Search results for "Parameter identification"

showing 10 items of 30 documents

Parameter identification of induction motor model by means of State Space-Vector Model Output Error Minimization

2014

This paper proposes a technique for the off-line estimation of the electrical parameters of the equivalent circuit of an Induction Machines (IM), and focuses on the application of an algorithm based on the minimization of a suitable cost function involving the differences between the measured stator current direct (sD) and quadrature (sQ) components and the corresponding estimated by the IM state model. This method exploits an entire start-up transient of the IM to estimate all of the 4 electrical parameters of the machine (Rs, Ls, σLs, Tr). It proposes also a set of tests to be made in order to estimate the variation of the magnetic parameters of the IM versus the rotor magnetizing current…

Engineeringgenetic structuresParameter identificationsaturation effects.Statorbusiness.industryRotor (electric)Function (mathematics)induction motorlaw.inventionQuadrature (mathematics)Settore ING-INF/04 - AutomaticalawControl theoryState spaceEquivalent circuitTransient (oscillation)businessInduction motor
researchProduct

A Sequential Quadratic Programming Method for Volatility Estimation in Option Pricing

2006

Our goal is to identify the volatility function in Dupire's equation from given option prices. Following an optimal control approach in a Lagrangian framework, we propose a globalized sequential quadratic programming (SQP) algorithm with a modified Hessian - to ensure that every SQP step is a descent direction - and implement a line search strategy. In each level of the SQP method a linear-quadratic optimal control problem with box constraints is solved by a primal-dual active set strategy. This guarantees L^1 constraints for the volatility, in particular assuring its positivity. The proposed algorithm is founded on a thorough first- and second-order optimality analysis. We prove the existe…

Hessian matrixMathematical optimizationLine searchComputer scienceMathematicsofComputing_NUMERICALANALYSISOptimal controlsymbols.namesakeValuation of optionsLagrange multipliersymbolsDescent directionVolatility (finance)Dupire equation parameter identification optimal control optimality conditions SQP method primal-dual active set strategySequential quadratic programming
researchProduct

NOVEL TOOLS FOR THE MECHANICAL ANALYSIS OF THIN PLATES AND RELEVANCE ON MEMBRANE-BASED TECHNOLOGIES

2020

Ion Exchange MembraneSettore ING-IND/26 - Teoria Dello Sviluppo Dei Processi ChimiciProfiled MembraneFluid-Structure InteractionThin PlateMembraneMembrane DeformationReverse ElectrodialysiElectrodialysiMeshfree methodLine Element-Less MethodMaterial parameter identificationFluid redistribution.Settore ICAR/08 - Scienza Delle Costruzioni
researchProduct

Analysis of Rectangular Orthotropic Membranes for Mechanical Properties Identification through Load-Displacement Data

2021

In this paper, an innovative procedure is introduced for the identification of the mechanical properties of orthotropic membranes based on load-displacement data. To this end, novel functional forms of the displacement components for rectangular membranes are appropriately introduced. Unknown coefficients of these displacement functions are determined, minimizing the total potential energy of the membrane. The energy method is then combined with an optimization procedure to estimate the elastic constants of the membranes in a straightforward manner. Specifically, a genetic algorithm is used to minimize a properly defined objective function directly related to the sought mechanical propertie…

Materials sciencebusiness.industryMechanical Engineering02 engineering and technologyStructural engineering021001 nanoscience & nanotechnologyOrthotropic materialBulge test Genetic algorithm Material parameter identification Membrane Orthotropic material Static responseIdentification (information)020303 mechanical engineering & transportsMembrane0203 mechanical engineeringMechanics of MaterialsBulge testGenetic algorithmStatic responseLoad displacement0210 nano-technologybusinessSettore ICAR/08 - Scienza Delle Costruzioni
researchProduct

Identification of linear parameter varying models

2002

We consider identification of a certain class of discrete-time nonlinear systems known as linear parameter varying system. We assume that inputs, outputs and the scheduling parameters are directly measured, and a form of the functional dependence of the system coefficients on the parameters is known. We show how this identification problem can be reduced to a linear regression, and provide compact formulae for the corresponding least mean square and recursive least-squares algorithms. We derive conditions on persistency of excitation in terms of the inputs and scheduling parameter trajectories when the functional dependence is of polynomial type. These conditions have a natural polynomial i…

Mechanical EngineeringGeneral Chemical EngineeringBiomedical EngineeringAerospace EngineeringIndustrial and Manufacturing EngineeringPolynomial interpolationScheduling (computing)Parameter identification problemLeast mean squares filterNonlinear systemControl and Systems EngineeringControl theoryLinear regressionApplied mathematicsElectrical and Electronic EngineeringMathematicsInternational Journal of Robust and Nonlinear Control
researchProduct

The Hu-Washizu variational principle for the identification of imperfections in beams

2008

This paper presents a procedure for the identification of imperfections of structural parameters based on displacement measurements by static tests. The proposed procedure is based on the well-known Hu–Washizu variational principle, suitably modified to account for the response measurements, which is able to provide closed-form solutions to some inverse problems for the identification of structural parameter imperfections in beams. Copyright © 2008 John Wiley & Sons, Ltd.

Numerical AnalysisMathematical optimizationEstimation theoryApplied MathematicsGeneral EngineeringSystem identificationInverse problemDisplacement (vector)static testsconcentrated damageIdentification (information)Exact solutions in general relativityVariational principleApplied mathematicsimperfectionsCalculus of variationsSettore ICAR/08 - Scienza Delle CostruzioniHu-Washizu variational principlestructural parameter identificationMathematicsInternational Journal for Numerical Methods in Engineering
researchProduct

A Numerical Method for an Inverse Problem Arising in Two-Phase Fluid Flow Transport Through a Homogeneous Porous Medium

2019

In this paper we study the inverse problem arising in the model describing the transport of two-phase flow in porous media. We consider some physical assumptions so that the mathematical model (direct problem) is an initial boundary value problem for a parabolic degenerate equation. In the inverse problem we want to determine the coefficients (flux and diffusion functions) of the equation from a set of experimental data for the recovery response. We formulate the inverse problem as a minimization of a suitable cost function and we derive its numerical gradient by means of the sensitivity equation method. We start with the discrete formulation and, assuming that the direct problem is discret…

Parameter identification problemFinite volume methodFlow (mathematics)DiscretizationNumerical analysisConjugate gradient methodApplied mathematicsBoundary value problemInverse problemMathematics
researchProduct

A linear approach for the nonlinear distributed parameter identification problem

1991

In identifying the nonlinear distributed parameters we propose an approach, which enables us to identify the nonlinear distributed parameters by just solving linear problems. In this approach we just need to identify linear parameters and then recover the nonlinear parameters from the identified linear parameters. An error estimate for the finite element approximation is derived. Numerical tests are also presented.

Parameter identification problemIdentification (information)Mathematical optimizationNonlinear systemDistributed parameter systemNonlinear parametersApplied mathematicsNumerical testsInverse problemPhysics::History of PhysicsFinite element methodMathematics
researchProduct

Identification for a general class of LPV Models

2000

Abstract In this paper we consider the problem of identifying discrete-time Linear Parameter Varying (LPV) models of non-linear or time-varying systems. LPV models are considered for their connection with the industrial practice of gain-scheduling. We assume that inputs, outputs and the scheduling parameters are measured, and a form of the functional dependence of the coefficients on the parameters is known. We show how the identification problem can be reduced to a linear regression so that a Least Mean Square identification algorithm can be reformulated. Conditions on the persistency of excitation in terms of the inputs and parameter trajectories are given to ensure the consistency of the…

Parameter identification problemLeast mean squares filterGain schedulingControl theoryLinear regressionMathematicsScheduling (computing)
researchProduct

Identification of linear parameter varying models

2003

We consider the problem of identifying discrete-time linear parameter varying models of nonlinear or time-varying systems. We assume that inputs, outputs and the scheduling parameters are measured, and a form of the functional dependence of the coefficients on the parameters. We show how the identification problem can be reduced to a linear regression, and we give conditions on persistency of excitation in terms of the inputs and parameter trajectories.

Parameter identification problemNonlinear systemIdentification (information)Control theoryMatrix algebraLinear regressionLinear systemScheduling (production processes)Applied mathematicsExcitationMathematics
researchProduct