Variable step-size affine projection algorithm based on global speech absence probability for adaptive feedbackcancellation简

A novel approach is proposed for improving adaptive feedback cancellation using a variable step-size affine projection algorithm（VSS-APA） based on global speech absence probability（GSAP）.The variable step-size of the proposed VSS-APA is adjusted according to the GSAP of the current frame.The weight vector of the adaptive filter is updated by the probability of the speech absence.The performance measure of acoustic feedback cancellation is evaluated using normalized misalignment.Experimental results demonstrate that the proposed approach has better performance than the normalized least mean square（NLMS） and the constant step-size affine projection algorithms.     

基于局部特征描述的目标定位

针对SURF不能满足实时性、BRISK匹配率低的特点,本文采用SURF检测关键点与BRISK计算描述子相结合的方法,提出一种新的特征描述方法SURF-BRISK。本文首先通过SURF-BRISK描述方法进行特征匹配,然后通过RANSAC去除误匹配,最后通过正确的匹配点对计算仿射变换的6个参数并进行目标定位。实验表明, SURF-BRISK特征描述方法不仅具有实时性和鲁棒性,而且在目标定位中取得了较好的结果。     

基于Java2D的数值模拟绘图系统研究与实现

大庆油田勘探开发研究院开发研制了具有自主知识产权的聚合物驱油数值模拟软件POLYGEL模型．该模型是一个能够满足油田实际需要的模拟机理完善的聚合物调驱数值模拟软件,具有调剖、多种分子量聚合物驱分质分注等模拟功能．该模型在驱油机理和物理化学现象描述方面已经达到了国际先进水平。然而,POLYGEL模型没有基于微机版本的数值模拟绘图展示系统．使数值模拟的工作效率大为降低,并且也限制了研究院开发研制的数值模拟软件在采油厂的推广应用力度,该文针对上述问题,旨在实现一个操作简捷、性能优越的绘图展示系统,从而使POLYGEL模型的模拟结果更加直观可靠。     

不确定仿射非线性系统的自适应控制——GRBF网络学习方法

研究一类不确定仿射非线性系统的自适应控制问题,构造出基于滑动模型控制和ＧＲＢＦ网络的自适应控制器,使得对于任意的系统初值和网络初始仅重,被控系统的输出均能渐近跟踪已知参考信号,控制器设计中所需估计参数数学于实际参数个数。仿真结果令人满意。     

Optimality of robust disturbance‐feedback strategies

In this paper, robust disturbance‐feedback strategies for finite time‐horizon problems are studied. Linear discrete‐time systems subject to linear control, state constraints, and quadratic objective functions are considered. In addition, persistent disturbances, which enter the system additively and are contained in a polytopic set, act on the system. The synthesis of robust strategies leads in the case of the traditional robust state‐feedback and open‐loop min–max strategies to, respectively, nonconvex problems or conservatism. However, robust disturbance‐feedback problems can easily be reformulated as convex problems and solved by tractable linear matrix inequalities. Hence this approach bypasses the nonconvexity issue while maintaining the advantages of feedback strategies. As a key result, it is shown that both sources of conservatism attributed to this approach, namely, the relaxation method and the affine parametrization, can be removed at the expense of an increase in computational effort. Copyright © 2015 John Wiley & Sons, Ltd.     

关于HFE密码系统的密钥问题研究

多变量密码系统的设计与分析在理论探索与实际应用中扮演着重要的角色.在现有的多变量密码系统中,由Partarin在1996年提出的HFE密码系统被认为是最有前途的.在许多应用中,因HFE密码系统快速的公钥加密等原因,它还是一个很有前途的公钥密码.它的安全性是基于有限域F上的多元二次方程组的求解问题.在HFE公钥密码系统中,密钥问题是一个很重要的问题,但目前还没有映射φ:K-Fn[其中K是F的n次扩展,F的特征为2]及其逆的作用下,对每一个非平凡公钥都有qn(n 1)n/Ⅱi=1(qi-1)2个非平凡私钥与之相对应,同时得出结论:求有限域F上的任意二次方程组的解[方程的个数优小于等于变元的个数n]都可转化求有限域K(K是有限域F的"次扩展)上多项式方程的根,另外还给出了有限域F上HFE密码系统的两类弱密钥.这些结果不但能加深对HFE密码系统的理解,而且也可能产生对HFE密码系统的新的攻击.     

The analysis of global input-to-state stability for piecewise affine systems with time-delay

In this paper, global input-to-state stability (ISS) for discrete-time piecewise affine systems with time-delay are considered. Piecewise quadratic ISS-Lyapunov functions are adopted. Both Lyapunov-Razumikhin and Lyapunov-Krasovskii methods are used. The theorems of Lyapunov-Razumikhin type and Lyapunov-Krasovskii type for piecewise affine systems with time-delay are shown, respectively.     

Reconstruction of General Curves,Using Factorization and Bundle Adjustment

In this paper, we extend the notion of affine shape, introduced by Sparr, from finite point sets to curves. The extension makes it possible to reconstruct 3D-curves up to projective transformations, from a number of their 2D-projections. We also extend the bundle adjustment technique from point features to curves.The first step of the curve reconstruction algorithm is based on affine shape. It is independent of choice of coordinates, is robust, does not rely on any preselected parameters and works for an arbitrary number of images. In particular this means that, except for a small set of curves (e.g. a moving line), a solution is given to the aperture problem of finding point correspondences between curves. The second step takes advantage of any knowledge of measurement errors in the images. This is possible by extending the bundle adjustment technique to curves.Finally, experiments are performed on both synthetic and real data to show the performance and applicability of the algorithm.     

非线性仿射控制系统的C0镇定性

通过Lyapunov函数设计反馈控制器使得非线性仿射控制系统全局渐进稳定是一种有效的方法．为了使得反馈控制器具有连续性,Sontag提出控制Lyapunov函数应具有小控制性,即要求在原点连续反馈控制器存在,该条件在实际中无法应用．针对这一问题本文提出了聚点条件来保证反馈控制器具有连续性,该条件直接对选择的控制Lyapunov函数进行检验,并且聚点条件还是必要的;文章将控制Lyapunov函数的严格不等式放宽为非严格的不等式,提出非严格控制Lyapunov函数,利用LaSalle定理得到：采用满足聚点条件的非严格控制Lyapunov函数来设计连续反馈控制器,非线性仿射控制系统是全局渐进稳定,扩大了控制Lyapunov函数的寻找范围：最后通过对一种带摩擦的弹簧系统进行验证．     

基于混合逻辑动态的混杂系统研究及应用

综述了一种在工业领域中使用的混杂系统建模方法,即基于混合逻辑动态MLD（Mixed Logic Dynamic）的建模方法。分析了在该建模框架下系统的可观性、可控性、形式验证、稳定性、状态估计及故障检测、最优控制和预测控制,并且以水电厂为例讨论了该方法在实际工程中的应用。基于MLD的混杂系统研究目前仍处于起步阶段,在理论上混杂系统预测控制、最优控制、多目标控制及混合整数二次规划求解都有待研究,在应用上如何根据不同问题有效地建模混杂系统也有待研究。