| The on-line water quality monitoring system is an integrated on-line automatic monitoring network composed of sensor technology,computer application technology and communication network technology.The existing river water quality monitoring system mainly establishes the water quality monitoring station near the river course.Not only the construction cost is high,but also has a certain impact on the local natural environment.The design and implementation of a small river water quality monitoring system and management software based on Internet of things technology could solve this problem effectively.The system has the advantages of high accuracy,low cost and easy maintenance,and can continuously monitor the water quality of rivers.The designed water quality monitoring platform mainly includes two parts: the river water quality collection system and the river water quality management system.The main results are as follows:(1)Designed and completed a set of river water quality monitoring terminals with low cost,perfect functions and high compatibility.Using raspberry PI as the control module of monitoring terminal,it could be compatible with most data transmission protocols and network transmission protocols effectively,and has wide applicability to sensors.(2)Taking Windows platform as an example,the river water quality management system is designed.This study proposes a software design scheme of river water quality management system based on cloud service mode,which solves the problems of data uploading difficulty,poor data flow and maintenance difficulty caused by internal servers of traditional management departments.The adoption of cloud computing technology improves the data processing efficiency and reduces the configuration requirements of terminal hardware.The real-time display function of water quality and equipment status,water quality warning function,water quality analysis function are realized.(3)Completed the calibration of the sensor data of the monitoring terminal.According to the principle and characteristics of different sensors,the current and calculation parameters are adjusted by means of calibration such as two-point method and standard liquid method.Calibrated sensor with measured R2>0.999.After calibration,the measurement accuracy of standard liquid by ammonia nitrogen and conductivity sensor is high,so theoretical formula is used for calculation.The calibration parameters of other sensors are as follows: current-temperature calibration parameters are Y =0.0062x-25.0000;Current-p H conversion parameter: y=0.0009x-3.4958;Current-level conversion parameters are y=0.3124x-1249.7000;The conversion parameters of current to ammonia nitrogen are:Y=0.000625x-2.5062;Current-turbidity conversion parameters are: Y =0.0625-250.0469.(4)Accurate and stable transmission of monitoring data under laboratory conditions was completed.The error rate per 10,000 pieces of data is about 0.13%,and the monitoring data loss rate is 0%.Using 3 times standard deviation to judge the error value and using multi-segment linear interpolation to repair the error value and missing value have very high accuracy and short calculation time.(5)Designed a local river water quality management system with graphical interface based on cloud service mode.It meets the design requirements,and realizes real-time water quality data display,water quality data management,water quality data warning,monitoring terminal management,water quality data analysis and other functions.A set of river water quality monitoring terminal with low cost,complete function and high reliability and a supporting river water quality management system have been completed. |
