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To improve graphene-based multifunctional devices at nanoscale, a stepwise and controllable fabrication procedure must be elucidated. Here, a series of structural transition of bismuth (Bi) adatoms, adsorbed on monolayer epitaxial graphene (MEG), is explored at room temperature. Bi adatoms undergo a structural transition from one-dimensional (1D) linear structures to two-dimensional (2D) triangular islands and such 2D growth mode is affected by the corrugated substrate. Upon Bi deposition, a little charge transfer occurs and a characteristic peak can be observed in the tunneling spectrum, reflecting the distinctive electronic structure of the Bi adatoms. When annealed to ~500 K, 2D triangular Bi islands aggregate into Bi nanoclusters (NCs) of uniform size. A well-controlled fabrication method is thus demonstrated. The approaches adopted herein provide perspectives for fabricating and characterizing periodic networks on MEG and related systems, which are useful in realizing graphene-based electronic, energy, sensor and spintronic devices.

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Resource allocation and call admission control (CAC) are two key issues in satellite networks for multimedia applications with quality of service (QoS) guarantees. This paper introduces a new priority-based CAC scheme for multiclass services in satellite networks operating above 10 GHz, where the dominant factor limiting performance is rain attenuation, a phenomenon exhibiting both spatial and temporal variation. The proposed scheme exploits the predictability of the satellite channel and accepts a new call if sufficient resources exist for existing and new users to guarantee their QoS requirements. At the same time, it assigns higher priority to real-time users compared to non-real time ones. The performance of the proposed scheme is investigated using Markov chain to represent the satellite channel states. Analytical expressions concerning the call blocking probability under clear sky and rain conditions are derived.