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Ognjan Lužanin - One of the best experts on this subject based on the ideXlab platform.

  • using statistically Designed Experiment to optimize vacuum assisted post processing of binder jetted specimens
    Rapid Prototyping Journal, 2019
    Co-Authors: Dejan Movrin, Ognjan Lužanin, Vera Guduric
    Abstract:

    Purpose This paper aims to propose a vacuum-assisted post-processing method for use in binder jetted technology. The method is based on six key technological parameters and uses standard, commercially available consumables to achieve improvement in tensile strength, as well as the microstructure and porosity of the infiltrated matrix. Design/methodology/approach Six key technological parameters were systematically varied as factors on three levels, using design of Experiment, i.e. definitive screening design. Surface response methodology was used to optimize the process and yield optimal tensile strength for the given range of input factors. Thus obtained, the optimized factor settings were used in a set of confirmation runs, where the result of optimization was Experimentally confirmed. To confirm improvement in microstructure of the infiltrated matrix, SEM analysis was performed, while the reduction of porosity was analyzed using mercury porosimetry. Findings The obtained results indicate that, compared to its conventional counterpart, the proposed, optimized infiltration method yields improvement in tensile strength which is significant from both the statistical and engineering point of view, while reducing porosity by 3.5 times, using only standard consumables. Scanning electron microscopy examination of fractured specimens’ micrographs also revealed significant morphological differences between the conventional and proposed method of post-processing. This primarily reflects in higher surface area under hardened epoxy infiltrate, which contributes to increased load capacity of specimen cross-section. Research limitations/implications At the present stage of development, the most important limitation of the proposed method is the overall size of models which can be accommodated in standard vacuum impregnation units. Although, in this study, the infiltration method did not prove statistically significant, further investigation is required with models of complex geometry, various sizes and mass arrangements, where infiltration would be more challenging and could possibly result in different findings. Practical implications The most important practical implication of this study is the Experimentally verified result of optimization, which showed that tensile strength and matrix microstructure can be significantly improved, using just standard consumables. Social implications Improved strength contributes to reduction of material consumption, which, in a longer run, can be beneficial for environment protection and sustainable development. Originality/value Based on literature review, there have been no previous investigations which studied the tensile strength of infiltrated specimens through design of Experiment, which involved specimen preheating temperature, level and duration of vacuum treatment of infiltrate mixture and infiltrated specimens and infiltration method.

  • optimization of azo printing dye removal with oak leaves nzvi h2o2 system using statistically Designed Experiment
    Journal of Cleaner Production, 2018
    Co-Authors: Vesna Kecic, đurđa Kerkez, Miljana Prica, Ognjan Lužanin, Milena Becelictomin, Dragana Tomasevic Pilipovic, Božo Dalmacija
    Abstract:

    Abstract The paper investigates the potential use of nano zero-valent iron (nZVI) particles as a cheap, natural and effective catalyst in the Fenton-like system for the removal of water-based Magenta flexographic dye from aqueous solution. The functional nZVI was successfully synthesized within an environmentally friendly method, by using the natural product extract, oak leaves (OAK-nZVI). The process of Magenta removal was optimized using statistically Designed Experiment. The influence of four quantitative parameters on decolorization efficiency was investigated: initial dye concentration (20–180 mgL-1), OAK- nZVI dosage (0.75–60 mgL-1), H2O2 concentration (1–11 mM) and pH value (2–10). The results of statistical analysis show that OAK-nZVI dosage and pH significantly contribute to the decolorization efficiency, while the concentration of H2O2 has a significant influence on their impact. The optimization yielded highest removal efficiency of 91.95% under following conditions: initial dye concentration of 180 mgL−1, OAK-nZVI dosage of 60 mgL−1, H2O2 concentration of 11 mM and pH value 2. Optimization results were Experimentally verified. Treatment of real effluent under optimized Experimental conditions resulted within 84.06% Magenta removal after a reaction time of 60 min. The absorption spectra of Magenta dye clearly indicate the changes in the molecular structure in the form of the destruction of azo bond in the chromophore, leading to the decolorization of dye solution. Based on the GC–MS analysis, the mechanism for Fenton-like oxidation of Magenta was proposed.

Jeanne M. Hampton - One of the best experts on this subject based on the ideXlab platform.

  • Friction, wear, and lubrication of hydrogels as synthetic articular cartilage
    Wear, 2000
    Co-Authors: Mark E. Freeman, Michael J. Furey, Brian J. Love, Jeanne M. Hampton
    Abstract:

    Abstract In recent years, synthetic hydrogels have been studied not only as possible replacements for articular cartilage but as platforms for growing cartilage in a damaged joint. In the present study, the tribological behavior of synthesized poly(2-hydroxyethyl)methacrylate (polyHEMA) hydrogels was investigated in a four-factor, two-level Designed Experiment using a device developed for biotribology research. The contact geometry consisted of a 6-mm diameter stainless steel ball on flat polyHEMA disks. The variables in the Designed Experiment were (a) applied load, (b) lubrication, (c) hydrogel crosslink density, and (d) degree of hydrogel hydration. Linear oscillating sliding contact tests were conducted for 30 min for each test. The results showed several significant main effects and first-order interactions. Increasing the applied load from 6 to 20 N increased average hydrogel wear by 125%. Increased crosslink density reduced wear by over 60%. And increased hydration resulted in an increase of 130% in wear. The coefficient of friction ranged from a low value of 0.02 to a high of 1.7 while linear wear varied by a factor of over 60. Interactions between (a) hydration and lubrication and (b) hydration and crosslinking on wear were highly significant. The single most important finding from this study was that, as expected, there was no correlation between friction — which is commonly reported in the literature on hydrogels — and wear. Most of the data fell into two groups, namely low wear/low friction and high wear/low friction. These results may be useful in the tribological design of hydrogels for both low wear and low friction.

  • Friction, Wear, and Lubrication of Hydrogels as Synthetic Articular Cartilage
    1998
    Co-Authors: Mark E. Freeman, Michael J. Furey, Brian J. Love, Jeanne M. Hampton
    Abstract:

    In recent years, synthetic hydrogels have been studied not only as possible replacements for articular cartilage but also as platforms for growing cartilage in a damaged joint. In the present study, the tribological behaviour of synthesized poly (2- hydroxyethyl) methacrylate (polyHEMA) hydrogels was investigated in a four-factor, two-level Designed Experiment using a device developed for biotribology research. The contact geometry consisted of a 6mm diameter stainless steel ball on flat polyHEMA disks. The variables in the Designed Experiment were (a) applied load, (b) lubrication, (c) hydrogel cross-link density and (d) degree of hydrogel hydration. Linear oscillating sliding contact tests were conducted for 30 minutes for each test. The results showed several significant main effects and first-order interactions. Increasing the applied load from 6 to 20N increased average hydrogel wear by 125%. Increased cross-link density reduced wear by over 60%. And increased hydration resulted in an increase of 130% in wear. The coefficient of friction ranged from a low value of 0.02 to a high of 1.7 while linear wear varied by a factor of over 60. Interactions between (a) hydration and lubrication and (b) hydration and cross-linking on wear were highly significant. The single most important finding from this study was that, as expected, there was no correlation between friction - which is commonly reported in the literature on hydrogels- and wear. Most of the data fell into two groups, namely low wear-low friction and high wear-low friction. These results may be useful in the tribological design of hydrogels for both low wear and low friction.

Božo Dalmacija - One of the best experts on this subject based on the ideXlab platform.

  • optimization of azo printing dye removal with oak leaves nzvi h2o2 system using statistically Designed Experiment
    Journal of Cleaner Production, 2018
    Co-Authors: Vesna Kecic, đurđa Kerkez, Miljana Prica, Ognjan Lužanin, Milena Becelictomin, Dragana Tomasevic Pilipovic, Božo Dalmacija
    Abstract:

    Abstract The paper investigates the potential use of nano zero-valent iron (nZVI) particles as a cheap, natural and effective catalyst in the Fenton-like system for the removal of water-based Magenta flexographic dye from aqueous solution. The functional nZVI was successfully synthesized within an environmentally friendly method, by using the natural product extract, oak leaves (OAK-nZVI). The process of Magenta removal was optimized using statistically Designed Experiment. The influence of four quantitative parameters on decolorization efficiency was investigated: initial dye concentration (20–180 mgL-1), OAK- nZVI dosage (0.75–60 mgL-1), H2O2 concentration (1–11 mM) and pH value (2–10). The results of statistical analysis show that OAK-nZVI dosage and pH significantly contribute to the decolorization efficiency, while the concentration of H2O2 has a significant influence on their impact. The optimization yielded highest removal efficiency of 91.95% under following conditions: initial dye concentration of 180 mgL−1, OAK-nZVI dosage of 60 mgL−1, H2O2 concentration of 11 mM and pH value 2. Optimization results were Experimentally verified. Treatment of real effluent under optimized Experimental conditions resulted within 84.06% Magenta removal after a reaction time of 60 min. The absorption spectra of Magenta dye clearly indicate the changes in the molecular structure in the form of the destruction of azo bond in the chromophore, leading to the decolorization of dye solution. Based on the GC–MS analysis, the mechanism for Fenton-like oxidation of Magenta was proposed.

Paul E Benson - One of the best experts on this subject based on the ideXlab platform.

  • comparison of end result and method specifications for managing quality
    Transportation Research Record, 1995
    Co-Authors: Paul E Benson
    Abstract:

    The results of a statistically Designed Experiment in which asphalt concrete cores and nuclear gauge readings were taken from five California projects are reported. Relative compaction for the projects was controlled with a method specification. Analysis of variance is used to separate test error and locational components of variance for specific gravity, asphalt content, air voids, lift thickness, and grading. Compaction results are compared with similar results from 16 end result specification (ERS) jobs studied previously. Relative compaction on the ERS jobs averages 3.1% higher in value. Findings on test precision, increased lot size, and materials variability are discussed.

Michael J. Furey - One of the best experts on this subject based on the ideXlab platform.

  • Friction, wear, and lubrication of hydrogels as synthetic articular cartilage
    Wear, 2000
    Co-Authors: Mark E. Freeman, Michael J. Furey, Brian J. Love, Jeanne M. Hampton
    Abstract:

    Abstract In recent years, synthetic hydrogels have been studied not only as possible replacements for articular cartilage but as platforms for growing cartilage in a damaged joint. In the present study, the tribological behavior of synthesized poly(2-hydroxyethyl)methacrylate (polyHEMA) hydrogels was investigated in a four-factor, two-level Designed Experiment using a device developed for biotribology research. The contact geometry consisted of a 6-mm diameter stainless steel ball on flat polyHEMA disks. The variables in the Designed Experiment were (a) applied load, (b) lubrication, (c) hydrogel crosslink density, and (d) degree of hydrogel hydration. Linear oscillating sliding contact tests were conducted for 30 min for each test. The results showed several significant main effects and first-order interactions. Increasing the applied load from 6 to 20 N increased average hydrogel wear by 125%. Increased crosslink density reduced wear by over 60%. And increased hydration resulted in an increase of 130% in wear. The coefficient of friction ranged from a low value of 0.02 to a high of 1.7 while linear wear varied by a factor of over 60. Interactions between (a) hydration and lubrication and (b) hydration and crosslinking on wear were highly significant. The single most important finding from this study was that, as expected, there was no correlation between friction — which is commonly reported in the literature on hydrogels — and wear. Most of the data fell into two groups, namely low wear/low friction and high wear/low friction. These results may be useful in the tribological design of hydrogels for both low wear and low friction.

  • lubrication of ceramics by tribopolymerization a Designed Experiment to determine effects of monomer structure load and speed on wear
    Tribology Transactions, 1999
    Co-Authors: Michael J. Furey, B R Tritt, Czeslaw Kajdas, R Kempinski
    Abstract:

    An Experimental study of ceramic lubrication by tribopolymerization at high loads and high speeds, using a pin-on-disk (fixed ball-on-flat) machine with alumina-on-alumina, is presented. In order to extend the range of applied loads and sliding velocities beyond those used in previous studies, a three-factor, two-level Designed Experiment was carried out to determine the effects of monomer structure, load, and speed on wear. Five monomers of widely varying chemical structure were used at one percent concentration in a hydrocarbon carrier fluid, hexadecane. They consisted of (a) one condensation-type monomer, a partial glycol ester of a longchain dimer acid, and (b) four vinyl-type addition monomers. Two levels of load (40 and 160 N) and speed (0.25 and 1.0 m/s) - each varying by a factor of four were used; thus the range of frictional heat generation was 16 to 1. The results of this study were rather surprising and changed our thinking on the mechanism(s) by which monomers can act to reduce ceramic wear. ...

  • Friction, Wear, and Lubrication of Hydrogels as Synthetic Articular Cartilage
    1998
    Co-Authors: Mark E. Freeman, Michael J. Furey, Brian J. Love, Jeanne M. Hampton
    Abstract:

    In recent years, synthetic hydrogels have been studied not only as possible replacements for articular cartilage but also as platforms for growing cartilage in a damaged joint. In the present study, the tribological behaviour of synthesized poly (2- hydroxyethyl) methacrylate (polyHEMA) hydrogels was investigated in a four-factor, two-level Designed Experiment using a device developed for biotribology research. The contact geometry consisted of a 6mm diameter stainless steel ball on flat polyHEMA disks. The variables in the Designed Experiment were (a) applied load, (b) lubrication, (c) hydrogel cross-link density and (d) degree of hydrogel hydration. Linear oscillating sliding contact tests were conducted for 30 minutes for each test. The results showed several significant main effects and first-order interactions. Increasing the applied load from 6 to 20N increased average hydrogel wear by 125%. Increased cross-link density reduced wear by over 60%. And increased hydration resulted in an increase of 130% in wear. The coefficient of friction ranged from a low value of 0.02 to a high of 1.7 while linear wear varied by a factor of over 60. Interactions between (a) hydration and lubrication and (b) hydration and cross-linking on wear were highly significant. The single most important finding from this study was that, as expected, there was no correlation between friction - which is commonly reported in the literature on hydrogels- and wear. Most of the data fell into two groups, namely low wear-low friction and high wear-low friction. These results may be useful in the tribological design of hydrogels for both low wear and low friction.