低阈值大功率半导体激光器的研制

近几年来,针对光盘的信息处理、激光印刷和长距离通信等实际应用的需要,稳定的单模大功率半导体激光器的研究取得了很大进展.对于GaAlAs/GaAs激光器,限制输出功率增加的主要原因之一是腔面的光学灾变损伤,利用扩大近场束斑尺寸来减少腔面的光子流密度或使腔面变成对光不吸收的透明区都是提高功率输出的重要途径,而降低阈值电流减     

Back-Propagation Artificial Neural Networks for Water Supply Pipeline Model

IntroductionWater supply pipelines are the lifelines of a city.Their operation status will greatly influence socialdevelopment.Burst points in pipeline networksshould be found as soon as possible.　Due to their randomness,time variation,andperiodicity of urban water supply pipelines,it isvery difficult to locate burst points usingtraditional methods such as direct observing,sonardetecting,etc. The traditional methods cannotfind the burst point without frequent routinechecks.Sometimes,it is im…