Electromagnetic absorbers(EMA) have driven the development of Electromagnetic(EM) technology and advanced EM devices. Utilizing the EM energy conversion of EM absorbers to design various devices is attractive and prom...Electromagnetic absorbers(EMA) have driven the development of Electromagnetic(EM) technology and advanced EM devices. Utilizing the EM energy conversion of EM absorbers to design various devices is attractive and promising, especially in personal protection and healthcare. In this review article, the simulation and numerical analysis of EM materials are reviewed, from numerical analysis of dielectric parameters, simulation of wave absorbing performance, electromagnetic performance improvement, and structural construction optimization. For the EM response mechanism, radiation-dependent relaxation and charge transport energy transitions are dissected. For the EM calculation section, two leading roles are highlighted, including the purposeful design of EM and the provision of theoretical guidance for optimizing electromagnetic absorption performance. In addition, this work points out the current problems and potential opportunities in the numerical simulation of absorbing materials, points out the new development direction, and proposes prospects.展开更多
The radial ultrasonic rolling electrochemical micromachining(RUR-EMM)combined rolling electrochemical micromachining(R-EMM)and ultrasonic vibration was studied in this paper.The fundamental understanding of the machin...The radial ultrasonic rolling electrochemical micromachining(RUR-EMM)combined rolling electrochemical micromachining(R-EMM)and ultrasonic vibration was studied in this paper.The fundamental understanding of the machining process especially the interaction between multiphysics in the interelectrode gap(IEG)was investigated and discussed by the finite element method.The multiphysics coupling model including flow field model,Joule heating model,material dissolution model and vibration model was built.3D multiphysics simulation based on micro dimples process in RUR-EMM and R-EMM was proposed.Simulation results showed that the electrolyte flowed into and out IEG periodically,gas bubbles were easy to squeeze out and the gas void fraction deceased about 16%to 54%,the maximum current density increased by 1.36 times in RUR-EMM than in R-EMM in one vibration period of time.And application of the ultrasonic vibration increased the electrolyte temperature about 1.3–4.4%in IEG.Verification experiments of the micro dimple process denoted better corrosion consistency of array dimples in RUR-EMM,there was no island at the micro dimple bottom which always formed in R-EMM,and an aggregated deviation of less than 8.7%for the micro dimple depth and 4%for the material removal amount between theory and experiment was obtained.展开更多
The corrosion behavior of B10 copper-nickel alloy welded joints in seawater pipeline system was analyzed under local turbulence induced by weld residual height.The corrosion behavior was evaluated by array electrode t...The corrosion behavior of B10 copper-nickel alloy welded joints in seawater pipeline system was analyzed under local turbulence induced by weld residual height.The corrosion behavior was evaluated by array electrode technology,mor-phology and elemental characterization,and COMSOL Multiphysics simulation.The results provide a theoretical basis for the corrosion and leakage of B10 alloy in seawater pipeline under the action of turbulence.The results show that residual height-induced turbulence exhibits a significant effect on the corrosion behavior in different areas of welded joints in B10 alloy.Turbulence can damage some surfaces,causing polarity deflection followed by acceleration of corrosion,or it is easier to form a protective film to slow down corrosion.COMSOL Multiphysics results show that the shear rate and turbulent kinetic energy increase linearly with the increase in residual height and velocity.The corrosion behavior of alloy surface is influenced by controlling the mass transfer rate and surface state.展开更多
Background: Skin aging is an unavoidable process aggravated by environmental agents. Among other energy devices, non-invasive radiofrequency (RF) technology is widely used for skin tightening and body contouring as it...Background: Skin aging is an unavoidable process aggravated by environmental agents. Among other energy devices, non-invasive radiofrequency (RF) technology is widely used for skin tightening and body contouring as it is simpler and more affordable than other technologies that also minimize pain and side-effects. However, most of the current RF devices do not provide automatic skin temperature control and it is difficult to achieve controlled, deep, and harmless thermal increase, so treatment performance and safety is dependent on the operator’s movements and expertise. Objective: To show the potential of numerical simulations for optimizing the design of monopolar and bipolar RF electrodes that are capable of providing homogeneous, deep and controlled heating. Materials and methods: In-silico models were developed and analyzed using Comsol Multiphysics software to simulate the RF effect produced in tissue by rotating monopolar and bipolar electrodes with different geometries from the Sculpt & Shape RF device (Sinclair, Spain), operating at frequencies of 0.5 and 1 MHz. Ex-vivo and in-vivo proof-of-concept tests were carried out to validate the simulations. Finally, treatments were performed on 16 subjects and a total of 78 body areas to assess the clinical results generated by the RF electrodes for skin tightening and body contouring. Results: In-silico studies emulated the superficial and deep dispersion of heat due to the release of RF energy into human skin tissue. The rotating electrodes (monopolar and bipolar) and the selected RF frequency (0.5 and 1 MHz) determined the homogeneity of the thermal distribution, the penetration depth (between 4.37 mm and 25.0 mm) and the heating dynamics (between 30 and 100 seconds to reach the target skin temperature), which were confirmed by ex-vivo and in-vivo tests. In addition, real treatments on facial and body areas using skin temperatures of between 43˚C and 44˚C showed consistent results with good clinical efficacy for skin tightening, circumference reduction and cellulite reduction, with no adverse effects and high subject satisfaction. Conclusions: New monopolar and bipolar RF electrodes with rotating technology have been designed and optimized using numerical simulations. The use of in-silico studies and accurate models that reproduce the thermal behavior of human biological tissues can be used to better understand RF devices and to develop superior, efficient, and safer products more quickly.展开更多
This study proposes and systematically evaluates an optimized integration of warm surface seawater injection with depressurization for the long-term exploitation of marine natural gas hydrates.By employing comprehensi...This study proposes and systematically evaluates an optimized integration of warm surface seawater injection with depressurization for the long-term exploitation of marine natural gas hydrates.By employing comprehensive multiphysics simulations guided by field data from hydrate production tests in the South China Sea,we pinpoint key operational parameters—such as injection rates,depths,and timings—that notably enhance production efficiency.The results indicate that a 3-phase hydrate reservoir transitions from a free-gas-dominated production stage to a hydrate-decomposition-dominated stage.Moderate warm seawater injection supplies additional heat during the hydrate decomposition phase,thereby enhancing stable production;however,excessively high injection rates can impede the depressurization process.Only injection at an appropriate depth simultaneously balances thermal supplementation and the pressure gradient,leading to higher overall productivity.A“depressurization-driven sensible-heat supply window”is introduced,highlighting that timely seawater injection following initial depressurization prolongs reservoir dissociation dynamics.In this study area,commencing seawater injection at 170 d of depressurization proved optimal.This optimized integration leverages clean and renewable thermal energy,providing essential insights into thermal supplementation strategies with significant implications for sustainable,economically feasible,and efficient commercial-scale hydrate production.展开更多
The high costs of the currently used membranes in vanadium redox flow batteries(VRFBs)contribute to the price of the vanadium redox flow battery systems and therefore limit the market share of the VRFBs.Here we report...The high costs of the currently used membranes in vanadium redox flow batteries(VRFBs)contribute to the price of the vanadium redox flow battery systems and therefore limit the market share of the VRFBs.Here we report a detailed simulation and experimental studies on the effect of membrane reduction of single-cell VRFB.Different simulated designs demonstrate that a proposed centred and double-strip membrane coverage showed a promising performance.Experimental charge-discharge profile of different membrane size reduction,which showed good agreement with simulated data,suggests that the membrane size can comfortably be reduced by up to 20%without severe efficiency or discharge capacity loss.Long-term cycling of 80%centred membrane coverage showed improved capacity retention during the latter cycles with almost 1%difference in capacity and only 2%in energy efficiency when compared to the fully covered-membrane cell.The results hold great promise for the development of cheap RFB stacks and facilitate the way to develop new cell designs with non-overlapping electrodes geometry.Therefore,giving more flexibility to improve the overall performance of the system.展开更多
The effectiveness of breast cancer ablation by radiofrequency (RF) has been associated to the capacity of concentrating the electromagnetic energy in the tumor region, our group has proposed that this condition could ...The effectiveness of breast cancer ablation by radiofrequency (RF) has been associated to the capacity of concentrating the electromagnetic energy in the tumor region, our group has proposed that this condition could be modulated by appropriate RF exposure cycle times as well as modification of tissue electrical conductivity. The aim of this work was to evaluate analytical and experimental optimal exposure cycle times to induce tissue ablation by RF assisted with magnetic nanoparticles. The study was conducted both analytically by multiphysics simulation of the induced currents in cancer tissue given a magnetron source and experimentally by the observation of hyperthermic effects induced in agar phantoms by a magnetron device by the use of RF assisted with magnetic nanoparticles. The temperature showed significant increases in short periods of time, and was clearly higher under the condition with nanoparticles. Appropriate RF exposure cycle times as well as modification of tissue electrical conductivity by magnetic nanoparticles seems suitable factors to modulate the electromagnetic energy in tumoral regions.展开更多
Laser electrochemical machining is an innovative composite processing method,achieving high surface quality and efficient shaping for difficult-to-machine materials through the combined effects of laser and electroche...Laser electrochemical machining is an innovative composite processing method,achieving high surface quality and efficient shaping for difficult-to-machine materials through the combined effects of laser and electrochemical energy.Electrochemical machining adjusts the parameters of the physical field to eliminate the recast layer generated by laser ablation.In addition,the increase in electrolyte temperature caused by the laser can promote electrochemical dissolution.This work proposed a new multiphysics simulation model to explore the structure formation mechanism based on the temporal variations of temperature,electric,and flow fields during composite processing.The laser-coupled electrochemical machining used a three-current model.The temperature field variation considered not only the laser irradiation factor but also the effect of convective heat transfer induced by fluid flow.Moreover,temperature variation influences electric and flow fields,changing the physical parameters of electrolytes,such as conductivity and dynamic viscosity.Transient deformation geometry was used to uncover the material removal process during composite machining and then predict the final profile of the obtained structures.The manufacturing process could be elaborately described by the multiple physical fields using the established simulation model.Finally,an experimental study was conducted to validate the reasonability of the proposed simulation model.The role of laser effects in composite machining was also highlighted through the comparison of theoretical and experimental results.展开更多
The evolution of coronavirus disease(COVID-19)into a pandemic has severely hampered the usage of public transit systems.In a post-COVID-19 world,we may see an increased reliance on autonomous cars and personal rapid t...The evolution of coronavirus disease(COVID-19)into a pandemic has severely hampered the usage of public transit systems.In a post-COVID-19 world,we may see an increased reliance on autonomous cars and personal rapid transit(PRT)systems,with inherent physical distancing,over buses,trains and aircraft for intracity,intercity,and interstate travel.However,air travel would continue to be the dominant mode of intercontinental transportation for humans.In this study,we perform a comprehensive computational analysis,using ANSYS Fluent,of typical intercontinental aircraft ventilation systems to determine the seat where environmental factors are most conducive to human comfort with regards to air quality,protection from orally or nasally released pollutants such as CO_(2)and coronavirus,and thermal comfort levels.Air velocity,temperature,and air pollutant concentration emitted from the nose/mouth of fellow travelers are considered for both Boeing and Airbus planes.In each plane,first class,business class,and economy class sections were analyzed.We present conclusions as to which is the optimum seat in each section of each plane and provide the data of the environmental conditions to support our inferences.The findings may be used by the general public to decide which seat to occupy for their next intercontinental flight.Alternatively,the commercial airliners can use such a model to plan the occupancy of the aircraft on long-duration intercontinental flights(viz.,Airbus A380 and Boeing B747).展开更多
This paper is the second part of a two part sequence on multiphysics algorithms and software.The first[1]focused on the algorithms;this part treats the multiphysics software framework and applications based on it.Tigh...This paper is the second part of a two part sequence on multiphysics algorithms and software.The first[1]focused on the algorithms;this part treats the multiphysics software framework and applications based on it.Tight coupling is typically designed into the analysis application at inception,as such an application is strongly tied to a composite nonlinear solver that arrives at the final solution by treating all equations simultaneously.The applicationmust also take care tominimize both time and space error between the physics,particularly if more than one mesh representation is needed in the solution process.This paper presents an application framework that was specifically designed to support tightly coupled multiphysics analysis.The Multiphysics Object Oriented Simulation Environment(MOOSE)is based on the Jacobian-freeNewton-Krylov(JFNK)method combined with physics-based preconditioning to provide the underlying mathematical structure for applications.The report concludes with the presentation of a host of nuclear,energy,and environmental applications that demonstrate the efficacy of the approach and the utility of a well-designed multiphysics framework.展开更多
There is a growing trend within energy and environmental simulation to consider tightly coupled solutions to multiphysics problems.This can be seen in nuclear reactor analysis where analysts are interested in coupled ...There is a growing trend within energy and environmental simulation to consider tightly coupled solutions to multiphysics problems.This can be seen in nuclear reactor analysis where analysts are interested in coupled flow,heat transfer and neutronics,and in nuclear fuel performance simulation where analysts are interested in thermomechanics with contact coupled to species transport and chemistry.In energy and environmental applications,energy extraction involves geomechanics,flow through porous media and fractured formations,adding heat transport for enhanced oil recovery and geothermal applications,and adding reactive transport in the case of applications modeling the underground flow of contaminants.These more ambitious simulations usually motivate some level of parallel computing.Many of the physics coupling efforts to date utilize simple code coupling or first-order operator splitting,often referred to as loose coupling.While these approaches can produce answers,they usually leave questions of accuracy and stability unanswered.Additionally,the different physics often reside on distinct meshes and data are coupled via simple interpolation,again leaving open questions of stability and accuracy.∗Corresponding author.Email addresses:Derek.Gaston@inl.gov(D.Gaston),This paper is the first part of a two part sequence on multiphysics algorithms and software.Part I examines the importance of accurate time and space integration and that the degree of coupling used for the solution should match the requirements of the simulation.It then discusses the preconditioned Jacobian-free Newton Krylov solution algorithm that is used for both multiphysics and multiscale solutions.Part II[1]presents the software framework;the Multiphysics Object Oriented Simulation Environment(MOOSE)and discusses applications based on it.展开更多
The utilization of environmentally friendly hydrogen energy requires proton exchange membrane fuel cell de-vices that offer high power output while remaining affordable.However,the current optimization of their key co...The utilization of environmentally friendly hydrogen energy requires proton exchange membrane fuel cell de-vices that offer high power output while remaining affordable.However,the current optimization of their key component,i.e.,the membrane electrode assembly,is still based on intuition-guided,inefficient trial-and-error cycles due to its complexity.Hence,we introduce an innovative,explainable artificial intelligence(AI)tool trained as a reliable assistant for a variable analysis and optimum-value prediction.Among the 8 algorithms considered,the surrogate model built with an artificial neural network achieves high replaceability in the experimentally validated multiphysics simulation(R^(2)=0.99845)and a much lower computational cost.For interpretation,partial dependence plots and the Shapley value method are applied to black-box models to intelligently simulate the impact of each parameter on performance.These methods show that a tradeoff existed in the catalyst layer thickness.The AI-guided optimization suggestions regarding catalyst loading and the ion-omer content are fully supported by the experimental results,and the final product achieves 3.2 times the Pt utilization of commercial products with a time cost orders of magnitude smaller.展开更多
基金supported by the National Natural Science Foundation of China (Nos.51772060and 51972078)the Key Laboratory of Advanced Structural Functional Integration Materials&Green Manufacturing Technology,Harbin Institute of Technology,Harbin,150001,China。
文摘Electromagnetic absorbers(EMA) have driven the development of Electromagnetic(EM) technology and advanced EM devices. Utilizing the EM energy conversion of EM absorbers to design various devices is attractive and promising, especially in personal protection and healthcare. In this review article, the simulation and numerical analysis of EM materials are reviewed, from numerical analysis of dielectric parameters, simulation of wave absorbing performance, electromagnetic performance improvement, and structural construction optimization. For the EM response mechanism, radiation-dependent relaxation and charge transport energy transitions are dissected. For the EM calculation section, two leading roles are highlighted, including the purposeful design of EM and the provision of theoretical guidance for optimizing electromagnetic absorption performance. In addition, this work points out the current problems and potential opportunities in the numerical simulation of absorbing materials, points out the new development direction, and proposes prospects.
基金financial support of the projects from the National Natural Science Foundation of China(Nos.51975532 and 51475428)the Zhejiang Provincial Natural Science Foundation(No.LY19E050007)。
文摘The radial ultrasonic rolling electrochemical micromachining(RUR-EMM)combined rolling electrochemical micromachining(R-EMM)and ultrasonic vibration was studied in this paper.The fundamental understanding of the machining process especially the interaction between multiphysics in the interelectrode gap(IEG)was investigated and discussed by the finite element method.The multiphysics coupling model including flow field model,Joule heating model,material dissolution model and vibration model was built.3D multiphysics simulation based on micro dimples process in RUR-EMM and R-EMM was proposed.Simulation results showed that the electrolyte flowed into and out IEG periodically,gas bubbles were easy to squeeze out and the gas void fraction deceased about 16%to 54%,the maximum current density increased by 1.36 times in RUR-EMM than in R-EMM in one vibration period of time.And application of the ultrasonic vibration increased the electrolyte temperature about 1.3–4.4%in IEG.Verification experiments of the micro dimple process denoted better corrosion consistency of array dimples in RUR-EMM,there was no island at the micro dimple bottom which always formed in R-EMM,and an aggregated deviation of less than 8.7%for the micro dimple depth and 4%for the material removal amount between theory and experiment was obtained.
基金support from the National Natural Science Foundation of China(Grant No.42176209)the Natural Science Foundation of Shandong Province(Grant No.ZR2021MD064)the Fundamental Research Funds for the Central Universities(Grant No.19CX05001A).
文摘The corrosion behavior of B10 copper-nickel alloy welded joints in seawater pipeline system was analyzed under local turbulence induced by weld residual height.The corrosion behavior was evaluated by array electrode technology,mor-phology and elemental characterization,and COMSOL Multiphysics simulation.The results provide a theoretical basis for the corrosion and leakage of B10 alloy in seawater pipeline under the action of turbulence.The results show that residual height-induced turbulence exhibits a significant effect on the corrosion behavior in different areas of welded joints in B10 alloy.Turbulence can damage some surfaces,causing polarity deflection followed by acceleration of corrosion,or it is easier to form a protective film to slow down corrosion.COMSOL Multiphysics results show that the shear rate and turbulent kinetic energy increase linearly with the increase in residual height and velocity.The corrosion behavior of alloy surface is influenced by controlling the mass transfer rate and surface state.
文摘Background: Skin aging is an unavoidable process aggravated by environmental agents. Among other energy devices, non-invasive radiofrequency (RF) technology is widely used for skin tightening and body contouring as it is simpler and more affordable than other technologies that also minimize pain and side-effects. However, most of the current RF devices do not provide automatic skin temperature control and it is difficult to achieve controlled, deep, and harmless thermal increase, so treatment performance and safety is dependent on the operator’s movements and expertise. Objective: To show the potential of numerical simulations for optimizing the design of monopolar and bipolar RF electrodes that are capable of providing homogeneous, deep and controlled heating. Materials and methods: In-silico models were developed and analyzed using Comsol Multiphysics software to simulate the RF effect produced in tissue by rotating monopolar and bipolar electrodes with different geometries from the Sculpt & Shape RF device (Sinclair, Spain), operating at frequencies of 0.5 and 1 MHz. Ex-vivo and in-vivo proof-of-concept tests were carried out to validate the simulations. Finally, treatments were performed on 16 subjects and a total of 78 body areas to assess the clinical results generated by the RF electrodes for skin tightening and body contouring. Results: In-silico studies emulated the superficial and deep dispersion of heat due to the release of RF energy into human skin tissue. The rotating electrodes (monopolar and bipolar) and the selected RF frequency (0.5 and 1 MHz) determined the homogeneity of the thermal distribution, the penetration depth (between 4.37 mm and 25.0 mm) and the heating dynamics (between 30 and 100 seconds to reach the target skin temperature), which were confirmed by ex-vivo and in-vivo tests. In addition, real treatments on facial and body areas using skin temperatures of between 43˚C and 44˚C showed consistent results with good clinical efficacy for skin tightening, circumference reduction and cellulite reduction, with no adverse effects and high subject satisfaction. Conclusions: New monopolar and bipolar RF electrodes with rotating technology have been designed and optimized using numerical simulations. The use of in-silico studies and accurate models that reproduce the thermal behavior of human biological tissues can be used to better understand RF devices and to develop superior, efficient, and safer products more quickly.
基金supported by the National Key R&D Program of China(No.2024YFB4206700)the Joint Geological Funds of the National Natural Science Foundation of China(No.U2244223)+5 种基金the China Scholarship Council Program(No.202404910533)the Guangdong Major Project of Basic and Applied Basic Research(No.2020B0301030003)the China Geological Survey Project(No.DD20211350)the Key Deployment Program of Chinese Academy of Sciences(Nos.YJKYYQ20190043,ZDBS-LY-DQC003,KFZD-SW-422,and ZDRW-ZS-2021-3-1)the Scientific Research and Technology Development Project of China National Petroleum Corporation(No.2022DJ5503)the Supercomputing Laboratory,IGGCAS.
文摘This study proposes and systematically evaluates an optimized integration of warm surface seawater injection with depressurization for the long-term exploitation of marine natural gas hydrates.By employing comprehensive multiphysics simulations guided by field data from hydrate production tests in the South China Sea,we pinpoint key operational parameters—such as injection rates,depths,and timings—that notably enhance production efficiency.The results indicate that a 3-phase hydrate reservoir transitions from a free-gas-dominated production stage to a hydrate-decomposition-dominated stage.Moderate warm seawater injection supplies additional heat during the hydrate decomposition phase,thereby enhancing stable production;however,excessively high injection rates can impede the depressurization process.Only injection at an appropriate depth simultaneously balances thermal supplementation and the pressure gradient,leading to higher overall productivity.A“depressurization-driven sensible-heat supply window”is introduced,highlighting that timely seawater injection following initial depressurization prolongs reservoir dissociation dynamics.In this study area,commencing seawater injection at 170 d of depressurization proved optimal.This optimized integration leverages clean and renewable thermal energy,providing essential insights into thermal supplementation strategies with significant implications for sustainable,economically feasible,and efficient commercial-scale hydrate production.
文摘The high costs of the currently used membranes in vanadium redox flow batteries(VRFBs)contribute to the price of the vanadium redox flow battery systems and therefore limit the market share of the VRFBs.Here we report a detailed simulation and experimental studies on the effect of membrane reduction of single-cell VRFB.Different simulated designs demonstrate that a proposed centred and double-strip membrane coverage showed a promising performance.Experimental charge-discharge profile of different membrane size reduction,which showed good agreement with simulated data,suggests that the membrane size can comfortably be reduced by up to 20%without severe efficiency or discharge capacity loss.Long-term cycling of 80%centred membrane coverage showed improved capacity retention during the latter cycles with almost 1%difference in capacity and only 2%in energy efficiency when compared to the fully covered-membrane cell.The results hold great promise for the development of cheap RFB stacks and facilitate the way to develop new cell designs with non-overlapping electrodes geometry.Therefore,giving more flexibility to improve the overall performance of the system.
文摘The effectiveness of breast cancer ablation by radiofrequency (RF) has been associated to the capacity of concentrating the electromagnetic energy in the tumor region, our group has proposed that this condition could be modulated by appropriate RF exposure cycle times as well as modification of tissue electrical conductivity. The aim of this work was to evaluate analytical and experimental optimal exposure cycle times to induce tissue ablation by RF assisted with magnetic nanoparticles. The study was conducted both analytically by multiphysics simulation of the induced currents in cancer tissue given a magnetron source and experimentally by the observation of hyperthermic effects induced in agar phantoms by a magnetron device by the use of RF assisted with magnetic nanoparticles. The temperature showed significant increases in short periods of time, and was clearly higher under the condition with nanoparticles. Appropriate RF exposure cycle times as well as modification of tissue electrical conductivity by magnetic nanoparticles seems suitable factors to modulate the electromagnetic energy in tumoral regions.
基金supported by National Key R&D Program of China(No.2021YFF0500203)National Natural Science Foundation of China(No.52405561)Open Research Fund of State Key Laboratory of Precision Manufacturing for Extreme Service Performance(Kfkt2024-02).
文摘Laser electrochemical machining is an innovative composite processing method,achieving high surface quality and efficient shaping for difficult-to-machine materials through the combined effects of laser and electrochemical energy.Electrochemical machining adjusts the parameters of the physical field to eliminate the recast layer generated by laser ablation.In addition,the increase in electrolyte temperature caused by the laser can promote electrochemical dissolution.This work proposed a new multiphysics simulation model to explore the structure formation mechanism based on the temporal variations of temperature,electric,and flow fields during composite processing.The laser-coupled electrochemical machining used a three-current model.The temperature field variation considered not only the laser irradiation factor but also the effect of convective heat transfer induced by fluid flow.Moreover,temperature variation influences electric and flow fields,changing the physical parameters of electrolytes,such as conductivity and dynamic viscosity.Transient deformation geometry was used to uncover the material removal process during composite machining and then predict the final profile of the obtained structures.The manufacturing process could be elaborately described by the multiple physical fields using the established simulation model.Finally,an experimental study was conducted to validate the reasonability of the proposed simulation model.The role of laser effects in composite machining was also highlighted through the comparison of theoretical and experimental results.
文摘The evolution of coronavirus disease(COVID-19)into a pandemic has severely hampered the usage of public transit systems.In a post-COVID-19 world,we may see an increased reliance on autonomous cars and personal rapid transit(PRT)systems,with inherent physical distancing,over buses,trains and aircraft for intracity,intercity,and interstate travel.However,air travel would continue to be the dominant mode of intercontinental transportation for humans.In this study,we perform a comprehensive computational analysis,using ANSYS Fluent,of typical intercontinental aircraft ventilation systems to determine the seat where environmental factors are most conducive to human comfort with regards to air quality,protection from orally or nasally released pollutants such as CO_(2)and coronavirus,and thermal comfort levels.Air velocity,temperature,and air pollutant concentration emitted from the nose/mouth of fellow travelers are considered for both Boeing and Airbus planes.In each plane,first class,business class,and economy class sections were analyzed.We present conclusions as to which is the optimum seat in each section of each plane and provide the data of the environmental conditions to support our inferences.The findings may be used by the general public to decide which seat to occupy for their next intercontinental flight.Alternatively,the commercial airliners can use such a model to plan the occupancy of the aircraft on long-duration intercontinental flights(viz.,Airbus A380 and Boeing B747).
文摘This paper is the second part of a two part sequence on multiphysics algorithms and software.The first[1]focused on the algorithms;this part treats the multiphysics software framework and applications based on it.Tight coupling is typically designed into the analysis application at inception,as such an application is strongly tied to a composite nonlinear solver that arrives at the final solution by treating all equations simultaneously.The applicationmust also take care tominimize both time and space error between the physics,particularly if more than one mesh representation is needed in the solution process.This paper presents an application framework that was specifically designed to support tightly coupled multiphysics analysis.The Multiphysics Object Oriented Simulation Environment(MOOSE)is based on the Jacobian-freeNewton-Krylov(JFNK)method combined with physics-based preconditioning to provide the underlying mathematical structure for applications.The report concludes with the presentation of a host of nuclear,energy,and environmental applications that demonstrate the efficacy of the approach and the utility of a well-designed multiphysics framework.
文摘There is a growing trend within energy and environmental simulation to consider tightly coupled solutions to multiphysics problems.This can be seen in nuclear reactor analysis where analysts are interested in coupled flow,heat transfer and neutronics,and in nuclear fuel performance simulation where analysts are interested in thermomechanics with contact coupled to species transport and chemistry.In energy and environmental applications,energy extraction involves geomechanics,flow through porous media and fractured formations,adding heat transport for enhanced oil recovery and geothermal applications,and adding reactive transport in the case of applications modeling the underground flow of contaminants.These more ambitious simulations usually motivate some level of parallel computing.Many of the physics coupling efforts to date utilize simple code coupling or first-order operator splitting,often referred to as loose coupling.While these approaches can produce answers,they usually leave questions of accuracy and stability unanswered.Additionally,the different physics often reside on distinct meshes and data are coupled via simple interpolation,again leaving open questions of stability and accuracy.∗Corresponding author.Email addresses:Derek.Gaston@inl.gov(D.Gaston),This paper is the first part of a two part sequence on multiphysics algorithms and software.Part I examines the importance of accurate time and space integration and that the degree of coupling used for the solution should match the requirements of the simulation.It then discusses the preconditioned Jacobian-free Newton Krylov solution algorithm that is used for both multiphysics and multiscale solutions.Part II[1]presents the software framework;the Multiphysics Object Oriented Simulation Environment(MOOSE)and discusses applications based on it.
基金This work was partially supported by the National Key R&D Plan of China[2019YFB1504503]the National Natural Science Foundation of China[21802069]the Key R&D plan of Zhejiang Province[2020C01006].The database generation from the multiphysics simu-lation model was performed at the High-Performance Computing Center of the Collaborative Innovation Center of Advanced Microstructures,Collaborative Innovation Center of Advanced Microstructures,Nanjing University,Nanjing 210,093,China.
文摘The utilization of environmentally friendly hydrogen energy requires proton exchange membrane fuel cell de-vices that offer high power output while remaining affordable.However,the current optimization of their key component,i.e.,the membrane electrode assembly,is still based on intuition-guided,inefficient trial-and-error cycles due to its complexity.Hence,we introduce an innovative,explainable artificial intelligence(AI)tool trained as a reliable assistant for a variable analysis and optimum-value prediction.Among the 8 algorithms considered,the surrogate model built with an artificial neural network achieves high replaceability in the experimentally validated multiphysics simulation(R^(2)=0.99845)and a much lower computational cost.For interpretation,partial dependence plots and the Shapley value method are applied to black-box models to intelligently simulate the impact of each parameter on performance.These methods show that a tradeoff existed in the catalyst layer thickness.The AI-guided optimization suggestions regarding catalyst loading and the ion-omer content are fully supported by the experimental results,and the final product achieves 3.2 times the Pt utilization of commercial products with a time cost orders of magnitude smaller.
