本文主要介绍FREQUENTIS VCS3020X Vel 7.0内话系统,在投入空中交通管制过程中,为满足管制员在不同时期的不同需求,通过修改TMCS的相应配置,包括配置不同电话类型,修改内话席位图布局等日常维护,以达到管制员要求。由于FREQUENTIS内话...本文主要介绍FREQUENTIS VCS3020X Vel 7.0内话系统,在投入空中交通管制过程中,为满足管制员在不同时期的不同需求,通过修改TMCS的相应配置,包括配置不同电话类型,修改内话席位图布局等日常维护,以达到管制员要求。由于FREQUENTIS内话系统具有较高的可靠性和较强的实用性,正越来越多地被广泛使用于空中交通管制用途。展开更多
Electronic devices pervade everyday life,which has triggered severe electromagnetic(EM)wave pollution.To face this challenge,developing EM wave absorbers with ultra-broadband absorption capacity is critically required...Electronic devices pervade everyday life,which has triggered severe electromagnetic(EM)wave pollution.To face this challenge,developing EM wave absorbers with ultra-broadband absorption capacity is critically required.Currently,nano-composite construction has been widely utilized to realize impedance match and broadband absorption.However,complex experimental procedures,limited thermal stability,and interior oxidation resistance are still unneglectable issues.Therefore,it is appealing to realize ultra-broadband EM wave absorption in single-phase materials with good stability.Aiming at this target,two high-entropy transition metal carbides(HE TMCs)including(Zr,Hf,Nb,Ta)C(HE TMC-2)and(Cr,Zr,Hf,Nb,Ta)C(HE TMC-3)are designed and synthesized,of which the microwave absorption performance is investigated in comparison with previously reported(Ti,Zr,Hf,Nb,Ta)C(HE TMC-1).Due to the synergistic effects of dielectric and magnetic losses,HE TMC-2 and HE TMC-3 exhibit better impedance match and wider effective absorption bandwidth(EAB).In specific,the exclusion of Ti element in HE TMC-2 endows it optimal minimum reflection loss(RL_(min))and EAB of−41.7 dB(2.11 mm,10.52 GHz)and 3.5 GHz(at 3.0 mm),respectively.Remarkably,the incorporation of Cr element in HE TMC-3 significantly improves the impedance match,thus realizing EAB of 10.5,9.2,and 13.9 GHz at 2,3,and 4 mm,respectively.The significance of this study lays on realizing ultra-broadband capacity in HE TMC-3(Cr,Zr,Hf,Nb,Ta),demonstrating the effectiveness of high-entropy component design in tailoring the impedance match.展开更多
Reinforcement distribution tailoring has been proven effective in strengthening and toughening titanium matrix composites(TMCs).In this work,the analysis of the Ti64(Ti-6Al-4V)-B phase diagram indicated that B content...Reinforcement distribution tailoring has been proven effective in strengthening and toughening titanium matrix composites(TMCs).In this work,the analysis of the Ti64(Ti-6Al-4V)-B phase diagram indicated that B content dominates the TiB distribution.With this philosophy,B content regulation was applied to tailor homogeneous and network structures in Ti64-B composites fabricated via laser-directed energy deposition additive manufacturing(AM).The unique plate-like TiB attends inhomogeneous composites(Ti64–0.05B).However,in network composite(Ti64–0.25B),the TiB whisker(TiBw)arranges along priorβ-Ti grains with the same orientation.Moreover,the synergistic improvement of strength(988 MPa→1202 MPa),stiffness(106 GPa→116 GPa),hardness(325 HV→362 HV),and uniform elongation(5%→7.8%)were achieved.This work exhibited a balanced strength/ductility trade-off,which provides a good guide on microstructure tailoring.展开更多
TiB/Ti-1.5Fe-2.25Mo composites were synthesized in situ using the spark plasma sintering （SPS） method at temperatures of 850-1150 °C. The effect of the sintering temperature on microstructure and mechanical pro...TiB/Ti-1.5Fe-2.25Mo composites were synthesized in situ using the spark plasma sintering （SPS） method at temperatures of 850-1150 °C. The effect of the sintering temperature on microstructure and mechanical properties of the composites was investigated. The results indicate that the aspect ratio of the in situ synthesized TiB whiskers in Ti alloy matrix decreases rapidly with an increase in sintering temperature. However, both the relative density of the sintered specimens and the volume content of TiB whiskers in composites increase with increasing sintering temperature. Thus, the bending strength of the composites synthesized using SPS process increases slowly with increasing the sintering temperature from 850 to 1150 °C. TiB/Ti-1.5Fe-2.25Mo composite synthesized at 1150 °C using SPS method exhibits the highest bending strength of 1596 MPa due to the formation of fine TiB whiskers in Ti alloy matrix and the dense microstructure of the composite.展开更多
文摘本文主要介绍FREQUENTIS VCS3020X Vel 7.0内话系统,在投入空中交通管制过程中,为满足管制员在不同时期的不同需求,通过修改TMCS的相应配置,包括配置不同电话类型,修改内话席位图布局等日常维护,以达到管制员要求。由于FREQUENTIS内话系统具有较高的可靠性和较强的实用性,正越来越多地被广泛使用于空中交通管制用途。
基金We gratefully acknowledge the financial support from the National Natural Science Foundation of China(Nos.51972089,51672064,and U1435206).
文摘Electronic devices pervade everyday life,which has triggered severe electromagnetic(EM)wave pollution.To face this challenge,developing EM wave absorbers with ultra-broadband absorption capacity is critically required.Currently,nano-composite construction has been widely utilized to realize impedance match and broadband absorption.However,complex experimental procedures,limited thermal stability,and interior oxidation resistance are still unneglectable issues.Therefore,it is appealing to realize ultra-broadband EM wave absorption in single-phase materials with good stability.Aiming at this target,two high-entropy transition metal carbides(HE TMCs)including(Zr,Hf,Nb,Ta)C(HE TMC-2)and(Cr,Zr,Hf,Nb,Ta)C(HE TMC-3)are designed and synthesized,of which the microwave absorption performance is investigated in comparison with previously reported(Ti,Zr,Hf,Nb,Ta)C(HE TMC-1).Due to the synergistic effects of dielectric and magnetic losses,HE TMC-2 and HE TMC-3 exhibit better impedance match and wider effective absorption bandwidth(EAB).In specific,the exclusion of Ti element in HE TMC-2 endows it optimal minimum reflection loss(RL_(min))and EAB of−41.7 dB(2.11 mm,10.52 GHz)and 3.5 GHz(at 3.0 mm),respectively.Remarkably,the incorporation of Cr element in HE TMC-3 significantly improves the impedance match,thus realizing EAB of 10.5,9.2,and 13.9 GHz at 2,3,and 4 mm,respectively.The significance of this study lays on realizing ultra-broadband capacity in HE TMC-3(Cr,Zr,Hf,Nb,Ta),demonstrating the effectiveness of high-entropy component design in tailoring the impedance match.
文摘Reinforcement distribution tailoring has been proven effective in strengthening and toughening titanium matrix composites(TMCs).In this work,the analysis of the Ti64(Ti-6Al-4V)-B phase diagram indicated that B content dominates the TiB distribution.With this philosophy,B content regulation was applied to tailor homogeneous and network structures in Ti64-B composites fabricated via laser-directed energy deposition additive manufacturing(AM).The unique plate-like TiB attends inhomogeneous composites(Ti64–0.05B).However,in network composite(Ti64–0.25B),the TiB whisker(TiBw)arranges along priorβ-Ti grains with the same orientation.Moreover,the synergistic improvement of strength(988 MPa→1202 MPa),stiffness(106 GPa→116 GPa),hardness(325 HV→362 HV),and uniform elongation(5%→7.8%)were achieved.This work exhibited a balanced strength/ductility trade-off,which provides a good guide on microstructure tailoring.
基金Prject(20111D0503200316)supported by the Programme for Peking Excellent Talents in University,ChinaProject(613135)supported by 973 Defence Plan of China
文摘TiB/Ti-1.5Fe-2.25Mo composites were synthesized in situ using the spark plasma sintering （SPS） method at temperatures of 850-1150 °C. The effect of the sintering temperature on microstructure and mechanical properties of the composites was investigated. The results indicate that the aspect ratio of the in situ synthesized TiB whiskers in Ti alloy matrix decreases rapidly with an increase in sintering temperature. However, both the relative density of the sintered specimens and the volume content of TiB whiskers in composites increase with increasing sintering temperature. Thus, the bending strength of the composites synthesized using SPS process increases slowly with increasing the sintering temperature from 850 to 1150 °C. TiB/Ti-1.5Fe-2.25Mo composite synthesized at 1150 °C using SPS method exhibits the highest bending strength of 1596 MPa due to the formation of fine TiB whiskers in Ti alloy matrix and the dense microstructure of the composite.
