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Coarse-graining techniques of large-scale complex networks have been an important approach to reduce network size, which merge nodes who share the same or similar properties while preserving some significant functions or properties of the original networks. However, reducing network size is often at the cost of worsening network performance. Thus, there is a trade-off between the coarse-grained network sizes and network performance. To find the balance between the two sides and based on the spectral coarse-graining approach (SCG), we propose two optimization algorithms, which are called variable step size optimization algorithm (VSSOA) and variable scale optimization algorithm (VSOA). The two algorithms can calculate the optimal coarse-grained step size and the optimal scale to reduce the share size of the network. The two algorithms are applied to the coarse-graining of several typical networks. And the feasibility and validity of the proposed algorithms are further verified by phase synchronization of coupled Kuramoto oscillators on typical networks. The related investigation provides a deep insight to the coarse-graining of large-scale complex networks.

Magnonics offers a new way for information transport that uses spin waves (SWs) and is free of charge currents. Unlike Damon-Eshbach SWs, the magneto-static forward volume SWs offer the reciprocity configuration suitable for SW logic devices with low power consumption. Here, we study forward volume SW propagation in yttrium iron garnet (YIG) thin films with an ultra-low damping constant α = 8 × 10 - 5 . We design different integrated microwave antenna with different k-vector excitation distributions on YIG thin films. Using a vector network analyzer, we measured SW transmission with the films magnetized in perpendicular orientation. Based on the experimental results, we extract the group velocity as well as the dispersion relation of SWs and directly compare the power efficiency of SW propagation in YIG using coplanar waveguide and micro stripline for SW excitation and detection.

We investigate hole mobility in InSb-based ultrathin body (UTB) devices based on physical modeling. For arbitrary surface orientation, the dependence of hole mobility on body thickness and biaxial strain is evaluated. The anisotropic band structures under quantum confinement are computed by solving the six-band k ⋅ p Schrodinger and Poisson equations in a self-consistent way. Hole mobility is calculated by the Kubo–Greenwood formula. Physical models include acoustic and optical phonons, polar optical phonons, and surface roughness scattering mechanisms. Our results show that in InSb-based devices with various surface orientations, hole mobility begins to deteriorate as body thickness is reduced below a certain range. It is important that mobility improvement from non-(0 0 1) surface orientation is observed, especially for extremely thin body. With regard to biaxial strain, compressive strain is effective to enhance hole mobility for different orientations. Additionally, in both unstrained and strained cases, the optimal surface/channel direction for hole mobility is obtained along the (1 1 0)/[ 1 ¯ 1 0] direction, followed by (1 1 1)/any, (1 1 0)/[0 0 1], and (0 0 1)/any directions.