637 research outputs found
The magnetic environment of the Orion-Eridanus superbubble as revealed by Planck
Using the 353-GHz polarization observations by the Planck satellite we
characterize the magnetic field in the Orion-Eridanus superbubble, a nearby
expanding structure that spans more than 1600 square degrees in the sky. We
identify a region of both low dispersion of polarization orientations and high
polarization fraction associated with the outer wall of the superbubble
identified in the most recent models of the large-scale shape of the region. We
use the Davis-Chandrasekhar-Fermi method to derive plane-of-the-sky magnetic
field strengths of tens of microGauss toward the southern edge of the bubble.
The comparison of these values with existing Zeeman splitting observations of
HI in emission suggests that the large-scale magnetic field in the region was
primarily shaped by the expanding superbubble.Comment: 7 pages, 8 figures. Accepted for publication as a Letter in A&A,
section 1. Letters to the Editor (08/12/2017
Mid-J CO Shock Tracing Observations of Infrared Dark Clouds I
Infrared dark clouds (IRDCs) are dense, molecular structures in the
interstellar medium that can harbour sites of high-mass star formation. IRDCs
contain supersonic turbulence, which is expected to generate shocks that
locally heat pockets of gas within the clouds. We present observations of the
CO J = 8-7, 9-8, and 10-9 transitions, taken with the Herschel Space
Observatory, towards four dense, starless clumps within IRDCs (C1 in
G028.37+00.07, F1 and F2 in G034.43+0007, and G2 in G034.77-0.55). We detect
the CO J = 8-7 and 9-8 transitions towards three of the clumps (C1, F1, and F2)
at intensity levels greater than expected from photodissociation region (PDR)
models. The average ratio of the 8-7 to 9-8 lines is also found to be between
1.6 and 2.6 in the three clumps with detections, significantly smaller than
expected from PDR models. These low line ratios and large line intensities
strongly suggest that the C1, F1, and F2 clumps contain a hot gas component not
accounted for by standard PDR models. Such a hot gas component could be
generated by turbulence dissipating in low velocity shocks.Comment: 14 pages, 8 figures, 5 tables, accepted by A&A, minor updates to
match the final published versio
Object-Centric Stereo Matching for 3D Object Detection
Safe autonomous driving requires reliable 3D object detection-determining the
6 DoF pose and dimensions of objects of interest. Using stereo cameras to solve
this task is a cost-effective alternative to the widely used LiDAR sensor. The
current state-of-the-art for stereo 3D object detection takes the existing
PSMNet stereo matching network, with no modifications, and converts the
estimated disparities into a 3D point cloud, and feeds this point cloud into a
LiDAR-based 3D object detector. The issue with existing stereo matching
networks is that they are designed for disparity estimation, not 3D object
detection; the shape and accuracy of object point clouds are not the focus.
Stereo matching networks commonly suffer from inaccurate depth estimates at
object boundaries, which we define as streaking, because background and
foreground points are jointly estimated. Existing networks also penalize
disparity instead of the estimated position of object point clouds in their
loss functions. We propose a novel 2D box association and object-centric stereo
matching method that only estimates the disparities of the objects of interest
to address these two issues. Our method achieves state-of-the-art results on
the KITTI 3D and BEV benchmarks.Comment: Accepted in ICRA 202
Recommended from our members
METADATA REGISTRY, ISO/IEC 11179
ISO/IEC-11179 is an international standard that documents the standardization and registration of metadata to make data understandable and shareable. This standardization and registration allows for easier locating, retrieving, and transmitting data from disparate databases. The standard defines the how metadata are conceptually modeled and how they are shared among parties, but does not define how data is physically represented as bits and bytes. The standard consists of six parts. Part 1 provides a high-level overview of the standard and defines the basic element of a metadata registry - a data element. Part 2 defines the procedures for registering classification schemes and classifying administered items in a metadata registry (MDR). Part 3 specifies the structure of an MDR. Part 4 specifies requirements and recommendations for constructing definitions for data and metadata. Part 5 defines how administered items are named and identified. Part 6 defines how administered items are registered and assigned an identifier
Progress of the National Air Quality Cooperation Programme (NSL)
Om de luchtkwaliteit in Nederland te verbeteren is het Nationaal Samenwerkingsprogramma Luchtkwaliteit (NSL) opgezet. In dit programma werken de Rijksoverheid en decentrale overheden samen om te zorgen dat Nederland overal tijdig aan de grenswaarden voor fijnstof (2011) en stikstofdioxide (2015) zal voldoen. Om de voortgang te volgen is bij het NSL een monitoringsprogramma opgezet. Centraal onderdeel daarvan is een rekeninstrument waarvoor de overheden de brongegevens aanleveren. De daaruitvolgende rekenresultaten zijn vervolgens door het Bureau Monitoring (samenwerkingsverband RIVM en InfoMil) samengevoegd in voorliggende voortgangsrapportage. De prognoses voor 2011 en 2015 laten zien dat voor een groot deel van Nederland de resultaten onder de Europese grenswaarden voor PM10 (fijnstof) en NO2 liggen. Op een aantal plekken zijn er wel nieuwe of grotere overschrijdingen van de PM10- en NO2-grenswaarden zichtbaar. Bij de fijnstof (PM10) overschrijdingen gaat het hoofdzakelijk om locaties bij veehouderijen en een aantal industriele gebieden. Vooral nabij veehouderijen is op een aantal plekken nog sprake van grote overschrijdingen die lastig voor medio 2011 op te lossen zijn. De huidige prognose voor de concentraties stikstofdioxide in 2015 laat een minder gunstige ontwikkeling zien ten opzichte van wat is berekend in de vaststelling van het NSL. Dit komt voor een belangrijk deel door tegenvallende verkeersemissies wat heeft geleid tot een aantal nieuwe overschrijdingen. De nu in de prognoses berekende concentraties liggen op veel locaties net onder de grenswaarde. Met veel concentraties net onder de grenswaarde neemt het aantal overschrijdingen snel toe bij een tegenvaller in een van de gemaakte aannamen. In combinatie met een grote en deels onbekende onzekerheid in de rekenresultaten vormt dit een risico voor het behalen van de doelstelling van het NSL.The NSL has been put in place to improve air quality in the Netherlands and to ensure that the Netherlands meets the date of compliance with the EU limit values for particulate matter and nitrogen dioxide. Local, regional and national authorities work together within the framework of this programme to ensure that these goals are met. A monitoring programme, centred around a specially designed assessment tool, has been set up to monitor the progress. This tool uses data that the participating authorities are required to provide as part of the annual monitoring cycle. The results of the tool have been bundled by the Bureau Monitoring into this progress report. The prognosis for 2011 and 2015, based on the results obtained using the assessment tool, are that the concentrations of PM10 and NO2 fall below the EU limit values in most parts of the Netherlands. However, exceedances of the limit values do occur at specific locations. For PM10, these exceedances mostly occur close to a number of industrial sites and stock farms. Particularly high exceedances in the vicinity of these stock farms will make it difficult to meet the limit values by mid 2011 at these locations. The prognostications for NO2 show a less favourable decline in NO2 concentrations than was modelled at the establishment of the NSL. This is mostly due to the decline in traffic emissions falling short of expectations, resulting in new exceedances. At many locations, the calculated concentrations in the prognostications fall just under the limit value and, consequently, there will be a large increase in the number of exceedances when one or more of the premises become less favourable. This possibility, together with the large and partially unknown uncertainty in the calculation results, add up to a risk for not meeting the limit values by the date of compliance.VRO
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