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2019


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A Design Tool for Therapeutic Social-Physical Human-Robot Interactions

Mohan, M., Kuchenbecker, K. J.

Workshop paper (3 pages) presented at the HRI Pioneers Workshop, Daegu, South Korea, March 2019 (misc)

Abstract
We live in an aging society; social-physical human-robot interaction has the potential to keep our elderly adults healthy by motivating them to exercise. After summarizing prior work, this paper proposes a tool that can be used to design exercise and therapy interactions to be performed by an upper-body humanoid robot. The interaction design tool comprises a teleoperation system that transmits the operator’s arm motions, head motions and facial expression along with an interface to monitor and assess the motion of the user interacting with the robot. We plan to use this platform to create dynamic and intuitive exercise interactions.

hi

DOI Project Page [BibTex]

2019


DOI Project Page [BibTex]


Chemical Nanomotors at the Gram Scale Form a Dense Active Optorheological Medium
Chemical Nanomotors at the Gram Scale Form a Dense Active Optorheological Medium

Choudhury, U., Singh, D. P., Qiu, T., Fischer, P.

Adv. Mat., (1807382), Febuary 2019 (article)

Abstract
The rheological properties of a colloidal suspension are a function of the concentration of the colloids and their interactions. While suspensions of passive colloids are well studied and have been shown to form crystals, gels, and glasses, examples of energy‐consuming “active” colloidal suspensions are still largely unexplored. Active suspensions of biological matter, such as motile bacteria or dense mixtures of active actin–motor–protein mixtures have, respectively, reveals superfluid‐like and gel‐like states. Attractive inanimate systems for active matter are chemically self‐propelled particles. It has so far been challenging to use these swimming particles at high enough densities to affect the bulk material properties of the suspension. Here, it is shown that light‐triggered asymmetric titanium dioxide that self‐propel, can be obtained in large quantities, and self‐organize to make a gram‐scale active medium. The suspension shows an activity‐dependent tenfold reversible change in its bulk viscosity.

pf

link (url) DOI [BibTex]


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Resource-rational analysis: Understanding human cognition as the optimal use of limited computational resources

Lieder, F., Griffiths, T. L.

Behavioral and Brain Sciences, 43, E1, Febuary 2019 (article)

Abstract
Modeling human cognition is challenging because there are infinitely many mechanisms that can generate any given observation. Some researchers address this by constraining the hypothesis space through assumptions about what the human mind can and cannot do, while others constrain it through principles of rationality and adaptation. Recent work in economics, psychology, neuroscience, and linguistics has begun to integrate both approaches by augmenting rational models with cognitive constraints, incorporating rational principles into cognitive architectures, and applying optimality principles to understanding neural representations. We identify the rational use of limited resources as a unifying principle underlying these diverse approaches, expressing it in a new cognitive modeling paradigm called resource-rational analysis. The integration of rational principles with realistic cognitive constraints makes resource-rational analysis a promising framework for reverse-engineering cognitive mechanisms and representations. It has already shed new light on the debate about human rationality and can be leveraged to revisit classic questions of cognitive psychology within a principled computational framework. We demonstrate that resource-rational models can reconcile the mind's most impressive cognitive skills with people's ostensive irrationality. Resource-rational analysis also provides a new way to connect psychological theory more deeply with artificial intelligence, economics, neuroscience, and linguistics.

re

DOI [BibTex]

DOI [BibTex]


Fast and Resource-Efficient Control of Wireless Cyber-Physical Systems
Fast and Resource-Efficient Control of Wireless Cyber-Physical Systems

Baumann, D.

KTH Royal Institute of Technology, Stockholm, Febuary 2019 (phdthesis)

ics

PDF [BibTex]

PDF [BibTex]


 Perceptual Effects of Inconsistency in Human Animations
Perceptual Effects of Inconsistency in Human Animations

Kenny, S., Mahmood, N., Honda, C., Black, M. J., Troje, N. F.

ACM Trans. Appl. Percept., 16(1):2:1-2:18, Febuary 2019 (article)

Abstract
The individual shape of the human body, including the geometry of its articulated structure and the distribution of weight over that structure, influences the kinematics of a person’s movements. How sensitive is the visual system to inconsistencies between shape and motion introduced by retargeting motion from one person onto the shape of another? We used optical motion capture to record five pairs of male performers with large differences in body weight, while they pushed, lifted, and threw objects. From these data, we estimated both the kinematics of the actions as well as the performer’s individual body shape. To obtain consistent and inconsistent stimuli, we created animated avatars by combining the shape and motion estimates from either a single performer or from different performers. Using these stimuli we conducted three experiments in an immersive virtual reality environment. First, a group of participants detected which of two stimuli was inconsistent. Performance was very low, and results were only marginally significant. Next, a second group of participants rated perceived attractiveness, eeriness, and humanness of consistent and inconsistent stimuli, but these judgements of animation characteristics were not affected by consistency of the stimuli. Finally, a third group of participants rated properties of the objects rather than of the performers. Here, we found strong influences of shape-motion inconsistency on perceived weight and thrown distance of objects. This suggests that the visual system relies on its knowledge of shape and motion and that these components are assimilated into an altered perception of the action outcome. We propose that the visual system attempts to resist inconsistent interpretations of human animations. Actions involving object manipulations present an opportunity for the visual system to reinterpret the introduced inconsistencies as a change in the dynamics of an object rather than as an unexpected combination of body shape and body motion.

ps

publisher pdf DOI [BibTex]

publisher pdf DOI [BibTex]


First Observation of Optical Activity in Hyper-Rayleigh Scattering
First Observation of Optical Activity in Hyper-Rayleigh Scattering

Collins, J., Rusimova, K., Hooper, D., Jeong, H. H., Ohnoutek, L., Pradaux-Caggiano, F., Verbiest, T., Carbery, D., Fischer, P., Valev, V.

Phys. Rev. X, 9(011024), January 2019 (article)

Abstract
Chiral nano- or metamaterials and surfaces enable striking photonic properties, such as negative refractive index and superchiral light, driving promising applications in novel optical components, nanorobotics, and enhanced chiral molecular interactions with light. In characterizing chirality, although nonlinear chiroptical techniques are typically much more sensitive than their linear optical counterparts, separating true chirality from anisotropy is a major challenge. Here, we report the first observation of optical activity in second-harmonic hyper-Rayleigh scattering (HRS). We demonstrate the effect in a 3D isotropic suspension of Ag nanohelices in water. The effect is 5 orders of magnitude stronger than linear optical activity and is well pronounced above the multiphoton luminescence background. Because of its sensitivity, isotropic environment, and straightforward experimental geometry, HRS optical activity constitutes a fundamental experimental breakthrough in chiral photonics for media including nanomaterials, metamaterials, and chemical molecules.

pf

link (url) DOI [BibTex]

link (url) DOI [BibTex]


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Automatic Bayesian Density Analysis

Vergari, A., Molina, A., Peharz, R., Ghahramani, Z., Kersting, K., Valera, I.

Proceedings of the AAAI Conference on Artificial Intelligence (AAAI-19), 33:01, pages: 5207-5215, AAAI.org, AAAI-19, January 2019 (conference)

ei

arXiv DOI [BibTex]

arXiv DOI [BibTex]


Perceiving Systems (2016-2018)
Perceiving Systems (2016-2018)
Scientific Advisory Board Report, 2019 (misc)

ps

pdf [BibTex]

pdf [BibTex]


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Extracting the dynamic magnetic contrast in time-resolved X-ray transmission microscopy

Schaffers, T., Feggeler, T., Pile, S., Meckenstock, R., Buchner, M., Spoddig, D., Ney, V., Farle, M., Wende, H., Wintz, S., Weigand, M., Ohldag, H., Ollefs, K, Ney, A.

{Nanomaterials}, 9(7), MDPI, Basel, Schweiz, 2019 (article)

mms

DOI [BibTex]

DOI [BibTex]


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Generation of switchable singular beams with dynamic metasurfaces

Yu, P., Li, J., Li, X., Schütz, G., Hirscher, M., Zhang, S., Liu, N.

{ACS Nano}, 13(6):7100-7106, American Chemical Society, Washington, DC, 2019 (article)

mms

DOI [BibTex]

DOI [BibTex]


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A 32-channel multi-coil setup optimized for human brain shimming at 9.4T

Aghaeifar, A., Zhou, J., Heule, R., Tabibian, B., Schölkopf, B., Jia, F., Zaitsev, M., Scheffler, K.

Magnetic Resonance in Medicine, 2019, (Early View) (article)

ei

DOI [BibTex]

DOI [BibTex]


Multidimensional Contrast Limited Adaptive Histogram Equalization
Multidimensional Contrast Limited Adaptive Histogram Equalization

Stimper, V., Bauer, S., Ernstorfer, R., Schölkopf, B., Xian, R. P.

IEEE Access, 7, pages: 165437-165447, 2019 (article)

ei

arXiv link (url) DOI [BibTex]

arXiv link (url) DOI [BibTex]


Tailored Magnetic Springs for Shape-Memory Alloy Actuated Mechanisms in Miniature Robots
Tailored Magnetic Springs for Shape-Memory Alloy Actuated Mechanisms in Miniature Robots

Woodward, M. A., Sitti, M.

IEEE Transactions on Robotics, 35, 2019 (article)

Abstract
Animals can incorporate large numbers of actuators because of the characteristics of muscles; whereas, robots cannot, as typical motors tend to be large, heavy, and inefficient. However, shape-memory alloys (SMA), materials that contract during heating because of change in their crystal structure, provide another option. SMA, though, is unidirectional and therefore requires an additional force to reset (extend) the actuator, which is typically provided by springs or antagonistic actuation. These strategies, however, tend to limit the actuator's work output and functionality as their force-displacement relationships typically produce increasing resistive force with limited variability. In contrast, magnetic springs-composed of permanent magnets, where the interaction force between magnets mimics a spring force-have much more variable force-displacement relationships and scale well with SMA. However, as of yet, no method for designing magnetic springs for SMA-actuators has been demonstrated. Therefore, in this paper, we present a new methodology to tailor magnetic springs to the characteristics of these actuators, with experimental results both for the device and robot-integrated SMA-actuators. We found magnetic building blocks, based on sets of permanent magnets, which are well-suited to SMAs and have the potential to incorporate features such as holding force, state transitioning, friction minimization, auto-alignment, and self-mounting. We show magnetic springs that vary by more than 3 N in 750 $\mu$m and two SMA-actuated devices that allow the MultiMo-Bat to reach heights of up to 4.5 m without, and 3.6 m with, integrated gliding airfoils. Our results demonstrate the potential of this methodology to add previously impossible functionality to smart material actuators. We anticipate this methodology will inspire broader consideration of the use of magnetic springs in miniature robots and further study of the potential of tailored magnetic springs throughout mechanical systems.

pi

DOI [BibTex]


Thrust and Hydrodynamic Efficiency of the Bundled Flagella
Thrust and Hydrodynamic Efficiency of the Bundled Flagella

Danis, U., Rasooli, R., Chen, C., Dur, O., Sitti, M., Pekkan, K.

Micromachines, 10, 2019 (article)

pi

[BibTex]

[BibTex]


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Piezo-electrical control of gyration dynamics of magnetic vortices

Filianina, M., Baldrati, L., Hajiri, T., Litzius, K., Foerster, M., Aballe, L., Kläui, M.

{Applied Physics Letters}, 115(6), American Institute of Physics, Melville, NY, 2019 (article)

mms

DOI [BibTex]

DOI [BibTex]


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Control What You Can: Intrinsically Motivated Task-Planning Agent

Blaes, S., Vlastelica, M., Zhu, J., Martius, G.

In Advances in Neural Information Processing (NeurIPS’19), pages: 12520-12531, Curran Associates, Inc., NeurIPS'19, 2019 (inproceedings)

Abstract
We present a novel intrinsically motivated agent that learns how to control the environment in the fastest possible manner by optimizing learning progress. It learns what can be controlled, how to allocate time and attention, and the relations between objects using surprise based motivation. The effectiveness of our method is demonstrated in a synthetic as well as a robotic manipulation environment yielding considerably improved performance and smaller sample complexity. In a nutshell, our work combines several task-level planning agent structures (backtracking search on task graph, probabilistic road-maps, allocation of search efforts) with intrinsic motivation to achieve learning from scratch.

al

link (url) Project Page [BibTex]

link (url) Project Page [BibTex]


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Barely porous organic cages for hydrogen isotrope separation

Liu, M., Zhang, L., Little, M. A., Kapil, V., Ceriotti, M., Yang, S., Ding, L., Holden, D. L., Balderas-Xicohténcatl, R., He, D., Clowes, R., Chong, S. Y., Schütz, G., Chen, L., Hirscher, M., Cooper, A. I.

{Science}, 366(6465):613-620, American Association for the Advancement of Science, Washington, D.C., 2019 (article)

mms

DOI [BibTex]

DOI [BibTex]


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Magnetically induced anisotropy of flux penetration into strong-pinning superconductor/ferromagnet bilayers

Simmendinger, J., Hänisch, J., Bihler, M., Ionescu, A. M., Weigand, M., Sieger, M., Hühne, R., Rijckaert, H., van Driessche, I., Schütz, G., Albrecht, J.

{New Journal of Physics}, 21, IOP Publishing, Bristol, 2019 (article)

mms

DOI [BibTex]

DOI [BibTex]


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X-ray microscopic characterization of high-Tc-supercoductors using image processing

Bihler, M.

Universität Stuttgart, Stuttgart, 2019 (mastersthesis)

mms

[BibTex]


Microrobotics and Microorganisms: Biohybrid Autonomous Cellular Robots
Microrobotics and Microorganisms: Biohybrid Autonomous Cellular Robots

Alapan, Y., Yasa, O., Yigit, B., Yasa, I. C., Erkoc, P., Sitti, M.

Annual Review of Control, Robotics, and Autonomous Systems, 2019 (article)

pi

[BibTex]

[BibTex]


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X-ray Optics Fabrication Using Unorthodox Approaches

Sanli, U., Baluktsian, M., Ceylan, H., Sitti, M., Weigand, M., Schütz, G., Keskinbora, K.

Bulletin of the American Physical Society, APS, 2019 (article)

mms pi

[BibTex]

[BibTex]


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Learning Transferable Representations

Rojas-Carulla, M.

University of Cambridge, UK, 2019 (phdthesis)

ei

[BibTex]

[BibTex]


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Sample-efficient deep reinforcement learning for continuous control

Gu, S.

University of Cambridge, UK, 2019 (phdthesis)

ei

[BibTex]


{Direct observation of coherent magnons with suboptical wavelengths in a single-crystalline ferrimagnetic insulator}
Direct observation of coherent magnons with suboptical wavelengths in a single-crystalline ferrimagnetic insulator

Förster, J., Gräfe, J., Bailey, J., Finizio, S., Träger, N., Groß, F., Mayr, S., Stoll, H., Dubs, C., Surzhenko, O., Liebing, N., Woltersdorf, G., Raabe, J., Weigand, M., Schütz, G., Wintz, S.

{Physical Review B}, 100(21), American Physical Society, Woodbury, NY, 2019 (article)

Abstract
Spin-wave dynamics were studied in an extended thin film of single-crystalline yttrium iron garnet using time-resolved scanning transmission x-ray microscopy. A combination of mechanical grinding and focused ion beam milling has been utilized to achieve a soft x-ray transparent thickness of the underlying bulk gadolinium gallium garnet substrate. Damon-Eshbach type spin waves down to about 100 nm wavelength have been directly imaged in real space for varying frequencies and external magnetic fields. The dispersion relation extracted from the experimental data agreed well with theoretical predictions. A significant influence of the ion milling process on the local magnetic properties was not detected.

mms

DOI [BibTex]

DOI [BibTex]


{Nanoscale detection of spin wave deflection angles in permalloy}
Nanoscale detection of spin wave deflection angles in permalloy

Gross, F., Träger, N., Förster, J., Weigand, M., Schütz, G., Gräfe, J.

{Applied Physics Letters}, 114(1), American Institute of Physics, Melville, NY, 2019 (article)

Abstract
Magnonics is a potential candidate for beyond CMOS and neuromorphic computing technologies with advanced phase encoded logic. However, nanoscale imaging of spin waves with full phase and magnetization amplitude information is a challenge. We show a generalized scanning transmission x-ray microscopy platform to get a complete understanding of spin waves, including the k-vector, phase, and absolute magnetization deflection angle. As an example, this is demonstrated using a 50 nm thin permalloy film where we find a maximum deflection angle of 1.5° and good agreement with the k-vector dispersion previously reported in the literature. With a spatial resolution approximately ten times better than any other methods for spin wave imaging, x-ray microscopy opens a vast range of possibilities for the observation of spin waves and various magnetic structures.

mms

DOI [BibTex]

DOI [BibTex]


{gFORC: A graphics processing unit accelerated first-order reversal-curve calculator}
gFORC: A graphics processing unit accelerated first-order reversal-curve calculator

Groß, F., Martínez-García, J. C., Ilse, S. E., Schütz, G., Goering, E., Rivas, M., Gräfe, J.

{Journal of Applied Physics}, 126(16), AIP Publishing, New York, NY, 2019 (article)

Abstract
First-order reversal-curves have proven to be an indispensable characterization tool for physics as well as for geology. However, the conventional evaluation algorithm requires a lot of computational effort for a comparable easy task to overcome measurement noise. In this work, we present a new evaluation approach, which exploits the diversity of Fourier space to not only speed up the calculation by a factor of 1000 but also move away from the conventional smoothing factor toward real field resolution. By comparing the baseline resolution of the new and the old algorithm, we are able to deduce an analytical equation that converts the smoothing factor into field resolution, making the old and new algorithm comparable. We find excellent agreement not only for various systems of increasing complexity but also over a large range of smoothing factors. The achieved speedup enables us to calculate a large number of first-order reversal-curve diagrams with increasing smoothing factor allowing for an autocorrelation approach to find a hard criterion for the optimum smoothing factor. This previously computational prohibitive evaluation of first-order reversal-curves solves the problem of over- and undersmoothing by increasing general readability and preventing information destruction.

mms

DOI [BibTex]

DOI [BibTex]


Max Planck Institute for Intelligent Systems - Highlights
Max Planck Institute for Intelligent Systems - Highlights
2019 (mpi_year_book)

Abstract
In the future, artificially intelligent systems will substantially change the way we live, work, and communicate. Intelligent systems will become increasingly important in all spheres of life – as virtual systems on the Internet, or as cyber-physical systems in the real world. Artificial intelligence (AI) will be used for autonomous driving, as well as to diagnose and fight diseases, or to carry out emergency operations that are too dangerous for humans. This is just the beginning.

MPI IS Yearbook 2019 (en) MPI IS Jahresbericht 2019 (de) [BibTex]


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Response of active Brownian particles to shear flow

Asheichyk, K., Solon, A., Rohwer, C. M., Krüger, M.

The Journal of Chemical Physics, 150(14), American Institute of Physics, Woodbury, N.Y., 2019 (article)

icm

DOI [BibTex]

DOI [BibTex]


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Vortex Mass in the Three-Dimensional O(2) Scalar Theory

Delfino, G., Selke, W., Squarcini, A.

Physical Review Letters, 122(5), American Physical Society, Woodbury, N.Y., 2019 (article)

icm

DOI [BibTex]

DOI [BibTex]


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Ferromagnetic colloids in liquid crystal solvents

Zarubin, G.

Universität Stuttgart, Stuttgart, 2019 (phdthesis)

icm

link (url) DOI [BibTex]

link (url) DOI [BibTex]


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Fluctuating interface with a pinning potential

Pranjić, Daniel

Universität Stuttgart, Stuttgart, 2019 (mastersthesis)

icm

[BibTex]

[BibTex]


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Dynamics near planar walls for various model self-phoretic particles

Bayati, P., Popescu, M. N., Uspal, W. E., Dietrich, S., Najafi, A.

Soft Matter, 15(28):5644-5672, Royal Society of Chemistry, Cambridge, UK, 2019 (article)

icm

DOI [BibTex]

DOI [BibTex]


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Glucose Oxidase Micropumps: Multi-Faceted Effects of Chemical Activity on Tracer Particles Near the Solid-Liquid Interface

Munteanu, R. E., Popescu, M. N., Gáspár, S.

Condensed Matter, 4(3), MDPI, Basel, 2019 (article)

icm

DOI [BibTex]


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Criticality senses topology

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

EPL, 128(2), EDP Science, Les-Ulis, 2019 (article)

icm

DOI [BibTex]

DOI [BibTex]


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Soft Sensors for Curvature Estimation under Water in a Soft Robotic Fish

Wright, Brian, Vogt, Daniel M., Wood, Robert J., Jusufi, Ardian

In 2019 2nd IEEE International Conference on Soft Robotics (RoboSoft 2019), pages: 367-371, IEEE, Piscataway, NJ, 2nd IEEE International Conference on Soft Robotics (RoboSoft 2019), 2019 (inproceedings)

bio

DOI [BibTex]

DOI [BibTex]


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TD-regularized actor-critic methods

Parisi, S., Tangkaratt, V., Peters, J., Khan, M. E.

Machine Learning, 108(8):1467-1501, (Editors: Karsten Borgwardt, Po-Ling Loh, Evimaria Terzi, and Antti Ukkonen), 2019 (article)

ei

DOI [BibTex]

DOI [BibTex]


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A Robustness Analysis of Inverse Optimal Control of Bipedal Walking

Rebula, J. R., Schaal, S., Finley, J., Righetti, L.

IEEE Robotics and Automation Letters, 4(4):4531-4538, 2019 (article)

mg

DOI [BibTex]

DOI [BibTex]


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Statistical Coverage Control of Mobile Sensor Networks

Arslan, Ö.

IEEE Transactions on Robotics, 35(4):889-908, 2019 (article)

am

DOI [BibTex]

DOI [BibTex]


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On the positivity and magnitudes of Bayesian quadrature weights

Karvonen, T., Kanagawa, M., Särkä, S.

Statistics and Computing, 29, pages: 1317-1333, 2019 (article)

pn

DOI [BibTex]

DOI [BibTex]


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Probabilistic solutions to ordinary differential equations as nonlinear Bayesian filtering: a new perspective

Tronarp, F., Kersting, H., Särkkä, S. H. P.

Statistics and Computing, 29(6):1297-1315, 2019 (article)

ei pn

DOI [BibTex]

DOI [BibTex]


Wide Range-Sensitive, Bending-Insensitive Pressure Detection and Application to Wearable Healthcare Device
Wide Range-Sensitive, Bending-Insensitive Pressure Detection and Application to Wearable Healthcare Device

Kim, S., Amjadi, M., Lee, T., Jeong, Y., Kwon, D., Kim, M. S., Kim, K., Kim, T., Oh, Y. S., Park, I.

In 2019 20th International Conference on Solid-State Sensors, Actuators and Microsystems & Eurosensors XXXIII (TRANSDUCERS & EUROSENSORS XXXIII), 2019 (inproceedings)

pi

[BibTex]

[BibTex]


Nitrogen doped carbon quantum dots demonstrate no toxicity under in vitro conditions in a cervical cell line and in vivo in Swiss albino mice
Nitrogen doped carbon quantum dots demonstrate no toxicity under in vitro conditions in a cervical cell line and in vivo in Swiss albino mice

Singh, V., Kashyap, S., Yadav, U., Srivastava, A., Singh, A. V., Singh, R. K., Singh, S. K., Saxena, P. S.

Toxicology research, 8, Oxford University Press, 2019 (article)

pi

DOI [BibTex]

DOI [BibTex]


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Spatial Continuity Effect vs. Spatial Contiguity Failure. Revising the Effects of Spatial Proximity Between Related and Unrelated Representations

Beege, M., Wirzberger, M., Nebel, S., Schneider, S., Schmidt, N., Rey, G. D.

Frontiers in Education, 4:86, 2019 (article)

Abstract
The split-attention effect refers to learning with related representations in multimedia. Spatial proximity and integration of these representations are crucial for learning processes. The influence of varying amounts of proximity between related and unrelated information has not yet been specified. In two experiments (N1 = 98; N2 = 85), spatial proximity between a pictorial presentation and text labels was manipulated (high vs. medium vs. low). Additionally, in experiment 1, a control group with separated picture and text presentation was implemented. The results revealed a significant effect of spatial proximity on learning performance. In contrast to previous studies, the medium condition leads to the highest transfer, and in experiment 2, the highest retention score. These results are interpreted considering cognitive load and instructional efficiency. Findings indicate that transfer efficiency is optimal at a medium distance between representations in experiment 1. Implications regarding the spatial contiguity principle and the spatial contiguity failure are discussed.

re

link (url) DOI [BibTex]


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Spatial Filtering based on Riemannian Manifold for Brain-Computer Interfacing

Xu, J.

Technical University of Munich, Germany, 2019 (mastersthesis)

ei

[BibTex]

[BibTex]


Learning to Control Highly Accelerated Ballistic Movements on Muscular Robots
Learning to Control Highly Accelerated Ballistic Movements on Muscular Robots

Büchler, D., Calandra, R., Peters, J.

2019 (article) Submitted

Abstract
High-speed and high-acceleration movements are inherently hard to control. Applying learning to the control of such motions on anthropomorphic robot arms can improve the accuracy of the control but might damage the system. The inherent exploration of learning approaches can lead to instabilities and the robot reaching joint limits at high speeds. Having hardware that enables safe exploration of high-speed and high-acceleration movements is therefore desirable. To address this issue, we propose to use robots actuated by Pneumatic Artificial Muscles (PAMs). In this paper, we present a four degrees of freedom (DoFs) robot arm that reaches high joint angle accelerations of up to 28000 °/s^2 while avoiding dangerous joint limits thanks to the antagonistic actuation and limits on the air pressure ranges. With this robot arm, we are able to tune control parameters using Bayesian optimization directly on the hardware without additional safety considerations. The achieved tracking performance on a fast trajectory exceeds previous results on comparable PAM-driven robots. We also show that our system can be controlled well on slow trajectories with PID controllers due to careful construction considerations such as minimal bending of cables, lightweight kinematics and minimal contact between PAMs and PAMs with the links. Finally, we propose a novel technique to control the the co-contraction of antagonistic muscle pairs. Experimental results illustrate that choosing the optimal co-contraction level is vital to reach better tracking performance. Through the use of PAM-driven robots and learning, we do a small step towards the future development of robots capable of more human-like motions.

ei

Arxiv Video [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)

mms

DOI [BibTex]

DOI [BibTex]


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AReS and MaRS Adversarial and MMD-Minimizing Regression for SDEs

Abbati*, G., Wenk*, P., Osborne, M. A., Krause, A., Schölkopf, B., Bauer, S.

Proceedings of the 36th International Conference on Machine Learning (ICML), 97, pages: 1-10, Proceedings of Machine Learning Research, (Editors: Chaudhuri, Kamalika and Salakhutdinov, Ruslan), PMLR, 2019, *equal contribution (conference)

ei

PDF link (url) [BibTex]

PDF link (url) [BibTex]