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Deep learning to develop zero-equation based turbulence model for cFD simulations of the built environment

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Building Simulation 2024年第3期17卷 399-414页

作者： Giovanni calzolari Wei liu Division of Sustainable Buildings Department of Civil and Architectural EngineeringKTH Royal Institute of TechnologyBrinnelvägen 23Stockholm11428Sweden

This study aims to improve the accuracy and speed of predictions for thermal comfort and air quality in built environments by creating a coupled framework between computational fluid dynamics(cFD)simulations and deep learning *** coupling approach is showcased by the development of a data-driven turbulence *** new turbulence model is built using a deep learning neural network,whose mapping structure is based on a zero-equation turbulence model for built environment simulations,and is coupled with the cFD software OpenFOAM to create a hybrid *** neural network is a standard shallow multi-layer *** number of hidden layers and nodes per layer was optimized using Bayesan optimization *** framework is trained on an indoor environment case study,as well as tested on an indoor office simulation and an outdoor building array *** show that the deep learning based turbulence model is more robust and faster than traditional two-equation Reynolds average Navier-Stokes(RANS)turbulence models,while maintaining a similar level of *** model also outperforms the standard algebraic zero-equation model due to its superior ability to generalize to various flow *** some challenges,namely the mapping constraint,the limited training dataset size and the source of generation of training data,the hybrid framework demonstrates the viability of the coupling technique and serves as a starting point for future development of more reliable and advanced models.

关键词： neural networks computational fluid dynamics(cFD) turbulence model OpenFOAM

Hydrogen and nitrogen absorption properties of ce-added Zr_(2)(Fe_(1-x)Ni_(x)) alloys

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Journal of Rare Earths 2024年第6期42卷 1136-1141,I0005页

作者： Kai Yin Xiaopeng liu State Key Laboratory of Advanced Materials for Smart Sensing GRINM Group Co.Ltd.Beijing10088China GRIMAT Engineering Institute co. Ltd.Beijing101407China General Research Institute of Nonferrous Metals Beijing100088China

To improve the nitriding resistance of Zr_(2)Fe alloy,the ce-added Zr_(2)(Fe_(1-x)Ni_(x))(x=0,0.15,0.3,0.5)alloys were prepared by magnetic levitation melting *** effects of Ni substitution for Fe on the phase structure,hydrogen and nitrogen absorption properties of the alloys were investigated by X-ray diffraction,scanning electron microscopy and p-c isotherm *** experimental results show that Ni substitution can effectively inhibit the formation of both α-Zr and ZrFe_(2) phases and promote the formation of c16 structure Zr_(2)(Fe,Ni)phase,causing Ni-substituted alloys to exhibit low nitrogen absorption rate and *** 623 K under 0.5 MPa nitrogen pressure,the nitrogen absorption capacity of ce-added Zr_(2)(Fe_(0.5)Ni_(0.5))alloy reaches to 0.8 mL/g,much lower than that of Zr_(2)Fe alloy(1.5 mL/g).Ni substitution decreases the crystal cell volume of the c_(16)Zr_(2)(Fe,Ni)phase,resulting in an increase in the hydrogen absorption equilibrium *** 623 K under 0.05 MPa hydrogen pressure,the hydrogen absorption capacity decreases from 1.46 wt%of Zr_(2)Fe alloy to 1.41 wt%of ce-added Zr_(2)(Fe_(0.5)Ni_(0.5))alloy.

关键词： Zr_(2)Fe alloy ce Pressure-composition isotherm Hydrogen absorption Nitrogen absorption Rare earths

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Numerical investigation of non-uniform temperature fields for proppant and fluid phases in supercritical cO_(2)fracturing

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Particuology 2024年第7期90卷 149-163页

作者： Boyu liu Jun Yao Research center of Multiphase Flow in Porous Media China University of Petroleum(East China)Qingdao 266000China

The non-uniform temperature distribution in supercritical cO_(2)(Sc-cO_(2))fracturing influences the density,viscosity,and volume expansion or shrinkage rate of Sc-cO_(2),impacting proppant *** study presents a coupled computational fluid dynamics-discrete element method and heat transfer model to examine the effects of proppant bed shape and the heat transfers of proppant-wall,proppant-fluid,and fluid-wall on the fluid and proppant temperature *** Sc-cO_(2)volume expansion is assessed under various temperature conditions by evaluating the volume-averaged Sc-cO_(2)*** factors,including proppant size,shape,thermal conductivity,concentration,temperature difference,and injection velocity,are carefully analyzed to elucidate their *** findings elucidate the existence of four distinct zones in the fluid temperature *** zone exhibits different magnitudes of temperature change under diverse conditions and undergoes dynamic transformations with the development of the proppant *** fluid-wall heat transfer and the fluid temperatures in Zones c and D are significantly subject to the fluid injection velocity(governing the heating duration),the temperature difference between fluid and formation(impacting the magnitude of heat flux),and the proppant bed shape(controlling the effective heating area).Additionally,the proppant-wall and proppant-fluid heat transfers determine the temperatures of both the proppant bed and the fluid within Zone B,showing a strong correlation with proppant thermal conductivity,proppant size,injection velocity,and temperature *** proposed coupled model provides valuable insights into the temperature distributions and flow behaviors of temperature-dependent fracturing fluids and proppants.

关键词： cFD-DEM Heat transfer compressible fluid cO_(2)sequestration Proppant transport

Photoionisation detection of a single Er3+ ion with sub-100-ns time resolution

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National Science Review 2024年第4期11卷 38-45页

作者： Yangbo Zhang Wenda Fan Jiliang Yang Hao Guan Qi Zhang Xi Qin changkui Duan Gabriele G.de Boo Brett c.Johnson jeffrey c.Mc callum Matthew J.Sellars Sven Rogge chunming Yin Jiangfeng Du cAS Key Laboratory of Microscale Magnetic Resonance and School of Physical Sciences University of Science and Technology of China cAS center for Excellence in Quantum Information and Quantum Physics University of Science and Technology of China Hefei National Laboratory University of Science and Technology of China centre of Excellence for Quantum computation and communication Technology School of Physics University of New South Wales centre of Excellence for Quantum computation and communication Technology School of Engineering RMIT University centre of Excellence for Quantum computation and communication Technology School of Physics University of Melbourne centre of Excellence for Quantum computation and communication Technology Research School of Physics and Engineering Australian National University

Efficient detection of single optical centres in solids is essential for quantum information processing, sensing and single-photon generation *** this work,we use radio-frequency（RF） reflectometry to electrically detect the photoionisation induced by a single Er3+ion in *** high bandwidth and sensitivity of the RF reflectometry provide sub-100-ns time resolution for the photoionisation *** this technique,the optically excited state lifetime of a single Er3+ion in a Si nano-transistor is measured for the first time to be 0.49±0.04μ*** results demonstrate an efficient approach for detecting a charge state change induced by Er excitation and *** approach could be used for fast readout of other single optical centres in solids and is attractive for large-scale integrated optical quantum systems thanks to the multi-channel RF reflectometry demonstrated with frequency multiplexing techniques.

关键词： single optical centres erbium ions RF reflectometry photoionisation detection

Identification of the optimal doping position of hetero-atoms in chalcogen-doped Fe-N-c catalysts for oxygen reduction reaction

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Particuology 2024年第6期89卷 99-108页

作者： Weihao liu Huanhuan He Qingtao liu Xin Wan Jianglan Shui School of Materials Science and Engineering Beihang UniversityBeijing100191China School of Space and Environment Beihang UniversityBeijing102206China Tianmushan Laboratory Hangzhou310023China

The excellent oxygen reduction reaction(ORR)activity of Fe–N–c catalysts in acidic media makes them potential for low-cost proton exchange membrane fuel *** recent years,it has been shown that heteroatoms(B,O,S,P,cl,F,etc.)can be used as electron-withdrawing groups to modulate the planar structure and electron distribution of the Fe–Nx active sites to achieve simultaneous improvement of catalytic activity and ***,the optimal location of the heteroatoms remains ***,taking chalcogen heteroatoms(S and Se)as an example,we control the doping positions and investigate their effect on the ORR performance of the Fe–N–c *** first coordination shell of the iron single atom is identified as the optimal doping *** optimized catalysts Fe–N_(3)Se_(1)/Nc and Fe–N_(3)Se_(1)/Nc demonstrate improved activity and stability in both half cells and fuel *** work provides insights into the enhancement mechanism of heteroatom doping in single-atom catalysts.

关键词： Oxygen reduction reaction Fe-N-c catalysts Hetero-atom doping Doping position Enhancement mechanism

High-performance,stable coNi LDH@Ni foam composite membrane with innovative peroxymonosulfate activation for 2,4-dichlorophenol destruction

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Journal of Environmental Sciences 2024年第7期141卷 235-248页

作者： Yu liu Weibao liu Xinrui Gan Jiangwei Shang Xiuwen cheng college of chemistry and Environmental Science Xinjiang Laboratory of Phase Transitions and Microstructures of Condensed Matter PhysicsYili Normal UniversityYining 835000China Key Laboratory for Environmental Pollution Prediction and control Gansu ProvinceCollege of Earth and Environmental SciencesLanzhou UniversityLanzhou 730000China

In this study,the cobalt-nickel layered double hydroxides(coNi LDH)were synthesized with a variety of co/Ni mass ratio,as *** comparison,co1Ni3LDH presented the best peroxymonosulfate(PMS)activation efficiency for 2,4-dichlorophenol ***,coNi LDH@Nickel foam(coNi LDH@NF)composite membrane was constructed for enhancing the stability of catalytic ***,coNi LDH@NF-PMS system exerted high degradation efficiency of 99.22%within 90 min for 2,4-DcP when[PMS]_(0)=0.4 g/L,co^(1)Ni^(3)LDH@NF=2 cm×2 cm(0.2 g/L),reaction temperature=298 *** the surface morphology and structure of the catalyst,it was demonstrated that the coNi LDH@NF composite membrane possessed abundant cavity structure,good specific surface area and sufficient active ***,·OH,SO_(4)·^(-)and^(1)O_(2)played the primary role in the coNi LDH@NF-PMS system for 2,4-DcP decomposition,which revealed the PMS activation mechanism in coNi LDH@NF-PMS ***,this study eliminated the stability and adaptability of coNi LDH@NF composite membrane,proposing a new theoretical basis of PMS heterogeneous catalysts selection.

关键词： coNi LDH@NF composite membrane Peroxymonosulfate 2,4-dichlorophenol Reactive radicals

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Optimization performance of quantum endoreversible Otto machines with dual-squeezed reservoirs

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chinese Physics B 2024年第10期33卷 198-204页

作者： Haoguang liu college of Science and Technology Nanchang Aeronautical UniversityNanchang 332020China

We consider a quantum endoreversible Otto engine cycle and its inverse operation-Otto refrigeration cycle,employing two-level systems as the working substance and operating in dual-squeezed *** demonstrate that the efficiency of heat engines at maximum work output and the coefficient of performance for refrigerators at the maximum c criterion will degenerate toη-=η_(c)/(2-η_(c))andε-=(√9+8ε_(c)-3)/2 when symmetric squeezing is satisfied,*** also investigated the influences of squeezing degree on the performance optimization of quantum Otto heat engines at the maximum work output and refrigerators at the maximum X *** analytical results show that the efficiency of heat engines at maximum work output and the coefficient of performance for refrigerators at the maximum X criterion can be improved,reduced or even inhibited in asymmetric ***,we also find that the efficiency of quantum Otto heat engines at maximum work output is lower than that obtained from the Otto heat engines based on a single harmonic oscillator ***,the coefficient of performance of the corresponding refrigerator is higher.

关键词： quantum Otto heat engine quantum Otto refrigerator optimization performance dual-squeezed reservoirs

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Two-dimensional atomically thin Pt layers on MXenes: The role of electronic effects during catalytic dehydrogenation of ethane and propane

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Nano Research 2024年第3期17卷 1251-1258页

作者： Zhe Li Tobias K.Misicko Fan Yang Xiaopeng liu Zhenwei Wu Xiaoyang Gao Tao Ma jeffrey T.Miller Daniela S.Mainardi collin D.Wick Zhenhua Zeng Yang Xiao Yue Wu Department of chemical and Biological Engineering Iowa State University618 Bissell RoadAmesIA 50011USA Institute for Micromanufacturing Louisiana Tech University505 Tech DriveRustonLA 71272USA Davidson School of chemical Engineering Purdue University480 Stadium Mall DriveWest LafayetteIN 47907USA Michigan center for Materials characterization University of Michigan2800 Plymouth RdAnn Arbor MI 48109USA college of Engineering and Science Louisiana Tech UniversityRustonLA 71272USA

Atomically thin Pt nanolayers were synthesized on the surface of Mo2Tic2 MXenes and used for the catalytic dehydrogenation of ethane and propane into ethylene and propylene,two important chemicals for the petrochemical *** compared with Pt nanoparticles,the atomically thin Pt nanolayer catalyst showed superior coke-resistance(no deactivation for 24 h),high activity(turnover frequencies(TOFs)of 0.4–1.2 s^(-1)),and selectivity(>95%)toward ethylene and *** unique Pt nanolayer has a similar geometric surface to Pt nanoparticles,enabling the investigations of the electronic effect on the catalytic performance,where the geometric effect is *** is found that the electronic effect plays a critical role in dehydrogenative product selectivity and catalyst *** metal–support interaction is found dependent on the substrate and metal components,providing wide opportunities to explore high-performance MXene-supported metallic catalysts.

关键词： MXene catalysis alkane dehydrogenation nanolayers

Atomically precise Ru-O-Ru clusters for enhanced water dissociation in alkaline hydrogen evolution

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Nano Research 2024年第8期17卷 6993-7000页

作者： Dong liu Li Xu Sicheng Li Airong Xu Yuanhua Sun Tong liu Mengyuan liu Huijuan Wang Xiaokang liu Tao Yao Tao Ding Hefei National Research center for Physical Sciences at the Microscale School of Nuclear Science and TechnologyKey Laboratory of Precision and Intelligent ChemistryNational Synchrotron Radiation LaboratoryUniversity of Science and Technology of ChinaHefei 230029China Experimental center of Engineering and Materials Science University of Science and Technology of ChinaHefei 230026China

Atomic clusters typically exhibit distinctive electronic structures and physicochemical ***,as the size decreases,their ability to adsorb and dissociate water also diminishes,thereby affecting chemical reactions involving water *** the adsorption and dissociation capabilities of atomic clusters towards water molecules and elucidating the mechanisms underlying their performance enhancement have become important research ***,employing the carrier-anchored strategy,Ru-O-Ru atomic clusters were prepared and displayed excellent activity and durability in the hydrogen evolution ***,the Ru-O-Ru atomic clusters exhibited only 86 mV overpotential at 100 mA·cm−^(2) and superior membrane-electrode-assembly activity than commercial Ru/c *** radiation-based Fourier transform infrared spectroscopic measurements revealed that the modification of oxygen in Ru-O-Ru units promoted the reorientation of water molecules from a H-up orientation to H-down,therefore,enhanced the formation of strong hydrogen-bond network of interfacial water on the surface of Ru-O-Ru clusters,leading to enhanced adsorption and dissociation of water and accelerated Volmer *** findings provide a potential strategy and deep insights for the development of atomic clusters in electrocatalysts.

关键词： hydrogen evolution in-situ Fourier transform infrared(FTIR) Ru catalysts electrocatalysis atomic clusters