Analysis of the Heterogeneous Vectorial Network Model of Collective Motion

We analyze the vectorial network model, a stochastic protocol that describes collective motion of groups of agents, randomly mixing in a planar space. Motivated by biological and technical applications, we focus on a heterogeneous form of the model, where agents have different propensity to interact with others. By linearizing the dynamics about a synchronous state and leveraging an eigenvalue perturbation argument, we establish a closed-form expression for the mean-square convergence rate to the synchronous state in the absence of additive noise. These closed-form findings are extended to study the effect of added noise on the agents' coordination, captured by the polarization of the group. Our results reveal that heterogeneity has a detrimental effect on both the convergence rate and the polarization, which is nonlinearly moderated by the average number of connections in the group. Numerical simulations are provided to support our theoretical findings.</p

High-Resolution Agent-Based Modeling of COVID-19 Spreading in a Small Town

Amid the ongoing COVID-19 pandemic, public health authorities and the general population are striving to achieve a balance between safety and normalcy. Ever changing conditions call for the development of theory and simulation tools to finely describe multiple strata of society while supporting the evaluation of “what-if” scenarios. Particularly important is to assess the effectiveness of potential testing approaches and vaccination strategies. Here, an agent-based modeling platform is proposed to simulate the spreading of COVID-19 in small towns and cities, with a single-individual resolution. The platform is validated on real data from New Rochelle, NY—one of the first outbreaks registered in the United States. Supported by expert knowledge and informed by reported data, the model incorporates detailed elements of the spreading within a statistically realistic population. Along with pertinent functionality such as testing, treatment, and vaccination options, the model accounts for the burden of other illnesses with symptoms similar to COVID-19. Unique to the model is the possibility to explore different testing approaches—in hospitals or drive-through facilities—and vaccination strategies that could prioritize vulnerable groups. Decision-making by public authorities could benefit from the model, for its fine-grain resolution, open-source nature, and wide range of features

Buckling and postbuckling of magnetoelastic flat plates carrying an electric current

AbstractThe basic equations of a fully nonlinear theory of electromagnetically conducting flat plates carrying an electric current and exposed to a magnetic field of arbitrary orientation are derived. The relevant equations have been obtained by considering that both the elastic and electromagnetic media are homogeneous and isotropic. The geometrical nonlinearities are considered in the von-Kármán sense, and the soft ferromagnetic material of the plate is assumed to feature negligible hysteretic losses. Based on the electromagnetic and elastokinetic field equations, by using the standard averaging methods, the 3-D coupled problem is reduced to an equivalent 2-D one, appropriate to the theory of plates. Having in view that the elastic structures carrying an electric current are prone to buckling, by using the presently developed theory, the associated problems of buckling and postbuckling are investigated. In this context, the problem of the electrical current inducing the buckling instability of the plate, and its influence on the postbuckling behavior are analyzed. In the same context, the problem of the natural frequency–electrical current interaction of flat plates, as influenced by a magnetic field is also addressed

Cellulose-based magnetoelectric composites

Since the first magnetoelectric polymer composites were fabricated more than a decade ago, there has been a reluctance to use piezoelectric polymers other than poly(vinylidene fluoride) and its copolymers due to their well-defined piezoelectric mechanism and high piezoelectric coefficients that lead to superior magnetoelectric coefficients of > 1 V.cm−1 Oe−1. This is the current situation despite the potential for other piezoelectric polymers, such as natural biopolymers, to bring unique, added-value properties and functions to magnetoelectric composite devices. Therefore, we demonstrate a cellulose-based magnetoelectric laminate composite that produces considerable magnetoelectric coefficients of 1.5 V.cm−1 Oe−1 at low magnetic fields. Simple solution processing induces alignment of cellulose fibrils, leading to amplification of nanoscale piezoelectric domains and the magnetoelectric coefficient. The magnetoelectric frequency line shape shows a Fano-resonance that is ubiquitous in the field of physics, such as photonics, though never experimentally observed in magnetoelectric composites. This fundamental phenomenon is due to the inherent chemical structure of cellulose and important for understanding the magnetoelectric mechanisms. The work successfully demonstrates the concept of exploring new advances in using biopolymers in magnetoelectric composites, particularly cellulose, which is increasingly employed as a renewable, low-cost, easily processable and degradable material.The authors would like to acknowledge the financial support from the ARC Australian Research Fellowship (A/Prof. Michael Higgins) and ARC DP110104359 and ARC Centre of Excellence for Electromaterials Science (ACES, Project Number CE 140100012), University of Wollongong (UOW) We acknowledge assistance from Yi Du and Long Ren (UOW) for scanning electron microscopy. The authors would also like to acknowledge the FCT - Fundação para a Ciência e Tecnologia -for financial support under project PTDC/EEI-SII/5582/2014 and FCTgrant SFRH/BPD/96227/2013 (PM). SLM thanks financial support from the Basque Government Industry Department under the ELKARTEK Program and the Diputación Foral de Bizkaia for finantial support under the Bizkaia Talent program; European Union’s Seventh Framework Programme; Marie Curie Actions – People; Grant agreement nº 267230. like to acknowledge the FCT - Fundação para a Ciência e Tecnologia - for financial support under project PTDC/EEI - SII/5582/2014 and FCT grant SFRH/BPD/96227/2013 (PM). SLM thanks financial support from the Basque Government Industry Department under the ELKARTEK Program and the Diputación Foral de Bizkaia for finantial support under the Bizkaia Talent program; European Union’s Seventh Framework Programme; Marie Curie Actions – People; Grant agreement nº 267230info:eu-repo/semantics/publishedVersio