三维矩形布局吸引子性质的研究

吸引子法作为一种量化的定位规则,在解决三维布局问题时取得了较好的效果。 对解决三维矩形布局问题的吸引子法进行了研究,获得了吸引子法的一些基本性质,如最佳布 入点、吸引子法的趋角性、隐性吸引子的“唯一”性以及位置的“动态性”等,有利于吸引子法在 三维矩形布局求解中得到更好地运用。     

动态吸引子在布局求解中的应用

在研究分析现有布局启发算法的基础上,提出了动态吸引子的概念,并据此建立了动态的定位函数和布局求解算法,分析了定位函数中各参数和坐标点的含义．通过调整定位函数中参数的取值,可得到满足不同条件和要求的优化布局方案．最后通过实例验证了该算法的合理性．     

一种基于蜜蜂进化选择算子的布局遗传算法

三维矩形布局问题属于NP 难问题,对于三维矩形布局问题的求解大多依赖于各 种启发式算法。该文以布局物体体积递减为定序规则,结合布局物体在布局空间中的几何可行 域,以吸引子法为定位规则,利用蜜蜂进化型遗传算法优化吸引子函数中的参数来求解三维矩 形布局问题(BEGA),得到新型布局遗传算法。最后对不同的算例进行了计算,并与以标准比 例选择作为选择算子的传统布局遗传算法(SPGA)等对比证明了该算法的有效性。     

基于非线性方程组的吸引子图形绘制

利用线性函数迭代系统进行迭代可以绘制出树与山等自然景物,而非线性系统在这方面的研究结果相对较少。本文利用辅助函数与一个随机生成的多项式函数构成动力系统,其中辅助函数具备类似正弦函数的性质,而多项式函数只含有二次项或者一次项,通过绘制分形图等方法对系统的混沌特性进行分析,结果表明,一组三维正弦函数与两个三维多项式函数构造的动力系统是混沌的概率很高,通过迭代可以得到众多的具有观赏和实用价值的三维吸引子。除了可以辅助绘制吸引子图形外,这种构造混沌的方法也是混沌理论研究的一个实例。     

复混沌系统的稳态控制

混沌系统的多稳态具有复杂性和非预期性,引起了人们的极大关注,如何针对混沌系统进行稳态控制还没有有效的方法.混沌吸引子是复混沌系统典型的动态特性.本文的主要目标是选择合适的控制方法使复混沌系统在预定的位置范围获得期望的稳态吸引子.本文即针对复混沌稳态吸引子的控制问题,提出了分段函数控制器和比例正弦函数控制器,分别用于实现稳态吸引子的位置控制和形状控制,其中混沌吸引子的位置由分段函数的间隔控制,混沌吸引子的形状由系统参数或正弦函数控制.这两种控制器简单可行,易于实现.最后,通过复Lorenz混沌系统和一个物理实例Duffing振子仿真实验验证了所提出控制器的有效性.     

具有平面晶体对称性混沌吸引子的分形极限图

提出用混沌函数构造具有平面晶体群对称性混沌吸引子的上半平面、方极限和圆极限分形图的简便方法.通过确定单个混沌吸引子所在的基本区域,利用同胚仿射变换,把基本区域中的混沌吸引子自相似地映射到上半平面,进而生成方极限、圆极限分形图.这些图案具有很好的艺术渲染力.该方法使单个混沌吸引子保持几何结构不变,但图形在整体上却具有很好分形自相似的性质.     

基于离散余弦变换基函数迭代的人脸图像识别

使用非线性混沌方法处理与识别图像的研究工作逐渐增多,已有文献给出了一种 将正弦函数作为辅助函数与图像构造动力系统,迭代生成混沌吸引子作为图像特征。为进一步 探究图像吸引子作为图像的特性,改进识别效果,使用离散余弦变换(DCT)基函数矩阵代替正 弦函数,迭代生成近似混沌吸引子,用于人脸识别。首先,研究分析了DCT 基函数矩阵的多样 性与振荡特性;然后利用DCT 基函数矩阵与图像矩阵构造迭代表达式,通过给出的迭代算法使 其产生吸引子,再对吸引子进行快速傅里叶变换,计算相关系数,识别人脸图像。对于Yalefaces 图像库,每幅图像都参加训练,识别率可以达到100%,当使用每组前5 幅图像训练提取特征, 识别率可以超过85%;对于CMU PIE 数据库,每幅图像都参加训练,识别率可以超过99%。 该吸引子方法可以作为一种图像底层特征提取方法,有待于进一步深入研究。     

饱和函数序列电路的设计及其在多涡卷混沌电路中的应用

以普通运算放大器作为有源器件,设计了饱和函数序列电路,给出了电路频率临界值.将饱和函数序列电路应用于多涡卷混沌电路设计,研究了饱和函数序列幅度、宽度、斜率等参数对多涡卷混沌吸引子相图的影响.设计了基于参数可调的饱和函数序列的混沌电路,研究表明,通过选择合适的参数,可以调控多涡卷吸引子大小和形状.设计的饱和函数序列电路稳定且灵活,有利于其在多涡卷混沌电路中的应用.     

多涡卷Chua混沌吸引子的设计与性能分析

为了设计结构复杂、性能优越的多涡卷混沌系统,采用理论分析和数值仿真的方法,通过设计一个连续非线性函数,建立了三阶Chua系统的单方向与网格多涡卷吸引子模型.在Matlab平台上,通过吸引子相图、最大Lyapunov指数、分岔图和Poincaré截面等方法,分析了多涡卷Chua混沌系统的动力学特性.研究结果表明,多涡卷Chua混沌吸引子具有丰富的动力学特性,仿真结果与理论分析一致,表明了多涡卷Chua混沌系统设计方法的有效性和设计模型的正确性.     

利用互信息确定延迟时间的新算法

对比研究混沌时间序列相空间重构中对延迟时间选取的各种算法,根据混沌吸引子所具有的伪周期性与各态历经的性质,提出采用逐步细化的方法寻找系统互信息函数的第一局部最小值,作为最佳的延迟时间。克服了传统互信息函数计算繁琐、难以编程实现的缺点,兼具精确性与高效性。通过Risssler和Lorenz系统的数值仿真结果验证了算法的可靠性。     

Capacitated single allocation hub location problem—A bi-criteria approach

A different approach to the capacitated single allocation hub location problem is presented. Instead of using capacity constraints to limit the amount of flow that can be received by the hubs, we introduce a second objective function to the model (besides the traditional cost minimizing function), that tries to minimize the time to process the flow entering the hubs. Two bi-criteria single allocation hub location problems are presented: in a first model, total time is considered as the second criteria and, in a second model, the maximum service time for the hubs is minimized. To generate non-dominated solutions an interactive decision-aid approach developed for bi-criteria integer linear programming problems is used. Both bi-criteria models are tested on a set of instances, analyzing the corresponding non-dominated solutions set and studying the reasonableness of the hubs flow charge for these non-dominated solutions. The increased information provided by the non-dominated solutions of the bi-criteria model when compared to the unique solution given by the capacitated hub location model is highlighted.     

基于激光雷达的室外移动机器人避障与导航新方法

提出了一种应用于室外移动机器人避障与导航的新方法——角度势场法．此方法将当前视场极坐标系的二维障碍物信息转换到一维的角度域内,综合评估视场内的障碍物在角度域内产生的阻力效应,以及目标点在角度域内产生的引力效应,计算得出当前目标角度及通行函数,确定移动机器人驾驶角和速度的控制输出,做到兼顾移动机器人的安全与向目标点的行进．此方法已应用于室外移动机器人THMR V．     

Moving-boundary problems solved by adaptive radial basis functions

The objective of this paper is to present an alternative approach to the conventional level set methods for solving two-dimensional moving-boundary problems known as the passive transport. Moving boundaries are associated with time-dependent problems and the position of the boundaries need to be determined as a function of time and space. The level set method has become an attractive design tool for tracking, modeling and simulating the motion of free boundaries in fluid mechanics, combustion, computer animation and image processing. Recent research on the numerical method has focused on the idea of using a meshless methodology for the numerical solution of partial differential equations. In the present approach, the moving interface is captured by the level set method at all time with the zero contour of a smooth function known as the level set function. A new approach is used to solve a convective transport equation for advancing the level set function in time. This new approach is based on the asymmetric meshless collocation method and the adaptive greedy algorithm for trial subspaces selection. Numerical simulations are performed to verify the accuracy and stability of the new numerical scheme which is then applied to simulate a bubble that is moving, stretching and circulating in an ambient flow to demonstrate the performance of the new meshless approach.     

A multifactor model for international plant location and financing under uncertainty

This paper presents a model for analyzing international plant location and financing decisions under uncertainty. The model diverges from the usual plant location problem in that location and financing decisions are considered simultaneously. This approach is necessary since subsidized financing as well as preferential tax treatment can be significant influences on international location decisions. In addition, financing in different currencies can be used to hedge uncertain price and exchange rate movements.Risk aversion enters via a mean-variance objective function in firm profit. The resulting problem is mixedinteger quadratic and would generally present severe computational difficulties. However, we show that a multifactor approach can be used to transform this problem into one which can be solved fairly readily. The result is a model which is computationally feasible for problems of reasonable size while still including the effects of uncertainty, financial subsidies and hedging strategies on international location decisions. Computational experience is discussed for two solution procedures. One approach uses the quadratic programming package of LINDO coupled to a branch-and-bound procedure. The other approach used a gradient search procedure plus branch-and-bound.     

Data Intensive and Network Aware (DIANA) Grid Scheduling

In Grids scheduling decisions are often made on the basis of jobs being either data or computation intensive: in data intensive situations jobs may be pushed to the data and in computation intensive situations data may be pulled to the jobs. This kind of scheduling, in which there is no consideration of network characteristics, can lead to performance degradation in a Grid environment and may result in large processing queues and job execution delays due to site overloads. In this paper we describe a Data Intensive and Network Aware (DIANA) meta-scheduling approach, which takes into account data, processing power and network characteristics when making scheduling decisions across multiple sites. Through a practical implementation on a Grid testbed, we demonstrate that queue and execution times of data-intensive jobs can be significantly improved when we introduce our proposed DIANA scheduler. The basic scheduling decisions are dictated by a weighting factor for each potential target location which is a calculated function of network characteristics, processing cycles and data location and size. The job scheduler provides a global ranking of the computing resources and then selects an optimal one on the basis of this overall access and execution cost. The DIANA approach considers the Grid as a combination of active network elements and takes network characteristics as a first class criterion in the scheduling decision matrix along with computations and data. The scheduler can then make informed decisions by taking into account the changing state of the network, locality and size of the data and the pool of available processing cycles.     

The role of context in perceptions of the aesthetics of web pages over time

An important aspect of the empirical study of user experience is the process by which users form aesthetic and other judgements of interactive products. The current study extends previous research by presenting test users with a context (mode of use) in which to make their judgements, using sets of web pages from specific domains rather than unrelated pages, studying the congruence of perceptions of aesthetic value over time, including judgements after use of a web site, manipulating the aesthetic design of web pages and studying the relationship between usability and aesthetic value. The results from two experiments demonstrate that context increases the stability of judgements from perceptions after brief exposure to those after self-paced exposure and from perceptions after self-paced exposure to those of after site use. Experiment 1 shows that relatively attractive pages are preferred over relatively unattractive pages after brief exposure, but only if no context is provided. Experiment 2 shows that after brief exposure, classically aesthetic pages that are information oriented are rated as more attractive than expressively aesthetic pages. Perceptions are not correlated with measures of task performance or mental effort. We conclude that context is a pivotal factor influencing the stability of users’ perceptions, which must be explicitly addressed in the study of users’ product experience. Furthermore, the type of aesthetics that is relevant to users’ perceptions appears to depend on the application domain. The principle ‘what is beautiful is usable’ is not confirmed.     

加权方差投影在眼角定位中的应用

提出了一种基于加权方差投影函数(WVPF )的眼角定位方法。该方法利用Haarlike 特征训练级联分类器,定位眼角的粗略位置。同时,采用Harris角点检测中的角点响应函数作为加权因子函数,构建了加权方差投影函数。考虑到眼角的角点特征,眼角位置在眼角区域内的水平加权方差投影曲线和垂直加权方差投影曲线中都有峰值,可通过对加权方差投影曲线的分析对眼角细定位。实验结果表明,该方法在BioID人脸库中对眼角定位表现良好,计算复杂度低。     

改进RetinaNet的遮挡目标检测算法研究

针对目标检测任务中目标实例密集、重叠等因素导致的检测精度不高的问题,提出一种改进回归损失函数与动态非极大值抑制的目标检测框架。采用结合排斥因子Rep的GIoU-Loss进行目标位置回归,在增加回归参数间相关性的同时降低候选边框向邻近真值偏移概率。Rep-GIoU-Loss不仅有效提升目标位置回归精度,对目标遮挡情形也具有较好的鲁棒性。此外,增加稠密度预测分支预测目标被遮挡程度,并将遮挡程度预测值作为NMS方法的动态阈值,以减少漏检、虚检目标实例。实验结果表明,改进方法检测精度在PASCAL VOC2007测试数据集上提高了1.3个百分点,自制数据集可提高2.8个百分点,验证了该方法的有效性。     

一种基于遗传算法的多缺陷定位方法

基于程序频谱的缺陷定位方法可以有效地辅助开发人员定位软件内部缺陷,但大部分已有自动化方法在解决多缺陷定位问题时表现不佳,部分效果尚可的方法因复杂度较高或需要开发人员较多交互而仍需进一步改善.为改善上述问题,提出一种基于遗传算法的多缺陷定位方法 GAMFal,具体来说:首先基于搜索的软件工程思想对多缺陷定位问题进行建模,构建了候选缺陷分布的染色体编码方式,并基于扩展的Ochiai系数计算个体的适应度值;随后使用遗传算法在解空间中搜索具有最高适应度值的候选缺陷分布,在终止条件被满足后返回最优解种群;最后根据这个种群对程序实体进行排序.这样开发人员可以依次对程序实体进行检查并最终确定多个缺陷的具体位置.实证研究以Siemens套件中的7个程序和Linux的3个程序(gzip、grep和sed)作为评测对象,并扩展传统的定位方法评测标准EXAM至EXAMF和EXAML,通过与其他经典的缺陷定位方法(Tarantula、Improved Tarantula及Ochiai)进行对比,并通过Friedman检测和最小显著性差异测试可得,提出的GAMFal方法在整体定位效率方面优于传统方法,且需要更少的人工交互.除此之外,GAMFal的执行时间也在可接受的范围之内.