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2019


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Active Perception based Formation Control for Multiple Aerial Vehicles

Tallamraju, R., Price, E., Ludwig, R., Karlapalem, K., Bülthoff, H. H., Black, M. J., Ahmad, A.

IEEE Robotics and Automation Letters, Robotics and Automation Letters, IEEE, August 2019 (article) Accepted

Abstract
We present a novel robotic front-end for autonomous aerial motion-capture (mocap) in outdoor environments. In previous work, we presented an approach for cooperative detection and tracking (CDT) of a subject using multiple micro-aerial vehicles (MAVs). However, it did not ensure optimal view-point configurations of the MAVs to minimize the uncertainty in the person's cooperatively tracked 3D position estimate. In this article, we introduce an active approach for CDT. In contrast to cooperatively tracking only the 3D positions of the person, the MAVs can actively compute optimal local motion plans, resulting in optimal view-point configurations, which minimize the uncertainty in the tracked estimate. We achieve this by decoupling the goal of active tracking into a quadratic objective and non-convex constraints corresponding to angular configurations of the MAVs w.r.t. the person. We derive this decoupling using Gaussian observation model assumptions within the CDT algorithm. We preserve convexity in optimization by embedding all the non-convex constraints, including those for dynamic obstacle avoidance, as external control inputs in the MPC dynamics. Multiple real robot experiments and comparisons involving 3 MAVs in several challenging scenarios are presented.

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pdf Project Page [BibTex]

2019


pdf Project Page [BibTex]


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Learning and Tracking the 3D Body Shape of Freely Moving Infants from RGB-D sequences

Hesse, N., Pujades, S., Black, M., Arens, M., Hofmann, U., Schroeder, S.

Transactions on Pattern Analysis and Machine Intelligence (TPAMI), 2019 (article)

Abstract
Statistical models of the human body surface are generally learned from thousands of high-quality 3D scans in predefined poses to cover the wide variety of human body shapes and articulations. Acquisition of such data requires expensive equipment, calibration procedures, and is limited to cooperative subjects who can understand and follow instructions, such as adults. We present a method for learning a statistical 3D Skinned Multi-Infant Linear body model (SMIL) from incomplete, low-quality RGB-D sequences of freely moving infants. Quantitative experiments show that SMIL faithfully represents the RGB-D data and properly factorizes the shape and pose of the infants. To demonstrate the applicability of SMIL, we fit the model to RGB-D sequences of freely moving infants and show, with a case study, that our method captures enough motion detail for General Movements Assessment (GMA), a method used in clinical practice for early detection of neurodevelopmental disorders in infants. SMIL provides a new tool for analyzing infant shape and movement and is a step towards an automated system for GMA.

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pdf Journal DOI [BibTex]

pdf Journal DOI [BibTex]


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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.

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publisher pdf DOI [BibTex]

publisher pdf DOI [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)

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[BibTex]

[BibTex]


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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)

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DOI [BibTex]

DOI [BibTex]


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Coherent excitation of heterosymmetric spin waves with ultrashort wavelengths

Dieterle, G., Förster, J., Stoll, H., Semisalova, A. S., Finizio, S., Gangwar, A., Weigand, M., Noske, M., Fähnle, M., Bykova, I., Gräfe, J., Bozhko, D. A., Musiienko-Shmarova, H. Y., Tiberkevich, V., Slavin, A. N., Back, C. H., Raabe, J., Schütz, G., Wintz, S.

{Physical Review Letters}, 122(11), American Physical Society, Woodbury, N.Y., 2019 (article)

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DOI [BibTex]

DOI [BibTex]


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Reprogrammability and Scalability of Magnonic Fibonacci Quasicrystals

Lisiecki, F., Rychły, J., Kuświk, P., Głowiński, H., Kłos, J. W., Groß, F., Bykova, I., Weigand, M., Zelent, M., Goering, E. J., Schütz, G., Gubbiotti, G., Krawczyk, M., Stobiecki, F., Dubowik, J., Gräfe, J.

Physical Review Applied, 11, pages: 054003, 2019 (article)

Abstract
Magnonic crystals are systems that can be used to design and tune the dynamic properties of magnetization. Here, we focus on one-dimensional Fibonacci magnonic quasicrystals. We confirm the existence of collective spin waves propagating through the structure as well as dispersionless modes; the reprogammability of the resonance frequencies, dependent on the magnetization order; and dynamic spin-wave interactions. With the fundamental understanding of these properties, we lay a foundation for the scalable and advanced design of spin-wave band structures for spintronic, microwave, and magnonic applications.

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link (url) DOI [BibTex]

link (url) DOI [BibTex]


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The Virtual Caliper: Rapid Creation of Metrically Accurate Avatars from 3D Measurements

Pujades, S., Mohler, B., Thaler, A., Tesch, J., Mahmood, N., Hesse, N., Bülthoff, H. H., Black, M. J.

IEEE Transactions on Visualization and Computer Graphics, 25, pages: 1887,1897, IEEE, 2019 (article)

Abstract
Creating metrically accurate avatars is important for many applications such as virtual clothing try-on, ergonomics, medicine, immersive social media, telepresence, and gaming. Creating avatars that precisely represent a particular individual is challenging however, due to the need for expensive 3D scanners, privacy issues with photographs or videos, and difficulty in making accurate tailoring measurements. We overcome these challenges by creating “The Virtual Caliper”, which uses VR game controllers to make simple measurements. First, we establish what body measurements users can reliably make on their own body. We find several distance measurements to be good candidates and then verify that these are linearly related to 3D body shape as represented by the SMPL body model. The Virtual Caliper enables novice users to accurately measure themselves and create an avatar with their own body shape. We evaluate the metric accuracy relative to ground truth 3D body scan data, compare the method quantitatively to other avatar creation tools, and perform extensive perceptual studies. We also provide a software application to the community that enables novices to rapidly create avatars in fewer than five minutes. Not only is our approach more rapid than existing methods, it exports a metrically accurate 3D avatar model that is rigged and skinned.

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Project Page IEEE Open Access IEEE Open Access PDF DOI [BibTex]

Project Page IEEE Open Access IEEE Open Access PDF DOI [BibTex]


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Interpreting first-order reversal curves beyond the Preisach model: An experimental permalloy microarray investigation

Groß, F., Ilse, S. E., Schütz, G., Gräfe, J., Goering, E.

{Physical Review B}, 99(6), American Physical Society, Woodbury, NY, 2019 (article)

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DOI [BibTex]


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Bistability of magnetic states in Fe-Pd nanocap arrays

Aravind, P. B., Heigl, M., Fix, M., Groß, F., Gräfe, J., Mary, A., Rajgowrav, C. R., Krupiński, M., Marszałek, M., Thomas, S., Anantharaman, M. R., Albrecht, M.

Nanotechnology, 30, pages: 405705, 2019 (article)

Abstract
Magnetic bistability between vortex and single domain states in nanostructures are of great interest from both fundamental and technological perspectives. In soft magnetic nanostructures, the transition from a uniform collinear magnetic state to a vortex state (or vice versa) induced by a magnetic field involves an energy barrier. If the thermal energy is large enough for overcoming this energy barrier, magnetic bistability with a hysteresis-free switching occurs between the two magnetic states. In this work, we tune this energy barrier by tailoring the composition of FePd alloys, which were deposited onto self-assembled particle arrays forming magnetic vortex structures on top of the particles. The bifurcation temperature, where a hysteresis-free transition occurs, was extracted from the temperature dependence of the annihilation and nucleation field which increases almost linearly with Fe content of the magnetic alloy. This study provides insights into the magnetization reversal process associated with magnetic bistability, which allows adjusting the bifurcation temperature range by the material properties of the nanosystem.

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link (url) [BibTex]

link (url) [BibTex]


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Probabilistic Linear Solvers: A Unifying View

Bartels, S., Cockayne, J., Ipsen, I. C. F., Hennig, P.

Statistics and Computing, 2019 (article) Accepted

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link (url) [BibTex]

link (url) [BibTex]


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Artifacts from manganese reduction in rock samples prepared by focused ion beam (FIB) slicing for X-ray microspectroscopy

Macholdt, D. S., Förster, J., Müller, M., Weber, B., Kappl, M., Kilcoyne, A. L. D., Weigand, M., Leitner, J., Jochum, K. P., Pöhlker, C., Andreae, M. O.

{Geoscientific instrumentation, methods and data systems}, 8(1):97-111, Copernicus Publ., Göttingen, 2019 (article)

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DOI [BibTex]

DOI [BibTex]


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Mixed-state magnetotransport properties of MgB2 thin film prepared by pulsed laser deposition on an Al2O3 substrate

Alzayed, N. S., Shahabuddin, M., Ramey, S. M., Soltan, S.

{Journal of Materials Science: Materials in Electronics}, 30(2):1547-1552, Springer, Norwell, MA, 2019 (article)

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DOI [BibTex]

DOI [BibTex]


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Comparison of theories of fast and ultrafast magnetization dynamics

Fähnle, M.

{Journal of Magnetism and Magnetic Materials}, 469, pages: 28-29, NH, Elsevier, Amsterdam, 2019 (article)

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DOI [BibTex]

DOI [BibTex]


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Concepts for improving hydrogen storage in nanoporous materials

Broom, D. P., Webb, C. J., Fanourgakis, G. S., Froudakis, G. E., Trikalitis, P. N., Hirscher, M.

{International Journal of Hydrogen Energy}, 44(15):7768-7779, Elsevier, Amsterdam, 2019 (article)

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DOI [BibTex]

DOI [BibTex]


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Controlling dislocation nucleation-mediatd plasticity in nanostructures via surface modification

Shin, J., Chen, L. Y., Sanli, U. T., Richter, G., Labat, S., Richard, M., Cornelius, T., Thomas, O., Gianola, D. S.

{Acta Materialia}, 166, pages: 572-586, Elsevier Science, Kidlington, 2019 (article)

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DOI [BibTex]

DOI [BibTex]

2000


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Anisotropic flux pinning in thin YBCO-films by substrate modifications

Leonhardt, S., Warthmann, R., Albrecht, J., Jooss, C., Kronmüller, H., Haage, T., Zegenhagen, J., Habermeier, H.-U.

{Physica C}, 332, pages: 214-218, 2000 (article)

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[BibTex]

2000


[BibTex]


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A review of the magnetic relaxation and its application to the study of atomic defects in α-iron and its diuluted alloys

Blythe, H. J., Kronmüller, H., Seeger, A., Walz, F.

{Physica Status Solidi (A)}, 181, pages: 233-345, 2000 (article)

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[BibTex]

[BibTex]


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Magnetic properties of Sm2Co17-xGax (x \textequals 0-7) compounds

Liang, B., Kleinschroth, I., Shen, B. G., Kronmüller, H.

{Journal of Applied Physics}, 87, pages: 5314-5316, 2000 (article)

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[BibTex]

[BibTex]


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Computational micromagnetism of magnetic structures and magnetization processes in small particles

Kronmüller, H., Hertel, R.

{Journal of Magnetism and Magnetic Materials}, 215-216, pages: 11-17, 2000 (article)

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[BibTex]

[BibTex]


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Interface-structure studies by atomic-resolution electron microscopy, order-disorder phenomena, and atomic diffusion in gas-phase-synthesized nanocrystalline solids

Schaefer, H.-E., Reimann, K., Straub, W., Phillipp, F., Tanimoto, H., Brossmann, U., Würschum, R.

{Materials Science and Engineering A}, 286, pages: 24-33, 2000 (article)

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[BibTex]

[BibTex]


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High-performance permanent magnets

Goll, D., Kronmüller, H.

{Naturwissenschaften}, 87, pages: 423-438, 2000 (article)

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[BibTex]

[BibTex]


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Nonlinear magnetoelastic coupling coefficients from simultaneous measurements of magnetostrictive stress and anisotropy in epitaxial magnetic films

Fähnle, M., Komelj, M.

{Journal of Applied Physics}, 88, pages: 2781-2786, 2000 (article)

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[BibTex]


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Reconstruction of the Mo(100) surface: a tight-binding study

Haas, H., Wang, C. Z., Ho, K. M., Fähnle, M., Elsässer, C.

{Surface Science}, 457, pages: L397-L403, 2000 (article)

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[BibTex]

[BibTex]


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The strain-softening phenomenon of icosahedral Al-Pd-Mn single quasicrystals

Brunner, D., Plachke, D., Carstanjen, H. D.

{Materials Science and Engineering A}, 294-296, pages: 773-776, 2000 (article)

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[BibTex]

[BibTex]


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Corrosion behaviour of the protective and decorative TiN coatings on large area steel strips

Vershinin, N., Filonov, K., Straumal, B., Gust, W., Wiener, I., Rabkin, E., Kazakevich, A.

{Surface and Coatings Technology}, 125, pages: 229-232, 2000 (article)

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[BibTex]

[BibTex]


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Influence of substrate irradiation on critical density and microstructure in YBCO thin films

Leonhardt, S., Albrecht, J., Warthmann, R., Habermeier, H.-U., Kronmüller, H.

{Physica C}, 341-348, pages: 1979-1980, 2000 (article)

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[BibTex]

[BibTex]


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Channeling of high-energy particles in bent crystals - experiments at the CERN SPS

Baurichter, A., Biino, C., Clement, M., Doble, N., Elsener, K., Fidecaro, G., Freund, A., Gatignon, L., Grafström, P., Gyr, M., Hage-Ali, M., Herr, W., Keppler, P., Kirsebom, K., Klem, J., Major, J., Medenwaldt, R., Mikkelsen, U., Moller, S. P., Siffert, P., Uggerhoj, E., Vilakazi, Z. Z., Weisse, E.

{Nuclear Instruments and Methods in Physics Research B}, 164-165, pages: 27-43, 2000 (article)

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[BibTex]

[BibTex]


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Magnetoelastic effects in ultrathin epitaxial Ni films: An ab-initio study

Komelj, M., Fähnle, M.

{Journal of Magnetism and Magnetic Materials}, 222, pages: L 245-L 250, 2000 (article)

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[BibTex]

[BibTex]


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Evidence for near-grain boundary lattice rotations in an Fe(Si) alloy.

Rabkin, E., Semenov, V., Bischoff, E.

{Zeitschrift f\"ur Metallkunde}, 91, pages: 165-170, 2000 (article)

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[BibTex]

[BibTex]


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Electron focusing in metals and semimetals

Heil, J., Böhm, A., Gröger, A., Primke, M., Wyder, P., Keppler, P., Major, J., Bender, H., Schönherr, E., Wendel, H., Wolf, B., Würz, U., Grill, W., Herrenberger, S., Knauth, S., Lenzner, J.

{Physics Reports}, 323, pages: 387-455, 2000 (article)

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[BibTex]

[BibTex]


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Analysis of the electronic structure of intermetallic compounds and application to structural defects in B2 phases

Börnsen, N., Meyer, B., Bester, G., Fähnle, M.

{Journal of Alloys and Compounds}, 308, pages: 1-14, 2000 (article)

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[BibTex]

[BibTex]


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Melt-spun precipitation-hardened Sm2(Co,Cu,Fe,Zr)17 magnets with abnormal temperature dependence of coercivity

Goll, D., Kleinschroth, I., Sigle, W., Kronmüller, H.

{Applied Physics Letters}, 76, pages: 1054-1056, 2000 (article)

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[BibTex]

[BibTex]


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Hydrogen-induced phase transition of GdZn1-xMgx compounds

Reule, H., Hirscher, M.

{Journal of Alloys and Compounds}, 298, pages: 1-8, 2000 (article)

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[BibTex]

[BibTex]


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The influence of a finite bandwidth on the Verwey transition in magnetite

Brabers, J. H. V. J., Walz, F., Kronmüller, H.

{Journal of Physics: Condensed Matter}, 12, pages: 5437-5452, 2000 (article)

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[BibTex]

[BibTex]


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Influcence of vortex-vortex interaction on critical currents across low-angle grain boundaries in YBa2Cu3O7-δ

Albrecht, J., Leonhardt, S., Kronmüller, H.

{Physical Review B}, 63, 2000 (article)

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[BibTex]

[BibTex]


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Symmetrical Tilt Grain boundaries in body-centred cubic transition metals: An ab-initio local-density-functional study

Ochs, T., Beck, O., Elsässer, C., Meyer, B.

{Philosophical Magazine A}, 80, pages: 351-372, 2000 (article)

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[BibTex]


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The liquid ferromagnet Co80Pd20 and its critical exponent γ

Bührer, C., Beckmann, M., Fähnle, M., Maier, K.

{Journal of Magnetism and Magnetic Materials}, 212, pages: 211-224, 2000 (article)

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[BibTex]

[BibTex]


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Irreversible magnetization processes in a soft magnetic platelet

Hertel, R., Kronmüller, H.

{Physica B}, 275, pages: 1-4, 2000 (article)

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[BibTex]

[BibTex]


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Measurement of the Zener relaxation in high-purity FeCr single crystals

Hirscher, M., Brossmann, U., Henes, R.

{Materials Transactions, JIM}, 41, pages: 82-86, 2000 (article)

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[BibTex]

[BibTex]


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Ab-initio statistical mechanics for alloy phase diagrams and ordering phenomena including the effect of vacancies

Lechermann, F., Fähnle, M.

{Physical Review B}, 63, 2000 (article)

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[BibTex]


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Reactions in TiO2/Ti3Al and TiO2/TiAl bilayers: Application of target-factor analysis in auger electron spectroscopy

van Lier, J., Baretzky, B., Zalar, A., Mittemeijer, E. J.

{Surface and Interface Analysis}, 30, pages: 124-129, 2000 (article)

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[BibTex]

[BibTex]


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Ab-initio treatment of noncollinear spin systems within the atomic-sphere approximation and beyond

Grotheer, O., Ederer, C., Fähnle, M.

{Physical Review B}, 62, pages: 5601-5608, 2000 (article)

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[BibTex]

[BibTex]


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Is d-Al-Cu-Co a random tiling?

Zeger, G., Plachke, D., Carstanjen, H. D., Trebin, H. R.

{Materials Science and Engineering A}, 294, pages: 291-294, 2000 (article)

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[BibTex]

[BibTex]


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Nonlinear magnetoelastic coupling coefficients in Fe from an ab-initio calculation

Komelj, M., Fähnle, M.

{Journal of Magnetism and Magnetic Materials}, 220, pages: L 7-L 12, 2000 (article)

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[BibTex]

[BibTex]


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Current densities in low-angle grain boundaries of YBCO

Albrecht, J., Warthmann, R., Leonhardt, S., Kronmüller, H.

{Physica C}, 341-348, pages: 1459-1460, 2000 (article)

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[BibTex]

[BibTex]


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The hydrogen desorption kinetics of Pd-coated LaNi5-type films

Cuevas, F., Hirscher, M.

{Journal of Alloys and Compounds}, 313, pages: 269-275, 2000 (article)

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[BibTex]


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The structure of the trihydride GdH3

Ellner, M., Reule, H., Mittemeijer, E. J.

{Journal of Alloys and Compounds}, 309, pages: 127-131, 2000 (article)

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[BibTex]

[BibTex]


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Corrosion resistance of the vacuum arc deposited Ti, TiN and TiO2 coatings on large area glass substrates

Vershinin, N., Filonov, K., Straumal, B., Gust, W., Dimitriou, R., Kovalev, A., Camacho, J.

{Surface and Coatings Technology}, 125, pages: 223-228, 2000 (article)

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[BibTex]

[BibTex]