基于外部特征及子带谱质心法的西瓜糖度检测  

Watermelon sugar content detection based on the external characteristics and sub-band spectrum centroid method

作　　者：庄为 李臻峰 宋飞虎 李静[1,2] 朱冠宇 ZHUANG Wei1,2, LI Zhen-feng1,2, SONG Fei-hu1,2, LI Jing1,2 ,ZHU Guan-yu1(1. School of Mechanical Engineering of Jiangnan University, Wuxi, Jiangsu 214222, China ; 2. Jiangsu Key Laboratory of Advanced Food Manufacturing Equipment and Technology, Wuxi, Jiangsu 214222, China)

机构地区：[1]江南大学机械工程学院,江苏无锡214122 [2]江苏省食品先进制造装备技术重点实验室,江苏无锡214122

出　　处：《食品与机械》2018年第8期48-53,共6页Food and Machinery

基　　金：国家自然科学基金(编号:515082290);江苏省产学研联合创新资金(编号:BY2014023-32);政策引导类计划(产学研合作)-前瞻性联合研究项目(编号:BY2015019-16)

摘　　要：针对振动无损检测方法对硬件系统及测试条件要求较高,且实际应用系统设计很少的问题,开发便携式振动检测系统,对时间信号进行小波阈值去噪后,提取某特定西瓜品种的子带频谱质心,并提出横径的平方与纵径乘积作为体积参数。研究发现,子带频谱质心频率点与西瓜的质量、体积参数呈负相关,对激励力度依赖性较小。将质量、体积参数、子带频谱质心频率点作为变量,利用逐步多元线性回归分析和曲面建模,建立糖度检测模型。曲面建模法所建模型较好,确定系数达到0. 881 1,预测集样本的标准差RMSEP略大于校正集样本的,并且RMSEP和RMSEC均小于最大糖度的10%。该模型可以很好地利用216~268 Hz的子带频谱质心频率点对8~10成熟西瓜进行糖度预测。At present,the vibration nondestructive testing method has high requirements on hardware system and test conditions,and few practical application systems have been designed.. In order to solve this problem,a portable vibration test detection system was built. The time signal was denoised by the method of wavelet threshold denoising. The sub-band spectrum centroid of a certain watermelon variety was extracted. The product of square of transverse diameter and the longitudinal diameter was proposed as the volume parameters. It is found that the frequency point of sub-band spectrum centroid is negatively correlated with the quality of watermelon and the volume parameters,and is less dependent on the intensity of the excitation. Using stepwise multivariate linear regression analysis and surface modeling established the sugar detection model,and the quality of watermelon,the frequency point of sub-band spectrum centroid and the volume parameters were variables. The model established by surface modeling method is better. The determination coefficient of the model reached 0. 881 1,the standard deviation of the prediction set sample RMSEP was slightly larger than the standard deviation of the calibration set RMSEC,and RMSEP and RMSEC were both less than 10% of the maximum sugar content. The model can be well used to predict the sugar content of the watermelons of the maturity of 80% to 100% with the frequency point of sub-band spectrum centroid of 216 to 268 Hz.

关 键 词：振动检测 西瓜糖度 子带频谱质心 逐步多元线性回归 曲面建模 

分 类 号：S651[农业科学—果树学]