| Due to the influence of climate,the rivers in northern China often freeze and seal in winter,which will cause ice disaster and threaten the safety of people’s life and property in the process of freezing and melting.The Yellow River is one of the rivers with frequent ice disasters in China.Therefore,the flood control department will detect the ice situation of the Yellow River every year through the method of artificial field measurement.However,its efficiency is low and the data obtained is lack of continuity.With the development of modern sensing technology,the ice thickness can be measured by sonar,radar,ultrasonic and other new methods.However,the detection accuracy needs to be improved and it is difficult to obtain the changes in the ice layer.Therefore,it is necessary to develop a new automatic observation equipment to provide accurate original ice data for the ice protection of rivers.In view of the low efficiency and lack of continuity in the observation of the Yellow River ice situation,this paper carries out a research on the design of the ice sheet thermodynamic equilibrium buoy system based on the difference of medium temperature characteristics.In order to improve the detection accuracy of ice temperature in low temperature environment,a high precision temperature measuring sensor is designed.According to the difference of temperature appreciation caused by heating,the ice sheet temperature can be changed actively by the periodic self-heating unit,and the surface of the ice sheet can be identified accurately by the ultrasonic detection sensor.In order to evaluate the performance of the system,a field deployment was carried out at Toudaoguai Hydrological Station of the Yellow River from January 9,2020 to March 1,2020,and obtained the ice sheet evolution data of the entire monitoring cycle,which provided a new solution for the study of river ice situation and scientific guidance of disaster prevention work.The research of this subject mainly includes the following four aspects:(1)The design of a high precision temperature sensor for a wide temperature range(-50℃～+20℃)has been carried out.By studying the temperature resistance relation,measuring accuracy and long-term stability of different thermal resistors,the temperature sensing unit was selected and calibrated.At the same time,considering the influence of multi-channel analog switches on the temperature measurement results of the system,the relationship between the on-off resistance and temperature is analyzed,and the design scheme of high-precision temperature sensor is determined.(2)Aiming at the problem that the ice sheet interface cannot be accurately identified during the melting period,a periodic self-heating unit was designed to heat the ice sheet,and the accurate judgment of the interface is realized according to the difference in temperature rise caused by heating.The characteristics of heating power,time and temperature rise of medium were studied,and the software and hardware design of each module of the ice sheet thermodynamic equilibrium buoy system was completed.(3)In order to evaluate the performance of the system,field observation experiments were conducted at Toudaoguai Hydrological Station of the Yellow River in January 2020,the ice evolution data of the whole monitoring period were obtained during the experiment.By analyzing the vertical profile temperature of ice sheet and the difference of temperature appreciation caused by heating,combined with the auxiliary measurement results of the ultrasonic sensor,the accurate identification of all fields is realized.(4)Based on the field observation data,the thermodynamic parameters of the ice sheet were calculated,the thermodynamic changes in the ice layer during its growth and pre ablation were obtained.Considering the difference between the temperature of the ice surface and the temperature of the ice surface and the influence of the water and heat flux on the ice surface,the classical prediction model of the ice thickness is optimized,which provides an important theoretical basis for preventing the ice disaster. |
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