Full Factorial Method Research Articles

A systematic erosion–corrosion study of two stainless steels in marine conditions via experimental design

Erosion–corrosion performance of two stainless steels (UNS S32760 and UNS S31603) for marine applications has been assessed under liquid–solid impingement conditions in 3.5% NaCl. The total material loss rate and the components of mechanical erosion, electrochemical corrosion and their synergistic interactions have been determined under various conditions. The major environmental parameters considered are solid loading, flow velocity and fluid temperature. For the two stainless steels, a quantitative analysis of the damage showed mechanical erosion to be the dominant process under erosion–corrosion over the range of conditions considered. A full two-level factorial experimental design method was applied to study the individual effects of each parameter as well as their interactive contributions to the overall material degradation. The analysis shows that the interactions between environmental factors all accelerate mass loss during the erosion–corrosion process and the interactive effect between velocity and sand loading is the greatest. Fluid temperature has the smallest effect of the three parameters. Some guidelines to assist in material selection for erosion–corrosion and progress towards prediction of erosion–corrosion in marine applications are discussed in this paper.

Shape optimization of inclined ribs as heat transfer augmentation device

This work presents numerical optimization techniques for the design of a rectangular channel with inclined ribs to enhance turbulent heat transfer. The response surface method with Reynolds-averaged Navier-Stokes analysis is used for optimization. Shear stress transport turbulence model is used as a turbulence closure. Computational results for local heat transfer rate show a reasonable agreement with the experimental data. Width-to-rib height ratio and attack angle of the rib are chosen as design variables. The objective function is defined as a linear combination of heat-transfer and friction-loss related terms with the weighting factor. Full-factorial experimental design method is used to determine the data points. Optimum shapes of the channel have been obtained in a range of the weighting factor.

난류열전달 증진을 위한 딤플형상의 최적설계

This study presents a numerical procedure to optimize the shape of dimple surface to enhance turbulent heat transfer in a rectangular channel. The response surface based optimization method is used as an optimization technique with Reynolds-averaged Navier-Stokes analysis of fluid flow and heat transfer with shear stress transport (SST) turbulence model. The dimple depth-to-dimple print diameter ratio, channel height-to-dimple print diameter ratio, and dimple print diameter-to-pitch ratio are chosen as design variables. The objective function is defined as a linear combination of heat transfer related term and friction loss related term with a weighting factor. Full factorial method is used to determine the training points as a mean of design of experiment. The optimum shape shows remarkable performance in comparison with a reference shape.

Experimental observation of tool wear, cutting forces and chip morphology in face milling of cobalt based super-alloy with physical vapour deposition coated and uncoated tool

Cobalt base superalloys are used extensively in applications requiring good wear, corrosion and heat resistance. The main goal of this study is to examine the effect of machining conditions (cutting speed, feed rate and depth of cut) on tool wear, chip morphology and cutting forces in symmetric face milling of cobalt base superalloy with physical vapour deposition coated and uncoated inserts. with the aim of achieving to achieve this goal, 90 milling experiments were carried out with different cutting speeds, feed rate and depth of cut under dry cutting conditions. The settings of machining parameters were determined by using general full factorial design method. Chip morphology, cutting forces and tool wear were compared by using PVD coated and uncoated hard metal inserts which are obtained dependent on feed rate, cutting speed and cutting depth. The cutting forces increase as the feed rate and depth of the cut increases, but cutting speeds’ effect on cutting forces has not been observed for symmetric face milling.

Process improvement approach to the saponification reaction by using statistical experimental design

The purpose of this study was to determine the effective operating parameters and the optimum operating conditions of a batch saponification process in the frame of the process improvement. Full two-level factorial and face-centered central composite (FCCC) statistical experimental design methods were used successively. Examined parameters were the main and interaction effects of temperature, agitation rate, initial sodium hydroxide (NaOH) and ethyl acetate (EtOAc, CH 3COOC 2H 5) concentrations. Selected process response was the fractional conversion rate of NaOH ( X A). Temperature and agitation rate were found to have no effect on the response at the 10% selected significance level ( α = 0.1). The dependence of response on the NaOH and EtOAc concentrations was illustrated by a linear second-order polynomial model. Examination of the residuals served as a diagnostic check of the model and it was found that the model was good enough to fit the experimental data. Optimum operating conditions at which maximum X A was obtained about 100% were found to be 0.01 mol L −1 NaOH and 0.1 mol L −1 EtOAc by applying response surface method (RSM). With the use of residual analysis and statistical techniques, more reliable and proper results were obtained at the process improvement stage of the saponification process.

Net analyte signal-based simultaneous determination of antazoline and naphazoline using wavelength region selection by experimental design-neural networks

Net analyte signal (NAS)-based multivariate calibration methods were employed for simultaneous determination of anthazoline and naphazoline. The NAS vectors calculated from the absorbance data of the drugs mixture were used as input for classical least squares (CLS), principal component and partial least squares regression PCR and PLS methods. A wavelength selection strategy was used to find the best wavelength region for each drug separately. As a new procedure, we proposed an experimental design-neural network strategy for wavelength region optimization. By use of a full factorial design method, some different wavelength regions were selected by taking into account different spectral parameters including the starting wavelength, the ending wavelength and the wavelength interval. The performance of all the multivariate calibration methods, in all selected wavelength regions for both drugs, was evaluated by calculating a fitness function based on the root mean square error of calibration and validation. A three-layered feed-forward artificial neural network (ANN) model with back-propagation learning algorithm was employed to model the nonlinear relationship between the spectral parameters and fitness of each regression method. From the resulted ANN models, the spectral regions in which lowest fitness could be obtained were chosen. Comparison of the results revealed that the net NAS-PLS resulted in lower prediction error than the other models. The proposed NAS-based calibration method was successfully applied to the simultaneous analyses of anthazoline and naphazoline in a commercial eye drop sample.

반응면기법을 이용한 침전조의 형상최적설계

A numerical procedure for optimizing the shape of three-dimensional sedimentation tank is presented to maximize its sedimentation efficiency. The response surface based optimization is used as an optimization technique with Reynolds-averaged Navier-Stokes analysis for multi-phase flow. Standard k-ε model is used as a turbulence closure. Three design variables such as, tank height to center feed wall diameter ratio, blockage ratio of center feed wall and angle of distributor are chosen as design variables. Sedimentation efficiency is defined as an objective function. Full-factorial method is used to determine the training points as a means of design of experiment. Sensitivity of each design variable on the objective function has been evaluated. And, optimal values of the design variables have been obtained.

Performance optimization of hypervelocity launcher system using experimental data

This study presents the performance optimization of hypervelocity launcher system by using the experimentall data. During the optimization, the RSM (Response Surface Method) is adopted to find the operating parameters that could maximize the projectile speed. To construct a reliable response surface model, 3 full factorial method is used with the selected design variables, such as piston mass and 2 driver fill pressure. Nine test data could successfully construct the reasonable response surface, which used to yield the optimal operational conditions of the system using the genetic algorithm. The optimization results are confirmed by the experimental test with a good accuracy. Thus, the optimization can improve the performance of the facility.

Optimization by full factorial design of the emulsifying properties of ethanol insoluble fraction from rapeseed lecithin

AbstractRapeseed lecithin ethanol insoluble fraction (LEIF), was acetylated and optimum conditions for improving LEIF emulsifying property were determined. The effects of reaction time, pyridine amount and temperature on phosphatidyl ethanolamine conversion degree (PECD) and emulsion stability index (ESI) have been described in the form of regression equations. A full factorial design method was used. Regression equations for the maximum value of response functions and computation results were calculated and compared with those obtained in control experiments. Acetylation of rapeseed LEIF with the use of calculated optimal parameters led to 35% and 60% increments in PECD and ESI, respectively.

A statistical approach to the experimental design of the sulfuric acid leaching of gold-copper ore

The high grade of copper in the Igarape Bahia (Brazil) gold-copper ore prevents the direct application of the classic cyanidation process. Copper oxides and sulfides react with cyanides in solution, causing a high consumption of leach reagent and thereby raising processing costs and decreasing recovery of gold. Studies have showm that a feasible route for this ore would be a pretreatment for copper minerals removal prior to the cyanidation stage. The goal of this experimental work was to study the experimental conditions required for copper removal from Igarape Bahia gold-copper ore by sulfuric acid leaching by applying a statistical approach to the experimental design. By using the Plackett Burman method, it was possible to select the variables that had the largest influence on the percentage of copper extracted at the sulfuric acid leaching stage. These were temperature of leach solution, stirring speed, concentration of sulfuric acid in the leach solution and particle size of the ore. The influence of the individual effects of these variables and their interactions on the experimental response were analyzed by applying the replicated full factorial design method. Finally, the selected variables were optimized by the ascending path statistical method, which determined the best experimental conditions for leaching to achieve the highest percentage of copper extracted. Using the optimized conditions, the best leaching results showed a copper extraction of 75.5%.

A study of antifungal antibiotic production by Streptomyces chattanoogensis MTCC 3423 using full factorial design.

To determine the correct levels of the three process parameters identified as the most important for maximum production of antifungal antibiotic by the newly isolated strain of Streptomyces chattanoogensis MTCC 3423. The three independent variables, namely concentration of carbon source (glucose), nitrogen source (soybean meal) and temperature of incubation, were found to be the most important for production of antifungal antibiotic by the isolate Streptomyces chattanoogensis MTCC 3423 from a one-factor-at-a-time study. These variables were varied at three levels in 27 experiments using full factorial design. The results were analysed using statistical software for social sciences, SPSS (version 6.0). They indicated that the optimum combination of the three factors for maximum yield (263.63 U) of the antibiotic was concentration of carbon source (glucose) 5%, concentration of nitrogen source (soybean meal) 1% and temperature of incubation 30 degrees C. The antifungal antibiotic activity of the isolate was estimated against Candida albicans by bioassay. The S. chattanoogensis MTCC 3423 isolate was found to yield a maximum of 263.63 IU Nystatin ml-1 medium by manipulating the three process parameters of glucose, soybean meal and temperature of incubation. As process optimization by single-dimensional search is laborious and time consuming, and does not guarantee determination of optimal conditions, an attempt was made to use a more practical full factorial method. Even though antifungal antibiotic treatment and resistance data have been analysed using SPSS software, there are no reports on antifungal antibiotic production using SPSS.

Production of S-adenosyl- L-methionine by a mutant strain of Kluyveromyces lactis

S-Adenosyl-l-methionine (AdoMet) was produced by a mutant strain Kluyveromyces lactis AM-65 grown on whey. A full factorial design method of three factors – (NH4)2SO4 (factor x1), corn steep liquor (factor x2) and l-methionine (factor x3) on three levels – was used to determine the optimal medium conditions for the production of AdoMet. A time course shake-flask experiment in optimal whey medium (x1=3.1 g l−1, x2=12.7 g l−1, x3=4.6 g l−1) was also carried out and the results confirmed the results of the factorial design and subsequent quadratic modelling and optimization of AdoMet production which reached 90 mg g−1 cell dry wt.

Full factorial design to study fermentative production of inulinase using inulin from kuth ( Saussurea lappa) root power by Aspergillus niger van Teighem UV11 mutant

Kuth ( Saussurea lappa) as a source of inulin for fermentative production of inulinase has been tested for the first time. Preliminary shake-flask experiments in the fermentative production of inulinase using kuth as the carbon source, in combination with different organic and inorganic nitrogen sources, gave the highest yield of inulinase activity (302 Uml −1) with corn steep liquor as the nitrogen source. The full factorial design using 3 3 = 27 experiments with varying combinations of kuth and CSL concentrations and agitation rates was tried. The results obtained were analysed using SPSS/PC+ (Version 4·0). This is the first use of a full factorial method for optimising fermentative production of inulinase.

Computerized study of interactions among factors and their optimization through response surface methodology for the production of tannin acyl hydrolase by Aspergillus niger PKL 104 under solid state fermentation

Optimization of five parameters (initial moisture, initial pH, incubation temperature, inoculum ratio and fermentation period), as per central composite rotable design falling under the response surface methodology, was attempted in a total of 32 experimental sets, after fitting the experimental data to the polynomial model of a suitable degree, for tannin acyl hydrolase production by Aspergillus niger PKL 104 in solid state fermentation system. The quantitative relation between the enzyme production and different levels of these factors was exploited to work out optimized levels of these parameters by flexible polyhedron search method and confirmed by further experimentations. The best set required 5% inoculum, 6.5 initial pH, 28 °C fermentation temperature, 62% initial moisture and 3 days fermentation time. The optima were worked out under the additional constraints for temperature (∼ 30 °C) and fermentation time (not more than 3 days) which are essential from industrial conditions and to pre-empt contamination, respectively. The best set resulted in 1.34 times more enzyme production than that was obtained before this optimization. Three dimensional plots, relating the enzyme production to paired factors (when other three factors were kept at their optimal levels) best described the behaviour of solid state fermentation system and the interactions between factors under optimized conditions. The model showed that the enzyme production was affected by all the five factors studied. The initial pH exhibited a positive interaction with moisture but no interaction with other factors. Initial moisture level and inoculum ratio showed negative interaction in contrast to positive interaction between inoculum ratio and fermentation period. It is thus apparent that the response surface methodology not only gives valuable information on interactions between the factors but also leads to identification of feasible optimum values of the studied factors, in addition to 99% (or more) savings on resources as compared to a full factorial traditional optimization method. Response surface methods have not been used earlier for optimizing parameters in solid state fermentation system.

Optimal conditions for fractionation of rapeseed lecithin with alcohols

Deoiled rapeseed lecithin was fractionated with ethanol, and optimum conditions have been determined to improve purified lecithin yield and phosphatidylcholine (PC) enrichment. The effect of extraction time, solvent volume, ethanol concentration and temperature on the yield and the PC enrichment have been described in the form of regression equations. A full factorial experiment method and a second‐order orthogonal design were used in the study. The regression equations were calculated for the maximum value of the response functions optimized by an electronic data processing method, and the results (yield and PC enrichment calculated from regression equations) were compared with those obtained in control experiments. The use of calculated optimal parameters in the fractionation process led to 81–96% and 58% increments in yield and PC enrichment, respectively.