In this work, PA6/PA66/GNP thermal composites were prepared via a melt blending method. Mechanical properties, morphology and thermal properties of PA6/PA66/GNP composites were investigated. The thermal conductivity of composite containing 50 wt-% of graphene nanoplatelets was measured as 5·03 W m -1 K -1 at 30°C. When the Al 2 O 3 was replaced for graphene nanoplatelets, the thermal conductivity of composites decreased, but the mechanical properties improved. The optimum amount of Al 2 O 3 which replaced graphene nanoplatelets is 10%. When graphite was used to replace for graphene nanoplatelets, thermal conductivity basically remained unchanged but mechanical properties decreased.
To address the problems of the slow convergence and inefficiency in the existing adaptive PID controllers, we propose a new adaptive PID controller using the asynchronous advantage actor-critic (A3C) algorithm. Firstly, the controller can train the multiple agents of the actor-critic structures in parallel exploiting the multi-thread asynchronous learning characteristics of the A3C structure. Secondly, in order to achieve the best control effect, each agent uses a multilayer neural network to approach the strategy function and value function to search the best parameter-tuning strategy in continuous action space. The simulation results indicate that our proposed controller can achieve the fast convergence and strong adaptability compared with conventional controllers.
In this paper, we proposed a graphene-silicon nitride (GSN) waveguide model, which was unveiled to unveil its second-order dispersion (SOD) characteristics. The influences of the different thicknesses of graphene layer and the different heights from graphene to the core material of silicon nitride on SOD were investigated in detail. The tunability of SOD via controlling the bias voltage applied to the graphene layer was demonstrated and a 50 nm wavelength tuning was achieved with a small perturbation in voltage while keeping the geometric structure of the waveguide unchanged. Moreover, a flat SOD curve of the GSN waveguide was obtained with a large bandwidth of 700 nm between the two zero-dispersion wavelengths (ZDWs). These results provided significant insights for potential applications of graphene-related optoelectronic devices, integrated optics, and optical communications.
This article mainly presents a summary of development of dynamic comparators and the optimization to conventional comparator in recent years. By comparing the design of two different comparators, the design method of less power consumption, high speed or small delay, and low input referred noise can be concluded. The Dynamic comparator is designed to have small delay and less power consumption compared with two-stage comparator. The dynamic-bias comparator spends less power for operation the circuit compared with double-tail comparator. The FIA comparator operates under the controlling of logic NOR gate.
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