Examinando por Materia "Statistical analysis"

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    Ítem
    Identifying Factors Causing Delays and Cost Overruns in Construction Projects in Colombia
    (Universidad EAFIT, 2018-06-14) Lozano Serna, Sara; Patiño Galindo, Ivonne; Gómez-Cabrera, Adriana; Torres, Andrés; Pontificia Universidad Javeriana
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    Ítem
    The removal of the trivalent chromium from the leather tannery wastewater: the optimisation of the electro-coagulation process parameters.
    (IWA PUBLISHING, 2011-02-01) GilPavas, E.; Dobrosz-Gomez, I.; Gomez-Garcia, M. A.; GilPavas, E.; Dobrosz-Gomez, I.; Gomez-Garcia, M. A.; Universidad EAFIT. Departamento de Ingeniería de Procesos; Procesos Ambientales (GIPAB)
    The capacity of the electro-coagulation (EC) process for the treatment of the wastewater containing Cr3+, resulting from a leather tannery industry placed in Medellin (Colombia), was evaluated. In order to assess the effect of some parameters, such as: the electrode type (Al and/or Fe), the distance between electrodes, the current density, the stirring velocity, and the initial Cr3+ concentration on its efficiency of removal (%RCr+3), a multifactorial experimental design was used. The %RCr3+ was defined as the response variable for the statistical analysis. In order to optimise the operational values for the chosen parameters, the response surface method (RSM) was applied. Additionally, the Biological Oxygen Demand (BOD5), the Chemical Oxygen Demand (COD), and the Total Organic Carbon (TOC) were monitored during the EC process. The electrodes made of aluminium appeared to be the most effective in the chromium removal from the wastewater under study. At pH equal to 4.52 and at 28 degrees C, the optimal conditions of Cr3+ removal using the EC process were found, as follows: the initial Cr3+ concentration=3,596 mg/L, the electrode gap=0.5 cm, the stirring velocity=382.3 rpm, and the current density=57.87 mA/cm2. At those conditions, it was possible to reach 99.76% of Cr3+ removal, and 64% and 61% of mineralisation (TOC) and COD removal, respectively. A kinetic analysis was performed in order to verify the response capacity of the EC process at optimised parameter values.
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    Ítem
    Statistical analysis of the main incremental forming-SPIF process parameters that contribute to the change the roughness in an experimental geometry
    (FEDERACION ASOCIACIONES INGENIEROS INDUSTRIALES ESPANA, 2016-11-01) Paramo-Bermúdez, G.-J.; Bustamante-Correa, F.-A.; Benítez-Lozano, A.-J.; Paramo-Bermúdez, G.-J.; Bustamante-Correa, F.-A.; Benítez-Lozano, A.-J.; Universidad EAFIT. Departamento de Ingeniería de Producción; Grupo en Tecnologías para la Producción
    Over time the process of incremental deformation of sheet metal without matrix in its variant (SPIF), has been developed in different countries with the aim of meeting the needs of flexible production with no investment in tooling and low production costs. As in any manufacturing process is important to obtain a surface quality of the part that meets customer needs, this variable is evaluated by the average roughness (Ra). For this reason the purpose of this study is to investigate the influence of the variation of three process parameters and determine which of them contributes in greater proportion to the change in the average roughness (Ra) measured parallel and perpendicular to the path followed by the tool. Besides this, it wants to validate the impact that has the spindle speed in the analyzed variable and the orange peel defect. To this end, a full multifactorial design of experiments with three factors and two levels () and three replicates were performed, in order to obtain greater reliability in the model. Subsequently, an analysis of variance is executed and the results are formalized, finding which parameters influence more than others in changing roughness and how the orange peel defect depends on the spindle speed. Additionally, the results are compared with the authors cited. The aspects developed in this study highlight the importance of improving quality variables in any field of sheet metal processing in the international industrial environment.
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    Ítem
    Treatment of automotive industry oily wastewater by electrocoagulation: statistical optimization of the operational parameters.
    (IWA PUBLISHING, 2009-11-01) GilPavas, Edison; Molina-Tirado, Kevin; Angel Gomez-Garcia, Miguel; GilPavas, Edison; Molina-Tirado, Kevin; Angel Gomez-Garcia, Miguel; Universidad EAFIT. Departamento de Ingeniería de Procesos; Procesos Ambientales (GIPAB)
    An electrocoagulation process was used for the treatment of oily wastewater generated from an automotive industry in Medellin (Colombia). An electrochemical cell consisting of four parallel electrodes (Fe and Al) in bipolar configuration was implemented. A multifactorial experimental design was used for evaluating the influence of several parameters including: type and arrangement of electrodes, pH, and current density. Oil and grease removal was defined as the response variable for the statistical analysis. Additionally, the BOD(5), COD, and TOC were monitored during the treatment process. According to the results, at the optimum parameter values (current density = 4.3 mA/cm(2), distance between electrodes = 1.5 cm, Fe as anode, and pH = 12) it was possible to reach a c.a. 95% oils removal, COD and mineralization of 87.4% and 70.6%, respectively. A final biodegradability (BOD(5)/COD) of 0.54 was reached.