Non-pharmacological interventions (NPIs), and in particular social distancing, in conjunction with the advent of effective vaccines at the end of 2020, aspired for the development of a protective immunity shield against the spread of SARS-CoV-2. The main question rose is related to the deployment strategy of the two doses with respect to the imposed NPIs and population age. In this study, an extended (SEIR) agent-based model on small-world networks was employed to identify the optimal policies against Covid 19 pandemic, including social distancing measures and mass vaccination. To achieve this, a new methodology is proposed to solve the inverse problem of calibrating an agent's infection rate with respect to vaccination efficacy. The results show that deploying the first vaccine dose across the whole population is sufficient to control the epidemic, with respect to deaths, even for low number of social contacts. Moreover, for the same range of social contacts, we found that there is an optimum ratio of vaccinating ages > 65 over the younger ones of 4/5.
The engineering applications of the innovative materials, such as carbon nanotubes (CNTs) and graphene sheets, constitute a developing branch of the modern science. CNTs, in particular, exhibit extraordinarily mechanical properties capable of making them a reliable material for the above applications. The simulation of the mechanical response of a CNT is effectively conducted by a generalized beam model. This work investigates the response of a CNT, subjected to a static loading, by means of a gradient beam model. Given that the existence of a boundary layer is demonstrated by the analytical solutions of the aforementioned problem, the interior penalty discontinuous Galerkin finite element methods (IPDGFEMs) are crucial to its solution. The hp‐version IPDGFEMs are developed in this study for the solution of a static gradient elastic beam in bending, derived from two different equilibrium formulations, for the first time. An a priori error analysis is also performed for the above method, and numerical simulations are then carried out. A comparison is finally drawn between the exact deflection and those of the IPDGFEM and the conforming C2‐continuous finite element method (C2CFEM) for a number of discretizations and each length scale that is investigated. The deduced results highlight the suitability, the efficiency, and the accuracy of the investigated models over the already existing ones, and they have considerable significance for the engineering design in the range of micro and nanodimensions.
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