Double-column bridge piers are prone to local damage during earthquakes,leading to the destruction of bridges.To improve the earthquake resistance of double-column bridge piers,a novel swing column device(SCD),consist...Double-column bridge piers are prone to local damage during earthquakes,leading to the destruction of bridges.To improve the earthquake resistance of double-column bridge piers,a novel swing column device(SCD),consisting of a magnetorheological(MR)damper,a current controller,and a swing column,was designed for the present work.To verify the seismic energy dissipation ability of the SCD,a lumped mass model for a double-column bridge pier with the SCD was established according to the low-order modeling method proposed by Steo.Furthermore,the motion equation of the double-column bridge pier with the SCD was established based on the D′Alembert principle and solved with the use of computational programming.It was found that the displacement response of the double-column bridge pier was effectively controlled by the SCD.However,due to rough current selection and a time delay,there is a significant overshoot of the bridge acceleration using SCD.Hence,to solve the overshoot phenomenon,a current controller was designed based on fuzzy logic theory.It was found that the SCD design based on fuzzy control provided an ideal shock absorption effect,while reducing the displacement and acceleration of the bridge pier by 36.43%‒40.63%and 30.06%‒33.6%,respectively.展开更多
The persistent pursuit of miniaturization and energy efficiency in semiconductor technology has driven the scaling of complementary metal-oxide-semiconductor field-effect transistors(CMOS FETs,i.e.,the MOSFETs)to thei...The persistent pursuit of miniaturization and energy efficiency in semiconductor technology has driven the scaling of complementary metal-oxide-semiconductor field-effect transistors(CMOS FETs,i.e.,the MOSFETs)to their physical limits.Conventional MOSFETs face intrinsic challenges,especially the Boltzmann limit that imposes a fundamental lower bound on the subthreshold swing(SS≥60 mV dec^(−1)at room temperature).This limitation severely restricts voltage scaling and exacerbates static power dissipation.To overcome these bottlenecks,tunnel field-effect transistors(TFETs)have emerged as a promising post-CMOS alternative.The advantages of ultra-small SS well below the Boltzmann limit,as well as ultralow leakage currents,make TFETs ideal for low-power electronics and energy-efficient computing in the future information industry.However,its current development has encountered significant resistance to further performance improvement requirements;new breakthroughs have evolved to be based on interdisciplinary research that covers materials science,device technology,theoretical physics,and so on.Here,we provide a review on the design and development of TFET,which mainly describes the device physics model of tunnel junctions,and discusses the optimization direction of key parameters,the design direction of potential structures,and the development direction of the innovation system based on the device physics.Also,we visualize the framework for the figures of merit of TFET performance and further forecast the future applications of TFET.展开更多
文摘Double-column bridge piers are prone to local damage during earthquakes,leading to the destruction of bridges.To improve the earthquake resistance of double-column bridge piers,a novel swing column device(SCD),consisting of a magnetorheological(MR)damper,a current controller,and a swing column,was designed for the present work.To verify the seismic energy dissipation ability of the SCD,a lumped mass model for a double-column bridge pier with the SCD was established according to the low-order modeling method proposed by Steo.Furthermore,the motion equation of the double-column bridge pier with the SCD was established based on the D′Alembert principle and solved with the use of computational programming.It was found that the displacement response of the double-column bridge pier was effectively controlled by the SCD.However,due to rough current selection and a time delay,there is a significant overshoot of the bridge acceleration using SCD.Hence,to solve the overshoot phenomenon,a current controller was designed based on fuzzy logic theory.It was found that the SCD design based on fuzzy control provided an ideal shock absorption effect,while reducing the displacement and acceleration of the bridge pier by 36.43%‒40.63%and 30.06%‒33.6%,respectively.
基金supported by the Research Grants Council of Hong Kong(RGC GRF No.15304224,PolyU SRFS2122-5S02,AoE/P-701/20)PolyU Project of 1-YWBG and RCNN 1-CE0H.
文摘The persistent pursuit of miniaturization and energy efficiency in semiconductor technology has driven the scaling of complementary metal-oxide-semiconductor field-effect transistors(CMOS FETs,i.e.,the MOSFETs)to their physical limits.Conventional MOSFETs face intrinsic challenges,especially the Boltzmann limit that imposes a fundamental lower bound on the subthreshold swing(SS≥60 mV dec^(−1)at room temperature).This limitation severely restricts voltage scaling and exacerbates static power dissipation.To overcome these bottlenecks,tunnel field-effect transistors(TFETs)have emerged as a promising post-CMOS alternative.The advantages of ultra-small SS well below the Boltzmann limit,as well as ultralow leakage currents,make TFETs ideal for low-power electronics and energy-efficient computing in the future information industry.However,its current development has encountered significant resistance to further performance improvement requirements;new breakthroughs have evolved to be based on interdisciplinary research that covers materials science,device technology,theoretical physics,and so on.Here,we provide a review on the design and development of TFET,which mainly describes the device physics model of tunnel junctions,and discusses the optimization direction of key parameters,the design direction of potential structures,and the development direction of the innovation system based on the device physics.Also,we visualize the framework for the figures of merit of TFET performance and further forecast the future applications of TFET.
