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A robust implicit high-order discontinuous Galerkin method for solving compressible Navier-Stokes equations on arbitrary grids

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Acta Mechanica Sinica 2024年第8期40卷 96-119页

作者： jia yan Xiaoquan yang Peifen Weng Shanghai Institute of Applied Mathematics and Mechanics Shanghai Key Laboratory of Mechanics in Energy EngineeringSchool of Mechanics and Engineering ScienceShanghai UniversityShanghai200072China College of Energy and Mechanical Engineering Shanghai University of Electric PowerShanghai200090China

The primary impediments impeding the implementation of high-order methods in simulating viscous flow over complex configurations are robustness and *** challenges impose significant constraints on computational efficiency,particularly in the domain of engineering *** address these concerns,this paper proposes a robust implicit high-order discontinuous Galerkin(DG)method for solving compressible Navier-Stokes(NS)equations on arbitrary *** method achieves a favorable equilibrium between computational stability and *** solve the linear system,an exact Jacobian matrix solving strategy is employed for preconditioning and matrix-vector generation in the generalized minimal residual(GMRES)*** approach mitigates numerical errors in Jacobian solution during implicit calculations and facilitates the implementation of an adaptive Courant-Friedrichs-Lewy(CFL)number increasing strategy,with the aim of improving convergence and *** further enhance the applicability of the proposed method for intricate grid distortions,all simulations are performed in the reference *** practice significantly improves the reversibility of the mass matrix in implicit calculations.A comprehensive analysis of various parameters influencing computational stability and efficiency is conducted,including CFL number,Krylov subspace size,and GMRES convergence *** computed results from a series of numerical test cases demonstrate the promising results achieved by combining the DG method,GMRES solver,exact Jacobian matrix,adaptive CFL number,and reference domain calculations in terms of robustness,convergence,and *** analysis results can serve as a reference for implicit computation in high-order calculations.

关键词： Discontinuous Galerkin method Exact Jacobian matrix GMRES solver Adaptive CFL number Reference domain High-order

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A real-time calibration method based on time-to-digital converter for accelerator timing system

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Nuclear Science and Techniques 2024年第9期35卷 127-140页

作者： Qi-Hao Duan Liang Ge yan-Hao jia Jie-Yu Zhu Wei Zhang Institute of modern physics Chinese Academy of SciencesLanzhou 730000China University of Chinese Academy of Sciences Beijing 100049China

The high-intensity heavy-ion accelerator facility(HIAF)is a scientific research facility complex composed of multiple cas-cade accelerators of different types,which pose a scheduling problem for devices distributed over a certain range of 2 km,involving over a hundred *** white rabbit,a technology-enhancing Gigabit Ethernet,has shown the capability of scheduling distributed timing devices but still faces the challenge of obtaining real-time synchronization calibration param-eters with high *** study presents a calibration system based on a time-to-digital converter implemented on an ARM-based System-on-Chip(SoC).The system consists of four multi-sample delay lines,a bubble-proof encoder,an edge controller for managing data from different channels,and a highly effective calibration module that benefits from the SoC *** performance was evaluated with an average RMS precision of 5.51 ps by measuring the time intervals from 0 to 24,000 ps with 120,000 data for every *** design presented in this study refines the calibration precision of the HIAF timing *** eliminates the errors caused by manual calibration without efficiency loss and provides data support for fault *** can also be easily tailored or ported to other devices for specific applications and provides more space for developing timing systems for particle accelerators,such as white rabbits on HIAF.

关键词： HIAF White rabbit Calibration system Time-to-digital converter(TDC)

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Contributors to tidal duration asymmetry with varied coastline configurations on western shelf of Yellow Sea

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Water Science and Engineering 2024年第1期17卷 1-12页

作者： Xi Feng Zheng Li Hui Feng jia-yan yang Shou-peng Xie Wei-bing Feng College of Harbor.Coastal and Offshore Engineering Hohai UniversityNanjing 210098China China Harbour Engineering Co. LtdBeijing 100027China Key Laboratory of Port Waterway and Sedimentation Engineering of the Ministry of CommunicationsNanjing 210029China China South-to-North Water Diversion Corporation Limited Beijing 100036China

Coastal management in China is confronted with an urgent choice between natural restoration and maintenance of existing seawalls and reclaimed land for economic development.A key criterion for making this decision is the resilience to coastal flooding,which depends on the ability to predict tidal *** duration asymmetry(TDA)is a key parameter in determination of the arrival and duration of flood *** study selected the western inner shelf of the Yellow Sea(WYS)as the study area and investigated the responses of TDA to different shoreline configurations and relative sea level *** responses of TDA to shoreline reconstruction yielded spatial variability locally and *** the nearshore area,the responses of TDA to the complex ocean environment mainly originated from the combined functions of reflection,bottom friction,and advection,which controlled the energy transfer from M2 or S2 constituents to their overtides or compound *** sensitivity of TDA to coastline typologies was not limited to coastal waters but could stretch over the entire inner *** vulnerability of tidal responses was due to the displacement of the M2 amphidrome of the Kelvin wave on the WYS,which in turn changed tidal energy fluxes over the *** relative sea level rise could intensify the feedback of TDA to seawalls and land reclamation.

关键词： Tidal duration asymmetry Western inner shelf of Yellow Sea Natural restoration Relative sea level rise Tidal amphidrome

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Short-Term Prediction of Photovoltaic Power Based on DBSCAN-SVM Data Cleaning and PSO-LSTM Model

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Energy Engineering 2024年第10期121卷 3019-3035页

作者： Yujin Liu Zhenkai Zhang Li Ma yan jia Weihua Yin Zhifeng Liu School of Energy and Power Engineering Inner Mongolia University of TechnologyHohhot010051China Key Laboratory ofWind Energy and Solar Energy Utilization Technology Ministry of EducationHohhot010051China Production Management Department Inner Mongolia Energy Power Generation Investment Group Co.Ltd.Hohhot010051China

Accurate short-termphotovoltaic(PV)power prediction helps to improve the economic efficiency of power stations and is of great significance to the arrangement of grid scheduling *** order to improve the accuracy of PV power prediction further,this paper proposes a data cleaning method combining density clustering and support vector *** constructs a short-termPVpower predictionmodel based on particle swarmoptimization(PSO)optimized Long Short-Term Memory(LSTM)***,the input features are determined using Pearson’s correlation *** feature information is clustered using density-based spatial clustering of applications withnoise(DBSCAN),and then,the data in each cluster is cleanedusing support vectormachines(SVM).Secondly,the PSO is used to optimize the hyperparameters of the LSTM network to obtain the optimal network ***,different power prediction models are established,and the PV power generation prediction results are *** results show that the data methods used are effective and that the PSO-LSTM power prediction model based on DBSCAN-SVM data cleaning outperforms existing typical methods,especially under non-sunny days,and that the model effectively improves the accuracy of short-term PV power prediction.

关键词： Photovoltaic power prediction LSTM network DBSCAN-SVM PSO deep learning

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The function of doping nitrogen on removing fluoride with decomposing La-MOF-NH_2:Density functional theory calculation and experiments

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Journal of Environmental Sciences 2024年第1期135卷 118-129页

作者： Hongguo Zhang KuilinWan jia yan Qian Li Yufang Guo Lei Huang Samuel Raj Babu Arulmani jian Luo School of Environmental Science and Engineering Guangzhou UniversityGuangzhou 510006China Guangzhou University-Linkoping University Research Center on Urban Sustainable Development Guangzhou UniversityGuangzhou 510006China School of Civil and Environmental Engineering Georgia Institute of TechnologyAtlantaGA 30332USA

Fluoride is an important pollutant in wastewater,and adsorption is an effective way to remove *** nitrogen plays an important role in adsorbent materials,computational models were developed to understand the changes in work function resulting from nitrogen ***-N-C-800℃,was prepared by pyrolyzing La-MOF-NH_(2)to verify the influence on the performance of removing fluoride by *** and electrochemical performance tests were performed to characterize La-N-C-800℃.Adsorption kinetics,adsorption thermodynamics,initial concentrations,pH,and ions competition were investigated using La-N-C-800℃for fluoride *** addition,density functional theory was applied to evaluate the function of *** nitrogen atoms were added,the density of states,partial density of states,populations,and different orbits of charge were calculated to discover deep *** strengthened the carbon structure and La_(2)O_(3)structure to remove *** addition,nitrogen can also act as an adsorption site in the carbon *** results provide design ideas for improving the performance of adsorbent materials by doping elements.

关键词： Capacitive deionization Fluoride La-MOFs Doping nitrogen

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Strong,tough,and thermally conductive nacre-inspired boron nitride nanosheet/epoxy layered nanocomposites

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Nano Research 2024年第2期17卷 820-828页

作者： Huagao Wang Rongjian Lu Lei Li Cheng Liang jia yan Rui Liang Guoxing Sun Lei jiang Qunfeng Cheng School of Chemistry Key Laboratory of Bio-inspired Smart Interfacial Science and Technology of Ministry of EducationBeihang UniversityBeijing 100191China School of Chemistry and Materials Science University of Science and Technology of ChinaHefei 230026China Suzhou Institute for Advanced Research University of Science and Technology of ChinaSuzhou 215123China Department of Stomatology Fifth Medical CenterChinese PLA General HospitalBeijing 100039China Department of Engineering Science Faculty of Innovation EngineeringMacao University of Science and TechnologyAvenida Wai LongTaipaMacao 999078 China Joint Key Laboratory of the Ministry of Education Institute of Applied Physics and Materials EngineeringUniversity of MacaoAvenida da UniversidadeTaipaMacao 999078China Institute of Energy Materials Science(IEMS) University of Shanghai for Science and TechnologyShanghai 200093China

Thermally conductive polymer nanocomposites integrated with lightweight,excellent flexural strength,and high fracture toughness(KIc)would be of great use in many ***,achieving all of these properties simultaneously remains a great *** by natural nacre,here we demonstrate a lightweight,strong,tough,and thermally conductive boron nitride nanosheet/epoxy layered(BNNEL)*** of the layered structure and enhancing the interfacial interactions through hydrogen bonding and Si–O–B covalent bonding,the resulting nacre-inspired BNNEL nanocomposites show high fracture toughness of~4.22 MPa·m^(1/2),which is 7 folds as high as pure ***,the BNNEL nanocomposites demonstrate sufficient flexural strength(~168.90 MPa,comparable to epoxy resin),while also being lightweight(~1.23 g/cm^(3)).Additionally,the BNNEL nanocomposites display a thermal conductivity(κ)of~0.47 W/(m·K)at low boron nitride nanosheet loading of 2.08 vol.%,which is 2.7 times higher than that of pure epoxy *** developed nacre-inspired strategy of layered structure design and interfacial enhancement provides an avenue for fabricating high mechanical properties and thermally conductive polymer nanocomposites.

关键词： nacre-inspiration nanocomposites flexural strength fracture toughness(KIc) thermal conductivity

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Access to Enantioenriched Allylic Alcohols via Peptide-Mimic Phosphonium Salt-Catalyzed Asymmetric Aerobic Hydroxylation

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Chinese Journal of Chemistry 2024年第17期42卷 2017-2022页

作者： Jixing Che Siqiang Fang Zanjiao Liu jiaja He jia-yan Zheng Fan Wang Tianli Wang Key Laboratory of Green Chemistry&Technology of Ministry of Education College of ChemistrySichuan University29 Wangjiang RoadChengduSichuan610064China Department of Chemistry National University of SingaporeScience Drive 3Singapore 117543Singapore

The development of catalytic asymmetric methods that enable access to value-added functionalities or structures,exemplified by allylic alcohols,is a highly interesting yet challenging topic from both academic and industrial ***,before recent advances in chemical catalysis,there were scarce protocols toward constructing enantioenriched tertiary allylic alcohol *** this context,peptide-mimic phosphonium salts were found to be highly efficient in catalytic asymmetricα-hydroxylation ofα,β-unsaturated and/orβ,Y-unsaturated compounds with satisfactory regio-and stereochemical outcomes(up to 97%yield and 95%ee).This methodology tolerates a broad array of substrates and thus provides an expeditious and unified platform for the assembly of enantioenriched tertiary allylic alcohols by avoiding the use of additional reductants and expensive metal ***,the power of this protocol is enlarged by simple conditions and the use of air as a source of hydroxyl functionality.

关键词： Asymmetric catalysis Peptide-mimic phosphonium salts Aerobic hydroxylation Enantioenrichedα-allylic alcohols lon pairs Oxygen Ketones

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Electromagnetic Performance Analysis of Variable Flux Memory Machines with Series-magnetic-circuit and Different Rotor Topologies

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CES Transactions on Electrical Machines and Systems 2024年第1期8卷 3-11页

作者： Qiang Wei Z.Q.Zhu yan jia jianghua Feng Shuying Guo Yifeng Li Shouzhi Feng Department of Electronic and Electrical Engineering The University of SheffieldSheffield S13JDU.K. IEEE the CRRC Zhuzhou Institute Company Ltd. Zhuzhou 412001China

In this paper,the electromagnetic performance of variable flux memory(VFM)machines with series-magnetic-circuit is investigated and compared for different rotor *** on a V-type VFM machine,five topologies with different interior permanent magnet(IPM)arrangements are evolved and optimized under same *** on two-dimensional(2-D)finite element(FE)method,their electromagnetic performance at magnetization and demagnetization states is *** reveals that the iron bridge and rotor lamination region between constant PM(CPM)and variable PM(VPM)play an important role in torque density and flux regulation(FR)***,the global efficiency can be improved in VFM machines by adjusting magnetization state(MS)under different operating conditions.

关键词： Memory machine Permanent magnet Rotor topologies Series magnetic circuit Variable flux

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Anisotropic swelling pressures of compacted GMZ bentonite infiltrated with salt solutions

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Journal of Rock Mechanics and Geotechnical Engineering 2024年第9期16卷 3772-3785页

作者： Jing Ma Yong-Gui Chen Ling-yan jia Wei-Min Ye Dong-Bei Wu Qiong Wang Department of Geotechnical Engineering College of Civil EngineeringTongji UniversityShanghai200092China State Key Laboratory of Disaster Reduction in Civil Engineering College of Civil EngineeringTongji UniversityShanghai200092China School of Chemical Science and Engineering Tongji UniversityShanghai200092China

In the high-level radioactive waste(HLW)deep geological repository,bentonite is compacted uniaxially,and then arranged vertically in engineered *** assembly scheme induces the initial anisotropy,and with hydration,it develops more evidently under chemical *** investigate the anisotropic swelling of compacted Gaomiaozi(GMZ)bentonite and the further response to saline effects,a series of constant-volume swelling pressure tests were *** showed that dry density enhanced the bentonite swelling and raised the final anisotropy,whereas saline inhibited the bentonite swelling but still promoted the final *** final anisotropy coefficient(ratio of radial to axial pressure)obeyed the Boltzmann sigmoid attenuation function,decreasing with concentration and dry density,converging to a minimum value of *** staged evolution of anisotropy coefficient was discovered,that saline inhibited the rise of the anisotropy coefficient(Dd)in the isotropic process greater than the valley(d1)in the anisotropic process,leading to the final anisotropy *** isotropic stage amplified the impact of soil structure rearrangement on the macro-swelling pressure ***,a new method for predicting swelling pressures of compacted bentonite was proposed,by expanding the equations of Gouy-Chapman theory with a dissipative wedge *** evolutionary function was constructed,revealing the correlation between the occurrence time and the pressure value due to the structure rearrangement and the former crystalline ***,a design reference for dry density was given,based on the chemical conditions around the pre-site in Beishan,*** anisotropy promoted by saline would cause a greater drop of radial pressure,making the previous threshold on axial swelling fail.

关键词： HLW deep geological repository Compacted GMZ bentonite Anisotropic swelling pressure Multi-scale structure Saline effect

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Effect of Low-temperature Imidization on Properties and Aggregation Structures of Polyimide Films with Different Rigidity

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Chinese Journal of Polymer Science 2024年第8期42卷 1134-1146页

作者： yan jia Lei Zhai Song Mo Yi Liu Li-Xin Liu Xin-Yu Du Min-Hui He Lin Fan Key Laboratory of Science and Technology on High-tech Polymer Materials Institute of ChemistryChinese Academy of SciencesBeijing 100190China School of Chemical Sciences University of Chinese Academy of SciencesBeijing 100049China

The traditional high-temperature preparation process of polyimide can cause many problems and limits the wider application in extreme *** important challenge to be solved urgently is the reduction of imidization *** this work,twelve kinds of polyimide films with different chain rigidity were prepared at low temperature of 200℃,in the absence or presence of imidazole used as the *** molecular rigidity and free volume were theoretically calculated,and relationship between structure and properties were systematically *** results show that imidization reaction under low temperatures is significantly affected by the rigidity of molecula r *** rigid structure of polyimide is not conducive to the low-temperature imidization,but this adverse effect can be eliminated by adding catalyst,resulting the notably increased imidization *** optical and thermal properties can be improved to a certain extent for the chemically catalyzed system,resulting in relatively higher heat resistance and thermal *** the mechanical performance could be determined by com plicating factors,greatly different from polyimide films prepa red by high temperature *** investigate aggregation structures of film s,the effect of chain rigidity and catalyst on the stacking or orientation of molecular chains was further *** wo rk can contribute to the understanding of chemically catalyzed imidization that is rarely reported in the existing research,and will provide guidance for the low-temperature preparation of high-performance polyimides.

关键词： Polyimide Imidization Catalyst Structure and properties Aggregation structures

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