Apparent horizon and gravitational thermodynamics of Universe in the Eddington-Born-Infeld theory

The thermodynamics of Universe in the Eddington-Born-Infeld (EBI) theory was restudied by utilizing the holographic-style gravitational equations that dominate the dynamics of the cosmical apparent horizon $\Upsilon_{A}$ and the evolution of Universe. We started in rewriting the EBI action of the Palatini approach into the Bigravity-type action with an extra metric $q_{\mu\nu}$. With the help of the holographic-style dynamical equations, we discussed the property of the cosmical apparent horizon $\Upsilon_{A}$ including timelike, spacelike and null characters, which depends on the value of the parameter of state $w_{m}$ in EBI Universe. The unified first law for the gravitational thermodynamics and the total energy differential for the open system enveloped by $\Upsilon_{A}$ in EBI Universe were obtained. Finally, applying the positive-heat-out sign convention, we derived the generalized second law of gravitational thermodynamics in EBI universe.Comment: 23 pages, 0 figure

Crystal Polymorph Control for High-Performance Organic Field-Effect Transistors

Organic molecules are assembled together by weak non-covalent intermolecular interactions in solid state. Multiple crystalline packing states (crystal polymorphism) have commonly existed in the active layer for organic field-effect transistors (OFETs). Different polymorphs, even with the slightest changes in their molecular packing, can differ the charge transport mobility by orders of magnitude. Therefore, accessing new polymorphs can serve as a novel design strategy for attaining high device performance. Here, we review the state of the art in this emerging field of crystal polymorph control. We firstly introduce the role of polymorphism and the methods of polymorph control in organic semiconductors. Then we review the latest studies on the performance of polymorphs in OFET devices. Finally, we discuss the advantages and challenges for polymorphism as a platform for the study of the relationship between molecular packing and charge transport

Numerical simulation research of vortex-induced vibrations of the long circular cylinders with high mass-ratio

The two-degrees-of-freedom vortex-induced vibrations (VIV) of the long circular cylinders with high mass-ratio are numerically simulated with the software ANSYS/CFX. The VIV characteristic of the cylinder is analyzed in the different conditions (Ur = 3, 5, 6, 8, 10). When Ur is 5, 6, 8 and 10, the conclusion is different from the vortex-induced vibrations of the cylinder with low mass-ratio. When Ur is 3, the frequency of the drag force on the cylinder is twice of that of the lift force and the in-line VIV frequency of the cylinder is twice of that of the cross-flow VIV. The in-line VIV amplitude of the cylinder is much smaller than the cross-flow VIV amplitude. The motion trace is the crescent. When Ur is 5 and 6, the frequency ratio between the drag force and lift force is still 2, but the main in-line VIV frequency of the cylinder is mainly the same as that of the cross-flow VIV and the secondary in-line VIV frequency is equal to the frequency of the drag force. The in-line VIV amplitude is still very small compared with the cross-flow VIV amplitude. When Ur is up to 8 and 10, the in-line VIV frequency of the cylinder is the same as the main frequency of the cross-flow VIV which is close to the inherent frequency of the cylinder and is different from the frequency of the drag force or lift force. But the secondary cross-flow VIV frequency of the cylinder is equal to the frequency of the lift force. The amplitude ratio between in-line VIV and cross-flow VIV is about 0.5. When Ur is 5, 6, 8 and 10, the motion trace is mainly the oval