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2019


A Learnable Safety Measure
A Learnable Safety Measure

Heim, S., Rohr, A. V., Trimpe, S., Badri-Spröwitz, A.

Conference on Robot Learning, November 2019 (conference) Accepted

dlg ics

Arxiv [BibTex]

2019


Arxiv [BibTex]


Predictive Triggering for Distributed Control of Resource Constrained Multi-agent Systems
Predictive Triggering for Distributed Control of Resource Constrained Multi-agent Systems

Mastrangelo, J. M., Baumann, D., Trimpe, S.

In Proceedings of the 8th IFAC Workshop on Distributed Estimation and Control in Networked Systems, pages: 79-84, 8th IFAC Workshop on Distributed Estimation and Control in Networked Systems (NecSys), September 2019 (inproceedings)

ics

arXiv PDF DOI [BibTex]

arXiv PDF DOI [BibTex]


Event-triggered Pulse Control with Model Learning (if Necessary)
Event-triggered Pulse Control with Model Learning (if Necessary)

Baumann, D., Solowjow, F., Johansson, K. H., Trimpe, S.

In Proceedings of the American Control Conference, pages: 792-797, American Control Conference (ACC), July 2019 (inproceedings)

ics

arXiv PDF [BibTex]

arXiv PDF [BibTex]


Data-driven inference of passivity properties via Gaussian process optimization
Data-driven inference of passivity properties via Gaussian process optimization

Romer, A., Trimpe, S., Allgöwer, F.

In Proceedings of the European Control Conference, European Control Conference (ECC), June 2019 (inproceedings)

ics

PDF [BibTex]

PDF [BibTex]


Trajectory-Based Off-Policy Deep Reinforcement Learning
Trajectory-Based Off-Policy Deep Reinforcement Learning

Doerr, A., Volpp, M., Toussaint, M., Trimpe, S., Daniel, C.

In Proceedings of the International Conference on Machine Learning (ICML), International Conference on Machine Learning (ICML), June 2019 (inproceedings)

Abstract
Policy gradient methods are powerful reinforcement learning algorithms and have been demonstrated to solve many complex tasks. However, these methods are also data-inefficient, afflicted with high variance gradient estimates, and frequently get stuck in local optima. This work addresses these weaknesses by combining recent improvements in the reuse of off-policy data and exploration in parameter space with deterministic behavioral policies. The resulting objective is amenable to standard neural network optimization strategies like stochastic gradient descent or stochastic gradient Hamiltonian Monte Carlo. Incorporation of previous rollouts via importance sampling greatly improves data-efficiency, whilst stochastic optimization schemes facilitate the escape from local optima. We evaluate the proposed approach on a series of continuous control benchmark tasks. The results show that the proposed algorithm is able to successfully and reliably learn solutions using fewer system interactions than standard policy gradient methods.

ics

arXiv PDF [BibTex]

arXiv PDF [BibTex]


Feedback Control Goes Wireless: Guaranteed Stability over Low-power Multi-hop Networks
Feedback Control Goes Wireless: Guaranteed Stability over Low-power Multi-hop Networks

(Best Paper Award)

Mager, F., Baumann, D., Jacob, R., Thiele, L., Trimpe, S., Zimmerling, M.

In Proceedings of the 10th ACM/IEEE International Conference on Cyber-Physical Systems, pages: 97-108, 10th ACM/IEEE International Conference on Cyber-Physical Systems, April 2019 (inproceedings)

Abstract
Closing feedback loops fast and over long distances is key to emerging applications; for example, robot motion control and swarm coordination require update intervals below 100 ms. Low-power wireless is preferred for its flexibility, low cost, and small form factor, especially if the devices support multi-hop communication. Thus far, however, closed-loop control over multi-hop low-power wireless has only been demonstrated for update intervals on the order of multiple seconds. This paper presents a wireless embedded system that tames imperfections impairing control performance such as jitter or packet loss, and a control design that exploits the essential properties of this system to provably guarantee closed-loop stability for linear dynamic systems. Using experiments on a testbed with multiple cart-pole systems, we are the first to demonstrate the feasibility and to assess the performance of closed-loop control and coordination over multi-hop low-power wireless for update intervals from 20 ms to 50 ms.

ics

arXiv PDF DOI Project Page [BibTex]

arXiv PDF DOI Project Page [BibTex]


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A special issue on hydrogen-based Energy storage

Hirscher, M.

{International Journal of Hydrogen Energy}, 44, pages: 7737, Elsevier, Amsterdam, 2019 (misc)

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DOI [BibTex]

DOI [BibTex]


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Nanoscale X-ray imaging of spin dynamics in Yttrium iron garnet

Förster, J., Wintz, S., Bailey, J., Finizio, S., Josten, E., Meertens, D., Dubs, C., Bozhko, D. A., Stoll, H., Dieterle, G., Traeger, N., Raabe, J., Slavin, A. N., Weigand, M., Gräfe, J., Schütz, G.

2019 (misc)

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link (url) [BibTex]

link (url) [BibTex]


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Reconfigurable nanoscale spin wave majority gate with frequency-division multiplexing

Talmelli, G., Devolder, T., Träger, N., Förster, J., Wintz, S., Weigand, M., Stoll, H., Heyns, M., Schütz, G., Radu, I., Gräfe, J., Ciubotaru, F., Adelmann, C.

2019 (misc)

Abstract
Spin waves are excitations in ferromagnetic media that have been proposed as information carriers in spintronic devices with potentially much lower operation power than conventional charge-based electronics. The wave nature of spin waves can be exploited to design majority gates by coding information in their phase and using interference for computation. However, a scalable spin wave majority gate design that can be co-integrated alongside conventional Si-based electronics is still lacking. Here, we demonstrate a reconfigurable nanoscale inline spin wave majority gate with ultrasmall footprint, frequency-division multiplexing, and fan-out. Time-resolved imaging of the magnetisation dynamics by scanning transmission x-ray microscopy reveals the operation mode of the device and validates the full logic majority truth table. All-electrical spin wave spectroscopy further demonstrates spin wave majority gates with sub-micron dimensions, sub-micron spin wave wavelengths, and reconfigurable input and output ports. We also show that interference-based computation allows for frequency-division multiplexing as well as the computation of different logic functions in the same device. Such devices can thus form the foundation of a future spin-wave-based superscalar vector computing platform.

mms

link (url) [BibTex]

link (url) [BibTex]


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Hydrogen Energy

Hirscher, M., Autrey, T., Orimo, S.

{ChemPhysChem}, 20, pages: 1153-1411, Wiley-VCH, Weinheim, Germany, 2019 (misc)

mms

link (url) DOI [BibTex]

link (url) DOI [BibTex]


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Real-space imaging of confined magnetic skyrmion tubes

Birch, M. T., Cortés-Ortuño, D., Turnbull, L. A., Wilson, M. N., Groß, F., Träger, N., Laurenson, A., Bukin, N., Moody, S. H., Weigand, M., Schütz, G., Popescu, H., Fan, R., Steadman, P., Verezhak, J. A. T., Balakrishnan, G., Loudon, J. C., Twitchett-Harrison, A. C., Hovorka, O., Fangohr, H., Ogrin, F., Gräfe, J., Hatton, P. D.

2019 (misc)

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link (url) [BibTex]

link (url) [BibTex]

2011


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Amorphous grain boundary layers in the ferromagnetic nanograined ZnO films

Straumal, B. B., Mazilkin, A. A., Protasova, S. G., Myatiev, A. A., Straumal, P. B., Goering, E., Baretzky, B.

In 520, pages: 1192-1194, Hersonissos, Greece, 2011 (inproceedings)

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DOI [BibTex]

2011


DOI [BibTex]


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Inversed solid-phase grain boundary wetting in the Al-Zn system

Protasova, S. G., Kogtenkova, O. A., Straumal, B. B., Zieba, P., Baretzky, B.

In 46, pages: 4349-4353, Mie, Japan, 2011 (inproceedings)

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DOI [BibTex]

DOI [BibTex]


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First measurement of the heat effect of the grain boundary wetting phase transition

Straumal, B. B., Kogtenkova, O. A., Protasova, S. G., Zieba, P., Czeppe, T., Baretzky, B., Valiev, R. Z.

In 46, pages: 4243, Mie, Japan, 2011 (inproceedings)

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DOI [BibTex]

DOI [BibTex]


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Transmission electron microscopy investigation of boundaries between amorphous "grains" in Ni50Nb20Y30 alloy

Mazilkin, A. A., Abrosimova, G. E., Protasova, S. G., Straumal, B. B., Schütz, G., Dobatkin, S. V., Bakai, A. S.

In 46, pages: 4336-4342, Mie, Japan, 2011 (inproceedings)

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DOI [BibTex]

DOI [BibTex]

2004


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High-speed dynamics of magnetization processes in hard magnetic particles and thin platelets

Goll, D., Kronmüller, H.

In Proceedings of the 18th International Workshop on Rare-Earth Magnets and their Applications, pages: 465-469, Laboratoire de Cristallographie/Laboratoire Louis Neel, CNRS, Grenoble, 2004 (inproceedings)

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[BibTex]

2004


[BibTex]


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Nanoscale Materials for Energy Storage
{Materials Science \& Engineering B}, 108, pages: 292, Elsevier, 2004 (misc)

mms

[BibTex]

[BibTex]


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High-speed dynamics of magnetization processes in hard magnetic particles and thin platelets

Goll, D., Kronmüller, H.

In Proceedings of the 18th International Workshop on Rare-Earth Magnets and their Applications, pages: 465-469, Laboratoire de Cristallographie/Laboratoire Louis Neel, CNRS, Grenoble, 2004 (inproceedings)

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[BibTex]

[BibTex]


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Modern nanocrystalline/nanostructured hard magnetic materials

Kronmüller, H., Goll, D.

In 272-276, pages: e319-e320, Rome [Italy], 2004 (inproceedings)

mms

[BibTex]

[BibTex]


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Modern nanostructured high-temperature permanent magnets

Goll, D., Kronmüller, H., Stadelmaier, H. H.

In Proceedings of the 18th International Workshop on Rare-Earth Magnets and their Applications, pages: 578-583, Laboratoire de Cristallographie/Laboratoire Louis Néel, CNRS, Grenoble, 2004 (inproceedings)

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[BibTex]

[BibTex]


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Imaging sub-ns spin dynamics in magnetic nanostructures with magnetic transmission X-ray microscopy

Fischer, P., Stoll, H., Puzic, A., Van Waeyenberge, B., Raabe, J., Haug, T., Denbeaux, G., Pearson, A., Höllinger, R., Back, C. H., Weiss, D., Schütz, G.

In Synchrotron Radiation Instrumentation, 705, pages: 1291-1294, AIP Conference Proceedings, American Institute of Physics, San Francisco, California (USA), 2004 (inproceedings)

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[BibTex]

[BibTex]


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Modern nanostructured high-temperature permanent magnets

Goll, D., Kronmüller, H., Stadelmaier, H. H.

In Proceedings of the 18th International Workshop on Rare-Earth Magnets and their Applications, pages: 578-583, Laboratoire de Cristallographie/Laboratoire Louis Néel, CNRS, Grenoble, 2004 (inproceedings)

mms

[BibTex]

[BibTex]


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Existence of transient temperature spike induced by SHI: evidence by ion beam analysis

Avasthi, D. K., Ghosh, S., Srivastava, S. K., Assmann, W.

In 219-220, pages: 206-214, Albuquerque, NM [USA], 2004 (inproceedings)

mms

[BibTex]

[BibTex]


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Hard magnetic hollow nanospheres

Goll, D., Berkowitz, A. E., Bertram, H. N.

In Proceedings of the 18th International Workshop on Rare-Earth Magnets and their Applications, pages: 704-707, Laboratoire de Cristallographie/Laboratoire Louis Neel, CNRS, Grenoble, 2004 (inproceedings)

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[BibTex]

[BibTex]