低阶煤热萃取物与瘦煤共炭化焦炭的微观结构及显微强度研究

以众唯瘦煤作为主炼焦煤,大同长焰煤萃取物作为添加剂,进行共炭化处理制备坩埚焦。利用偏光显微镜法定量研究焦炭光学显微组分,获得焦炭的各向异性指数(DRAS);采用XRD及分峰拟合的方法研究了焦炭的微晶粒径(L_c)、芳香缩合度(I_a)、石墨化度(g);利用Raman光谱结合分峰拟合的方法研究了焦炭中理想石墨微晶含量(I_g)。对所得焦炭的光学显微组分进行定量分析发现:大同长焰煤热解萃取产物的添加对共炭化焦炭的光学显微组分有显著的影响,利用偏光显微镜法计算出焦炭的DRAS与XRD和Raman计算的焦炭微晶参数呈现很好一致性。并且,焦炭的显微强度与其微观结构关联性极大。     

掺镧锆锡钛酸铅陶瓷极化强度变化量对电子发射电流强度的影响

铁电阴极因其优异的电子发射性能在高功率微波管的电子束源、平板显示技术以及宇航推进器等领域 有着广阔应用前景而日益受到人们的重视.大量研究表明,铁电阴极电子发射性能受阴极材料性能的影响. 在激励电场作用下,铁电阴极材料会产生表面非屏蔽电荷而引起极化强度的变化, 这表明铁电阴极电子发射性能可能与阴极材料的极化强度变化量存在着某种关系. 为研究阴极材料极化强度变化量对铁电阴极电子发射性能的影响,以掺镧锆锡钛酸铅铁电和反铁电陶瓷样品 作为阴极材料,通过正半周电滞回线测试得到阴极材料在不同电场强度下的极化强度变化量, 测量得到电子发射电流强度随激励电场的变化曲线,并分析了电子发射电流强度与极化强度变化量的关系. 结果表明,两种样品电子发射电流强度与极化强度变化量正相关.     

二面体群的Grothendieck环结构

二面体群的表示范畴为对称半单monoidal范畴,因而其Grothendieck环为有限多个元素生成的交换环.本文确定了该Grothendieck环的极小生成元,并且进一步证明了该Grothendieck环与某一多项式环的商环同构.     

二面体群的Grothendieck环结构

二面体群的表示范畴为对称半单monoidal范畴,因而其Grothendieck环为有限多个元素生成的交换环.本文确定了该Grothendieck环的极小生成元,并且进一步证明了该Grothendieck环与某一多项式环的商环同构.     

Rotational manipulation of massive particles in a 2D acoustofluidic chamber constituted by multiple nonlinear vibration sources

Rotational manipulation of massive particles and biological samples is essential for the development of miniaturized lab-on-a-chip platforms in the fields of chemical, medical, and biological applications. In this paper, a device concept of a two-dimensional acoustofluidic chamber actuated by multiple nonlinear vibration sources is proposed. The functional chamber enables the generation of acoustic streaming vortices for potential applications that include strong mixing of multi-phase flows and rotational manipulation of micro-/nano-scale objects without any rotating component. Using numerical simulations, we find that diversified acoustofluidic fields can be generated in the chamber under various actuations, and massive polystyrene beads inside can experience different acoustophoretic motions under the combined effect of an acoustic radiation force and acoustic streaming. Moreover, we investigate and clarify the effects of structural design on modulation of the acoustofluidic fields in the chamber. We believe the presented study could not only provide a promising potential tool for rotational acoustofluidic manipulation, but could also bring this community some useful design insights into the achievement of desired acoustofluidic fields for assorted microfluidic applications.