Biomedical subjects

Cheng-Hung Chang

Publications and source records attributed to Cheng-Hung Chang.

4 recordsLinked to original sources

PubMed2003

Transfer operator approach on three-dimensional quantum billiards with SO(2) symmetry.

This work demonstrates the application of Bogomolny's transfer operator method on three-dimensional dynamics. Motivated by experimental observations of lenslike metal clusters, the quantum billiards bounded by a flat bottom and an upper surface with SO(2) symmetry are studied. A precise determination of the energies with error less than 0.05% and exact predicted degeneracies in the special case of the half-sphere billiard confirm the efficiency of this method. Furthermore, the spectra and degeneracies of lens billiards with varying heights are explicitly determined.

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PubMed2003

Truncation and reset process on the dynamics of Parrondo's games.

The counter-intuitive feature of Parrondo's games is illustrated on various dynamical systems combined from different deterministic and stochastic subsystems. The concept of truncation and reset process is introduced, which provides a transparent perspective to understand the underlying mechanism of this class of dynamics, including the transport of flashing ratchets, and clarifies the puzzlement why random switching between two games can generate reversal dynamics as periodical switching does.

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PubMed2002

Quantization conditions in Bogomolny's transfer operator method.

Bogomolny's transfer operator method plays a significant role in the study of quantum chaos, along with other well known methods like Gutzwiller's trace formula and the dynamical zeta function, which generalize the Einstein-Brillouin-Keller quantization rule from integrable systems to chaotic systems. According to the theory, the Fredholm determinant of the transfer operator, defined on a Poincaré section of a classical physical system, provides a quantization condition to the energy spectrum of the corresponding quantum system. This study presents two factorization formulas, which relate different quantization conditions defined on different classical trajectory segments. These explicit relations answer the question of why all these classical quantization conditions determine exactly the same energy spectrum of the corresponding quantum systems. As an example, these formulas are illustrated in the equilateral triangular billiard.

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PubMed2002

Ratchet models using driving forces generated by deterministic chaotic maps.

This study investigates how ratchets perform under driving forces generated by the circle, baker, and logistic maps with varying driving frequencies. The markedly different unidirectional net transports induced by distinct maps and frequencies are clarified by vector field analysis of the ratchet equations. Analysis results indicate that both the deterministic property of the driving forces and the asymmetric effect due to the ratchet potential impact the transport. Moreover, the driving frequency determines which factor suppresses the other one and dominates the ratchet transport.

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