In this work, we choose Nb3Al/Nb3Sn as a new test case for flat/steep band model of superconductivity. Based on the density functional theory in the generalized gradient approximation, the electronic structure of Nb3A...In this work, we choose Nb3Al/Nb3Sn as a new test case for flat/steep band model of superconductivity. Based on the density functional theory in the generalized gradient approximation, the electronic structure of Nb3Al/ Nb3Sn has been studied. The obtained results agree well with those of the earlier studies and show clearly fiat bands around the Fermi level. The steep bands as characterized in this work locate around the M point in the first Brillouin zone. The obtained results reveal that Nb3Al/Nb3Sn fits more to the ＂Flat/steep＂ band model than to the van-Hove singularity scenario. The fiat/steep band condition for superconductivity implies a different thermodynamic behavior of superconductors other than that predicted from the conventional BCS theory. This observation sets up an indicator for selecting a suitable superconductor when its large-scale industrial use is needed, for example, in superconducting maglev system or ITER project.展开更多
In practical engineering structures,complex low-frequency vibrations are often encountered.However,most reported elastic metamaterials are designed for high-frequency ranges or rely on substantial additional mass to c...In practical engineering structures,complex low-frequency vibrations are often encountered.However,most reported elastic metamaterials are designed for high-frequency ranges or rely on substantial additional mass to control low-frequency vibrations,making them difficult to apply in real-world engineering scenarios.To address this limitation,we propose a homogeneous locally resonance metamaterial with tunable low-frequency bandgaps.This design overcomes the challenges associated with conventional local resonators,which are often large and heavy,making them impractical for engineering applications.By integrating resonator structures composed of elastic chiral spiral beams and mass blocks onto the supporting structure,we achieve lowfrequency vibration control within limited spaces,broadband absorption with gradient parameter units,and vibration control under different curvatures.The effectiveness of the proposed design is validated through comparative computational methods,dispersion curve calculations,frequency response simulations,and experimental tests.This study proposes a novel LRM structure with a full bandgap from 96.9 to 124 Hz.The transmittance is negative in most of the band gap range,which has been verified through numerical and experimental results.This approach effectively meets the complex low-frequency vibration control requirements of various curved structures in engineering applications,providing a viable solution for low-frequency vibration control of structures such as flat and cylindrical shells.展开更多
This work proposes a new simulation algorithm to improve message handling in discrete event formalism. We present an approach to minimize simulation execution time. To do this, we propose to reduce the number of excha...This work proposes a new simulation algorithm to improve message handling in discrete event formalism. We present an approach to minimize simulation execution time. To do this, we propose to reduce the number of exchanged messages between Parallel DEVS (PDEVS) components (simulators and coordinators). We propose three changes from PDEVS: direct coupling, flat structure and local schedule. The goal is the decentralisation of a number of tasks to make the simulators more autonomous and simplify the coordinators to achieve a greater speedup. We propose to compare the simulation results of several models to demonstrate the benefits of our approach.展开更多
基金financially supported by the Science Foundation for International Cooperation of Sichuan Province (2014HH0016)the Fundamental Research Funds for the Central Universities (SWJTU2014: A0920502051113-10000)National Magnetic Confinement Fusion Science Program (2011GB112001)
文摘In this work, we choose Nb3Al/Nb3Sn as a new test case for flat/steep band model of superconductivity. Based on the density functional theory in the generalized gradient approximation, the electronic structure of Nb3Al/ Nb3Sn has been studied. The obtained results agree well with those of the earlier studies and show clearly fiat bands around the Fermi level. The steep bands as characterized in this work locate around the M point in the first Brillouin zone. The obtained results reveal that Nb3Al/Nb3Sn fits more to the ＂Flat/steep＂ band model than to the van-Hove singularity scenario. The fiat/steep band condition for superconductivity implies a different thermodynamic behavior of superconductors other than that predicted from the conventional BCS theory. This observation sets up an indicator for selecting a suitable superconductor when its large-scale industrial use is needed, for example, in superconducting maglev system or ITER project.
基金supported by the National Key Research and Development Plan of China(Grant No.2023YFB3406302)the National Natural Science Foundation of China(Grant No.52175120)the Guangdong Basic and Applied Basic Research Foundation(Grant No.2024A1515011126)。
文摘In practical engineering structures,complex low-frequency vibrations are often encountered.However,most reported elastic metamaterials are designed for high-frequency ranges or rely on substantial additional mass to control low-frequency vibrations,making them difficult to apply in real-world engineering scenarios.To address this limitation,we propose a homogeneous locally resonance metamaterial with tunable low-frequency bandgaps.This design overcomes the challenges associated with conventional local resonators,which are often large and heavy,making them impractical for engineering applications.By integrating resonator structures composed of elastic chiral spiral beams and mass blocks onto the supporting structure,we achieve lowfrequency vibration control within limited spaces,broadband absorption with gradient parameter units,and vibration control under different curvatures.The effectiveness of the proposed design is validated through comparative computational methods,dispersion curve calculations,frequency response simulations,and experimental tests.This study proposes a novel LRM structure with a full bandgap from 96.9 to 124 Hz.The transmittance is negative in most of the band gap range,which has been verified through numerical and experimental results.This approach effectively meets the complex low-frequency vibration control requirements of various curved structures in engineering applications,providing a viable solution for low-frequency vibration control of structures such as flat and cylindrical shells.
文摘This work proposes a new simulation algorithm to improve message handling in discrete event formalism. We present an approach to minimize simulation execution time. To do this, we propose to reduce the number of exchanged messages between Parallel DEVS (PDEVS) components (simulators and coordinators). We propose three changes from PDEVS: direct coupling, flat structure and local schedule. The goal is the decentralisation of a number of tasks to make the simulators more autonomous and simplify the coordinators to achieve a greater speedup. We propose to compare the simulation results of several models to demonstrate the benefits of our approach.
