15,104 research outputs found

    Analysis of Energy Consumption Performance towards Optimal Radioplanning of Wireless Sensor Networks in Heterogeneous Indoor Environments

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    In this paper the impact of complex indoor environment in the deployment and energy consumption of a wireless sensor network infrastructure is analyzed. The variable nature of the radio channel is analyzed by means of deterministic in-house 3D ray launching simulation of an indoor scenario, in which wireless sensors, based on an in-house CyFi implementation, typically used for environmental monitoring, are located. Received signal power and current consumption measurement results of the in-house designed wireless motes have been obtained, stating that adequate consideration of the network topology and morphology lead to optimal performance and power consumption reduction. The use of radioplanning techniques therefore aid in the deployment of more energy efficient elements, optimizing the overall performance of the variety of deployed wireless systems within the indoor scenario

    The abundance of 28Si32S, 29Si32S, 28Si34S, and 30Si32S in the inner layers of the envelope of IRC+10216

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    We present high spectral resolution mid-IR observations of SiS towards the C-rich AGB star IRC+10216 carried out with the Texas Echelon-cross-Echelle Spectrograph mounted on the NASA Infrared Telescope Facility. We have identified 204 ro-vibrational lines of 28Si32S, 26 of 29Si32S, 20 of 28Si34S, and 15 of 30Si32S in the frequency range 720-790 cm-1. These lines belong to bands v=1-0, 2-1, 3-2, 4-3, and 5-4, and involve rotational levels with Jlow<90. About 30 per cent of these lines are unblended or weakly blended and can be partially or entirely fitted with a code developed to model the mid-IR emission of a spherically symmetric circumstellar envelope composed of expanding gas and dust. The observed lines trace the envelope at distances to the star <35R* (~0.7 arcsec). The fits are compatible with an expansion velocity of 1+2.5(r/R*-1) km/s between 1 and 5R*, 11 km/s between 5 and 20R*, and 14.5 km/s outwards. The derived abundance profile of 28Si32S with respect to H2 is 4.9e-6 between the stellar photosphere and 5R*, decreasing linearly to 1.6e-6 at 20R* and to 1.3e-6 at 50R*. 28Si32S seems to be rotationally under LTE in the region of the envelope probed with our observations and vibrationally out of LTE in most of it. There is a red-shifted emission excess in the 28Si32S lines of band v=1-0 that cannot be found in the lines of bands v=2-1, 3-2, 4-3, and 5-4. This excess could be explained by an enhancement of the vibrational temperature around 20R* behind the star. The derived isotopic ratios 28Si/29Si, and 32S/34S are 17 and 14, compatible with previous estimates.Comment: 11 pages, 5 figures, and 4 tables. Accepted for publication in MNRA

    Characterization of Nb22O54 microrods grown from niobium oxide powders recovered from mine tailings

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    In this work, the possibility of using niobium oxide recovered from tailings from the Penouta Sn-Nb-Ta deposit (located at the North of Spain) as starting material for growing microstructures is demonstrated. The properties of the starting material have been studied to understand its crystal structure, quality and purity. Recovered niobium oxide powders are mainly of TT-Nb2O5. These powders have been used to grow Nb22O54 microrods by an evaporation method in an argon atmosphere. Different characterization techniques (X-Ray diffraction, scanning electron microscopy, micro-Raman spectroscopy, luminescence) have been used to determine the properties of Nb22O54 microrods, mainly focusing on the crystal quality and refractive index. The present study opens the way to the transformation of waste (mine tailings) into a material of high technological value as niobium oxide, and its reintroduction into the value chain for a wide range of applications, from coatings to batteries and supercapacitors

    Kinematics of the Outflow From The Young Star DG Tau B: Rotation in the vicinities of an optical jet

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    We present 12^{12}CO(2-1) line and 1300 ÎŒ\mum continuum observations made with the Submillimeter Array (SMA) of the young star DG Tau B. We find, in the continuum observations, emission arising from the circumstellar disk surrounding DG Tau B. The 12^{12}CO(2-1) line observations, on the other hand, revealed emission associated with the disk and the asymmetric outflow related with this source. Velocity asymmetries about the flow axis are found over the entire length of the flow. The amplitude of the velocity differences is of the order of 1 -- 2 km s−1^{-1} over distances of about 300 -- 400 AU. We interpret them as a result of outflow rotation. The sense of the outflow and disk rotation is the same. Infalling gas from a rotating molecular core cannot explain the observed velocity gradient within the flow. Magneto-centrifugal disk winds or photoevaporated disk winds can produce the observed rotational speeds if they are ejected from a keplerian disk at radii of several tens of AU. Nevertheless, these slow winds ejected from large radii are not very massive, and cannot account for the observed linear momentum and angular momentum rates of the molecular flow. Thus, the observed flow is probably entrained material from the parent cloud. DG Tau B is a good laboratory to model in detail the entrainment process and see if it can account for the observed angular momentum.Comment: Accepted to Ap

    1.3 mm Polarized emission in the circumstellar disk of a massive protostar

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    We present the first resolved observations of the 1.3 mm polarized emission from the disk-like structure surrounding the high-mass protostar Cepheus A HW2. These CARMA data partially resolve the dust polarization, suggesting a uniform morphology of polarization vectors with an average position angle of 57° ± 6° and an average polarization fraction of 2.0% ± 0.4%. The distribution of the polarization vectors can be attributed to (1) the direct emission of magnetically aligned grains of dust by a uniform magnetic field, or (2) the pattern produced by the scattering of an inclined disk. We show that both models can explain the observations, and perhaps a combination of the two mechanisms produces the polarized emission. A third model including a toroidal magnetic field does not match the observations. Assuming scattering is the polarization mechanism, these observations suggest that during the first few 104 years of high-mass star formation, grain sizes can grow from1 mm to several 10s ÎŒm.Fil: Fernandez Lopez, Manuel. Provincia de Buenos Aires. GobernaciĂłn. Comision de Investigaciones CientĂ­ficas. Instituto Argentino de RadioastronomĂ­a. Consejo Nacional de Investigaciones CientĂ­ficas y TĂ©cnicas. Centro CientĂ­fico TecnolĂłgico Conicet - La Plata. Instituto Argentino de Radioastronomia; ArgentinaFil: Stephens, I. W.. Harvard-Smithsonian Center for Astrophysics; Estados Unidos. Boston University; Estados Unidos. University of Illinois; Estados UnidosFil: Girart, J. M.. Harvard-Smithsonian Center for Astrophysics; Estados Unidos. Institut de CiĂšncies de l’Espai; EspañaFil: Looney, L.. University of Illinois; Estados UnidosFil: Curiel, S.. Universidad Nacional AutĂłnoma de MĂ©xico; MĂ©xicoFil: Segura Cox, D.. University of Illinois; Estados UnidosFil: Eswaraiah, C.. National Tsing Hua University; RepĂșblica de ChinaFil: Lai, S. P.. National Tsing Hua University; RepĂșblica de Chin

    EURONU WP6 2009 yearly report: Update of the physics potential of Nufact, superbeams and betabeams

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    Many studies in the last ten years have shown that we can measure the unknown angle theta13, discover leptonic CP violation and determine the neutrino hierarchy in more precise neutrino oscillation experiments, searching for the subleading channel nue -> numu in the atmospheric range. In this first report of WP6 activities the following new results are reviewed: (1) Re-evaluation of the physics reach of the upcoming generation of experiments to measure theta13 and delta; (2) New tools to explore a larger parameter space as needed beyond the standard scenario; (3) Neutrino Factory: (a) evaluation of the physics reach of a Nufact regards sterile neutrinos; (b) evaluation of the physics reach of a Nufact as regards non-standard interactions; (c) evaluation of the physics reach of a Nufact as regards violation of unitarity; (d) critical assessment on long baseline tau-detection at Nufact; (e) new physics searches at a near detector in a Nufact; (4) Beta-beams: (a) choice of ions and location for a gamma = 100 CERN-based beta-beam; (b) re-evaluation of atmospheric neutrino background for the gamma = 100 beta-beam scenario; (c) study of a two baseline beta-beam; (d) measuring absolute neutrino mass with beta-beams; (e) progress on monochromatic beta-beams; (5) Update of the physics potential of the SPL super-beam. Eventually, we present an updated comparison of the sensitivity to theta13, delta and the neutrino mass hierarchy of several of the different proposed facilities.Comment: 2009 Yearly report of the Working Package 6 (Physics) of the EUROnu FP7 EU project. 55 pages, 21 figures

    Black Box Model of Integrated Circuits for ESD Behavioral Simulation and Industrial Application Case

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    In order to design electronic products for Electro Static Discharges constraints, the use of simulation is fundamental. This is the only solution to justify the design and to manage properly the margin during the development. In order to do so, models are required and especially for the integrated circuits (IC). A Pspice model had been developed and validated for ESD performance prediction of IC implemented inside an electronic product. Nevertheless, the practical implementation of these modeling techniques for IC induced some issues, especially under Pspice, being the targeted tool for our simulation. Divergences issues during time domain simulation were frequently observed and sometimes irresolvable with model previously proposed. We propose in this article new implementation techniques in Pspice. A practical example is used to demonstrate the capability of our model
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