The theoretical and numerical calculation and experimental study on soft contact electromagnetic casting forming
Based on classical electromagnetic theory, the electromagnetic pressure calculation model and the formula of electromagnetic casting forming have been established. Theoretical and numerical results indicated that the frequency, current density, relative permeability of alloy melt and resistivity can also influence the effect of electromagnetic pressure. Meanwhile, the effect of metal physics properties parameters on the value of electromagnetic pressure is more complicated. The needed magnetic field for casting Al-Si alloys liquid column with length of 0.05m in experiment was very close to the theoretical value. This result indicated that the formula of electromagnetic casting forming can be used to guide experiments and the actual industrial production.
Numerical Simulation of Magnetic Field Distribution in Intermediate-Frequency Soft-Contact Electromagnetic Continuous Casting Mold for Round Billets
The method of numerical simulation is used to research the distribution of magnetic field in the intermediate-frequency soft-contact electromagnetic continuous casting mold for round billets,and the changes of magnetic induction intensity along with the changes of structure parameters of mold,processing parameters and electrical parameters are discussed.The results show that in the intermediate-frequency electromagnetic field,the magnetic induction intensity in mold first increases and then decreases,and the Bz is maximum just below the center height of coil.Comprehensively considering the structure and magnetic permeability of mold,the appropriate slit width is 0.5 mm,and the appropriate slit number is 8,the largest magnetic induction intensity can be obtained when the initial surface of the molten steel is at center height of the coil,and the magnetic induction intensity in mold increases with the increase of induction current intensity and frequency.
Nonprofit Communication and Fundraising in China: Exploring the Theory of Situational Support in an International Context
Using a survey of 586 college students from Beijing, China, this study tested the theory of situational support by exploring Chinese students’ motivations to participate in nonprofit fundraising events. This study also compared theory variables between Chinese and U.S. college students by looking at similar data from a survey previously conducted with 514 U.S. students. There were differences between the two groups regarding constraint recognition, subjective norms, attitudes toward fundraising, and other variables, perhaps because of Confucianism, collectivism, and other differences between China and the United States. The findings generate a range of theoretical and practical implications including how nonprofit practitioners in China might develop better communication and messaging strategies to segment publics, motivate potential donors, and advance future fundraising efforts.