用二维时域有限差分法计算机翼雷达散射截面

应用二维时域有限差分(FDTD)程序计算二维翼型NACA0012和金属方柱的双站雷达散射截面,与国内外文献上的结果进行比较,证明该程序的有效性.而后计算二维不同形状机翼的双站雷达散射截面(RCS)和不同后掠角时后掠翼和三角翼的双站RCS,得出不同形状机翼有不同的RCS分布;改变后掠角的大小可以改变机翼的RCS分布.因此,根据设计要求,可以通过选用不同机翼形状或不同大小的后掠角,使飞行器达到RCS减缩.     

Enhancing light extraction of GaN-based blue light-emitting diodes by a tuned nanopillar array

Surface patterning of p-GaN to improve the light extraction efficiency of GaN-based blue light-emitting diodes(LEDs) has been investigated. Periodic nanopillar arrays on p-GaN have been fabricated by polystyrene(PS) nanosphere lithography; the diameter of the nanopillars can be tuned to optimize the electrical and optical properties of the LEDs. The electroluminescence intensity of the nanopillar-patterned LEDs is better than that of conventional LEDs; the greatest enhancement increased the intensity by a factor of 1.41 at a 20 mA injection current. The enhancements can be explained by a model of bilayer film on a GaN substrate. This method may serve as a practical approach to improve the efficiency of light extraction from LEDs.     

多目标规划的极大熵方法

多目标规划的极大熵方法王雪华，秦学志（大连理工大学）ＴＨＥＭＡＸＩＭＵＭＥＮＴＲＯＰＹＭＥＴＨＯＤＦＯＲＭＵＬＴＩＯＢＪＥＣＴＩＶＥＰＲＯＧＲＡＭＭＩＮＧ￥ＷａｎｇＸｕｅ－ｈｕａ；ＱｉｎＸｕｅ－ｚｈｉ（ＤａｌｉａｎＵｎｉｖｅｒｓｉｔｙｏｆＴｅｃｈｎｏ...