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2017


On the Design of {LQR} Kernels for Efficient Controller Learning
On the Design of LQR Kernels for Efficient Controller Learning

Marco, A., Hennig, P., Schaal, S., Trimpe, S.

Proceedings of the 56th IEEE Annual Conference on Decision and Control (CDC), pages: 5193-5200, IEEE, IEEE Conference on Decision and Control, December 2017 (conference)

Abstract
Finding optimal feedback controllers for nonlinear dynamic systems from data is hard. Recently, Bayesian optimization (BO) has been proposed as a powerful framework for direct controller tuning from experimental trials. For selecting the next query point and finding the global optimum, BO relies on a probabilistic description of the latent objective function, typically a Gaussian process (GP). As is shown herein, GPs with a common kernel choice can, however, lead to poor learning outcomes on standard quadratic control problems. For a first-order system, we construct two kernels that specifically leverage the structure of the well-known Linear Quadratic Regulator (LQR), yet retain the flexibility of Bayesian nonparametric learning. Simulations of uncertain linear and nonlinear systems demonstrate that the LQR kernels yield superior learning performance.

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arXiv PDF On the Design of LQR Kernels for Efficient Controller Learning - CDC presentation DOI Project Page [BibTex]

2017


arXiv PDF On the Design of LQR Kernels for Efficient Controller Learning - CDC presentation DOI Project Page [BibTex]


Optimizing Long-term Predictions for Model-based Policy Search
Optimizing Long-term Predictions for Model-based Policy Search

Doerr, A., Daniel, C., Nguyen-Tuong, D., Marco, A., Schaal, S., Toussaint, M., Trimpe, S.

Proceedings of 1st Annual Conference on Robot Learning (CoRL), 78, pages: 227-238, (Editors: Sergey Levine and Vincent Vanhoucke and Ken Goldberg), 1st Annual Conference on Robot Learning, November 2017 (conference)

Abstract
We propose a novel long-term optimization criterion to improve the robustness of model-based reinforcement learning in real-world scenarios. Learning a dynamics model to derive a solution promises much greater data-efficiency and reusability compared to model-free alternatives. In practice, however, modelbased RL suffers from various imperfections such as noisy input and output data, delays and unmeasured (latent) states. To achieve higher resilience against such effects, we propose to optimize a generative long-term prediction model directly with respect to the likelihood of observed trajectories as opposed to the common approach of optimizing a dynamics model for one-step-ahead predictions. We evaluate the proposed method on several artificial and real-world benchmark problems and compare it to PILCO, a model-based RL framework, in experiments on a manipulation robot. The results show that the proposed method is competitive compared to state-of-the-art model learning methods. In contrast to these more involved models, our model can directly be employed for policy search and outperforms a baseline method in the robot experiment.

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PDF Project Page [BibTex]

PDF Project Page [BibTex]


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Event-based State Estimation: An Emulation-based Approach

Trimpe, S.

IET Control Theory & Applications, 11(11):1684-1693, July 2017 (article)

Abstract
An event-based state estimation approach for reducing communication in a networked control system is proposed. Multiple distributed sensor agents observe a dynamic process and sporadically transmit their measurements to estimator agents over a shared bus network. Local event-triggering protocols ensure that data is transmitted only when necessary to meet a desired estimation accuracy. The event-based design is shown to emulate the performance of a centralised state observer design up to guaranteed bounds, but with reduced communication. The stability results for state estimation are extended to the distributed control system that results when the local estimates are used for feedback control. Results from numerical simulations and hardware experiments illustrate the effectiveness of the proposed approach in reducing network communication.

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arXiv Supplementary material PDF DOI Project Page [BibTex]

arXiv Supplementary material PDF DOI Project Page [BibTex]


Model-Based Policy Search for Automatic Tuning of Multivariate PID Controllers
Model-Based Policy Search for Automatic Tuning of Multivariate PID Controllers

Doerr, A., Nguyen-Tuong, D., Marco, A., Schaal, S., Trimpe, S.

In Proceedings of the IEEE International Conference on Robotics and Automation (ICRA), pages: 5295-5301, IEEE, Piscataway, NJ, USA, IEEE International Conference on Robotics and Automation (ICRA), May 2017 (inproceedings)

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PDF arXiv DOI Project Page [BibTex]

PDF arXiv DOI Project Page [BibTex]


Virtual vs. {R}eal: Trading Off Simulations and Physical Experiments in Reinforcement Learning with {B}ayesian Optimization
Virtual vs. Real: Trading Off Simulations and Physical Experiments in Reinforcement Learning with Bayesian Optimization

Marco, A., Berkenkamp, F., Hennig, P., Schoellig, A. P., Krause, A., Schaal, S., Trimpe, S.

In Proceedings of the IEEE International Conference on Robotics and Automation (ICRA), pages: 1557-1563, IEEE, Piscataway, NJ, USA, IEEE International Conference on Robotics and Automation (ICRA), May 2017 (inproceedings)

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PDF arXiv ICRA 2017 Spotlight presentation Virtual vs. Real - Video explanation DOI Project Page [BibTex]

PDF arXiv ICRA 2017 Spotlight presentation Virtual vs. Real - Video explanation DOI Project Page [BibTex]


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Chemically active colloids near osmotic-responsive walls with surface-chemistry gradients

Popescu, M. N., Uspal, W. E., Dietrich, S.

Journal of Physics: Condensed Matter, 29, IOP Publishing, Bristol, 2017 (article)

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DOI [BibTex]

DOI [BibTex]


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Active colloids in the context of chemical kinetics

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

Journal of Physics A, 50, IOP Pub., Bristol, 2017 (article)

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DOI [BibTex]

DOI [BibTex]


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Microbots Decorated with Silver Nanoparticles Kill Bacteria in Aqueous Media

Vilela, D., Stanton, M. M., Parmar, J., Sánchez, S.

ACS Applied Materials and Interfaces, 9(27):22093-22100, American Chemical Society, Washington, DC, 2017 (article)

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DOI [BibTex]

DOI [BibTex]


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Measurement of second-order response without perturbation

Helden, L., Basu, U., Krüger, M., Bechinger, C.

EPL, 116(6), IOP Publishing, Bristol, 2017 (article)

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DOI [BibTex]

DOI [BibTex]


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Swimming with a cage: low-Reynolds-number locomotion inside a droplet

Reigh, S., Zhu, L. L., Gallaire, F., Lauga, E.

Soft Matter, 13(17):3161-3173, Royal Society of Chemistry, Cambridge, UK, 2017 (article)

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DOI [BibTex]

DOI [BibTex]


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Active Particle Accumulation at Boundaries: A Strategy to Measure Contact Angles

Simmchen, J., Malgaretti, P.

ChemNanoMat, 3(11):790-793, Wiley, Weinheim, 2017 (article)

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DOI [BibTex]

DOI [BibTex]


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Two-fluid model for locomotion under self-confinement

Reigh, S., Lauga, E.

Physical Review Fluids, 2(9), American Physical Society, 2017 (article)

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DOI [BibTex]

DOI [BibTex]


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Bubble gating in biological ion channels: A density functional theory study

Gu\ssmann, Florian, Roth, R.

Physical Review E, 95(6), American Physical Society, Melville, NY, 2017 (article)

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DOI [BibTex]

DOI [BibTex]


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Nematic films at chemically structured surfaces

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

Journal of Physics: Condensed Matter, 29(7), IOP Publishing, Bristol, 2017 (article)

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DOI [BibTex]

DOI [BibTex]


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Nonadditive interactions and phase transitions in strongly confined colloidal systems

Vasilyev, O., Dietrich, S., Kondrat, S.

Soft Matter, 14(4):586-596, Royal Society of Chemistry, Cambridge, UK, 2017 (article)

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DOI [BibTex]

DOI [BibTex]


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Platinum-free cobalt ferrite based micromotors for antibiotic removal

Parmar, J., Villa, K., Vilela, D., Sánchez, S.

Applied Materials Today, 9, pages: 605-611, Elsevier, Amsterdam, 2017 (article)

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DOI [BibTex]

DOI [BibTex]


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Stationary and time-dependent heat transfer in paradigmatic many-body geometries

Asheichyk, Kiryl

Universität Stuttgart, Stuttgart, 2017 (mastersthesis)

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[BibTex]

[BibTex]


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Perils of ad hoc approximations for the activity function of chemically powered colloids

Popescu, M. N., Uspal, W. E., Tasinkevych, M., Dietrich, S.

The European Physical Journal E, 40, EDP Sciences; Società Italiana di Fisica; Springer, Les Ulis; Bologna; Heidelberg, 2017 (article)

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DOI [BibTex]

DOI [BibTex]


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Transient Casimir Forces from Quenches in Thermal and Active Matter

Rohwer, C. M., Kardar, M., Krüger, M.

Physical Review Letters, 118(1), American Physical Society, Woodbury, N.Y., 2017 (article)

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DOI [BibTex]

DOI [BibTex]


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Rotational motion of dimers of Janus particles

Majee, A.

European Physical Journal E, 40(3), Springer, Berlin, 2017 (article)

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DOI [BibTex]

DOI [BibTex]


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Designing Micro- and Nanoswimmers for Specific Applications

Katuri, J., Ma, X., Stanton, M. M., Sanchez, S.

Accounts of Chemical Research, 50(1):2-11, American Chemical Society, Easton, Pa., 2017 (article)

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DOI [BibTex]

DOI [BibTex]


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Wedge wetting by electrolyte solutions

Mußotter, M., Bier, M.

Physical Review E, 96(3), American Physical Society, Melville, NY, 2017 (article)

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DOI [BibTex]

DOI [BibTex]


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Effect of boundaries on vacuum field fluctuations and radiation-mediated interactions between atoms

Armata, F., Butera, S., Fiscelli, G., Incardone, R., Notararigo, V., Palacino, R., Passante, R., Rizzuto, L., Spagnolo, S.

Journal of Physics: Conference Series, 880, IOP Publishing, Bristol, 2017 (article)

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DOI [BibTex]

DOI [BibTex]


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Non-equilibrium forces after temperature quenches in ideal fluids with conserved density

Hölzl, Christian

Universität Stuttgart, Stuttgart, 2017 (mastersthesis)

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[BibTex]

[BibTex]


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Numerical studies of active colloids at fluid interfaces

Peter, Toni

Universität Stuttgart, Stuttgart, 2017 (mastersthesis)

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[BibTex]

[BibTex]


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Smectic phases in ionic liquid crystals

Bartsch, H., Bier, M., Dietrich, S.

Journal of Physics: Condensed Matter, 29(46), IOP Publishing, Bristol, 2017 (article)

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DOI [BibTex]

DOI [BibTex]


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Pushing Bacterial Biohybrids to In Vivo Applications

Stanton, M. M., Sánchez, S.

Trends in Biotechnology, 35(10):910-913, Elsevier Current Trends, Amsterdam, Netherlands, 2017 (article)

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DOI [BibTex]

DOI [BibTex]


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Particles with nonlinear electric response: Suppressing van der Waals forces by an external field

Soo, H., Dean, D. S., Krüger, M.

Physical Review E, 95(1), American Physical Society, Melville, NY, 2017 (article)

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DOI [BibTex]

DOI [BibTex]


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Electrolyte solutions at curved electrodes. I. Mesoscopic approach

Reindl, A., Bier, M., Dietrich, S.

The Journal of Chemical Physics, 146(15), American Institute of Physics, Woodbury, N.Y., 2017 (article)

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DOI [BibTex]

DOI [BibTex]


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Self-propelling micro-nanorobots: challenges and fututre perspectives in nanomedicine

Ma, X., Sánchez, S.

Nanomedicine, 12(12):1363-1367, Future Medicine Ltd, London, UK, 2017 (article)

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DOI [BibTex]

DOI [BibTex]


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Salt-induced microheterogeneities in binary liquid mixtures

Bier, M., Mars, J., Li, H., Mezger, M.

Physical Review E, 96(2), American Physical Society, Melville, NY, 2017 (article)

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DOI [BibTex]

DOI [BibTex]


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Forward-backward multiplicity correlations in proton-proton collisions from several GeV to LHC energies

Bravina, L., Bleibel, J., Emaus, R., Zabrodin, E.

EPJ Web of Conferences, 164, EDP Sciences, Les Ulis, 2017 (article)

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DOI [BibTex]

DOI [BibTex]


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Key-lock colloids in a nematic liquid crystal

Silvestre, N. M., Tasinkevych, M.

Physical Review E, 95(1), American Physical Society, Melville, NY, 2017 (article)

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DOI [BibTex]

DOI [BibTex]


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Collective dynamics of laterally confined active particles near fluid-fluid interfaces

Kistner, Irina

Universität Stuttgart, Stuttgart, 2017 (mastersthesis)

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[BibTex]

[BibTex]


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Fluctuation induced forces in critical films with disorder at their surfaces

Maciolek, A., Vasilyev, O., Dotsenko, V., Dietrich, S.

Journal of Statistical Mechanics: Theory and Experiment, Institute of Physics Publishing, Bristol, England, 2017 (article)

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DOI [BibTex]

DOI [BibTex]


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Action at a distance in classical uniaxial ferromagnetic arrays

Abraham, D. B., Maciolek, A., Squarcini, A., Vasilyev, O.

Physical Review E, 96(4), American Physical Society, Melville, NY, 2017 (article)

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DOI [BibTex]

DOI [BibTex]


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Cooperative behavior of biased probes in crowded interacting systems

Vasilyev, O., Bénichou, O., Mej\’\ia-Monasterio, C., Weeks, E. R., Oshanin, G.

Soft Matter, 13(41):7617-7624, Royal Society of Chemistry, Cambridge, UK, 2017 (article)

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DOI [BibTex]

DOI [BibTex]


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Nonequilibrium Fluctuational Quantum Electrodynamics: Heat Radiation, Heat Transfer, and Force

Bimonte, G., Emig, T., Kardar, M., Krüger, M.

Annual Review of Condensed Matter Physics, 8, pages: 119-143, 2017 (article)

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DOI [BibTex]

DOI [BibTex]


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A Gaussian theory for fluctuations in simple liquids

Krüger, M., Dean, D. S.

The Journal of Chemical Physics, 146(13), American Institute of Physics, Woodbury, N.Y., 2017 (article)

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DOI [BibTex]

DOI [BibTex]


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Critical Casimir interactions between colloids around the critical point of binary solvents

Stuij, S. G., Labbe-Laurent, M., Kodger, T. E., Maciolek, A., Schall, P.

Soft Matter, 13(31):5233-5249, Royal Society of Chemistry, Cambridge, UK, 2017 (article)

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DOI [BibTex]

DOI [BibTex]


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Bio-catalytic mesoporous Janus nano-motors powered by catalase enzyme

Ma, X., Sánchez, S.

Tetrahedron, 73(33):4883-4886, Elsevier Science, Kidlington, 2017 (article)

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DOI [BibTex]

DOI [BibTex]


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Basic features of proton-proton interactions at ultra-relativistic energies and RFT-based quark-gluon string model

Zabrodin, E., Bravina, L., Bleibel, J.

EPJ Web of Conferences, 164, EDP Sciences, Les Ulis, 2017 (article)

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DOI [BibTex]

DOI [BibTex]


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Self-diffusion of DNA grafted functional colloids in a crowded environment

Werner, M.

Universität Stuttgart, Stuttgart, 2017 (mastersthesis)

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[BibTex]

[BibTex]


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The modified Langevin description for probes in a nonlinear medium

Krüger, M., Maes, C.

Journal of Physics: Condensed Matter, 29(6), IOP Publishing, Bristol, 2017 (article)

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DOI [BibTex]

DOI [BibTex]


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Smoluchowski rate for diffusion-controlled reactions of molecules with antenna

Vasilyev, O., Lizana, L., Oshanin, G.

Journal of Physics A, 50(26), IOP Pub., Bristol, 2017 (article)

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DOI [BibTex]

DOI [BibTex]


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Model microswimmers in channels with varying cross section

Malgaretti, P., Stark, H.

The Journal of Chemical Physics, 146(17), American Institute of Physics, Woodbury, N.Y., 2017 (article)

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DOI [BibTex]

DOI [BibTex]


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Electrostatic interaction between non-identical charged particles at an electrolyte interface

Schmetzer, Timo

Universität Stuttgart, Stuttgart, 2017 (mastersthesis)

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[BibTex]

[BibTex]


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Heat radiation and transfer for point particles in arbitrary geometries

Asheichyk, K., Müller, B., Krüger, M.

Physical Review B, 96(15), American Physical Society, Woodbury, NY, 2017 (article)

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DOI [BibTex]

DOI [BibTex]