791 research outputs found

    Theoretical aspects of high energy elastic nucleon scattering

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    The eikonal model must be denoted as strongly preferable for the analysis of elastic high-energy hadron collisions. The given approach allows to derive corresponding impact parameter profiles that characterize important physical features of nucleon collisions, e.g., the range of different forces. The contemporary phenomenological analysis of experimental data is, however, not able to determine these profiles unambiguously, i.e., it cannot give the answer whether the elastic hadron collisions are more central or more peripheral than the inelastic ones. However, in the collisions of mass objects (like protons) the peripheral behavior of elastic collisions should be preferred.Comment: 7 pages, 4 figure

    Contemporary models of elastic nucleon scattering and their predictions for LHC

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    The analyses of elastic collisions of charged nucleons have been based standardly on West and Yennie formula. However, this approach has been shown recently to be inadequate from experimental as well as theoretical points of view. The eikonal model seems to be more pertinent as it enables to determine physical characteristics in impact parameter space. The contemporary phenomenological models cannot give, of course, any definite answer as the elastic collisions may be interpreted differently, as central or peripheral processes. Nevertheless, the predictions for the planned LHC energy have been given on their basis and the possibility of exact determination of luminosity has been considered.Comment: 11 pages, 6 figure

    Reconstruction of elastic events

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    This note describes an elastic event reconstruction method developed for the TOTEM experiment. It is based on linear track parameterization and linear track fit. The suggested method has been implemented within simulation/reconstruction software framework, and results for the 1540 m and 90 m optics are given. The obtained resolution is compared to analytic estimates presented in the appendix

    Description and simulation of beam smearing effects

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    This note addresses angular smearing (i.e. beam divergence), energy smearing and vertex smearing effects. Their mathematical description is given also for the case with non-zero crossing angle. Finally, the influence of angular smearing (the most relevant effect for the TOTEM experiment) on particles scattered to small angles is presented in an explicit form, useful for further studies

    Carbon-Rich Silicon Oxycarbide (SiOC) and Silicon Oxycarbide/Element (SiOC/X, X= Si, Sn) Nano-Composites as New Anode Materials for Li-Ion Battery Application

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    Carbon-rich silicon oxycarbide (SiOC) and silicon oxycarbide/element nano-composites (SiOC/X, X=Si, Sn) are prepared via thermal conversion of polyorganosiloxanes and studied as potential anode material for Li-ion battery application. The obtained materials are characterized by various chemical, structural, electrochemical and electro-analytical methods. The chemical composition and microstructure of the samples is analyzed and correlated with their electrochemical properties and performance. For carbon-rich SiOC, the lithium ion storage process, including the transport and mobility of lithium ions within the material, is investigated. The electrochemical properties of carbon-rich SiOC strongly correlate with the ceramic microstructure and phase composition, which in turn correlate with the final temperature of pyrolysis. Both, an increasing organization of free carbon within the microstructure and the gradual degradation of the amorphous Si-O-C network lead to reduced capacities and changing voltage profiles. According to electro-analytical studies by PITT, GITT and EIS, the diffusion coefficient of Li-ions within SiOC prepared at 1100°C is in a similar order of magnitude as reported for disordered carbons, but faster than for graphite. In the case of SiOC/X (X=Si, Sn) nano-composites, an additional Li-alloy forming phase is embedded within the SiOC matrix. For the synthesis of SiOC/Sn, a new innovative single-source precursor approach is introduced, which enables the in-situ precipitation of metallic Sn phase upon the thermal conversion of tin-modified polysiloxanes. Due to this microstructural design, the Li-ion storage capacity of the composite is enhanced, compared to pure SiOC. In addition, the embedding of Si and Sn alloy forming phases within stabilizing SiOC matrices strongly increases their cycling stability upon continuous lithiation and delithiation

    Model-based estimation of in-car-communication feedback applied to speech zone detection

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    Modern cars provide versatile tools to enhance speech communication. While an in-car communication (ICC) system aims at enhancing communication between the passengers by playing back desired speech via loudspeakers in the car, these loudspeaker signals may disturb a speech enhancement system required for hands-free telephony and automatic speech recognition. In this paper, we focus on speech zone detection, i.e. detecting which passenger in the car is speaking, which is a crucial component of the speech enhancement system. We propose a model-based feedback estimation method to improve robustness of speech zone detection against ICC feedback. Specifically, since the zone detection system typically does not have access to the ICC loudspeaker signals, the proposed method estimates the feedback signal from the observed microphone signals based on a free-field propagation model between the loudspeakers and the microphones as well as the ICC gain. We propose an efficient recursive implementation in the short-time Fourier transform domain using convolutive transfer functions. A realistic simulation study indicates that the proposed method allows to increase the ICC gain by about 6dB while still achieving robust speech zone detection results.Comment: 5 pages, submitted to International Workshop on Acoustic Signal Enhancement (IWAENC), Bamberg, Germany, 202

    Green shipping: Marine engine pollution abatement using a combined catalyst/seawater scrubber system. 1. Effect of catalyst

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    A marine engine pollution abatement system was constructed and tested on a 1.5 MW auxiliary marine engine. The integrated system, designed to abate all of the currently legislated emissions from marine engines, consisted of a monolithic Pt/Al2O3 oxidation catalyst and a seawater scrubber, both of suitable dimensions for the engine size. The test results obtained showed the general validity of the approach adopted, as significant abatement of emissions was achieved. However, under the conditions used, the system showed some limitations with regard to the sulphur content of the fuel. On the basis of the results obtained, the system can be used with fuel sulphur content of up to 0.4%,while problems were encountered when a fuel with a sulphur content of 2.0% was used. Whereas the catalytic section operated satisfactorily, fine tuning of the scrubber operating conditions is necessary to improve abatement of NOx and increase the range of fuel sulphur which can be used with the system

    EEG recording latency in critically ill patients: Impact on outcome. An analysis of a randomized controlled trial (CERTA).

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    OBJECTIVE To assess, in adults with acute consciousness impairment, the impact of latency between hospital admission and EEG recording start, and their outcome. METHODS We reviewed data of the CERTA trial (NCT03129438) and explored correlations between EEG recording latency and mortality, Cerebral Performance Categories (CPC), and modified Rankin Scale (mRS) at 6 months, considering other variables, using uni- and multivariable analyses. RESULTS In univariable analysis of 364 adults, median latency between admission and EEG recordings was comparable between surviving (61.1 h; IQR: 24.3-137.7) and deceased patients (57.5 h; IQR: 22.3-141.1); p = 0.727. This did not change after adjusting for potential confounders, such as lower Glasgow Coma Score on enrolment (p < 0.001) and seizure or status epilepticus detection (p < 0.001). There was neither any correlation between EEG latency and mRS (rho 0.087, p 0.236), nor with CPC (rho = 0.027, p = 0.603). CONCLUSION This analysis shows no correlation between delays of EEG recordings and mortality or functional outcomes at 6 months in critically ill adults. SIGNIFICANCE These findings might suggest that in critically ill adults mortality correlates with underlying brain injury rather than EEG delay