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Resonance mechanism of flapping wing based on fluid structure interaction simulation

Chinese Journal of Aeronautics 2024年第5期37卷 243-262页

作者： Yueyang GUO wenqing yang Yuanbo dong dong XUE National Key Laboratory of Science and Technology on Aerodynamic Design and Research School of AeronauticsNorthwestern Polytechnical UniversityXi'an 710072China Research&Development Institute of Northwestern Polytechnical University in Shenzhen Shenzhen 518063China yangtze River Delta Research Institute of Northwestern Polytechnical University Taicang 215400China

Certain insect species have been observed to exploit the resonance mechanism of their *** order to achieve resonance and optimize aerodynamic performance,the conventional approach is to set the flapping frequency of flexible wings based on the Traditional Structural Modal(TSM)***,there exists controversy among researchers regarding the relationship between frequency and aerodynamic *** that the structural response of wings can be influenced by the surrounding air vibrations,an analysis known as Acoustic Structure Interaction Modal(ASIM)is introduced to calculate the resonant *** this study,Fluid Structure Interaction(FSI)simulations are employed to investigate the aerodynamic performance of flapping wings at modal frequencies derived from both TSM and ASIM *** performance is evaluated for various mass ratios and frequency ratios,and the findings indicate that the deformation and changes in vortex structure exhibit similarities at mass ratios that yield the highest aerodynamic ***,the flapping frequency associated with the maximum time-averaged vertical force coefficient at each mass ratio closely aligns with the ASIM frequency,as does the frequency corresponding to maximum ***,the ASIM analysis can provide an effective means for predicting the optimal flapping frequency for flexible ***,it enables the prediction that flexible wings with varying mass ratios will exhibit similar deformation and vortex structure *** paper offers a fresh perspective on the ongoing debate concerning the resonance mechanism of Flexible Flapping Wings(FFWs)and proposes an effective methodology for predicting their aerodynamic performance.

关键词： Flexible Flapping Wing(FFW) Acoustic Structure Interaction Modal(ASIM) Fluid Structure Interaction(FSI) Resonance mechanism Aerodynamic performance

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Autonomous navigation method of satellite constellation based on adaptive forgetting factors

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Chinese Journal of Aeronautics 2024年第7期37卷 317-332页

作者： dong WANG Jing yang Kai XIONG School of Automation Science and Electrical Engineering Beihang UniversityBeijing 100191China Science and Technology on Space Intelligent Control Laboratory Beijing Institute of Control EngineeringBeijing 100094China

To address the problem that model uncertainty and unknown time-varying system noise hinder the filtering accuracy of the autonomous navigation system of satellite constellation,an autonomous navigation method of satellite constellation based on the Unscented Kalman Filter with Adaptive Forgetting Factors(UKF-AFF)is *** process noise covariance matrix is estimated online with the strategy that combines covariance matching and adaptive adjustment of forgetting *** adaptive adjustment coefficient based on squared Mahalanobis distance of state residual is employed to achieve online regulation of forgetting factors,equipping this method with more *** intersatellite direction vector obtained from photographic observations is introduced to determine the constellation satellite orbit together with the distance measurement to avoid rank deficiency *** that the number of available measurements varies online with intersatellite visibility in practical applications such as time-varying constellation configurations,the smooth covariance matrix of state correction determined by innovation and gain is adopted and constructed *** analysis of the proposed method is also *** effectiveness of the proposed method is verified by the Monte Carlo simulation and comparison *** estimation accuracy of constellation position and velocity of UKF-AFF is improved by 30%and 44%respectively compared to those of the extended Kalman filter,and the method proposed is also better than other several adaptive filtering methods in the presence of significant model uncertainty.

关键词： Constellation autonomous navigation Unscented Kalman filter Adaptive forgetting factor Model uncertainty Stability analysis

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Wideband Millimeter Wave Antenna with Cavity Backed Slotted Patch and Magneto-Electric Dipole

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Chinese Journal of Electronics 2024年第5期33卷 1234-1244页

作者： yang CHENG Yuandan dong School of Electronic Science and Engineering University of Electronic Science and Technology of China

This paper proposes a wideband cavity-backed slotted patch antenna, loaded with a magneto-electric（ME）-dipole and fed by a microstrip line, for millimeter wave（mm-Wave） applications. The coupled-feed cavitybacked slotted patch antenna is loaded with the ME-dipole. The slotted patch antenna serves as both a radiator and a ground for the ME-dipole. The combination of the ME-dipole antenna and the slotted patch antenna realizes a –10 dB impedance bandwidth covering over 22.86–44.35 GHz（63.9%）. The pattern of the antenna element remains stable throughout this bandwidth. The proposed broadband antenna unit not only realizes single linearly polarized（LP）radiation but also can be designed for dual-LP radiation. The dual-polarized radiation can be achieved by changing the slot of the patch antenna to a crossed slot and altering the ME-dipole antenna to a dual-polarization form. A 2 × 2 dual-polarized array has been designed, fabricated, and tested. A novel dual-polarized feeding network is *** achieve higher isolation, broadband in-phase feed and differential feed are adopted, respectively. A low-loss single to the differential structure is proposed for differential feeding. The simulated isolation of the array is higher than 40 d *** results show that the dual-polarized 2 × 2 array has an overlapping bandwidth of 52.3%(|S11| well suited for mm-Wave applications.

关键词： Slot antennas Costs Dipole antennas Patch antennas Magnetoelectric effects Broadband communication Broadband antennas Array antenna Dual-polarized antenna Feeding network Magneto-electric dipole Millimeter-wave (mm-Wave) Patch BROAD-BAND POLARIZED ANTENNA ARRAY PLANAR BALUN

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Hydrothermal liquefaction of biomass for jet fuel precursors:A review

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Chinese Chemical Letters 2024年第8期35卷 36-49页

作者： Shengfei dong Ziyu Liu Xiaoyi yang School of Energy and Power Engineering Energy and Environment International CentreBeihang UniversityBeijing 100191China School of Aeronautic Science and Engineering Beihang UniversityBeijing 100191China

Climate change is an important issue facing the world today and carbon reduction has become the fo-cus of attention for all *** bio-fuels are an important means to achieve carbon emis-sion *** production of jet fuel precursors from biomass by hydrothermal liquefaction(HTL)has received a lot of attention due to its mild conditions and environmental *** biomass and algal biomass are considered as the second and the third generation biomasses as promising raw materials for alternative fuel *** them,lignocellulosic biomass has been extensively studied due to its wide range of sources and can be divided into one-step HTL and stepwise HTL accord-ing to the process *** biomass has been extensively studied experimentally due to its short growth cycle and the fact that it can sequester large amounts of carbon without taking up arable *** this paper,the feedstock composition of different biomasses is reviewed for the HTL of biomass.A detailed review of the process characteristics,reaction pathways and influencing factors for the HTL pro-duction of jet fuel precursors from lignocellulosic biomass and algal biomass is also *** references are provided for further process optimization and bio-crude quality upgrading.

关键词： Hydrothermal liquefaction(HTL) Lignocellulosic biomass Microalgae Bio-crude Jet fuel precursors

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Risk-Averse Two-Stage Distributionally Robust Economic Dispatch Model Under Uncertain Renewable Energy

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CSEE Journal of Power and Energy Systems 2024年第4期10卷 1514-1524页

作者： Ce yang weiqing Sun Jiannan yang dong Han Department of Control Science and Engineering University of Shanghai for Science and TechnologyShanghai 200093China Department of Electrical Engineering University of Shanghai for Science and TechnologyShanghai 200093China School of Economics and Business Administration Chongqing UniversityChongqing 400044China

With the participation of large quantities of renewable energy in power system operations,their volatility and intermittence increases the difficulties and challenges of power system economic *** the uncertainty of renewable energy generation,based on the distributionally robust optimization method,a two-stage economic dispatch model is proposed to minimize the total operation *** this paper,it is assumed that the fluctuating of renewable power generation follows the unknown probability distribution that is restricted in an ambiguity set,which is established by utilizing the first-order moment information of available historical ***,the theory of conditional value-at-risk is introduced to transform the model into a tractable model,which we call robust counterpart *** on the stochastic dual dynamic programming method,an improved iterative algorithm is proposed to solve the robust counterpart ***,the convergence optimum can be obtained by the improved iterative algorithm,which performs a forward pass and backward pass repeatedly in each iterative ***,by comparing with other methods,the results on the modified IEEE 6-bus,118-bus,and 300-bus system show the effectiveness and advantages of the proposed model and method.

关键词： Energy and reserve co-dispatch distributionally robust conditional value-at-risk stochastic dual dynamic programming

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Adaptive multi-channel Bayesian graph attention network for IoT transaction security

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Digital Communications and Networks 2024年第3期10卷 631-644页

作者： Zhaowei Liu dong yang Shenqiang Wang Hang Su School of Computer and Control Engineering Yantai UniversityYantai264005China Department of Electronics Information and BioengineeringPolitecnico di MilanoMilan20133Italy

With the rapid advancement of 5G technology,the Internet of Things(IoT)has entered a new phase of appli-cations and is rapidly becoming a significant force in promoting economic *** to the vast amounts of data created by numerous 5G IoT devices,the Ethereum platform has become a tool for the storage and sharing of IoT device data,thanks to its open and tamper-resistant ***,Ethereum account security is necessary for the Internet of Things to grow quickly and improve people's *** modeling Ethereum trans-action records as a transaction network,the account types are well identified by the Ethereum account classifi-cation system established based on Graph Neural Networks(GNNs).This work first investigates the Ethereum transaction ***,experimental metrics reveal that the Ethereum transaction network is neither optimal nor even satisfactory in terms of accurately representing transactions per *** flaw may significantly impede the classification capability of GNNs,which is mostly governed by their *** work proposes an Adaptive Multi-channel Bayesian Graph Attention Network(AMBGAT)for Ethereum account clas-sification to address this *** uses attention to enhance node features,estimate graph topology that conforms to the ground truth,and efficiently extract node features pertinent to downstream *** extensive experiment with actual Ethereum transaction data demonstrates that AMBGAT obtains competitive performance in the classification of Ethereum accounts while accurately estimating the graph topology.

关键词： Internet of things Graph representation learning Node classification Security mechanism

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Study on the force chain characteristics with coal dust layer and the three-body contact stiffness

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Particuology 2024年第9期92卷 288-304页

作者： Xinwei yang dongxuan Wu Hongyue Chen dong Wang School of Mechanical Engineering Liaoning Technical UniversityFuxin123000China Ordos Institute of Liaoning Technical University Ordos017000China School of Mining Liaoning Technical UniversityFuxin123000China China National Coal Association Dynamic Research for High-end Complete Integrated Coal Mining Equipment and Big Data Analysis CentreFuxin123000China

To explore the influence of the meso-mechanical behaviors of the wet coal dust layers on the contact stiffness of mechanical bonding surfaces,a three-body contact model incorporating an interface with wet coal dust was constructed based on breakage *** model considered the mechanical surface morphology and contact characteristics of the wet coal *** force chain evolution laws of the wet coal dust layer were elucidated under the effects of gap filling and the cover layer,and the bearing characteristics of the three-body contact bonding surfaces were revealed by quantitative analyses of the number,length,collimation coefficient,and coordination number of the force chains within the wet coal dust ***,the three-body normal contact stiffness under various preload forces was computed and experimentally *** results demonstrate that the external load transfer path of the three-body contact bonding surfaces was from mechanical surface(macroscopic stress)to wet coal dust layer(mesoscopic force chains)and then to mechanical surface(peaks and valleys).The interactions among these three elements contributed to transforming the distributions of the macroscopic stresses and mesoscopic force chains to the locations at the peaks and valleys of the mechanical *** them,the proportion of short force chains in the wet coal dust layer increased from approximately 0.8%–91%,while the proportion of long force chains exhibited an opposite changing *** force chain collimation coefficient initially increased and subsequently stabilized,reaching a maximum value of 0.93.A large number of broken,small particles in the wet coal dust layer mainly served to fill the gaps among large *** maximum relative error between the experimental and simulated values on the three-body contact stiffness is 7.26%,indicating that the simulation results can be an approximate substitute for the experimental results with a certain degree of accuracy and practic

关键词： wet coal dust Force chain Three-body contact stiffness Gap flling effect Cover layer effect

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Investigation of high rate mechanical flow followed by ignition for high-energy propellant under dynamic extrusion loading

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Defence Technology（防务技术） 2024年第2期32卷 336-347页

作者： Liying dong Yanqing Wu Kun yang Xiao Hou State Key Laboratory of Explosion Science and Technology Beijing Institute of TechnologyBeijing 100081China School of Aerospace Engineering Beijing Institute of TechnologyBeijing 100081China

Investigating the ignition response of nitrate ester plasticized polyether(NEPE) propellant under dynamic extrusion loading is of great significant at least for two cases. Firstly, it helps to understand the mechanism and conditions of unwanted ignition inside charged propellant under accident ***, evaluates the risk of a shell crevice in a solid rocket motor(SRM) under a falling or overturning scene. In the present study, an innovative visual crevice extrusion experiment is designed using a dropweight apparatus. The dynamic responses of NEPE propellant during extrusion loading, including compaction and compression, rapid shear flow into the crevice, stress concentration, and ignition reaction, have been firstly observed using a high-performance high-speed camera. The ignition reaction is observed in the triangular region of the NEPE propellant sample above the crevice when the drop weight velocity was 1.90 m/s. Based on the user material subroutine interface UMAT provided by finite element software LS-DYNA, a viscoelastic-plastic model and dual ignition criterion related to plastic shear dissipation are developed and applied to the local ignition response analysis under crevice extrusion conditions. The stress concentration occurs in the crevice location of the propellant sample, the shear stress is relatively large, the effective plastic work is relatively large, and the ignition reaction is easy to occur. When the sample thickness decreases from 5 mm to 2.5 mm, the shear stress increases from 22.3 MPa to 28.6 MPa, the critical value of effective plastic work required for ignition is shortened from 1280 μs to 730 μs, and the triangular area is easily triggering an ignition reaction. The propellant sample with a small thickness is more likely to stress concentration, resulting in large shear stress and effective work, triggering an ignition reaction.

关键词： NEPE propellant Crevice extrusion Shear flow Sample thickness Ignition reaction

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Parallelization strategies for resolved simulations of fluid-structure-particle interactions

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Applied Mathematics and Mechanics(English Edition) 2024年第5期45卷 857-872页

作者： Jianhua QIN Fei LIAO Guodan dong Xiaolei yang The State Key Laboratory of Nonlinear Mechanics Institute of MechanicsChinese Academy of SciencesBeijing 100190China Interdisciplinary Center for Fundamental and Frontier Sciences Nanjing University of Science and TechnologyJiangyin 214443Jiangsu ProvinceChina School of Aeronautics Northwestern Polytechnical UniversityXi'an 710072China School of Engineering Sciences University of Chinese Academy of SciencesBeijing 100049China

Fluid-structure-particle interactions in three spatial dimensions happen in many environmental and engineering *** paper presents the parallel algorithms for the hybrid diffuse and sharp interface immersed boundary(IB)method developed in our previous *** the moving structure modeled using the sharp interface IB method,a recursive box method is developed for efficiently classifying the background grid *** the particles modeled using the diffuse interface IB method,a‘master-slave’approach is *** the particle-particle interaction(PPI)and particle-structure interaction(PSI),a fast algorithm for classifying the active and inactive Lagrangian points,which discretize the particle surface,is developed for the‘dry’contact *** results show that the proposed recursive box method can reduce the classifying time from 52seconds to 0.3 *** parallel efficiency is obtained for cases with different particle ***,the lubrication model is utilized when a particle approaches a wall,enabling an accurate simulation of the rebounding phenomena in the benchmark particle-wall collision *** last,the capability of the proposed computational framework is demonstrated by simulating particle-laden turbulent channel flows with rough walls.

关键词： particle-resolved direct numerical simulation particle-laden flow complex geometry resolved fluid-structure-particle interaction(RFSPI) immersed boundary(IB)method

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Finite Groups with Some Bounded Codegrees

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Acta Mathematica Sinica,English Series 2024年第7期40卷 1778-1784页

作者： dong Fang yang Yu ZENG Heng LV School of Mathematics and Statistics Southwest UniversityChongqing400715P.R.China Department of Mathematics Changshu Institute of TechnologyChangshu215500P.R.China

For a characterχof a finite group G,the number cod(χ) := ∣G:ker(χ)∣/χ(1)is called the codegree ofχ.In this paper,we give a solvability criterion for a finite group G depending on the minimum of the ratioχ(1)^(... 详细信息

关键词： Finite group codegree degree simple group

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