How to freely control heat transfer at macroscopic scale is always a dream of human beings due to important applications in thermal protection,detection,and control/management.Within the past decade(2008-2018),thermal...How to freely control heat transfer at macroscopic scale is always a dream of human beings due to important applications in thermal protection,detection,and control/management.Within the past decade(2008-2018),thermal metamaterials have been shown as a promising candidate for this purpose.Here,I review the up-to-date research progress in the field,which mainly includes the following novel phenomena and functional devices together with initial applications:thermal cloak,concentrator,dual function,thermal rotator,macroscopic thermal diode,thermal camouflage,thermal transparency,thermal crystal,energy-free thermostat,abnormal conduction in networks,convection cloak/concentrator/camouflage,and thermal radiation cooling.The underlying mechanisms are presented according to six categories of theory:transformation thermotics,direct solution of Laplace equation,energy band theory,phase transition theory,transformation thermal convection,and thermal radiation theory.I also introduce and comment their prospects from fundamental research to industrial applications.This review has relevance to novel controls of heat transfer(conduction,convection,and radiation)by using artificial structures or devices.展开更多
We experimentally demonstrate multiple frequency conversion via atomic spin coherence of storing a light pulse in a doped solid. The essence of this multiple frequency conversion is four-wave mixing based on stored at...We experimentally demonstrate multiple frequency conversion via atomic spin coherence of storing a light pulse in a doped solid. The essence of this multiple frequency conversion is four-wave mixing based on stored atomic spin coherence. Through electromagnetically induced transparency, an input probe pulse is stored into atomic spin coherence by modulating the intensity of the control field. By using two different control fields to interact with the coherently prepared medium, the stored atomic spin coherence can be transformed into three different information channels. Multiple frequency conversion is implemented efficiently by manipulating the spectra of the control fields to scatter atomic spin coherence. This multiple frequency conversion is expected to have potential applications in information processing and communication network.展开更多
By constructing an innovation decision-making model that includes economic policy uncertainty(EPU),this paper finds that EPU will have a negative impact on corporate innovation.Further analysis shows that it has asymm...By constructing an innovation decision-making model that includes economic policy uncertainty(EPU),this paper finds that EPU will have a negative impact on corporate innovation.Further analysis shows that it has asymmetric effects on long-term and short-term innovation decisions and puts forward two potential mechanisms of inhibitory effect in long-term:one is reducing follow-up investment,and the other is reducing marketization return.The empirical analysis verifies the inhibitory effect of EPU on corporate innovation and verifies two potential mechanisms.We further investigate the potential moderating effects:increased information transparency and of capital structure adjustment speed can mitigate the inhibition of EPU on corporate innovation.This study provides clear policy implication to ease the uncertainty of economic policy at the government level.展开更多
This paper gives a brief survey of recent developments on mathematical modeling and analysis of the open cavity scattering problems, which arise in diverse scientific areas and have significant industrial and military...This paper gives a brief survey of recent developments on mathematical modeling and analysis of the open cavity scattering problems, which arise in diverse scientific areas and have significant industrial and military applications. The scattering problems are studied for the two-dimensional Helmholtz equation corresponding to the transverse magnetic or electric polarization, and the three-dimensional time-harmonic and time-domain Maxwell equations. Since these problems are imposed in open domains, a key step of the analysis is to develop transparent boundary conditions and reformulate them equivalently into boundary value problems in bounded domains. The well-posedness of weak solutions are shown for the associated variational problems by using either the Lax-Milgram theorem or the Fredholm alternative.展开更多
基金financial support by the National Natural Science Foundation of China under Grant No.11725521the Science and Technology Commission of Shanghai Municipality under Grant No.16ZR1445100
文摘How to freely control heat transfer at macroscopic scale is always a dream of human beings due to important applications in thermal protection,detection,and control/management.Within the past decade(2008-2018),thermal metamaterials have been shown as a promising candidate for this purpose.Here,I review the up-to-date research progress in the field,which mainly includes the following novel phenomena and functional devices together with initial applications:thermal cloak,concentrator,dual function,thermal rotator,macroscopic thermal diode,thermal camouflage,thermal transparency,thermal crystal,energy-free thermostat,abnormal conduction in networks,convection cloak/concentrator/camouflage,and thermal radiation cooling.The underlying mechanisms are presented according to six categories of theory:transformation thermotics,direct solution of Laplace equation,energy band theory,phase transition theory,transformation thermal convection,and thermal radiation theory.I also introduce and comment their prospects from fundamental research to industrial applications.This review has relevance to novel controls of heat transfer(conduction,convection,and radiation)by using artificial structures or devices.
基金Project supported by the National Basic Research Program of China(Grant No.2011CB921603)the National Natural Science Foundation of China(Grant Nos.11374126,11347137,11404336,and 11204103)+1 种基金the China Postdoctoral Science Foundation(Grant No.2013T60317)the National Fund for Fostering Talents of Basic Science,China(Grant No.J1103202)
文摘We experimentally demonstrate multiple frequency conversion via atomic spin coherence of storing a light pulse in a doped solid. The essence of this multiple frequency conversion is four-wave mixing based on stored atomic spin coherence. Through electromagnetically induced transparency, an input probe pulse is stored into atomic spin coherence by modulating the intensity of the control field. By using two different control fields to interact with the coherently prepared medium, the stored atomic spin coherence can be transformed into three different information channels. Multiple frequency conversion is implemented efficiently by manipulating the spectra of the control fields to scatter atomic spin coherence. This multiple frequency conversion is expected to have potential applications in information processing and communication network.
文摘By constructing an innovation decision-making model that includes economic policy uncertainty(EPU),this paper finds that EPU will have a negative impact on corporate innovation.Further analysis shows that it has asymmetric effects on long-term and short-term innovation decisions and puts forward two potential mechanisms of inhibitory effect in long-term:one is reducing follow-up investment,and the other is reducing marketization return.The empirical analysis verifies the inhibitory effect of EPU on corporate innovation and verifies two potential mechanisms.We further investigate the potential moderating effects:increased information transparency and of capital structure adjustment speed can mitigate the inhibition of EPU on corporate innovation.This study provides clear policy implication to ease the uncertainty of economic policy at the government level.
文摘This paper gives a brief survey of recent developments on mathematical modeling and analysis of the open cavity scattering problems, which arise in diverse scientific areas and have significant industrial and military applications. The scattering problems are studied for the two-dimensional Helmholtz equation corresponding to the transverse magnetic or electric polarization, and the three-dimensional time-harmonic and time-domain Maxwell equations. Since these problems are imposed in open domains, a key step of the analysis is to develop transparent boundary conditions and reformulate them equivalently into boundary value problems in bounded domains. The well-posedness of weak solutions are shown for the associated variational problems by using either the Lax-Milgram theorem or the Fredholm alternative.
