102,452 research outputs found
Manuale Operativo per la Gestione degli Impianti di Disinfezione dell'Acqua con Impiego di Sostanze a Base di Cloro
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Nuove Tecniche per l'Abbattimento e il Controllo dei Composti Organo-alogenati nelle Acque
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Gli acidi grassi omega-3 attenuano la vasocostrizione arteriosa mediante l'aumentata produzione di ossido nitrico
No full textAssociation of elevated levels of PAI-1 with insulin resistance and inflammatory markers in hypertension.
No full textEffect of alternate CH4-reducing/lean combustion treatments on the reactivity of fresh and S-poisoned Pd/CeO2/Al2O3 catalysts
No full textThis work investigates the effect of treatments under different CH4-containing atmospheres on the reactivity of fresh and S-poisoned 2% w/w Pd/Al2O3/CeO2 catalysts for methane combustion.
Over the fresh catalyst the decomposition/reformation processes of PdO occurring during cycles of CH4-reducing/lean combustion pulses allowed the complete recovery of activity losses possibly associated with H2O poisoning which were observed during prolonged exposure under lean combustion conditions. The presence of CeO2 markedly enhances both the activity losses under lean combustion conditions and the rate of PdO reoxidation/reactivation upon Pd redox cycle.
Under lean combustion conditions, regeneration of catalyst deactivated by exposure to SO2-containing atmosphere required very high temperatures (above 750 degrees C) in order to decompose stable sulphate species adsorbed on the support. Treatments consisting of alternate CH4- reducing/lean combustion pulses allowed a complete recovery of activity at much lower temperatures (550-600 degrees C) due to the reduction of sulphates by CH4 activated on the surface of Pd metal. A protecting role of CeO2 on Pd poisoning due either to exposure to SO2-containing atmosphere or to spill-back of support sulphates species was also evidenced. (C) 2007 Elsevier B.V. All rights reserved
The peak stress method to calculate residual notch stress intensity factors in welded joints
No full textAccording to the recent literature, the intensity of linear elastic residual stress
fields near the toe region of a welded joint can be quantified by the residual
notch stress intensity factors (R‐NSIFs). The computational effort required to
compute the R‐NSIFs implies strong limitations of applicability in practice,
owing to the very refined meshes needed and to the non‐linear transient nature
of welding process simulations, especially in 3‐dimensional numerical models
of large structures. The peak stress method (PSM) is a design approach that
takes care of the industrial needs of rapidity and ease of use. According to the
PSM, it is possible to evaluate the R‐NSIFs by using the peak stress calculated
at the point of singularity with coarse finite element (FE) models. While the
PSM was originally calibrated by using the Ansys FE code, in the present contribution,
the PSM has been calibrated to rapidly estimate the R‐NSIFs in the
Sysweld FE environment
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