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  本文關(guān)鍵詞： 揮發(fā)氣味 可視化傳感器 檢測 反應(yīng)室 圖像處理　出處：《江蘇大學(xué)》2017年碩士論文　論文類型：學(xué)位論文

【摘要】：氣味是食品、農(nóng)產(chǎn)品的重要屬性,可以通過揮發(fā)性氣體的檢測實現(xiàn)食品的品質(zhì)、真?zhèn)�、貨架期等的分析和區(qū)分。嗅覺可視化傳感器技術(shù)是檢測氣體的新技術(shù),它利用色敏材料制作的傳感器陣列與待檢測氣體發(fā)生反應(yīng)時傳感器的顏色變化,對揮發(fā)性有機(jī)氣體(VOCs)進(jìn)行定性或定量分析,并且將氣味信息以直觀可視的圖像方式表達(dá)出來。在嗅覺可視化技術(shù)檢測食品品質(zhì)中,揮發(fā)氣體在反應(yīng)室內(nèi)與傳感器的分布與接觸狀況以及傳感器的圖像信號處理和分析對檢測精度有很高的影響�；诖�,本研究設(shè)計并優(yōu)化了氣體分布反應(yīng)室,對圖像處理流程中的部分算法和方案進(jìn)行了比較研究,以實現(xiàn)不同存儲時間食醋和大米氣體的檢測和區(qū)分。論文的主要研究內(nèi)容如下:(1)設(shè)計了一個在進(jìn)氣口前嵌入弧形擋板以起到引流效果的反應(yīng)室,利用COMSOL Multiphysics仿真軟件對反應(yīng)室進(jìn)行流場模擬。仿真效果顯示擋板的彎曲程度是影響氣體分布比較關(guān)鍵的因素,擋板位置雖然也會影響反應(yīng)室中氣流的分布,但是與前者相比,其影響并不是很大。當(dāng)擋板的彎曲程度大時,會導(dǎo)致反應(yīng)室中間的氣體流速大,兩側(cè)的氣體流速小,且氣體主要分布在中間通道區(qū)域,四周的氣體分布較少;當(dāng)擋板的彎曲程度過小時,情況相反。當(dāng)擋板靠近進(jìn)氣口,會導(dǎo)致傳感器陣列兩側(cè)氣體流速變小;當(dāng)擋板遠(yuǎn)離出氣口,則會使色敏傳感器陣列中間的氣體流速變小,同時,氣體在靠近出口部分的分布較廣。經(jīng)過反復(fù)仿真模擬本研究確定當(dāng)擋板曲率為3.3,擋板前端距離進(jìn)氣口的垂直距離為1.5cm時,仿真的效果最好。通過COMSOL Multiphysics提取傳感器陣列各區(qū)域的速度進(jìn)行比較,同樣表明擋板形狀和位置優(yōu)化后的反應(yīng)室更能夠保證反應(yīng)室中各區(qū)域流場均勻。本研究同時對反應(yīng)室的部件和整體尺寸、材料進(jìn)行了設(shè)計。利用溴甲酚綠和乙酸的顯色反應(yīng),將加工制作完成后的反應(yīng)室,與模擬氣體自由揮發(fā)環(huán)境的反應(yīng)室進(jìn)行試驗比較,結(jié)果顯示有擋板反應(yīng)室下,提取的顏色區(qū)域相應(yīng)各分量特征的平均值一般較大,變異系數(shù)偏小,說明前者中乙酸氣體與傳感器陣列的反應(yīng)更加充分,其均衡性也較好。(2)對圖像處理流程中的圖形中心點定位、特征區(qū)域選取、顏色空間模型的選擇進(jìn)行了比較和分析。首先,應(yīng)用一階矩、最小外接矩形、橢圓擬合等方法,來求目標(biāo)圖形的中心點坐標(biāo),結(jié)果顯示,三種方法都能滿足實際應(yīng)用時的需要,而第一種方法的計算量和耗時相對較少。其次,分別對應(yīng)用中心定位取圓形區(qū)域為特征區(qū)域,與漫水填充法分割傳感器不同顏色分布層為特征區(qū)域進(jìn)行了對比,結(jié)果顯示靠近傳感器中心的顏色層并不能很好反應(yīng)傳感器反應(yīng)前后的特征,而選擇剔除中心顏色層的外圍區(qū)域為特征區(qū)域更為合理。最后,對基于RGB、HSV和Lab三種顏色模型提取的傳感器顯色區(qū)域特征數(shù)據(jù)進(jìn)行了比較分析,結(jié)果顯示,Lab顏色空間模型時,特別是在顏色分量Δa和Δb下,其特征變量的標(biāo)準(zhǔn)差較小。相較于RGB和HSV顏色模型,在Lab顏色模型下提取的特征值具有更高的穩(wěn)定性。(3)應(yīng)用設(shè)計的嗅覺可視化系統(tǒng)及圖像處理方法,分別以食醋和大米作為液態(tài)和固態(tài)食品的代表,對產(chǎn)品的儲藏時間進(jìn)行了檢測和區(qū)分。首先,在檢測新醋和醋齡1~4年的食醋時,分別在RGB、HSV和Lab顏色空間下提取特征數(shù)據(jù),并結(jié)合主成分分析(PCA)和線性判別分析(LDA)等,比較了不同顏色模型下醋齡檢測的識別率。結(jié)果顯示,在顏色模型為Lab,LDA模型對食醋年限的鑒別效果最好,這也進(jìn)一步驗證了Lab顏色空間的較優(yōu)表現(xiàn)。其次,在利用嗅覺可視化系統(tǒng)檢測不同年限食醋時,分別應(yīng)用了新反應(yīng)室和模擬氣體自由揮發(fā)環(huán)境的反應(yīng)室,PCA和LDA分析的結(jié)果顯示,在新反應(yīng)室下,當(dāng)主成分?jǐn)?shù)為8時,模型的訓(xùn)練集和預(yù)測集的識別率均達(dá)到95%,且相同主成分?jǐn)?shù)時,識別率一般高于在模擬氣體自由揮發(fā)環(huán)境的反應(yīng)室,這說明前者的模型穩(wěn)定性和準(zhǔn)確性更高。最后在新反應(yīng)室和模擬氣體自由揮發(fā)環(huán)境的反應(yīng)室下,對新米和陳米氣味進(jìn)行檢測,結(jié)合PCA可知,前者可以100%地區(qū)分出兩種不同的大米,這也進(jìn)一步驗證了所設(shè)計的新反應(yīng)室的可行性。
[Abstract]:The smell is an important attribute of food, agricultural products, through the detection of volatile gas to achieve the food quality, authenticity, analysis and distinguish the shelf life of the sensor. The olfactory visualization technology is a new technology for gas detection, it uses a sensor array making color sensitive material changes color sensor and the tested gas react, to volatile organic compounds (VOCs) qualitative or quantitative analysis, and the odor information in the way of image visual expression. The olfactory visualization technology in food quality detection, gas distribution in the reaction chamber and the sensor and the contact condition and the image sensor signal processing and analysis have great influence on the detection accuracy based on. This, the research on the design and optimization of the distribution of gas reaction chamber, in the process of image processing algorithm and scheme are studied, in order to realize Detection and differentiation of vinegar and rice with storage time of gas. The main research contents of this paper are as follows: (1) a design of the front of the air inlet baffle to embedded into the reaction chamber drainage effect, the flow simulation of reaction chamber using COMSOL Multiphysics simulation software. The simulation results show that the factors which affect the bending degree of baffle the key of gas distribution, baffle position although also can influence the gas flow distribution in the reaction chamber, but compared with the former, the impact is not great. When the bending degree of baffle is large, will cause the gas flow velocity in the middle of a large reaction chamber, on both sides of the gas flow rate is small, and the main gas distribution area in the middle channel. The distribution of less surrounding gas; when the bending degree of the baffle is too small, the opposite is the case. When the baffle near the inlet gas flow rate on both sides of the sensor array can lead to smaller; when the baffle is away from the outlet. The gas flow rate intermediate color sensor array becomes small, at the same time, the gas distribution in the near exit portion is wide. The study determined when the baffle curvature is 3.3 repeated simulation, the vertical distance from the front end of the air inlet baffle distance is 1.5cm, the best simulation results. Through the COMSOL extraction of Multiphysics sensor array in each region the speed comparison also shows that the reaction chamber baffle shape and position optimized more to ensure the regional reaction chamber. The uniform flow field and the research on the reaction chamber components and the overall size, materials are designed. Using the chromogenic reaction of bromocresol green and acetic acid, will be processed after the completion of the reaction chamber, for compared with the reaction chamber to simulate the gas free volatile environment, results show that the baffle reaction chamber, the corresponding color region extraction component average value is generally large, variation The small coefficient that acetic acid gas sensor array and the former reaction more fully, the balance is also good. (2) the image graphics processing center location in the process of feature selection area, color space selection of models were compared and analyzed. Firstly, based on the first order moment, the minimum bounding rectangle. The ellipse fitting method, coordinates, Center for target figure shows that the three methods can meet the needs of practical application, and the computation of the first method and time consuming less. Secondly, the application of positioning center take circular area for feature regions, different color segmentation sensor distribution layer feature compared with the regional flood fill method, results show that near the center of the color sensor layer is not very good characteristics before and after reaction and the choice of sensor response, peripheral region excluding center color layer for the feature area Is more reasonable. Finally, based on RGB, HSV and Lab three kinds of color model to extract the sensor data are compared and analyzed, the color region shows that the Lab color space model, especially in color components a and B, the characteristics of the variable standard deviation is smaller than RGB and HSV. Color model, feature extraction in the Lab color model value has higher stability. (3) the olfactory visualization system and image processing method is applied to design, vinegar and rice were used as liquid and solid food, the product storage time were tested and identified. First of all, in the detection of new vinegar vinegar at the age of 1~4 years and vinegar, respectively in RGB, feature extraction data of HSV and Lab color space, and combined with principal component analysis (PCA) and linear discriminant analysis (LDA), compare the recognition models of different colors under the old vinegar detection rate. The results showed that the color model For Lab, the best identification effect LDA model for vinegar age, this further proves the better performance of Lab color space. Secondly, in the detection of different years of vinegar using olfactory visualization system, are applied to the reaction chamber and the reaction chamber of new simulation of gas free volatile environment, analysis of the PCA and LDA results showed that in the new reaction chamber, when the concentration is 8, the model training and prediction sets, the recognition rate reached 95%, and the same number of principal components, the recognition rate is generally higher than that in the reaction chamber to simulate the gas free volatile environment, it shows that the stability and accuracy of the former is higher. Finally in the new reaction chamber the reaction chamber and Simulation of gas free volatile environment, to detect the new meters and the smell of rice, with PCA shows that the former 100% can distinguish two different types of rice, which further proves that the new reaction chamber design is feasible .

【學(xué)位授予單位】：江蘇大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2017
【分類號】：TS207.3;TP391.41

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