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X-ORIGINAL-URL:https://alop.uni-trier.de
X-WR-CALDESC:Events for ALOP
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DTSTART:20201025T010000
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DTSTART;TZID=Europe/Berlin:20201109T160000
DTEND;TZID=Europe/Berlin:20201109T180000
DTSTAMP:20201020T170920
CREATED:20201008T063327Z
LAST-MODIFIED:20201008T063928Z
UID:5156-1604937600-1604944800@alop.uni-trier.de
SUMMARY:ALOP-Colloquium with Prof. Dr. Volker Mehrmann\, TU Berlin
DESCRIPTION:On Monday\, November 9. 2020 at 16:00 c.t. Prof. Dr. Volker Mehrmann\, TU Berlin will present his recent work at our colloquium entitled \nHierarchical energy based modeling\, simulation and control of multi-physics systems. \nAbstract: The next level of digitization will create digital twins of every product or process. To do this in a mathematical rigorous and risk and error controlled way\, a new modeling\, simulation and optimization paradigm is needed. While automated modularized modeling is common in some domains like circuit design or multi-body dynamics\, it becomes increasingly challenging when systems or numerical solvers from different physical domains are coupled\, due to largely different scales or modeling accuracy\, and very different software technologies. \nA recent system theoretic approach to address these challenges is the use of network based energy based modeling via constrained port-Hamiltonian (pH) systems\, where the coupling is done in a physically meaningful way via energy variables. Furthermore\, for each subsystem a whole model hierarchy can be employed ranging from very fine grane models to highly reduced surrogate models arising from model reduction or data based modeling. The model hierarchy allows adaptivity not only in the discretization but also in the model selection. \nWe will present an overview over the hierarchical pH modeling approach and illustrate the advantages: \nVery robust models which are close to the real physics\, invariance of the structure under Galerkin projection discretization or model reduction as well as state and time dependent coordinate changes. \nThe results are illustrated with numerical results at the hand of several real world applications. \nThe event is a virtual event via ZOOM. The link will be distributed via email. \n\n \n
URL:https://alop.uni-trier.de/event/alop-colloquium-with-prof-dr-volker-mehrmann-tu-berlin/
CATEGORIES:Colloquium
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BEGIN:VEVENT
DTSTART;TZID=Europe/Berlin:20201123T160000
DTEND;TZID=Europe/Berlin:20201123T180000
DTSTAMP:20201020T170920
CREATED:20201013T082059Z
LAST-MODIFIED:20201013T082134Z
UID:5188-1606147200-1606154400@alop.uni-trier.de
SUMMARY:ALOP-Colloquium with Prof. Dr. Rakesh Vohra\, University of Pennsylvania
DESCRIPTION:On Monday\, November 23\, 2020 at 16:00 Prof. Dr. Rakesh Vohra\, University of Pennsylvania will present his recent work at our colloquium entitled \n \nLinear Programming and Prophet Inequalities \nProphet inequalities bound the expected reward that can be obtained in a class of stopping problems by the optimal reward of the corresponding off-line problem. We use linear programming techniques to obtain prophet inequalities for a class of stopping problems associated with selecting a point in a polyhedron. One application is to `computational sprinting’\, in which a chip temporarily exceeds its sustainable thermal power budget to provide instantaneous throughput\, after which the chip must return to nominal operation to cool down. We also illustrate the usefulness of the approach by giving some new and simple derivations of existing results. \nThis is based on joint work with Markos Epitropu. \nThis presentation will take place via ZOOM. A link will be e-mailed prior to the event.
URL:https://alop.uni-trier.de/event/alop-colloquium-with-prof-dr-rakesh-vohra-university-of-pennsylvania/
CATEGORIES:Colloquium
ORGANIZER;CN="RTG%20ALOP%20at%20Trier%20University":MAILTO:ALOP@uni-trier.de
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=Europe/Berlin:20201214T160000
DTEND;TZID=Europe/Berlin:20201214T180000
DTSTAMP:20201020T170920
CREATED:20201008T115646Z
LAST-MODIFIED:20201008T115829Z
UID:5163-1607961600-1607968800@alop.uni-trier.de
SUMMARY:ALOP-Colloquium with Prof. Dr. Falk Hante\, HU Berlin
DESCRIPTION:On Monday\, December 14\, 2020 at 16:00\, Prof. Dr. Falk Hante\, Humbold Universität zu Berlin will present his recent work at our colloquium. \n \nThis presentation will take place via ZOOM. A link will be e-mailed prior to the event.
URL:https://alop.uni-trier.de/event/alop-colloquium-with-prof-dr-falk-hante-hu-berlin/
CATEGORIES:Colloquium
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=Europe/Berlin:20210125T160000
DTEND;TZID=Europe/Berlin:20210125T180000
DTSTAMP:20201020T170920
CREATED:20201013T042122Z
LAST-MODIFIED:20201013T043841Z
UID:5180-1611590400-1611597600@alop.uni-trier.de
SUMMARY:ALOP-Colloquium with Prof. Dr. Steven Gabriel\, University of Maryland
DESCRIPTION:On Monday\, January 25\, 2021 at 16:00 c.t. Prof. Dr. Steven Gabriel of the University of Maryland \, Baltimore will present his recent work at our colloquium entitled \n \nA parametric programming approach to bilevel optimisation with lower-level variables in the upper level \nThis paper examines linearly constrained bilevel programming problems in which the upper-level\nobjective function depends on both the lower-level primal and dual optimal solutions. We parametrize\nthe lower-level solutions and thereby the upper-level objective function by the upper-level variables\nand argue that it may be non-convex and even discontinuous. However\, when the upper-level\nobjective is affine in the lower-level primal optimal solution\, the parametric function is piece-wise linear.\nWe show how this property facilitates the application of parametric programming and demonstrate how\nthe approach allows for decomposition of a separable lower-level problem. When the upper-level\nobjective is bilinear in the lower-level primal and dual optimal solutions\, we also provide an exact\nlinearisation method that reduces the bilevel problem to a single-level mixed-integer linear programme\n(MILP). We assess the performance of the parametric programming approach on two case studies of\nstrategic investment in electricity markets and benchmark against state-of-the-art MILP and non-linear\nsolution methods for bilevel optimisation problems. Preliminary results indicate substantial\ncomputational advantages over several standard solvers\, especially when the lower-level problem\nseparates into a large number of subproblems. Furthermore\, we show that the parametric\nprogramming approach succeeds in solving problems to global optimality for which standard methods\ncan fail. \nFor further information\, please refer to this article: Henrik C. Bylling\, Steven A. Gabriel & Trine K. Boomsma (2020) A parametric programming approach to bilevel optimisation with lower-level variables in the upper level\, Journal of the Operational Research Society\, 71:5\, 846-865\, DOI: 10.1080/01605682.2019.1590132\nTo link to this article: https://doi.org/10.1080/01605682.2019.1590132 \n \nThis presentation will take place via ZOOM. A link will be e-mailed prior to the event.
URL:https://alop.uni-trier.de/event/alop-colloquium-with-steven-gabriel-university-of-maryland/
CATEGORIES:Colloquium
ORGANIZER;CN="RTG%20ALOP%20at%20Trier%20University":MAILTO:ALOP@uni-trier.de
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