Search results for "Linear system"
showing 10 items of 1558 documents
Model predictive control for continuous lactide ring‐opening polymerization processes
2020
International audience; Polylactic acid (PLA) is an attractive environment-friendly thermoplastic that is bio-sourced and biodegradable. PLA is industrially produced by the ring-opening polymerization of Lactide. This reaction is sensitive to drifts in the operating conditions and impurities in the raw materials that may affect the reaction rate as well as the polymer properties, which can be very costly in continuous processes. It is therefore crucial to employ a control strategy that allows recovering the nominal conditions and maintaining the desired properties and conversion level in case of drift. Three control strategies are discussed in this paper: Proportional-Integral controller (P…
Variable kinematics models and finite elements for nonlinear analysis of multilayered smart plates
2015
Abstract A variable kinematics approach for moderately large deflection analysis of smart magneto-electro-elastic multilayered plates is presented. The approach is based on the condensation of the electro-magnetic state into the plate kinematics, whose nonlinear strain–displacement relationships are expressed in the von Karman sense. This leads to models resulting in an effective mechanical plate, which takes the multifield coupling effects into account by the plate stiffness, inertia and loading characteristics, consistently defined as combinations of the layers material properties. By a unified approach, both equivalent single layer and layerwise models are developed formulating the assoc…
Supply chain modelling and analysis: an application of Latin square to a repeated coupling of non-linear differential equations
2011
In the last 50 years, Forrester’s system dynamics techniques have been adopted to analyse problems and find solutions for global supply chains. An important topic in production-inventory system modelling is the design of experiment. The aim of this paper is to present an application of a statistical technique of design of experiment, the Latin Square Design, to set a combination of input values for the initial-value problem of non-linear repeated coupling of first-order differential equations modelling a production-inventory system. This design permits to reduce the number of experiments while allowing statistical analysis for testing the significance of the studied parameters.
Influence of spatial delay on the modulational instability in a composite system with a controllable nonlinearity.
2017
A theoretical investigation of the modulational instability (MI) in a composite system with a nonlocal response function is presented. A composite system of silver nanoparticles in acetone is chosen, whose nonlinearity can be delicately varied by controlling the volume fraction of the constituents, thus enabling the possibility of nonlinearity management. A pump-probe counterpropagation configuration has been assumed, and the interplay between the competing nonlinearities and the nonlocalities in the MI dynamics is systematically explored. A different class of nonlocalities have been considered, and the study reveals that the nonlocality critically depends on the kind of nonlocal function. …
Observation of Kuznetsov-Ma soliton dynamics in optical fibre
2012
International audience; The nonlinear Schro¨dinger equation (NLSE) is a central model of nonlinear science, applying to hydrodynamics, plasma physics, molecular biology and optics. The NLSE admits only few elementary analytic solutions, but one in particular describing a localized soliton on a finite background is of intense current interest in the context of understanding the physics of extreme waves. However, although the first solution of this type was the Kuznetzov-Ma (KM) soliton derived in 1977, there have in fact been no quantitative experiments confirming its validity. We report here novel experiments in optical fibre that confirm the KM soliton theory, completing an important serie…
Thermal Stability of a DC/DC Converter with Inductor in Partial Saturation
2021
Inductors operated in quasi saturation in dc–dc converters allow reduction of the core size and realization costs; on the other hand, they imply an increase of dissipated power that can jeopardize the thermal stability of the converter. In this article, this issue is studied by a mathematical model able to represent both the inductor nonlinearity and its temperature dependence. The main losses, such as ohmic, skin effect and magnetic, are taken into account in the model. The inductor is characterized by a polynomial curve whose parameters are a function of the temperature. Finally, the whole converter is modeled and simulation results, obtained on a boost converter, are compared with experi…
Adaptive high-gain extended kalman filter and applications
2010
The work concerns the ``observability problem” --- the reconstruction of a dynamic process's full state from a partially measured state--- for nonlinear dynamic systems. The Extended Kalman Filter (EKF) is a widely-used observer for such nonlinear systems. However it suffers from a lack of theoretical justifications and displays poor performance when the estimated state is far from the real state, e.g. due to large perturbations, a poor initial state estimate, etc… We propose a solution to these problems, the Adaptive High-Gain (EKF). Observability theory reveals the existence of special representations characterizing nonlinear systems having the observability property. Such representations…
A Novel Self-organizing Neural Technique for Wind Speed Mapping
2009
Systems with high nonlinearities are, in general, very difficult to model. This is particularly true in geostatistics, where the problem of the estimation of a regionalized variable (RV) given only a small amount of measurement stations and a complex terrain surface is very challenging. This paper introduces a novel strategy, which couples the Curvilinear Component Analysis (CCA) and the Generalized Mapping Regressor (GMR). CCA, which is a nonlinear projector of a data manifold, is here used in order to find the intrinsic dimension of the data manifold, just giving an insight on the nonlinearities of the problem. This analysis drives the pre-processing of the data set used for the training …
The Analysis of Auxological Data by Means of Nonlinear Multivariate Growth Curves
1999
In this paper we treat the problem to analyse a data set constituted by multivariate growth curves for different subjects; thus in this context we deal with 3-way data tables. Nevertheless, it is not possible using factorial techniques proposed to deal with 3-way data matrices, because the observations are generally not equally spaced; moreover a multilevel approach founded on polynomial models is not suitable to deal with intrinsic nonlinear models. We propose a non-factorial technique to analyse auxological data sets using an intrinsic nonlinear multivariate growth model with autocorrelated errors. The application to a real data set of growing children gave easily interpretable results.
Integration of Two Multiobjective Optimization Methods for Nonlinear Problems
2003
In this paper, we bring together two existing methods for solving multiobjective optimization problems described by nonlinear mathematical models and create methods that benefit from both heir strengths. We use the Feasible Goals Method and the NIMBUS method to form new hybrid approaches. The Feasible Goals Method (FGM) is a graphic decision support tool that combines ideas of goal programming and multiobjective methods. It is based on the transformation of numerical information given by mathematical models into a variety of feasible criterion vectors (that is, feasible goals). Visual interactive display of this variety provides information about the problem that helps the decision maker to…