Fakultet for naturvitenskap og teknologi: Nye registreringer
Viser treff 2301-2320 av 5336
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Snow and Ice Thickness Retrievals Using GNSS-R: Preliminary Results of the MOSAiC Experiment
(Journal article; Tidsskriftartikkel; Peer reviewed, 2020-12-10)The FSSCat mission was the 2017 ESA Sentinel Small Satellite (S⌃3) Challenge winner and the Copernicus Masters competition overall winner. It was successfully launched on 3 September 2020 onboard the VEGA SSMS PoC (VV16). FSSCat aims to provide coarse and downscaled soil moisture data and over polar regions, sea ice cover, and coarse resolution ice thickness using a combined L-band microwave radiometer ... -
Rapid temperature rise may have triggered glacier surges all over Svalbard
(Mastergradsoppgave; Master thesis, 2020-05-04)Observational and geomorphological records suggest that most glaciers on Svalbard reached their maximum Little Ice Age extents by means of surging. Furthermore, it seems to have happened within just a few decades, suggesting that the rapid concurrent changes in climate might have triggered this widespread surging. The specific precipitation and temperature range of Svalbard seems optimal for glacier ... -
Hyperspectral Nonlinear Unmixing by Using Plug-and-Play Prior for Abundance Maps
(Journal article; Tidsskriftartikkel; Peer reviewed, 2020-12-16)Spectral unmixing (SU) aims at decomposing the mixed pixel into basic components, called endmembers with corresponding abundance fractions. Linear mixing model (LMM) and nonlinear mixing models (NLMMs) are two main classes to solve the SU. This paper proposes a new nonlinear unmixing method base on general bilinear model, which is one of the NLMMs. Since retrieving the endmembers’ abundances represents ... -
Rhenium-Imido Corroles
(Journal article; Tidsskriftartikkel; Peer reviewed, 2020-04-10)Metallocorroles involving 5d transition metals are currently of interest as near-IR phosphors and as photosensitizers for oxygen sensing and photodynamic therapy. Their syntheses, however, are often bedeviled by capricious and low-yielding protocols. Against this backdrop, we describe rhenium-imido corroles, a new class of 5d metallocorroles, synthesized simply and in respectable (∼30%) yields via ... -
Millstone Hill ISR Measurements of Small Aspect Angle Spectra
(Journal article; Tidsskriftartikkel; Peer reviewed, 2020-05-04)The Millstone Hill incoherent scatter (IS) radar is used to measure spectra close to perpendicular to the Earth's magnetic field, and the data are fit to three different forward models to estimate ionospheric temperatures. IS spectra measured close to perpendicular to the magnetic field are heavily influenced by Coulomb collisions, and the temperature estimates are sensitive to the collision operator ... -
Joint Invariants of Linear Symplectic Actions
(Journal article; Tidsskriftartikkel; Peer reviewed, 2020-12-07)We review computations of joint invariants on a linear symplectic space, discuss variations for an extension of group and space and relate this to other equivalence problems and approaches, most importantly to differential invariants. -
Automatic Grading of Retinal Blood Vessel in Deep Retinal Image Diagnosis
(Journal article; Tidsskriftartikkel; Peer reviewed, 2020-09-01)Automatic grading of retinal blood vessels from fundus image can be a useful tool for diagnosis, planning and treatment of eye. Automatic diagnosis of retinal images for early detection of glaucoma, stroke, and blindness is emerging in intelligent health care system. The method primarily depends on various abnormal signs, such as area of hard exudates, area of blood vessels, bifurcation points, ... -
Differential Invariants of Linear Symplectic Actions
(Journal article; Tidsskriftartikkel; Peer reviewed, 2020-12-07)We consider the equivalence problem for symplectic and conformal symplectic group actions on submanifolds and functions of symplectic and contact linear spaces. This is solved by computing differential invariants via the Lie-Tresse theorem. -
The Structure of Climate Variability Across Scales
(Journal article; Tidsskriftartikkel; Peer reviewed, 2020-03-05)One of the most intriguing facets of the climate system is that it exhibits variability across all temporal and spatial scales; pronounced examples are temperature and precipitation. The structure of this variability, however, is not arbitrary. Over certain spatial and temporal ranges, it can be described by scaling relationships in the form of power laws in probability density distributions and ... -
Organometallic Chemistry for Enabling Carbon Dioxide Utilization
(Journal article; Tidsskriftartikkel; Peer reviewed, 2020-05-11)<p>In photosynthesis, carbon dioxide is used as the carbon source; indeed, most carbon atoms in the structure of a massive tree—the trunk, the branches, the leaves—originate from CO2. This insight has profound implications for chemical synthesis: complex molecular structures are built from something as simple and inert as CO<sub>2</sub>. Scientists have long been fascinated by this concept, and ... -
Person Re-identification in Videos by Analyzing Spatio-temporal Tubes
(Journal article; Tidsskriftartikkel; Peer reviewed, 2020-06-23)Typical person re-identification frameworks search for <i>k</i> best matches in a gallery of images that are often collected in varying conditions. The gallery usually contains image sequences for video re-identification applications. However, such a process is time consuming as video re-identification involves carrying out the matching process multiple times. In this paper, we propose a new method ... -
Capacity and Limits of Multimodal Remote Sensing: Theoretical Aspects and Automatic Information Theory-Based Image Selection
(Journal article; Tidsskriftartikkel; Peer reviewed, 2020-08-17)Although multimodal remote sensing data analysis can strongly improve the characterization of physical phenomena on Earth's surface, nonidealities and estimation imperfections between records and investigation models can limit its actual information extraction ability. In this article, we aim at predicting the maximum information extraction that can be reached when analyzing a given data set. By ... -
A Novel Rayleigh Dynamical Model for Remote Sensing Data Interpretation
(Journal article; Tidsskriftartikkel; Peer reviewed, 2020-02-19)This article introduces the Rayleigh autoregressive moving average (RARMA) model, which is useful to interpret multiple different sets of remotely sensed data, from wind measurements to multitemporal synthetic aperture radar (SAR) sequences. The RARMA model is indeed suitable for continuous, asymmetric, and nonnegative signals observed over time. It describes the mean of Rayleigh-distributed ... -
Comparison of Machine Learning Methods for Predicting Quad-Polarimetric Parameters from Dual-Polarimetric SAR Data
(Journal article; Tidsskriftartikkel; Peer reviewed, 2021-02-17)This paper addresses the problem of up-scaling full polarimetric (quad-pol) parameters from small quad-pol synthetic aperture radar (SAR) scenes to large dual-pol scenes, using a sophisticated Machine Learning (ML) method, namely the Gaussian Process Regression (GPR). The approach is to let the GPR model learn the relationships between the dual-pol input data and the quad-pol parameters on a quad-pol ... -
The fate of plastic in the ocean environment – a minireview
(Journal article; Tidsskriftartikkel; Peer reviewed, 2021-01-14)The presence of plastics in the marine environment poses a threat to ocean life and has received much scientific and public attention in recent years. Plastics were introduced to the market in the 1950s and since then, global production figures and ocean plastic littering have increased exponentially. Of the 359 million tonnes (Mt) produced in 2018, an estimated 14.5 Mt has entered the ocean. In ... -
Deformation Behavior and Inferred Seismic Properties of Tonalitic Migmatites at the Time of Pre‐melting, Partial Melting, and Post‐Solidification
(Journal article; Tidsskriftartikkel, 2021-01-21)As seismic data from the lower crust becomes more readily available, it is important to link seismic properties to the ongoing processes within lower crustal evolution. This includes high temperature, pre‐ and post‐migmatization solid state deformation as well as melt‐present deformation. We selected two tonalitic migmatites with variable former melt content (one metatexite and one diatexite) from ... -
Evidence for influx of Atlantic water masses to the Labrador Sea during the Last Glacial Maximum
(Journal article; Tidsskriftartikkel; Peer reviewed, 2021-03-21)The Last Glacial Maximum (LGM, 23–19,000 year BP) designates a period of extensive glacial extent and very cold conditions on the Northern Hemisphere. The strength of ocean circulation during this period has been highly debated. Based on investigations of two marine sediment cores from the Davis Strait (1033 m water depth) and the northern Labrador Sea (2381 m), we demonstrate a significant influx ... -
Insights into the REY inventory of seep carbonates from the Northern Norwegian margin using geochemical screening
(Journal article; Tidsskriftartikkel; Peer reviewed, 2020-08-27)Rare earth element and yttrium (REY) systematics of authigenic seep carbonates can provide insights into the physico-chemical characteristics of seep systems and allow discrimination of carbonate precipitation under seawater- or porewater-dominated fluid regimes. However, care must be taken when interpreting their REY systematics, since seep carbonates comprise a mixture of detrital silicates and ... -
Multiscale characterisation of chimneys/pipes: Fluid escape structures within sedimentary basins
(Journal article; Tidsskriftartikkel; Peer reviewed, 2021-02-19)Evaluation of seismic reflection data has identified the presence of fluid escape structures cross-cutting overburden stratigraphy within sedimentary basins globally. Seismically-imaged chimneys/pipes are considered to be possible pathways for fluid flow, which may hydraulically connect deeper strata to the seabed. The properties of fluid migration pathways through the overburden must be constrained ... -
Rethinking the role of solar energy under location specific constraints
(Journal article; Tidsskriftartikkel; Peer reviewed, 2020-09-22)In this manuscript we evaluate the potential of photovoltaic systems to meet some dedicated energy demand in specific geographic locations. Our approach is based on location-specific constraints rather than on pre-established, location-independent methodologies or assumptions. First, we propose that a thorough analysis of the socio-economic and technical possibilities of a location must act as the ...