附录A 外文文献A Coal Mine Environmental Monitor System with Localization I.RESEARCH STATUSAs an important energy, coal plays a pivotal role in the economic development. Coal mine monitoring system, is the important guarantee for coal mine safety and high efficiency production. In order to ensure the safe operation, the installation of environment monitoring node in tunnels to real-time detection is very important. However, commonly used traditional monitoring node wired connection to obtain communication with the control system, this node exist wiring difficulties, expensive and other shortcomings. In contrast, wireless sensor node can be easily with current mine monitoring network connection, and good compatibility, facilitate constituted mine gas monitoring network, to suit various size of mine applications. Since wireless nodes are battery powered, so completely out of the shackles of the cable, shorten the construction period can be arranged at any time where the need to use.The Zigbee wireless communication technology is used in this coal mine environmental monitor system. This is a new short-range, low complexity, low power, low data rate, low-cost two-way wireless communication technology. Now, wireless sensor network product based on Zigbee technology are quantity and variety, but the real product can be applied in underground environments of special sensor node is very few. The sensor node that we designed in the system is truly able to apply to in-well environment, it through the wireless sensor node security certification. At the same time, due to the special nature of the wireless network is that it can spread the wireless signal, we can easily locate staff for coal mine safety monitoring provides more protection.II. SYSTEM ARCHITECTUREThis system is a comprehensive monitoring system which is combined with software and hardware. Hardware part includes wireless mobile nodes and fixed nodes which were deployed in the underground tunnel, the main function of them is to collect coal mine environment data and require persons location. Software part refers to the PC monitoring software which is designed in VC+ is used to summarize and display the data of each node. Monitoring node is divided into mobile nodes and fixed nodes; they are using Zigbee protocol for wireless transmission of data. Because the fixed node is also using wireless data transmission method, so its deployed in the underground roadway becomes very convenient. As the mobile node is carried by the miner, it must be using wireless transmission method. This allows the mine to form a topology of Zigbee wireless sensor network. The fixed node in wireless sensor network is router device and the mobile node carried by miner is the end device. Normally, the router of Zigbee network has no sensor equipment; it is only responsible for data forwarding. But considering the practical application, we believe that add sensor devices on the router will be better on monitoring underground coal mine environment. So in our design, the router also has an environment monitoring function which is usually designed in end device.Fixed node will sent received data from mobile node to the gateway, then the gateway transmits data to monitor computer through RS232 or optical fiber. The PC monitor software in the computer will process all data and display them in a visualization window. The PC software also calculates each mobile nodes real-time location through the specific localization algorithm, according to the received signal strength (RSSI) obtained from mobile nodes.III. NODE DESIGNSince the Zigbee wireless network platform sold on present market was designed for the general environment, for special underground so they are not suitable for the environment. Therefore, we need to customize the system for underground environment whit a special hardware circuit. Node photo are shown in Fig. 1Then wireless microcontroller CC2530 chip is the core processor of the node device, it can constitute a Zigbee network with very few peripheral circuits. The CC2530 is an IEEE 802.15.4 compliant true System-on-Chip, supporting the proprietary 802.15.4 market as well as the Zigbee, Zigbee PRO, and Zigbee RF4CE standards. Unlike other wireless chip, CC2530 built-in 8051 monolithic integrated circuits kernel, therefore we no longer need to use a single MCU to control the circuit, and this save us a lot of cost.A. Mobile NodeThe mobile node is the end device of a Zigbee network that can be carried by miner; it should be a portable and low power consumption node. So the mobile node we designed is only as small as a mobile phone, and it is by built-in lithium ion battery power supply. In power loss, the core processor CC2530 is a low power consumption chip, when it is in the sleep mode, it only need to use less then 1uA work current. In order to reduce power consumption as much as possible on the display, a 100*32 pixel matrix with no backlighting LCD scr