Cascading failures in coupled networks with both inner-dependency and inter-dependency links

We study the percolation in coupled networks with both inner-dependency and inter-dependency links, where the inner- and inter-dependency links represent the dependencies between nodes in the same or different networks, respectively. We find that when most of dependency links are inner- or inter-ones, the coupled networks system is fragile and makes a discontinuous percolation transition. However, when the numbers of two types of dependency links are close to each other, the system is robust and makes a continuous percolation transition. This indicates that the high density of dependency links could not always lead to a discontinuous percolation transition as the previous studies. More interestingly, although the robustness of the system can be optimized by adjusting the ratio of the two types of dependency links, there exists a critical average degree of the networks for coupled random networks, below which the crossover of the two types of percolation transitions disappears, and the system will always demonstrate a discontinuous percolation transition. We also develop an approach to analyze this model, which is agreement with the simulation results well.Comment: 9 pages, 4 figure

The puzzle of anomalously large isospin violations in η(1405/1475)→3π\eta(1405/1475)\to 3\pi

The BES-III Collaboration recently report the observation of anomalously large isospin violations in $J/\psi\to \gamma\eta(1405/1475) \to \gamma \pi^0 f_0(980)\to \gamma +3\pi$, where the $f_0(980)$ in the $\pi\pi$ invariant mass spectrum appears to be much narrower ($\sim$ 10 MeV) than the peak width ($\sim$50 MeV) measured in other processes. We show that a mechanism, named as triangle singularity (TS), can produce a narrow enhancement between the charged and neutral $K\bar{K}$ thresholds, i.e., $2m_{K^\pm}\sim 2m_{K^0}$. It can also lead to different invariant mass spectra for $\eta(1405/1475)\to a_0(980)\pi$ and $K\bar{K}^*+c.c.$, which can possibly explain the long-standing puzzle about the need for two close states $\eta(1405)$ and $\eta(1475)$ in $\eta\pi\pi$ and $K\bar{K}\pi$, respectively. The TS could be a key to our understanding of the nature of $\eta(1405/1475)$ and advance our knowledge about the mixing between $a_0(980)$ and $f_0(980)$.Comment: 4 pages and 7 eps figures; Journal-matched versio

A study of vortex ring generation by a circular disc

A vortex ring is a region where the fluid mostly spins around an imaginary axis line that forms a closed loop. It is a fundamental phenomenon for the fluid passing by an object. In general, there are two methods associated with the axisymmetric vortex generation: fluid discharge from an orifice or a nozzle, and disc start-up instantly. Recent study by Yang (2012) showed that the different mechanisms of vortex generation could lead to a similar formation process and a universal principle of the optimal vortex formation could exist. Present work is mainly based on a numerical simulation study of disc vortex ring formation. A commercial Computational Fluid Dynamics solver is employed to carry out the simulation. The simulation parameters are selected the same as those of Yang’s (2012) experimental study. The model is built with fluid passing by a 30mm diameter and 2mm thickness disc in a large computational domain. The simulation results are validated with experimental data. By studying the Iso-surface, representative values, i.e. size of both vortex ring and vortex ring core, circulation and kinetic energy during the formation phases of the vortex ring are investigated. Comparison and analyses between the numerical simulation and the experimental data will be given in detail

A Model of Two-Way Selection System for Human Behavior

We propose a model of two-way selection system. It appears in the processes like choosing a mate between men and women, making contracts between job hunters and recruiters, and trading between buyers and sellers. In this paper, we propose a model of two-way selection system, and present its analytic solution for the expectation of successful matching total and the regular pattern that the matching rate trends toward an inverse proportion to either the ratio between the two sides or the ratio of the state total to the smaller people number. The proposed model is verified by empirical data of the matchmaking fairs. Results indicate that the model well predicts this typical real-world two- way selection behavior to the bounded error extent, thus it is helpful for understanding the dynamics mechanism of the real-world two-way selection system.Comment: 8 pages, 4 figure

Effects of heritability on evolutionary cooperation in spatial prisoner’s dilemma games

AbstractWe study the effects of heritability on the evolution of the spatial prisoner’s dilemma game. In our model, the fitness of each player is composed of the instantaneous payoff from the interactions and the inherited fitness from the last generation. Based on extensive simulations, we find that the density of cooperators is enhanced by increasing the heritability of players over a wide range of the model parameter. The mean fitness of cooperators and defectors are also studied for understanding our results