CO and CO2 Anode Gas Concentration at Lower Current Densities in Cryolite Melt

This work aims to study the CO-CO2 gas composition at low potentials and low current densities in cryolite melt with relatively low alumina content (≤2 wt%). There is a scarcity of data in the literature regarding the low current density region and also for bath low in alumina. The experimental setup was constructed to minimize the back reaction as well as the Boudouard reaction. For potentials up to 1.55 V and corresponding current densities up to 0.07 A cm−2, it was found that CO is the dominant product. Between 1.55 and 1.65 V (corresponding current density region 0.07 to 0.2 A cm−2), CO2 becomes the dominant gas product. These potential values are probably slightly large due to suspected Boudouard reaction between CO2 and carbon particles in the melt formed by disintegration of the graphite anode. The results are discussed in relation to the literature data and thermodynamic calculationspublishedVersio

Automatically generated interactive weather reports based on webcam images

Most weather reports are either based on data from dedicated weather stations, satellite images, manual measurements or forecasts. In this paper a system that automatically generates weather reports using the contents on webcam images are proposed. There are thousands of openly available webcams on the Internet that provide images in real time. A webcam image can reveal much about the weather conditions at a particular site and this study demonstrates a strategy for automatically classifying a webcam scene into cloudy, partially cloudy, sunny, foggy and night. The system has been run for several months collecting 60 Gb of image data from webcams across the world. The reports are available through an interactive web-based interface. A selection of benchmark images was manually tagged to assess the accuracy of the weather classification which reached a success rate of 67.3%

Bubble Evolution on Different Carbon Anode Designs in Cryolite Melt

The anode potential has been shown to be highly dependent on anode geometry and orientation in the Hall–Héroult process. This work is an experimental laboratory scale study of the effect of anode geometry and orientation on bubble formation and detachment for four different anode designs: horizontal (surface facing downwards), inverted horizontal (surface facing upwards), vertical, rod (with both vertical and horizontal surface). From polarization curves, it was found that the vertical anode and the inverted horizontal anode operated at lowest potentials. Above 1 A cm−2, the vertical anode showed the lowest potential. As the current increases, the transition towards smaller noise is pronounced for the horizontal anode and to some degree for the vertical anode and inverted horizontal anode. Fast Fourier Transform analysis of chronoamperometric data gave a dominant frequency only for the horizontal anode and the rod anode. The bubble release time corresponded well with the dominant frequency for the rod anode for all current densities and for the horizontal anode at lower current densities. Only random bubble noise was found for the vertical and the inverted horizontal anode and is probably due to a bubble-induced convection effectively removing the bubbles.publishedVersio

A Study of Bubble Behavior and Anode Effect on the Graphite and Industrial Carbon Anode in a See-Through Furnace During Aluminium Electrolysis

Anode gas bubble behavior and anode effect on graphite and industrial carbon rod-shaped anode in a cryolite melt have been studied using a see-through furnace. The different carbon materials have different properties which can affect bubble behavior and electrochemical properties. Industrial carbon is more inhomogeneous with respect to structure, pore, aggregates and impurities in comparison to the graphite. More bubbles were nucleated on the industrial carbon than on the graphite for the same current density. The time related to the coalescence process for both anodes was found to be in interval 16 to 24 ms and independent of the current densities. Bubbles detached from the horizontal surface of the anode have similar average diameter value for both anodes for current densities 1.0 A cm−2, the average diameter is lower for the industrial carbon anode. The onset of the anode effect occurred faster on the graphite than on the industrial anode. The PFC-containing gas layer appeared to be thicker and more stable on the graphite anode than on the industrial carbon anode.publishedVersio

A rapid antibody screening haemagglutination test for predicting immunity to SARS-CoV-2 variants of concern

Background: Evaluation of susceptibility to emerging SARS-CoV-2 variants of concern (VOC) requires rapid screening tests for neutralising antibodies which provide protection. Methods: Firstly, we developed a receptor-binding domain-specific haemagglutination test (HAT) to Wuhan and VOC (alpha, beta, gamma and delta) and compared to pseudotype, microneutralisation and virus neutralisation assays in 835 convalescent sera. Secondly, we investigated the antibody response using the HAT after two doses of mRNA (BNT162b2) vaccination. Sera were collected at baseline, three weeks after the first and second vaccinations from older (80–99 years, n = 89) and younger adults (23–77 years, n = 310) and compared to convalescent sera from naturally infected individuals (1–89 years, n = 307). Results: Here we show that HAT antibodies highly correlated with neutralising antibodies (R = 0.72–0.88) in convalescent sera. Home-dwelling older individuals have significantly lower antibodies to the Wuhan strain after one and two doses of BNT162b2 vaccine than younger adult vaccinees and naturally infected individuals. Moverover, a second vaccine dose boosts and broadens the antibody repertoire to VOC in naïve, not previously infected older and younger adults. Most (72–76%) older adults respond after two vaccinations to alpha and delta, but only 58–62% to beta and gamma, compared to 96–97% of younger vaccinees and 68–76% of infected individuals. Previously infected older individuals have, similarly to younger adults, high antibody titres after one vaccination. Conclusions: Overall, HAT provides a surrogate marker for neutralising antibodies, which can be used as a simple inexpensive, rapid test. HAT can be rapidly adaptable to emerging VOC for large-scale evaluation of potentially decreasing vaccine effectiveness.publishedVersio

Hva en aktørorientert stedstilnærming kan tilføre samfunnsfaget i grunnskolen - En drøfting med utgangspunkt i en gruppe ungdomsskoleelevers stedsbilder av Tøyen.

Læreplanverket for den norske skolen er under store endringer gjennom fagfornyelsen. Fagplanene for samfunnsfag skal omstruktureres og fokuseres. Det er i lys av disse endringene jeg i denne masteroppgaven tar til orde for at en samfunnsgeografisk tilnærming til stedsbegrepet har relevans og kan aktualiseres i grunnskolen. Dette gjelder ikke bare i geografifaget, men også i en bredere samfunnsfaglig kontekst. Steder er mer enn geografiske størrelser, vi forstår og opplever steder ulikt og dette får betydning for hvordan vi betrakter andre steder og mennesker. Tøyen er et godt eksempel på et sted det snakkes mye om, et sted det er mange fortellinger og forestillinger rundt. I denne oppgaven er en gruppe ungdomsskoleelevers stedsbilder av Tøyen utgangspunktet for å knytte denne brede stedsforståelsen til samfunnsfaget i grunnskolen. Følgende problemstilling er mitt utgangspunkt: Hvilke stedsbilder av Tøyen kommer til uttrykk blant ungdomsskoleelever ved to skoler i Oslo, og hva kan en aktørorientert stedstilnærming tilføre samfunnsfaget i grunnskolen? Gjennom en aktørorientert stedstilnærming løftes stedsbegrepet ut fra en deskriptiv og statisk forståelsesramme. Tilnærmingen er forankret i samfunnsgeografien og sosiokulturelle stedsanalyser. Steder forstås her som dynamiske og sosiale størrelser, der meningsinnholdet er mangfoldig, flersidig og gjerne motstridende. Våre stedsbilder preges av de erfaringer og opplevelser vi har til steder og i møte med andre mennesker. Samtidig formes våre forestillinger i en kulturell kontekst og gjennom sosiale prosesser, der ulike stedsfortellinger og stedmyter formidles fra ulike aktører . Metodene som ligger til grunn for datainnsamlingen er kvalitative, og datagrunnlaget baserer seg på 42 elevtekster og to gruppesamtaler. Informantenes forestillinger og det meningsinnholdet de tillegger Tøyen, tegner et mangfoldig og motstridende bilde av stedet. Stedsbildene preges av både negative og positive forestillinger. I tillegg sammenlikner elevene Tøyen med andre steder i Oslo eller setter det i kontrast til eget hjemsted. Dessuten er det ikke bare de fysiske sidene ved Tøyen de knytter sine forestillinger til, elevenes stedsbilder tegner også et bilde av menneskene der. I oppgavens drøftingsdel kobles den aktørorienterte stedstilnærmingen til skolens styringsdokumenter. Jeg diskuterer hvordan denne forståelsen av stedsbegrepet kan ses i lys av kompetanseområder, idealer og verdier samfunnsfaget skal befatte seg med. Med funn i datamaterialet som et viktig grunnlag, løfter jeg frem hva denne aktørorienterte stedstilnærmingen kan tilføre undervisningen i samfunnsfag. Med en dynamisk og sosialt forankret stedsforståelse til grunn, åpner det i skolen opp for å betrakte stedsfortellinger og stedsmyter med et kritisk blikk og gjennom perspektivmangfold blant elevene. Det handler videre om å forebygge sosiale grensesettinger som fordommer, stigmatisering og diskriminering, et viktig mål i demokratiopplæringen. Denne tilnærmingen i møte med andre steder og samfunn, kan også være et viktig bidrag for å skape oppslutning om solidaritet, en grunnleggende verdi i skolen

CO and CO2 Anode Gas Concentration at Lower Current Densities in Cryolite Melt

This work aims to study the CO-CO2 gas composition at low potentials and low current densities in cryolite melt with relatively low alumina content (≤2 wt%). There is a scarcity of data in the literature regarding the low current density region and also for bath low in alumina. The experimental setup was constructed to minimize the back reaction as well as the Boudouard reaction. For potentials up to 1.55 V and corresponding current densities up to 0.07 A cm−2, it was found that CO is the dominant product. Between 1.55 and 1.65 V (corresponding current density region 0.07 to 0.2 A cm−2), CO2 becomes the dominant gas product. These potential values are probably slightly large due to suspected Boudouard reaction between CO2 and carbon particles in the melt formed by disintegration of the graphite anode. The results are discussed in relation to the literature data and thermodynamic calculation

Automatically generated interactive weather reports based on webcam images

Most weather reports are either based on data from dedicated weather stations, satellite images, manual measurements or forecasts. In this paper a system that automatically generates weather reports using the contents on webcam images are proposed. There are thousands of openly available webcams on the Internet that provide images in real time. A webcam image can reveal much about the weather conditions at a particular site and this study demonstrates a strategy for automatically classifying a webcam scene into cloudy, partially cloudy, sunny, foggy and night. The system has been run for several months collecting 60 Gb of image data from webcams across the world. The reports are available through an interactive web-based interface. A selection of benchmark images was manually tagged to assess the accuracy of the weather classification which reached a success rate of 67.3%

Bubble Evolution on Different Carbon Anode Designs in Cryolite Melt

The anode potential has been shown to be highly dependent on anode geometry and orientation in the Hall–Héroult process. This work is an experimental laboratory scale study of the effect of anode geometry and orientation on bubble formation and detachment for four different anode designs: horizontal (surface facing downwards), inverted horizontal (surface facing upwards), vertical, rod (with both vertical and horizontal surface). From polarization curves, it was found that the vertical anode and the inverted horizontal anode operated at lowest potentials. Above 1 A cm−2, the vertical anode showed the lowest potential. As the current increases, the transition towards smaller noise is pronounced for the horizontal anode and to some degree for the vertical anode and inverted horizontal anode. Fast Fourier Transform analysis of chronoamperometric data gave a dominant frequency only for the horizontal anode and the rod anode. The bubble release time corresponded well with the dominant frequency for the rod anode for all current densities and for the horizontal anode at lower current densities. Only random bubble noise was found for the vertical and the inverted horizontal anode and is probably due to a bubble-induced convection effectively removing the bubbles

A Study of Bubble Behavior and Anode Effect on the Graphite and Industrial Carbon Anode in a See-Through Furnace During Aluminium Electrolysis

Anode gas bubble behavior and anode effect on graphite and industrial carbon rod-shaped anode in a cryolite melt have been studied using a see-through furnace. The different carbon materials have different properties which can affect bubble behavior and electrochemical properties. Industrial carbon is more inhomogeneous with respect to structure, pore, aggregates and impurities in comparison to the graphite. More bubbles were nucleated on the industrial carbon than on the graphite for the same current density. The time related to the coalescence process for both anodes was found to be in interval 16 to 24 ms and independent of the current densities. Bubbles detached from the horizontal surface of the anode have similar average diameter value for both anodes for current densities 1.0 A cm−2, the average diameter is lower for the industrial carbon anode. The onset of the anode effect occurred faster on the graphite than on the industrial anode. The PFC-containing gas layer appeared to be thicker and more stable on the graphite anode than on the industrial carbon anode