Latest Papers in Condensed Matter Physics

Statistical Mechanics

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Fluid-structure coupling of concentric double FGM shells with different lengths (1905.00879v1)

Ehsan Moshkelgosha, Ehsan Askari, Kyeong-Hoon Jeong, Ali Shafiei

2019-05-02

The aim of this study is to develop a semi-analytical method to investigate fluid-structure coupling of concentric double shells with different lengths and elastic behaviours. Co-axial shells constitute a cylindrical circular container and a baffle submerged inside the stored fluid. The container shell is made of functionally graded materials with mechanical properties changing through its thickness continuously. The baffle made of steel is fixed along its top edge and submerged inside fluid such that its lower edge freely moves. The developed approach is verified using a commercial finite element computer code. Although the model is presented for a specific case in the present work, it can be generalized to investigate coupling of shellplate structures via fluid. It is shown that the coupling between concentric shells occurs only when they vibrate in a same circumferential mode number, n. It is also revealed that the normalized vibration amplitude of the inner shell is about the same as that of the outer shell, for narrower radial gaps. Moreover, the natural frequencies of the fluid-coupled system gradually decrease and converge to the certain values as the gradient index increases.

Two Dimensional Poincare Maps constructed through Ginzburg-Landau Theory of critical phenomena in Physics (1904.05194v2)

Yiannis Contoyiannis, Myron Kampitakis

2019-03-28

Based on the saddle point approximation in G-L theory of the critical phenomena we construct two-dimensional Poincare maps which describe the symmetry breaking (SB) and the tricritical crossover phenomenon in Physics. The phase space diagrams of these maps are in agreement with the theoretical predictions. A correction in these maps close to the critical point for small values of the order parameter is attempted. Finally we demonstrate that numerical experiments verify the correctness of these maps.

Bose-Einstein condensation in two-dimensional traps (1905.00830v1)

Mi Xie

2019-05-02

In two-dimensional traps, since the theoretical study of Bose-Einstein condensation (BEC) will encounter the problem of divergence, the actual contribution of the divergent terms is often estimated in some indirect ways with the accuracy to the leading order. In this paper, by using an analytical continuation method to solve the divergence problem, we obtain the analytical expressions of critical temperature and condensate fraction for Bose gases in a two-dimensional anisotropic box and harmonic trap, respectively. They are consistent with or better than previous studies. Then, we further consider the nonvanishing chemical potential, and obtain the expressions of chemical potential and more precise condensate fraction. These results agree with the numerical calculation well, especially for the case of harmonic traps. The comparison between the grand canonical and canonical ensembles shows that our calculation in the grand canonical ensemble is reliable.

Thermodynamics and Many Body Chaos for generalized large q SYK models (1905.00811v1)

Jiaqi Jiang, Zhenbin Yang

2019-05-02

This paper considers a type of generalized large q SYK models which include multi-body interactions between Majorana fermions. At the double scaling limit, we derive the effective action and find a universal thermodynamics relation. We also consider the chaos exponent using the retarded kernel method and find an efficient way to calculate the Lyapunov exponent for generalized large q SYK models numerically.

Aging and rejuvenation during elastostatic loading of amorphous alloys (1905.00761v1)

Nikolai V. Priezjev

2019-05-02

Using molecular dynamics simulations, we investigate the effect of uniaxial elastostatic compression on the potential energy, structural relaxation, and mechanical properties of binary glasses. We consider the three-dimensional Kob-Andersen binary mixture, which was initially cooled from the liquid state to the glass phase with a slow rate at zero pressure. The glass was then loaded with a static stress at the annealing temperature during extended time intervals. It is found that the static stress below the yielding point induces large-scale plastic deformation and significant rejuvenation when the annealing temperature is smaller than a fraction of the glass transition temperature. By contrast, aging effects become dominant at sufficiently small values of the static stress and higher annealing temperatures. The mechanical tests after the elastostatic compression have shown that both the elastic modulus and the yield stress decrease in rejuvenated samples, while the opposite trend was observed for relaxed glasses. These results might be useful for the thermomechanical processing of metallic glasses with optimized mechanical properties.

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