Active semiflexible polymer under shear flow

The dynamic behavior of a self-propelled semiflexible filament of length L is con- sidered under the action of a linear shear flow. The system is studied by using Brownian multi-particle collision dynamics. The system can be characterized in terms of the persistence length Lp of the chain, of the Peclet number, and of the Weissenberg number. The quantity Lp/L measures the bending rigidity of the polymer, the Peclet number Pe is the ratio of active force times L to thermal energy, and the Weissenberg number Wi characterizes the flow strength over thermal effects.

Interpolation-based, minimum-time piecewise constant control of linear continuous-time SISO systems

We present a novel approach to the system inversion problem for linear, scalar (i.e. single-input, single-output, or SISO) plants. The problem is formulated as a constrained optimization program, whose objective function is the transition time between the initial and the final values of the system's output, and the constraints are (i) a threshold on the input intensity and (ii) the requirement that the system's output interpolates a given set of points. The system's input is assumed to be a piecewise constant signal.

Traveling Band Solutions in a System Modeling Hunting Cooperation

A classical Lotka-Volterra model with the logistical growth of prey-and-hunting coopera- tion in the functional response of predators to prey was extended by introducing advection terms, which included the velocities of animals. The effect of velocity on the kinetics of the problem was analyzed. In order to examine the band behavior of species over time, traveling wave solutions were introduced, and conditions for the coexistence of both populations and/or extinction were found. Numerical simulations illustrating the obtained results were performe

A forecasting model for the porosity variation during the carbonation process

In this paper we introduce a mathematical model of concrete carbonation Portland cement specimens. The main novelty of this work is to describe the intermediate chemical reactions, occurring in the carbonation process of concrete, involving the interplay of carbon dioxide with the water present into the pores. Indeed, the model here proposed, besides describing transport and diffusion processes inside the porous medium, takes into account both fast and slow phenomena as intermediate reactions of the carbonation process.

Random Walk in Physics

Abbiamo oggi una pletora di libri molto popolari su argomenti come i buchi neri, i viaggi nel tempo, le onde gravitazionali, il Big Bang, il bosone di Higgs, il multiverso. Questo libro segue un’altra strada, e si propone di dare una spiegazione informale e semplice di alcune delle idee della fisica e della matematica moderne che, nonostante la loro importanza concettuale e pratica, non sono trattate nei libri più popolari.