Research On Application Of Wireless Sensor Networks In Coalfield Spontaneous Combustion Monitor

Jurassic coal spontaneous combustion located in arid areas in northern China is a very serious problem, which wastes a lot of limited coal resources and results in a great deal of pollution. Therefore, in order to reduce the incidence of spontaneous events and the losses caused by them, it is necessary to monitor the coalfield areas where are easy to self-ignition, and then grasp the environmental data from there in time. Currently monitoring is primarily accomplished by hand, aviation and satellite remote sensing. But for the vast coalfield areas, manual monitoring has low efficiency and poor real-time characteristics. Aviation and satellite remote sensing are vulnerably limited to weather, terrain and cost factors, affecting the monitoring accuracy and monitoring cycle. Under the background of cooperation project of "Environmental protection in the coal energy field", this paper applies wireless sensor networks technology to monitor the spontaneous coalfield to overcome the deficiency of traditional monitoring methods.According to remote monitoring application characters of the spontaneous coalfield, we propose a wireless sensor network monitoring system adapted to this occasion. Under the GAINZ node development platform, we design energy-efficient MAC protocol based on time schedule (ET-MAC) and multi-path tree routing protocol based on group structure (MTR), and use GPRS technology to realize remote data transmission. ET-MAC uses activate / sleep mechanism to reduce the energy loss caused by listening. Also, ET-MAC uses the strategy of grouping the nodes in the network and re-election mechanism in cluster heads to balance energy consumption and prolong network life cycle. Taking fully into account the network service less, requiring reliable real-time data transmission in emergency situations and energy-limited nodes in the spontaneous coalfield environment, MTR uses multi-path transmission, which is that energy is routing center under normal circumstances, while in case of emergency it is important to consider the timeliness and reliability of the information arrival to the monitor. Finally, we deliver the designed MAC layer, network layer protocol and the related upper application into GAINZ nodes, to measure network-building, data transmission and GPRS connectivity.The test results indicate that this system can collect and transmit the environmental data of the spontaneous coalfield, and meet the requirements of real-time effective monitoring and initial specifications of the project. So this system provides an effective method for monitoring the spontaneous coalfield, thereby reducing human resources required to monitor the spontaneous coalfield, the economic costs and losses caused by coal spontaneous combustion.