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Ett informationsblad från matematiska institutionen vid Linköpings universitet. Material till Lite Mat lämnas till Maud Lindström litemat@mai.liu.se senast torsdagar kl 12.00.
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Ett informationsblad från matematiska institutionen vid Linköpings universitet
v39 2002
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Onsdagen den 25 september, kl. 13.00-14.00 talar Professor Nikolay Kuznetsov, St. Petersburg,
On sloshing frequencies in the ice-fishing problem
Sammanfattning:
The ice-fishing problem is a boundary value problem for the Laplace equation with a spectral parameter in a boundary condition on a part of the boundary. This problem describes free oscillations of water in a half-space covered by a rigid dock with apertures, where the above mentioned condition is imposed. The aim of talk is twofold:
(1) Assuming that the problem is two-dimensional and that there are two equal gaps in the dock, it will be demonstrated by differentiating the Rayleigh quotient that all eigenvalues are monotonic functions of the spacing between gaps. For the fundamental eigenvalue and the corresponding eigenfunction the asymptotic formulae for large values of spacing will be discussed.
(2) For the three-dimensional problem, it occurs that the fundamental eigenvalue depends in a complicated way on the geometry of apertures. Some examples illustrating this dependence will be given.
Onsdagen den 2 oktober, kl. 13.00-14.00 talar Professor Adrian Constantin, Lund,
The Camassa-Holm model for shallow water waves
Sammanfattning:
A recently derived nonlinear partial differential equation models the unidirectional propagation of waves on shallow water. The rich structure of the equation is the object of our presentation: the equation is an integrable infinite-dimensional Hamiltonian system and a re-expression of geodesic flow on the diffeomorphism group of the circle. Moreover, it models waves of permanent form as well as wave breaking and its solitary waves interact like solitons.
Onsdagen den 9 oktober, kl. 13.00-14.00 talar Professor Kurt Johansson, KTH
Lokal: ISY/MAI:s seminarierum Glashuset, ingång 25.
Välkomna!
Anders Björn,
Vladimir Kozlov och
Stefan Rauch-Wojciechowski
Onsdagen den 25 september kl. 14.10 talar Anders Hansson, ISY
A Primal-Dual Interior-Point Method for Robust Optimal Control of Linear Discrete-Time Systems
Abstract: In this talk is described how to efficiently solve a robust optimal control problem using recently developed primal-dual interior-point methods. Among potential applications are model predictive control. The optimization problem considered consists of a worst case quadratic performance criterion over a finite set of linear discrete-time models subject to inequality constraints on the states and control signals. The scheme has been prototyped in Matlab. To give a rough idea of the efficiencies obtained, it is possible to solve problems with more than 10000 primal variables and 40000 constraints on a workstation. The key to the efficient implementation is an iterative solver in conjunction with a Riccati-recursion invertible pre-conditioner for computing the search directions.
Lokal: ISY/MAI:s seminarierum Glashuset, ingång 25.
Onsdagen den 25 september kl. 15.30 talar Bjarni Kristjaanson, Maximal Software Ltd
Using the MPL Modeling System and the OptiMax 2000 Component Library to create Embedded Optimization Applications
MPL (Mathematical Programming Language) is an advanced modeling system that allows the model developer to formulate complicated optimization models in a clear, concise and efficient way
There will be demonstrations on how MPL can now directly import data from relational databases such as Paradox, Access . Special emphasis will be given to what effects this can have on formulating large industrial models.
The Optimax 2000 is a new object-oriented Component Library that allows the model developer to easily create customized end-user applications to solve real-world optimization problems.
We will demonstrate how this allows seamless integration of optimization models into easily maintainable applications, by connecting the MPL modeling language with any object-oriented programming language, such as VBA for Excel/Access, Visual Basic, Visual C++, Java, Delphi, and web scripting languages.
A number of demonstrations will be shown of how MPL and OptiMax models, can make good use of EXCEL's extensive graphical and reporting capabilities, to show the solution results to the end-user of the model.
We will demonstrate how optimization and modeling services can be packaged into component libraries based on industry standards such as ActiveX/Com and JavaBeans. This allows seamless integration of optimization into easily maintainable applications.
Lokal: Kompakta rummet
Onsdagen den 25 september, kl. 10.15 talar professor Yair censor Department of Mathematics University of Haifa, Israel
Finding the Projection of a Point onto the Intersection of Convex Sets Via Projections onto Halfspaces
Abstract: We present a modification of Dykstra's algorithm for the best approximation problem which allows us to avoid projections onto general convex sets. Instead, we calculate projections onto either a halfspace or onto the intersection of two halfspaces. Convergence of the algorithm is established and special choices of the halfspaces are proposed. The option to project onto halfspaces instead of general convex sets makes the algorithm more practical. The fact that the halfspaces are quite general enables us to apply the algorithm in a variety of cases and to generalize a number of known projection algorithms.
Lokal: ISY/MAI:s seminarierum Glashuset, ingång B25.
Välkomna!
Lars Eldén och Tommy Elfving
Fredagen den 27 september, kl. 13.15 talar Professor Nikolay Kuznetsov, St Petersburg
Variations on a theme by Fritz John
In 1950, F. John published the second of his papers on the water-wave problem. In this paper he developed a method that proved itself to be extremely successful in studying the question of uniqueness for this problem (this question is a nontrivial one because point eigenvalues embedded in the continuous spectrum might exist).
The talk is concerned with various aspects of John's approach. Examples in which it works and fails to work will be discussed.
Lokal: Seminarierum Beurling
Välkomna!
Vladimir Kozlov
Fredagen den 27 september kl 13.15-15 presenterar Jennifer Nijm, Grundskollärarprogrammet, sitt examensarbete med titeln Vad vet lärare om sina elevers uppfattningar om matematik? Opponent är Christina Andersson. Intresserade kan kontakta undertecknad för en kopia av uppsatsen.
Lokal: Determinanten, ingång B23, 1 tr.
Välkomna!
Christer Bergsten
Torsdagen den 3 oktober kl 13.15-15 leder undertecknad ett diskussionsseminarium med temat Att förstå och diskutera matematiska texter. Vi utgår från två artiklar, som bör läsas före seminariet:
- Sierpinska, A. (1997). Formats of interaction and model readers. For the Learning of Mathematics 17(2), 3-12.
- Borasi, R. et al (1998). Using transactional reading strategies to support sense-making and discussion in mathematics classrooms: An exploratory study. Journal for Research in Mathematics Education 29(3), 275-305.
Intresserade kan kontakta undertecknad för kopior av artiklarna.
Lokal: Determinanten, ingång B23, 1 tr.
Välkomna!
Christer Bergsten
Samtliga administratörer kommer delta i utvecklingsdagar i Söderköping tisdagen 24 - onsdag 25/9 (lunch-lunch).
Mer information om MAI finns på under MAIs hemsida
Material till Lite Mat lämnas till Maud Lindström senast
torsdagar kl 12.00.
Tel 013-281405, Fax 013-100746, Email: litemat@mai.liu.se
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Senast ändrad: Thu 2010-03-18; 18:16 MET