Institutt for fysikk og teknologi

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Institutt for fysikk og teknologi

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• Artikler, rapporter og annet (fysikk og teknologi) [97]
• Mastergradsoppgaver i fysikk [20]
• Mastergradsoppgaver i teknologi - kommunikasjon og mikroelektronikk [19]
• Mastergradsoppgaver i teknologi - romfysikk [9]

Recent additions

• Observatoriet i 80-årene

  Trulsen, Jan (Journal article; Tidsskriftartikkel, 1980)

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  Abstract:	På terskelen til en ny dekade er det naturlig å stille spørsmålet hva Observatoriets fremtidige rolle skal bli. Vil det fortsatt være behov for forskningsinnsats på Observatoriets tradisjonelle fagfelter, eller skal innsatsen etter hvert anta en annen retning? Vi skal forsøke å belyse dette ved først å rette blikket bakover for derigjennom å få øye på de store utviklingslinjer i den internasjonale forskningsinnsats på området kosmisk fysikk.
  Description:	This article is part of Ottar (1980), nr 121-122, "Nordlysobservatoriet 50 år", available in Munin at http://hdl.handle.net/10037/5177
  URI:	http://hdl.handle.net/10037/5187

  File(s) in this item: 1

  article.pdf   (705.1Kb)
• Nordlysobservatoriet i dag

  Solheim, Jan-Erik (Journal article; Tidsskriftartikkel, 1980)

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  Abstract:	Da Det Norske Institutt for Kosmisk Fysikk ble del av Universitetet i Tromsø, opphørte Nordlysobservatoriet å eksistere som en formell enhet. Det som i dag omfattes av Nordlysobservatoriet, er dels en fortsettelse av den opprinnelige observasjonsvirksomheten til det gamle Nordlysobservatoriet - men også nye aktiviteter har kommet til - særlig innen feltene plasmafysikk og radiogeofysikk. I det følgende beskrives virksomheten både ved observatoriet og utestasjonene.
  Description:	This article is part of Ottar (1980), nr 121-122, "Nordlysobservatoriet 50 år", available in Munin at http://hdl.handle.net/10037/5177
  URI:	http://hdl.handle.net/10037/5185

  File(s) in this item: 1

  article.pdf   (18.30Mb)
• Nordlys i verdensrommet

  Havnes, Ove (Journal article; Tidsskriftartikkel, 1980)

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  Abstract:	Vi vil ikke her gå inn i nordlyset som vi kjenner det fra jorden, men kort omtale andre steder i verdensrommet hvor vi har observert nordlyslignende fenomen eller hvor vi kan vente å finne beslektede fenomen.
  Description:	This article is part of Ottar (1980), nr 121-122, "Nordlysobservatoriet 50 år", available in Munin at http://hdl.handle.net/10037/5177
  URI:	http://hdl.handle.net/10037/5181

  File(s) in this item: 1

  article.pdf   (2.045Mb)
• Capillary suction model as pipes of different sizes: flow conditions and comparison with experiments

  Nguyen, Hung Thanh; Jacobsen, Stefan; Melandsø, Frank (Conference object; Konferansebidrag, 2012)

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  Abstract:

  ABSTRACT Absorption of water in concrete is often described by the simple linear water uptake vs. square-root-of-time law. However, a deviation from this behaviour is frequently seen depending on factors such as initial water content, water/binder ratio and specimen thickness. The deviation increases with thickness (typically from 25 to 100 mm) and is seen even for very dry specimens with capillary pores. We have applied Laplaces law for suction created under a curved meniscus between air and water to series of pipes with different lengths and radii. The resulting analytical model was first compared with numerical simulations at abrupt reduction or increase of pipe radius showing good agreement. Then a complete second order equation describing the relation between the capillary suction and the suction time was developed. Varying geometries of the pipes of the capillary system were investigated including the effects on the flow rate of varying combination of lengths, radii and sequence. The results showed that largest flow reductions occurred with very narrow sections causing a blocking, reducing the capillary flow rate vs. square root of time in the same manner as in concrete. The often observed phenomenon of reduced flow below the straight line water uptake vs. square root of time could be simulated with the multiple diameter pipe models, as seen by comparing simulations with experiments with varying concrete qualities and sample thicknesses in simple capillary absorption tests. Key-words: capillary suction, pipe geometry, model

  URI:

  http://hdl.handle.net/10037/5114

  File(s) in this item: 1

  article.pdf   (394.7Kb)
• Radiometric temperature reading of a hot ellipsoidal object inside the oral cavity by a shielded microwave antenna put flush to the cheek

  Klemetsen, Øystein; Jacobsen, Svein Ketil; Birkelund, Yngve (Journal article; Tidsskriftartikkel; Peer reviewed, 2012)

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  Abstract:

  A new scheme for detection of vesicoureteral reflux (VUR) in children has recently been proposed in the literature. The idea is to warm bladder urine via microwave exposure to at least fever temperatures and observe potential urine reflux from the bladder back to the kidney(s) by medical radiometry. As a preliminary step toward realization of this detection device, we present non-invasive temperature monitoring by use of microwave radiometry in adults to observe temperature dynamics in vivo of a water-filled balloon placed within the oral cavity. The relevance of the approach with respect to detection of VUR in children is motivated by comparing the oral cavity and cheek tissue with axial CT images of young children in the bladder region. Both anatomical locations reveal a triple-layered tissue structure consisting of skin–fat–muscle with a total thickness of about 8–10 mm. In order to mimic variations in urine temperature, the target balloon was flushed with water coupled to a heat exchanger, that was moved between water baths of different temperatures, to induce measurable temperature gradients. The applied radiometer has a center frequency of 3.5 GHz and provides a sensitivity (accuracy) of 0.03 °C for a data acquisition time of 2 s. Three different scenarios were tested and included observation through the cheek tissue with and without an intervening water bolus compartment present. In all cases, radiometric readings observed over a time span of 900 s were shown to be highly correlated (R ~ 0.93) with in situ temperatures obtained by fiberoptic probes.

  URI:

  http://hdl.handle.net/10037/5057

  File(s) in this item: 1

  article.pdf   (6.815Mb)

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