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Coil shape quality is the external representation of strip product quality, and it is also a direct reflection of strip production process level. This paper aims to predict the coil shape results in advance based on the real-time data through the designed algorithm.

Aiming at the strip production scale and coil shape application requirements, this paper proposes a strip coil shape defects prediction algorithm based on Siamese semi-supervised denoising auto-encoder (DAE)-convolutional neural networks. The prediction algorithm first reconstructs the information eigenvectors using DAE, then combines the convolutional neural networks and skip connection to further process the eigenvectors and finally compares the eigenvectors with the full connect neural network and predicts the strip coil shape condition.

The performance of the model is further verified by using the coil shape data of a steel mill, and the results show that the overall prediction accuracy, recall rate and F-measure of the model are significantly better than other commonly used classification models, with each index exceeding 88%. In addition, the prediction results of the model for different steel grades strip coil shape are also very stable, and the model has strong generalization ability.

This research provides technical support for the adjustment and optimization of strip coil shape process based on the data-driven level, which helps to improve the production quality and intelligence level of hot strip continuous rolling.

Cascaded DC-DC converters system is the main structure of distributed power system, and it has complex nonlinear phenomena during operation, which affect the power quality. Therefore, the dynamic behavior of the cascaded buck converter and boost converter system, as one of the typical cascaded DC-DC converters systems is analyzed.

Firstly, the studied cascaded system of the buck converter with peak current control and the boost converter with PI current control is introduced and its discrete modeling is built. Then, the Jacobian matrix of the cascaded system is calculated to research the stability when the parameter change. Finally, simulation by PSIM and experiments are carried out to verify the theoretical analysis.

The coexistence of fast and slow time scale bifurcations with the changes of reference current and input voltage are studied in the cascaded system, and using simulation analysis to further study the sensitivity of the inductor current of the front-stage converter and back-stage converter to different parameters.

A discrete model of the cascaded buck converter and boost converter system is established, and its dynamic behavior is analyzed in detail for the first time.

Dairy products are an essential part of a healthy diet, and dairy is an emerging food industry in China. Meanwhile, the dairy industry is one of the “disaster zones” with quality and safety issues occurring more frequently in its supply chain than in others. Based on qualitative research focused on consumers in the Northwest and South of China, the present study aims to understand and provide information on consumer perception of food safety in dairy products.

Nine focus group interviews were carried out from January to April 2018. Altogether, 61 participants (24 males, 37 females, aged 18–60 years) were recruited in four cities. Qualitative content analysis of the data was conducted using Nvivo version 11.4.0.

A high concern with the safety of dairy products is widespread, particularly among participants with children, who are especially worried about the safety of dairy products. High prevalence of food safety incidents causes consumers to lower their confidence in food safety, and make them pay more attention to the news about food safety incidents. Consumers tend to become less sensitive to price, focusing more on food safety and quality, while purchasing dairy products. Brand and purchase venue are the most important indicators for consumers to determine the quality of dairy products. Safety certification becomes increasingly important.

It has some limitations. The focus group interviews covered different two regions (Northwest and South of China). However, the number of focus groups was limited to nine because of budget constraints. The participants come from Northwest and South of the country, which means that the findings may not apply for another area of the country. A more representative sampling with a larger sample size would be necessary to increase the validity of the study. However, the results can serve as input for further research.

This paper explores the Chinese consumers' perception of food safety and dairy products, consumers' behaviour concerning dairy products based on focus group interviews with consumers. This study offers valuable insights to members of academia, food suppliers and policy-makers.