497 research outputs found

    Energetic BEM for the numerical analysis of 2D Dirichlet damped wave propagation exterior problems

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    Abstract Time-dependent problems modeled by hyperbolic partial differential equations can be reformulated in terms of boundary integral equations and solved via the boundary element method. In this context, the analysis of damping phenomena that occur in many physics and engineering problems is a novelty. Starting from a recently developed energetic space-time weak formulation for 1D damped wave propagation problems rewritten in terms of boundary integral equations, we develop here an extension of the so-called energetic boundary element method for the 2D case. Several numerical benchmarks, whose numerical results confirm accuracy and stability of the proposed technique, already proved for the numerical treatment of undamped wave propagation problems in several dimensions and for the 1D damped case, are illustrated and discussed

    Decorso del tempo e disastri ambientali : riflessioni sulla prescrizione del reato a partire dal caso Eternit

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    La notissima vicenda relativa al cd. caso Eternit, conclusasi in sede di legittimità con una declaratoria di estinzione per intervenuta prescrizione dei reati contestati – omissione dolosa di cautele, aggravata dalla verificazione del disastro (art. 437, co. 2, cp) e disastro cd. innominato (art. 434, co. 2, c.p.) –, ha posto all'attenzione anche del “grande pubblico” le complesse problematiche sottese all'individuazione del dies a quo della prescrizione penale. Nel presente contributo, l’Autore sottopone a vaglio critico le decisioni di merito e legittimità intervenute nel processo Eternit, con particolare riguardo alla questione dell’individuazione del dies a quo della prescrizione per il delitto di disastro cd. innominato (art. 434, co. 2, c.p.), concludendo nel senso di condividere le conclusioni della Corte di cassazione, sia pur alla luce di un diverso percorso argomentativo

    Application of Energetic BEM to 2D Elastodynamic Soft Scattering Problems

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    Abstract Starting from a recently developed energetic space-time weak formulation of the Boundary Integral Equations related to scalar wave propagation problems, in this paper we focus for the first time on the 2D elastodynamic extension of the above wave propagation analysis. In particular, we consider elastodynamic scattering problems by open arcs, with vanishing initial and Dirichlet boundary conditions and we assess the efficiency and accuracy of the proposed method, on the basis of numerical results obtained for benchmark problems having available analytical solution

    Si conclude definitivamente il processo ThyssenKrupp

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    Preparation of Sonocatalyst Fe2O3/ZnO using Sol-gel/precipitation method: characterization and removal of acid orange 7 in aqueous solution / Nur Fadzeelah A. K. and Nor Aimi Abdul Wahab

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    Fe2O3/ZnO composite catalyst was synthesized using a solgel/precipitation method. The synthesized samples were characterized by Xray diffraction (XRD), scanning elctron microscope (SEM) with energy dispersive X-tray spectroscopy (EDX) and Brunauer−Emmet−Teller (BET) method. The feasibility of Fe2O3/ZnO composite catalyst on the removal of Acid Orange 7 (AO7) solution was examined under an ultrasonic irradiation. The removal percentage of AO7 solution was monitored by UVvis spectrophotometer. The characterization results exhibited that the Fe2O3/ZnO composite catalyst was successfully prepared using the solgel/precipitation method. The loading of Fe2O3 particles on the surface of ZnO particles resulted in high surface area compared to ZnO catalyst. Performance wise, the highest removal percentage of AO7 solution for sonocatalytic activity (at 120 min) showed only 8.05% and 9.12% for ZnO catalyst and Fe2O3/ZnO composite catalyst, respectively. Thus, the poor removal of AO7 solution in sonocatalytic experiment using this composite catalyst indicating this catalyst is not a good potential as sonocatalyst in treatment of azo dyes. In addition, this study has revealed that Fe2O3/ZnO composite catalyst was superior to the adsorption activity in removing of AO7 from aqueous solution due to adsorption ability of Fe2O3

    A study on spline quasi-interpolation based quadrature rules for the isogeometric Galerkin BEM

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    Two recently introduced quadrature schemes for weakly singular integrals [Calabr\`o et al. J. Comput. Appl. Math. 2018] are investigated in the context of boundary integral equations arising in the isogeometric formulation of Galerkin Boundary Element Method (BEM). In the first scheme, the regular part of the integrand is approximated by a suitable quasi--interpolation spline. In the second scheme the regular part is approximated by a product of two spline functions. The two schemes are tested and compared against other standard and novel methods available in literature to evaluate different types of integrals arising in the Galerkin formulation. Numerical tests reveal that under reasonable assumptions the second scheme convergences with the optimal order in the Galerkin method, when performing hh-refinement, even with a small amount of quadrature nodes. The quadrature schemes are validated also in numerical examples to solve 2D Laplace problems with Dirichlet boundary conditions

    Aquilaria malaccensis Leaf as an Alternative Source of Anti-inflammatory Compounds

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    Currently, the long-term consumption of aspirin and non-aspirin non-steroidal anti-inflammatory drugs (NSAIDs) as anti-inflammatory medicines and pain relievers, have been reported to cause various side effects. Thus, natural compounds of several plant species including Aquilaria malaccensis have been explored as an alternative therapeutic source for inflammation treatment with regard to their safety and efficacy. Despite the accelerating rate on the research of agarwood leaf, the scientific evidences to elucidate the proclaimed pharmacological activities particularly anti-inflammatory activity are still limited. Therefore, it is the interest of this study to investigate the biological activity relating to the anti-inflammatory activity of A. malaccensis leaf extracted using Soxhlet and Supercritical Fluid Extraction (SFE) methods. Results showed that A. malaccensis leaf ethanolic soxhlet extract (ALEXB) gave higher yield (mg/g) of 98.33 ± 4.11 (9.83% wt/wt) as compared to soxhlet extract using hexane (ALEXA); 24.04 ± 5.27 (2.40% wt/wt) after 6 hours of extraction. Meanwhile, the supercritical fluid extract (SFEX) gave a relatively low yield of 12.57 ± 0.61 (1.26% wt/wt). The GCMS analysis revealed that 25, 30 and 16 compounds were detected in ALEXA, ALEXB and SFEX respectively with phytol as the major compound in the soxhlet extracts and n-hexadecanoic as a major compound in SFEX. Subsequently, in-vitro study showed that the extracts demonstrated inhibition of protein (albumin) denaturation in a concentration-dependent manner throughout a concentration range of 400-16000 µg/ml tested. Exclusively, the GCMS of leaf SFEX showed a peak of 1H-Cycloprop[e]azulene, decahydro-1,1,7-trimethyl-4-methylene (0.4205%), a tricyclic sesquiterpene that was testified to have potential analgesic and anti-inflammatory activity. Further research is warranted to explore the anti-inflammatory activities of A. malaccensis leaf extracts and their mechanism of action as an alternative halal ingredient for nutraceuticals and pharmaceuticals
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