To address the issue of the difference in surface energy between the top and bottom surfaces,a first principles-based method was employed to investigate the fixed modes of three different surfaces of AlN and Cu2O.The purpose is to correct the material's surface energy and compare it with the average sur-face energy.The results of the two schemes show that the surface energy rankings of AlN and Cu2O are(001)＜(010)＜(110)and(111)＜(001)＜(100),respectively.It is related to their incomplete differ-ences in dangling bond densities.
The actual trunk multi-core fiber (MCF) splicing is studied by a 7-core fiber for long-distance transmission. The results show that the quality of MCF splicing affects both transmission loss and crosstalk. The splicing quality is influenced by end-face treatment, discharge intensity, discharge time, electrode spacing and other parameters. By aligning the fibers controlled by the axis algorithm and optimization of the fusion splicing parameter, the typical value of splicing point loss can be less than 0.3 dB, which can better meet the requirements of application for engineering wiring.
The microchannel heat sink with periodically arranged triangular cavities and arc-shaped ribs (MC-ARTC) is investigated numerically under the conditions of Reynolds number 147-736. The effects of triangular cavities and arc-shaped ribs on velocity, pressure, and temperature distribution in the channel are analyzed in comparison with a rectangular microchannel heat sink, microchannel heat sink with arc-shaped ribs, and microchannel heat sink with triangular cavities. The results show that the triangular cavity and the arc-shaped rib have important effects on the flow and heat transfer characteristics in the microchannel heat sink. Both rib and cavity can cause a change in fluid flow direction and disturb the development of the flow boundary layer. The fluid flow and heat transfer characteristics of microchannels are improved. Among the four microchannels, the MC-ARTC has the optimum comprehensive performance for the combined effect of the rib and cavity. Relative cavity width (beta $\beta $) and relative rib height (theta $\theta $) are also defined to study the effects of cavity width (W t ${W}_{{\rm{t}}}$ = 89-200 mu m) and rib height (H a ${H}_{{\rm{a}}}$ = 8.9-28.9 mu m) on the flow and heat transfer characteristics. It is found that the heat transfer of MC-ARTC is enhanced with increasing W t ${W}_{{\rm{t}}}$ and H a ${H}_{{\rm{a}}}$, while lead to higher pressure drop. When beta $\beta $ and theta $\theta $ are 252 and 249 mu m, respectively, the comprehensive performance factor (P f ${P}_{{\rm{f}}}$) of MC-ARTC reaches 1.76.
为了提高1.55μm波段DFB激光器的输出性能及高温特性,制作了两种不同结构的InAlGaAs/InP大光腔激光器.两种激光器芯片均在外延设计上采用非对称结构,能够有效减少器件内吸收损耗,从而提高输出功率.对两种芯片均进行了不同腔长、发散角及高温性能测试,可以观测到采用较厚n侧限制层的芯片的输出功率更大.
以某轨道工程车为研究对象,利用Solidworks建立转向架刚性模型,对该模型进行网格划分后,使用ANSYS和SIMPACK建立包含柔性转向架的刚柔耦合动力学模型,研究转向架弹性变形对车辆直线运行稳定性、曲线通过性能和车辆运行平稳性的影响.以轴箱定位节点横向、垂向刚度,一系悬挂横向、垂向刚度,二系悬挂横向、垂向刚度为设计变量,设计拉丁超立方试验,利用RBF神经网络和NSGA-Ⅱ算法对横向、垂向平稳性指标,脱轨系数和轮轨横向力进行多目标优化.结果表明:轴箱定位节点横向、垂向刚度为5775 kN/m、11419 kN/m,一系悬挂横向刚度、垂向刚度为6042 kN/m、7834 kN/m,二系悬挂横向、垂向刚度为152 kN/m、158 kN/m时车辆动力学性能得到显著改善.
