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Blob sizes and velocities in the Alcator C-Mod scrape-off layer
(Journal article; Tidsskriftartikkel; Peer reviewed, 2013)
Gas-puff imaging data is used to investigate the dynamics of blob-like structures in the scrape-off layer of Alcator C-Mod. A blob-tracking algorithm is developed and used to compute blob propagation velocities and cross-field sizes for a series of discharges where the line-averaged particle density View the MathML source is varied. We find that the mean radial blob velocity increases from View the ...
20 years of research on the Alcator C-Mod tokamak
(Journal article; Tidsskriftartikkel; Peer reviewed, 2014)
A Scatter-Based Prototype Framework and Multi-Class Extension of Support Vector Machines
(Journal article; Tidsskriftartikkel; Peer reviewed, 2012)
We provide a novel interpretation of the dual of support vector machines (SVMs) in terms of scatter with respect to class prototypes and their mean. As a key contribution, we extend this framework to multiple classes, providing a new joint Scatter SVM algorithm, at the level of its binary counterpart in the number of optimization variables. This enables us to implement computationally efficient ...
Secondary charging effects due to icy dust particle impacts on rocket payloads
(Journal article; Tidsskriftartikkel; Peer reviewed, 2012)
We report measurements of dust currents obtained with a small probe and a larger probe during the flight of the ECOMA-4 rocket through the summer polar mesosphere. The payload included two small dust probes behind a larger dust probe located centrally at the front. For certain phases of the payload rotation, the current registered by one of the small dust probes was up to 2 times the current measured ...
A Multitexture Model for Multilook Polarimetric Synthetic Aperture Radar Data
(Journal article; Tidsskriftartikkel; Peer reviewed, 2013)
A statistical model for multilook polarimetric radar data is presented where the polarimetric channels are associated with individual texture variables having potentially different statistical
properties. The feasibility of producing closed form probability density functions under certain restrictions is outlined.
Mellin kind statistics are derived under various assumptions on the texture variables, ...
An Advanced Non-Gaussian Feature Space Method for POL-SAR Image Segmentation
(Conference object; Konferansebidrag, 2013)
This work extends upon our simple feature-based multichannel SAR segmentation method to incorporate highly desirable statistical properties into a computationally simple
approach. The desirable properties include Markov random field contextual smoothing and goodness-of-fit testing to automatically obtain the significant number of classes. To achieve this we need to find an explicit class model to ...
Comparison of feature based segmentation of full polarimetric SAR satellite sea ice images with manually drawn ice charts
(Journal article; Tidsskriftartikkel; Peer reviewed, 2013)
In this paper we investigate the performance of
an algorithm for automatic segmentation of full polarimetric, synthetic aperture radar (SAR) sea ice scenes. The algorithm uses statistical and polarimetric properties of the backscattered radar signals to segment the SAR image into a specified number of classes. This number was determined in advance from visual inspection of the SAR image and by ...
A Textural–Contextual Model for Unsupervised Segmentation of Multipolarization Synthetic Aperture Radar Images
(Journal article; Tidsskriftartikkel; Peer reviewed, 2013)
This paper proposes a novel unsupervised, non-Gaussian, and contextual segmentation method that combines an advanced statistical distribution with spatial contextual informa-tion for multilook polarimetric synthetic aperture radar (PolSAR)data. This extends on previous studies that have shown the added value of both non-Gaussian modeling and contextual smoothing individually or for intensity channels ...
Agreement and Complementarity of Sea Ice Drift Products
(Journal article; Tidsskriftartikkel; Peer reviewed, 2016-01-08)
Changes in Arctic sea ice have raised questions about changes in sea ice drift patterns. Reduced sea ice coverage may open up the Arctic to further exploration of maritime activities, particularly during the summer months. Given such changes, it is important to investigate differences between available sea ice drift products. Products based on synthetic aperture radar (SAR), radar scatterometer, and ...
Muliggjørende teknologi og rammebetingelser
(Research report; Forskningsrapport, 2018-02-19)