Institutt for fysikk og teknologi: Nye registreringer
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Transmission structured illumination microscopy with tunable frequency illumination using tilt mirror assembly
(Journal article; Tidsskriftartikkel; Peer reviewed, 2023-01-26)We present experimental demonstration of tilt-mirror assisted transmission structured illumination microscopy (tSIM) that offers a large field of view super resolution imaging. An assembly of custom-designed tilt-mirrors are employed as the illumination module where the sample is excited with the interference of two beams reflected from the opposite pair of mirror facets. Tunable frequency structured ... -
Stiffness tensor estimation of anisotropic crystal using point contact method and unscented Kalman filter
(Journal article; Tidsskriftartikkel; Peer reviewed, 2023-02-02)The potential application of Lithium Niobate (LiNbO3) crystal is immense, specifically in the domain of metasurfaces and nano-resonators. However, the practical application of LiNbO<sub>3</sub> is impeded due to unreliable experimental techniques and inaccurate inversion algorithms for material characterization. In the current research, material characterization of anisotropic crystal is proposed ... -
Image inpainting in acoustic microscopy
(Journal article; Tidsskriftartikkel; Peer reviewed, 2023-04-27)Scanning acoustic microscopy (SAM) is a non-ionizing and label-free imaging modality used to visualize the surface and internal structures of industrial objects and biological specimens. The image of the sample under investigation is created using high-frequency acoustic waves. The frequency of the excitation signals, the signal-to-noise ratio, and the pixel size all play a role in acoustic image ... -
A clinically motivated self-supervised approach for content-based image retrieval of CT liver images
(Journal article; Tidsskriftartikkel; Peer reviewed, 2023-05-09)Deep learning-based approaches for content-based image retrieval (CBIR) of computed tomography (CT) liver images is an active field of research, but suffer from some critical limitations. First, they are heavily reliant on labeled data, which can be challenging and costly to acquire. Second, they lack transparency and explainability, which limits the trustworthiness of deep CBIR systems. We address ... -
Highly sensitive quantitative phase microscopy and deep learning aided with whole genome sequencing for rapid detection of infection and antimicrobial resistance
(Journal article; Tidsskriftartikkel; Peer reviewed, 2023-04-12)Current state-of-the-art infection and antimicrobial resistance (AMR) diagnostics are based on culture-based methods with a detection time of 48–96 h. Therefore, it is essential to develop novel methods that can do real-time diagnoses. Here, we demonstrate that the complimentary use of label-free optical assay with whole-genome sequencing (WGS) can enable rapid diagnosis of infection and AMR. Our ... -
The Departure from Mixed-Layer Similarity During the Afternoon Decay of Turbulence in the Free-Convective Boundary Layer: Results from Large-Eddy Simulations
(Journal article; Tidsskriftartikkel; Peer reviewed, 2023-06-21)This study analyses the departure of the velocity-variances profiles from their quasi-steady state described by the mixed-layer similarity, using large-eddy simulations with different prescribed shapes and time scales of the surface kinematic heat flux decay. Within the descriptive frames where the time is tracked solely by the forcing time scale (either constant or time-dependent) describing the ... -
Extreme Horizontal Wind Perturbations in the Mesosphere and Lower Thermosphere Over South America Associated With the 2022 Hunga Eruption
(Journal article; Tidsskriftartikkel; Peer reviewed, 2023-06-13)On 15 January 2022, the Hunga volcano produced a massive explosion that generated perturbations in the entire atmosphere. Nonetheless, signatures in the mesosphere and lower thermosphere (MLT) have been challenging to identify. We report MLT horizontal wind perturbations using three multistatic specular meteor radars on the west side of South America (spanning more than 3,000 km). The most ... -
Sea Ice Remote Sensing—Recent Developments in Methods and Climate Data Sets
(Journal article; Tidsskriftartikkel; Peer reviewed, 2023-04-03)Sea ice monitoring by polar orbiting satellites has been developed over more than four decades and is today one of the most well-established applications of space observations. This article gives an overview of data product development from the first sensors to the state-of-the-art regarding retrieval methods, new products and operational data sets serving climate monitoring as well as daily operational ... -
Single-Molecule Sizing through Nanocavity Confinement
(Journal article; Tidsskriftartikkel; Peer reviewed, 2023-02-24): An approach relying on nanocavity confinement is developed in this paper for the sizing of nanoscale particles and single biomolecules in solution. The approach, termed nanocavity diffusional sizing (NDS), measures particle residence times within nanofluidic cavities to determine their hydrodynamic radii. Using theoretical modeling and simulations, we show that the residence time of particles ... -
Solved and unsolved riddles about low-latitude daytime valley region plasma waves and 150-km echoes
(Journal article; Tidsskriftartikkel; Peer reviewed, 2023-02-27)The Earth’s atmosphere near both the geographic and magnetic equators and at altitudes between 120 and 200 km is called the low-latitude valley region (LLVR) and is among the least understood regions of the ionosphere/thermosphere due to its complex interplay of neutral dynamics, electrodynamics, and photochemistry. Radar studies of the region have revealed puzzling daytime echoes scattered from ... -
Efficient Fuel Consumption Minimization for Green Vehicle Routing Problems using a Hybrid Neural Network-Optimization Algorithm
(Master thesis; Mastergradsoppgave, 2023-06-01)Efficient routing optimization yields benefits that extend beyond mere financial gains. In this thesis, we present a methodology that utilizes a graph convolutional neural network to facilitate the development of energy-efficient waste collection routes. Our approach focuses on a Waste company in Tromsø, Remiks, and uses real-life datasets, ensuring practicability and ease of implementation. In ... -
Wind resource assessment and siting for the expansion of Fakken wind park
(Master thesis; Mastergradsoppgave, 2023-05-31)Norway is anticipated to experience an energy deficit in the coming years, and one solution to address this issue is the implementation of new renewable energy sources. To mitigate the projected energy deficit, increased energy production is required. With its considerable wind potential, the country offers ample opportunities for wind energy development. Consequently, there is a growing demand for ... -
RELAX: Representation Learning Explainability
(Journal article; Tidsskriftartikkel; Peer reviewed, 2023-03-11)Despite the significant improvements that self-supervised representation learning has led to when learning from unlabeled data, no methods have been developed that explain what influences the learned representation. We address this need through our proposed approach, RELAX, which is the first approach for attribution-based explanations of representations. Our approach can also model the uncertainty ... -
Preconditioning of Summer Melt Ponds From Winter Sea Ice Surface Temperature
(Journal article; Tidsskriftartikkel; Peer reviewed, 2023-02-22)Comparing helicopter-borne surface temperature maps in winter and optical orthomosaics in summer from the year-long Multidisciplinary drifting Observatory for the Study of Arctic Climate expedition, we find a strong geometric correlation between warm anomalies in winter and melt pond location the following summer. Warm anomalies are associated with thinner snow and ice, that is, surface depression ... -
Optimal sizing and placement of Electrical Vehicle charging stations to serve Battery Electric Trucks
(Master thesis; Mastergradsoppgave, 2023-06-01)For Norway to reach the emission limits in the Paris Agreement, a substantial amount of CO2 must be reduced. Road traffic alone accounts for a high percentage of the total emissions during 2021. This thesis will focus on electrifying the transport sector and analyzing charging infrastructure for heavy-duty electric vehicles. New charging infrastructure for heavy-duty Electric Vehicles (EVs) provides ... -
Smart Senja electrical network expansion modeling
(Master thesis; Mastergradsoppgave, 2023-05-30)The addition of variable renewable energy sources into the electrical energy systems of the world has been increasing in recent years. This form of distributed energy production with high production volatility can introduce massive challenges in operating a lower voltage distribution network. One of these affected networks is on the island of Senja in northern Norway, with an eldering radial electrical ... -
Probabilistic Wind Power Forecasting with Deep Neural Sequence Models
(Master thesis; Mastergradsoppgave, 2023-05-27)As the world strives to fulfill the goal of zero-emission established during the Paris agreement, an increasing amount of wind power is integrated into the liberalized electricity markets. With this escalation comes the need for wind power forecasting (WPF) due to the intermittent nature of wind, and WPF is therefore becoming an important field of study to successfully incorporate wind power to the ... -
Comparing quality of breast cancer care in the Netherlands and Norway by federated propensity score analytics
(Journal article; Tidsskriftartikkel; Peer reviewed, 2023-06-05)Purpose - The aim of the study was to benchmark and compare breast cancer care quality indicators (QIs) between Norway and the Netherlands using federated analytics preventing transfer of patient-level data.<p> <p>Methods - Breast cancer patients (2017–2018) were retrieved from the Netherlands Cancer Registry and the Cancer Registry of Norway. Five European Society of Breast Cancer Specialists ... -
Predicting Regions of Local Recurrence in Glioblastomas Using Voxel-Based Radiomic Features of Multiparametric Postoperative MRI
(Journal article; Tidsskriftartikkel; Peer reviewed, 2023-03-22)The globally accepted surgical strategy in glioblastomas is removing the enhancing tumor. However, the peritumoral region harbors infiltration areas responsible for future tumor recurrence. This study aimed to evaluate a predictive model that identifies areas of future recurrence using a voxel-based radiomics analysis of magnetic resonance imaging (MRI) data. This multi-institutional study included ... -
Energy budget diagnosis of changing climate feedback
(Journal article; Tidsskriftartikkel; Peer reviewed, 2023-04-21)The climate feedback determines how Earth’s climate responds to anthropogenic forcing. It is thought to have been more negative in recent decades due to a sea surface temperature “pattern effect,” whereby warming is concentrated in the western tropical Pacific, where nonlocal radiative feedbacks are very negative. This phenomenon has however primarily been studied within climate models. We diagnose ...