金属平板覆盖负折射率媒质的电磁波反射系数的PLRC-FDTD分析

 推导了负折射率媒质中的FDTD分段线性递归卷积(PLRC)计算式,并将PLRC-FDTD方法用于仿真电磁波与负折射率媒质的相互作用, 计算了金属平板覆盖负折射率媒质层对垂直入射电磁波的反射系数。数值结果表明：负折射率媒质包层可以极大地减少目标的电磁回波能量,碰撞频率越大,振荡频率越小,其吸波性能越好;负折射率媒质碰撞频率、振荡频率及其分布形式是影响反射系数的重要因素。     

Formulas to Solve the （2＋1）—Dimensional System：The （2＋1）—Extension of Classical Boussinesq System

We deal with the (2 1)-extension of classical Boussinesq system,which can reduce to several meaningful (1 1)-dimensional systems.By studying its lax paire,we put forward invariances of Lax pair at first,then a recursion formula depending on an arbitrary function is derived,At last,some solutions of the (2 1)-extension of classical Boussinesq system are digged out by using the formula.     

基于Polyak步长的随机递归梯度算法

针对机器学习中一类有限光滑凸函数和的最小化问题,将随机递归梯度算法和Polyak步长结合,提出基于Polyak步长的随机递归梯度算法(SARAH-Polyak).分别在强凸和一般凸条件下证明了算法的线性收敛性.实验结果表明SARAH-Polyak算法的有效性.     

Recursion Operators of Two Supersymmetric Equations

From Lax representations, recursion operators for the supersymmetric KdV and the supersymmetric Kaup-Kupershimdt (SKK) equations are proposed explicitly. Under some special conditions, the recursion operator of the supersymmetricSawada-Kotera equation can be recovered by the one of the SKK equation.     

基于SCI/ERA方法的高效气动力降阶模型

由正交Walsh函数构造Walsh-单信号-复合-输入,对其作用下的计算流体力学响应采用单信号-复合-输入/特征系统实现算法SCI/ERA(Single-Composite-Input/Eigensystem Realization Algorithm)辨识得到离散时间非定常气动力状态空间降阶模型。通过对Isogai机翼剖面气动弹性算例的计算证明该方法具有和非定常计算流体力学方法相当的精度同时模型维数降低2个数量级;在模型构造时间上,SCI/ERA方法比脉冲/ERA方法计算效率提高24%,同时内存占用减小34%;由理论分析可知当耦合结构模态数目增加时,SCI/ERA方法所需的计算开销增幅远小于脉冲/ERA方法;采用频域平衡特征正交分解BPOD(Balanced Proper Orthogonal Decomposition)方法可以准确地从降阶模型中提取出一个低频二次降阶模型,同时保持与原模型相当的精度。二次降阶后模型维数进一步减小88%。     

Hamiltonian System of New Nonlinear Lattice Equations

A 3-dimensional Lie algebra sμ（3） is obtained with the help of the known Lie algebra. Based on the sμ（3）, a new discrete 3 × 3 matrix spectral problem with three potentials is constructed. In virtue of discrete zero curvature equations, a new matrix Lax representation for the hierarchy of the discrete lattice soliton equations is acquired. It is shown that the hierarchy possesses a Hamiltonian operator and a hereditary recursion operator, which implies that there exist infinitely many common commuting symmetries and infinitely many common commuting conserved functionals.     

Analysis and implementation of a new hyperchaotic system

Based on a modified Lorenz system, a relatively simple four-dimensional continuous autonomous hyperchaotic system is proposed by introducing a state feedback controller. The system consists of four coupled first-order ordinary differential equations with three nonlinear cross-product terms. Some dynamical properties of this hyperchaotic system, including equlibria, stability, Lyapunov exponent spectrum and bifurcation, are analysed in detail. Moreover, an electronic circuit diagram is designed for demonstrating the existence of the hyperchaos, and verifying computer simulation results.     

复合结构60A电流型WEDM脉冲电源设计与实现

本文提出了一种电流型WEDM脉冲电源的设计方案,其具有较大的脉冲峰值电流,并便于调整,能够实现窄脉宽．脉冲频率高,只输出单向矩形脉冲,脉冲波形的前沿和后沿陡直,脉冲参数能在较宽的范围内可调,既保持了逆变式电源的优点,又具备了独立式脉冲电源相近的加工性能．     

一种可伸缩的支持向量机的硬件实现方法

提出了支持向量机（Support Vector Machine）学习过程硬件实现的一种新的数字电路结构,它可以在保证向量机学习速度的同时,提高支持向量机的硬件资源利用效率;此外基于此结构的支持向量学习机还可以适用于低于设计数的样本集．由于该设计的灵活性以及其对硬件要求的减小,使得支持向量学习机可以更好、更方便地应用于嵌入式系统中．     

Barnsley-Elton-Hardin的一个定理的修正

Ｂａｒｎｓｌｅｙ等在关联矩阵不可约的条件下,得到了递归ＦＩＦ的分形维数公式。本文首先指出该九公式是错误的,然后给出新的维数公式,并且新维数公式没有关联矩阵为不可约的限制条件。