1,029 research outputs found

    Towards QoE-Driven Optimization of Multi-Dimensional Content Streaming

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    Whereas adaptive video streaming for 2D video is well established and frequently used in streaming services, adaptation for emerging higher-dimensional content, such as point clouds, is still a research issue. Moreover, how to optimize resource usage in streaming services that support multiple content types of different dimensions and levels of interactivity has so far not been sufficiently studied. Learning-based approaches aim to optimize the streaming experience according to user needs. They predict quality metrics and try to find system parameters maximizing them given the current network conditions. With this paper, we show how to approach content and network adaption driven by Quality of Experience (QoE) for multi-dimensional content. We describe components required to create a system adapting multiple streams of different content types simultaneously, identify research gaps and propose potential next steps

    Hochwasser und Sturzfluten an Flüssen in Deutschland

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    Flusshochwasser werden in lokale und plotzliche Sturzfluten und in Hochwasser an groseren Flussen unterschieden. Fur verschiedene Hochwasserindikatoren und Flusseinzugsgebiete ergeben sich erhebliche Unterschiede, wobei sowohl uberwiegend aus Regen als auch uberwiegend aus Schmelzwasser gespeiste Hochwasserereignisse betrachtet werden. Besondere Aufmerksamkeit finden Hochwasserereignisse an Rhein, Elbe, Weser und Ems sowie die Entwicklung von Sturzfluten infolge von Extremniederschlagen kurzer Dauer, wobei die Beobachtungen und Trends zu Modellierungsergebnissen in Beziehung gesetzt werden. Auch die Notwendigkeit von Anpassungsmasnahmen aufgrund uberwiegend positiver Trends wird diskutiert

    Mobility in a Globalised World

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    The term mobility has different meanings in the following academic disciplines. In economics, mobility is the ability of an individual or a group to improve their economic status in relation to income and wealth within their lifetime or between generations. In information systems and computer science, mobility is used for the concept of mobile computing, in which a computer is transported by a person during normal use. Logistics creates, by the design of logistics networks, the infrastructure for the mobility of people and goods. Electric mobility is one of today’s solutions from engineering perspective to reduce the need of energy resources and environmental impact. Moreover, for urban planning, mobility is the crunch question about how to optimize the different needs for mobility and how to link different transportation systems. The conference “Mobility in a Globalised World” took place in Iserlohn, Germany, on September 14th – 15th, 2011. The aim of this conference was to provide an interdisciplinary forum for the exchange of ideas among practitioners, researchers, and government officials regarding the different modes of mobility in a globalised world, focusing on both domestic and international issues. The proceedings at hand document the results of the presentations and ensuing discussions at the conference

    Evaluation der Berufseinstiegsbegleitung nach § 421s SGB III: Zwischenbericht 2011

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    Die Anforderungen an Schülerinnen und Schüler zwei Jahre vor ihrem Schulabschluss sind hoch. Schulisch sind sie mit vielen Prüfungen gefordert. Daneben müssen sie Bewerbungen für Ausbildungsplätze schreiben. Wenn es zum Bewerbungsgespräch kommt, stehen sie vor einer unbekannten Situation. Viele sind unsicher darüber, wie es nach der Schule weitergeht. Das Berufsleben - später meist selbstverständlich - ist die große Unbekannte. In dieser Phase hilft die Berufseinstiegsbegleitung nach dem Arbeitsförderungsrecht derzeit in einer modellhaften Erprobung an rund 1.000 Schulen denjenigen, die besondere Schwierigkeiten beim Schulabschluss und beim Übergang in die berufliche Zukunft haben. Bisher wurden dabei rund 37.000 Schülerinnen und Schülern durch die Bundesagentur für Arbeit gefördert. Die begleitende Wirkungsforschung (Evaluation) zeigt nun, dass sich bei den Teilnehmenden leichte Verbesserungen der Noten in Mathematik, Deutsch und Englisch zeigen. Von denjenigen, die die Schule „in Begleitung“ verlassen haben, haben 22,8 % eine betriebliche und 5,1 % eine schulische Berufsausbildung begonnen. Vergleichszahlen zu Übergängen von der Schule in den Beruf von jungen Menschen "ohne entsprechende Begleitung" liegen noch nicht vor. Nach der Schule verteilen sich die Schülerinnen und Schüler auf verschiedene Betriebe, Berufsschulen und andere Einrichtungen. Für die Tätigkeit der Berufseinstiegsbegleiterinnen und -begleiter stellt dies eine räumliche und eine organisatorische Herausforderung dar. Denn die Berufseinstiegsbegleitung endet in der Berufsausbildung normalerweise erst nach sechs Monaten. Damit soll die kritische Anfangsphase, in der die meisten Abbrüche stattfinden, stabilisiert werden. Die bisherigen positiven Erfahrungen mit der Berufseinstiegsbegleitung haben die Bundesregierung dazu veranlasst, im Entwurf eines Gesetzes zur Verbesserung der Eingliederungschancen am Arbeitsmarkt die Entfristung der Berufseinstiegsbegleitung vorzuschlagen. Der Deutsche Bundestag hat dieses Gesetz am 23. September 2011 verabschiedet

    Beam test performance of a prototype module with Short Strip ASICs for the CMS HL-LHC tracker upgrade

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    The Short Strip ASIC (SSA) is one of the four front-end chips designed for the upgrade of the CMS Outer Tracker for the High Luminosity LHC. Together with the Macro-Pixel ASIC (MPA) it will instrument modules containing a strip and a macro-pixel sensor stacked on top of each other. The SSA provides both full readout of the strip hit information when triggered, and, together with the MPA, correlated clusters called stubs from the two sensors for use by the CMS Level-1 (L1) trigger system. Results from the first prototype module consisting of a sensor and two SSA chips are presented. The prototype module has been characterized at the Fermilab Test Beam Facility using a 120 GeV proton beam

    Measurement of the top quark forward-backward production asymmetry and the anomalous chromoelectric and chromomagnetic moments in pp collisions at √s = 13 TeV

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    Abstract The parton-level top quark (t) forward-backward asymmetry and the anomalous chromoelectric (d̂ t) and chromomagnetic (μ̂ t) moments have been measured using LHC pp collisions at a center-of-mass energy of 13 TeV, collected in the CMS detector in a data sample corresponding to an integrated luminosity of 35.9 fb−1. The linearized variable AFB(1) is used to approximate the asymmetry. Candidate t t ¯ events decaying to a muon or electron and jets in final states with low and high Lorentz boosts are selected and reconstructed using a fit of the kinematic distributions of the decay products to those expected for t t ¯ final states. The values found for the parameters are AFB(1)=0.048−0.087+0.095(stat)−0.029+0.020(syst),μ̂t=−0.024−0.009+0.013(stat)−0.011+0.016(syst), and a limit is placed on the magnitude of | d̂ t| < 0.03 at 95% confidence level. [Figure not available: see fulltext.

    Measurement of b jet shapes in proton-proton collisions at root s=5.02 TeV

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    We present the first study of charged-hadron production associated with jets originating from b quarks in proton-proton collisions at a center-of-mass energy of 5.02 TeV. The data sample used in this study was collected with the CMS detector at the CERN LHC and corresponds to an integrated luminosity of 27.4 pb(-1). To characterize the jet substructure, the differential jet shapes, defined as the normalized transverse momentum distribution of charged hadrons as a function of angular distance from the jet axis, are measured for b jets. In addition to the jet shapes, the per-jet yields of charged particles associated with b jets are also quantified, again as a function of the angular distance with respect to the jet axis. Extracted jet shape and particle yield distributions for b jets are compared with results for inclusive jets, as well as with the predictions from the pythia and herwig++ event generators.Peer reviewe

    Measurement of the azimuthal anisotropy of Y(1S) and Y(2S) mesons in PbPb collisions at root s(NN)=5.02 TeV

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    The second-order Fourier coefficients (v(2)) characterizing the azimuthal distributions of Y(1S) and Y(2S) mesons produced in PbPb collisions at root s(NN) = 5.02 TeV are studied. The Y mesons are reconstructed in their dimuon decay channel, as measured by the CMS detector. The collected data set corresponds to an integrated luminosity of 1.7 nb(-1). The scalar product method is used to extract the v2 coefficients of the azimuthal distributions. Results are reported for the rapidity range vertical bar y vertical bar < 2.4, in the transverse momentum interval 0 < pT < 50 GeV/c, and in three centrality ranges of 10-30%, 30-50% and 50-90%. In contrast to the J/psi mesons, the measured v(2) values for the Y mesons are found to be consistent with zero. (C) 2021 The Author(s). Published by Elsevier B.V.Peer reviewe

    Search for new particles in events with energetic jets and large missing transverse momentum in proton-proton collisions at root s=13 TeV

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    A search is presented for new particles produced at the LHC in proton-proton collisions at root s = 13 TeV, using events with energetic jets and large missing transverse momentum. The analysis is based on a data sample corresponding to an integrated luminosity of 101 fb(-1), collected in 2017-2018 with the CMS detector. Machine learning techniques are used to define separate categories for events with narrow jets from initial-state radiation and events with large-radius jets consistent with a hadronic decay of a W or Z boson. A statistical combination is made with an earlier search based on a data sample of 36 fb(-1), collected in 2016. No significant excess of events is observed with respect to the standard model background expectation determined from control samples in data. The results are interpreted in terms of limits on the branching fraction of an invisible decay of the Higgs boson, as well as constraints on simplified models of dark matter, on first-generation scalar leptoquarks decaying to quarks and neutrinos, and on models with large extra dimensions. Several of the new limits, specifically for spin-1 dark matter mediators, pseudoscalar mediators, colored mediators, and leptoquarks, are the most restrictive to date.Peer reviewe

    Combined searches for the production of supersymmetric top quark partners in proton-proton collisions at root s=13 TeV

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    A combination of searches for top squark pair production using proton-proton collision data at a center-of-mass energy of 13 TeV at the CERN LHC, corresponding to an integrated luminosity of 137 fb(-1) collected by the CMS experiment, is presented. Signatures with at least 2 jets and large missing transverse momentum are categorized into events with 0, 1, or 2 leptons. New results for regions of parameter space where the kinematical properties of top squark pair production and top quark pair production are very similar are presented. Depending on themodel, the combined result excludes a top squarkmass up to 1325 GeV for amassless neutralino, and a neutralinomass up to 700 GeV for a top squarkmass of 1150 GeV. Top squarks with masses from 145 to 295 GeV, for neutralino masses from 0 to 100 GeV, with a mass difference between the top squark and the neutralino in a window of 30 GeV around the mass of the top quark, are excluded for the first time with CMS data. The results of theses searches are also interpreted in an alternative signal model of dark matter production via a spin-0 mediator in association with a top quark pair. Upper limits are set on the cross section for mediator particle masses of up to 420 GeV
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