5.1. Collection of Sample Data
1. Pledge Risk
Price stability (NW1): Price stability is influenced by the variety of pledges and changes in market supply and demand [
43] and is expressed as the volatility of the product price. When price volatility is less than 5%, the pledge price stability is considered strong with a value of 3. When price volatility is 5%–10%, the pledge price stability is general with a value of 2. Lastly, when price volatility is greater than 10%, the pledge price stability is poor with a value of 1.
Legality (NW2): According to the signed confirming warehouse financing contract, we determine whether or not the pledge is legal. If the 3PL and financial institution determine that the pledge is legal, then the pledge is legally strong and takes a value of 3. If the financial institution and 3PL do not clearly state the legal status of the pledge, then the legality of the pledge is generally defined and takes a value of 2. If the pledge provided by the financing enterprise has obvious illegality, then the pledge is considered to have a low level of legality and takes a value of 1.
Liquidity (NW3): The liquidity of pledges is affected by market demand, market prices, and the substitutability of the collateral. After a comprehensive analysis of various influencing factors, we find that if the pledge has strong liquidity, it takes a value of 3. If the pledge has general liquidity, then it takes a value of 2. If the pledge has weak liquidity, then it takes a value of 1.
2. Credit Risk of Financing Companies
Performance ability (NN1): It is a quantitative indicator measured by the company’s compliance rate as follows:
where
is the total number of annual contracts of the enterprise and
denotes the number of contracts by default.
Continuing ability (NN2): If the company has been in business for more than five years, then we assume that the company’s ability to sustain its operations is strong and takes a value of 3. If the company is operating for three to five years, then we assign a value of 2 for its ability to continue operations. If the company has been operating for less than three years, it takes a value of 1, which indicates poor performance.
Profitability (NN3): This term pertains to the profitability of financing companies. The study uses quantitative indicators for the return of assets of enterprises [
44].
Solvency (NN4): The solvency of enterprises is a quantitative indicator expressed by the asset liability ratio of financing companies [
45].
3. Internal Management Risk
Pledge assessment risk (NP1): We stipulate that if the evaluation price of the pledge is lower than the market value, then the pledge is well evaluated and takes a value of 3. If the assessed value of the pledge is equal to the market value, then the pledge is considered normal and takes a value of 2. Lastly, if the pledge evaluation is higher than the market value, then the pledge evaluation is poor and takes a value of 1.
Regulatory system normative (NP2): If the enterprise has a documented implementation of a supervision program for supply chain finance, then the regulatory system is standardized and takes a value of 3. If an enterprise has an unwritten regulatory system, then its regulatory system is generally normative and takes a value of 2. If the enterprise does not have a regulatory system for supply chain finance, then the normativeness is considered poor and takes a value of 1.
Inventory risk warning (NP3): If the enterprise sets a safety stock warning for the pledge with special personnel engaged in inventory risk processing, it takes a value of 3. If the enterprise does not set a safety stock warning, then the inventory risk is high and takes a value of 1. The value between the two is 2.
Operational risk (NP4): If confirming warehouse financing is strictly in accordance with the provisions of the contract, then no deviation will occur amid the operation. This condition indicates that the operational risk is low and takes a value of 3. If confirming warehouse financing completely deviates from the contract and operates independently, then the operational risk is considered large and takes a value of 1. If the operational risk is between the two levels, then it takes a value of 2.
Organizational rationality (NP5): If the company has accordingly set up a department for supply chain finance with a clear division of labor, then the organization is reasonable and takes a value of 3. If the enterprise has formed a department for supply chain finance without a clear division of labor and system, then the organization is generally reasonable and takes a value of 2. If the company does not have an independent business unit for supply chain finance, then the organization is not highly reasonable and takes a value of 1.
4. Contractual Legal Risk
Contract standardization (NR1): If a standard written contract exists in the business model of the confirming warehouse and does not require revision and supplementation, then the standardization of the contract is high and takes a value of 3. If a standard contract exists but needs modification and supplementation according to specific circumstances, then the standardization degree of the contract is low and takes a value of 2. In the absence of a standard contract, its standardization is considered low and takes a value of 1.
Contractual liability risk (NR2): If the contract for confirming warehouse financing has a clear division of responsibilities among the three parties, then the agreed liability risk is low and takes a value of 3. If the business contract has a clear division in terms of responsibility among the three parties with certain ambiguous areas, then the agreed liability risk is general and takes a value of 2. If the contract does not have a significant division of risk, then the risk is high and takes a value of 1.
Legal policy risk (NR3) [
46]: If the local government imposes management regulations and measures for supply chain finance and both enterprises comply with corporate and contract laws, then the legal policy risk is low and takes a value of 3. If the local government has no relevant laws, but the enterprises are in compliance with contract and enterprise laws, then the legal policy risks are general and takes a value of 2. If the local government is undergoing war or financial crisis and economic and political instability, then the legal policy risks are high and takes a value of 1.
3PL too much responsibility (NR4): If the logistics enterprise undertakes a number of businesses, such as supervision, transportation, and pledge evaluation, then it bears excessive responsibility and takes a value of 3. If the logistics enterprise only bears its internal responsibility, then it bears minimal responsibility and takes a value of 1. If it is neither of the two scenarios, then it takes a value of 2.
In this work, the following 24 sets of sample data are obtained through data search and analysis, where D represents the risk level of each supply chain finance business. We obtained the data according to the Duffel method. Sample data is shown in
Table 7.
5.3. Training and Testing of BP Neural Network
1. Determining the Number of Neurons in the Hidden Layer
We establish the risk measurement model of confirming warehouse financing from the 3PL perspective using the BP neural network and MATLAB for training and testing. On the basis of the risk measurement model, the number of input neurons is determined to be 16. The number of neurons in the output is related to the evaluation results, which are proposed as a risk level and unique. The output values are assigned the following values: high risk = 3, medium risk = 2, and low risk = 1. The number of neurons in the hidden layer is determined using the Equation (1). The number of neurons in the hidden layer is determined to be 5~15 given that the numbers of neurons in the input and output layers are 16 and 1, respectively.
To carry out the training and testing of sample data, we select 24 sets of sample data and utilize 20 of them as training data for the risk measurement model of confirming warehouse financing from the 3PL perspective. The remaining 4 sets of data are used as sample data to verify the authenticity of the training results. We use sets 1–20 of the sample data as the training data and sets 21–24 as the test sample data.
Moreover, we design a three-layer BP neural network with the tansig transfer function for the hidden layer, purelin for the output layer, and a hidden layer of neurons of 5~15. The training function selects the traingm function; the maximum number of trainings is set to 10,000, and network error is set to 0.001. At this point, only the error curves of the number of neurons in the hidden layer are selected as 11, 12, 13, and 14 for comparison.
Trained as shown in
Figure 3, we find that the convergence rate of the BP neural network gradually accelerates with the increase in the number of neurons in the hidden layer. In addition, the training error is gradually reduced. When the number of neuronal nodes reaches 13, the error reaches a minimum value
. This value is smaller than
when the hidden layer node is 12 and increases by up to 14 times when the hidden layer neuron node is
. From the aspects of convergence speed and descent stability, epoch = 180 when
, epoch = 114 when
, and epoch = 229 when
. After repeated simulation training, the error results of the five trainings are selected for comparison. When the number of neurons in the hidden layer is set to 13, the average error value is small. This finding indicates that this number of neurons is the optimal number of neurons in the hidden layer when the number of neurons is 13.
Table 9 provides the simulation error results.
2. Training Function
When the model selects a neuron node in the hidden layer, the training function used is traingdx, whereas the training of traingdm and traingd is not simulated. In the case of selecting the optimal training function, the selected function should be compared with the optimal training function under common training parameters. Then, the best training function is superior. At this time, the implicit layer transfer function is set to tansig, the output layer transfer function is purein, and the number of neurons in the hidden layer is set to 13. The maximum number of training times is set to 2000, the network error is set to 0.001, and traingdm and traingd are selected for the excitation function of the hidden layer due to their slow convergence speed.
Figure 4 presents the training results.
The training results indicate that when the traingdx function is selected, the network convergence path only reaches 114 steps to reach the expected error value, and error at this time is 0.000876. Under the same training parameters, the traingdm function must reach upon reaching the training target error value, and when the training function used is traingd. Comparing the error values of the two functions, we find that the error value of the traingdm function is greater than the error value of the traingdx. Thus, the traingdx function value is selected as the training function of the hidden layer due to its relatively fast convergence speed and minimal error.
3. Determining the Learning Rate
The network learning rate influences the stability and convergence of the BP neural network. To obtain a good network learning rate, we screen the MATLAB network learning rate, which has a default value of 0.01. Then, we select learning rates of 0.005 and 0.02 to train the model. The training functions of the hidden, input, and output layers select the traingdx, tansig, and purelin functions, respectively. In addition, the number of neurons of the hidden layer is set to 13 with a maximum number of training steps set to 2000 and expected network error value of 0.001.
Figure 5 presents the training results.
We compare the training values of the three learning rates. At learning rates of 0.005, 0.02, and 0.01, the error values obtained are 0.000976, 0.000987, and 0.000876 with training frequencies of 171, 140, and 114, respectively. The comparison further indicates that at learning rates of 0.005 and 0.01, the error and number of training times are greater than the learning rate of 0.01 with a relatively large fluctuation in the error graph. Given a learning rate of 0.01, the neural network model has good stability. Therefore, the selected learning rate is 0.01.
4. Training and Inspection
Through continual training and testing of the BP network, we establish the various index parameters of the risk measurement model of confirming warehouse financing based on the BP neural network from the 3PL perspective. The number of neurons in the input and output layers is 16 and 1, respectively, whereas the number of neurons in the hidden layer is 13. The implicit layer transfer function is tansig, the training function is travelingdx, and the transfer function of the output layer is purelin with the learning rate set to 0.01 and target error value set to 0.001. Next, we train sample data 1–20 and obtain the output value, as shown in
Table 10.
The table shows that the absolute error between the BP neural network training result and expected target value is remarkably small and is within 0.1. In addition, output value Y can well represent the risk situation of a business, which is consistent with the results obtained by comprehensive evaluation. Among the 20 sets of sample data for training, a majority of the supply chain finance services are in a high-risk state, which accounts for more than 40% of the overall businesses. This finding serves as a good warning for the risk prevention of ZY Logistics in supply chain finance. The training results show that the established risk measurement model is characterized by markedly high precision and accuracy and can measure and evaluate the risks of supply chain finance.
The following sets of sample data are used to test the generalizability of the BP neural network model. Results are consistent with predictions, that is, the 3PL perspective of the index system for measuring the risk of confirming warehouse financing is scientific and reasonable.
Table 11 provides the results.
The test errors of the four groups of cases are −0.042998, −0.011102, 0.020514, and 0.039448—all of which are small and negligible. The difference between the output value “Y” of the neural network and expected target value is small. In addition, the output result is consistent with the predicted result, which indicates that the proposed risk measurement index system has good evaluation and applicability to the risk of supply chain finance of ZY Logistics. Through the combination of the actual cases of ZY Logistics, the BP neural network verified the established risk measurement index system of confirming warehouse financing from the 3PL perspective. The verification results indicate the rationality and applicability of the established indicator system for risk measurement.