用“微波辐照——盐酸浸出法”制备酸溶性富钛渣的研究

本探讨了将微波这一新技术应用在钛铁矿冶金的可行性．结果表明,钛铁矿精矿经“微波辐矿经”微波辐照——盐酸浸出法”能制得供硫酸法生产钛白的酸溶性富钛渣,且具有方法新、能耗低、工艺简便等特点．     

A numerical study of the fluid flow and heat transfer around a single row of tubes in a channel using immerse boundary method

The analysis of the time-dependent and two-dimensional fluid flow and heat transfer around a single row of tubes in a channel is performed numerically. Due to its fundamental significance and practical importance, aerodynamic and heat transfer characteristics of tube bundle have been paid great attention by many researchers. In the present study, the immersed boundary method is applied by using a Cartesian grid system. Numerical solution for the governing equations of mass, momentum and energy conservation is obtained with the finite volume method. To validate the numerical approach with the immersed boundary method, the results have been compared with published data. The generation and evolution of vortical structures, wake interactions and their effects on the drag, lift and heat transfer are analyzed at different Reynolds numbers. The effect of hydraulic boundary layer development on the fluid flow and heat transfer is also investigated.     

无铅化PCB表面材料及工艺特点

无铅化电子组装中PCB表面镀层技术主要有无铅钎料热风整平、浸锡、浸银、化学镀镍/浸金和有机可焊保护层五种。每种工艺技术具有各自的优缺点,每种工艺材料与不同无铅钎料具有不同的兼容性。从可制造性、可生产性以及与无铅钎料的匹配性等方面对五种PCB表面镀层技术做了较为全面的阐述,并通过对润湿性和可靠性评估得到一定的最佳配比,为...