Step Structure in Cold-Rolled Deformed Nanocrystalline Nickel

The microstructure characteristic of the cold-rolled deformed nanocrystalline nickel metal is studied by transmission electron microscopy. The results show that there are step structures nearby the grain boundary （CB）, and the contrast of stress field in front of the step corresponds to the step in the shape. It is indicated that the interaction between twins and dislocations is not a necessary condition to realizing the deformation. In the later stage of the deformation when the grain size becomes about lOOnm, the deformation can depend upon the moving of the boundary of the stack faults （SFs） which result from the partial dislocations emitted from CBs. However, when the size of SFs grows up, the local internal stress which is in front of the step gradually becomes higher. When this stress reaches a critical value which stops the gliding of the partial dislocations, the SFs will stop to grow up and leave a step structure behind.     

Sb有序单晶纳米线阵列的制备

采用直流电沉积的方法在氧化铝模板（AAM）中成功地制备了Sb单晶纳米线阵列. X射线衍射（XRD）证明所制得的纳米线阵列为(110)取向的六方相Sb.透射电镜（TEM）显示Sb纳米线平滑而均匀,直径40～50 nm,长径比大于1000.选区电子衍射（SAED）结果表明,所制得的纳米丝为Sb单晶丝.场发射扫描电镜（FE-SEM）显示Sb纳米线阵列规则,填充率接近100％.     

稀疏低秩噪声模型下无监督实时单通道语音增强算法

针对现有基于字典学习的增强算法需要先验信息、不易实时处理的问题,提出一种便于实时处理的无监督的单通道语音增强算法。首先,该算法将无监督条件下背景噪声的建模问题转化为带噪语音幅度谱的稀疏低秩噪声分解;然后,采用增量非负子空间方法对背景噪声进行在线字典学习,获得能够体现背景噪声时变特性的自适应噪声字典;最后,利用所得的噪声字典,采用易于实时处理的逐帧迭代方式,对带噪语音进行处理。实验结果表明:相较于多带谱减法和基于低秩稀疏矩阵分解的增强算法,所提算法在噪声抑制方面的性能尤为显著,在多项性能评价指标上,均表现出更好的结果。      

Fe48Co52 Alloy Nanowire Arrays: Effects of Magnetic Field Annealing

详细研究了磁场退火对于具有不同线间距(30～60 nm)和不同线直径(22～46 nm)的Fe48Co52合金纳米线阵列性能的影响．研究表明,退火过程中沿纳米线方向施加3kOe的磁场对于阵列的最佳退火温度和晶体结构以及线直径较小或线间距较大阵列的磁性能均无明显影响．但是对于具有较大线直径或较小线间距的阵列,这种磁场退火处理限制了其易磁化方向的转动并明显提高了其矫顽力与矩形度．认为不同阵列内部有效各向异性场强度之间所存在的差异是导致磁场退火后阵列磁性能出现不同变化的主要原因．