Broadband undistorted transmission is one of the criteria to preserve the information carried by incident waves and pulses,allowing imaging formation and source detection.For transmission through artificial materials ...Broadband undistorted transmission is one of the criteria to preserve the information carried by incident waves and pulses,allowing imaging formation and source detection.For transmission through artificial materials like metasurfaces,undistorted transmission usually requires each meta-atom to possess exactly the same transmission amplitude and phase.Here,we consider a special acoustic metasurface consisting of meta-atoms with the same transmission phase but different transmittance.Interestingly,we find that when the meta-atoms are of subwavelength scale,the difference in transmittance would not induce substantial distortion in the transmitted wavefront.Based on this observation,we numerically and experimentally demonstrate acoustic metasurfaces that exhibit undistorted transmission and configurable arbitrary reflection.Two distinct types of reflection,i.e.,anomalous reflection and diffuse reflection,are numerically and experimentally demonstrated with the transmission wavefront undistorted through a broad spectrum.Our work reveals a more general condition for realizing broadband undistorted transmission and configurable reflection with metasurfaces,which has potential implications in acoustic field manipulation and novel sonar domes.展开更多
Hybrid DC transmission technology is used in new energy transmission due to its advantages of large capacity and long distances.Line-commutated converter-voltage source converter-multi-terminal DC(LCC-VSC-MTDC)is one ...Hybrid DC transmission technology is used in new energy transmission due to its advantages of large capacity and long distances.Line-commutated converter-voltage source converter-multi-terminal DC(LCC-VSC-MTDC)is one of the more important development directions in future power grids.But the multi-terminal high voltage direct current system has problems of inconsistent boundary characteristics,inconsistent control,and fault response characteristics,which places higher requirements on the protection scheme.A protection scheme based on the undistorted factor is proposed to ensure the safe operation of the system.First,the inconsistent line mode voltage attenuation characteristics of different fault locations are used to construct the undistorted factor.Subsequently,the undistorted factor is used to identify fault.The advantage of this scheme is that it remains unaffected by boundary elements,control strategies,and distributed capacitance.Finally,the LCC-VSC-MTDC model verifies the correctness and superiority of the proposed protection scheme.展开更多
Preparation of large rylenes often needs the use of solubilizing groups along the rylene backbone,which results in the distortion of the skeleton and thus broadening of the absorption spectrum.In this work,we successf...Preparation of large rylenes often needs the use of solubilizing groups along the rylene backbone,which results in the distortion of the skeleton and thus broadening of the absorption spectrum.In this work,we successfully synthesized 2,5,8,16,19,22-hexakis[2,6-bis(tri-fluoromethyl)phenyl]hexarylene(H)by using an oxidative fusion reaction of perylene trimer in 5%yield.The product is soluble in common organic solvents and could be purified with column chromatography.Single-crystal X-ray diffraction analysis revealed that the hexarylene core is not disturbed by the substituents very much and is almost planar.The longest absorption of H exhibits a sharp peak at 831 nm and an on-set at 875 nm in toluene with a small full-width-at-half-maximum(FWHM)of 660 cm^(-1).The molar extinction coefficient is as large as 131,000 M^(-1)cm^(-1).The substituents could not perturb the electronic properties of the hexarylene because aryl groups are perpendicular to the hexarylene core and the carbon atoms at 2,5,16,19-positions have negligible coeffi-cients on its HOMO and LUMO,estimated by theoretical calculations.As a result,the hexarylene having less absorption at the visible light region was stable enough in solution under the LED room light for more than 1 week.This strategy gives a useful guideline to establish the near-infrared materials that exhibit stability under ambient conditions.展开更多
基金supported by the National Key Research and Development Program of China(Grant No.2020YFA0211400)the National Natural Science Foundation of China(Grants Nos.12474293,12174188,12404364,12504545,12504515,and 12174192)+2 种基金the State Key Program of National Natural Science Foundation of China(Grant No.11834008)the Natural Science Foundation of Jiangsu Province(Grants Nos.BK20240575 and BK20233001)the China Postdoctoral Science Foundation(Grants No.2023M731612)。
文摘Broadband undistorted transmission is one of the criteria to preserve the information carried by incident waves and pulses,allowing imaging formation and source detection.For transmission through artificial materials like metasurfaces,undistorted transmission usually requires each meta-atom to possess exactly the same transmission amplitude and phase.Here,we consider a special acoustic metasurface consisting of meta-atoms with the same transmission phase but different transmittance.Interestingly,we find that when the meta-atoms are of subwavelength scale,the difference in transmittance would not induce substantial distortion in the transmitted wavefront.Based on this observation,we numerically and experimentally demonstrate acoustic metasurfaces that exhibit undistorted transmission and configurable arbitrary reflection.Two distinct types of reflection,i.e.,anomalous reflection and diffuse reflection,are numerically and experimentally demonstrated with the transmission wavefront undistorted through a broad spectrum.Our work reveals a more general condition for realizing broadband undistorted transmission and configurable reflection with metasurfaces,which has potential implications in acoustic field manipulation and novel sonar domes.
基金supported by the National Natural Science Foundation of China-State Grid Joint Fund for Smart Grid(No.U2066210).
文摘Hybrid DC transmission technology is used in new energy transmission due to its advantages of large capacity and long distances.Line-commutated converter-voltage source converter-multi-terminal DC(LCC-VSC-MTDC)is one of the more important development directions in future power grids.But the multi-terminal high voltage direct current system has problems of inconsistent boundary characteristics,inconsistent control,and fault response characteristics,which places higher requirements on the protection scheme.A protection scheme based on the undistorted factor is proposed to ensure the safe operation of the system.First,the inconsistent line mode voltage attenuation characteristics of different fault locations are used to construct the undistorted factor.Subsequently,the undistorted factor is used to identify fault.The advantage of this scheme is that it remains unaffected by boundary elements,control strategies,and distributed capacitance.Finally,the LCC-VSC-MTDC model verifies the correctness and superiority of the proposed protection scheme.
基金supported by Grants-in-Aid for Scientific Research(Nos.JP20H02816(HH),JP20H00379(HY),JP20H05833(HY),JP20H02711(NA),JP22H19067(NA),JP22K05225(KM),JP20K15261(KM))。
文摘Preparation of large rylenes often needs the use of solubilizing groups along the rylene backbone,which results in the distortion of the skeleton and thus broadening of the absorption spectrum.In this work,we successfully synthesized 2,5,8,16,19,22-hexakis[2,6-bis(tri-fluoromethyl)phenyl]hexarylene(H)by using an oxidative fusion reaction of perylene trimer in 5%yield.The product is soluble in common organic solvents and could be purified with column chromatography.Single-crystal X-ray diffraction analysis revealed that the hexarylene core is not disturbed by the substituents very much and is almost planar.The longest absorption of H exhibits a sharp peak at 831 nm and an on-set at 875 nm in toluene with a small full-width-at-half-maximum(FWHM)of 660 cm^(-1).The molar extinction coefficient is as large as 131,000 M^(-1)cm^(-1).The substituents could not perturb the electronic properties of the hexarylene because aryl groups are perpendicular to the hexarylene core and the carbon atoms at 2,5,16,19-positions have negligible coeffi-cients on its HOMO and LUMO,estimated by theoretical calculations.As a result,the hexarylene having less absorption at the visible light region was stable enough in solution under the LED room light for more than 1 week.This strategy gives a useful guideline to establish the near-infrared materials that exhibit stability under ambient conditions.
