Visualized pattern recognition optimization for apple mechanical damage by laser relaxation spectroscopy

Figures & data

Figure 1. Single wavelength laser relaxation spectroscopy detection system.

Figure 2. Algorithm flow diagram: (a) BP algorithm structure diagram; (b) DELM algorithm flow chart.

Table 1. Comparison of the advantages and disadvantages of different models.

Algorithms	Advantages	Disadvantages
BP	Strong non-linear mapping capabilities, strong self-learning and self-adaptive capabilities, as well as good fault tolerance.	Slow convergence of algorithms and a wide choice of neural network structures.
DELM	There is a canonical term restriction that prevents overfitting of the model.	Long training hours

Table 2. Parameters and results of different model runs.

BP		DELM
Training time	0.192s	Max_iteration	100
Optimal number of iterations	841	Number of hidden layers of ELM-AE	^[Citation29,Citation31]
Number of implied layers	3	popsize	80
Number of training set samples	1500	Number of training set samples	1500
Number of test set samples	323	Number of test set samples	323
BP		DELM	SSA-DELM
Training set accuracy	0.918	0.843	0.861
Test set Accuracy	0.9474	0.855	0.846
NPR (test set)	0.967	0.957	0.915
TPR (test set)	0.909	0.667	0.732

Figure 3. Results of different models: (a) DELM and SSA-DELM model test set classification results; (b) SSA-DELM algorithm convergence curve; (c) BP neural network structure visualization model diagram; (d) BP neural network training set and validation set accuracy graph; (e) BP neural network training set and validation set loss value graph.

Table 3. Comparison of accuracy of different models optimized by MMCR.

Model name	Average bar count classification accuracy		Result classification accuracy
	Damage（NPR）	Undamaged（TPR）	Damage （NPR）	Undamaged （TPR）	Average
BP	100%	87.5%	100%	95%	97.5%
DELM	98%	25%	100%	15%	57.5%
SSA-DELM	100%	33%	100%	20%	60%

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Data availability statement

Data sharing does not apply to this article as no datasets were generated or analyzed during the current study.