It is regretful that the Acknowledgments part was lost in the final process of publication.The Acknowledgments part should be added as follow.The work described in this paper was supported by the grants from the Resea...It is regretful that the Acknowledgments part was lost in the final process of publication.The Acknowledgments part should be added as follow.The work described in this paper was supported by the grants from the Research Grants Council of the Hong Kong Special Administrative Region,China(Project No.16205721).展开更多
The activation of CO on iron-based materials is a key elementary reaction for many chemical processes.We investigate CO adsorption and dissociation on a series of Fe,Fe_(3)C,Fe_(5)C_(2),and Fe_(2)C catalysts through d...The activation of CO on iron-based materials is a key elementary reaction for many chemical processes.We investigate CO adsorption and dissociation on a series of Fe,Fe_(3)C,Fe_(5)C_(2),and Fe_(2)C catalysts through density functional theory calculations.We detect dramatically different performances for CO adsorption and activation on diverse surfaces and sites.The activation of CO is dependent on the local coordination of the molecule to the surface and on the bulk phase of the underlying catalyst.The bulk properties and the different local bonding environments lead to varying interactions between the adsorbed CO and the surface and thus yielding different activation levels of the C-O bond.We also examine the prediction of CO adsorption on different types of Fe-based catalysts by machine learning through linear regression models.We combine the features originating from surfaces and bulk phases to enhance the prediction of the activation energies and perform eight different linear regressions utilizing the feature engineering of polynomial representations.Among them,a ridge linear regression model with2nd-degree polynomial feature generation predicted the best CO activation energy with a mean absolute error of 0.269 eV.展开更多
Featuring low cost, high abundance, low electrochemical potential, and large specific capacity, zinc(Zn)metal holds great potential as an anode material for next-generation rechargeable aqueous batteries.However, the ...Featuring low cost, high abundance, low electrochemical potential, and large specific capacity, zinc(Zn)metal holds great potential as an anode material for next-generation rechargeable aqueous batteries.However, the poor reversibility resulting from dendrite formation and side reactions poses a major obstacle for its practical application. Electrolyte, which is regarded as the “blood” of batteries, has a direct impact on reaction kinetics, mass transport, and side reactions and thus plays a key role in determining the electrochemical performance of Zn electrodes. Therefore, considerable efforts have been devoted to modulating the electrolytes to improve the performance of Zn electrodes. Although significant progress has been made, achieving stable and highly reversible Zn electrodes remains a critical challenge. This review aims to provide a systematic summary and discussion on electrolyte strategies for highperformance aqueous Zn batteries. The(electro)-chemical behavior and fundamental challenges of Zn electrodes in aqueous electrolytes are first discussed. Electrolyte modulation strategies developed to address these issues are then classified and elaborated according to the underlying mechanisms.Finally, remaining challenges and promising future research directions on aqueous electrolyte engineering are highlighted. This review offers insights into the design of highly efficient electrolytes for new generation of rechargeable Zn batteries.展开更多
The photothermal self-driving process of Janus microparticles has wide application prospects in the fields of biomedicine.Since silica and gold have good biocompatibility and high photothermal conversion efficiency,th...The photothermal self-driving process of Janus microparticles has wide application prospects in the fields of biomedicine.Since silica and gold have good biocompatibility and high photothermal conversion efficiency,the SiO_(2)@Au Janus microparticles are widely used as drug carriers.Based on the multiphysics coupling method,the photothermal self-driving process of SiO_(2)@Au Janus microparticles was investi-gated,wherein the substrate was SiO_(2)particles and one side of the particles was coated with gold film.Under a continuous wave laser with irradiation of 20 W/cm^(2),the distance covered by the Janus particles was increased by increasing the thickness of the gold film and reducing the size of the SiO_(2)particles;the self-driving characteristics of the Janus particles were controlled substantially by increasing the intensity of the incident laser.Based on the simulation results,the thermophoretic motion and Brownian motion of particles can be measured by comparing the absolute values of the thermophoretic force impulse,Brownian force impulse,and drag force impulse.The Brownian force acting on Janus microparticles under low laser power cannot be ignored.Furthermore,the minimum laser power required for Janus particles to overcome Brownian motion was calculated.The results can effectively guide the design of Janus particles in biomedicine and systematically analyze the mechanism of particle thermophoretic motion during drug delivery.展开更多
In this paper,a 3D meta-atom-based structure is constructed for the multifunctional compatible design of visible,infrared,and microwave.To achieve high performance,a novel dispersion tailoring strategy is proposed.Thr...In this paper,a 3D meta-atom-based structure is constructed for the multifunctional compatible design of visible,infrared,and microwave.To achieve high performance,a novel dispersion tailoring strategy is proposed.Through the incorporation of multiple controllable losses within the 3D meta-atom,the dispersion characteristics are tailored to the desired target region.The effectiveness of the strategy is verified with an error rate of less than5%.A proof-of-concept prototype is designed and fabricated,exhibiting high visible transparency,low infrared emission of 0.28,and microwave ultra-broadband absorption with a fractional bandwidth of 150%under 2.7 to18.7 GHz.This work contributes a novel design strategy for the development of high-performance multispectral stealth materials with wide applications.展开更多
This paper is concerned with the forced convective heat transfer of dilute liquid suspensions of nanoparticles (nanofluids) flowing through a straight pipe under laminar conditions. Stable nanofluids are formulated ...This paper is concerned with the forced convective heat transfer of dilute liquid suspensions of nanoparticles (nanofluids) flowing through a straight pipe under laminar conditions. Stable nanofluids are formulated by using the high shear mixing and ultrasonication methods. They are then characterised for their size, surface charge,thermal and rheological properties and tested for their convective heat transfer behaviour. Mathematical modelling is performed to simulate the convective heat transfer of nanofluids using a single phase flow model and considering nanofluids as both Newtonian and non-Newtonian fluid. Both experiments and mathematical modelling show that nanofluids can substantially enhance the convective heat transfer. Analyses of the results suggest that the non-Newtonian character of nanofluids influences the overall enhancement, especially for nanofluids with an obvious non-Newtonian character.展开更多
Compared to traditional optical domes, domes of sapphire coated with films can effectively reduce emissivity and increase transmittance. The purpose of this work is to investigate the thermal radiation effect on sapph...Compared to traditional optical domes, domes of sapphire coated with films can effectively reduce emissivity and increase transmittance. The purpose of this work is to investigate the thermal radiation effect on sapphire optical dome coated with yttrium oxide by a radio frequency mag- netron sputtering method. The emissivity of sapphire coated with Y203 films is studied by both numerical and experi- mental methods. The results indicate that the emissivity of sapphire substrate is reduced effectively with increasing the thickness of the Y203 film. In addition, a finite element model is developed to simulate the radiation intensity of the optical dome. The thermal responses indicate that the max- imum temperature is reduced apparently compared with the uncoated sapphire as Y203 film thicknesses increase. The average irradiance distribution at different film thicknesses with time shows that the self-thermal radiation disturbance of sapphire optical dome delays 0.93 s when the thickness of Y203 film is 200μm, which can guarantee the dome works properly and effectively even in a harsh environment.展开更多
Size-controlled hollow Fe3O4 nanospheres were synthesized via a one-pot hydrothermal method as a function of reaction time and sodium citrate,polyacrylamide,and urea content.Multiple characterization techniques such a...Size-controlled hollow Fe3O4 nanospheres were synthesized via a one-pot hydrothermal method as a function of reaction time and sodium citrate,polyacrylamide,and urea content.Multiple characterization techniques such as scanning and transmission electron microscopy and Raman spectroscopy were employed to investigate the crystal structure and morphology of the obtained nanospheres.The Fe3O4 nanosphere formation mechanism was elucidated from analyzing the characterization data.High levels of sodium citrate and longer reaction times were observed to increase the diameter of the nanospheres until hollow structures formed.Furthermore,polyacrylamide and urea promoted the formation of hollow structures.The hollow-structured Fe3O4 nanospheres exhibited high magnetization saturation values in the range of 48.8-58.7 emu/g.The facile synthesis method described herein,to generate size-controlled Fe3O4 nanospheres with tailored properties,demonstrates potential across a wide range of fields from drug-delivery and stealth devices,to environmental and energy applications.展开更多
This paper presents a flexible radio-frequency microelectromechanical system(RF MEMS)switch integrated on cyclo-olefin polymer(COP)substrate using a modified surface MEMS processing technology,which could be used in t...This paper presents a flexible radio-frequency microelectromechanical system(RF MEMS)switch integrated on cyclo-olefin polymer(COP)substrate using a modified surface MEMS processing technology,which could be used in the 17-19 GHz frequency band of satellite communication.Through systematic simulation analysis,it is found that flexible RF MEMS switch can achieve certain bending radius by miniaturizing the electronic dimension,without degrading the RF performance.It is demonstrated that the RF characteristics of flexible RF MEMS switch with special anchor structural design,fabricated by modified surface MEMS processing,are not sensitive to bending deformation under the curvature of 0 mm^(-1),0.05 mm^(-1),0.10 mm^(-1).Furthermore,the range of bending curvature which will affect the RF characteristics is given through systematic simulation.The flexible RF MEMS switch with high process compatibility and stable RF performance is believed to be promising candidates for future microwave communications and other consumer electronics.展开更多
In this work, a discrete particle model (DPM) was applied to investigate the dynamic characteristics in a gas-solid bubbling fluidized bed of binary solid particles. The solid phase was simulated by the hard- sphere...In this work, a discrete particle model (DPM) was applied to investigate the dynamic characteristics in a gas-solid bubbling fluidized bed of binary solid particles. The solid phase was simulated by the hard- sphere discrete particle model. The large eddy simulation (LES) method was used to simulate the gas phase. To improve the accuracy of the simulation, an improved sub-grid scale (SGS) model in the LES method was also applied. The mutative Smagorinsky constant case was compared with the previously published experimental data. The simulation by the mutative Smagorinsky constant model exhibited better agreement with the experimental data than that by the common invariant Smagorinsky constant model. Various restitution coefficients and different compositions of binary solids were investigated to determine their influences on the rotation characteristics and granular temperatures of the particles. The particle translational and rotational characteristic distributions were related to certain simulation parameters.展开更多
Solar power,as one of renewable energy,holds potential application for producing steam which relies on high-temperature liquid by traditional methods.Herein,steam was generated by a bio-inspired strategy derived from ...Solar power,as one of renewable energy,holds potential application for producing steam which relies on high-temperature liquid by traditional methods.Herein,steam was generated by a bio-inspired strategy derived from the plants transpiration using a Printed Recyclable Carbon Membrane(PRCM).The membrane structure facilitated the concentration of carbon particles for the photoreaction and the heat generation for water evaporation,thereby improving the photo-thermal conversion efficiency.The PRCM achieved the best steady evaporation efficiency of 51.9%,which was 5.6 times higher than the value for water and recycling tests were demonstrated.The carbon particles were separated from the water under the magnetism action,a convenient approach that avoided secondary pollution resulting from the disintegration of the PRCM.Rapid preparation,low cost,and reusability of the printed carbon membrane allow for photo-thermal applications such as solar steam generation and seawater desalination.展开更多
The discrete hard sphere particle model (DPM) is applied in this work to study numerically the distribu- tions of particle and bubble granular temperatures in a bubbling fluidized bed. The dimensions of the bed and ...The discrete hard sphere particle model (DPM) is applied in this work to study numerically the distribu- tions of particle and bubble granular temperatures in a bubbling fluidized bed. The dimensions of the bed and other parameters are set to correspond to those of Miuller et al(2008). Various drag models and oper- ational parameters are investigated to find their influence on particle and bubble granular temperatures. Various inlet superficial gas velocities are used in this work to obtain their effect on flow characteristics. It is found that the superficial gas velocity has the most important effect on granular temperatures including bubble granular temperature, particle translational granular temperature and particle rotational granular temperature. The drag force model affects more seriously the large scale variables such as the bubble gran- ular temperature. Restitution coefficient influences all granular temperatures to some degree. Simulation results are compared with experimental results by Muller et al. (2008) showing reasonable agreement.展开更多
文摘It is regretful that the Acknowledgments part was lost in the final process of publication.The Acknowledgments part should be added as follow.The work described in this paper was supported by the grants from the Research Grants Council of the Hong Kong Special Administrative Region,China(Project No.16205721).
基金financially supported from the National Natural Science Foundation of China (No.22002008)Ningxia Key Research and Development Project,China (Nos.2022BEE03002 and 2022BSB03056)funding support from Synfuels China,Co.,Ltd.and Beijing Advanced Innovation Center for Materials Genome Engineering。
文摘The activation of CO on iron-based materials is a key elementary reaction for many chemical processes.We investigate CO adsorption and dissociation on a series of Fe,Fe_(3)C,Fe_(5)C_(2),and Fe_(2)C catalysts through density functional theory calculations.We detect dramatically different performances for CO adsorption and activation on diverse surfaces and sites.The activation of CO is dependent on the local coordination of the molecule to the surface and on the bulk phase of the underlying catalyst.The bulk properties and the different local bonding environments lead to varying interactions between the adsorbed CO and the surface and thus yielding different activation levels of the C-O bond.We also examine the prediction of CO adsorption on different types of Fe-based catalysts by machine learning through linear regression models.We combine the features originating from surfaces and bulk phases to enhance the prediction of the activation energies and perform eight different linear regressions utilizing the feature engineering of polynomial representations.Among them,a ridge linear regression model with2nd-degree polynomial feature generation predicted the best CO activation energy with a mean absolute error of 0.269 eV.
文摘Featuring low cost, high abundance, low electrochemical potential, and large specific capacity, zinc(Zn)metal holds great potential as an anode material for next-generation rechargeable aqueous batteries.However, the poor reversibility resulting from dendrite formation and side reactions poses a major obstacle for its practical application. Electrolyte, which is regarded as the “blood” of batteries, has a direct impact on reaction kinetics, mass transport, and side reactions and thus plays a key role in determining the electrochemical performance of Zn electrodes. Therefore, considerable efforts have been devoted to modulating the electrolytes to improve the performance of Zn electrodes. Although significant progress has been made, achieving stable and highly reversible Zn electrodes remains a critical challenge. This review aims to provide a systematic summary and discussion on electrolyte strategies for highperformance aqueous Zn batteries. The(electro)-chemical behavior and fundamental challenges of Zn electrodes in aqueous electrolytes are first discussed. Electrolyte modulation strategies developed to address these issues are then classified and elaborated according to the underlying mechanisms.Finally, remaining challenges and promising future research directions on aqueous electrolyte engineering are highlighted. This review offers insights into the design of highly efficient electrolytes for new generation of rechargeable Zn batteries.
基金supported by the Heilongjiang Province Natural Science Foundation(Grant No.LH2019E053)Fundamental Research Funds for Central Universities(Grant No.FRFCU5710051421).
文摘The photothermal self-driving process of Janus microparticles has wide application prospects in the fields of biomedicine.Since silica and gold have good biocompatibility and high photothermal conversion efficiency,the SiO_(2)@Au Janus microparticles are widely used as drug carriers.Based on the multiphysics coupling method,the photothermal self-driving process of SiO_(2)@Au Janus microparticles was investi-gated,wherein the substrate was SiO_(2)particles and one side of the particles was coated with gold film.Under a continuous wave laser with irradiation of 20 W/cm^(2),the distance covered by the Janus particles was increased by increasing the thickness of the gold film and reducing the size of the SiO_(2)particles;the self-driving characteristics of the Janus particles were controlled substantially by increasing the intensity of the incident laser.Based on the simulation results,the thermophoretic motion and Brownian motion of particles can be measured by comparing the absolute values of the thermophoretic force impulse,Brownian force impulse,and drag force impulse.The Brownian force acting on Janus microparticles under low laser power cannot be ignored.Furthermore,the minimum laser power required for Janus particles to overcome Brownian motion was calculated.The results can effectively guide the design of Janus particles in biomedicine and systematically analyze the mechanism of particle thermophoretic motion during drug delivery.
基金Open Fund of Key Laboratory(JZX7Y201911SY008601)Key Project of National Natural Science Foundation of China(52032004)National Natural Science Foundation for Distinguished Young Scholars of China(51625201)。
文摘In this paper,a 3D meta-atom-based structure is constructed for the multifunctional compatible design of visible,infrared,and microwave.To achieve high performance,a novel dispersion tailoring strategy is proposed.Through the incorporation of multiple controllable losses within the 3D meta-atom,the dispersion characteristics are tailored to the desired target region.The effectiveness of the strategy is verified with an error rate of less than5%.A proof-of-concept prototype is designed and fabricated,exhibiting high visible transparency,low infrared emission of 0.28,and microwave ultra-broadband absorption with a fractional bandwidth of 150%under 2.7 to18.7 GHz.This work contributes a novel design strategy for the development of high-performance multispectral stealth materials with wide applications.
基金supported by Chinese Heilongjiang Postdoctoral FoundationChinese Heilongjiang Postdoctoral Science Funding No.LBH-Q07036+1 种基金the Science Creative Foundation for Distinguished Young Scholars in Harbin (Grant No. 2008RFLG005)Project Supported by Natural Scientific Research Innovation Foundation in Harbin Institute of Technology No.HIT.NSRIF. 2008.43.
文摘This paper is concerned with the forced convective heat transfer of dilute liquid suspensions of nanoparticles (nanofluids) flowing through a straight pipe under laminar conditions. Stable nanofluids are formulated by using the high shear mixing and ultrasonication methods. They are then characterised for their size, surface charge,thermal and rheological properties and tested for their convective heat transfer behaviour. Mathematical modelling is performed to simulate the convective heat transfer of nanofluids using a single phase flow model and considering nanofluids as both Newtonian and non-Newtonian fluid. Both experiments and mathematical modelling show that nanofluids can substantially enhance the convective heat transfer. Analyses of the results suggest that the non-Newtonian character of nanofluids influences the overall enhancement, especially for nanofluids with an obvious non-Newtonian character.
文摘Compared to traditional optical domes, domes of sapphire coated with films can effectively reduce emissivity and increase transmittance. The purpose of this work is to investigate the thermal radiation effect on sapphire optical dome coated with yttrium oxide by a radio frequency mag- netron sputtering method. The emissivity of sapphire coated with Y203 films is studied by both numerical and experi- mental methods. The results indicate that the emissivity of sapphire substrate is reduced effectively with increasing the thickness of the Y203 film. In addition, a finite element model is developed to simulate the radiation intensity of the optical dome. The thermal responses indicate that the max- imum temperature is reduced apparently compared with the uncoated sapphire as Y203 film thicknesses increase. The average irradiance distribution at different film thicknesses with time shows that the self-thermal radiation disturbance of sapphire optical dome delays 0.93 s when the thickness of Y203 film is 200μm, which can guarantee the dome works properly and effectively even in a harsh environment.
基金This work was financially supported by the National Natural Science Foundation of China(Grant No.51676060)the Natural Science Funds of Heilongjiang Province for Distinguished Young Scholars(Grant No.JC2016009)the Science Creative Foundation for Distinguished Young Scholars in Harbin(Grant No.2014RFYXJ004).
文摘Size-controlled hollow Fe3O4 nanospheres were synthesized via a one-pot hydrothermal method as a function of reaction time and sodium citrate,polyacrylamide,and urea content.Multiple characterization techniques such as scanning and transmission electron microscopy and Raman spectroscopy were employed to investigate the crystal structure and morphology of the obtained nanospheres.The Fe3O4 nanosphere formation mechanism was elucidated from analyzing the characterization data.High levels of sodium citrate and longer reaction times were observed to increase the diameter of the nanospheres until hollow structures formed.Furthermore,polyacrylamide and urea promoted the formation of hollow structures.The hollow-structured Fe3O4 nanospheres exhibited high magnetization saturation values in the range of 48.8-58.7 emu/g.The facile synthesis method described herein,to generate size-controlled Fe3O4 nanospheres with tailored properties,demonstrates potential across a wide range of fields from drug-delivery and stealth devices,to environmental and energy applications.
基金supported by BOE Technology Group Co.,Ltd.Y.L.acknowledges support from the National Natural Science Foundation of China under grant numbers 61825102 and U21A20460.
文摘This paper presents a flexible radio-frequency microelectromechanical system(RF MEMS)switch integrated on cyclo-olefin polymer(COP)substrate using a modified surface MEMS processing technology,which could be used in the 17-19 GHz frequency band of satellite communication.Through systematic simulation analysis,it is found that flexible RF MEMS switch can achieve certain bending radius by miniaturizing the electronic dimension,without degrading the RF performance.It is demonstrated that the RF characteristics of flexible RF MEMS switch with special anchor structural design,fabricated by modified surface MEMS processing,are not sensitive to bending deformation under the curvature of 0 mm^(-1),0.05 mm^(-1),0.10 mm^(-1).Furthermore,the range of bending curvature which will affect the RF characteristics is given through systematic simulation.The flexible RF MEMS switch with high process compatibility and stable RF performance is believed to be promising candidates for future microwave communications and other consumer electronics.
基金financially supported by the National Natural Science Foundation of China(Grant No.51322601)the National Natural Science Foundation of China-China National Petroleum Corporation Joint Fund of Petrochemical Engineering(U1162122)the Fundamental Research Funds for the Central Universities (Grant No.HIT.BRETIV.201315)
文摘In this work, a discrete particle model (DPM) was applied to investigate the dynamic characteristics in a gas-solid bubbling fluidized bed of binary solid particles. The solid phase was simulated by the hard- sphere discrete particle model. The large eddy simulation (LES) method was used to simulate the gas phase. To improve the accuracy of the simulation, an improved sub-grid scale (SGS) model in the LES method was also applied. The mutative Smagorinsky constant case was compared with the previously published experimental data. The simulation by the mutative Smagorinsky constant model exhibited better agreement with the experimental data than that by the common invariant Smagorinsky constant model. Various restitution coefficients and different compositions of binary solids were investigated to determine their influences on the rotation characteristics and granular temperatures of the particles. The particle translational and rotational characteristic distributions were related to certain simulation parameters.
基金This work is financially supported by the China National Key Research and Development Plan Project(2018YFA0702300)the National Natural Science Foundation of China(51676060)+1 种基金EU ThermaSMART project H2020-MSCA-RISE(778104)Smart thermal management of high power microprocessors using phase-change(ThermaSMART).
文摘Solar power,as one of renewable energy,holds potential application for producing steam which relies on high-temperature liquid by traditional methods.Herein,steam was generated by a bio-inspired strategy derived from the plants transpiration using a Printed Recyclable Carbon Membrane(PRCM).The membrane structure facilitated the concentration of carbon particles for the photoreaction and the heat generation for water evaporation,thereby improving the photo-thermal conversion efficiency.The PRCM achieved the best steady evaporation efficiency of 51.9%,which was 5.6 times higher than the value for water and recycling tests were demonstrated.The carbon particles were separated from the water under the magnetism action,a convenient approach that avoided secondary pollution resulting from the disintegration of the PRCM.Rapid preparation,low cost,and reusability of the printed carbon membrane allow for photo-thermal applications such as solar steam generation and seawater desalination.
基金supported by the Foundation for Innovative Research Groups of the National Natural Science Foundation of China (Grant No. 51121004)the National Natural Science Foundation of China–China National Petroleum Corporation Joint Fund of Petrochemical Engineering (U1162122) the Program for New Century Excellent Talents in University (NCET-08-0159)
文摘The discrete hard sphere particle model (DPM) is applied in this work to study numerically the distribu- tions of particle and bubble granular temperatures in a bubbling fluidized bed. The dimensions of the bed and other parameters are set to correspond to those of Miuller et al(2008). Various drag models and oper- ational parameters are investigated to find their influence on particle and bubble granular temperatures. Various inlet superficial gas velocities are used in this work to obtain their effect on flow characteristics. It is found that the superficial gas velocity has the most important effect on granular temperatures including bubble granular temperature, particle translational granular temperature and particle rotational granular temperature. The drag force model affects more seriously the large scale variables such as the bubble gran- ular temperature. Restitution coefficient influences all granular temperatures to some degree. Simulation results are compared with experimental results by Muller et al. (2008) showing reasonable agreement.