In this paper, a novel three‐dimensional (3D) cellular structure with negative Poisson's ratio was designed by alternating cuboid surface indents on the vertical ribs of the unit cells. The Poisson's ratio and Young's modulus of structures with different geometric parameters were determined using the finite element method (FEM) as a function of these parameters. Samples with identical geometric variables were fabricated via 3D printing, and their through‐thickness direction Poisson's ratios were measured and compared with simulation results. Results showed that the Poisson's ratio of the 3D cellular structures can be tuned from positive to negative and can reach a minimal value of −0.958. Good agreement was found between the experimental results and the simulation. This lattice structure is considerably stiffer than re‐entrant negative Poisson's ratio foam with the same solid phase. The design concept developed here can be optimized for specific applications via geometric parameters manipulation.
The electromagnatically induced absorption (EIA) is obtained in degenerated cycled cesium atomic two-level transition of 6S1/2F=4—6P3/2F'=5. The effect of the magnetic field on coherence of the atom is also investigated experimentally. When external magnetic field is applied, the mixed structure of electromagnetically induced absorption and transparency is obtained in the transition of 6S1/2F=4—6P3/2F'=5. The experimental results are in agreement with theoretical analysis of C.Y. Ye et al. (2002).
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