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| 2. |
- Alef, Walter, et al.
(författare)
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Geodetic data analysis of VGOS experiments
- 2021
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Ingår i: 2021 34th General Assembly and Scientific Symposium of the International Union of Radio Science, URSI GASS 2021.
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Konferensbidrag (refereegranskat)abstract
- Very Long Baseline Interferometry (VLBI) serves as one of the common geodetic methods to define the global reference frames and monitor Earth's orientation variations. The technical upgrade of the VLBI method known as the VLBI Global Observing System (VGOS) includes a critical re-design of the observed frequencies from the dual band mode (S and X band, i.e. 2 GHz and 8 GHz) to observations in a broadband (2-14 GHz). Since 2019 the first VGOS experiments are available for the geodetic analysis in free access at the International VLBI service for Geodesy and Astrometry (IVS). Also regional-only subnetworks such as European VLBI stations have succeeded already in VGOS mode. Based on these brand-new observations we review the current geodetic data analysis workflow to build a bridge between geodetic observed delays derived from different bands.
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| 3. |
- Bech, Martin, et al.
(författare)
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Results from the first preclinical CT scanner with grating based phase contrast and a rotating gantry
- 2012
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Ingår i: International Workshop on X-Ray and Neutron Phase Imaging with Gratings. - : AIP. - 1551-7616 .- 0094-243X. - 9780735410725 ; 1466, s. 130-136
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Konferensbidrag (refereegranskat)abstract
- After successful demonstrations of soft-tissue phase-contrast imaging with grating interferometers at synchrotron radiation sources and at laboratory based x-ray tubes, a first preclinical CT scanner with grating based phase contrast imaging modality has been constructed. The rotating gantry is equipped with a three-grating interferometer, a 50 watt tungsten anode source and a Hamamatsu flat panel detector. The total length of the interferometer is 45 cm, and the bed of the scanner is optimized for mice, with a scanning diameter of 35 mm. From one single scan both phase-contrast and standard attenuation based tomography can be attained, providing an overall gain in image contrast.
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| 4. |
- Bohg, Jeannette, et al.
(författare)
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Task-based Grasp Adaptation on a Humanoid Robot
- 2012
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Ingår i: Proceedings 10th IFAC Symposium on Robot Control. ; , s. 779-786
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Konferensbidrag (refereegranskat)abstract
- In this paper, we present an approach towards autonomous grasping of objects according to their category and a given task. Recent advances in the field of object segmentation and categorization as well as task-based grasp inference have been leveraged by integrating them into one pipeline. This allows us to transfer task-specific grasp experience between objects of the same category. The effectiveness of the approach is demonstrated on the humanoid robot ARMAR-IIIa.
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| 5. |
- Garcia-Ruiz, A., et al.
(författare)
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Hermetic all-fiber phase modulators using Joule heating in carbon-coated fibers
- 2018
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Ingår i: Optics InfoBase Conference Papers. - Washington, D.C. : OSA - The Optical Society. - 9781557528209
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Konferensbidrag (refereegranskat)abstract
- Certain applications of fiber sensors (e.g. avionics, oil industry) imply extreme operating conditions spurring the development of hermetic all-fiber devices. We present a hermetic all-fiber phase modulator based on Joule heating in a carbon-coated fiber.
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| 6. |
- Jordan, Ralph, et al.
(författare)
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Decoding of woven convolutional codes and simulation results
- 2000
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Ingår i: [Host publication title missing]. - 0780358570 ; , s. 96-96
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Konferensbidrag (refereegranskat)abstract
- An iterative decoding scheme for woven convolutional codes is presented. It is called pipeline decoding and operates in a window sliding over the received sequence. This exploits the nature of convolutional codes as sequences and suits the concept of convolutional encoding and decoding as a continuous process. The pipeline decoder is analyzed in terms of decoding delay and decoding complexity. Additional interleaving for woven convolutional constructions is introduced by employing a convolutional scrambler. It is shown that some types of interleaving preserve the lower bound on the free distance of the original woven construction. Simulation results for woven convolutional codes are presented
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| 7. |
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| 8. |
- Magalhães, Regina, et al.
(författare)
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Distributed detection of quadratic Kerr effect in silica fibers using chirped-pulse φoTDR
- 2019
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Ingår i: Proceedings of SPIE - The International Society for Optical Engineering. - : SPIE. - 9781510631236 - 9781510631243
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Konferensbidrag (refereegranskat)abstract
- Monitoring the presence of external electric fields over large distances and detecting losses along power transmission networks, is of extreme importance nowadays due to concerns with environment, efficiency, cost and safety. In this work, we evaluate a method to achieve distributed measurements of the quadratic electro-optic Kerr effect in silica fibers in a distributed way. For this purpose, we integrate a twin-hole fiber filled with BiSn alloy electrodes and monitor its electric-field induced refractive index (RI) change Δn by using a chirped-pulse phase-sensitive OTDR (CP-ΦOTDR). By exploiting its high sensitivity (RI changes of the order of 10-9), we demonstrate that the proposed system is able to detect the intrinsic quadratic electrooptic nonlinearity (the electric Kerr effect) in the fiber, an effect that is usually considered to be too weak to be exploited for practical applications. Additionally, we show that the CP-ΦOTDR is sufficiently sensitive to measure the electric Kerr effect with untreated standard telecommunication fibers under realistic fields.
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| 9. |
- Ott, Jürgen, et al.
(författare)
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Cm and mm Survey of Molecular Absorption Lines in Centaurus A
- 2012
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Ingår i: American Astronomical Society, AAS Meeting. ; 219, s. 349.26-
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- We present Australia Telescope Array data of molecular absorption lines toward the bright central core of Centaurus A. The line of sight crosses the prominent dust lane and continues through the disk and eventually through gas that may be very close to the central supermassive black hole. The goal of our the survey is to determine the physical conditions of the gas via analyses of molecular line tracers including molecular abundances and excitation that is sensitive to changes in temperature, density, ionization, and shocks. This study allows us to derive the physical conditions of every absorption line complex and finally let us assign the most likely environments. We present ATCA data in the 20-50GHz range at medium resolution of a few km/s and possibly ALMA data at 3mm and 1mm wavelengths. The project continues with sub-km/s higher spectral resolution for the most important lines in 2012.
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