Die Dozenten der Informatik-Institute der Technischen Universität
Braunschweig laden im Rahmen des Informatik-Kolloquiums zu folgendem
Vortrag ein.
Dimitris G. Giovanis, Institute of Structural Analysis and Antiseismic
Research, National Technical University of Athens, Greece:
A variability response function (VRF)-based adaptive spectral Galerkin
stochastic finite element method
Beginn: 19.11.2015, 10:00 Uhr
Ort: TU Braunschweig, Informatikzentrum, Mühlenpfordtstraße 23,
8. OG, Raum 826
Webseite: http://www.ibr.cs.tu-bs.de/cal/kolloq/2015-11-19-giovanis.html
Kontakt: Prof. Hermann G. Matthies, PhD
In this work the concept of variability response function (VRF)
is utilized in the framework of Galerkin, spectral stochastic finite
element method (SSFEM) in order to achieve an a priori low-cost estimate
of the spatial distribution of the statistical second-order error of the
response, as a function of the truncation order of the Karhunen-Loève
(KL) decomposition. This way the optimal encapsulation of the information
contained in the correlation structure of the random input is achieved
through a spatial variation of the truncated KL terms. The criterion for
selecting the number of KL terms at different parts of the structure is
the uniformity of the spatial distribution of the second-order error. As
a consequence, an increase of sparsity of the coefficient matrix of
the corresponding linear system of equations is achieved, leading to a
reduction of the computational cost of the method.
This work has been supported by the European Research Council
Advanced Grant MASTER - Mastering the computational challenges in
numerical modeling and optimum design of CNT reinforced composites
(ERC-2011-ADG-20110209).
Die Dozenten der Informatik-Institute der Technischen Universität
Braunschweig laden im Rahmen des Informatik-Kolloquiums zu folgendem
Vortrag ein.
George Stefanou, Institute of Structural Analysis & Dynamics of
Structures, Department of Civil Engineering, Aristotle University of
Thessaloniki, Greece:
Linking micromechanics-based properties with the stochastic finite
element method
Beginn: 17.11.2015, 14:00 Uhr
Ort: TU Braunschweig, Informatikzentrum, Mühlenpfordtstraße 23,
8. OG, Raum 826
Webseite: http://www.ibr.cs.tu-bs.de/cal/kolloq/2015-11-17-stefanou.html
Kontakt: Prof. Hermann G. Matthies, PhD
The linking of microstructure uncertainty with the random variation
of material properties at the macroscale is particularly needed in the
framework of the stochastic finite element method (SFEM) where arbitrary
assumptions are usually made regarding the probability distribution
and correlation structure of the macroscopic (effective) mechanical
properties. In this work, the linking is efficiently accomplished by
exploiting the excellent synergy of the extended finite element method
(XFEM) and Monte Carlo simulation for the computation of the effective
properties of random two-phase composites. The homogenization is based
on Hill's energy condition and involves the generation of a large number
of realizations of the microstructure with uncertainty in the geometry
(shape, number, spatial distribution and orientation of inclusions) or
in the constituent material properties. The mean value, coefficient of
variation and probability distribution of the effective elastic modulus
and Poisson ratio of the random composite are computed. A comparison of
the relative influence of the above two kinds of uncertainty is made. The
effective properties are finally used in the framework of SFEM to obtain
the response of a composite structure and useful conclusions are derived
regarding the effect of random microstructure on the probabilistic
characteristics of the response.
This work is supported by the European Research Council Advanced Grant
''MASTER-Mastering the computational challenges in numerical modeling
and optimum design of CNT reinforced composites'' (ERC-2011-ADG 20110209).
Die Dozenten der Informatik-Institute der Technischen Universität
Braunschweig laden im Rahmen des Informatik-Kolloquiums zu folgendem
Vortrag ein.
Dimitris G. Giovanis, Institute of Structural Analysis and Antiseismic
Research, National Technical University of Athens, Greece:
A variability response function (VRF)-based adaptive spectral Galerkin
stochastic finite element method
Beginn: 19.11.2015, 10:00 Uhr
Ort: TU Braunschweig, Informatikzentrum, Mühlenpfordtstraße 23,
8. OG, Raum 826
Webseite: http://www.ibr.cs.tu-bs.de/cal/kolloq/2015-11-19-giovanis.html
Kontakt: Prof. Hermann G. Matthies, PhD
In this work the concept of variability response function (VRF)
is utilized in the framework of Galerkin, spectral stochastic finite
element method (SSFEM) in order to achieve an a priori low-cost estimate
of the spatial distribution of the statistical second-order error of the
response, as a function of the truncation order of the Karhunen-Loève
(KL) decomposition. This way the optimal encapsulation of the information
contained in the correlation structure of the random input is achieved
through a spatial variation of the truncated KL terms. The criterion for
selecting the number of KL terms at different parts of the structure is
the uniformity of the spatial distribution of the second-order error. As
a consequence, an increase of sparsity of the coefficient matrix of
the corresponding linear system of equations is achieved, leading to a
reduction of the computational cost of the method.
This work has been supported by the European Research Council
Advanced Grant MASTER - Mastering the computational challenges in
numerical modeling and optimum design of CNT reinforced composites
(ERC-2011-ADG-20110209).
Die Dozenten der Informatik-Institute der Technischen Universität
Braunschweig laden im Rahmen des Informatik-Kolloquiums zu folgendem
Vortrag ein.
George Stefanou, Institute of Structural Analysis & Dynamics of
Structures, Department of Civil Engineering, Aristotle University of
Thessaloniki, Greece:
Linking micromechanics-based properties with the stochastic finite
element method
Beginn: 17.11.2015, 14:00 Uhr
Ort: TU Braunschweig, Informatikzentrum, Mühlenpfordtstraße 23,
8. OG, Raum 826
Webseite: http://www.ibr.cs.tu-bs.de/cal/kolloq/2015-11-17-stefanou.html
Kontakt: Prof. Hermann G. Matthies, PhD
The linking of microstructure uncertainty with the random variation
of material properties at the macroscale is particularly needed in the
framework of the stochastic finite element method (SFEM) where arbitrary
assumptions are usually made regarding the probability distribution
and correlation structure of the macroscopic (effective) mechanical
properties. In this work, the linking is efficiently accomplished by
exploiting the excellent synergy of the extended finite element method
(XFEM) and Monte Carlo simulation for the computation of the effective
properties of random two-phase composites. The homogenization is based
on Hill's energy condition and involves the generation of a large number
of realizations of the microstructure with uncertainty in the geometry
(shape, number, spatial distribution and orientation of inclusions) or
in the constituent material properties. The mean value, coefficient of
variation and probability distribution of the effective elastic modulus
and Poisson ratio of the random composite are computed. A comparison of
the relative influence of the above two kinds of uncertainty is made. The
effective properties are finally used in the framework of SFEM to obtain
the response of a composite structure and useful conclusions are derived
regarding the effect of random microstructure on the probabilistic
characteristics of the response.
This work is supported by the European Research Council Advanced Grant
''MASTER-Mastering the computational challenges in numerical modeling
and optimum design of CNT reinforced composites'' (ERC-2011-ADG 20110209).
Die Dozenten der Informatik-Institute der Technischen Universität
Braunschweig laden im Rahmen des Informatik-Kolloquiums zu folgendem
Vortrag ein.
Ahmad Dehwah, PhD Candidate in the Electrical Engineering at King Abdullah
University of Science and Technology:
Energy Aware Routing Schemes in Solar Powered Wireless Sensor Networks
for Flash Flood and Traffic Monitoring Applications
Beginn: 10.11.2015, 16:30 Uhr
Ort: TU Braunschweig, Informatikzentrum, Mühlenpfordtstraße 23,
1. OG, Hörsaal M 161
Webseite: http://www.ibr.cs.tu-bs.de/cal/kolloq/2015-11-10-dehwah.html
Kontakt: Prof. Dr.-Ing. Lars Wolf
Wireless sensor networks have enabled the existence of many accurate and
inexpensive monitoring systems that could help in saving people lives
as well as monitoring the environment. Nevertheless, having a long term
operational network is associated with multiple challenges especially for
critical and emergency applications. Our focus is on real-time traffic
monitoring and flash flood detection system using solar powered wireless
sensor networks. As a real-time application, system reliability and energy
management is critical to ensure the system operation thus, we consider
data routing policies in order to optimize the energy. Motivated by
multi-purpose sensor networks, the objective is to find the best network
policy that maximizes the minimal energy among nodes in a sensor network,
over a finite time horizon, given uncertain energy input forecasts. We
first show the derivation of the Mixed Integer Linear Programming (MILP)
counterpart for solving the problem in a centralized manner. Then we
drive the optimal policy that maximizes our specific problem over some
time horizon using forward dynamic programming. Finally, we present
a derivation for the proposed greedy policy that is distributed, and
exhibits significantly lower complexity with a computational time that
outperforms both aforementioned approaches along with the experimental
validation.
