Luleå University of Technology Publications
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Hydraulic Modeling of Thermal Dynamics in a Generic Reservoir During Pumped Hydropower Operation
No full textIn this study, a three-dimensional hydrodynamic model is developed to investigate diurnal thermal dynamics induced by pumped hydropower storage operations. At this stage, the focus is on thermal mixing in a generic reservoir, with the aim of providing a methodology that can be adapted to various reservoir scenarios. Key issues include enhancing the understanding of how numerical grid resolution impacts modeling results and demonstrating a method for conducting mesh studies in standing water bodies influenced by flow fields, such as those generated by pumping. The model, being implemented in Delft3D FM, is designed to simulate the upper reservoir of a pumped hydropower plant under initial conditions of thermal stratification. A systematic mesh study was conducted by varying cell sizes in different directions to evaluate their influence on the modeling results. A Richardson analysis shows that the longitudinal resolution, along the main reservoir direction, has minimal impact, while the vertical and the lateral resolutions are critical to avoid thin layers in the mesh and prevent oscillations and numerical inaccuracies. The research demonstrates that pumped hydropower operations alter the thermal regime in the upper reservoir, leading to thinning and temperature fluctuations in the epilimnion, as well as weakening the thickness and strength of the thermocline. Additionally, these operations promote the formation of a large-scale recirculation zone. The adaptable model framework allows for changes in bathymetry, initial stratification conditions, and pumping scenarios, enabling new insights into general temperature dynamics and mixing patterns. Full text: CC BY license;Funder: European Regional Development Fund and the Green Transition North-smart energy systems-project (GTN-SE) (no.20359797);This article has previously appeared as a manuscript in a thesis.</p
Hospital Dog—effective, patient-safe, side-effect-free, environmentally safe, cost-effective integrated medicine
No full textFull text: CC BY-NC license;</p
Optimization of a cosmic muon tomography scanner for cargo border control inspection
No full textThe past several decades have seen significant advancement in applications using cosmic-ray muons for tomography scanning of unknown objects. One of the most promising developments is the application of this technique in border security for the inspection of cargo inside trucks and sea containers in order to search for hazardous and illicit hidden materials. This work focuses on the optimization studies for a muon tomography system similar to that being developed within the framework of the “SilentBorder” project funded by the EU Horizon 2020 scheme. Current studies are directed toward optimizing the detector module design, following two complementary approaches. The first leverages TomOpt, a Python-based end-to-end software that employs differentiable programming to optimize scattering tomography detector configurations. While TomOpt inherently supports gradient-based optimization, a Bayesian Optimization module is introduced to better handle scenarios with noisy objective functions, particularly in image reconstruction-driven optimization tasks. The second optimization strategy relies on detailed GEANT4-based simulations, which, while more computationally intensive, offer higher physical fidelity. These simulations are also employed to study the impact of incorporating secondary particle information alongside cosmic muons for improved material discrimination. This paper highlights the outcomes and key findings from these optimization studies. Godkänd;2025;Nivå 0;2025-11-28 (u2);Full text: CC BY license;For funding information, see: https://doi.org/10.1063/5.0287758</p
A method for correcting the substructure of multiprong jets using the Lund jet plane
No full textMany analyses at the CERN LHC exploit the substructure of jets to identify heavy resonances produced with high momenta that decay into multiple quarks and/or gluons. This paper presents a new technique for correcting the substructure of simulated large-radius jets from multiprong decays. The technique is based on reclustering the jet constituents into several subjets such that each subjet represents a single prong, and separately correcting the radiation pattern in the Lund jet plane of each subjet using a correction derived from data. The data presented here correspond to an integrated luminosity of 138 fb−1 collected by the CMS experiment between 2016–2018 at a center-of-mass energy of 13 TeV. The correction procedure improves the agreement between data and simulation for several different substructure observables of multiprong jets. This technique establishes, for the first time, a robust calibration for the substructure of jets with four or more prongs, enabling future measurements and searches for new phenomena containing these signatures.Godkänd;2025;Nivå 0;2025-11-28 (u2);Full text: CC BY license;For funding information, see: https://doi.org/10.1007/JHEP11(2025)038</p
Participatory Design for Small-Scale PV Integration in Heritage Districts: The Case of Öjeby Church Town, Piteå, Sweden
No full textThe integration of small-scale photovoltaic (PV) systems in heritage districts poses a significant challenge: balancing sustainability and energy transition goals while preserving cultural and historical values. This study addresses the problem that existing planning and regulatory frameworks often exclude residents’ perspectives, leading to solutions that are technically feasible but socially contested. The objective is to explore how residents, as potential prosumers, can be effectively integrated into decision-making processes for PV adoption in heritage districts. Focusing on Öjeby Church Town in Piteå, northern Sweden, we employed transdisciplinary participatory design methods, including stakeholder workshops, interviews, council meetings, and a tailored resident design workshop to capture both explicit and tacit knowledge. These design methods were combined with spatial analysis and visual assessment. The findings reveal that residents favour PV solutions that minimise visual impact on heritage buildings, preferring installations in green and grey infrastructure over direct building integration. The process also enhanced awareness, legitimacy, and agency among participants, while exposing regulatory gaps, ownership complexities, and aesthetic tensions. The study contributes a replicable participatory framework that integrates community values with technical and heritage expertise, offering a pathway toward value-sensitive energy transitions in protected cultural environments.Validerad;2025;Nivå 2;2025-09-17 (u8);Full text license: CC BY</p
Reproducible Method for Modifying a Published Electricity Network Model for Transmission Expansion Planning
No full textTransmission network-expansion planning research requires reproducibility of results and comparability of research from various sources. This paper presents a process for modifying a published electricity network model so that the model can be used for exploration of transmission expansion planning problems for different load and generation profiles. Nodal voltages and branch currents are kept within performance limits by following the applicable planning codes, with reinforcements selected based on a defined strategy to achieve compliance with the applicable standards. The process can be applied to any published model and any set of planning standards to result in a base model that is suitably up to date and realistic for transmission network-expansion planning research. A case study is presented, whereby the process is followed for the “Nordic-32”—a popular reference model based on the Swedish transmission network of the 1980s—with the result being a reproducible and updatable model suitable for exploring transmission expansion planning using 2024 generation-and-demand assumptions from Sweden and network design guidelines based on the Nordel Grid Code.Validerad;2025;Nivå 2;2025-11-12 (u4);Full text license: CC BY</p
Search for heavy neutral Higgs bosons A and H in the tt¯Z channel in proton-proton collisions at 13 TeV
No full textA direct search for new heavy neutral Higgs bosons A and H in the tt‾ Z channel is presented, targeting the process pp → A → ZH with H → tt‾. For the first time, the channel with decays of the Z boson to muons or electrons in association with all-hadronic decays of the tt‾ system is targeted. The analysis uses proton-proton collision data collected at the CERN LHC with the CMS experiment at √ = 13TeV, which correspond to an integrated luminosity of 138fb−1. No signal is observed. Upper limits on the product of the cross section and branching fractions are derived for narrow resonances A and H with masses up to 2100 and 2000 GeV, respectively, assuming A boson production through gluon fusion. The results are also interpreted within two-Higgs-doublet models, where A and H are CP-odd and CP-even states, respectively, complementing and substantially extending the reach of previous searches.Godkänd;2025;Nivå 0;2025-08-07 (u8);For funders please see: https://www.sciencedirect.com/science/article/pii/S0370269325003296?via%3Dihub#ac0010;Full text license: CC BY</p
SAFT2 equation of state for the CH4–CO2–H2S–H2O–NaCl quinary system
No full textUnderstanding the phase equilibria and physicochemical properties of the CH4–CO2–H2S–H2O–NaCl quinary system and its subsystems is essential for assessing fluid migration and changes in geological formations following CO2 or acid gas injection. Moreover, this system is closely associated with a large percentage of geological fluids responsible for transport, mass transfer, and the formation of critical mineral ore deposits. In this study, a statistical associating fluid theory (SAFT)-based equation of state (EOS) was developed to investigate phase equilibria and thermodynamic properties of the system over temperatures from 298 to 423 K, pressures up to 600 bar, and NaCl concentration up to 6 mol/kgH2O. The model incorporated pure component and cross-interaction parameters from previous studies, along with CH4–H2S cross-interactions derived from experimental data in this work. The SAFT EOS reliably predicted the phase behavior of the CH4–CO2–H2S and CH4–CO2–H2S–H2O systems, as validated against experimental data and other thermodynamic models. It also successfully predicted phase equilibria and densities for the CH4–H2S–H2O–NaCl and CH4–CO2–H2S–H2O–NaCl systems across a NaCl concentration range of 0–6 mol/kgH2O. This study provides the first systematic development of a SAFT-based model for the CH4–CO2–H2S–H2O–NaCl system, demonstrating reliable performance in characterizing their phase behavior and thermodynamic properties.Validerad;2025;Nivå 2;2025-10-07 (u2);Full text: CC BY license;</p
The meaning of cold bathing in middle aged and elderly people in Sweden - a phenomenological hermeneutic study
No full textCold baths have been used in various cultures for centuries, with modern scientific interest growing over the past few decades. The aim of this phenomenological hermeneutic study was to explore the meaning of outdoor cold bathing of people who regularly engage in that practice. Nine people, seven women and two men aged 44 to 70, who regularly cold bathed in Sweden participated in the study. They were interviewed during the winter-spring of 2025. Participants described cold bathing as a powerful coping mechanism during periods of stress and life transition, often beginning in midlife when facing personal or professional challenges. Cold bathing was described as a powerful practice that not only challenges the body but also uplifts the mind, often becoming a valued ritual for both physical recovery and emotional renewal. Being in nature was an important part of the holiness of the experience.Validerad;2025;Nivå 2;2025-08-11 (u5);Full text license: CC BY-NC 4.0;</p
Characteristics of sediment deposited in a curtained stormwater storage and treatment facility located in the receiving water
No full textA curtained stormwater storage and treatment facility was constructed in Lake Storsjön (Sweden) to treat urban stormwater runoff discharges. Over two and a half years, sediments were sampled four times across four facility zones (from inlet to outlet) in two depths to inform facility operation and polluted sediment management. Sediments were analysed for particle size distribution, metals, polycyclic aromatic hydrocarbons, and organic matter content to assess the spatial distribution of deposited sediment characteristics. Finer sediments (<0.016 mm) prevailed near the outlet, with a higher presence of fine particles in the deeper layer (10–20 cm). Substantial variations in chemical concentrations were observed, differing by up to three orders of magnitude. Higher concentrations were consistently found in the inlet zone and deeper layers (10–20 cm depth) throughout the sampling program. Combined horizontal and vertical distributions of sediment characteristics indicated a predominance of historical deposits in the sediments collected. Frequent exceedances of Predicted No-Effect Concentrations of chemicals, particularly in the inlet zone, highlighted potential risks to the aquatic environment that would result from dredging activities. This underscores the importance of considering broad mitigation strategies, including the capping of contaminated sediment, to control the environmental impacts of contaminated sediments on the lake ecosystem.Validerad;2025;Nivå 2;2025-11-27 (u2);Full text license: CC BYArea-efficient stormwater treatment – Where? When? How