本文選題：肥液　切入點：氮素濃度　出處：《昆明理工大學(xué)》2015年碩士論文

【摘要】：在自動灌溉施肥中,灌水和施肥可以得到精確地監(jiān)控,而獲得肥液濃度是實施肥液濃度監(jiān)控的關(guān)鍵,因此實現(xiàn)肥液濃度的在線檢測對于實現(xiàn)肥液濃度的在線調(diào)控有重要意義。現(xiàn)有的自動灌溉系統(tǒng)中肥液濃度主要是通過肥液EC值來衡量,肥液EC值反映的是中鹽的總含量,沒有反映出肥液中各組分的含量。為實現(xiàn)肥液自動混合過程中氮素濃度的實時檢測,本文采用離子選擇電極檢測法設(shè)計了一個檢測裝置,分析了電極的溫度變異性,在此基礎(chǔ)上建立溫度參數(shù)模型；并針對混合肥液中常出現(xiàn)的,對氮素濃度測量造成干擾的共存離子引起的測量誤差進(jìn)行了分析。本文的主要研究工作如下：采用硝酸根離子選擇電極檢測肥液氮素濃度方法,設(shè)計了肥液氮素濃度檢測裝置,檢測裝置由信號調(diào)理電路、溫度傳感器、數(shù)據(jù)采集以及顯示電路組成,并對該檢測裝置進(jìn)行了性能測試試驗：(1)以標(biāo)準(zhǔn)毫伏計PHS-3CT作為對比,測試了裝置對電極響應(yīng)電勢的測量準(zhǔn)確性,檢測裝置測量最大相對誤差為5.2%,最小相對誤差為1.2%,表明檢測裝置能夠準(zhǔn)確測量電極輸出電勢。(2)在5-45℃范圍內(nèi),分析了離子選擇電極的溫度變異性,以25℃為基準(zhǔn),電勢值的最大溫度變異率為8.8%；采用最小二乘法的逐步擬合方法建立了溫度-濃度-電極響應(yīng)電勢三者之間的參數(shù)模型,并通過試驗得到參數(shù)模型測量誤差最大為9.2%,驗證了該模型的有效性。(3)采用固定干擾法分析了C1-、SO42-、H2PO4-和HPO42-等4種干擾離子對裝置測量結(jié)果的影響,并分別分析了C1-濃度以及H2PO4濃度與N03-濃度比值不同時,溶液中Cl-、H2PO4-引起的測量誤差的大小。本文通過試驗驗證了肥液氮素濃度檢測裝置的性能,結(jié)果表明所設(shè)計的檢測裝置測量的可靠性,為自動混肥時氮素濃度的測量提供了一種可靠的方法。
[Abstract]:In automatic irrigation and fertilization, irrigation and fertilization can be monitored accurately, and the key to implement the monitoring of fertilizer concentration is to obtain the concentration of fertilizer solution. Therefore, it is important to realize the on-line measurement of the concentration of fertilizer solution, which is mainly measured by EC value of fertilizer solution in the existing automatic irrigation system, and the EC value of fertilizer liquid reflects the total content of medium salt. In order to realize the real-time detection of nitrogen concentration in the process of automatic mixing of fertilizer solution, a detection device was designed by ion selective electrode method, and the temperature variability of the electrode was analyzed. On the basis of this, the temperature parameter model is established, and in view of the common occurrence in the liquid of compound fertilizer, The measurement error caused by the interference ion of nitrogen concentration measurement is analyzed. The main research work in this paper is as follows: the method of nitrate ion selective electrode is used to detect the concentration of liquid nitrogen in fertilizer, and the measuring device of fertilizer liquid nitrogen concentration is designed. The detection device is composed of signal conditioning circuit, temperature sensor, data acquisition and display circuit, and the performance test test of the device is carried out. (1) the standard millivolt meter PHS-3CT is used as a contrast. The measuring accuracy of the device to the electrode response potential is tested. The maximum relative error and the minimum relative error of the measuring device are 5.2and 1.2respectively. The results show that the measuring device can accurately measure the electrode output potential in the range of 5-45 鈩，

本文編號：1657174