Searcharxiv⌕ Search

arXiv subjects

Pi-Gang Luan

Publications and source records attributed to Pi-Gang Luan.

24 records · Page 2Linked to original sources
arXiv2001

Statistics of Lyapunov exponent in one-dimensional layered systems

Localization of acoustic waves in a one dimensional water duct containing many randomly distributed air filled blocks is studied. Both the Lyapunov exponent and its variance are computed. Their statistical properties are also explored extensively. The results reveal that in this system the single parameter scaling is generally inadequate no matter whether the frequency we consider is located in a pass band or in a band gap. This contradicts the earlier observations in an optical case. We compare the results with two optical cases and give a possible explanation of the origin of the different behaviors.

cond-mat↗
arXiv2001

Two dimensional photonic crystals

The topology, the symmetry involving the shape of dielectric cylinders, and the lattice structure are among the most important ingredients in the architecture of photonic crystals. In this paper, we present a systematic derivation of the formulas which are needed in computing the photonic band structures of many commonly used two dimensional lattice structures and dielectric cylinders with various kinds of symmetries and rotations. Further the results are applied to arrays of hollow cross-shaped cylinders embedded in the alumina ceramic background. A large complete photonic band gap is found in the high frequency regime.

cond-mat↗
arXiv2000

Acoustic radiation in randomly-layered structures

Radiation from acoustic sources located inside randomly-layered structures is studied using the transfer matrix method. It is shown that in contrast to the periodically layered cases where the radiation can be either enhanced or inhibited depending on the frequency, and the characteristics and the material composition of the structures, in the random structures the radiation is always inhibited. The degree of inhibition depends on the acoustic frequency, number of random layers, and the randomness and acoustic parameters of the structures. Both spherically and cylindrically random structures are considered. The results point to the possibility of designing sonic waveguide devices which will not suffer from the energy loss caused by radiation, thus allowing effective energy confinement or long-range energy propagation.

cond-mat↗
arXiv2000

Acoustic wave propagation in an one-dimensional layered system

Propagation of acoustic waves in an one-dimensional water duct containing many air filled blocks is studied by the transfer matrix formalism. Energy distribution and interface vibration of the air blocks are computed. For periodic arrangement band structure and transmission rate are calculated analytically, whereas the Lyapunov exponent and its variance are computed numerically for random situations. A distinct collective behavior for localized waves is found. The results are also compared with optical situations.

cond-mat↗
arXiv2000

Localization of acoustic waves in 1D random liquid media

We study acoustic propagation in one dimensional water ducts containing many air-filled blocks. The acoustic band structures for the periodic arrangements of the blocks is calculated, whereas the transmission for various random configurations of the blocks is computed by the transfer matrix method. It is shown that waves at all frequencies become localized even with a small amount of randomness. The spatial distribution of the localized energy is investigated, and is shown not to be trapped near the source, contrary to higher dimensional cases. The results also reveal a distinct collective behaviour for localized waves, a feature useful for distinguishing the localization from the residual absorption effect.

cond-mat↗