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2020


A little damping goes a long way: a simulation study of how damping influences task-level stability in running
A little damping goes a long way: a simulation study of how damping influences task-level stability in running

Heim, S., Millard, M., Mouel, C. L., Badri-Spröwitz, A.

Biology Letters, 16(9), September 2020 (article)

Abstract
It is currently unclear if damping plays a functional role in legged locomotion, and simple models often do not include damping terms. We present a new model with a damping term that is isolated from other parameters: that is, the damping term can be adjusted without retuning other model parameters for nominal motion. We systematically compare how increased damping affects stability in the face of unexpected ground-height perturbations. Unlike most studies, we focus on task-level stability: instead of observing whether trajectories converge towards a nominal limit-cycle, we quantify the ability to avoid falls using a recently developed mathematical measure. This measure allows trajectories to be compared quantitatively instead of only being separated into a binary classification of ‘stable' or ‘unstable'. Our simulation study shows that increased damping contributes significantly to task-level stability; however, this benefit quickly plateaus after only a small amount of damping. These results suggest that the low intrinsic damping values observed experimentally may have stability benefits and are not simply minimized for energetic reasons. All Python code and data needed to generate our results are available open source.

dlg ics

link (url) DOI [BibTex]

2020


link (url) DOI [BibTex]


Transient coarsening and the motility of optically heated Janus colloids in a binary liquid mixture
Transient coarsening and the motility of optically heated Janus colloids in a binary liquid mixture

Gomez-Solano, J., Roy, S., Araki, T., Dietrich, S., Maciolek, A.

Soft Matter, 16, pages: 8359-8371, Royal Society of Chemistry, August 2020 (article)

Abstract
A gold-capped Janus particle suspended in a near-critical binary liquid mixture can self-propel under illumination. We have immobilized such a particle in a narrow channel and carried out a combined experimental and theoretical study of the non-equilibrium dynamics of a binary solvent around it – lasting from the very moment of switching illumination on until the steady state is reached. In the theoretical study we use both a purely diffusive and a hydrodynamic model, which we solve numerically. Our results demonstrate a remarkable complexity of the time evolution of the concentration field around the colloid. This evolution is governed by the combined effects of the temperature gradient and the wettability, and crucially depends on whether the colloid is free to move or is trapped. For the trapped colloid, all approaches indicate that the early time dynamics is purely diffusive and characterized by composition layers travelling with constant speed from the surface of the colloid into the bulk of the solvent. Subsequently, hydrodynamic effects set in. Anomalously large nonequilibrium fluctuations, which result from the temperature gradient and the vicinity of the critical point of the binary liquid mixture, give rise to strong concentration fluctuations in the solvent and to permanently changing coarsening patterns not observed for a mobile particle. The early time dynamics around initially still Janus colloids produces a force which is able to set the Janus colloid into motion. The propulsion due to this transient dynamics is in the direction opposite to that observed after the steady state is attained.

icm

link (url) DOI [BibTex]

link (url) DOI [BibTex]


Event-triggered Learning
Event-triggered Learning

Solowjow, F., Trimpe, S.

Automatica, 117, Elsevier, July 2020 (article)

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arXiv PDF DOI Project Page [BibTex]

arXiv PDF DOI Project Page [BibTex]


Interface-mediated spontaneous symmetry breaking and mutual communication between drops containing chemically active particles
Interface-mediated spontaneous symmetry breaking and mutual communication between drops containing chemically active particles

Singh, D., Domínguez, A., Choudhury, U., Kottapalli, S., Popescu, M., Dietrich, S., Fischer, P.

Nature Communications, 11(2210), May 2020 (article)

Abstract
Symmetry breaking and the emergence of self-organized patterns is the hallmark of com- plexity. Here, we demonstrate that a sessile drop, containing titania powder particles with negligible self-propulsion, exhibits a transition to collective motion leading to self-organized flow patterns. This phenomenology emerges through a novel mechanism involving the interplay between the chemical activity of the photocatalytic particles, which induces Mar- angoni stresses at the liquid–liquid interface, and the geometrical confinement provided by the drop. The response of the interface to the chemical activity of the particles is the source of a significantly amplified hydrodynamic flow within the drop, which moves the particles. Furthermore, in ensembles of such active drops long-ranged ordering of the flow patterns within the drops is observed. We show that the ordering is dictated by a chemical com- munication between drops, i.e., an alignment of the flow patterns is induced by the gradients of the chemicals emanating from the active particles, rather than by hydrodynamic interactions.

pf icm

link (url) DOI [BibTex]


Data-efficient Auto-tuning with Bayesian Optimization: An Industrial Control Study
Data-efficient Auto-tuning with Bayesian Optimization: An Industrial Control Study

Neumann-Brosig, M., Marco, A., Schwarzmann, D., Trimpe, S.

IEEE Transactions on Control Systems Technology, 28(3):730-740, May 2020 (article)

Abstract
Bayesian optimization is proposed for automatic learning of optimal controller parameters from experimental data. A probabilistic description (a Gaussian process) is used to model the unknown function from controller parameters to a user-defined cost. The probabilistic model is updated with data, which is obtained by testing a set of parameters on the physical system and evaluating the cost. In order to learn fast, the Bayesian optimization algorithm selects the next parameters to evaluate in a systematic way, for example, by maximizing information gain about the optimum. The algorithm thus iteratively finds the globally optimal parameters with only few experiments. Taking throttle valve control as a representative industrial control example, the proposed auto-tuning method is shown to outperform manual calibration: it consistently achieves better performance with a low number of experiments. The proposed auto-tuning framework is flexible and can handle different control structures and objectives.

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arXiv (PDF) DOI Project Page [BibTex]

arXiv (PDF) DOI Project Page [BibTex]


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Sliding Mode Control with Gaussian Process Regression for Underwater Robots

Lima, G. S., Trimpe, S., Bessa, W. M.

Journal of Intelligent & Robotic Systems, January 2020 (article)

ics

DOI [BibTex]

DOI [BibTex]


Hierarchical Event-triggered Learning for Cyclically Excited Systems with Application to Wireless Sensor Networks
Hierarchical Event-triggered Learning for Cyclically Excited Systems with Application to Wireless Sensor Networks

Beuchert, J., Solowjow, F., Raisch, J., Trimpe, S., Seel, T.

IEEE Control Systems Letters, 4(1):103-108, January 2020 (article)

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arXiv PDF DOI Project Page [BibTex]

arXiv PDF DOI Project Page [BibTex]


Control-guided Communication: Efficient Resource Arbitration and Allocation in Multi-hop Wireless Control Systems
Control-guided Communication: Efficient Resource Arbitration and Allocation in Multi-hop Wireless Control Systems

Baumann, D., Mager, F., Zimmerling, M., Trimpe, S.

IEEE Control Systems Letters, 4(1):127-132, January 2020 (article)

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arXiv PDF DOI [BibTex]

arXiv PDF DOI [BibTex]


Self-supervised motion deblurring
Self-supervised motion deblurring

Liu, P., Janai, J., Pollefeys, M., Sattler, T., Geiger, A.

IEEE Robotics and Automation Letters, 2020 (article)

Abstract
Motion blurry images challenge many computer vision algorithms, e.g., feature detection, motion estimation, or object recognition. Deep convolutional neural networks are state-of-the-art for image deblurring. However, obtaining training data with corresponding sharp and blurry image pairs can be difficult. In this paper, we present a differentiable reblur model for self-supervised motion deblurring, which enables the network to learn from real-world blurry image sequences without relying on sharp images for supervision. Our key insight is that motion cues obtained from consecutive images yield sufficient information to inform the deblurring task. We therefore formulate deblurring as an inverse rendering problem, taking into account the physical image formation process: we first predict two deblurred images from which we estimate the corresponding optical flow. Using these predictions, we re-render the blurred images and minimize the difference with respect to the original blurry inputs. We use both synthetic and real dataset for experimental evaluations. Our experiments demonstrate that self-supervised single image deblurring is really feasible and leads to visually compelling results.

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pdf Project Page Blog [BibTex]

pdf Project Page Blog [BibTex]


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Axisymmetric spheroidal squirmers and self-diffusiophoretic particles

Pöhnl, R., Popescu, M. N., Uspal, W. E.

Journal of Physics: Condensed Matter, 32(16), IOP Publishing, Bristol, 2020 (article)

icm

DOI [BibTex]

DOI [BibTex]


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Tracer diffusion on a crowded random Manhattan lattice

Mej\’\ia-Monasterio, C., Nechaev, S., Oshanin, G., Vasilyev, O.

New Journal of Physics, 22(3), IOP Publishing, Bristol, 2020 (article)

icm

DOI [BibTex]

DOI [BibTex]


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Wetting transitions on soft substrates

Napiorkowski, M., Schimmele, L., Dietrich, S.

{EPL}, 129(1), EDP Science, Les-Ulis, 2020 (article)

icm

DOI [BibTex]

DOI [BibTex]


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Blessing and Curse: How a Supercapacitor Large Capacitance Causes its Slow Charging

Lian, C., Janssen, M., Liu, H., van Roij, R.

Physical Review Letters, 124(7), American Physical Society, Woodbury, N.Y., 2020 (article)

icm

DOI [BibTex]

DOI [BibTex]


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Interplay of quenching temperature and drift in Brownian dynamics

Khalilian, H., Nejad, M. R., Moghaddam, A. G., Rohwer, C. M.

EPL, 128(6), EDP Science, Les-Ulis, 2020 (article)

icm

DOI [BibTex]

DOI [BibTex]


Learning Neural Light Transport
Learning Neural Light Transport

Sanzenbacher, P., Mescheder, L., Geiger, A.

Arxiv, 2020 (article)

Abstract
In recent years, deep generative models have gained significance due to their ability to synthesize natural-looking images with applications ranging from virtual reality to data augmentation for training computer vision models. While existing models are able to faithfully learn the image distribution of the training set, they often lack controllability as they operate in 2D pixel space and do not model the physical image formation process. In this work, we investigate the importance of 3D reasoning for photorealistic rendering. We present an approach for learning light transport in static and dynamic 3D scenes using a neural network with the goal of predicting photorealistic images. In contrast to existing approaches that operate in the 2D image domain, our approach reasons in both 3D and 2D space, thus enabling global illumination effects and manipulation of 3D scene geometry. Experimentally, we find that our model is able to produce photorealistic renderings of static and dynamic scenes. Moreover, it compares favorably to baselines which combine path tracing and image denoising at the same computational budget.

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arxiv [BibTex]


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Fractal-seaweeds type functionalization of graphene

Amsharov, K., Sharapa, D. I., Vasilyev, O. A., Martin, O., Hauke, F., Görling, A., Soni, H., Hirsch, A.

Carbon, 158, pages: 435-448, Elsevier, Amsterdam, 2020 (article)

icm

DOI [BibTex]

DOI [BibTex]


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Effective pair interaction of patchy particles in critical fluids

Farahmand Bafi, N., Nowakowski, P., Dietrich, S.

The Journal of Chemical Physics, 152(11), American Institute of Physics, Woodbury, N.Y., 2020 (article)

icm

DOI [BibTex]

DOI [BibTex]


HOTA: A Higher Order Metric for Evaluating Multi-Object Tracking
HOTA: A Higher Order Metric for Evaluating Multi-Object Tracking

Luiten, J., Osep, A., Dendorfer, P., Torr, P., Geiger, A., Leal-Taixe, L., Leibe, B.

International Journal of Computer Vision (IJCV), 2020 (article)

Abstract
Multi-Object Tracking (MOT) has been notoriously difficult to evaluate. Previous metrics overemphasize the importance of either detection or association. To address this, we present a novel MOT evaluation metric, HOTA (Higher Order Tracking Accuracy), which explicitly balances the effect of performing accurate detection, association and localization into a single unified metric for comparing trackers. HOTA decomposes into a family of sub-metrics which are able to evaluate each of five basic error types separately, which enables clear analysis of tracking performance. We evaluate the effectiveness of HOTA on the MOTChallenge benchmark, and show that it is able to capture important aspects of MOT performance not previously taken into account by established metrics. Furthermore, we show HOTA scores better align with human visual evaluation of tracking performance.

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pdf [BibTex]

pdf [BibTex]


Wireless Control for Smart Manufacturing: Recent Approaches and Open Challenges
Wireless Control for Smart Manufacturing: Recent Approaches and Open Challenges

Baumann, D., Mager, F., Wetzker, U., Thiele, L., Zimmerling, M., Trimpe, S.

Proceedings of the IEEE, 2020 (article) To be published

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arXiv DOI [BibTex]

arXiv DOI [BibTex]


Spatial Scheduling of Informative Meetings for Multi-Agent Persistent Coverage
Spatial Scheduling of Informative Meetings for Multi-Agent Persistent Coverage

Haksar, R. N., Trimpe, S., Schwager, M.

IEEE Robotics and Automation Letters, 2020 (article) Accepted

ics

DOI [BibTex]

DOI [BibTex]


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Cassie-Wenzel transition of a binary liquid mixture on a nanosculptured surface

Singh, S. L., Schimmele, L., Dietrich, S.

Physical Review E, 101(5), American Physical Society, Melville, NY, 2020 (article)

icm

DOI [BibTex]

DOI [BibTex]


Safe and Fast Tracking on a Robot Manipulator: Robust MPC and Neural Network Control
Safe and Fast Tracking on a Robot Manipulator: Robust MPC and Neural Network Control

Nubert, J., Koehler, J., Berenz, V., Allgower, F., Trimpe, S.

IEEE Robotics and Automation Letters, 2020 (article) Accepted

Abstract
Fast feedback control and safety guarantees are essential in modern robotics. We present an approach that achieves both by combining novel robust model predictive control (MPC) with function approximation via (deep) neural networks (NNs). The result is a new approach for complex tasks with nonlinear, uncertain, and constrained dynamics as are common in robotics. Specifically, we leverage recent results in MPC research to propose a new robust setpoint tracking MPC algorithm, which achieves reliable and safe tracking of a dynamic setpoint while guaranteeing stability and constraint satisfaction. The presented robust MPC scheme constitutes a one-layer approach that unifies the often separated planning and control layers, by directly computing the control command based on a reference and possibly obstacle positions. As a separate contribution, we show how the computation time of the MPC can be drastically reduced by approximating the MPC law with a NN controller. The NN is trained and validated from offline samples of the MPC, yielding statistical guarantees, and used in lieu thereof at run time. Our experiments on a state-of-the-art robot manipulator are the first to show that both the proposed robust and approximate MPC schemes scale to real-world robotic systems.

am ics

arXiv PDF DOI [BibTex]

arXiv PDF DOI [BibTex]


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Energy storage in steady states under cyclic local energy input

Zhang, Y., Holyst, R., Maciolek, A.

Physical Review E, 101(1), American Physical Society, Melville, NY, 2020 (article)

icm

DOI [BibTex]

DOI [BibTex]


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Numerical simulations of self-diffusiophoretic colloids at fluid interfaces

Peter, T., Malgaretti, P., Rivas, N., Scagliarini, A., Harting, J., Dietrich, S.

Soft Matter, 16(14):3536-3547, Royal Society of Chemistry, Cambridge, UK, 2020 (article)

icm

DOI [BibTex]

DOI [BibTex]


Event-triggered Learning for Linear Quadratic Control
Event-triggered Learning for Linear Quadratic Control

Schlüter, H., Solowjow, F., Trimpe, S.

IEEE Transactions on Automatic Control, 2020 (article) Accepted

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arXiv [BibTex]

arXiv [BibTex]

2012


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Structure and aggregation of colloids immersed in critical solvents

Mohry, T. F., Maciolek, A., Dietrich, S.

Journal of Chemical Physics, 136(22), 2012 (article)

icm

DOI [BibTex]

2012


DOI [BibTex]


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Ewald sum for hydrodynamic interactions with periodicity in two dimensions

Bleibel, J.

Journal of Physics A: Mathematical and Theoretical, 45(22), 2012 (article)

icm

DOI [BibTex]

DOI [BibTex]


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Patchy worm-like micelles: solution structure studied by small-angle neutron scattering

Rosenfeldt, S., Luedel, F., Schulreich, C., Hellweg, T., Radulescu, A., Schmelz, J., Schmalz, H., Harnau, L.

Physical Chemistry Chemical Physics, 14, pages: 12750-12756, 2012 (article)

icm

DOI [BibTex]

DOI [BibTex]


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Time correlations and persistence probability of a Brownian particle in a shear flow

Chakraborty, D.

European Physical Journal B, 85(8), Springer-Verlag Heidelberg, Heidelberg, 2012 (article)

icm

DOI [BibTex]

DOI [BibTex]


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Local theory for ions in binary liquid mixtures

Bier, M., Gambassi, A., Dietrich, S.

The Journal of Chemical Physics, 137(3), American Institute of Physics, Woodbury, N.Y., 2012 (article)

icm

DOI [BibTex]

DOI [BibTex]


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Effect of ions on confined near-critical binary aqueous mixture

Pousaneh, F., Ciach, A., Maciolek, A.

Soft Matter, 8(29):7567-7581, 2012 (article)

icm

DOI [BibTex]

DOI [BibTex]


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Surface integration approach: a new technique for evaluating geometry dependent forces between objects of various geometry and a plate

Dantchev, D., Valchev, G.

Journal of Colloid and Interface Science, 372(1):148-163, 2012 (article)

icm

DOI [BibTex]

DOI [BibTex]


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Stability of thin wetting films on chemically nanostructured surfaces

Checco, A., Ocko, B. M., Tasinkevych, M., Dietrich, S.

Physical Review Letters, 109(16), American Physical Society., Woodbury, N.Y., etc., 2012 (article)

icm

DOI [BibTex]

DOI [BibTex]


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The structure of fluids with impurities

Bier, M., Harnau, L.

Zeitschrift f\"ur physikalische Chemie, 226(7-8):807-814, Akademische Verlagsgesellschaft, Frankfurt am Main, 2012 (article)

icm

DOI [BibTex]

DOI [BibTex]


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Stepwise swelling of a thin film of lamellae-forming poly(styrene-b-butadiene) in cyclohexane vapor

Di, Zhenyu, Posselt, Dorthe, Smilgies, Detlef-M., Li, Ruipeng, Rauscher, Markus, Potemkin, Igor I., Papadakis, Christine M.

Macromolecules, 45(12):5185-5195, 2012 (article)

icm

link (url) DOI [BibTex]

link (url) DOI [BibTex]


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A close look at proteins: submolecular resolution of two- and three-dimensionally folded cytochrome c at surfaces

Deng, Z., Thontasen, N., Malinowski, N., Rinke, G., Harnau, L., Rauschenbach, S., Kern, K.

Nano Letters, 12, pages: 2452-2458, 2012 (article)

icm

DOI [BibTex]

DOI [BibTex]


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Field-induced breakup of emulsion droplets stabilized by colloidal particles

Kim, E. G., Stratford, K., Clegg, P. S., Cates, M. E.

Physical Review E, 85(2), 2012 (article)

icm

DOI [BibTex]

DOI [BibTex]


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Precursor films in wetting phenomena

Popescu, M. N., Oshanin, G., Dietrich, S., Cazabat, A. M.

Journal of Physics: Condensed Matter, 24, 2012 (article)

icm

DOI [BibTex]

DOI [BibTex]


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First passages in bounded domains: When is the mean first passage time meaningful?

Mattos, Thiago G., Mejia-Monasterio, Carlos, Metzler, Ralf, Oshanin, Gleb

Physical Review E, 86(3), Published by the American Physical Society through the American Institute of Physics, Melville, NY, 2012 (article)

icm

DOI [BibTex]

DOI [BibTex]


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Gelation, phase behavior, and dynamics of beta-lactoglobulin amyloid fibrils at varying concentrations and ionic strengths

Bolisetty, S., Harnau, L., Jung, J., Mezzenga, R.

Biomacromolecules, 13, pages: 3241-3252, 2012 (article)

icm

DOI [BibTex]

DOI [BibTex]


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Interactions of distinct quadrupolar nematic colloids

Eskandari, Z., Silvestre, N. M., Tasinkevych, M., Telo da Gama, M. M.

Soft Matter, 8(39):10100-10106, Royal Society of Chemistry, Cambridge, UK, 2012 (article)

icm

DOI [BibTex]

DOI [BibTex]


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Transport of cargo by catalytic Janus micro-motors

Baraban, L., Tasinkevych, M., Popescu, M. N., Sanchez, S., Dietrich, S., Schmidt, O. G.

Soft Matter, 8(1):48-52, 2012 (article)

icm

DOI [BibTex]

DOI [BibTex]


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Mesoscopic analysis of Gibbs’criterion for sessile nanodroplets on trapezoidal substrates

Dutka, F., Napiorkowski, M., Dietrich, S.

Journal of Chemical Physics, 136(6), 2012 (article)

icm

DOI [BibTex]

DOI [BibTex]


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Complete wetting of elastically responsive substrates

Bernardino, N. R., Dietrich, S.

Physical Review E, 85(5), 2012 (article)

icm

DOI [BibTex]

DOI [BibTex]


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GPU-accelerated simulation of colloidal suspensions with direct hydrodynamic interactions

Kopp, M., Höfling, F.

The European Physical Journal - Special Topics, 210(1):101-117, 2012 (article)

icm

DOI [BibTex]

DOI [BibTex]


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Liquid crystal boojum-colloids

Tasinkevych, M., Silvestre, N. M., da Gama, M. M. Telo

New Journal of Physics, 14, Institute of Physics Pub., Bristol, UK, 2012 (article)

icm

DOI [BibTex]

DOI [BibTex]


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Crystalline inverted membrane grown on surfaces by electrospray ion beam deposition in vacuum

Rauschenbach, S., Rinke, G., Malinowski, N., Weitz, R., Dinnebier, R., Thontasen, N., Deng, Z., Lutz, T., Rollo, P., Costantini, G., Harnau, L., Kern, K.

Advanced Materials, 24, pages: 2761-2767, 2012 (article)

icm

DOI [BibTex]

DOI [BibTex]

2011


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Collective dynamics of colloids at fluid interfaces

Bleibel, J., Dominguez, A., Oettel, M., Dietrich, S.

European Physical Journal E, 34(11), 2011 (article)

icm

DOI [BibTex]

2011


DOI [BibTex]