Opin vísindi

 

Nýlega bætt við

Verk
Multi-level CFD-based airfoil shape optimization with automated low-fidelity model selection
(2013) Koziel, Slawomir; Leifsson, Leifur; Department of Engineering
Computational fluid dynamic (CFD) models are ubiquitous in aerodynamic design. Variable-fidelity optimization algorithms have proven to be computationally efficient and therefore suitable to reduce high CPU-cost related to the design process solely based on accurate CFD models. A convenient way of constructing the variable-fidelity models is by using the high-fidelity solver, but with a varying degree of discretization and reduced number of flow solver iterations. So far, selection of the appropriate parameters has only been guided by the designer experience. In this paper, an automated lowfidelity model selection technique is presented. By defining the problem as a constrained nonlinear optimization problem, suitable grid and flow solver parameters are obtained. Our approach is compared to conventional methods of generating a family of variable-fidelity models. Comparison of the standard and the proposed approaches in the context of aerodynamic design of a transonic airfoil indicates that the automated model generation can yield significant computational savings.
Verk
Low-cost EM-simulation-driven multi-objective optimization of antennas
(2014) Bekasiewicz, Adrian; Koziel, Slawomir; Leifsson, Leifur; Department of Engineering
A surrogate-based method for efficient multi-objective antenna optimization is presented. Our technique exploits response surface approximation (RSA) model constructed from sampled low-fidelity antenna model (here, obtained through coarse-discretization EM simulation). The RSA model enables fast determination of the best available trade-offs between conflicting design goals. A low-cost RSA model construction is possible through initial reduction of the design space. Optimization of the RSA model has been carried out using a multi-objective evolutionary algorithm (MOEA). Additional response correction techniques have been subsequently applied to improve selected designs at the high-fidelity EM antenna model level. The refined designs constitute the final Pareto set representation. The proposed approach has been validated using an ultra-wideband (UWB) monocone and a planar Yagi-Uda antenna.
Verk
A scoping review of the Cryosphere’s ecosystem services, disservices, and related indicators
(Elsevier, 2025-06) Malinauskaite, Laura; Cook, David; Zaman, Hashim; Gomez-Baggethun, Erik; Faculty of Economics (UI); Hagfræðideild (HÍ); School of Social Sciences (UI); Félagsvísindasvið (HÍ)
The cryosphere, which refers to the parts of the Earth’s surface where water is in solid form, is a major contributor to human wellbeing through the provision of vital ecosystem services. These include, e.g., groundwater recharge, water storage and purification, climate regulation, and diverse cultural and spiritual benefits. A systematized classification of ecosystem services can be used to define, measure, and value the ways in which the cryosphere contributes to society and to communicate these benefits in a clear, transparent and scientifically sound way, yet, it has been missing to date. This study builds on previous literature exploring the cryosphere’s positive and negative impacts on human wellbeing in the context of rapid climate change. It further organises this knowledge on a global scale with a view to enhancing scientific exploration and policy guidance, along with facilitating comparability between different studies. Our research applies the Search-Appraisal-Synthesis-Analysis (SALSA) literature review method and the Common International Classification of Ecosystem Services (CICES) to source and systemise the existing information on ecosystem services and disservices provided by the cryosphere, and possible indicators for monitoring their changes are identified. A total of 30 ecosystem services and 10 disservices were identified, together with indicators that could be used to monitor their trends in biophysical, economic, and sociocultural terms. Our research finds that the cryosphere continues to provide vital ecosystem services despite accelerated retreat of glaciers and other cryospheric components, but also an increasing amount of ecosystem disservices because of global climate change. Monitoring trends in the cryosphere’s contributions to human wellbeing has the potential to inform adaptive governance in fast-changing cryospheric environments.
Verk
The Genuine Progress Indicator for the transition economies of the Baltic States: reflections on economic welfare and methodological choices
(Elsevier, 2026-09) Malinauskaite, Laura; Cook, David; Davíðsdóttir, Brynhildur; Faculty of Economics (UI); Hagfræðideild (HÍ); School of Social Sciences (UI); Félagsvísindasvið (HÍ)
The Baltic States of Estonia, Latvia, and Lithuania have experienced rapid Gross Domestic Product (GDP) growth since the collapse of the Soviet Union and subsequent transition from planned to market economy, reporting increasing levels of consumption and subjective wellbeing but persistent income inequality, which raises the question of whether economic expansion has translated into genuine welfare improvements. The study provides the first application of an updated Genuine Progress Indicator (GPI) framework to the Baltic States for the period 1995-2023. To assess the robustness of the results, a sensitivity analysis of the components with the greatest influence on GPI values was conducted: valuation of lei-sure time, the cost of carbon, and the income inequality adjustment. The analysis reveals that economic welfare measured by the GPI has generally exceeded GDP across all three countries in the study period, apart from 2023 in Estonia and Lithuania, offering indications that the welfare returns of additional economic growth might be diminishing. However, the extent to which the GPI exceeds or falls below GDP varies considerably depending on pa-rameter choices. The sensitivity of the GPI to assumptions regarding hourly wages, carbon cost, and inequality baselines highlights methodological challenges that makes cross-country comparisons difficult. These findings caution against uncritical use of the GPI in pol-icy settings and highlight the need for methodological standardisation and clearer valuation guidelines if the metric is to serve as a credible tool for assessing progress beyond GDP.
Verk
The Genuine Progress Indicator’s development and applications – a systematic literature review from 1995 to 2023
(Springer Nature, 2026-01) Malinauskaite, Laura; Cook, David; Davíðsdóttir, Brynhildur; Faculty of Economics (UI); Hagfræðideild (HÍ); School of Social Sciences (UI); Félagsvísindasvið (HÍ)
The Genuine Progress Indicator (GPI) is a composite economic indicator designed in 1995 to consider the trade-offs between the costs and benefits of economic activity, seeking to provide a more comprehensive view of macroeconomic wellbeing than is revealed by market activity measured by the Gross Domestic Product (GDP). The measure was developed as a response to the lack of consideration of societal and environmental dimensions in the economic development debate and includes monetary adjustments that reflect effects of economic activity to economic welfare. The study applies the PSALSAR systematic literature review methodology to extract the main themes and discussions related to the GPI, including its methods and policy applications, based on the period 1995 to 2023. The analysis of 43 reviewed publications suggest that the GPI has evolved substantially during the period examined, gaining more solid theoretical foundations, yet there are diverging opinions in the literature on its purpose, methodology, and extent to which it can inform sustainable development. Most of the studies were conducted in developed countries with the purpose of comparing GPI and GDP and highlighting the welfare implications of its different components. Various calls for GPI methodological alignment enabling comparability between studies remain largely unanswered, as the GPI 2.0 methodology has not gained traction. Varying accounting approaches used to compute GPI sub-indicators confirm a persistent lack of convention in valuation methods. The findings suggest ongoing development of the GPI since 1995 but scant evidence of its policy implementation. The lack of a shared vision for the future of the GPI among its practitioners appears to be one of the main obstacles to its further harmonisation and application.