Beyond pairwise strategy updating in the prisoner's dilemma game

In spatial games players typically alter their strategy by imitating the most successful or one randomly selected neighbor. Since a single neighbor is taken as reference, the information stemming from other neighbors is neglected, which begets the consideration of alternative, possibly more realistic approaches. Here we show that strategy changes inspired not only by the performance of individual neighbors but rather by entire neighborhoods introduce a qualitatively different evolutionary dynamics that is able to support the stable existence of very small cooperative clusters. This leads to phase diagrams that differ significantly from those obtained by means of pairwise strategy updating. In particular, the survivability of cooperators is possible even by high temptations to defect and over a much wider uncertainty range. We support the simulation results by means of pair approximations and analysis of spatial patterns, which jointly highlight the importance of local information for the resolution of social dilemmas.Comment: 9 two-column pages, 5 figures; accepted for publication in Scientific Report

Cubically convergent methods for selecting the regularization parameters in linear inverse problems

AbstractWe present three cubically convergent methods for choosing the regularization parameters in linear inverse problems. The detailed algorithms are given and the convergence rates are estimated. Our basic tools are Tikhonov regularization and Morozov's discrepancy principle. We prove that, in comparison with the standard Newton method, the computational costs for our cubically convergent methods are nearly the same, but the number of iteration steps is even less. Numerical experiments for an elliptic boundary value problem illustrate the efficiency of the proposed algorithms

The Cyclostationary Characteristic Analysis of the Time-Frequency Overlapped Signal in Single-Channel

AbstractThe characteristic analysis of the time-frequency overlapped signal (TFOS) in single-channel is a powerful challenge in electronic countermeasures. So, in this paper, the time-frequency overlapped degrees (Pt, Pf) of signals are proposed to measure the level overlapped of in time domain and frequency domain. Afterwards, based on cyclostationary principle, the proposition about the cyclostationary characteristic of TFOS is proved. Moreover, the cyclic spectrum of TFOS is deduced. Theoretical analysis and experimental results show that the linear sum of multicyclostationary signals is still cyclostationary signal

Numerical analysis of a time discretized method for nonlinear filtering problem with L\'evy process observations

In this paper, we consider a nonlinear filtering model with observations driven by correlated Wiener processes and point processes. We first derive a Zakai equation whose solution is a unnormalized probability density function of the filter solution. Then we apply a splitting-up technique to decompose the Zakai equation into three stochastic differential equations, based on which we construct a splitting-up approximate solution and prove its half-order convergence. Furthermore, we apply a finite difference method to construct a time semi-discrete approximate solution to the splitting-up system and prove its half-order convergence to the exact solution of the Zakai equation. Finally, we present some numerical experiments to demonstrate the theoretical analysis

Organizational Network Evolution and Governance Strategies in Megaprojects

The organization is the key factor for megaprojects in which thousands of connections and relations intertwine and influence the project performance. However, organizational evolution in megaprojects has not been fully studied. This study investigates the evolution of the organizational network of a megaproject in China using social network analysis (SNA), and then proposes corresponding governance strategies. The result shows that megaproject organizations evolve towards more connected networks but are differentiated for various investors. For government invested projects, the organizational network is well connected, cooperative, yet unstable and require strategic long-term governance policies; for private invested projects, the network is stable, but collaboration among participants is low, which indicates a need to establish collaborative governance structures. The result complements the organizational evolution theory for megaprojects and offers effective strategies for governing megaproject organizations. This study also helps practitioners better understand the nature and characteristics of megaproject organizations.

Exploring the social legitimacy of urban road PPPs in Nigeria

Public–private partnerships (PPPs) have become an effective and efficient contractual agreement between the state and the private sector for providing infrastructure services. Yet, their social acceptance and legitimacy are questionable. Communities accept such changes to their social contract with the government only if the PPPs are perceived to be legitimate as public institutions are not trusted by the communities. As a result, the disappointments and controversial underperformance of PPPs in Nigeria, like most developing countries, have been generally associated with community opposition due to any agency or competence-related failure. Hence, the need for this study. Drawing on data from two urban road PPPs in Nigeria, we identify the following three deeply internalised shared beliefs that shape a community group’s perceptions and attitudes towards an infrastructure built by PPPs in their neighbourhood: the public services should be provided for free, PPPs are created mainly to serve perceived ‘corrupt’ politicians and public institutions are not effective and efficient in service delivery. These beliefs, combined with the community’s structural power, explain why some community groups oppose (or support) infrastructure PPPs within their proximity, and the growing legitimacy challenge PPPs face. Our paper in this regard provides a guidance for designing effective and targeted community engagement strategies for PPP projects and contributed to PPP stakeholder management and mainstream stakeholder management research

Existence of Solutions of a Discrete Fourth-Order Boundary Value Problem

Let a,b be two integers with b-a≥5 and let 𝕋2={a+2,a+3,…,b-2}. We show the existence of solutions for nonlinear fourth-order discrete boundary value problem Δ4u(t-2)=f(t,u(t), Δ2u(t-1)), t∈𝕋2, u(a+1)=u(b-1)=Δ2u(a)=Δ2u(b-2)=0 under a nonresonance condition involving two-parameter linear eigenvalue problem. We also study the existence and multiplicity of solutions of nonlinear perturbation of a resonant linear problem