Design Of Wiresess Sensor Nodes Applied To Safety Monitoring Of Qinghai-Tibet Railway Permafrost Subgrade

It has been over 100 years since people began to construct railroads upon permafrost regions all over the world. Because of the sensitivity of the frozen soil to temperature, diseases, such as frost-heaving and thawing-settlement, are always affecting the daily operation of the railways in permafrost areas. Thus it has great importance to carry out long-term, systematic and overall safety monitoring of the subgrade to find and resolve the hidden troubles timely. There exist many monitoring methods and systems, traditional or modern, based on different theories. However, in most cases, satisfactory results are not easy to get, because of the inherent deficiencies of the existing monitoring systems.Because of their characteristics of self organization, fault tolerance, rapid deployment, automatic mobile localization, etc. wireless sensor networks (WSNs), as a result of the technical combination of sensors, MENS, wireless communication and distributed signal processing, centralizing in data acquisition and data management, have found their way into a wide variety of applications and systems, such as military defense, industrial and agricultural control, urban management, environmental monitoring, etc., with vastly varying requirements and characteristics recently.To provide a new method for the subgrade safety monitoring of railroads in permafrost areas, WSNs, in this dissertation, are applied to monitor the safety of the Qinghai-Tibet Railway sbugrade. After an overall study of the actual demand of the Qinghai-Tibet Railway sbugrade safety monitoring, temperature was determined as the major monitoring parameter. A series of wireless sensor nodes is developed, named as Snows Elf, consisting of three sub-kinds named as Snows Elf_S, Snows Elf_C and Snows Elf_T. It is described, in detail, the software and hardware design of the controller&communication, sensors, power supply, and human-computer interaction subsystems of Snows Elf nodes. Besides, the circuit schematic and PCB diagrams, with the program flow charts of these subsystems are provided in this dissertation.Then several experiments are designed and carried out to test the environmental adaptability and the actual temperature monitoring capability of the Snows Elf wireless sensor nodes. The experimental results show that the Snows Elf wireless sensor nodes have great environmental adaptability and the actual temperature monitoring capability. Therefore they can play an important role in the Qinghai-Tibet Railway sbugrade safety monitoring.This dissertation is supported by by NSFC of Anhui, China (No. 070412037).