Showing papers by "Francesco Amato published in 2006"

Robust Control of Linear Systems Subject to Uncertain Time-Varying Parameters

Abstract: Linear Time-Varying Systems- Quadratic Stability- Systems Depending on Bounded Rate Uncertainties- Controller Design- Discrete-Time Systems

Finite-Time Control of Linear Systems: A Survey

Abstract: This chapter illustrates various finite-time analysis and design problems for linear systems. Most of this work deals with continuous-time systems. First, some conditions for finite-time stability and boundedness are presented; then we turn to the design problem. In this context, we consider both the state feedback and the output feedback synthesis. For both cases, we end up with some sufficient conditions involving linear matrix inequalities (both algebraic and differential). The last section of the chapter extends the previous results to discrete-time systems.

Finite-Time Output Feedback Control of Linear Systems via Differential Linear Matrix Conditions

Abstract: This paper deals with the finite-time output feedback control problem for continuous-time, time-varying linear systems. Sufficient conditions for the existence of a controller which finite-time stabilizes the closed loop system are provided, both for the state feedback and the output feedback case. Such conditions are given in terms of a feasibility problem involving Riccati differential equations and differential linear matrix inequalities.

Multiscale modeling of protein transport in silicon membrane nanochannels. Part 1. Derivation of molecular parameters from computer simulations

Abstract: We report in this account our efforts in the development of a novel multiscale simulation tool for integrated nanosystem design, analysis and optimization based on a three-tiered modeling approach consisting of (i) molecular models, (ii) atomistic molecular dynamics simulations, and (iii) dynamical models of protein transport at the continuum scale. In this work we used molecular simulations for the analysis of lysozyme adsorption on a pure silicon surface. The molecular modeling procedures adopted allowed (a) to elucidate the specific mechanisms of interaction between the biopolymer and the silicon surface, and (b) to derive molecular energetic and structural parameters to be employed in the formulation of a mathematical model of diffusion through silicon-based nanochannel membranes, thus filling the existing gap between the nano—and the macroscale.

Multiscale modeling of protein transport in silicon membrane nanochannels. Part 2. From molecular parameters to a predictive continuum diffusion model

Abstract: Transport and surface interactions of proteins in nanopore membranes play a key role in many processes of biomedical importance. Although the use of porous materi- als provides a large surface-to-volume ratio, the efficiency of the operations is often determined by transport behavior, and this is complicated by the fact that transport paths (i.e., the pores) are frequently of molecular dimensions. Under these conditions, a protein diffusion can be slower than predicted from Fick law. The main contribution of this paper is the development of a mathematical model of this phenomenon, whose parameters are computed via molecular modeling, as described Part 1. Our multiscale modeling methodology, val- idated by using experimental results related to the diffusion of lysozyme molecules, constitutes an "ab initio" recipe, for which no experimental data are needed to predict the protein release, and can be tailored in principle to match any differ- ent protein and any different surface, thus filling gap between the nano and the macroscale.

On the Region of Asymptotic Stability of Nonlinear Quadratic Systems

Abstract: This paper considers the following problem: given a nonlinear quadratic system and a certain box containing the origin of the state space, determine whether this box belongs to the Region of Asymptotic Stability of the zero equilibrium point of the system under consideration. Quadratic systems play an important role in the modelling of a wide class of nonlinear processes (electrical, robotic, biological, etc.). For such systems it is of mandatory importance not only to determine whether the origin of the state space is locally asymptotically stable but also to ensure that the operative range is included into the convergence region of the equilibrium. The proposed algorithm requires the solution of a suitable feasibility problem involving Linear Matrix Inequalities constraints. Some examples illustrate the effectiveness of the proposed procedure.

Characterization Methods for Quality Control of Nanopore and Nanochannel Membranes

Abstract: Nanotechnology is considered a fascinating subject not only by scientists, but also by people not involved in research. Likely, the appeal derives from common people thinking of nanotech devices as “invisible, mysterious objects”, capable of accomplishing complex tasks. Such a mysterious feeling can be explained by the fact that nanodevices features cannot be entrapped, because of their dimensions, by the common experience of human sensing, like other systems, exhibiting much more complex structures or functions, but macroscopic dimensions (e.g. airplanes, robots, skyscrapers).

A Versatile Mechatronic Tool for Minimally Invasive Surgery

Abstract: This paper describes a novel handheld mechatronic tool for minimally invasive surgery (MIS) able to assist the surgeon in several surgical acts and enhancing his (or her) dexterity and sensitivity. The main feature of this tool is the limitation of the risk of damage of the biological tissues in a plurality of procedures of manipulation (dissection, blunt dissection, pulling, stretching and stripping), of suture and cutting, in which the actuators included inside the tool assist the surgeon in performing these surgical acts. For this purpose, the mechatronic tool is equipped with an embedded microcontroller and sensors measuring the operating forces, which enable the closed loop force and torque control of the tool- tissue interaction. Through the consciousness and the direct control of the interaction forces, the surgeon can manipulate tissues selectively by the application of the operating forces on the basis of the surgical needs and of the tissue consistence. In particular, this paper discusses the design steps performed via a virtual prototyping approach implemented in a MATLAB/Simulinktrade environment and composed of kinematic, dynamical modeling and control system synthesis. The advantages in terms of simplification of the surgical act, resulting from the properties of servo-assistance of the tool, have been shown by the use of a preliminary version of the tool prototype in a simulation, performed by a pelvi trainer, that has involved complex tasks as suturing and knot tying

Modeling the cell cycle of fission yeast by means of piecewise linear systems

Abstract: Biological process modeling requires the use of a non-LTI description On the other hand, experimental data suggest that the behavior of many biological systems can be described with good approximation by means of piecewise Linear Time-Invariant (LTI) models On the basis of these considerations, the present work focuses on the problem of analyzing a set of experimental data and identifying the points where discontinuous phenomena occur A validation of the technique is provided exploiting the well established cell cycle model of fission yeast by Novak and Tyson

Release of Proteins from Nanochannel Delivery Systems: A Coupled Many-Scale Simulation - Experimental Investigation

Abstract: Transport and surface interactions of proteins in nanopore membranes play a key role in many processes of biomedical importance. Although the use of porous materials provides a large surface-to-volume ratio, the efficiency of the operations is often determined by transport behavior, and this is complicated by the fact that transport paths (i.e., the pores) are frequently of molecular dimensions. Under these conditions, wall effects become significant, with the mobility of molecules being affected by hydrodynamic interactions between protein molecules and the wall. Modeling of transport in pores is normally carried out at the continuum level, making use of such parameters as hindrance coefficients; these in turn are typically estimated using continuum methods applied at the level of individual diffusing particles. In this work we coupled experimental evidences to manyscale molecular simulations for the analysis of hen egg-white lysozyme adsorption/diffusion through a microfabricated silicon membrane, having pores of nanometric size in only one dimension. Our joint efforts allowed us a) to elucidate the specific mechanisms of interaction between the biopolymer and the silicon surface, and b) to derive molecular energetic and structural parameters to be employed in the formulation of a mathematical model of diffusion, thus filling the gap between the nano- and the macroscale.