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564
Walking the tightrope: Responsive yet stable traffic engineering
 In Proc. ACM SIGCOMM
, 2005
"... Current intradomain Traffic Engineering (TE) relies on offline methods, which use long term average traffic demands. It cannot react to realtime traffic changes caused by BGP reroutes, diurnal traffic variations, attacks, or flash crowds. Further, current TE deals with network failures by precompu ..."
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Cited by 158 (3 self)
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Current intradomain Traffic Engineering (TE) relies on offline methods, which use long term average traffic demands. It cannot react to realtime traffic changes caused by BGP reroutes, diurnal traffic variations, attacks, or flash crowds. Further, current TE deals with network failures by precomputing alternative routings for a limited set of failures. It may fail to prevent congestion when unanticipated or combination failures occur, even though the network has enough capacity to handle the failure. This paper presents TeXCP, an online distributed TE protocol that balances load in realtime, responding to actual traffic demands and failures. TeXCP uses multiple paths to deliver demands from an ingress to an egress router, adaptively moving traffic from overutilized to underutilized paths. These adaptations are carefully designed such that, though done independently by each edge router based on local information, they balance load in the whole network without oscillations. We model TeXCP, prove the stability of the model, and show that it is easy to implement. Our extensive simulations show that, for the same traffic demands, a network using TeXCP supports the same utilization and failure resilience as a network that uses traditional offline TE, but with half or third the capacity.
Spaceex: Scalable verification of hybrid systems
 In Proceedings of the International Conference on Computer Aided Verification
, 2011
"... Abstract. We present a scalable reachability algorithm for hybrid systems with piecewise affine, nondeterministic dynamics. It combines polyhedra and support function representations of continuous sets to compute an overapproximation of the reachable states. The algorithm improves over previous wo ..."
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Cited by 88 (5 self)
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Abstract. We present a scalable reachability algorithm for hybrid systems with piecewise affine, nondeterministic dynamics. It combines polyhedra and support function representations of continuous sets to compute an overapproximation of the reachable states. The algorithm improves over previous work by using variable time steps to guarantee a given local error bound. In addition, we propose an improved approximation model, which drastically improves the accuracy of the algorithm. The algorithm is implemented as part of SpaceEx, a new verification platform for hybrid systems, available at spaceex.imag.fr. Experimental results of full fixedpoint computations with hybrid systems with more than 100 variables illustrate the scalability of the approach. 1
The quadrupletank process: A multivariable laboratory process with an adjustable zero
 IEEE Trans. on Control Systems Technology
"... Abstract—A novel multivariable laboratory process that consists of four interconnected water tanks is presented. The linearized dynamics of the system have a multivariable zero that is possible to move along the real axis by changing a valve. The zero can be placed in both the left and the right hal ..."
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Cited by 53 (0 self)
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Abstract—A novel multivariable laboratory process that consists of four interconnected water tanks is presented. The linearized dynamics of the system have a multivariable zero that is possible to move along the real axis by changing a valve. The zero can be placed in both the left and the right halfplane. In this way the quadrupletank process is ideal for illustrating many concepts in multivariable control, particularly performance limitations due to multivariable right halfplane zeros. The location and the direction of the zero have an appealing physical interpretation. Accurate models are derived from both physical and experimental data and decentralized control is demonstrated on the process. Index Terms—Education, laboratory process, multivariable control, multivariable zeros. I.
A Method for Handling Uncertainty in Evolutionary Optimization with an Application to Feedback Control of Combustion
"... Abstract — We present a novel method for handling uncertainty in evolutionary optimization. The method entails quantification and treatment of uncertainty and relies on the rank based selection operator of evolutionary algorithms. The proposed uncertainty handling is implemented in the context of th ..."
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Cited by 50 (14 self)
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Abstract — We present a novel method for handling uncertainty in evolutionary optimization. The method entails quantification and treatment of uncertainty and relies on the rank based selection operator of evolutionary algorithms. The proposed uncertainty handling is implemented in the context of the Covariance Matrix Adaptation Evolution Strategy (CMAES) and verified on test functions. The present method is independent of the uncertainty distribution, prevents premature convergence of the evolution strategy and is well suited for online optimization as it requires only a small number of additional function evaluations. The algorithm is applied in an experimental setup to the online optimization of feedback controllers of thermoacoustic instabilities of gas turbine combustors. In order to mitigate these instabilities, gaindelay or modelbased H ∞ controllers sense the pressure and command secondary fuel injectors. The parameters of these controllers are usually specified via a trial and error procedure. We demonstrate that their online optimization with the proposed methodology enhances, in an automated fashion, the online performance of the controllers, even under highly unsteady operating conditions, and it also compensates for uncertainties in the modelbuilding and design process. I.
From experiment design to closedloop control
, 2005
"... The links between identification and control are examined. The main trends in this research area are summarized, with particular focus on the design of low complexity controllers from a statistical perspective. It is argued that a guiding principle should be to model as well as possible before any m ..."
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Cited by 45 (1 self)
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The links between identification and control are examined. The main trends in this research area are summarized, with particular focus on the design of low complexity controllers from a statistical perspective. It is argued that a guiding principle should be to model as well as possible before any model or controller simplifications are made as this ensures the best statistical accuracy. This does not necessarily mean that a fullorder model always is necessary as well designed experiments allow for restricted complexity models to be nearoptimal. Experiment design can therefore be seen as the key to successful applications. For this reason, particular attention is given to the interaction between experimental constraints and performance specifications.
A tutorial on linear and bilinear matrix inequalities
, 2000
"... This is a tutorial on the mathematical theory and process control applications of linear matrix inequalities (LMIs) and bilinear matrix inequalities (BMIs). Many convex inequalities common in process control applications are shown to be LMIs. Proofs are included to familiarize the reader with the ma ..."
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Cited by 44 (0 self)
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This is a tutorial on the mathematical theory and process control applications of linear matrix inequalities (LMIs) and bilinear matrix inequalities (BMIs). Many convex inequalities common in process control applications are shown to be LMIs. Proofs are included to familiarize the reader with the mathematics of LMIs and BMIs. LMIs and BMIs are applied to several important process control applications including control structure selection, robust controller analysis and design, and optimal design of experiments.
Attack detection and identification in cyberphysical systems
 IEEE Trans. Automat. Contr
"... Cyberphysical systems are ubiquitous in power systems, transportation networks, industrial process control and critical infrastructures. These systems need to operate reliably in the face of unforeseen failures and external malicious attacks. In this paper (i) we propose a mathematical framework fo ..."
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Cited by 30 (4 self)
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Cyberphysical systems are ubiquitous in power systems, transportation networks, industrial process control and critical infrastructures. These systems need to operate reliably in the face of unforeseen failures and external malicious attacks. In this paper (i) we propose a mathematical framework for cyberphysical systems, attacks, and monitors; (ii) we characterize fundamental monitoring limitations from systemtheoretic and graphtheoretic perspectives; and (iii) we design centralized and distributed attack detection and identification monitors. Finally, we validate our findings through compelling examples. I.
Bandit problems
 Proceedings of the Seventh International Berry
, 1985
"... the formulation and solution of robust performance ..."
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Cited by 23 (1 self)
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the formulation and solution of robust performance
Issues, progress and new results in robust adaptive control
 ADAPTIVE CONTROL AND SIGNAL PROCESSING
, 2006
"... We overview recent progress in the field of robust adaptive control with special emphasis on methodologies that use multiplemodel architectures. We argue that the selection of the number of models, estimators and compensators in such architectures must be based on a precise definition of the robust ..."
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Cited by 22 (6 self)
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We overview recent progress in the field of robust adaptive control with special emphasis on methodologies that use multiplemodel architectures. We argue that the selection of the number of models, estimators and compensators in such architectures must be based on a precise definition of the robust performance requirements. We illustrate some of the concepts and outstanding issues by presenting a new methodology that blends robust nonadaptive mixed µsynthesis designs and stochastic hypothesistesting concepts leading to the socalled Robust Multiple Model Adaptive Control (RMMAC) architecture. A numerical example is used to illustrate the RMMAC design methodology, as well as its strengths and potential shortcomings. The later motivated us to develop a variant architecture, denoted as RMMAC/XI, that can be effectively used in highly uncertain exogenous plant disturbance environments.