This paper proposes a scheme for updating the location of the sink node to balance the network topology when a wireless sensor network (WSN) is scaled up. We divide the proposed location update scheme into two steps, namely, searching the optimal location and designing the pathfinding algorithm. For the former, to find the optimal location of the sink node simply and efficiently, we only consider the information of the expanded longer paths and some key nodes instead of the global information of the entire network, which is easy to implement with a low-computational load. Then, considering the general unattended application scenario, we propose an improved reinforcement learning (RL) algorithm for the sink node to calculate a feasible efficient path, and then the sink node follows the path to reach the optimal location. Finally, through simulations, we demonstrate the optimal position of the sink node in expanded scenarios and successfully let the sink node learn the effective pathfinding method to reach the target position. A large number of simulation results verify the efficiency and effectiveness of our proposed scheme from the perspective of the efficiency of the pathfinding algorithm.
In this paper, medium access control (MAC) sublayer data traffic scheduling in distributed networked control systems (DNCSs) with networked induced packet losses and delays is investigated for stabilization and control of system dynamics. An effectiveinformation-directed distributed sensor selection algorithm is proposed to select sensors to participate in delay-tolerant information filtering for state estimation. The distributed scheduling algorithm is based on the total amount of effective information for all measurements stored in the sensors. We consider packet loss in wireless networks as a special type of delay, so the impact of packet losses on effective information amount can also be studied for the formulation of distributed scheduling strategy in the presence of packet losses. The distributed data traffic scheduling considering packet losses and delays is carried out in a networked system with data packet dropout governed by a Markov process for voltage regulation and stabilization with distributed energy resources (DERs). Experimental results demonstrate that the scheduling algorithm with awareness of the system dynamic state can well control the power system dynamics.
The lithium-ion battery separator plays roles of separating the positive and negative electrodes and providing ion channels, and at the same time, it can play a more important role in the safety of the lithium-ion battery. In this work, a modified PP (polypropylene)/PAN (polyacrylonitrile)/cotton fibers composite membrane with a thermal shut-off function was prepared by a wet-laid process. The results are as follows: When the fibers’ mass fraction was 50%, the composite membrane had the best combination properties, with a tensile strength of 1.644 KN·m−1, the porosity was 63%, and it had good wettability with an aspiration height of 39 mm and a liquid absorption rate of 269%. The thermal shrinkage of the composite membrane was less than 4% after thermal treatment under 160 °C. More importantly, the DSC curve showed that the modified PP/PAN/cotton fibers composite membrane had a thermal shut-off function with the temperature between 110 °C and 160 °C. After thermal treatment under 160 °C for 1 h, the ionic conductivity of the fiber membrane decreased to 0.32 mS·cm−1 from 1.99 mS·cm−1. Electrochemical performance tests showed that the button battery using the fiber composite membrane had a slightly better initial discharge, capacity retention and cycle performance at different rates than the button battery equipped with the PP membrane. The results show that the modified PP/PAN/cotton fibers composite membrane improves the safety and electrochemical performance of lithium-ion battery.
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