Nye registreringer

  • Correlation between Wettability and Dissolution of Calcite in Ion-Free Water 

    AlMahri, Mariam; Lu, Jin-You; Chen, Shih-Wen; Olukan, Tuza Adeyemi; Yang, Thomas Chung-Kuang; Alhassan, Saeed; Chiesa, Matteo (Journal article; Tidsskriftartikkel; Peer reviewed, 2024-03-13)
    Calcite, a prevalent mineral in the earth’s crust, plays a pivotal role in various geological and industrial processes, including carbon sequestration, water treatment, and enhanced oil recovery. Understanding how wettability (a crucial surface property influenced by the interaction between calcite and surrounding fluids) affects calcite’s dissolution is essential for optimizing these processes. We ...
  • On the strength of E and F region irregularities for GNSS scintillation in the dayside polar ionosphere 

    Madhanakumar, Mahith; Spicher, Andres; Vierinen, Juha-Pekka; Oksavik, Kjellmar (Journal article; Tidsskriftartikkel; Peer reviewed, 2024-03-02)
    We present results of the study conducted to quantify the relative contribution of different ionospheric regions to phase scintillation in Global Navigation Satellite Systems (GNSS) at the dayside high latitude ionosphere. By taking advantage of the scanning capability of the 32-m EISCAT radar in Svalbard (ESR) and its recurrent favourable location below the dayside auroral region, we developed ...
  • Simultaneous electrochemical determination of benzenediol compounds in environmental samples using nano architectures of hydrogen ammonium zinc molybdate layered double hydroxides integrated with carbon black modified electrode 

    Karuppiah, Chelladurai; Babulal, Sivakumar Musuvadhi; Chen, Shen-Ming; Palanisamy, Selvakumar; Hsu, Li-Fan; Yang, Chun-Chen; Chiesa, Matteo (Journal article; Tidsskriftartikkel; Peer reviewed, 2023-09-02)
    Phenolic compounds, such as benzenediol (BD), are toxic and exhibit poor biodegradability, posing a threat to human health and the environment, even at low concentrations. Therefore, the simultaneous detection of BD at low detection limits and a wide detection range is of significant interest for monitoring water quality and environmental remediation efforts. In this study, we developed a novel ...
  • Quantification of van der Waals forces in bimodal and trimodal AFM 

    Santos Hernandez, Sergio; Gadelrab, Karim; Elsherbiny, Lamiaa; Drexler, Xaver; Olukan, Tuza Adeyemi; Font, Josep; Barcons, Victor; Chiesa, Matteo (Journal article; Tidsskriftartikkel; Peer reviewed, 2023-05-22)
    The multifrequency formalism is generalized and exploited to quantify attractive forces, i.e., van der Waals interactions, with small amplitudes or gentle forces in bimodal and trimodal atomic force microscopy (AFM). The multifrequency force spectroscopy formalism with higher modes, including trimodal AFM, can outperform bimodal AFM for material property quantification. Bimodal AFM with the second ...
  • Quasi Monte Carlo time-frequency analysis 

    Levie, Ron; Avron, Haim; Kutyniok, Gitta Astrid Hildegard (Journal article; Tidsskriftartikkel; Peer reviewed, 2022-09-30)
    We study signal processing tasks in which the signal is mapped via some generalized time-frequency transform to a higher dimensional time-frequency space, processed there, and synthesized to an output signal. We show how to approximate such methods using a quasi-Monte Carlo (QMC) approach. We consider cases where the time-frequency representation is redundant, having feature axes in addition to the ...
  • Efficient photoelectrocatalytic degradation of amoxicillin using nano-TiO<inf>2</inf> photoanode thin films: A comparative study with photocatalytic and electrocatalytic methods 

    Alaydaroos, Alia Husain; Sydorenko, Jekaterina; Palanisamy, Selvakumar; Chiesa, Matteo; Al Hajri, Ebrahim (Journal article; Tidsskriftartikkel; Peer reviewed, 2023-07-24)
    Excessive utilization of antibiotics in human, animal, and aquaculture poses a substantial threat to human health and the environment. Photoelectrochemical processes are increasingly applied for water remediation because they generate oxidizing species and mineralize organic pollutants, making even small water quantities more amenable for utilization. Thus, this study presents the fabrication of an ...
  • Estimating the Space Debris Density Function using Radar Beam Park Measurements 

    Vierinen, Juha; Hermann, Frank; Kastinen, Daniel; Kero, Johan; Markkanen, Jussi; Grydeland, Tom (Journal article; Tidsskriftartikkel; Peer reviewed, 2023)
    Estimating the density of space debris as a function of orbital elements and size is crucial for determining the risk of collision of spacecraft. For objects 1 cm or larger in diameter, this information can be obtained using beam park observations made with powerful ground based radars. This study presents a novel technique for estimating the density of space debris as a function of orbital elements ...
  • Radar size inference from statistics of RCS samples 

    Anfinsen, Stian Normann; Grydeland, Tom; Vierinen, Juha; Kastinen, Daniel; Ricker, Robert; Arntzen, Ingar M; Kero, J.; Høgda, Kjell Arild (Journal article; Tidsskriftartikkel; Peer reviewed, 2023)
    Radar Beam-park experiments have been very successful in characterizing the distribution of space debris objects, both in terms of orbital parameters but also in terms of limiting the estimates of their radar cross section, or RCS. A recent paper \[0\] used observed range and range rates to refine orbit estimates by matching up the observed SNR curve to that predicted by simulations. This gives good ...
  • ProtoVAE: A Trustworthy Self-Explainable Prototypical Variational Model 

    Gautam, Srishti; Boubekki, Ahcene; Hansen, Stine; Salahuddin, Suaiba Amina; Jenssen, Robert; Hohne, Marina Marie-Claire; Kampffmeyer, Michael (Journal article; Tidsskriftartikkel; Peer reviewed, 2022-10-15)
    The need for interpretable models has fostered the development of self-explainable classifiers. Prior approaches are either based on multi-stage optimization schemes, impacting the predictive performance of the model, or produce explanations that are not transparent, trustworthy or do not capture the diversity of the data. To address these shortcomings, we propose ProtoVAE, a variational autoencoder-based ...
  • Synthetic wavelength scanning interferometry for 3D surface profilometry with extended range of height measurement using multi-colour LED light sources 

    Mann, Priyanka; Dubey, Vishesh Kumar; Ahmad, Azeem; Butola, Ankit; Mehta, Dalip Singh (Journal article; Tidsskriftartikkel; Peer reviewed, 2023-04-05)
    We report three-dimensional surface profilometry with extended range of height measurements using synthetic wavelength scanning interferometry without tunable filters, wavelength-tuning lasers, grating elements. We have used inexpensive multiple colour light emitting diodes (LEDs) and operate them sequentially one by one or combination of two or more colours simultaneously to visualize synthetic ...
  • Data Augmentation for SAR Sea Ice and Water Classification Based on Per-Class Backscatter Variation With Incidence Angle 

    WANG, QIANG; Lohse, Johannes; Doulgeris, Anthony Paul; Eltoft, Torbjørn (Journal article; Tidsskriftartikkel; Peer reviewed, 2023-07-03)
    Monitoring sea ice in polar regions is critical for understanding global climate change and supporting marine navigation. Recently, researchers started to utilize machine/deep learning methodologies to automate the separation of sea ice and open water in synthetic aperture radar imagery. However, this requires a large amount of reliably labeled training data. We here propose an augmentation routine ...
  • Airborne Investigation of Quasi-Specular Ku-Band Radar Scattering for Satellite Altimetry Over Snow-Covered Arctic Sea Ice 

    de Rijke Thomas, Claude; Landy, Jack Christopher; Mallett, Robbie; Willatt, Rosemary; Tsamados, Michel; King, Joshua (Journal article; Tidsskriftartikkel; Peer reviewed, 2023-09-22)
    Surface-based Ku-band radar altimetry investigations indicate that the radar signal is typically backscattered from well above the snow–sea ice interface. However, this would induce a bias in satellite altimeter sea ice thickness retrievals not reflected by buoy validation. Our study presents a mechanism to potentially explain this paradox: probabilistic quasi-specular radar scattering from the ...
  • On the Control of Northern Hemispheric Feedbacks by AMOC: Evidence from CMIP and Slab Ocean Modeling 

    Eiselt, Kai-Uwe; Graversen, Rune Grand (Journal article; Tidsskriftartikkel; Peer reviewed, 2023-09-06)
    The climate sensitivity of Earth and the radiative climate feedback both change over time as a result of a so-called “pattern effect,” i.e., changing patterns of surface warming. This is suggested by numerical climate model experiments. The Atlantic meridional overturning circulation (AMOC) influences surface warming patterns as it redistributes energy latitudinally. Thus, this ocean circulation may ...
  • Changes in the North Pacific Jet Stream in Recent Decades 

    Alizadeh, Omid; Babaei, Morteza (Journal article; Tidsskriftartikkel; Peer reviewed, 2023-11-25)
    Changes in the path and intensity of jet streams have major impacts on regional weather and climate patterns. We investigated changes in the intensity, meridional position, and altitude of the North Pacific jet in different seasons during the period 1979–2020 using the European Centre for Medium-Range Weather Forecasts (ECMWF) fifth-generation reanalysis (ERA5) dataset. Our analysis indicates that ...
  • Single-shot multispectral quantitative phase imaging of biological samples using deep learning 

    Bhatt, Sunil; Butola, Ankit; Kumar, Anand; Thapa, Pramila; Joshi, Akshay; Jadhav, Suyog S.; Singh, Neetu; Prasad, Dilip K.; Agarwal, Krishna; Mehta, Dalip Singh (Journal article; Tidsskriftartikkel; Peer reviewed, 2023-05-16)
    Multispectral quantitative phase imaging (MS-QPI) is a high-contrast label-free technique for morphological imaging of the specimens. The aim of the present study is to extract spectral dependent quantitative information in single-shot using a highly spatially sensitive digital holographic microscope assisted by a deep neural network. There are three different wavelengths used in our method: 𝜆=532 , ...
  • The Distribution of Small-Scale Irregularities in the E-Region, and Its Tendency to Match the Spectrum of Field-Aligned Current Structures in the F-Region 

    Ivarsen, Magnus Fagernes; Lozinsky, Adam; St-Maurice, Jean-Pierre; Spicher, Andres; Huyghebaert, Devin Ray; Hussey, Glenn C.; Galeschuk, Draven; Pitzel, Brian; Vierinen, Juha (Journal article; Tidsskriftartikkel; Peer reviewed, 2023-04-16)
    We associate new data from icebear, a coherent scatter radar located in Saskatchewan, Canada, with scale-dependent physics in the ionosphere. We subject the large-scale icebear 3D echo patterns (treated as 2D point clouds) to a data analysis technique hitherto never applied to the ionosphere, a technique that is widely applied in cosmological red-shift surveys to characterize the spatial clustering ...
  • Federated Partially Supervised Learning With Limited Decentralized Medical Images 

    Dong, Nanqing; Kampffmeyer, Michael; Voiculescu, Irina; Xing, Eric (Journal article; Tidsskriftartikkel; Peer reviewed, 2022-12-20)
    Data government has played an instrumental role in securing the privacy-critical infrastructure in the medical domain and has led to an increased need of federated learning (FL). While decentralization can limit the effectiveness of standard supervised learning, the impact of decentralization on partially supervised learning remains unclear. Besides, due to data scarcity, each client may have access ...
  • Strongly intermittent far scrape-off layer fluctuations in Alcator C-Mod plasmas close to the empirical discharge density limit 

    Ahmed, Sajidah; Garcia, Odd Erik; Q Kuang, Adam; LaBombard, Brian; L Terry, James; Theodorsen, Audun (Journal article; Tidsskriftartikkel; Peer reviewed, 2023-09-07)
    Intermittent plasma fluctuations in the boundary region of the Alcator C-Mod device were comprehensively investigated using data time-series from gas puff imaging and mirror Langmuir probe diagnostics. Fluctuations were sampled during stationary plasma conditions in ohmically heated, lower single null diverted configurations with scans in both line-averaged density and plasma current, with Greenwald ...
  • On the Effects of Self-supervision and Contrastive Alignment in Deep Multi-view Clustering 

    Trosten, Daniel Johansen; Løkse, Sigurd Eivindson; Jenssen, Robert; Kampffmeyer, Michael (Journal article; Tidsskriftartikkel; Peer reviewed, 2023-08-22)
    Self-supervised learning is a central component in recent approaches to deep multi-view clustering (MVC). However, we find large variations in the development of self-supervision-based methods for deep MVC, potentially slowing the progress of the field. To address this, we present Deep-MVC, a unified framework for deep MVC that includes many recent methods as instances. We leverage our framework to ...
  • Supercm: Revisiting Clustering for Semi-Supervised Learning 

    Singh, Durgesh Kumar; Boubekki, Ahcene; Jenssen, Robert; Kampffmeyer, Michael (Journal article; Tidsskriftartikkel; Peer reviewed, 2023-05-05)
    The development of semi-supervised learning (SSL) has in recent years largely focused on the development of new consistency regularization or entropy minimization approaches, often resulting in models with complex training strategies to obtain the desired results. In this work, we instead propose a novel approach that explicitly incorporates the underlying clustering assumption in SSL through extending ...

Vis mer