Actuators are one of the key points for the development of active flow control technology.Efficient methods of high speed flow control can provide enhanced propulsive efficiency and at the same time enable safe and ma...Actuators are one of the key points for the development of active flow control technology.Efficient methods of high speed flow control can provide enhanced propulsive efficiency and at the same time enable safe and maneuverable high speed flight.The development of high speed flight technology promotes the emergence of novel and robust actuators.This review introduces the state of the art in the development of actuators that can be used in high speed active flow control.The classification and different operation criteria of the actuators are discussed.The specifications,mechanisms and applications of various popular actuator types including fluidic,mechanical,and plasma actuators are described.Based on the realistic need of high speed flow control and the existing results of actuators,a new actuator design method is proposed.At last,the merits and drawbacks of the actuators are summarized and some suggestions on the development of active flow control technology are put forward.展开更多
CMOS platforms with a high nonlinear figure of merit are highly sought after for high photonic quantum efficiencies, enabling functionalities not possible from purely linear effects and ease of integration with CMOS e...CMOS platforms with a high nonlinear figure of merit are highly sought after for high photonic quantum efficiencies, enabling functionalities not possible from purely linear effects and ease of integration with CMOS electronics. Silicon-based platforms have been prolific amongst the suite of advanced nonlinear optical signal processes demonstrated to date. These include crystalline silicon, amorphous silicon, Hydex glass, and stoichio- metric silicon nitride. Residing between stoichiometric silicon nitride and amorphous silicon in composition, silicon-rich nitride films of various formulations have emerged recently as promising nonlinear platforms for high nonlinear figure of merit nonlinear optics. Silicon-rich nitride films are compositionally engineered to create bandgaps that are sufficiently large to eliminate two-photon absorption at telecommunications wavelengths while enabling much larger nonlinear waveguide parameters （5x-500x） than those in stoichiometric silicon uitride. This paper reviews recent developments in the field of nonlinear optics using silicon-rich nitride platforms, as well as the outlook and future opportunities in this burgeoning field.展开更多
Thermoelectrics has played a fascinating role in the developments of direct energy conversion technologies.Over the past decade,sulfur-based thermoelectric materials have been significantly advanced in optimizing elec...Thermoelectrics has played a fascinating role in the developments of direct energy conversion technologies.Over the past decade,sulfur-based thermoelectric materials have been significantly advanced in optimizing electrical and thermal transport due to their similarities in chemical and structural properties with tellurides and selenides.This review provides research progress on metal sulfides,particularly focuses on materials exhibiting high thermoelectric figure of merit(ZT>1.0).It highlights the potential compounds,e.g.Cu-S,Sn-S,Pb-S based,and polysulfides.Great strategies of superionic conducting,band configuration tuning,high-entropy alloying,and anomalous harmonic scattering are try to demonstrate the performance-improved mechanisms for thermoelectric sulfides.In addition,some common synthesis recipes are briefly introduced,and thereby making potential candidates as excellent alternatives for producing thermoelectric power generators in the mid temperature.Key outcomes along with how to further improve the thermoelectric performance and promote its scale-up applications are also outlined at the end.展开更多
Thermoelectric materials can be used to convert heat to electric power through the Seebeck effect. We study magneto-thermoelectric figure of merit （ZT） in three-dimensional Dirac semimetal Cd3A 5 2 crystal. It is fo...Thermoelectric materials can be used to convert heat to electric power through the Seebeck effect. We study magneto-thermoelectric figure of merit （ZT） in three-dimensional Dirac semimetal Cd3A 5 2 crystal. It is found that enhancement of power factor and reduction of thermal conductivity can be realized at the same time through magnetic field although magnetoresistivity is greatly increased. ZT can be highly enhanced from 0.17 to 1.1 by more than six times around 350 K under a perpendicular magnetic field of 7 T. The huge enhancement of ZT by magnetic field arises from the linear Dirac band with large Fermi velocity and the large electric thermal conductivity in CdsA 5 2. Our work paves a new way to greatly enhance the thermoelectric performance in the quantum topological materials.展开更多
Finding binary sequences with Large SHG ratios is very important in the field of ultrafast science, biomedical optics, high-resolution microscopy and label-free imaging. In this paper, we have demonstrated the relatio...Finding binary sequences with Large SHG ratios is very important in the field of ultrafast science, biomedical optics, high-resolution microscopy and label-free imaging. In this paper, we have demonstrated the relation between the SHG contrast ratio and the traditional Merit Factor values. And in the light from known results in Merit Factor Problems, we have shown that Legendre Sequences or Jacobi Sequences, are still the best candidates to obtain binary sequences with large SHG contrast ratios. The authors also discussed the SHG behaviors on some sequences obtained from cyclotomic classes over the finite field GF (2l) .展开更多
基金supported by the National Natural Science Foundation of China (Grant No. 11002161)the Foundation for the Author of National Excellent Doctor Dissertation of China (Grant No. 201058)the Specialized Research Fund for the Doctor Program of Higher Education of China (Grant No. 20104307110007)
文摘Actuators are one of the key points for the development of active flow control technology.Efficient methods of high speed flow control can provide enhanced propulsive efficiency and at the same time enable safe and maneuverable high speed flight.The development of high speed flight technology promotes the emergence of novel and robust actuators.This review introduces the state of the art in the development of actuators that can be used in high speed active flow control.The classification and different operation criteria of the actuators are discussed.The specifications,mechanisms and applications of various popular actuator types including fluidic,mechanical,and plasma actuators are described.Based on the realistic need of high speed flow control and the existing results of actuators,a new actuator design method is proposed.At last,the merits and drawbacks of the actuators are summarized and some suggestions on the development of active flow control technology are put forward.
基金MOE Academic Research Fund Tier 2 GrantNational Research Foundation Competitive Research Grant+3 种基金National Research Foundation Land and Liveability National Innovation Challenge GrantSUTD-MIT International Design CenterTemasek Laboratories grantNational Research Foundation,Prime Minister’s Office,Singapore,under its Medium Sized Centre Program
文摘CMOS platforms with a high nonlinear figure of merit are highly sought after for high photonic quantum efficiencies, enabling functionalities not possible from purely linear effects and ease of integration with CMOS electronics. Silicon-based platforms have been prolific amongst the suite of advanced nonlinear optical signal processes demonstrated to date. These include crystalline silicon, amorphous silicon, Hydex glass, and stoichio- metric silicon nitride. Residing between stoichiometric silicon nitride and amorphous silicon in composition, silicon-rich nitride films of various formulations have emerged recently as promising nonlinear platforms for high nonlinear figure of merit nonlinear optics. Silicon-rich nitride films are compositionally engineered to create bandgaps that are sufficiently large to eliminate two-photon absorption at telecommunications wavelengths while enabling much larger nonlinear waveguide parameters （5x-500x） than those in stoichiometric silicon uitride. This paper reviews recent developments in the field of nonlinear optics using silicon-rich nitride platforms, as well as the outlook and future opportunities in this burgeoning field.
基金supported by the National Natural Science Foundation of China,China(No.52202232)the JST Mirai Program,Japan(No.JPMJMI19A1)+2 种基金the Natural Science Foundation of Hubei Province,China(No.2022CFB937)the Guangdong Basic and Applied Basic Research Foundation,China(No.2020A1515110251)the CAS Key Laboratory of Cryogenics,TIPC,China(No.CRYO202204).
文摘Thermoelectrics has played a fascinating role in the developments of direct energy conversion technologies.Over the past decade,sulfur-based thermoelectric materials have been significantly advanced in optimizing electrical and thermal transport due to their similarities in chemical and structural properties with tellurides and selenides.This review provides research progress on metal sulfides,particularly focuses on materials exhibiting high thermoelectric figure of merit(ZT>1.0).It highlights the potential compounds,e.g.Cu-S,Sn-S,Pb-S based,and polysulfides.Great strategies of superionic conducting,band configuration tuning,high-entropy alloying,and anomalous harmonic scattering are try to demonstrate the performance-improved mechanisms for thermoelectric sulfides.In addition,some common synthesis recipes are briefly introduced,and thereby making potential candidates as excellent alternatives for producing thermoelectric power generators in the mid temperature.Key outcomes along with how to further improve the thermoelectric performance and promote its scale-up applications are also outlined at the end.
基金supported by the National Key R&D Program of the Ministry of Science and Technology China(2017YFA0303001,2016YFA0300201 and 2017YFA0204904)the National Natural Science Foundation of China(11534010,11774325 and21603210)+4 种基金the Key Research Program of Frontier Sciences CAS(QYZDY-SSW-SLH021)Hefei Science Center CAS(2016HSCIU001)the Fundamental Research Funds for the Central UniversitiesSupercomputing Center at USTC for providing the computing resourcespartially performed on the Superconducting Magnet and PPMS-16T Facilities,High Magnetic Field Laboratory of CAS
文摘Thermoelectric materials can be used to convert heat to electric power through the Seebeck effect. We study magneto-thermoelectric figure of merit （ZT） in three-dimensional Dirac semimetal Cd3A 5 2 crystal. It is found that enhancement of power factor and reduction of thermal conductivity can be realized at the same time through magnetic field although magnetoresistivity is greatly increased. ZT can be highly enhanced from 0.17 to 1.1 by more than six times around 350 K under a perpendicular magnetic field of 7 T. The huge enhancement of ZT by magnetic field arises from the linear Dirac band with large Fermi velocity and the large electric thermal conductivity in CdsA 5 2. Our work paves a new way to greatly enhance the thermoelectric performance in the quantum topological materials.
文摘Finding binary sequences with Large SHG ratios is very important in the field of ultrafast science, biomedical optics, high-resolution microscopy and label-free imaging. In this paper, we have demonstrated the relation between the SHG contrast ratio and the traditional Merit Factor values. And in the light from known results in Merit Factor Problems, we have shown that Legendre Sequences or Jacobi Sequences, are still the best candidates to obtain binary sequences with large SHG contrast ratios. The authors also discussed the SHG behaviors on some sequences obtained from cyclotomic classes over the finite field GF (2l) .
