Opin vísindi
Opin vísindi er varðveislusafn vísindaefnis og doktorsritgerða í opnum aðgangi á vegum íslenskra háskóla og Landsbókasafns Íslands - Háskólabókasafns.
Opinn aðgangur að rannsóknaniðurstöðum er í samræmi við 10. gr. laga nr. 3/2003 um opinberan stuðning við vísindarannsóknir sem og kröfur innlendra og erlendra rannsóknasjóða. Markmiðið með opnum aðgangi er að niðurstöður rannsókna séu aðgengilegar sem flestum óhindrað og án endurgjalds á rafrænu formi. Vistun í varðveislusafninu er varanleg og ætlað að tryggja aðgang að vísindaefni íslenskra háskóla í opnum aðgangi um ókomna tíð. Varðveislusafnið Opin vísindi er tengt við rannsóknagáttina IRIS og rannsóknaniðurstöður í opnum aðgangi sem eru skráðar í IRIS eru um leið vistaðar og gerðar aðgengilegar til framtíðar í varðveislusafninu. Með því að safna þessu efni saman í eitt safn verður aðgangur að því einfaldur og þægilegur fyrir alla sem vilja kynna sér það og geta þannig notið þess öfluga vísindastarfs sem fram fer í háskólum landsins.
Varðveislusafnið er OpenAIRE / OpenAIREplus samhæft og samrýmist kröfum sem gerðar eru um birtingu rannsóknaniðurstaðna úr verkefnum sem styrkt eru úr evrópsku rannsóknaáætlununum FP7 og H2020.
Varðveislusafnið notar opna hugbúnaðinn DSpace.
Opinn aðgangur að rannsóknaniðurstöðum er í samræmi við 10. gr. laga nr. 3/2003 um opinberan stuðning við vísindarannsóknir sem og kröfur innlendra og erlendra rannsóknasjóða. Markmiðið með opnum aðgangi er að niðurstöður rannsókna séu aðgengilegar sem flestum óhindrað og án endurgjalds á rafrænu formi. Vistun í varðveislusafninu er varanleg og ætlað að tryggja aðgang að vísindaefni íslenskra háskóla í opnum aðgangi um ókomna tíð. Varðveislusafnið Opin vísindi er tengt við rannsóknagáttina IRIS og rannsóknaniðurstöður í opnum aðgangi sem eru skráðar í IRIS eru um leið vistaðar og gerðar aðgengilegar til framtíðar í varðveislusafninu. Með því að safna þessu efni saman í eitt safn verður aðgangur að því einfaldur og þægilegur fyrir alla sem vilja kynna sér það og geta þannig notið þess öfluga vísindastarfs sem fram fer í háskólum landsins.
Varðveislusafnið er OpenAIRE / OpenAIREplus samhæft og samrýmist kröfum sem gerðar eru um birtingu rannsóknaniðurstaðna úr verkefnum sem styrkt eru úr evrópsku rannsóknaáætlununum FP7 og H2020.
Varðveislusafnið notar opna hugbúnaðinn DSpace.
Nýlega bætt við
Typing Fallback Functions : A Semantic Approach to Type Safe Smart Contracts
(Schloss Dagstuhl- Leibniz-Zentrum fur Informatik GmbH, Dagstuhl Publishing, 2026-06-25) Lybech, Stian; Gorla, Daniele; Aceto, Luca; Krebbers, Robbert; Silva, Alexandra; Department of Computer Science
This paper develops semantic typing in a smart-contract setting to ensure type safety of code that uses statically untypable language constructs, such as the fallback function. The idea is that the creator of a contract on the blockchain equips code containing such constructs with a formal proof of its type safety, given in terms of the semantics of types. Then, a user of the contract only needs to check the validity of the provided “proof certificate” of type safety. This is a form of proof-carrying code, which naturally fits with the immutable nature of the blockchain environment. As a concrete application of our approach, we focus on ensuring information flow control and non-interference for TinySol, a distilled version of the Solidity language, through security types. We provide the semantics of types in terms of a typed operational semantics of TinySol and we express the proofs of safety as coinductively-defined typing interpretations, which can be represented compactly via up-to techniques, similar to those used for bisimilarity. We also show how our machinery can be used to type the typical pointer-to-implementation pattern based on the fallback function and to reject a distilled version of the infamous Parity Multisig Wallet Attack.
Computational Design and Analysis of a High-Isolation 5G MIMO Antenna Using a Binary GWO-Optimized Pixelated Metasurface
(2026-04) Ülgü, Mehmet; Karaaslan, Muharrem; Atcı, Ahmet; Wang, Lulu; Altıntaş, Olcay; Department of Engineering
Compact 5G millimeter-wave (mm-Wave) multiple-input multiple-output (MIMO) systems face a serious challenge as high isolation is required for high spectral efficiency. This paper presents a novel computational design framework for enhancing the isolation of a two-port ultra-wideband (UWB) MIMO antenna, specifically targeting the 5G n257 band (26.5–29.5 GHz). A pixelated metasurface is presented and optimized with the help of a binary-coded Grey Wolf Optimizer (B-GWO) algorithm through a MATLAB-Computer Simulation Technology (CST) co-simulation interface, which is used in contrast to some conventional decoupling structures. A Geometric Mirror Symmetry method is used to accelerate the optimization process, which halves the number of optimization variables and significantly reduces the computational load. Crucially, this symmetry is also a fundamental requirement to ensure that the reflection coefficients ((Formula presented.), (Formula presented.)) of the antennas remain identical. The proposed design achieves isolation levels better than 20 dB across the entire target band, reaching a peak isolation of (Formula presented.) dB at (Formula presented.) GHz, while maintaining reflection coefficients ((Formula presented.), (Formula presented.)) below (Formula presented.) dB. The MIMO diversity performance is comprehensively validated with an Envelope Correlation Coefficient (ECC) (Formula presented.), a Diversity Gain (DG) of (Formula presented.) dB, and a Total Active Reflection Coefficient (TARC) (Formula presented.) dB. Moreover, the suppression of surface waves enhances the realized gain to (Formula presented.) dBi, providing a (Formula presented.) dB improvement over the reference antenna. In addition, an equivalent passive RLC circuit model is constructed to observe the physical process of the pixelated surface, which shows the optimized structure as a band stop filter at the coupling frequency. The high correlation of the Equivalent Circuit Model and full-wave simulation outcomes confirms that the suggested design procedure is a strong verification alternative to physical fabrication.
Byzantine Consensus in the Partially Authenticated Setting
(Association for Computing Machinery, 2026-07-01) Lenzen, Christoph; Loss, Julian; Shi, Kecheng; Wagner, Benedikt; Department of Computer Science
Byzantine Agreement and Broadcast are traditionally studied in one of two extremes: the authenticated setting, where a public key infrastructure (PKI) enables universally verifiable signatures and yields higher fault tolerance, and the unauthenticated setting, where no PKI is available and resilience necessarily drops. Motivated by Proof-of-Stake blockchains, where only a stable subset of participants (e.g., validators) have registered long-term keys while others do not, we initiate a systematic study of consensus in the partially authenticated setting, where a subset of parties are registered in a PKI and the remaining parties are unregistered.We provide a nearly complete feasibility characterization of the resilience as a function of the number s of registered parties among n total parties. First, we show that Byzantine Agreement or Byzantine Broadcast with an unregistered sender is possible if and only if t ≤ max{⌈s/2⌉, ⌈n/3⌉} - 1, matching a simple protocol and an impossibility bound. Second, for Byzantine Broadcast with a registered sender, we give a deterministic synchronous broadcast protocol tolerating up to t ≤ s + ⌈(n - s)/3⌉ - 1 Byzantine faults (equivalently, 3t < n + 2s); while we present the binary case in the main body for clarity, our techniques extend to an efficient multivalued protocol. We complement this with a matching lower bound in a strengthened leakage model in which the adversary learns each party's private state at the end of every round, ruling out both deterministic protocols and randomized protocols that rely only on short-lived secrets and the basic signing/verification interface.
Buffering strategies in the VUCA and BANI world
(2026-12) Tync, Łukasz; Kuchta, Dorota; Fridgeirsson, Thordur Vikingur; Department of Engineering
In an era characterised by volatility, uncertainty, complexity, and ambiguity (VUCA), further compounded by brittleness, anxiety, non-linearity, and incomprehensibility (BANI), it has become increasingly important to investigate how buffering strategies enable organisations to maintain resilience and sustainability. This study explores both traditional and emerging concepts of organisational buffers, with the aim of identifying their forms and assessing their role in contemporary management practice. Adopting a dual-method approach, the research combines conventional and AI-assisted literature analysis with qualitative interviews conducted with organisational leaders. AI tools were employed to detect both explicit and implicit buffering strategies in the academic literature, revealing a wide spectrum of structural, human resource, psychological, and strategic buffers. Complementing this, a pilot study based on semi-structured interviews offered practical insights into real-world buffering practices. The findings demonstrate that organisations actively deploy a variety of buffering mechanisms, including scenario planning, vertical integration, skill diversity, psychological safety, and experience-based leadership. The study advances resilience theory by laying the groundwork for a comprehensive and typologically expanded framework of buffering strategies applicable across diverse organisational contexts. It further underscores the crucial interplay between technological tools and human judgement in identifying adaptive strategies that foster long-term sustainability in turbulent environments.
Breast Ultrasound AI Under Dataset Shift : A Patient-Leakage-Aware Benchmark
(2026-05) Wang, Lulu; Department of Engineering
Background: Artificial intelligence (AI) has shown promise in breast ultrasound image analysis, but most evidence still comes from single-dataset studies. Clinical translation requires evaluation under heterogeneous acquisition and curation conditions. This study presents a patient-leakage-aware, reproducible benchmark for breast ultrasound AI under dataset shift, with emphasis on external generalization, calibration, and confidence-related behavior. Methods: A reproducible benchmark framework was developed using patient-level splitting, internal testing, pairwise cross-dataset evaluation, whole-image and region-of-interest (ROI) input strategies, calibration analysis, targeted ROI-margin sensitivity analysis, representative explainable AI visualization, and an auxiliary lesion-versus-normal confidence-based analysis. Four public breast ultrasound datasets (BUSI, BUS-UCLM, BUS-BRA, and BrEaST) were harmonized for a primary benign-versus-malignant lesion classification task. Normal images were excluded from the primary endpoint and used only in auxiliary analyses when sufficient numbers were available. Results: Cross-dataset testing was weaker on average than internal testing, with mean raw AUROC decreasing from 0.801 to 0.719 and mean balanced accuracy from 0.723 to 0.635. ROI input improved external performance, especially for the vision transformer, increasing mean external AUROC from 0.666 to 0.805 and mean external balanced accuracy from 0.594 to 0.713 relative to whole-image input. Temperature scaling improved calibration-related metrics, reducing mean external expected calibration error from 0.180 to 0.150 and mean external negative log-likelihood from 0.848 to 0.682. Conclusions: This study establishes a reproducible benchmark for evaluating breast ultrasound AI under dataset shift, with explicit attention to patient-level leakage control, external validity, and reliability of predicted probabilities.
Flokkar í Opnum vísindum
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- University of Iceland
- University of Akureyri
- Bifröst University
- Hólar University College
- IRIS
- Agricultural University of Iceland
- National and University Library of Iceland
- Iceland University of the Arts