Kuramoto-like model is adopted to model a power grid reasonably. And critical synchronization coupling strength and average synchronization error are used to describe synchronization ability and robustness of a power grid, respectively. It is found that power distribution of generators has a great influence on transmission power of lines, and the more high-load lines in power grid, the more difficult the network synchronization. Based on the discovery, we calculate transmission power of each line under uniform power distribution method of generators (EG mode). Then, based on a power flow tracking algorithm, an non-uniform power distribution method (TG mode) of the generators is further proposed. With this method, as the total amount of power generated is given, power of the hub generator node is increased and power of the edge generator node is reduced. It shows that the new power distribution strategy reduces effectively critical synchronization coupling strength and average synchronization error. Thus the method improves synchronization performance and robustness of a power grid.

We study thermodynamic stability, mechanical properties, and microscopic mechanisms of transition metal monoboride TMB (take TiB, VB and CrB in 3d series; ZrB, NbB and MoB in 4d series; HfB, TaB and WB in 5d series as examples) by first-principles calculations based on density functional theory and plane pseudopotential wave method. We found thermodynamic stability and hardness anomalies of transition metal monoborides. In particular, as valence electron concentration is 8 e·(f.u.)^-1, thermodynamic stability is the most stable and hardness is the highest. To reveal its mechanism, we calculated electronic structure of TMB. As valence electron concentration of TMB is at 8 e·(f.u.)^-1, covalent bonding of pd blocked effectively dislocation slipping between metal bilayers, prevented shear deformation, and resulted in high hardness. These discoveries may help new superhard material designs.

Based on mesoscopic heterogeneity theory model of Pride and Berryman, coupled dynamical equations were deduced with a group of displacements, and a group with displacement and pore pressure. With double-porosity model, elastic wave expression of phase velocity and inverse quality factor are deduced. Influence of mesoscopic flow on propagation of elastic waves was discussed. Numerical examples show that velocity of fast wave increases rapidly with increase of frequency, and mesoscopic flow loss is at least higher one order of magnitude than Biot loss. Besides, mesoscopic flow has different influence on slow wave. It is proved that mesoscopic flow is the main factor of wave energy loss and velocity dispersion.

An iterative physical optics(IPO) method combined with multilevel fast multipole algorithm(MLFMA) is used to solve electromagnetic scattering by a three-dimensional complex cavity efficiently and rapidly.The iterative formulations of hybrid algorithm are derived.For slow bending cavities in engineering,a proper subsection structured grouping method is provided to avoid the shelter of facets between two groups.A generalized reciprocity integral(GRI) method is applied to cavities with complex termination.The methods obtain accurate results and improve computing speed.

A simple genetic algorithm(SGA) is modified to form self-adaptive genetic algorithm(SAGA) in aerodynamic optimization design. Real number coding skill is used in the algorithm to represent individuals of population, while binary coding and encoding are not required. In order to improve the quality and efficiency of optimization design, crossover and mutation operators are designed with respect to specified problem. Then self-adaptive genetic algorithm is adopted to maximize lift-to-drag ratio of transonic airfoil and wing as examples. Analysis approves the designed results reasonable.