Polymer composite films with high energy density as well as high efficiency are promising dielectric materials in pulsed power systems. In improving the energy discharged efficiency, poly vinylidene fluoride-hexafluoropropylene [P(VDF-HFP)] film blended with 20 vol.% poly(methylmethacrylate) (PMMA), which has a much slimmer ferroelectric hysteresis loop, is employed as the polymer matrix. Highly dispersive Ba 0.6 Sr 0.4 TiO 3 (BST) nanoparticles with an average particle size of 12.1 nm are utilised to improve the polarisation of the blend film without sacrificing the dielectric strength. Uniform nanocomposite films with high flexibility and excellent energy-storage performance are obtained. Especially, due to the optimisation of both polymer matrix and fillers, the BST modified P(VDF-HFP)/PMMA blend films show improved breakdown strength and depressed energy loss, which leads to an enhanced energy density of 10.3 J/cm 3 at 378 kV/mm.

In this paper, we introduce an aspiration-dependent persistence into the spatial prisoner's dilemma game aimed at promoting cooperation in a population. Based on aspiration, a player could adjust his/her strategy persistence level during the evolutionary process. In particular, he/she will hold a strategy longer if it brings him/her a satisfactory payoff, otherwise he/she will decrease the time duration of keeping the present choice. We also introduce a tunable parameter to characterize the sensitivity of strategy persistence to aspiration and investigate the effects of the sensitivity on the evolution of cooperation. The results show that aspirationdependent strategy persistence could effectively promote cooperation. At an intermediate aspiration, diverse strategy persistence levels among population could be formed during the evolution, which ultimately results in the highest cooperation level. Then, we present intuitive explanations for the existence of optimal aspiration by scrutinizing the microscopic evolution of cooperation. Moreover, we find that, in the population where individuals are more sensitive to aspiration, cooperation could be further promoted by assembling greater cooperator clusters with the help of diverse strategy persistence distribution. Our results highlight the more realistic scenario where aspiration-dependent persistence is involved in the spatial prisoner's dilemma game.

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Abstract. In the evolution of cooperation, the motion of players plays an important role. In this paper, we incorporate, into an evolutionary prisoner dilemma's game on networks, a new factor that cooperators and defectors move with different probabilities. By investigating the dependence of the cooperator frequency on the moving probabilities of cooperators and defectors, µ c and µ d , we find that cooperation is greatly enhanced in the parameter regime of µ c < µ d . The snapshots of strategy pattern and the evolutions of cooperator clusters and defector clusters reveal that either the fast motion of defectors or the slow motion of cooperators always favors the formation of large cooperator clusters. The model is investigated on different types of networks such as square lattices, Erdös-Rényi networks and scale-free networks and with different types of strategy-updating rules such as the richest-following rule and the Fermi rule. The numerical results show that the observed phenomena are robust to different networks and to different strategy-updating rules.

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