Frühere Termine

Sonderkolloquium (INF), Vijay Ganesh, University of Waterloo, Kanada / am 17.10.2017

17.10.2017 von 14:00 bis 15:00

Institut für Informatik, Christian-Albrechts-Platz 4, 24118 Kiel

Titel: On The Unreasonable Effectiveness of Boolean SAT Solvers

Abstract: Modern conflict-driven clause-learning (CDCL) Boolean SAT solvers routinely solve very large industrial SAT instances in relatively short periods of time. This phenomenon has stumped both theoreticians and practitioners since Boolean satisfiability is an NP-complete problem widely believed to be intractable. It is clear that these solvers somehow exploit the structure of real-world instances. However, to-date there have been few results that precisely characterize this structure or shed any light on why these SAT solvers are so efficient.

In this talk, I will present results that provide a deeper empirical understanding of why CDCL SAT solvers are so efficient, which may eventually lead to a complexity-theoretic result. Our results can be divided into two parts. First, I will talk about structural parameters that can characterize industrial instances and shed light on why they are easier to solve even though they may contain millions of variables compared to small crafted instances with hundreds of variables. Second, I will talk about internals of CDCL SAT solvers, and describe why they are particularly suited to solve industrial instances.

Brief Bio: Dr. Vijay Ganesh is an assistant professor at the University of Waterloo since 2012. Prior to that he was a research scientist at MIT, and completed his PhD in computer science from Stanford University in 2007. Vijay's primary area of research is the theory and practice of automated reasoning aimed at software engineering, formal methods, security, and mathematics. In this context he has led the development of many SAT/SMT solvers, most notably, STP, The Z3 string solver, MapleSAT, and MathCheck. He has also proved several decidability and complexity results relating to the SATisfiability problem for various mathematical theories. For his research, he has won over 20 awards including an ACM Test of Time Award at CCS 2016, two Google Faculty Research Awards in 2011 and 2013, and a Ten-Year Most Influential Paper Award at DATE 2008.

Prof. Nowotka

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Sonderkolloquium (INF), Vijay Ganesh, University of Waterloo, Kanada / am 17.10.2017

17.10.2017 von 14:00 bis 15:00

Institut für Informatik, Christian-Albrechts-Platz 4, 24118 Kiel

Titel: On The Unreasonable Effectiveness of Boolean SAT Solvers

Abstract: Modern conflict-driven clause-learning (CDCL) Boolean SAT solvers routinely solve very large industrial SAT instances in relatively short periods of time. This phenomenon has stumped both theoreticians and practitioners since Boolean satisfiability is an NP-complete problem widely believed to be intractable. It is clear that these solvers somehow exploit the structure of real-world instances. However, to-date there have been few results that precisely characterize this structure or shed any light on why these SAT solvers are so efficient.

In this talk, I will present results that provide a deeper empirical understanding of why CDCL SAT solvers are so efficient, which may eventually lead to a complexity-theoretic result. Our results can be divided into two parts. First, I will talk about structural parameters that can characterize industrial instances and shed light on why they are easier to solve even though they may contain millions of variables compared to small crafted instances with hundreds of variables. Second, I will talk about internals of CDCL SAT solvers, and describe why they are particularly suited to solve industrial instances.

Brief Bio: Dr. Vijay Ganesh is an assistant professor at the University of Waterloo since 2012. Prior to that he was a research scientist at MIT, and completed his PhD in computer science from Stanford University in 2007. Vijay's primary area of research is the theory and practice of automated reasoning aimed at software engineering, formal methods, security, and mathematics. In this context he has led the development of many SAT/SMT solvers, most notably, STP, The Z3 string solver, MapleSAT, and MathCheck. He has also proved several decidability and complexity results relating to the SATisfiability problem for various mathematical theories. For his research, he has won over 20 awards including an ACM Test of Time Award at CCS 2016, two Google Faculty Research Awards in 2011 and 2013, and a Ten-Year Most Influential Paper Award at DATE 2008.

Prof. Nowotka

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Kolloquiumsvortrag, Prof. Dr. Stefan Sauter, Uni Zürich / am 21.07.2017

21.07.2017 von 14:15 bis 15:45

Institut für Informatik, Ludewig-Meyn-Straße 2, 24118 Kiel, Raum: Übungsraum 2/K

Titel: A Family of Crouzeix-Raviart Non-Conforming Finite Elements in Two- and Three Spatial Dimensions

Abstract: In this talk we will present a family of non-conforming "Crouzeix-Raviart" type finite elements in two and three dimensions. They consist of local polynomials of maximal degree p on simplicial finite element meshes while certain jump conditions are imposed across adjacent simplices.

We will prove optimal a priori estimates for these finite elements. The characterization of this space via jump conditions goes back to the seminal paper of Crouzeix and Raviart in 1973. However, the definition is implicit and the derivation of an explicit representation of the local basis functions for general p in 3D was an open problem.

We present explicit representations for these functions by developing some theoretical tools for fully symmetric and reflection symmetric orthogonal polynomials on triangles and their representation.

Finally we will analyze the linear independence of these sets of functions and discuss the question whether they span the whole non-conforming space. This talk comprises joint work with P. Ciarlet Jr., ENSTA, Paris and Charles F. Dunkl, Virginia Tech.

Prof. Börm

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Kolloquiumsvortrag, Prof. Dr. Stefan Sauter, Uni Zürich / am 21.07.2017

21.07.2017 von 14:15 bis 15:45

Institut für Informatik, Ludewig-Meyn-Straße 2, 24118 Kiel, Raum: Übungsraum 2/K

Titel: A Family of Crouzeix-Raviart Non-Conforming Finite Elements in Two- and Three Spatial Dimensions

Abstract: In this talk we will present a family of non-conforming "Crouzeix-Raviart" type finite elements in two and three dimensions. They consist of local polynomials of maximal degree p on simplicial finite element meshes while certain jump conditions are imposed across adjacent simplices.

We will prove optimal a priori estimates for these finite elements. The characterization of this space via jump conditions goes back to the seminal paper of Crouzeix and Raviart in 1973. However, the definition is implicit and the derivation of an explicit representation of the local basis functions for general p in 3D was an open problem.

We present explicit representations for these functions by developing some theoretical tools for fully symmetric and reflection symmetric orthogonal polynomials on triangles and their representation.

Finally we will analyze the linear independence of these sets of functions and discuss the question whether they span the whole non-conforming space. This talk comprises joint work with P. Ciarlet Jr., ENSTA, Paris and Charles F. Dunkl, Virginia Tech.

Prof. Börm

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Power Girls & Power Boys Days

Sonderkolloquium, Prof. Dr. María López Fernández, Universität Zürich / am 18.07.2017

18.07.2017 von 11:00 bis 13:00

Ludewig-Meyn-Str. 2. Raum Ü2/K (LMS2, R. Ü2/K), 24118 Kiel

Titel: Generalized Convolution Quadrature

Abstract: ubich's Convolution Quadrature is nowadays a well
established method for the time discretization of retarded potentials
associated to wave equations. It has been very much developed in the
last decade, both from the theoretical and the algorithmic point of
view. However, despite its nice properties, the Convolution Quadrature
is strictly restricted to the use of fixed time steps. In this talk I
will present the "generalized Convolution Quadrature", a new family of
methods designed to overcome the strong restriction to uniform
temporal grids. I will show stability and convergence estimates and
numerical results illustrating the good behaviour of the new method. I
will also outline the current limitations in the implementation of the
generalized Convolution Quadrature and future possibilities of
development.

Prof. Börm

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Sonderkolloquium, Tomislav Dragicevic, University Aalborg / 12.07.2017

12.07.2017 von 15:00 bis 16:45

Institute Ostufer, Geb. D, "Aquarium", Kaiserstr. 2, 24143 Kiel

Titel: Coordination Strategies for DC Microgrids

Abstract: DC distribution systems have higher efficiency, better current carrying capacity and faster response when compared to conventional AC systems. They also provide more natural interface with many types of RES and ESSs and better compliance with consumer electronics. Furthermore, when components are coupled around a DC bus, there are no issues with reactive power flow, power quality and frequency regulation, resulting in a notably less complex control system when compared to the AC coupled systems. All these facts lead to more and more applications of DC systems in modern power systems, including data/telecom centers, maritime industry, high voltage transmission systems, electric vehicle charging infrastructure, and DC microgrids. Still, design and operation of general DC systems imposes a number of specific challenges. The aim of this lecture is in particular to present functionalities of different coordinated control strategies for DC microgrids. In this context, centralized, decentralized and distributed controls are assessed. Decentralized control can be regarded as an extension of local control since it is also based exclusively on local measurements. In contrast, centralized and distributed control strategies rely on digital communication technologies. A number of approaches of using these three coordinated control strategies to achieve various control objectives are reviewed in the paper. Moreover, properties of DC MG dynamics and stability are discussed.

Prof. Liserre

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Sonderkolloquium, Tomislav Dragicevic, University Aalborg / 12.07.2017

12.07.2017 von 15:00 bis 16:45

Institute Ostufer, Geb. D, "Aquarium", Kaiserstr. 2, 24143 Kiel

Titel: Coordination Strategies for DC Microgrids

Abstract: DC distribution systems have higher efficiency, better current carrying capacity and faster response when compared to conventional AC systems. They also provide more natural interface with many types of RES and ESSs and better compliance with consumer electronics. Furthermore, when components are coupled around a DC bus, there are no issues with reactive power flow, power quality and frequency regulation, resulting in a notably less complex control system when compared to the AC coupled systems. All these facts lead to more and more applications of DC systems in modern power systems, including data/telecom centers, maritime industry, high voltage transmission systems, electric vehicle charging infrastructure, and DC microgrids. Still, design and operation of general DC systems imposes a number of specific challenges. The aim of this lecture is in particular to present functionalities of different coordinated control strategies for DC microgrids. In this context, centralized, decentralized and distributed controls are assessed. Decentralized control can be regarded as an extension of local control since it is also based exclusively on local measurements. In contrast, centralized and distributed control strategies rely on digital communication technologies. A number of approaches of using these three coordinated control strategies to achieve various control objectives are reviewed in the paper. Moreover, properties of DC MG dynamics and stability are discussed.

Prof. Liserre

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Kolloquiumsvortrag, Prof. Grandoni, IDSIA USI-SUPSI in Lugano / am 07.07.2017

07.07.2017 von 14:15 bis 15:45

Institut für Informatik, Ludewig-Meyn-Str. 2, Raum Ü2/K (LMS2, R. Ü2/K), 24114 Kiel

Titel: Approximating Geometric Knapsack via L-packings

Abstract: Joint work with: Waldo Galvez, Sandy Heydrich, Salvatore Ingala,
Arindam Khan, Andreas Wiese

In the 2-dimensional geometric knapsack problem (2DK) we are given a
set of n axis-aligned rectangular items, each one with an associated
profit, and an axis-aligned square knapsack. The goal is to find a
(non-overlapping) packing of a maximum profit subset of items inside
the knapsack (without rotating items). The best-known polynomial-time
approximation factor for this problem (even just in the cardinality
case) is 2 + ε [Jansen and Zhang, SODA 2004]. In this work we break
the 2 approximation barrier, achieving a polynomial-time 17/9 + ε <
1.89 approximation, which improves to 558/325+ ε < 1.72 in the
cardinality case.

Essentially all prior work on 2DK approximation packs items inside a
constant number of rectangular containers, where items inside each
container are packed using a simple greedy strategy. We deviate for
the first time from this setting: we show that there exists a large
profit solution where items are packed inside a constant number of
containers plus one L-shaped region at the boundary of the knapsack
which contains items that are high and narrow and items that are wide
and thin. The items of these two types possibly interact in a complex
manner at the corner of the L.

The above structural result is not enough however: the best-known
approximation ratio for the sub-problem in the L-shaped region is 2 +
ε (obtained via a trivial reduction to 1-dimensional knapsack by
considering tall or wide items only). Indeed this is one of the
simplest special settings of the problem for which this is the best
known approximation factor. As a second major, and the main
algorithmic contribution of this work, we present a PTAS for this
case. We believe that this will turn out to be useful in future work
in geometric packing problems.

We also consider the variant of the problem with rotations (2DKR),
where items can be rotated by 90 degrees. Also in this case the
best-known polynomial-time approximation factor (even for the
cardinality case) is 2 + ε [Jansen and Zhang, SODA 2004]. Exploiting
part of the machinery developed for 2DK plus a few additional ideas,
we obtain a polynomial-time 3/2 + ε-approximation for 2DKR, which
improves to 4/3 + ε in the cardinality case.

Prof. Jansen

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Kolloquiumsvortrag, Prof. Grandoni, IDSIA USI-SUPSI in Lugano / am 07.07.2017

07.07.2017 von 14:15 bis 15:45

Institut für Informatik, Ludewig-Meyn-Str. 2, Raum Ü2/K (LMS2, R. Ü2/K), 24114 Kiel

Titel: Approximating Geometric Knapsack via L-packings

Abstract: Joint work with: Waldo Galvez, Sandy Heydrich, Salvatore Ingala,
Arindam Khan, Andreas Wiese

In the 2-dimensional geometric knapsack problem (2DK) we are given a
set of n axis-aligned rectangular items, each one with an associated
profit, and an axis-aligned square knapsack. The goal is to find a
(non-overlapping) packing of a maximum profit subset of items inside
the knapsack (without rotating items). The best-known polynomial-time
approximation factor for this problem (even just in the cardinality
case) is 2 + ε [Jansen and Zhang, SODA 2004]. In this work we break
the 2 approximation barrier, achieving a polynomial-time 17/9 + ε <
1.89 approximation, which improves to 558/325+ ε < 1.72 in the
cardinality case.

Essentially all prior work on 2DK approximation packs items inside a
constant number of rectangular containers, where items inside each
container are packed using a simple greedy strategy. We deviate for
the first time from this setting: we show that there exists a large
profit solution where items are packed inside a constant number of
containers plus one L-shaped region at the boundary of the knapsack
which contains items that are high and narrow and items that are wide
and thin. The items of these two types possibly interact in a complex
manner at the corner of the L.

The above structural result is not enough however: the best-known
approximation ratio for the sub-problem in the L-shaped region is 2 +
ε (obtained via a trivial reduction to 1-dimensional knapsack by
considering tall or wide items only). Indeed this is one of the
simplest special settings of the problem for which this is the best
known approximation factor. As a second major, and the main
algorithmic contribution of this work, we present a PTAS for this
case. We believe that this will turn out to be useful in future work
in geometric packing problems.

We also consider the variant of the problem with rotations (2DKR),
where items can be rotated by 90 degrees. Also in this case the
best-known polynomial-time approximation factor (even for the
cardinality case) is 2 + ε [Jansen and Zhang, SODA 2004]. Exploiting
part of the machinery developed for 2DK plus a few additional ideas,
we obtain a polynomial-time 3/2 + ε-approximation for 2DKR, which
improves to 4/3 + ε in the cardinality case.

Prof. Jansen

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Sonderkolloquium, Jun.-Prof. Dr. Mattias Heinrich, Uni Lübeck / am 07.07.2017

07.07.2017 von 14:15 bis 15:45

Institut für Informatik,Christian-Albrechts-Platz 4, R.715, 24114 Kiel

Titel: Learning Sparse Binary Features for Medical Image Segmentation of the Abdomen

Abstract: In this talk, we explore the capabilities of sparse binary features for medical image segmentation. Due to insufficient contrast and anatomical shape variations local image patches rarely provide sufficient information for accurate segmentation of abdominal structures. Based on our two recent MICCAI papers, we propose to use long-range binary features to robustly capture the image context. Two different classification strategies are subsequently developed. 

First, a very fast approximate nearest neighbour search based on vantage point forests and Hamming distances between feature strings is presented. The classifier can be learned and applied to new data in few seconds. The approach reaches state-of-the-art performance for larger organs on the VISCERAL3 benchmark.

Second, we develop a deep neural network architecture that combines a local CNN path with a new contextual path that encodes the sparse binary features. Following the ideas from Network-in-Network, 1x1 convolutions are employed to learn the best combination of different binary offset locations. We demonstrate experimentally that this restricted feature extraction in the first layer enables to regularise the network with a huge receptive field and leads to short training times of less than 10 minutes. Using only 1 million trainable parameters, the model achieves a accuracy of 64.5% Dice, which is comparable to the best performing, much more complex deep CNN approach for pancreas segmentation.

Finally, the potential use of learned binary features for other tasks in medical image analysis, such as image registration and disease classification will be discussed.

Prof. Carsten Meyer

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Sonderkolloquium, Jun.-Prof. Dr. Mattias Heinrich, Uni Lübeck / am 07.07.2017

07.07.2017 von 14:15 bis 15:45

Institut für Informatik,Christian-Albrechts-Platz 4, R.715, 24114 Kiel

Titel: Learning Sparse Binary Features for Medical Image Segmentation of the Abdomen

Abstract: In this talk, we explore the capabilities of sparse binary features for medical image segmentation. Due to insufficient contrast and anatomical shape variations local image patches rarely provide sufficient information for accurate segmentation of abdominal structures. Based on our two recent MICCAI papers, we propose to use long-range binary features to robustly capture the image context. Two different classification strategies are subsequently developed. 

First, a very fast approximate nearest neighbour search based on vantage point forests and Hamming distances between feature strings is presented. The classifier can be learned and applied to new data in few seconds. The approach reaches state-of-the-art performance for larger organs on the VISCERAL3 benchmark.

Second, we develop a deep neural network architecture that combines a local CNN path with a new contextual path that encodes the sparse binary features. Following the ideas from Network-in-Network, 1x1 convolutions are employed to learn the best combination of different binary offset locations. We demonstrate experimentally that this restricted feature extraction in the first layer enables to regularise the network with a huge receptive field and leads to short training times of less than 10 minutes. Using only 1 million trainable parameters, the model achieves a accuracy of 64.5% Dice, which is comparable to the best performing, much more complex deep CNN approach for pancreas segmentation.

Finally, the potential use of learned binary features for other tasks in medical image analysis, such as image registration and disease classification will be discussed.

 

Prof. Meyer

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Kolloquiumsvortrag, Carsten Grashoff, Max Planck Institute of Biochemistry / am 03.07.2017

Kolloquiumsvortrag, Carsten Grashoff / am 03.07.2017

03.07.2017 von 17:15 bis 18:45

Institute Ostufer, Geb. D, "Aquarium", Kaiserstr. 2, 24143 Kiel

Titel: Piconewton-sensitive biosensors to investigate molecular forces in cells

Abstract: The ability of cells to adhere and simultaneously sense differences in tissue stiffness is crucial for organ development and function. Yet, the molecular mechanisms by which cells sense extracellular matrix rigidity have remained unknown because suitable techniques to measure mechanical forces across intracellular proteins in living cells were missing.

We therefore develop novel, single-molecule‒calibrated tension sensor modules that allow the analysis of a physiologically highly relevant force regime in cells. Our new probes are sensitive to forces of 3–5 piconewton (pN), 6–8 pN and 9–11 pN, respectively; they are characterized by fast folding/unfolding transitions, reversibility and a sharp force-response threshold (1, 2, 3). By applying these new probes to the cell adhesion proteins talin-1 and talin-2, we demonstrate that these central integrin activators establish intracellular, mechanical linkages that bear mechanical forces of about 7–10 pN upon cell adhesion and are regulated by f-actin and vinculin association. We find that the integrin–talin–actin linkage is indispensable for extracellular rigidity sensing and, surprisingly, talin isoform-specific (1). Furthermore, multiplexing distinct tension sensor constructs by dual-color FLIM reveals an unexpected intramolecular tension gradient across talin that is modulated by intracellular signals and extracellular rigidity (3).

References:

1. Austen KA et al., and Grashoff C. 2015. Nat Cell Biol.

2. Freikamp A, Cost AL, and Grashoff C. 2016. Trends Cell Biol.

3. Ringer et al., and Grashoff C. 2017. under review

Prof. Christine Selhuber-Unkel

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Sommerfest 2017

Kolloquiumsvortrag, Antrittsvorlesung Prof. Kapels / am 26.06.2017

26.06.2017 von 17:15 bis 18:45

Institute Ostufer, Geb. D, "Aquarium", Kaiserstr. 2, 24143 Kiel

Titel: Von der Siliziumtechnologie zu Wide-Bandgap Leistungshalbleitern

Abstract: Kontinuierliche Innovationen im Bereich der siliziumbasierten Leistungshalbleiterbauelemente ermöglichten grundlegende Fortschritte für eine effiziente dezentrale Energieversorgung, die Weiterentwicklung der Elektromobilität und energieeffiziente Stromrichter für Industrie- und Consumer-Anwendungen. Aktuelle Trends in Leistungsdichte und Gewicht werden jedoch zunehmend nicht mehr mit Halbleiterbauelementen auf Siliziumbasis erfüllt werden können. Leistungstransistoren auf Basis von SiC und GaN ermöglichen hier Zukunftspotentiale zu heben. Die Vorlesung zeigt die wesentlichen Bauelementekonzepte, aktuelle Herausforderungen und Lösungen auf.

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Kolloquiumsvortrag, Antrittsvorlesung Prof. Kapels / am 26.06.2017

26.06.2017 von 17:15 bis 18:45

Institute Ostufer, Geb. D, "Aquarium", Kaiserstr. 2, 24143 Kiel

Titel: Von der Siliziumtechnologie zu Wide-Bandgap Leistungshalbleitern

Abstract: Kontinuierliche Innovationen im Bereich der siliziumbasierten Leistungshalbleiterbauelemente ermöglichten grundlegende Fortschritte für eine effiziente dezentrale Energieversorgung, die Weiterentwicklung der Elektromobilität und energieeffiziente Stromrichter für Industrie- und Consumer-Anwendungen. Aktuelle Trends in Leistungsdichte und Gewicht werden jedoch zunehmend nicht mehr mit Halbleiterbauelementen auf Siliziumbasis erfüllt werden können. Leistungstransistoren auf Basis von SiC und GaN ermöglichen hier Zukunftspotentiale zu heben. Die Vorlesung zeigt die wesentlichen Bauelementekonzepte, aktuelle Herausforderungen und Lösungen auf.

Prof. Kapels

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Sonderkolloquium, Prof. R.D. Lorenz, University of Wisconsin-Madison / 23.06.2017

23.06.2017 von 13:00 bis 15:00

Institute Ostufer, Geb. D, "Aquarium", Kaiserstr. 2, 24143 Kiel

Titel: Disruptive Paradigm Changes for Electrical Machines and Electrical Drives

Abstract: Electric machine design paradigms have been dramatically changed by the need to meet the demands for minimizing losses and smooth torque control during driving cycles with widely vary loads and speeds.  Simultaneously, new drive control paradigms systematically out-perform industry standard field oriented control (FOC) and simultaneously solve several classical problems with FOC. In addition, the internet of things is opening expansive opportunities for motor drives.  This presentation with focus on these disruptive changes in the paradigms for electric machines and electrical drives and explore the opportunities for innovation that these technologies provide.

Affiliation:

Chaired Professor and Co-Director of WEMPEC at the University of Wisconsin-Madison, in Madison, Wisconsin, USA

Short Bio:

Prof. Robert D. (Bob) Lorenz is a Life Fellow of IEEE, Past President of IEEE IAS, and Past Member of the IEEE Board of Directors. He is a Chaired Professor at the University of Wisconsin-Madison and Co-Director of the Wisconsin Electric Machines and Power Electronics Consortium (WEMPEC) which just celebrated its 36th Anniversary with over 85 international sponsor firms.    He has pioneered core technologies for physics-based control design, self-sensing, flux observers, current regulators, deadbeat-direct torque and flux control, variable flux and variable magnetization state PM machines and power semiconductor temperature and strain control and has won 33 prize paper awards from the IEEE.

Prof. Liserre

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Sonderkolloquium, Prof. R.D. Lorenz, University of Wisconsin-Madison / 23.06.2017

23.06.2017 von 13:00 bis 15:00

Institute Ostufer, Geb. D, "Aquarium", Kaiserstr. 2, 24143 Kiel

Titel: Disruptive Paradigm Changes for Electrical Machines and Electrical Drives

Abstract: Electric machine design paradigms have been dramatically changed by the need to meet the demands for minimizing losses and smooth torque control during driving cycles with widely vary loads and speeds.  Simultaneously, new drive control paradigms systematically out-perform industry standard field oriented control (FOC) and simultaneously solve several classical problems with FOC. In addition, the internet of things is opening expansive opportunities for motor drives.  This presentation with focus on these disruptive changes in the paradigms for electric machines and electrical drives and explore the opportunities for innovation that these technologies provide.

Affiliation:

Chaired Professor and Co-Director of WEMPEC at the University of Wisconsin-Madison, in Madison, Wisconsin, USA

Short Bio:

Prof. Robert D. (Bob) Lorenz is a Life Fellow of IEEE, Past President of IEEE IAS, and Past Member of the IEEE Board of Directors. He is a Chaired Professor at the University of Wisconsin-Madison and Co-Director of the Wisconsin Electric Machines and Power Electronics Consortium (WEMPEC) which just celebrated its 36th Anniversary with over 85 international sponsor firms.    He has pioneered core technologies for physics-based control design, self-sensing, flux observers, current regulators, deadbeat-direct torque and flux control, variable flux and variable magnetization state PM machines and power semiconductor temperature and strain control and has won 33 prize paper awards from the IEEE.

Prof. Liserre

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Sonderkolloquium Prof. Tamulevicius, Technische Universität Kaunas / am 20.06.2017

20.06.2017 von 17:15 bis 18:45

Technische Fakultät, Institut für Materialwissenschaft, Kaiserstr. 2, Kiel, Raum: "Aquarium", Geb. D

Titel: Nanoparticles, nanocomposites - from optics to medicine

Abstract: Principles of deposition and applications of diamond-like carbon thin films, diamond-like carbon-based nanocomposites including metallic nanoparticles as well as capillary assisted deposition of nanoparticles will be presented, thereby concentrating on the optical, electrical  properties and the use of the assembly of particles as building blocks for optical sensors and antimicrobial surfaces. Features of localized surface plasmon effects, surface enhanced Raman scattering, detection of ultrafast energy transfer processes will be discussed.

Prof. Faupel

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Sonderkolloquium Prof. Tamulevicius, Technische Universität Kaunas / am 20.06.2017

20.06.2017 von 17:15 bis 18:45

Technische Fakultät, Institut für Materialwissenschaft, Kaiserstr. 2, Kiel, Raum: "Aquarium", Geb. D

Titel: Nanoparticles, nanocomposites - from optics to medicine

Abstract: Principles of deposition and applications of diamond-like carbon thin films, diamond-like carbon-based nanocomposites including metallic nanoparticles as well as capillary assisted deposition of nanoparticles will be presented, thereby concentrating on the optical, electrical  properties and the use of the assembly of particles as building blocks for optical sensors and antimicrobial surfaces. Features of localized surface plasmon effects, surface enhanced Raman scattering, detection of ultrafast energy transfer processes will be discussed.

Prof. Faupel

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Kolloquiumsvortrag, Prof. Dr.-Ing. Mücklich, Functional Materials, Dept. Mat. Science & Engineering, Saarland University / am 19.06.2017

19.06.2017 von 17:15 bis 18:45

Institute Ostufer, Geb. D, "Aquarium", Kaiserstr. 2, 24143 Kiel

Titel: Optimized functionality by 3D microstructure research and efficient surface patterning

Abstract: In the introduction a short overview will be given concerning the three units of the institute, such as the chair for functions materials which is dedicated to fundamental research and teaching, the European School of Materials, which is focused on the international study programs on all academic levels and the Material Engineering Center Saarland, which is promoted by applied research and transfer activities. Then some of the research activities will be discussed based on three main questions:

-          How does 3D microstructure research on the micro, nano and atomic scale help to understand the quantitative relations between microstructure formation and properties  

-          How does the initial 3D morphology control the processing and formation of microstructures and

-          How can Direct Laser Interference Patterning be exploited to design optimized surface functionalities

Prof. Quandt

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Kolloquiumsvortrag, Prof. Dr.-Ing. Mücklich, Functional Materials, Dept. Mat. Science & Engineering, Saarland University / am 19.06.2017

19.06.2017 von 17:15 bis 18:45

Institute Ostufer, Geb. D, "Aquarium", Kaiserstr. 2, 24143 Kiel

Titel: Optimized functionality by 3D microstructure research and efficient surface patterning

Abstract: In the introduction a short overview will be given concerning the three units of the institute, such as the chair for functions materials which is dedicated to fundamental research and teaching, the European School of Materials, which is focused on the international study programs on all academic levels and the Material Engineering Center Saarland, which is promoted by applied research and transfer activities. Then some of the research activities will be discussed based on three main questions:

-          How does 3D microstructure research on the micro, nano and atomic scale help to understand the quantitative relations between microstructure formation and properties  

-          How does the initial 3D morphology control the processing and formation of microstructures and

-          How can Direct Laser Interference Patterning be exploited to design optimized surface functionalities

Prof. Quandt

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Kolloquiumsvortrag, Prof. Herbert Jäger, Jacobs University Bremen / am 12.06.2017

12.06.2017 von 17:15 bis 18:45

Institut für Elektrotechnik und Informationstechnik, Geb. D, "Aquarium", Kaiserstr. 2, 24143 Kiel

Thema: An introduction to Reservoir Computing


Abstract: Recurrent neural networks (RNNs) are general approximators for nonlinear dynamical systems and have recently become widely used in the "deep learning" field of machine learning, especially for speech and language processing tasks. For instance, Google's speech recognition and language translation services are based on RNNs.

However, the deep learning set-ups for RNN training are computationally very expensive, require very large volumes of training data, and need high-precision numerical processing. For such reasons, deep-learning variants of RNNs are problematic in fields where training data are scarce, where fast and cheap algorithms are desired, or where noisy or low-precision hardware is to be used. This is often the case in domains of nonlinear signal processing, control, brain-machine interfacing, or biomedical signal processing.

Reservoir Computing (RC) is an alternative machine learning approach for RNNs which is in many aspects complementary to the ways of deep learning. In RC, a large, random, possibly low-precision and noisy RNN is used as a nonlinear excitable medium - called the "reservoir" - which is driven by an input signal. The reservoir itself is not adapted or trained. Instead, only a "readout" mechanism is trained, which assembles the desired output signal from the large variety of random, excited signals within the reservoir. This readout training is cheap - typically just a linear regression. RC has become a popular approach in research that aims at useful computations on the basis on unconventional hardware (non-digital, noisy, low-precision).

The talk gives an introduction to the basic principles and variants of RC. Numerous examples will be presented according to wishes from the audience.

Prof. Hermann Kohlstedt

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Kolloquiumsvortrag, Prof. Herbert Jäger, Jacobs University Bremen / am 12.06.2017

Sonderkolloquium, Prof. Remus Teodorescu, Universität Aalborg / 12.06.2017

12.06.2017 von 15:15 bis 16:45

Institute Ostufer, Geb. D, "Aquarium", Kaiserstr. 2, 24143 Kiel

Titel: Modular Multilevel Converter Research at Aalborg University

Abstract:This presentation is aiming on summarizing the main features of the recently published book: Design, Control, and Application of Modular Multilevel Converters for HVDC Transmission Systems, ISBN: 978-1-118-85156-2, Wiley 2016http://eu.wiley.com/WileyCDA/WileyTitle/productCd-1118851560.html#. Special focus will be on Control under unbalanced conditions of MMC.

Prof. Liserre

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Sonderkolloquium, Prof. Remus Teodorescu, Universität Aalborg / 12.06.2017

Kolloquiumsvortrag, PhD Tammy Riklin Raviv, Ben-Gurion-University of the Negev, Beer Sheva, Israel / am 09.06.2017

09.06.2017 von 13:30 bis 15:00

Institut für Informatik, Ludewig-Meyn-Straße 2, 24118 Kiel, Raum: Übungsraum 2/K

Titel:

Ensemble of Expert Deep Neural Networks for Spatio-Temporal Denoising of Contrast-Enhanced MRI Sequences

Abstract:

Abstract: Dynamic contrast-enhanced MRI (DCE-MRI) is an imaging protocol where MRI scans are acquired repetitively throughout the injection of a contrast agent. The analysis of dynamic scans is widely used for the detection and quantification of blood-brain barrier (BBB) permeability. Extraction of the pharmacokinetic (PK) parameters from the DCE-MRI concentration curves allows quantitative assessment of the integrity of the BBB functionality. However, curve fitting required for the analysis of DCE-MRI data is error-prone as the dynamic scans are subject to non-white, spatially dependent and anisotropic noise.

We present a novel spatio-temporal framework based on Deep Convolution Neural Networks (DCNNs) to address the DCE-MRI denoising challenges. This is accomplished by an ensemble of expert DCNNs constructed as deep autoencoders, where each is trained on a specific subset of the input space to accommodate different noise characteristics and curve prototypes. The most likely reconstructed curves are then chosen using a classifier DCNN followed by a quadratic programming optimization. As clean signals (ground-truth)

for training are not available, a fully automatic model for generating realistic training sets with complex nonlinear dynamics is introduced. The proposed approach has been applied to full and even temporally down-sampled DCE-MRI datasets acquired by MRI machines in different locations and of different manufacturers and is shown to favorably compare to state-of-the-art denoising methods.

Prof. Carsten Meyer

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Kolloquiumsvortrag, PhD Tammy Riklin Raviv, Ben-Gurion-University of the Negev, Beer Sheva, Israel / am 09.06.2017

09.06.2017 von 13:30 bis 15:00

Institut für Informatik, Ludewig-Meyn-Straße 2, 24118 Kiel, Raum: Übungsraum 2/K

Titel:Ensemble of Expert Deep Neural Networks for Spatio-Temporal Denoising of Contrast-Enhanced MRI Sequences

Abstract: Abstract: Dynamic contrast-enhanced MRI (DCE-MRI) is an imaging protocol where MRI scans are acquired repetitively throughout the injection of a contrast agent. The analysis of dynamic scans is widely used for the detection and quantification of blood-brain barrier (BBB) permeability. Extraction of the pharmacokinetic (PK) parameters from the DCE-MRI concentration curves allows quantitative assessment of the integrity of the BBB functionality. However, curve fitting required for the analysis of DCE-MRI data is error-prone as the dynamic scans are subject to non-white, spatially dependent and anisotropic noise.

We present a novel spatio-temporal framework based on Deep Convolution Neural Networks (DCNNs) to address the DCE-MRI denoising challenges. This is accomplished by an ensemble of expert DCNNs constructed as deep autoencoders, where each is trained on a specific subset of the input space to accommodate different noise characteristics and curve prototypes. The most likely reconstructed curves are then chosen using a classifier DCNN followed by a quadratic programming optimization. As clean signals (ground-truth)

for training are not available, a fully automatic model for generating realistic training sets with complex nonlinear dynamics is introduced. The proposed approach has been applied to full and even temporally down-sampled DCE-MRI datasets acquired by MRI machines in different locations and of different manufacturers and is shown to favorably compare to state-of-the-art denoising methods.

Prof. Carsten Meyer

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Intelligente Materialien: Europäische Konferenz zum dritten Mal in Kiel

Sonderkolloquium, Prof. Dr. Raj, Universität Agra, Indien / am 08.06.2017

08.06.2017 von 11:30 bis 13:00

Institut für Informatik, Christian-Albrechts-Platz 4, Raum: 910 (CAP 4), 24118 Kiel

Titel: Finite Element Modelling and Simulation of Selected Bulk Nano-material Processing Techniques

Abstract: A brief review of the material modeling such as visco-plastic, coupled thermo visco-plastic along with mathematical formulation is presented with application to forming of Bulk Nano-structured Materials using Severe Plastic Deformation(SPD). The material is assumed to be homogeneous, isotropic, incompressible. Elasticity is neglected and the material behavior chosen is given by the Norton-Hoff law. A power law is used to simulate the friction between the die and the work-piece. The flow problem with a given temperature distribution is solved simultaneously with the heat diffusion equation. Using the Penalty approach to enforce approximate incompressibility, the Variational principle is applied. This finds the velocity field solution of the problem by minimizing the functional. The coupling between the mechanical and the thermal problems is obtained through the dependency of the consistency of the material with temperature. Being a non-steady state process, SPD is analyzed by using small steady-like deformation steps. The usual finite element method is used to discretize the two problems at a given state Ω(t), and in the axi-symmetrical case the interpolation of the variables is performed in the (r2, z) space. The SPD processes that are modeled are Equal Channel Angular Pressing (ECAP), Twist Extrusion (TE), Accumulative Roll Bonding(ARB), Repetitive Corrugation and Straightening (RCS) and High Pressure Torsion (HPT). Finite Element Modeling and experimentation of these SPD processes is presented in this paper.

Prof. Srivastav

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Sonderkolloquium, Prof. Dr. Raj, Universität Agra, Indien / am 08.06.2017

08.06.2017 von 11:30 bis 13:00

Institut für Informatik, Christian-Albrechts-Platz 4, Raum: 910 (CAP 4), 24118 Kiel

Titel: Finite Element Modelling and Simulation of Selected Bulk Nano-material Processing Techniques

Abstract: A brief review of the material modeling such as visco-plastic, coupled thermo visco-plastic along with mathematical formulation is presented with application to forming of Bulk Nano-structured Materials using Severe Plastic Deformation(SPD). The material is assumed to be homogeneous, isotropic, incompressible. Elasticity is neglected and the material behavior chosen is given by the Norton-Hoff law. A power law is used to simulate the friction between the die and the work-piece. The flow problem with a given temperature distribution is solved simultaneously with the heat diffusion equation. Using the Penalty approach to enforce approximate incompressibility, the Variational principle is applied. This finds the velocity field solution of the problem by minimizing the functional. The coupling between the mechanical and the thermal problems is obtained through the dependency of the consistency of the material with temperature. Being a non-steady state process, SPD is analyzed by using small steady-like deformation steps. The usual finite element method is used to discretize the two problems at a given state Ω(t), and in the axi-symmetrical case the interpolation of the variables is performed in the (r2, z) space. The SPD processes that are modeled are Equal Channel Angular Pressing (ECAP), Twist Extrusion (TE), Accumulative Roll Bonding(ARB), Repetitive Corrugation and Straightening (RCS) and High Pressure Torsion (HPT). Finite Element Modeling and experimentation of these SPD processes is presented in this paper.

Prof. Srivastav

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Kolloquiumsvortrag, Prof. Dr. Helmut Harbrecht, Uni Basel / am 02.06.2017

02.06.2017 von 14:15 bis 15:45

Institut für Informatik, Ludewig-Meyn-Straße 2, 24118 Kiel, Raum: Übungsraum 2/K

Titel: On multilevel quadrature for elliptic partial differential equations with random input

Abstract: This talk is dedicated to multilevel quadrature methods for the rapid solution of partial differential equations with a random input parameter. The key idea of such approaches is a sparse-grid approximation of the occurring product space between the stochastic and the spatial variable. We develop the mathematical theory and present error estimates for the computation of the solution’s moments with focus on the mean and the variance in case of second order elliptic boundary value problems with random diffusion. In particular, the present framework covers the multilevel Monte Carlo method and the multilevel quasi-Monte Carlo method as special cases. The theoretical findings are supplemented by numerical experiments.

Prof. Börm

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Kolloquiumsvortrag, Prof. Dr. Helmut Harbrecht, Uni Basel / am 02.06.2017

02.06.2017 von 14:15 bis 15:45

Institut für Informatik, Ludewig-Meyn-Straße 2, 24118 Kiel, Raum: Übungsraum 2/K

Titel: On multilevel quadrature for elliptic partial differential equations with random input

Abstract: This talk is dedicated to multilevel quadrature methods for the rapid solution of partial differential equations with a random input parameter. The key idea of such approaches is a sparse-grid approximation of the occurring product space between the stochastic and the spatial variable. We develop the mathematical theory and present error estimates for the computation of the solution’s moments with focus on the mean and the variance in case of second order elliptic boundary value problems with random diffusion. In particular, the present framework covers the multilevel Monte Carlo method and the multilevel quasi-Monte Carlo method as special cases. The theoretical findings are supplemented by numerical experiments.

Prof. Börm

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Kolloquiumsvortrag, Dr. Barth, ehem. Airbus Defense / am 22.05.2017

22.05.2017 von 17:15 bis 18:45

Institute Ostufer, Geb. D, "Aquarium", Kaiserstr. 2, 24143 Kiel

Titel: Hochfrequenz-Filterdesign unter Berücksichtigung hoher Transmissionsleistung

Abstract: Das Design von Hohlleiterfiltern mit Hilfe der Softwareprogramme HFSS, MATHCAD und AWR wird beschrieben. Das Design berücksichtigt die hohe Transmissionsleistung (hier 40KW gepulst), die bei Radargeräten auftritt und den Entwickler vor besondere Herausforderung stellt. Die Designmethode ist äußerst präzise, so dass die Anforderungen an das Filter schon im ersten Designschritt erreicht werden. Eine Abstimmung, die Feldkonzentrationen und damit Überschläge in den Filterresonatoren hervorrufen könnten, ist damit nicht nötig. Trotzdem wird eine Abstimmmethode bei hohen Feldstärken diskutiert.

Ein Filter, das für die Luftraumüberwachung eines Flughafens konstruiert wurde und dort auch seit Jahren in Betrieb ist, wird als Beispiel vorgestellt.

Prof. Höft

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Kolloquiumsvortrag, Dr. Barth / am 22.05.2017

22.05.2017 von 17:15 bis 18:45

Institute Ostufer, Geb. D, "Aquarium", Kaiserstr. 2, 24143 Kiel

Titel: Hochfrequenz-Filterdesign unter Berücksichtigung hoher Transmissionsleistung

Abstract: Das Design von Hohlleiterfiltern mit Hilfe der Softwareprogramme HFSS, MATHCAD und AWR wird beschrieben. Das Design berücksichtigt die hohe Transmissionsleistung (hier 40KW gepulst), die bei Radargeräten auftritt und den Entwickler vor besondere Herausforderung stellt. Die Designmethode ist äußerst präzise, so dass die Anforderungen an das Filter schon im ersten Designschritt erreicht werden. Eine Abstimmung, die Feldkonzentrationen und damit Überschläge in den Filterresonatoren hervorrufen könnten, ist damit nicht nötig. Trotzdem wird eine Abstimmmethode bei hohen Feldstärken diskutiert.

Ein Filter, das für die Luftraumüberwachung eines Flughafens konstruiert wurde und dort auch seit Jahren in Betrieb ist, wird als Beispiel vorgestellt.

Prof. Höft

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Kolloquiumsvortrag, Prof. Knut Graichen, Institut für Mess-, Regel- und Mikrotechnik, Universität Ulm / am 15.05.2017

15.05.2017 von 17:15 bis 18:45

Institute Ostufer, Geb. D, "Aquarium", Kaiserstr. 2, 24143 Kiel

Titel: Eingebettete nichtlineare Optimierung und MPC im (Sub-)Millisekundenbereich

Abstract: Nichtlineare Optimierungsverfahren und deren Anwendung im Zusammenhang mit der nichtlinearen modellprädiktiven Regelung (NMPC) sind in der Regelungstechnik insbesondere für dynamische Systeme mit mehreren Stellgrößen und zur Berücksichtigung von Systembeschränkungen von zunehmender Bedeutung. Eine Herausforderung bei der Umsetzung dieser Verfahren in der Praxis ist jedoch der hohe numerische Aufwand und die algorithmische Komplexität, insbesondere bei hochdynamischen Systemen mit Abtastzeiten im (Sub-)Millisekundenbereich. Die Problematik der Umsetzbarkeit wird durch die Tatsache weiter verschärft, dass Hardware-Lösungen in der industriellen Praxis häufig sehr limitierte Ressourcen besitzen. Als Beispiele seien Speicherprogrammierbare Steuerungen (SPS) oder Steuergeräte (Electronic Control Unit – ECU) genannt. Diesen Herausforderungen kann im Sinne eines eingebetteten Entwurfs durch die Verwendung von zugeschnittenen Optimierungsalgorithmen in Kombination mit einer echtzeitfähigen Auswertung begegnet werden.
Im Hinblick auf die oben genannten Herausforderungen präsentiert der Vortrag einen Ansatz zur nichtlinearen dynamischen Optimierung und modellprädiktiven Regelung, der eine echtzeitfähige Umsetzung selbst auf leistungsschwacher Hardware ermöglicht. Neben der methodischen und algorithmischen Vorstellung wird das Verfahren anhand von ausgewählten mechatronischen Beispielen erläutert.

Prof. Thomas Meurer

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Kolloquiumsvortrag, Prof. Knut Graichen, Institut für Mess-, Regel- und Mikrotechnik, Universität Ulm / am 15.05.2017

15.05.2017 von 17:15 bis 18:45

Institute Ostufer, Geb. D, "Aquarium", Kaiserstr. 2, 24143 Kiel

Titel: Eingebettete nichtlineare Optimierung und MPC im (Sub-)Millisekundenbereich

Abstract: Nichtlineare Optimierungsverfahren und deren Anwendung im Zusammenhang mit der nichtlinearen modellprädiktiven Regelung (NMPC) sind in der Regelungstechnik insbesondere für dynamische Systeme mit mehreren Stellgrößen und zur Berücksichtigung von Systembeschränkungen von zunehmender Bedeutung. Eine Herausforderung bei der Umsetzung dieser Verfahren in der Praxis ist jedoch der hohe numerische Aufwand und die algorithmische Komplexität, insbesondere bei hochdynamischen Systemen mit Abtastzeiten im (Sub-)Millisekundenbereich. Die Problematik der Umsetzbarkeit wird durch die Tatsache weiter verschärft, dass Hardware-Lösungen in der industriellen Praxis häufig sehr limitierte Ressourcen besitzen. Als Beispiele seien Speicherprogrammierbare Steuerungen (SPS) oder Steuergeräte (Electronic Control Unit – ECU) genannt. Diesen Herausforderungen kann im Sinne eines eingebetteten Entwurfs durch die Verwendung von zugeschnittenen Optimierungsalgorithmen in Kombination mit einer echtzeitfähigen Auswertung begegnet werden.
Im Hinblick auf die oben genannten Herausforderungen präsentiert der Vortrag einen Ansatz zur nichtlinearen dynamischen Optimierung und modellprädiktiven Regelung, der eine echtzeitfähige Umsetzung selbst auf leistungsschwacher Hardware ermöglicht. Neben der methodischen und algorithmischen Vorstellung wird das Verfahren anhand von ausgewählten mechatronischen Beispielen erläutert.

Prof. Thomas Meurer

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Kolloquiumsvortrag, Prof. Armin Iske, Universität Hamburg / am 12.05.2017

12.05.2017 von 14:15 bis 15:45

Institut für Informatik, Ludewig-Meyn-Straße 2, 24118 Kiel, Raum: Übungsraum 2/K

Titel: Error Estimates and Convergence Rates for Filtered Back Projection.

Abstract: We consider the approximation of target functions from fractional Sobolev spaces by the method of filtered back projection (FBP), which gives an inversion of the Radon transform. To this end, we analyze the intrinsic FBP approximation error which is incurred by the use of a low-pass filter with finite bandwidth, before we prove $L^2$-error estimates on Sobolev spaces of fractional order. The obtained error bounds are affine-linear with respect to the distance between the filter's window function and the constant function $1$ in the $L^\infty$-norm. With assuming more regularity for the window function, we refine the error estimates to prove convergence for the FBP approximation in the $L^2$-norm as the filter's bandwidth goes to infinity. We finally give asymptotic convergence rates in terms of the bandwidth of the low-pass filter and the smoothness of the target function.

Prof. Börm

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Kolloquiumsvortrag, Prof. Armin Iske, Universität Hamburg / am 12.05.2017

12.05.2017 von 14:15 bis 15:45

Institut für Informatik, Ludewig-Meyn-Straße 2, 24118 Kiel, Raum: Übungsraum 2/K

Titel: Error Estimates and Convergence Rates for Filtered Back Projection.

Abstract: We consider the approximation of target functions from fractional Sobolev spaces by the method of filtered back projection (FBP), which gives an inversion of the Radon transform. To this end, we analyze the intrinsic FBP approximation error which is incurred by the use of a low-pass filter with finite bandwidth, before we prove $L^2$-error estimates on Sobolev spaces of fractional order. The obtained error bounds are affine-linear with respect to the distance between the filter's window function and the constant function $1$ in the $L^\infty$-norm. With assuming more regularity for the window function, we refine the error estimates to prove convergence for the FBP approximation in the $L^2$-norm as the filter's bandwidth goes to infinity. We finally give asymptotic convergence rates in terms of the bandwidth of the low-pass filter and the smoothness of the target function.

Prof. Börm

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Sonderkolloquium, Prof. Dr. Mayr, Universität Klagenfurt / 10.05.2017

10.05.2017 von 17:00 bis 18:30

Hermann-Rodewald-Str. 3, 408a, 24118 Kiel

Titel: Konzeptuelle Modellierung – eine Disziplin mit Potenzial

Abstract: Die Welt ist voll von Menschen, die konzeptuell modellieren, sich dessen aber nicht bewusst sind und daher pragmatisch agieren. Dies ist nicht weiter schlimm. Es sei denn, es handelt sich um ExpertInnen der Informatik und angrenzender Gebiete, die es besser wissen sollen. Denn viele und vor allem sehr teure Probleme im Umfeld der Erstellung und des Betriebs von Softwaresystemen – zu denen ich natürlich auch datenintensive Informationssysteme zähle – entstehen durch unzureichende oder unsachgemäße Modellierung: selbst wenn man glaubt, hierauf großes Augenmerk zu legen bzw. gelegt zu haben.

Die Schuld hieran liegt nur zu einem kleineren Teil an den in der Praxis Handelnden selbst. Denn als Konsumenten von Lehrbüchern, Kursen usw. können sie es kaum besser wissen. Verantwortlich sind  vor allem diejenigen, die im Bereich der Modellierungsforschung arbeiten und lehren, mich eingeschlossen. Denn es ist uns offenbar nicht gelungen, (konzeptuelle) Modellierungsmethoden so zu gestalten und zu vermitteln, dass an ihrer systematischen und erfolgsbringenden Verwendung kein Weg vorbeiführt. Also muss man die Ursachen analysieren und daraus Konsequenzen für die Zukunft ziehen. Hierzu soll dieser Vortrag beitragen.

Zunächst werde ich versuchen, einen Eindruck davon zu vermitteln, was falsch läuft: vom Fehlen einer scharfen Definition des Begriffes „Konzeptuelle Modellierung“ selbst, über die anschwellende Ontologieflut, die offenbar den Mangel an Standards und Konstruktionsregeln ausgleichen soll, bis zum damit verbundenen Begriffs- und Methodenchaos.

Hiervon ausgehend werde ich aufzeigen, wohin, und mit welchen meist einfachen Mitteln, die Reise gehen könnte, ohne dass wieder (vermeintlich) Neues zu erfinden, zu predigen und zu verkraften wäre: über vieles wurde nämlich bereits nachgedacht und geschrieben, teils unbeachtet, teils wieder vergessen.

Heinrich C. Mayr ist emeritierter Ordentlicher Universitätsprofessor an der Alpen-Adria-Universität Klagenfurt (AAU), an der er seit 1990 tätig ist und die Forschungsgruppe Application Engineering leitet. Zuvor war er Assistent und Hochschulassistent an der Universität Karlsruhe (heute KIT), Gastprofessor an verschiedenen Universitäten im In- und Ausland und geschäftsführender Gesellschafter eines Softwareunternehmens. Seine Forschungsergebnisse sind in über 200 meist begutachteten (peer review) Veröffentlichungen dokumentiert. Sie betreffen im Wesentlichen Entwurfs- und Entwicklungsmethoden für Informationssysteme, die Modellierung im Kontext von Anforderungsanalyse, Systementwurf und Wissensmanagement, sowie die Entwicklung domänenspezifischer Modellierungssprachen. Unter anderem war er Sprecher des Fachbereichs Softwaretechnik und Informationssysteme, Vizepräsident und Präsident der Gesellschaft für Informatik (GI), Aufsichtsratsvorsitzender der Stadtwerke Klagenfurt AG, Aufsichtsratsmitglied der FH Kärnten, Hochschulrat der Pädagogischen Hochschule Kärnten, acht Jahre Dekan der seinerzeitigen Fakultät für Wirtschaftswissenschaften und Informatik und sechs Jahre Rektor der AAU. Derzeit ist er Hauptherausgeber der Lecture Notes in Informatics (LNI), Chairman des ER Steering Committee, Vorsitzender des Beirats des Software Internet Cluster SIC und Mitglied des Fachausschusses “Wirtschaftsinformatik” der  ASIIN.

Prof. Thalheim

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Sonderkolloquium, Prof. Dr. Mayr, Universität Klagenfurt / 10.05.2017

10.05.2017 von 17:00 bis 18:30

Hermann-Rodewald-Str. 3, 408a

Titel: Konzeptuelle Modellierung – eine Disziplin mit Potenzial

Abstract: Die Welt ist voll von Menschen, die konzeptuell modellieren, sich dessen aber nicht bewusst sind und daher pragmatisch agieren. Dies ist nicht weiter schlimm. Es sei denn, es handelt sich um ExpertInnen der Informatik und angrenzender Gebiete, die es besser wissen sollen. Denn viele und vor allem sehr teure Probleme im Umfeld der Erstellung und des Betriebs von Softwaresystemen – zu denen ich natürlich auch datenintensive Informationssysteme zähle – entstehen durch unzureichende oder unsachgemäße Modellierung: selbst wenn man glaubt, hierauf großes Augenmerk zu legen bzw. gelegt zu haben.

Die Schuld hieran liegt nur zu einem kleineren Teil an den in der Praxis Handelnden selbst. Denn als Konsumenten von Lehrbüchern, Kursen usw. können sie es kaum besser wissen. Verantwortlich sind  vor allem diejenigen, die im Bereich der Modellierungsforschung arbeiten und lehren, mich eingeschlossen. Denn es ist uns offenbar nicht gelungen, (konzeptuelle) Modellierungsmethoden so zu gestalten und zu vermitteln, dass an ihrer systematischen und erfolgsbringenden Verwendung kein Weg vorbeiführt. Also muss man die Ursachen analysieren und daraus Konsequenzen für die Zukunft ziehen. Hierzu soll dieser Vortrag beitragen.

Zunächst werde ich versuchen, einen Eindruck davon zu vermitteln, was falsch läuft: vom Fehlen einer scharfen Definition des Begriffes „Konzeptuelle Modellierung“ selbst, über die anschwellende Ontologieflut, die offenbar den Mangel an Standards und Konstruktionsregeln ausgleichen soll, bis zum damit verbundenen Begriffs- und Methodenchaos.

Hiervon ausgehend werde ich aufzeigen, wohin, und mit welchen meist einfachen Mitteln, die Reise gehen könnte, ohne dass wieder (vermeintlich) Neues zu erfinden, zu predigen und zu verkraften wäre: über vieles wurde nämlich bereits nachgedacht und geschrieben, teils unbeachtet, teils wieder vergessen.

Heinrich C. Mayr ist emeritierter Ordentlicher Universitätsprofessor an der Alpen-Adria-Universität Klagenfurt (AAU), an der er seit 1990 tätig ist und die Forschungsgruppe Application Engineering leitet. Zuvor war er Assistent und Hochschulassistent an der Universität Karlsruhe (heute KIT), Gastprofessor an verschiedenen Universitäten im In- und Ausland und geschäftsführender Gesellschafter eines Softwareunternehmens. Seine Forschungsergebnisse sind in über 200 meist begutachteten (peer review) Veröffentlichungen dokumentiert. Sie betreffen im Wesentlichen Entwurfs- und Entwicklungsmethoden für Informationssysteme, die Modellierung im Kontext von Anforderungsanalyse, Systementwurf und Wissensmanagement, sowie die Entwicklung domänenspezifischer Modellierungssprachen. Unter anderem war er Sprecher des Fachbereichs Softwaretechnik und Informationssysteme, Vizepräsident und Präsident der Gesellschaft für Informatik (GI), Aufsichtsratsvorsitzender der Stadtwerke Klagenfurt AG, Aufsichtsratsmitglied der FH Kärnten, Hochschulrat der Pädagogischen Hochschule Kärnten, acht Jahre Dekan der seinerzeitigen Fakultät für Wirtschaftswissenschaften und Informatik und sechs Jahre Rektor der AAU. Derzeit ist er Hauptherausgeber der Lecture Notes in Informatics (LNI), Chairman des ER Steering Committee, Vorsitzender des Beirats des Software Internet Cluster SIC und Mitglied des Fachausschusses “Wirtschaftsinformatik” der  ASIIN.

Prof. Thalheim

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Kolloquiumsvortrag, Prof. Jacquelien Scherpen von der Universität Groningen (NL) / am 08.05.2017

08.05.2017 von 17:15 bis 18:45

Institute Ostufer, Geb. D, "Aquarium", Kaiserstr. 2, 24143 Kiel

Titel: Passivity based control techniques for (micro-)grid control

Abstract: In this presentation I will discuss some physical modeling consideration for grid models, and the various devices in the grid, such as synchronous generators and inverter models for the embedding of renewables. Furthermore, the (passivity based) control possibilities and difficulties of networks with such generating devices will be discussed, as well as control considerations for inverters. Finally, a more simple OPF control model for microgrids is considered in the analysis.

Prof. Thomas Meurer/Prof. Marco Liserre

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Kolloquiumsvortrag, Prof. Jacquelien Scherpen von der Universität Groningen (NL) / am 08.05.2017

08.05.2017 von 17:15 bis 18:45

Institute Ostufer, Geb. D, "Aquarium", Kaiserstr. 2, 24143 Kiel

Titel: Passivity based control techniques for (micro-)grid control

Abstract: In this presentation I will discuss some physical modeling consideration for grid models, and the various devices in the grid, such as synchronous generators and inverter models for the embedding of renewables. Furthermore, the (passivity based) control possibilities and difficulties of networks with such generating devices will be discussed, as well as control considerations for inverters. Finally, a more simple OPF control model for microgrids is considered in the analysis.

Prof. Thomas Meurer/Prof. Marco Liserre

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Sonderkolloquium, Prof. Thomas Plagemann / Prof. Vera Goebel, Universität Oslo / am 04.05.2017

04.05.2017 von 16:30 bis 18:00

ZBW, Düsternbrooker Weg 120, 24105 Kiel, Raum B024

Titel: A Platform for fine-granular migration of multimedia applications

Abstract: As a step towards mobile and ubiquitous computing, the TRAMP Real-time Application Mobility Platform (TRAMP) enables secure and user-friendly migration of multimedia application components. The motivating factors are device and user mobiliy, i.e., to let the user determine where application components should execute at all times. In order to organize and locate roaming devices, a decentralized peer-to-peer overlay is developed. To provide location transparency for application developers and enable efficient data sharing among application components, an API is provided that hides whether shared memory or latency optimized network distribution is used to share data. The problem of open TCP connections to third-party applications is solved with a proxy-based approach. Multimedia applications are especially sensitive to service interruptions that can be caused by migration, and a new approach for check-pointing, state transfer and resuming an application with minimal freeze time is therefore introduced. The evaluation of TRAMP shows that this optimization for low freeze time has significant effect. For example, migrating the Skype video-conferencing application with TRAMP reduces the average freeze time from 41.1 seconds with legacy approaches to 213 milliseconds. Further results from the empirical evaluation of TRAMP demonstrate that it has no negative impact on the Quality of Experience.

Prof. Scherp

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Sonderkolloquium, Prof. Thomas Plagemann / Prof. Vera Goebel, Universität Oslo / am 04.05.2017

04.05.2017 von 16:30 bis 18:00

ZBW, Düsternbrooker Weg 120, 24105 Kiel, Raum B024

Titel: A Platform for fine-granular migration of multimedia applications

Abstract: As a step towards mobile and ubiquitous computing, the TRAMP Real-time Application Mobility Platform (TRAMP) enables secure and user-friendly migration of multimedia application components. The motivating factors are device and user mobiliy, i.e., to let the user determine where application components should execute at all times. In order to organize and locate roaming devices, a decentralized peer-to-peer overlay is developed. To provide location transparency for application developers and enable efficient data sharing among application components, an API is provided that hides whether shared memory or latency optimized network distribution is used to share data. The problem of open TCP connections to third-party applications is solved with a proxy-based approach. Multimedia applications are especially sensitive to service interruptions that can be caused by migration, and a new approach for check-pointing, state transfer and resuming an application with minimal freeze time is therefore introduced. The evaluation of TRAMP shows that this optimization for low freeze time has significant effect. For example, migrating the Skype video-conferencing application with TRAMP reduces the average freeze time from 41.1 seconds with legacy approaches to 213 milliseconds. Further results from the empirical evaluation of TRAMP demonstrate that it has no negative impact on the Quality of Experience.

Prof. Scherp

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Kolloquiumsvortrag, Prof. Massimo Guarnieri, University Padua (Italien) / am 24.04.2017

24.04.2017 von 17:15 bis 18:45

Institute Ostufer, Geb. D, "Aquarium", Kaiserstr. 2, 24143 Kiel

Titel: Vanadium Redox Flow Batteries: Potentials and Challenges of an Emerging Storage Technology.

Abstract:  Energy storage is expected to expand its importance the next future, in order to provide increasing services, both mobile and stationary. Depending on their kind, rated powers vary from a few kilowatts (excluding portable electronics) to some gigawatts, with operating times ranging from fractions of a second to several hours and response times from milliseconds to some minutes. Electrochemical storage technologies are by far the most versatile form of energy storage to face this vast rising demand, and a huge market is soaring. Recent techno-financial analyses have forecasted investments exceeding US$10 billion/year on energy storage technologies by 2020.

The most enticing forms of electrochemical storage should allow to separated power and energy rating, in order to tailor discharge duration at will and the most promising solution for doing so at a reasonably high round-trip efficiency and at a high cycle life are flow batteries. For this reason, several major laboratories around the world are intensively researching them.

My talk will present the main feature of the most developed chemistry of flow battery, namely Vanadium Redox Flow Battery. An overview will be delivered on how they work, what are their architectures, needed ancillary technology, including power electronic interfaces, and possible applications, from small domestic end-user to smart-grid substations. The strengths, weaknesses and challenges of vanadium redox flow batteries will be highlights. A particular reference will be given to the research programs on VRFBs on-going at University of Padua, both experimental and numerical, aiming at taking them to full commercial success.

CV

Massimo Guarnieri joined the CNR (Italian National Council of Researches) in 1882 and the University of Padua in 1983, where he is full professor of electrical engineering since 2000. He is a ICS (International Compumag Society) Member since 2008, an IEEE Member since 2012 and a ECS (Electrochemical Society) Member since 2014. Initially he centered his work on the analysis and design of large electromagnetic devices for the thermonuclear fusion research experiments Eta-Beta II and RFX, both built at Padua. For the latter he worked in and eventually led the Magntic System Group, responsible for the device’s major inductor systems (diameter up to 8 m, 50 kA, 200 kV). He later centered his interests in the area of numerical computation for electromagnetic and coupled problems. Since 13 years he is involved in the analysis, optimization and design of fuel cells, redox flow batteries and electrochemical storage devices, including modelling, experimental investigation, and parameters/performance identification. He is also widely interested in history of technology and science. His scientific production of over 200 items includes papers on journals and conference proceedings (over 110 indexed in Scopus) and several textbooks. He chairs the Education & Profession Group of the AEIT-ASTRI Italian Electrical Engineers Institution. He is the official representative of the University of Padua in N.ERGHY, the European Union association representing the universities and research institution in the Fuel Cell and Hydrogen Joint Technology Initiative (FCH JTI). He is a columnist and editorial board member of the IEEE Industrial Electronics Magazine.

Prof. Liserre

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Kolloquiumsvortrag, M. Sc. Alexander Mäcker, Universität Paderborn / am 21.04.2017

21.04.2017 von 14:15 bis 15:45

Institut für Informatik, Ludewig-Meyn-Straße 2, 24118 Kiel, Raum: Übungsraum 2/K

Titel: Non-Clairvoyant Scheduling to Minimize Max Flow Time on a Machine with Setup Times

Abstract:

Consider a problem in which $n$ jobs that are classified into $k$ types arrive over time at their release times and are to be scheduled on a single machine so as to minimize the maximum flow time. The machine requires a setup taking $s$ time units whenever it switches from processing jobs of one type to jobs of a different type. We consider the problem as an online problem where each job is only known to the scheduler as soon as it arrives and where the processing time of a job only becomes known upon its completion (non-clairvoyance). We analyze a simple modification of the FIFO strategy and show the competitiveness to be $\Theta(\sqrt{n})$, which is optimal for ``greedy-like'' algorithms. We will then also consider a smoothed analysis of the competitiveness. The smoothed competitiveness turns out to only be $O(\varepsilon^{-2} \log^2 n)$ when processing times $p_j$ are independently perturbed by adding a random value uniformly drawn from $[-\varepsilon p_j, \varepsilon p_j]$, $0 < \varepsilon < 1$. The talk is based on joint work with Manuel Malatyali and Sören Riechers.

Prof. Jansen

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Kolloquiumsvortrag, Dipl.-Ing. Ingo Schalk-Schupp, Forschungslabor Nuance Communication / am 10.04.2017

10.04.2017 von 17:15 bis 18:45

Institute Ostufer, Geb. D, "Aquarium", Kaiserstr. 2, 24143 Kiel

Titel: Nonlinear Echo Suppression

Abstract: This presentation provides a short overview concerning acoustic echo cancellation and acoustic echo suppression methods followed by a more in-depth discussion of new methods dealing with Hammerstein-type nonlinear distortions.

The Hammerstein system is divided into a linear and a parallel nonlinear part by an alternative way to define of the linear one. The implications of this separation definition and its relation to linear acoustic echo cancellation are illuminated.

Based on this approach, and assuming a converged linear echo canceller, a suppression approach for nonlinearly distorted acoustic echo signal components is introduced, the essential component of which is the nonlinear echo power spectral density estimation, which depends on one unknown real scalar parameter.

Subsequently, an identification algorithm for said parameter is presented, which results in a usable nonlinear echo suppressor still under the assumption of a converged linear echo canceller. Moreover, a generic comprehensive evaluation method for suppressor-type algorithms is advertised.

Finally, the challenge of concurrently adaptive linear echo canceller and nonlinear echo suppressor is analyzed and a solution for a full system is presented. After listening to several audio examples, the audience is invited to discuss the presentation’s contents.

Short biography

Ingo Schalk-Schupp studied systems engineering and technical cybernetics at Otto von Guericke University in Magdeburg, Germany. He graduated as a diploma engineer (Diplomingenieur) in 2012 with a diploma thesis titled “Speech Signal Enhancement in Automotive Environments” composed at Nuance Communications in Ulm, Germany. The thesis comprised two patent applications and was granted the best thesis award by the “Magdeburger Kybernetiker e.V.” Since 2012, he has been a PhD student with Nuance in Ulm and is supervised by Professor Andreas Wendemuth, Chair of Cognitive Systems at Otto von Guericke University Magdeburg. This presentation reflects the author’s findings from his PhD research.

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Sonderkolloquium, Dr. Chidambaram Amalai, ETH Zürich / am 10.04.2017

10.04.2017 von 15:00 bis 16:30

Ludewig-Meyn-Str. 2. Raum Ü2/K (LMS2, R. Ü2/K)

Titel: Algorithmic Advances in Allocation and Scheduling

Abstract: We study the restricted case of Scheduling on Unrelated Parallel
Machines. In this problem, we are given a set of jobs J with processing
times p_j and each job may be scheduled only on some subset of machines
S_j. The goal is to find an assignment of jobs to machines to minimize
the time by which all jobs can be processed. In a seminal paper,
Lenstra, Shmoys, and Tardos designed an elegant 2-approximation for the
problem in 1987. The question of whether approximation algorithms with
better guarantees exist for this classic scheduling problem has since
remained a source of mystery.

In recent years, with the improvement of our understanding of
Configuration LPs, it now appears an attainable goal to design such an
algorithm. Our main contribution is to make progress towards this goal.
When the processing times of jobs are either 1 or epsilon < 1, we design
an approximation algorithm whose guarantee tends to 1+sqrt(3)/2 =
1.8660254, for the interesting cases when epsilon approaches 0. This
improves on the 2 - epsilon_0 guarantee recently obtained by
Chakrabarty, Khanna, and Li for some constant epsilon_0 > 0.

 

Prof. Jansen

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Technische Fakultät organisiert erneut Siegerehrung des Landeswettbewerbs „Jugend forscht – Schüler experimentieren“

Sonderkolloquium, Frau Dr. Azra Bahadori, Niels-Bohr-Insitut, Universität Kopenhagen / am 27.03.2017

Sonderkolloquium, Prof. Gerold Jäger, Universität Umeâ, Schweden / am 09.03.2017

09.03.2017 von 11:00 bis 12:30

Institut für Informatik, Christian-Albrechts-Platz 4, Raum 910 (CAP 4)

Titel: Optimale Strategien für die Black-Peg-Variante des Statischen Masterminds und des Statischen AB-Games

Abstract: Mastermind ist ein Logikspiel für zwei Personen, das im Jahre 1970 erfunden wurde und sich seit zu einem populären Gesellschaftsspiel entwickelt hat, das über 50 Millionen Mal verkauft wurde. Die beiden am Spiel beteiligten Spieler werden als Codemaker und Codebreaker bezeichnet. Der Codemaker legt zu Beginn des Spiels einen vierstelligen Farb-Code fest, der aus sechs Farben ausgewählt wird. Der Codebreaker versucht, diesen Code zu erraten, indem er einen gleichartigen Farb-Code als Frage verwendet und vom Codemaker eine Antwort erhält, wie nahe seine Frage am zu erratenden Farb-Code ist. Für jeden Stift, der sowohl in Farbe als auch in Position richtig ist, gibt der Codemaker einen schwarzen Stift in der Antwort und für jeden Stift, der nur in der Farbe richtig ist, einen weißen Stift. Mit Hilfe dieser Antwort kann er weitere Fragen stellen, die auf dasselbe Weise beantwortet werden, und dies geschieht solange, bis der Codebreaker den Farb-Code erraten hat. Eine natürliche Erweiterung ist es, statt einenm vierstelligen Farb-Code einen p-stelligen mit beliebigem p zu erlauben und statt 6 Farben c Farben mit beliebigem c zu erlauben. Insbesondere in den letzten 10 Jahren hat sich Mastermind zu einem vielbeachteten Forschungsthema entwickelt. Im Jahre 2006 wurde gezeigt, dass Mastermind NP vollständig ist. Des Weiteren wurden Anwendungen von Mastermind in der Komplexitätstheorie, Bioinformatik und Kryptographie untersucht und es wurden Schranken und optimale Strategien für viele Mastermind-Varianten bewiesen, oft indem entweder konstantes p oder konstantes c betrachtet wurden. In diesem Vortrag betrachten wir eine Kombination von drei Mastermind-Varianten: 1. Das AB-Game, das sich von Mastermind unterscheidet, indem sowohl in dem Farb-Code als auch bei den Fragen die Stifte alle verschiedene Farben haben müssen. 2. Die Black-Peg-Variante, in der der Codemaker nur schwarze Stifte als Antwort gibt. 3. Statisches Mastermind, in dem der Codebreaker eine bestimmte Anzahl von Fragen gleich zu Beginn des Spieles gibt, dann alle Antworten erhält und schließlich nur noch einen weiteren Versuch hat, den richtigen Farb-Code zu erraten.
Goddard hat im Jahre 2003 optimale Strategien für das originale Statische Mastermind vorgestellt, und zwar für den Fall von p=2, p=3, p=4 Stiften. In diesem Vortrag wird eine Strategie für die Black-Peg Variante des Statischen Mastermind mit p=2 Stiften vorgestellt und deren Zulässigkeit und Optimalität bewiesen. Des Weiteren werden Strategien für p=3, c=2, c=3 vorgestellt, deren Optimalitätsbeweis ein offenes Problem darstellt. Schließlich 9 weitere Paare (p,c) presentiert, deren Zulässigkeit und Optimalität mit Hilfe eines Computerprogramms gezeigt werden konnte. Am Ende des Vortrags wird über Work-in-Progress berichtet, und zwar über zulässige und optimale Strategien für die Black-Peg-Version des AB-Games. Insbesondere geht es um die Fälle von p=2 Stiften und p=c Stiften. Der letzte Fall ist besonders interessant, aber auch anspruchsvoll, da der Farb-Code und die Fragen Permutationen entsprechen.

Prof. Srivastav

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Kolloquiumsvortrag, Prof. Knut Graichen, Institut für Mess-, Regel- und Mikrotechnik, Universität Ulm / am 06.02.2017

06.02.2017 um 17:15 bis 06.03.2017 um 18:45

Technische Fakultät, Institut für Elektrotechnik und Informationstechnik, Kaiserstr. 2, Kiel, Raum: "Aquarium", Geb. D

Titel: Eingebettete nichtlineare Optimierung und MPC im (Sub-)Millisekundenbereich

Abstract: Nichtlineare Optimierungsverfahren und deren Anwendung im Zusammenhang mit der nichtlinearen modellprädiktiven Regelung (NMPC) sind in der Regelungstechnik insbesondere für dynamische Systeme mit mehreren Stellgrößen und zur Berücksichtigung von Systembeschränkungen von zunehmender Bedeutung. Eine Herausforderung bei der Umsetzung dieser Verfahren in der Praxis ist jedoch der hohe numerische Aufwand und die algorithmische Komplexität, insbesondere bei hochdynamischen Systemen mit Abtastzeiten im (Sub-)Millisekundenbereich. Die Problematik der Umsetzbarkeit wird durch die Tatsache weiter verschärft, dass Hardware-Lösungen in der industriellen Praxis häufig sehr limitierte Ressourcen besitzen. Als Beispiele seien Speicherprogrammierbare Steuerungen (SPS) oder Steuergeräte (Electronic Control Unit – ECU) genannt. Diesen Herausforderungen kann im Sinne eines eingebetteten Entwurfs durch die Verwendung von zugeschnittenen Optimierungsalgorithmen in Kombination mit einer echtzeitfähigen Auswertung begegnet werden.

Im Hinblick auf die oben genannten Herausforderungen präsentiert der Vortrag einen Ansatz zur nichtlinearen dynamischen Optimierung und modellprädiktiven Regelung, der eine echtzeitfähige Umsetzung selbst auf leistungsschwacher Hardware ermöglicht. Neben der methodischen und algorithmischen Vorstellung wird das Verfahren anhand von ausgewählten mechatronischen Beispielen erläutert.

Prof. Dr.-Ing. Thomas Meurer

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Sonderkolloquium Prof. Concari, University of Parma / am 21.02.2017

21.02.2017 von 15:00 bis 16:30

Technische Fakultät, Kaiserstr. 2, Kiel, Raum: "Aquarium", Geb. D

Titel: Fault Diagnosis of Electrical Machines

Abstract: The fault diagnosis of electrical machines has been the subject of intensive research for several decades. Being able to detect or predict incipient faults before they impair the ability of the machines to function properly is a very welcome feature in industrial environments, where unscheduled downtime can cause production and financial loss.

Electrical machine faults include electrical stator faults, electrical rotor faults, eccentricity, bearing faults. Diagnostic techniques for the detection of such faults in electrical machines are reviewed, and their effectivity is assessed in different operating conditions, including closed-loop inverter-fed operation. Furthermore, the impact of wide-bandgap devices is discussed and prognostic techniques are reviewed, with particular focus on aerospace applications.

Prof. Liserre

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Kolloquiumsvortrag, Prof. Dr. Robert Huber, Inst. für Biomedizinische Optik, Uni Lübeck / am 16.01.2017

16.01.2017 von 17:15 bis 18:45 – Technische Fakultät, Insitut für ET/IT, Kaiserstr. 2, Kiel, Raum: "Aquarium", Geb. D

Kolloquiumsvortrag, Dr. Seraphine Wegner, MPI Polymer-Forschung Mainz / am 09.01.2017

Sonderkolloquium Greg P. Carman (IEEE Magnetics Distinguished Lecturer) / am 08.12.2016

Sonderkolloquium Prof. J.I. Leon / 07.12.2016

07.12.2016 von 10:00 bis 11:30

Technische Fakultät, Institut für Elektrotechnik und Informationstechnik, Kaiserstr. 2, Kiel, Raum: Geb. D, "Aquarium"

Titel: The Essential Role and the Continuous Evolution of Modulation Techniques for Voltage-Source Inverters in the Past, Present, and Future Power Electronics

Abstract: The cost reduction of power electronic devices, the increase in their reliability, efficiency and power capability, lower development times, together with more demanding application requirements, have driven the development of several new inverter topologies recently introduced in industry, particularly medium-voltage converters. New more complex inverter topologies and new application fields come along with additional control challenges, such as: voltage imbalances, power quality issues, higher efficiency needs and fault tolerant operation, which necessarily requires the parallel development of modulation schemes.
Therefore, recently there have been significant advances in the field of modulation of dc/ac converters, which conceptually has been dominated during the last several decades almost exclusively by classic pulse width modulation methods. This talk aims to concentrate and discuss the latest developments on this exciting technology, to provide insight on where the state-of-the-art stands today, and analyze the trends and challenges driving its future.

Prof. Marco Liserre

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Sonderkolloquium Dr. Akihiko Sugiyama / 06.12.2016

06.12.2016 von 17:15 bis 18:45 – Technische Fakultät, Institut für Elektrotechnik und Informationstechnik, Kaiserstr. 2, Kiel, Raum: Geb. D, "Aquarium"

Sonderkolloquium Prof. Joachim Holtz, Technical University Braunschweig / 25.11.2016

25.11.2016 von 12:00 bis 13:00

Technische Fakultät, Institut für Elektrotechnik und Informationstechnik, Kaiserstr. 2, Kiel, Raum: Geb. B Raum 101

Titel: Predictive Current Control

Abstract: Predictive Current Control – When to use?

Switching losses contribute the major portion to the total losses in medium voltage drives. Operation at extremely low switching frequency is therefore mandatory. Low harmonic current distortion can be nevertheless maintained when predictive current control is used.

Predictive current control is currently attracting the interest of many researchers. Even specific conferences are being organized on this novel topic. The predictive algorithm directly generates the firing pulses of the inverter, thus eliminating a pulsewidth modulator. A preset magnitude of the current error is permitted, defined as the magnitude difference between reference and actual current space vectors. Inverter gate pulses are generated such as to maximize the time differences between any two switching instants. This minimizes the switching frequency, and thus the switching losses. Harmonic current distortion is held at a predetemined value.

A gate pulse is generated whenever a predefined current error is exceeded. That error is computed as the difference between reference and actual current space vector. The next switching state is then determined such that maximum time elapses until the error vector exceeds its limit again. This minimizes the switching frequency and also the switching losses. Overmodulation and a smooth transition to full-wave operation produces maximum inverter output voltage. The error vector is represented here in a rotor field oriented coordinate system and different error magnitudes are permitted in the respective axes. 

About the Speaker

Joachim Holtz graduated in 1967 and received the Ph.D. degree in 1969 from the Technical University Braunschweig, Germany.

In 1969 he became Associate Professor and, and in 1971 Full Professor and Head of the Control Engineering Laboratory, Indian Institute of Technology in Madras, India. He joined the Siemens Research Laboratories in Erlangen, Germany in 1972. From 1976 to 1998, he was Professor and Head of the Electrical Machines and Drives Laboratory, Wuppertal University, Germany. He is presently Professor Emeritus and a Consultant.

His publications include 2 invited papers in the PROCEEDINGS OF THE IEEE, 17 invited papers in IEEE Journals, and 27 single-authored IEEE Journal papers. He is the recipient of 17 Prize Paper Awards, a coauthor of seven books and holds 33 patents.

Dr. Holtz is the recipient of the IEEE Industrial Electronics Society Dr. Eugene Mittelmann Achievement Award, the IEEE Industrial Applications Society Outstanding Achievement Award, the IEEE Power Electronics Society William E. Newell Field Award, the IEEE Third Millennium Medal, the Anthony J. Hornfeck Service Award, and the IEEE Lamme Gold Medal. He is a Life Fellow of the IEEE.

Dr. Holtz is Past Editor-in-Chief of the IEEE Transactions on Industrial Electronics, Distinguished Lecturer of the IEEE Industrial Applications Society and IEEE Industrial Electronics Society.

Prof. Marco Liserre

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Erasmus+ Info Veranstaltung für Studierende an der TF

Grippeschutzimpfung auf dem Ostufer

Doppelkolloquium, Prof. C. V. Lakshmi, Computer Science Dayalbagh Educational Institut, Agra, India / am 05.10.2016, 15:15 Uhr - 16:00 Uhr

05.10.2016 um 15:15 bis 17.10.2016 um 16:00

Institut für Informatik, Vorbau Ludewig-Meyn-Straße 2, 24118 Kiel, Raum Ü2/K

Titel: A fast and robust many fonts printed Optical Character Recognition system for Indian Scripts

Abstract: Making machines “read” text printed or handwritten on paper has been a long cherished goal in Computer Science. Considerable success has been achieved for scripts like Roman script that is quite simple and consists of very few symbols.
This talk describes the design and development of an Optical Character Recognition system for printed many-font Indian scripts. The system takes an image of printed text in Devanagari (Hindi, dominant language in North India) or Telugu (a prominent South Indian Language) as an input. It performs a full OCR and provides output that can be directly taken into an editor. Indian scripts are classified into two classes – one class consists of scripts that are written with a prominent headline called Shirorekha and the other class consists of those scripts which do not have a shirorekha. In our work, Devanagari is taken as a representative of the first class and Telugu as a representative of the second class as specified above.
Indian scripts are extremely complicated due to the presence of a vast number of possible combinations of vowels and consonants which are written joined together to form what are called compound characters. The OCR problem becomes even more difficult when text is present in complicated layouts or on complicated backgrounds.
The OCR system designed and implemented is shown to provide excellent results for text images of Telugu and Devanagari. A large number of fonts are considered – 24 for Telugu and 25 for Devanagari and the results are excellent for all these fonts. This is the first reported attempt that works for such a large number of fonts for Indian scripts. Further the recognition rates are enhanced by judiciously implementing schemes for reducing the number of exemplars and the number of features to be stored in the databases. New types of features in transform domain are shown to give better results. The fact that the system works excellently for all these fonts on both Shirorekha-based script as well as non-Shirorekha based Indian script augurs well for the other Indian scripts.
The talk would highlight the main characteristics of Indian scripts and the challenges in development of OCR for them. It would then describe how these challenges are resolved in our work. Considerable emphasis would be laid on practical demonstration of the OCR system apart from explaining its internal structure and logic.

Prof. Anand Srivastav

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Doppelkolloquium, Prof. C Patvardhan, Dayalbagh Educational Institut Agra, India / am 05.10.2016, 14:15 Uhr - 15:00 Uhr

05.10.2016 von 14:15 bis 15:00

Institut für Informatik, Vorbau Ludewig-Meyn-Straße 2, 24118 Kiel, Raum Ü2/K

Titel: Engineering Quantum-inspired Evolutionary Algorithms for solution of large Combinatorial Optimization problems

Abstract: Quantum-inspired Evolutionary Algorithms (QIEA) is a recent branch of EAs. QIEA is a population-based probabilistic Evolutionary Algorithm that integrates concepts from quantum computing for higher representation power and robust search. It maintains a population of individuals in quantum bits or qubits. A qubit coded individual can probabilistically represent a linear superposition of states in the search space and has a better characteristic of population diversity than other representations.
Thus, QEAs are characterized by population dynamics, individual representation, evaluation function etc., as in EAs, as well as quantum bit (qubit) representation, superposition of states etc. as in Quantum Computing. The advantage of the QEAs is that, unlike the other EAs, they can work with small population sizes without being stuck in local minima and without converging prematurely because of loss of diversity. In the extreme case, the immense representation power of the qubits enables use of population size of 1. This reduces the computational burden. Integration of several algorithmic ideas judiciously enables the solution of very large sized problems.
The talk would introduce the QEAs and present some of our recent work on QIEAs and applications. Pointers towards efficient implementations would be discussed. We would also present some directions of future research.

Prof. Anand Srivastav

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Sonderkolloquium, Dr. Alex Q. Huang, North Carolina State University / 09.09.2016

09.09.2016 von 09:30 bis 11:00

Institut für Elektrotechnik, Kaiserstraße 2, 24143 Kiel, Geb. D, "Aquarium"

Titel: 15 kV SiC MOSFET Based Medium Voltage DC/DC Converter

 

Abstract: Medium voltage DC-DC converter is an important element of a medium voltage solid state transformer (SST). It is also considered the most critical element in the future medium voltage DC grid. In reaching medium voltage operation range, device series connection and converter series connection are all viable solutions. This talk will discuss the unique capability of SiC MOSFET in achieving extremely simple and high power density design by operating at very high switching frequency. This is achieved by taking advantage of the zero switching loss in ZVS-based converters and design optimization. Control strategies to improve the reliability of the DC/DC converter is also discussed. In conclusion, 15 kV SiC MOSFET is almost an ideal semiconductor switch that can enable medium voltage conversion at 100 kHz and at a voltage up to 12 kV.

 

Dr. Alex Q. Huang

Dr. Alex Huang received his B.Sc. degree from Zhejiang University, China in 1983 and his M.Sc. degree from Chegdu Institute of Radio Engineering, China in 1986, both in electrical engineering. He received his Ph.D. from Cambridge University, UK in 1992. From 1994 to 2004, he was a founding member and a professor of Center for Power Electronics System (an NSF ERC) at Virginia Tech. Since 2004, he has been a professor of electrical engineering at North Carolina State University and he is currently the Progress Energy Distinguished Professor of Electrical and Computer Engineering. He established the NSF FREEDM Systems ERC in 2008. As part of the FREEDM System concept, he developed the original concept of Energy Internet with the Solid State Transformer serving as an Energy Router. Today, FREEDM Systems ERC is one of the most successful ERCs in the USA with support from many companies. Dr. Huang is also the lead PI and visionary leader behind NCSU’s recent success in establishing the next generation Wide bandgap power electronics manufacturing innovation institute.

Dr. Huang’s research areas are power semiconductor devices, power management integrated circuits, power electronics and its emerging applications such as those in future electric power delivery and management systems. A very active and productive research leader, Dr. Huang has mentored and graduated more than 70 Ph.D. and master students and has generated more than $200m external R&D fundings in the last 20 years.  Dr. Huang has published more than 450 papers in journals and conference proceedings, and holds 20 US patents.  Dr. Huang is the inventor and developer of the ETO thyristor technology. Dr. Huang is a fellow of IEEE and the recipient of the prestigious 2003 R&D 100 award and 2011 MIT Technology Magazine awards. 

 

Prof. Dr. Marco Liserre

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Kolloquiumsvortrag: PD Dr. Frank Gurski - Universität Düsseldorf/ 17.07.2015

17.07.2015 von 14:15 bis 15:45

Institut für Informatik, Ludewig-Meyn-Str. 2, Übungsraum 2

Titel: Knapsack Problems: A Parameterized point of view

 

Abstract:

 

The knapsack problem is a very famous NP-hard problem in combinatorial optimization. In the 0-1 knapsack problem (0-1 KP) we are given a set A of n items. Every item j has a profit p(j) and a size s(j). Further there is a capacity c of the knapsack. The task is to choose a subset A' of A, such that the total profit of A' is maximized and the total size of A' is at most c.

Within the d-dimensional 0-1 knapsack problem (d-KP) a set A of n items and a number d of dimensions is given. Every item j has a profit p(j) and for dimension i the size s(i,j). Further for every dimension i there is a capacity c(i). The goal is to find a subset A' of A, such that the total profit of A' is maximized and for every dimension i the total size of A' is at most the capacity c(i).

Further we consider the multiple 0-1 knapsack problem (MKP) where beside n items a number m of knapsacks is given. Every item j has a profit p(j) and a size s(j) and each knapsack i has a capacity c(i). The task is to choose m disjoint subsets of A such that the total profit of the selected items is maximized and each subset can be assigned to a different knapsack i without exceeding its capacity c(i) by the sizes of the selected items.

Since d-KP and MKP are defined on inputs of various informations, we study the fixed-parameter tractability of these problems. The idea behind fixed-parameter tractability is to split the complexity into two parts - one part that depends purely on the size of the input, and one part that depends on some parameter of the problem that tends to be small in practice. We discuss the following parameters: the number of items, the threshold value for the profit, the sizes, the profits, the number d of dimensions, and the number m of knapsacks.

We also consider the connection of parameterized knapsack problems to linear programming, approximation, and pseudopolynomial algorithms.

Prof. Jansen

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Kolloquiumsvortrag: Dr. Stephan Warnat/ Dalhousie University, Halifax, Canada / 13.07.2015

13.07.2015 von 17:15 bis 18:45

Institut für Materialwissenschaft, Kaiser Str. 2, Geb.C , Raum "Aquarium"

Titel: Multi User MEMS environment to test microorganisms in aqueous media

 

Abstract:

 

90 % of international traded products are transported using marine transportation.  Transport and delivery of microorganisms through ballast water from departure to arrival location is an unwanted consequence. Some organisms are invaders or alien species and change the marine ecosystem irreversibly. These irreversible changes cause annual damage in ecosystems, farming and tourism of several million dollars.

 

            I will present our current work on a cell monitoring system using Micro-Electrochemical Systems (MEMS) in a microfluidic camera environment: 1) Devices have to work reliable in seawater. Several MEMS materials show immediate corrosion during operation in seawater. An encapsulation strategy of active structures using Al2O3, TiO2 multilayers deposited by Atomic Layer Deposition (ALD) will be presented which allowed a constant operation in seawater for 30 days; 2) A novel Gecko inspired adhesive technology is currently evaluated to form sealed fluidic chamber systems on top of the MEMS. This technology allows fluidic sealing without bonding processes; 3) The mechanical stiffness of single cells allow an assessment of cell viability. An approach was developed to measure the mechanical cell stiffness based on differential displacement measurements on a two stage spring system. Displacements were measured optically within a ±10 nm accuracy during MEMS operation in aqueous media. This technique allowed differentiation of viable and non-viable Saccharomyces cerevisiae (baker’s yeast). I will conclude the talk with our plans to integrate the developed MEMS platform into a mobile camera platform.

Prof. Wagner

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Kolloquiumsvortrag: Dr. Davide Barater, Department of Information Engineering, University of Parma, Italy/ 06.07.2015

06.07.2015 von 17:15 bis 18:45

Institut für (Ost), Kaiser Str. 2, Geb.C , Raum "Aquarium"

Titel: “Accelerated Life tests for Electric drives in Aircrafts”

 Abstract:

The concept behind the More Electric Aircraft (MEA) is the progressive electrification of on-board actuators and services. It is a way to reduce or eliminate the dependence on hydraulic, mechanical and the bleed air/pneumatic systems and pursue efficiency, reliability and maintainability. At the moment, the lifetime problems of electromechanical actuators, adopted in MEA, have been addressed by analyzing separately the causes of failures, and accelerated tests were proposed for the single components. This project aims at realizing a test bed able to apply multiple age accelerating stresses and to realize the on-line test of the electric machine and drive, under different operating conditions.

The main failure in electric drives is due to electric faults resulting from the damage in the motor winding insulation system. In this work the main stress factors affecting the lifespan of insulation materials in aerospace applications will be analyzed. A special test bed will be also proposed, to assess insulation lifespan modelling under various stress conditions, especially investigating the interaction between ageing factors. The test bed will allow to characterize insulation degradation under variable ambient and power supply parameters for simple models, such as twisted pairs, up to coil form and complete machine operated at rated load. The proposed approach is based on the design of experiments (DOE). The results of the work that will be carried out will allow to identify the most influential factors affecting insulation lifetime and the interactions between them.

The test setup comprises a Thermal vacuum chamber, an embedded dynamometer/brake system and a custom inverter based on SiC devices capable to apply PWM commutation of different dv/dt ratio.

The test rig would allow an all-in-one approach for multi-parameter measurement, thus minimizing the required test runs.

The test set-up will thus provide a means to confirm, experimentally validate, and also fine-tune insulation degradation lifetime models. In particular a lifetime model, based on the physic Of Failure (PoF) method, that considers the impact of the different stress factors on the system, is expected to be developed during the project.

The ultimate goal is to foster the development and adoption of electric drives for aerospace applications, resulting from more reliable procedures that allow accurate estimation of a system lifetime from the design stage (design reliability work flow) 

Presentation:

Title: “Impact of wide-bandgap devices on the insulation system of magnetics”

In the last few years wide-bandgap power devices, such as SiC and GaN switches, have been started to market. They provide superior performances respect to their Silicon counterparts, reaching faster commutation and maintaining their efficiency even in case of high temperature operation. Nevertheless, their impact on real system has not been completely investigated. The high dv/dt ratio, enabled by the fast commutation transients of SiC or GaN devices, introduces very high frequency harmonics that can trigger partial discharge phenomena in the windings of magnetics present in the circuit, leading to deterioration of the insulation systems.

For this reasons a trade-off between performance and reliability must be reached to enable the widespread utilization of wide-bandgap devices.

Davide Barater was born in Italy on August 13, 1983. He received Master’s degree in Electronic Engineering in 2009 and the Ph.D. degree in Information Technologies in 2014 from the University of Parma, Italy. He was an honorary scholar at the University of Nottingham, U.K, during 2012. He is now working as a postdoctoral research associate at the Department of Information Engineering, University of Parma, Italy. His research area is focused on power electronics for renewable energy systems, static energy conversion and motor drives. He is a reviewer of IEEE transaction on Power Electronics, on Industry application, on Industrial Informatics. He is author or coauthor of more than 20 international papers,  He holds one international patents.

 

Prof. Liserre

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Kolloquiumsvortrag: Prof. Alexandr Dmitriev, Chalmers University, Göteborg/ 29.06.2015

29.06.2015 von 17:15 bis 18:45

Institut für Materialwissenschaft, Kaiser Str. 2, Geb.C , Raum "Aquarium"

Titel:

Magnetoplasmonics and active control of light at the bottom-up playground (for nano-, meta-, micro- and beyond)


Abstract:

The combination of magnetism and plasmonics developed into a new burgeoning

field - magnetoplasmonics, where the control of non-reciprocity in light’s interaction with a magnetized media is targeted for various applications. I will discuss the two aspects of magnetoplasmonics: optical polarization-rotator metasurfaces actively tunable with magnetic field; and the label-free optical biochemosensing, where magnetoplasmonics delivers two orders of magnitude higher sensitivity than the current nanoplasmonic sensors.

All discussed magnetoplasmonic platforms are produced on a large (cm2) scale with the affordable and simple bottom-up nanofabrication we develop. I will also highlight our latest ‘any pattern on any surface’ versatile conformal nanofab protocol.

Prof. Faupel

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Sonderkolloquium: Prof. Dr. Thanassis Tiropanis (University of Southampton)/ 25.06.2015

25.06.2015 von 14:15 bis 15:45

Institut für Informatik, Ludewig-Meyn-Str. 2, Übungsraum 2

Titel:  "Web Observatories: Infrastructures for Engaging with Data and Analytics on a Global Scale"

 

Abstract:

 Web Observatories are global distributed resources that can engage communities with data and analytic resources to make the most of existing and emergent datasets including those of the linked data cloud, social media, online archives and media archives. This undertaking is promising in terms of fostering data literacy and innovation on a large scale but comes with infrastructural challenges. Those challenges include resource description and discovery, interoperability, privacy and performance for queries and analytics on a distributed scale. This talk presents how those challenges are addressed in the architecture of the Southampton University Web Observatory and discusses a research roadmap on Web Observatory development.

Prof. Hasselbring

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Kolloquiumsvortrag: Prof. Dr.-Ing. Dr.-Ing. habil. Robert Weigel / TU Erlangen

22.06.2015 von 17:15 bis 18:45

Institut für Materialwissenschaf UND Institut für Elektrotechnik und Informationstechnik, Kaiser Str. 2, Geb.C , Raum "Aquarium"

Titel: Highly Integrated Wideband Microwave Sensors for Emerging Biomedical Applications

 

Abstract: One of the most important challenges of modern and aging societies that need to be addressed is the improvement of health and lifetime of individuals. In the last decade, immense progress has been made in electronics based on nanoelectronics technologies in conjunction with complex smart and embedded system realizations. The current development trends in these key technologies are going to enable crucial innovations and the proliferation of solutions for medical applications such as biomedical sensing and spectroscopy. This talk presents miniaturized microwave and millimeter-wave silicon-germanium circuits and sensor systems for the above mentioned challenges. The present work explains the basic measurement principles and introduces the integrated vector network analyzer as a fundamental component for the design of compact powerful biomedical sensors. Several single-chip sensors as well as hybrid solutions will be presented and discussed. Furthermore, a special ultra-wideband sensor concept for spectroscopy coming with solutions for the injection of electromagnetic waves into biological samples will be demonstrated. Finally, future development trends will be discussed.

Prof. Quandt und Prof. Knöchel

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Kolloquiumsvortrag: Prof. Andreas Hütten - Universität Bielefeld / 15.06.2015

15.06.2015 von 17:15 bis 18:45

Institut für (Ost), Kaiser Str. 2, Geb.C , Raum "Aquarium"

Titel: Heusler alloys: fundamentals and applications

 

 

Abstract:
The triumphant advance of Heusler compounds can mainly be attributed to their unique band structure
enabling the realization of different physical properties such as ferromagnetism, semi- and superconductivity in one material class. As a consequence of the theoretically predictions of 100% spin polarized half- and full-Heusler compounds over the past decade, Heusler alloys are among the most promising materials class for future applications in magneto electronics. The resulting electronic structures as well as their magnetic properties will be used to identify potential areas of applications. Among these areas are magnetic logic, biosensors and granular GMR-sensors. Thin films made of Heusler compounds are not only relevant for spintronic applications. There is also great interest in the class of shape-memory compounds like X-Mn-Y (X=Ni, Co,Y= Ga, Sn, In) in thin films. For applications such as actuators, magnetic cooling and hybrid systems, thin films are often advantageous or mandatory. For magnetic cooling devices, thin films offer the advantage of a high surface to volume ratio. This allows a fast heat transfer. A general knowledge of the thin film influence on the martensitic transition (MT) is required for all these applications and will be discussed.

Prof. Faupel

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Sonderkolloquiumsvortrag: Prof. Dr. Mario Bebendorf (Universität Bayreuth) / 09.06.2015

09.06.2015 von 10:15 bis 11:45

Institut für Informatik, CAP 4, Raum 715

Titel: Niedrigrang-Approximation von elliptischen Randwertproblemen bei stark variablen Koeffizienten

Abstract:

Hierarchische Matrizen erlauben es unter Anderem, die Inverse und die Faktoren der LU-Zerlegung von Finite-Element-Diskretisierungen elliptischer Randwertprobleme nachweislich mit logarithmisch-linearer Komplexität zu approximieren. Der entsprechende Beweis weist allerdings eine starke Abhängigkeit des lokalen Ranges vom Verhältnis des größten und kleinsten Koeffizienten des Differentialoperators bzgl. der "L²"-Norm aus, was in numerischen Experimenten allerdings nie beobachtet werden konnte. Im Vortrag zeigen wir, dass diese Abhängigkeit bei Wahl geeigneter Normen nicht besteht. Hieraus kann eine logarithmische Abhängigkeit bzgl. der "L²"-Norm abgeleitet werden.

Prof. Börm

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Kolloquiumsvortrag: Prof.Tamas Kerekes Aalborg Universität / DK / 08.06.2015

08.06.2015 von 17:15 bis 18:45

Institut für (Ost), Kaiser Str. 2, Geb.C , Raum "Aquarium"

Titel:  "Problem Based Learning – the Aalborg way"

Abstract:

Problem Based Learning (PBL) has been successfully applied at Aalborg University (AAU) since it was established in 1974. PBL is not only about rote learning. Every semester students work in a group with fellow students having different academic strengths and weaknesses, combining their common knowledge to solve a problem. The work should end in the submission of a semester report, describing the main problem, the objectives and the methodology how the problem was solved and how successful they were in achieving the objectives, detailing the results, including simulation, modelling and laboratory experiments.

Group members will need to collaborate with each other, define and divide the tasks for achieving the goals that they set in the beginning of the project. This way the group work will have an academic and social dimension at the same time, by which the students will learn how to work together with other people, a quality which is very important on the labor market/in industry.

PBL gives the opportunity to put theoretical knowledge into practice. By working with “real-life” problems, the students will not only gain professional experience, but they will also make good contacts, that can be used in the future in case of job applications. Furthermore, these “real-life” problems come from industrial partners/companies, therefore students will work with problems related to leading edge research, and their results/findings might be included in tomorrow’s commercial products.

Prof. Liserre

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Kolloquiumsvortrag: Prof. Lene Oddershede, Niels Bohr Institut, Universität Kopenhagen / 01.06.2015

01.06.2015 von 17:15 bis 18:45

Institut für Materialwissenschaft, Kaiser Str. 2, Geb.C , Raum "Aquarium"

Titel: Optical control and biomedical applications of HOT nanoparticles

Abstract:

Precise optical control over individual metallic nanoparticles has huge potential for nano-architectural purposes. The talk will commence by explaining how a focused laser beam can control not only the position, but also the orientation of a single nanoparticle [1]. While optically manipulating metallic nanostructures, it is worth noting that absorption and heating associated with resonant irradiation of metallic nanoparticles can be extreme [2]. Moreover, the heating of a nanoparticle cannot be theoretically predicted as the precise focal intensity distribution on the nanoscale is unknown and typically highly aberrated [3]. Utilizing a novel membrane-based assay we directly quantify the heating of an individual irradiated gold nanoparticle and show how this depends on laser power and particle size, shape, orientation and composition [4,5]. Also, our novel results show how the photo-thermal effect of metallic nanoparticles can be used to create localized heat gradients inside living cells, which is highly useful for targeted drug delivery and for photothermal treatment of cancers.

[1] Selhuber-Unkel et al., Quantitative optical trapping of single gold nanorods. Nano Letters, vol. 8, p. 2998-3003 (2008).

[2] Bendix et al., Direct measurements of heating by electromagnetically trapped gold nanoparticles on supported lipid bilayers, ACS Nano, vol. 4 p.2256-2262 (2010).

[3] Kyrsting et al., Mapping 3D focal intensity exposes the stable trapping positions of single nanoparticles. Nano Letters vol.13 p.31-35 (2013).

[4] Ma et al., Large-Scale Orientation Dependent Heating from a Single Irradiated Gold Nanorod. Nano Letters vol.12 p.3954-3960 (2012).

[5] Ma et al., Heat generation by irradiated complex composite nanostructures. Nano Letters, vol. 14 p.612-619 (2014).

 

Prof. Christine Selhuber-Unkel

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Kolloquiumsvortrag: PD Dr. Oleg Petracic, Forschungszentrum Juelich GmbH / 18.05.2015

18.05.2015 von 17:15 bis 18:45

Institut für Materialwissenschaft, Kaiser Str. 2, Geb.C , Raum "Aquarium"

Titel: Functional nanomaterials from self-assembled magnetic nanoparticles

 

 

Abstract:

Nanoparticles (NPs) can be considered as multi-functional 'building blocks' for novel materials with tunable physical and chemical properties. Magnetic NPs can be used e.g. for novel energy efficient data storage systems, spintronic devices or permanent magnets with improved properties. I will report on (1.) magnetic monomer NPs from FePt, MnO and iron oxide and (2.) heterodimer ('Janus') NPs consisting of a ferromagnetic (FM) FePt particle attached to an antiferromagnetic (AF) MnO particle. The monomer iron oxide NPs have a diameter of 15 or 20 nm. By applying them onto various substrates and also using various techniques, they form self-organized sub-monolayers, monolayers, multilayers or 3d supercrystals. The structure and magnetism of these assemblies has been investigated using grazing incidence small angle x-ray and neutron scattering, electron microscopy and magnetometry. In FePt@MnO heterodimer particle systems the close contact of the two subunits yields an exchange bias effect. The spin structure has been studied using neutron scattering.

Our results yield the perspective on how to tune the magnetic behavior of the individual building blocks on the one hand and the collective properties of the entire NP assembly on the other hand.

 References:

[1]       S. A. Claridge, A. W. Castleman, S. N. Khanna, C. B. Murray, A. Sen, and P. S. Weiss, ACS Nano 3, 244 (2009).

[2]       O. Petracic, Superlatt. Microstr. 47, 569 (2010).

[3]       S. Bedanta, A. Barman, W. Kleemann, O. Petracic, and T. Seki, Magnetic nanoparticles-
a subject for both fundamental research and applications,
J. Nanomater. 2013, 952540 (2013)

[4]       D. Mishra, D. Greving, G. A. Badini Confalonieri, J. Perlich, B.P. Toperverg, H. Zabel, and
O. Petracic, Growth modes of nanoparticle superlattice thin films, Nanotechnology 25, 205602 (2014)

[5]       S. Bedanta, O. Petracic, and W. Kleemann , Supermagnetism, Handbook of Magnetic Materials, Vol. 23, Ed. K.J.H. Buschow, Elsevier (2015)

 

 

 

 

 

Prof. McCord

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Kolloquiumsvortrag: Prof. Harald Giessen, Physikalisches Institut, Uni Stuttgart / 04.05.2015

04.05.2015 von 17:15 bis 18:45

Institut für Materialwissenschaft, Kaiser Str. 2, Geb.C , Raum "Aquarium"

Titel: Complex functional plasmonics: from fundamentals to applications


Abatract: folgt

Prof. M. Elbahri

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Kolloquiumsvortrag: Prof. Dr. Nan Ma, Biomaterialforschung HZG / FU Berlin/ 27.04.2015

27.04.2015 von 17:15 bis 18:45

Institut für Materialwissenschaft, Kaiserstr. 2, Geb.C , Raum "Aquarium"

Titel: Stem cell and cardiac repair

 

 

Abstract:

 

Stem cell mediated therapies offer great regenerative potential to improve cardiac function and neovascularization in patients with cardiovascular disorder. Recently, numerous clinical and preclinical studies using different type of stem (progenitor) cells have demonstrated their promising therapeutic effect. However, the low rate of cell engraftment and survival in the ischemic tissue greatly limits their therapeutic efficacy. To achieve the maximal clinical benefits, Dr. Nan Ma and her team attempted to explore cell pre-selection, genetic enhancement, tissue engineering and protein and/or small molecule treatment approaches to further augment cell homing, engraftment and cell survival. In this presentation, Dr. Nan Ma will introduce you how to employ the novel cell-enhancement strategies to aid the stem cell treatment of ischemic heart disease. The presentation will also highlight the potential of applying genetic and chemical modulation to enhance stem cell therapeutic and latest progress on gaining mechanistic insights of stem cell-extracellular matrix interactions. Further, using Laser-Induced-Forward-Transfer (LIFT) cell printing techniques, we are able to produce functional cardiac patch. LIFT-based stem cell cardiac patches for the treatment of myocardial infarction might improve wound healing and functional preservation.

Prof. Selhuber-Unkel

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Kolloquimsvortrag: Dr. Karsten Wegner, ETH Zurich / 20.04.2015

20.04.2015 von 17:15 bis 18:45

Institut für Materialwissenschaft, Kaiser Str. 2, Geb.C , Raum "Aquarium

Titel: Flame Manufacture of ZnO and other Metal Oxide Nanoparticles

 

Abstract:

Flame spray pyrolysis has evolved into an extremely versatile process for production of single and multicomponent oxide nanoparticles of almost all periodic table elements. Material development has been carried out mostly with laboratory reactors at g/h scale, now requiring transfer into an industrial production environment. Successful process scale-up to kg/h output has been achieved for instance for zirconia or iron phosphate whereas the transfer remained challenging for zinc oxide nanoparticles.
This prompted us to investigate flame synthesis of ZnO in more detail. Formation and growth of spherical and rod-like structures was tracked by sampling nanoparticles thermophoretically in-situ the reactor and analyzing their morphology by electron microscopy. Along with temperature measurements and process simulations, conditions for production of sphere-like particles and nanorods could be developed. Characterization of the surface chemistry revealed shape-dependent differences that could affect the performance of the powders in catalytic hydrogen production, one envisioned application.

Prof. Adelung

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Kolloquiumsvortrag: Prof. Dr. James Currie / 17.04.2015

17.04.2015 von 14:15 bis 15:45

Institut für Informatik, Ludewig-Meyn-Str. 2, Übungsraum 2

Titel: Growth rate of binary words avoiding xxxR

Abstract:

Consider the set of those binary words with no non-empty factors of the form xxxR. Du, Mousavi, Schaeffer, and Shallit asked whether this set of words grows polynomially or exponentially with length. In this talk, we demonstrate the existence of upper and lower bounds on the number of such words of length n, where each of these bounds is asymptotically equivalent to a (different) function of the form Cnlg n+c, where C, c are constants.


Prof. Nowotka

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Kolloquiumsvortrag: Professor Arno Ehresmann, Universität Kassel (CINSaT) / 13.04.2015

13.04.2015 von 17:15 bis 18:45

Institut für Materialwissenschaft, Kaiser Str. 2, Geb.C , Raum "Aquarium"

Titel:  Light-ion bombardment induced tailored domains in magnetic thin film systems

 

Abstract:

Artificial magnetic domain patterns can be fabricated in magnetic thin film systems by light-ion bombardment induced magnetic patterning. This technique enables a local modification of anisotropies, e.g., the unidirectional anisotropy in exchange bias layer systems or the perpendicular anisotropy in Co/ Au multilayers. Remanently stable magnetic patterns (tailored domains) may be created, where the geometry and the local anisotropy may be set independently without large changes in surface topography. These patterns allow also a tailoring of the associated magnetic strayfield landscapes over the surface of the magnetic layer system. The talk will discuss the fundamentals for fabricating such artificial domain patterns, their use in a variety of sensor concepts and the use of the associated stray field landscapes for positioning and controlled movement of small particles.

 

 

 

 

Prof. J. McCord

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