Journal: Technical report

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ETH Zürich, Institut für Automatik

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2009 - 200912010 - 20146
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Publications 1 - 7 of 7
  • On the evaluation of mp-MIQP solutions
    Item type: Report
    Fuchs, A.; Axehill, D.; Morari, M. (2013)
    Technical report
    This paper presents an efficient approach for the evaluation of multi-parametric mixed integer quadratic program (mp-MIQP) solutions, occurring for instance in control problems involving discrete time hybrid systems with quadratic cost. Traditionally, the online evaluation requires a sequential comparison of piecewise quadratic value functions. As the main contribution, we introduce a lifted parameter space in which the piecewise quadratic value functions become piecewise affine and can be merged to a single value function defined over a single polyhedral partition without any overlaps. This enables efficient point location approaches using a single binary search tree. Numerical experiments include a power electronics application and demonstrate an online speedup up to an order of magnitude. We also show how the achievable online evaluation time can be traded off against the offline computational time.
  • Energy efficient ventilation
    Item type: Report
    Morari, Manfred; Rostalski, Ph.; Woods, Andy (2009)
    Technical report
    Upflow displacement ventilation is designed to provide fresh, pre-conditioned air throughout a space, while maintaining the natural tendency of hot air to rise to the top of the space. In principle this can reduce the cooling load in comparison with systems which use a high level source of pre-conditioned air combined with mixing ventilation. One of the questions concerning upflow displacement ventilation is the distribution and concentration of contaminants which may accumulate within the space through the interaction of the ventilation flow and the occupants/activity in the building. We develop a simplified fluid model to explore this feature of displacement ventilation in more detail, and test the model with some new laboratory experiments.
  • Stopping Criteria for First-Order Methods
    Item type: Report
    Richter, S.; Morari, M. (2012)
    Technical report
    This technical note introduces and evaluates stopping criteria for convex optimization. The emphasis is put on criteria that are `cheap' to evaluate if first-order methods, such as gradient projection or the fast gradient method, are applied. We investigate three different criteria which are based either on the complexity results of first-order methods, a property of the gradient mapping or on conjugacy, which to the best of the authors' knowledge results in a novel stopping criterion.
  • Bilinear Modeling for Model Predictive Control of an Air Handling Unit
    Item type: Report
    Sturzenegger, David (2012)
    Technical report
  • A Complexity-Based Review on Proximal Gradient Methods for Convex Composite Optimization
    Item type: Report
    Richter, S.; Morari, M.; Jones, C. (2012)
    Technical report
  • A Tractable Nonlinear Fault Detection and Isolation Technique with Application to the Cyber-Physical Security of Power Systems
    Item type: Report
    Mohajerin Esfahani, Peyman; Vrakopoulou, M.; Andersson, G.; et al. (2012)
    Technical report
    This article consists of two parts: a theoretical part concerned with fault detection schemes, and an application part dealing with cyber security of power systems. In the first part, we develop a tractable approach to design a robust residual generator to detect and isolate faults in high dimensional nonlinear systems. Previous approaches on fault detection and isolation problems are either confined to linear systems or they are only applicable to low dimensional dynamics with more specific structures. In contrast, we propose a novel methodology to robustify a linear residual generator for a nonlinear system in the presence of certain disturbance signatures. To this end, we formulate the problem into the framework of quadratic programming which enables us to solve relatively high dimensional systems. In the second part, the application is motivated by the emerging problem of cyber security in power networks. We provide description of a multi-machine power system that represents a two-area power system, and we model a cyber-physical attack emanating from the vulnerabilities introduced by the interaction between IT infrastructure and power system. The algorithm developed in the first part is finally used to diagnose such an intrusion before the functionality of the power system is disrupted.
  • Inverse Parametric Optimization with an Application to Hybrid System Control
    Item type: Report
    Hempel, Andreas B.; Goulart, Paul J.; Lygeros, John (2014)
    Technical report
    We present a number of results on inverse parametric optimization and its application to hybrid system control. We show that any function that can be written as the difference of two convex functions can also be written as a linear mapping of the solution to a convex parametric optimization problem. We exploit these results in application to the control of systems with piecewise affine dynamics, and show that it is possible to model such systems as optimizing processes. Optimal control problems for such systems can be remodeled as bilevel optimization problems and solved with existing techniques.
Publications 1 - 7 of 7