Site occupations and ordering behaviour of O phase in Ti2AlNb—based intermetallics

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热处理对Ag—15Al固溶体短程有序度的影响

研究了热处理对Ag-15Al(at％)固溶体合金电阻率和有序参数的影响,由X射线衍射分析表明,合金的短程序转变不是Ag_3Al化合物型的δ第二相的形成,而是α-Ag-Al固溶体原子的有序排列。     

Electronic structures of quasi-one-dimensional ferrimagnetic insulator Ca3Co2O6

The electronic structures of quasi-one-dimensional ferrimagnetic Ca₃Co₂O₆ are investigated using the generalized gradient approximation (GGA) as well as the GGA plus on-site Coulomb interaction (GGA+U) scheme. GGA+U calculations reveal that the interchain ferrimagnetic Ca₃Co₂O₆ is a Mott–Hubbard insulator rather than a metal given from GGA. In addition, we found an on-site U induced 3z²−r² orbital ordering on Co_pri sublattice which drives the intrachain ferromagnetic coupling along c-axis. Our findings suggest that strong electron-electron correlation plays an important role in Ca₃Co₂O₆.     

基于偏序关系的遗传算法求解多峰函数优化问题

该文设计了基于偏序关系的演化算法求解多峰函数优化问题新算法。并从偏序关系的性质出发,从理论上为该算法的收敛性提供了一定的依据,进而为其搜索操作提供了明确的方向,避免了演化搜索过程中的盲目性。     

含数量折扣的买-卖两方多商品联合定购改进模型

以定购次数必须为整数这一客观条件为前提,在Kohli和Park提出的含数量折扣的买-卖两方多商品联合定购模型基础上,构建了一个更真实、更科学的改进模型,分别对数量折扣策略下多商品单独定购和联合定购时两级供应链成本组成进行了分析,并求出两种定购情况各自所对应的最优每次定购数量;最后用模拟算例描述了改进模型的运算过程,并证明了联合定购相对于单独定购可以节约供应链总交易成本.     

遗传算法在OBDD变量排序中的应用

编序的二元判决图（ＯＢＤＤ）在电路测试和逻辑验证等方面具有广泛的应用。如何选取一个电路的变量顺序,使得所构造的ＯＢＤＤ最小,是等同于ＮＰＣ的问题。目前有多种寻找电路变量顺序的方法,但都具有一定程度的局限性,不能找到近似的最优解。     

Separable reversible data hiding in encrypted image based on pixel value ordering and additive homomorphism

This work proposes a separable reversible data hiding scheme in encrypted images based on pixel value ordering (PVO). After the original image is encrypted using homomorphism encryption by the content owner, the data hider embeds the secret data in encrypted domain. The PVO strategy realizes hiding data in each block. Additive homomorphism guarantees the performance of PVO in encrypted domain is close to that in plain domain. Besides, the homomorphism encryption does not cause data expansion, and the payload can be further improved. With the watermarked encrypted image, if the receiver has only the data hiding key, he can extract the additional data. If the receiver has only the encryption key, he can obtain a decrypted image similar to the original one. If the receiver has both the data hiding key and the encryption key, he can extract the additional data without any error and recover the original image losslessly.     

Stacking number dependence of size distribution of vertically stacked InAs/GaAs quantum dots

Vertically stacked layer structure is useful for controlling the size distribution of quantum dots. The dependence of the size distribution of quantum dots on the stacking numbers is theoretically and experimentally investigated. We show that the size distribution of quantum dots decreases with increasing the stacking number, and it occurs drastically when the stacking number is changed from 1 to 2. The quantitative analysis on in-plane strain energy distribution is also performed for the explanation.     

Self‐Assembly of Nanostructured,Complex, Multication Films via Spontaneous Phase Separation and Strain‐Driven Ordering

Spontaneous self‐assembly of a multication nanophase in another multication matrix phase is a promising bottom‐up approach to fabricate novel, nanocomposite structures for a range of applications. In an effort to understand the mechanisms for such self‐assembly, complimentary experimental and theoretical studies are reported to first understand and then control or guide the self‐assembly of insulating BaZrO₃ (BZO) nanodots within REBa₂Cu₃O_7–δ (RE = rare earth elements including Y, REBCO) superconducting films. The strain field developed around BZO nanodots embedded in the REBCO matrix is a key driving force dictating the self‐assembly of BZO nanodots along REBCO c‐axis. The size selection and spatial ordering of BZO self‐assembly are simulated using thermodynamic and kinetic models. The BZO self‐assembly is controllable by tuning the interphase strain field. REBCO superconducting films with BZO defect arrays self‐assembled to align in both vertical (REBCO c‐axis) and horizontal (REBCO ab‐planes) directions result in the maximized pinning and J_c performance for all field angles with smaller angular J_c anisotropy. The work has broad implications for the fabrication of controlled self‐assembled nanostructures for a range of applications via strain‐tuning.     

Characterization of LSMO/C60 spinterface by first-principle calculations

Spinterface between fullerene C₆₀ and La_{0 7}Sr_{0 3}MnO₃ (LSMO) was studied by means of density functional theory. Co-existence of many different configurations was shown, and probabilities of their appearance were estimated. Dependence of composite properties on configuration and temperature was also investigated. Key role of transition metal atoms in both binding between composite compartments and magnetic ordering in C₆₀ molecule was discussed. The latter was suggested to be responsible for spin-polarized charge transport while overall magnetic moment of fullerene molecule is relatively small.