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Viser treff 11-20 av 37
Optical transport, lifting and trapping of micro-particles by planar waveguides
(Journal article; Tidsskriftartikkel; Peer reviewed, 2015-03-03)
Optical waveguides can be used to trap and transport micro-particles. The particles are held close to the waveguide surface by the evanescent field and propelled forward. We propose a new technique to lift and trap particles above the surface of the waveguides. This is made possible by a gap between two opposing, planar waveguides. The field emitted from each of the waveguide ends diverge fast, away ...
An Automatic U-distribution and Markov Random Field Segmentation Algorithm for PolSAR Images
(Journal article; Tidsskriftartikkel; Peer reviewed, 2015)
Convergence of statistical moments of particle density time series in scrape-off layer plasmas
(Journal article; Tidsskriftartikkel; Peer reviewed, 2015)
On the relation between polarimetric synthetic aperture radar (SAR) features and sea ice melt pond fraction
(Journal article; Tidsskriftartikkel; Peer reviewed, 2015-11-12)
In this study we examine the relationship between sea ice melt pond fraction and two polarimetric C-band synthetic aperture radar (SAR) features. Three high-resolution SAR scenes were recorded in the Fram Strait in late summer 2011, covering iceberg-fast first-year and old sea ice. In addition, melt pond fraction was retrieved from photographs recorded during a helicopter flight at the study area. ...
Classification of low backscatter ocean regions using log-cumulants
(Conference object; Konferansebidrag, 2015-01)
In a synthetic aperture radar image, low backscatter regions of various origin can be observed in ocean areas.
Operational oil spill detection services work to discriminate anthropogenic oil spills from natural phenomena
such as seeps, low wind fields, thin ice and biogenic
slicks. In this paper, we investigate the potential of using matrix log-cumulants for this purpose.
Aspects of model-based decompositions in radar polarimetry
(Journal article; Tidsskriftartikkel; Peer reviewed, 2015-11-12)
In this paper, we further analyse the problem that polarimetric target decomposition methods in general have more physical parameters than equations, making the decomposition under-determined and hence have no unique solution. The common approach to get around this problem is to make certain assumptions, thus fixing one or more parameters, allowing the other free parameters to be solved from the set ...
Assessing polarimetric SAR sea-ice classifications using consecutive day images
(Journal article; Tidsskriftartikkel; Peer reviewed, 2015)
This paper investigates automatic segmentation and classification of C-band, polarimetric synthetic aperture radar (SAR) satellite images of Arctic sea ice under freezing conditions prior to melt. The objective is to investigate the robustness of the results obtained under slightly varying environmental conditions and different viewing geometries. Initially, three geographically overlapping SAR ...
Mesospheric temperatures and sodium properties measured with the ALOMAR Na lidar compared with WACCM
(Journal article; Tidsskriftartikkel; Peer reviewed, 2015-01-16)
We present a comparison of the temperature and sodium layer properties observed by the ALOMAR Na
lidar (69.3°N, 16.0°E) and simulated by the Whole Atmosphere Community Climate Model with specified
dynamics and implemented sodium chemistry (WACCM-Na). To constrain the meteorological fields
below 60 km, we use MERRA and GEOS-5. For the years 2008 to 2012, we analyse daily averages of
temperature ...
The science case for the EISCAT_3D radar
(Journal article; Tidsskriftartikkel; Peer reviewed, 2015-07-29)
The EISCAT (European Incoherent SCATer) Scientific Association has provided versatile incoherent scatter (IS) radar
facilities on the mainland of northern Scandinavia (the EISCAT UHF and VHF radar systems) and on Svalbard (the
electronically scanning radar ESR (EISCAT Svalbard Radar) for studies of the high-latitude ionised upper atmosphere
(the ionosphere). The mainland radars were constructed ...
Eastward-expanding auroral surges observed in the post-midnight sector during a multiple-onset substorm
(Journal article; Tidsskriftartikkel; Peer reviewed, 2015-11-09)
We present three eastward-expanding auroral surge (EEAS) events that were observed intermittently at intervals of
about 15 min in the post-midnight sector (01:55–02:40 MLT) by all-sky imagers and magnetometers in northern
Europe. It was deduced that each surge occurred just after each onset of a multiple-onset substorm, which was
small-scale and did not clearly expand westward, because they were ...