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(1) Background. This study aims to improve the accuracy of the pricing model. (2) Methods. Heston model is combined with ResNet50 convolutional neural network model. Based on the optimization of Heston model parameters by genetic algorithm (GA), ResNet50 model is used to correct the deviation between market option price and Heston price, so a new hybrid option pricing model is established based on the empirical research on the European call options of Huatai-PB CSI 300ETF (code 510300), Harvest CSI 300ETF (code 159919), and SSE 50ETF (code 510050). (3) Results. The pricing result of the hybrid model is better than other single models and hybrid models. The model is applicable to the pricing of options with short and long remaining terms. (4) Conclusions. It is shown that the combination of Heston model and ResNet50 model with optimized parameters can ensure the interpretability of the model and enhance the nonlinear fitting ability of the model, which confirms the effectiveness of the hybrid model and provides a reference for investors and institutions to make scientific decisions.

The distinguished characteristic of casting process of natural yellow clay-bonded green sand is a strippable sintering layer formed at the interface of casting and mould. Hot shake-out can be realized because this sintering layer can firmly attach to the casting surfaces to protect castings at elevated temperature. Better surface quality of castings is achieved after the sintering layer easily shed from the casting surface at room temperature. In this study, a series of tests were carried out to reveal the characteristic of this sintering layer. First, thermal gravimetric/differential thermal analysis (TG/DTA) method was used for detailed analysis the thermal property of natural yellow clay-bonded green sand. And, X-ray diffraction (XRD) analysis was employed to define the phase composition at variable temperatures. Then, sintering experiments were carried out on mixtures of natural yellow clay-bonded sand with iron powder or iron oxides under different conditions. Finally, the mechanical performances of sinter layer of natural yellow clay-bonded sand at elevated and room temperatures were investigated. The result revealed that natural yellow clay-bonded green sand is a kind of low grade molding sand, and iron oxides participate in the forming of sintering layer. The sintering layer of natural yellow clay-bonded sand were proved both excellent plastic at elevated temperature and brittle at room temperature, which coincides with its behavior in the casting process.