基于压电材料的主动吸声降噪方法研究

提出了用压电材料进行主动吸声的方法。用压电陶瓷作为主动吸声系统中的吸声材料,通过等间距布置于压电陶瓷正前方的两个麦克风传感器,检测出平面入射声波与反射声波,利用压电陶瓷的压电性能,在压电陶瓷上加电压使得反射声波为零,从而达到主动吸声的目的。最后对不同频率入射的声波用matlab语言进行了仿真,仿真结果表明文中所提方法的可行性。

Preparation and thermal conductivity of tungsten coated diamond/copper composites

Tungsten was plated on the surface of diamond by using thermal diffusion method.Different process parameters were employed to prepare the composites with tungsten,diamond and copper.The micro morphology of different samples was observed,and the thermal conductivity of samples was measured by laser flash method.The optimal process parameters for preparing diamond/copper composites with high thermal conductivity were investigated.The results indicated that plating tungsten on diamond could modify the interface bonding.When the diamond was plated for 60 min,the coating appeared intact,uniform and flat,and the thermal conductivity of the sample could reach as high as 486 W/(m·K).The integrity and uniformity were more important than thickness for the coating.When the tungsten-plated diamond was further annealed,the metallurgical bonding between the coating and the diamond was enhanced,and the thermal conductivity rose to 559 W/(m·K).

塑料异型材彩色共挤面表面质量的控制

门窗用塑料异型材彩色共挤面的表面质量是评价共挤型材的一个重要的指标,型材表面质量的好坏直接影响到型材的外观。本文从共挤出模具的角度讨论了提高型材共挤表面质量的方法。

整体煤气化联合循环技术综述

介绍国外整体煤气化联合循环技术的发展现状及运行情况,展示整体煤气联合循环技术装置的性能指标和技术路线,指出整体燃蒸联合循环发电技术将是二十一世纪能源建设的重要方向。