| The frequent occurrence of river ice flood disasters in alpine regions in China posed a serious threat to the lives and property of local residents.In view of the prevention of natural disasters such as ice flood,various sensors are used to monitor the ice and water regime of rivers at home and abroad,but the detection methods need to be improved and the detection accuracy needs to be improved.The temperature of river ice sheet profile is an important physical parameter for analyzing the thermodynamic parameters of ice sheet and establishing ice thickness prediction model.The temperature chain of ice regime detection based on the difference of temperature characteristics of different media in river ice sheet profile has been widely used in the field of ice regime detection and achieved good results.At present,the measurement accuracy of ice detection temperature chain used at home and abroad in low temperature environment is limited,and there are still large errors in the wide temperature range,which gradually can't meet the needs of actual data analysis.Therefore,it is of great significance to develop a high precision temperature detection equipment for ice sheet profiles in wide temperature range for ice flood disaster prevention and hydrological research.By studying the resistance-temperature relationship of thermistors and the structure of sensors,a new type of high-precision temperature sensor for ice-cover profiles with high accuracy and reliability is designed,and a detection system is developed.This research mainly carries out the following four aspects:(1)The thermistor was selected as the sensor temperature detecting unit by consulting the data,and the detection and calibration methods of the thermistor were studied.LTC2983 is selected as the core device of the detection circuit.By studying the resistance-temperature characteristics of the thermistor,the temperature residual compensation method and the resistance residual compensation method based on the thermistor calibration empirical formula are proposed,and a good calibration effect is obtained.The accuracy of single-point sensor temperature detection in a wide temperature range(-50?~+30?)in a low temperature environment is 0.1?.(2)Based on the difference in temperature characteristics of air,snow,ice and water in the vertical direction of the river ice sheet profile,a high-precision temperature detecting sensor for the ice sheet profile was designed.Through the analysis of the internal resistance of ADG732,the feasibility of multi-point temperature detection of the sensor is determined.The sensor adopts a chain structure,and the main body adopts a PCB and is encapsulated in an epoxy resin,thereby effectively improving the reliability of the sensor.(3)Designed a relatively complete detection system,including hardware and software design.The hardware is mainly the design of the data acquisition instrument,including the design of the main control CPU module,the data storage module and the data transmission module;the software is mainly the design of the temperature acquisition program,the data storage program and the data transmission program.By adopting MSP430 low-power single-chip microcomputer as the CPU and adopting dual-channel power supply,the overall power consumption of the system is effectively reduced.(4)The high-precision temperature detection system for the ice sheet profile was installed in the Mohe section of Heilongjiang River in mid-December 2017 and completed more than three months of on-site collection experiments.During the monitoring period,a relatively complete temperature data of river ice sheet profiles at the center of the river was obtained.By analyzing the temperature curves of the river ice sheet profile in several typical periods,the thermodynamic changes inside the ice sheet are known.Based on the analysis of the existing large amount of ice water data,the ice thickness variation of the river during the monitoring period was obtained by using the ice sheet profile temperature data,and the heat flux in the ice was calculated and analyzed.Stephen Law is optimized by means of a's piecewise fitting based on the temperature data of ice cover profile,which improves the accuracy of estimation of ice thickness of Stephen Law and provides important parameters for the prevention of ice flood disasters in cold regions. |
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