基于超声检测的沙窝萝卜品质评价方法研究

发布时间：2018-06-22 12:55

本文选题：超声波检测 + 沙窝萝卜　；参考：《天津科技大学》2017年硕士论文

【摘要】：天津的沙窝萝卜是广受大家喜爱的一种果蔬类产品,在国内外都有很高的声誉。鉴于目前对沙窝萝卜的质量分类大多还是人工依据外部质量指标来进行判别的这种状况,并结合超声波无损检测技术所具有的优点,本文提出利用超声波无损检测技术来实现沙窝萝卜内部品质的判别。因为影响沙窝萝卜内部品质的主要是糠心病害的发生,因此本文主要是针对沙窝萝卜内部是否存在糠心进行检测。完成的主要工作和成果有:(1)本文对果蔬类产品内部品质的检测现状进行了概述,通过超声波及其检测技术的介绍以及利用超声波检测果蔬类产品的国内外发展现状和成果的阐述,论述了利用超声检测沙窝萝卜内部品质的可行性。并设计了利用超声波检测沙窝萝卜糠心的实验方案。(2)根据所设计的实验方案,设计了一套适用于超声实验的检测平台。该实验检测平台采取半圆弧形的设计,从而使得可以满足实验过程中两个检测探头间0～180°范围内任意角度的要求,同时也可以满足对于不同轮廓形状以及直径大小的被测物体的检测,此外还实现了检测探头的完好装夹,从而来确保检测探头与被测物体的良好接触。(3)通过有糠心和无糠心这两种沙窝萝卜样品,对实验所得的物理参数与沙窝萝卜糠心与否进行了分析,通过分析得出,超声波的速度与沙窝萝卜内部是否糠心没有很明显的线性关系,并与样品的重量、直径的大小均无显著的影响。对于实验检测所接收到的超声波图形,从时域信号以及频域信号两方面进行了分析。通过对图形的时域信号的分析发现,有糠心的沙窝萝卜的振幅要小于无糠心的沙窝萝卜并在在信号图中会有缺陷波的存在。之后利用快速傅里叶变换(FFT)的方法得到信号的频谱图,对于信号的频谱图通过统计发现,在所测的批次中,有糠心的沙窝萝卜的频谱图中的最大幅度值小于18,而无糠心的最大幅度值要大于18。因此选定频谱图中的最大幅度值来对沙窝萝卜内部是否存在糠心进行判别。(4)在得到以上的结论之后,应用随机选取的样品对所得结论进行了验证,通过预测的糠心情况与实际的糠心情况的对比,得到该判别方法对于无糠心的沙窝萝卜以及有糠心的沙窝萝卜判别的准确率分别为81.25%和75%。之后,基于以上的分析,提出了初步实现沙窝萝卜内部质量等级的想法。
[Abstract]:Tianjin's sand pit radish is one of the most popular fruit and vegetable products, and has a high reputation both at home and abroad. In view of the current classification of the quality of the sand nest radish mostly by the artificial basis of the external quality index, and combining the advantages of the ultrasonic nondestructive testing technique, this paper proposes the use of ultrasonic wave. In this paper, the main work and results are as follows: (1) the status of the internal quality of fruit and vegetable products was detected in this paper. Through the introduction of ultrasonic and its detection technology and the development of ultrasonic detection of fruit and vegetable products at home and abroad, the feasibility of ultrasonic detection of internal quality of sand pit radish is discussed. An experimental scheme for detecting the heart of sand pit radish by ultrasonic wave is designed. (2) according to the experiment designed The scheme has designed a set of detection platform for ultrasonic testing. The test platform adopts a semicircular arc design, which makes it possible to meet the requirements of any angle within the range of 0~180 degrees between the two detection probes during the experiment, and can also meet the detection of the measured objects with different contour shapes and diameter. The good contact between the probe and the measured object is also realized. (3) through the analysis of the physical parameters of the two sand nest radishes with the bran heart and the no chaff, the physical parameters of the experiment and the heart of the sand pit radish are analyzed. The velocity of ultrasonic wave and the bran inside the sand pit radish are analyzed. There is no obvious linear relationship between the heart and the weight of the sample, and there is no significant influence on the weight of the sample and the size of the diameter. Two aspects of the time domain signal and the frequency domain signal received by the experimental detection are analyzed. The amplitude of the bran sand pit radish is less than that without the bran without the heart. There will be a defective wave in the signal map. Then the frequency spectrum of the signal is obtained by the method of fast Fourier transform (FFT). The maximum amplitude in the spectrum map of the bran nest radish is less than 18 in the measured batch. More than 18., the maximum amplitude value in the selected spectrum map is selected to distinguish whether the bran heart exists in the interior of the sand pit radish. (4) after the above conclusions are obtained, the results are verified by the random selected samples. By comparing the predicted chaff condition with the actual bran mood, the method is obtained for the no chaff. The accuracy rate of discrimination between sand nest radish and bran core radish was 81.25% and 75%. respectively. Based on the above analysis, the idea of the initial realization of the internal quality grade of the radish was put forward.
【学位授予单位】：天津科技大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TB559

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