21 research outputs found
The influence of pipeline wettability and crude oil composition on deposition of gas hydrates during petroleum production
No full textAt specific temperature and pressure conditions, hydrates can sometimes plug production pipelines. It has been shown that some oils contain natural inhibiting compounds (NICs) that prevent hydrate plug formation even though the pressure and temperature are within the hydrate formation conditions. Thus, the hydrate plugging tendency is influenced by the crude oil composition. The mechanisms by which deposition of hydrates occur in a petroleum production system are also likely to be related to pipeline surface properties, e.g. pipeline material, surface free energy and roughness. The ultimate aim of this work is to develop an understanding of the deposition of hydrates on the pipeline wall. Most of the work in this thesis deals with contact angle measurements that determine the wettability of various solids. Different materials and oil compositions have been tested including both model oil systems and crude oil systems. Micromechanical force experiments have been used to determine the adhesion force between hydrates and solids with different amounts of petroleum acids present in the oil phase. The factors that have been identified in this work as most likely influencing deposition of hydrates to the pipeline wall are the presence of free water, surface material and crude oil composition. It may seem as if hydrate deposition will not occur unless free water is present. When the pipeline wall material has a low surface free energy, such as epoxy coated surfaces, deposition seems to be reduced. Crude oils that are assumed as non-plugging and contain high concentrations of acids seems to reduce the probability for deposition to occur
Circulating MicroRNAs and Aerobic Fitness - The HUNT-Study
No full text© 2013 Bye et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited
Career guidance in groups
No full textMaster i yrkespedagogikkDenne masteroppgaven dokumenterer et kvalitativt forskningsprosjekt med karriereveiledning i grupper blant elever på studiespesialiserende utdanningsprogram ved en videregående skole.
Problemstillingen er: Hvordan videreutvikle vg3- elevers selvinnsikt, valgkompetanse og egenaktivitet gjennom strukturert karriereveiledning i grupper?
Utviklingsprosjektet gir en fenomenologisk vinkling av elevers opplevelse av å ha deltatt i karriereveiledning i grupper. Gruppene består av tre elever i hver gruppe og studien er basert på kvalitative data fra fokusgruppeintervjuer gjennomført fra høsten 2014 til januar 2015. Det overordnede målet er å komme frem til en strukturert og organisert veiledningsmodell som kan danne en ny praksis slik at elever skal videreutvikle selvinnsikt, valgkompetanse og egenaktivitet (handling). Gruppeveiledningens innhold er blitt utarbeidet med bakgrunn i styringsdokumenter, karriereteori og teori knyttet til veiledning. Området karriereveiledning er viet stor plass i drøftinger av funn. Det trekkes også inn ulike teoretiske innfallsvinkler til veiledning som konstruktivistisk veiledning, gruppeveiledning/veiledning i fellesskaper, etiske prinsipper i henhold til gruppeveiledning og karriereveileders rolle. I dagens samfunn har elever utrolig mye å velge mellom og det er ikke lett å være alene om dette valget. Gruppeveiledningen i dette utviklingsprosjektet viser at ungdommen synes det er positivt å reflektere sammen om overgangstiden fra videregående skole og ut i en verden som har mye å tilby. Karriereveiledning i grupper handler om å gjøre hver av deltakerne i stand til å forstå deres egen situasjon bedre, overveie strategier for endringer og planlegge handlinger. Gruppeveiledningen i denne forskningsoppgaven har vist at ved å reflektere rundt karriereferdigheter (CMS) som selvinnsikt, mulighetsoppmerksomhet, valgkompetanse, overgangsferdigheter og handlingsmuligheter, så utvikler elevene seg. Dette avhenger av karrieremodenheten til elevene og de kan ha forskjellig behov for veiledning. Dette handler også om rådgivningens plass i skolen og rådgivers tid og resurser
Karriereveiledning i grupper
No full textDenne masteroppgaven dokumenterer et kvalitativt forskningsprosjekt med karriereveiledning i grupper blant elever på studiespesialiserende utdanningsprogram ved en videregående skole.
Problemstillingen er: Hvordan videreutvikle vg3- elevers selvinnsikt, valgkompetanse og egenaktivitet gjennom strukturert karriereveiledning i grupper?
Utviklingsprosjektet gir en fenomenologisk vinkling av elevers opplevelse av å ha deltatt i karriereveiledning i grupper. Gruppene består av tre elever i hver gruppe og studien er basert på kvalitative data fra fokusgruppeintervjuer gjennomført fra høsten 2014 til januar 2015. Det overordnede målet er å komme frem til en strukturert og organisert veiledningsmodell som kan danne en ny praksis slik at elever skal videreutvikle selvinnsikt, valgkompetanse og egenaktivitet (handling). Gruppeveiledningens innhold er blitt utarbeidet med bakgrunn i styringsdokumenter, karriereteori og teori knyttet til veiledning. Området karriereveiledning er viet stor plass i drøftinger av funn. Det trekkes også inn ulike teoretiske innfallsvinkler til veiledning som konstruktivistisk veiledning, gruppeveiledning/veiledning i fellesskaper, etiske prinsipper i henhold til gruppeveiledning og karriereveileders rolle. I dagens samfunn har elever utrolig mye å velge mellom og det er ikke lett å være alene om dette valget. Gruppeveiledningen i dette utviklingsprosjektet viser at ungdommen synes det er positivt å reflektere sammen om overgangstiden fra videregående skole og ut i en verden som har mye å tilby. Karriereveiledning i grupper handler om å gjøre hver av deltakerne i stand til å forstå deres egen situasjon bedre, overveie strategier for endringer og planlegge handlinger. Gruppeveiledningen i denne forskningsoppgaven har vist at ved å reflektere rundt karriereferdigheter (CMS) som selvinnsikt, mulighetsoppmerksomhet, valgkompetanse, overgangsferdigheter og handlingsmuligheter, så utvikler elevene seg. Dette avhenger av karrieremodenheten til elevene og de kan ha forskjellig behov for veiledning. Dette handler også om rådgivningens plass i skolen og rådgivers tid og resurser
Wind Turbines for the Power Supply for Offshore Fish Farms : A Case Study for the Norwegian West Coast
No full textMaster's thesis Renewable Energy ENE500 - University of Agder 2017In this thesis the power consumption of a fish farm is set in relation to the expected power
production from a wind turbine in order to assess the feasibility of this combination. The fish
farm, called Rataren, is located in Sør-Trøndelag and hourly data on power consumption is
available in the period 1st February 2016 until 31st August 2016, as a result of change in
energy source from diesel generators to the onshore power grid. This is one of Norway’s
largest fish farms and has 14 cages during the studied period. There are some minor data
losses that are removed from the data sets. Wind speed, air and water temperatures at 2.5 masl
and 1 mbsl are measured by a Seawatch Midi 185 Buoy at the location, and the data are
supplied by SINTEF Ocean. In view of the estimation of the power output of a wind turbine
the data on wind speed have to be extrapolated from measuring height to turbine hub height.
For this the atmospheric stability, estimated here by the temperature difference between the
air and the sea, is taken into account. The classifications used are unstable, slightly unstable,
near-neutral, slightly stable and stable, and are characterized by limits of the temperature
differences set to -3°C, -1°C, 1°C and 3°C.
Two methods of extrapolating wind speed from measuring height to hub height are
considered; the logarithmic law with corrections according to stability and the power law
parametrized according to stability. For both methods the complete calculation of key
variables requires information that is unavailable in this case of study. The problems faced
when using the log law were the determination of stability parameter z/L, but also variation in
friction velocity or roughness height. When using the log law in combination with different
values for the variables based on literature, there were inconsistencies in the results indicated
by unreasonable wind profiles. The more simplified method, the power law, is therefore
concluded as the best approximation when this many parameters are unknown. The power law
exponents that are used to correspond to each of the atmospheric conditions mentioned are set
to 0.07, 0.09, 0.11, 0.13 and 0.15. Hourly mean wind speeds were then calculated using the
power law with the exponent for the stability class found to occur at that particular hour. The
results show an average wind speed of 7.04 m/s at 65 meters, compared to a measured
average of 5.01 m/s at 2.5 meters height.
The hourly power production at site by a Hywind Demo 2.3 MW turbine and a GWP 750 kW
turbine was estimated. To analyse the sensitivity of the results to the relation of consumption
and production, the hourly consumption is also multiplied by three and by six in two other
cases, while being compared to the power production by the Hywind turbine. The production
by a wind farm of three GWP turbines are estimated and compared to the other cases, which
is similar in capacity to the one Hywind turbine. The 750 kW turbines are considered to be
slightly more favourable, as the ratio of energy import to export to the onshore power grid is
lower. In all, the results show that wind turbine is not suitable without energy storage or
additional power sources. Hence, it is not possible to make a firm conclusion of which turbine
is most suitable without further investigations
Circulating MicroRNAs and Aerobic Fitness - The HUNT-Study
No full textAerobic fitness, measured as maximal oxygen uptake (VO2max), is a good indicator of cardiovascular health, and a strong predictor of cardiovascular mortality. Biomarkers associated with low VO2max may therefore represent potential early markers of future cardiovascular disease (CVD). The aim of this study was to assess whether circulating microRNAs (miRs) are associated with VO2max-level in healthy individuals. In a screening study, 720 miRs were measured in serum samples from healthy individuals (40–45 yrs) with high (n = 12) or low (n = 12) VO2max matched for gender, age and physical activity. Candiate miRs were validated in a second cohort of subjects with high (n = 38) or low (n = 38) VO2max. miR-210 and miR-222 were found to be higher in the low VO2max-group (p<0.05). In addition, miR-21 was increased in male participants with low VO2max (p<0.05). There were no correlations between traditional risk factors for CVD (blood pressure, cholesterol, smoking habit, or obesity) and miR-21, miR-210 and miR-222. DIANA-mirPath identified 611 potential gene-targets of miR-21, miR-210 and miR-222, and pathway analysis indicated alterations in several important signaling systems in subjects with low VO2max. Potential bias involve that blood was collected from non-fasting individuals, and that 8 performed exercise within 24 h before sampling. In conclusion, we found that miR-210, miR-21, and miR-222 were increased in healthy subjects with low VO2max. The lack of association between these three miRs, and other fitness related variables as well as traditional CVD risk factors, suggests that these miRs may have a potential as new independent biomarkers of fitness level and future CVD.© 2013 Bye et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited
Voriconazole-induced periostitis
No full textIn this case report, a 49-year-old man was diagnosed with influenza-associated invasive aspergillosis. Voriconazole therapy was initiated and adjusted to meet therapeutic range. After 16 weeks of treatment the patient was admitted with multifocal, skeletal pains. Alkaline phosphatase was 1,900 U/L and S-voriconazole 9.9 mg/l. A bone scintigraphy and SPECT-CT were performed, and the diagnostic images along with the clinical findings were consistent with voriconazole-induced periostitis. Voriconazole therapy was discontinued, and isavuconazole therapy was initiated, and the patient's symptoms resolved completely.</p
A Prospective Population Study of Resting Heart Rate and Peak Oxygen Uptake (the HUNT Study, Norway)
No full textObjectives:
We assessed the prospective association of resting heart rate (RHR) at baseline with peak oxygen uptake (VO2peak) 23 years later, and evaluated whether physical activity (PA) could modify this association.
Background:
Both RHR and VO2peak are strong and independent predictors of cardiovascular morbidity and mortality. However, the association of RHR with VO2peak and modifying effect of PA have not been prospectively assessed in population studies.
Methods:
In 807 men and 810 women free from cardiovascular disease both at baseline (1984–86) and follow-up 23 years later, RHR was recorded at both occasions, and VO2peak was measured by ergospirometry at follow-up. We used Generalized Linear Models to assess the association of baseline RHR with VO2peak, and to study combined effects of RHR and self-reported PA on later VO2peak.
Results:
There was an inverse association of RHR at baseline with VO2peak (p<0.01). Men and women with baseline RHR greater than 80 bpm had 4.6 mL·kg−1·min−1 (95% confidence interval [CI], 2.8 to 6.3) and 1.4 mL·kg−1·min−1 (95% CI, −0.4 to 3.1) lower VO2peak at follow-up compared with men and women with RHR below 60 bpm at baseline. We found a linear association of change in RHR with VO2peak (p = 0.03), suggesting that a decrease in RHR over time is likely to be beneficial for cardiovascular fitness. Participants with low RHR and high PA at baseline had higher VO2peak than inactive people with relatively high RHR. However, among participants with relatively high RHR and high PA at baseline, VO2peak was similar to inactive people with relatively low RHR.
Conclusion:
RHR is an important predictor of VO2peak, and serial assessments of RHR may provide useful and inexpensive information on cardiovascular fitness. The results suggest that high levels of PA may compensate for the lower VO2peak associated with a high RHR.© Nauman et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited
Etablering av småskala vannkraft
No full textDenne bacheloroppgaven har som hensikt å vurdere etableringen av et småskala vannkraftverk i Tverråa, en elv i Tylldalen. Problemstillingen går ut på hvordan etablering og drift av småskala vannkraftverk påvirker miljømessige og bærekraftige faktorer. I tillegg til å undersøke hvilken innvirkning dette har på økonomiske og energirelaterte aspekter. Vurderingen av energiproduksjonen for vannkraftverket har resultert i to alternativer, ett med dam og ett uten.
Den første delen omhandler de ulike tekniske komponentene som gjelder for begge alternativene. En vannvei av PE-rør med rørdiameter 160 mm, og en peltonturbin med en asynkron generator er valgt for Tverråa. Dette er for å utnytte kraften fra vannet i elva på en måte som gir mest mulig energiproduksjon, med minst mulig tap. Elva har en vannmengde på 0.03 m^3/s, og det er beregnet til å gi en energiproduksjon på 100 kW. Dette gir en årsproduksjon som kan dekke forbruket til gården Høyberget gjennom store deler av året, og overskuddet kan selges videre på kraftnettet. Årsproduksjonen for de to alternativene, er henholdsvis 340 000 kWh og 307 000 kWh. Der det er Alternativ 1, med dam, som kommer best ut av den tekniske analysen.
Den andre delen omhandler en grov økonomisk analyse, for å finne ut om etableringen av kraftverket er økonomisk levedyktig. Fra økonomiske beregninger konkluderes det at Alternativ 1, med dam, er mest lønnsomt. Dette er på grunnlag av at alternativet med dam gir høyere produksjon både årlig og sesongmessig, som gir større inntekter. Dammen regulerer vannstrømmen, sikrer en jevnere produksjon og øker effektiviteten. Videre hadde denne løsningen en bedre teknisk utforming enn Alternativ 2. Dette gjelder både med tanke på at en dam vil kreve mindre vedlikehold enn en terskel, men også at den gir en høyere brukstid på kraftverket.
Samlet sett peker beregningene mot at potensialet for lønnsomhet eksisterer, men med betydelige forbehold. I henhold til NVEs veileder for småkraftverk, anbefales det å doble investeringsgrensen hvis kraften produseres for eget bruk. De økonomiske beregningene viser da at etableringen kan være lønnsomt over en 30-års periode. Imidlertid befinner prosjektet seg på grensen til lønnsomhet, og flere faktorer tilsier at det ikke nødvendigvis vil være økonomisk fordelaktig. Usikkerheter i kostnadsanslag og inntektsprognoser spiller en vesentlig rolle i denne vurderingen. For videre arbeid, vil en mer detaljert analyse kunne gi en klarere indikasjon på prosjektets langsiktige økonomiske levedyktighet.This bachelor's thesis evaluates the establishment of a small-scale hydropower plant in Tverråa, a river in Tylldalen. The main question is how the establishment and operation of a small-scale hydropower plant impact environmental and sustainable factors, as well as their effects on economic and energy-related aspects. The assessment of the hydropower plant's energy production has resulted in two alternatives: one with a dam and one without.
The first part discusses the various technical components to both alternatives. A PE-pipe with a diameter of 160 mm and a Pelton turbine with an asynchronous generator were chosen for Tverråa. This setup aims to maximize the energy production from the river with minimal losses. The river has a flow rate of 0.03 m^3/s, and it is estimated to produce 100 kW of energy. This annual production can cover the consumption of the farm Høyberget for most of the year, with the surplus being sold to the power grid. The annual production for the two alternatives is 340 000 kWh and 307 000 kWh. It is Alternative 1, which includes a dam, that is performing best in the technical analysis.
The second part involves a simple economic analysis to determine whether the establishment of the power plant is economically viable. Economic calculations conclude that Alternative 1 is the most profitable. This is because the dam alternative provides higher annual and seasonal production, leading to greater revenues. The dam regulates water flow, ensures more consistent production, and increases efficiency. Furthermore, this solution had a better technical design than Alternative 2. In addition, it is requiring less maintenance and offering higher operating time for the power plant.
Overall, the calculations suggest that there is potential for profitability, but with significant reservations. According to the Norwegian Water Resources and Energy Directorate's (NVE) guidelines for small hydropower plants, it is recommended to double the investment limit if the power is produced for own use. The economic calculations then show that the establishment can be profitable over a 30-year period. However, the project is on the borderline of profitability, and several factors indicate that it may not necessarily be economically advantageous. Uncertainties in cost estimates and income forecasts play a crucial role in this assessment. For further work, a more detailed analysis could provide a clearer indication of the project's long-term economic viability
Serum levels of choline-containing compounds are associated with aerobic fitness level: the HUNT-study.
No full textBACKGROUND: Cardiovascular disease (CVD) is a leading cause of death worldwide, and the number of people at risk is continuously growing. New methods for early risk prediction are therefore needed to actuate prevention strategies before the individuals are diagnosed with CVD. Several studies report that aerobic fitness level, measured as maximal oxygen uptake (VO(2max)), is the single best predictor of future CVD mortality in healthy people. Based on this, we wanted to study differences between healthy individuals with a large difference in VO(2max)-level to identify new biomarkers of low aerobic fitness that may also have potential as early biomarkers of CVD risk. METHODOLOGY/PRINCIPAL FINDINGS: Serum samples from 218 healthy individuals with a low VO(2max) (n = 108, 63 women) or high VO(2max) (n = 110, 64 women) were analysed with MR metabolomics. In addition, standard clinical-chemical analyses for glucose, lipids, liver enzymes, micro-CRP, and colorimetric analysis on circulating choline were performed. Individuals in the low VO(2max)-group had increased serum levels of free choline, decreased phosphatidylcholine, increased glucosę and decreased unsaturated fatty acids compared to the individuals in the high VO(2max)-group. CONCLUSIONS/SIGNIFICANCE: Aerobic fitness dependent differences in serum levels of free choline and phosphatidylcholine are observed. They should be further studied as potential early markers of CVD risk
