Recherche

Afficher tous les résultats pour

Accueil

Personne

Alireza Karimi

À propos
Confidentialité
Mentions légales

Graph Chatbot

Publications associées (165)

Fixed-order LPV Controller Design for Rejection of a Sinusoidal Disturbance with Time-varying Frequency

Alireza Karimi, Zlatko Emedi

A new method for the design of fixed-order Linear Parameter Varying (LPV) controllers with polytopic representation for LTI plants is proposed. The stability constraints for the closed-loop system are presented through a set of Linear Matrix Inequalities ( ...

2012

A solution to the flexible transmission benchmark by convex optimization

Alireza Karimi, Gorka Galdos Sanz de Galdeano

The flexible transmission benchmark was proposed in the European Journal of Control to evaluate some robust digital control approaches in 1995. With progress in convex optimization algorithms new methods for robust controller design are developed. A recent ...

SAGE Publications2012

Mechanical and microstructural integrity of nickel-titanium and stainless steel laser joined wires

Jean-Marie Drezet, Aïcha Hessler-Wyser, Michel Rappaz, Alireza Karimi, Jonas Vannod

The biomedical industry shows increasing interest in the joining of dissimilar metals, especially with the aim of developing devices that combine different mechanical and corrosive properties. As an example, nickel titanium shape memory alloys joined to st ...

Elsevier2011

Texture change through film thickness and off-axis accommodation of (002) planes

Ayat Karimi, Alireza Karimi, Akshath Raghu Shetty

We present our recent experimental results on the formation of off-axis texture and crystallographic tilting of crystallites that take place in thin film of transition metal nitrides. For this purpose, the microstructural development of TiAlN film was stud ...

2011

Correlation between anionic substitution and structural properties in AlCr(OxN1-x) coatings deposited by lateral rotating cathode arc PVD

Alireza Karimi, Hossein Najafi

The influence of oxygen content on the properties of cathodic arc-deposited AlCr(OxN1-x) coatings has been studied. All samples were prepared in a nitrogen-rich mixture of N-2 and O-2 at 550 degrees C using lateral rotating arc cathodes (LARC) technology t ...

2011

Microstructure of Al95.5Cr2.5Si2(N1-xOx) thin films covering from nitrides to oxides

Alireza Karimi, Hossein Najafi

Al95.5Cr2.5Si2(N1-xOx) thin films were prepared using pulsed DC-magnetron sputtering at 650 degrees C by changing the oxygen to nitrogen ratio (O-2/(O-2 + N-2)) in the reactive gas. The obtained films were characterized by various techniques including XRD, ...

2011

Effect of deposition angle on the structure and properties of pulsed-DC magnetron sputtered TiAlN thin films

Marco Cantoni, Alireza Karimi, Akshath Raghu Shetty

This article reports the comparison of structure and properties of titanium aluminum nitride (TiAlN) films deposited onto Si(100) substrates under normal and oblique angle depositions using pulsed-DC magnetron sputtering. The substrate temperature was set ...

2011

Unified cluster expansion method applied to the configurational thermodynamics of cubic Ti1-xAlxN

Alireza Karimi

We study the thermodynamics of cubic Ti1-xAlxN using a unified cluster expansion approach for the alloy problem. The purely configurational part of the alloy Hamiltonian is expanded in terms of concentration- and volume-dependent effective cluster interact ...

2011

Direct data-driven H2 − H∞ loop-shaping

Alireza Karimi

In this paper, a direct data-driven approach is proposed to tune fixed-order controllers for unknown stable LTI plants in a mixed-sensitivity loop-shaping problem. The method requires a single set of input-output samples and it is based on simple convex op ...

2011

On identification methods for direct data-driven controller tuning

Alireza Karimi, Klaske van Heusden

In non-iterative data-driven controller tuning, a set of measured input/output data of the plant is used directly to identify the optimal controller that minimizes some control criterion. This approach allows the design of fixed-order controllers, but lead ...

Wiley-Blackwell2011

RST Controller Design by Convex Optimization Using Frequency-Domain Data

Roland Longchamp, Alireza Karimi, Gorka Galdos Sanz de Galdeano

A new robust fixed-order RST controller design approach by convex optimization is proposed in this paper. Only frequency-domain data are considered in the approach for linear time-invariant single-input single-output systems. It is shown that performance s ...

2011

Robust gain-scheduled blending control of raw-mix quality in cement industries

Michael Amrhein, Alireza Karimi, Vinicius De Oliveira

This paper addresses the control of the blending process in cement industries. This process can be modeled by a nonlinear multivariable system with large parametric uncertainty. Using a specific transformation, a linear parameter varying (LPV) model with s ...

Ieee Service Center, 445 Hoes Lane, Po Box 1331, Piscataway, Nj 08855-1331 Usa2011

Fixed-order H-infinity controller design for systems with ellipsoidal parametric uncertainty

Alireza Karimi, Arash Sadeghzadeh

In this paper, fixed-order robust H-infinity controller design for systems with ellipsoidal parametric uncertainty based on parameter dependent Lyapunov functions is studied. Using the concept of Strictly Positive Realness (SPRness) of transfer functions, ...

Taylor & Francis2011

Data-driven model reference control with asymptotically guaranteed stability

Dominique Bonvin, Alireza Karimi, Klaske van Heusden

This paper presents a data-driven controller tuning method that includes a set of constraints for ensuring closed-loop stability. The approach requires a single experiment and can also be applied to nonminimum-phase or unstable systems. The tuning scheme u ...

Wiley-Blackwell2011

Deposition and characterization of pulsed direct current magnetron sputtered Al95.5Cr2.5Si2 (N1-xOx) thin films

Alireza Karimi, Hossein Najafi

Aluminum rich oxynitride thin films were prepared using pulsed direct current (DC) magnetron sputtering from an Al95.5Cr2.5Si2 (at.%) target. Two series of films were deposited at 400 degrees C and 650 degrees C by changing the O-2/(O-2 + N-2) ratio in the ...

2010

Influence of oxygen content on structure and properties of multi-element AlCrSiON oxynitride thin films

Alireza Karimi

Multi-element oxynitrides of type Al-Cr-Si-O-N were prepared using r.f. magnetron sputtering from Al80Cr2.5Si17.5 (at.%) target composition and O-2/(O-2+N-2) gas flow ratio between 0 and 100%. Two series of samples varying from pure nitrides to pure oxides ...

2010

Linear Parameter Varying Iterative Learning Control with application to a Linear Motor System

Alireza Karimi, Mark Edward John Butcher

In this paper an Iterative Learning Control (ILC) algorithm is proposed for a certain class of Linear Parameter Varying (LPV) systems whose dynamics change between iterations. Consistency of the algorithm in the presence of stochastic disturbances is shown ...

Institute of Electrical and Electronics Engineers2010

Robust Controller Design by Convex Optimization based on Finite Frequency Samples of Spectral Models

Roland Longchamp, Alireza Karimi, Gorka Galdos Sanz de Galdeano

Some frequency-domain controller design problems are solved using a finite number of frequency samples. Consequently, the performance and stability conditions are not guaranteed for the frequencies between the frequency samples. In this paper, all possible ...

Ieee Service Center, 445 Hoes Lane, Po Box 1331, Piscataway, Nj 08855-1331 Usa2010

H∞ Controller Design for Spectral MIMO Models by Convex Optimization

Roland Longchamp, Alireza Karimi, Gorka Galdos Sanz de Galdeano

A new method for robust ﬁxed-order H∞ controller design by convex optimization for multivariable systems is investigated. Linear Time-Invariant Multi-Input Multi- Output (LTI-MIMO) systems represented by a set of complex values in the frequency domain are ...

Elsevier2010

Fixed-Order H-infinity Controller Design via Convex Optimization Using an Alternative to Youla Prameterization

Alireza Karimi, Hamid Khatibi

All H-infinity controllers of a SISO LTI system are parameterized thanks to the relation between Bounded Real Lemma and Positive Real Lemma and a new concept of strict positive realness of two transfer functions with the same Lyapunov matrix in the matrix ...

Institute of Electrical and Electronics Engineers2010

Page 6 sur 9