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Fully resolved simulations of viscoelastic suspensions by an efficient immersed boundary-lattice Boltzmann method

Particuology 2023年第4期75卷 26-49页

作者： Shenxu Qin Maoqiang Jiang Kuang Ma Jin Su Zhaohui Liu State Key Laboratory of Coal Combustion School of Energy and Power EngineeringHuazhong University of Science and TechnologyWuhan430074China School of Science Xian Polytechnic UniversityXi'an710048China

An efficient immersed boundary-lattice Boltzmann method(IB-LBM)is proposed for fully resolved simulations of suspended solid particles in viscoelastic flows.Stress LBM based on Giesekus and Oldroyd-B constitutive equation are used to model the viscoelastic stress tensor.A boundary thickening-based direct forcing IB method is adopted to solve the particle-fluid interactions with high accuracy for non-slip boundary conditions.A universal law is proposed to determine the diffusivity constant in a viscoelastic LBM model to balance the numerical accuracy and stability over a wide range of computa-tional parameters.An asynchronous calculation strategy is adopted to further improve the computing efficiency.The method was firstly applicated to the simulation of sedimentation of a single particle and a pair of particles after good validations in cases of the flow past a fixed cylinder and particle migration in a Couette flow against FEM and FVM methods.The determination of the asynchronous calculation strategy and the effect of viscoelastic stress distribution on the settling behaviors of one and two particles are revealed.subsequently,504 particles settling in a closed cavity was simulated and the phenomenon that the viscoelastic stress stabilizing the Rayleigh-Taylor instabilities was observed.At last,simulations of a dense flow involving 11001 particles,the largest number of particles to date,were performed to investigate the instability behavior induced by elastic effect under hydrodynamic interactions in a viscoelastic fluid.The elasticity-induced ordering of the particle structures and fluid bubble structures in this dense flow is revealed for the first time.These simulations demonstrate the capability and prospects of the present method for aid in understanding the complex behaviors of viscoelastic particle suspensions.

关键词： Fullyresolved simulation Lattice Boltzmann method Immersed boundary method Viscoelastic suspension Particle sedimentation

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Effects of thinning on the understory light environment of different stands and the photosynthetic performance and growth of the reforestation species Phoebe bournei

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Journal of Forestry Research 2024年第1期35卷 12-28页

作者： Shicheng su Nianqing jin Xiaoli Wei College of Forestry Guizhou UniversityGuiyang 550025People’s Republic of China Institute for Forest Resources and Environment of Guizhou Guizhou UniversityGuiyang 550025People’s Republic of China

Light levels determine regeneration in stands and a key concern is how to regulate the light environment of different stand types to the requirements of the understory.In this study,we selected three stands typical in south China(a Cryptomeria japonica plantation,a Quercus acutissima plantation,and a mixed stand of both)and three thinning intensities to determine the best understory light environ-ment for 3-year-old Phoebe bournei seedlings.The canopy structure,understory light environment,and photosynthe-sis and growth indicators were assessed following thin-ning.Thinning improved canopy structure and understory light availability of each stand;species composition was the reason for differences in the understory light environ-ment.Under the same thinning intensity,the mixed stand had the greatest light radiation and most balanced spectral composition.P.bournei photosynthesis and growth were closely related to the light environment;all three stands required heavy thinning to create an effective and sustained understory light environment.In a suitable understory light environment,the efficiency of light interception,absorption,and use by seedlings was enhanced,resulting in a higher carbon assimilation the main limiting factor was stomatal conductance.As a shade-avoidance signal,red/far-red radia-tion is a critical factor driving changes in photosynthesis and growth of P.bournei seedlings,and a reduction increased light absorption and use capacity and height:diameter ratios.The growth advantage transformed from diameter to height,enabling seedlings to access more light.Our findings suggest that the regeneration of shade-tolerant species such as P.bournei could be enhanced if a targeted approach to thinning based on stand type was adopted.

关键词： Thinning Understory light environment Phoebe bournei Photosynthetic performance Growth performance

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Electromyogram Based Personal Recognition Using Attention Mechanism for IoT Security

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Computers, Materials & Continua 2023年第11期77卷 1663-1678页

作者： Jin Su Kim sungbum Pan IT Research Institute Chosun UniversityGwang-Ju61452Korea

As Internet of Things(IoT)technology develops,integrating network functions into diverse equipment introduces new challenges,particularly in dealing with counterfeit issues.Over the past few decades,research efforts have focused on leveraging electromyogram(EMG)for personal recognition,aiming to address security concerns.However,obtaining consistent EMG signals from the same individual is inherently challenging,resulting in data irregularity issues and consequently decreasing the accuracy of personal recognition.Notably,conventional studies in EMG-based personal recognition have overlooked the issue of data irregularities.This paper proposes an innovative approach to personal recognition that combines a siamese fusion network with an auxiliary classifier,effectively mitigating the impact of data irregularities in EMG-based recognition.The proposed method employs empirical mode decomposition(EMD)to extract distinctive features.The model comprises two sub-networks designed to follow the siamese network architecture and a decision network integrated with the novel auxiliary classifier,specifically designed to address data irregularities.The two sub-networks sharing a weight calculate the compatibility function.The auxiliary classifier collaborates with a neural network to implement an attention mechanism.The attention mechanism using the auxiliary classifier solves the data irregularity problem by improving the importance of the EMG gesture section.Experimental results validated the efficacy of the proposed personal recognition method,achieving a remarkable 94.35%accuracy involving 100 subjects from the multisession CU_sEMG database(DB).This performance outperforms the existing approaches by 3%,employing auxiliary classifiers.Furthermore,an additional experiment yielded an improvement of over 0.85%of Ninapro DB,3%of CU_sEMG DB compared to the existing EMG-based recognition methods.Consequently,the proposed personal recognition using EMG proves to secure IoT devices,offering robustness against data irregularities.

关键词： Personal recognition electromyogram siamese network auxiliary classifier

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Lower Bounds of Distance Laplacian Spectral Radii of n-Vertex Graphs in Terms of Fractional Matching Number

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Journal of the Operations Research Society of China 2023年第1期11卷 189-196页

作者： jin Yan Yan Liu Xue-Li su School of Mathematical Sciences South China Normal UniversityGuangzhou510631GuangdongChina

A fractional matching of a graph G is a function f: E(G)→[0,1] such that for each vertex v, ∑eϵΓG(v)f(e)≤1.. The fractional matching number of G is the maximum value of ∑e∈E(G)f(e) over all fractional matchings f. Tian et al. (Linear Algebra Appl 506:579–587, 2016) determined the extremal graphs with minimum distance Laplacian spectral radius among n-vertex graphs with given matching number. However, a natural problem is left open: among all n-vertex graphs with given fractional matching number, how about the lower bound of their distance Laplacian spectral radii and which graphs minimize the distance Laplacian spectral radii? In this paper, we solve these problems completely.

关键词： Distance Laplacian Spectral radius Fractional matching number

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A novel model of the carbon cycle in the Cambrian ocean

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Science China Earth Sciences 2024年第6期67卷 1759-1778页

作者： Huajian WANG Shuichang ZHANG Xiaomei WANG Jin Su Yuntao YE Yuke LIU Key Laboratory of Petroleum Geochemistry Research Institute of Petroleum Exploration and DevelopmentChina National Petroleum CorporationBeijing 100083China Key Laboratory of Orogenic Belts and Crustal Evolution School of Earth and Space SciencesPeking UniversityBeijing 100871China

The classic model of the carbon cycle suggests that the extensive burial of ^(12)C-enriched organic carbon leads to a positive carbon isotope(δ^(13)C)excursion(CIE),while massive oxidation of organic carbon results in a negative CIE.However,global events such as the BAsal Cambrian Carbon isotope Excursion(BACE)and the Steptoean Positive Carbon Isotope Excursion(SPICE)are global negative and positive δ^(13)C excursions,respectively,and they also exhibit significant organic carbon burial anomalies,displaying decoupling between carbon isotope anomalies and organic carbon burial.Based on the analyses of the Cambrian carbon cycle and paleoceanographic evolution records from well Tadong2 in the Tarim Basin,we propose a novel model of the carbon cycle in the Cambrian ocean that incorporates oceanic dissolved organic carbon(DOC).Our findings are as follows.(1)The Cambrian ocean maintained substantial DOC reservoirs,which were regulated by ocean currents and paleo-redox conditions and exerted significant influence on the oceanic carbon cycle.(2)The oxidation of the oceanic DOC reservoirs during the early Cambrian led to the BACE and the Asian Phenomenon of the Cambrian petroleum systems,while the expansion of the oceanic DOC reservoirs during the SPICE resulted in a global positive δ^(13)C excursion and the absence of significant organic carbon burial.(3)The deep-basin sedimentary environment in the eastern depression of the Tarim Basin may have fostered the development of organic-rich black shales during the Furongian Series,corresponding to organic carbon burial during the SPICE and representing potential prospects for ultra-deep oil and gas exploration.Future research should focus on the formation mechanism,reserve scale,and influencing factors of the oceanic DOC reservoirs,as well as their resource and environmental effects.It is expected that new breakthroughs will be made in the fields of Earth system science and oil and gas exploration.

关键词： Carbon isotope Organic carbon BACE SPICE Dissolved organic carbon Climate change Black shale

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Simultaneously enhanced efficiency and ambient stability of inorganic perovskite solar cells by employing tetramethylammonium chloride additive in CsPbI2Br

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Journal of Materials Science & Technology 2022年第7期102卷 224-231页

作者： In su jin Bhaskar Parida Jae Woong Jung Department of Advanced Materials Engineering for Information and Electronics Kyung Hee University1732 Deogyeong-daeroGiheung-guYongin-siGyeonggi-do 446-701Republic of Korea Integrated Education Institute for Frontier Materials(BK21 Four) Kyung Hee University1732 Deogyeong-daeroGiheung-guYongin-siGyeonggi-do 446-701Republic of Korea

Although all-inorganic perovskites possess suitable bandgap and thermal stability for photovoltaic ap-plications,the unstable film morphologies,and poor moisture stabilities lag behind the organic-inorganic hybrid counterparts.Herein,we demonstrate that high qualityα-CsPbI_(2 ) Br films with improved phase sta-bility,high crystallinity,and pinhole-free film morphology was achieved by employing tetramethylammo-nium chloride(TMACl)as an additive.As a result,the TMACl-added CsPbI_(2) Br films exhibited high power conversion efficiency of 14.12%with an open-circuit voltage of 1.19 V,a short-circuit current density of 15.08 mA/cm^(2),and a fill factor of 0.78.More importantly,the TMACl addition imparts hydrophobicity to the film surface of CsPbI_(2) Br,which delivered excellent stability up to 30 days in the ambient condition and thermal stability at 85℃ for 156 h,respectively.Moreover,the TMACl-added device also exhibited excellent PCE of 27.16%under indoor light source(1000 lux),which presents a promising approach for designing stable but high performance all-inorganic perovskite solar cells.

关键词： Inorganic perovskite solar cells CsPbI2Br Additive Tetramethylammonium chloride Efficiency

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Efficient heavy metal recycling and water reuse from industrial wastewater using new reusable and inexpensive polyphenylene sulfide derivatives

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Chinese Journal of Chemical Engineering 2023年第6期58卷 89-102页

作者： Chaozhi Zhang Qianqian Shen Yanxiao su Ruihua jin School of Environmental Science and Engineering Nanjing University of Information Science&TechnologyNanjing 210044China School of Chemistry and Materials Science Nanjing University of Information Science&TechnologyNanjing 210044China

Heavy metal(HM)pollution is a serious environment problem.Recovering HM from industrial wastewater by efficient adsorbents is a sustainable method due to recycling HM and acquiring reusable water.However,popular efficient adsorbents are usually expensive or non-reusable.In this paper,methods of efficient HM recycling and water reuse from industrial wastewater were developed using efficient adsorbents,new polyphenylene sulfide derivatives,which are recyclable and stable in an acidic,alkaline or oxidative aqueous solution.Moreover,they can efficiently and quickly adsorb HM ions.The maximum adsorption capacities of these adsorbents for HM ions are at the range from 51.3-184.2 mg·g^(-1).The adsorption equilibrium times of them for HM ions are at the range from 10 to 80 min.Therefore,this paper suggests sustainable methods of HM recovery and water reuse from industrial wastewater.

关键词： Lead-acid wastewater Inexpensive engineering plastic Recycling Reusable water sustainable method

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Stochastic and Distributed Optimal Energy Management of Active Distribution Networks Within Integrated Office Buildings

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CSEE Journal of Power and Energy Systems 2024年第2期10卷 504-517页

作者： Zening Li su su Xiaolong jin Mingchao Xia Qifang Chen Koji Yamashita National Active Distribution Network Technology Research Center Beijing Jiaotong UniversityBeijing 100044China Key Laboratory of Smart Grid of Ministry of Education Tianjin UniversityTianjin 300072China Electrical and Computer Engineering University of California RiversideCA92521USA.

This paper proposes a stochastic and distributed optimal energy management approach for active distribution networks(ADNs)within office buildings.The proposed approach aims at scheduling office buildings fitted with heating ventilation and air conditioning(HVAC)systems,and electric vehicle(EV)charging piles,to participate in the ADN optimization.First,an energy management approach for the ADN with aggregated office buildings is proposed.And the ADN optimization model is formulated considering the detailed building thermal dynamics and the mobile behaviors of workers.Then,to consider un-certainties of photovoltaic(PV)power,scenario-based stochastic programming is integrated into the ADN optimization model.To further realize the stochastic energy management of the ADN within office buildings in a distributed manner,the alternating direction method of multipliers(ADMM)is used to solve the ADN optimization model.The original ADN optimization problem is divided into the network-side and the building-side sub-problems to effectively protect the privacy of the ADN and the office buildings.Finally,the ADN optimization model incorporating office buildings is validated in the winter by numerical studies.In addition,the impacts of comfort temperature range and expected state of charge(SOC)at departure are analyzed.Index Terms—ADN,EV,HVAC system,Office building,Stochastic and distributed energy management.

关键词： ADN EV HVAC system Office building Stochastic and distributed energy management

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PPP models and performances from single-to quad-frequency BDS observations

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Satellite Navigation 2020年第1期1卷 179-191页

作者： Shuanggen jin Ke su Shanghai Astronomical Observatory Chinese Academy of SciencesShanghai 200030China School of Remote Sensing and Geomatics Engineering Nanjing University of Information Science and TechnologyNanjing 210044China Jiangsu Engineering Center for Collaborative Navigation/Positioning and Smart Applications Nanjing 210044China University of Chinese Academy of Sciences Beijing 100049China

Nowadays,China BeiDou Navigation Satellite System(BDS)has been developed well and provided global services with highly precise positioning,navigation and timing(PNT)as well as unique short-message communication,particularly global system(BDS-3)with higher precision multi-frequency signals.The precise point positioning(PPP)can provide the precise position,receiver clock,and zenith tropospheric delay(ZTD)with a stand-alone receiver compared to the traditional double differenced relative positioning mode,which has been widely used in PNT,geodesy,meteorology and so on.However,it has a lot of challenges for multi-frequency BDS PPP with different strategies and more unknown parameters.In this paper,the detailed PPP models using the single-,dual-,triple-,and quad-frequency BDS observations are presented and evaluated.Firstly,BDS system and PPP method are introduced.Secondly,the stochastic models of time delay bias in BDS-2/BDS-3 PPP including the neglection,random constant,random walk and white noise are presented.Then,three single-frequency,four dual-frequency,four triple-frequency and four quad-frequency BDS PPP models are provided.Finally,the BDS PPP models progress and performances including theoretical comparison of the models,positioning performances,precise time and frequency transfer,ZTD,inter-frequency bias(IFB)and differential code bias(DCB)are presented and evaluated as well as future challenges.The results show that the multi-frequency BDS observations will greatly improve the PPP performances.

关键词： BDS GNSS PPP IFB ZTD DCB

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Cardiac resident macrophages: Spatiotemporal distribution, development, physiological functions, and their translational potential on cardiac diseases

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Acta Pharmaceutica Sinica B 2024年第4期14卷 1483-1493页

作者： jing jin Yurou Wang Yueqin Liu subrata Chakrabarti Zhaoliang su International Genome Center Jiangsu UniversityZhenjiang 212013China Institute for Medical Immunology Jiangsu UniversityZhenjiang 212013China Center Laboratory the Fourth People's Hospital of ZhenjiangZhenjiang 212008China Department of Pathology and Laboratory Medicine Western UniversityLondonOntario N6A 5C1Canada

Cardiac resident macrophages (CRMs) are the main population of cardiac immune cells. The role of these cells in regeneration, functional remodeling, and repair after cardiac injury is always the focus of research. However, in recent years, their dynamic changes and contributions in physiological states have a significant attention. CRMs have specific phenotypes and functions in different cardiac chambers or locations of the heart and at different stages. They further show specific differentiation and development processes. The present review will summarize the new progress about the spatiotemporal distribution, potential developmental regulation, and their roles in cardiac development and aging as well as the translational potential of CRMs on cardiac diseases. Of course, the research tools for CRMs, their respective advantages and disadvantages, and key issues on CRMs will further be discussed.

关键词： Cardiac resident macrophages Spatiotemporal distribution Cardiac development Cardiac homeostasis Physiological functions Research tools Clinical translation Transcriptional characteristics

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