How to adjust the temperature zone temperature and furnace speed parameters to optimize the furnace temperature curve, so as to improve the product quality is the main problem faced by the temperature curve optimization of the reflow furnace. In this paper, the heat transfer model is established by the heat convection and heat conduction equations, and the mechanism of temperature change in the welding area is analyzed. Then, by gradually determining the objective function and comprehensively establishing the optimization model according to the known conditions, the optimal parameters are solved, so as to solve the optimization problem of furnace temperature curve. According to Newton’s cooling law, specific heat theorem and Laplace equation, the temperature function of the center of the welding zone is deduced and solved, and the analytic function model of the temperature change in the center of the welding area can be obtained by synthesizing the inherent size conditions of the reflow furnace. Taking the corresponding data of experimental temperature and time as the fitting data, the undetermined parameters of the model were solved by nonlinear least square fitting method and undetermined coefficient method. The square sum of fitting residuals is 5857.7, which proves that the model has good fitting effect. Using the new experimental data to solve the model, the temperature change of the welding center at each position and time in the reflow furnace is analyzed. The temperature in the center of the welding area at the middle point of the low temperature zone 3, 6, 7 and the end of the small temperature zone 8 is 143.81°C, 181.78°C, 201.33°C, 228.97°C, respectively.
Pregnancy can cause many complications and chronic diseases. Dietary intervention has been impressed on the prevention and treatment of diseases during pregnancy. Reasonable dietary intake and nutritional fortification can contribute to decrease the risk diseases during pregnancy. Common pregnant diseases are postpartum depression, obesity, and diabetes. This paper is to review the maternal nutrition and the effect of fiber diet in patients with gestational diseases. It is well known that pregnant women require additional nutrition due to a series of alterations in the body's regular metabolic processes following fertilization. In addition to that, nutrition is regarded to be related to weight gain and gestational diabetes, which in turn affects the mental health of pregnant women negatively, hence improving nutritional intake may reduce these complications and their related short- and long-term morbidity. It has synthesized that pregnancy physiological changes may reveal the risk of chronic diseases, including insulin resistance and dyslipidemia as manifestations of diabetes and obesity. Although the direct influence of dietary soluble fiber on intestinal microbiota has been extensively researched, the impact of a high-fiber diet on pregnancy illnesses has yet to be properly investigated. Qualitative analysis shows that dietary fiber benefits to alleviate the impacts where pregnant diseases bring. High fiber dietary can control the calories intake and improve insulin resistant. Furthermore, dietary fiber is thought to be one of the dietary components that might help avoid the development of unfavorable mental health. Therefore, emphasize that the intake of dietary fiber is significantly vital to help improve maternal and child health.
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