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Effects of heterogeneous wealth distribution on public cooperation with collective risk

Physical Review E 2010年第1期82卷 016102-016102页

作者： Jing Wang Feng Fu Long Wang Center for Systems and Control State Key Laboratory for Turbulence and Complex Systems College of Engineering Peking University Beijing 100871 China Program for Evolutionary Dynamics Harvard University One Brattle Square Cambridge Massachusetts 02138 USA

The distribution of wealth among individuals in real society can be well described by the Pareto principle or “80-20 rule.” How does such heterogeneity in initial wealth distribution affect the emergence of public cooperation, when individuals, the rich and the poor, engage in a collective-risk enterprise, not to gain a profit but to avoid a potential loss? Here we address this issue by studying a simple but effective model based on threshold public goods games. We analyze the evolutionary dynamics for two distinct scenarios, respectively: one with fair sharers versus defectors and the other with altruists versus defectors. For both scenarios, particularly, we in detail study the dynamics of the population with dichotomic initial wealth—the rich versus the poor. Moreover, we demonstrate the possible steady compositions of the population and provide the conditions for stability of these steady states. We prove that in a population with heterogeneous wealth distribution, richer individuals are more likely to cooperate than poorer ones. Participants with lower initial wealth may choose to cooperate only if all players richer than them are cooperators. The emergence of pubic cooperation largely relies on rich individuals. Furthermore, whenever the wealth gap between the rich and the poor is sufficiently large, cooperation of a few rich individuals can substantially elevate the overall level of social cooperation, which is in line with the well-known Pareto principle. Our work may offer an insight into the emergence of cooperative behavior in real social situations where heterogeneous distribution of wealth among individual is omnipresent.

关键词： Pareto principle

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Evolutionary dynamics of public goods games with diverse contributions in finite populations

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Physical Review E 2010年第5期81卷 056103-056103页

作者： Jing Wang Bin Wu Xiaojie Chen Long Wang Center for Systems and Control State Key Laboratory for Turbulence and Complex Systems College of Engineering Peking University Beijing 100871 China Max-Planck-Institute for Evolutionary Biology August-Thienemann-Str. 2 24306 Plön Germany

The public goods game is a powerful metaphor for exploring the maintenance of social cooperative behavior in a group of interactional selfish players. Here we study the emergence of cooperation in the public goods games with diverse contributions in finite populations. The theory of stochastic process is innovatively adopted to investigate the evolutionary dynamics of the public goods games involving a diversity of contributions. In the limit of rare mutations, the general stationary distribution of this stochastic process can be analytically approximated by means of diffusion theory. Moreover, we demonstrate that increasing the diversity of contributions greatly reduces the probability of finding the population in a homogeneous state full of defectors. This increase also raises the expectation of the total contribution in the entire population and thus promotes social cooperation. Furthermore, by investigating the evolutionary dynamics of optional public goods games with diverse contributions, we find that nonparticipation can assist players who contribute more in resisting invasion and taking over individuals who contribute less. In addition, numerical simulations are performed to confirm our analytical results. Our results may provide insight into the effect of diverse contributions on cooperative behaviors in the real world.

关键词： Random processes

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New type of adaptive control for a class of distributed time-delay systems with adaptation regard to delay parameter

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Journal of systems engineering and Electronics 2010年第6期000卷 1054-1062页

作者： Lin Chai Shumin Fei Haiyan Jin Ruimin Wang Yanhong Li Key Laboratory of Measurement and Control of Complex Systems of Engineering Southeast UniversityNanjing 210096P.R.China School of Automation Southeast UniversityNanjing 210096P.R.China

The problem on stabilization for the system with distributed delays is researched. The distributed time-delay under consideration is assumed to be a constant time-delay, but not known exactly. A design method is proposed for a memory proportional and integral (PI) feedback controller with adaptation to distributed time-delay. The feedback controller with memory simultaneously contains the current state and the past distributed information of the addressed systems. The design for adaptation law to distributed delay is very concise. The controller can be derived by solving a set of linear matrix inequalities (LMIs). Two numerical examples are given to illustrate the effectiveness of the design method.

关键词： distributed delay linear matrix inequality (LMI) adaptive control time-delay systems memory PI feedback

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Limited-memory-BFGS-based iterative algorithm for multispectral bioluminescence tomography with Huber regularization

Limited-memory-BFGS-based iterative algorithm for multispect...

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Medical Imaging 2010 - Biomedical Applications in Molecular, Structural, and Functional Imaging

作者： Feng, Jinchao Jia, Kebin Tian, Jie Qin, Chenghu Zhu, Shouping College of Electronic Information and Control Engineering Beijing University of Technology Beijing 100022 China Key Laboratory of Complex Systems and Intelligence Science Institute of Automation Chinese Academy of Sciences P. O. Box 2728 Beijing 100190 China Life Science Research Center Xidian University Xi'an 710071 China

ISBN: (纸本)9780819480279

Multispectral bioluminescence tomography is becoming a promising tool because it can resolve the biodistibution of bioluminescent reporters associated with cellular and subcellular function through several millimeters with to centimeters of tissues in vivo. Generally, to recover the bioluminescent sources, the source reconstruction problem is formulated as a nonlinear least-squares-type bounds constrained optimization problem. However, bioluminescence tomography (BLT) is an ill-posed problem. For the sake of stability and uniqueness of BLT, many algorithms have been proposed to regularize the problem, such as L2 norm and L1 norm. Here, we proposed a new regularization method with Huber function to regularize BLT problem to obtain robustness like L1 and rapid convergence of L 2. Furthermore, the computational burden is largely increased with the use of spectral data. Therefore, there is a critical need to develop a fast reconstruction algorithm for solving multispectral bioluminescence tomography. In the paper, a limited memory quasi-Newton algorithm for solving the large-scale optimization problem is proposed to fast localize the bioluminescent source. In the numerical simulation, a heterogeneous phantom was used to evaluate the performance of the proposed algorithm with the Monte Carlo based synthetic data. Additionally, the real mouse experiments were conducted to further evaluate the proposed algorithm. The results demonstrate the potential and merits of the proposed algorithm. © 2010 Copyright SPIE - The International Society for Optical engineering.

关键词： Constrained optimization

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Universality of weak selection

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Physical Review E 2010年第4期82卷 046106-046106页

作者： Bin Wu Philipp M. Altrock Long Wang Arne Traulsen Research Group Evolutionary Theory Max-Planck-Institute for Evolutionary Biology August-Thienemann-Str. 2 24306 Plön Germany Center for Systems and Control State Key Laboratory for Turbulence and Complex Systems College of Engineering Peking University Beijing 100871 China

Weak selection, which means a phenotype is slightly advantageous over another, is an important limiting case in evolutionary biology. Recently, it has been introduced into evolutionary game theory. In evolutionary game dynamics, the probability to be imitated or to reproduce depends on the performance in a game. The influence of the game on the stochastic dynamics in finite populations is governed by the intensity of selection. In many models of both unstructured and structured populations, a key assumption allowing analytical calculations is weak selection, which means that all individuals perform approximately equally well. In the weak selection limit many different microscopic evolutionary models have the same or similar properties. How universal is weak selection for those microscopic evolutionary processes? We answer this question by investigating the fixation probability and the average fixation time not only up to linear but also up to higher orders in selection intensity. We find universal higher order expansions, which allow a rescaling of the selection intensity. With this, we can identify specific models which violate (linear) weak selection results, such as the one-third rule of coordination games in finite but large populations.

关键词： Game theory

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Evolutionary prisoner's dilemma game on highly clustered community networks

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Chinese Physics B 2009年第7期18卷 2623-2628页

作者：刘永奎李智陈小杰王龙 Center for Complex Systems Department of Automatic Control Engineering Xidian University State Key Laboratory for Turbulence and Complex Systems Center for Systems and Control College of Engineering Peking University

This paper studies the evolutionary prisoner＇s dilemma game on a highly clustered community network in which the clustering coefficient and the community size can be tuned. It finds that the clustering coefficient in such a degree-homogeneous network inhibits the emergence of cooperation for the entire range of the payoff parameter. Moreover, it finds that the community size can also have a marked influence on the evolution of cooperation, with a larger community size leading to not only a lower cooperation level but also a smaller threshold of the payoff parameter above which cooperators become extinct.

关键词： prisoner＇s dilemma cooperation clustering coefficient community structure

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Evolutionary Self-Questioning Games with Local Contribution

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中国物理快报（英文版） 2009年第8期26卷 375-378页

作者： LIU Yong-Kui LI Zhi CHEN Xiao-Jie WANG Long Center for Complex Systems Department of Automatic Control EngineeringXidian UniversityXi'an 710071 State Key Laboratory for Turbulence and Complex Systems Center for Systems and ControlCollege of EngineeringPeking UniversityBeijing 100871 Department of Zoology University of British ColumbiaVancouver BC V6T 1Z4Canada Center for Complex Systems Department of Automatic Control EngineeringXidian UniversityXi'an 710071 State Key Laboratory for Turbulence and Complex Systems Center for Systems and ControlCollege of EngineeringPeking UniversityBeijing 100871

We investigate the evolutionary Prisoner's Dilemma and the Snowdrift Game on small-world networks in a realistic social context where individuals consider their local contributions to their group and update their strategies by self-questioning. An individual with introspection can determine whether its current strategy is superior by playing a virtual round of the game and its local contribution is defined as the sum of all the payoffs its neighbors collect against it. In our model, the performance of an individual is determined by both its payoff and local contribution through a linear combination. We demonstrate that the present mechanism can produce very robust cooperative behavior in both games. Furthermore, we provide theoretical analysis based on mean-field approximation, and find that the analytical predictions are qualitatively consistent with the simulation results.

关键词： No English keyword

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Prisoner's Dilemma Game on Two Types of Positively Correlated Networks

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中国物理快报（英文版） 2009年第4期26卷 265-268页

作者： LIU Yong-Kui LI Zhi CHEN Xiao-Jie WANG Long Center for Complex Systems Department of Automatic Control EngineeringXidian UniversityXi'an 710071 State Key Laboratory for Turbulence and Complex Systems Center for Systems and ControlCollege of EngineeringPeking UniversityBeijing 100871 Department of Zoology University of British ColumbiaVancouver BC V6T 1Z4Canada State Key Laboratory for Turbulence and Complex Systems Center for Systems and ControlCollege of EngineeringPeking UniversityBeijing 100871 Center for Complex Systems Department of Automatic Control EngineeringXidian UniversityXi'an 710071

We study the effects of degree correlations on the evolution of cooperation in the prisoner's dilemma game with individuals located on two types of positively correlated networks. It is shown that the positive degree correlation can either promote or inhibit the emergence of cooperation depending on network configurations. Furthermore, we investigate the probability to cooperate as a function of connectivity degree, and find that high-degree individuals generally have a higher tendency to cooperate. Finally, it is found that small-degree individuals usually change their strategy more frequently, and such change is shown to be unfavourable to cooperation for both kinds of networks.

关键词： No English keywords

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Prisoner's Dilemma Game on Clustered Scale-Free Networks under Different Initial Distributions

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中国物理快报（英文版） 2009年第8期26卷 4-7页

作者： LEI Chuang JIA Jian-Yuan CHEN Xiao-Jie CONG Rui WANG Long School of Mechano-electronic Engineering Xidian UniversityXi'an 710071 State Key Laboratory for Turbulence and Complex Systems Center for Systems and ControlCollege of EngineeringPeking UniversityBeijing 100871 School of Mechano-electronic Engineering Xidian UniversityXi'an 710071 State Key Laboratory for Turbulence and Complex Systems Center for Systems and ControlCollege of EngineeringPeking UniversityBeijing 100871

The evolutionary prisoner's dilemma game is investigated under different initial distributions for cooperators and defectors on scale-free networks with a tunable clustering coefficient. It is found that, on the one hand, cooperation can be enhanced with the increasing clustering coefficient when only the most connected nodes are occupied by cooperators initially. On the other hand, if cooperators just occupy the lowest-degree nodes at the beginning, then the higher the value of the clustering coefficient, the more unfavorable the environment for cooperators to survive for the increment of temptation to defect. Thereafter, we analytically argue these nontrivial phenomena by calculating the cooperation probability of the nodes with different degrees in the steady state, and obtain the critical values of initial frequency of cooperators below which cooperators would vanish finally for the two initial distributions.

关键词： No English keyword

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HS joint statistics based adaptive color segmentation

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Dongnan Daxue Xuebao (Ziran Kexue Ban)/Journal of Southeast University (Natural Science Edition) 2010年第SUPPL. 1期40卷 266-271页

作者： Li, Jun Meng, Zhengda School of Automation Southeast University Nanjing 210096 China Key Laboratory of Measurement and Control of Complex Systems of Engineering of Ministry of Edu. Southeast University Nanjing 210096 China

An adaptive threshold segmentation algorithm based on HS joint statistics using HSI color model is introduced in order to improve the performance of image segmentation and the robustness of object recognition to illumination change. Statistics of H and S component value of all the pixels in the region of interest (ROI) is obtained after image segmentation in HSI color space. The changing rule of statistics is verified while an empirical scale factor is applied to reflect the difference between the influence of H value and S value on segmentation threshold. The threshold is thus adjusted online according to the proposed approach. Experimental results demonstrate the decrease trend of H and S component value with intensified light. Furthermore, it validates the robustness of the approach under the circumstance of changing illumination. Thus the accuracy of the vision-based robot grasping is significantly improved.

关键词： Image segmentation

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