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  • 1.
    Abramson, Nils H.
    KTH, Skolan för industriell teknik och management (ITM).
    Holographic Metrology and Basic Physics2013Inngår i: Journal of Physics, Conference Series, ISSN 1742-6588, E-ISSN 1742-6596, Vol. 415, nr 1, s. 012030-Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A short pulse of light is emitted from one point followed by a short observation from another point separated in space and time from the first. Even if space is full of scattering particles no sphere of expanding light is seen from outside by the observer, instead he finds himself inside an ellipsoid of light. We use this ellipsoid for measurement and in a graphic way to explain and evaluate optical resolution, gated viewing, radar, holography, 3-D interferometry and Special Relativity. In the later case the Lorentz Contraction together with the Time Dilation are explained as results of the eccentricity of the measuring ellipsoid, caused by its velocity. Finally, the extremely thin ellipsoid of the very first light appears as a beam aimed directly at the observer which might explain the wave or ray duality of light and entanglement.

  • 2.
    Abtahi, Farhad
    et al.
    KTH, Skolan för teknik och hälsa (STH), Patientsäkerhet (Stängd 20130701).
    Gyllensten, Illapha Cuba
    KTH, Skolan för teknik och hälsa (STH).
    Lindecrantz, Kaj
    KTH, Skolan för teknik och hälsa (STH), Medicinska sensorer, signaler och system (MSSS) (Stängd 20130701).
    Seoane, Fernando
    KTH, Skolan för teknik och hälsa (STH), Medicinska sensorer, signaler och system (MSSS) (Stängd 20130701).
    Software tool for analysis of breathing-related errors in transthoracic electrical bioimpedance spectroscopy measurements2012Inngår i: Journal of Physics, Conference Series, ISSN 1742-6588, E-ISSN 1742-6596, Vol. 407, nr 1, s. 012028-Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    During the last decades, Electrical Bioimpedance Spectroscopy (EBIS) has been applied in a range of different applications and mainly using the frequency sweep-technique. Traditionally the tissue under study is considered to be timeinvariant and dynamic changes of tissue activity are ignored and instead treated as a noise source. This assumption has not been adequately tested and could have a negative impact and limit the accuracy for impedance monitoring systems. In order to successfully use frequency-sweeping EBIS for monitoring time-variant systems, it is paramount to study the effect of frequency-sweep delay on Cole Model-based analysis. In this work, we present a software tool that can be used to simulate the influence of respiration activity in frequency-sweep EBIS measurements of the human thorax and analyse the effects of the different error sources. Preliminary results indicate that the deviation on the EBIS measurement might be significant at any frequency, and especially in the impedance plane. Therefore the impact on Cole-model analysis might be different depending on method applied for Cole parameter estimation.

  • 3.
    Andersson, Magnus
    et al.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och tillämpad fysik, MAP.
    Espinosa-Arronte, Beatriz
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och tillämpad fysik, MAP.
    van der Beek, C. J.
    Nikolaou, M.
    Lidmar, J.
    KTH, Skolan för teknikvetenskap (SCI), Teoretisk fysik.
    Wallin, M.
    A vortex solid-to-liquid transition with fully anisotropic scaling2009Inngår i: Journal of Physics, Conference Series, ISSN 1742-6588, E-ISSN 1742-6596, Vol. 150, nr 5Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The vortex solid-to-liquid transition has been studied in heavy ion irradiated untwinned single crystals of YBa2Cu3O7-delta with an inclined applied magnetic field. For magnetic fields tilted at angles about 45 degrees away from the columnar defects, we find that the electric resistivity in the vortex liquid regime approaches zero with power laws in the reduced temperature T - T-c that have different exponents in all three spatial directions. Since the symmetry in the problem has been broken in two non-collinear directions by i) the direction of the columnar defects and ii) the direction of the applied magnetic field, our findings give evidence for a new type of critical behavior with fully anisotropic critical exponents. A possible view of the vortex topology for the transition is also suggested.

  • 4. Askinazi, L. G.
    et al.
    Kornev, V. A.
    Krikunov, S. V.
    Krupnik, L. I.
    Lebedev, S. V.
    Smirnov, A. I.
    Tendler, Michael
    KTH, Skolan för elektro- och systemteknik (EES), Fusionsplasmafysik. KTH, Skolan för elektro- och systemteknik (EES), Centra, Alfvénlaboratoriet.
    Tukachinsky, A. S.
    Vildjunas, M. I.
    Zhubr, N. A.
    Radial electric field evolution in various operational modes in the TUMAN-3M tokamak2008Inngår i: Journal of Physics, Conference Series, ISSN 1742-6588, E-ISSN 1742-6596, Vol. 123, s. 012010-Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Radial electric field evolution has been studied on the TUAMN-3M tokamak in different modes of operation: ohmic and NBI heating, L- and H-modes, with and without strong MHD activity. Peripheral radial electric field was measured using Langmuire probes, which were inserted up to 2cm inside LCFS, while core plasma potential evolution was measured using HIBP diagnostic. It was found, that in presence of strong MHD activity radial electric field in a vicinity of the island changed sign from negative to positive and could reach up to 4kV/m. Central plasma potential exhibited a positive perturbation of ∼700V during the MHD burst. This positive radial electric field might lead to H-mode termination, both in ohmic and NBI heating cases. Possible mechanism of the positive Er generation, namely the electron losses along ergodized magnetic field lines in the presence of MHD-island, is discussed. The same mechanism might be responsible for the positive potential spikes during a saw-tooth crash, also observed using HIBP. Another phenomenon observed using HIBP was quasi-coherent potential oscillations with the frequency close to one of the GAM. Possible location of these oscillations in the core region r/a ∼ 0.33 is discussed.

  • 5.
    Aurell, Erik
    KTH, Skolan för datavetenskap och kommunikation (CSC), Beräkningsbiologi, CB.
    The physics of distributed information systems2013Inngår i: Journal of Physics, Conference Series, ISSN 1742-6588, E-ISSN 1742-6596, Vol. 473, nr 1, s. 012017-Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    This paper aims to introduce Distributed Systems as a field where the ideas and methods of physics can potentially be applied, and to provide entry points to a wide literature. The contributions of Leslie Lamport, inspired by Relativity Theory, and of Edsger Dijkstra, which has the flavor of a growth process, are discussed at some length. The intent of the author is primarily to stimulate interest in the statistical physics community, and the discussions are therefore framed in a non-technical language; the author apologizes in advance to readers from the computer science side for the unavoidable impreciseness and ambiguities.

  • 6. Bazilevskaya, G. A.
    et al.
    Mayorov, A. G.
    Malakhov, V. V.
    Mikhailov, V. V.
    Adriani,
    Barbarino, G. C.
    Bellotti, R.
    Boezio, M.
    Bogomolov, E. A.
    Bonechi, L.
    Bongi, M.
    Bonvicini, V.
    Bottai, S.
    Bruno, A.
    Cafagna, F.
    Campana, D.
    Carbone, R.
    Carlson, Per
    KTH, Skolan för teknikvetenskap (SCI), Fysik, Partikel- och astropartikelfysik.
    Casolino, M.
    Castellini, G.
    Consiglio, L.
    De Pascale, M. P.
    De Santis, C.
    De Simone, N.
    Di Felice, V.
    Galper, A. M.
    Gillard, William
    KTH, Skolan för teknikvetenskap (SCI), Fysik, Partikel- och astropartikelfysik.
    Jerse, G.
    Karelin, A. V.
    Koldashov, S. V.
    Krutkov, S. Y.
    Kvashnin, A. N.
    Leonov, A.
    Marcelli, L.
    Menn, W.
    Mocchiutti, E.
    Monaco, A.
    Mori, N.
    Osteria, G.
    Palma, F.
    Papini, P.
    Pearce, Mark
    KTH, Skolan för teknikvetenskap (SCI), Fysik, Partikel- och astropartikelfysik.
    Picozza, P.
    Pizzolotto, C.
    Ricci, M.
    Ricciarini, S. B.
    Sarkar, R.
    Rossetto, Laura
    KTH, Skolan för teknikvetenskap (SCI), Fysik, Partikel- och astropartikelfysik.
    Simon, M.
    Sparvoli, R.
    Spillantini, P.
    Stozhkov, Y. I.
    Vacchi, A.
    Vannuccini, E.
    Vasilyev, G.
    Voronov, S. A.
    Wu, J.
    Yurkin, Y. T.
    Zampa, G.
    Zampa, N.
    Zverev, V. G.
    Solar energetic particle events in 2006-2012 in the PAMELA experiment data2013Inngår i: Journal of Physics, Conference Series, ISSN 1742-6588, E-ISSN 1742-6596, Vol. 409, nr 1Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The PAMELA magnetic spectrometer launched in June 2006 has observed the last strong energetic solar particle event of the 23rd solar cycle in December 2006. Subsequent long minimum of solar activity and weak development of the 24th solar cycle led to a deficit in the solar energetic particle events on the Earth orbit. As a result, only few events with protons accelerated above 100 MeV occurred in 2010-2012. The paper gives the preliminary results on energetic solar particles in the beginning of the 24th solar circle as measured with the PAMELA instrument.

  • 7.
    Bertilson, Michael
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Biomedicinsk fysik och röntgenfysik.
    von Hofsten, Olov
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Biomedicinsk fysik och röntgenfysik.
    Thieme, J.
    Lindblom, Magnus
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Biomedicinsk fysik och röntgenfysik.
    Holmberg, Anders
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Biomedicinsk fysik och röntgenfysik.
    Takman, Per
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Biomedicinsk fysik och röntgenfysik.
    Vogt, Ulrich
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Biomedicinsk fysik och röntgenfysik.
    Hertz, Hans
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Biomedicinsk fysik och röntgenfysik.
    First application experiments with the Stockholm compact soft x-ray microscope2009Inngår i: Journal of Physics, Conference Series, ISSN 1742-6588, E-ISSN 1742-6596, Vol. 186Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Most soft x-ray microscopes operating in the water window (lambda = 2.3 - 4.4 nm) rely on synchrotron radiation sources. In the future we believe scientists will use soft x-ray microscopes as one imaging tool among others in their own laboratory. For this purpose we have developed a full field soft x-ray microscope with a laser-plasma source compact enough to fit on an optical table. In this contribution we describe the current status of this microscope now featuring stable operation at lambda = 3.37 nm or lambda = 2.48 nm. In-house fabricated single element zone plates offering the possibility to perform phase contrast imaging have been implemented. We also report on the first application experiments for compact soft x-ray microscopy, including results from studies of clay minerals and colloids existing in nature and results from phase optics experiments. Planned upgrades of the microscope include increasing the source brightness, implementing more efficient condenser optics, and installing a cryo sample stage for tomography. These improvements will open up for further applications, especially in the field of biological imaging.

  • 8. Bertolini, S.
    et al.
    Luzio, L. D.
    Malinský, Michal
    KTH, Skolan för teknikvetenskap (SCI), Teoretisk fysik, Teoretisk partikelfysik.
    The quantum vacuum of the minimal SO(10) GUT2010Inngår i: Journal of Physics, Conference Series, ISSN 1742-6588, E-ISSN 1742-6596, Vol. 259, nr 1, s. 012098-Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    We reexamine the longstanding no-go excluding all potentially viable SO(10) →SU(3)c⊗ SU(2)L ⊗ U(1)Y symmetry breaking patterns within the minimal renormalizable non-supersymmetric SO(10) GUT framework featuring the 45-dimensional adjoint representation in the Higgs sector. A simple symmetry argument indicates that quantum effects do change the vacuum structure of the model dramatically. A thorough analysis of the one-loop effective potential reveals that the phenomenologically favoured symmetry breaking chains passing through the SU(4)C ⊗ SU(2)L ⊗ U(1)R or SU(3)c ⊗ SU(2)L ⊗ SU(2)R ⊗ U(1)B-L intermediate stages are, indeed, supported at the quantum level. This brings the class of minimal non-supersymmetric SO(10) GUTs back from oblivion, providing a new ground for a potentially realistic model building.

  • 9. Bevilacqua, R.
    et al.
    Pomp, S.
    Hayashi, M.
    Hirayama, S.
    Naito, Y.
    Watanabe, Y.
    Tippawan, U.
    Simutkin, V.
    Andersson, P.
    Blomgren, J.
    Österlund, M.
    Tesinsky, Milan
    KTH, Skolan för teknikvetenskap (SCI), Fysik, Reaktorfysik.
    Lecolley, F. -R
    Marie, N.
    Hjalmarsson, A.
    Prokofiev, A.
    Kolozhvari, A.
    Study of pre-equilibrium emission of light complex particles from Fe and Bi induced by intermediate energy neutrons2011Inngår i: Journal of Physics, Conference Series, ISSN 1742-6588, E-ISSN 1742-6596, Vol. 312, nr SECTION 8, s. 082013-Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    We have measured double differential cross sections (DDX) for emission of hydrogen- and helium-isotopes in the interaction of 175 MeV quasi-monoenergetic neutrons with Fe and Bi using the Medley setup at the The Svedberg Laboratory (Uppsala, Sweden). We compared experimental DDX with calculations with the TALYS code, which includes exciton model and Kalbach systematics; the code fails to reproduce the emission of complex light ions, generally overestimating it. We propose an correction for the application of the Kalbach phenomenological model in the TALYS code by introducing a new energy dependence for the nucleon transfer mechanism in the pre-equilibrium emission region. Our results suggest also evidence for multiple pre-equilibrium emission of composite particles at 175 MeV.

  • 10. Boezio, M.
    et al.
    Adriani, O.
    Ambriola, M.
    Barbarino, G. C.
    Basili, A.
    Bazilevskaja, G. A.
    Bellotti, R.
    Bogomolov, E. A.
    Bonechi, L.
    Bongi, M.
    Bongiorno, L.
    Bonvicini, V.
    Bruno, A.
    Cafagna, F.
    Campana, D.
    Carlson, P.
    KTH, Skolan för teknikvetenskap (SCI), Fysik, Partikel- och astropartikelfysik.
    Casolino, M.
    Castellini, G.
    De Pascale, M. P.
    De Rosa, G.
    Di Felice, V.
    Fedele, D.
    Galper, A. M.
    Hofverberg, P.
    KTH.
    Koldashov, S. V.
    Krutkov, S. Y.
    Kvashnin, A. N.
    Lundquist, J.
    Maksumov, O.
    Malvezzi, V.
    Marcelli, L.
    Menn, W.
    Mikhailov, V. V.
    Minori, M.
    Misin, S.
    Mocchiutti, E.
    Morselli, A.
    Nikonov, N. N.
    Orsi, S.
    KTH.
    Osteria, G.
    Papini, P.
    Pearce, Mark
    KTH, Skolan för teknikvetenskap (SCI), Fysik, Partikel- och astropartikelfysik.
    Picozza, P.
    Ricci, M.
    Ricciarini, S. B.
    Runtso, M. F.
    Russo, S.
    Simon, M.
    Sparvoli, R.
    Spillantini, P.
    Stozhkov, Y. I.
    Taddei, E.
    Vacchi, A.
    Vannuccini, E.
    Vasilyev, G.
    Voronov, S. A.
    Yurkin, Y. T.
    Zampa, G.
    Zampa, N.
    Zverev, V. G.
    The PAMELA space experiment: First year of operation2008Inngår i: Journal of Physics, Conference Series, ISSN 1742-6588, E-ISSN 1742-6596, Vol. 110, nr 6, artikkel-id 062002Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    On the 15th of June 2006 the PAMELA experiment, mounted on the Resurs DK1 satellite, was launched from the Baikonur cosmodrome and it has been collecting data since July 2006. PAMELA is a satellite-borne apparatus designed to study charged particles in the cosmic radiation, to investigate the nature of dark matter, measuring the cosmic-ray antiproton and positron spectra over the largest energy range ever achieved, and to search for antinuclei with unprecedented sensitivity. The apparatus comprises a time-of-flight system, a silicon-microstrip magnetic spectrometer, a silicon-tungsten electromagnetic calorimeter, an anticoincidence system, a shower tail catcher scintillator and a neutron detector. The combination of these devices allows charged particle identification over a wide energy range. © 2008 IOP Publishing Ltd.

  • 11. Bolognesi, P.
    et al.
    O'Keeffe, P.
    Feyer, V.
    Plekan, O.
    Prince, K.
    Coreno, M.
    Mattioli, G.
    Amore Bonapasta, A.
    Zhang, Wenhua
    KTH, Skolan för bioteknologi (BIO), Teoretisk kemi (stängd 20110512). University of Science and Technology of China, Hefei, China .
    Carravetta, V.
    Ovcharenko, Y.
    Avaldi, L.
    Inner shell excitation, ionization and fragmentation of pyrimidine2010Inngår i: Journal of Physics, Conference Series, ISSN 1742-6588, E-ISSN 1742-6596, Vol. 212, s. 012002-Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The inner shell excitation and ionisation of pyrimidine have been studied at the carbon K edge by near-edge X ray absorption fine structure (NEXAFS) and X ray photoelectron (XPS) spectroscopies. The theoretical predictions of density functional theory (DFT) provide a satisfactory assignment of the complex spectra of this polyatomic molecule. The fragmentation following the C(1s -1)π* excitation has been investigated by resonant Auger electron-ion coincidence spectroscopy, which allows a site and state selective study.

  • 12. Bonvicini, V.
    et al.
    Boezio, M.
    Mocchiutti, E.
    Vacchi, A.
    Zampa, G.
    Zampa, N.
    Bellotti, R.
    Bruno, A.
    Cafagna, F.
    Adriani, O.
    Bonechi, L.
    Bongi, M.
    Bottai, S.
    Fedele, D.
    Papini, P.
    Ricciarini, S.
    Spillantini, P.
    Taddei, E.
    Vannuccini, E.
    Castellini, G.
    Ricci, M.
    Basilevskaja, A.
    Kvashnin, N.
    Stozhkov, I.
    Galper, M.
    Grishantseva, L.
    Koldashov, V.
    Leonov, A.
    Mikhailov, V.
    Voronov, A.
    Yurkin, T.
    Zverev, G.
    Barbarino, G.
    De Rosa, G.
    Osteria, G.
    Campana, D.
    Casolino, M.
    De Pascale, P.
    Malvezzi, V.
    Marcelli, L.
    Minori, M.
    Picozza, P.
    Sparvoli, R.
    Bogomolov, A.
    Krutkov, Y.
    Vasilyev, G.
    Menn, W.
    Simon, M.
    Carlson, Per
    KTH, Skolan för teknikvetenskap (SCI), Fysik, Partikel- och astropartikelfysik.
    Hofverberg, Petter
    KTH, Skolan för teknikvetenskap (SCI), Fysik, Partikel- och astropartikelfysik.
    Orsi, Silvio
    KTH, Skolan för teknikvetenskap (SCI), Fysik, Partikel- och astropartikelfysik.
    Pearce, Mark
    KTH, Skolan för teknikvetenskap (SCI), Fysik, Partikel- och astropartikelfysik.
    Performance of the PAMELA Si-W imaging calorimeter in space2009Inngår i: Journal of Physics, Conference Series, ISSN 1742-6588, E-ISSN 1742-6596, Vol. 160, s. 012039-Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The Payload for Antimatter-Matter Exploration and Light Nuclei Astrophysics (PAMELA), primarily designed to directly measure antiparticles (antiprotons and positrons) in the cosmic radiation, was launched successfully on June 15th, 2006, and, since then, it is in continuous data taking. The calorimeter of the PAMELA apparatus has been designed to identify antiprotons from an electron background and positrons from a background of protons with high efficiency and rejection power. It is a sampling silicon-tungsten imaging calorimeter, which comprises 44 single-sided silicon sensor planes (380 μm thick) interleaved with 22 plates of tungsten absorber (0.74 X0 each). It is the first silicon-tungsten calorimeter to be launched in space. In this work we present the in-orbit performance of the calorimeter, including the measured identification capabilities. The calorimeter provides a proton rejection factor of ∼105 while keeping a high efficiency in selecting electrons and positrons, thus fulfilling the identification power needed to reach the primary scientific objectives of PAMELA. We show also that, after almost two years of operation in space, the calorimeter is still performing nominally.

  • 13.
    Brinne Roos, Johanna
    et al.
    KTH, Skolan för bioteknologi (BIO), Teoretisk kemi.
    Larson, Åsa
    KTH, Skolan för bioteknologi (BIO), Teoretisk kemi.
    Orel, Ann E.
    A direct, local model of dissociative recombination of HF+2009Inngår i: Journal of Physics, Conference Series, ISSN 1742-6588, E-ISSN 1742-6596, Vol. 192Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The direct mechanism of dissociative recombination of HF+ have been studied by propagating wave packets on 30 resonant states. The relevant electronic states have been calculated ab initio with electron scattering calculations and multireference configuration interaction calculations. We obtain a qualitative good agreement with experiments for energies in the range from 0.04 eV to 10 eV. Some of the structures in the experimental cross section can be explained by the direct capture and dissociation along the resonant states. To fully describe the measured cross section, the electronic couplings between the neutral states cannot be neglected.

  • 14.
    Cameron, David
    et al.
    University of Oslo, Nordic Data Grid Facility, Kastrup, Danmark.
    Gholami, Ali
    KTH, Skolan för datavetenskap och kommunikation (CSC), Centra, Parallelldatorcentrum, PDC.
    Karpenko, Dmytro
    University of Oslo.
    Konstantinov, Aleksandr
    University of Oslo, Vilnius University Institute of Applied Research.
    Adaptive data management in the ARC Grid middleware2011Inngår i: Journal of Physics, Conference Series, ISSN 1742-6588, E-ISSN 1742-6596, Vol. 331, nr 062006Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The Advanced Resource Connector (ARC) Grid middleware was designed almost 10 years ago, and has proven to be an attractive distributed computing solution and successful in adapting to new data management and storage technologies. However, with an ever-increasing user base and scale of resources to manage, along with the introduction of more advanced data transfer protocols, some limitations in the current architecture have become apparent. The simple first-in first-out approach to data transfer leads to bottlenecks in the system, as does the built-in assumption that all data is immediately available from remote data storage. We present an entirely new data management architecture for ARC which aims to alleviate these problems, by introducing a three-layer structure. The top layer accepts incoming requests for data transfer and directs them to the middle layer, which schedules individual transfers and negotiates with various intermediate catalog and storage systems until the physical file is ready to be transferred. The lower layer performs all operations which use large amounts of bandwidth, i.e. the physical data transfer. Using such a layered structure allows more efficient use of the available bandwidth as well as enabling late-binding of jobs to data transfer slots based on a priority system. Here we describe in full detail the design and implementation of the new system.

  • 15.
    Candelaresi, Simon
    KTH, Centra, Nordic Institute for Theoretical Physics NORDITA. AlbaNova University Center, Stockholm University, Sweden .
    Topological constraints in magnetic field relaxation2014Inngår i: Journal of Physics, Conference Series, ISSN 1742-6588, E-ISSN 1742-6596, Vol. 544, nr 1, artikkel-id 012006Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Stability and reconnection of magnetic fields play a fundamental role in natural and manmade plasma. In these applications the field's topology determines the stability of the magnetic field. Here I will describe the importance of one topology quantifier, the magnetic helicity, which impedes any free decay of the magnetic energy. Further constraints come from the fixed point index which hinders the field to relax into the Taylor state.

  • 16. Castellani, F.
    et al.
    Astolfi, D.
    Mana, M.
    Becchetti, M.
    Segalini, Antonio
    KTH, Skolan för teknikvetenskap (SCI), Mekanik, Strömningsfysik. KTH, Skolan för teknikvetenskap (SCI), Centra, Linné Flow Center, FLOW.
    Wake losses from averaged and time-resolved power measurements at full scale wind turbines2017Inngår i: Journal of Physics, Conference Series, ISSN 1742-6588, E-ISSN 1742-6596, Vol. 854, nr 1, artikkel-id 012006Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    This work deals with the experimental analysis of wake losses fluctuations at full-scale wind turbines. The test case is a wind farm sited on a moderately complex terrain: 4 turbines are installed, having 2 MW of rated power each. The sources of information are the time-resolved data, as collected from the OPC server, and the 10-minutes averaged SCADA data. The objective is to compare the statistical distributions of wake losses for far and middle wakes, as can be observed through the "fast" lens of time-resolved data, for certain selected test-case time series, and through the "slow" lens of SCADA data, on a much longer time basis that allow to set the standards of the mean wake losses along the wind farm. Further, time-resolved data are used for an insight into the spectral properties of wake fluctuations, highlighting the role of the wind turbine as low-pass filter. Summarizing, the wind rose, the layout of the site and the structure of the data sets at disposal allow to study middle and far wake behavior, with a "slow" and "fast" perspective.

  • 17. Cocolios, T. E.
    et al.
    Andreyev, A. N.
    Antalic, S.
    Barzakh, A. E.
    Bastin, B.
    Büscher, J.
    Darby, I. G.
    Dexters, W.
    Fedorov, D. V.
    Fedosseev, V. N.
    Flanagan, K. T.
    Franchoo, S.
    Fritzsche, S.
    Huber, G.
    Huyse, M.
    Keupers, M.
    Köster, U.
    Kudryavtsev, Y.
    Mané, E.
    Marsh, B. A.
    Molkanov, P. L.
    Page, R. D.
    Seliverstov, M. D.
    Sjödin, Marica
    KTH, Skolan för teknikvetenskap (SCI), Fysik, Kärnfysik.
    Stefan, I.
    Walle, J. V. D.
    Duppen, P. V.
    Venhart, M.
    Zemlyanoy, S. G.
    Early onset of deformation in the neutron-deficient polonium isotopes2012Inngår i: Journal of Physics, Conference Series, ISSN 1742-6588, E-ISSN 1742-6596, Vol. 381, nr 1, s. 012072-Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    In-source laser spectroscopy has been performed at CERN-ISOLDE with the RILIS laser ion source on 191-204,206,208-211,216,218Po. New information on the β decay of 199Po were extracted in the process, challenging previous results. Large-scale atomic calculations were performed to extract the changes in the mean-square charge radius δr 2 from the isotope shifts. The δ«r» 2 for the even-A isotopes reveal a large deviation from the spherical droplet model for N < 116.

  • 18. Di Siena, A.
    et al.
    Görier, T.
    Doerk, H.
    Citrin, J.
    Johnson, Thomas
    KTH, Skolan för elektro- och systemteknik (EES), Fusionsplasmafysik.
    Schneider, M.
    Poli, E.
    Non-Maxwellian background effects in gyrokinetic simulations with GENE2016Inngår i: Journal of Physics, Conference Series, ISSN 1742-6588, E-ISSN 1742-6596, Vol. 775, nr 1, artikkel-id 012003Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The interaction between fast particles and core turbulence has been established as a central issue for a tokamak reactor. Recent results predict significant enhancement of electromagnetic stabilisation of ITG turbulence in the presence of fast ions. However, most of these simulations were performed with the assumption of equivalent Maxwellian distributed particles, whereas to rigorously model fast ions, a non-Maxwellian background distribution function is needed. To this aim, the underlying equations in the gyrokinetic code GENE have been re-derived and implemented for a completely general background distribution function. After verification studies, a previous investigation on a particular JET plasma has been revised with linear simulations. The plasma is composed by Deuterium, electron, Carbon impurities, NBI fast Deuterium and ICRH 3He. Fast particle distributions have been modelled with a number of different analytic choices in order to study the impact of non-Maxwellian distributions on the plasma turbulence: slowing down and anisotropic Maxwellian. Linear growth rates are studied as a function of the wave number and compared with those obtained using an equivalent Maxwellian. Generally, the choice of the 3He distribution seems to have a stronger impact on the microinstabilities than that of the fast Deuterium.

  • 19.
    Eitel-Amor, Georg
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Mekanik. KTH, Skolan för teknikvetenskap (SCI), Centra, Linné Flow Center, FLOW.
    Flores, O.
    Schlatter, Philipp
    KTH, Skolan för teknikvetenskap (SCI), Mekanik. KTH, Skolan för teknikvetenskap (SCI), Centra, Linné Flow Center, FLOW.
    Hairpin vortices in turbulent boundary layers2014Inngår i: Journal of Physics, Conference Series, ISSN 1742-6588, E-ISSN 1742-6596, Vol. 506, nr 1, s. 012008-Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The present work addresses the question whether hairpin vortices are a dominant feature of near-wall turbulence and which role they play during transition. First, the parent-offspring mechanism is investigated in temporal simulations of a single hairpin vortex introduced in a mean shear flow corresponding to turbulent channels and boundary layers up to Re-tau = 590. Using an eddy viscosity computed from resolved simulations, the effect of a turbulent background is also considered. Tracking the vortical structure downstream, it is found that secondary hairpins are created shortly after initialization. Thereafter, all rotational structures decay, whereas this effect is enforced in the presence of an eddy viscosity. In a second approach, a laminar boundary layer is tripped to transition by insertion of a regular pattern of hairpins by means of defined volumetric forces representing an ejection event. The idea is to create a synthetic turbulent boundary layer dominated by hairpin-like vortices. The flow for Re-tau < 250 is analysed with respect to the lifetime of individual hairpin-like vortices. Both the temporal and spatial simulations demonstrate that the regeneration process is rather short-lived and may not sustain once a turbulent background has formed. From the transitional flow simulations, it is conjectured that the forest of hairpins reported in former DNS studies is an outer layer phenomenon not being connected to the onset of near-wall turbulence.

  • 20.
    El Khoury, George K.
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Mekanik. KTH, Skolan för teknikvetenskap (SCI), Centra, Linné Flow Center, FLOW.
    Schlatter, Philipp
    KTH, Skolan för teknikvetenskap (SCI), Mekanik. KTH, Skolan för teknikvetenskap (SCI), Centra, Linné Flow Center, FLOW.
    Brethouwer, Geert
    KTH, Skolan för teknikvetenskap (SCI), Mekanik, Turbulens. KTH, Skolan för teknikvetenskap (SCI), Centra, Linné Flow Center, FLOW.
    Johansson, Arne V.
    KTH, Skolan för teknikvetenskap (SCI), Mekanik, Turbulens. KTH, Skolan för teknikvetenskap (SCI), Centra, Linné Flow Center, FLOW.
    Turbulent pipe flow: Statistics, Re-dependence, structures and similarities with channel and boundary layer flows2014Inngår i: Journal of Physics, Conference Series, ISSN 1742-6588, E-ISSN 1742-6596, Vol. 506, nr 1, s. 012010-Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Direct numerical simulation data of fully developed turbulent pipe flow are extensively compared with those of turbulent channel flow and zero-pressure-gradient boundary layer flow for Re-tau up to 1 000. In the near-wall region, a high degree of similarity is observed in the three flow cases in terms of one-point statistics, probability density functions of the wall-shear stress and pressure, spectra, Reynolds stress budgets and advection velocity of the turbulent structures. This supports the notion that the near-wall region is universal for pipe and channel flow. Probability density functions of the wall shear stress, streamwise turbulence intensities, one-dimensional spanwise/azimuthal spectra of the streamwise velocity and Reynolds-stress budgets are very similar near the wall in the three flow cases, suggesting that the three cauonical wall-bounded flows share wally features. In the wake region, the wean streamwise velocity and Reynolds stress budgets show smile expected differences.

  • 21.
    Elfström, Niklas
    et al.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Materialfysik.
    Linnros, Jan
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Materialfysik.
    Sensitivity of silicon nanowires in biosensor applications2008Inngår i: Journal of Physics, Conference Series, ISSN 1742-6588, E-ISSN 1742-6596, Vol. 100, nr PART 5Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A 2-dimensional simulation tool was designed to investigate the threshold voltage behaviour for a silicon nanowire constructed in a top down approach on silicon on insulator (SOI) material. The simulation shows, assuming a positive charge of +1.10(11) cm(-2) between the silicon/silicon dioxide interface and negatively charged surface states on top of the nanowire that the threshold voltage increases with decreasing height of the nanowire.

  • 22.
    Eriksson, O.
    et al.
    KTH. Uppsala University, Sweden .
    Mikkelsen, R.
    Hansen, K. S.
    Nilsson, K.
    KTH. Uppsala University, Sweden .
    Ivanell, Stefan
    KTH, Skolan för teknikvetenskap (SCI), Mekanik, Stabilitet, Transition, Kontroll. Uppsala University, Sweden .
    Analysis of long distance wakes of Horns Rev I using actuator disc approach2014Inngår i: Journal of Physics, Conference Series, ISSN 1742-6588, E-ISSN 1742-6596, Vol. 555, nr 1, artikkel-id 012032Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The wake recovery behind the Horns Rev wind farm is analysed to investigate the applicability of Large Eddy Simulations (LES) in combination with an actuator disc method (ACD) for farm to farm interaction studies. Periodic boundary conditions on the lateral boundaries are used to model the wind farm (as infinitely wide), using only two columns of turbines. The meteorological conditions of the site are taken into account by introducing wind shear and pre-generated synthetic turbulence to the simulation domain using body forces. Simulations are carried out to study the power production and the velocity deficit in the farm wake. The results are compared to the actual power production as well as to wind measurements at 2 km and 6 km behind the wind farm. The simulated power production inside the farm shows an overall good correlation with the real production, but is slightly overpredicted in the most downstream rows. The simulations overpredict the wake recovery, namely the wind velocity, at long distances behind the farm. Further studies are needed before the presented method can be applied for the simulation of long distance wakes. Suggested parameters to be studied are the development of the turbulence downstream in the domain and the impact of the grid resolution.

  • 23. Fenu, F.
    et al.
    Piotrowski, L. W.
    Shin, H.
    Jung, A.
    Bacholle, S.
    Bisconti, F.
    Capel, Francesca
    KTH, Skolan för teknikvetenskap (SCI), Fysik, Partikel- och astropartikelfysik.
    Eser, J.
    Kawasaki, Y.
    Kuznetsov, E.
    Larsson, O.
    Mackovjak, S.
    Miyamoto, H.
    Plebaniak, Z.
    Prevot, G.
    Putis, M.
    Shinozaki, K.
    Adams, J.
    Bertaina, M.
    Bobik, P.
    Casolino, M.
    Matthews, J. N.
    Ricci, M.
    Wiencke, L.
    Preliminary analysis of EUSO - TA data2016Inngår i: Journal of Physics, Conference Series, ISSN 1742-6588, E-ISSN 1742-6596, Vol. 718, nr 5, artikkel-id 52011Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The EUSO-TA detector is a pathfinder for the JEM-EUSO project and is currently installed in Black Rock Mesa (Utah) on the site of the Telescope Array fluorescence detectors. Aim of this experiment is to validate the observation principle of JEM-EUSO on air showers measured from ground. The experiment gets data in coincidence with the TA triggers to increase the likelihood of cosmic ray detection. In this framework the collaboration is also testing the detector response with respect to several test events from lasers and LED flashers. Moreover, another aim of the project is the validation of the stability of the data acquisition chain in real sky condition and the optimization of the trigger scheme for the rejection of background. Data analysis is ongoing to identify cosmic ray events in coincidence with the TA detector. In this contribution we will show the response of the EUSO-TA detector to all the different typologies of events and we will show some preliminary results on the trigger optimization performed on such data.

  • 24. Fokas, A. S.
    et al.
    Lenells, Jonatan
    Perturbative and exact results on the neumann value for the nonlinear Schrödinger on the half-line2014Inngår i: Journal of Physics, Conference Series, ISSN 1742-6588, E-ISSN 1742-6596, Vol. 482, nr 1, artikkel-id 012015Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The most challenging problem in the implementation of the so-called unified transform to the analysis of the nonlinear Schrödinger equation on the half-line is the characterization of the unknown boundary value in terms of the given initial and boundary conditions. For the so-called linearizable boundary conditions this problem can be solved explicitly. Furthermore, for non-linearizable boundary conditions which decay for large t, this problem can be largely bypassed in the sense that the unified transform yields useful asymptotic information for the large t behavior of the solution. However, for the physically important case of periodic boundary conditions it is necessary to characterize the unknown boundary value. Here, we first present a perturbative scheme which can be used to compute explicitly the asymptotic form of the Neumann boundary value in terms of the given τ-periodic Dirichlet datum to any given order in a perturbation expansion. We then discuss briefly an extension of the pioneering results of Boutet de Monvel and co-authors which suggests that if the Dirichlet datum belongs to a large class of particular τ-periodic functions, which includes {a exp(iωt)|a &gt; 0, ω ≥ a2}, then the large t behavior of the Neumann value is given by a τ-periodic function which can be computed explicitly.

  • 25. Galper, A. M.
    et al.
    Sparvoli, R.
    Adriani, O.
    Barbarino, G.
    Bazilevskaya, G. A.
    Bellotti, R.
    Boezio, M.
    Bogomolov, E. A.
    Bongi, M.
    Bonvicini, V.
    Bottai, S.
    Bruno, A.
    Cafagna, F.
    Campana, D.
    Carlson, Per
    KTH, Skolan för teknikvetenskap (SCI), Fysik, Partikel- och astropartikelfysik.
    Casolino, M.
    Castellini, G.
    De Donato, C.
    De Santis, C.
    Di Felice, V.
    Karelin, A. V.
    Koldashov, S. V.
    Koldobskiy, S. A.
    Krutkov, S. Y.
    Kvashnin, A. N.
    Leonov, A. A.
    Malakhov, V. V.
    Marcelli, L.
    Martucci, M.
    Mayorov, A. G.
    Menn, W.
    Merge, M.
    Mikhailov, V. V.
    Mocchiutti, E.
    Mori, N.
    Munini, R.
    Osteria, G.
    Palma, F.
    Panico, B.
    Papini, P.
    Pearce, Mark
    KTH, Skolan för teknikvetenskap (SCI), Fysik, Partikel- och astropartikelfysik.
    Picozza, P.
    Ricci, M.
    Ricciarini, S. B.
    Simon, M.
    Spillantini, P.
    Stozhkov, Y. I.
    Vacchi, A.
    Vannuccini, E.
    Vasilyev, G. I.
    Voronov, S. A.
    Yurkin, Y. T.
    Zampa, G.
    Zampa, N.
    The PAMELA experiment: A decade of Cosmic Ray Physics in space2017Inngår i: Journal of Physics, Conference Series, ISSN 1742-6588, E-ISSN 1742-6596, Vol. 798, nr 1, artikkel-id 012033Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The PAMELA detector was launched on June 15 th of 2006 on board the Russian Resurs-DK1 satellite and during ten years of continuous data-taking it has observed very interesting features in cosmic rays, especially in the fluxes of protons, helium and electrons. Moreover, PAMELA measurements of cosmic antiproton and positron fluxes and positron-to-all-electron ratio have set strong constraints to the nature of Dark Matter. Measurements of boron, carbon, lithium and beryllium (together with the isotopic fraction) have also shed new light on the elemental composition of the cosmic radiation. Search for signatures of more exotic processes (such as the ones involving Strange Quark Matter) has also been pursued. Furthermore, over the years the instrument has allowed a constant monitoring of the solar activity and a prolonged study of the solar modulation, improving the comprehension of the heliosphere mechanisms. PAMELA has also measured the radiation environment around the Earth, and detected for the first time the presence of an antiproton radiation belt surrounding our planet. In this highlight paper PAMELA main results will be reviewed.

  • 26. Geppert, W. D.
    et al.
    Vigren, E.
    Hamberg, M.
    Zhaunerchyk, V.
    Thomas, R. D.
    Kamińska, M.
    Millar, T. J.
    Semaniak, J.
    Roberts, H.
    Hellberg, F.
    Österdahl, Fabian
    KTH, Skolan för teknikvetenskap (SCI), Fysik.
    Ehlerding, A.
    Larsson, M.
    Formation of biomolecule precursors in space2007Inngår i: Journal of Physics, Conference Series, ISSN 1742-6588, E-ISSN 1742-6596, Vol. 88, nr 1, s. 012068-Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Alcohols and nitriles not only play an important role as templates for synthesis of larger molecules in the interstellar medium and planetary atmospheres, but they can also be regarded as precursors for biomolecules. Alcohols can form carbohydrates through reaction with HCO and nitriles can be hydrolysed to amino acids in aqueous solutions, which is the final step of the well-known Strecker synthesis. Therefore the question of the pathways of formation of alcohols and nitriles and the efficiency and the product distribution of their subsequent degradation reactions in the above-mentioned astrophysical environments is of great interest. In both processes dissociative recombination reactions of protonated nitriles and alcohols may play a major role and are included in models of interstellar clouds and planetary atmospheres. However, the reaction rate coefficients and product branching ratios for the majority of these processes are so far still unknown, which adversely affects the quality of predictions of model calculations. In this Contribution, we therefore present branching ratios and rate constants of the dissociative recombination of protonated methanol (CH3OH 2), as well as protonated acetonitrile (CH3CNH +), acrylonitrile (C2H3CNH+) and cyanoacetylene (HC3NH+). The impact of the obtained new data on model calculations of abundances of important interstellar molecules in dark clouds is discussed.

  • 27. Gleber, S. -C
    et al.
    Sedlmair, J.
    Bertilson, Michael
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Biomedicinsk fysik och röntgenfysik.
    Von Hofsten, Olov
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Biomedicinsk fysik och röntgenfysik.
    Heim, S.
    Guttmann, P.
    Hertz, Hans
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Biomedicinsk fysik och röntgenfysik.
    Fischer, P.
    Thieme, J.
    X-ray stereo microscopy for investigation of dynamics in soils2009Inngår i: Journal of Physics, Conference Series, ISSN 1742-6588, E-ISSN 1742-6596, Vol. 186, s. 012104-Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The here presented combination of stereo imaging and elemental mapping with soft X-ray microscopy reveals the spatial arrangement of naturally aqueous colloidal systems, e.g. iron oxides in soil colloid clusters. Changes in the spatial arrangement can be induced by manipulating the sample in-situ and thus be investigated directly and as a function of time.

  • 28. Gvozdic, D. M.
    et al.
    Ekenberg, Ulf
    KTH, Skolan för informations- och kommunikationsteknik (ICT).
    Strong dependence of spin direction and wave function localization on In-plane wave vector in wide modulation-doped quantum wells2007Inngår i: Journal of Physics, Conference Series, ISSN 1742-6588, E-ISSN 1742-6596, Vol. 61, nr 1, s. 273-277Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    An important mechanism in spintronics is spin-splitting induced by structure and/or bulk inversion asymmetry. These effects are frequently assumed to depend on two parameters usually denoted by α and β respectively, and α is assumed to be proportional to some average electric field. We here demonstrate that the spatial dependence of the electric field gives very important effects absent in simpler models. These effects are particularly clear in wide modulation-doped quantum wells where there are two weakly interacting electron gases in the interface regions. Using an 8 × 8 k . p matrix approach we obtain anticrossings between interacting subbands at which the spin direction and/or wave function localization are found to be strong functions of the in-plane wave vector.

  • 29.
    Haghighi, Ehsan Bitaraf
    et al.
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik.
    Anwar, Zahid
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik.
    Lumbreras, Itziar
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik.
    Mirmohammadi, Seyed Aliakbar
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik.
    Behi, Mohammadreza
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik.
    Khodabandeh, Rahmatollah
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Tillämpad termodynamik och kylteknik.
    Palm, Björn
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Tillämpad termodynamik och kylteknik.
    Screening Single Phase Laminar Convective Heat Transfer of Nanofluids in a Micro-tube2012Inngår i: Journal of Physics, Conference Series, ISSN 1742-6588, E-ISSN 1742-6596, Vol. 395, artikkel-id 012036Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Nano scale solid particles dispersed in base fluids are a new class of engineered colloidal solutions called nanofluids. Several studies reported enhancement of heat transfer by using nanofluids. This article reports convective single-phase heat transfer coefficients in an open 30 cm long, 0.50 mm internal diameter stainless steel test section. The setup is used for screening single phase laminar convective heat transfer with water and three different nanofluids: water based Al2O3, ZrO2, and TiO2 (all with 9 wt% of particles). A syringe pump with adjustable pumping speed is used to inject fluids into the test section. Thirteen T-type thermocouples are attached on the outer surface of the test section to record the local wall temperatures. Furthermore, two T-type thermocouples are used to measure inlet and outlet fluid temperatures. A DC power supply is used to heat up the test section and a differential pressure transducer is used to measure the pressure drop across the tube. Furthermore, the effective thermal conductivities of these nanofluids are measured using the Transient Plane Source (TPS) method at a temperature range of 20 - 50 degrees C. The experimental average values of heat transfer coefficients for nanofluids are compared with water. Enhancement in heat transfer of nanofluids is observed only when compared at constant Reynolds number (Due to higher viscosity for nanofluids, higher velocity or mass flow rate is required for nanofluids to reach the same Reynolds number). The other methods of comparison: equal mass flow rate, volume flow rate, pressure drop and pumping power did not show any augmentation of the heat transfer coefficient for the tested nanofluids compared to water.

  • 30.
    Hellsten, Torbjörn
    et al.
    KTH, Skolan för elektro- och systemteknik (EES), Fusionsplasmafysik.
    Hannan, Abdul
    KTH, Skolan för elektro- och systemteknik (EES), Fusionsplasmafysik.
    Johnson, Thomas
    KTH, Skolan för elektro- och systemteknik (EES), Fusionsplasmafysik.
    Höök, Lars Josef
    KTH, Skolan för elektro- och systemteknik (EES), Fusionsplasmafysik.
    Villard, L.
    A dielectric response model for FEM solutions of ICRF wave fields2012Inngår i: Journal of Physics, Conference Series, ISSN 1742-6588, E-ISSN 1742-6596, Vol. 401, nr 1, s. 012009-Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Modelling of fast wave ICRF heating in large machines with high density such as DEMO is challenging because of the short wave lengths. Therefore, fast, efficient global wave solvers are necessary. A major difficulty with calculating the wave field in a spatial dispersive medium is that the dielectric tensor becomes a function of the local wave vector, which in its turn depends on the solution. Furthermore, the solution may consist of several waves co-existing at the same location subjected to separate response functions. In order to model upshift of the parallel wave vector, higher order FLR-effects on the cyclotron absorption and TTMP damping for the electron absorption methods based on iteration, suitable for FEM codes, are proposed.

  • 31.
    Herrero-Garcia, Juan
    KTH, Skolan för teknikvetenskap (SCI), Teoretisk fysik.
    Predicting the capture rate in the Sun from a direct detection signal independently of the astrophysics2016Inngår i: Journal of Physics, Conference Series, ISSN 1742-6588, E-ISSN 1742-6596, Vol. 718, nr 4, artikkel-id 42027Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The goal of the works on which this talk is based is to relate a direct detection signal with neutrino limits from the Sun independently of the astrophysics. In order to achieve this we derive a halo-independent lower bound on the dark matter capture rate in the Sun from a direct detection signal, with which one can set upper limits on the branching ratios into different channels from the absence of a high-energy neutrino flux in neutrino observatories. We also extend this bound to the case of inelastic scattering, both endothermic and exothermic. From two inelastic signals we show how the dark matter mass, the mass difference of the states and the couplings to neutrons and protons can be obtained. Furthermore, one can also pin down the exothermic/endothermic nature of the scattering, and therefore a precise lower bound on the solar capture rate is predicted. We also discuss isospin violation and uncertainties due to form factors.

  • 32.
    Hertz, Hans M.
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Biomedicinsk fysik och röntgenfysik.
    Bertilson, Michael
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Biomedicinsk fysik och röntgenfysik.
    Chubarova, Elena
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Biomedicinsk fysik och röntgenfysik.
    Ewald, Johannes
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Biomedicinsk fysik och röntgenfysik.
    Gleber, S-C
    Hemberg, Oscar
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Biomedicinsk fysik och röntgenfysik.
    Henriksson, M.
    von Hofsten, Olov
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Biomedicinsk fysik och röntgenfysik.
    Holmberg, Anders
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Biomedicinsk fysik och röntgenfysik.
    Lindblom, Magnus
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Biomedicinsk fysik och röntgenfysik.
    Mudry, Emeric
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Biomedicinsk fysik och röntgenfysik.
    Otendal, Mikael
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Biomedicinsk fysik och röntgenfysik.
    Reinspach, Julia
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Biomedicinsk fysik och röntgenfysik.
    Schlie, Moritz Gustav
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Biomedicinsk fysik och röntgenfysik.
    Skoglund, Peter
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Biomedicinsk fysik och röntgenfysik.
    Takman, Per
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Biomedicinsk fysik och röntgenfysik.
    Thieme, J.
    Sedlmair, J.
    Tjörnhammar, Richard
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Biomedicinsk fysik och röntgenfysik.
    Tuohimaa, Tomi
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Biomedicinsk fysik och röntgenfysik.
    Vita, M.
    Vogt, Ulrich
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Biomedicinsk fysik och röntgenfysik.
    Laboratory x-ray micro imaging: Sources, optics, systems and applications2009Inngår i: Journal of Physics, Conference Series, ISSN 1742-6588, E-ISSN 1742-6596, Vol. 186Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    We summarize the recent progress in laboratory-scale soft and hard x-ray micro imaging in Stockholm. Our soft x-ray work is based on liquid-jet laser-plasma sources which are combined with diffractive and multilayer optics to form laboratory x-ray microscopes. In the hard x-ray regime the imaging is based on a liquid-metal-jet electron-impact source which provides the necessary coherence to allow phase-contrast imaging with high fidelity.

  • 33.
    Holmberg, Anders
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Biomedicinsk fysik och röntgenfysik.
    Lindblom, Magnus
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Biomedicinsk fysik och röntgenfysik.
    Reinspach, Julia
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Biomedicinsk fysik och röntgenfysik.
    Bertilson, Michael
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Biomedicinsk fysik och röntgenfysik.
    Hertz, Hans M.
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Biomedicinsk fysik och röntgenfysik.
    Soft x-ray zone plate fabrication at KTH, Stockholm2009Inngår i: Journal of Physics, Conference Series, ISSN 1742-6588, E-ISSN 1742-6596, Vol. 186Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    We present the status of our zone plate and test object fabrication processes along with the latest fabricated components. With our nickel process, zone plates with outermost zone width of 20 nm and zone height of 90 nm have been fabricated. A gold electroplating process has recently been introduced for the fabrication of test objects. The first result for gold gratings with 70 nm period and 135 nm height is shown.

  • 34.
    Hossenfelder, Sabine
    KTH, Centra, Nordic Institute for Theoretical Physics NORDITA.
    Testing superdeterministic conspiracy2014Inngår i: Journal of Physics, Conference Series, ISSN 1742-6588, E-ISSN 1742-6596, Vol. 504, nr 1, s. 012018-Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Tests of Bell's theorem rule out local hidden variables theories. But any theorem is only as good as the assumptions that go into it, and one of these assumptions is that the experimenter can freely choose the detector settings. Without this assumption, one enters the realm of superdeterministic hidden variables theories and can no longer use Bell's theorem as a criterion. One can like or not like such superdeterministic hidden variables theories and their inevitable nonlocality, the real question is how one can test them. Here, we propose a possible experiment that could reveal superdeterminism.

  • 35.
    Hyvärinen, Ann
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Mekanik, Strömningsfysik. KTH, Skolan för teknikvetenskap (SCI), Centra, Linné Flow Center, FLOW.
    Segalini, Antonio
    KTH, Skolan för teknikvetenskap (SCI), Mekanik, Strömningsfysik. KTH, Skolan för teknikvetenskap (SCI), Centra, Linné Flow Center, FLOW.
    Qualitative analysis of wind-turbine wakes over hilly terrain2017Inngår i: Journal of Physics, Conference Series, ISSN 1742-6588, E-ISSN 1742-6596, Vol. 854, nr 1, artikkel-id 012023Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    In this work, wind-turbine wakes are studied over flat and hilly terrains. Measurements made by using stereoscopic PIV are compared to data obtained from numerical simulations using RANS equations and an actuator-disc method. The numerical and experimental data show similar qualitative trends, indicating that the wind-turbine wake is perturbed by the presence of the hills. Additionally, a faster flow recovery at hub height is seen with the hilly terrain, indicating that the hills presence is beneficial for downstream turbines exposed to wake-interaction effects. The Jensen wake model is implemented over the hilly terrain and it is shown that this model cannot accurately capture the wake modulations induced by the hills. However, by superimposing a wind-turbine wake simulated over flat terrain on the hilly-terrain flow field, it is illustrated that the commonly-used wake-superposition technique can yield reasonable results if the used wake model has sufficient accuracy.

  • 36.
    Häggström, Lennart
    et al.
    Uppsala Universitet.
    Soroka, Inna
    Uppsala Universitet.
    Kamali, Saeed.
    Uppsala Universitet.
    Thickness dependent crystallographic transition in Fe/Ni multilayers2010Inngår i: Journal of Physics, Conference Series, ISSN 1742-6588, E-ISSN 1742-6596, Vol. 217, s. 012112-Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The crystallog. transition between bcc- and fcc-structures has been studied in Fe/Ni multilayers with Moessbauer spectroscopy and X-ray diffraction. Layered structures have been confirmed and the structures depends both on individual layer thickness and the ratio of the constituents. Two sets of samples are made: the Fe layer thickness kept const. to 12 monolayer (ML) and 24ML, while the Ni layer thicknesses varied from 3 to 12ML. When the Ni layer is thin, the Fe/Ni multilayers have the bcc phase. When the thickness of Ni layer reaches 6ML and larger, a gradual transition to the fcc phase occurs. Moessbauer spectroscopy studies confirm the existence of a magnetic Fe bcc phase with in-plane magnetization in all samples, two magnetic fcc phases with fields of 28 T and 10 T and small amts. of nonmagnetic fcc phases in the thicker films. The obsd. behavior can be attributed to the existence of two types of interfaces which are not necessary overlapping each other: An elemental interface between Fe and Ni and a structural interface between fcc and bcc phases. [on SciFinder(R)]

  • 37. Innocenti, M. E.
    et al.
    Tronci, C.
    Markidis, Stefano
    KTH, Skolan för datavetenskap och kommunikation (CSC), Beräkningsvetenskap och beräkningsteknik (CST).
    Lapenta, G.
    Grid coupling mechanism in the semi-implicit adaptive Multi-Level Multi-Domain method2016Inngår i: Journal of Physics, Conference Series, ISSN 1742-6588, E-ISSN 1742-6596, Vol. 719, nr 1, artikkel-id 12019Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The Multi-Level Multi-Domain (MLMD) method is a semi-implicit adaptive method for Particle-In-Cell plasma simulations. It has been demonstrated in the past in simulations of Maxwellian plasmas, electrostatic and electromagnetic instabilities, plasma expansion in vacuum, magnetic reconnection [1, 2, 3]. In multiple occasions, it has been commented on the coupling between the coarse and the refined grid solutions. The coupling mechanism itself, however, has never been explored in depth. Here, we investigate the theoretical bases of grid coupling in the MLMD system. We obtain an evolution law for the electric field solution in the overlap area of the MLMD system which highlights a dependance on the densities and currents from both the coarse and the refined grid, rather than from the coarse grid alone: grid coupling is obtained via densities and currents.

  • 38. Itälä, E.
    et al.
    Kooser, K.
    Hägerth, T.
    Rachlew, Elisabeth
    KTH, Skolan för teknikvetenskap (SCI), Fysik, Atom- och molekylfysik.
    Huels, M. A.
    Kukk, E.
    Photofragmentation of a DNA nucleoside thymidine; Valence-vs. core ionization2012Inngår i: Journal of Physics, Conference Series, ISSN 1742-6588, E-ISSN 1742-6596, Vol. 388, nr PART 2, s. 022078-Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The photofragmentation of free thymidine molecule has been studied using combined electron- and ion spectroscopy. The results show that valence- and core ionization processes produce very different fragmentation patterns and that regardless of the photon energy, the photoionization leads almost always to dissociation of the thymidine molecule.

  • 39. Ivanov, A. V.
    et al.
    Bessarab, Pavel F.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Material- och nanofysik.
    Uzdin, V. M.
    Jónsson, H.
    Tip-surface interaction and rate of magnetic transitions2016Inngår i: Journal of Physics, Conference Series, ISSN 1742-6588, E-ISSN 1742-6596, Vol. 741, nr 1, artikkel-id 012184Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Calculations of the interaction between a magnetic tip of an atomic force microscope with a magnetic surface using the non-collinear extension of the Alexander-Anderson model are described. The mechanism and rate of thermally activated magnetic transitions in a cluster of atoms at the tip is investigated. The results are compared with experimental data and found to be in good agreement with measured lifetimes [R. Schmidt et. al., Phys. Rev. B 86, 174402 (2012).]. The results are also compared with previously reported density functional theory calculations.

  • 40. Johnsson, L.
    et al.
    Netzer, Gilbert
    KTH, Skolan för datavetenskap och kommunikation (CSC), Centra, Parallelldatorcentrum, PDC.
    The impact of Moore's Law and loss of Dennard scaling: Are DSP SoCs an energy efficient alternative to x86 SoCs?2016Inngår i: Journal of Physics, Conference Series, ISSN 1742-6588, E-ISSN 1742-6596, Vol. 762, nr 1, artikkel-id 012022Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Moore's law, the doubling of transistors per unit area for each CMOS technology generation, is expected to continue throughout the decade, while Dennard voltage scaling resulting in constant power per unit area stopped about a decade ago. The semiconductor industry's response to the loss of Dennard scaling and the consequent challenges in managing power distribution and dissipation has been leveled off clock rates, a die performance gain reduced from about a factor of 2.8 to 1.4 per technology generation, and multi-core processor dies with increased cache sizes. Increased caches sizes offers performance benefits for many applications as well as energy savings. Accessing data in cache is considerably more energy efficient than main memory accesses. Further, caches consume less power than a corresponding amount of functional logic. As feature sizes continue to be scaled down an increasing fraction of the die must be "underutilized" or "dark" due to power constraints. With power being a prime design constraint there is a concerted effort to find significantly more energy efficient chip architectures than dominant in servers today, with chips potentially incorporating several types of cores to cover a range of applications, or different functions in an application, as is already common for the mobile processor market. Digital Signal Processors (DSPs), largely targeting the embedded and mobile processor markets, typically have been designed for a power consumption of 10% or less of a typical x86 CPU, yet with much more than 10% of the floating-point capability of the same technology generation x86 CPUs. Thus, DSPs could potentially offer an energy efficient alternative to x86 CPUs. Here we report an assessment of the Texas Instruments TMS320C6678 DSP in regards to its energy efficiency for two common HPC benchmarks: STREAM (memory system benchmark) and HPL (CPU benchmark).

  • 41.
    Kalpakli, Athanasia
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Mekanik. KTH, Skolan för industriell teknik och management (ITM), Centra, Competence Center for Gas Exchange (CCGEx).
    Örlü, Ramis
    KTH, Skolan för teknikvetenskap (SCI), Mekanik. KTH, Skolan för teknikvetenskap (SCI), Centra, Linné Flow Center, FLOW. KTH, Skolan för industriell teknik och management (ITM), Centra, Competence Center for Gas Exchange (CCGEx).
    Tillmark, Nils
    KTH, Skolan för teknikvetenskap (SCI), Mekanik. KTH, Skolan för teknikvetenskap (SCI), Centra, Linné Flow Center, FLOW. KTH, Skolan för industriell teknik och management (ITM), Centra, Competence Center for Gas Exchange (CCGEx).
    Alfredsson, P. Henrik
    KTH, Skolan för teknikvetenskap (SCI), Mekanik. KTH, Skolan för teknikvetenskap (SCI), Centra, Linné Flow Center, FLOW. KTH, Skolan för industriell teknik och management (ITM), Centra, Competence Center for Gas Exchange (CCGEx).
    Pulsatile turbulent flow through pipe bends at high Dean and Womersley numbers2011Inngår i: Journal of Physics, Conference Series, ISSN 1742-6588, E-ISSN 1742-6596, Vol. 318, s. 092023-Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Turbulent pulsatile flows through pipe bends are prevalent in internal combustion engine components which consist of bent pipe sections and branching conduits. Nonetheless, most of the studies related to pulsatile flows in pipe bends focus on incompressible, low Womersley and low Dean number flows, primarily because they aim in modeling blood flow, while internal combustion engine related flows have mainly been addressed in terms of integral quantities and consist of single point measurements. The present study aims at bridging the gap between these two fields by means of time-resolved stereoscopic particle image velocimetry measurements in a pipe bend with conditions that are close to those encountered in exhaust manifolds. The time/phase-resolved three-dimensional cross-sectional flow-field 3 pipe diameters downstream the pipe bend is captured and the interplay between different secondary motions throughout a pulse cycle is discussed.

  • 42. Karim, A.
    et al.
    Hansson, G. V.
    Linnarsson, Margareta
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och tillämpad fysik, MAP.
    Influence of Er and O concentrations on the microstructure and luminescence of Si:Er/O LEDs2008Inngår i: Journal of Physics, Conference Series, ISSN 1742-6588, E-ISSN 1742-6596, Vol. 100, nr Part 4, s. 042010-Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Erbium(Er)/Oxygen(O) doped Silicon (Si) layers grown by molecular beam epitaxy (MBE), can be used for fabricating Si-based light emitting diodes. The electroluminescence intensity from these layers depends sensitively on the formation of specific types of Er/O precipitates inside the Si host. We have performed a detailed microstructure analysis of MBE-grown Er/O doped Si layers using electron microscopy and combined it with secondary ion mass spectrometry (SIMS) measurements as well as electroluminescence studies. Two types of microstructures are observed in different samples with specific Er and O concentrations and grown using Er and Si co-evaporation in O ambient. The first type of microstructure consists of planar precipitates along (311) planes mostly initiated at the onset of the growth of the Si: Er/O layer. The second characteristic type of microstructure observed contain round precipitates of Er/O. Using analytical microscopy techniques it was revealed that the round precipitates contain a higher ratio of Er to O as compared to the planar precipitates of the first type. The planar precipitates normally result in structures with high electroluminescence intensity while the structures with round precipitates have low intensity.

  • 43.
    Kawasaki, Hiroharu
    et al.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Ohshima, T.
    Yagyu, Y.
    Suda, Y.
    Khartsev, Sergiy
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Grishin, Alex
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    TiO2/TiN/TiO2 heat mirrors by laser ablation of single TiN target2008Inngår i: Journal of Physics, Conference Series, ISSN 1742-6588, E-ISSN 1742-6596, Vol. 100, nr 1, s. 012038-Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Titanium oxide (TiO2 ) and titanium nitride (TiN) multilayered films grown by pulsed laser deposition (PLD) technique have been tested as a heat mirror, which have a high transmittance in the visible region and a high reflectance in the infrared. Three layer TiO2 /TiN/TiO2 heat mirrors were grown on Corning glass substrates ablating single TiN target. Switching of TiO2 -to-TiN layers composition was achieved by changing gas atmosphere (oxygen-to-nitrogen). Grown TiO2 /TiN/TiO2 heat mirrors are highly transparent in visible (above 60% at 525nm), opaque in infrared (10% at 2600nm) and in the range from 400 nm to 2600 nm they possess almost the same properties as films prepared using two targets: TiO2 and TiN. XPS confirms similarity of chemical composition of multilayered TiO2 /TiN films prepared by single TiN and two TiO2 and TiN targets techniques. Furthermore, multifunctional self cleaning properties of TiO2 /TiN heat mirrors are expected through the precise control of the composition of the top TiO2 layer operating as a photocatalyst.

  • 44. Kazakov, Ye.O.
    et al.
    Fülöp, T.
    Pusztai, I.
    Johnson, Thomas
    KTH, Skolan för elektro- och systemteknik (EES), Fusionsplasmafysik.
    Effect of plasma shaping and resonance location on minority ion temperature anisotropy in tokamak plasmas heated with ICRH2012Inngår i: Journal of Physics, Conference Series, ISSN 1742-6588, E-ISSN 1742-6596, Vol. 401, nr 1, s. 012011-Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Poloidal asymmetries of the impurity distribution, which are observed in tokamaks, may influence the impurity cross-field transport. Low field side ion cyclotron resonance heating (ICRH) often results in an inboard accumulation of impurities, which may in turn lead to an outward convective impurity flux. The temperature anisotropy of the ICRH-heated minority ions is identified to be one of the main parameters governing the impurity asymmetry strength. In the present work we analyze the effect of plasma shaping and the ICRH resonance location on the minority temperature anisotropy by means of the TORIC-SSFPQL modelling. We find that ellipticity reduces the anisotropy level due to the wave defocussing and broader absorption regions for the elongated plasmas. The temperature anisotropy decrease in case of the resonance layers located closer to the edge is caused by the significant reduction in heating power densities due to geometrical reasons.

  • 45. Kimberg, Victor
    et al.
    Zhang, Song Bin
    Rohringer, Nina
    X-ray lasing in diatomic molecules2014Inngår i: Journal of Physics, Conference Series, ISSN 1742-6588, E-ISSN 1742-6596, Vol. 488, nr 1Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    We predict high-gain x-ray lasing in diatomic molecules by ultrafast core ionization of the C K- and O K-edges in CO and the N K-edge in N2 with an x-ray free-electron laser source. To estimate the spectral and temporal output of this molecular x-ray laser, we solve generalized Maxwell-Bloch equations, keeping track of the electronic and nuclear degrees of freedom. Despite the broad fluorescence bandwidth, the amplified x-ray emission shows a narrow spectrum. By controlling the molecular alignment and thereby the alignment of the transition dipole moment polarization and emission energy control of the x-ray laser radiation is achievable.

  • 46.
    Kleusberg, Elektra
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Mekanik, Stabilitet, Transition, Kontroll. KTH, Skolan för teknikvetenskap (SCI), Centra, Linné Flow Center, FLOW. KTH, Centra, SeRC - Swedish e-Science Research Centre.
    Mikkelsen, R. F.
    Schlatter, Philipp
    KTH, Skolan för teknikvetenskap (SCI), Mekanik. KTH, Skolan för teknikvetenskap (SCI), Centra, Linné Flow Center, FLOW. KTH, Centra, SeRC - Swedish e-Science Research Centre.
    Ivanell, Stefan
    KTH, Skolan för teknikvetenskap (SCI), Mekanik, Stabilitet, Transition, Kontroll. KTH, Skolan för teknikvetenskap (SCI), Centra, Linné Flow Center, FLOW. KTH, Centra, SeRC - Swedish e-Science Research Centre. Uppsala University, Sweden.
    Henningson, Dan S.
    KTH, Skolan för teknikvetenskap (SCI), Mekanik, Stabilitet, Transition, Kontroll. KTH, Skolan för teknikvetenskap (SCI), Centra, Linné Flow Center, FLOW. KTH, Centra, SeRC - Swedish e-Science Research Centre.
    High-Order Numerical Simulations of Wind Turbine Wakes2017Inngår i: Journal of Physics, Conference Series, ISSN 1742-6588, E-ISSN 1742-6596, Vol. 854, nr 1, artikkel-id 012025Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Previous attempts to describe the structure of wind turbine wakes and their mutual interaction were mostly limited to large-eddy and Reynolds-averaged Navier-Stokes simulations using finite-volume solvers. We employ the higher-order spectral-element code Nek5000 to study the influence of numerical aspects on the prediction of the wind turbine wake structure and the wake interaction between two turbines. The spectral-element method enables an accurate representation of the vortical structures, with lower numerical dissipation than the more commonly used finite-volume codes. The wind-turbine blades are modeled as body forces using the actuator-line method (ACL) in the incompressible Navier-Stokes equations. Both tower and nacelle are represented with appropriate body forces. An inflow boundary condition is used which emulates homogeneous isotropic turbulence of wind-tunnel flows. We validate the implementation with results from experimental campaigns undertaken at the Norwegian University of Science and Technology (NTNU Blind Tests), investigate parametric influences and compare computational aspects with existing numerical simulations. In general the results show good agreement between the experiments and the numerical simulations both for a single-turbine setup as well as a two-turbine setup where the turbines are offset in the spanwise direction. A shift in the wake center caused by the tower wake is detected similar to experiments. The additional velocity deficit caused by the tower agrees well with the experimental data. The wake is captured well by Nek5000 in comparison with experiments both for the single wind turbine and in the two-turbine setup. The blade loading however shows large discrepancies for the high-turbulence, two-turbine case. While the experiments predicted higher thrust for the downstream turbine than for the upstream turbine, the opposite case was observed in Nek5000.

  • 47.
    Kothe, Christian
    et al.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Fotonik och optik, Kvantelektronik och -optik, QEO.
    Sainz, Isabel
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Fotonik och optik, Kvantelektronik och -optik, QEO.
    Björk, Gunnar
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Fotonik och optik, Kvantelektronik och -optik, QEO.
    Detecting entanglement through correlations between local observables2007Inngår i: Journal of Physics, Conference Series, ISSN 1742-6588, E-ISSN 1742-6596, Vol. 84, s. 012010-Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    We propose a measure of two-qubit entanglement that is invariant under local unitary transformations, and which is based on local measurements covariances. It measures the Hilbert-Schmidt distance between the state and the product state obtained by multiplying the local density matrices. The measure has the benefit that the experimentalist need not have any a priori knowledge of the state to make the measurements. For pure states, the measure provides the state's concurrence directly, without resorting to state tomography. For statistically mixed states, the measure provides bounds for the concurrence. The two-qutrit case is also studied.

  • 48. Koči, L.
    et al.
    Ahuja, Rajeev
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Tillämpad materialfysik. Condensed Matter Theory Group, Physics Department, Uppsala University, Sweden.
    Belonoshko, Anatoly B.
    KTH, Skolan för teknikvetenskap (SCI), Teoretisk fysik, Kondenserade materiens teori.
    Ab initio and classical molecular dynamics calculations of the high-pressure melting of Ne2008Inngår i: Journal of Physics, Conference Series, ISSN 1742-6588, E-ISSN 1742-6596, Vol. 121Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Classical molecular dynamics (CMD) calculations are fast but are heavily dependent on the potential feasibility. On the other hand, first-principles (ab initio) molecular dynamics (AIMD) does not use any empirical knowledge, but can be extremely time consuming. As both techniques have been applied to study melting at extreme conditions, a comparison of the methods is motivated. Furthermore, when melting is studied with MD, the use of coexistent solid and liquid structures (two-phase) in the initial simulation configuration, instead of a only a solid structure (one-phase), can have a significant impact. In this work, comparisons have been made between CMD and AIMD methods applied to one- and two-phase systems for the melting of Ne at high pressure.

  • 49.
    Krüger, Peter
    et al.
    Physikalisches Institut, Universität Heidelberg, D-69120 Heidelberg, Germany .
    Wildermuth, Stephan
    Physikalisches Institut, Universität Heidelberg, D-69120 Heidelberg, Germany .
    Hofferberth, Sebastian
    Physikalisches Institut, Universität Heidelberg, D-69120 Heidelberg, Germany .
    Andersson, L Mauritz
    Physikalisches Institut, Universität Heidelberg, D-69120 Heidelberg, Germany .
    Groth, Sönke
    Physikalisches Institut, Universität Heidelberg, D-69120 Heidelberg, Germany .
    Bar-Joseph, Israel
    Institute for Condensed Matter Physics, The Weizmann Institute of Science, Rehovot 76100, Israel .
    Schmiedmayer, Jörg
    Physikalisches Institut, Universität Heidelberg, D-69120 Heidelberg, Germany .
    Cold atoms close to surfaces: measuring magnetic field roughness and disorder potentials2005Inngår i: Journal of Physics, Conference Series, ISSN 1742-6588, E-ISSN 1742-6596, Vol. 19, nr 1, s. 56-65Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Microscopic atom optical devices integrated on atom chips allow to precisely control and manipulate ultra-cold ( T < 1 µK) neutral atoms and Bose-Einstein condensates (BECs) close to surfaces. The relevant energy scale of a BEC is extremely small (down to < 10 −11 eV). Consequently, BECs can be utilized as a sensor for variations of the potential energy of the atoms close to the surface. Here we describe how to use trapped atoms as a measurement device and analyze the performance and flexibility of the field sensor. We demonstrate microscopic magnetic imaging with simultaneous high spatial resolution (3 µm) and high field sensitivity (4 nT). With one dimensional BECs, we probe the magnetic field variations close to the surface at distances down to a few microns. Measurements of the magnetic field of a 100 µm wide current carrying wire imply that the magnetic field variations stem from residual variations of the current flow direction, resulting from local properties of the wire. These disorder potentials found near lithographically fabricated wires are two orders of magnitude smaller than those measured close to electroplated conductors.

  • 50. Kukk, E.
    et al.
    Kooser, K.
    Itälä, E.
    Trinh Ha, D.
    Urpelainen, S.
    Rachlew, Elisabeth
    KTH, Skolan för teknikvetenskap (SCI), Fysik, Atom- och molekylfysik.
    Dissociation dynamics of doubly charged CO2 and CS2 molecules as studied by electron-ion coincidence spectroscopy and simulations2012Inngår i: Journal of Physics, Conference Series, ISSN 1742-6588, E-ISSN 1742-6596, Vol. 388, nr Part 2, s. 022084-Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Auger decay following C 1s core ionization leads to dissociating doubly ionized molecular states of CO2 and CS2. Detailed dynamics of these three- and two-body processes is investigated using electron-ion multicoincidence spectroscopy and Monte-Carlo simulations of various dissociation scenarios.

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