本文選題：射頻探頭 + 螺線管線圈�。� 參考：《東南大學(xué)》2017年碩士論文

【摘要】：食用油的品質(zhì)鑒別一直是社會(huì)的熱點(diǎn)問題,在眾多的檢測(cè)方法中,核磁共振技術(shù)因具有無損、快速和安全的優(yōu)勢(shì),已經(jīng)被證實(shí)為一種非常有價(jià)值的檢測(cè)方法。本文在回顧食用油品質(zhì)鑒別研究現(xiàn)狀和低場(chǎng)核磁共振技術(shù)的基礎(chǔ)上,通過研究具有穩(wěn)定調(diào)諧匹配特性的射頻探頭和具有高精密的溫度控制系統(tǒng),在實(shí)驗(yàn)室現(xiàn)有研究成果的基礎(chǔ)上,研制了一種面向食用油品質(zhì)鑒別的低場(chǎng)核磁共振檢測(cè)平臺(tái)�；谠撈脚_(tái)裝置,建立食用油品質(zhì)核磁共振的檢測(cè)模型,實(shí)現(xiàn)對(duì)食用油品質(zhì)的鑒別。論文研究取得的成果如下:(1)基于螺線管線圈的理論模型,以相對(duì)信噪比為優(yōu)化目標(biāo),設(shè)計(jì)和優(yōu)化了射頻螺線管線圈參數(shù)。結(jié)果表明,當(dāng)線圈直徑D和高度H取5.1mm時(shí),線徑為d為0.2mm,匝數(shù)n為12匝,線圈的相對(duì)信噪比達(dá)到最大,即為最優(yōu)的參數(shù)模型。通過改進(jìn)螺線管線圈的制作工藝,實(shí)現(xiàn)了射頻線圈參數(shù)的精確控制。最后,根據(jù)實(shí)驗(yàn)測(cè)試的信噪比,驗(yàn)證了理論模型的準(zhǔn)確性和合理性。(2)改進(jìn)探頭射頻電路的匹配網(wǎng)絡(luò),有效的增加了探頭調(diào)諧匹配范圍和降低探頭的回波損耗,完成了射頻電路的實(shí)際制作與測(cè)試,包括射頻電路的仿真、元器件的選擇及測(cè)試、耐壓值測(cè)試等。同時(shí),通過研究射頻探頭品質(zhì)因素選擇,在26.09MHz頻率下,集成所設(shè)計(jì)的射頻線圈和調(diào)諧匹配電路,完成射頻探頭的制作。(3)基于低場(chǎng)核磁共振檢測(cè)平臺(tái)的溫控需求,設(shè)計(jì)高精度溫度控制系統(tǒng)的技術(shù)方案,測(cè)定溫控系統(tǒng)PID(比例-積分-微分)參數(shù)。同時(shí),從傳感器位置、空氣流動(dòng)性、保溫性能、環(huán)境溫度等方面,優(yōu)化系統(tǒng)的溫控性能和溫度梯度場(chǎng),確定檢測(cè)系統(tǒng)的共振頻率,實(shí)現(xiàn)36.0℃±0.1℃的溫控目標(biāo),完成高精度溫控系統(tǒng)的設(shè)計(jì)制作。(4)搭建食用油品質(zhì)低場(chǎng)核磁共振檢測(cè)平臺(tái),選取常用的大豆油、花生油和調(diào)和油等食用油作為樣本,建立食用油橫向弛豫時(shí)間T2和縱向弛豫時(shí)T1與煎炸時(shí)間的線性關(guān)系,同時(shí)與商業(yè)核磁共振儀器Bruker Minispec mq60進(jìn)行對(duì)比,完成檢測(cè)平臺(tái)裝置的性能驗(yàn)證和測(cè)試。最后,基于該平臺(tái)裝置檢測(cè)了福臨門、金龍魚和魯花三種大豆油食用油樣本,引入極性化合物參數(shù)和標(biāo)準(zhǔn)檢測(cè)方法柱層析法,建立核磁共振弛豫曲線與極性化合物含量的交叉模型,能夠有效鑒別不同煎炸時(shí)間的極性化合物含量。結(jié)果表明,大豆油油脂在煎炸43小時(shí)后即不可再食用,檢測(cè)誤差在15%以內(nèi)。因此,本文研究的低場(chǎng)核磁共振檢測(cè)平臺(tái)裝置可成為食用油檢測(cè)領(lǐng)域中的重要潛在工具。
[Abstract]:The identification of edible oil quality has always been a hot issue in society. Among the many detection methods, nuclear magnetic resonance (NMR) technology has been proved to be a very valuable detection method because of its advantages of nondestructive, rapid and safe. On the basis of reviewing the present research situation of edible oil quality identification and low field nuclear magnetic resonance (LNMR) technology, the RF probe with stable tuning and matching characteristics and the high precision temperature control system are studied in this paper. A low field nuclear magnetic resonance (NMR) detection platform for edible oil quality identification was developed on the basis of the existing research results in the laboratory. Based on the platform, a nuclear magnetic resonance (NMR) detection model of edible oil quality was established to identify the quality of edible oil. The research results are as follows: 1) based on the theoretical model of solenoid coil, the parameters of RF solenoid coil are designed and optimized with the relative signal-to-noise ratio (SNR) as the optimization target. The results show that when the coil diameter D and height H take 5.1mm, the linear diameter is 0.2mm and the number of turns n is 12 turns. The relative signal-to-noise ratio of the coil reaches the maximum, which is the optimal parameter model. The precise control of RF coil parameters is realized by improving the manufacturing process of solenoid coil. Finally, according to the signal-to-noise ratio of the experimental test, the accuracy and rationality of the theoretical model are verified. (2) the matching network of the probe RF circuit is improved, which effectively increases the tuning range of the probe and reduces the echo loss of the probe. The design and test of RF circuit are completed, including the simulation of RF circuit, the selection and test of components and components, the test of voltage value, etc. At the same time, by studying the selection of RF probe quality factors and integrating the designed RF coil and tuning matching circuit under 26.09MHz frequency, the RF probe is fabricated. The temperature control requirement of low field nuclear magnetic resonance detection platform is realized. The PID (proportional-integral-differential) parameters of the temperature control system were measured by the technical scheme of high precision temperature control system. At the same time, the temperature control performance and temperature gradient field of the system are optimized from the aspects of sensor position, air fluidity, heat preservation performance and ambient temperature. The resonance frequency of the detection system is determined, and the temperature control target of 36.0 鈩，

本文編號(hào)：1952162