1,077 research outputs found
Una complessa eredità: ricordando Fabrizio Frasnedi (1944-2015)
No full textIl volume raccoglie una serie di contributi in ricordo di Fabrizio Frasnedi a cinque anni dalla sua scomparsa.
Interventi di Gian Mario Anselmi, Bruno Capaci, Maria Rosaria Catino, Guido Conti, Cristiana De Santis, Yahis Martari, Chiara Panzieri, Michele Prandi, Rocco Ronchi, Alberto Sebastiani, Matteo Vial
SOLUTION OF THE H-INFINITY STEADY STATE RICCATI EQUATION FOR NON EXPONENTIALLY STABILIZABLE SYSTEMS
No full text
Designing sustainable diet plans by solving triobjective integer programs
No full textWe present an algorithm for triobjective nonlinear integer programs that combines the -constrained method with available oracles for biobjective integer programs. We prove that our method is able to detect the nondominated set within a finite number of iterations. Specific strategies to avoid the detection of weakly nondominated points are devised. The method is then used to determine the nondominated solutions of triobjective 0–1 models, built to design nutritionally adequate and healthy diet plans, minimizing their environmental impact. The diet plans refer to menus for school cafeterias and we consider the carbon, water and nitrogen footprints as conflicting objectives to be minimized. Energy and nutrient contents are constrained in suitable ranges suggested by the dietary recommendation of health authorities. Results obtained on two models and on real world data are reported and discussed
Dwell-time controllers for stochastic systems with switching Markov chain
No full textWe study the problem of feedback stabilization of a family of nonlinear stochastic systems with switching mechanism modeled by a Markov chain. We introduce a novel notion of stability under switching, which guarantees a given probability that the trajectories of the system hit some target set in finite time and remain thereinafter. Our main contribution is to prove that if the expectation of the time between two consecutive switching (dwell time) is "sufficiently large", then the system is stable under switching with guaranteed probability. We, illustrate this methodology by constructing measurement feedback controllers for a wide class of stochastic nonlinear systems. (c) 2005 Elsevier Ltd. All rights reserved
Discrete level set segmentation for pupil morphology characterization
No full textThe pupil morphological characteristics are of great interest for non invasive early diagnosis of the central nervous system response to environmental stimuli of different nature. Their evaluation in subjects suffering some typical diseases such as diabetes, Alzheimer disease, schizophrenia, drug and alcohol addiction is of concern. In this paper geometrical pupil features such as area, centroid coordinates, eccentricity, major and minor axes lengths are estimated by a procedure based on an image segmentation algorithm. It exploits the level set formulation of the related variational problem. A discrete set up of this problem is proposed: an arbitrary initial curve is evolved towards the unique optimal segmentation boundary by a difference equation. Numerical tests are performed on real pupillometry data taken in different illumination conditions showing a high degree of robustness of the shape parameters estimates
Stabilization and control of a flexible structure continuum model
No full textIn this paper the stabilization problem for a flexible slewing link is considered, leading to some interesting considerations about the use of positive real compensators. By modelling the structure motion as a set of first order differential equations on a proper Hilbert space, the authors study this problem in an infinite-dimensional setting by following two approaches. In the first one standard results on semigroups theory are considered, while in the second the authors use passivity arguments, directly related to the classical Lyapunov direct method. Control applications such as set-point motion and LQR are finally reviewe
Large deflection of a non-linear, elastic, asymmetric Ludwick cantilever beam subjected to horizontal force, vertical force and bending torque at the free end
No full textThe investigated cantilever beam is characterized by a constant rectangular cross-section and is subjected to a concentrated constant vertical load, to a concentrated constant horizontal load and to a concentrated constant bending torque at the free end. The same beam is made by an elastic non-linear asymmetric Ludwick type material with different behavior in tension and compression. Namely the constitutive law of the proposed material is characterized by two different elastic moduli and two different strain exponential coefficients. The aim of this study is to describe the deformation of the beam neutral surface and particularly the horizontal and vertical displacements of the free end cross-section. The analysis of large deflection is based on the Euler-Bernoulli bending beam theory, for which cross-sections, after the deformation, remain plain and perpendicular to the neutral surface; furthermore their shape and area do not change. On the stress viewpoint, the shear stress effect and the axial force effect are considered negligible in comparison with the bending effect. The mechanical model deduced from the identified hypotheses includes two kind of non-linearity: the first due to the material and the latter due to large deformations. The mathematical problem associated with the mechanical model, i.e. to compute the bending deformations, consists in solving a non-linear algebraic system and a non-liner second order ordinary differential equation. Thus a numerical algorithm is developed and some examples of specific results are shown in this paper. © Springer Science+Business Media Dordrecht 2014
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