In situ observations of turbulent ship wakes and their spatiotemporal extent

In areas of intensive ship traffic, ships pass every 10ĝ€\uafmin. Considering the amount of ship traffic and the predicted increase in global maritime trade, there is a need to consider all types of impacts shipping has on the marine environment. While the awareness about, and efforts to reduce, chemical pollution from ships is increasing, less is known about physical disturbances, and ship-induced turbulence has so far been completely neglected. To address the potential importance of ship-induced turbulence on, e.g., gas exchange, dispersion of pollutants, and biogeochemical processes, a characterisation of the temporal and spatial scales of the turbulent wake is needed. Currently, field measurements of turbulent wakes of real-size ships are lacking. This study addresses that gap by using two different methodological approaches: in situ and ex situ observations. For the in situ observations, a bottom-mounted acoustic Doppler current profiler (ADCP) was placed at 32ĝ€\uafm depth below the shipping lane outside Gothenburg harbour. Both the acoustic backscatter from the air bubbles in the wake and the dissipation rate of turbulent kinetic energy were used to quantify the turbulent wake depth, intensity, and temporal longevity for 38 ship passages of differently sized ships. The results from the ADCP measurements show median wake depths of 13ĝ€\uafm and several occasions of wakes reaching depths >ĝ€\uaf18ĝ€\uafm, which is in the same depth range as the seasonal thermocline in the Baltic Sea. The temporal longevity of the observable part of the wakes had a median of around 10ĝ€\uafmin and several passages of >ĝ€\uaf20ĝ€\uafmin. In the ex situ approach, sea surface temperature was used as a proxy for the water mass affected by the turbulent wake (thermal wake), as lowered temperature in the ship wake indicates vertical mixing in a thermally stratified water column. Satellite images of the thermal infrared sensor (TIRS) onboard Landsat-8 were used to measure thermal wake width and length, in the highly frequented and thus major shipping lane north of Bornholm, Baltic Sea. Automatic information system (AIS) records from both the investigated areas were used to identify the ships inducing the wakes. The satellite analysis showed a median thermal wake length of 13.7ĝ€\uafkm (nCombining double low line144), and the longest wake extended over 60ĝ€\uafkm, which would correspond to a temporal longevity of 1ĝ€\uafh 42ĝ€\uafmin (for a ship speed of 20ĝ€\uafkn). The median thermal wake width was 157.5ĝ€\uafm. The measurements of the spatial and temporal scales are in line with previous studies, but the maximum turbulent wake depth (30.5ĝ€\uafm) is deeper than previously reported. The results from this study, combined with the knowledge of regional high traffic densities, show that ship-induced turbulence occurs at temporal and spatial scales large enough to imply that this process should be considered when estimating environmental impacts from shipping in areas with intense ship traffic

Rapport forprosjekt : Campus 4 Avdeling for økonomi, samfunnsfag og informatikk

I kapittel 1 tolkes oppdraget og vår mandatforståelse. Det legges stor vekt på dokumentasjon og datagrunnlag, slik det ble etterspurt i forstudien. I kapittel 3 drøftes forholdet til campus 3. Vi ser ikke konfliktområder som tilsier organisasjonsendringer. Kapittel 4 viser aktivitet og utfordringer innen våre virksomhetsområder. Markedssituasjonen for våre studier svinger mye, noe som krever kontinuerlig tilpassing og omstilling; en kan i liten grad vedta utviklingen. Videre vektlegges den regionale utfordringen i tillegg til nasjonale oppgaver. Det vises til målsettinger gitt i stasbudsjettet, og særlig til utfordringer gitt i ”En ledende kompetansenasjon”, en utreding fra UFD. I kapittel 4.2 belyses høgskolens markedsutvikling. Flere av studiene på ØSIR, særlig informatikk, er konjunkturutsatte utdanninger og det har vært, og en må forvente, store svingninger i søkertall. IT-utdanningene i HH har hatt samme relative søkerutvikling som ved andre statlige høgskoler. Økonomiutdanningene har også hatt store svingninger, men i 2005 er søkningen passert søkningen fra 1997 og er på samme relative nivå som snittet for alle studier, og høyere enn for andre økonomistudier i statlige høgskoler. Søkningen til samfunnsfag i Norge har fra 2002 økt kraftig og betydelig mer enn for snittet av alle studier. Samfunnsfagene ved avdelingen har ikke tatt del i denne veksten. Vi mener hele høgskolen har tapt relativ konkurransekraft. de siste 7 år. Ut i fra veksten i ungdomskullene må en kunne forvente 20 % økt søkermasse nasjonalt frem mot år 2010. Siden år 2000 har ØSIR hatt tap av måltall og studiepoengproduksjon. Det har også avdelinger i andre høgskoler med samme type fagportefølje. Høgskolen i Hedmark har samlet tapt måltall og studiepoengproduksjon. ØSIR har en meget høg eksternfinansiert utdanningsvirksomhet, på samme nivå som for ordinære studieplasser. Videre belyses avdelingen diversifiseringsstrategi for studieutvikling. I korthet består det av å markedsføre mange studier med utgangspunkt i en grunnstamme kurs og fag. Det påvises at dette er en strategi som er i bruk her og også hos de fleste andre konkurrenter. Selv om det administrativt kunne ha vært enklere med færre studier, så er diversifisering en konsekvens av markedsutsetting. Samordna opptak (SO) er en markedskanal i tillegg til et servicesenter. ”Music Management” versus ”Øk/adm. Mulighet til fordyping blant annet innen musikkarrangement” er vel et nærliggende eksempel. I kapittel 4.3 dokumenteres utviklingen av forskningsaktivitet: I Norge og Hedmark, og internt i høgskolen. Omfanget i Hedmark er betydelig lavere enn i snittet av fylker uten universitet, og enda lavere enn landsgjennomsnittet. I høgskolen er det ca. 2 forekomster av FoU+formidling pr. fast ansatt pr. år de tre siste årene, slik kriteriene for dette har vært frem til nå. Oppdragsomsetningen pr. fast ansatt blir også belyst. I kapittel 4.4 dokumenters eksternt finansiert virksomhet; omfang. typer, kunder, organisering, utfordringer. Avdelingen har satset meget høyt på å bidra til regional utvikling gjennom å tilby oppdragsutdanninger. Fordi Hedmark har en voksenbefolkning med lavt utdanningsnivå, har dette vært et adekvat bidrag til regional utvikling. I og med fylkets lave forskningsaktivitet er etterspørselen etter forskning innen våre fag begrenset. Forsvaret har etter hvert blitt vår største kunde for oppdragsutdanninger. Denne virksomheten har et nasjonalt nedslagsfelt som også har fått oppmerksomhet i Stortinget

Nordic calibration comparison for radiotherapy dosemeters : Cylindrical and plane-parallel ionization chambers

Raportissa kuvataan pohjoismaisena yhteistyönä tehty mittausvertailu. Mittausvertailussa oli mukana viisi laboratoriota Pohjoismaista (Suomi, Ruotsi, Norja ja kaksi laboratoriota Tanskasta). Vertailussa käytettiin kahta erilaista sädehoidon annosmittauksissa käytettävää ionisaatiokammiota (sylinteri ja tasolevykammiot) sekä näihin liittyvää elektrometriä. Osallistuvat laboratoriota määrittivät kalibrointikertoimen veteen absorboituneelle annokselle näille ionisaatiokammioille Co-60 –säteilyllä. Lisäksi laboratoriot määrittivät joitakin ionisaatiokammioiden korjauskertoimia sekä elektrometrin herkkyyskorjauskertoimen, mikäli mittaukset oli mahdollista toteuttaa kyseissä laboratoriossa. Kaikki mittaustulokset ovat erittäin lähellä toisiaan epävarmuusarvioiden puitteissa ja ne tukevat hyvin kaikkien laboratorioiden mittauskykyä

Surface Reactions During Atomization, Handling and Consolidation of Al-powders

Surface reactions during atomization and consolidation of pure Al and the alloys Al2Mg, Al5Mn2.5Cr, Al5Mn6Cr and Al8Fe2Mo were studied by using ESCA, SAM and SEM. The powders were analysed in the as-atomized condition and after exposure to humid atmosphere. The powders were atomized by using the USGA (Ultra Sonic Gas Atomization)-technique. The cooling rate of the powder was in the order of 105-106 K/s. The rapid cooling increases the solubility of the alloying elements far beyond the isothermal solubility limits of the alloy system. Though the atomization is performed in a high purity He gas atmosphere, the oxygen potential is high enough to cause oxidation of the surface of the metal powder particles. At high temperatures, discrete Al2O3-particles are formed. During the subsequent cooling and storage of the powder a thin oxide layer develops between the oxide islands on the surface. The average oxide thickness is about 50 \uc5. The thickness of the oxide was determined by taking the effect of the spherical shape of the powder into consideration. The oxide thickness is found to be independent of the particle size, at least in the range 5 \ub5m to 50 \ub5m. Beside Al magnesium is the only element that oxidizes during atomization. It is enriched in the outer surface layers and distributed in a very irregular way over the surface. Exposure of the powder to humid atmosphere causes hydration of Al2O3 and formation of Al(OH)3 on the surface. The amount of hydroxide increases with exposure time and relative humidity. The outer layers of Al(OH)3 are decomposed in ultra high vacuum to Al2O3 and H2O. The thickness of the decomposed layer of Al(OH)3 was found to be 17 \uc5, corresponding to 7 \uc5 of Al2O3. The alloying elements Mn and Cr dissolved in the matrix of the powder tend to stabilize the surface oxide and thereby decrease the hydroxide formation. Gases adsorbed on the powder are released during degassing and heating before extrusion. The gas reactions were analysed using mass spectroscopy. It was possible to detect desorption of H2O from the surface even after a minimum exposure to air. Alhydroxide is decomposed to Al2O3 and H2O during the heating process; longer exposure time to humid atmosphere gives a larger gas release from the powder surfaces. The results show the necessity of a careful degassing before consolidation of the powder. Consolidation of the powder into compact products was done by hot extrusion. At a high reduction ratio the material formed becomes ductile. It is concluded that the surface oxide breaks up due to surface enlargement during extrusion, thereby achieving metallic bonding between the particles. Oxide products present on the boundaries at a lower area reduction ratio results in PPB (prior particle boundary) failure

En multivocal litteraturöversikt på utvecklarupplevelse

Developer experience is a concept that has emerged from the notion of User experience. Developer experience differs from user experience that it is considering developers instead of users. However, developers can be seen as users of software development tools. The concept of developer experience has initiated new ways of thought and practices for software development. Even if there has been previous research on the topic of developer experience, there are still open questions and vague definitions on what developer experience is and what it means in practice. To better understand the definition of developer experience this thesis’ focus is on understanding the current state of research of developer experience. The study was performed as multivocal literature review where articles written by both academics and practitioners were analyzed. The results from the review indicate that developer experience can be seen as a way to understand the feelings and perceptions of the developers in a software development context. Developer experience is studied both in the academics and the industry, where they both focus on improving the developers experiences when developing software. The difference between the academics and practitioners is that academics are focused on understanding the underlying phenomena of developer experience, while practitioners have seen a lot of different opportunities and business value in studying and improving developer experience.Utvecklarupplevelse är ett begrepp som har framträtt från definitionen av använ- darupplevelse. Utvecklarupplevelse skiljer sig från användarupplevelse från att utveck- larupplevelse är förknippad med utvecklare som både utvecklar nya produkter och tjänster men också som också agerar som användare av verktyg och hjälpmedel till utveckling. Användarupplevelse fokuserar endast på personer som använder produkter och tjänster. Konceptet av utvecklaruDeveloper experience is a concept that has emerged from the notion of User experience. Developer experience differs from user experience that it is considering developers instead of users. However, developers can be seen as users of software development tools. The concept of developer experience has initiated new ways of thought and practices for software development. Even if there has been previous research on the topic of developer experience, there are still open questions and vague definitions on what developer experience is and what it means in practice. To better understand the definition of developer experience this thesis’ focus is on understanding the current state of research of developer experience. The study was performed as multivocal literature review where articles written by both academics and practitioners were analyzed. The results from the review indicate that developer experience can be seen as a way to understand the feelings and perceptions of the developers in a software development context. Developer experience is studied both in the academics and the industry, where they both focus on improving the developers experiences when developing software. The difference between the academics and practitioners is that academics are focused on understanding the underlying phenomena of developer experience, while practitioners have seen a lot of different opportunities and business value in studying and improving developer experience.pplevelse har resulterat till nya tankesätt och metoder inom mjukvaruutveckling. Fastän det har gjorts forskning inom ämnet av utvecklarupplevelse, så finns det ännu öppna frågor om utvecklarupplevelse och vad det innebär. Existerande definitioner på utvecklarupplevelse är till viss del vaga. För att bättre förstå definitionen av utvecklarupplevelse, fokuserar detta diplomarbete på att förstå den nuvarande statusen på forskning av utvecklarupplevelse. Studien i detta diplomarbete utfördes som en litteraturöversikt, där artiklar skrivna av både akade- miker och experter inom industrin analyserades. Resultaten från litteraturöversikten indikerar att utvecklarupplevelse kan ses som ett sätt att förstå utvecklarnas känslor och uppfattningar i mjukvaruutveckling. Utvecklarupplevelse studeras både inom akademin och industrin, där båda fokuserar på att förbättra utvecklarnas upplevelser när man utvecklar programvara. Skillnaden mellan akademiker och industrin är att akademiker är inriktade på att förstå de underliggande fenomenen av utvecklarupp- levelse, medan industrin har sett många olika möjligheter med att skapa affärsvärde av att förstå och förbättra utvecklarupplevelse

Surface Reactions During Atomization, Handling and Consolidation of Al-powders

Surface reactions during atomization and consolidation of pure Al and the alloys Al2Mg, Al5Mn2.5Cr, Al5Mn6Cr and Al8Fe2Mo were studied by using ESCA, SAM and SEM. The powders were analysed in the as-atomized condition and after exposure to humid atmosphere. The powders were atomized by using the USGA (Ultra Sonic Gas Atomization)-technique. The cooling rate of the powder was in the order of 105-106 K/s. The rapid cooling increases the solubility of the alloying elements far beyond the isothermal solubility limits of the alloy system. Though the atomization is performed in a high purity He gas atmosphere, the oxygen potential is high enough to cause oxidation of the surface of the metal powder particles. At high temperatures, discrete Al2O3-particles are formed. During the subsequent cooling and storage of the powder a thin oxide layer develops between the oxide islands on the surface. The average oxide thickness is about 50 \uc5. The thickness of the oxide was determined by taking the effect of the spherical shape of the powder into consideration. The oxide thickness is found to be independent of the particle size, at least in the range 5 \ub5m to 50 \ub5m. Beside Al magnesium is the only element that oxidizes during atomization. It is enriched in the outer surface layers and distributed in a very irregular way over the surface. Exposure of the powder to humid atmosphere causes hydration of Al2O3 and formation of Al(OH)3 on the surface. The amount of hydroxide increases with exposure time and relative humidity. The outer layers of Al(OH)3 are decomposed in ultra high vacuum to Al2O3 and H2O. The thickness of the decomposed layer of Al(OH)3 was found to be 17 \uc5, corresponding to 7 \uc5 of Al2O3. The alloying elements Mn and Cr dissolved in the matrix of the powder tend to stabilize the surface oxide and thereby decrease the hydroxide formation. Gases adsorbed on the powder are released during degassing and heating before extrusion. The gas reactions were analysed using mass spectroscopy. It was possible to detect desorption of H2O from the surface even after a minimum exposure to air. Alhydroxide is decomposed to Al2O3 and H2O during the heating process; longer exposure time to humid atmosphere gives a larger gas release from the powder surfaces. The results show the necessity of a careful degassing before consolidation of the powder. Consolidation of the powder into compact products was done by hot extrusion. At a high reduction ratio the material formed becomes ductile. It is concluded that the surface oxide breaks up due to surface enlargement during extrusion, thereby achieving metallic bonding between the particles. Oxide products present on the boundaries at a lower area reduction ratio results in PPB (prior particle boundary) failure

Erosion-corrosion of laser and thermally deposited coatings exposed in fluidised bed combustion plants

Coated steel tubes were exposed in two power plants (CFB and PFBC) fired with wood chips and coal with a small addition of olive seeds, respectively. Laser coating and two thermal spray techniques were used. The samples in the PFBC plant were immersed in the fluidising bed at material temperatures 450 \ub0C and 400 \ub0C. The exposure lasted for a total time of 8089 h. In the CFB plant a probe at the cyclone entrance had a material temperature of 630 \ub0C for the first 2100 h and then 480 \ub0C for 920 h. The material wastage was determined from tube cross-sections. The corrosion products and deposits were analysed by SEM/EDX, Auger spectroscopy, XPS and XRD. Cobalt based coatings show the best performance in both plants, while nickel based coatings are very sensitive to erosion but resistant to a corrosive atmosphere. The totally degraded chromium carbide containing coating in the CFB plant shows that the degree of corrosion is much larger in this environment. The same coating was excellent in the fluidised bed due to its high erosion resistance. The material wastage is independent of the deposition method. The coating technicques had no significant effect on the spallation behaviour

Erosion-corrosion of laser and thermally deposited coatings exposed in fluidised bed combustion plants

Coated steel tubes were exposed in two power plants (CFB and PFBC) fired with wood chips and coal with a small addition of olive seeds, respectively. Laser coating and two thermal spray techniques were used. The samples in the PFBC plant were immersed in the fluidising bed at material temperatures 450 \ub0C and 400 \ub0C. The exposure lasted for a total time of 8089 h. In the CFB plant a probe at the cyclone entrance had a material temperature of 630 \ub0C for the first 2100 h and then 480 \ub0C for 920 h. The material wastage was determined from tube cross-sections. The corrosion products and deposits were analysed by SEM/EDX, Auger spectroscopy, XPS and XRD. Cobalt based coatings show the best performance in both plants, while nickel based coatings are very sensitive to erosion but resistant to a corrosive atmosphere. The totally degraded chromium carbide containing coating in the CFB plant shows that the degree of corrosion is much larger in this environment. The same coating was excellent in the fluidised bed due to its high erosion resistance. The material wastage is independent of the deposition method. The coating technicques had no significant effect on the spallation behaviour