大气波导的形成及其对雷达探测的影响

电磁波在海洋大气条件下传播时可产生大气波导现象。文章分析大气波导的形成以及对电磁波传播的影响,分析大气折射的存在条件,电磁波在大气波导中传播所受到的制约,总结出大气波导对雷达探测的影响。     

塔河油田超深井井筒掺稀降粘技术研究

基于热量传递原理和两相流动理论,建立了井筒掺稀油降粘工艺中产液沿井筒流动与传热的热力学模型。计算了产液沿井筒的温度分布和压力分布,同时进行了不同掺稀条件下降粘的室内实验。运用该模型结合实验结果对塔河油田稠油井掺稀降粘效果进行了计算,分析了不同工艺参数对掺稀降粘效果的影响。结果表明,井筒掺稀油降粘工艺适合于含水率低于20%的油井,开式掺稀油反循环比开式掺稀油正循环生产更有利于提高降粘效果,塔河油田井筒掺稀降粘合理的掺稀比率为1:2至1:1。     

激光能量密度对激光弯曲成形的影响

激光弯曲成形是一种热应力成形塑性加工技术.光斑的能量密度的大小对弯曲角度和材料的组织性能影响很大.增加能量密度,板料的弯曲角度显著增大.对于一种材料,总存在一组特定的工艺参数(光束输出功率、扫描速度、光斑大小等)使板料的弯曲角度最大.而且通过合理控制光斑的能量密度,可以显著改善变形区材料的组织和性能.     

Genetic algorithm-based hysteresis modeling and identification of rotary SMA actuators

This paper describes a new, modified generalized Preisach model for actuators that have severe dead-zone hysteresis, which is mainly observed in rotary SMA actuators. Along with the Preisach model, a new approach of hysteresis modeling and parameter identification using genetic algorithm was proposed. This modeling method achieved significant improvements in both accuracy and computation time. The proposed approach is general; therefore, it can be applied to identify any type of hysteresis. To demonstrate the efficiency of the proposed model, experimental results on hysteresis identification of Rotary SMA Actuator and performance of inverse hysteresis openloop controller are provided and compared.     

高压配电室(有充油设备)建筑设计

结合某矿山有充油设备的高压配电室建筑设计,对其建筑的屋面、墙体、承重结构、防火分区等设计的心得和体会。     

表面等离激元应用研究新进展

表面等离激元(SPP)是一种特殊的电磁模式,由于其具有的特殊性质,SPP被广泛用于许多前沿技术领域。综述了SPP在提高薄膜太阳能电池的转化效率,增加光学透镜分辨率,增强生物传感器灵敏度方面的研究新进展。     

建筑施工安全管理探究

伴随着建筑业市场的繁荣,建筑业给施工本身带来相应的问题。建筑施工安全的管理就是建筑业面临的问题,建筑施工的安全是建筑施工有效顺利进行的前提和保障,充分体现了管理者的能力。本文将就建筑施工安全管理进行探究,提出浅见。     

Effect of natural aging on microstructure and mechanical properties of friction stir welded 7050-T7451 joints

The microstructure and mechanical properties of friction stir welded 2.5 mm 7050-77451 aluminum alloy natural aging 72 h and 17 520 h were investigated,respectively.The uniaxial tensile test showed that yield strength,tensile strength and elongation of the joints 17 520 h natural aging were about 20%,12%and 24%higher than those joints natural aging72 h.Hardness profile of natural aging 17 520 h joint witnessed significant enhancement in nugget zone,compared with 72 h natural aging.Differential scanning calorimetry(DSC) and transmission electron microscopy(TEM) test revealed that more Guinier-Preston zone,η' and η phase emerged in nugget zone as natural aging duration increased,high density of dislocation located within grain boundary in nugget zone of joints natural aging 72 h.It is concluded that natural aging was feasible to enhance strength and plasticity of FSW joints simultaneously.