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Computing the recession cone of a convex upper image via convex projection
(2024-08) Kováčová, Gabriela; Ulus, Firdevs; Department of Engineering
It is possible to solve unbounded convex vector optimization problems (CVOPs) in two phases: (1) computing or approximating the recession cone of the upper image and (2) solving the equivalent bounded CVOP where the ordering cone is extended based on the first phase. In this paper, we consider unbounded CVOPs and propose an alternative solution methodology to compute or approximate the recession cone of the upper image. In particular, we relate the dual of the recession cone with the Lagrange dual of weighted sum scalarization problems whenever the dual problem can be written explicitly. Computing this set requires solving a convex (or polyhedral) projection problem. We show that this methodology can be applied to semidefinite, quadratic, and linear vector optimization problems and provide some numerical examples.
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Sexual violence in the workplace and associated health outcomes: a nationwide, cross-sectional analysis of women in Iceland : a nationwide, cross-sectional analysis of women in Iceland
(2024-06) Jonsdottir, S. D.; Thordardottir, E. B.; Valdimarsdottir, U. A.; Halldorsdottir, T.; Gudnadottir, S. A.; Jakobsdottir, J.; Runarsdottir, H.; Tomasson, G.; Aspelund, T.; Hauksdottir, A.; Sálfræðideild
Background: Workplace sexual violence against women is a pressing global issue with scarce knowledge on its health implications. Existing research is largely limited to specific occupations, which calls for comprehensive, population-based studies. This study aimed to examine the associations between self-labelled workplace sexual violence and a variety of health outcomes in a nationally representative sample of Icelandic women aged 18–69 years. Methods: Participants in this cross-sectional study were women in the Stress-And-Gene-Analysis (SAGA) cohort who answered the question regarding workplace sexual violence, defined in our study as encompassing all work sectors, academic settings, and other school environments. Eligible participants were women, aged 18–69 years, residing in Iceland, who spoke Icelandic and were listed in the Icelandic Population Register or had a contact number registered with the online 1819 service. Poisson and binomial regressions were used to assess the associations between workplace sexual violence and validated measures of current mental and physical health outcomes (eg, probable depression, general anxiety, and severe sleep problems). Multiple imputation was performed to account for missing values in the dataset. Findings: The study was conducted from March 1, 2018, to July 1, 2019. Of the 113 814 women deemed eligible for study inclusion, 104 197 were invited to take part in the online survey. Of those invited, 30 403 women completed the survey and were included in the SAGA cohort. Among these participants, 15 812 provided answers to the question regarding exposure to workplace sexual harassment or violence. Exposure to sexual violence was associated with an increased prevalence of probable depression (prevalence ratio [PR] 1·50 [95% CI 1·41–1·60]), general anxiety (PR 1·49 [1·40–1·59]), social phobia (PR 1·62 [1·48–1·78]), self-harm (PR 1·86 [1·53–2·28]), suicidal ideation (PR 1·68 [1·44–1·68]), suicide attempts (PR 1·99 [1·62–2·44]), binge drinking (PR 1·10 [1·01–1·20]), sleep problems (PR 1·41 [1·48–1·91]), physical symptoms (PR 1·59 [1·48–1·70]), and sick leave (PR 1·20 [1·12–1·28]). The prevalence of the health outcomes among those exposed show age-related differences: younger women report anxiety or depression more frequently, while older women report sleep problems after experiencing workplace sexual violence. Interpretation: In this cross-sectional study self-reported experiences of sexual violence in the workplace were associated with several self-reported health outcomes. The findings suggest a need for targeted interventions to promote workplace safety and to mitigate adverse health implications among people who have experienced workplace sexual violence. Future research should explore factors such as the frequency, duration, and relationship dynamics of workplace sexual violence, as well as the effect on different genders and sexual orientations, to deepen our understanding of these experiences and inform effective prevention strategies. Funding: Reykjavík Energy Research Fund, The Icelandic Gender Equality Fund, European Research Council, and Icelandic Center for Research.
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Reducing Intrusive Trauma Memories Using a Brief Mental Imagery Competing Task Intervention: Case Series of Trauma-Exposed Women in Iceland : Case Series of Trauma-Exposed Women in Iceland
(2026-05-15) Thorarinsdottir, Kristjana; Holmes, Emily A; Hardarson, Johann; Agustsdottir, Freyja; Kanstrup, Marie; Singh, Laura; Hauksdottir, Arna; Halldorsdottir, Thorhildur; Gudmundsdottir, Berglind; Thordardottir, Edda Bjork; Valdimarsdottir, Unnur; Bjornsson, Andri; Sálfræðideild
Background: There is a need for scalable and simple interventions for trauma-exposed people. In this case series, we built on our previous case study and case series findings and further explored the use and potential effectiveness of a brief novel intervention to reduce the number of past intrusive memories of trauma. The imagery competing task intervention consists of a memory reminder and the visuospatial task Tetris played with mental rotation, targeting 1 intrusive memory at a time. Here, we test remote delivery of the intervention, including guidance from researchers without specialist mental health training, in a sample of women in Iceland with current intrusive memories from trauma. Objective: In a case series of trauma-exposed women, we aimed to explore whether this brief novel intervention reduces the number of established intrusive memories (primary outcome) and improves general functioning and symptom reduction in posttraumatic stress, depression, and anxiety (secondary outcomes). The acceptability of the intervention along with adaptations, that is, delivery by psychology students without specialist mental health training and digital delivery, was explored. Methods: Participants (N=8) monitored the number of intrusive memories from an index trauma (occurring 3‐16 years previously) in a daily diary at baseline, during the intervention, and postintervention at 1-month and 3-month follow-ups. The intervention was delivered digitally with guidance from clinical psychologists or psychology students. A repeated AB design was used (“A”: preintervention baseline, “B”: intervention phase). Intrusions were targeted one by one, creating repetitions of an AB design (ie, length of baseline “A” and intervention “B” varied for each memory). Results: The number of intrusive memories reduced for all participants from the baseline phase compared with the intervention phase, although the reduction was minimal for 2 participants (6.3%‐93%). The number of intrusive memories continued to reduce for 6 out of 8 participants (58%‐100% reduction at 1-month follow-up; 72%‐100% reduction at 3-month follow-up). Symptoms of posttraumatic stress, depression, and anxiety were reduced for most participants postintervention and continued to decrease during the follow-up periods. Functioning was improved for 7 of the 8 participants from baseline to postintervention and continued to improve at the follow-up assessments for 3 participants. The intervention delivered digitally and partly by students was perceived to be an acceptable way to reduce the frequency of intrusive memories by all participants (mean rating 9.5 out of 10). Conclusions: Data from this case series of traumatized women provide preliminary evidence for the effectiveness of this novel brief intervention in reducing intrusive memories of trauma occurring several years ago and in improving functioning and reducing core symptom burden. This study will inform a randomized controlled trial of this novel intervention, which may have considerable implications for large-scale clinical management of traumatized populations.
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Trade associations in Nordic construction - Their role in procurement and project delivery
(2024) Klakegg, O. J.; Ingason, H. T.; Aaltonen, K.; Lahdenperä, P.; Kadefors, A.; Thuesen, C.; Gottlieb, S. C.; Department of Engineering
A trade association is a not-for-profit organization made up of companies and/or individuals with common interests or who work in the same industry. They act as a representative body for the industry they represent. As the 'industry voice', trade associations speak on behalf of their members to government, agencies, regulators, the media, and other opinion formers. There are several trade associations connected to the construction industry in all Nordic countries. The purpose of this paper is to investigate what role they play in improving procurement and project delivery in the Nordic countries. Based on interviews with trade association representatives across all Nordic countries, the paper maps their structures, roles, and strategies for involving in procurement and project delivery across the construction industry in each country. Similarities and differences are analysed and discussed considering the situation in each country. The result shows that trade associations have important and similar roles in each country, motivated by the wish to support their members. The first observation is that most trade associations across the Nordics are actively involved in developing procurement trends and knowledge accumulation. The motivation for engaging in procurement and project delivery is the well-being of members. They all depend on fair competition and access to market, and they all need to be associated with successful projects. The second observation is that it seems generally accepted across the trade associations that it is important to promote more collaborative procurement strategies and project delivery methods. The third observation is that all trade associations across the Nordics take an active role in gathering, analysing, and distributing knowledge and experiences connected to this development. Dissemination is both possible and probable through the trade associations effort.
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Field-Validated Two-Phase CFD Modelling of a Utility-Scale Geothermal Steam Ejector : Operational Boundaries and Performance Scaling
(2026-09) Muguruza, Ximena Guardia; Groves, Christine; Tesfahunegn, Yonatan Afework; Saevarsdottir, Gudrun Arnbjorg; Gudjonsdottir, Maria Sigridur; Department of Engineering
Supersonic ejectors offer a promising solution for extending low-pressure well life and increasing total power output in geothermal plants by entraining low-pressure fluid using a high-pressure primary flow. While steam supersonic ejectors are widely used in industrial applications such as refrigeration, their deployment in geothermal power generation remains largely unexplored, leaving a critical gap in field-validated numerical models for utility-scale two-phase systems. To address this, this study presents a 3D Computational Fluid Dynamics (CFD) framework validated against industrial-scale field tests conducted at the Theistareykir Geothermal Power Plant in Iceland (connecting wells ThG-11 and ThG-15). Four RANS turbulence models (Standard (Formula presented.), RNG (Formula presented.), Realizable (Formula presented.), and (Formula presented.)) were evaluated in ANSYS Fluent using a homogeneous Eulerian wet-steam formulation. The Realizable (Formula presented.) model demonstrated superior accuracy, achieving the lowest absolute error (6.4%) against field data. While non-equilibrium thermodynamic relaxation caused a systematic 8.9–12.6% overprediction in primary motive flow, secondary entrainment predictions closely tracked physical performance, with entrainment ratio errors reaching 0.00% under stable operation. Crucially, the model identifies operational boundaries: while field data places the physical backflow limit at an inlet pressure ratio of (Formula presented.) ((Formula presented.) difference), numerical divergence near zero-entrainment establishes a conservative modelling threshold at (Formula presented.). By defining these physical and numerical limits while quantifying nozzle-sizing safety margins, this work provides a verified benchmark for scaling up CFD models for full-capacity geothermal ejector networks.

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