Birgir Hrafnkelsson

Dr. Birgir Hrafnkelsson

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Research Focus & Metrics

Academic Career Length

17Years (2010-Present)

(Calculated once Scilit publication data is synced: current year − year of first publication + 1)

Representative Publications

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21 February 2019 in Bulletin of Earthquake Engineering
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Milad KowsariMilad Kowsari
Milad Kowsari
BHBenedikt Halldorsson
Benedikt Halldorsson
BHBirgir Hrafnkelsson
Birgir Hrafnkelsson
JSJonas Thor Snaebjornsson
Jonas Thor Snaebjornsson
SJSigurjón Jónsson
Sigurjón Jónsson

5 December 2021 in Environmetrics
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BHBirgir Hrafnkelsson
Birgir Hrafnkelsson
HSHelgi Sigurdarson
Helgi Sigurdarson
SRSölvi Rögnvaldsson
Sölvi Rögnvaldsson
AJAxel Örn Jansson
Axel Örn Jansson
RVRafael Daníel Vias
Rafael Daníel Vias
SGSigurdur M. Gardarsson
Sigurdur M. Gardarsson

1 September 2015 in Energies
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BRBirgir Freyr Ragnarsson
Birgir Freyr Ragnarsson
GOGudmundur V. Oddsson
Gudmundur V. Oddsson
RURunar Unnthorsson
Runar Unnthorsson
BHBirgir Hrafnkelsson
Birgir Hrafnkelsson
Wind energy harnessing is a new energy production alternative in Iceland. Current installed wind power in Iceland sums to 1.8 MW, which in contrast is 0.1% of the country’s total electricity production. This article is dedicated to the exploration of the potential cost of wind energy production at Búrfell in the south of Iceland. A levelized cost of energy (LCOE) approach was applied to the estimation of the potential cost. Weibull simulation is used to simulate wind data for calculations. A confirmation of the power law is done by comparing real data to calculated values. A modified Weibull simulation is verified by comparing results with actual on-site test wind turbines. A wind farm of 99MWis suggested for the site. Key results were the capacity factor (CF) at Búrfell being 38.15% on average and that the LCOE for wind energy was estimated as 0.087–0.088 USD/kWh (assuming 10% weighted average cost of capital (WACC)), which classifies Búrfell among the lowest LCOE sites for wind energy in Europe.

13 April 2016 in Energies
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BHBirgir Hrafnkelsson
Birgir Hrafnkelsson
GOGudmundur V. Oddsson
Gudmundur V. Oddsson
RURunar Unnthorsson
Runar Unnthorsson
A novel Monte Carlo (MC) approach is proposed for the simulation of wind speed samples to assess the wind energy production potential of a site. The Monte Carlo approach is based on historical wind speed data and reserves the effect of autocorrelation and seasonality in wind speed observations. No distributional assumptions are made, and this approach is relatively simple in comparison to simulation methods that aim at including the autocorrelation and seasonal effects. Annual energy production (AEP) is simulated by transforming the simulated wind speed values via the power curve of the wind turbine at the site. The proposed Monte Carlo approach is generic and is applicable for all sites provided that a sufficient amount of wind speed data and information on the power curve are available. The simulated AEP values based on the Monte Carlo approach are compared to both actual AEP and to simulated AEP values based on a modified Weibull approach for wind speed simulation using data from the Burfell site in Iceland. The comparison reveals that the simulated AEP values based on the proposed Monte Carlo approach have a distribution that is in close agreement with actual AEP from two test wind turbines at the Burfell site, while the simulated AEP of the Weibull approach is such that the P50 and the scale are substantially lower and the P90 is higher. Thus, the Weibull approach yields AEP that is not in line with the actual variability in AEP, while the Monte Carlo approach gives a realistic estimate of the distribution of AEP.

4 October 2018 in BMC Infectious Diseases
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EEElias Eythorsson
Elias Eythorsson
SSSamuel Sigurdsson
Samuel Sigurdsson
BHBirgir Hrafnkelsson
Birgir Hrafnkelsson
HEHelga Erlendsdóttir
Helga Erlendsdóttir
ÁHÁsgeir Haraldsson
Ásgeir Haraldsson
KKKarl G Kristinsson
Karl G Kristinsson
Antimicrobial resistance is a public-health threat and antimicrobial consumption is the main contributor. The ten-valent pneumococcal conjugate vaccine (PHiD-CV10) was introduced into the Icelandic vaccination program in 2011. The aim was to estimate the vaccine impact of PHiD-CV10 on outpatient antimicrobial prescriptions in children. Eleven Icelandic birth-cohorts (2005–2015) were followed from birth until three years of age or to the end of the study period (December 31, 2016). Birth-cohorts were grouped as vaccine non-eligible (VNEC, 2005–2010) or vaccine eligible (VEC, 2011–2015). Data on primary care visits for respiratory infections and antimicrobial prescriptions were extracted from two national registers. Using national identification numbers, prescriptions were linked to physician visits if filled within three days of the visit. Incidence rates and incidence rate ratios between VNEC and VEC were calculated. An Andersen-Gill model was used to model the individual level data, accounting for repeated events and censoring. Vaccine impact was calculated as (1 – Hazard Ratio) × 100%. Included were 53,510 children who contributed 151,992 person-years of follow-up and filled 231,660 antimicrobial prescriptions. The incidence rate was significantly lower in the VEC compared to the VNEC, 144.5 and 157.2 prescriptions per 100 person-years respectively (IRR 0.92, 95%CI 0.91–0.93). Children in VEC were more likely to have filled zero (IRR 1.16 (95%CI 1.10–1.23) and 1–4 (IRR 1.08 95%CI 1.06–1.11) prescriptions compared to children in VNEC. The vaccine impact of PHiD-CV10 against all-cause antimicrobial prescriptions was 5.8% (95%CI 1.6–9.8%).When only considering acute otitis media-associated prescriptions, the vaccine impact was 21.8% (95%CI 11.5–30.9%). The introduction of PHiD-CV10 lead to reduced antimicrobial use in children, mainly by reducing acute otitis media episodes. This intervention therefore reduces both disease burden and could slow the spread of antimicrobial resistance.

5 April 2014 in The European Journal of Health Economics
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TÓThorhildur Ólafsdóttir
Thorhildur Ólafsdóttir
BHBirgir Hrafnkelsson
Birgir Hrafnkelsson
TÁTinna Laufey Ásgeirsdóttir
Tinna Laufey Ásgeirsdóttir