In the process of double-layer gas-assiste extrusion of a plastic micro-tube, the tugging effect caused by the pressure difference of the gas cushion layer inside the die has a great influence on the external dimensions of the micro-tube. Therefore, this study establishes a two-phase extrusion model based on compressible gas and incompressible melt. Ansys Polyflow finite element software was used to numerically simulate the extrusion process of the melt to analyze the effect of the gas cushion layer pressure difference on the micro-tube deformation. The research shows that the shrinkage rate of the micro-tube increases with increasing pressure of the outer cushion layer, and the degree of tube wall migration increases, too. In the process of extrusion, the first normal stress difference at the entrance of the gas cushion layer shows a significant effect on the melt velocity field distribution and the extruded micro-tube cross-sectional deformation.

In the gas-assisted extrusion process, the melt inside the die is in a low-viscosity molten state, so the flow field of the gas cushion layer has a great effect on the cross-sectional shape of the micro-tube. Therefore, this study establishes the gas distribution chamber model of the gas-assisted die. Ansys Fluent software was used to simulate the gas flow field of the gas distribution chamber. The effect of the gas chamber structure on the size of the micro-tube was analyzed by the extrusion experiment. The research shows that the velocity unevenness coefficient of the gas outlet of the single gas chamber die is 11.8%, which is higher than that of the double gas chamber die. The use of a double gas chamber die can improve the stability of the gas cushion layer and the wall thickness non-uniformity of the micro-tube, which verifies the simulation results.

In recently years, there are more than 70% of power generated by coal station. Based on this, it can be shown that fossil fuels are the main consumption for generating energy. Burning fossil fuels will produce a lot of carbon dioxide and other harmful gas. Moreover, fossil fuels are unsustainable energy, which means it will run out in the future. For avoiding this situation, sustainable energy need to be exploited so that can replace fossil fuels. Currently, there are wind power, solar power, nuclear power in China. Some wind farms already built in different place of China. Due to high advantages of sea, China is paying attention to develop offshore wind farm. This essay introduces details of offshore wind farm including rules of designing facilities and outlook of each level in China.

Since February 2022, the intensification of the Ukrainian conflict has triggered significant impacts on financial market. Huge changes in supply and demand have led to a spike in stock volatility, which resulted in the growth in risk aversion among investors. The gold is regarded as a safe haven asset and has hedge function in the stock markets. In this study, a Monte-Carlo pricing simulation based on Black-Scholes model for chooser option was investigated using the underlying asset of gold. The gold price and volatility index were sourced from Yahoo Finance website and the Chicago Board Options Exchange (CBOE). According to the analysis, the present value of the average return for one-month chooser option is simulated as $58.91, using the initial gold price of $1965.10 and the strike price of $1977.3. The present value of the average return for one-month chooser option is significantly higher than traditional call or put options. According to the sensitivity analysis, the return of chooser option under the pricing model adopted is not sensitive to the changes in volatility and time, which indicates that this pricing model is able to resist to risks and play a better role in a high-volatility market. These results shed light on the optimization of investment portfolio under complex situations. The utilization of a new pricing method paved a path for the research of exotic options and the state-of-art applications of them in the financial innovation procedures.

Due to the complexity of mold flow channel parameters, they have a significant impact on medical microtubule forming quality during the gas-assisted extrusion process. In this paper, the influence mechanism of mold flow channel parameters on medical microtubule forming quality is investigated. First, the multiphase flow model of the medical microtubule gas-assisted extrusion process is established. Then, the numerical solution of medical microtubule extrusion is presented based on Polyflow finite element software. Further, the medical microtubule size, morphology, velocity, pressure, and first normal stress difference under different mold flow channel parameters are compared and analyzed. Finally, the experimental platform for gas-assisted extrusion is built, and the correctness of the numerical simulation is verified by the extrusion experiment. The simulation and experimental results show that under the 15–5 condition, the inner radius, outer radius, and wall thickness of the microtubule are closer to ideal values, and the forming quality is better than other parameters. As the ratio of the gas-assisted to non-gas-assisted sections increases, the gas effect becomes more intense, and the shrinkage of the microtube increases. In the gas-assisted section, the wall thickness and outer radius of the microtubes increase first and then decrease, and they stay the same near the exit section. This reveals that gas-assisted forming technology can effectively eliminate extrusion swelling.