14,224 research outputs found

    "Discrepant hardenings" in cosmic ray spectra: a first estimate of the effects on secondary antiproton and diffuse gamma-ray yields

    Full text link
    Recent data from CREAM seem to confirm early suggestions that primary cosmic ray (CR) spectra at few TeV/nucleon are harder than in the 10-100 GeV range. Also, helium and heavier nuclei spectra appear systematically harder than the proton fluxes at corresponding energies. We note here that if the measurements reflect intrinsic features in the interstellar fluxes (as opposed to local effects) appreciable modifications are expected in the sub-TeV range for the secondary yields, such as antiprotons and diffuse gamma-rays. Presently, the ignorance on the origin of the features represents a systematic error in the extraction of astrophysical parameters as well as for background estimates for indirect dark matter searches. We find that the spectral modifications are appreciable above 100 GeV, and can be responsible for ~30% effects for antiprotons at energies close to 1 TeV or for gamma's at energies close to 300 GeV, compared to currently considered predictions based on simple extrapolation of input fluxes from low energy data. Alternatively, if the feature originates from local sources, uncorrelated spectral changes might show up in antiproton and high-energy gamma-rays, with the latter ones likely dependent from the line-of-sight.Comment: 6 pages, 3 figures. Clarifications and references added, conclusions unchanged. Matches published versio

    Accessible interactive digital signage for visually impaired

    Get PDF
    In this workshop we discuss the potential of cross-modal haptic-auditory feedback for empowering visually impaired people to experience Interactive Digital Signage

    Evaluation of the infrared test method for the olympus thermal balance tests

    Get PDF
    The performance of the infrared (IR) rig used for the thermal balance testing of the Olympus S/C thermal model is discussed. Included in this evaluation are the rig effects themselves, the IRFLUX computer code used to predict the radiation inputs, the Monitored Background Radiometers (MBR's) developed to measure the absorbed radiation flux intensity, the Uniform Temperature Reference (UTR) based temperature measurement system and the data acquisition system. A preliminary set of verification tests were performed on a 1 m x 1 m zone to assess the performance of the IR lamps, calrods, MBR's and aluminized baffles. The results were used, in part, to obtain some empirical data required for the IRFLUX code. This data included lamp and calrod characteristics, the absorptance function for various surface types, and the baffle reflectivities

    New results on source and diffusion spectral features of Galactic cosmic rays: I- B/C ratio

    Get PDF
    In a previous study (Maurin et al., 2001), we explored the set of parameters describing diffusive propagation of cosmic rays (galactic convection, reacceleration, halo thickness, spectral index and normalization of the diffusion coefficient), and we identified those giving a good fit to the measured B/C ratio. This study is now extended to take into account a sixth free parameter, namely the spectral index of sources. We use an updated version of our code where the reacceleration term comes from standard minimal reacceleration models. The goal of this paper is to present a general view of the evolution of the goodness of fit to B/C data with the propagation parameters. In particular, we find that, unlike the well accepted picture, and in accordance with our previous study, a Kolmogorov-like power spectrum for diffusion is strongly disfavored. Rather, the χ2\chi^2 analysis points towards δ0.7\delta\gtrsim 0.7 along with source spectra index 2.0\lesssim 2.0. Two distinct energy dependences are used for the source spectra: the usual power-law in rigidity and a law modified at low energy, the second choice being only slightly preferred. We also show that the results are not much affected by a different choice for the diffusion scheme. Finally, we compare our findings to recent works, using other propagation models. This study will be further refined in a companion paper, focusing on the fluxes of cosmic ray nuclei.Comment: 32 pages, 13 figures, accepted in A&

    Preface

    Get PDF

    LOW-COST 4D BIM MODELLING: A COMPARISON BETWEEN FREECAD AND COMMERCIAL SOFTWARE

    Get PDF
    Abstract. The paper aims to investigate the potential inherent in a FOSS (Free and Open Source Software) approach for the 4D BIM modelling using Freecad. In order to reach this goal it shows a comparison of Freecad features with those of commercial software, considering the evaluation of the effective application of this Open Source software in the professional environment, and highlighting the progress in the FOSS BIM area, that still represents an unexplored study field if compared to the vast publications related to BIM modelling that occurred in the last two decades. To this end, the study has been carried out on a singular case study, a steel canopy which has been designed for the urban renewal of a public space in Teramo. Despite its size, the canopy required the definition of complex details. Its structural system has addressed the study to compare Freecad with some software dedicated to steel structures or particularly suitable for the modelling of this specific structural typology: Tekla Structures and Sketchup. Starting from a concise historical reconstruction of the FOSS spread, the paper introduces a brief overview of the potential of Freecad in terms of BIM modelling - also proposing an operational modality to facilitate the drawing of BIM elements within the software - and finally reaching to the examination of three simulations which has been carried. This comparison can be useful to establish the current state of development of Freecad in the field of 4D BIM
    corecore