavelength management devices in SPPs circuits,nanosensors,etc.

关键词： surface plasmon polaritons coupled resonators multiplexing

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An Extended Convex Combination Approach for Quadratic L_(2)Performance Analysis of Switched Uncertain Linear Systems

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IEEE/CAA Journal of Automatica Sinica 2022年第9期9卷 1706-1709页

作者： Yufang Chang Guisheng Zhai Lianglin Xiong bo fu Hubei Collaborative Innovation Center for High-efficiency Utilization of Solar Energy Hubei University of TechnologyWuhan 430068China the Department of Mathematical Sciences Shibaura Institute of TechnologySaitama 337-8570Japan the School of Mathematics and Computer Science Yunnan Minzu UniversityKunming 650500China

Dear Editor,This letter is concerned with quadratic L_(2) performance(quadratic stability and L_(2) gain)for switched uncertain linear systems(SULS)with norm-bounded *** that no single uncertain subsystem achieves quadratic L_(2) performanceγbut a convex combination of the subsystems can make it,we propose a state-dependent switching law such that the SULS achieves the desired quadratic L_(2) *** discussion is extended to the SULS with state feedback control,and a sufficient condition is proposed to design the state feedback gains and the switching law simultaneously.

关键词： quadratic letter Convex

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Switched-capacitor Based Seven-level boost Inverter with a Reduced Number of Devices

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CSEE Journal of Power and Energy Systems 2024年第1期10卷 381-391页

作者： Weijie Lin Jun Zeng bo fu Zhixing Yan Junfeng Liu School of Electric Power Engineering South China University of TechnologyGuangzhou 510641China WISDRI Engineering&Research Incorporation Limited Wuhan 430074China Department of Energy Aalborg UniversityAalborg 9220Denmark School of Automation Science and Engineering South China University of TechnologyGuangzhou 510641China

The conventional multilevel inverters(MLIs)have the disadvantages of numerous devices,incapacity of boost,unbalance for capacitor’s voltage,high complexity for control,and *** by this issue,a seven-level boost inverter(7LBI)based on a switched capacitor is presented for singlephase applications in this *** proposed 7LBI using only seven transistors can achieve seven output levels,1.5 voltage gain,and natural balance of capacitors’voltages without sensors or other auxiliary methods,which illustrates its suitability for the applications of renewable energy *** configuration of topology and operating principles are illustrated in *** natural balance of capacitors and capacitance calculations are deduced as ***,the comparative study is conducted for different types of *** results illustrate the merits of the proposed 7LBI with respect to reduced devices,lower voltage stress,and less power ***,a simulation for the proposed 7LBI with PWM modulation is realized based on the theoretical analysis;an experimental prototype is also implemented,verifying multilevel output,boost ability,natural balance for switched capacitors,and performance of transient response.

关键词： Multilevel inverters voltage gain natural balance renewable energy generation reduced number of elements

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Camera-based Basketball Scoring Detection Using Convolutional Neural Network

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International Journal of Automation and computing 2021年第2期18卷 266-276页

作者： Xu-bo fu Shao-Long Yue De-Yun Pan Department of Public Physical and Art Education Zhejiang UniversityHangzhou 310058China North China Electric Power University Beijing 102206China

Recently,deep learning methods have been applied in many real scenarios with the development of convolutional neural networks(CNNs).In this paper,we introduce a camera-based basketball scoring detection(BSD)method with CNN based object detection and frame difference-based motion *** the proposed BSD method,the videos of the basketball court are taken as ***,the real-time object detection,i.e.,you only look once(YOLO)model,is implemented to locate the position of the basketball ***,the motion detection based on frame difference is utilized to detect whether there is any object motion in the area of the hoop to determine the basketball scoring *** proposed BSD method runs in real-time with satisfactory basketball scoring detection *** experiments on the collected real scenario basketball court videos show the accuracy of the proposed BSD ***,several intelligent basketball analysis systems based on the proposed method have been installed at multiple basketball courts in Beijing,and they provide good performance.

关键词： Computer vision convolutional neural network(CCN) frame difference motion detection object detection real-time system

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Simulation investigation of tractive energy conservation for a cornering rear-wheel-independent-drive electric vehicle through torque vectoring

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Science China(Technological Sciences) 2018年第2期61卷 257-272页

作者： SUN Wen WANG JunNian WANG QingNian ASSADIAN Francis fu bo State Key Laboratory of Automotive Simulation and Control Jilin UniversityChangchun 130022China Department of Mechanical and Aerospace Engineering University of CaliforniaDavisCA 9561USA

Although electric vehicle fully exhibits its comparative merits of energy conservation and environmental friendliness, further improvement of its traction energy efficiency lacks comprehensive investigations in the past. In this paper, the effect of the torque vectoring on traction energy conservation during cornering for a rear-wheel-independent-drive electric vehicle is ***, turning resistance coefficient and energy conservation mechanism of torque vectoring are derived from the single track dynamic model. Next, an optimal torque vectoring control strategy based on genetic algorithm is proposed, with the consideration of the influence of the operation-point change of the in-wheel motors, to find out the best torque vectoring ratio offline. Finally,various simulation tests are conducted to validate the energy conservation effect after Simulink modelling. The results verify that though the optimization of the operating region of the motors is the main part for tractive energy conservation, the contribution of torque vectoring itself can reach up to 1.7% in some typical cases.

关键词： electric vehicle (EV) independent drive cornering resistance torque vectoring energy saving optimization

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The driven cavity turbulent flow with porous walls: Energy transfer, dissipation, and time-space correlations

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Journal of Hydrodynamics 2021年第4期33卷 712-724页

作者： Wen-wu Yang bo-fu Wang Quan Zhou Yu-hong Dong Shanghai Institute of Applied Mathematics and Mechanics School of Mechanics and Engineering ScienceShanghai Key Laboratory of Mechanics in Energy EngineeringShanghai UniversityShanghai200072China

The energy transfer and dissipation as well as the turbulent structures in a lid-driven cavity flow with porous walls are investigated via the lattice boltzmann method, with direct numerical simulation (DNS) for an isothermal incompressible flow for which the Reynolds number (Re) is 50 000. A generalized Navier-Stokes equation with the Brinkman-Forchheimer-extended Darcy model is implemented, in which the presence of permeable walls is taken into account. This study focuses on the modulations of the flow field due to porous walls, by comparing with the results from the cavity flow bounded with smooth walls. Firstly, we derived the exact expression of the kinetic energy dissipation rate in a cavity to study the budget balance of the induced and dissipated kinetic energy. By decomposing the total kinetic energy dissipation into the componential contributions of the viscous and porous medium layer, we found that the kinetic energy dissipated in the thin porous layer occupies 37% of the total driven lid-induced kinetic energy in the present parameters. Then we found that the time-averaged kinetic energy, turbulent kinetic energy (TKE), as well as the strength of the large-scale energy-containing eddy, and secondary eddies are significantly attenuated. furthermore, it is found that the momentum and kinetic energy transfer near the corners are vastly decreased. Finally, the space-time velocity correlation functions are also provided to examine the decorrelation property of small eddies by means of convection and distortion motions in the cavity turbulent field.

关键词： Cavity turbulent flow porous medium energy transfer dissipation time-space correlations

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Linking atmospheric emission and deposition to accumulation of soil cadmium in the Middle-Lower Yangtze Plain,China

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Journal of Integrative Agriculture 2023年第10期22卷 3170-3181页

作者： TANG Li-li fu bo-min WU Yang CAI fu-chen MA Yi-bing National Observation and Research Station of Coastal Ecological Environments in Macao Macao Environmental Research InstituteMacao University of Science and TechnologyMacao SAR 999078P.R.China

Cadmium(Cd)is one of the most toxic heavy metals in the *** deposition has been found to be the main source of Cd pollution of soil on a large scale in China,and identification of the relationships between anthropogenic emission,atmospheric deposition,and Cd accumulation in soil is important for developing ways to mitigate Cd non-point *** this study,the relationship between atmospheric emission,atmospheric deposition,and soil Cd accumulation in the Middle-Lower Yangtze Plain in China was investigated using datasets of atmospheric emission,deposition,and soil accumulation from the literatures published between 2000 and *** results showed that the soil Cd accumulation rate in the study area exceeded the national average(4.0μg kg^(–1)yr^(–1))and continued to accumulate in recent decades,although the average accumulation rate decreased from 9.45μg kg^(–1)yr^(–1)(2000–2010 period)to8.86μg kg^(–1)yr^(–1)(2010–2020 period).The contribution of atmospheric deposition flux to Cd increment in the soil was in the range of 22–29%,with the atmospheric deposition flux decreasing from 0.54 mg m^(–2)yr^(–1)(2000–2010)to 0.48 mg m^(–2)yr^(–1)(2010–2020),both values being greater than the national *** Cd deposition and emission were highly correlated in a provincial administrative region,which is close to a ratio of *** factors may be in a state of dynamic change due to the influences of new Cd emission control technologies and environmental *** the main sources of Cd emissions,dust,and smoke emissions per ton of non-ferrous metal production decreased by 64.7%between the 2000–2010 and 2010–2020 *** new environmental policies have been instigated,atmospheric emission of Cd is still *** was hoped that the findings of this work would provide a scientific basis for the rational control of atmospheric emissions and Cd pollution of soil.

关键词： cadmium soil accumulation atmospheric emission atmospheric deposition

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A Complex Network Model for Analyzing Railway Accidents Based on the Maximal Information Coefficient

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Communications in Theoretical Physics 2016年第10期65卷 459-466页

作者： fu-bo Shao Ke-Ping Li State Key Laboratory of Rail Traffic Control and Safety Beijing Jiaotong University

It is an important issue to identify important influencing factors in railway accident *** this paper,employing the good measure of dependence for two-variable relationships,the maximal information coefficient(MIC),which can capture a wide range of associations,a complex network model for railway accident analysis is designed in which nodes denote factors of railway accidents and edges are generated between two factors of which MIC values are larger than or equal to the dependent *** variety of network structure is *** the increasing of the dependent criterion,the network becomes to an approximate scale-free ***,employing the proposed network,important influencing factors are *** we find that the annual track density-gross tonnage factor is an important factor which is a cut vertex when the dependent criterion is equal to *** the network,it is found that the railway development is unbalanced for different states which is consistent with the fact.

关键词： railway accidents complex network the maximal information coefficient

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