22 research outputs found

    Higgs production via gluon fusion from kT-factorisation

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    Theoretical studies of Higgs production via gluon fusion are frequently carried out in the limit where the top quark mass is much larger than the Higgs mass, an approximation which reduces the top quark loop to an effective vertex. We present a numerical analysis of the error thus introduced by performing a Monte Carlo calculation for gg->h in kT-factorisation, using the parton shower generator CASCADE. We proceed to compare CASCADE to the collinear Monte Carlos PYTHIA, MC@NLO and POWHEG. We study the dependence of parton radiation on the resummation of high-energy corrections taken into account by kT-factorisation, and its influence on predictions for the Higgs pT spectrum.Comment: Contribution to the Workshop Diffraction 2010, Otranto (Italy), September 201

    Nanocrystalline La0.8Sr0.2MnyFe1-yO3-δ perovskites and their oxygen deficiency correlation with their oxygen permeation and CO oxidation properties

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    The present paper aims at the investigation of the interrelation between the composition, microstructural properties and the oxygen deficiency of La0.8Sr0.2MnyFe1-yO3-δ (y=0-1) type perovskites, influencing their properties as membranes or oxidation catalysts

    GLYCEROL STEAM REFORMING ON NICKEL LOADED APATITE-TYPE LANTHANUM SILICATES

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    In the present paper for the first time it is reported the application of apatite-type lanthanum silicates in the steam reforming of glycerol reaction. The La9.83Si5Fe0.75Al0.25O26±d, apatite oxide prepared by solid state synthesis was applied as a supporting material for a 8wt% Ni catalyst. Apatite oxide and catalyst (fresh, reduced and used) samples were characterized by means of the XRD, SEM, TEM techniques. Catalytic testing experiments were performed using a fixed bed reactor at temperatures ranging from 400 to 700 oC with a feed consisting of C3H8Ο3 (20% v/v.) and H2O in the liquid phase

    Impact of processing parameters on tensile strength, inprocess crystallinity and mesostructure in FDM-fabricated PLA specimens

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    Purpose – This study aims to investigate the impact of layer thickness, extrusion temperature, extrusion speed and build plate temperature on the tensile strength, crystallinity achieved during fabrication (herein, in-process crystallinity) and mesostructure of Poly(lactic acid) specimens. Both tensile strength and in-process crystallinity were optimized and verified as the function of processing parameters, and their relationship was thoroughly examined. Design/methodology/approach – The four key technological parameters were systematically varied as factors on three levels, using the statistically designed experiment. Surface response methodology was used to optimize tensile strength and crystallinity for the given ranges of input factors. Optimized factor settings were used in a set of confirmation runs, where the result of optimization was experimentally confirmed. Material characterization was performed using differential scanning calorimetry and X-ray diffraction analysis, while the effect of processing parameters on mesostructure was examined by scanning electron microscopy. Findings – Layer thickness and its quadratic effect are dominant contributors to tensile strength. Significant interaction between layer thickness and extrusion speed implies that these parameters should always be varied simultaneously within designed experiment to obtain adequate process model. As regards, the in-process crystallinity, extrusion speed is part of two significant interactions with plate temperature and layer thickness, respectively. Quality of mesostructure is vital contributor to tensile strength during FDM process, while the in-process crystallinity exhibited no impact, remaining below the 20 per cent margin regardless of process parameter settings. Originality/value – According to available literature, there have been no previously published investigations which studied the effect of process parameters on tensile strength, mesostructure and in-process crystallinity through systematic variation of four critical processing parameters

    Numerical Integration of Discontinuous Functions in Many Dimensions

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    Hydrothermal Synthesis of ZnO–doped Ceria Nanorods: Effect of ZnO Content on the Redox Properties and the CO Oxidation Performance

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    The rational design of highly efficient, noble metal-free metal oxides is one of the main research priorities in the area of catalysis. To this end, the fine tuning of ceria-based mixed oxides by means of aliovalent metal doping has currently received particular attention due to the peculiar metal-ceria synergistic interactions. Herein, we report on the synthesis, characterization and catalytic evaluation of ZnO–doped ceria nanorods (NR). In particular, a series of bare CeO2 and ZnO oxides along with CeO2/ZnO mixed oxides of different Zn/Ce atomic ratios (0.2, 0.4, 0.6) were prepared by the hydrothermal method. All prepared samples were characterized by X-ray diffraction (XRD), N2 physisorption, temperature-programmed reduction (TPR), scanning electron microscopy with energy dispersive X-ray spectroscopy (SEM-EDS) and transmission electron microscopy (TEM). The CO oxidation reaction was employed as a probe reaction to gain insight into structure-property relationships. The results clearly showed the superiority of mixed oxides as compared to bare ones, which could be ascribed to a synergistic ZnO–CeO2 interaction towards an improved reducibility and oxygen mobility. A close correlation between the catalytic activity and oxygen storage capacity (OSC) was disclosed. Comparison with relevant literature studies verifies the role of OSC as a key activity descriptor for reactions following a redox-type mechanism
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