98 research outputs found

    Generalized Fock spaces and the Stirling numbers

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    The Bargmann-Fock-Segal space plays an important role in mathematical physics, and has been extended into a number of directions. In the present paper we imbed this space into a Gelfand triple. The spaces forming the Fr\'echet part (i.e. the space of test functions) of the triple are characterized both in a geometric way and in terms of the adjoint of multiplication by the complex variable, using the Stirling numbers of the second kind. The dual of the space of test functions has a topological algebra structure, of the kind introduced and studied by the first named author and G. Salomon.Comment: revised versio

    Patenter som innovasjonsindikatorer : Komparativ analyse av 3 ulike bransjer i 4 nordiske land i perioden 1996 til 2005

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    Ved bruk av patentdatabasen USPTO (US Patent & Trademark Office) som inneholder samtlige amerikanske patenter og mĂžnsterbeskyttelser, er det utfĂžrt en analyse med formĂ„l Ă„ sammenligne patenteringsaktivitet i Norge, Danmark, Sverige og Finland for fĂžlgende tre bransjer: Kuldeteknikk, Offshoreteknikk, og Telekommunikasjon. MĂ„let med denne undersĂžkelsen er en studie av: ‱ Indikatorer for teknologisk utvikling og innovasjon. ‱ Patenter benyttet som innovasjonsindikatorer. ‱ Patenteringsaktivitet i tre ulike bransjer/patentklasser i fire forskjellige land. Fra analysen kan fĂžlgende oppsummeres: ‱ Bruk av Patentstatistikk, ved Ă„ telle antall patenter, benyttes for Ă„ vurdere omfanget av patenteringen. Metoden gir imidlertid ikke det rette bildet av nyskapningsaktiviteten, da noen patenter aldri realiseres og andre benyttes kun for Ă„ blokkere for nye patenter. ‱ Ved Ă„ normalisere antall registrerte patenter Ă„rlig med hensyn til de respektive lands innbyggere, viser resultatene at i land med stĂžrre befolkningsgrunnlag patenteres mer. ‱ Ved Ă„ se pĂ„ dynamikken av denne prosessen globalt over tid, vil det gi et reelt bilde av de mekanismer som kan pĂ„virke patenteringen (oppgang eller nedgang i bransjen). ‱ Bruk av Patentstatistikk ved Ă„ telle antall siteringer: BĂ„de alder og antall patenter pĂ„virker resultatene kraftig, og eldre patenter har normalt flere siteringer enn yngre patenter. ‱ Ved Ă„ telle antall siteringer pr. patent fjernes koplingen (til en viss grad), men fortsatt er eldre patenter sitert oftere enn nyere patenter. ‱ Ved Ă„ ”normalisere” antall siteringer pr. Ă„r antydes hvor viktige snittet av patentene er. Antallet siteringer avtar med tiden (som forventet). ‱ NĂ„r antall nyere patenter Ăžker vil det kompensere for redusert antall siteringer for disse patentene. Hvis WPC indikatoren synker, kan dette forklares med at antall nye patenter ikke Ăžker sĂ„ veldig. ‱ RTCA – indikatoren benyttes for Ă„ fĂ„ Ăžkt forstĂ„else for landets spesialisering, og dette var meget fremtredende i denne analysen.‱ LineĂŠr regresjonsanalyse benyttes for Ă„ vise snittet av antall siteringer av alle patenter, og kan gi svar pĂ„ i hvilken grad det ene landets patenter siteres oftere enn patenter fra de Ăžvrige land. Metoden gir ogsĂ„ svar pĂ„ om det ene landets patenter er ”bedre” enn det andre landets patenter. Videre trekkes fĂžlgende konklusjon: ‱ Ved Ă„ knytte de analyserte bransjene mot de analyserte land ble fĂžlgende klart: I Norge er det olje- og gassbransjen med offshore utstyrsproduksjon som er stĂžrst, i Sverige og i Finland – telekommunikasjon og i Danmark - kuldeautomatikk

    Analyse av utviklingsprosessen ved en typisk norsk lystbÄtprodusent

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    Rapporten beskriver kartlegging av produktutviklingsprosessen ved en bedrift lokalisert pÄ SÞrlandet, GrimstadBÄt AS (GB). Dette er et fiktivt navn pÄ en bÄtprodusent lokalisert pÄ sÞrlandet og rapporten baserer seg pÄ intervjuer med bedriftens nÞkkelpersoner i produktutviklingsprosessen. Det faglige grunnlaget er nedfelt i UNIC-prosjektets manual [1,2]. Rapporten vektlegger flaskehalser i utviklingsprosessen og at GB ikke legger tilstrekkelig vekt pÄ den effektivisering av produksjon og produktutvikling (PU) som skjer hos konkurrentene Rapporten beskriver bedriften og en analyse av bedriftens produktutviklingsstrategi

    Revised circulation scheme North of the Denmark Strait

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    Author Posting. © The Author(s), 2013. This is the author's version of the work. It is posted here by permission of Elsevier Ltd. for personal use, not for redistribution. The definitive version was published in Deep Sea Research Part I: Oceanographic Research Papers 79 (2013): 20-39, doi:10.1016/j.dsr.2013.05.007.The circulation and water mass transports north of the Denmark Strait are investigated using recently collected and historical in-situ data along with an idealized numerical model and atmospheric reanalysis fields. Emphasis is placed on the pathways of dense water feeding theDenmark StraitOverflowWater plume as well as the upper-layer circulation of freshwater. It is found that the East Greenland Current (EGC) bifurcates at the northern end of the Blosseville Basin, some 450 km upstream of the Denmark Strait, advecting overflow water and surface freshwater away from the boundary. This “separated EGC” flows southward adjacent to the previously identified North Icelandic Jet, indicating that approximately 70% of the Denmark Strait Overflow Water approaches the sill along the Iceland continental slope. Roughly a quarter of the freshwater transport of the EGC is diverted offshore via the bifurcation. Two hypotheses are examined to explain the existence of the separated EGC. The atmospheric fields demonstrate that flow distortion due to the orography of Greenland imparts significant vorticity into the ocean in this region. The negative wind stress curl, together with the closed bathymetric contours of the Blosseville Basin, is conducive for spinning up an anti-cyclonic gyre whose offshore branch could represent the separated EGC. An idealized numerical simulation suggests instead that the current is primarily eddy-forced. In particular, baroclinic instability of the model EGC spawns large anticyclones that migrate offshore and coalesce upon reaching the Iceland continental slope, resulting in the separated EGC. Regardless of the formation mechanism, the recently obtained shipboard data and historical hydrography both indicate that the separated EGC is a permanent feature of the circulation north of the Denmark Strait.Support for this work was provided by the Norwegian Research Council (KV), the European Union 7th Framework Programme (FP7 2007-2013) under grant agreement n.308299 NACLIM Project (KV), US National Science Foundation grants OCE-0959381 (RP, MS, DT) and OCE-0850416 (MS), and the Natural Sciences and Engineering Research Council of Canada (KM)

    The North Icelandic Jet and its relationship to the North Icelandic Irminger Current

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    Author Posting. © The Authors, 2017. This article is posted here by permission of Sears Foundation for Marine Research for personal use, not for redistribution. The definitive version was published in Journal of Marine Research 75 (2017): 605-639, doi:10.1357/002224017822109505.Shipboard hydrographic and velocity sections are used to quantify aspects of the North Icelandic Jet (NIJ), which transports dense overflow water to Denmark Strait, and the North Icelandic Irminger Current (NIIC), which imports Atlantic water to the Iceland Sea. The mean transports of the two currents are comparable, in line with previous notions that there is a local overturning cell in the Iceland Sea that transforms the Atlantic water to dense overflow water. As the NIJ and NIIC flow along the north side of Iceland, they appear to share a common front when the bottom topography steers them close together, but even when they are separate there is a poleward flow inshore of the NIJ. The interannual variability in salinity of the inflowing NIIC is in phase with that of the outflowing NIJ. It is suggested, however, that the NIIC signal does not dictate that of the NIJ. Instead, the combination of liquid and solid freshwater flux from the east Greenland boundary can account for the observed net freshening of the NIIC to the NIJ for the densest half of the overturning circulation in the northwest Iceland Sea. This implies that the remaining overturning must occur in a different geographic area, consistent with earlier model results. The year-to-year variability in salinity of the NIJ can be explained by applying annual anomalies of evaporation minus precipitation over the Iceland Sea to a one-dimensional mixing model. These anomalies vary in phase with the wind stress curl over the North Atlantic subpolar gyre, which previous studies have shown drives the interannual variation in salinity of the inflowing NIIC.Funding for the project was provided by the National Science Foundation under grants OCE-1558742 (RSP, MAS, DJT, CN), OCE-1433170 (MAS), and OCE-0959381 (DM); the Norwegian Research Council under grant agreement no. 231647 (KV); the Bergen Research Foundation (KV); the European Union Seventh Framework Programme (FP7 2007-2013) under grant agreement 308299 (NACLIM project, KV, HV, and SJ); and the Natural Sciences and Engineering Research Council of Canada (GWKM)

    Northern Bering Sea tip jets

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    Author Posting. © American Geophysical Union, 2012. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Geophysical Research Letters 39 (2012): L08807, doi:10.1029/2012GL051537.Low-level regions of high wind speed known as tip jets have been identified near Cape Farewell, Greenland's southernmost point. These wind systems contribute to this area being the windiest location on the ocean's surface and play an important role in the regional weather and climate. Here we present the first analysis of the wind systems that make the Siberian coast of the northern Bering Sea the windiest location in the North Pacific Ocean during the boreal winter. In particular we show that tips jets characterized by enhanced northeasterly winds occur in the vicinity of the two prominent headlands along the coast, Cape Navarin and Cape Olyutorsky. The advance of sea ice in the region is shown to impact the frequency and location of the high speed winds in the vicinity of these two capes. Furthermore, we show that these jets are associated with the interaction of extra-tropical cyclones with the high topography of the Koryak Mountain range, situated just inland of the capes. The windstress imparted to the ocean via the tip jets is argued to help drive the formation of dense water in winter in the northern Bering Sea, thus playing an important role in the regional oceanic circulation.GWKM was supported by the Natural Science and Engineering Research Council of Canada. RSP was funded by grant NA08OAR43200895 from the National Oceanic and Atmospheric Administration.2012-10-2

    Seasonal evolution of Aleutian low pressure systems: Implications for the North Pacific subpolar circulation

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    The seasonal change in the development of Aleutian low pressure systems from early fall to early winter is analyzed using a combination of meteorological reanalysis fields, satellite sea surface temperature (SST) data, and satellite wind data. The time period of the study is September–December 2002, although results are shown to be representative of the long-term climatology. Characteristics of the storms were documented as they progressed across the North Pacific, including their path, central pressure, deepening rate, and speed of translation. Clear patterns emerged. Storms tended to deepen in two distinct geographical locations—the Gulf of Alaska in early fall and the western North Pacific in late fall. In the Gulf of Alaska, a quasi-permanent “notch” in the SST distribution is argued to be of significance. The signature of the notch is imprinted in the atmosphere, resulting in a region of enhanced cyclonic potential vorticity in the lower troposphere that is conducive for storm development. Later in the season, as winter approaches and the Sea of Okhotsk becomes partially ice covered and cold, the air emanating from the Asian continent leads to enhanced baroclinicity in the region south of Kamchatka. This corresponds to enhanced storm cyclogenesis in that region. Consequently, there is a seasonal westward migration of the dominant lobe of the Aleutian low. The impact of the wind stress curl pattern resulting from these two regions of storm development on the oceanic circulation is investigated using historical hydrography. It is argued that the seasonal bimodal input of cyclonic vorticity from the wind may be partly responsible for the two distinct North Pacific subarctic gyres

    Upstream sources of the Denmark Strait Overflow : observations from a high-resolution mooring array

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    © The Author(s), 2016. This is the author's version of the work and is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Deep Sea Research Part I: Oceanographic Research Papers 112 (2016): 94-112, doi:10.1016/j.dsr.2016.02.007.We present the first results from a densely instrumented mooring array upstream of the Denmark Strait sill, extending from the Iceland shelfbreak to the Greenland shelf. The array was deployed from September 2011 to July 2012, and captured the vast majority of overflow water denser than 27.8 kgm-3 approaching the sill. The mean transport of overflow water over the length of the deployment was 3.54 ± 0.16 Sv. Of this, 0.58 Sv originated from below sill depth, revealing that aspiration takes place in Denmark Strait. We confirm the presence of two main sources of overflow water: one approaching the sill in the East Greenland Current and the other via the North Icelandic Jet. Using an objective technique based on the hydrographic properties of the water, the transports of these two sources are found to be 2.54 ± 0.17 Sv and 1.00 ± 0.17 Sv, respectively. We further partition the East Greenland Current source into that carried by the shelfbreak jet (1.50 ± 0.16 Sv) versus that transported by a separated branch of the current on the Iceland slope (1.04 ± 0.15 Sv). Over the course of the year the total overflow transport is more consistent than the transport in either branch; compensation takes place among the pathways that maintains a stable total overflow transport. This is especially true for the two East Greenland Current branches whose transports vary out of phase with each other on weekly and longer time scales. We argue that wind forcing plays a role in this partitioning.The mooring and analysis work was supported by NSF OCE research grants OCE-0959381 and OCE-1433958, by the European Union 7th Framework Programme (FP7 2007-2013) under grant agreement n. 308299 NACLIM, and and by the Research Council of Norway through the Fram Centre Flaggship project 6606-299.2017-03-2

    Spatial distribution of air-sea heat fluxes over the sub-polar North Atlantic Ocean

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    Author Posting. © American Geophysical Union, 2012. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Geophysical Research Letters 39 (2012): L18806, doi:10.1029/2012GL053097.On a variety of spatial and temporal scales, the energy transferred by air-sea heat and moisture fluxes plays an important role in both atmospheric and oceanic circulations. This is particularly true in the sub-polar North Atlantic Ocean, where these fluxes drive water-mass transformations that are an integral component of the Atlantic Meridional Overturning Circulation (AMOC). Here we use the ECMWF Interim Reanalysis to provide a high-resolution view of the spatial structure of the air-sea turbulent heat fluxes over the sub-polar North Atlantic Ocean. As has been previously recognized, the Labrador and Greenland Seas are areas where these fluxes are large during the winter months. Our particular focus is on the Iceland Sea region where, despite the fact that water-mass transformation occurs, the winter-time air-sea heat fluxes are smaller than anywhere else in the sub-polar domain. We attribute this minimum to a saddle point in the sea-level pressure field, that results in a reduction in mean surface wind speed, as well as colder sea surface temperatures associated with the regional ocean circulation. The magnitude of the heat fluxes in this region are modulated by the relative strength of the Icelandic and Lofoten Lows, and this leads to periods of ocean cooling and even ocean warming when, intriguingly, the sensible and latent heat fluxes are of opposite sign. This suggests that the air-sea forcing in this area has large-scale impacts for climate, and that even modest shifts in the atmospheric circulation could potentially impact the AMOC.GWKM was supported by the Natural Science and Engineering Research Council of Canada. IAR was funded in part by NCAS (the National Centre for Atmospheric Sciences) and by NERC grant NE/I005293/1. RSP was funded by grant OCE-0959381 fromthe US National Science Foundation.2013-03-2
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