红黑排序混合算法收敛速度分析

The algorithm of applying the block Gauss elimination to the Red-Black or-dering matrix to reduce the order of the system then solve the reduced system byiterative methods is called Hybrid Red-Black Ordering algorithm.In this paper,we discuss the convergence rate of the hybrid methods combined with JACOBI,CG,GMRES(m).Theoretical analysis shows that without preconditioner thesethree hybrid methods converge about 2 times as fast as the corresponding natural ordering methods.For the case that all the eigenvalues is near the real axis, the GMRES(m) algorithm converges about 3 times faster than the natural ordering GMRES(m).Various numerical experiments are presented.For large scale prob-lem with preconditioners, numerical experiments show that the GMRES(m) hybrid methods converge from about 3 times to even 5 times as fast as the natural order-ing methods and the computing time is reduced to about 1/3 even 1/6 of that of the natural ordering methods.     

混沌经济学——混沌与分形

本文给出作为混沌经济学的数学基础的混沌与分形的简短介绍 .     

An infinite-time relaxation theorem for differential inclusions

The fundamental relaxation result for Lipschitz differential inclusions is the Filippov-Wazewski Relaxation Theorem, which provides approximations of trajectories of a relaxed inclusion on finite intervals. A complementary result is presented, which provides approximations on infinite intervals, but does not guarantee that the approximation and the reference trajectory satisfy the same initial condition.

     

A （2, 3） quantum threshold scheme based on Greenberger-Horne-Zeilinger state

In this paper, by using properties of quantum controlled-not manipulation and entanglement states, we have designed a novel (2, 3) quantum threshold scheme based on the Greenberger- Horne -Zeilinger (GHZ) state. The proposed scheme involves two phases, i.e. a secret sharing phase and a secret phase. Detailed proofs show that the proposed scheme is of unconditional security. Since the secret is shared among three participants, the proposed scheme may be applied to quantum key distribution and secret sharing.     

Isotropic ferromagnetic resonance field shift in as-prepared permalloy/FeMn bilayers

Exchange-coupled wedged-permalloy (Py)/FeMn bilayers are studied by ferromagnetic resonance (FMR) technique at room temperature. In comparison, Py single layer films were also made. For Py single layer films and Py/FeMn bilayers, only one uniform resonance peak was observed at high magnetic fields, indicating no interfacial diffusion at the Py/FeMn and Py/Cu interfaces. Negative isotropic in-plane resonance field does exist in Py/FeMn bilayers and its magnitude increases with decreasing Py layer thickness. In order to explain above phenomena, interfacial perpendicular anisotropy must be considered simultaneously, in addition to irreversible rotation of spins in FeMn layers. This is because the perpendicular resonance field of the bilayers is larger than that of Py single layer films.     

Adaptive control of bifurcation and chaos in a time-delayed system

In this paper, the stabilization of a continuous time-delayed system is considered. To control the bifurcation and chaos in a time-delayed system, a parameter perturbation control and a hybrid control are proposed. Then, to ensure the asymptotic stability of the system in the presence of unexpected system parameter changes, the adaptive control idea is introduced, i.e., the perturbation control parameter and the hybrid control parameter are automatically tuned according to the adaptation laws, respectively. The adaptation algorithms are constructed based on the Lyapunov-Krasovskii stability theorem. The adaptive parameter perturbation control and the adaptive hybrid control methods improve the corresponding constant control methods. They have the advantages of increased stability, adaptability to the changes of the system parameters, control cost saving, and simplicity. Numerical simulations for a well-known chaotic time-delayed system are performed to demonstrate the feasibility and superiority of the proposed control methods. Besides, comparison of the two adaptive control methods are made in an experimental study.     

时间延迟积分型面阵CMOS图像传感器MTF速度失配模型研究

研究了时间延迟积分型面阵互补金属氧化物半导体(CMOS)图像传感器调制传递函数(MTF)速度失配特性,在分析累加级数、像素尺寸、镜头放大倍数、行周期及电机运动速度失配等影响因素的基础上,建立了MTF速度失配模型。基于现场可编程门阵列(FPGA)开发板,搭建面阵CMOS图像传感器实现线阵时间延时积分(TDI)的CMOS测试系统。实验结果表明,在光强为3lx,速度失配M(ΔV/V)<2,8级时间延迟积分与面阵成像相比,MTF值提高50%;当累加级数为8级,速度失配满足M(ΔV/V)=2的速度失配容限时,奈奎斯特频率处的MTF值下降10%,当速度失配达到M(ΔV/V)=10时,MTF值下降35%。     

Zr4Al2高压下热动力学性质的第一性原理研究

本文主要通过平面波赝势密度泛函理论的第一性原理计算方法,采用了广义梯度近似（GGA）交换相关函数,研究了六角结构的Zr4Al2的EOS态方程和热动力学性质。通过采用了声子效应的准谐近似德拜模型,我们成功得到了晶胞体积V随温度以及V/V0、德拜温度Θ、热熔CV 随压强P的变化关系。另外,我们还研究了热膨胀系数α及格林参数γ随温度和压强的变化关系,计算结果表明格林参数和热膨胀系数随温度的升高而增加,但是在较高的温度下,热膨胀系数几乎不受温度的影响。     

Temperature dependent exchange bias effect in polycrystalline BiFeO3/FM (FM = NiFe, Co) bilayers

Extensive studies on the temperature (T) dependent exchange bias effect were carried out in polycrystalline BiFeO₃(BFO)/NiFe and BFO/Co bilayers. In contrast to single-crystalline BFO/ferromagnet (FM) bilayers, sharp increase of the exchange bias field (H _E ) below 50 K were clearly observed in both of these two bilayers. However, when T is higher than 50 K, H _E increases with T and decreases further when T is larger than 230 K (for BFO/NiFe) or 200 K (for BFO/Co), which is similar to those reported in single-crystalline BFO/FM bilayers. After the exploration of magnetic field cooling, the temperature dependent exchange bias can be explained considering two contributions from both the interfacial spin-glass-like frustrated spins and the polycrystalline grains in the BFO layer. Moreover, obvious exchange bias training effect can be observed at both 5 K and room temperature and the corresponding results can be well fitted based on a recently proposed theoretical model taking into account the energy dissipation of the AFM layer.     

Blocked-micropores,surface functionalized,bio-compatible and silica-coated iron oxide nanocomposites as advanced MRI contrast agent

Quasi-critical fluctuations occur close to critical points or close to continuous phase transitions. In three-dimensional systems, precision tuning is required to access the fluctuation regime. Lowering the dimensionality enhances the parameter space for quasi-critical fluctuations considerably. This enables one to make use of novel properties emerging in fluctuating systems, such as giant susceptibilities, Casimir forces or novel quasi-particle interactions. Examples are discussed ranging from simple metal–adsorbate systems to unconventional superconductivity in iron-based superconductors.