Szemináriumok

Dynamics of hardware-in-the-loop experiments

Időpont: 
2018. 11. 29. 10:15
Hely: 
H607 (A megszokottól eltérő hely !)
Előadó: 
Stépán Gábor
A szeminárium részletei: 
Miklós Farkas Seminar on Applied Analysis

A widely used tool of engineering R&D is the hardware-in-the-loop (HIL) experiment. Instead of building the full prototype of a developed machine, only its most critical parts are constructed physically, while the rest of the machine is emulated by means of actuators, sensors, and digital control in between. If the mathematical model of the rest of the machine is available, the control unit can provide a realistic environment for the physically constructed test part. The control, however, introduces digital effects into this system which is originally continuous. From dynamical view-point, the most relevant digital effects are the appearances of delay and zero-order-hold (ZOH). The nonlinear dynamics of the real system and the one emulated by means of the HIL experiment are compared from stability and nonlinear vibrations view-point in case of a brake system where stick-slip phenomenon occurs. The limitations of HIL experiments are identified by means of Hopf bifurcation calculations, numerical simulations and dynamic measurements carried out on the corresponding experimental test rig. 

The introductory part of the lecture will present the concept of the ERC advanced grant project and the role of HIL in the development of new milling tools for metal cutting, and the concluding part of the lecture will present the application of the results for the development of HIL experiments in case of high-speed-milling (HSM).

Extended finite element methods: a brief introduction

Időpont: 
2018. 11. 22. 10:15
Hely: 
H306
Előadó: 
Karátson János
A szeminárium részletei: 
Miklós Farkas Seminar on Applied Analysis

The finite element method (FEM) is a fundamental tool of the numerical solution of real-life problems based on partial differential equations. In the recent decades, various generalizations of the standard FEM have been developed. A lot of such extensions have been motivated by difficulties, arising in physical or engineering problems, that may be cumbersome to overcome with standard FEM techniques. Such situations are the presence of boundary layers, singularities or discontinuities in the solution, complex and/or evolving geometry of the physical domains etc. The tools of extension of the FEM may be enriching the polynomial approximation space with non-polynomial shape functions, allowing general polygonal/polyhedral cells, or use a boundary-unfitted mesh and restricted shape functions (either to a bulk domain or to a surface). This survey type talk gives a brief introduction to the main ideas of some generalized FEMs that use the above ideas: XFEM, VEM, CutFEM and TraceFEM. 

Kari Nyílt Nap

Időpont: 
2018. 11. 16.
09:00 to 16:00
Hely: 
BME K épület

Sok szeretettel várunk minden kedves érdeklődőt a Budapesti Műszaki és Gazdaságtudományi Egyetem Természettudományi Karának Nyílt Napjára 2018. november 16-án (pénteken) a BME dísztermében.

Részletes információk: http://felvi.physics.bme.hu/nyiltnap

Operator semigroups, innovative integrators, and flood prevention

Időpont: 
2018. 11. 15. 10:15
Hely: 
H306
Előadó: 
Csomós Petra
A szeminárium részletei: 
Miklós Farkas Seminar on Applied Analysis

The talk summarizes our results obtained when studying the possible application of innovative integrators (operator splitting  procedures and exponential integrators) to optimal control problems. We introduce the innovative integrators considered, and present the advantages and drawbacks of their use. After introducing the abstract optimal control problem having a linear quadratic cost function, we prove the convergence of innovative integrators applied to it. To do so, we briefly summarize the main results in operator semigroup theory, used in the proof. As an example, we treat the linear quadratic regulator problem of the one-dimensional and two-dimensional shallow water equations, and illustrate our results by numerical experiments.

The results are based on the joint works with Johannes Winckler (Tübingen) and Hermann Mena (Innsbruck).

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