False‐Name Manipulation in Weighted Voting Games: Empirical and Theoretical Analysis

Weighted voting games are important in multiagent systems because of their usage in automated decision making. However, they are not immune from the vulnerability of false‐name manipulation by strategic agents that may be present in the games. False‐name manipulation involves an agent splitting its weight among several false identities in anticipation of power increase. Previous works have considered false‐name manipulation using the well‐known Shapley–Shubik and Banzhaf power indices. Bounds on the extent of power that a manipulator may gain exist when it splits into k = 2 false identities for both the Shapley–Shubik and Banzhaf indices. The bounds when an agent splits into k > 2 false identities, until now, have remained open for the two indices. This article answers this open problem by providing four nontrivial bounds when an agent splits into k > 2 false identities for the two indices. Furthermore, we propose a new bound on the extent of power that a manipulator may gain when it splits into several false identities in a class of games referred to as excess unanimity weighted voting games. Finally, we complement our theoretical results with empirical evaluation. Results from our experiments confirm the existence of beneficial splits into several false identities for the two indices, and also establish that splitting into more than two false identities is qualitatively different than the previously known splitting into exactly two false identities.     

A systematic decision making approach for product conceptual design based on fuzzy morphological matrix

Conceptual design plays an important role in development of new products and redesign of existing products. Morphological matrix is a popular tool for conceptual design. Although the morphological-matrix based conceptual design approaches are effective for generation of conceptual schemes, quantitative evaluation to each of the function solution principle is seldom considered, thus leading to the difficulty to identify the optimal conceptual design by combining these function solution principles. In addition, the uncertainties due to the subjective evaluations from engineers and customers in early design stage are not considered in these morphological-matrix based conceptual design approaches. To solve these problems, a systematic decision making approach is developed in this research for product conceptual design based on fuzzy morphological matrix to quantitatively evaluate function solution principles using knowledge and preferences of engineers and customers with subjective uncertainties. In this research, the morphological matrix is quantified by associating the properties of function solution principles with the information of customer preferences and product failures. Customer preferences for different function solution principles are obtained from multiple customers using fuzzy pairwise comparison (FPC). The fuzzy customer preference degree of each solution principle is then calculated by fuzzy logarithmic least square method (FLLSM). In addition, the product failure data are used to improve product reliability through fuzzy failure mode effects analysis (FMEA). Unlike the traditional FMEA, the causality relationships among failure modes of solution principles are analyzed to use failure information more effectively through constructing a directed failure causality relationship diagram (DFCRD). A fuzzy multi-objective optimization model is also developed to solve the conceptual design problem. The effectiveness of this new approach is demonstrated using a real-world application for conceptual design of a horizontal directional drilling machine (HDDM).     

时滞状态反馈下离散时滞系统H∞控制器失效时间分析

针对控制器存在短暂失效的情形,研究一类时变时滞离散系统在时滞状态反馈控制下的H_∞控制器失效时间分析问题.本文的目标是寻求控制器正常工作时间与失效时间的比率应满足的条件以确保系统指数镇定且具有加权l_2增益.为此,基于切换的思想,所考虑的系统被转化为一个仅含有两个子系统的切换系统,其中一个子系统是控制器失效时的不稳定子系统,另一个是控制器未失效时的稳定子系统.通过使用多Lyapunov函数及平均驻留时间方法,给出问题可解的充分条件及时滞状态反馈H_∞切换控制器的设计方案.仿真算例表明了所得结果的有效性.     

微分代数系统结构化分析

对工程和科学问题进行建模和仿真的时候,人们常常很自然地会用微分代数系统对这些问题进行描述.为了检验微分代数系统的初始相容性并进行求解,对微分代数系统进行结构化分析非常重要.本文对经典的微分代数系统结构化分析方法进行了深入的研究;提出了一种新的结构化分析方法,可以高效地对大规模、高阶高指标的微分代数系统进行结构化分析,并快速检验其初始相容性;证明了该方法的终止性,分析了其最坏时间复杂度.该方法的关键在于对最大加权二部子图的使用,而最大加权二部子图则来源于原始系统的加权二部图.实验结果显示,该方法能高效地完成对微分代数系统的结构化分析.     

互联网空间下的城市网络格局及结构研究*

大数据时代,互联网成为科学研究的有效工具和平台。借助百度搜索指数数据,运用复杂网络方法构建互联网空间下有向加权城市网络模型,分析互联网上的城市网络格局及复杂结构。以我国36大城市数据为样本,实证发现该城市网络的节点出权及入权累积分布均符合指数分布,归类网络中的城市活跃类型,计算挖掘出网络中的关键城市节点以及网络的凝聚子群。从互联网新媒介视角对“互联网 ”计划下城市网络结构做出了新的解析,丰富了城市复杂网络的研究,对城市的建设规划、管理具有指导意义。     

基于加权频繁子树相似度的网页评论信息抽取*

快速积累的海量产品评论信息是商家和消费者进行需求调研或购物决策时的重要依据。针对现有网页信息抽取方法普遍存在人工耗时大,抽取准确率低等问题,提出了一种基于加权频繁子树相似度的网页评论信息抽取方法WTS。首先通过视觉特征对网页进行剪枝处理。然后,通过深度加权的相似度度量方法抽取最佳频繁子树。最后,通过子树对齐方法抽取评论路径并解析评论内容。通过对京东、苏宁等网站的评论内容抽取实验,验证了WTS比D-EEM、POL等方法在抽取产品评论信息上具有一定的优势。     

自适应局部区域型水平集分割算法

灰度不均匀现象普遍存在于自然图像和医学图像中,因此使用传统的图像分割方法很难精准的分割出目标物,从而导致图像分割在模式识别和临床医学的应用中会出现很多问题.为了更好地改善分割效果,解决灰度不均匀现象所带来的问题,本文结合图像的自适应梯度权重信息和局部区域信息提出一种新型的水平集分割算法.由于图像的梯度信息具有稳定性,因此文中通过在局部区域中使用自适应梯度权重信息,达到结合图像边缘信息和区域信息的目的以提高算法鲁棒性.同时,文中使用的梯度权重滤波增加了图像对比度,因此分割的效果有了显著改善.最后,通过与LCV （local Chan-Vese）模型和LIC （local intensity clustering）模型的对比实验来验证本文分割方法的有效性和鲁棒性.在实验对比中,本文方法均得到比较令人满意的结果,充分展示其在处理灰度不均匀图像上的优势.     

空间站测量设备计量周期确定方法研究与探讨

测量设备的计量周期是指按照规定程序对测量设备进行定期计量的时间间隔,一般为1年。随着中国空间站时代的逐渐到来,在轨测量设备运行时间需要多年以上,存在地面所说的设备计量超期使用问题,如何分析评估测量设备,合理确定计量周期、尽最大可能满足空间站需求变得较为迫切。本文结合中国未来空间站测量设备的实际特点,介绍了医监医保类设备确定计量周期的原则和方法,选择使用加权及总分评定法确定计量周期。本文既可为未来空间站设备计量周期确定提供参考,也可以为非强制检定设备确定计量周期提供参考。     

Minimising total weighted earliness and tardiness penalties on identical parallel machines using a fast ruin-and-recreate algorithm

This paper studies the scheduling problem of minimising total weighted earliness and tardiness penalties on identical parallel machines against a restrictive common due date. This problem is NP-hard in the strong sense and arises in many just-in-time production environments. A fast ruin-and-recreate (FR&R) algorithm is proposed to obtain high-quality solutions to this complex problem. The proposed FR&R algorithm is tested on a well-known set of benchmark test problems that are taken from the literature. Computational results provide evidence of the efficiency of FR&R, which consistently outperform existing algorithms when applied to benchmark instances. This work provides a viable alternative approach for efficiently solving this practical but complex scheduling problem.     

A pseudospectral tau approximation for time delay systems and its comparison with other weighted‐residual‐type methods

This paper presents a method which applies pseudospectral tau approximation for retarded functional differential equations (RFDEs). The goal is to construct a system of ordinary differential equations, which provides a finite dimensional approximation of the original RFDE. The method can be used to determine approximate stability diagrams for RFDEs. Thorough numerical case studies show that the rightmost characteristic roots of the ordinary differential equation approximation converge to the rightmost characteristic roots of the original RFDE. Application of the method to time‐periodic RFDEs is also demonstrated, and the convergence of the stability boundaries is verified numerically. The method is compared with recently developed highly efficient numerical methods: the pseudospectral collocation (also called Chebyshev spectral continuous‐time approximation), the spectral Legendre tau method, and the spectral element method. The comparison is based on the stability analysis of three linear autonomous RFDEs. The efficiency of the methods is measured by the convergence rate of stability boundaries in the space of system parameters, by the convergence rate of the rightmost characteristic exponent and by the computation time of the stability charts. Copyright © 2016 John Wiley & Sons, Ltd.