Kolloquiumsvortrag, nn / 04.04.2016
04.04.2016 von 17:15 bis 18:45
Institut Ostufer, Kaiserstraße 2, 24143 Kiel, Raum: Geb. D, "Aquarium"
Titel:
Abstract:
Jeweils montags eine halbe Stunde vor Beginn der Vorträge, also um 16.45 Uhr, werden die Gastredner den Besuchern des Kolloquiums in einer zwanglosen Runde bei einer Tasse Kaffee in der "Eisdiele" (Eingangshalle Geb. D, neben dem "Aquarium") vorgestellt.
Ansprechpartnerin: Tanja Wengler (Tel. 0431-880-6001) dekanat@tf.uni-kiel.de
Jolanta Makowski (Tel. 0431-880-6068) dekanat@tf.uni-kiel.de
Alle Vorträge finden -
soweit nicht anders angegeben - im Raum Ü2/K des Instituts für
Informatik (Ludewig-Meyn-Str. 2, Vorbau des Mathematischen Seminars) freitags um 14 Uhr c.t. statt. 45 Minuten vor Vortragsbeginn stehen Tee
und Kaffee bereit.
Ansprechpartner/innen: Geschäftszimmer des Instituts für Informatik (Tel. 0431 880-4465)aktuell@informatik.uni-kiel.de
Nachfolgend alle Vortragstermine in chronologischer Abfolge
04.04.2016 von 17:15 bis 18:45
Institut Ostufer, Kaiserstraße 2, 24143 Kiel, Raum: Geb. D, "Aquarium"
Titel:
Abstract:
08.04.2016 von 14:15 bis 15:45
Institut für Informatik, Ludewig-Meyn-Straße 2, 24118 Kiel, Raum: Übungsraum 2/K
Titel:
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11.04.2016 von 17:15 bis 18:45
Institut für Materialwissenschaft, Raum: Geb. D, Aquarium, Kaiserstraße 2, 24143 Kiel
Titel: Biomimetic calcium phosphate mineralization - effects of surfaces and interfaces
Abstract:
Calcium phosphate is one of the most important biominerals. It comes in a variety of phases, e.g. hydroxyapatite, brushite, etc., and is a key component in bones, teeth, and tendons.1,2 Biomimetic calcium phosphate mineralization, that is, the synthesis of calcium phosphate/organic composites using a synthetic template or additive, provides access to a large variety of calcium phosphate composites that could for instance be useful for bone repair. However, the details of calcium phosphate nucleation, growth, and phase selection are not fully understood yet. To rationally design tailored materials for specific applications such as healthcare, this would however be essential.Among others, interfaces are a key factor affecting the formation, structure, composition, and properties of both the calcium phosphate deposits and the resulting hybrid materials. In spite of this, there are only relatively few studies on the role of surfaces and interfaces on calcium phosphate growth.The presentation will present data on calcium phosphate formation on model surfaces, both at the solid-liquid3 and the liquid-air interface,4-7 and discuss the effects of these interfaces on crystal formation. A special focus is put on the effects of polycations, such as poly(2-dimethylethylamino methacrylate) (PDMAEMA), because polycations have been less extensively studied than polyanions and there is hence a lack of information on their role in calcium phosphate mineralization. This also applies to the effects of oligomeric compounds as mineralization templates.8 Our studies show that not only the type of surface (anionic vs. cationic) but also the charge of each polymer surface (charged vs. uncharged) strongly affects the outcome of the mineralization process. A preliminary hypothesis of how polycations may regulate calcium phosphate is also proposed9 and – time permitting – I will also present some recent data on how ionic liquids can be used to generate interesting composite materials.10
References
(1) Calcium
Phosphates in Biological and Industrial Systems; Kluwer Academic
Publishers: Norwell-Dordrecht, 1998.
(2) Handbook
of Biomineralization; Wiley-VCH: Weinheim, 2007.
(10) Salama, A.; Neumann, M.; Günter, C.; Taubert, A. Beilstein. J. Nanotechnol. 2014, 5, 1553.
15.04.2016 von 14:15 bis 15:45
Institut für Informatik, Ludewig-Meyn-Straße 2, 24118 Kiel, Raum: Übungsraum 2/K
Titel:
Abstract:
18.04.2016 von 17:15 bis 18:45
Institut Ostufer, Kaiserstraße 2, 24143 Kiel, Raum: Geb. D, "Aquarium"
Titel:
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22.04.2016 von 14:15 bis 15:45
Institut für Informatik, Ludewig-Meyn-Straße 2, 24118 Kiel, Raum: Übungsraum 2/K
Titel: Publishing Inference-Proof Relational Data: Design, Implementation, Optimization and Experiments
Abstract:
An agent might want to share information maintained by a relational database by means of data publishing, i.e., by generating a view customized for the further unrestricted usage by the anticipated clients. Often, however, the usability of the view has to be confined to ensure the confidentiality of particular pieces of information in need of being excluded from sharing. Within the framework of Controlled Interaction Execution, we have designed a sound and complete generation procedure for an inference-proof (i.e., consistent and confidentiality-preserving) view that has minimal distortion distance to the original database instance. Confidentiality is achieved regarding a policy declared in terms of first-order logic sentences to be kept hidden. Consistency ensures the compliance with postulated a priori knowledge of the clients, expressed as first-order logic sentences, too. Conceptually, the generation procedure performs a depth-first search for satisfying the constraints and follows a branch-and-bound strategy for minimizing distortions. We have further provided an actual implementation of the generation procedure together with several optimizations. In particular, we exploited sophisticated local lower bounds on the number of additional distortions in subtrees to be explored to prune them early, and we employed coordinated parallelization for searching in many subtrees concurrently. Moreover, we have performed an experimental evaluation in terms of runtime behavior. Finally, we have also explored to replace depth-first searching by priority searching, exhibited special cases that can be handled more efficiently, considered heuristics for only approximating distortion minimality, and explored options of refined mechanisms to employ and invent constants to resolve current violations of constraints.
The original design was joint work with Lena Wiese (J. Biskup/L. Wiese, Journal of Computer Security 16 (2008) 477–494; L. Wiese, Dissertation, TU Dortmund 2009; J. Biskup, L. Wiese, Theoretical Computer Science 412 (2011) 4044–4072).
The implementation, the optimizations and the evaluation are joint work with Christine Dahn, Katharina Diekmann, Ralf Menzel, Dirk Schalge und Lena Wiese (manuscript submitted for publication).
25.04.2016 von 17:15 bis 18:15
Institut Ostufer, Kaiserstraße 2, 24143 Kiel, Raum: Geb. D, "Aquarium"
Titel:
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29.04.2016 von 14:15 bis 15:45
Institut für Informatik, Ludewig-Meyn-Straße 2, 24118 Kiel, Raum: Übungsraum 2/K
Titel:
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02.05.2016 von 17:15 bis 18:45
Institut Ostufer, Kaiserstraße 2, 24143 Kiel, Raum: Geb. D, "Aquarium"
06.05.2016 von 14:15 bis 15:45
Institut für Informatik, Ludewig-Meyn-Straße 2, 24118 Kiel, Raum: Übungsraum 2/K
Titel:
Abstract:
09.05.2016 von 17:15 bis 18:45
Institut Ostufer, Kaiserstraße 2, 24143 Kiel, Raum: Geb. D, "Aquarium"
Title:
Abstract:
13.05.2016 von 11:00 bis 12:00
Institut Ostufer, Kaiserstraße 2, 24143 Kiel, Raum: Geb. D, "Aquarium"
Titel: "Design and resonance-damping of LCL-filter based grid-tie
converters and recent developments on power electronics control"
Abstract - The first part of the lecture will deal with LCL-filter based
three-phase grid-tie converters. Adopting an LCL-filter, instead of an
L-filter, allows using a reduced value for the total inductance and so
reducing losses and preserving dynamics. However, stability problems can
arise if the present resonance is not properly damped. Passive damping
uses additional resistors and active damping modifies the control
algorithm. Many solutions have been proposed in a vast amount of
publications. For this lecture, different configurations for passive
damping will be explained along with the following active damping
procedures: lead-lag network, capacitor-current feedback and notch
filter. Stability and robust design against grid line inductance
variations will also be considered. The last part of the lecture
explores the opportunity of harmonic mitigation at distribution level in
small hybrid ac/dc building by using a centralized power factor
corrector (PFC) with large bandwidth. It is foreseeable an increased
presence of hybrid ac/dc buildings with coexisting ac and dc
infrastructures because of the unprecedented expansion of native dc
powered equipment (LEDs and consumer electronics). The proposals provide
all the steps for the straightforward control design of the PFC and its
harmonic mitigation function (HMF) with fast calculations. The HMF
requires only software modifications in the PFC and one sensor to
measure the nonlinear load.
13.05.2016 von 14:15 bis 15:45
Institut für Informatik, Ludewig-Meyn-Straße 2, 24118 Kiel, Raum: Übungsraum 2/K
Titel:
Abstract :
20.05.2016 von 14:15 bis 15:45
Institut für Informatik, Ludewig-Meyn-Straße 2, 24118 Kiel, Raum: Übungsraum 2/K
Titel:
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23.05.2016 von 17:15 bis 18:45
Institut Ostufer, Kaiserstraße 2, 24143 Kiel, Raum: Geb. D, "Aquarium"
Titel:
Abstract:
27.05.2016 von 14:15 bis 16:00
Institut für Informatik, Ludewig-Meyn-Straße 2, 24118 Kiel, Raum: Übungsraum 2/K
27.05.2016 von 16:15 bis 17:30
Institut für Informatik, Ludewig-Meyn-Straße 2, 24118 Kiel, Raum: Übungsraum 2/K
Titel: Generating and Traversing Large Graphs in External-Memory
Abstract:
Large graphs arise naturally in many real world
applica-
tions. The actual performance of simple RAM model algo-
rithms for traversing these graphs (stored in external mem-
ory) deviates significantly from their linear or near-linear
predicted performance because of the large number of I/Os
they incur. In order to alleviate the I/O bottleneck, many
external memory graph traversal algorithms have been de-
signed with provable worst-case guarantees. In the talk I
highlight some techniques used in the design and engineer-
ing of such algorithms and survey the state-of-the-art in
I/O-efficient graph traversal algorithms. I will also report
on recent work concerning the generation of massive scale
free networks under resource constraints.
30.05.2016 von 17:15 bis 18:45
Institut Ostufer, Kaiserstraße 2, 24143 Kiel, Raum: Geb. D, "Aquarium"
03.06.2016 von 14:15 bis 15:45
Institut für Informatik, Ludewig-Meyn-Straße 2, 24118 Kiel, Raum: Übungsraum 2/K
Prof. Dr. Reinhard von Hanxleden
06.06.2016 von 17:15 bis 18:45
Institut Ostufer, Kaiserstraße 2, 24143 Kiel, Raum: Geb. D, "Aquarium"
Titel:
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09.06.2016 von 13:20 bis 14:00
Driftmann-Hörsaal, Olshausenstr. 75, Hörsaal 3
Abstract: To image in high resolution large and occlusion-prone scenes, a camera must move above and around. Degradation of visibility due to geometric occlusions and distances is exacerbated by scattering underwater. Moreover, underwater and in other media, artificial lighting is needed. We propose to jointly optimize the path of platforms carrying either a camera or a light source. The work generalizes the next best view concept of robot vision to scattering media and cooperative movable lighting.
09.06.2016 von 14:05 bis 14:50
Driftmann-Hörsaal, Olshausenstr. 75, Hörsaal 3
Abstract: With the widespread use of imaging technologies in basic research and
routine clinical practice, medical researchers and physicians are faced
with analyzing an ever-increasing amount of complex image data. Also in
biology imaging has become an indispensable tool, for instance for
behavior studies of small animals. Many computer vision algorithms have
been successfully adapted and applied to biomedical imaging
applications. However, the specific characteristics of biomedical image
data pose new challenges and force researchers to develop novel concepts
and algorithms. In fact, biomedical imaging can be seen as another
driving force for computer vision research. This talk emphasizes this
fundamental research view of biomedical computer vision. A variety of
topics will be motivated by current research in biology and medicine.
The related challenges, concepts, and algorithms will be discussed.
13.06.2016 von 17:15 bis 18:45
Institut Ostufer, Kaiserstraße 2, 24143 Kiel, Raum: Geb. D, "Aquarium"
Titel:
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20.06.2016 von 17:15 bis 18:45
Institut für Materialwissenschaften, Kaiserstraße 2, 24143 Kiel, Raum: Geb. D, "Aquarium"
23.06.2016 von 16:00 bis 17:00
Christian-Albrechts-Platz 4, Raum 910
Title: Systems of polynomial equations over finite fields and linear codes
Abstract:
We consider the problem of determining the maximum number of common solutions of a bunch of polynomials over a finite field. The simplest case is of course of a single (nonzero) polynomial in one variable, where the degree usually gives the maximum number of solutions. In the general case of several polynomials in several variables, the problem is meaningful and interesting when the base field is finite and the solutions are sought in the corresponding affine or projective space over the given finite field. When these polynomials are assumed linearly independent and of a degree bounded by a fixed positive integer, the problem is equivalent to a problem in coding theory, namely, that of determining the generalized Hamming weights of Reed-Muller codes. The known solution in this case, due to Heijnen and Pellikaan (1998) uses results in combinatorics such as Kruskal-Katona theorem.
The case of systems of linearly independent multivariate homogeneous polynomials, all of the same degree, where the zeros are considered in a projective space over the given finite field is perhaps even more interesting. There is an elaborate conjecture of Tsfasman and Boguslavsky that predicts the maximum value when the degree of the homogeneous polynomials is not too large in comparison to the size of the finite field. Special cases of the conjecture are known to be true, thanks to the results of Serre (1991) and Boguslavsky (1997), but the general case has been open for quite some time.
27.06.2016 von 17:15 bis 18:45
Institut Ostufer, Kaiserstraße 2, 24143 Kiel, Raum: Geb. D, "Aquarium"
In the first part of the talk, I will present our basic framework for studying network representations in the human brain. In particular, analyzing brain oscillations and oscillatory interactions allows us to characterize regional activation patterns and mechanisms supporting inter-regional communication and plasticity. In the second part, I will describe some recent studies on network representations of memory traces. Using intracranial EEG recordings in epilepsy patients as well as simultaneous EEG/fMRI recordings in healthy participants, we found that stimulus-specific representations are reinstantiated during memory recall and spontaneously reactivated during awake resting state and sleep. As I will show in the third part, analyzing content-specific representations may be clinically relevant to identify early pathophysiology and potential new therapies in Alzheimer’s dementia. Using fMRI in genetic risk carriers for Alzheimer’s disease, we observed impaired entorhinal grid cell-like representations and altered navigational strategies. Furthermore, we found that deep brain stimulation to the medial temporal lobe may be a novel therapeutic option for ameliorating memory dysfunction; understanding the oscillatory basis of memory processes may help optimizing stimulation parameters.
28.06.2016 von 14:30 bis 15:30
Christian-Albrechts-Platz 4, Raum 1304 a
Titel: Chaos: Versatile and Efficient All-to-All Data Sharing and
In-Network Processing at Scale
Abstract: An important building block for low-power wireless systems is
to efficiently share and process data among all devices in a network. We
introduce Chaos, a primitive that natively supports all-to-all data
sharing in low-power wireless networks. Different from current
approaches, Chaos embeds programmable in-network processing into a
communication support based on synchronous transmissions. We show that
this design enables a variety of common all-to-all interactions,
including network-wide agreement and data aggregation. Chaos scales
efficiently to networks consisting of hundreds of nodes, achieving
severalfold improvements over the state of the art in radio duty cycle
and latency at high reliability. For example, Chaos computes simple
aggregates, such as the maximum, in a 100-node multi-hop network within
less than 90 milliseconds using off-the-shelf IEEE 802.15.4 radios.
Moreover, Chaos departs from the traditional message-based programming
paradigm of networking and utilizes an approach that is similar to
shared memory: Nodes maintain local state which they merge with any
received state and which they in-turn share with neighboring nodes. We
discuss how this paradigm changes protocol design and implementation.
For example, we show how Chaos can provide widespread communication
patterns such as collection, dissemination, agreement, and aggregation
at high performance and low implementation complexity.
01.07.2016 von 14:15 bis 15:45
Institut für Informatik, Ludewig-Meyn-Straße 2, 24118 Kiel, Raum: Übungsraum 2/K
Titel:
Abstract:
04.07.2016 von 17:15 bis 18:45
Institut Ostufer, Kaiserstraße 2, 24143 Kiel, Raum: Geb. D, "Aquarium"
08.07.2016 von 14:15 bis 15:45
Institut für Informatik, Ludewig-Meyn-Straße 2, 24118 Kiel, Raum: Übungsraum 2/K
Titel:
Abstract:
11.07.2016 von 17:15 bis 18:45
Institut Ostufer, Kaiserstraße 2, 24143 Kiel, Raum: Geb. D, "Aquarium"
Today, spin waves are seen as high potential information carrier
for next-generation information and communication devices [1]. This view is based on the substantially reduced energy dissipation and much smaller wavelengths of spin waves compared to traditional charge current
signals. For the implementation
of spin wave technology into applicable devices, however, novel concepts
for the generation, manipulation, and detection of spin waves are yet to be found. With respect to spin wave generation,
it was
typically necessary to either use patterned transducers with sizes on the order
of the desired wavelengths (striplines or point-contacts),
or to
generate those spin waves parametrically by a double-frequency
spatially uniform microwave signal [2]. In this presentation, I will report on a newly discovered concept for the generation of spin
waves, which overcomes the bandwidth limitations
in terms of the minimum wavelength
limit given by the patterning size. This method utilizes the translation of natural topological defects, namely the gyration
of magnetic
vortex cores to generate isotropically
propagating, non-reciprocal spin waves
[3].
Experimentally, such spin-waves
were directly observed by means of time-resolved x-ray microscopy. Furthermore, I
will address directional and one-dimensional spin wave emission in anistropic magnetic
systems.
[1] D. Rosso, “International Technology Roadmap for Semiconductors Explores Next 15
Years of Chip Technology”, www.semiconductors.org, (2014).
[2] A. G. Gurevich and G. A. Melkov,
Magnetization Oscillations and Waves. New York:
CRC,
1996.
[3] S. Wintz et al., submitted (2015).
Today, spin waves are seen as high potential information carrier for next-generation information and communication devices. This is based on the substantially reduced energy dissipation and much smaller wavelengths of spin waves compared to traditional charge current signals. For a device implementation, however, novel concepts for the generation, manipulation, and detection of spin waves are yet to be found. Here, we report on a newly discovered concept for the generation of spin waves, which overcomes typical bandwidth limitations of traditional spin wave excitation methods. Our approach utilizes the gyration of magnetic vortex cores to generate isotropically propagating, non- reciprocal spin waves.
15.07.2016 von 14:15 bis 15:45
Institut für Informatik, Ludewig-Meyn-Straße 2, 24118 Kiel, Raum: Übungsraum 2/K
Titel:
Abstract:
22.07.2016 von 14:15 bis 15:45
Institut für Informatik, Ludewig-Meyn-Straße 2, 24118 Kiel, Raum: Übungsraum 2/K
Titel:
Abstract:
18.07.2016 von 17:15 bis 18:45
Institut Ostufer, Kaiserstraße 2, 24143 Kiel, Raum: Geb. D, "Aquarium"
Titel:
Abstract:
09.09.2016 von 09:30 bis 11:00
Institut für Elektrotechnik, Kaiserstraße 2, 24143 Kiel, Geb. D, "Aquarium"
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.