流态化模拟:基于介尺度结构的多尺度CFD

介尺度结构是研究气固流态化多尺度行为的关键。传统的基于平均化处理方式的双流体模拟不能准确描述流化床中的多尺度流动和传递行为。相较而言,基于能量最小多尺度(EMMS)方法的结构多流体模型(SFM)基于局部空间(网格)内的非均匀介尺度结构流动特征,其宏观预测结果与网格分辨率基本无关,因而可以大幅降低模拟计算量。基于SFM模拟得到的流动结构,EMMS多尺度传质模型进一步成功解释了传统传质文献中的数据差异。集成上述模型,形成了一整套模拟流化床流动-传递-反应耦合过程的多尺度计算流体力学(CFD)方法,并将其应用于预测循环流化床中典型的S型轴向分布、揭示噎塞转变的机理以及流化床放大困难的原因。多尺度CFD使工业规模循环床的三维、全系统、动态流动-反应耦合过程的准确模拟成为可能,并为实现从模拟向实时虚拟过程转变的目标打下基础。     

基于AFM的微纳米结构力学特性测量

原子力显微镜（ＡＦＭ）以其优异的特性不仅在微米、纳米的范围内获取图象。同时可以获取针尖与样品之间的作用力,为研究样品的力学性能提供了新思路。对ＡＦＭ在力学测量上的原理和应用进行了综述,并提出基于ＡＦＭ的生物样品的力学测量的新方法。     

基于广义周期性的单通道多分量正弦调频信号分离和参数估计

针对噪声条件下的单通道多分量正弦调频(SFM)信号,该文提出一种信号分离和参数提取方法。利用正弦调频信号的广义周期性进行奇异值分解,以求出分量信号的调制频率;通过离散点搜索,估计出分量信号的调频(FM)初始相位、调制指数及载频,并对这些估计值利用信赖域算法进行优化,减小误差;利用内积计算,估计分量信号的幅度和初始相位。此外,还利用自相关矩阵特征值分解估计混合信号的信噪比(SNR),并根据信噪比确定停止分解的阈值。在仿真与分析中,针对具体的信号详细说明了该方法的各步骤,并在不同信噪比条件下分析了该方法的参数估计精确度。     

基于场景图划分的无人机影像定位算法

针对大规模长序列无人机（UAV）影像定位中存在的速度慢、误差漂移等问题,结合UAV影像的特点,提出了一种基于场景图划分的UAV影像定位算法。首先,利用全球定位系统（GPS）辅助信息缩小特征匹配的空间搜索范围,从而加速同名点的提取;之后结合视觉一致性和空间一致性来构建场景图,并利用归一化割（Ncut）对其进行划分;接着,对各组场景图进行增量重建;最后,利用光束法平差（BA）融合场景图从而计算出场景的三维模型。此外,在BA阶段,所提算法对代价函数进行扩充,即加入了GPS空间约束信息。在四个UAV影像数据集上的实验结果表明,与COLMAP等多种运动恢复结构（SFM）算法相比,所提算法的定位速度提升了50%,重投影误差减小了41%,定位误差控制在0.5m之内。此外,通过有无GPS辅助下的算法的实验对比,可以得知引入相对和绝对GPS约束的BA有效解决了误差漂移问题,避免了出现歧义性结果,并且极大地减小了定位误差。     

Atomic force microscopy of freeze-fracture replicas of rat atrial tissue

Atomic force microscopy (AFM) has provided three-dimensional (3-D) surface images of many biological specimens at molecular resolution. In the absence of spectroscopic capability for AFM, it is often difficult to distinguish individual components if the specimen contains a population of mixed structures such as in a cellular membrane. In an effort to understand the AFM images better, a correlative study between AFM and the well-established technique of transmission electron microscopy (TEM) was performed. Freeze-fractured replicas of adult rat atrial tissue were examined by both TEM and AFM. The same replicas were analysed and the same details were identified, which allowed a critical comparison of surface topography by both techniques. AFM images of large-scale subcellular structures (nuclei, mitochondria, granules) correlated well with TEM images. AFM images of smaller features and surface textures appeared somewhat different from the TEM images. This presumably reflects the difference in the surface sensitivity of AFM versus TEM, as well as the nature of images in AFM (3-D surface contour) and TEM (2-D projection). AFM images also provided new information about the replica itself. Unlike TEM, it was possible to examine both sides of the replica with AFM; the resolution on one side was significantly greater compared with the other side. It was also possible to obtain quantitative height information which is not readily available with TEM.     

SNOM/SFM结合的近场光学探针

介绍了近年来近场光学探针技术的进展，特别是可与扫描力显徽镜结合的探针制备技术。     

Amine-cured epoxy surface morphology and interphase with copper: an approach employing electron beam lithography and scanning force microscopy

The interphase between polymer and metal was investigated for further understanding of the mechanical properties. In particular, an analysis of the stiffness can provide significant information to determine the stress distribution in the interphase. The polymer–metal interphase was prepared by applying epoxy on micrometer-scale copper structures, which were created by electron beam lithography (EBL). The stiffness was characterized by force modulation microscopy (FMM), which is a scanning force microscopy (SFM)-based technique. According to the analysis, a stiffness variation was observed in the interphase. It showed a lower stiffness in the interphase than in the bulk epoxy, which is far from the copper structures. In addition, the morphology of epoxy surface was studied. The nodules on the epoxy surface were characterized and the average length was found to be approx. 76 nm. FMM showed adequate sensitivity to visualize the nodules on the epoxy. Therefore, FMM can also be a very effective method to analyze epoxy morphology and the stiffness in the interphase along with the topography images.     

扫描静电力显微镜及其电荷捕获/释放技术

介绍扫描静电力显微测量及其用实现电荷捕获释放的技术现状，发展动向，以及关键技术的一些最新成果，前者已被广泛应用于测量半导体表面电荷密度分布，表面电势以及铁电材料铁电体结构的研究中，后者可望用于研制速度和存贮容量都比现在提高成千上万倍的量子器件。最后，本文探讨了基于微晶振的静电力显微测量的关键技术及其解决方案。     

Perturbation analysis of stochastic fluid models with respect to the fluid arrival process

The deployment of network applications (e.g., multimedia and other real time applications) has put extra pressure on network scarce resources (bandwidth and buffers) thus generating a need for effective resource allocation and management. In this paper we adopt a stochastic fluid model (SFM) framework and derive sensitivity estimators for three performance measures of interest (workload, throughput and loss volume) with respect to the fluid inflow process parameters. The motivation is to use the sensitivity estimators for dynamic control and optimisation of the systems performance. Subsequently these estimators are evaluated based on data observed from a single sample path of the discrete-event system and are used to dynamically control the input process to the system allowing the network to work continuously at an optimal or near optimal point. The proposed analysis naturally leads to a distributed algorithm for evaluating the propagation of perturbations in a network (e.g., due to changes in the buffer size of upstream nodes).     

基于无人机自标定的表面流场测量方法

针对无人机图像标定及配准等关键技术问题,提出了一种基于无人机自标定的表面流场测量方法。该方法基于运动恢复结构(SFM)三维重建技术完成无人机图像自标定,采用加速稳健特征变换(SURF)方法对无人机图像进行配准。将该方法应用于南京市三汊河河口闸下游表面流场测量,结果表明,基于SFM的三维重建精度可以满足自标定的要求,不需要另外设置地面控制点对无人机图像进行标定,简化无人机标定过程, SURF方法可有效地消除无人机位置飘移对表面流场测量结果的影响。