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Subject: search.filters.subject.Analysis of variance

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    Thermochemical treatment of spent coffee grounds via torrefaction: A statistical evidence of biochar properties similarity between inert and oxidative conditions
    (2024-03-01)
    Pambudi, Suluh
    ;
    Jongyingcharoen, Jiraporn Sripinyowanich
    ;
    Saechua, Wanphut
    This study used several statistical analyses to explore the impact of both inert and oxidative conditions on the characteristics of biochar derived from the torrefaction of spent coffee grounds (SCG). The study also considered variations in torrefaction temperature and residence time. Various fuel analyses were conducted, including high heating value (HHV), torrefaction index, proximate characteristics, thermogravimetric analysis (TGA), hygroscopicity, and Fourier-transform infrared spectroscopy (FTIR). The analysis of variance (ANOVA) revealed that the influence of both inert and oxidative conditions on HHV and mass yield was insignificant (p ≥ 0.05). Moreover, considering the same temperature and residence time, principal component analysis (PCA) and hierarchical cluster analysis (HCA) identified oxidative and inert conditions belonging to the same group or cluster. This finding indicated that neither atmospheric condition significantly affected the characteristics of the biochar measured in this research. Therefore, oxidative torrefaction offers significant advantages as it can produce biochar of comparable quality under inert conditions.
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    Material structure selection of blue organic light emitting diodes utilizing a hybrid experimental design
    (2016-08-12)
    Shie, Jie Ren
    ;
    Chittawanij, Apisit
    ;
    Hong, Lin Ann
    ;
    Lai, Chang Jun
    ;
    Lai, Yun Jr
    A hybrid approach integrating a Taguchi orthogonal table with an irregular design of experiments (DOE) method was proposed for selecting an optimal material structure of blue organic light emitting diodes in order to achieve multi-objective quality characteristics of devices. Analysis of variance (ANOVA) was adopted to identify significant factors before regression models were obtained. Finally, an optimal material structure was determined by maximizing a desirability function relating to selected critical quality characteristics including the driving voltage, the luminance, and luminance efficiency.
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    Effects of wire-EDM machining variables on surface roughness of newly developed DC 53 die steel: Design of experiments and regression model
    (2007-10-01)
    Kanlayasiri, K.
    ;
    Boonmung, S.
    DC53 is a newly developed cold die steel from Daido Steel, Japan. It is an improvement over the familiar cold die steel SKD11. Because DC53 is a new die steel, only little information is available in literature for its machining characteristics. This paper presents an investigation of the effects of machining variables on the surface roughness of wire-EDMed DC53 die steel. In this study, the machining variables investigated were pulse-peak current, pulse-on time, pulse-off time, and wire tension. Analysis of variance (ANOVA) technique was used to find out the variables affecting the surface roughness. Assumptions of ANOVA were discussed and carefully examined using analysis of residuals. Quantitative testing methods on residual analysis were used in place of the typical qualitative testing techniques. Results from the analysis show that pulse-on time and pulse-peak current are significant variables to the surface roughness of wire-EDMed DC53 die steel. The surface roughness of the test specimen increases when these two parameters increase. Lastly, a mathematical model was developed using multiple regression method to formulate the pulse-on time and pulse-peak current to the surface roughness. The developed model was validated with a new set of experimental data, and the maximum prediction error of the model was less than 7%. © 2007.
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    An investigation on effects of wire-EDM machining parameters on surface roughness of newly developed DC53 die steel
    (2007-06-12)
    Kanlayasiri, K.
    ;
    Boonmung, S.
    DC53 is a newly developed cold die steel from Daido Steel, Japan. It is an improvement over the familiar cold die steel SKD11. Because DC53 is a new die steel, only little information is available in literature for its machining characteristics. This paper investigated the effects of machining parameters on surface roughness of wire EDMed DC53 die steel. The investigated machining parameters were pulse-on time, pulse-off time, pulse-peak current, and wire tension. Analysis of variance (ANOVA) technique was used to find out the parameters affecting the surface roughness. Assumptions of ANOVA were discussed and then examined through residual analysis. Quantitative testing methods on residual analysis were employed in place of the typical qualitative testing techniques. Results from ANOVA show that pulse-on time and pulse-peak current are significant variables to surface roughness of wire-EDMed DC53 die steel. The surface roughness of test specimen increased as these two variables increased. © 2007.