Higher-order topological insulators(HOTIs),with topological corner or hinge states,have emerged as a thriving topic in the field of topological physics.However,few connections have been found for HOTIs with well-explo...Higher-order topological insulators(HOTIs),with topological corner or hinge states,have emerged as a thriving topic in the field of topological physics.However,few connections have been found for HOTIs with well-explored first-order topological insulators.Recently a proposal asserted that a significant bridge can be established between the HOTIs and Z2 topological insulators.When subjected to an inplane Zeeman field,corner states,the signature of the HOTIs,can be induced in a Z2 topological insulator.Such Zeeman fields can be produced,for example,by the ferromagnetic proximity effect or magnetic atom doping,which drastically increases the experimental complexity.Here,we show that a phononic crystal,designed as a bilayer of coupled acoustic cavities,exactly hosts the Kane-Mele model with built-in in-plane Zeeman fields.The helical edge states along the zigzag edges are gapped,and the corner states,localized spatially at the corners of the samples,appear in the gap.This verifies the Zeeman field induced higher-order topology.We further demonstrate the intriguing contrast properties of the corner states at the outer and inner corners in a hexagonal ring-shaped sample.展开更多
Plowing-extruding tool was designed and plowing-extruding process was investigated.Then,a manufacturing method of integral serrated high-finned tube,plowing-extruding based on variational feed was proposed,in which pl...Plowing-extruding tool was designed and plowing-extruding process was investigated.Then,a manufacturing method of integral serrated high-finned tube,plowing-extruding based on variational feed was proposed,in which plowing-extruding tool moved forward at two different feeds,f1 and f2,in turn.In this method,overlaps that are usually avoided in practical application were utilized to manufacture high fins and average height of fins was up to 1.58 mm.The critical feed(fc) of overlaps forming and terms of high fins forming were analyzed.The main technical parameters that affect the fins height were discussed.The experimental results show that the fins height increases with extruding inclination angle and plowing-extruding depth,and the fins height increases with f1 increasing when f1 is smaller than fc,and decreases with f1 increasing if f1 is larger than fc.展开更多
基金the National Natural Science Foundation of China(Grant Nos.12372278,11732010,11972251,11872272,and 12172242)the Foundation of National Key Laboratory of Science and Technology on Aerodynamic Design and Research(Grant No.61422010301)+3 种基金the Foundation of National Key Laboratory of Aerodynamic Noise Control(Grant No.ANCL20230108)the Foundation of State Key Laboratory of Rail Transit Vehicle System(Grant No.TPL2306)Chinesisch-Deutsche Zentrum für Wissenschaftsförderung(Grant No.GZ1575)the Ministry of Industry and Information Technology(Grand No.[2019]360).
基金supported by the National Natural Science Foundation of China(11890701,11974120,11974005,12074128,12074232,12125406,and 12174455)the National Key R&D Program of China(2018YFA0305800)+1 种基金the Guangdong Basic and Applied Basic Research Foundation(2019B151502012,2021B1515020086,and 2021A1515010347)the Science and Technology Projects in Guangzhou(202102020960)。
文摘Higher-order topological insulators(HOTIs),with topological corner or hinge states,have emerged as a thriving topic in the field of topological physics.However,few connections have been found for HOTIs with well-explored first-order topological insulators.Recently a proposal asserted that a significant bridge can be established between the HOTIs and Z2 topological insulators.When subjected to an inplane Zeeman field,corner states,the signature of the HOTIs,can be induced in a Z2 topological insulator.Such Zeeman fields can be produced,for example,by the ferromagnetic proximity effect or magnetic atom doping,which drastically increases the experimental complexity.Here,we show that a phononic crystal,designed as a bilayer of coupled acoustic cavities,exactly hosts the Kane-Mele model with built-in in-plane Zeeman fields.The helical edge states along the zigzag edges are gapped,and the corner states,localized spatially at the corners of the samples,appear in the gap.This verifies the Zeeman field induced higher-order topology.We further demonstrate the intriguing contrast properties of the corner states at the outer and inner corners in a hexagonal ring-shaped sample.
基金Project(50605023) supported by the National Natural Science Foundation of China
文摘Plowing-extruding tool was designed and plowing-extruding process was investigated.Then,a manufacturing method of integral serrated high-finned tube,plowing-extruding based on variational feed was proposed,in which plowing-extruding tool moved forward at two different feeds,f1 and f2,in turn.In this method,overlaps that are usually avoided in practical application were utilized to manufacture high fins and average height of fins was up to 1.58 mm.The critical feed(fc) of overlaps forming and terms of high fins forming were analyzed.The main technical parameters that affect the fins height were discussed.The experimental results show that the fins height increases with extruding inclination angle and plowing-extruding depth,and the fins height increases with f1 increasing when f1 is smaller than fc,and decreases with f1 increasing if f1 is larger than fc.
