With the gradual expansion of the application field in wireless sensor networks, the problems of the energy consumption has received more and more attention. In wireless sensor networks, the location of sensor nodes and gateway nodes are usually fixed. To ensure that the energy consumption of the sensor network is minimized during data transmission, it is necessary to optimize the placement of relay nodes. This paper proposes the solution of relay nodes placement based on optimal transmission distance, which can minimize the energy consumption and extend the lifetime of the entire network during the transmission process. This scheme starts with a one-dimensional queue network and calculates the optimal distance for each hop transmission to minimize the energy consumption of the one-dimensional queue network. Due to the poor connectivity of the one-dimensional queue network, the concept of the optimal transmission distance is introduced into two-dimensional network, so that the placement scheme can be divided into the symmetrical relay node placement and the asymmetric relay node placement. Finally, the energy consumption of the network is minimized by properly selecting relay nodes. The simulation show that the proposed relay node placement scheme can reduce the energy consumption of the sensor network and extend the network life cycle.
In order to equalize network energy consumption, and extend the life cycle, the optimized protocol based on low-power adaptive cluster stratification (LEACH) is proposed. Firstly, considering residual energy and distance of nodes, the threshold function of the cluster head is modified, and the network region division strategy is optimized, to reasonably adjust the size of clusters. For intracluster transmission, a sleep mechanism is added to balance node energy consumption. And a new barycenter node is added to assist cluster head (CH) to complete the transmission task, thereby extending the service lifetime. In the multihop communication between clusters, in order to calculate the fitting factor of the next hop, we derived a new formula, which takes into account the angle, remaining energy, and distance. Simulation results show that the total remaining energy of the optimized LEACH protocol is reduced by 31.4%, and the network life cycle is increased by about 52%.
With the development of tunnel technology, the number of tunnels becomes huge in some area, and adjoining tunnels turn into tunnel group in some highway sections. So, to ensure the traffic safety, the linkage ventilation control system for the tunnels of the whole highway section is necessary and essential. In this research, obtaining the live traffic information of each tunnel is the key point. This article attempts to build up an intelligent ventilation system which makes traffic flow data of every tunnel available and predictable. The system achieves information sharing and build up weight-based traffic forecasting model. In addition, the composition of fuzzy-logic ventilation control model is introduced. The research might expand the application of intelligent tunnel ventilation control system and could provide references to other linkage ventilation control system of tunnel groups.
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