A two-dimensional self-consistent fluid model is employed to investigate radio-frequency process parameters on the plasma properties in Ar microdischarges. The neutral gas density and temperature balance equations are...A two-dimensional self-consistent fluid model is employed to investigate radio-frequency process parameters on the plasma properties in Ar microdischarges. The neutral gas density and temperature balance equations are taken into account. We mainly investigate the effect of the electrode gap on the spatial distribution of the electron density and electron temperature profiles, due to a mode transition from the regime（secondary electrons emission is responsible for the significant ionization） to the regime（sheath oscillations and bulk electrons are responsible for sustaining discharge） induced by a sudden decrease of electron density and electron temperature.The pressure, radio-frequency sources frequency and voltage effects on the electron density are also elaborately investigated.展开更多
Interdigitated back contact（IBC） solar cells can achieve a very high efficiency due to its less optical losses. But IBC solar cells demand for high quality passivation of the front surface. In this paper, a polycrys...Interdigitated back contact（IBC） solar cells can achieve a very high efficiency due to its less optical losses. But IBC solar cells demand for high quality passivation of the front surface. In this paper, a polycrystalline silicon/SiO_2 stack structure as front surface field to passivate the front surface of IBC solar cells is proposed. The passivation quality of this structure is investigated by two dimensional simulations. Polycrystalline silicon layer and SiO_2 layer are optimized to get the best passivation quality of the IBC solar cell. Simulation results indicate that the doping level of polycrystalline silicon should be high enough to allow a very thin polycrystalline silicon layer to ensure an effective passivation and small optical losses at the same time. The thickness of SiO_2 should be neither too thin nor too thick, and the optimal thickness is 1.2 nm.Furthermore, the lateral transport properties of electrons are investigated, and the simulation results indicate that a high doping level and conductivity of polycrystalline silicon can improve the lateral transportation of electrons and then the cell performance.展开更多
Guiding wall is used to change the flow of the oxidation ditch as supporting structure, it widely uses eccentric setting, and its setting parameters are mostly empirical judgments. According to fluent software that si...Guiding wall is used to change the flow of the oxidation ditch as supporting structure, it widely uses eccentric setting, and its setting parameters are mostly empirical judgments. According to fluent software that simulates the velocity distribution of the guiding wall, to discuss the settings of the guiding wall in different length of downstream extension, eccentricity and guiding wall radius, so to work out its optimized settings.展开更多
The characteristics of a collisional dual frequency （DF） sheath near an electrode with a cylindrical hole are studied by utilizing a two-dimensional model which includes time-dependent fluid equations coupled with t...The characteristics of a collisional dual frequency （DF） sheath near an electrode with a cylindrical hole are studied by utilizing a two-dimensional model which includes time-dependent fluid equations coupled with the Poisson equation and an equivalent-circuit model, The effects of the gas pressure on the two-dimensional profiles of the potential, electric field, ion fluid velocity in a DF sheath are investigated. The simulation results show that the cylindrical hole on the electrode has a significant influence on the DF sheath structure, i.e., the sheath profile tends to wrap around the contour of the hole feature. Moreover, it is shown that the structure of the DF sheath is different from that of a single frequency （SF） sheath because the profile of the DF sheath is modulated by the combination of the high and low frequency sources. In addition the characteristics of the DF sheath are obviously affected by the collisional effects in the DF sheath.展开更多
A two-dimensional model of a weakly-ionized hydrogen direct-current （DC） discharge at low pressure is simulated. In the model, the metal electron overflow and secondary electron emission coefficient at the cathode s...A two-dimensional model of a weakly-ionized hydrogen direct-current （DC） discharge at low pressure is simulated. In the model, the metal electron overflow and secondary electron emission coefficient at the cathode spot axe introduced to represent the relationship between the electron and ion density, and the electron energy distribution function is expressed by kinetic theory. The electron current density and reaction constant reasonably set on the boundary are discussed. It is determined that 11 collision reactions play a major role in low pressure and weakly ionized hydrogen discharge. On this basis, the relationship between mobility, electrode spacing, and breakdown voltage is verified. Good agreement is achieved between the simulation curve and Paschen curve.展开更多
Recent studies on hydrogen combustion were reviewed briefly. The laminar flow and combustion of premixed hydrogen/air mixture in a cylindrical channel of a monolith reactor with and without catalytic wall was numerica...Recent studies on hydrogen combustion were reviewed briefly. The laminar flow and combustion of premixed hydrogen/air mixture in a cylindrical channel of a monolith reactor with and without catalytic wall was numerically modeled by solving two-dimensional (2-D) Navier-Stokes (N-S) equations, energy equation, and species equations. Eight gas species and twenty reversible gas reactions were considered. The control volume technique and the SIMPLE algorithm were used to solve the partial differential equations. The streamlines of the flow field, temperature contours, the entrance length, and the concentration fields were computed. It is found that the entrance zone plays an important role on flow and temperature as well as species distribution. Therefore, the flow cannot be assumed either as fully developed or as plug flow. There is a small but strong thermal expansion zone between the wall and the entrance. Both diffusion and convection affect the heat and mass transfer processes in the expansion zone. Thus the equations of momentum, energy and species conservations should be used to describe hydrogen/air combustion in the monolith reactor. The hot-spot location and concentration field of the homogeneous combustion is strongly influenced by the inlet velocity and temperature, and the equivalence ratio. The catalytic combustion of premixed hydrogen/air mixture over platinum catalyst-coated wall in a cylindrical channel was also simulated.展开更多
Simulating U(1) quantum gauge theories with spatial dimensions greater than one is of great physical significance. Here we propose a simple realization of U(1) gauge theory with Rydberg and Rydberg-dressed atom arrays...Simulating U(1) quantum gauge theories with spatial dimensions greater than one is of great physical significance. Here we propose a simple realization of U(1) gauge theory with Rydberg and Rydberg-dressed atom arrays. Within the experimentally accessible range, we find that the various aspects of the U(1) gauge theory can be well simulated, such as the emergence of topological sectors, incommensurability, and the Rokhsar–Kivelson point that hosts deconfined charge excitations and degenerate topological sectors. Our proposal is promising to implement experimentally and exhibits pronounced quantum dynamics.展开更多
A two-dimensional Reynolds-averaged Navier-Stokes solver is applied to analyze the aerodynamic behavior of the Shock/Boundary-Layer interaction of rocket with a boosted The K-ε turbulence model and a finite volume m...A two-dimensional Reynolds-averaged Navier-Stokes solver is applied to analyze the aerodynamic behavior of the Shock/Boundary-Layer interaction of rocket with a boosted The K-ε turbulence model and a finite volume method in a unstructured body-fitted curvilinear coordinates have been used. The results indicate that the separation and the reattachment occur in the Boundary-Layer of the main rocket because of the shock interaction. The shape of the booster nose effects the flow field obviously. In the case of the hemisphere booster nose the pressure has complicate distributions and the separation is very clear. The distance between the booster and main rocket has the evident effect on the flow field. If the distance is smaller the pressure coefficient is bigger the separation zone even the separation bubble occurs.展开更多
AIGaN/GaN HEMTs are investigated by numerical simulation from the self-consistent solution of Schr6dinger-Poisson-hydrodynamic （HD） systems. The influences of polarization charge and quantum effects are considered i...AIGaN/GaN HEMTs are investigated by numerical simulation from the self-consistent solution of Schr6dinger-Poisson-hydrodynamic （HD） systems. The influences of polarization charge and quantum effects are considered in this model. Then the two-dimensional conduction band and electron distribution, electron temperature characteristics, Id versus Vd and Id versus Vg, transfer characteristics and transconductance curves are obtained. Corresponding analysis and discussion based on the simulation results are subsequently given.展开更多
As emerging two-dimensional(2D)materials,carbides and nitrides(MXenes)could be solid solutions or organized structures made up of multi-atomic layers.With remarkable and adjustable electrical,optical,mechanical,and el...As emerging two-dimensional(2D)materials,carbides and nitrides(MXenes)could be solid solutions or organized structures made up of multi-atomic layers.With remarkable and adjustable electrical,optical,mechanical,and electrochemical characteristics,MXenes have shown great potential in brain-inspired neuromorphic computing electronics,including neuromorphic gas sensors,pressure sensors and photodetectors.This paper provides a forward-looking review of the research progress regarding MXenes in the neuromorphic sensing domain and discussed the critical challenges that need to be resolved.Key bottlenecks such as insufficient long-term stability under environmental exposure,high costs,scalability limitations in large-scale production,and mechanical mismatch in wearable integration hinder their practical deployment.Furthermore,unresolved issues like interfacial compatibility in heterostructures and energy inefficiency in neu-romorphic signal conversion demand urgent attention.The review offers insights into future research directions enhance the fundamental understanding of MXene properties and promote further integration into neuromorphic computing applications through the convergence with various emerging technologies.展开更多
BACKGROUND Orthopaedic surgical education has traditionally depended on the apprenticeship model of“see one,do one,teach one”.However,reduced operative exposure,stricter work-hour regulations,medicolegal constraints...BACKGROUND Orthopaedic surgical education has traditionally depended on the apprenticeship model of“see one,do one,teach one”.However,reduced operative exposure,stricter work-hour regulations,medicolegal constraints,and patient safety concerns have constrained its practicality.Simulation-based training has become a reliable,safe,and cost-efficient alternative.Dry lab techniques,especially virtual and augmented reality,make up 78%of current dry lab research,whereas wet labs still set the standard for anatomical realism.AIM To evaluate the effectiveness,limitations,and future directions of wet and dry lab simulation in orthopaedic training.METHODS A scoping review was carried out across four databases-PubMed,Cochrane Library,Web of Science,and EBSCOhost-up to 2025.Medical Subject Headings included:"Orthopaedic Education","Wet Lab","Dry Lab","Simulation Training","Virtual Reality",and"Surgical Procedure".Eligible studies focused on orthopaedic or spinal surgical education,employed wet or dry lab techniques,and assessed training effectiveness.Exclusion criteria consisted of non-English publications,abstracts only,non-orthopaedic research,and studies unrelated to simulation.Two reviewers independently screened titles,abstracts,and full texts,resolving discrepancies with a third reviewer.RESULTS From 1851 records,101 studies met inclusion:78 on dry labs,7 on wet labs,4 on both.Virtual reality(VR)simulations were most common,with AI increasingly used for feedback and assessment.Cadaveric training remains the gold standard for accuracy and tactile feedback,while dry labs-especially VR-offer scalability,lower cost(40%-60%savings in five studies),and accessibility for novices.Senior residents prefer wet labs for complex tasks;juniors favour dry labs for basics.Challenges include limited transferability data,lack of standard outcome metrics,and ethical concerns about cadaver use and AI assessment.CONCLUSION Wet and dry labs each have unique strengths in orthopaedic training.A hybrid approach combining both,supported by standardised assessments and outcome studies,is most effective.Future efforts should aim for uniform reporting,integrating new technologies,and policy support for hybrid curricula to enhance skills and patient care.展开更多
This study introduces a new ocean surface friction velocity scheme and a modified Thompson cloud microphysics parameterization scheme into the CMA-TYM model.The impact of these two parameterization schemes on the pred...This study introduces a new ocean surface friction velocity scheme and a modified Thompson cloud microphysics parameterization scheme into the CMA-TYM model.The impact of these two parameterization schemes on the prediction of the movement track and intensity of Typhoon Kompasu in 2021 is examined.Additionally,the possible reasons for their effects on tropical cyclone(TC)intensity prediction are analyzed.Statistical results show that both parameterization schemes improve the predictions of Typhoon Kompasu’s track and intensity.The influence on track prediction becomes evident after 60 h of model integration,while the significant positive impact on intensity prediction is observed after 66 h.Further analysis reveals that these two schemes affect the timing and magnitude of extreme TC intensity values by influencing the evolution of the TC’s warm-core structure.展开更多
Marine thin plates are susceptible to welding deformation owing to their low structural stiffness.Therefore,the efficient and accurate prediction of welding deformation is essential for improving welding quality.The t...Marine thin plates are susceptible to welding deformation owing to their low structural stiffness.Therefore,the efficient and accurate prediction of welding deformation is essential for improving welding quality.The traditional thermal elastic-plastic finite element method(TEP-FEM)can accurately predict welding deformation.However,its efficiency is low because of the complex nonlinear transient computation,making it difficult to meet the needs of rapid engineering evaluation.To address this challenge,this study proposes an efficient prediction method for welding deformation in marine thin plate butt welds.This method is based on the coupled temperature gradient-thermal strain method(TG-TSM)that integrates inherent strain theory with a shell element finite element model.The proposed method first extracts the distribution pattern and characteristic value of welding-induced inherent strain through TEP-FEM analysis.This strain is then converted into the equivalent thermal load applied to the shell element model for rapid computation.The proposed method-particularly,the gradual temperature gradient-thermal strain method(GTG-TSM)-achieved improved computational efficiency and consistent precision.Furthermore,the proposed method required much less computation time than the traditional TEP-FEM.Thus,this study lays the foundation for future prediction of welding deformation in more complex marine thin plates.展开更多
Instead of the capillary plasma generator(CPG),a discharge rod plasma generator(DRPG)is used in the30 mm electrothermal-chemical(ETC)gun to improve the ignition uniformity of the solid propellant.An axisymmetric two-d...Instead of the capillary plasma generator(CPG),a discharge rod plasma generator(DRPG)is used in the30 mm electrothermal-chemical(ETC)gun to improve the ignition uniformity of the solid propellant.An axisymmetric two-dimensional interior ballistics model of the solid propellant ETC gun(2D-IB-SPETCG)is presented to describe the process of the ETC launch.Both calculated pressure and projectile muzzle velocity accord well with the experimental results.The feasibility of the 2D-IB-SPETCG model is proved.Depending on the experimental data and initial parameters,detailed distribution of the ballistics parameters can be simulated.With the distribution of pressure and temperature of the gas phase and the propellant,the influence of plasma during the ignition process can be analyzed.Because of the radial flowing plasma,the propellant in the area of the DRPG is ignited within 0.01 ms,while all propellant in the chamber is ignited within 0.09 ms.The radial ignition delay time is much less than the axial delay time.During the ignition process,the radial pressure difference is less than 5 MPa at the place 0.025 m away from the breech.The radial ignition uniformity is proved.The temperature of the gas increases from several thousand K(conventional ignition)to several ten thousand K(plasma ignition).Compare the distribution of the density and temperature of the gas,we know that low density and high temperature gas appears near the exits of the DRPG,while high density and low temperature gas appears at the wall near the breech.The simulation of the 2D-IB-SPETCG model is an effective way to investigate the interior ballistics process of the ETC launch.The 2D-IB-SPETC model can be used for prediction and improvement of experiments.展开更多
Analysis of the environmental and economic performance of fishing vessels has received limited attention compared with other ship types despite their notable contribution to global greenhouse gas(GHG)emissions.This st...Analysis of the environmental and economic performance of fishing vessels has received limited attention compared with other ship types despite their notable contribution to global greenhouse gas(GHG)emissions.This study evaluates the carbon footprint(CF)and economic viability of a liquefied natural gas(LNG)-fueled fishing vessel,using real engine operation simulations to provide precise and dynamic evaluation of fuel consumption and GHG emissions.Operational profiles are obtained through the utilization of onboard monitoring systems,whereas engine performance is simulated using the 1D/0D AVL Boost^(TM)model.Life cycle assessment(LCA)is conducted to quantify the environmental impact,whereas life cycle cost assessment(LCCA)is performed to analyze the profitability of LNG as an alternative fuel.The potential impact of the future fuel price uncertainties is addressed using Monte Carlo simulations.The LCA findings indicate that LNG has the potential to reduce the CF of the vessel by 14%to 16%,in comparison to a diesel power system configuration that serves as the baseline scenario.The LCCA results further indicate that the total cost of an LNG-powered ship is lower by 9.5%-13.8%,depending on the share of LNG and pilot fuels.This finding highlights the potential of LNG to produce considerable environmental benefits while addressing economic challenges under diverse operational and fuel price conditions.展开更多
The paper establishes the relationship between the settling efficiency and the sizes of the sedimentation tank through the process of numerical simulation, which is taken as one of the constraints to set up a simple o...The paper establishes the relationship between the settling efficiency and the sizes of the sedimentation tank through the process of numerical simulation, which is taken as one of the constraints to set up a simple optimum designing model of sedimentation tank. The feasibility and advantages of this model based on numerical calculation are verified through the application of practical case.展开更多
This study systematically investigated the Lean Blowoff(LBO)limits of Two-Dimensional(2D)bluff-body stabilized premixed flames by varying the air mass flow rate,inflowtemperature,bluff-body width,and fuel type.The dat...This study systematically investigated the Lean Blowoff(LBO)limits of Two-Dimensional(2D)bluff-body stabilized premixed flames by varying the air mass flow rate,inflowtemperature,bluff-body width,and fuel type.The data of LBO limits were analyzed and fittedaccording to the Damk?hler(Da)and Reynolds(Re)numbers,and the fitting accuracy of LBO datawas highly improved by a modified characteristic length simultaneously considering the length andwidth of the bluff body,which is usually neglected in the previous studies.Moreover,to our knowl-edge,this is the first time that simultaneous transverse and spanwise OH*-Chemiluminescence(CL)imaging has been performed to examine the three-dimensional behavior of the LBO process.The flame stability is heavily affected by the mass and energy transport between reactants andproducts in both directions,potentially leading to the flame pinch-off.The intensity and positionof the upstream flame after pinch-off are decisive to the occurrence of the following LBO.Whenthe upstream flame after pinch-off is weak and close to the bluff body,it cannot re-ignite thedownstream unburnt gas.Subsequently,a permanent downstream extinction occurs,and theLBO takes place.The results help understand the LBO mechanism of 2D bluff-body stabilizedflames.展开更多
A two-dimensional discrete dislocation dynamics （DDD） technology by Giessen and Needleman （1995）, which has been extended by integrating a dislocation-grain boundary interaction model, is used to computationally a...A two-dimensional discrete dislocation dynamics （DDD） technology by Giessen and Needleman （1995）, which has been extended by integrating a dislocation-grain boundary interaction model, is used to computationally analyze the micro-cyclic plastic response of polycrystals containing micron-sized grains, with special attentions to significant influence of dislocationpenetrable grain boundaries （GBs） on the micro-plastic cyclic responses of polycrystals and underlying dislocation mechanism. Toward this end, a typical polycrystalline rectangular specimen under simple tension-compression loading is considered. Results show that, with the increase of cycle accumulative strain, continual dislocation accumulation and enhanced dislocation-dislocation interactions induce the cyclic hardening behavior; however, when a dynamic balance among dislocation nucleation, penetration through GB and dislocation annihilation is approximately established, cyclic stress gradually tends to saturate. In addition, other factors, including the grain size, cyclic strain amplitude and its history, also have considerable influences on the cyclic hardening and saturation.展开更多
Graphyne is expected to be a new-class of highly-efficient sieving membranes due to its controllable uniform pore structure and ultrathin single-atom thickness. Herein, we computationally investigate the permeation pe...Graphyne is expected to be a new-class of highly-efficient sieving membranes due to its controllable uniform pore structure and ultrathin single-atom thickness. Herein, we computationally investigate the permeation performance of liquid ethanol–water mixtures across polyporous two-dimensional γ-graphyne sheets. It was found that, in the mixture, ethanol with larger molecular diameter permeates faster through the graphyne pores than water. The simulations demonstrate that pristine graphynes could act as highly-efficient ethanol-permselective membranes for separation of ethanol–water mixtures, with ethanol permeability remarkably higher than conventional membranes. This separation mechanism is distinctly different from the molecular-size dependent sieving process. The stronger hydrophobic interfacial affinity between graphyne and ethanol makes ethanol molecules preferentially adsorb on graphyne surface and selectively penetrate through graphyne pores. This penetration mechanism provides new understanding of molecular transport through atomically thick two-dimensional nanoporous membranes and this work is expected to be valuable in the potential development of highly-efficient membranes for liquid-phase mixture separation.展开更多
A numerical model has been developed for computing turbulent flow in plane-wall diffuser.The model solves the weakly compressible flow equations with the application of the Smagorinsky's subgrid-scale turbulence m...A numerical model has been developed for computing turbulent flow in plane-wall diffuser.The model solves the weakly compressible flow equations with the application of the Smagorinsky's subgrid-scale turbulence model and the boundary conditions of partial slip and no slip at the solid wall.Application examples include two-dimensional calculations of unstalled and stalled flows in diffusers of small diverging angle,as well as transitory stall flow in a symmetric diffuser of 16°total angle.For the unstalled and stalled flows,the calculated pressure recovery and velocity profile are compared with experimental data.For the transitory stall flow,the com- putational result shows the unsteady flow features including the vortex shedding and stall washout phenomena that have been experimentally observed.展开更多
基金Supported by the Fundamental Research Funds in Heilongjiang Provincial Universities of China under Grant No 135209312
文摘A two-dimensional self-consistent fluid model is employed to investigate radio-frequency process parameters on the plasma properties in Ar microdischarges. The neutral gas density and temperature balance equations are taken into account. We mainly investigate the effect of the electrode gap on the spatial distribution of the electron density and electron temperature profiles, due to a mode transition from the regime（secondary electrons emission is responsible for the significant ionization） to the regime（sheath oscillations and bulk electrons are responsible for sustaining discharge） induced by a sudden decrease of electron density and electron temperature.The pressure, radio-frequency sources frequency and voltage effects on the electron density are also elaborately investigated.
基金supported by the National Natural Science Foundation of China(Grant Nos.11104319,11274346,51202285,61234005,51172268,51602340,61274059,and 51402347)the Solar Energy Action Plan of Chinese Academy of Sciences(Grant Nos.Y1YT064001,Y1YF034001,and Y2YF014001)+2 种基金the Graduate and College Student’s Innovative Project(Grant No.YC2016-X19)the Project of Beijing Municipal Science and Technology Commission(Grant No.Z151100003515003)the Opening Project of Key Laboratory of Microelectronics Devices&Integrated Technology,Institute of Microelectronics,Chinese Academy of Sciences
文摘Interdigitated back contact（IBC） solar cells can achieve a very high efficiency due to its less optical losses. But IBC solar cells demand for high quality passivation of the front surface. In this paper, a polycrystalline silicon/SiO_2 stack structure as front surface field to passivate the front surface of IBC solar cells is proposed. The passivation quality of this structure is investigated by two dimensional simulations. Polycrystalline silicon layer and SiO_2 layer are optimized to get the best passivation quality of the IBC solar cell. Simulation results indicate that the doping level of polycrystalline silicon should be high enough to allow a very thin polycrystalline silicon layer to ensure an effective passivation and small optical losses at the same time. The thickness of SiO_2 should be neither too thin nor too thick, and the optimal thickness is 1.2 nm.Furthermore, the lateral transport properties of electrons are investigated, and the simulation results indicate that a high doping level and conductivity of polycrystalline silicon can improve the lateral transportation of electrons and then the cell performance.
文摘Guiding wall is used to change the flow of the oxidation ditch as supporting structure, it widely uses eccentric setting, and its setting parameters are mostly empirical judgments. According to fluent software that simulates the velocity distribution of the guiding wall, to discuss the settings of the guiding wall in different length of downstream extension, eccentricity and guiding wall radius, so to work out its optimized settings.
基金supported by National Natural Science Foundation of China (Nos.10635010,10572035)
文摘The characteristics of a collisional dual frequency （DF） sheath near an electrode with a cylindrical hole are studied by utilizing a two-dimensional model which includes time-dependent fluid equations coupled with the Poisson equation and an equivalent-circuit model, The effects of the gas pressure on the two-dimensional profiles of the potential, electric field, ion fluid velocity in a DF sheath are investigated. The simulation results show that the cylindrical hole on the electrode has a significant influence on the DF sheath structure, i.e., the sheath profile tends to wrap around the contour of the hole feature. Moreover, it is shown that the structure of the DF sheath is different from that of a single frequency （SF） sheath because the profile of the DF sheath is modulated by the combination of the high and low frequency sources. In addition the characteristics of the DF sheath are obviously affected by the collisional effects in the DF sheath.
基金supported by National Natural Science Foundation of China(No.50877003)
文摘A two-dimensional model of a weakly-ionized hydrogen direct-current （DC） discharge at low pressure is simulated. In the model, the metal electron overflow and secondary electron emission coefficient at the cathode spot axe introduced to represent the relationship between the electron and ion density, and the electron energy distribution function is expressed by kinetic theory. The electron current density and reaction constant reasonably set on the boundary are discussed. It is determined that 11 collision reactions play a major role in low pressure and weakly ionized hydrogen discharge. On this basis, the relationship between mobility, electrode spacing, and breakdown voltage is verified. Good agreement is achieved between the simulation curve and Paschen curve.
基金Foundation item: Partially supported by the Key Laboratory of Multiphase Reaction of the Chinese Academy of Sciences State Key of Coal Conversion of the Chinese Academy of Sciences
文摘Recent studies on hydrogen combustion were reviewed briefly. The laminar flow and combustion of premixed hydrogen/air mixture in a cylindrical channel of a monolith reactor with and without catalytic wall was numerically modeled by solving two-dimensional (2-D) Navier-Stokes (N-S) equations, energy equation, and species equations. Eight gas species and twenty reversible gas reactions were considered. The control volume technique and the SIMPLE algorithm were used to solve the partial differential equations. The streamlines of the flow field, temperature contours, the entrance length, and the concentration fields were computed. It is found that the entrance zone plays an important role on flow and temperature as well as species distribution. Therefore, the flow cannot be assumed either as fully developed or as plug flow. There is a small but strong thermal expansion zone between the wall and the entrance. Both diffusion and convection affect the heat and mass transfer processes in the expansion zone. Thus the equations of momentum, energy and species conservations should be used to describe hydrogen/air combustion in the monolith reactor. The hot-spot location and concentration field of the homogeneous combustion is strongly influenced by the inlet velocity and temperature, and the equivalence ratio. The catalytic combustion of premixed hydrogen/air mixture over platinum catalyst-coated wall in a cylindrical channel was also simulated.
基金supported by the National Key Research and Development Program of China (Grant Nos. 2022YFA1404204 and 2022YFA1403700)the National Natural Science Foundation of China (Grant Nos. 12274086, 11534001 and 11925402)+5 种基金funding from the National Science Foundation of China (Grant Nos. 12274046, 11874094, 12147102, and 12347101)Chongqing Natural Science Foundation (Grant No. CSTB2022NSCQ-JQX0018)the Fundamental Research Funds for the Central Universities (Grant No. 2021CDJZYJH-003)Xiaomi Foundation/Xiaomi Young Talents Programthe supports of the start-up funding of Westlake Universitysupport from the Natural Sciences and Engineering Research Council of Canada (NSERC) through Discovery Grants。
文摘Simulating U(1) quantum gauge theories with spatial dimensions greater than one is of great physical significance. Here we propose a simple realization of U(1) gauge theory with Rydberg and Rydberg-dressed atom arrays. Within the experimentally accessible range, we find that the various aspects of the U(1) gauge theory can be well simulated, such as the emergence of topological sectors, incommensurability, and the Rokhsar–Kivelson point that hosts deconfined charge excitations and degenerate topological sectors. Our proposal is promising to implement experimentally and exhibits pronounced quantum dynamics.
文摘A two-dimensional Reynolds-averaged Navier-Stokes solver is applied to analyze the aerodynamic behavior of the Shock/Boundary-Layer interaction of rocket with a boosted The K-ε turbulence model and a finite volume method in a unstructured body-fitted curvilinear coordinates have been used. The results indicate that the separation and the reattachment occur in the Boundary-Layer of the main rocket because of the shock interaction. The shape of the booster nose effects the flow field obviously. In the case of the hemisphere booster nose the pressure has complicate distributions and the separation is very clear. The distance between the booster and main rocket has the evident effect on the flow field. If the distance is smaller the pressure coefficient is bigger the separation zone even the separation bubble occurs.
文摘AIGaN/GaN HEMTs are investigated by numerical simulation from the self-consistent solution of Schr6dinger-Poisson-hydrodynamic （HD） systems. The influences of polarization charge and quantum effects are considered in this model. Then the two-dimensional conduction band and electron distribution, electron temperature characteristics, Id versus Vd and Id versus Vg, transfer characteristics and transconductance curves are obtained. Corresponding analysis and discussion based on the simulation results are subsequently given.
基金supported by the NSFC(12474071)Natural Science Foundation of Shandong Province(ZR2024YQ051,ZR2025QB50)+6 种基金Guangdong Basic and Applied Basic Research Foundation(2025A1515011191)the Shanghai Sailing Program(23YF1402200,23YF1402400)funded by Basic Research Program of Jiangsu(BK20240424)Open Research Fund of State Key Laboratory of Crystal Materials(KF2406)Taishan Scholar Foundation of Shandong Province(tsqn202408006,tsqn202507058)Young Talent of Lifting engineering for Science and Technology in Shandong,China(SDAST2024QTB002)the Qilu Young Scholar Program of Shandong University。
文摘As emerging two-dimensional(2D)materials,carbides and nitrides(MXenes)could be solid solutions or organized structures made up of multi-atomic layers.With remarkable and adjustable electrical,optical,mechanical,and electrochemical characteristics,MXenes have shown great potential in brain-inspired neuromorphic computing electronics,including neuromorphic gas sensors,pressure sensors and photodetectors.This paper provides a forward-looking review of the research progress regarding MXenes in the neuromorphic sensing domain and discussed the critical challenges that need to be resolved.Key bottlenecks such as insufficient long-term stability under environmental exposure,high costs,scalability limitations in large-scale production,and mechanical mismatch in wearable integration hinder their practical deployment.Furthermore,unresolved issues like interfacial compatibility in heterostructures and energy inefficiency in neu-romorphic signal conversion demand urgent attention.The review offers insights into future research directions enhance the fundamental understanding of MXene properties and promote further integration into neuromorphic computing applications through the convergence with various emerging technologies.
文摘BACKGROUND Orthopaedic surgical education has traditionally depended on the apprenticeship model of“see one,do one,teach one”.However,reduced operative exposure,stricter work-hour regulations,medicolegal constraints,and patient safety concerns have constrained its practicality.Simulation-based training has become a reliable,safe,and cost-efficient alternative.Dry lab techniques,especially virtual and augmented reality,make up 78%of current dry lab research,whereas wet labs still set the standard for anatomical realism.AIM To evaluate the effectiveness,limitations,and future directions of wet and dry lab simulation in orthopaedic training.METHODS A scoping review was carried out across four databases-PubMed,Cochrane Library,Web of Science,and EBSCOhost-up to 2025.Medical Subject Headings included:"Orthopaedic Education","Wet Lab","Dry Lab","Simulation Training","Virtual Reality",and"Surgical Procedure".Eligible studies focused on orthopaedic or spinal surgical education,employed wet or dry lab techniques,and assessed training effectiveness.Exclusion criteria consisted of non-English publications,abstracts only,non-orthopaedic research,and studies unrelated to simulation.Two reviewers independently screened titles,abstracts,and full texts,resolving discrepancies with a third reviewer.RESULTS From 1851 records,101 studies met inclusion:78 on dry labs,7 on wet labs,4 on both.Virtual reality(VR)simulations were most common,with AI increasingly used for feedback and assessment.Cadaveric training remains the gold standard for accuracy and tactile feedback,while dry labs-especially VR-offer scalability,lower cost(40%-60%savings in five studies),and accessibility for novices.Senior residents prefer wet labs for complex tasks;juniors favour dry labs for basics.Challenges include limited transferability data,lack of standard outcome metrics,and ethical concerns about cadaver use and AI assessment.CONCLUSION Wet and dry labs each have unique strengths in orthopaedic training.A hybrid approach combining both,supported by standardised assessments and outcome studies,is most effective.Future efforts should aim for uniform reporting,integrating new technologies,and policy support for hybrid curricula to enhance skills and patient care.
基金supported by the National Key R&D Program of China[grant number 2023YFC3008004]。
文摘This study introduces a new ocean surface friction velocity scheme and a modified Thompson cloud microphysics parameterization scheme into the CMA-TYM model.The impact of these two parameterization schemes on the prediction of the movement track and intensity of Typhoon Kompasu in 2021 is examined.Additionally,the possible reasons for their effects on tropical cyclone(TC)intensity prediction are analyzed.Statistical results show that both parameterization schemes improve the predictions of Typhoon Kompasu’s track and intensity.The influence on track prediction becomes evident after 60 h of model integration,while the significant positive impact on intensity prediction is observed after 66 h.Further analysis reveals that these two schemes affect the timing and magnitude of extreme TC intensity values by influencing the evolution of the TC’s warm-core structure.
基金Supported by the National Natural Science Foundation of China under Grant No.51975138the High-Tech Ship Scientific Research Project from the Ministry of Industry and Information Technology under Grant No.CJ05N20the National Defense Basic Research Project under Grant No.JCKY2023604C006.
文摘Marine thin plates are susceptible to welding deformation owing to their low structural stiffness.Therefore,the efficient and accurate prediction of welding deformation is essential for improving welding quality.The traditional thermal elastic-plastic finite element method(TEP-FEM)can accurately predict welding deformation.However,its efficiency is low because of the complex nonlinear transient computation,making it difficult to meet the needs of rapid engineering evaluation.To address this challenge,this study proposes an efficient prediction method for welding deformation in marine thin plate butt welds.This method is based on the coupled temperature gradient-thermal strain method(TG-TSM)that integrates inherent strain theory with a shell element finite element model.The proposed method first extracts the distribution pattern and characteristic value of welding-induced inherent strain through TEP-FEM analysis.This strain is then converted into the equivalent thermal load applied to the shell element model for rapid computation.The proposed method-particularly,the gradual temperature gradient-thermal strain method(GTG-TSM)-achieved improved computational efficiency and consistent precision.Furthermore,the proposed method required much less computation time than the traditional TEP-FEM.Thus,this study lays the foundation for future prediction of welding deformation in more complex marine thin plates.
文摘Instead of the capillary plasma generator(CPG),a discharge rod plasma generator(DRPG)is used in the30 mm electrothermal-chemical(ETC)gun to improve the ignition uniformity of the solid propellant.An axisymmetric two-dimensional interior ballistics model of the solid propellant ETC gun(2D-IB-SPETCG)is presented to describe the process of the ETC launch.Both calculated pressure and projectile muzzle velocity accord well with the experimental results.The feasibility of the 2D-IB-SPETCG model is proved.Depending on the experimental data and initial parameters,detailed distribution of the ballistics parameters can be simulated.With the distribution of pressure and temperature of the gas phase and the propellant,the influence of plasma during the ignition process can be analyzed.Because of the radial flowing plasma,the propellant in the area of the DRPG is ignited within 0.01 ms,while all propellant in the chamber is ignited within 0.09 ms.The radial ignition delay time is much less than the axial delay time.During the ignition process,the radial pressure difference is less than 5 MPa at the place 0.025 m away from the breech.The radial ignition uniformity is proved.The temperature of the gas increases from several thousand K(conventional ignition)to several ten thousand K(plasma ignition).Compare the distribution of the density and temperature of the gas,we know that low density and high temperature gas appears near the exits of the DRPG,while high density and low temperature gas appears at the wall near the breech.The simulation of the 2D-IB-SPETCG model is an effective way to investigate the interior ballistics process of the ETC launch.The 2D-IB-SPETC model can be used for prediction and improvement of experiments.
文摘Analysis of the environmental and economic performance of fishing vessels has received limited attention compared with other ship types despite their notable contribution to global greenhouse gas(GHG)emissions.This study evaluates the carbon footprint(CF)and economic viability of a liquefied natural gas(LNG)-fueled fishing vessel,using real engine operation simulations to provide precise and dynamic evaluation of fuel consumption and GHG emissions.Operational profiles are obtained through the utilization of onboard monitoring systems,whereas engine performance is simulated using the 1D/0D AVL Boost^(TM)model.Life cycle assessment(LCA)is conducted to quantify the environmental impact,whereas life cycle cost assessment(LCCA)is performed to analyze the profitability of LNG as an alternative fuel.The potential impact of the future fuel price uncertainties is addressed using Monte Carlo simulations.The LCA findings indicate that LNG has the potential to reduce the CF of the vessel by 14%to 16%,in comparison to a diesel power system configuration that serves as the baseline scenario.The LCCA results further indicate that the total cost of an LNG-powered ship is lower by 9.5%-13.8%,depending on the share of LNG and pilot fuels.This finding highlights the potential of LNG to produce considerable environmental benefits while addressing economic challenges under diverse operational and fuel price conditions.
文摘The paper establishes the relationship between the settling efficiency and the sizes of the sedimentation tank through the process of numerical simulation, which is taken as one of the constraints to set up a simple optimum designing model of sedimentation tank. The feasibility and advantages of this model based on numerical calculation are verified through the application of practical case.
基金the financial support of the National Natural Science Foundation of China(Nos.U2141221 and 52076136)the National Science and Technology Major Project,China(Nos.J2019-Ⅲ-0004-0047 and Y2022-Ⅲ-0001-0010)+1 种基金the Center for Basic Science of Aero Engines and Gas Turbines Project,China(No.P2022-B-Ⅱ019-001)the Natural Science Foundation of Shanghai,China(Nos.22ZR1467900 and 23ZR1481400)。
文摘This study systematically investigated the Lean Blowoff(LBO)limits of Two-Dimensional(2D)bluff-body stabilized premixed flames by varying the air mass flow rate,inflowtemperature,bluff-body width,and fuel type.The data of LBO limits were analyzed and fittedaccording to the Damk?hler(Da)and Reynolds(Re)numbers,and the fitting accuracy of LBO datawas highly improved by a modified characteristic length simultaneously considering the length andwidth of the bluff body,which is usually neglected in the previous studies.Moreover,to our knowl-edge,this is the first time that simultaneous transverse and spanwise OH*-Chemiluminescence(CL)imaging has been performed to examine the three-dimensional behavior of the LBO process.The flame stability is heavily affected by the mass and energy transport between reactants andproducts in both directions,potentially leading to the flame pinch-off.The intensity and positionof the upstream flame after pinch-off are decisive to the occurrence of the following LBO.Whenthe upstream flame after pinch-off is weak and close to the bluff body,it cannot re-ignite thedownstream unburnt gas.Subsequently,a permanent downstream extinction occurs,and theLBO takes place.The results help understand the LBO mechanism of 2D bluff-body stabilizedflames.
基金supported by the National Natural Science Foundation of China(No.10672064).
文摘A two-dimensional discrete dislocation dynamics （DDD） technology by Giessen and Needleman （1995）, which has been extended by integrating a dislocation-grain boundary interaction model, is used to computationally analyze the micro-cyclic plastic response of polycrystals containing micron-sized grains, with special attentions to significant influence of dislocationpenetrable grain boundaries （GBs） on the micro-plastic cyclic responses of polycrystals and underlying dislocation mechanism. Toward this end, a typical polycrystalline rectangular specimen under simple tension-compression loading is considered. Results show that, with the increase of cycle accumulative strain, continual dislocation accumulation and enhanced dislocation-dislocation interactions induce the cyclic hardening behavior; however, when a dynamic balance among dislocation nucleation, penetration through GB and dislocation annihilation is approximately established, cyclic stress gradually tends to saturate. In addition, other factors, including the grain size, cyclic strain amplitude and its history, also have considerable influences on the cyclic hardening and saturation.
基金Supported by the National Natural Science Foundation of China(21676136 and 21376116)A PAPD Project of Jiangsu Higher Education Institution
文摘Graphyne is expected to be a new-class of highly-efficient sieving membranes due to its controllable uniform pore structure and ultrathin single-atom thickness. Herein, we computationally investigate the permeation performance of liquid ethanol–water mixtures across polyporous two-dimensional γ-graphyne sheets. It was found that, in the mixture, ethanol with larger molecular diameter permeates faster through the graphyne pores than water. The simulations demonstrate that pristine graphynes could act as highly-efficient ethanol-permselective membranes for separation of ethanol–water mixtures, with ethanol permeability remarkably higher than conventional membranes. This separation mechanism is distinctly different from the molecular-size dependent sieving process. The stronger hydrophobic interfacial affinity between graphyne and ethanol makes ethanol molecules preferentially adsorb on graphyne surface and selectively penetrate through graphyne pores. This penetration mechanism provides new understanding of molecular transport through atomically thick two-dimensional nanoporous membranes and this work is expected to be valuable in the potential development of highly-efficient membranes for liquid-phase mixture separation.
文摘A numerical model has been developed for computing turbulent flow in plane-wall diffuser.The model solves the weakly compressible flow equations with the application of the Smagorinsky's subgrid-scale turbulence model and the boundary conditions of partial slip and no slip at the solid wall.Application examples include two-dimensional calculations of unstalled and stalled flows in diffusers of small diverging angle,as well as transitory stall flow in a symmetric diffuser of 16°total angle.For the unstalled and stalled flows,the calculated pressure recovery and velocity profile are compared with experimental data.For the transitory stall flow,the com- putational result shows the unsteady flow features including the vortex shedding and stall washout phenomena that have been experimentally observed.
