Application Study Of X-ray NDT In Grapefruit Quality Testing

A fundamental study of dynamic non-destruction measurement of grapefruit quality wascarried out in this research by using a set of X-ray system combining with the image processingtechniques.The fundamental study included establishing the relevant model to forecast the size ofgrapefruit and its edible rate, as well as studying the defect recognition technology for grapefruitgraining based on the gray level image. The results were as followed:(1) Through analyzing the structure of X-ray detection system and image-formingprinciple,collecting the blank background image with different parameters setting, as well asmaking statistical analysis, we discussed the relationship among the tube voltage intensity,current intensity and image grey value, and established a mathematical model. This model hashighly accuracy, which is important for eliminating background information and speeding upcalculation.(2) The relationship between the average gray-value and the thickness of both thegrapefruit's pulp and peel was fitted with the model. The pulp index model fitting degree is thehighest (which is up to0.9996), while the result for the peel is poorer. According to the pulpindex fitting model, we established a forecasting model for pulp volume. The linear fit (Y=X)between forecasting value of pulp volume and its actual value was done, and the fitting degreewas0.9923. Combined with X-ray images, we were able to forecast the edible rate of grapefruitthrough such model with high accuracy. It turned out that the misjudgment ratio was only7.81%.(3)Study on the effect of the shape, varieties and size of grapefruit on defect recognitionshowed that the shape and size of grapefruit had greater influence on the image defectrecognition, while the variety of grapefruit has less effect on it.(4) We applied the X-ray detector and image processing technology to grapefruit grainingrecognition and then compared the image with the object. Results showed that when thereexisted cracking phenomena along the axes place of grapefruit in the images, it turned out thatgrapefruit was under its graining stage; when there existed something like filiform in the images,it suggested that the moisture content was lower and the grapefruit had already lignified; thewhite fleck in the pulp area in the images implied the beginning of grapefruit graining. Throughjudging and grading the graining of grape fruit, as well as comparing with the object, it can be proved that the new technology for grapefruit graining recognition was of highly feasibility,whose misjudgment ratio reached only6.35%.