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Now showing items 1 - 2 of 2

  • Assessment of volatile organic pollution control technologies in automotive industry

    Chonglei Ren;Xuefeng Liu;Jiabao Ren;Lei Wang;China Automotive Technology and Research Center;  

    Volatile organic compounds(VOCs) are one of the main factors causing air pollution in China. In the automotive industry, spraying, drying, and other processes will produce a large amount of VOCs pollution. How to select suitable treatment techniques is the major problem for VOCs control. In this paper, a treatment technology evaluation index system was constructed based on the characteristics of VOCs emission in automobile manufacturing.Using the Analytic Hierarchy Process(AHP) model to comprehensively evaluate VOCs governance technologies in the automotive industry. The results showed that the priority of the six VOCs treatment techniques is as follows: runner + RTO > activated carbon + TO >activated carbon + RTO > runner + RCO > activated carbon + CO > activated carbon + RCO.
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  • Determining color difference thresholds in denture base acrylic resin

    Jiabao Ren   Hong Lin   Qingmei Huang   Gang Zheng  

    Abstract Statement of problem In restorative prostheses, color is important, but the choice of color difference formula used to quantify color change in acrylic resins is not straightforward. Purpose The purpose of this in vitro study was to choose a color difference formula that best represented differences between the calculated color and the observed imperceptible to unacceptable color and to determine the corresponding perceptibility and acceptability threshold of color stability for denture base acrylic resins. Material and methods A total of 291 acrylic resin denture base plates were fabricated and subjected to radiation tests from zero to 42 hours in accordance with ISO 7491:2000. Color was measured with a portable spectrophotometer, and color differences were calculated with 3 International Commission on Illumination (CIE) formulas: CIELab, CMC(1:1), and CIEDE2000. Thirty-four observers with no deficiencies in color perception participated in psychophysical perceptibility and acceptability assessments under controlled conditions in vitro. These 2 types of assessments were regressed to each observer by each formula to generate receiver operator characteristic (ROC) curves. Areas under the curves (AUCs) were then calculated and analyzed to exclude observers with poor color discrimination. AUCs were subjected to 1-way ANOVA (α=.05) to deter the statistical significance of discriminability among the 3 formulas in terms of perceptibility and acceptability judgments. Student-Newman-Keuls tests (α=.05) were used for post hoc comparison. Results CMC(1:1) and CIEDE2000 formulas performed better for imperceptible to unacceptable color differences, with corresponding CMC(1:1) and CIEDE2000 values for perceptibility of 2.52 and 1.72, respectively, and acceptability thresholds of 6.21 and 4.08, respectively. Conclusions Formulas CMC(1:1) and CIEDE2000 possess higher discriminability than that of CIELab in the assessment of perceptible color difference threshold of denture base acrylic resin. A statistically significant difference exists between perceptibility and acceptability thresholds for denture base acrylic resin.
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