The minmax regret gradual covering location problem on a network with incomplete information of demand weights

The gradual covering location problem seeks to establish facilities on a network so as to maximize the total demand covered, allowing partial coverage. We focus on the gradual covering location problem when the demand weights associated with nodes of the network are random variables whose probability distributions are unknown. Using only information on the range of these random variables, this study is aimed at finding the “minmax regret” location that minimizes the worst-case coverage loss. We show that under some conditions, the problem is equivalent to known location problems (e.g. the minmax regret median problem). Polynomial time algorithms are developed for the problem on a general network with linear coverage decay functions.     

一种基于网格模型的无限传感器网络K区域覆盖算法

目前无限传感器网络K覆盖问题的解决机制大都有颇为苛刻的假设条件,如要求节点具有很强的能量、节点的感知区域能被精确定义等.提出了一个基于布尔感知理论的分布式网格模型及相应的K区域覆盖算法,能够很好地处理感知区域形状不规则及大小发生变化的K覆盖问题,算法时间复杂度小,适用范围广泛.仿真实验证明了算法的有效性.     

A dynamic analysis of corporate investments and emission tax policy in an oligopoly market with network externality

We investigate the product innovation, green R&D investments and the emission tax policy in an oligopoly market with network externality. It is shown that an appropriate tax policy should be deployed to effectively control pollution and motivate innovation. At the early stage of the market, the emission tax should gradually reduce to motivate firms to achieve optimal investments. Later at the mature stage, the emission tax policy should carefully consider both the market competition and green technology levels.     

基于变换域PCNN的近红外与彩色可见光融合

针对近红外与彩色可见光图像融合后对比度低、细节丢失和颜色失真等问题,提出一种基于多尺度变换和自适应脉冲耦合神经网络(PCNN-pulse coupled neural network,PCNN)的红外与彩色可见光图像融合的新算法。首先将彩色可见光图像转换到HSI（hue saturation intensity)空间,HSI色彩空间包含亮度、色度和饱和度三个分量,并且这三个分量互不相关,因此利用这个特点可对三个分量分别进行处理。将其亮度分量与近红外图像分别进行多尺度变换,变换方法选择Tetrolet变换。变换后分别得到低频和高频分量,针对图像低频分量,提出一种期望最大的低频分量融合规则;针对图像高频分量,采用高斯差分算子调节PCNN模型的阈值,提出一种自适应的PCNN模型作为融合规则。处理后的高低频分量经过Tetrolet逆变换得到的融合图像作为新的亮度图像。然后将新的亮度图像和原始的色度和饱和度分量反向映射到RGB空间,得到融合后的彩色图像。为了解决融合带来的图像平滑化和原始图像光照不均的问题,引入颜色与锐度校正机制(colour and sharpness correction, CSC)来提高融合图像的质量。为了验证方法的有效性,选取了5组分辨率为1 024×680近红外与彩色可见光图像进行试验,并与当前高效的四种融合方法以及未进行颜色校正的本方法进行了对比。实验结果表明,同其他图像融合算法进行对比分析,该方法在有无CSC颜色的情况下均能保留最多的细节和纹理,可见度均大大提高,同时本方法的结果在光照条件较弱的情况下具有更多的细节和纹理,均具有更好的对比度和良好的色彩再现性。在信息保留度、颜色恢复、图像对比度和结构相似性等客观指标上均具有较大优势。     

双阈值二元神经网络极限环的存在惟一性

研究具负反馈的双阈值二元神经网络模型的动力学性质。在一定的初始函数空间内，对设定的阈值范围证明了模型存在惟一稳定极限环。     

网络流在清理三角债问题中的应用

本文把清理三角债中两种优化数学模型问题，化成求解相应网络上最小费用流的问题，从而得到（强）多项式算法，并把另外的一种优化数学模型问题。化成线性规划问题.于是解答了文[3]中提出的清理三角债的三个基本问题．     

Spin-orbit scattering in the quantum Hall effect

We study dynamics of electrons in a magnetic field using a network model with two channels per link with random mixing, while the intrachannel potential is periodic (non-random); the channels represent two spin states. We consider channel mixing as function of the energy separation of the two extended states, and show that the phase diagram is different from the standard quantum Hall diagram for random intrachannel potential.     

Inverse estimation of temperature dependent emissivity of solid metals

An algorithm in the form of inverse problem to estimate the surface emissivity versus temperature of solids of variable thermal properties separated by a non-participating medium is proposed. The estimations are reproduced by the connection of variable slope stretches (piece-wise function) with no information of the temperature dependence of the emissivity. The input data (measurements) come from the solution of the direct problem by adding a random error to the temperature field. Both the direct and inverse problem are numerically solved by means of the network simulation method. The influence of different parameters in the estimation is studied and the resulting estimations are compared with exact solutions in order to verify the effectiveness of the proposed method.     

Definitions of equilibrium in network formation games

We examine a variety of stability and equilibrium definitions that have been used to study the formation of social networks among a group of players. In particular we compare variations on three types of definitions: those based on a pairwise stability notion, those based on the Nash equilibria of a link formation game, and those based on equilibria of a link formation game where transfers are possible.Bloch is also affiliated with the University of Warwick.     

A framework and algorithms for circular drawings of graphs

In this paper, we present a framework and two linear time algorithms for obtaining circular drawings of graphs. The first technique produces circular drawings of biconnected graphs and finds a zero crossing circular drawing if one exists. The second technique finds multiple embedding circle drawings. Techniques for the reduction of edge crossings are also discussed. Results of experimental studies are included.