Vesicles are involved in a vast variety of transport processes in living organisms. Additionally, they serve as a model for the dynamics of cell suspensions. Predicting the rheological properties of their suspensions is still an open question, as even the interaction of pairs is yet to be fully understood. Here we analyse the effect of a single vesicle, undergoing tank-treading motion, on its surrounding shear flow by studying the induced disturbance field $\delta \vec{V}$, the difference between the velocity field in its presence and absence. The comparison between experiments and numerical simulations reveals an impressive agreement. Tracking ridges in the disturbance field magnitude landscape, we identify the principal directions along which the velocity difference field is analysed in the vesicle vicinity. The disturbance magnitude is found to be significant up to about 4 vesicles radii and can be described by a power law decay with the distance $d$ from the vesicle $ \| \delta \vec{V} \| \propto d^{-3/2}$. This is consistent with previous experimental results on the separation distance between two interacting vesicles under similar conditions, for which their dynamics is altered. This is an indication of vesicles long-range effect via the disturbance field and calls for the proper incorporation of long-range hydrodynamic interactions when attempting to derive rheological properties of vesicle suspensions.

The obstacles to the E-Mobility (EM)'s development are widely discussed both in scientific and in industrial fields. Approaches to overcome these obstacles are still not consolidate. At the same time, it is not so clear, what Business Models (BM) are more sustainable for the owners of Charging Infrastructure (CI). With the aim to support the development of charging network (CN), the authors propose a new BM based on intelligent, collaborative and digital services for all actors of the value chain. The implementation of this BM starts with the development of a decisional structure (DS) and the sharing of data and information among all operators that are involved into the charging process. The main elements of the model are explained and the first results of implementation are given. Future development are discussed to enrich the research and to supply at industrial field a useful tool to face decisions in the real context of CNs.

The authors propose a Multi Attributes approach to meet the demand of personalized tourist tours into cultural cities. Respecting to others works present into the literature, in this paper the decisional process includes two phases and a high number of variables that don't increase the complexity of the problem. A real application in an Italian city, Florence, is presented to demonstrate the great potential of this system into real context. The first phase of optimization is solved applying an innovative Genetic Algorithm, the second one a Multi Criteria Method, Analytic Hierarchy Process (AHP). The combination of these two approach gives flexibility to the system with respect to number of variables and allow to return a good solution for tourist in few second of computational time.

A new algorithm for the solution of free surface flows with large front deformation and fragmentation is presented. The algorithm is obtained by coupling a classical Finite Volume (FV) approach, that discretizes the Navier-Stokes equations on a block structured Eulerian grid, with an approach based on the Smoothed Particle Hydrodynamics (SPH) method, implemented in a Lagrangian framework. The coupling procedure is formulated in such a way that each solver is applied in the region where its intrinsic characteristics can be exploited in the most efficient and accurate way: the FV solver is used to resolve the bulk flow and the wall regions, whereas the SPH solver is implemented in the free surface region to capture details of the front evolution. The reported results clearly prove that the combined use of the two solvers is convenient from the point of view of both accuracy and computing time.

The aim of the present paper is the analysis of simplified boundary conditions to be used in numerical simulations, to take into account blockage effects for wind tunnel experiments of large scale wind tur- bines. The goal is the development of an efficient and reliable tool to be used to correct data obtained from experiments where the blockage coefficient is high and/or the turbine is highly loaded, for which traditional correction coefficients (derived from the Glauert theory or its more recent versions) fail. Numerical simulations of the flow around a three-bladed model-scale wind turbine with horizontal axis are reported; in all test cases, the turbine diameter is comparable with test section dimensions, and therefore blockage effects are significant. The actual experiments were approximated numerically with a simplified wind tunnel geometry, that retains the symmetries of the isolated turbine simulation in a rotating frame and therefore allows steady state computations. To this end, two circular wind tunnel were tested: for the first, the radius was chosen to retain the same cross-section as the actual wind tunnel; in the second, its was set to be equal to half of the smallest cross-section dimension. The aerodynamic performances of the turbine, in terms of power and thrust coefficients, are analyzed and compared with available experimental data. Detailed analysis of the flow in the wake is also reported. Analogous simulations in an unbounded domain are also reported.

Conformational heterogeneity is key to the function of many biomacromolecules, but only a few groups have tried to characterize it until recently. Now, thanks to the increased throughput of experimental data and the increased computational power, the problem of the characterization of protein structural variability has become more and more popular. Several groups have devoted their efforts in trying to create quantitative, reliable and accurate protocols for extracting such information from averaged data. We analyze here different approaches, discussing strengths and weaknesses of each. All approaches can roughly be clustered into two groups: Those satisfying the maximum entropy principle and those recovering ensembles composed of a restricted number of molecular conformations. In the first case, the solution focuses on the features that are common to all the infinite solutions satisfying the experimental data; in the second case, the reconstructed ensemble shows the conformational regions where a large probability can be placed. The upper limits for conformational probabilities (MaxOcc) can also be calculated. We also give an overview of the mainstream experimental observables, with considerations on the assumptions underlying their usage.

The problem is addressed of the maximal integrability of the gradient of solutions to quasilinear elliptic equations, with merely measurable coefficients, in two variables. Optimal results are obtained in the framework of Orlicz spaces, and in the more general setting of all rearrangement-invariant spaces. Applications to special instances are exhibited, which provide new gradient bounds, or improve certain results available in the literature.

Sono state esposte le sintesi delle conoscenze scientifiche acquisite sino ad oggi sulle Antiche Vie dell'Ambra, dal Mesolitico fino all'Antica Roma e dal Mar Baltico all'Europa Meridionale, al Mar Nero ed al Medio Oriente, con riferimenti ai ritrovamenti più recenti, ai giacimenti, con particolare riguardo all'ambra baltica, e sono state avanzate contemporaneamente ipotesi o riferimenti sui tragitti relativi. Una particolare evidenza è stata data alle vie che attraverso lo scambio commerciale hanno determinato la diffusione delle diverse culture fra i popoli e quindi maggior valore assumono in questo contesto le antichissime vie di epoche in cui i contatti e la comunicazione fra i popoli erano in dipendenza soprattutto delle vie del commercio. Grande importanza hanno assunto, alla luce delle superiori considerazioni, le vie che in epoca protostorica, ed in particolare nelle età del Bronzo e del Ferro, hanno consentito e caratterizzato i commerci dell'Ambra, oltreché di altri materiali, dal Mar Baltico, all'Adriatico, all'Egeo, al Mar Nero ed al Medio Oriente, mettendo in contatto popoli e culture completamente diversi fra loro, contribuendo senza dubbio allo sviluppo delle civiltà e delle conoscenze. Le vie di pace, come quelle dell'ambra, hanno sempre generato cultura.

We propose a numerical method to solve the Wigner equation in quantum systems of spinless, non-relativistic particles. The method uses a spectral decomposition into L-2(R-d) basis functions in momentum-space to obtain a system of first-order advection-reaction equations. The resulting equations are solved by splitting the reaction and advection steps so as to allow the combination of numerical techniques from quantum mechanics and computational fluid dynamics by identifying the skew-hermitian reaction matrix as a generator of unitary rotations. The method is validated for the case of particles subject to a one-dimensional (an-)harmonic and Morse potential using finite-differences for the advection part. Thereby, we verify the second order of convergence and observe non-classical behavior in the evolution of the Wigner function. (C) 2015 Elsevier Inc. All rights reserved.

Cooperativity effects have been proposed to explain the non-local rheology in the dynamics of soft jammed systems. Based on the analysis of the free-energy model proposed by L. Bocquet, A. Colin and A. Ajdari, Phys. Rev. Lett., 2009, 103, 036001, we show that cooperativity effects resulting from the nonlocal nature of the fluidity (inverse viscosity) are intimately related to the emergence of shear-banding configurations. This connection materializes through the onset of inhomogeneous compact solutions (compactons), wherein the fluidity is confined to finite-support subregions of the flow and strictly zero elsewhere. The compacton coexistence with regions of zero fluidity ("non-flowing vacuum") is shown to be stabilized by the presence of mechanical noise, which ultimately shapes up the equilibrium distribution of the fluidity field, the latter acting as an order parameter for the flow-noflow transitions occurring in the material.

In this article, we study in detail the fluid dynamics system proposed in Clarelli et al. (2013, J. Math. Biol., 66, 1387-1408) to model the formation of cyanobacteria biofilms. After analysing the linear stability of the unique non-trivial equilibrium of the system, we introduce in the model the influence of light and temperature, which are two important factors for the development of a cyanobacteria biofilm. Since the values of the coefficients we use for our simulations are estimated through information found in the literature, some sensitivity and robustness analyses on these parameters are performed. All these elements enable us to control and to validate the model we have already derived and to present some numerical simulations in the 2D and the 3D cases.

We apply the Z-control approach to a generalized predator prey system and consider the specific case of indirect control of the prey population. We derive the associated Z-controlled model and investigate its properties from the point of view of the dynamical systems theory. The key role of the design parameter A. for the successful application of the method is stressed and related to specific dynamical properties of the Z-controlled model. Critical values of the design parameter are also found, delimiting the lambda-range for the effectiveness of the Z-method. Analytical results are then numerically validated by the means of two ecological models: the classical Lotka-Volterra model and a model related to a case study of the wolf wild boar dynamics in the Alta Murgia National Park. Investigations on these models also highlight how the Z-control method acts in respect to different dynamical regimes of the uncontrolled model. (C) 2016 The Authors. Published by Elsevier Inc.

In this paper some recent mathematical models applied to material damage are reviewed. The complexity of damage processes related to Cultural Heritage materials creates the necessity of developing predictive tools in order to monitor and detect surface alterations even before they are visible by naked eyes. The proposed models, elaborated by a research group of the Institute of Applied Mathematics - Research Council of Italy, are based on partial differential equations and well capture the main features of chemical processes (copper corrosion and salt crystallization), which occur on different materials such as stone and copper.

We propose a version of the pure temporal epidemic type aftershock sequences (ETAS) model: the ETAS model with correlated magnitudes. As for the standard case, we assume the Gutenberg-Richter law to be the probability density for the magnitudes of the background events. Instead, the magnitude of the triggered shocks is assumed to be probabilistically dependent on that of the relative mother events. This probabilistic dependence is motivated by some recent works in the literature and by the results of a statistical analysis made on some seismic catalogs [Spassiani and Sebastiani, J. Geophys. Res. 121, 903 (2016)10.1002/2015JB012398]. On the basis of the experimental evidences obtained in the latter paper for the real catalogs, we theoretically derive the probability density function for the magnitudes of the triggered shocks proposed in Spassiani and Sebastiani and there used for the analysis of two simulated catalogs. To this aim, we impose a fundamental condition: averaging over all the magnitudes of the mother events, we must obtain again the Gutenberg-Richter law. This ensures the validity of this law at any event's generation when ignoring past seismicity. The ETAS model with correlated magnitudes is then theoretically analyzed here. In particular, we use the tool of the probability generating function and the Palm theory, in order to derive an approximation of the probability of zero events in a small time interval and to interpret the results in terms of the interevent time between consecutive shocks, the latter being a very useful random variable in the assessment of seismic hazard.

The distribution of the magnitudes of seismic events is generally assumed to be independent on past seismicity. However, by considering events in causal relation, for example, mother-daughter, it seems natural to assume that the magnitude of a daughter event is conditionally dependent on one of the corresponding mother events. In order to find experimental evidence supporting this hypothesis, we analyze different catalogs, both real and simulated, in two different ways. From each catalog, we obtain the law of the magnitude of the triggered events by kernel density. The results obtained show that the distribution density of the magnitude of the triggered events varies with the magnitude of their corresponding mother events. As the intuition suggests, an increase of the magnitude of the mother events induces an increase of the probability of having high values of the magnitude of the triggered events. In addition, we see a statistically significant increasing linear dependence of the magnitude means.

The understanding of water transport in graphene oxide (GO) membranes stands out as a major theoretical problem in graphene research. Notwithstanding the intense efforts devoted to the subject in the recent years, a consolidated picture of water transport in GO membranes is yet to emerge. By performing mesoscale simulations of water transport in ultrathin GO membranes, we show that even small amounts of oxygen functionalities can lead to a dramatic drop of the GO permeability, in line with experimental findings. The coexistence of bulk viscous dissipation and spatially extended molecular friction results in a major decrease of both slip and bulk flow, thereby suppressing the fast water transport regime observed in pristine graphene nanochannels. Inspection of the flow structure reveals an inverted curvature in the near-wall region, which connects smoothly with a parabolic profile in the bulk region. Such inverted curvature is a distinctive signature of the coexistence between single-particle zero-temperature (noiseless) Langevin friction and collective hydrodynamics. The present mesoscopic model with spatially extended friction may offer a computationally efficient tool for future simulations of water transport in nanomaterials. Copyright (C) EPLA, 2016

It is commonly agreed that the most challenging problems in modern science and engineering involve the concurrent and nonlinear interaction of multiple phenomena, acting on a broad and disparate spectrum of scales in space and time. It is also understood that such phenomena lie at the interface between different disciplines, such as physics, chemistry, material science and biology. The multiscale and multi-level nature of these problems commands a paradigm shift in the way they need to be handled, both conceptually and in terms of the corresponding problem-solving computational tools

Hybrid particle-continuum computational frameworks permit the simulation of gas flows by locally adjusting the resolution to the degree of non-equilibrium displayed by the flow in different regions of space and time. In this work, we present a new scheme that couples the direct simulation Monte Carlo (DSMC) with the lattice Boltzmann (LB) method in the limit of isothermal flows. The former handles strong non-equilibrium effects, as they typically occur in the vicinity of solid boundaries, whereas the latter is in charge of the bulk flow, where non-equilibrium can be dealt with perturbatively, i.e. according to Navier-Stokes hydrodynamics. The proposed concurrent multiscale method is applied to the dilute gas Couette flow, showing major computational gains when compared with the full DSMC scenarios. In addition, it is shown that the coupling with LB in the bulk flow can speed up the DSMC treatment of the Knudsen layer with respect to the full DSMC case. In other words, LB acts as a DSMC accelerator.This article is part of the themed issue 'Multiscale modelling at the physics-chemistry-biology interface'.

This article is part of the themed issue 'Multiscale modelling at the physics-chemistry-biology interface'. We discuss a unified mesoscale framework (chimaera) for the simulation of complex states of flowing matter across scales of motion. The chimaera framework can deal with each of the three macro-meso-micro levels through suitable 'mutations' of the basic mesoscale formulation. The idea is illustrated through selected simulations of complex micro-and nanoscale flows.

This article is part of the themed issue 'Multiscale modelling at the physics-chemistry-biology interface'. Hybrid particle-continuum computational frameworks permit the simulation of gas flows by locally adjusting the resolution to the degree of non-equilibrium displayed by the flow in different regions of space and time. In this work, we present a new scheme that couples the direct simulation Monte Carlo (DSMC) with the lattice Boltzmann (LB) method in the limit of isothermal flows. The former handles strong non-equilibrium effects, as they typically occur in the vicinity of solid boundaries, whereas the latter is in charge of the bulk flow, where non-equilibrium can be dealt with perturbatively, i.e. according to Navier-Stokes hydrodynamics. The proposed concurrent multiscale method is applied to the dilute gas Couette flow, showing major computational gains when compared with the full DSMC scenarios. In addition, it is shown that the coupling with LB in the bulk flow can speed up the DSMC treatment of the Knudsen layer with respect to the full DSMC case. In other words, LB acts as a DSMC accelerator.