In this paper,we study the two-dimensional Helmholtz scattering problem by a locally perturbed line with impedance boundary condition.Different from the problem with Dirichlet boundary condition,the Green function of ...In this paper,we study the two-dimensional Helmholtz scattering problem by a locally perturbed line with impedance boundary condition.Different from the problem with Dirichlet boundary condition,the Green function of the Helmholtz equation with impedance boundary condition becomes very complicated and comprises surface waves along the locally perturbed line.A uniaxial perfectly matched layer(UPML)method is proposed to truncate the half plane into a bounded computational domain.The main contribution of this paper is to prove the well-posedness of the PML problem and the exponential convergence of the approximate solution to the exact solution as either the thickness or the medium parameter of PML increases.展开更多
Heat is almost everywhere.Unlike electricity,which can be easily manipulated,the current ability to control heat is still highly limited owing to spontaneous thermal dissipation imposed by the second law of thermodyna...Heat is almost everywhere.Unlike electricity,which can be easily manipulated,the current ability to control heat is still highly limited owing to spontaneous thermal dissipation imposed by the second law of thermodynamics.Optical illumination and pressure have been used to switch endothermic/exothermic responses of materials via phase transitions;however,these strategies are less cost-effective and unscalable.Here,we spectroscopically demonstrate the glassy crystal state of 2-amino-2-methyl-1,3-propanediol(AMP)to realize an affordable,easily manageable approach for thermal energy recycling.The supercooled state of AMP is so sensitive to pressure that even several megapascals can induce crystallization to the ordered crystal,resulting in a substantial temperature increase of 48 K within 20 s.Furthermore,we demonstrate a proof-of-concept device capable of programable heating with an extremely high work-to-heat conversion effi-ciency of383.Such delicate and efficient tuning of heat may remarkably facilitate rational utilization of waste heat.展开更多
基金supported by China NSF grants Nos.11771057,11401040 and 11671052.The research of X.J.Li is supported by China NSF grant Nos.11805049 and 11771440 and by the National Magnetic Confinement Fusion Science Program No.2015GB110003.
文摘In this paper,we study the two-dimensional Helmholtz scattering problem by a locally perturbed line with impedance boundary condition.Different from the problem with Dirichlet boundary condition,the Green function of the Helmholtz equation with impedance boundary condition becomes very complicated and comprises surface waves along the locally perturbed line.A uniaxial perfectly matched layer(UPML)method is proposed to truncate the half plane into a bounded computational domain.The main contribution of this paper is to prove the well-posedness of the PML problem and the exponential convergence of the approximate solution to the exact solution as either the thickness or the medium parameter of PML increases.
基金The work conducted in the Institute of Metal Research was supported by the Key Research Program of Frontier Sciences of the Chinese Academy of Sciences(grant no.ZDBS-LY-JSC002)the Liaoning Provincial Science Fund for Distinguished Young Scholars(grant no.2023JH6/100500003)+7 种基金the Innovation Fund of Institute of Metal Research,Chinese Academy of Sciences,(grant no.2021-ZD01)the CSNS Consortium on High-performance Materials of the Chinese Academy of Sciences,the Young Innovation Talent Program of Shenyang(grant no.RC210432)the Ministry of Science and Technology of the People’s Republic of China(grant nos.2021YFB3501201,2022YFE0109900,and 2020YFA0406002)the National Natural Science Foundation of China(grant nos.11934007,52001101,and 61974147)the International Partner Program of Chinese Academy of Sciences(grant no.174321KYSB20200008)J.L.and M.W.are grateful for the Research Foundation Flanders(grant no.G0B3218N)J.Luo acknowledges Sichuan Science and Technology Program(grant nos.2022ZYD0016 and 2023JDRC0013)National Natural Science Foundation of China(grant nos.21776120 and 22378270).The authors thank Sucheng Wang and Changji Li for their help with the in situ XRD experiments,Shuai Huang for thermal infrared image measurements,and Bo Huang for sample deuteration.They also thank Prof.Jie Pan and Prof.Si Lan for valuable discussions.
文摘Heat is almost everywhere.Unlike electricity,which can be easily manipulated,the current ability to control heat is still highly limited owing to spontaneous thermal dissipation imposed by the second law of thermodynamics.Optical illumination and pressure have been used to switch endothermic/exothermic responses of materials via phase transitions;however,these strategies are less cost-effective and unscalable.Here,we spectroscopically demonstrate the glassy crystal state of 2-amino-2-methyl-1,3-propanediol(AMP)to realize an affordable,easily manageable approach for thermal energy recycling.The supercooled state of AMP is so sensitive to pressure that even several megapascals can induce crystallization to the ordered crystal,resulting in a substantial temperature increase of 48 K within 20 s.Furthermore,we demonstrate a proof-of-concept device capable of programable heating with an extremely high work-to-heat conversion effi-ciency of383.Such delicate and efficient tuning of heat may remarkably facilitate rational utilization of waste heat.
