新型有机/无机聚合物网络的合成与二阶非线性光学

合成了含双官能团的生色团4’-(N,N-二羟乙基)氨基-4-硝基偶氮苯(DR19),采用溶胶-凝胶方法,通过"两端"交联设计合成了光学性能良好的二阶非线性新型有机/无机复合聚合物网络.经过极化交联后,其在室温和较高温度下均具有良好的二次谐波产生(SHG)稳定性,表明该交联聚合体系能形成致密的硅-氧网络,从而有效地抑制生色团分子的取向松弛.     

6,7,8,9-四氢-吩嗪并[2,3]C_(60)衍生物的结构、电子光谱和二阶非线性光学性质的理论研究

利用半经验AM1量子化学方法研究了6, 7, 8, 9-四氢-吩嗪并[2, 3]C60衍生物(1～4)及其异构体5, 6, 7, 8-四氢-9, 10-二氮杂蒽并[2, 3]C60衍生物 (5～8) 的结构。 结果表明,目标分子的前线轨道主要由C60部分决定, C60母体与加成基团之间存在较强的分子内电荷转移, C60部分是电子受体,吩嗪环部分为电子给体。 在AM1优化几何构型的基础上, 用INDO/SCI方法计算了目标分子的电子光谱, 用完全态求和(SOS)公式计算了其二阶非线性光学性质。 计算结果表明, 目标分子在400 nm 以上均存在弱吸收峰, 与实验所得结果一致。 5, 6, 7, 8-四氢-9, 10-二氮杂蒽并[2, 3]C60衍生物(5～8)的二阶非线性光学系数(0)比其异构体6, 7, 8, 9-四氢-吩嗪并[2, 3]C60衍生物(1～4)的大得多。     

基于二阶池化网络的鲁棒视觉跟踪算法

针对低分辨率、遮挡以及相似物体干扰等复杂场景下目标易丢失的问题,本文提出了基于二阶池化网络的视觉跟踪算法.已有的方法大多采用一阶池化网络,使得对低分辨目标和相似目标间的区分性不足.对此,本文首先在VGG16网络结构的基础上,将网络最后的一阶池化层替换为二阶协方差池化层,接着在ImageNet和CUB200-2011数据集上对网络进行重新训练.在跟踪阶段,为了减少运算负担,仅提取预训练网络的第四层卷积特征作为目标的外观表征.最后将提取的特征与已有的相关滤波算法进行结合.实验结果表明,本文算法在跟踪精度和成功率上均取得了优异的性能表现.     

Cluster consensus of second-order multi-agent systems via pinning control

This paper investigates the cluster consensus problem for second-order multi-agent systems by applying the pinning control method to a small collection of the agents.Consensus is attained independently for different agent clusters according to the community structure generated by the group partition of the underlying graph and sufficient conditions for both cluster and general consensus are obtained by using results from algebraic graph theory and the LaSalle Invariance Principle.Finally,some simple simulations are presented to illustrate the technique.     

基于绝对关联度的图像目标边缘提取方法

针对传统边缘检测方法对光学经纬仪实际拍摄的含噪声图像边缘检测效果不理想的问题,将灰色系统理论引入图像边缘检测,通过绝对关联分析与边缘检测算子相结合,提出一种利用二阶微分算子作为参考序列,图像像素作为比较序列,通过计算灰色绝对关联度来检测图像边缘的方法。实验结果表明,该方法与现有方法相比,边缘检测效果更好,检测的边缘清晰、连续,对噪声图像边缘的检测精度较高,抗噪声能力强。     

分析非均匀填充圆柱介质谐振器的二阶精度FDTD公式

从积分形式的Maxwell方程出发，利用连续函数的Taylor级数展开，严格地给出了包含介质交界面的二阶精度时域有限差分(FDTD)公式，解决了以往FDTD法处理非均匀介质填充区域问题时只有一阶精度的问题。分析表明，为了获得二阶精度，除了需要引入适当等效介电常数外，还必须采用适当非均匀网格。该方法被用于轴对称圆柱介质谐振器的分析。计算结果与理论值吻合良好，计算精度比传统的FDTD方法提高了一个数量级以上。     

Second-order sufficient optimality conditions for local and global nonlinear programming

This paper presents a new approach to the sufficient conditions of nonlinear programming. Main result is a sufficient condition for the global optimality of a Kuhn-Tucker point. This condition can be verified constructively, using a novel convexity test based on interval analysis, and is guaranteed to prove global optimality of strong local minimizers for sufficiently narrow bounds. Hence it is expected to be a useful tool within branch and bound algorithms for global optimization.     

Low-gain adaptive stabilization of infinite-dimensional second-order systems

In this paper, low-gain adaptive stabilization of infinite-dimensional undamped second-order systems is considered in the case where the input and output operators are collocated. The systems have an infinite number of poles and zeros on the imaginary axis. The adaptive stabilizer is constructed by a low-gain adaptive PI controller (proportional plus integral controller). An energy-like function and a multiplier function are introduced and low-gain adaptive stabilization of the linear second-order systems is analyzed.     

Analysis of general second-order fluid flow in double cylinder rheometer

The fractional calculus approach in the constitutive relationship model of second-order fluid is introduced and the flow characteristics of the viscoelastic fluid in double cylinder rheometer are studied. First, the analytical solution of which the derivative order is 1/2 is derived with the analytical solution and the reliability of Laplace numerical inversion based on Crump algorithm for the problem is verified, then the characteristics of second-order fluid flow in the rheometer by using Crump method is analyzed. The results indicate that the more obvious the viscoelastic properties of fluid are, the more sensitive the dependence of velocity and stress on fractional derivative order is.     

Local Saddle Points and Convexification for Nonconvex Optimization Problems

Recently, Li (Ref. 1) obtained a saddle-point result for a general class of nonconvex optimization problems with inequality constraints, by using a transformation equivalent to taking the pth power of the objective function and the constraints, under several conditions. In this paper, we show that, by an equivalent transformation, using the pth power of the constraints or using the pth power of the objective function and the constraints, the same result can be obtained under much weaker and reasonable conditions. Also, our results can be extended to the problem in which equality and inequality constraints are involved.