4 papers
Non-Bloch band theory for time-modulated discrete mechanical systems
Kei Matsushima, Takayuki Yamada
This study establishes a non-Bloch band theory for time-modulated discrete mechanical systems. We consider simple mass-spring chains whose stiffness is periodically modulated in ti…
Topology optimization of isotropic viscoelastic microstructures based on periodic homogenization
Hiroaki Deguchi, Kei Matsushima, Takayuki Yamada
Mitigating low-frequency noise is particularly challenging due to its limited natural attenuation. This study aims to design viscoelastic composite microstructures that achieve bot…
Exceptional points and defective resonances in an acoustic scattering system with sound-hard obstacles
Kei Matsushima, Takayuki Yamada
This paper is concerned with non-Hermitian degeneracy and exceptional points associated with resonances in an acoustic scattering problem with sound-hard obstacles. The aim is to f…
Observation of exceptional points in a spherical open elastic system
Hiroaki Deguchi, Kei Matsushima, Takayuki Yamada
Exceptional points (EPs) are spectral singularities in non-Hermitian systems where eigenvalues and their corresponding eigenstates coalesce simultaneously. In this study, we calcul…