| 1. |
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| 2. |
- Aamodt, K., et al.
(författare)
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First proton-proton collisions at the LHC as observed with the ALICE detector: measurement of the charged-particle pseudorapidity density at root s=900 GeV
- 2010
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Ingår i: European Physical Journal C. Particles and Fields. - : Springer Science and Business Media LLC. - 1434-6044. ; 65:1-2, s. 111-125
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Tidskriftsartikel (refereegranskat)abstract
- On 23rd November 2009, during the early commissioning of the CERN Large Hadron Collider (LHC), two counter-rotating proton bunches were circulated for the first time concurrently in the machine, at the LHC injection energy of 450 GeV per beam. Although the proton intensity was very low, with only one pilot bunch per beam, and no systematic attempt was made to optimize the collision optics, all LHC experiments reported a number of collision candidates. In the ALICE experiment, the collision region was centred very well in both the longitudinal and transverse directions and 284 events were recorded in coincidence with the two passing proton bunches. The events were immediately reconstructed and analyzed both online and offline. We have used these events to measure the pseudorapidity density of charged primary particles in the central region. In the range vertical bar eta vertical bar < 0.5, we obtain dN(ch)/d eta = 3.10 +/- 0.13(stat.) +/- 0.22(syst.) for all inelastic interactions, and dN(ch)/d eta = 3.51 +/- 0.15(stat.) +/- 0.25(syst.) for nonsingle diffractive interactions. These results are consistent with previous measurements in proton-antiproton interactions at the same centre-of-mass energy at the CERN Sp<(p)over bar>S collider. They also illustrate the excellent functioning and rapid progress of the LHC accelerator, and of both the hardware and software of the ALICE experiment, in this early start-up phase.
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| 3. |
- Aamodt, K., et al.
(författare)
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Alignment of the ALICE Inner Tracking System with cosmic-ray tracks
- 2010
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Ingår i: Journal of Instrumentation. - 1748-0221. ; 5
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Konferensbidrag (refereegranskat)abstract
- ALICE (A Large Ion Collider Experiment) is the LHC (Large Hadron Collider) experiment devoted to investigating the strongly interacting matter created in nucleus-nucleus collisions at the LHC energies. The ALICE ITS, Inner Tracking System, consists of six cylindrical layers of silicon detectors with three different technologies; in the outward direction: two layers of pixel detectors, two layers each of drift, and strip detectors. The number of parameters to be determined in the spatial alignment of the 2198 sensor modules of the ITS is about 13,000. The target alignment precision is well below 10 mu m in some cases (pixels). The sources of alignment information include survey measurements, and the reconstructed tracks from cosmic rays and from proton-proton collisions. The main track-based alignment method uses the Millepede global approach. An iterative local method was developed and used as well. We present the results obtained for the ITS alignment using about 10(5) charged tracks from cosmic rays that have been collected during summer 2008, with the ALICE solenoidal magnet switched off.
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| 4. |
- Aamodt, K., et al.
(författare)
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Charged-particle multiplicity measurement in proton-proton collisions at root s=0.9 and 2.36 TeV with ALICE at LHC
- 2010
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Ingår i: European Physical Journal C. Particles and Fields. - : Springer Science and Business Media LLC. - 1434-6044. ; 68:1-2, s. 89-108
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Tidskriftsartikel (refereegranskat)abstract
- Charged-particle production was studied in proton-proton collisions collected at the LHC with the ALICE detector at centre-of-mass energies 0.9 TeV and 2.36 TeV in the pseudorapidity range vertical bar eta vertical bar < 1.4. In the central region (vertical bar eta vertical bar < 0.5), at 0.9 TeV, we measure charged-particle pseudo-rapidity density dN(ch)/d eta = 3.02 +/- 0.01(stat.)(-0.05)(+0.08)(syst.) for inelastic interactions, and dN(ch)/d eta = 3.58 +/- 0.01 (stat.)(-0.12)(+0.12)(syst.) for non-single-diffractive interactions. At 2.36 TeV, we find dN(ch)/d eta = 3.77 +/- 0.01(stat.)(-0.12)(+0.25)(syst.) for inelastic, and dN(ch)/d eta = 4.43 +/- 0.01(stat.)(-0.12)(+0.17)(syst.) for non-single-diffractive collisions. The relative increase in charged-particle multiplicity from the lower to higher energy is 24.7% +/- 0.5%(stat.)(-2.8)(+5.7)%(syst.) for inelastic and 23.7% +/- 0.5%(stat.)(-1.1)(+4.6)%(syst.) for non-single-diffractive interactions. This increase is consistent with that reported by the CMS collaboration for non-single-diffractive events and larger than that found by a number of commonly used models. The multiplicity distribution was measured in different pseudorapidity intervals and studied in terms of KNO variables at both energies. The results are compared to proton-antiproton data and to model predictions.
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| 5. |
- Aamodt, K., et al.
(författare)
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Midrapidity Antiproton-to-Proton Ratio in pp Collisons root s=0.9 and 7 TeV Measured by the ALICE Experiment
- 2010
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Ingår i: Physical Review Letters. - 1079-7114. ; 105:7
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Tidskriftsartikel (refereegranskat)abstract
- The ratio of the yields of antiprotons to protons in pp collisions has been measured by the ALICE experiment at root s = 0.9 and 7 TeV during the initial running periods of the Large Hadron Collider. The measurement covers the transverse momentum interval 0.45 < p(t) < 1.05 GeV/c and rapidity vertical bar y vertical bar < 0.5. The ratio is measured to be R-vertical bar y vertical bar<0.5 = 0.957 +/- 0.006(stat) +/- 0.0014(syst) at 0.9 Tev and R-vertical bar y vertical bar<0.5 = 0.991 +/- 0.005 +/- 0.014(syst) at 7 TeV and it is independent of both rapidity and transverse momentum. The results are consistent with the conventional model of baryon-number transport and set stringent limits on any additional contributions to baryon-number transfer over very large rapidity intervals in pp collisions.
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| 6. |
- Aamodt, K., et al.
(författare)
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Production of pions, kaons and protons in pp collisions at root s=900 GeV with ALICE at the LHC
- 2011
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Ingår i: European Physical Journal C. Particles and Fields. - : Springer Science and Business Media LLC. - 1434-6044. ; 71:6
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Tidskriftsartikel (refereegranskat)abstract
- The production of pi(+), pi(-), K+, K-, p, and (p) over bar at mid-rapidity has been measured in proton-proton collisions at root s = 900 GeV with the ALICE detector. Particle identification is performed using the specific energy loss in the inner tracking silicon detector and the time projection chamber. In addition, time-of-flight information is used to identify hadrons at higher momenta. Finally, the distinctive kink topology of the weak decay of charged kaons is used for an alternative measurement of the kaon transverse momentum (p(t)) spectra. Since these various particle identification tools give the best separation capabilities over different momentum ranges, the results are combined to extract spectra from p(t) = 100 MeV/c to 2.5 GeV/c. The measured spectra are further compared with QCD-inspired models which yield a poor description. The total yields and the mean pt are compared with previous measurements, and the trends as a function of collision energy are discussed.
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| 7. |
- Aamodt, K., et al.
(författare)
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Two-pion Bose-Einstein correlations in pp collisions at root s=900 GeV
- 2010
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Ingår i: Physical Review D (Particles, Fields, Gravitation and Cosmology). - 1550-2368. ; 82:5
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Tidskriftsartikel (refereegranskat)abstract
- We report on the measurement of two-pion correlation functions from pp collisions at root s = 900 GeV performed by the ALICE experiment at the Large Hadron Collider. Our analysis shows an increase of the Hanbury Brown-Twiss radius with increasing event multiplicity, in line with other measurements done in particle- and nuclear collisions. Conversely, the strong decrease of the radius with increasing transverse momentum, as observed at the Relativistic Heavy Ion Collider and at Tevatron, is not manifest in our data.
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| 8. |
- Aamodt, K., et al.
(författare)
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Charged-particle multiplicity measurement in proton-proton collisions at root s=7 TeV with ALICE at LHC
- 2010
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Ingår i: European Physical Journal C. Particles and Fields. - : Springer Science and Business Media LLC. - 1434-6044. ; 68:3-4, s. 345-354
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Tidskriftsartikel (refereegranskat)abstract
- The pseudorapidity density and multiplicity distribution of charged particles produced in proton-proton collisions at the LHC, at a centre-of-mass energy root s = 7 TeV, were measured in the central pseudorapidity region vertical bar eta vertical bar < 1. Comparisons are made with previous measurements at root s = 0.9 TeV and 2.36 TeV. At root s = 7 TeV, for events with at least one charged particle in |eta vertical bar| < 1, we obtain dN(ch)/d eta = 6.01 +/- 0.01(stat.)(-0.12)(+0.20) (syst.). This corresponds to an increase of 57.6%+/-0.4%(stat.)(-1.8%)(+3.6) (syst.) relative to collisions at 0.9 TeV, significantly higher than calculations from commonly used models. The multiplicity distribution at 7 TeV is described fairly well by the negative binomial distribution.
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| 9. |
- Aamodt, K., et al.
(författare)
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The ALICE experiment at the CERN LHC
- 2008
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Ingår i: Journal of Instrumentation. - 1748-0221. ; 3:S08002
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Forskningsöversikt (refereegranskat)abstract
- ALICE (A Large Ion Collider Experiment) is a general-purpose, heavy-ion detector at the CERN LHC which focuses on QCD, the strong-interaction sector of the Standard Model. It is designed to address the physics of strongly interacting matter and the quark-gluon plasma at extreme values of energy density and temperature in nucleus-nucleus collisions. Besides running with Pb ions, the physics programme includes collisions with lighter ions, lower energy running and dedicated proton-nucleus runs. ALICE will also take data with proton beams at the top LHC energy to collect reference data for the heavy-ion programme and to address several QCD topics for which ALICE is complementary to the other LHC detectors. The ALICE detector has been built by a collaboration including currently over 1000 physicists and engineers from 105 Institutes in 30 countries, Its overall dimensions are 16 x 16 x 26 m(3) with a total weight of approximately 10 000 t. The experiment consists of 18 different detector systems each with its own specific technology choice and design constraints, driven both by the physics requirements and the experimental conditions expected at LHC. The most stringent design constraint is to cope with the extreme particle multiplicity anticipated in central Pb-Pb collisions. The different subsystems were optimized to provide high-momentum resolution as well as excellent Particle Identification (PID) over a broad range in momentum, up to the highest multiplicities predicted for LHC. This will allow for comprehensive studies of hadrons, electrons, muons, and photons produced in the collision of heavy nuclei. Most detector systems are scheduled to be installed and ready for data taking by mid-2008 when the LHC is scheduled to start operation, with the exception of parts of the Photon Spectrometer (PHOS), Transition Radiation Detector (TRD) and Electro Magnetic Calorimeter (EMCal). These detectors will be completed for the high-luminosity ion run expected in 2010. This paper describes in detail the detector components as installed for the first data taking in the summer of 2008.
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| 10. |
- Aamodt, K., et al.
(författare)
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Transverse momentum spectra of charged particles in proton-proton collisions at root s=900 GeV with ALICE at the LHC
- 2010
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Ingår i: Physics Letters. Section B: Nuclear, Elementary Particle and High-Energy Physics. - : Elsevier BV. - 0370-2693. ; 693:2, s. 53-68
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Tidskriftsartikel (refereegranskat)abstract
- The inclusive charged particle transverse momentum distribution is measured in proton-proton collisions at root s = 900 GeV at the LHC using the ALICE detector. The measurement is performed in the central pseudorapidity region (vertical bar eta vertical bar < 0.8) over the transverse momentum range 0.15 < p(T) < 10 GeV/c. The correlation between transverse momentum and particle multiplicity is also studied. Results are presented for inelastic (INEL) and non-single-diffractive (NSD) events. The average transverse momentum for vertical bar eta vertical bar < 0.8 is < p(T)>(INEL) = 0.483 +/- 0.001 (stat.) +/- 0.007 (syst.) GeV/c and < p(T)>(NSD) = 0.489 +/- 0.001 (stat.) +/- 0.007 (syst.) GeV/c, respectively. The data exhibit a slightly larger < p(T)> than measurements in wider pseudorapidity intervals. The results are compared to simulations with the Monte Carlo event generators PYTHIA and PHOJET. (C) 2010 Published by Elsevier B.V.
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| 11. |
- Prusti, T., et al.
(författare)
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The Gaia mission
- 2016
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Ingår i: Astronomy and Astrophysics. - : EDP Sciences. - 0004-6361 .- 1432-0746. ; 595
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Tidskriftsartikel (refereegranskat)abstract
- Gaia is a cornerstone mission in the science programme of the European Space Agency (ESA). The spacecraft construction was approved in 2006, following a study in which the original interferometric concept was changed to a direct-imaging approach. Both the spacecraft and the payload were built by European industry. The involvement of the scientific community focusses on data processing for which the international Gaia Data Processing and Analysis Consortium (DPAC) was selected in 2007. Gaia was launched on 19 December 2013 and arrived at its operating point, the second Lagrange point of the Sun-Earth-Moon system, a few weeks later. The commissioning of the spacecraft and payload was completed on 19 July 2014. The nominal five-year mission started with four weeks of special, ecliptic-pole scanning and subsequently transferred into full-sky scanning mode. We recall the scientific goals of Gaia and give a description of the as-built spacecraft that is currently (mid-2016) being operated to achieve these goals. We pay special attention to the payload module, the performance of which is closely related to the scientific performance of the mission. We provide a summary of the commissioning activities and findings, followed by a description of the routine operational mode. We summarise scientific performance estimates on the basis of in-orbit operations. Several intermediate Gaia data releases are planned and the data can be retrieved from the Gaia Archive, which is available through the Gaia home page.
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| 12. |
- Brown, A. G. A., et al.
(författare)
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Gaia Data Release 1 Summary of the astrometric, photometric, and survey properties
- 2016
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Ingår i: Astronomy and Astrophysics. - : EDP Sciences. - 0004-6361 .- 1432-0746. ; 595
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Tidskriftsartikel (refereegranskat)abstract
- Context. At about 1000 days after the launch of Gaia we present the first Gaia data release, Gaia DR1, consisting of astrometry and photometry for over 1 billion sources brighter than magnitude 20.7. Aims. A summary of Gaia DR1 is presented along with illustrations of the scientific quality of the data, followed by a discussion of the limitations due to the preliminary nature of this release. Methods. The raw data collected by Gaia during the first 14 months of the mission have been processed by the Gaia Data Processing and Analysis Consortium (DPAC) and turned into an astrometric and photometric catalogue. Results. Gaia DR1 consists of three components: a primary astrometric data set which contains the positions, parallaxes, and mean proper motions for about 2 million of the brightest stars in common with the HIPPARCOS and Tycho-2 catalogues - a realisation of the Tycho-Gaia Astrometric Solution (TGAS) - and a secondary astrometric data set containing the positions for an additional 1.1 billion sources. The second component is the photometric data set, consisting of mean G-band magnitudes for all sources. The G-band light curves and the characteristics of similar to 3000 Cepheid and RR Lyrae stars, observed at high cadence around the south ecliptic pole, form the third component. For the primary astrometric data set the typical uncertainty is about 0.3 mas for the positions and parallaxes, and about 1 mas yr(-1) for the proper motions. A systematic component of similar to 0.3 mas should be added to the parallax uncertainties. For the subset of similar to 94 000 HIPPARCOS stars in the primary data set, the proper motions are much more precise at about 0.06 mas yr(-1). For the secondary astrometric data set, the typical uncertainty of the positions is similar to 10 mas. The median uncertainties on the mean G-band magnitudes range from the mmag level to similar to 0.03 mag over the magnitude range 5 to 20.7. Conclusions. Gaia DR1 is an important milestone ahead of the next Gaia data release, which will feature five-parameter astrometry for all sources. Extensive validation shows that Gaia DR1 represents a major advance in the mapping of the heavens and the availability of basic stellar data that underpin observational astrophysics. Nevertheless, the very preliminary nature of this first Gaia data release does lead to a number of important limitations to the data quality which should be carefully considered before drawing conclusions from the data.
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| 13. |
- Clementini, G., et al.
(författare)
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Testing parallaxes with local Cepheids and RR Lyrae stars
- 2017
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Ingår i: Astronomy and Astrophysics. - : EDP Sciences. - 0004-6361 .- 1432-0746. ; 605
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Tidskriftsartikel (refereegranskat)abstract
- Context. Parallaxes for 331 classical Cepheids, 31 Type II Cepheids, and 364 RR Lyrae stars in common between Gaia and the HIPPARCOS and Tycho-2 catalogues are published in Gaia Data Release 1 (DR1) as part of the Tycho-Gaia Astrometric Solution (TGAS). Aims. In order to test these first parallax measurements of the primary standard candles of the cosmological distance ladder, which involve astrometry collected by Gaia during the initial 14 months of science operation, we compared them with literature estimates and derived new period-luminosity (PL), period-Wesenheit (PW) relations for classical and Type II Cepheids and infrared PL, PL-metallicity (PLZ), and optical luminosity-metallicity (MV-[Fe/H]) relations for the RR Lyrae stars, with zero points based on TGAS.Methods. Classical Cepheids were carefully selected in order to discard known or suspected binary systems. The final sample comprises 102 fundamental mode pulsators with periods ranging from 1.68 to 51.66 days (of which 33 with sigma(omega)/omega < 0 : 5). The Type II Cepheids include a total of 26 W Virginis and BL Herculis stars spanning the period range from 1.16 to 30.00 days (of which only 7 with sigma(omega)/omega 0 : 5). The RR Lyrae stars include 200 sources with pulsation period ranging from 0.27 to 0.80 days (of which 112 with sigma(omega)/omega < 0 : 5). The new relations were computed using multi- band (V; I; J; K-s) photometry and spectroscopic metal abundances available in the literature, and by applying three alternative approaches: (i) linear least-squares fitting of the absolute magnitudes inferred from direct transformation of the TGAS parallaxes; (ii) adopting astrometry-based luminosities; and (iii) using a Bayesian fitting approach. The last two methods work in parallax space where parallaxes are used directly, thus maintaining symmetrical errors and allowing negative parallaxes to be used. The TGAS-based PL; PW; PLZ, and MV [Fe/H] relations are discussed by comparing the distance to the Large Magellanic Cloud provided by different types of pulsating stars and alternative fitting methods.Results. Good agreement is found from direct comparison of the parallaxes of RR Lyrae stars for which both TGAS and HST measurements are available. Similarly, very good agreement is found between the TGAS values and the parallaxes inferred from the absolute magnitudes of Cepheids and RR Lyrae stars analysed with the Baade-Wesselink method. TGAS values also compare favourably with the parallaxes inferred by theoretical model fitting of the multi-band light curves for two of the three classical Cepheids and one RR Lyrae star, which were analysed with this technique in our samples. The K-band PL relations show the significant improvement of the TGAS parallaxes for Cepheids and RR Lyrae stars with respect to the HIPPARCOS measurements. This is particularly true for the RR Lyrae stars for which improvement in quality and statistics is impressive.Conclusions. TGAS parallaxes bring a significant added value to the previous HIPPARCOS estimates. The relations presented in this paper represent the first Gaia-calibrated relations and form a work-in-progress milestone report in the wait for Gaia-only parallaxes of which a first solution will become available with Gaia Data Release 2 (DR2) in 2018.
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| 14. |
- van Leeuwen, F., et al.
(författare)
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Gaia Data Release 1 : Open cluster astrometry: Performance, limitations, and future prospects
- 2017
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Ingår i: Astronomy and Astrophysics. - : EDP Sciences. - 0004-6361 .- 1432-0746. ; 601
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Tidskriftsartikel (refereegranskat)abstract
- Context. The first Gaia Data Release contains the Tycho-Gaia Astrometric Solution (TGAS). This is a subset of about 2 million stars for which, besides the position and photometry, the proper motion and parallax are calculated using Hipparcos and Tycho-2 positions in 1991.25 as prior information. Aims. We investigate the scientific potential and limitations of the TGAS component by means of the astrometric data for open clusters. Methods. Mean cluster parallax and proper motion values are derived taking into account the error correlations within the astrometric solutions for individual stars, an estimate of the internal velocity dispersion in the cluster, and, where relevant, the effects of the depth of the cluster along the line of sight. Internal consistency of the TGAS data is assessed. Results. Values given for standard uncertainties are still inaccurate and may lead to unrealistic unit-weight standard deviations of least squares solutions for cluster parameters. Reconstructed mean cluster parallax and proper motion values are generally in very good agreement with earlier Hipparcos-based determination, although the Gaia mean parallax for the Pleiades is a significant exception. We have no current explanation for that discrepancy. Most clusters are observed to extend to nearly 15 pc from the cluster centre, and it will be up to future Gaia releases to establish whether those potential cluster-member stars are still dynamically bound to the clusters. Conclusions. The Gaia DR1 provides the means to examine open clusters far beyond their more easily visible cores, and can provide membership assessments based on proper motions and parallaxes. A combined HR diagram shows the same features as observed before using the Hipparcos data, with clearly increased luminosities for older A and F dwarfs.
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| 15. |
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| 16. |
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| 17. |
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| 18. |
- Fodor, G, et al.
(författare)
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Design Aspects of Network Assisted Device-to-Device Communications
- 2012
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Ingår i: IEEE Communications Magazine. - : IEEE Press. - 0163-6804 .- 1558-1896. ; 50:3, s. 170-177
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Tidskriftsartikel (refereegranskat)abstract
- Device-to-device (D2D) communications underlaying a cellular infrastructure has been proposed as a means of taking advantage of the physical proximity of communicating devices, increasing resource utilization, and improving cellular coverage. Relative to the traditional cellular methods, there is a need to design new peer discovery methods, physical layer procedures, and radio resource management algorithms that help realize the potential advantages of D2D communications. In this article we use the 3GPP Long Term Evolution system as a baseline for D2D design, review some of the key design challenges, and propose solution approaches that allow cellular devices and D2D pairs to share spectrum resources and thereby increase the spectrum and energy efficiency of traditional cellular networks. Simulation results illustrate the viability of the proposed design.
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| 19. |
- G, Eneroth, et al.
(författare)
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Applying ATM/AAL2 as a switching technology in third-generation mobile access networks
- 1999
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Ingår i: IEEE Communications Magazine. - : IEEE Press. - 0163-6804 .- 1558-1896. ; 37:6, s. 112-122
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Tidskriftsartikel (refereegranskat)abstract
- In this article we focus on the transport and switching part of third-generation mobile access networks and outline some important aspects of applying ATM in these networks. In particular, we argue that in order for the mobile access network to support low-bit-rate delay-sensitive traffic consisting of short packets, the standardization of a new ATM adaptation layer, AAL2, and associated signaling protocol has been necessary. The AAL2 protocol has been designed to support low-bit-rate delay-sensitive services (typically compressed voice) where other adaptation layers fail to deliver the required QoS and maintain efficient resource utilization at the same time. Furthermore, in order to provide mobility and soft handover support in CDMA-based mobile networks such as UMTS or IMT-2000, there is also a strong demand for fast connection establishment and release. Therefore, when designing ATM-based cellular access networks some specific architectural and traffic management issues need to be addressed.
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| 20. |
- Sargeson, A. M., et al.
(författare)
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Names and symbols for the transfermium elements
- 1997
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Ingår i: Pure and Applied Chemistry. - : Walter de Gruyter GmbH. - 0033-4545 .- 1365-3075. ; 69:12, s. 2471-2473
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Tidskriftsartikel (refereegranskat)abstract
- The recommendations (ref. 1) of the Commission on Nomenclature of Inorganic Chemistry (CNIC) on the nomenclature of the transfermium elements (101-109, inclusive) were considered by the IUPAC Bureau at Guildford (UK) in September 1995. As a result of the various criticisms of the recommendations and theway that they had been processed, the Bureau decided to adopt the recommendations as provisional and to circulate them to national/regional nomenclature centres in the normal way, with notices to be published innational/regional chemistry journals and magazines, requesting submission of comments to CNIC. In particular, the National Adhering Organizations (NAOs) were invited to express their views concerning the extant proposals for the names of these elements and the principles and traditions used to derive them. The response from the general chemical community was small, and the bulk of the replies came from nuclear scientists.
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| 21. |
- Sargeson, A. M., et al.
(författare)
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Names and symbols of transfermium elements (IUPAC recommendations 1994)
- 1994
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Ingår i: Pure and Applied Chemistry. - : Walter de Gruyter GmbH. - 0033-4545 .- 1365-3075. ; 66:12, s. 2419-2421
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Tidskriftsartikel (refereegranskat)abstract
- The Transfermium Working Group (TWG) was set up in 1986 under the joint auspices of the International Union of Pure and Applied Chemistry (IUPAC) and the International Union of Pure and Applied Physics (IUPAP). Its conclusions, duly endorsed by IUPAC and IUPAP, were published in the following three reports:1. Criteria that must be satisfied for the discovery of a new chemical element to be recognized, Pure & Appl. Chem., 63, 879-886 (1991).2. Discovery of the transfermium elements: Introduction to the discovery profiles, Pure & Appl. Chem., 65, 1757-1763 (1993).3, Discovery of the transfermium elements: Discovery profiles of the transfermium elements, Pure & Appl. Chem., 65, 1764-1814 (1993).IUPAC went a stage further by inviting responses on reports 2 and 3 from the three major groups concerned, i.e., Lawrence Berkeley Laboratory, California; Joint Institute for Nuclear Research, Dubna; and Gesellschaft fur Schwerionenforschung , Darmstadt. These responses together with the TWG's reply to the responses were published unedited in Pure & Appl. Chem.,Vol. 65, (1993), pp. 1815-1824.
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| 22. |
- Bulakci, O., et al.
(författare)
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An Agile Resource Management Framework for 5G
- 2017
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Konferensbidrag (refereegranskat)abstract
- This paper presents the design foundations of an agile resource management (RM) framework for the fifth generation (5G) radio access network (RAN) by describing essential building blocks (BBs). Overall, the presented RM framework provides holistic RM solutions that consider and exploit the novel aspects of 5G systems, such as, diverse service requirements, co-existence of multiple air interface (AI) variants (AIVs) in the overall AI, dynamic radio topologies, and novel communication modes. The proposed framework encompasses the following key BBs: Advanced interference management techniques for dense and dynamic deployments; dynamic traffic steering mechanisms that aim to attain the optimum mapping of 5G services to any available resources when and where needed by considering the peculiarities of different AIVs; tight interworking between novel 5G AIVs and evolved legacy AIVs such as Longterm Evolution (LTE); sharing of a common RAN by multiple network slices; RAN moderation techniques to attain energy efficiency gains; and functional extensions in the device measurement context to enable all the above new functionalities. The BBs are analyzed from the perspectives of key findings and RAN design implications.
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| 23. |
- Carvalho, E. de, et al.
(författare)
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EU FP7 INFSO-ICT-317669 METIS, D3.1 Positioning of multi-node/multi-antenna technologies
- 2013
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- This document describes the research activity in multi-node/multi-antenna technologies within METIS and positions it with respect to the state-of-the-art in the academic literature and in the standardization bodies. Based on the state-of-the-art and as well as on the METIS objectives,we set the research objectives and we group the different activities (or technology components) into research clusters with similar research objectives. The technologycomponents and the research objectives have been set to achieve an ambidextrous purpose. On one side we aim at providing the METIS system with those technological components that are a natural but non-trivial evolution of 4G. On the other side, we aim at seeking for disruptivetechnologies that could radically change 5G with respect to 4G. Moreover, we mapped the different technology components to METIS’ other activities and to the overall goals of theproject.
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| 29. |
- Porra, L., et al.
(författare)
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Quantitative Imaging of Regional Aerosol Deposition, Lung Ventilation and Morphology by Synchrotron Radiation CT
- 2018
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Ingår i: Scientific Reports. - : NATURE PUBLISHING GROUP. - 2045-2322. ; 8
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Tidskriftsartikel (refereegranskat)abstract
- To understand the determinants of inhaled aerosol particle distribution and targeting in the lung, knowledge of regional deposition, lung morphology and regional ventilation, is crucial. No single imaging modality allows the acquisition of all such data together. Here we assessed the feasibility of dual-energy synchrotron radiation imaging to this end in anesthetized rabbits; both in normal lung (n = 6) and following methacholine (MCH)-induced bronchoconstriction (n = 6), a model of asthma. We used K-edge subtraction CT (KES) imaging to quantitatively map the regional deposition of iodine-containing aerosol particles. Morphological and regional ventilation images were obtained, followed by quantitative regional iodine deposition maps, after 5 and 10 minutes of aerosol administration. Iodine deposition was markedly inhomogeneous both in normal lung and after induced bronchoconstrition. Deposition was significantly reduced in the MCH group at both time points, with a strong dependency on inspiratory flow in both conditions (R-2 = 0.71; p < 0.0001). We demonstrate for the first time, the feasibility of KES CT for quantitative imaging of lung deposition of aerosol particles, regional ventilation and morphology. Since these are among the main factors determining lung aerosol deposition, we expect this imaging approach to bring new contributions to the understanding of lung aerosol delivery, targeting, and ultimately biological efficacy.
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| 30. |
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| 31. |
- A, Eriksson, et al.
(författare)
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A middlebox control plane framework for wireless and mobile IP networks
- 2004
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Ingår i: 2004 International Conference on Parallel Processing Workshops, 2004 (ICPP 2004 Workshops). - New York : IEEE conference proceedings. ; , s. 322-329
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Bokkapitel (övrigt vetenskapligt/konstnärligt)abstract
- In wireless and mobile IP networks there is a need to support a set of functions that are related to wireless QoS provisioning, resource optimizations, mobility and security management and operator policy enforcement. These requirements have lead to the frequent usage of so called middleboxes including header/payload compressors, performance enhancement proxies, tunnel endpoints, packet filters and redirectors, QoS schedulers and others. Unfortunately, the increasing usage of these types of devices often leads to undesirable artifacts called feature interactions. In this paper we propose a framework that aims to coordinate the operation of middleboxes such that feature interactions are avoided. The three main ideas are (1) the separation of the control plane from the distributed network nodes, (2) the usage of a middlebox function independent horizontal protocol that allows mobile hosts to communicate their desired service requests to the network and (3) the usage of a vertical protocol between the network control and user planes. We present two examples in which this framework helps eliminate the risk for feature interactions. We comment on the relationship between the end-to-end principle and this framework. Finally, we discuss how future middleboxes can fit into this framework.
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| 32. |
- AG, Valkó, et al.
(författare)
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Voice QoS in third-generation mobile systems
- 1999
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Ingår i: IEEE Journal on Selected Areas in Communications. - : Institute of Electrical and Electronics Engineers (IEEE). - 0733-8716 .- 1558-0008. ; 17:1, s. 109-123
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Tidskriftsartikel (refereegranskat)
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| 33. |
- AT, Andersen, et al.
(författare)
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A partially-blocking queueing system with CBR/VBR and ABR/UBR arrival streams
- 2002
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Ingår i: Telecommunications Systems. - : Baltzer Academic Publisher. - 1018-4864 .- 1572-9451. ; 19:1, s. 75-99
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Tidskriftsartikel (refereegranskat)abstract
- In this paper we consider an ATM transmission link., to which CBR or VBR and ABR or UBR calls arrive according to independent Poisson processes. CBR/VBR calls (characterized by their equivalent bandwidth) are blocked and leave the system if the available link capacity is less than required at the time of arrival. ABR/UBR calls, however, accept partial blocking, meaning that they may enter service even if the available capacity is less than the specified required peak bandwidth, but greater than the so called minimal accepted bandwidth. Partially blocked ABR/UBR calls instead experience longer service time, since smaller given bandwidth entails proportionally longer time spent in the system, as first suggested in [3] and analyzed in details herein. Throughout the life time of an ABR/UBR connection, its bandwidth consumption fluctuates in accordance with the current load on the link but always at the highest possible value up to their peak bandwidth (greedy sources). Additionally, if this minimal accepted bandwidth is unavailable at the time of arrival, ABR/UBR calls are allowed to wait in a finite queue. This system is modeled by a Continuous Time Markov Chain (CTMC) and the CBR/VBR and ABR/UBR blocking probabilities and the mean ABR/UBR waiting- and service times are derived.
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| 34. |
- Baroffio, L., et al.
(författare)
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GreenEyes : Networked energy-aware visual analysis
- 2015
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Ingår i: 2015 IEEE International Conference on Multimedia and Expo Workshops, ICMEW 2015. - : IEEE conference proceedings. - 9781479970797
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Konferensbidrag (refereegranskat)abstract
- The GreenEyes project aims at developing a comprehensive set of new methodologies, practical algorithms and protocols, to empower wireless sensor networks with vision capabilities. The key tenet of this research is that most visual analysis tasks can be carried out based on a succinct representation of the image, which entails both global and local features, while it disregards the underlying pixel-level representation. Specifically, GreenEyes will pursue the following goals: i) energy-constrained extraction of visual features; ii) rate-efficiency modelling and coding of visual feature; iii) networking streams of visual features. This will have a significant impact on several scenarios including, e.g., smart cities and environmental monitoring.
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| 35. |
- Belleschi, M, et al.
(författare)
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Performance analysis of a distributed resource allocation scheme for D2D communications
- 2011
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Ingår i: 2011 IEEE GLOBAL TELECOMMUNICATIONS CONFERENCE (GLOBECOM 2011): 54th Annual IEEE Global Telecommunications Conference (GLOBECOM). - New York : IEEE conference proceedings. ; , s. 358-362
-
Bokkapitel (refereegranskat)abstract
- Device-to-device (D2D) communications underlaying a cellular infrastructure has recently been proposed as a means of increasing the cellular capacity, improving the user throughput and extending the battery lifetime of user equipments by facilitating the reuse of spectrum resources between D2D and cellular links. In network assisted D2D communications, when two devices are in the proximity of each other, the network can not only help the devices to set the appropriate transmit power and schedule time and frequency resources but also to determine whether communication should take place via the direct D2D link (D2D mode) or via the cellular base station (cellular mode). In this paper we formulate the joint mode selection, scheduling and power control task as an optimization problem that we first solve assuming the availability of a central entity. We also propose a distributed suboptimal joint mode selection and resource allocation scheme that we benchmark with respect to the centralized optimal solution. We find that the distributed scheme performs close to the optimal scheme both in terms of resource efficiency and user fairness.
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| 36. |
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| 37. |
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| 38. |
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| 39. |
- Cinkler, T, et al.
(författare)
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Simulative analysis of end-to-end call-blocking probability evaluation techniques in multi-rate loss networks
- 1996
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Ingår i: Modelling and simulation 1996. - San Diego : Society of Computer Simulation (SCS). ; , s. 521-525
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Bokkapitel (övrigt vetenskapligt/konstnärligt)abstract
- For the: end-to-end call blocking probability computation in multi-rate loss networks the so called reduced load approximation under link independence assumption is often used, because it allows the derivation of analytical and numerical results. However, its accuracy and extendibility to multirouting or multicasting networks (like the B-ISDN) is seldom studied. This paper attempts to generalize this assumption and to assess the usefulness of this generalization by comparing simulation and approximation results on link, route and end-to-end blocking probability evaluation For thess kinds of networks.
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| 40. |
- D, Mariz, et al.
(författare)
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Simulative analysis of access selection algorithms for multi-access networks
- 2006
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Ingår i: 2006 International Symposium on a World of Wireless, Mobile and Multimedia Networks (WoWMoM'06). - New York : IEEE conference proceedings. ; , s. 219-227
-
Bokkapitel (övrigt vetenskapligt/konstnärligt)abstract
- It is expected that future wireless systems will consist of several distinct radio access technologies (including WCDMA/HSDPA, GSM/EDGE/GPRS, WLAN and others) forming a multi-access system that offers advanced voice and multimedia services. Previous works have shown that the combined capacity region of such systems depend on the service allocation policy that assigns user sessions to the available subsystems. The currently available service allocation policies typically operate off-line implying that the actual service mix is assumed to be known prior to the service allocation taking place. In this paper we consider the on-line problem according to which sessions arrive one after the other and no assumptions on the service mix can be made. We adopt four on-line bin-packing algorithms to the multi-access environment and study their performance by means of simulation in terms of the class-wise blocking probability and throughput. We find that the algorithm termed Less Voice provides the best performance in terms of the blocking probabilities and imposes the least slow down for elastic sessions
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| 41. |
- Elamain, Omaima Abubakr, et al.
(författare)
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Optically isotropic state in bent core nematic mixtures with rod like molecules induced by direct current electric field
- 2013
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Ingår i: Applied Physics Letters. - : AIP Publishing. - 0003-6951 .- 1077-3118. ; 103:16
-
Tidskriftsartikel (refereegranskat)abstract
- One of the most important characteristic of the liquid crystal displays is the contrast of the generated images. The dark state of the display is a prerequisite for a high image contrast. Optically isotropic state was observed in bent core nematic mixtures containing rod like molecules induced by low applied dc electric field. It is found that the switching properties of these nematic mixtures depend on the concentration of the rod like molecules. Comparatively high concentrations of rod like molecules in the mixtures resulted in an improvement of the contrast and switching properties of the bent core nematic mixtures, thus demonstrating their potential for display applications.
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| 42. |
- Fallgren, Mikael, et al.
(författare)
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An optimization approach to joint cell and power allocation in multicell networks
- 2011
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Ingår i: IEEE Int Conf Commun. - : IEEE. - 9781612849553 ; , s. 5963591-
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Konferensbidrag (refereegranskat)abstract
- Since the seminal paper by Knopp and Humblet that showed that the system throughput of a single cell system is maximized if only one terminal transmits at a time, there has been a large interest in opportunistic communications and its relation to various fairness measures. On the other hand, in multicell systems there is a need to allocate transmission power such that some overall utility function is maximized typically under fairness constraints. Furthermore, in multicell systems the degree of resource allocation freedom includes the serving cell selection that allows for load balancing and thereby the efficient use of radio resources. In this paper we formulate the joint serving cell selection (link selection) and power allocation problem as an optimization task whose purpose is to maximize either the minimum user throughput or the multicell sum throughput. Both the max-min and the max-throughput problems are non-polynomial hard and we therefore propose heuristic solution approaches. We present numerical results that give new and valuable insights into the trade off between fair and sum throughput optimal joint resource allocation strategies.
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| 43. |
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| 44. |
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| 45. |
- Fodor, G., et al.
(författare)
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An Overview of Device-to-Device Communications Technology Components in METIS
- 2016
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Ingår i: IEEE Access. - : Institute of Electrical and Electronics Engineers (IEEE). - 2169-3536 .- 2169-3536. ; 4, s. 3288-3299
-
Tidskriftsartikel (refereegranskat)abstract
- As the standardization of network-assisted device-to-device (D2D) communications by the Third Generation Partnership Project progresses, the research community has started to explore the technology potential of new advanced features that will largely impact the performance of 5G networks. For 5G, D2D is becoming an integrative term of emerging technologies that take an advantage of the proximity of communicating entities in licensed and unlicensed spectra. The European 5G research project Mobile and Wireless Communication Enablers for the 2020 Information Society (METIS) has identified advanced D2D as a key enabler for a variety of 5G services, including cellular coverage extension, social proximity, and communicating vehicles. In this paper, we review the METIS D2D technology components in three key areas of proximal communications-network-assisted multi-hop, full-duplex, and multi-antenna D2D communications-and argue that the advantages of properly combining cellular and ad hoc technologies help to meet the challenges of the information society beyond 2020.
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| 46. |
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| 47. |
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| 48. |
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| 49. |
- Fodor, G., et al.
(författare)
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Simulative analysis of a multi-cell admission control algorithm in WCDMA networks
- 2007
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Ingår i: 2007 IEEE International Conference on Communications. - : IEEE. - 1424403537 - 9781424403530 ; , s. 4797-4804
-
Konferensbidrag (refereegranskat)abstract
- It has for long been recognized that in multi-cell wide-band code division multiple access (WCDMA) networks the admission of a new session into the system can have undesirable impacts on the neighboring cells. Although admission control algorithms that take into account such multi-cell impacts have been studied in the past, little attention has been paid to multi-cell admission and rate control algorithms when traffic is elastic. In this work, we propose a model for multi-cell WCDMA networks to study the impact of admission and rate control algorithms on key performance measures such as the class-wise blocking and dropping probabilities, block error rates and the overall throughput. By means of simulation we compare the performance of multi-cell algorithms with that of a single cell algorithm. For voice traffic, we find that multi-cell algorithms improve the session drop and block error probabilities in both of the examined heterogenous (termed "Hotspot" and "Hotround") scenarios. When traffic is elastic, the multicell algorithms perform better in the examined homogeneous case.
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| 50. |
- G, Fodor, et al.
(författare)
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A low intercell interference variation scheduler for OFDMA networks
- 2008
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Ingår i: 2008 IEEE INTERNATIONAL CONFERENCE ON COMMUNICATIONS, PROCEEDINGS, VOLS 1-13. - New York : IEEE conference proceedings. ; , s. 3078-3084
-
Bokkapitel (övrigt vetenskapligt/konstnärligt)abstract
- In orthogonal frequency division multiple access networks, link adaptation (LA) selects the appropriate modulation and coding scheme for the upcoming transmission time interval. Since LA relies on measurements of the interference level and assumes that it remains similar during the next scheduling instance, the performance of LA depends on the variation (rather than simply the level) of intercell interference (ICI). In this paper we propose a minimum variance scheduler that allows for opportunistic scheduling - and thereby to take advantage of multi-user frequency diversity - but keeps the variation of intercell interference at a low level. We build on previously proposed collision models (detailed in own work and related other papers) and study the interplay between this scheduler and two intercell interference coordination (ICIC) methods that we call random and coordinated subcarrier allocation. We find that the proposed low variance scheduling scheme together with coordinated ICIC reduces ICI and its variance and is superior to other scheduling techniques in terms of the overall system throughput.
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