水产养殖氨氮在线检测方法及系统研究

发布时间：2018-11-08 17:14

【摘要】：精细化养殖具有养殖密度高和经济效益好等特点,已逐渐取代粗放养殖成为主流养殖模式。由于养殖密度较高,常导致水中营养元素氮转变为有毒的氨氮。当氨氮浓度超过2.00mg/L时,水生物便会出现中毒症状,甚至大量死亡。因此,必须周期性检测养殖水体中氨氮浓度。而我国水产养殖氨氮检测技术相对落后,缺乏专用于水产养殖业的低浓度高精度氨氮在线检测设备。养殖水体中氨氮浓度较低,要求检测精度较高,但是高精度实验室氨氮检测设备因价格较高和操作复杂难以推广。因此,多数养殖厂仍使用便携式氨氮测定仪或氨氮试纸人工检测氨氮浓度。人工检测常由于检测员操作不当导致较大的人为误差,便携式氨氮测定仪或氨氮试纸存在检测低浓度水体时检测误差大、检出限高和试剂浪费等问题。针对上述问题,论文提出了一种水产养殖氨氮在线检测方法,实现低浓度氨氮在线高精度检测,主要研究内容如下:(1)从纳氏试剂配制方法、试剂与氨氮化学反应和吸光度检测三方面分析水产养殖氨氮检测精度影响因素,并根据分析结果提出优化措施,降低检出限和检测误差,提高了低浓度氨氮检测分辨率。(2)因为检测环境常年变化较大,所以为了避免对在线检测精度的影响,提出了基于LSSVM软测量数据处理算法,选取养殖水体温度、吸光度峰值和峰值时间作为输入量,氨氮浓度作为输出量,实现在线检测精度补偿,无需增加额外功能组件,减少成本,提高了检测精度。(3)实现水产养殖氨氮在线检测系统,完成现场检测装置和监控终端的软硬件设计。硬件电路主要有微处理器最小系统、光电检测、温度检测和GPRS通信等电路,软件有以微处理器为核心的控制、AD采样、显示以及无线通信等程序,并采取自定义数据包、差错控制和断点续传技术提高通信可靠性。(4)在搭建的水产养殖氨氮在线检测系统平台上,进行检测系统的精度、稳定性和重复性实验,并选用便携式氨氮检测仪进行对比实验。实验结果表明:基于LSSVM软测量方法提高了低浓度氨氮检测准确性,实现了检测精度补偿;本课题提出的水产养殖氨氮在线检测系统具有较高的检测精度、稳定性和重复性,避免了影响因素干扰,检测实验结果标准偏差和相对标准偏差平均值分别为0.0107mg/L和1.28%;基于影响分析结果优化后的在线检测系统降低了检测误差和检出限,提高了检测精度,节省试剂,减少单次检测成本。
[Abstract]:Fine culture has the characteristics of high density and good economic benefit, and has gradually replaced extensive culture as the mainstream culture mode. Because of the high density of aquaculture, the nutrient nitrogen in water is often changed into toxic ammonia nitrogen. When ammonia concentration exceeds 2.00mg/L, aquatic organisms will appear toxic symptoms, and even a large number of deaths. Therefore, the concentration of ammonia nitrogen in aquaculture water must be detected periodically. However, the detection technology of ammonia nitrogen in aquaculture in China is relatively backward, and lack of low concentration and high precision ammonia nitrogen on-line detection equipment for aquaculture industry. The concentration of ammonia nitrogen in aquiculture water is low and the precision of detection is high. However, it is difficult to popularize the equipment of ammonia nitrogen detection in high precision laboratory because of its high price and complicated operation. Therefore, most aquaculture plants still use portable ammonia nitrogen tester or ammonia nitrogen test paper to manually detect ammonia concentration. Human error is often caused by the improper operation of the tester. The portable ammonia nitrogen tester or the ammonia nitrogen test paper has many problems such as high detection error, high detection limit and waste of reagent. In order to solve the above problems, an on-line detection method of ammonia-nitrogen in aquaculture is proposed to realize the on-line and high-precision detection of low concentration ammonia nitrogen. The main research contents are as follows: (1) the preparation method of Nessler's reagent. The factors affecting the detection accuracy of ammonia-nitrogen in aquaculture were analyzed in three aspects: reagents and ammonia nitrogen chemical reaction and absorbance detection. Based on the analysis results, the optimization measures were put forward to reduce the detection limit and detection error. The detection resolution of low concentration ammonia nitrogen is improved. (2) in order to avoid the influence on the accuracy of on-line detection, a soft sensor data processing algorithm based on LSSVM is proposed to select the temperature of aquaculture water. The peak absorbance and peak time are used as input amount and ammonia nitrogen concentration as output quantity to realize on-line measurement accuracy compensation without adding additional functional components and reducing cost. The detection accuracy is improved. (3) the on-line detection system of ammonia nitrogen in aquaculture is realized, and the hardware and software design of field detection device and monitoring terminal are completed. Hardware circuits mainly include microprocessor minimum system, photoelectric detection, temperature detection and GPRS communication circuits. The software has microprocessor as the core control, AD sampling, display and wireless communication programs, and adopt custom data packets. Error control and breakpoint transmission technology improve the reliability of communication. (4) the precision, stability and repeatability of the system are tested on the platform of the online detection system of aquaculture ammonia nitrogen. A portable ammonia-nitrogen detector was used to carry out a comparative experiment. The experimental results show that the accuracy of low concentration ammonia nitrogen detection is improved and the accuracy compensation is realized based on LSSVM soft sensing method. The online detection system of ammonia nitrogen in aquaculture presented in this paper has high detection precision, stability and repeatability, and avoids the interference of influencing factors. The average values of standard deviation and relative standard deviation were 0.0107mg/L and 1.28 respectively. The optimized on-line detection system based on the results of impact analysis reduces the detection error and detection limit, improves the detection accuracy, saves reagent and reduces the cost of single detection.
【学位授予单位】：江苏大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：S959;TP274

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