Formulation method of ball indentation process for ultra-thin elastic body with mechanics poisson effect

A new theoretical method for determining the mechanics properties of ultra-thin elastic materials is proposed in this paper. This method is based on a full contact model and Poisson’s effect. This study consisted of three steps. First, FE model of indentation problem for ultra-thin specimen is developed by elastic constitutive relationship for precise analysis of problem. Second, the simplified model is used to evaluate the result of FEM, and its availability is discussed by comparison with extended Hertzian theory. Third, an equation is proposed after comparing the results of FEM, extended Hertzian theory and full contact model

Observation of Fast Evolution in Parity-Time-Symmetric System

To find and realize the optimal evolution between two states is significant both in theory and application. In quantum mechanics, the minimal evolution is bounded by the gap between the largest and smallest eigenvalue of the Hamiltonian. In the parity-time-symmetric(PT-symmetric) Hamiltonian theory, it was predicted that the optimized evolution time can be reduced drastically comparing to the bound in the Hermitian case, and can become even zero. In this Letter, we report the experimental observation of the fast evolution of a PT-symmetric Hamiltonian in an nuclear magnetic resonance (NMR) quantum system. The experimental results demonstrate that the PT-symmetric Hamiltonian can indeed evolve much faster than that in a quantum system, and time it takes can be arbitrary close to zero.Comment: 13 pages, 5 figure