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2014


Roombots: A hardware perspective on 3D self-reconfiguration and locomotion with a homogeneous modular robot
Roombots: A hardware perspective on 3D self-reconfiguration and locomotion with a homogeneous modular robot

Spröwitz, A., Moeckel, R., Vespignani, M., Bonardi, S., Ijspeert, A. J.

{Robotics and Autonomous Systems}, 62(7):1016-1033, Elsevier, Amsterdam, 2014 (article)

Abstract
In this work we provide hands-on experience on designing and testing a self-reconfiguring modular robotic system, Roombots (RB), to be used among others for adaptive furniture. In the long term, we envision that RB can be used to create sets of furniture, such as stools, chairs and tables that can move in their environment and that change shape and functionality during the day. In this article, we present the first, incremental results towards that long term vision. We demonstrate locomotion and reconfiguration of single and metamodule RB over 3D surfaces, in a structured environment equipped with embedded connection ports. RB assemblies can move around in non-structured environments, by using rotational or wheel-like locomotion. We show a proof of concept for transferring a Roombots metamodule (two in-series coupled RB modules) from the non-structured environment back into the structured grid, by aligning the RB metamodule in an entrapment mechanism. Finally, we analyze the remaining challenges to master the full Roombots scenario, and discuss the impact on future Roombots hardware.

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DOI [BibTex]

2014


DOI [BibTex]


A freely-moving monkey treadmill model
A freely-moving monkey treadmill model

Foster, J., Nuyujukian, P., Freifeld, O., Gao, H., Walker, R., Ryu, S., Meng, T., Murmann, B., Black, M., Shenoy, K.

J. of Neural Engineering, 11(4):046020, 2014 (article)

Abstract
Objective: Motor neuroscience and brain-machine interface (BMI) design is based on examining how the brain controls voluntary movement, typically by recording neural activity and behavior from animal models. Recording technologies used with these animal models have traditionally limited the range of behaviors that can be studied, and thus the generality of science and engineering research. We aim to design a freely-moving animal model using neural and behavioral recording technologies that do not constrain movement. Approach: We have established a freely-moving rhesus monkey model employing technology that transmits neural activity from an intracortical array using a head-mounted device and records behavior through computer vision using markerless motion capture. We demonstrate the excitability and utility of this new monkey model, including the fi rst recordings from motor cortex while rhesus monkeys walk quadrupedally on a treadmill. Main results: Using this monkey model, we show that multi-unit threshold-crossing neural activity encodes the phase of walking and that the average ring rate of the threshold crossings covaries with the speed of individual steps. On a population level, we find that neural state-space trajectories of walking at diff erent speeds have similar rotational dynamics in some dimensions that evolve at the step rate of walking, yet robustly separate by speed in other state-space dimensions. Significance: Freely-moving animal models may allow neuroscientists to examine a wider range of behaviors and can provide a flexible experimental paradigm for examining the neural mechanisms that underlie movement generation across behaviors and environments. For BMIs, freely-moving animal models have the potential to aid prosthetic design by examining how neural encoding changes with posture, environment, and other real-world context changes. Understanding this new realm of behavior in more naturalistic settings is essential for overall progress of basic motor neuroscience and for the successful translation of BMIs to people with paralysis.

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pdf Supplementary DOI Project Page [BibTex]

pdf Supplementary DOI Project Page [BibTex]


Detection and Tracking of Occluded People
Detection and Tracking of Occluded People

Tang, S., Andriluka, M., Schiele, B.

International Journal of Computer Vision, 110, pages: 58-69, 2014 (article)

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PDF [BibTex]

PDF [BibTex]


Kinematic primitives for walking and trotting gaits of a quadruped robot with compliant legs
Kinematic primitives for walking and trotting gaits of a quadruped robot with compliant legs

Spröwitz, A. T., Ajallooeian, M., Tuleu, A., Ijspeert, A. J.

Frontiers in Computational Neuroscience, 8(27):1-13, 2014 (article)

Abstract
In this work we research the role of body dynamics in the complexity of kinematic patterns in a quadruped robot with compliant legs. Two gait patterns, lateral sequence walk and trot, along with leg length control patterns of different complexity were implemented in a modular, feed-forward locomotion controller. The controller was tested on a small, quadruped robot with compliant, segmented leg design, and led to self-stable and self-stabilizing robot locomotion. In-air stepping and on-ground locomotion leg kinematics were recorded, and the number and shapes of motion primitives accounting for 95\% of the variance of kinematic leg data were extracted. This revealed that kinematic patterns resulting from feed-forward control had a lower complexity (in-air stepping, 2–3 primitives) than kinematic patterns from on-ground locomotion (νm4 primitives), although both experiments applied identical motor patterns. The complexity of on-ground kinematic patterns had increased, through ground contact and mechanical entrainment. The complexity of observed kinematic on-ground data matches those reported from level-ground locomotion data of legged animals. Results indicate that a very low complexity of modular, rhythmic, feed-forward motor control is sufficient for level-ground locomotion in combination with passive compliant legged hardware.

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link (url) DOI [BibTex]

link (url) DOI [BibTex]


Segmentation of Biomedical Images Using Active Contour Model with Robust Image Feature and Shape Prior
Segmentation of Biomedical Images Using Active Contour Model with Robust Image Feature and Shape Prior

S. Y. Yeo, X. Xie, I. Sazonov, P. Nithiarasu

International Journal for Numerical Methods in Biomedical Engineering, 30(2):232- 248, 2014 (article)

Abstract
In this article, a new level set model is proposed for the segmentation of biomedical images. The image energy of the proposed model is derived from a robust image gradient feature which gives the active contour a global representation of the geometric configuration, making it more robust in dealing with image noise, weak edges, and initial configurations. Statistical shape information is incorporated using nonparametric shape density distribution, which allows the shape model to handle relatively large shape variations. The segmentation of various shapes from both synthetic and real images depict the robustness and efficiency of the proposed method.

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[BibTex]

[BibTex]


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Efflorescence upon humidification? X-ray microspectroscopic in situ observation of changes in aerosol microstructure and phase state upon hydration

Pöhlker, C., Saturno, J., Krüger, M. L., Förster, J. D., Weigand, M., Wiedemann, K. T., Bechtel, M., Artaxo, P., Andreae, M. O.

{Geophysical Research Letters}, 41(10):3681-3689, American Geophysical Union, Washington, D.C., 2014 (article)

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DOI [BibTex]

DOI [BibTex]


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Investigation of cellular microstructure and enhanced coercivity in sputtered Sm2(CoCuFeZr)17 film

Bhatt, R., Bhatt, P., Schütz, G.

{Journal of Applied Physics}, 115(10), American Institute of Physics, New York, NY, 2014 (article)

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DOI [BibTex]

DOI [BibTex]


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Detecting magnetic flux distributions in superconductors with polarized x-rays

Stahl, C., Audehm, P., Gräfe, J., Ruoß, S., Weigand, M., Schmidt, M., Treiber, S., Bechtel, M., Goering, E., Schütz, G., Albrecht, J.

{Physical Review B}, 90(10), American Physical Society, Woodbury, NY, 2014 (article)

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DOI [BibTex]

DOI [BibTex]


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Spatial degradation mapping and component-wise degradation tracking in polymer-fullerene blends

Pedersen, E. B. B., Tromholt, T., Madsen, M. V., Böttiger, A. P. L., Weigand, M., Krebs, F. C., Andreasen, J. W.

{Journal of Materials Chemistry C}, 2(26):5176-5182, Royal Society of Chemistry, Cambridge, UK, 2014 (article)

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DOI [BibTex]

DOI [BibTex]


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Vortex core reversal due to spin wave interference

Bauer, H. G., Sproll, M., Back, C. H., Woltersdorf, G.

{Physical Review Letters}, 112, American Physical Society, Woodbury, N.Y., 2014 (article)

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DOI [BibTex]

DOI [BibTex]


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Understanding the adsorption mechanism of noble gases Kr and Xe in CPO-27-Ni, CPO-27-Mg, and ZIF-8

Magdysyuk, O. V., Adams, F., Liermann, H., Spanopoulos, I., Trikalitis, P. N., Hirscher, M., Morris, R. E., Duncan, M. J., McCormick, L. J., Dinnebier, R. E.

{Physical Chemistry Chemical Physics}, 16(43):23908-23914, Royal Society of Chemistry, Cambridge, England, 2014 (article)

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DOI [BibTex]

DOI [BibTex]


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Unidirectional sub-100-ps magnetic vortex core reversal

Noske, M., Gangwar, A., Stoll, H., Kammerer, M., Sproll, M., Dieterle, G., Weigand, M., Fähnle, M., Woltersdorf, G., Back, C. H., Schütz, G.

{Physical Review B}, 90(10), American Physical Society, Woodbury, NY, 2014 (article)

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DOI [BibTex]

DOI [BibTex]


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Domain wall transformations and hopping in La0.7Sr0.3MnO3 nanostructures imaged with high resolution x-ray magnetic microscopy

Finizio, S., Foerster, M., Krüger, B., Vaz, C. A. F., Miyawaki, T., Mawass, M. A., Pena, L., Méchin, L., Hühn, S., Moshnyaga, V., Büttner, F., Bisig, A., Le Guyader, L., El Moussaoui, S., Valencia, S., Kronast, F., Eisebitt, S., Kläui, M.

{Journal of Physics: Condensed Matter}, 26(45), IOP Publishing, Bristol, 2014 (article)

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DOI [BibTex]

DOI [BibTex]


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Tunable eigenmodes of coupled magnetic vortex oscillators

Hänze, M., Adolff, C. F., Weigand, M., Meier, G.

{Applied Physics Letters}, 104(18), American Institute of Physics, Melville, NY, 2014 (article)

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DOI [BibTex]

DOI [BibTex]


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Domain wall pinning in ultra-narrow electromigrated break junctions

Reeve, R. M., Loescher, A., Mawass, M.-A., Hoffmann-Vogel, R., Kläui, M.

{Journal of Physics: Condensed Matter}, 26(47), IOP Publishing, Bristol, 2014 (article)

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DOI [BibTex]

DOI [BibTex]


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Highly effective hydrogen isotope separation in nanoporous metal-organic framworks with open metal sites: Direct measurement and theoretical analysis

Oh, H., Savchenko, I., Mavrandonakis, A., Heine, T., Hirscher, M.

{ACS Nano}, 8(1):761-770, American Chemical Society, Washington, DC, 2014 (article)

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DOI [BibTex]

DOI [BibTex]


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Stabilization of the dissipation-free current transport in inhomogeneous MgB2 thin films

Treiber, S., Stahl, C., Schütz, G., Soltan, S., Albrecht, J.

{Physica C}, 506, pages: 1-5, North-Holland, Amsterdam, 2014 (article)

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DOI [BibTex]

DOI [BibTex]


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Thermal conductivity of mechanically joined semiconducting/metal nanomembrane superlattices

Grimm, D., Wilson, R. B., Teshome, B., Gorantla, S., Rümmeli, M. H., Bublat, T., Zallo, E., Li, G., Cahill, D. G., Schmidt, O. G.

{Nano Letters}, 14(5):2387-2393, American Chemical Society, Washington, DC, 2014 (article)

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DOI [BibTex]

DOI [BibTex]


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Role of the sample boundaries in the problem of dissipative magnetization dynamics

Fähnle, M., Slavin, A., Hertel, R.

{Journal of Magnetism and Magnetic Materials}, 360, pages: 126-130, Elsevier, Amsterdam, 2014 (article)

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DOI [BibTex]

DOI [BibTex]


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Using magnetic coupling in bilayers of superconducting YBCO and soft-magnetic CoFeB to map supercurrent flow

Stahl, C., Walker, P., Treiber, S., Christiani, G., Schütz, G., Albrecht, J.

{EPL}, 106(2), 2014 (article)

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DOI [BibTex]

DOI [BibTex]


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Element-specific depth profile of magnetism and stoichiometry at the La0.67Sr0.33MnO3/BiFeO3 interface

Bertinshaw, J., Brück, S., Lott, D., Fritzsche, H., Khaydukov, Y., Soltwedel, O., Keller, T., Goering, E., Audehm, P., Cortie, D. L., Hutchison, W. D., Ramasse, Q. M., Arredondo, M., Maran, R., Nagarajan, V., Klose, F., Ulrich, C.

{Physical Review B}, 90(4), American Physical Society, Woodbury, NY, 2014 (article)

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DOI [BibTex]

DOI [BibTex]


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Magnetic reflectometry of heterostructures (Topical Review)

Macke, S., Goering, E.

{Journal of Physics: Condensed Matter}, 26(36), IOP Publishing, Bristol, 2014 (article)

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DOI [BibTex]

DOI [BibTex]


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Optimizing the fabrication of diffractive optical elements using a focused ion beam system

Vijayakumar, A., Eigenthaler, U., Keskinbora, K., Sridharan, G. M., Pramitha, V., Hirscher, M., Spatz, J. P., Bhattacharya, S.

{Proceedings of SPIE}, 9130, 2014 (article)

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DOI [BibTex]

DOI [BibTex]


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Direct observation of internal vortex domain-wall dynamics

Stein, F.-U., Bocklage, L., Weigand, M., Meier, G.

{Physical Review B}, 89(2), American Physical Society, Woodbury, NY, 2014 (article)

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DOI [BibTex]

DOI [BibTex]


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Synchronous precessional motion of multiple domain walls in a ferromagnetic nanowire by perpendicular field pulses

Kim, J., Mawass, M., Bisig, A., Krüger, B., Reeve, R. M., Schulz, T., Büttner, F., Yoon, J., You, C., Weigand, M., Stoll, H., Schütz, G., Swagten, H. J. M., Koopmans, B., Eisebitt, S., Kläui, M.

{Nature Communications}, 5, Nature Publishing Group, London, 2014 (article)

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DOI [BibTex]

DOI [BibTex]


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Magnetic field distribution and characteristic fields of the vortex lattice for a clean superconducting niobium sample in an external field applied along a three-fold axis

Yaouanc, A., Maisuradze, A., Nakai, N., Machida, K., Khasanov, R., Amato, A., Biswas, P. K., Baines, C., Herlach, D., Henes, Rolf, Keppler, P., Keller, H.

{Physical Review B}, 89(18), American Physical Society, Woodbury, NY, 2014 (article)

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DOI [BibTex]

DOI [BibTex]


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Experimental assessment of Physical upper limit for hydrogen storage capacity at 20 K in densified MIL-101 monoliths

Oh, H., Lupu, D., Blanita, G., Hirscher, M.

{RSC Advances}, 4(6):2648-2651, Royal Society of Chemistry, Cambridge, UK, 2014 (article)

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DOI [BibTex]

DOI [BibTex]


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Strengthening zones in the Co matrix of WC-Co cemented carbides

Konyashin, I., Lachmann, F., Ries, B., Mazilkin, A. A., Straumal, B. B., Kübel, C., Llanes, L., Baretzky, B.

{Scripta Materialia}, 83, pages: 17-20, Pergamon, Tarrytown, NY, 2014 (article)

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DOI [BibTex]

DOI [BibTex]


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Multilayer Fresnel zone plates for high energy radiation resolve 21 nm features at 1.2 keV

Keskinbora, K., Robisch, A., Mayer, M., Sanli, U., Grévent, C., Wolter, C., Weigand, M., Szeghalmi, A., Knez, M., Salditt, T., Schütz, G.

{Optics Express}, 22(15):18440-18453, Optical Society of America, Washington, DC, 2014 (article)

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DOI [BibTex]

DOI [BibTex]


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Interplay of linker functionalization and hydrogen adsorption in the metal-organic framework MIL-101

Szilágyi, P. A., Weinrauch, I., Oh, H., Hirscher, M., Juan-Alcaniz, J., Serra-Crespo, P., de Respinis, M., Trzesniewski, B. J., Kapteijn, F., Geerlings, H., Gascon, J., Dam, B., Grzech, A., van de Krol, R.

{The Journal of Physical Chemistry C}, 118(34):19572-19579, American Chemical Society, Washington DC, 2014 (article)

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DOI [BibTex]

DOI [BibTex]


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Application of magneto-optical Kerr effect to first-order reversal curve measurements

Gräfe, J., Schmidt, M., Audehm, P., Schütz, G., Goering, E.

{Review of Scientific Instruments}, 85, American Institute of Physics, Woodbury, N.Y. [etc.], 2014 (article)

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DOI Project Page [BibTex]

DOI Project Page [BibTex]


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Efficient focusing of 8 keV X-rays with multilayer Fresnel zone plates fabricated by atomic layer deposition and focused ion beam milling. Erratum

Mayer, M., Keskinbora, K., Grévent, C., Szeghalmi, A., Knez, M., Weigand, M., Snigirev, A., Snigireva, I., Schütz, G.

{Journal of Synchrotron Radiation}, 640, pages: 640-640, Published for the International Union of Crystallography by Munksgaard, Copenhagen, Denmark, 2014 (article)

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DOI [BibTex]

DOI [BibTex]


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Low-amplitude magnetic vortex core reversal by non-linear interaction between azimuthal spin waves and the vortex gyromode

Sproll, M., Noske, M., Bauer, H., Kammerer, M., Gangwar, A., Dieterle, G., Weigand, M., Stoll, H., Woltersdorf, G., Back, C. H., Schütz, G.

{Applied Physics Letters}, 104(1), American Institute of Physics, Melville, NY, 2014 (article)

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DOI [BibTex]

DOI [BibTex]


A Quantitative Analysis of Current Practices in Optical Flow Estimation and the Principles behind Them
A Quantitative Analysis of Current Practices in Optical Flow Estimation and the Principles behind Them

Sun, D., Roth, S., Black, M. J.

International Journal of Computer Vision (IJCV), 106(2):115-137, 2014 (article)

Abstract
The accuracy of optical flow estimation algorithms has been improving steadily as evidenced by results on the Middlebury optical flow benchmark. The typical formulation, however, has changed little since the work of Horn and Schunck. We attempt to uncover what has made recent advances possible through a thorough analysis of how the objective function, the optimization method, and modern implementation practices influence accuracy. We discover that "classical'' flow formulations perform surprisingly well when combined with modern optimization and implementation techniques. One key implementation detail is the median filtering of intermediate flow fields during optimization. While this improves the robustness of classical methods it actually leads to higher energy solutions, meaning that these methods are not optimizing the original objective function. To understand the principles behind this phenomenon, we derive a new objective function that formalizes the median filtering heuristic. This objective function includes a non-local smoothness term that robustly integrates flow estimates over large spatial neighborhoods. By modifying this new term to include information about flow and image boundaries we develop a method that can better preserve motion details. To take advantage of the trend towards video in wide-screen format, we further introduce an asymmetric pyramid downsampling scheme that enables the estimation of longer range horizontal motions. The methods are evaluated on Middlebury, MPI Sintel, and KITTI datasets using the same parameter settings.

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pdf full text code [BibTex]

pdf full text code [BibTex]


Automatic 4D Reconstruction of Patient-Specific Cardiac Mesh with 1- to-1 Vertex Correspondence from Segmented Contours Lines
Automatic 4D Reconstruction of Patient-Specific Cardiac Mesh with 1- to-1 Vertex Correspondence from Segmented Contours Lines

C. W. Lim, Y. Su, S. Y. Yeo, G. M. Ng, V. T. Nguyen, L. Zhong, R. S. Tan, K. K. Poh, P. Chai,

PLOS ONE, 9(4), 2014 (article)

Abstract
We propose an automatic algorithm for the reconstruction of patient-specific cardiac mesh models with 1-to-1 vertex correspondence. In this framework, a series of 3D meshes depicting the endocardial surface of the heart at each time step is constructed, based on a set of border delineated magnetic resonance imaging (MRI) data of the whole cardiac cycle. The key contribution in this work involves a novel reconstruction technique to generate a 4D (i.e., spatial–temporal) model of the heart with 1-to-1 vertex mapping throughout the time frames. The reconstructed 3D model from the first time step is used as a base template model and then deformed to fit the segmented contours from the subsequent time steps. A method to determine a tree-based connectivity relationship is proposed to ensure robust mapping during mesh deformation. The novel feature is the ability to handle intra- and inter-frame 2D topology changes of the contours, which manifests as a series of merging and splitting of contours when the images are viewed either in a spatial or temporal sequence. Our algorithm has been tested on five acquisitions of cardiac MRI and can successfully reconstruct the full 4D heart model in around 30 minutes per subject. The generated 4D heart model conforms very well with the input segmented contours and the mesh element shape is of reasonably good quality. The work is important in the support of downstream computational simulation activities.

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[BibTex]

[BibTex]


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The local magnetic properties of [MnIII6 CrIII]3+ and [FeIII6 CrIII]3+ single-molecule magnets deposited on surfaces studied by spin-polarized photoemission and XMCD with circularly polarized synchrotron radiation

Heinzmann, U., Helmstedt, A., Dohmeier, N., Müller, N., Gryzia, A., Brechling, A., Hoeke, V., Krickemeyer, E., Glaser, T., Fonin, M., Bouvron, S., Leicht, P., Tietze, T., Goering, E., Kuepper, K.

{Journal of Physics: Conference Series}, 488(13), IOP Publishing, Bristol, 2014 (article)

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DOI [BibTex]

DOI [BibTex]


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A fluorene based covalent triazine framework with high CO2 and H2 capture and storage capacities

Hug, S., Mesch, M. B., Oh, H., Popp, N., Hirscher, M., Senker, J., Lotsch, B. V.

{Journal of Materials Chemistry A}, 2(16):5928-5936, Royal Society of Chemistry, Cambridge, UK, 2014 (article)

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DOI [BibTex]

DOI [BibTex]


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Ab-initio calculations and atomistic calculations on the magnetoelectric effects in metallic nanostructures

Fähnle, M., Subkow, S.

{Physica Status Solidi C}, 11(2):185-191, Wiley-VCH, Weinheim, 2014 (article)

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DOI [BibTex]

DOI [BibTex]


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Role of electron-magnon scatterings in ultrafast demagnetization

Haag, M., Illg, C., Fähnle, M.

{Physical Review B}, 90(1), American Physical Society, Woodbury, NY, 2014 (article)

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DOI [BibTex]

DOI [BibTex]


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Element specific monolayer depth profiling

Macke, S., Radi, A., Hamann-Borrero, J. E., Verna, A., Bluschke, M., Brück, S., Goering, E., Sutarto, R., He, F., Cristiani, G., Wu, M., Benckiser, E., Habermeier, H., Logvenov, G., Gauquelin, N., Botton, G. A., Kajdos, A. P., Stemmer, S., Sawatzky, G. A., Haverkort, M. W., Keimer, B., Hinkov, V.

{Advanced Materials}, 26(38):6554-6559, Wiley VCH, Weinheim, 2014 (article)

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DOI [BibTex]

DOI [BibTex]


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Local modification of the magnetic vortex-core velocity by gallium implantation

Langner, H. H., Vogel, A., Beyersdorff, B., Weigand, M., Frömter, R., Oepen, H. P., Meier, G.

{Journal of Applied Physcis}, (10), American Institute of Physics, New York, NY, 2014 (article)

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DOI [BibTex]

DOI [BibTex]


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Influence of magnetic fields on spin-mixing in transition metals

Haag, M., Illg, C., Fähnle, M.

{Physical Review B}, 90(13), American Physical Society, Woodbury, NY, 2014 (article)

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DOI [BibTex]

DOI [BibTex]

2013


Branch\&Rank for Efficient Object Detection
Branch&Rank for Efficient Object Detection

Lehmann, A., Gehler, P., VanGool, L.

International Journal of Computer Vision, Springer, December 2013 (article)

Abstract
Ranking hypothesis sets is a powerful concept for efficient object detection. In this work, we propose a branch&rank scheme that detects objects with often less than 100 ranking operations. This efficiency enables the use of strong and also costly classifiers like non-linear SVMs with RBF-TeX kernels. We thereby relieve an inherent limitation of branch&bound methods as bounds are often not tight enough to be effective in practice. Our approach features three key components: a ranking function that operates on sets of hypotheses and a grouping of these into different tasks. Detection efficiency results from adaptively sub-dividing the object search space into decreasingly smaller sets. This is inherited from branch&bound, while the ranking function supersedes a tight bound which is often unavailable (except for rather limited function classes). The grouping makes the system effective: it separates image classification from object recognition, yet combines them in a single formulation, phrased as a structured SVM problem. A novel aspect of branch&rank is that a better ranking function is expected to decrease the number of classifier calls during detection. We use the VOC’07 dataset to demonstrate the algorithmic properties of branch&rank.

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pdf link (url) [BibTex]

2013


pdf link (url) [BibTex]


Extracting Postural Synergies for Robotic Grasping
Extracting Postural Synergies for Robotic Grasping

Romero, J., Feix, T., Ek, C., Kjellstrom, H., Kragic, D.

Robotics, IEEE Transactions on, 29(6):1342-1352, December 2013 (article)

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[BibTex]

[BibTex]


Markov Random Field Modeling, Inference & Learning in Computer Vision & Image Understanding: A Survey
Markov Random Field Modeling, Inference & Learning in Computer Vision & Image Understanding: A Survey

Wang, C., Komodakis, N., Paragios, N.

Computer Vision and Image Understanding (CVIU), 117(11):1610-1627, November 2013 (article)

Abstract
In this paper, we present a comprehensive survey of Markov Random Fields (MRFs) in computer vision and image understanding, with respect to the modeling, the inference and the learning. While MRFs were introduced into the computer vision field about two decades ago, they started to become a ubiquitous tool for solving visual perception problems around the turn of the millennium following the emergence of efficient inference methods. During the past decade, a variety of MRF models as well as inference and learning methods have been developed for addressing numerous low, mid and high-level vision problems. While most of the literature concerns pairwise MRFs, in recent years we have also witnessed significant progress in higher-order MRFs, which substantially enhances the expressiveness of graph-based models and expands the domain of solvable problems. This survey provides a compact and informative summary of the major literature in this research topic.

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Publishers site pdf [BibTex]

Publishers site pdf [BibTex]


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Multi-robot cooperative spherical-object tracking in 3D space based on particle filters

Ahmad, A., Lima, P.

Robotics and Autonomous Systems, 61(10):1084-1093, October 2013 (article)

Abstract
This article presents a cooperative approach for tracking a moving spherical object in 3D space by a team of mobile robots equipped with sensors, in a highly dynamic environment. The tracker’s core is a particle filter, modified to handle, within a single unified framework, the problem of complete or partial occlusion for some of the involved mobile sensors, as well as inconsistent estimates in the global frame among sensors, due to observation errors and/or self-localization uncertainty. We present results supporting our approach by applying it to a team of real soccer robots tracking a soccer ball, including comparison with ground truth.

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DOI [BibTex]

DOI [BibTex]


Vision meets Robotics: The {KITTI} Dataset
Vision meets Robotics: The KITTI Dataset

Geiger, A., Lenz, P., Stiller, C., Urtasun, R.

International Journal of Robotics Research, 32(11):1231 - 1237 , Sage Publishing, September 2013 (article)

Abstract
We present a novel dataset captured from a VW station wagon for use in mobile robotics and autonomous driving research. In total, we recorded 6 hours of traffic scenarios at 10-100 Hz using a variety of sensor modalities such as high-resolution color and grayscale stereo cameras, a Velodyne 3D laser scanner and a high-precision GPS/IMU inertial navigation system. The scenarios are diverse, capturing real-world traffic situations and range from freeways over rural areas to inner-city scenes with many static and dynamic objects. Our data is calibrated, synchronized and timestamped, and we provide the rectified and raw image sequences. Our dataset also contains object labels in the form of 3D tracklets and we provide online benchmarks for stereo, optical flow, object detection and other tasks. This paper describes our recording platform, the data format and the utilities that we provide.

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pdf DOI [BibTex]

pdf DOI [BibTex]


Visualizing dimensionality reduction of systems biology data
Visualizing dimensionality reduction of systems biology data

Lehrmann, A. M., Huber, M., Polatkan, A. C., Pritzkau, A., Nieselt, K.

Data Mining and Knowledge Discovery, 1(27):146-165, Springer, July 2013 (article)

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pdf SpRay [BibTex]

pdf SpRay [BibTex]


Unscented Kalman Filtering on Riemannian Manifolds
Unscented Kalman Filtering on Riemannian Manifolds

Soren Hauberg, Francois Lauze, Kim S. Pedersen

Journal of Mathematical Imaging and Vision, 46(1):103-120, Springer Netherlands, May 2013 (article)

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Publishers site PDF [BibTex]

Publishers site PDF [BibTex]


Quasi-Newton Methods: A New Direction
Quasi-Newton Methods: A New Direction

Hennig, P., Kiefel, M.

Journal of Machine Learning Research, 14(1):843-865, March 2013 (article)

Abstract
Four decades after their invention, quasi-Newton methods are still state of the art in unconstrained numerical optimization. Although not usually interpreted thus, these are learning algorithms that fit a local quadratic approximation to the objective function. We show that many, including the most popular, quasi-Newton methods can be interpreted as approximations of Bayesian linear regression under varying prior assumptions. This new notion elucidates some shortcomings of classical algorithms, and lights the way to a novel nonparametric quasi-Newton method, which is able to make more efficient use of available information at computational cost similar to its predecessors.

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website+code pdf link (url) [BibTex]

website+code pdf link (url) [BibTex]