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Soft coarse-grained particle model for particle-fluid systems

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Particuology 2024年第1期84卷 178-193页

作者： Yanhao Ye ji xu Wei Ge State Key Laboratory of Multiphase Complex Systems Institute of Process EngineeringChinese Academy of SciencesBeijing100190China School of Chemical Engineering University of Chinese Academy of SciencesBeijing100049China Innovation Academy for Green Manufacture Chinese Academy of SciencesBeijing100190China

By modeling a group of neighboring real particles as a single coarse-grained particle(CGP),discrete particle method(DPM)is now capable of simulating industrial-scale particle-fluid ***,a systematic approach to determine the CGP properties and develop their interaction models is still lacking,which casts uncertainty on the predictivity of the *** this study,collisions between predefined particle groups are analyzed to construct kernel functions for modeling the CGPs and then the model parameters are determined by equating the statistical properties of the CGPs and the real particles in the physical process *** approach is implemented for homogeneous cooling of granular gas,then demonstrated effective in simulating experimental fluidized beds.

关键词： Coarse-grain(CG) Discrete particle method(DPM) Fluidized bed Multi-scale simulation

Evolution of the high-field-side radiation belts during the neon seeding plasma discharge in EAST tokamak

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Chinese Physics B 2022年第10期31卷 458-466页

作者： ji-chan xu Liang Wang Guo-Sheng xu Yan-Min Duan Ling-Yi Meng Ke-Dong Li Fang Ding Rui-Rong Liang jian-Bin Liu EAST Team School of Mechanical Engineering Anhui University of Science&TechnologyHuainan 232001China Institute of Plasma Physics Chinese Academy of SciencesHefei 230031China

Divertor detachment achieved by injecting impurities or increasing density is always accompanied with various local radiation phenomena in the boundary or core plasma. This paper presents the formation and evolution of the high-field-side(HFS) radiation belts during the neon seeding plasma discharge in upper single null configuration with two directions of toroidal magnetic field in EAST tokamak. The neon mixed with deuterium seeding can induce the divertor detachment with strong radiation belts in the HFS scrape-off layer(SOL) region. With the increase of the radiation power, the plasma discharge will transit from H-mode to L-mode, and meanwhile the radiation belts move away from the near X-point to HFS SOL. When the radiation power is high enough, the radiation belts begin to move further to the other X-point along the HFS SOL, and even cause plasma disruption. The results indicate that the behavior of the radiation belts is related to the radiation power, plasma confinement performance and state of divertor detachment, which is useful for developing better feedback control methods to achieve high-performance radiative divertor operation mode.

关键词： high-field-side radiation belts neon seeding EAST

Gas–solid reactor optimization based on EMMS-DPM simulation and machine learning

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Particuology 2024年第6期89卷 131-143页

作者： Haolei Zhang Aiqi Zhu ji xu Wei Ge State Key Laboratory of Mesoscience and Engineering Institute of Process EngineeringChinese Academy of SciencesBeijing 100190China State Key Laboratory of Multiphase Complex Systems Institute of Process EngineeringChinese Academy of SciencesBeijing 100190China School of Chemical Engineering University of Chinese Academy of SciencesBeijing 100049China Innovation Academy for Green Manufacture Chinese Academy of SciencesBeijing 100190China

Design,scaling-up,and optimization of industrial reactors mainly depend on step-by-step experiments and engineering experience,which is usually time-consuming,high cost,and high *** numerical simulation can reproduce high resolution details of hydrodynamics,thermal transfer,and reaction process in reactors,it is still challenging for industrial reactors due to huge computational *** this study,by combining the numerical simulation and artificial intelligence(AI)technology of machine learning(ML),a method is proposed to efficiently predict and optimize the performance of industrial reactors.A gas–solid fluidization reactor for the methanol to olefins process is taken as an example.1500 cases under different conditions are simulated by the coarse-grain discrete particle method based on the Energy-Minimization Multi-Scale model,and thus,the reactor performance data set is *** develop an efficient reactor performance prediction model influenced by multiple factors,the ML method is established including the ensemble learning strategy and automatic hyperparameter optimization technique,which has better performance than the methods based on the artificial neural ***,the operating conditions for highest yield of ethylene and propylene or lowest pressure drop are searched with the particle swarm optimization algorithm due to its strength to solve non-linear optimization *** show that decreasing the methanol inflow rate and increasing the catalyst inventory can maximize the yield,while decreasing methanol the inflow rate and reducing the catalyst inventory can minimize the pressure *** two objectives are thus conflicting,and the practical operations need to be compromised under different circumstance.

关键词： Discrete particle method Artificial intelligence Machine learning Particle swarm optimization Industrial reactor optimization

3D coarse-grained DPM simulation of the MIP reaction-regeneration loop

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Particuology 2024年第6期89卷 57-66页

作者： Yanhao Ye Shuai Zhang ji xu Wei Ge State Key Laboratory of Mesoscience and Engineering(formerly State Key Laboratory of Multiphase Complex Systems) Institute of Process EngineeringChinese Academy of SciencesBeijing100190China School of Chemical Engineering University of Chinese Academy of SciencesBeijing100049China

The reactor-regenerator loop is the core facility of the maximizing iso-paraffin(MIP)*** the discrete particle method(DPM)simulation can provide detailed information at the particle scale,it has been unable to simulate such a complex loop system due to limitations of coarse-grained(CG)models,computing software,and *** this study,a newly proposed soft-shell CG-DPM model with a CG ratio of up to 800 is used to simulate a 3.5 Mt/a industrial-scale MIP reactor-regenerator *** solid fraction distribution obtained is found to agree well with in-situ *** properties including the distribution of solid fraction,gas and solid velocity,standard derivation of solid fraction with time,temporal distribution of the flow field,and particle residence time distribution are measured in the simulation,which are meaningful to better design and operate such systems in the future.

关键词： Discrete particle method Coarse-grain Maximizing iso-paraffins Full-loop Reaction-regeneration system

Cyclic Beam Direction of Arrival Estimation Method for Ship Propeller Noise

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Journal of Ocean University of China 2024年第4期23卷 883-896页

作者： ZHANG Xiaowei NIE Weihang xu ji YAN Yonghong The Key Laboratory of Speech Acoustics and Content Understanding Institute of AcousticsChinese Academy of SciencesBeijing 100190China The Key Laboratory of Speech Acoustics and Content Understanding Institute of AcousticsUniversity of Chinese Academy of SciencesBeijing 100049China The State Key Laboratory of Acoustics Institute of AcousticsChinese Academy of SciencesBeijing 100190China

In underwater acoustic applications,the conventional cyclic direction of arrival algorithm faces challenges,including a low signal-to-noise ratio and high bandwidth when compared with modulated *** response to these issues,this paper introduces a novel,robust,and broadband cyclic beamforming *** proposed method substitutes the conventional cyclic covariance matrix with the variance of the cyclic covariance matrix as its primary *** that the same frequency band shares a common steering vector,the new algorithm achieves superior detection performance for targets with specific modulation frequencies while suppressing interference signals and background *** results demonstrate a significant enhancement in the directibity index by 81%and 181%when compared with the traditional Capon beamforming algorithm and the traditional extended wideband spectral cyclic MUSIC(EWSCM)algorithm,***,the proposed algorithm substantially reduces computational complexity to 1/40th of that of the EWSCM algorithm,employing frequency band statistical averaging and covariance matrix variance.

关键词： cyclostationarity direction of arrival extended wideband spectral cyclic music cyclic covariance matrix

Influence of Incomplete Soil Plugs on Bearing Capacities of Bucket Foundations in Clay

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China Ocean Engineering 2024年第1期38卷 144-155页

作者： LI Hui-shan LIU Run YANG xu LIAN ji-jian State Key Laboratory of Hydraulic Engineering Intelligent Construction and Operation Tianjin UniversityTianjin 300072China School of Civil Engineering Tianjin UniversityTianjin 300072China Institute of Marine Energy and Intelligent Construction Tianjin University of TechnologyTianjin 300384China

Due to the uneven seabed and heaving of soil during pumping,incomplete soil plugs may occur during the installation of bucket foundations,and the impacts on the bearing capacities of bucket foundations need to be *** this paper,the contact ratio(the ratio of the top diameter of the soil plug to the diameter of the bucket)and the soil plug ratio(the ratio of the soil heave height to the skirt height)are defined to describe the shape and size of the incomplete soil ***,finite element models are established to investigate the bearing capacities of bucket foundations with incomplete soil plugs and the influences of the contact ratios,and the soil plug ratios on the bearing capacities are *** results show that the vertical bearing capacity of bucket foundations in homogeneous soil continuously improves with the increase of the contact ***,in normally consolidated soil,the vertical bearing capacity barely changes when the contact ratio is smaller than 0.75,while the bearing capacity suddenly increases when the contact ratio increases to 1 due to the change of failure *** contact ratio hardly affects the horizontal bearing capacity of bucket ***,the moment bearing capacity improves with the increase of the contact ratio for small aspect ratios,but hardly varies with increasing contact ratio for aspect ratios larger than ***,the reduction coefficient method is proposed based on this analysis to calculate the bearing capacities of bucket foundations considering the influence of incomplete soil *** comparison results show that the proposed reduction coefficient method can be used to evaluate the influences of incomplete soil plug on the bearing capacities of bucket foundations.

关键词： bucket foundation incomplete soil plug uniaxial bearing capacity contact ratio soil plug ratio

Facile synthesis of hierarchical NaX zeolite from natural kaolinite for efficient Knoevenagel condensation

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Chinese Journal of Chemical Engineering 2024年第1期65卷 75-84页

作者： Wen Xiao Peng Dong chan Wang jingdong xu Tiesen Li Haibo Zhu Tinghai Wang Renwei xu Yuanyuan Yue National Engineering Research Center of Chemical Fertilizer Catalyst College of Chemical EngineeringFuzhou UniversityFuzhou 350108China Qingyuan Innovation Laboratory Quanzhou 362801China Sinochem Quanzhou Energy Technology Co. Ltd.Quanzhou 362000China

Zeolite catalysts have found extensive applications in the synthesis of various fine ***,the micropores of zeolites impose diffusion limitations on bulky molecules,greatly reducing the catalytic ***,we explore an economic and environmentally friendly method for synthesizing hierarchical NaX zeolite that exhibits improved catalytic performance in the Knoevenagel condensation reaction for producing the useful fine chemical *** synthesis was achieved via a low-temperature activation of kaolinite and subsequent in-situ transformation strategy without any template or *** characterizations reveal that the synthesized NaX zeolite has both intercrystalline and intra-crystalline mesopores,smaller crystal size,and larger external specific surface area compared to commercial NaX *** mechanism investigations show that the inter-crystalline mesopores are generated by stacking smaller crystals formed from in-situ crystallization of the depolymerized kaolinite,and the intra-crystalline mesopores are inherited from the pores in the depolymerized *** synthesis strategy provides an energy-saving and effective way to construct hierarchical zeolites,which may gain wide applications in fine chemical manufacturing.

关键词： Hierarchical NaX zeolite Template-free synthesis Natural kaolinite Knoevenagel condensation

Catalytically generated noncovalent ammonium dienolate:a versatile platform for the development of organocatalytic asymmetric cascade reactions

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Science China Chemistry 2024年第8期67卷 2524-2546页

作者： Jun-Bing Lin Dong-Sheng ji Peng-Fei xu State Key Laboratory of Applied Organic Chemistry College of Chemistry and Chemical EngineeringLanzhou UniversityLanzhou 730000China Shaanxi Key Laboratory of Chemical Reaction Engineering College of Chemistry and Chemical EngineeringYan’an UniversityYan’an 716000China

Organocatalytic cascade reactions represent a powerful strategy for the rapid construction of complex chiral molecules with multiple stereocenters from simple substrates under mild conditions. The intriguing structural feature and diverse reactivity of catalytically generated dienolate species render them competent and versatile intermediates for the development of practical and valuable cascade reactions. Over the past years, a plethora of innovative and pioneering noncovalent ammonium dienolatemediated cascade reactions have been designed and implemented under the catalysis of chiral organocatalysts, making dienolate activation a general, robust, and complementary method for the functionalization of unsaturated carbonyl compounds and related substances. This review illustrates the recent advances in organocatalytic noncovalent ammonium dienolate-mediated cascade reactions(mainly from 2010 to 2023), including the cascade transformations of ammonium dienolates directly generated from unsaturated ketone/aldehyde, ester/lactone/azlactone, amide/lactam/pyrazolone/oxindole, and alkylidene nitrile compounds. The contents are arranged based on the reaction types of the ammonium dienolates, with an emphasis on cascade 2,5-, 3,5-, and 4,5-difunctionalizations of these intermediates. Furthermore, other cascade reactions involving the 1,3-, 2,3-, and even more complex 3,4,5-reactivities of ammonium dienolates were also discussed. The reaction pathway, reaction stereoinduction, and synthetic applications of the ammonium dienolate-mediated cascade reactions were highlighted throughout the article. As a stimulating and ever-growing research area, the organocatalytic noncovalent ammonium dienolate-mediated cascade reactions are expected to continue demonstrating their magic power for constructing chiral targets in the future and further expanding the boundaries of asymmetric catalysis.

关键词： organocatalysis asymmetric catalysis ammonium dienolate cascade reaction difunctionalization

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Dual in-situ observation of tribochemical and morphological evolution of single-layer WS_(2)and multi-layer WS_(2)/C coatings

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Friction 2024年第7期12卷 1580-1598页

作者： Yuzhen LIU Jae-Ho HAN Shusheng xu Young chan JUNG Dae-Eun KIM State Key Laboratory of Solid Lubrication Lanzhou Institute of Chemical PhysicsChinese Academy of SciencesLanzhou 730000China Department of Mechanical Engineering Yonsei UniversitySeoul03722Republic of Korea Shandong Laboratory of Advanced Materials and Green Manufacturing at Yantai Yantai 264000China Yantai Zhongke Research Institute of Advanced Materials and Green Chemical Engineering Yantai 264000China

The outstanding tribological performance of transition metal dichalcogenides(TMDs)is attributed to their unique sandwich microstructure and low interlayer shear *** advantageous structure allows TMDs to demonstrate exceptional friction reduction ***,the incorporation of TMDs and amorphous carbon(a-C)in multi-layer structures shows excellent potential for further enhancing tribological and anti-oxidation *** carbon,known for its high ductility,chemical inertness,and excellent wear resistance,significantly contributes to the overall performance of these multi-layer *** gain an in-depth understanding of the tribological mechanism and evolution of TMDs’multi-layer coatings,a dual in-situ analysis was carried out using a tribometer equipped with a 3D laser microscope and a Raman *** innovative approach allowed for a comprehensive evolution of the tribological,topographical,and tribochemical characteristics of both single-layer WS_(2)and multi-layer WS_(2)/C coatings in real *** findings from the dual in-situ tribotest revealed distinct failure characteristics between the single-layer WS_(2)coating and the multi-layer WS_(2)/C *** single-layer WS_(2)coating predominantly experienced failure due to mechanical removal,whereas a combination of mechanical removal and tribochemistry primarily influenced the failure of the multi-layer WS_(2)/C *** tribological evolution process of these two coatings can be classified into four stages on the basis of their tribological behavior:the running-in stage,stable friction stage,re-deposition stage,and lubrication failure *** stage represents a distinct phase in the tribological behavior of the coatings and contributes to our understanding of their behavior during sliding.

关键词： In-situ analysis multi-layer coating tribology tribochemistry