721 research outputs found

    Design of a movil manipulator with optimum mechanical energy using differential evolution

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    En este trabajo se establece el problema de diseño cinemático y dinámico de los eslabones de un manipulador móvil como un problema de optimización numérica, con el objetivo de minimizar la energía mecánica del sistema en las posiciones críticas de un espacio de trabajo pre-establecido. Al cumplir con el objetivo propuesto se disminuye consecuentemente el consumo de energía que necesita el sistema de control durante su operación dentro del espacio de trabajo pre-establecido. Para dar solución al problema de optimización, se incorpora un mecanismo de explotación exhaustiva en el algoritmo tradicional de evolución diferencial, permitiendo mejorar la búsqueda dentro de una vecindad del espacio de diseño. Resultados en simulación muestran el desempeño del algoritmo. A su vez se muestra un menor consumo de energía del diseño resultante comparado con otros 3 diseños.In this work, the design of kinematic and dynamic parameters of links of a mobile manipulator is stated as a numerical optimization problem (NOP). The NOP aims to minimize the mechanical energy of the system in critical positions given by the vertices of a workspace and consequently reduce the energy consumption of the control system during its operation in the workspace. An exhaustive exploitation mechanism is included in the traditional differential evolution algorithm to improve the search into a neighborhood in the design space. Simulation results show the performance of the algorithm. The resulting design shows less energy consumption than other three designs.Peer Reviewe

    CRISPRED: A data pipeline for the CRISP imaging spectropolarimeter

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    The production of science-ready data from major solar telescopes requires expertise beyond that of the typical observer. This is a consequence of the increasing complexity of instruments and observing sequences, which require calibrations and corrections for instrumental and seeing effects that are not only difficult to measure, but are also coupled in ways that require careful analysis in the design of the correction procedures. Modern space-based telescopes have data-processing pipelines capable of routinely producing well-characterized data products. High resolution imaging spectropolarimeters at ground-based telescopes need similar data pipelines.We present new methods for flat-fielding spectropolarimetric data acquired with telecentric Fabry-Perot instruments and a new approach for accurate camera co-alignment for image restoration. We document a procedure that forms the basis of current state-of-the-art processing of data from the CRISP imaging spectropolarimeter at the Swedish 1 m Solar Telescope (SST). By collecting, implementing, and testing a suite of computer programs, we have defined a data reduction pipeline for this instrument. This pipeline, CRISPRED, streamlines the process of making science-ready data.It is implemented and operated in IDL, with time-consuming steps delegated to C.CRISPRED will also be the basis for the data pipeline of the forthcoming CHROMIS instrument. © ESO, 201

    A home and ambulatory artificial nutrition (NADYA) group report, home parenteral nutrition in Spain, 2013

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    Aim: to communicate the results of the Spanish Home Parenteral Nutrition (HPN) registry of the NADYA-SENPE group for the year 2013. Material and methods: data was recorded online by NADYA group collaborators that were responsible of the HPN follow-up from 1st January to 31st December 2013. Results: a total of 197 patients and 202 episodes of HPN were registered from 35 hospitals that represents a rate of 4,22 patients/million habitants/year 2013. The median age was 53 years (IQR 40 – 64) for 189 adult patients and 7 months (IQR 6 – 35,5) for children. The most frequent disease in adults was neoplasm (30,7%) followed by other diseases (20,1%) and mesenteric ischemia (12,7%). Short bowel syndrome and intestinal obstruction (25,9%) were in 35.7% cases the indications for HPN

    Multiwavelength studies of MHD waves in the solar chromosphere: An overview of recent results

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    The chromosphere is a thin layer of the solar atmosphere that bridges the relatively cool photosphere and the intensely heated transition region and corona. Compressible and incompressible waves propagating through the chromosphere can supply significant amounts of energy to the interface region and corona. In recent years an abundance of high-resolution observations from state-of-the-art facilities have provided new and exciting ways of disentangling the characteristics of oscillatory phenomena propagating through the dynamic chromosphere. Coupled with rapid advancements in magnetohydrodynamic wave theory, we are now in an ideal position to thoroughly investigate the role waves play in supplying energy to sustain chromospheric and coronal heating. Here, we review the recent progress made in characterising, categorising and interpreting oscillations manifesting in the solar chromosphere, with an impetus placed on their intrinsic energetics.Comment: 48 pages, 25 figures, accepted into Space Science Review

    Measurement of W Polarisation at LEP

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    The three different helicity states of W bosons produced in the reaction e+ e- -> W+ W- -> l nu q q~ at LEP are studied using leptonic and hadronic W decays. Data at centre-of-mass energies \sqrt s = 183-209 GeV are used to measure the polarisation of W bosons, and its dependence on the W boson production angle. The fraction of longitudinally polarised W bosons is measured to be 0.218 \pm 0.027 \pm 0.016 where the first uncertainty is statistical and the second systematic, in agreement with the Standard Model expectation

    Search for Anomalous Couplings in the Higgs Sector at LEP

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    Anomalous couplings of the Higgs boson are searched for through the processes e^+ e^- -> H gamma, e^+ e^- -> e^+ e^- H and e^+ e^- -> HZ. The mass range 70 GeV < m_H < 190 GeV is explored using 602 pb^-1 of integrated luminosity collected with the L3 detector at LEP at centre-of-mass energies sqrt(s)=189-209 GeV. The Higgs decay channels H -> ffbar, H -> gamma gamma, H -> Z\gamma and H -> WW^(*) are considered and no evidence is found for anomalous Higgs production or decay. Limits on the anomalous couplings d, db, Delta(g1z), Delta(kappa_gamma) and xi^2 are derived as well as limits on the H -> gamma gamma and H -> Z gamma decay rates

    Measurement of W Polarisation at LEP

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    The three different helicity states of W bosons produced in the reaction e+ e- -> W+ W- -> l nu q q~ at LEP are studied using leptonic and hadronic W decays. Data at centre-of-mass energies \sqrt s = 183-209 GeV are used to measure the polarisation of W bosons, and its dependence on the W boson production angle. The fraction of longitudinally polarised W bosons is measured to be 0.218 \pm 0.027 \pm 0.016 where the first uncertainty is statistical and the second systematic, in agreement with the Standard Model expectation

    Neutral-Current Four-Fermion Production in e+e- Interactions at LEP

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    Neutral-current four-fermion production, e+e- -> ffff is studied in 0.7/fb of data collected with the L3 detector at LEP at centre-of-mass energies root(s)=183-209GeV. Four final states are considered: qqvv, qqll, llll and llvv, where l denotes either an electron or a muon. Their cross sections are measured and found to agree with the Standard Model predictions. In addition, the e+e- -> Zgamma* -> ffff process is studied and its total cross section at the average centre-of-mass energy 196.6GeV is found to be 0.29 +/- 0.05 +/- 0.03 pb, where the first uncertainty is statistical and the second systematic, in agreement with the Standard Model prediction of 0.22 pb. Finally, the mass spectra of the qqll final states are analysed to search for the possible production of a new neutral heavy particle, for which no evidence is found

    Measurement of Exclusive rho+rho- Production in Mid-Virtuality Two-Photon Interactions and Study of the gamma gamma* -> rho rho Process at LEP

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    Exclusive rho+rho- production in two-photon collisions between a quasi-real photon, gamma, and a mid-virtuality photon, gamma*, is studied with data collected at LEP at centre-of-mass energies root(s)=183-209GeV with a total integrated luminosity of 684.8pb^-1. The cross section of the gamma gamma* -> rho+ rho- process is determined as a function of the photon virtuality, Q^2, and the two-photon centre-of-mass energy, W_gg, in the kinematic region: 0.2GeV^2 < Q^2 <0.85GeV^2 and 1.1GeV < W_gg < 3GeV. These results, together with previous L3 measurements of rho0 rho0 and rho+ rho- production, allow a study of the gamma gamma* -> rho rho process over the Q^2-region 0.2GeV^2 < Q^2 < 30 GeV^2

    Measurement of the Running of the Electromagnetic Coupling at Large Momentum-Transfer at LEP

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    The evolution of the electromagnetic coupling, alpha, in the momentum-transfer range 1800GeV^2 < -Q^2 < 21600GeV^2 is studied with about 40000 Bhabha-scattering events collected with the L3 detector at LEP at centre-of-mass energies 189-209GeV. The running of alpha is parametrised as: alpha(Q^2) = alpha_0/(1-C Delta alpha(Q^2)), where alpha_0=\alpha(Q^2=0) is the fine-structure constant and C=1 corresponds to the evolution expected in QED. A fit to the differential cross section of the e+e- ->e+e- process for scattering angles in the range |cos theta|<0.9 excludes the hypothesis of a constant value of alpha, C=0, and validates the QED prediction with the result: C = 1.05 +/- 0.07 +/- 0.14, where the first uncertainty is statistical and the second systematic
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