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bionic Flapping Pectoral Fin with Controllable Spatial Deformation

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Journal of bionic Engineering 2019年第5期16卷 916-930页

作者： Yueri Cai Lingkun chen Shusheng bi Guoyuan Li Houxiang Zhang Robotics Institute Beihang UniversityBeijing 100191China Department of Ocean Operations and Civil Engineering Norwegian University of Science and TechnologyAalesund 6025Norway

This paper presents the design of a bionic pectoral fin with fin rays driven by multi-joint *** by the cownose ray,the bionic pectoral fin is modeled and simplified based on the key structure and movement parameters of the cownose ray's pectoral fin.A novel bionic propulsion fin ray composed of a synchronous belt mechanism and a slider-rocker mechanism is designed and optimized in order to minimize the movement errors between the designed fin rays and the spanwise curves observed from the cownose ray,and thereby reproducing an actively controllable flapping deformation.A bionic flapping pectoral fin prototype is developed *** verify that the bionic pectoral fin flaps consistently with the design rule extracted from the cownose *** in a towing tank are set up to test its capability of generating the lift force and the propulsion *** movement parameters within the usual propulsion capabilities of the bionic pectoral fm are utilized:The flapping frequency of 0.2 Hz-0.6 Hz,the flapping amplitude of 3°-18°,and the phase di^rence of 10°-60°.The results show that the bionic pectoral fin with actively controllable spatial deformation has expected propulsion performance,which supports that the natural features of the cownose ray play an important role in designing and developing a bionic prototype.

关键词： cownose ray bionic pectoral fin controllable deformation multiple fin rays propulsion perfonnance

Activated carbon induced oxygen vacancies-engineered nickel ferrite with enhanced conductivity for supercapacitor application

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Frontiers of Chemical Science and Engineering 2023年第12期17卷 2088-2100页

作者： Xicheng Gao Jianqiang bi Linjie Meng Lulin Xie chen Liu Key Laboratory for Liquid-Solid Structural Evolution and Processing of Materials(Ministry of Education) School of Materials Science and EngineeringShandong UniversityJinan 250061China

NiFe_(2)O_(4) is a kind of bimetallic oxide possessing excellent theoretical capacity and application prospect in the field of ***,due to the inherent poor conductivity of metal oxides,the performance of NiFe_(2)O_(4) is not ideal in *** vacancies can not only enhance the conductivities of NiFe_(2)O_(4) but also provide better adsorption of OH,which is beneficial to the electrochemical ***,oxygen vacancies engineered NiFe_(2)O_(4)(NiFe_(2)O_(4)‒δ)is obtained through a two-step method,including a hydrothermal reaction and a further heat treatment in activated carbon *** of electron paramagnetic resonance spectra indicate that more oxygen vacancies exist in the treated NiFe_(2)O_(4)‒δthan the original ***-Vis diffuse reflectance spectra prove that the treated NiFe_(2)O_(4)‒δowns better conductivity than the original NiFe_(2)O_(4).As for the electrochemical performances,the treated NiFe_(2)O_(4)‒δperforms a high specific capacitance of 808.02 F∙g^(‒1) at 1 A∙g^(‒1).Moreover,the asymmetric supercapacitor of NiFe_(2)O_(4)‒δ//active carbon displays a high energy density of 17.7 Wh∙kg^(‒1) at the power density of 375 W∙kg^(‒1).This work gives an effective way to improve the conductivity of metal oxides,which is beneficial to the application of metal oxides in supercapacitors.

关键词： nickel ferrite oxygen vacancy high conductivity supercapacitor

Atmospheric deposition of polycyclic aromatic hydrocarbons （PAHs） in Shanghai： the spatio-temporal variation and source identification

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Frontiers of Earth Science 2018年第1期12卷 63-71页

作者： chen chenG Chunjuan bi Dongqi WANG Zhongjie YU Zhenlou chen School of Geographic Sciences East China Normal University Shanghai 200241 China Shanghai Environment Monitoring Center Shanghai 200232 China Department of Geology and Planetary Science University of Pittsburgh Pittsburgh PAl 5217 USA

This study investigated the dry and wet deposition fluxes of atmospheric polycyclic aromatic hydrocarbons （PAHs） in Shanghai, China. The flux sources were traced based on composition and spatio-temporal variation. The results show that wet deposition concentrations of PAHs ranged from 0.07 to 0.67 μg·L-1 and were correlated with temperature （P 〈 0.05）. Dry deposition of PAHs concentrations ranged from 3.60-92.15 μg·L-1 and were higher in winter and spring than in summer and autumn. The annual PAH average fluxes were 0.631 μg·m-2·d-1 and 4.06 μg.m·d-1 for wet and dry deposition, respectively. The highest wet deposition of PAH fluxes was observed in summer, while dry deposition fluxes were higher in winter and spring. Atmospheric PAHs were deposited as dry deposition in spring and winter, yet wet deposition was the dominant pathway during summer. Total atmospheric PAH fluxes were higher in the northern areas than in the southern areas of Shanghai, and were also observed to be higher in winter and spring. Annual deposition of atmospheric PAHs was about 10.8 t in across all of Shanghai. Wet deposition of PAHs was primarily composed of two, three, or four rings, while dry deposition of PAHs was composed of four, five, or six rings. The atmospheric PAHs, composed of four, five, or six rings, primarily existed in the form of particulates. Coal combustion and vehicle emissions were the dominant sources of PAH in the observed area of downtown Shanghai. In suburban areas, industrial pollution, from sources such as coke oven, incinerator, and oil fired power plant, was as significant as vehicle emissions in contributing to the deposition of PAHs.

关键词： PAHs dry and wet deposition temporal andspatial variation Shanghai

NSHV trajectory prediction algorithm based on aerodynamic acceleration EMD decomposition

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Journal of Systems Engineering and Electronics 2021年第1期32卷 103-117页

作者： LI Fan XIONG Jiajun LAN Xuhui bi Hongkui chen Xin Air Force Early Warning Academy Wuhan 430019China Unit 95980 of the PLA Xiangyang 441000China

Aiming at the problem of gliding near space hypersonic vehicle(NSHV)trajectory prediction,a trajectory prediction method based on aerodynamic acceleration empirical mode decomposition(EMD)is *** method analyzes the motion characteristics of the skipping gliding NSHV and verifies that the aerodynamic acceleration of the target has a relatively stable *** this basis,EMD is used to extract the trend of aerodynamic acceleration into multiple sub-items,and aggregate sub-items with similar ***,a prior basis function is set according to the aerodynamic acceleration stability rule,and the aggregated data are fitted by the basis function to predict its future *** that,the prediction data of the aerodynamic acceleration are used to drive the system to predict the target ***,experiments verify the effectiveness of the *** addition,the distribution of prediction errors in space is discussed,and the reasons are analyzed.

关键词： hypersonic vehicle trajectory prediction empirical mode decomposition(EMD) aerodynamic acceleration

Design and fabrication of NiFe_(2)O_(4)/few-layers WS_(2) composite for supercapacitor electrode material

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Frontiers of Materials Science 2023年第3期17卷 83-94页

作者： Xicheng Gao Jianqiang bi Lulin Xie chen Liu Key Laboratory for Liquid-Solid Structural Evolution and Processing of Materials(Ministry of Education) School of Materials Science and EngineeringShandong UniversityJinan 250061China

Few-layers WS_(2) was obtained through unique chemical liquid exfoliation of commercial WS_(2).Results showed that after the exfoliation process,the thickness of WS_(2) reduced ***,the NiFe_(2)O_(4) nanosheets/WS_(2) composite was successfully synthesized through a facile hydrothermal method at 180°C,and then proven by the analyses of field emission scanning electron microscopy,X-ray diffraction,and X-ray photoelectron *** composite showed a high specific surface area of 86.89 m^(2)·g^(−1) with an average pore size of 3.13 ***,in the threeelectrode electrochemical test,this composite exhibited a high specific capacitance of 878.04 F·g^(−1) at a current density of 1 A·g^(−1),while in the two-electrode system,the energy density of the composite could reach 25.47 Wh·kg^(−1) at the power density of 70 W·kg^(−1) and maintained 13.42 Wh·kg^(−1) at the higher power density of 7000 W·kg^(−1).All the excellent electrochemical performances demonstrate that the NiFe_(2)O_(4) nanosheets/WS_(2) composite is an excellent candidate for supercapacitor applications.

关键词： WS_(2) chemical liquid exfoliation NiFe_(2)O_(4) composite supercapacitor

Energy budget of cold and hot gas-solid fluidized beds through CFD-DEM simulations

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Particuology 2024年第6期89卷 153-171页

作者： Lei bi Yunpeng Jiao Chunjiang Liu Jianhua chen Wei Ge School of Chemical Engineering and Technology Tianjin UniversityTianjin 300072China State Key Laboratory of Multiphase Complex Systems Institute of Process EngineeringChinese Academy of SciencesBeijing100190China School of Chemical Engineering University of Chinese Academy of SciencesBeijing 100049China

Direct energy budget is carried out for both cold and hot flow in gas–solid fluidization ***,the energy paths are proposed from thermodynamic *** consumption means total power input to the specific system,and it can be decomposed into energy retention and energy *** retention is the variation of accumulated mechanical energy in the system,and energy dissipation is the energy converted to heat by irreversible *** based on the Computational Fluid Dynamics-Discrete Element Method(CFD-DEM)framework,different energy terms are quantified from the specific flow elements of fluid cells and particles as well as their interactions with the *** order to clarify the energy budget,it is important to identify which system is studied:the particle-fluid system or the particle *** the cold flow,the total energy consumption of the particle sub-system can well indicate the onset of bubbling and turbulent,while the variation of local energy consumption terms can reflect the evolution of heterogeneous *** the hot flow,different heat transfer mechanisms are analyzed and the solver is modified to reproduce the experimental *** impact of the heat transfer mechanisms and heat production on energy consumption is also *** proposed budget method has proven to be energy-conservative and easy to conduct,and it is hopeful to be applied to other multiphase flow systems.

关键词： Energy budget Gas-solid fluidization CFD-DEM Regime transition Heat transfer mechanism

Theoretical and experimental investigation of holographic reconstruction and prediction of multi-source hybrid acoustic field

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Science China(Physics,Mechanics & Astronomy) 2005年第3期48卷 282-299页

作者： bi Chuanxing chen Jian chen Xinzhao YU Fei LI Weibing Dynamic Measuring Center Hefei University of Technology Hefei 230009 China Dynamic Measuring Center Hefei University of Technology Hefei 230009 China Dynamic Measuring Center Hefei University of Technology Hefei 230009 China Dynamic Measuring Center Hefei University of Technology Hefei 230009 China Dynamic Measuring Center Hefei University of Technology Hefei 230009 China

Study on a multi-source hybrid acoustic field is very important for nearfield acoustic holography (NAH) to be applied in the practical engineering field. In this paper, two methods based on the distributed source boundary point method (DSBPM) for holographic reconstruction and prediction of multi-source hybrid acoustic field, namely combination method with single surface measurement and combination method with multi-surface measurement, are proposed. Then, an experiment on two coherent speakers is carried out. By comparison of the reconstructed and predicted results and the actual measured results, the validity of the two methods and the superiority of the combination method with multi-surface measurement are proved. Considering the high sensitivity of the reconstructed results to measurement errors, the Tikhonov regularization method is proposed to stabilize the reconstruction procedure and restrict the influence of errors. And then, the optimal reconstructed results can be obtained and the reliability of holographic reconstruction and prediction is assured.

关键词： acoustic holography, boundary point, distributed source, acoustic radiation, regularization.

Task mapper and application-aware virtual machine scheduler oriented for parallel computing

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Journal of Zhejiang University-Science C(Computers and Electronics) 2012年第3期13卷 155-177页

作者： Jing ZHANG Xiao-jun chen Jun-huai LI Xiang LI School of Computer Science and Engmeering Xi'an University of TechnologyXi'an 710048China State Key Laboratory for Manufacturing Systems Engineering Xi'an Jiaotong UniversityXi'an 710048China

We design a task mapper TPCM for assigning tasks to virtual machines, and an application-aware virtual machine scheduler TPCS oriented for parallel computing to achieve a high performance in virtual computing systems. To solve the problem of mapping tasks to virtual machines, a virtual machine mapping algorithm (VMMA) in TPCM is presented to achieve load balance in a cluster. Based on such mapping results, TPCS is constructed including three components: a middleware supporting an application-driven scheduling, a device driver in the guest OS kernel, and a virtual machine scheduling algorithm. These components are implemented in the user space, guest OS, and the CPU virtualization subsystem of the Xen hypervisor, respectively. In TPCS, the progress statuses of tasks are transmitted to the underlying kernel from the user space, thus enabling virtual machine scheduling policy to schedule based on the progress of tasks. This policy aims to exchange completion time of tasks for resource utilization. Experimental results show that TPCM can mine the parallelism among tasks to implement the mapping from tasks to virtual machines based on the relations among subtasks. The TPCS scheduler can complete the tasks in a shorter time than can Credit and other schedulers, because it uses task progress to ensure that the tasks in virtual machines complete simultaneously, thereby reducing the time spent in pending, synchronization, communication, and switching. Therefore, parallel tasks can collaborate with each other to achieve higher resource utilization and lower overheads. We conclude that the TPCS scheduler can overcome the shortcomings of present algorithms in perceiving the progress of tasks, making it better than schedulers currently used in parallel computing.

关键词： Virtual machine Virtualization Application-aware Parallel computing Virtual machine mapping Credit algorithm Virtual machine scheduling

Seismic Fragility Analysis of Long-Span Bridge System with Durability Degradation

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Computer Modeling in Engineering & Sciences 2019年第10期121卷 177-214页

作者： Yan Liang Jialei Yan Zhanqi cheng huai chen Ruimin Mao College of Civil Engineering Zhengzhou UniversityZhengzhouChina

An offshore long-span continuous rigid-frame bridge is taken as an example to study the effect of degradation of bond-slip behavior on the seismic performance of bridges in an offshore environment during a service *** the basis of a numerical simulation analysis using the OpenSeeS platform,the influence of durability degradation of concrete carbonization,steel corrosion,and degradation of bond-slip performance is considered collectively using incremental dynamic analysis method to examine the time-varying seismic fragility of the offshore *** show that when bond slip is considered,the exceedance probability of the bridge components and the system increases significantly,and the durability degradation caused by concrete carbonization and chloride ion erosion in the whole life cycle increases the seismic response of the bridge *** results of the proposed time-varying seismic fragility analysis indicate that,considering the degradation of bond-slip behavior of reinforced concrete after the durability degradation of materials,the exceedance probability of the pier,bearing,abutment,and system increases with the extension of service period and the increase in seismic strength under earthquake *** addition,with the extension of service time,the effect of bond slip on the seismic fragility of components and system gradually decreases.

关键词： Bridge durability degradation bond slip seismic fragility