

 

Athanasios C Antoulas  Professor  Professor in Electrical and Computer Engineering   email:aca@rice.edu    Diploma Electrical Engineering (1975) ETH Zurich
 Diploma Mathematics (1975) ETH Zurich
 Doctorate (1980) ETH Zurich
 Habilitation (1983) ETH Zurich
  Primary Department  Department of Electrical and Computer Engineering   

Department Affiliations 
 Dynamical Systems GroupKen Kennedy Institute for Information Technology 

Websites 
 wwwece.rice.edu/~aca


Research Areas 
 Dynamical Systems and Computation 

Projection methods for balanced model
reduction. 
 Source: NSF Grant CCR9988393
Investigators: D.C. Sorensen and A.C. Antoulas 

On the approximation of linear operators with applications 
 Source: NSF Grant DMS 9972591
Investigator: A.C. Antoulas 

test 
 test 

Model Reduction of LargeScale Dynamical Systems 
 Dynamical systems are a principal tool in the modeling and control of physical phenomena as diverse as signal propagation in the neural/nervous system, circuit simulation, weather forecasting, and fluid dynamics. Direct numerical simulation has been one of very few available means for studying the rich complexity of these phenomena, and in many areas of engineering numerical simulation has become essential to the design process. Optimal design of such phenomena is virtually impossible without numerical simulation. However, the ever increasing demand for improved model fidelity leads inevitably to dynamical systems of extremely large scale and complexity. At the same time the systems to be modeled arising mostly from the spatial discretization of the underlying PDEs (partial differential equations), have become more heterogeneous and complex, frequently arising in multiphysics environments. The resulting model manipulations and simulations often impose unmanageable burdens on both human and computational resources, and thus provide the principal motivation for model reduction  creating smaller, cheaper models that closely mimic the original. The use of such complex models for analysis, simulation, optimization, and computeraided system design, can be facilitated (or even made possible) by means of model reduction. Thereby the number of equations involved in the numerical simulation is reduced. The resulting system can then be used in design, optimization, etc., significantly reducing the development time. Thus, model reduction plays an important role in simulations which take place in many application areas. 

Closing the Gap between Descriptive and Predictive Models for Complex Data 

This project considers modeling of complex data which is characterized by source heterogeneity, multiple modalities, high volume, high dimensionality, and multiple scales (temporal, spatial, and functional). Our research is motivated by the gap between descriptive and predictive models to remedy the short comings of each. There is a fundamental difference between the current predictive and descriptive modeling approaches. The descriptive models for capturing a complex system are discrete, data driven and based on feature extraction and mining. One can quantify a functional state with the multiscale features of underlying structural organization, train machine learning algorithms to classify different functional states. However, predicting a functional state and its associated structural organization is not easy since descriptive models lack the laws of physics governing the dynamics of a complex system necessary for prediction. For example we can analyze histopathology tissue samples and decide on the (mal)functional state (e.g., cancerous, diseased or healthy) by using descriptive models in conjunction with classifiers, however, we cannot accurately predict the growth of a tumor during 3 months. In contrast the predictive models are continuous, physicsbased, and based on parametric optimization, however, they are not truly multiscale and cannot capture the structural organization since the parameters have limited relevance to the actual data and to the biology. For example, a predictive model based on physics and solved with finite element method will output a prediction of how the tumor may look like (i.e., shape prediction) in three months but cannot quantify structural organization including cell to cell relationships, cell to ECM interactions, different types of cell etc. 

Model Reduction for Structured Dynamical Systems
R38570776000
NSF CCR0306503
Grant duration: 8/15/20037/31/2006
Ammount: $436,607.00 
 Principal Investigators: D.C. Sorensen (CAAM) and A.C. Antoulas (ECE).
For a summary, see statement following second research project (NSF ITR Grant) below. 

Collaborative Research on Model Reduction of Dynamical Systems for Realtime Control
NSF ITR (Information Technology Research) Grant, collaborative with Purdue and Florida State

 Principal Investigators:
A. Sameh, A. Gramma, C. Hoffmann (Purdue University),
D.C. Sorensen, A.C. Antoulas (Rice University),
K. Gallivan, P.M. van Dooren (Florida State University).
R38670776000
NSF ACI0325081
Grant duration: 9/01/20038/31/2007
Amount: $1,826,959.00
Summary of both Research Projects.
Two main themes can be identified among methodologies for model
reduction. Balanced and Hankel norm approximation methods are built
upon a family of ideas with very close connection to the singular
value decomposition. These methods preserve stability and
allow for global error bounds, but often
do not scale well in terms of computational efficiency and numerical
stability when applied to large scale problems because they rely
upon dense matrix computations.
Moment matching methods are based principally on Padelike
approximations and for largescale problems have lead naturally to the
use of Krylov and rational Krylov subspace projection methods. These methods
generally enjoy greater efficiency and numerical stability though
maintaining stability in the reduced order model cannot be
guaranteed and therefore may be problematic at times. Moreover, no
global error bounds exist.
A strong current trend aims at combining these two approaches by
deriving iterative methods which achieve approximate balanced
reduction. Our projects have been focused on this goal.
This proposal is concerned with the circle of ideas surrounding
model reduction. There are five areas we wish to investigate.
(a) Decay rate of a certain set of singular values
(known as Hankel singular values); (b) Model reduction
preserving stability and passivity by projection; (c) Convergence of
projection algorithms for model reduction;
(d) Periodically timevarying (LPTV) systems,
and (e) Second order dynamical systems.
We have already obtained results
regarding (a). We propose to expand and complete this investigation
which is important because it leads to error bounds for the reduced systems.
(b) The theme of this part is of high relevance to VLSI design.
We have developed a new approach to the problem which is
completely automatic. We intend to continue this investigation
taking into account inaccurate data and numerical issues.
Part (c) is a longstanding open problem. Based on recent developments,
namely a connection between the Lyapunov equation and quadrature rules,
we intend to prove convergence. In part (d) we intend to
extend the decay rate and model reduction results by Krylov methods to
the important class of time varying systems.
Part (e) concerns the numerical construction of reduced order models
for structured second dynamical systems. Again there are numerous
applications.
We intend to develop reduction schemes analogous to balanced truncation
for first order systems. These schemes will preserve the second order
structure in the reduced model, and possess provable bounds on the
approximation error.
Intellectual merit of the proposed activities.
The research proposed here will provide efficient
and robust methods for producing reduced order models of
large state space systems. These activities are
expected to have an impact both in system theory of complex systems
as well as in applied mathematics and in particular numerical methods for
largescale problems. Once the theory and computational
methods are developed, we expect that high quality software will result and
have applications in many areas of engineering.
This will enable at a later stage,
the design of real time controllers for complex systems.
It is also expected that this project will have an impact on the
education of students in engineering and applied mathematics both at
the undergraduate and the graduate levels.
Broader impact resulting from the proposed activities.
In today's technological world, physical processes are
described mainly by mathematical models, which are used to
simulate the behavior of the physical processes in question.
Sometimes, they are also used to modify or control their behavior.
In this framework, there is an ever increasing need for
improved accuracy which leads to models of high complexity.
The basic motivation for system approximation is the need in many
instances for a simplified model of a dynamical system, which
however captures the main features of the original complex model.
This need arises from limited computational, accuracy, and storage
capabilities. The simplified model is then used in place of the
original complex model, either for simulation, or control.
Important areas of application of model reduction are: weather prediction,
air quality management, molecular dynamics simulations, simulation and
control of chemical (e.g. CVD  Chemical Vapor Deposition) reactors,
car windscreen quality management, simulation and control of MEMS (Micro
Electro Mechanical Systems) devices, e.g. micromirrors, to name but a few.
Thus the proposed activities have potential benefits for society at large.


Teaching Areas 
 Dynamical Systems and Computation 

Selected Publications 
 Refereed articles 
 A.C. Antoulas "An overview of model reduction methods for largescale dynamical systems." IFAC Annual Reviews in Control (2004) In Revision 

 A.C. Antoulas, A new result on passivity preserving model reduction, Systems and Control Letters, 54(4): 361374 (2005). 

 S. Gugercin and A.C. Antoulas "A global error expression for the Lanczos procedure." Linear Algebra and Its Applications (2004) In Revision 

 S. Gugercin and A.C. Antoulas "A survey of model reduction by balanced truncation and some new results." Int. J. Control, 77 (2004) : 748766. 

 S. Gugercin and A.C. Antoulas "Model reduction of largescale systems by least squares." Linear Algebra and Its Applications (2004) In Press 

 A. Astolfi, A.C. Antoulas "Hinfinity norm approximation." Electronic Publication (2003) In Press 

 A.C. Antoulas "A new result on positive real interpolation and model reduction." Technical Report, ECE Department (2002) Submitted 

 A.C. Antoulas, D.C. Sorensen, Y. Zhou "On the decay rate of the Hankel singular values and related issues." Systems and Control Letters, 46 (2002) : 323342. 

 A.J. Mayo, A.C. Antoulas "A behavioural approach to positive real interpolation." Journal of Mathematical and Computer Modeling of Dynamical Systems (2003) In Press 

 D.C. Sorensen, A.C. Antoulas "The Sylvester equation and approximate balanced reduction." Linear Algebra and Its Applications, 351352 (2002) : 671700. 

 S. Gugercin, A.C. Antoulas "A survey of model reduction by balanced truncation and some new results." International Journal of Control (2003) Submitted 

 S. Gugercin, A.C. Antoulas, H.P. Zhang "The issue of consistency in identification for robust control." IEEE Transactions on Automatic Control (2003) In Press 

 S. Gugercin, D.C. Sorensen, A.C. Antoulas "A modified lowrank Smith method for largescale
Lyapunov equations." Numerical Algorithms, 32 (2003) : 2755. 

 Articles 
 B. Anic, C.A. Beattie, S. Gugercin and A.C. Antoulas "Interpolatory weighted H2model reduction" to appear, Automatica accepted October 2012. 

 S. Lefteriu, A.C. Antoulas, Connecting vector ﬁtting to barycentric interpolation and the Loewner matrix, submitted, IEEE Trans. Microwave and Wireless Components (2012). 

 S. Lefteriu, A.C. Antoulas, Convergence of the vector ﬁtting iteration, submitted, IEEE Trans. Microwave Theory and Wireless Components (2012) 

 A.C. Antoulas, A.C. Ionita, and S. Lefteriu, On twovariable rational interpolation, Linear Algebra and Its Applications, 436: 28892915 (2012), Available online 14 October 2011. 

 R. Ionutiu, A.C. Antoulas, On the reduction of multiterminal systems and their synthesis, submitted IEEE Trans. CAS, (2012). 

 S. Lefteriu, A.C. Antoulas: A New Approach to Modeling Multiport Systems from FrequencyDomain Data, IEEE Trans. CAD (ComputerAided Design), vol. 29, pages 1427 (2010). 

 Sanda Lefteriu, Athanasios C. Antoulas, Connecting vector fitting to barycentric interpolation and the Loewner matrix, submitted to IEEE Microwave and Wireless Components (2012).


 S. Lefteriu, A.C. Antoulas, Convergence of the vector fitting iteration, Submitted, IEEE Trans. Microwave Theory and Techniques (2012). 

 T. Reis, M. Heinkenschloss, A.C. Antoulas, Balanced Truncation Model Reduction for Systems with Inhomogeneous Initial Conditions, Automatica, 2011, Vol. 47, pp. 559564 

 E. Gildin, A.C. Antoulas, D. Sorensen, and R.H. Bishop, Model and Controller Reduction Applied to Structural Control Using Passivity Theory, Journal on Structural Control and Health Monitoring, 16(3): 319 334 (2009). 

 S. Koshita, M. Abe, M. Kawamata, and A.C. Antoulas, On Hankel singular values and reﬂected zeros of linear continuoustime systems, IEEE Trans. Automatic Control, TAC 54: 641646 (2009). 

 A.C. Antoulas, On the construction of passive models from frequency response data, Automatisierungstechnik, AT56: 447452 (2008). 

 R. Ionutiu, J. Rommes, and A.C. Antoulas, Passivity preserving model reduction using dominant spectral zero interpolation, IEEE Transactions on ComputerAided Design of Integrated Circuits and Systems, CAD27: 22502263 (2008). 

 S. Gugercin, A.C. Antoulas, and C. Beattie, An Iterative Rational Krylov approach to optimal H2 model reduction, (SIAM J. Matrix Analysis and Applications), 30: 609638 (2008). 

 A. J. Mayo and A.C. Antoulas "A Framework for the generalized realization problem, Linear Algebra and Its Applications, Special Issue in honor of P.A. Fuhrmann. Edited by A.C. Antoulas, U. Helmke, J. Rosenthal, V. Vinnikov, and E. Zerz, 425: 634662 (2007).." 

 A.C. Antoulas, On pole placement in model reduction, ATAutomatisierungstechnik, AT 55: 443448 (2007). 

 S. Gugercin and A.C. Antoulas, Model reduction of largescale systems by least squares, Linear Algebra and Applications, Special Issue on Order Reduction of LargeScale Systems, Edited by P. Benner, D.C. Sorensen, R. Freund, and A. Varga, 415(23): 290321 (2006). 

 A.C. Antoulas and A. Astolﬁ, Hinﬁnity norm approximation, in ”Unsolved Problems in Mathematical Systems and Control Theory”, edited by V.D. Blondel and A. Megretski, pages 267270. Electronic Book published by Princeton University Press (2004). 

 A.C. Antoulas, D. Sorensen, K. Gallivan, P. Van Dooren, A. Grama, C. Hoﬀmann, and A. Sameh, Model reduction of largescale dynamical systems, Lecture Notes in Computer Science, Edited by M. Bubak, G.D.v. Albada, P.M.A. Sloot, and J. Dongarra, Vol. 3038, pages 740747 (2004). 

 J. Hu and A.C. Antoulas "Model reduction of linear periodic time varying
systems." (2004) 

 D.C. Sorensen, S. Gugercin, and A.C. Antoulas, A modiﬁed lowrank Smith method for largescale Lyapunov equations, Numerical Algorithms, 32: 2755 (2003). 

 S. Gugercin, A.C. Antoulas, and H.P. Zhang, The issue of consistency in identiﬁcation for robust control, IEEE Transactions on Automatic Control, TAC48: 11091115 (2003). 

 Books 
 C.A. Ionita and A.C. Antoulas, Parametrized model reduction in the Loewner Framework, invited paper, to appear in Reduced Order Methods for modeling and computational reduction, A. Quarteroni and G. Rozza (Editors), book series: Modeling, Simulation and Applications, Springer Verlag (2013). 

 A.C. Ionita and A.C. Antoulas, Matrix pencils in time and frequency domain system identiﬁcation, in Developments in Control Theory towards Glocal Control, Edited by: Qiu, Chen, Iwasaki, Fujioka, The Institution of Science and Technilogy, pages 8088 (2012). 

 S. Lefteriu, A.C. Ionita and A.C. Antoulas, Modeling Systems Based on Noisy Frequency and Time Domain Measurements, in Perspectives in Mathematical System Theory, Control, and Signal Processing, S. Hara, Y. Ohta, and J.C. Willems Editors, Lecture Notes in Control and Information Sciences, Springer, Volume 398, pages 365378 (2010). 

 R. Ionutiu, S. Lefteriu and A.C. Antoulas, Comparison of model reduction methods with applications to circuit simulation, in Scientiﬁc Computing in Electrical Engineering, Book Series: Mathematics in Industry, G. Ciuprina, D. Ioan, Eds., vol. 11, pages 324 (2007). 

 A.C. Antoulas, Approximation of largescale dynamical systems, Book Series: Advances in Design and Control, DC 06, 479 pages, SIAM, Philadelphia (2005); second printing: (2008). 

 A.C. Antoulas, Frequency domain representation and singular value decomposition, in Control Systems, Robotics and Automation, Editor H. Unbehauen, in Encyclopedia of Life Support Systems (EOLSS), Developed under the Auspices of the UNESCO, Eolss Publishers, Oxford, Contribution 6.43.13.4, (2004). 

 A.C. Antoulas "Lectures on the approximation of largescale dynamical systems." 

 Book chapters 
 A.C. Antoulas, C.A. Beattie, and S. Gugercin, Interpolatory model reduction of largescale dynamical systems, in Efficient modeling and control of largescale systems, J. Mohammadpour and K.M. Grigoriadis Editors, 358, Springer Verlag, 2010. 

 R. Ionutiu, J. Rommes, and A.C. Antoulas, A new approach to passivity preserving model reduction: the dominant spectral zero method, in Scientific Computing in Electrical Engineering, J. Roos and L.R.J. Costa (Eds), Mathematics in Industry {\bf 14}, 491498, Springer Verlag, 2010. 

 S. Lefteriu and A. C. Antoulas Topics in model order reduction with applications to circuit simulation, in Model Reduction for Circuit Simulation, M. Hinze, P. Benner, and J.W. ter Maten Editors Lecture Notes in Electrical Engineering (LNEE), Springer, {\bf 74}, 81104 (2011). 

 S. Lefteriu and A.C. Antoulas, A new adaptive approach to multiport scattering parameters, in Scientific Computing in Electrical Engineering, J. Roos and L.R.J. Costa (Eds), Mathematics in Industry {\bf 14}, 2128, Springer Verlag, (2010). 

 A. Antoulas, D. Sorensen, K. Gallivan, P. Van Dooren, A. Grama, C. Hoffmann, A. Sameh "Model reduction of largescale dynamical systems." Lecture Notes in Computer Science, 3038 (2004) : 740747. 

 A. Astolfi and A.C. Antoulas "Hinfinity norm approximation}, in
"Unsolved Problems in Mathematical Systems and Control Theory." Electronic Book (2004) : 267270. 

 A.C. Antoulas "Frequency domain representation and singular
value decomposition." EOLSS (Encyclopedia for the Life Sciences) (2005) In Press 

 D.C. Sorensen and A.C. Antoulas, On model reduction of structured systems, in ”Dimension Reduction of LargeScale Systems”, Edited by P. Benner, V, Mehrmann and D.C. Sorensen, Springer Verlag, pages 125138 (2005). 

 Other 
 A.C. Antoulas "Largescale implementation of minmax model reduction
algorithms." (2004) 

 A.C. Antoulas and D.C. Sorensen "Approximation of largescale dynamical systems: An overview." International J. of Applied Mathematics and Computational Science (accepted for publication) 

 A.C. Antoulas and D.C. Sorensen "Lyapunov, Lanczos, and Inetria." Linear Algebra and Its Applications (LAA), 326 (2001) : 137150. 

 A.C. Antoulas, D.C. Sorensen, and S. Gugercin "A survey of model reduction methods for largescale systems." Contemporary Mathematics, 280 (2001) : 193219. 

 A.C. Antoulas, S. Gugercin, and H.P. Zhang "The issue of consistency in identification for robust control." Automatica 

 D.C. Sorensen, S. Gugercin, and A.C. Antoulas "A modified lowrank Smith method for largescale
Lyapunov equations." Technical Report, submitted 

 A. C. Antoulas and D.C. Sorensen "Lyapunov, Lanczos and Inertia." Linear Algebra and Applications (2000 (Accepted 2001 for publication)) 

 A.C. Antoulas and D.C. Sorensen "Projection methods for balanced model reduction." Revised Technical Report (2000) 

 A.C. Antoulas, D.C. Sorensen, and S.Gugercin "A survey of model reduction methods for largescale systems." In Proceedings of AMS/IMS/SIAM Summer Research Conference on Structured Matrices in Operator Theory, Numerical Analysis, Control, Boulder (2000 (To appear)) 

 P.M van Dooren, A.C. Antoulas "Approximation of largescale dynamical systems." SIAM Annual Meeting, Universite Catholique de Louvain, San Juan, Puerto Rico (July 9, 2000) 

 A.C. Antoulas "Approximation of linear dynamical systems." Wiley Encyclopedia of Electrical and Electronics Engineering, edited by J.G. Webster, 11 (1999) : 403422. 

 A.C. Antoulas "System approximation in the 2norm." Open problems in mathematical systems and control theory, V.D. Blondel, E.D. Sontag, M. Vidyasagar, and J.C. Willems, Eds., 2110, Springer Verlag, Communication and Control Engineering Series, London (1999) 

 A.C. Antoulas and B.D.O. Anderson "On the choice of inputs in identification for robust control." Automatica: 35 (1999) : 10091031. 

 A.C. Antoulas and D.C. Sorensen "On the Lyapunov equation." Technical Report, submitted (1999) 

 A.C. Antoulas, E.D. Sontag and Y. Yamamoto "Controllability and Observability." Wiley Encyclopedia of Electrical and Electronics Engineering, edited by J.G. Webster, 4 (1999) : 264281. 

 A.C. Antoulas, S. Gugercin and H.P. Zhang "On identification for robust control." Technical report, submitted (19) 

 A.C. Antoulas "Approximation of linear operators in the 2norm." Linear Algebra and Applications, 278 (1998) : 309316. 

 A.C. Antoulas and A. Astolfi "Optimizing the EV of the data matrix: a case study in nonsmooth analysis." Proceedings of the 35th IEEE CDC (1998) 

 A.C. Antoulas and B.D.O. Anderson "On the choice of inputs in Identification for robust control." Automatica (to appear (1999)) 

 A.C. Antoulas and H.P. Zhang "On identification for robust control." Automatica (submitted (1998)) 

Presentations 
 Invited Papers 
 "An overview of model reduction methods for largescale systems." 10th IFAC/IFORS/IMACS/IFIP Symposium on Large Scale Systems, Osaka, Japan. (July 2004) With A.C. Antoulas 

 "Gramian based model reduction of largescale systems." BIRS (Banff International Research Station), Banff, Canada. (April 2004) With A.C. Antoulas 

 "Issues in simulation and control of largescale systems." Georgia Institute of Technology, Atlanta. (January 2004) With A.C. Antoulas 

 "Overview of model reduction of largescale systems." International Symposium on Mathematical Theory of Networks and Systems, Leuven, Belgium. (July 2004) With A.C. Antoulas 

 Speaker. "Model reduction with passivity constraints." XV Householder Conference, Peebles, Scottland. (1721 June 2002) 

 "Model reduction with stability and passivity contsraints." IEEE CDC (Conf. on Decision and Control), Las Vegas, NV. (1013 December 2003) With S. Gugercin 

 Invited Talks 
 " Faculty Opponent for the Doctoral Dissertation: "Model Order Reduction Based on Semidefinite Programming". PhD Candidate: Aivar Sootla. LTH (Lund Technical University), Lund, Sweden. ." (1/12/2012) 

 MFO (Mathematical Research Institute): "Control Theory: Mathematical Perspectives on Complex Networked Systems", Invited Talk, Oberwolfach, Germany (2/27/12). 

 An overview of recent results in the reduction of parametrized systems, University of Stuttgart, 4/5/2012. 

 Model reduction of parametrized systems, CECAM (Centre Européen de Calcul Atomique et Moléculaire), EPF (Swiss Federal Institute of Technology) Lausanne, Switzerland, 1416 May 2012. 

 On model reduction for nonlinear systems, Max Planck Intritut Magdeburg, Schloss Ringberg, 69 May 2012. 

 Overview of recent result in parametrized model reduction, LTH (Lund University of Technology), Lund, Sweden. 11 January 2012. 

 Recent result in model reduction of parametrized systems, SIAM Conference on Applied Linear Algebra, Technical University of Valencia, Valencia, Spain, June 1822, 2012. 

 ""Issues in model reduction of largescale systems", University of Liege, Belgium.." (10/1/2010) 

 ""Model reduction from data", Seminar, University of Tokyo.." (9/7/2010) 

 ""Model reduction of parametrized systems", SYRENE Workshop, TU (Thechnical University) Berlin, Germany.." (12/24/2010) 

 ""Overview of model reduction for DAE systems", Workshop on DAE (Differential Algebraic Equation) systems", BIRS (Banff International Research Station), Banff, Canada.." (10/2429/2010) 

 ""The Loewner framework in parametrized model reduction", Workshop on Model Order Reduction in Optimization and Control with PDEs (MOR 2011), WIAS (Weierstrass Institute on Applied Analysis and Stochastics), Berlin, Germany.." (1/2628/2011) 

 ""Tutorial on model reduction in systems and Control", IEEE MCS (MultiConference on Systems), Yokohama, Japan.." (9/810/2010) 

 "An overview of model reduction methods for linear and nonlinear systems, DIMACS Workshop on Perspectives and Future Directions in Systems and Control Theory, Rutgers University.." (5/2326/2011) 

 "Charles Loewner and the Lowener matrix, University of Hamburg, Germany.." (12/8/2011) 

 "Overview of parametrized model reduction, Workshop of the GAMM (Geselschaft fuer Angewandte Mathematik und Mechanik) Activity Group "Applied and Numerical Linear Algeba", special topic: "Model Reduction", University of Bremen, Germany.." (9/2223/2011) 

 "The Loewner matrix and its applications, Householder Symposium 2011, Tahoe City, California.." (6/1217/2011) 

 "Gramians for structured systems." Mathematical Research Institute, Oberwolfach, Germany. (October 2003) With A.C. Antoulas 

 "Model reduction." University of Bremen, Bremen, Germany. (November 2003) With A.C. Antoulas 

 "Overview of model reduction methods." Mathematical Research Institute, Oberwolfach, Germany. (October 2003) With A.C. Antoulas 

 Speaker. "An overview of model reduction methods for largescale dynamical sstems." Brooklyn Poly, Brooklyn, NY. (14 March 2002) 

 Speaker. "An overview of model reduction methods for largescale dynamical systems." UT Austin, Aerospace Engineering Dept., Austin. (4 April 2002) 

 Speaker. "Issues in model reduction." Northern Illinois University, De Kalb, IL. (56 December 2002) 

 Speaker. "Issues in model reduction of largescale systems." Imperial College, London. (28 May 2002) 

 Speaker. "On model reduction of largescale systems." Universitaet Wuerzburg, Wuerzburg, Germany. (15 November 2002) 

 Speaker. "Overview of model reduction." IUB (Int. University Bremen), Bremen. (23 October 2002) 

 Speaker. "Overview of model reduction methods for largescale dynamical systems." MTNS 2002 (Math. Theory of Networks and Systems), Notre Dame. (1216 August 2002) 

 Speaker. "Short course on model reduction of largescale systems." Universitaet Bremen, Bremen. (22 November, 25 November, 26 November 2002) 

 Lectures 
 "On Model Order Reduction of Parametrized Systems, ICIAM (International Congreee on Industrial and Applied Mathematics), Vancouver.." (7/1822/2011) 

 "Parametric model reduction, 17th ILAS (International Linear Algebra Society) Conference "Pure and Applied Linear Algebra: The new Generation", TU (Technical University) Braunschweig, Germany.." (8/2226/2011) 

 "Sparsity Preserving Model Reduction with Applications in Circuit Simulation, ICIAM, Vancouver.." (7/1822/2011) 

 "KrylovBased Controller Reduction for LargeScale Systems." 43rd IEEE CDC (Conference on Decision and Control), Paradise Island, Bahamas. (December 2004) With S. Gugercin, A.C. Antoulas, C.A. Beattie, E. Gildin 

 Other 
 Member PhD Thesis Committee of Bart Besselink; topic: Nonlinear model reduction, Technical University Eindhoven, The Netherlands, 4 June 2012. 

 New results in model reduction of large sclae systems, Mimisymposium Organizer and Chair together with S. Gugercin, SIAM Conference on Applied Linear Algebra, Technical University of Valencia, Valencia, Spain, June 1822, 2012.


 "Faculty Opponent for the Doctoral Dissertation "Model Order Reduction Based on Semidefinite Programming"; PhD Candidate Aivar Soorla.." (1/12/2012) 

 "Application of model reduction methods." University of Illinois at Urbana Champaign, Champaing, IL. (11 September 2001) With A.C. Antoulas 

 "Computational issues in air quality monitoring." National Technical University, Athens. (4 October 2001) With A.C. Antoulas 

 "Hankel singular values and projection methods." University of Groningen, Groningen, The Netherlands. (1 June 2001) With A.C. Antoulas 

 "Issues in model reduction of dynamical systems." Fast Algorithms in Mathematics, Computer Science and Engineering, AMS/IMS/SIAM Summer Research Conference.
, Mt. Holyoke College, South Hadley, MA. (59 August 2001) With A.C. Antoulas 

 "Model reduction and Hankel singular values." Imperial College, London. (16 October 2001) With A.C. Antoulas 

 "Model reduction of the 12A and 1R modules of the Intl. Space Station." IEEE CDC, Orlando. (47 December 2001) With S. Gugercin, N. Bedrossian, and A.C. Antoulas 

 "On Krylov and SVD methods for model reduction." SIAM Conference on Signals Systems and Control, Boston. (1315 August 2001) With A.C. Antoulas 

 "On the decay rate of the Hankel singular values." IEEE CDC (Conference on Decision and Control), Orlando. (47 December) With A.C. Antoulas 

 "On the decay rate of the Hankel singular values." Conference on Approximation and Optimization, Guatemala City. (2630 March 2001) With A.C. Antoulas 

 "Overview of model reduction methods for largescale systems." SIAM Annual Meeting, San Diego. (914 July 2001) With A.C. Antoulas and D.C. Sorensen 

 "Overview of the activities of the Dynamical Systems Group at Rice University
." PearsonFest, A conference in honor of Boyd, Rice University. (March 910, 2001) With A.C. Antoulas 

 "Recent advances in the approximation of dynamical systems." Eindhoven University of Technology, Eindhoven, The Netherlands. (29 May 2001) With A.C. Antoulas 

 "Short Course on Approximation of largescale dynamical systems." Imperial College of Science Technology and Medicine, London. (24 May 2001) With A.C. Antoulas 

 "Approximation of largescale dynamical systems, Kyoto." Kyoto University, Japan. (November 2000) 

 "Approximation of largescale dynamical systems, Osaka." Osaka University, Japan. (November 2000) 

 "Approximation of largescale dynamical systems, San Juan." Siam Annual Meeting, Universite Catholique de Louvain, San Juan, Puerto Rico. (July 9, 2000) With P.M. van Dooren 

 "No Title." IFAC Conference on System Identification (SYSID'00), Santa Barbara, CA. (June 2000) With S. Gugercin 

 "No Title." International Symposium MTNS (Mathematical Theory on Networks and Systems) organized invited session, Perpignan, France. (June 2000) With D.C. Sorensen 

 "No Title." Institute of Automatic Control, Lund Technical University, Sweden. (June 2000) 

 "No Title." IEEE CDC (Conference on Decision and Control), Sydney, Australia. (December 2000) With S. Gugercin 

 "No Title." University of Groningen, The Netherlands. (June 2000) 

 "No Title." Workshop on POD (Proper Orthogonal Decomposition) methods, Graz, Austria. (May 2000) 

 "No Title." DLR (German Aerospace Agency), Munich, Germany. (May 2000) 

 "No Title." SIAM Conference on Applied Linear Algebra, organized minisymposium, Raleigh, North Carolina. (October 2000) With D.C. Sorensen 

 "No Title." IEEE CDC (Conference on Decision and Control), Sydney Australia. (December 2000) With A.C. Antoulas 

 "No Title." Institute for system dynamics, University of Stuttgart, Stuttgart, Gernamy. (May 2000) 

 "Workshop on the occasion of B.D.O. Anderson's 60th birthday." Bondi Junction, Sydney. (December 2000) 

 "A new method for model reduction of largescale systems." Structured Matrices in Operator Theory, Numerical Analysis, Control, AMS/IMS/SIAM Summer Research Conference, Boulder. (June 1999) 

 "A new solution of the Lyapunov equation." IEEE CDC, Phoenix, Arizona. (December 1999) With A.C. Antoulas and D.C. Sorensen 

 "Approximation of largescale dynamical systems." Workshop in Groningen, The Netherlands. (September 1999) With A.C. Antoulas 

 "Control of Uncertain Systems (Invited Presentation)." Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong. (July 1999) With A.C. Antoulas 

 "Identification for robust control." XIV Triennial World Congress, IFAC, Beijing. (July 47, 1999) With A.C. Antoulas and H.P. Zhang 

 "On eigenvalues and singular values of linear dynamical systems." 14th Housholder Symposium on Numerical Linear Algebra, Whistler, BC, Canada. (June 1999) 

 "On identification for control." Workshop in Control of Uncertain Systems, Hong Kong University. (JuneJuly 1999) With A.C. Antoulas 

 "On the assignment of eigenvalues in LTI systems." IEEE CDC, Phoenix, Arizona. (December 1999) With A.C. Antoulas and D.C. Sorensen 

 "Structured Matrices in Operator Theory, Numerical Analysis, Control." AMS/IMS/SIAM Summer Research Conference (Invited Presentation), Boulder. (June 1999) With A.C. Antoulas 

 "The mathematics of systems and control (Invited Presentation)." Workshop on the occasion of the 60th birthday of J.C. Willems, University of Groningen. (September 1999) With A.C. Antoulas 

 "An approach to identification and control." Texas Systems Day, Lubbock, TX. (November 1998) 

 "Identification and Control." IEEE CDC (Conference on Decision and Control), Tampa, Florida. (December 1998) 

 "Issues in identification." Univeristy of Torino, Italy. (July 1998) 

 "Lectures on the approximation of linear systems." Short Course, ETH Zurich. (May 1998) 

 "Model reduction in engineering." Dept. of Civil Engineering, UCLA. (April 1998) 

 "On Hankel singular values of linear systems." Int. Conference on Applied Mathematics (ICAM 98), Leuven, Belgium. (July 1998) 

 "Optimizing the EV of a data matrix." IEEE CDC (Conference on Decision and Control), Tampa, Florida. (December 1998) With A. Astolfi 

 "System identification and control." MTNS (Math. Theory of Networks and Systems), Padova, Italy. (July 1998) With Huipin Zhang 

 "The L2 approximation problem." IEEE CDC (Conference on Decision and Control), Tampa, Florida. (December 1998) 

 Session Chair 
 "MS (Mini Symposium) 148 StructurePreserving Model Reduction, ICIAM, Vancouver, 1822 July, 2011.." (7/1822/2011) 

 Workshops 
 "A survey of balancing methods for model
reduction." European Control Conference, Cambridge, UK. (September 2003) With S. Gugercin and A.C. Antoulas 

 "A timelimited balanced reduction method." 42nd IEEE CDC (Conference on Decision and Control), Maui. (December 2003) With S. Gugercin and A.C. Antoulas 

 "An H2 error expression for the Lanczos
procedure." 42nd IEEE CDC (Conference on Decision and Control), Maui. (December 2003) With S. Gugercin and A.C. Antoulas 

 "Controller Reduction by Krylov Projection Methods." MTNS (Int. Symposium on Mathematical Theory of Networks and Systems), Leuven, Belgium. (July 2004) With S. Gugercin, C.A. Beattie, A.C. Antoulas and E. Gildin 

 "Model reduction of largescale dynamical systems." 4th International Conference on Computational Science  ICCS 2004, Krakow, Poland. (June 2004) With A. Antoulas, D. Sorensen, K. Gallivan, P. Van Dooren, A. Grama, C. Hoffmann, A. Sameh 

Editorial Positions 
 Editor, Advances in Design and Control. SIAM (Society for Industrial and Applied Mathematics). (2003  2003)

 Member of the Editorial Board, SIAM J. Control and Optimization. (1991  1991)

 Member of the Editorial Board, IEEE Transaction on Automatic Control. (1987  1987)

 Member of the Editorial Board, Systems and Control Letters. (1988  1988)

 Other, Linear Algebra and its Applications, Special Issues on Systems and Control. (2006  2006)

 Other, Linear Algebra and its Applications, Special Issues on Systems and Control. (1992  1992)

 Editor in Chief, Systems and Control Letters. Elsevier. (1995  2015)

 Editor in Chief, Systems and Control Letters. Elsevier. (2011  2011)

 Editor in Chief, Systems and Control Letters. Elsevier. (2004  2004)

Supervised Theses & Dissertations 
 Serkan Gugercin, PhD Projection methods for model reduction of largescale systems. (2003) (Thesis Director)

Awards, Prizes, & Fellowships 
 Fellowship to attend workshop in Banff, BIRS (Banff International Research Station) (4/2004)

 Fellowship to attend a workshop in Oberwolfach, Mathematical Research Institute, Oberwolfach, Germany (10/2003)

 Member, IFAC Technical Committe on Linear Systems (Intl. Federation of Automatic Control)

 Foreign Member, SMG (Swiss Mathematical Society)

 Member, ILAS (Intl. Linear Algebra Society)

 NSF Panel, NSF (2425 April 2001)

 Fellow, IEEE (Institute of Electrical and Electronic Engineers)

 Member, AMS (American Mathematical Society)

 Organizer of MiniSymposium at the SIAM Annual Meeting and the SIAM Control Meeting,
San Diego, SIAM (914 July 2001)

 Member, SIAM (Society for Industrial and Applied Mathematics)

 Fellow, JSPS (Japan Society for the Promotion of Science)

 Fellow, IEEE (Institute of Electrical and Electronic Engineers)

Positions Held 
 EditorinChief, Systems and Control Letters. (2002  2002)
