Multiple Response Optimization Research Articles

Multiple Response Optimization of Dimensional Accuracy of Nimonic Alloy Miniature Gear Machined on Wire Edm Using Entropy Topsis Andpareto Anova

The purpose of this research is to obtain the optimum cutting parameters to achieve the dimensional accuracy of Nimonic alloy miniature gear manufactured using Wire EDM. The cutting parameters investigated in this study are current, pulse on time (PON), pulse off time (POFF), wire tension (WT) and dielectric fluids. Ethylene glycol, nanopowder of alumina and oxygen are mixed to demineralized water to prepare novel dielectric fluids. Deviation in inner diameter, deviation in outer diameter, deviation in land and deviation in tooth width are considered to check the dimensional accuracy. Taguchi L16 is employed for experimental design and multiple response optimization is performed using Entropy TOPSIS and Pareto ANOVA. Results indicate that pulse on time is the most notable parameter for good dimensional accuracy followed by dielectric fluid, current, pulse off time and wire tension. Ethylene glycol mixed demineralized water is preferred for low dimensional deviation. The optimum WEDM parameters are pulse on time at 20 μs, Ethylene glycol mixed demineralized water dielectric fluid, current at 3 A, pulse off time at 4 μs, and wire tension at 18 N.

Studies on effective interaction parameters in extraction of Pr and Nd using Aliquat 336 from NdFeB magnet-leaching solution: Multiple response optimizations by desirability function

Praseodymium (Pr) and neodymium (Nd) are considered as the light rare earth elements that have received significant attention due to their many applications. The extraction of Pr and Nd from NdFeB magnet-leaching solution using nitrate form of Aliquat 336 was investigated to show the interactive effects in solvent extraction process. The response surface methodology (RSM) based on central composite design (CCD) was used for experimental modeling and optimization. The studied variables included Aliquat 336 concentration of 0.30 to 0.85 mol/L, organic to aqueous phase ratio (O/A) of 1 to 3, pH of 2.0 to 5.0, and nitrate concentration of 2.2 to 5.6 mol/L. According to the results, it was found that there were effective inter-parameter interactions in which justified different feedbacks of the system under different operational conditions. Furthermore, two separated optimizations (i.e., co-extraction efficiency and operational selectivity) were also performed by desirability function method. In the optimization of co-extraction efficiency, the Pr and Nd extraction efficiencies were obtained 99.7% and 93.9%, respectively, while, the above responses in the optimization of operational selectivity were obtained 74.8% and 61.2%, respectively. The values of separation factor were determined same (i.e., 2.1) for both the optimizations. Meanwhile, it was found the stripping of Pr and Nd ions from the loaded organic phase can be effectively conducted under the 0.02 mol/L hydrochloric acid solution within a contact time of 5 min conditions. Also, the FT-IR analysis confirms the transformation of the metal-nitrate complex into the organic phase.

Synergistic effects of graphene nanoplatelets and NH2-MWCNTs on cryogenic mechanical properties of epoxy nanocomposites

Fracture toughness (FT) and Tensile strength (TS) of epoxy reinforced amine-functionalized MWCNTs (A-MWCNTs)/graphene nanoparticles (GNPs) composites are investigated in cryogenic environment. Simplex centroid design is employed to decide the composition of samples. FT and TS of epoxy improved significantly on incorporating 0.25 wt% of either A-MWCNTs or GNPs, but increasing the content of nanofillers beyond 0.25% showed lower enhancement in the mechanical properties. Simultaneous addition of nanofillers in epoxy demonstrated synergistic effects, with the maximum FT (121%) and TS (132%) noticed for hybrid composite containing 0.17% of each nanofiller. It is attributed to the presence of well interconnected 3D network between nanofillers and epoxy, which yield uniform dispersion of nanofillers and strong adhesion between nanofillers and epoxy. Regression analysis suggested quadratic models for estimating FT and TS. Multiple response optimization yields the maximum FT (0.907 MPm1/2) and TS (20.6 MPa) for hybrid composite containing 99.67% epoxy, 0.17% A-MWCNTS and 0.16% GNPs.

Intensification of mixing-pumping process in a novel active micropump-mixer with maximum efficiency and minimum energy cost: A LBM-RSM approach

In the present paper, a double multiple-relaxation-time lattice Boltzmann simulation and response surface optimization are performed to optimize the performance of a novel active micropump-mixer at high-Peclet number flows. The micropump-mixer is comprised of rotationally oscillating rectangular stirrer and two identical square rotors. Effects of three important non-dimensional parameters of the stirrer, including its diameter (DS), maximum velocity (US), and amplitude (K) are investigated on the mean mixing efficiency (εout), time-averaged of the instantaneous dimensionless averaged velocity (Uave), mixing energy cost (mec) and pumping energy cost (pec). All calculations are carried out for the non-dimensional US and K in the range of 0.1-1, and for DS in the range of 0.5−0.9, at fixed Reynolds and Peclet numbers of Re=1 and Pe=10000. Results indicated that εout increases with DS, and especially with K, while it displays a non-monotonic behavior with US. Furthermore, Uave and mec decrease with increasing DS and K. However, Uave is not influenced by US variations, but mec shows a decrease-increase trend with increasing US. The pec increases with increasing of all three parameters. Finally, optimization results indicated that non-dimensional values of 0.5, 0.702 and 1 respectively for Ds, Us and K are optimum values for multiple-response optimization.

Biorelevant Dissolution Method Development for Dutasteride and Tamsulosin Hydrochloride Modified Release Capsule Simulating Post-prandial Condition

Objectives: This research work is aimed to develop bio relevant dissolution method by simulating human gastrointestinal condition at post-prandial state. The quality control dissolution procedure for modified release product using simple buffers of specific pH is not adequate for prediction of in vivo performance. Methods: Percentage of drug absorbed is derived by deconvolution of drug plasma concentration at post-prandial condition using Wagner-Nelson deconvolution method. Quality control dissolution test is performed using office of generic drugs recommended dissolution method. Bio relevant dissolution method is developed using USP Apparatus 3 (reciprocating cylinder), with quality by design approach. A full factorial design of experiment study is performed for optimization of dips per minute and media volume. Separate dissolution method is developed for tamsulosin and dutasteride, since the formulation design and release profile are different for both drugs. Results: The dissolution profile obtained using quality control procedure is observed faster in comparison to percentage of drug absorbed. The bio relevant dissolution method developed for tamsulosin part is, 250ml of Fed state simulated change over dissolution media with 15DPM, based on desirability factor 0.8767 and for dutasteride part is, 100ml of pH 6.5 Fed state simulated intestinal fluid with 20DPM, based on desirability factor 0.5836, achieved from multiple response optimizations. The dissolution results are comparable to percentage of drug absorbed. The regression co-efficient (R2) value of 0.998 and 0.982 demonstrates a very good in vitro/in vivo correlation under post-prandial condition for tamsulosin and dutasteride respectively. Conclusion: The developed method shall be used as a predictive in vitro tool for evaluation of in vivo performance under post-prandial condition.

Technical feasibility of hard coating by flux-cored arc welding on a sugarcane cutting knife

The sugarcane agroindustry covers 10,184,340 ha of arable land in Brazil. Harvesting this crop requires increasingly sophisticated equipment and sugarcane uses a basal cutting system with knives. These knives deteriorate rapidly due to abrasion with silica in the soil, which makes hard coating feasible for these components. Hard coatings generally involve the addition of chromium to increase the service life of agricultural machinery parts. The need to reduce the levels of chemical elements harmful to humans and animals in agricultural soils requires a study of alternatives to substitute chromium in hard metal alloys. Based on that, this work is aimed to investigate an alternative this respect; the present study proposes a change in coating from tungsten carbide paste (WC), which contains chromium, to a titanium carbide–based coating without chromium. To this end, FCAW (flux-cored arc welding) welding process was used, with self-shielding flux-cored wire containing alloy elements that increase resistance to abrasion, thereby extending the service life of the component. Simultaneous optimization of multiple responses was used to determine proposed welding parameters. For validation purposes, abrasion wear tests with a rubber wheel and dry sand were conducted to compare resistance to abrasion between the proposed material and that used in commercial knives. Results from accelerated wear tests showed FCAW higher performance (around 48%) compared to the WC coating. This demonstrates technical feasibility of the proposed hard metal deposition process using FCAW welding aimed to increase the service life of basal cutting knives without chromium.

Optimization of Reaming Process Parameters for Alloy Grey Cast Iron HT250 Using Grey Relational Analysis

Reaming is one of the finishing processes that has been widely applied in automotive industry. Reaming parameters were evaluated and optimized based on multiple performance characteristics including tool wear and hole quality. Taguchi’s L16, 4-level, 2-factor orthogonal array (OA) was conducted for this test. It was shown that crater wear and flank wear were seen on the tool surface. Furthermore, the crater wear was also of major significance. Hole quality was discovered to be mostly dependent upon cutting speed and feed rate. TiAlN coated carbide reamer shows the best performance with respect to the tool wear as well as hole quality. Grey relational analysis used as a multiple-response optimization technique found that feed rate was the more influential parameter than cutting speed. The goal of the experimental results was to obtain both minimum diametral error and the value of surface roughness by adopting the optimal combination of the reaming parameters.

Experimental Investigation and Statistical Evaluation of Optimized Cutting Process Parameters and Cutting Conditions to Minimize Cutting Forces and Shape Deviations in Al6026-T9.

Precise, economical and sustainable cutting operations are highly desirable in the advanced manufacturing environment. For this aim, the present study investigated the influence of cutting parameters (i.e., the cutting speed (c), feed rate (f), depth of cut (d) and positive rake angle (p)) and sustainable cutting conditions (dry and minimum quantity lubricant (MQL)) on cutting forces (i.e., feed force (Ff), tangential forces (Ft), radial force (Fr) and resultant cutting forces (Fc) and shape deviations (i.e., circularity and cylindricity) of a 6026-T9 aluminum alloy. The type of lubricant and insert used are virgin olive oil and uncoated tungsten carbide tool. Turning experiments were performed on a TAKISAWA TC-1 CNC lathe machine and cutting forces were measured with the help of a Kistler 9257B dynamometer. Shape deviations were evaluated by means of a Tesa Micro-Hite 3D DCC 474 coordinate measuring machine (CMM). Experimental runs were planned based on Taguchi mixture orthogonal array design L16. Analysis of variance (ANOVA) was performed to study the statistical significance of cutting parameters. Taguchi based signal to noise (S/N) ratios are applied for optimization of single response, while for optimization of multiple responses Taguchi based signal to noise (S/N) ratios coupled with multi-objective optimization on the basis of ratio analysis (MOORA) and criteria importance through inter-criteria correlation (CRITIC) are employed. ANOVA results revealed that feed rate, followed by a depth of cut, are the most influencing and contributing factors for all components of cutting forces (Ff, Ft, Fr, and Fc) and shape deviations (circularity and cylindricity). The optimized cutting parameters obtained for multi responses are c = 600 m/min, f = 0.1 mm/rev, d = 1 mm and p = 25°, while for cutting conditions, MQL is optimal.

Development and evaluation of edible films based on cassava starch, whey protein, and bees wax

Films and edible coatings based on biopolymers have been developed as a packaging, which can be obtained from biodegradable materials and have properties similar to common plastics. These edible materials have many applications in the food industry, preventing mass transfer between the product and the surrounding environment. The objective of this study was to develop and evaluate the physicochemical and mechanical properties of edible films based on cassava starch (CS), whey protein (WP), and beeswax (BW). Response surface methodology has been used and the experiments were carried out based on face-centred composite design. On the other hand, three CS-based controls were formulated to evaluate the effect of the inclusion of WP and BW. The optimization of multiple responses established the optimal formulation: CS (3.17 %), WP (1.30 %), BW (0.50 %), presenting the following response variables: tensile stress (1.92 MPa), elongation (40.4 %), Young's modulus (42.1 MPa), water vapor permeability 1.79 × 10−11 (g mm/s cm2 Pa), swelling capacity (300.3 %), thickness (0.128 mm), moisture content (6.74 %), and colour: lightness (89.9), chromaticity a∗ (-1.8), chromaticity b∗ (7.7), saturation (9.9), tone (101.1°), and yellowness index (17.7). The selection and evaluation of this optimal formulation are essential because it is the material that shows the best possible mechanical and physicochemical properties using the studied components. The results, especially its good mechanical properties and low permeability to water vapour, would allow its application as a coating for fruits, vegetables, among others, effectively delaying its weight loss due to dehydration.

Machinability study of aircraft series aluminium alloys 7075-T6 and 7050-T7451

The aluminium alloy 7050-T7451 is generally considered as the principal choice in aeronautical applications demanding adequate strength, stress corrosion cracking resistance, and toughness. Surprisingly, despite extensive research works on machining and machinability of aluminium alloys, including aluminium alloy 7075-T6, limited information was found on machining and machinability evaluation of 7050-T7451, which belongs to a similar family as 7075-T6. To remedy the lack of knowledge determined, dry ball-end milling operations were performed with coated end milling tools on both materials. Experimental characterization and cutting force measurements were performed to measure/evaluate the cutting forces, burr formation morphology, insert performance (wear/breakage), and surface quality attributes. According to experimental studies, 7050-T7451 was found more machinable than 7075-T6. Less burr formation and better surface quality were observed on 7075-T6. Machining attributes are influenced by different experimental factors. However, other machinability attributes, including residual stress, vibration modes, as well as particle emission, must be studied under various lubrication modes and machining operations in subsequent studies. This also recalls further studies on simultaneous multiple response optimization.

Chemical-assisted ultrasonic drilling of Polycarbonate bullet proof UL-752 glass and optimisation of process parameter by Taguchi, GRA and RSM approach

ABSTRACT Purpose Polycarbonate bullet proof (UL-752) glass is highly demanded material in automobile, aerospace and space industries. It is also used in security chambers or buildings, because of its unique properties such as; impact bare capacity, hardness, excellent transparency, higher mechanical strength, good dimensional stability etc. Objective of this research investigation is focused at studying the impact of different input parameters (concentration, abrasive, power rating, grit size, HF acid concentration and tool material) on output responses (material removal rate, tool wear rate and surface roughness) in ultrasonic drilling of polycarbonate bullet proof (UL-752) glass. Design/methodology/approach The experiments have been performed by using Taguchi’s L27 orthogonal array and grey relation analysis has been used for the optimization of multiple responses. To find out the significant factors, analysis of variance is further employed. Abbreviation CUSM: Chemical assisted ultrasonic machining; PBPG: Polycarbonate bullet proof glassHF: Hydrofluoric; MRR: Material removal rate; TWR: Tool wear rate; SR: Surface roughness; DOE: Design of experiment; DOF: Degree of freedom; OA: Orthogonal array; GRA: Grey relation analysis; GRC: Grey relation coefficient; GRG: Grey relation grade; S/N: Signal to noise ratio; ANOVA: Analysis of variance; RSM: Response surface analysis; SEM: Scanning electron microscope

Optimización del proceso de cocción de quinua utilizando el diseño 3k y la función de deseabilidad: Grado de gelatinización, índice de absorción de agua, índice de solubilidad y desprendimiento de cotiledones

Optimization of the steam quinoa cooking process was carried out, using a response surface design (RSM) 3-level: 3k factorial, and the multiple response optimization methodology of the desirability function (Dx) was used to find the optimal region, which are improved tools to optimize the variables of a process, evaluate the maximization of the water absorption index (WAI), water solubility index (WSI), degree of gelatinization (GE) and the minimization of cotyledon detachment (DC) of quinoa (Chenopodium quinoa Willd). The equipment used was a vertical cook with a steam generator, the study cooking variables, the steam pressure, and the cooking time. The optimal process values were: Pressure 1.5 kgf.cm-2 and time 8 minutes for the best characteristics of cooked quinoa WSI of 26.411%, WAI of 7.960 (g.g-1), GE of 89.245% and CD of 18.40%, the value of the desirability function as an indicator of multiple responses was 0.798. Knowledge of these characteristics can be a valuable complement in the cooking process and thus contribute to improving the quality of cooked cereals.

Improvement of lignocellulosic biomass conversion by optimization of fungal ligninolytic enzyme activity and molasses stillage supplementation

Fungal treatment of lignocellulose is an ecologically and economically acceptable method. However, it needs improvement to increase the hydrolysis rate. A novel combination of multiple response optimization of ligninolytic activity of Trametes hirsuta F13 and supplementation of the lignocellulosic substrate (beechwood sawdust) with sugar beet molasses stillage was employed to improve and manage the desired type of fungal ligninolytic activity leading to a significant enhancement of biomass saccharification. Obtained optimal cultivation conditions (molasses stillage concentration, 13%; substrate moisture, 63%; and temperature, 25 °C) provided the desired combination of laccase and manganese-dependent peroxidase activity, and maintained the activities longer and at higher values (51.5 ± 3.5 U/L and 91 ± 4.24 U/L, respectively) than the conditions without molasses stillage (21.5 ± 2.12 U/L and 31.5 ± 4.9 U/L, respectively). Enzyme hydrolysis of the substrate treated for 7 days in the presence of molasses stillage released 20.54 ± 0.80 mg/mL fermentable sugars, and 63.58 ± 1.47 mg/mL from 18-days treated substrate, while sugar concentrations released from the substrates pretreated without the supplementation were 16.84 ± 0.30 mg/mL and 53.63 ± 2.16 mg/mL, respectively. The proposed new approach of the lignocellulose supplementation with sugar beet molasses stillage and manipulation and improvement of fungal ligninolytic activity proved to be a promising solution for the enhancement of lignocellulose bioconversion.

Rational design of process parameters for carbon-neutral and sulfur-free motor fuel production from second-generation biomass generated syngas

The carbon-neutral fuel produced from Fischer-Tropsch synthesis using H2/CO/CO2 mixture generated from gasification of second-generation biomass could be a replacement to the conventional crude-based fuel with an additional impressive feature of utilizing the greenhouse gas efficiently. The present study focuses upon multiple-response optimisation of process parameters in low-temperature Fischer-Tropsch reaction conditions with hydrogen deficient and carbon dioxide containing syngas feed reacted over a supported bimetallic catalyst developed and reported by the same group. Herein, we performed 28 experimental runs in a laboratory-scale high-pressure fixed-bed reactor for developing a quadratic model for identifying significant variables influencing process practicality. The developed regression models were statistically validated within a 95% confidence interval. The contribution of an individual, square and second-order interaction of process variables in the Fischer-Tropsch reaction performance are identified. A highest CO consumption rate of 13.9 mmol h−1 gcat−1 with minimum 6.8% CH4 selectivity and maximum 72.3% selectivity towards the C5+ hydrocarbons is achieved with a composite desirability of 0.94. These results are experimentally validated by performing confirmatory experiments at optimal process parameters. The distillation characteristics of liquid hydrocarbon product collected at the optimal conditions show similar T-50 cut with the commercially available refinery diesel fuel. The quality and quantity of the coke deposited on catalyst during a time-on-stream run were also evaluated and found to help this reaction.

Simultaneous Optimization of Acetaldehyde and DMS Concentrations for Better Sensory Quality of Beer Fermented on an Industrial Scale

The levels of selected volatile components that affected the sensory properties of a lager beer were optimized under high-gravity brewing conditions (15.5 °P) in an industrial plant. The influence of different pitching rates (6–10 million cells/mL), aeration levels (8–12 mg/L), times (4.5–13.5 h) of filling CCTs (cylindroconical tanks, 3850 hl), and fermentation temperatures (8.5–11.5 °C) on the contents of acetaldehyde, diacetyl, acetone, 2,3-pentanedion, dimethyl sulfide (DMS), and on the sensory properties of beer were investigated. Response surface methodology (RSM, Box–Behnken design) was used to research the possibilities for optimizing the concentration of selected volatile components and sensory properties of bottom-fermented lager beers. Statistical analyses of the results showed that the experimental factors had a significant influence (R-squared for the original model with no significant lack-of-fit) on some of the volatile components. Based on the Multiple Response Optimization analysis, the values of independent factors that ensured the highest beer sensory quality were the following: a pitching rate of 10 million cells per mL; a fermentation temperature of 11.5 °C; an aeration level of 12 mg/L; and a CCT filling time of 4.5 h. These results proved that RSM modelling can be successfully applied to optimize fermentation and lagering processes in an industrial plant to manufacture lagers of enhanced sensory quality.

Experimental investigations on high precision abrasive waterjet cutting of natural fibre reinforced nano clay filled green composites

The present investigation focused on abrasive waterjet cutting (AWJC) of natural fibre reinforced nano clay filled polyester composites with the objectives of maximizing material removal rate ( MRR) and minimizing the kerf taper ( KT) and surface roughness ( Ra). The influence of nano clay addition, traverse speed (TS), jet pressure (JP) and stand-off distance (SOD) on the AWJC characteristics of fabricated composite laminates are investigated. The natural fibre reinforced composite (NFRC) laminates are fabricated through hand lay-up technique through varying the wt% of nano clay fillers (0, 1 and 2). The AWJC experiments are planned and rigorous experiments were performed by adopting box-behnken design approach. The relative consequence of process variables on response features and quadratic regression models were assessed through analysis of variance (ANOVA). Further, multiple response optimization is carried out using statistical desirability technique to enhance the cut quality characteristics. The optimal AWJC parameters such as JP of 316.24 MPa, SOD of 2 mm and TS of 304.24 mm/min with 1.15 wt% of nano clay addition are determined. Microstructure of cut surface is examined to ascertain the morphological behaviour of AWJC surfaces with different processing conditions.

Identification of Optimal Process Parameter Settings Based on Manufacturing Performance for Fused Filament Fabrication of CFR-PEEK

Fused filament fabrication (FFF) has been proven to be an effective additive manufacturing technique for carbon fiber reinforced polyether–ether–ketone (CFR-PEEK) due to its practicality in use. However, the relationships between the process parameters and their trade-offs in manufacturing performance have not been extensively studied for CFR-PEEK although they are essential to identify the optimal parameter settings. This study therefore investigates the impact of critical FFF parameters (i.e., layer thickness, build orientation, and printing speed) on the manufacturing performance (i.e., printing time, dimensional accuracy, and material cost) of CFR-PEEK outputs. A full factorial design of the experiments is performed for each of the three sample designs to identify the optimal parameter combinations for each performance measure. In addition, multiple response optimization was used to derive optimal parameter settings for the overall performance. The results show that the optimal parameter settings depend on the performance measures regardless of the designs, and that the layer thickness plays a critical role in the performance trade-offs. In addition, lower layer thickness, horizontal orientation, and higher speed form the optimal settings to maximize the overall performance. The findings from this study indicate that FFF parameter settings for CFR-PEEK should be identified through multi-objective decision making that involves conflicts between the operational objectives for the parameter settings.

Volatile Esters and Fusel Alcohol Concentrations in Beer Optimized by Modulation of Main Fermentation Parameters in an Industrial Plant

Contents of selected volatile esters and fusel alcohols and their relation to the sensory quality of a bottom-fermented lager beer fermented under high-gravity conditions (15.5 °P) were analyzed using response surface methodology (RSM, Box–Behnken design). The influence of various pitching rates (6–10 mln cells/mL), aeration levels (8–12 mgO2/mL), times (4.5–13.5 h) of filling CCTs (cylindroconical fermentation tanks; 3850 hL), and fermentation temperatures (8.5–11.5 °C) on the contents of selected esters, as well as on concentrations of amyl alcohols and on the sum of higher alcohols in beer, was determined in a commercial brewery fermentation plant. Beers produced throughout the experiments met or exceeded all criteria established for a commercial, marketed beer. Statistical analyses of the results revealed that within the studied ranges of process parameters, models with diversified significance described the concentrations of volatiles in beer. The multiple response optimization procedure analyses showed that the values of process parameters that minimized higher alcohols in beer (97.9 mg/L) and maximized its ethyl acetate (22.0 mg/L) and isoamyl acetate (2.09 mg/L) contents, as well as maximized the sensory quality of beer, (66.4 pts) were the following: Pitching rate 10 mln cells per mL; fermentation temperature 11.5 °C; aeration level 8.8 mg/L; and CCT filling time 4.5 h.

Potential of natamycin to control growth of Zygosaccharomyces spp. in apple juice during storage

In this research, anti-yeast activity of natamycin in apple juice inoculated with both Zygosaccharomyces rouxii and Z. bailii during the storage at different temperatures was investigated. For this purpose, a response surface methodology approach was used to test and optimize effects of some processing variables; storage time (1, 21 and 41 days), storage temperature (4, 12 and 20 °C), sodium benzoate as a positive control (0, 0.05 and 0.1%) and natamycin concentration (0, 30 and 60 mg/L) on several physicochemical and bioactive properties of the apple juice samples. The results showed that the natamycin performed a remarkable anti-yeast effect on Z. bailii rather than on Z. rouxii. The brix levels of the samples decreased and so the turbidity values increased significantly due to the yeast activity during the storage. Bioactive properties were also significantly affected by the natamycin which was also revealed to increase the antioxidant capacity of apple juice during storage. Using multiple response optimization technique, it was calculated that minimum yeast count (YC) values would occur at storage time = 38.64 and 40.9 days, storage temperature = 19.81 and 14.4 °C, sodium benzoate level (fixed to 0%) and natamycin concentration = 40 and 51.9 mg/L for the samples inoculated with Z. bailii and Z. rouxii, respectively. It was concluded that the bioactive properties of apple juice could be preserved by addition of natamycin which is suggested to be a natural inhibitor during the storage.

A Robust Interactive Desirability Function Approach for Multiple Response Optimization Considering Model Uncertainty

To solve multiple response optimization problems that often involve incommensurate and conflicting responses, a robust interactive desirability function approach is proposed in this article. The proposed approach consists of a parameter initialization phase and calculation and decision-making phases. It considers a decision maker's preference information regarding tradeoffs among responses and the uncertainties associated with predicted response surface models. The proposed method is the first to consider model uncertainty using an interactive desirability function approach. It allows a decision maker to adjust any of the preference parameters, including the shape, bound, and target of a modified robust function with consideration of model uncertainty in a single and integrated framework. This property of the proposed method is illustrated using a tire tread compound problem, and the robustness of the adjustments for the approach is also considered. The new method is shown to be highly effective in generating a compromise solution that is faithful to the decision maker's preference structure and robust to uncertainties associated with model predictions.