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Medieval Masculinities and Bodies: Studies of gender relations based on the analysis of human skeletal remains from the monastic burial grounds at Skriðuklaustur, Iceland, and Västerås, Sweden
Get PDFThis compilation thesis is situated at the intersection of the scholarly fields of medieval
masculinities and the bioarchaeology of identities. The aim is to explore bodily aspects of
medieval masculinities through the analysis of human skeletal remains from two medieval
monastic sites, the Augustinian monastery Skriðuklaustur in Iceland (1493-1554), and the
Dominican priory in Västerås, Sweden (1244-1528). A total of 461 individuals were analysed, using standard osteological methods (Buikstra and Ubelaker, 1994).
Theories of masculinities have been developed with reference to modern gender relations, but scholars have found them relevant to medieval contexts (e.g. Beattie and Fenton, 2011; Hadley, 1999; Hodgson et al., 2019; Karras, 2003; Kiefer, 2009; Lees et al., 1994; Murray, 1999; Thibodeaux, 2010). They have to be applied with caution, however, as medieval society and gender relations differ in many ways from their contemporary equivalents (Fletcher, 2011; Karras, 2003:9-10). Connell’s (2005) definition of masculinity as a configuration of gender practices has been used in the thesis. Defining masculinity as a form of practice enables a bioarchaeological approach. The skeleton is plastic, and so enactments of masculinity can leave identifiable marks (Sofaer, 2006), such as specific patterns of entheseal changes, joint disease or trauma.
The four case studies in the thesis address the topics of diet, physical violence, performance in battle, and ability and appearance. The results indicate similarities and mutual influence between different masculinities, but also differences that could be detected through osteological analysis. The carbon and nitrogen stable isotope analysis of a sample of sixteen males and six females buried in Västerås revealed no significant differences in diet between the sexes, between adults and children (represented by dentin samples from the second molar), or between males of higher and lower status. The results suggest that fresh water fish were an important part of the diet, and that both clerics and laity took part in religious fasting (Paper I). There was a significant difference in patterns of weapon-related trauma, however. Lay males were more exposed to trauma than clergy and females. This particularly applied to males of high social standing, and those with battle experience (Paper II). There were also individual differences in gender performance, and some individuals may have transgressed the norms of ideal behaviour, such as ignoring rules of fasting or attacking defenceless victims.
At the same time as the body is shaped by enactments of gender, the way gender can be
enacted is conditioned by the skills and abilities of the body. Changes in the body can result in changed gender practices, and a loss of ability could lead to a crisis of masculinity (Shilling, 2004). This is exemplified in Paper III, on warrior masculinity, by weapon-related trauma and the risk of losing the ability to perform in battle, and in Paper IV, on clerical masculinity, through antemortem tooth loss and the risk of becoming irregular due to altered appearance and speech impairments.2013 University of Iceland Research Fund (research grant)
2013 Berit Wallenberg Foundation (grant for scientific analysis)
2013 Västerås stad (grant for scientific analysis)
2014 University of Iceland, Travel Grants of the Research Fund (travel grant)
2015 Berit Wallenberg Foundation (grant for scientific analysis)
2016 Västerås stad (grant for scientific analysis)
2018 Berit Wallenberg Foundation (grant for scientific analysis)
2018 Västerås stad (grant for scientific analysis)
2019 Helge Ax:son Johnson foundation (research grant)
2019 Letterstedtska (travel grant)
2019 Icelandic Research Fund, through the Disability before Disability project (travel grant)
2021 University of Iceland School of Humanities Education Fund (research grant
Comparative seismic risk assessment of the residential buildings for a strong earthquake scenario in Iceland using local vs. global models
No full textIceland is the most seismically active region in northern Europe and damaging earthquakes repeatedly occur in the South Iceland Seismic Zone (SISZ), a relatively densely populated region accommodating all critical infrastructures and lifelines. The most recent damaging earthquake in the SISZ was the Mw6.3, 29-May-2008 Ölfus earthquake that occurred in close vicinity of the Hveragerði town. The town experienced intense near-fault strong-motion recorded on a strong-motion array (ICEARRAY I). To understand the consequences that a strong earthquake can cause in a high seismic region in terms of
damage probability and damage-to-cost ratio, and to identify the most vulnerable building typologies, we perform seismic risk analyses for the Ölfus earthquake scenario across Hveragerði. Having detailed ground-motion data and a complete building exposure database give the unique opportunity to perform loss estimation in a high geographical resolution of building-by-building, contrary to the common municipality-based resolution. To this end, we employed the Empirical Bayesian Kriging method to estimate the intensity measures at building locations as well as account for the impact of their variability on the expected seismic loss. Finally, the risk metrics resultant from the global fragility curves developed as part of the global seismic risk model are compared with the most recent local models.This study was funded by the Horizon 2020 TURNkey project (#821046). It was also partly supported by a Postdoctoral grant (#218255-051) from the Icelandic Research Fund.Peer Reviewe
Stirring Up Skyr: From Live Cultures to Cultural Heritage
Get PDFIn recent years, the Icelandic dairy product skyr has been transformed from an everyday staple to a national food heritage. Skyr is high in protein and low in fat, and its nutritional value accounts for its international success. However, the domestic and international marketing of skyr glide effortlessly from medieval literature to modern healthy living in promoting skyr as a unique, wholesome, and authentic product: heritage food and Iceland's “secret to healthy living.” In this article, we explore how skyr has been recontextualized as heritage through the cultural staging of skyr-making and through branding efforts. It was not until skyr had become a standardized export commodity that people began to fear that action was needed to protect the traditional way of skyr-making. Picking up on the trend of “heritagization,” pioneered by Slow Food (which added skyr to its “Ark of Taste”) and by small farmers catering to tourists, industrial skyr producers have come around to narrating the cultural history of skyr, employing heritage branding to carve out a unique place within the global dairy-scape. We untangle the messy relationships between the local and the global in such heritage efforts by examining how global trends and markets influence people at local levels, impacting the way they think about and act on their own cultural forms, and how the local level, in turn, impacts global flows under the sign of heritage.Rannsóknasjóður Íslands (IRF), grant # 218181–051Publisher's versio
Pathogen inactivation in platelet concentrate storage : effects on quality and utilization
Get PDFIn transfusion medicine and blood banking, product quality and safety of patients are both essential. Blood transfusion is, in many instances, a lifesaving procedure; however, is not without risk. Blood products contain biological response modifiers (BRMs) that can induce febrile and allergic reactions and there is risk of donor/patient incompatibility, resulting in hemolytic transfusion reaction. Pathogen contamination of donor origin or due to collection and processing is another risk. The implementation of efficient viral screening has made blood transfusions safer, despite not addressing the risks from emerging pathogens or from bacterial contamination. For platelet concentrates (PCs) in particular, the standard storge conditions (room temperature) present an elevated risk of bacterial contamination and transfusion transmitted bacterial infection (TTBI) compared to other blood components, which are stored at subzero or refrigerated temperatures. Though the risk of TTBI can be minimized via the use of various screening assays, TTBI resulting in sepsis still occurs, with a high mortality rate. Therefore, methods have been developed to inactivate pathogens in blood products; such methods include photo or photochemical techniques, which influence the nucleic acids of pathogens and disable transcription. These methods have proven highly efficient in reducing the pathogenic load in blood products, namely PCs and plasma. As these methods have been approved
through clinical trials and then implemented in routine use, indications of negative effects on blood products have emerged, specifically effects on platelet quality have been of concern.
In response to the concern about reduced platelet quality, we investigated effect of pathogen inactivation (PI) with amotosalen and ultraviolet A (UVA) on the quality of stored platelets using a pool and split strategy and whole blood collected buffy coat (BC) platelet concentrates, with the aim of adding to the existing information.
Multiple reports have suggested that micro RNA (miRNA) are important post transcription regulators in platelets, and there have been indications of altered miRNA profile due to pathogen inactivation (PI) methods. Therefore, we examined PI effects on 25 pre-selected miRNAs. Minimal influence was observed, with only 1 out of the 25 showing PI treatment-related down regulation.
The release of BRMs from platelets into the storage media presents a potential risk of adverse events, as well as BRMs being indicators of platelet activation during storge. Monitoring the concentration of 36 proteins, we observed both reduction and increase of BRMs related to PI treatment.
Additionally, PC utilization in national blood transfusion services (at the Blood Bank of Iceland) was analyzed pre- and post-PI implementation. We observed several PI treatment-related effects on both miRNA profiles and protein concentrations in the storage media, as well as elevated expression of markers of platelets storge lesion (PSL), though these effects did not translate to increased utilization or adverse events. We also observed increased product availability and more efficient stock management due to increased storge time, without an increase in outdated stock.Í blóðbankastarfsemi og við blóðinngjöf skipta gæði afurðar og öryggi sjúklings öllu
máli. Í mörgum tilfellum er blóðinngjöf lífsbjargandi meðferð, en ekki laus við áhættu.
Blóð inniheldur lífvirka þætti sem geta stuðlað að aukaverkunum eins og hækkun á
líkamshita og ofnæmi, að auki er áhætta á blóðgjafa og blóðþega misræmi sem getur
valdið niðurbroti á blóðfrumum. Sýking í blóðhluta sem getur átt uppruna frá blóðgjafa
eða við vinnslu á blóðhlutanum er annar áhættuþáttur. Innleiðing veiru skimunar í
blóðhlutum hefur aukið mikið á öryggi við blóðinngjöf, án þess þó koma í veg fyrir
sýkingar vegna óþekktra sýkla eða bakteríu smits. Almennt er blóðflögu þykkni (BÞ)
geymt á vöggu og við stofuhita sem eru kjöraðstæður fyrir vöxt baktería, og þess vegna
er áhætta á slíku smiti margföld í tilfelli BÞ borið saman við aðra blóðhluta sem eru
kældir eða frystir við geymslu. Hægt er að lágmarka áhættu á bakteríu mengun með
margvíslegum skimunar aðferðum, en þrátt fyrir slíkar aðferðir eru tilfelli þar sem
bakteríu mengað BÞ veldur alvarlegri blóðsýkingu með hárri tíðni dauðsfalla. Til að
draga enn frekar úr og jafnvel koma alveg í veg fyrir bakteríu mengun i BÞ hafa verið
þróaðar smit-hreinsunar (SH) aðferðir sem byggja ljósa eða ljósa og efnatækni sem hafa
áhrif á kjarnsýrur í sýklum og koma í veg fyrir umritun. Þessar aðferðir hafa sannað sig í
að draga úr magni sýkla í blóðhlutum, þá sérstaklega BÞ og blóðvökva. Á sama tíma og
þessar aðferðir fengu samþykki byggt á klínískum tilraunum og voru innleiddar inn i
almenna blóðbanka starfsemi, komu fram vísbendingar um neikvæð áhrif á gæði
blóðhluta sérstaklega BÞ
Microsatellites; genotyping, mutation rate and effect on disease
Get PDFMicrosatellites are polymorphic tracts of short tandem repeats (STRs) with one to
six base-pair (bp) motifs and account for around 3% of the human genome. Just like
copying by hand a text where the same word occurs many times in a row, the replication
of microsatellites is error prone and frequently adds or removes one or more copies of
the repeat motif. As a result, microsatellites mutate several orders of magnitude faster
than unique genomic sequences and for a given microsatellite, a population can have
many possible length variations. The first objective of this study was to implement
a method to jointly determine the number of repeats present at each microsatellite
in the genome for a large number of samples. The second goal was to make the
determination of repeat numbers more computationally efficient while simultaneously
increasing the detection sensitivity of heavily expanded microsatellite alleles, known
as repeat expansions. Last, the software was run on two large sets of whole genome
sequenced individuals, one from Iceland and the other from the UK biobank. Using
the genealogy information available on the Icelandic set, de novo mutation events were
detected and the effects of parental sex, age and genotypes on the types and number
of mutations found in their offspring were estimated.Um það bil þrjú prósent af erfðamengi mannsins eru örtungl, en þau eru fjölbreytilegar raðir af stuttum samliggjandi endurtekningum þar sem endurtekna röðin er á
bilinu einn til sex basar á lengd. Líkt og við afritun á texta þar sem sama orðið er
endurtekið oft í röð, þá er villuhættan meiri við afritun örtunglaraða en við aðrar raðir
erfðamengisins og afleiðingin er að endurtekningu er bætt við eða hún tapast miðað
við upprunalega basaröð. Vegna þessa stökkbreytast örtungl nokkrum stærðargráðum
hraðar en aðrar raðir erfðamengisins og fyrir ákveðið örtungl getur hópur af fólki haft
margar mismunandi lengdarútgáfur. Fyrsta markmið verkefnisins var að hanna og
skrifa hugbúnað sem gæti ákvarðað fjölda endurtekninga fyrir öll örtungl í erfðamenginu hjá mörgun einstaklingum í einu. Næst, var reikniritinu hraðað en það jafnframt
gert næmara fyrir stórum útþenslu örtungla samsætum, sem geta valdið mörgum mismunandi heilkennum hjá þeim sem þær bera. Að lokum var hugbúnaðurinn notaður
til að meta arfgerð allra einstaklinga í tveimur stórum þýðum, frá Íslandi annars vegar
og Bretlandi hins vegar. Ættfræðiupplýsingar um íslenska þýðið voru notaðar til að
greina stökkbreytingar í afkvæmum sem ekki fundust í foreldrum og stökkbreytingarnar notaðar til að meta hvernig aldur kyn og arfgerð foreldra hefur áhrif á tegund og
fjölda stökkbreytinga sem þeir arfleiða afkvæmi sín að
Lagrangian Particle Tracking Data of a Straining Turbulent Flow Assessed Using Machine Learning and Parallel Computing
Get PDFThis study aimed to employ artificial intelligence capability and computing scalability to predict the velocity field of the straining turbulence flow. Rotating impellers in a box have generated the turbulence, subsequently subjected to an axisymmetric straining motion, with mean nominal strain rates of 4s^-1. Tracer particles are seeded in the flow, and their dynamics are investigated using high-speed Lagrangian Particle Tracking at 10,000 frames per second. The particle displacement, time, and velocities can be extracted using this technique. Particle displacement and time are used as input observables, and the velocity is employed as a response output. The experiment extracted data have been divided into training and test data to validate the models. Support vector polynomial regression (SVR) and Linear regression were employed to see how extrapolation for the velocity field can be extracted. These models can be done with low computing time. On the other hand, to create a dynamic prediction, Gated Recurrent Unit (GRU) is applied with a high-performance computing application. The results show that GRU presents satisfactory forecasting for the turbulence velocity field and the computing scale performed on the JUWELS and DEEP-EST and reported. GPUs have a significant effect on computing time. This work presents the capability of the GRU model for time series data related to turbulence flow prediction.This work was performed in the Center of Excellence (CoE) Research on AI and Simulation Based Engineering at Exascale (RAISE) and the EuroCC projects receiving funding from EU’s Horizon 2020 Research and Innovation Framework Programme under the grant agreement no.951733 and no. 951740 respectivelyPeer Reviewe
The intersection of environmental and sustainability education, and character education: An instrumental case study
Get PDFAlthough fostering values is promoted within environmental and sustainability education (ESE) and a shift in values seen as essential for a sustainable future, recent international findings indicate this aspect of ESE is being neglected (UNESCO, 2019). Previous research has shown there to be common ground between ESE and the field of character education (CE), a form of values education. Bringing together these two strands of theory and practice has the potential to be fruitful in terms of strengthening current, and introducing new, practices in both fields, particularly through drawing on existing evidence-based strategies within CE to inform ESE. While there has been some work in this regard, this has been almost exclusively theoretical and there has been little research regarding the practice of such integration. This paper details an instrumental case study exploring an existing case of where ESE and CE come together in practice. A study was conducted at a Scottish, independent, all- ages, holistic education-oriented school, exploring how ESE is carried out. Data were gathered via teacher interviews, school observations, field notes, and document analysis. Thematic analysis revealed four themes: the school as a sustainable organism; holistic learning; fostering a connectedness with nature; and nurturing the whole person. The data were then analysed from a CE perspective revealing multiple points of ESE-CE intersection e.g. school climate/ethos, role-modelling, and service-learning. The findings reveal commonalities between ESE and CE and provide examples of integrated ESE-CE practice, demonstrating potential for collaboration or shared ESE-CE practice. Avenues for further research are suggestedThis work was supported by The Icelandic Research Fund under grant number 141878-051.Accepted Manuscript (Peer Reviewed
Unsupervised Deep Learning in Remote Sensing with Application to Image Fusion and Denoising
Get PDFOptical remote sensing (RS) uses optical sensors to create images of the Earth's surface. Those imaging sensors are mounted on spaceborne or airborne vehicles and capture visible, near-infrared, and shortwave infrared radiation reflected from the Earth's surface. Optical remote sensing imaging systems usually provide multi-band images, such as hyperspectral images (HSIs) and multispectral images (MSIs), often with band-dependent spatial resolution. However, those images are often corrupted by noise and have low spatial/spectral resolution. This is caused by several reasons, such as atmospheric absorption, sensor imperfection, and a trade-off between spectral and spatial resolutions. Therefore, denoising or sharpening the images is crucial for many RS applications.
This thesis focuses on HSI denoising and RS image fusion. HSI denoising is the problem of recovering the original true image from the noisy HSI. On the other hand, in RS image fusion, one has a set of co-registered images, each acquired at a different frequency band and having a different spatial resolution. The aim is to sharpen the images so they all have a spatial resolution equal to the highest spatial resolution of the input images.
The main objective of this thesis is to propose new HSI denoising and RS image fusion methods using unsupervised deep learning (DL). The proposed unsupervised DL-based methods are inspired by the deep image prior idea, which centers around training a convolutional neural network (CNN) in an unsupervised manner. Moreover, several novel points are proposed, such as sparse and low-rank ideas, the sensors' modulation transfer functions (MTFs) utilization, and the usage of Stein's unbiased risk estimate (SURE). The proposed HSI denoising and RS image fusion methods are summarized below.
The thesis proposes two HSI denoising methods based on unsupervised CNNs. The first method incorporates the sparse and low-rank property induced by the high spectral and spatial correlation of HSIs to a CNN. Training a CNN for HSI denoising using the sparse and low-rank data significantly reduces computational load and improves the results. The second HSI denoising method derives a SURE-based loss function for training a CNN. Since SURE is an unbiased estimate of the mean-square error (MSE) between the denoised and the reference images and is calculated using only the noisy image, training a CNN with SURE loss avoids overfitting and is unsupervised. Additionally, the SURE-based HSI denoising method can be extended to deal with non-Gaussian noise and to work with low-dimensional HSI data obtained by projecting the original data to a subspace. The SURE-based method improves results and is more feasible in a practical HSI denoising application.
The thesis proposes a Sentinel-2 (S2) image fusion method using a single unsupervised CNN where the sensors' MTFs are embedded as a network layer. The proposed method uses a single CNN to sharpen both the 20 m and 60 m bands of the S2 image, unlike traditional DL-based methods that usually use separate CNN to sharpen each resolution band. Moreover, since the manufacturer provided the S2 sensors' MTFs, the proposed method employs an MTF-based degradation model as a CNN layer. By doing this, training the CNN is unsupervised, and the fused images are well-preserved in both spectral and spatial domains.
A general framework for RS image fusion is proposed. In this framework, a loss function based on SURE and a linear operator that maps an LR image to its HR is derived for training a CNN. The loss function used in this method has two main benefits. First, SURE is an unbiased estimate of the MSE between the fused and the reference images and is computed without using the reference image. Thus, the method is unsupervised and avoids overfitting. Second, the linear operator is chosen to give upsampling results, at least better than a simple interpolation method, e.g., bicubic. Therefore, the linear operator improves the overall fusion results. The method is applied for three representative RS image fusion problems, i.e., MSI and HSI fusion, S2 sharpening, and pansharpening, where the back-projection operator is used as a linear operator in the SURE-based loss. Experimental results show that the fusion quality is significantly enhanced by using back-projection and SURE.Ljósfræðileg fjarkönnun (RS) notar myndskynjara til að taka myndir af yfirborði jarðar.
Þessir myndskynjarar eru festir á gervihnetti eða flugvélar og fanga sýnilega, nærinnrauða og stuttbylgju-innrauða geislun sem endurkastast frá yfirborði jarðar.
Ljósfræðileg fjarkönnunarmyndkerfi eru skilgreind útfrá fjölda tíðnibanda og helstu
tegundir mynda eru margrása myndir (e. multispectral images (MSI)), og fjölrásamyndir
(e. hyperspectral images (HSI)). Af verkfræðilegum og eðlisfræðilegum ástæðum
hafa þessar myndir rýmisupplausn (e. spatial resolution) sem er tíðniháð og einnig
innihalda þessar myndir oft suð. Í þessari ritgerð er lögð áhersla á að auka gæði MSI
og HSI bæði með því að suðsía þær (e. denoising) og auka rýmisupplausn þeirra með
myndsambræðslu (skerping) (e. image fusion).
Þessi ritgerð er þróar nýjar aðferðir sem eru byggðar á því að nota óleiðbeindar
djúpnámsaðferðir (e. deep learning) sem byggja á földunarnetum (e. convolution neural
networks) til að suðsíða og skerpa MSI og HSI myndir. Til þess að þróa þessar aðferðir
eru notaðar hugmyndir frá merkjafræði og tölfræði eins og t.d., notkun á tíðnisvörun
myndskynjarana, SURE (e. Stein’s unbiased risk estimator), rýr merkjafræði (e. sparse
signal processing), og að fjarkönnunarmyndir ”lifa” oft í stærðfræðilegu rúmi af miklu
lægri vídd en þær eru teknar á.
Í þessari ritgerð eru þróaðar tvær aðferðir til suðsíunnar á fjölrásamyndum (e.
hyperspectral images (HSI)) með óileiðbeindum földunarnetum (e. convolution neural
networks (CNN)). Fyrri aðferðin nýtir rýra merkjafræði (e. sparse signal processing)
og að fjarkönnunarmyndir má oft greina í stærðfræðilegu rúmi af miklu lægri vídd en
þær eru teknar á. Þjálfun földunarneta með rýrum gögnum af lágri vídd dregur verulega
úr reikniþunga og bætir niðurstöður. Seinni aðferðin leiðir út tapfall (e. loss function)
byggt á SURE (e. Stein’s unbiased risk estimator) til þjálfunar á földunarnetum. Þar
sem sem reikna má SURE útfrá myndum sem innihalda suð og það er óbjagaður
metill á meðalferskekkju milli suðsíaðra mynda og viðmiðunarmynda kemst þjálfun
tauganeta með SURE tapfalli hjá því að ofmáta gögnin og er óleiðbeind. Einnig má
útvíkka þessa SURE miðuðu suðsíunnar aðferð til að vinna á ógaussísku suði og virka
með víddafækkuðum fjölrásamyndum. Aðferðin bætir niðurstöður og er fýsilegri í
raunverulegum hagnýtingum til suðsíunnar.
Þessi ritgerð þróar myndsambræðsluaðferð (e. image fusion method) fyrir Sentinel2 (S2) myndir með óleiðbeindu földunarneti þar sem tíðnisvörun myndskynjaranna
er innfeld sem lag í netið. Aðferðin notar stakt földunarnet til að skerpa bæði 20 og
60 m bönd S2 mynda, ólíkt mörgum fyrri djúpnámsaðferðum (e. deep learning) sem
flestar nota aðskild földunarneta til að skerpa bönd af ólíkri upplausn. Ennfremur
nýtar aðferðin mælda tíðnisvörun myndskynjaranna frá framleiðanda þeirra sem innfelt
sem lag í földunarnetið til að herma myndbreytingareiginleika þeirra. Þannig má nota
óleiðbeinda þjálfun en viðhalda bæði róf- og rúmþáttum sambræddu myndanna.
v
Víðtækt fyrirkomulag til myndbræðslu fjarskynjunar mynda er sett fram. Innan
þessa fyrirkomulags er tapfall byggt á SURE notað ásamt línulegum virkja sem varpar
mynd af lágri upplausn í hærri upplausn til að þjálfa földunarnet. Tapfallið hefur tvo
sérlega kosti. Í fyrsta lagi er SURE reiknað án viðmiðunarmynda útfrá myndum sem
innihalda suð en er óbjagaður metill á meðalferskekkju milli suðsíaðrar myndar og
undirlyggjandi viðmiðunarmyndar. Þar af leiðir að aðfeðrðin er óleiðbeind og kemst hjá
því að ofmáta gögn. Í öðru lagi er línulegi virkinn valinn til þess að gefa úrtaksþéttingu
(e. upsampling) sem er alltént betri en einföld brúun á borð við tvívíða þriðja stigs
brúun (e. bicubic interpolation). Línulegi virkinn bætir með því móti heildargæði
myndbræðslunnar. Aðferðinni er beitt á þrjú einkennandi verkefni í myndbræðslu
fjarskynjunarmynda, myndbræðslu margrása mynda og fjölrásamynda (e. multispectral
images (MSI) og hyperspectral images (HSI)), skerpingu S2 mynda og panskerping (e.
pansharpening), þar sem afturvarpsvirki (e. back-projection operator) er notaður sem
línulegur virki með SURE tapfalli. Niðurstöður tilrauna sýna að gæði myndbræðslu
aukast verulega með notkun afturvarps og SURE.The Icelandic Research Fund, Grant 174075-05 and Grant 207233-051, and the University of Iceland Doctoral Fund under Grant 1547-154305
Eruption dynamics of Anak Krakatau volcano (Indonesia) estimated using photogrammetric methods
Get PDFOpen Access funding enabled and organized by Projekt DEAL.Analyzing video data from an uncrewed aerial vehicle (UAV) of two short-lived dome building events at Anak Krakatau volcano (Indonesia), we determine vertical and horizontal movements of the dome surface prior to explosions, as well as initial eruption velocities and mass eruption rates via automated feature tracking and other photogrammetric methods. Initial eruption velocities and mass eruption rates are estimated as a proxy for eruptive strength. Eruptive strength is found to correlate with deformation magnitude, i.e., larger pre-explosion surface displacements are followed by both higher initial eruption velocities and mass fluxes. In accord with other studies, our observations can be explained by an overpressure underneath the dome’s surface. We assume that the dome seals the underlying vent efficiently, meaning that pre-explosion pressure build-up controls both deformation magnitude and eruptive strength. We support this assumption by a simple numerical model indicating that pre-explosion pressure increases between 8 and 16 MPa. The model further reveals that the two events vary significantly with respect to the importance of lateral visco-elastic flow for pressurization and deformation. The video sequences also show considerable variations in the gas release and associated deformation characteristics. Both constant and accelerating deformation is observed. Our case study demonstrates that photogrammetric methods are suitable to provide quantitative constraints on both effusive and explosive activity. Future work can build on our or similar approaches to develop automated monitoring strategies that would enable the observation and analysis of volcanic activity in near real time during a volcanic crisis.We would like to thank M. Rietze, who kindly provided us with the video sequences used in this study. He also supplied all the additional information on the video acquisition without which the processing of the films would not have been possible. TD is supported by the Icelandic Research Fund grant Nr. 206527-051. Additionally, we would like to thank Michael R. James for acting as associate editor and for providing us with helpful comments on the manuscript. Likewise, we are grateful to Richard Herd and an anonymous reviewer for their constructive comments and suggestions.Pre-print (óritrýnt handrit
The effect of wind and plume height reconstruction methods on the accuracy of simple plume models — a second look at the 2010 Eyjafjallajökull eruption
Get PDFReal-time monitoring of volcanic ash plumes with the aim to estimate the mass eruption rate is crucial for predicting atmospheric ash concentration. Mass eruption rates are usually assessed by 0D and 1D plume models, which are fast and require only a few observational input parameters, often only the plume height. A model’s output, however, depends also on the plume height data handling strategy (sampling rate, gap reconstruction methods and statistical treatment), especially in long-term eruptions with incomplete plume height records. Representing such an eruption, we used Eyjafjallajökull 2010 to test the sensitivity of six simple and two explicitly wind-affected plume models against 22 data handling strategies. Based on photogrammetric measurements, the wind deflection of the plume was determined and used to re-calibrate radar height data. The resulting data was then subjected to different data handling strategies, before being used as input for the plume models. The model results were compared to the erupted mass measured on the ground, allowing us to assess the prediction accuracy of each combination of data handling strategy and model. Combinations that provide highest prediction accuracies vary, depending on data coverage, eruptive strength, and fragmentation style. However, for this type of moderate to weak eruption, the most important factor was found to be the prevailing windspeed. When windspeeds exceed 20 m/s, most combinations of strategies and models provide predictions that underestimate the erupted mass by more than 40%. Under such conditions, the optimal choice of data handling strategy and plume model is of particularly relevance.The geo-referencing and photo analysis was conducted under the EU Framework 7 FutureVolc project (2012–2016). This work contributes to project MAXI-Plume, supported by the Icelandic Research Fund (Rannís), grant Nr. 206527-051.
TD was supported by the IRF (Rannís) Postdoctoral project grant 206527–051.Pre-print (óritrýnt handrit