Efficient solution of a class of partial integro-differential equation in reproducing kernel space

In [Y.l. Wang, T. Chaolu, Z. Chen, Using reproducing kernel for solving a class of singular weakly nonlinear boundary value problems, Int. J. Comput. Math. 87(2) (2010), pp. 367–380], we present three algorithms to solve a class of ordinary differential equations boundary value problems in reproducing kernel space. It is worth noting that our methods can get the solution of partial integro-differential equation. In this note, we use method 2 [M. Dehghan, Solution of a partial integro-differential equation arising from viscoelasticity, Int. J. Comput. Math. 83(1) (2006), pp. 123–129] to solve a class of partial integro-differential equation in reproducing kernel space. Numerical example shows our method is effective and has high accuracy.     

On local convergence of a Newton-type method in Banach space

In this study we are concerned with the local convergence of a Newton-type method introduced by us [I.K. Argyros and D. Chen, On the midpoint iterative method for solving nonlinear equations in Banach spaces, Appl. Math. Lett. 5 (1992), pp. 7–9.] for approximating a solution of a nonlinear equation in a Banach space setting. This method has also been studied by Homeier [H.H.H. Homeier, A modified Newton method for rootfinding with cubic convergence, J. Comput. Appl. Math. 157 (2003), pp. 227–230.] and Özban [A.Y. Özban, Some new variants of Newton's method, Appl. Math. Lett. 17 (2004), pp. 677–682.] in real or complex space. The benefits of using this method over other methods using the same information have been explained in [I.K. Argyros, Computational theory of iterative methods, in Studies in Computational Mathematics, Vol. 15, C.K. Chui and L. Wuytack, eds., Elsevier Science Inc., New York, USA, 2007.; I.K. Argyros and D. Chen, On the midpoint iterative method for solving nonlinear equations in Banach spaces, Appl. Math. Lett. 5 (1992), pp. 7–9.; H.H.H. Homeier, A modified Newton method for rootfinding with cubic convergence, J. Comput. Appl. Math. 157 (2003), pp. 227–230.; A.Y. Özban, Some new variants of Newton's method, Appl. Math. Lett. 17 (2004), pp. 677–682.]. Here, we give the convergence radii for this method under a type of weak Lipschitz conditions proven to be fruitful by Wang in the case of Newton's method [X. Wang, Convergence of Newton's method and inverse function in Banach space, Math. Comput. 68 (1999), pp. 169–186 and X. Wang, Convergence of Newton's method and uniqueness of the solution of equations in Banach space, IMA J. Numer. Anal. 20 (2000), pp. 123–134.]. Numerical examples are also provided.     

Vanishing point detection using cascaded 1D Hough Transform from single images

Vanishing point detection algorithms based on 2D histogramming techniques have been employed in a variety of computer vision systems. Previous algorithms achieved some good results but still failed to maintain a balanced performance in both accuracy and time. Recent research (Li et al., 2010) shows that, vanishing point detection could be converted to a 1D histogram search problem, which largely accelerates the procedure. In this paper, we further improve this idea and propose a complete scheme for vanishing point detection from images of the so called “Manhattan world”. We test our algorithm and some commonly used vanishing point detection methods on public database YorkUrbanDB and our own implemented database PKUCampusDB. Our algorithm shows significant performance improvements.     

HLA桥接多联邦系统中时空一致性问题研究

针对HLA桥接多联邦系统,提出其时空一致性问题研究。将桥接转发的数据划分为3种数据类型,定义相应的实体类和交互类,给出3种处理方法,其中,延时补偿法解决实体属性更新时的延时,平移命中点法处理精确制导武器爆炸交互时的延时,回滚法面向非精确制导武器爆炸交互时的延时。实验结果表明,该方法可满足桥接多联邦系统中的时空一致性。     

驾驶模拟系统人机界面的真实性评价

驾驶模拟系统是进行各项交通研究的有效手段和工具.详细描述了基于驾驶模拟器和Quest3D自行开发的驾驶模拟系统体系结构,着重介绍了其视觉呈现、听觉混成、体感模拟等模块组成的人机界面的设计,并采用综合分析法对系统人机界面的真实性进行了综合评价.结果表明,本文实现的驾驶模拟系统所建立的虚拟驾驶环境符合真实环境,其真实性能满足相关研究的需求.     

中国当代壁画的“缺席”与“在场”

从中国当代壁画的主题、表现语言、政府的支持程度等不同层面进行了论述,梳理、分析了其中的问题所在.与其他艺术相比,中国当代壁画总是处在一种＂缺席＂的状态,中国当代壁画要想获得重新＂在场＂的契机,必须剖析其本身从形式到公众性缺失等方面的诸多问题.     

电离层电波信号衰减的混沌时间序列预测

电波信号穿过电离层传播时,由于电离层的作用将使得电波信号产生一系列的失真.分析了传统混沌时间序列预测的理论和方法,并分析了电波信号穿过电离层的时间序列特征,发现该时间序列具有混沌时间特征,进而在传统的混沌时间序列预测的基础上,给出了一种更适合于电离层电波衰减时间序列预测的方法.同时,利用它预测了一组电波信号穿过电离层的时间序列特征,并分析了其预测精度.结果表明,利用修正的混沌时间序列预测方法预测的电波信号穿过电离层衰减的时间序列,其短期的预测效果很好.     

Method to generate training samples for neural network used in target recognition

Training neural network to recognize targets needs a lot of samples.People usually get these samples in a non-systematic way,which can miss or overemphasize some target information.To improve this situation,a new method based on virtual model and invariant moments was proposed to generate training samples.The method was composed of the following steps:use computer and simulation software to build target object’s virtual model and then simulate the environment,light condition,camera parameter,etc.;rotate the model by spin and nutation of inclination to get the image sequence by virtual camera;preprocess each image and transfer them into binary image;calculate the invariant moments for each image and get a vectors’ sequence.The vectors’ sequence which was proved to be complete became the training samples together with the target outputs.The simulated results showed that the proposed method could be used to recognize the real targets and improve the accuracy of target recognition effectively when the sampling interval was short enough and the circumstance simulation was close enough.     

利用恒流驱动技术的10～80V宽电压输入串联型开关电源

为拓宽开关电源产品的电压范围,提出了1种基于恒流驱动模式的能在10～80V宽电压范围工作的串联型开关稳压电源.该开关电源采用恒流方式驱动开关管,开关管在宽电压范围内始终能够得到理想的驱动电流.实验表明,该开关电源效率高、工作稳定、成本低,因此,可使用于工业用各种报警器产品和爆闪式信号灯中.     

一种基于显著性活动轮廓模型的图像分割方法

为了有效地提取图像中物体的轮廓,结合视觉注意机制,提出一种改进的距离正则化水平集活动轮廓模型的分析方法。首先提取图像的初级特征,构成图像显著图;然后采用最大类间方差法获得显著区域的初始轮廓,以此作为活动轮廓模型中曲线演化的初始位置;最后利用距离正则化水平集演化,获得目标物体的边界,完成图像分割。这种结合视觉注意机制与改进的距离正则化水平集演化方法能够显著降低水平函数演化次数,提高图像分割效率。仿真结果表明,它能有效检测单个及多目标物体的边界,且定位准确。