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Manon-Salas M.N.,Insurgentes University | Hernandez-Berriel M.C.,Toluca Institute of Technology | Marquez-Benavides L.,Universidad Michoacana de San Nicolas de Hidalgo
Revista Internacional de Contaminacion Ambiental | Year: 2012

The aim of this study was to determine the relationship between the accelerated anaerobic degradation and the settlement of municipal solid waste (MSW) in laboratory-scale bioreactors (LAB), by generating models using multivariate analysis. The settlement of MSW depends on several factors, multivariate analysis therefore provides the ability to evaluate a number of alternatives and select those that have statistical significance. Data for this study was obtained from an experimental design with 21 LAB. Each LAB was loaded with a volume of 412.24 cm3 MSW from the landfill site in Pátzcuaro, Michoacán. Three groups of seven LAB were operated using leachate recirculation rates of 40, 60 and 80% volume (%V). One LAB was dismantled from each group at day 15, 45, 75, 105, 135, 165 and 201 of experimentation. Refuse was then analyzed for settlement (%), pH and volatile solids removal (SVR); methane in biogas was also monitored. It was found that CH4 had collinearity problems related to SVR. The obtained model showed a strong association between RSV and settlement, the linear model with the highest precision was selected.

Galvanauskaite N.,Kaunas University of Technology | Sulcius A.,Kaunas University of Technology | Griskonis E.,Kaunas University of Technology | Diaz-Arista P.,Insurgentes University
Transactions of the Institute of Metal Finishing | Year: 2011

The preparation of a stable manganese ammonium sulphate bath (MASB) with a Te(VI) additive was investigated. It was found that the best Te(VI) additive is orthotelluric acid H6TeO6. The influence of the Te(VI) additive (0.55-2.20 mM) on cathode polarisation in a MASB was investigated. Current efficiency of manganese coatings electrodeposited from the MASB with 2.20 mM Te(VI) additive ranged from 34.1 to 37.7% and the concentration of incorporated tellurium was from 0.88 to 2.22%. It was determined that coatings reached the maximum values of tensile stress during the initial period of electrolysis. Tellurium incorporates in Mn coatings and changes their structure and morphology. This also influences microhardness of the coatings. The electrodeposited coatings consist of a mixture of two phases: brittle β-Mn and plastic b-Mn. A brittle a-Mn phase predominates in coatings obtained at high current densities. © 2011 Institute of Metal Finishing.

Martinez-Martinez J.,Insurgentes University | Xu L.,University of Waterloo
Journal of Constructional Steel Research | Year: 2011

The use of panelized cold-formed steel framing as the primary structural system has become increasingly popular for low- and mid-rise residential and commercial construction. The primary load-resistant elements in such framing are the structural panels built with uniformly spaced cold-formed steel studs and covered with structural sheathing. By taking advantage of in-line-framing, the framing members can be designed manually by using load tables published by manufacturers or spreadsheets developed in-house. In the case where the overall behaviour of the structure is needed, a finite element analysis has to be carried out. Conducting a finite element analysis for such types of buildings can be time consuming due to the large number of elements involved in modeling the framing member and structural sheathing. In this paper we present a simplified approach for analyzing cold-formed steel buildings by using finite element methods. In the proposed method, a typical 1.2 m wide wall panel which is built with cold-formed steel studs and structural sheathing is modeled by a 16-node shell element having equivalent material properties. In addition, the nonlinear behaviour of shear wall panels is simulated by a stiffness degradation factor. Compared to the conventional finite element method, a lesser number of elements will be used in the proposed method for modeling a building structure. The accuracy and efficiency of the proposed method are demonstrated through the comparison of results of the proposed and the conventional method on single shear wall panels. In addition, an example of nonlinear analysis for a three-storey building is presented. © 2010 Elsevier Ltd. All rights reserved.

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