Onset velocity of circulating fluidization and particle residence time distribution: A CFD–DEM study

Until now, the onset velocity of circulating fluidization in liquid–solid fluidized beds has been defined by the turning point of the time required to empty a bed of particles as a function of the superficial liquid velocity, and is reported to be only dependent on the liquid and particle properties. This study presents a new approach to calculate the onset velocity using CFD–DEM simulation of the particle residence time distribution (RTD). The onset velocity is identified from the intersection of the fitted lines of the particle mean residence time as a function of superficial liquid velocity. Our results are in reasonable agreement with experimental data. The simulation indicates that the onset velocity is influenced by the density and size of particles and weakly affected by riser height and diameter. A power-law function is proposed to correlate the mean particle residence time with the superficial liquid velocity. The collisional parameters have a minor effect on the mean residence time of particles and the onset velocity, but influence the particle RTD, showing some humps and trailing. The particle RTD is found to be related to the particle trajectories, which may indicate the complex flow structure and underlying mechanisms of the particle RTD.     

纤维素共混型液晶的光学性能与结构

利用紫外-可见分光光度计, X射线衍射仪与偏光显微镜研究了乙基纤维素(EC)与羟丙基纤维素(HPC)共混型胆甾液晶. 研究发现: 质量百分浓度相同时, 共混纤维素胆甾型液晶的最大反射波长与螺距随着共混物中HPC含量的增加而增大. XRD实验结果表明共混型纤维素液晶螺距增大与液晶体系中分子层间的距离增大相关. 可以利用该现象来调控纤维素胆甾型液晶的光学性能与螺距.     

拓扑量子方法及其在含C＝O和N＝O化合物性能估算中的应用

综合量子化学与拓扑化学知识, 提出了构建Y＝O (Y表示C, N)键拓扑量子键邻接矩阵的方法. 利用该矩阵特征根和量子化学原理, 计算了表征分子轨道能量、原子电荷和键级等的拓扑量子参数. 将这些参数对含C＝O, N＝O基团的有机分子的紫外吸收能量、红外伸缩振动频率和醛酮C＝O上的亲核加成反应速率等性质进行定量结构-性质相关, 得到的模型均具有良好的估算能力.     

遥感图像土地利用/覆盖多光谱特征分布空间距离分析方法

研究遥感图像多光谱特征分布是设计分类算法的关键。针对土地利用/覆盖类别由多种地物组成,难以求取多元分布模型分析类别多光谱特征的问题,提出了一种遥感图像土地利用/覆盖多光谱特征分布空间距离分析方法,以样品均值矢量作为类别中心,用最大最小法聚类形成类别多聚类中心,计算各聚类中心与类别中心的空间距离,以距离为横坐标、聚类中心含有的像元数占样品总数的百分比为纵坐标作图,形成内类、类间空间距离分布曲线分析遥感图像土地利用/覆盖类别多光谱特征。分类实验结果与空间距离分析结论吻合,说明空间距离分析方法可行。该方法利用空间距离把多维光谱分布转化为一维距离分布,计算简单,聚类门限值易于确定,多光谱分布特征清晰,较好地解决了多光谱特征的多元分布问题。     

Scheme for Implementing Quantum Search Algorithm in a Cluster State Quantum Computer

Using cluster state and single qubit measurement one can perform the one-way quantum computation. Here we give a detailed scheme for realizing a modified Grover search algorithm using measurements on cluster state. We give the measurement pattern for the cluster-state realization of the algorithm and estimated the number of measurement needed for its implementation. It is found that O（2^3n/^2n^2） number of single qubit measurements is required for its realization in a cluster-state quantum computer.     

Scheme for Implementing Perfect Quantum Teleportation with Non-maximally Entangled W-Class State in Cavity QED

We propose an experimentally feasible teleportation scheme with three-atom W-class state, which was first proposed by Agrawal and Pati [P. Agrawal and A. Pati, Phys. Rev. A 74 (2006) 062320], in cavity QED. In this scheme atoms interact simultaneously with a nonresonant cavity and there is no energy exchange between the atoms and the cavity. Thus it is insensitive to the cavity decay, which is of importance in view of experiment.     

卤代甲烷的键离解能与取代基效应

将芳环上取代基的电子效应参数引入卤代甲烷, 以卤代甲烷分子Y-CH_nX_{3－n (n＝0～3; Y＝H, F, Cl, Br, I; X＝F, Cl, Br, I)中Y-C键的标准键焓 与中心C原子相键连原子的场/诱导效应之和ΣFi、共轭效应之和ΣRi以及诱导偶极之和Σ(α×F)为参数, 建立了一个定量估算卤代甲烷分子中Y-C键离解能(BDE)的通用模型, BDE(Y-C)＝57.5460＋0.8855 －101.0780ΣRi－64.8390ΣFi－10.1034Σ(α×F). 对35个C-H, C-F, C-Cl, C-Br和C-I键回归分析结果表明, 估算Y-C键离解能的精度在实验误差范围内. 对外部数据集的预测结果表明, 该模型具有较高的预测精度, 可用于预测还没被实验测定的卤甲烷中Y-C键离解能. 还对卤代甲烷中104个C-Y键的键离解能进行了预测. 将芳环上取代基效应用于研究饱和体系化学键性能, 有利于深入理解取代基效应对化学键性能的影响.}     

单烯烃分子结构有限元方法及定量结构-沸点相关性研究

按照有限元方法, 将烯烃分子中的“C—C”单键和“C＝C”双键当作两种不同的线性杆元处理, 构建单烯烃分子的刚度矩阵, 连同质量矩阵求解相应的特征方程, 得到单烯烃分子的结构特征参量——固有频率, 将其用于定量结构-沸点预测模型, 对150个单烯烃分子的沸点实验测定值进行多元回归分析, 结果表明, 单烯烃分子结构与沸点性质间存在高相关性, 说明该方法是合理可行的.     

Analysis of the injection layer of PTCDA in OLEDs using x-ray photoemission spectroscopy and atomic force microscopy

Through the investigation of the sample surface and interface of 3, 4, 9, 10-perylenetetracarboxylic dianhydride (PTCDA)/indium-tin-oxide (ITO) thin films using atomic force microscopy, it has been found that the surface is complanate, the growth is uniform and the defects cover basically the surface of ITO. Furthermore, the number of pinholes is small. The analysis of the sample surface and interface further verifies this result by using x-ray photoemission spectroscopy . At the same time, PTCDA is found to have the ability of restraining the diffusion of chemical constituents from ITO to the hole transport layer, which is beneficial to the improvement of the performance and the useful lifetime of the organic light emitting diodes (OLEDs).     

Robust fuzzy control for chaotic dynamics in Lorenz systems with uncertainties

This paper deals with the robust fuzzy control for chaotic systems in the presence of parametric uncertainties. An uncertain Takagi--Sugeno fuzzy model for a Lorenz chaotic system is first constructed. Then a robust fuzzy state feedback control scheme ensures the control for stable operations under bounded parametric uncertainties. For a chaotic system with known uncertainty bounds, a robust fuzzy regulator is designed by choosing the control parameters satisfying the linear matrix inequality. To verify the validity and effectiveness of the proposed controller design method, an analysis technique is suggested and applied to the control of an uncertain Lorenz chaotic system.