共查询到19条相似文献,搜索用时 125 毫秒
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近年来,对磁振子晶体的研究已成为热点,与光子晶体等复合材料的性质类似,磁振子晶体也有带隙现象出现,频率在带隙范围内的自旋波在磁振子晶体内将被禁止传播。由此磁振子晶体有望能够被应用于广泛的仪器制造中。本文采用平面波展开法数值计算了分别由铁与钴、铁与氧化铀、钴与氧化铀材料构成的一维无限大各向同性的磁振子晶体的带结构,讨论了不同的填充率对磁振子晶体带隙结构的影响。计算结果表明,交换作用场对自旋波带宽的影响很明显。 相似文献
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超声波清洗技术的研究与应用现状 总被引:9,自引:1,他引:8
综述了超声波清洗的研究与应用现状,重点分析了超声清洗机理、换能器理论和各种因素对超声清洗的影响的研究进展;介绍了超声波清洗的有关应用及最新发展,指出传统的超声波清洗的由于在多方面具有一定的优势而在广泛的领域中得到更深入的应用.通过对超声波清洗应用的新发展--高频超声清洗、碳氢真空清洗等应用的介绍,进一步指出超声波清洗在正朝着复合、环保、高效和自动化的方向发展. 相似文献
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分析了钢带清洗的目的、常用的清洗方法,介绍了变幅杆超声波聚能器的原理,着重阐述了聚能式钢带清洗机的整机结构,工艺流程,技术参数以及客户化设计等方面的内容,最后总结了聚能式连续型钢带清洗机优点和应用趋势. 相似文献
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《分离科学与技术》2012,47(16):3569-3584
Abstract Homogeneous alumina membranes fouled by polystyrene latex particles at different pH values and ionic strengths were subjected to ultrasonic cleaning. Cleaning was more effective at high and low pH than at neutral pH. At low pH values, less repulsive particle‐particle interactions resulted in the removal of millimeter‐scale aggregates and highly effective cleaning. At near‐neutral pH, stronger repulsive particle‐particle interactions caused detachment to occur as individual particles from the cake layer rather than as flocs, which was a slightly less effective cleaning mechanism. Ultrasonic cleaning of cake layers formed at high ionic strength (>0.3 M KCl) was less effective than cleaning at lower ionic strength (<0.3 M KCl). High ionic strength caused particles to coagulate in solution and deposit as flocs on the membrane surface forming a highly permeable fouling layer. This fouling layer was resistant to ultrasound at the sub‐optimal cleaning conditions used in this study, perhaps due to particle attachment occurring within a primary energy minimum. Membrane cleaning experiments performed with particles of varying size showed that particle size was less important than the surface potential of the particles. For a given mass, particles that possessed the largest surface potential formed the thickest fouling layer, irrespective of particle size, and showed the greatest improvement in flux with ultrasonic cleaning. These results demonstrate that solution conditions influence ultrasonic cleaning of membranes primarily by modifying particle‐particle and particle‐membrane interactions as well as cake layer structure, rather than by impacting the extent or magnitude of cavitation events. 相似文献