Radiative cooling materials have gained prominence as a zero-energy solution for mitigating global warming.However,a comprehensive understanding of the atomic-scale optical properties and macroscopic optical performan...Radiative cooling materials have gained prominence as a zero-energy solution for mitigating global warming.However,a comprehensive understanding of the atomic-scale optical properties and macroscopic optical performance of radiative cooling materials remains elusive,limiting insight into the underlying physics of their optical response and cooling efficacy.La_(2)O_(3)and HfO_(2),which represent rare earth and third/fourth subgroup inorganic oxides,respectively,show promise for radiative cooling applications.In this study,we used multiscale simulations to investigate the optical properties of La_(2)O_(3)and HfO_(2)across a broad spectrum.First-principles calculations revealed their dielectric functions and intrinsic refractive indices,and the results indicated that the slightly smaller bandgap of La_(2)O_(3)compared to HfO_(2)induces a higher refractive index in the solar band.Additionally,three-phonon scattering was found to provide more accurate infrared optical properties than two-phonon scattering,which enhanced the emissivity in the sky window.Monte Carlo simulations were also used to determine the macroscopic optical properties of La_(2)O_(3)and HfO_(2)coatings.Based on the simulated results,we identified that the particle size and particle volume fraction play a dominant role in the optical properties.Our findings underscore the potential of La_(2)O_(3)and HfO_(2)nanocomposites for environment-friendly cooling and offer a new approach for high-throughput screening of optical materials through multiscale simulations.展开更多
The RHT model has 34 parameters,among which 19 parameters can be obtained by experiments or theoretical calculations and the remaining 15 parameters are difficult to acquire.In this study,firstly,10 Hopkinson impact t...The RHT model has 34 parameters,among which 19 parameters can be obtained by experiments or theoretical calculations and the remaining 15 parameters are difficult to acquire.In this study,firstly,10 Hopkinson impact tests were conducted to acquire the typical stress-strain curves of granite under dynamic loads.Through the sensitivity analysis,it is found that 13 of the 15 difficult-acquired parameters are effective to affect the shape of the stress-strain curve,and the other two parameters have no effect.Following the initial determination of model parameters with reference to the concrete RHT model,a new approach is proposed to optimize the 13 influential parameters through the LS-DYNA numerical simulation and orthogonal experiments.Finally,the determined granite RHT model parameters are verified by the results of Hopkinson impact tests conducted in this study and the bullet penetration test by Wang et al.Both results of the numerical simulations are in a good agreement with the tested results,which validates the suitability of the proposed method to acquire RHT model parameters for granite and the other rocks.展开更多
基金the National Natural Science Foundation of China(Grant Nos.U23A20565,52301194,and 52101178)the Shanghai Science and Technology Commission(Grant No.22511100400)+1 种基金the startup funding from Shanghai Jiao Tong University(Grant No.WH220405009)Innovation Program of Shanghai Municipal Education Commission(Grant No.2023ZKZD15)for providing funding support for this research。
文摘Radiative cooling materials have gained prominence as a zero-energy solution for mitigating global warming.However,a comprehensive understanding of the atomic-scale optical properties and macroscopic optical performance of radiative cooling materials remains elusive,limiting insight into the underlying physics of their optical response and cooling efficacy.La_(2)O_(3)and HfO_(2),which represent rare earth and third/fourth subgroup inorganic oxides,respectively,show promise for radiative cooling applications.In this study,we used multiscale simulations to investigate the optical properties of La_(2)O_(3)and HfO_(2)across a broad spectrum.First-principles calculations revealed their dielectric functions and intrinsic refractive indices,and the results indicated that the slightly smaller bandgap of La_(2)O_(3)compared to HfO_(2)induces a higher refractive index in the solar band.Additionally,three-phonon scattering was found to provide more accurate infrared optical properties than two-phonon scattering,which enhanced the emissivity in the sky window.Monte Carlo simulations were also used to determine the macroscopic optical properties of La_(2)O_(3)and HfO_(2)coatings.Based on the simulated results,we identified that the particle size and particle volume fraction play a dominant role in the optical properties.Our findings underscore the potential of La_(2)O_(3)and HfO_(2)nanocomposites for environment-friendly cooling and offer a new approach for high-throughput screening of optical materials through multiscale simulations.
基金Supported by the Talent Indroduction Research Start-up Fund Project of Kunming University of Science and Technology(KKSY201756009)
文摘The RHT model has 34 parameters,among which 19 parameters can be obtained by experiments or theoretical calculations and the remaining 15 parameters are difficult to acquire.In this study,firstly,10 Hopkinson impact tests were conducted to acquire the typical stress-strain curves of granite under dynamic loads.Through the sensitivity analysis,it is found that 13 of the 15 difficult-acquired parameters are effective to affect the shape of the stress-strain curve,and the other two parameters have no effect.Following the initial determination of model parameters with reference to the concrete RHT model,a new approach is proposed to optimize the 13 influential parameters through the LS-DYNA numerical simulation and orthogonal experiments.Finally,the determined granite RHT model parameters are verified by the results of Hopkinson impact tests conducted in this study and the bullet penetration test by Wang et al.Both results of the numerical simulations are in a good agreement with the tested results,which validates the suitability of the proposed method to acquire RHT model parameters for granite and the other rocks.
