Summary
Thermal energy can be converted into mechanical energy through the melting process of a phase change material (PCM). A PCM mixed with an insoluble liquid has higher energy converting efficiency during the whole melting process, where the massive microvacuum formed during the freezing process is filled by the insoluble liquid, which increases utilization of the volume change. The traditional theoretical model of the phase change process is unable to sufficiently describe the mixed PCM; therefore, a new model aimed at analyzing the characteristics of the volumetric change rate, as well as the freezing and melting times of the mixed PCM, is theoretically constructed. In this paper, the effective heat capacity method is used, and the effects of porosity are considered when the PCM is in the solid state. Comparisons of this model with the traditional model are carried out using both simulations and experiments for different pressures and geometric structures. Our results indicate that the introduced model has better accuracy when describing the phase change process of the pure PCM mixed with an insoluble liquid.
The performance of routing strategies on complex networks can be characterized by two measurements, i.e., the traffic capacity and the average packets travel time. By efficiently synthesizing the degree and the dynamic queue length of nodes, we propose the global hybrid (GH) routing strategy. It can achieve higher traffic capacity, as well as shorter average packets, travel time compared with the state-of-the-art global dynamic (GD) routing strategy and efficient routing (ER) strategy. Moreover, such superiority can be maintained through the queue length information and the corresponding routing paths are updated periodically. The simulation results show that our GH routing strategy can provide the same traffic capacity as the GD routing strategy does, which is more than twice as high as the ER strategy. At the same time, the average packets travel time of the GH routing strategy is more than 20% smaller than that of the GD routing strategy. It is worth noted that longer updating delay makes our GH routing strategy have a greater decline in the average packets travel time. With the updating delay equals 100, the decline can be up to 40%. To illustrate the practicability of our GH routing strategy, we also applied it to a scale-free networkbased data center network. The simulation results reveal that it is practical, effective, and can be used in real scenarios to improve network performance. INDEX TERMS Scale-free networks, hybrid routing, traffic capacity, average packets travel time.
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