{ "types" : { "Bookmark" : { "pluralLabel" : "Bookmarks" }, "Publication" : { "pluralLabel" : "Publications" }, "GoldStandardPublication" : { "pluralLabel" : "GoldStandardPublications" }, "GoldStandardBookmark" : { "pluralLabel" : "GoldStandardBookmarks" }, "Tag" : { "pluralLabel" : "Tags" }, "User" : { "pluralLabel" : "Users" }, "Group" : { "pluralLabel" : "Groups" }, "Sphere" : { "pluralLabel" : "Spheres" } }, "properties" : { "count" : { "valueType" : "number" }, "date" : { "valueType" : "date" }, "changeDate" : { "valueType" : "date" }, "url" : { "valueType" : "url" }, "id" : { "valueType" : "url" }, "tags" : { "valueType" : "item" }, "user" : { "valueType" : "item" } }, "items" : [ { "type" : "Publication", "id" : "https://puma.ub.uni-stuttgart.de/bibtex/208be7563b587190c24a78304dab29287/mathematik", "tags" : [ "Discrete","Dynamic","Finite","Fracture","Moving-mesh","Two-phase","algorithm","am","aperture","flow","fracture","from:brittalenz","ians","in","matrix","media","methods","models","porous","propagation","volume" ], "intraHash" : "08be7563b587190c24a78304dab29287", "interHash" : "1ef19dc47df248ebcee76f8655d00172", "label" : "A finite-volume moving-mesh method for two-phase flow in\r\nfracturing porous media", "user" : "mathematik", "description" : "", "date" : "2022-02-23 10:11:48", "changeDate" : "2022-04-11 06:45:24", "count" : 4, "pub-type": "article", "journal": "J. Comput. Phys.", "year": "2022", "url": "https://www.sciencedirect.com/science/article/pii/S0021999122000936", "author": [ "Samuel Burbulla","Christian Rohde" ], "authors": [ {"first" : "Samuel", "last" : "Burbulla"}, {"first" : "Christian", "last" : "Rohde"} ], "pages": "111031","abstract": "Multiphase flow in fractured porous media can be described\r\nby discrete fracture matrix models that represent the fractures as\r\ndimensionally reduced manifolds embedded in the bulk porous medium.\r\nGeneralizing earlier work on this approach we focus on immiscible\r\ntwo-phase flow in time-dependent fracture geometries, i.e., the fracture\r\nitself and the aperture of the fractures might evolve in time. For\r\ndynamic fracture geometries of that kind, neglecting capillary forces,\r\nwe deduce by transversal averaging of a full dimensional description a\r\ndimensionally reduced model that governs the geometric evolution and the\r\nflow dynamics. The core computational contribution is a\r\nmixed-dimensional finite-volume discretization based on a conforming\r\nmoving-mesh ansatz. This finite-volume moving-mesh (FVMM) algorithm is\r\ntracking the fractures' motions as a family of unions of facets of the\r\nmesh. Notably, the method permits arbitrary movement of facets of the\r\ntriangulation while keeping the mass conservation constraint. In a\r\nseries of numerical examples we investigate the modeling error of the\r\nreduced model as it compares to the original full dimensional model.\r\nMoreover, we show the performance of the finite-volume moving-mesh\r\nalgorithm for the complex wave pattern that is induced by the\r\ninteraction of saturation fronts and evolving fractures.", "doi" : "https://doi.org/10.1016/j.jcp.2022.111031", "bibtexKey": "burbulla2022finitevolume" } , { "type" : "Publication", "id" : "https://puma.ub.uni-stuttgart.de/bibtex/250eb44f91950357cf988eb9394027e14/mathematik", "tags" : [ "robust","multiobjective","synthesis","control","imng","feasibility","bilinear","h-infinity","inequalities","algorithms","formulas","linear-systems","global","h-2","matrix","uncertainty","output-feedback","from:carsten.scherer","design","optimization","parameter","peerReviewed","lmis","structured","dynamic","order" ], "intraHash" : "50eb44f91950357cf988eb9394027e14", "interHash" : "79b43995f394ecc9dbf6ddc0aa390ca5", "label" : "Robust output-feedback controller design via local BMI optimization", "user" : "mathematik", "description" : "", "date" : "2021-12-01 21:53:35", "changeDate" : "2024-03-12 10:23:32", "count" : 4, "pub-type": "article", "journal": "Automatica", "year": "2004", "url": "https://doi.org/10.1016/j.automatica.2004.01.028", "author": [ "S. Kanev","C. W. Scherer","M. Verhaegen","B. De Schutter" ], "authors": [ {"first" : "S.", "last" : "Kanev"}, {"first" : "C. W.", "last" : "Scherer"}, {"first" : "M.", "last" : "Verhaegen"}, {"first" : "B.", "last" : "De Schutter"} ], "volume": "40","number": "7","pages": "1115-1127","abstract": "The problem of designing a globally optimal full-order output-feedback controller for polytopic uncertain systems is known to be a non-convex NP-hard optimization problem, that can be represented as a bilinear matrix inequality optimization problem for most design objectives. In this paper a new approach is proposed to the design of locally optimal controllers. It is iterative by nature, and starting from any initial feasible controller it performs local optimization over a suitably defined non-convex function at each iteration. The approach features the properties of computational efficiency, guaranteed convergence to a local optimum, and applicability to a very wide range of problems. Furthermore, a fast (but conservative) LMI-based procedure for computing an initially feasible controller is also presented. The complete approach is demonstrated on a model of one joint of a real-life space robotic manipulator. (C) 2004 Elsevier Ltd. All rights reserved.", "shorttitle" : "Robust output-feedback controller design via local BMI optimization", "file" : "://000221904200002", "issn" : "0005-1098", "endnotereftype" : "Journal Article", "bibtexKey": "KanSch04a" } , { "type" : "Publication", "id" : "https://puma.ub.uni-stuttgart.de/bibtex/2b9e0ef26b3072dde1659125d18d60b7c/mathematik", "tags" : [ "approach","lyapunov","functions","relaxations","imng","matrix","inequality","from:carsten.scherer","EXC310","optimization","pn4","peerReviewed","programs","dependent" ], "intraHash" : "b9e0ef26b3072dde1659125d18d60b7c", "interHash" : "65da870d0bca9e82e2d000989caf405c", "label" : "Robust $l_1$ performance analysis for linear systems with parametric uncertainties", "user" : "mathematik", "description" : "", "date" : "2021-12-01 20:49:49", "changeDate" : "2024-03-12 10:23:53", "count" : 4, "pub-type": "article", "journal": "Int. J. Control", "year": "2008", "url": "https://doi.org/10.1080/00207170701730451", "author": [ "J. M. Rieber","C. W. Scherer","F. Allgower" ], "authors": [ {"first" : "J. M.", "last" : "Rieber"}, {"first" : "C. W.", "last" : "Scherer"}, {"first" : "F.", "last" : "Allgower"} ], "volume": "81","number": "5","pages": "851-864","abstract": "In this contribution, a computational approach for analysing the robust e.-gain (or the robust l(1) performance) of uncertain linear systems is developed. In particular, the system's state-space matrices may have a rational dependence on structured parametric time-invariant or time-varying uncertainties. The computation is based on robust semi-definite programming and provides a trade-off between accuracy and computational effort. A novel matrix inequality condition to determine the star-norm of discrete-time systems is derived as an auxiliary result.", "shorttitle" : "Robust l(1) performance analysis for linear systems with parametric uncertainties", "file" : "://000255553000012", "issn" : "0020-7179", "endnotereftype" : "Journal Article", "bibtexKey": "RieSch08a" } , { "type" : "Publication", "id" : "https://puma.ub.uni-stuttgart.de/bibtex/2798e2e62bd35092139fcd4b84f7ec2e5/mathematik", "tags" : [ "linear","robust","quadratic","rates","control","imng","rejection","pn4","parameters","disturbance","inequalities","stabilization","convexity","matrix","constraints","feedback","integral","output","systems","(lmis)","from:tobiasholicki","EXC310","optimization","(iqcs)","peerReviewed" ], "intraHash" : "798e2e62bd35092139fcd4b84f7ec2e5", "interHash" : "935b7ffc617413001028ab65b89dfb4d", "label" : "Robust output feedback control against disturbance filter uncertainty described by dynamic integral quadratic constraints", "user" : "mathematik", "description" : "", "date" : "2021-06-16 14:14:26", "changeDate" : "2024-03-12 10:23:40", "count" : 7, "pub-type": "article", "journal": "Int. J. Robust Nonlin.", "year": "2010", "url": "https://doi.org/10.1002/rnc.1554", "author": [ "S. G. Dietz","C. W. Scherer" ], "authors": [ {"first" : "S. G.", "last" : "Dietz"}, {"first" : "C. W.", "last" : "Scherer"} ], "volume": "20","number": "17","pages": "1903-1919","abstract": "Motivated by a robust disturbance rejection problem, in which disturbances are described by an uncertain filter at the plant input, a convex solution is presented for the robust output feedback controller synthesis problem for a particularly structured plant. The uncertainties are characterized by an integral quadratic constraint (IQC) with general frequency-dependent multipliers. By exploiting the structure of the generalized plant, linear matrix inequality (LMI)-synthesis conditions are derived in order to guarantee a specified L(2)-gain or H(2)-norm performance level, provided that the IQC multipliers are described by LMI constraints. Moreover, it is shown that part of the controller variables can be eliminated. Finally, the rejection of non-stationary sinusoidal disturbance signals is considered. In a numerical example, it is shown that specifying a bound on the rate-of-variation of the time-varying frequency can improve the performance if compared with the static IQC multipliers. Copyright (C) 2009 John Wiley & Sons, Ltd.", "shorttitle" : "Robust output feedback control against disturbance filter uncertainty described by dynamic integral quadratic constraints", "file" : "://000284215900001:Djvu", "issn" : "1049-8923", "endnotereftype" : "Journal Article", "bibtexKey": "DieSch10" } , { "type" : "Publication", "id" : "https://puma.ub.uni-stuttgart.de/bibtex/2b881c5bd45bba967a418431f264925f3/mathematik", "tags" : [ "15A23;","41A05;","42A82;","65Y20","Fast","Interpolation;","Matrix","Positive","computation;","definite","factorization;","from:mhartmann","functions;","ians","vorlaeufig" ], "intraHash" : "b881c5bd45bba967a418431f264925f3", "interHash" : "5fc476059e77e8e9226f6a15761cf6a5", "label" : "Fast computation of orthonormal basis for RBF spaces through Krylov\n\tspace methods", "user" : "mathematik", "description" : "", "date" : "2018-07-20 10:54:28", "changeDate" : "2019-12-18 14:37:55", "count" : 4, "pub-type": "article", "journal": "BIT Numerical Mathematics","publisher":"Springer Netherlands", "year": "2015", "url": "http://dx.doi.org/10.1007/s10543-014-0537-6", "author": [ "Stefano De Marchi","Gabriele Santin" ], "authors": [ {"first" : "Stefano", "last" : "De Marchi"}, {"first" : "Gabriele", "last" : "Santin"} ], "volume": "55","number": "4","pages": "949--966","abstract": "In recent years, in the setting of radial basis function, the study\n\tof approximation algorithms has particularly focused on the construction\n\tof (stable) bases for the associated Hilbert spaces. One of the ways\n\tof describing such spaces and their properties is the study of a\n\tparticular integral operator and its spectrum. We proposed in a recent\n\twork the so-called WSVD basis, which is strictly connected to the\n\teigen-decomposition of this operator and allows to overcome some\n\tproblems related to the stability of the computation of the approximant\n\tfor a wide class of radial kernels. Although effective, this basis\n\tis computationally expensive to compute. In this paper we discuss\n\ta method to improve and compute in a fast way the basis using methods\n\trelated to Krylov subspaces. After reviewing the connections between\n\tthe two bases, we concentrate on the properties of the new one, describing\n\tits behavior by numerical tests.", "issn" : "0006-3835", "file" : ":http\\://www.mathematik.uni-stuttgart.de/fak8/ians/publications/files/DeMSa2015_www_Fast_computation_onb_RBF.pdf:PDF", "owner" : "santinge", "language" : "English", "doi" : "10.1007/s10543-014-0537-6", "bibtexKey": "demarchi2015computation" } ] }