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Study on a semi-resolved CFD-DEM method for rod-like particles in a gas-solid fluidized bed

Particuology 2024年第4期87卷 20-36页

作者： Liping He Zhengxian Liu Yongzhi Zhao Department of Mechanics School of Mechanical EngineeringTianjin UniversityTianjin300350China Insttute of Process quipment College of Energy EngineeringZhejiang UniversityHangzhou30027China

Based on a semi-resolved CFD-DEM coupling method,this study proposed a method that uses the minimum distance between the fluid grid and the particle boundary as a reference value to determine the degree of influence of the target fluid grid on the particle's drag force.A fluidized bed of rod-like particles was chosen as a typical case to investigate the effect of different fluid grid scales on various fluidized bed characteristic *** calculation performance of the semi-resolved and unre-solved CFD-DEM coupling algorithm on key fluidized bed characteristic parameters such as average pressure drop,particle frequency distribution with bed height,and particle orientation distribution were *** was found that the semi-resolved CFD-DEM coupling algorithm gradually obtained results with higher consistency with decreasing fluid grid scale for key parameters such as particle frequency distribution with bed height,particle orientation distribution,and time-history mixing index,exhibiting a phenomenon similar to grid independence in fluid *** comparing with experimental results,it was verified that the semi-resolved CFD-DEM coupling algorithm can be applied to simulate multi-granular gas-solid systems with fluid grid scales equivalent to particle *** algorithm solves the limitation of fluid grid scale in the unresolved CFD-DEM coupling framework and improves the grid adaptability of the CFD-DEM coupling simulation algorithm.

关键词： CFD-DEM Semi-resolved method Fluid-solid flow Non-spherical particle Fluidized bed

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Modeling trends in multicomponent gas membrane separation process: a review

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Journal of engineering and Applied Science 2025年第1期72卷 1-19页

作者： Aninwede, Chukwuebuka Kratky, Lukas Department of Process Engineering Faculty of Mechanical Engineering Czech Technical University in Prague Technicka 4 Prague160 00 Czech Republic

The significance of mathematical modeling in comprehending engineering problems and predicting solutions, as well as the operational framework of any mechanical system or process, cannot be overstated. In this study, a comprehensive overview of standard mass transfer approaches and trends in mathematical modeling used by different authors in the literatures for efficient prediction of permeability, selectivity, and flux rate through hollow fiber membrane modules for multicomponent gas separation has been reviewed. This article categorizes different modeling approaches into three categories based on Fick’s law of diffusion, which stipulates that the basis of mass transfer across any membrane system is concentration or partial pressure difference. Standard mass transfer mechanisms in porous and nonporous membranes were also discussed in detail to elucidate the significance of the interrelationship between permeability and selectivity in membrane separation processes. Integral mass balance models in one-dimensional plane are the most prevalent and appealing models in many literatures for predicting membrane selectivity, permeability, mass flux, and gas recovery rate due to their simplicity of development and limited number of computations. Nevertheless, this review places greater emphasis on the potential of a fully developed conceptual dimensionless modeling approach in setting future standards in mathematical modeling of CO2 capture with membrane technology. © The Author(s) 2025.

关键词： Forecasting

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Electrochemical performance of NiAl-activated cathode for green hydrogen production

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Chinese Journal of Chemical engineering 2024年第11期75卷 290-298页

作者： Sofiane Latreche Naïma Boutarek-Zaourar Ismail Bencherifa Faouzi Messaoud Mohamed Trari Materials Technology Laboratory Faculty of Mechanical Engineering and Process EngineeringUSTHBAlgiersAlgeria Department of Mechanical Engineering University of BiskraB.P.14507000 BiskraAlgeria Faculty of Chemistry USTHBBP 3216111 AlgiersAlgeria

The current study presents for the first time the preparation of a NiAl(68%(mass)Ni)intermetallic compound through the induction heating technique as a cathode for alkaline water *** high-purity target was confirmed by X-ray diffraction and scanning electron microscopy combined with energy dispersive X-ray *** chemical activation of Al from the NiAl electrode was achieved in a 25%NaOH solution at 353 K for 72 *** performance and stability tests in a 1 mol·L^(-1)KOH solution at 298 K demonstrated that the enhancement of the hydrogen evolution reactionwas 13 times higher in the activated NiAl electrode than in the non-activated NiAl *** addition,the electrochemical tests showed that the activated NiAl electrode exhibited the best hydrogen evolution reaction *** on the findings,it is believed that the induction heating technique is a promising route for preparing a highly active and cost-effective NiAl electrode for green hydrogen production.

关键词： NiAl intermetallic compound Ni-Raney Hydrogen evolution reaction Electro-catalytic activity Water electrolysis Electrochemical impedance spectroscopy

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Entropic Multi-Relaxation-Time Lattice Boltzmann Model for Large Density Ratio Two-Phase Flows

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Communications in Computational Physics 2023年第1期33卷 39-56页

作者： S.A.Hosseini B.Dorschner I.V.Karlin Department of Mechanical and Process Engineering ETH Zurich8092 ZurichSwitzerland

We propose a multiple relaxation time entropic realization of a recent twophase flow lattice Boltzmann model[***,***,and ***,Journal of Fluid Mechanics 953(2022)].While the original model with a single relaxation time allows us to reach large density ratios,it is limited in terms of stability with respect to non-dimensional viscosity and *** showthat the entropic multiple relaxation time model extends the stability limits of the model significantly,which allows us to reach larger Reynolds numbers for a given grid *** thermodynamic properties of the solver,using the Peng-Robinson equation of state,are studied first using simple ***-existence densities and temperature scaling of both the interface thickness and the surface tension are shown to agree well with *** model is then used to simulate the impact of a drop onto a thin liquid film with density and viscosity ratios matching those of water and air both in two and three *** results are in very good agreement with theoretically predicted scaling laws and experimental data.

关键词： Lattice Boltzmann method two-phase flows entropic multiple relaxation time

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The optimum discharge pressure of CO2-based refrigeration cycles operating under subcritical and transcritical conditions

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International Journal of Ambient Energy 2023年第1期44卷 1232-1242页

作者： Sharma, Devendra Kumar Hazarika, Mihir Mouchum Ramgopal, Maddali Department of Mechanical Engineering IIT Kharagpur Kharagpur India Department of Energy and Process Engineering NTNU Trondheim Norway

In the present study a simple, single stage CO2-based vapour compression refrigeration system cycle, consisting of a compressor, condenser/gas cooler, expansion valve and an evaporator is studied to find the effect of various design and operating parameters on the separation of optimal pressure line from saturation and pseudocritical pressure lines. The results show that the optimum discharge pressure line deviates markedly from the pseudocritical pressure line for the transcritical cycle. In the subcritical cycle, away from the critical point, the optimum discharge pressure is the same as the saturation pressure corresponding to the condenser exit temperature. However, near the critical point, the optimum discharge pressure is different from the saturation pressure. With the help of this study, an optimum discharge pressure equation is developed which is found to be valid for subcritical as well as transcritical CO2 cycles. Highlights: The Operation of CO2-based refrigeration cycle across a critical point is *** discharge pressure for sub-and transcritical conditions is *** effects of evaporator temperature and compressor efficiency are studied.A correlation for optimum discharge pressure valid for sub- and transcritical cycles is suggested. © 2023 Informa UK Limited, trading as Taylor & Francis Group.

关键词： Carbon dioxide

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Light-harvesting properties of photocatalyst supports-no photon left behind

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npj Computational Materials 2024年第1期10卷 703-713页

作者： Athanasios A.Tountas Anselm Dreher Wenjie Zhou Abhinav Mohan Nazir P.Kherani Geoffrey A.Ozin Mohini M.Sain University of Toronto Department of Chemical Engineering and Applied ChemistryTorontoONCanada Karlsruhe Institute of Technology Institute for Micro Process Engineering(IMVT)KarlsruheGermany California Institute of Technology Department of Mechanical and Civil EngineeringPasadenaCA91106USA University of Toronto Department of Mechanical and Industrial Engineering TorontoTorontoONCanada University of Toronto Department of Materials Science and EngineeringTorontoONCanada University of Toronto Department of ChemistryTorontoONCanada

In this work,we set out to elucidate the light-harvesting properties of various random and ordered photocatalyst supports(PSs)with different macropore *** accomplish this,we propose two studies of increasing relevance,enabled by computed tomography(CT)reconstructions and raytracing COMSOL Multiphysics simulations:(a)a 360-degree light release study approximating a PS situated within a compound parabolic concentrator(CPC)or cylindrical LED reactor with open ends;and(b)the same systemas before but with closed *** ordered geometry is of interest,as it can be 3D printed at scale with a tailored morphology and porosity,and it can potentially be refined using machine learning models to optimize its light-harvesting *** will be shown,the local volumetric light absorption(LVLA)data suggests that an ordered PSwith amore open pore interior and a smaller pore exterior would begin to approach the more isophotonic light-harvesting properties of random PSs.

关键词： properties catalyst ordered

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System dynamics costing model for the capital cost estimation of electric vehicle batteries refurbishing facility

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International Journal of Industrial and Systems engineering 2024年第3期48卷 377-404页

作者： Kalwar, Muhammad Ahmed Wassan, Asif Nawaz Sheikh, Waleed Ahmed Khan, Muhammad Ali Mari, Hussain Bux Industrial Engineering and Management Faculty of Mechanical Process and Earth Engineering Mehran University of Engineering and Technology Jamshoro Sindh76062 Pakistan Department of Mechanical and Energy Systems Engineering University of Bradford United Kingdom Khairpur Mirs Sindh Pakistan

Electric vehicles (EVs) are considered sustainable vehicles due to low carbon emissions. Lithium-ion batteries (LIBs) are expensive electrical vehicle batteries (EVBs) due to their expensive rare raw materials, i.e., lithium, nickel and cobalt. With increased production of EVs, authors warned of the expected huge quantity of dismantled EVBs shortly and so explored their reusability. An in-depth review is conducted, and system dynamics (SD) model was developed in Anylogic whereas origin was used for graphs. The capital costs dynamics of the refurbishing facility were evaluated and the model was validated and initialised. The analysis was conducted in three sales scenarios:1) locally;2) regionally;3) nationally. This paper provides a framework for entrepreneurs. The results indicated scenario-2 as more suitable with a maximum return on investment (ROI) (80.26%) and minimum payback period (626 weeks). Therefore, it is concluded that it would be feasible for the refurbishing facility to operate regionally rather than locally/nationally. © 2024 Inderscience Enterprises Ltd.

关键词： batteries capital cost carbon carbon emissions electric vehicle batteries electric vehicles environment EVs infrastructural cost LIBs lithium-ion batteries recycling refurbished EVBs refurbishment retired EVs sustainability system dynamics

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Carbon Nanotube Resonator Research 38

Carbon Nanotube Resonator Research

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38th IEEE International Conference on Micro Electro mechanical Systems, MEMS 2025

作者： Vollmann, Morten Eth Zürich Department of Mechanical and Process Engineering Switzerland

ISBN: (纸本)9798331508890

Since the first demonstration of tunable carbon nanotube (CNT) resonators in the early 2000's there has been a lot of research in fabrication, modelling, characterization, and potential use cases of CNT resonators. In almost all publications on this topic the outstanding potential of CNTs is highlighted due to their unique material properties. The wide range of applications is often mentioned, however more than 20 years later, we don't have any real-world applications and are still far away from them. In this paper, we want to review the achievements in the field of tunable CNT resonators and discuss the next necessary steps to bring these devices into the real world. © 2025 IEEE.

关键词： Yarn

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Event-triggered sliding mode control of linear repetitive processes and its application in metal rolling process

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Science China(Information Sciences) 2024年第3期67卷 167-181页

作者： Xinyu LV Yugang NIU James LAM Key Laboratory of Smart Manufacturing in Energy Chemical Process (East China University of Science and Technology) Ministry of Education Department of Mechanical Engineering The University of Hong Kong

This paper investigates the design problem of a sliding mode controller for linear repetitive processes(LRPs) with a finite pass length on each pass. Under limited communication resources, an eventtriggered mechanism is implemented from the sensors to the controller, whose triggered sequence is consistent with the evolution direction of LRPs. To periodically orchestrate communication between the controller and actuator, a round-robin scheduling mechanism is established based on the pass length. A sliding function involving the state and pass profile is constructed, and the sliding mode controller is designed using triggered states and pass profile signals. Feasible controller gains are attained to ensure the stability of the resultant closed-loop system. Finally, the proposed strategy is implemented for a multi-roll metal rolling process.

关键词： event-triggered mechanism linear repetitive processes metal rolling process round-robin scheduling sliding mode control

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Magnetic Field-Based Reward Shaping for Goal-Conditioned Reinforcement Learning

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IEEE/CAA Journal of Automatica Sinica 2023年第12期10卷 2233-2247页

作者： Hongyu Ding Yuanze Tang Qing Wu Bo Wang Chunlin Chen Zhi Wang the Department of Control Science and Intelligence Engineering School of Management and EngineeringNanjing UniversityNanjing 210093China the Department of Power Engineering and Process Machinery School of Mechanical and Power EngineeringEast China University of Science and TechnologyShanghai 200237China IEEE

Goal-conditioned reinforcement learning(RL)is an interesting extension of the traditional RL framework,where the dynamic environment and reward sparsity can cause conventional learning algorithms to *** shaping is a practical approach to improving sample efficiency by embedding human domain knowledge into the learning *** reward shaping methods for goal-conditioned RL are typically built on distance metrics with a linear and isotropic distribution,which may fail to provide sufficient information about the ever-changing environment with high *** paper proposes a novel magnetic field-based reward shaping(MFRS)method for goal-conditioned RL tasks with dynamic target and *** by the physical properties of magnets,we consider the target and obstacles as permanent magnets and establish the reward function according to the intensity values of the magnetic field generated by these *** nonlinear and anisotropic distribution of the magnetic field intensity can provide more accessible and conducive information about the optimization landscape,thus introducing a more sophisticated magnetic reward compared to the distance-based ***,we transform our magnetic reward to the form of potential-based reward shaping by learning a secondary potential function concurrently to ensure the optimal policy invariance of our *** results in both simulated and real-world robotic manipulation tasks demonstrate that MFRS outperforms relevant existing methods and effectively improves the sample efficiency of RL algorithms in goal-conditioned tasks with various dynamics of the target and obstacles.

关键词： Dynamic environments goal-conditioned reinforcement learning magnetic field reward shaping

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