Optimum Parameter Design of Microbubble Drag Reduction in a Turbulent Flow by the Taguchi Method Combined With Artificial Neural Networks

2013 ◽  
Vol 135 (11) ◽  
Author(s):  
Kwan Ouyang ◽  
Sheng-Ju Wu ◽  
Huang-Hsin Huang
Keyword(s):  
Neural Networks ◽  
Artificial Neural Networks ◽  
Taguchi Method ◽  
Turbulent Flow ◽  
Drag Reduction ◽  
Bubble Size ◽  
Optimum Parameter ◽  
Air Injection ◽  
Parameter Design ◽  
Control Factors

This study attempts to optimize parameters for the microbubble drag reduction in a turbulent flow based on experimental measurements. Five parameters were investigated: three are control factors (the area of air injection, bubble size, and the rate of air injection) and two are indicative factors (flow speed and the measured position of local shear stress). An integrated approach of combining the Taguchi method with artificial neural networks (ANN) is proposed, implementing the optimum parameter design in this study. Based on the experimental results, analysis of variance concluded that, among the control factors, the rate of air injection has the greatest influence on microbubble drag reduction, while bubble size has the least. The investigation of drag reduction characteristics revealed that the drag ratio decreases with an increasing rate of air injection. However, if the rate of air supplied exceeds a certain value, the efficiency of drag reduction can drop. In the case of optimum parameter design, a 21% drag reduction and an S/N ratio of 1.976 dB were obtained.

Optimizing Experimental Variables to Enhance the Biodegradability of Polylactic Acid

2014 ◽  
Vol 472 ◽  
pp. 815-819
Author(s):  
Shu Wen Wang ◽  
Te Li Su
Keyword(s):  
Carbon Dioxide ◽  
Taguchi Method ◽  
Polylactic Acid ◽  
Renewable Resources ◽  
Raw Materials ◽  
Parameter Design ◽  
Hydrolysis Rate ◽  
Biodegradable Materials ◽  
Optimal Conditions ◽  
Control Factors

Polylactic acid (PLA), the biodegradable materials, mainly using biobase as raw materials, is the biodegradable polyester manufactured with fermentation and chemical synthesis, or polymerization of monomers from petrochemical products. The polymer usually made with the renewable resources, such as microorganism, plants and animals, will be decomposed into water and carbon dioxide if the natural landfill or compost environment has sufficient moisture, temperature, oxygen and suitable microorganism. Therefore, this paper aims to improve the hydrolysis rate of the PLA during the whole decomposition process and to increase the decomposition rate of PLA in the natural environment. In this paper, Taguchi method was used for the parameter design of PLA hydrolysis and focusing on choosing the conditions that would affect PLA hydrolysis as control factors, for example, temperature, bacteria, ventilation degree and nutrient. Meanwhile, the experiment was conducted with L8 orthogonal array and analysis of variance to find out the significant factor and the optimal conditions of PLA hydrolysis. We found the temperature and bacteria are signify factors by the variance. Lastly, confirmation experiments verified the reproducibility of this experiment. Confirmed by the experiments, results showed that the obtained SN ratios were greater than the rate of eight PLA hydrolysis experiments and this means the experiment is reliable.

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