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pro vyhledávání: '"Nemat‐Nasser, Sia"'
Autor:
Nemat-Nasser, Sia
Guided by theoretical predictions, we have demonstrated experimentally the existence of negative refraction on the lowest two (acoustic) passbands (shear and longitudinal modes) of a simple two dimensional phononic crystal consisting of an isotropic
Externí odkaz:
http://arxiv.org/abs/1709.07768
Autor:
Hasan, M. Arif, Nemat-Nasser, Sia
Publikováno v:
Phys. Rev. E 97, 022205 (2018)
Solitary waves (SWs) are generated in monoatomic (homogeneous) lightly contacting spherical granules by an applied input force of any time-variation and intensity. We consider finite duration shock loads and focus on the transition regime that leads
Externí odkaz:
http://arxiv.org/abs/1704.03068
Autor:
Sadeghi, Hossein, Nemat-Nasser, Sia
A two-dimensional phononic crystal (PC) can exhibit longitudinal-mode negative energy refraction on its lowest (acoustical) frequency pass band. The effective elastodynamic properties of a typical PC are calculated and it is observed that the compone
Externí odkaz:
http://arxiv.org/abs/1612.00037
The material properties selection for designing acoustic filters with optimal performance over a range of frequencies requires considerable effort to fabricate and test laboratory samples. To simplify this procedure, one may test a single sample at v
Externí odkaz:
http://arxiv.org/abs/1611.10005
Autor:
Nemat-Nasser, Sia
It is shown, for the first time, that negative refraction with positive phase velocity refraction can be realized (and controlled) over a wide range of frequency on the first (lowest) pass band of simple photonic and phononic crystals. First a unifie
Externí odkaz:
http://arxiv.org/abs/1603.03746
Autor:
Hasan, M. Arif, Nemat-Nasser, Sia
We focus on solitary waves generated in arrays of lightly contacting spherical elastic granules by shock forces of steep rise and slow decay durations, and establish a priori: (i) whether the peak value of the resulting solitary wave would be greater
Externí odkaz:
http://arxiv.org/abs/1502.04073
Autor:
Sadeghi, Hossein, Nemat-Nasser, Sia
A systematic method for optimal design of layered periodic composites for mitigation of impact-induced shock waves is presented. Frequency spectrum of a pulse with a sharp rise-time is analyzed and the frequency range that carries most of the pulse e
Externí odkaz:
http://arxiv.org/abs/1412.5684
Autor:
Nemat-Nasser, Sia
The refraction properties of phononic crystals are revealed by examining the anti-plane shear waves in doubly periodic elastic composites with unit cells containing rectangular and/or elliptical inclusions. The band-structure, group velocity, and ene
Externí odkaz:
http://arxiv.org/abs/1412.4019
Autor:
Srivastava, Ankit, Nemat-Nasser, Sia
This paper presents phononic band-structure calculation results obtained using a mixed variational formulation for 1-, and 2-dimensional unit cells. The formulation itself is presented in a form which is equally applicable to 3-dimensiomal cases. It
Externí odkaz:
http://arxiv.org/abs/1411.2996
Autor:
Srivastava, Ankit, Nemat-Nasser, Sia
Recent years have seen considerable research success in the field of dynamic homogenization which seeks to define frequency dependent effective properties for heterogeneous composites for the purpose of studying wave propagation. There is an approxim
Externí odkaz:
http://arxiv.org/abs/1411.2999