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Resonance mechanism of flapping w.ng based on fluid structure interaction simulation

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

作者： Yueyang GUO w.nqing 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 Northw.stern Polytechnical University in Shenzhen Shenzhen 518063China Yangtze River Delta Research Institute of Northw.stern 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 w.ngs based on the Traditional Structural Modal(TSM)***,there exists controversy among researchers regarding the relationship betw.en frequency and aerodynamic *** that the structural response of w.ngs can be influenced by the surrounding air vibrations,an analysis know. 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 w.ngs 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 w.th the maximum time-averaged vertical force coefficient at each mass ratio closely aligns w.th 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 w.ngs w.th varying mass ratios w.ll exhibit similar deformation and vortex structure *** paper offers a fresh perspective on the ongoing debate concerning the resonance mechanism of Flexible Flapping w.ngs(FFw.)and proposes an effective methodology for predicting their aerodynamic performance.

关键词： Flexible Flapping w.ng(FFw. Acoustic Structure Interaction Modal(ASIM) Fluid Structure Interaction(FSI) Resonance mechanism Aerodynamic performance

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Copper slag assisted coke reduction of phosphogypsum for sulphur dioxide preparation

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Chinese Journal of Chemical Engineering 2024年第1期65卷 43-53页

作者： dong Ma Qinhui w.ng State Key Laboratory of Clean Energy Utilization Institute for Thermal Power EngineeringZhejiang UniversityHangzhou 310027China

The reduction of phosphogypsum(PG)to lime slag and SO_(2)using coke can effectively alleviate the environmental problems caused by ***,the PG decomposition temperature remains high and the product yield remains *** adding additives,the decomposition temperature can be further reduced and PG decomposition rate and product yield can be ***,the use of current additives such as Fe_(2)O_(3)and SiO_(2)brings the problem of increasing economic ***,it is proposed to use solid w.ste copper slag(CS)as a new.additive to reduce PG to prepare SO2,w.ich can reduce the cost and meet the environmental benefits at the same *** effects of proportion,temperature and thermostatic time on PG decomposition are investigated by experimental and kinetic analysis combined w.th FactSage thermodynamic calculations to optimize the roasting ***,the reaction mechanism is *** is found that adding CS to the coke and PG system can increase the rate of PG decomposition and SO_(2)yield w.ile low.ring the PG decomposition *** example,w.en the CS/PG mass ratio increases from 0 to 1,PG decomposition rate increases from 83.38%to 99.35%,SO_(2)yield increases from 78.62%to 96.81%,and PG decomposition temperature decreases from 992.4℃to 949.6℃.The optimal reaction parameters are CS/PG mass ratio of 1,Coke/PG mass ratio of 0.06 at 1100℃for 20 min w.th 99.35%PG decomposition rate and 96.81%SO_(2) *** process proceeds according to the follow.ng reactions:2CaSO_(4)+ 0.7C + 0.8Fe_(2)SiO_(4)→0.8Ca_(2)SiO_(4)+ 0.2Ca_(2)Fe_(2)O_(5)+ 0.4Fe_(3)O_(4)+2SO_(2)+ 0.7CO_(2)Finally,a process for decomposing PG w.th coke and CS is proposed.

关键词： Phosphogypsum Sulfur dioxide Copper slag Fluidized-bed Reduction w.ste treatment

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Finite-time Prescribed Performance Time-Varying Formation Control for Second-Order Multi-Agent Systems w.th Non-Strict Feedback Based on a Neural Netw.rk Observer

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IEEE/CAA Journal of Automatica Sinica 2024年第4期11卷 1039-1050页

作者： Chi Ma Dianbiao dong the School of Mechanical Engineering Northwestern Polytechnical UniversityXi’an 710072China

This paper studies the problem of time-varying formation control w.th finite-time prescribed performance for nonstrict feedback second-order multi-agent systems w.th unmeasured states and unknow. *** eliminate nonlinearities,neural netw.rks are applied to approximate the inherent dynamics of the *** addition,due to the limitations of the actual w.rking conditions,each follow.r agent can only obtain the locally measurable partial state information of the leader *** address this problem,a neural netw.rk state observer based on the leader state information is ***,a finite-time prescribed performance adaptive output feedback control strategy is proposed by restricting the sliding mode surface to a prescribed region,w.ich ensures that the closed-loop system has practical finite-time stability and that formation errors of the multi-agent systems converge to the prescribed performance bound in finite ***,a numerical simulation is provided to demonstrate the practicality and effectiveness of the developed algorithm.

关键词： Finite-time control multi-agent systems neural netw.rk prescribed performance control time-varying formation control

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Resilient control of flexible hypersonic vehicles against unmatched distributed faults

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Chinese Journal of Aeronautics 2024年第5期37卷 60-70页

作者： dong ZHAO w.njing REN School of Artificial Intelligence Anhui UniversityHefei 230601China Key Laboratory of System Control and Information Processing Ministry of EducationShanghai Jiao Tong UniversityShanghai 200240China School of Electrical Engineering and Automation Hefei University of TechnologyHefei 230009China

This paper studies a robust fault compensation and vibration suppression problem of flexible hypersonic *** controlled plant is represented by a cascade system composed of a nonlinear Ordinary Differential Equation(ODE)and an Euler-Bernoulli Beam Equation(EBBE),in w.ich the vibration dynamics is coupled w.th the rigid dynamics and suffers from distributed faults.A state differential transformation is introduced to transfer distributed faults to an EBBE boundary and a longitudinal dynamics is refined by utilizing T-S fuzzy IF-THEN rules.A novel T-S fuzzy based fault-tolerant control algorithm is developed and related stability conditions are *** robust exponential stability and w.ll-posedness are proved by using the modified l_(0)-semigroup based Lyapunov direct approach.A simulation study on the longitudinal dynamics of flexible hypersonic vehicles effectively verifies the validity of the developed theoretical results.

关键词： Flexible hypersonic vehicles ODE-EBBE cascade Robust exponential stability Unmatched distributed fault compensation Vibration suppression

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Modeling urban scale human mobility through big data analysis and machinelearning

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Building Simulation 2024年第1期17卷 3-21页

作者： Yapan Liu Bing dong Department of Mechanical&Aerospace Engineering Syracuse University263 Link HallSyracuseNY 13244USA

In the United States,the buildings sector consumes about 76%of electricity use and 40% of all primary energy use and associated greenhouse gas *** behavior has draw. increasing research interests due to its impacts on the building energy ***,occupant behavior study at urban scale remains a challenge,and very limited studies have been *** an effort to couple big data analysis w.th human mobility modeling,this study has explored urban scale human mobility utilizing three months Global Positioning System(GPS)data of 93,o00 users at Phoenix Metropolitan *** research extracted stay points from raw.data,and identified users'home,w.rk,and other locations by Density-Based Spatial Clustering ***,daily mobility patterns w.re constructed using different types of *** propose a novel approach to predict urban scale daily human mobility patterns w.th 12-hour prediction horizon,using Long Short-Term Memory(LSTM)neural netw.rk *** show. the developed models achieved around 85%average accuracy and about 86%mean *** developed models can be further applied to analyze urban scale occupant behavior,building energy demand and flexibility,and contributed to urban planning.

关键词： urban human mobility big data analysis urban scale occupant behavior recurrent neural netw.rks

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Potential reduction in carbon fixation capacity under climate change in a Pinus koraiensis forest

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Forest Ecosystems 2024年第2期11卷 152-161页

作者： dong Kook w.o Department of Civil Engineering Keimyung UniversityDaegu42601Republic of Korea

There has been an increasing recognition of the crucial role of forests, responsible for sequestering atmospheric CO_(2), as a moral imperative for mitigating the pace of climate change. The complexity of evaluating climate change impacts on forest carbon and w.ter dynamics lies in the diverse acclimations of forests to changing environments. In this study, w. assessed tw. of the most common acclimation traits, namely leaf area index and the maximum rate of carboxylation(V_(cmax)), to explore the potential acclimation pathw.ys of Pinus koraiensis under climate change. w. used a mechanistic and process-based ecohydrological model applied to a P. koraiensis forest in Mt. Taehw., South Korea. w. conducted numerical investigations into the impacts of(i) Shared Socioeconomic Pathw.ys 2–4.5(SSP2-4.5) and 5–8.5(SSP5-8.5),(ii) elevated atmospheric CO_(2) and temperature, and(iii) acclimations of leaf area index and V_(cmax)on the carbon and w.ter dynamics of P. koraiensis. w. found that there w.s a reduction in net primary productivity(NPP) under the SSP2-4.5 scenario, but not under SSP5-8.5, compared to the baseline, due to an imbalance betw.en increases in atmospheric CO_(2) and temperature. A decrease in leaf area index and an increase in V_(cmax)of P. koraiensis w.re expected if acclimations w.re made to reduce its leaf temperature. Under such acclimation pathw.ys, it w.uld be expected that the w.ll-know. CO_(2) fertilizer effects on NPP w.uld be attenuated.

关键词： Climate change NEP Pinus koraiensis w.rming Acclimation

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Internal Polarization Field Induced Hydroxyl Spillover Effect for Industrial w.ter Splitting Electrolyzers

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Nano-Micro Letters 2024年第2期16卷 438-449页

作者： Jingyi Xie Fuli w.ng Yanan Zhou Yiw.n dong Yongming Chai Bin dong State Key Laboratory of Heavy Oil Processing College of Chemistry and Chemical EngineeringChina University of Petroleum(East China)Qingdao 266580People’s Republic of China

The formation of multiple oxygen intermediates supporting efficient oxygen evolution reaction(OER)are affinitive w.th hydroxyl ***,ability of the catalyst to capture hydroxyl and maintain the continuous supply at active sits remains a tremendous ***,an affordable Ni2P/FeP2 heterostructure is presented to form the internal polarization field(IPF),arising hydroxyl spillover(HOSo)during *** by IPF,the oriented HOSo from FeP2 to Ni2P can activate the Ni site w.th a new.hydroxyl transmission channel and build the optimized reaction path of oxygen intermediates for low.r adsorption energy,boosting the OER activity(242 mV *** at 100 mA cm-2)for least 100 *** interestingly,for the anion exchange membrane w.ter electrolyzer(AEMw.)w.th low.concentration electrolyte,the advantage of HOSo effect is significantly amplified,delivering 1 A cm^(-2)at a low.cell voltage of 1.88 V w.th excellent stability for over 50 h.

关键词： Hydroxyl spillover effect Internal polarization field Heterostructure Oxygen reduction reaction Anion exchange membrane w.ter electrolysis

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Improved Approximation Schemes for Early w.rk Scheduling on Identical Parallel Machines w.th a Common Due Date

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Journal of the Operations Research Society of China 2024年第2期12卷 341-350页

作者： w.i-dong Li School of Mathematics and Statistics Yunnan UniversityKunming650504YunnanChina

w. study the early w.rk scheduling problem on identical parallel machines in order to maximize the total early w.rk,i.e.,the parts of non-preemptive jobs that are executed before a common due *** preprocessing and constructing an auxiliary instance w.ich has several good properties,for any desired accuracy,w. propose an efficient polynomial time approximation scheme w.th running time O(f(1/ε)n),w.ere n is the number of jobs and f(1/ε)is exponential in 1/ε,and a fully polynomial time approximation scheme w.th running time O(1/ε^(2m+1)+n)w.en the number of machines is fixed.

关键词： Scheduling Early w.rk Polynomial time approximation scheme Effcient polynomial time approximation scheme Fully polynomial time approximation scheme

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A Long-Time-Step-Permitting Tracer Transport Model on the Regular Latitude–Longitude Grid

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Advances in Atmospheric Sciences 2024年第3期41卷 493-508页

作者： Jianghao LI Li dong Key Laboratory of Earth System Modeling and Prediction China Meteorological AdministrationBeijing 100081China State key Laboratory of Numerical Modeling for Atmospheric Sciences and Geophysical Fluid Dynamics(LASG) Institute of Atmospheric Physics(IAP)Chinese Academy of SciencesBeijing 100029China State Key Laboratory of Severe w.ather(LaSw. Chinese Academy of Meteorological SciencesChina Meteorological AdministrationBeijing 100081China College of Earth and Planetary Sciences University of Chinese Academy of SciencesBeijing 100049China

If an explicit time scheme is used in a numerical model, the size of the integration time step is typically limited by the spatial resolution. This study develops a regular latitude–longitude grid-based global three-dimensional tracer transport model that is computationally stable at large time-step sizes. The tracer model employs a finite-volume flux-form semiLagrangian transport scheme in the horizontal and an adaptively implicit algorithm in the vertical. The horizontal and vertical solvers are coupled via a straightforw.rd operator-splitting technique. Both the finite-volume scheme's onedimensional slope-limiter and the adaptively implicit vertical solver's first-order upw.nd scheme enforce monotonicity. The tracer model permits a large time-step size and is inherently conservative and monotonic. Idealized advection test cases demonstrate that the three-dimensional transport model performs very w.ll in terms of accuracy, stability, and efficiency. It is possible to use this robust transport model in a global atmospheric dynamical core.

关键词： tracer transport numerical stability latitude–longitude grid

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CONVERGENCE ANALYSIS OF SOME FINITE ELEMENT PARALLEL ALGORITHMS FOR THE STATIONARY INCOMPRESSIBLE MHD EQUATIONS

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Journal of Computational Mathematics 2024年第1期42卷 49-70页

作者： Xiaojing dong Yinnian He Hunan Key Laboratory for Computation and Simulation in Science and Engineering Key Laboratory of Intelligent Computing&Information Processing of Ministry of EducationSchool of Mathematics and Computational ScienceXiangtan UniversityXiangtan 411105China Institute of Applied Physics and Computational Mathematics Beijing 100088China School of Mathematics and Statistics Xi'an Jiaotong UniversityXi'an 710049China

By combination of iteration methods w.th the partition of unity method(PUM),some finite element parallel algorithms for the stationary incompressible magnetohydrodynamics(MHD)w.th different physical parameters are presented and *** algorithms are highly *** first,a global solution is obtained on a coarse grid for all approaches by one of the iteration *** parallelized residual schemes,local corrected solutions are calculated on finer meshes w.th overlapping *** subdomains can be achieved flexibly by a class of *** proposed algorithm is proved to be uniformly stable and ***,one numerical example is presented to confirm the theoretical findings.

关键词： Partition of unity method Local and parallel algorithm Finite element method Iteration methods Magnetohydrodynamics

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