Experimental Design Optimization Research Articles

Use of Taguchi’s DOE for process optimization of Co(II) extraction in chloride medium by Aliquat 336

Taguchi’s framework for the design of experiments (DOE)—more specifically, the orthogonal array L4 (23)—was used to optimize the extraction process of Co(II) statistically. A series of experiments involving the liquid–liquid extraction of cobalt by the ionic liquid extractant Aliquat 336 in a hydrochloric acidic medium were conducted. One experimental parameter was optimized per experiment. The cobalt was extracted (efficiency: 62%) and pre-concentrated (efficiency: 41%) from the loaded organic phase in deionized water (the stripping solution). Application of the McCabe–Thiele method indicated that six theoretical stages were needed to recover 98% of the cobalt. Process optimization was then performed via statistical analysis of the experimental data. Analyses of variance and of means showed that uncontrollable factors (noise) were completely absent from the process, and that only the main effects of the controllable factors A, B, and C—with no factor interactions—contributed to the optimal extraction of the cobalt, which was achieved when A, B, and C were at levels 2, 2, and 1, respectively. In this scenario, the signal-to-noise ratios for A, B, and C were 32, 29, and 26, respectively. Factor A was found to exert the strongest influence on the Co(II) extraction efficiency (50% of the combined influence of the three factors), followed by factors B (28%) and C (22%). Taguchi’s method is a widely accepted approach to DOE, and the application of this approach in this work shows that high-quality products can be produced using ecological green solvents, thus reducing the impact of cobalt production on the environment and ecosystems, which is important given that the cobalt mining industry is expanding globally.

Optimization of limonene biotransformation for the production of bulk amounts of α-terpineol

The biotransformation of R-(+)-limonene into high concentrations of R-(+)-α-terpineol by Sphingobium sp. was investigated in order to optimize the main process variables (pH, biocatalyst concentration, substrate concentration, temperature and agitation). This strategy comprised the screening of variables by a Plackett-Burman design followed by a Central Composite Design. The statistical analysis showed that the optimal α-terpineol production were at 28 °C and pH 7.0, with a limonene concentration of 350 g/L of organic phase agitation of 200 rpm and a biocatalyst concentration of 2.8 g/L of aqueous phase (OD600 = 8). Further trials showed that the R-(+)-α-terpineol concentration was higher (240 g/L after 96 h) when using a ratio of 1:3 (v.v−1) of organic:aqueous phases. However, the total production and yield (in terms of biomass) of α-terpineol would be maximized for an aqueous:organic ratio of 1:1. The experimental design optimization adopted herein was an effective tool for this type of study.

Nanocomposite-coated porous templates for engineered bone scaffolds: a parametric study of layer-by-layer assembly conditions

Using the layer-by-layer (LbL) assembly technique to deposit mechanically reinforcing coatings onto porous templates is a route for fabricating engineered bone scaffold materials with a combination of high porosity, strength, and stiffness. LbL assembly involves the sequential deposition of nano- to micro-scale multilayer coatings from aqueous solutions. Here, a design of experiments (DOE) approach was used to evaluate LbL assembly of polyethyleneimine (PEI), polyacrylic acid (PAA), and nanoclay coatings onto open-cell polyurethane foam templates. The thickness of the coatings, and the porosity, elastic modulus and collapse stress of coated foam templates were most strongly affected by the pH of PAA solutions, salt concentration, and interactions between these factors. The mechanical properties of coated foams correlated with the thickness of the coatings, but were also ascribed to changes in the coating properties due to the different assembly conditions. A DOE optimization aimed to balance the trade-off between higher mechanical properties but lower porosity of foam templates with increasing coating thickness. Micromechanical modeling predicted that deposition of 116 QLs would achieve mechanical properties of cancellous bone (>0.05 GPa stiffness and >2 MPa strength) at a suitable porosity of >70%. When capped with a final layer of PAA and cross-linked via thermal treatment, the PEI/PAA/PEI/nanoclay coatings exhibited good indirect cytotoxicity with mesenchymal stem cells. The ability of LbL assembly to deposit a wide range of functional constituents within multilayer-structured coatings makes the general strategy of templated LbL assembly a powerful route for fabricating engineered tissue scaffolds that can be applied onto various porous template materials to achieve a wide range of properties, pore structures, and multifunctionality.

Optimization of the heterogeneous electro-Fenton process assisted by scrap zero-valent iron for treating textile wastewater: Assessment of toxicity and biodegradability

In this work, the heterogeneous electro-Fenton process assisted by scrap zero-valent iron (SZVI) and with graphite electrodes (as anode and cathode) is studied as an alternative way to treat wastewater from a textile plant located in Medellín, Colombia. The effects of the initial pH, SZVI load, and current density in the SZVI-assisted electro-oxidation process (EO/SZVI) are analyzed and optimized using multivariable regression models generated using the Box–Behnken experimental design and convex nonlinear optimization. The EO/SZVI process leads to maximum reductions of approximately 100%, 67%, and 59% in color, chemical oxygen demand (COD), total organic carbon (TOC), respectively, under the optimal operating conditions of pH of 3.5. Further, it leads to an SZVI concentration of 0.6 g/L, and a current density of 20 mA/cm2 during 30 min of electrolysis. The post-process pollutants are characterized further using molecular weight distribution measurements, ultraviolet–visible spectroscopy, high-performance liquid chromatography, biodegradability, and toxicity. The results show that the treated effluent is polluted mostly by carboxylic acids of low molecular weight. A remarkable enhancement of the biodegradability of the effluent is evidenced by an increase in the BOD5/COD ratio (biodegradability index) from 0.15 to 0.54. Although the EO/SZVI process does not improve the toxicity (as measured by the mortality of Artemia salina), the latter is reduced subsequently from 100% to 20% through adsorption using activated carbon (AC). The findings of this study indicate that the EO/SZVI process is an effective and promising alternative for treating textile wastewater.

CROSSMAPPER: estimating cross-mapping rates and optimizing experimental design in multi-species sequencing studies.

MotivationNumerous sequencing studies, including transcriptomics of host-pathogen systems, sequencing of hybrid genomes, xenografts, mixed species systems, metagenomics and meta-transcriptomics, involve samples containing genetic material from divergent organisms. A crucial step in these studies is identifying from which organism each sequencing read originated, and the experimental design should be directed to minimize biases caused by cross-mapping of reads to incorrect source genomes. Additionally, pooling of sufficiently different genetic material into a single sequencing library could significantly reduce experimental costs but requires careful planning and assessment of the impact of cross-mapping. Having these applications in mind we designed Crossmapper, the first to our knowledge tool able to assess cross-mapping prior to sequencing, therefore allowing optimization of experimental design.ResultsUsing any combination of reference genomes, Crossmapper performs read simulation and back-mapping of those reads to the pool of references, quantifies and reports the cross-mapping rates for each organism. Crossmapper performs these analyses with numerous user-specified parameters, including, among others, read length, read layout, coverage, mapping parameters, genomic or transcriptomic data. Additionally, it outputs the results in highly interactive and publication-ready reports. This allows the user to perform multiple comparisons at once and choose the experimental setup minimizing cross-mapping rates. Moreover, Crossmapper can be used for resource optimization in sequencing facilities by pooling different samples into one sequencing library.Availability and implementationCrossmapper is a command line tool implemented in Python 3.6 and available as a conda package, allowing effortless installation. The source code, detailed information and a step-by-step tutorial is available at our GitHub page https://github.com/Gabaldonlab/crossmapper.Supplementary information Supplementary data are available at Bioinformatics online.

Optimization of Experimental Designs for System- Level Accelerated Life Test in a Memory System Degraded by Time-Dependent Dielectric Breakdown

Continuous memory technology scaling causes memory cells to be vulnerable to wearout. To ensure reliable operations of circuits and systems in the presence of wearout, we require accurate estimation of the lifetime of circuits and systems degraded by wearout. Since the conventional method of estimating circuit and system reliability degradation based on device-level accelerated life test (ALT) does not account for the tolerance of a circuit and a system to a wearout failure of a device, accelerated lifetime testing at the circuit and system level is necessary. For accurate estimation of system reliability using system-level ALT, we propose a method that optimizes the design of experiments for ALT. From significant observations from failure data statistics of system-level ALT with various stress conditions applied to the memory system of the Leon3 as a case study, we define acceptability regions for memory testing of each wearout mechanism. In addition, by analyzing errors in estimating Weibull parameters from system-level ALT, we develop a methodology that optimizes experimental designs in acceptability regions of each wearout mechanism to minimize such estimation errors in system-level ALT.

Analysis of Closed Loop Production System Using Orthogonal Array and Integer Programming Optimization

Sustainable production systems require optimal utilization of resources. Raw material acquisition is one of the costly processes in a production system. EOL (End-of-Life) products re-manufacturing through reverse logistics can help in decreasing excessive raw material cost. In this study, we consider production system of closed loop supply chain in which both forward and reverse production systems are active. DOE (Design of Experiments) methodology is incorporated which is a statistical approach adopted in dealing with complex workplace problems. We employ L9 orthogonal array using Taguchi experiment in Minitab 17 and DOE for plotting the results. Dependent variables used in this study are productivity, P (number of forward and reverse products produced per period) and quality accuracy of product (measured in percent deviation from reference standards). A trade-off analysis between the control variables is presented on the basis of SNR (Signal to Noise Ratio). Control variables used in the analysis are tools employed in production system (tu), number of machines being used (m) and dedicated manufacturing cells (dc). We use three levels of analysis for each control factor. Optimum result conditions are calculated using signal to noise ratio with larger-the-better-criteria as well as smaller-the-better criteria and study is concluded with main effects of the mean plots. DOE optimization analysis for productivity suggests combination set of 32, 8, and 6 for tools, machines in use and manufacturing cells, respectively. Similarly, for optimal dimensional accuracy, tools used are 24; number of machines in use is 14 with 3 manufacturing cells. All result indices are accomplished within a confidence interval of 95% with p-values less than 0.05. MILP (Mixed Integer Linear Programming) analysis considers cost function of production and transportation between tools, machines and levels and Taguchi based experimental findings are validated by mathematical optimization findings.

Experimental design applications in chemistry: A case study on Central composite design for optimization of extraction of olive seeds in a Soxhlet

Chemometrics is described in general as to extract the more useful information from the chemical data obtained experimentally by various methods applying some mathematical techniques to these data. Today, studies in many fields such as chemistry, biochemistry, earth, and environmental sciences are done experimentally and all analysis of semi-finished and finished products or raw materials for quality control are carried out in the laboratories. Establishment of test strategies for experimental design, analysis of experimental design models and optimization of the experimental factors of a reaction selected as a practical application for experimental design are the main subjects of this study. Here it was summarized creation of experiment strategies in order to optimize the effective operation factors on chemical reactions, mathematical solution techniques of the response surface functions to define the relationships between the factors and the experimental result affected by the factors, computer programing for the optimization of the reaction parameters and usage of some related software, statistically evaluation for the experimental results and optimization of a selected reaction as an experimental design application.

Defining Key Factors in Carbon Black-Filled NR/BR Compounds for Balancing Aircraft Tire Tread Properties

Carbon black (CB) is the most common reinforcing filler used in aircraft tire tread formulations. For CB-reinforced natural rubber/butadiene rubber (NR/BR) compounds, material and processing parameters are important factors that need to be controlled, as they can influence both, processing as well as the vulcanizate properties. It is essential to investigate and optimize the key elements, in order to achieve the target properties, while maintaining an acceptable trade-off for other characteristics. In the present study, the type of BR, mixer temperature, rotor speed, and filler mixing time were selected as input factors. A complete design of experiments (DOE) process was performed that comprised the following—two-level full factorial setup for initial screening, response surface method (RSM) for optimization, and confirmation runs for validation. This evaluation procedure was used to study the impact of factors and their interactions on the properties of CB-filled NR/BR compounds. From the DOE optimization which was later confirmed by the DOE validation, high rotor speed and long filler mixing time were the most significant factors in improving the Mooney viscosity, modulus at 300% elongation, hysteresis (tan delta), as well as in reducing the filler–filler interaction (Payne effect). In the case of tensile strength (TS) and abrasion resistance index (ARI), high rotor speed and long filler mixing time had an adverse effect, thus, causing a deterioration of these properties. Therefore, it is recommended to decrease the filler mixing time when combining it with high rotor speed.

Sequestration of methylene blue dye from aqueous solution by magnetic biocomposite: Three level Box–Behnken experimental design optimization and kinetic studies

ABSTRACT An attempt was made to maximize the sequestration of methylene blue (MB) dye from aqueous solution using magnetic biocomposite (WH/MnFe2O4 ) synthesized by chemical co-precipitation method. WH/MnFe2O4 was characterized by different techniques such as scanning electron microscope, X-ray diffraction, Fourier-transform infrared, and Energy-dispersive X-ray spectroscopy. An ideal experimental design was carried out based on three-factors, three-level Box–Behnken design using response surface methodology in the lab-scale batch study. The adsorption of MB dye on to WH/MnFe2O4 has been found to be highly significant with very low probability (p) values (<0.0001) based on the analysis of variance statistical value. The kinetics of the dye sorption followed the pseudo-second-order equation (R 2 > 0.996).

Application of hydrophobic deep eutectic solvent as the carrier for ferrofluid: A novel strategy for pre-concentration and determination of mefenamic acid in human urine samples by high performance liquid chromatography under experimental design optimization

In this study, ferrofluid of magnetic nanoparticles, oleic acid (OA), combined with hydrophobic deep eutectic solvent (Fe3O4 [iron oxide]-OA-DES) was prepared and coupled with vortex-assisted liquid phase microextraction, to pre-concentrate and determine mefenamic acid (MFA) in urine samples, following high performance liquid chromatography (HPLC). With regard to Fe3O4 nanoparticles, all sorbents were identified by SEM, TEM, and XRD. In addition, the influence of different parameters such as pH, ferrofluid volume, ionic strong (NaCl concentration %), and vortex time was investigated and optimized by response surface methodology (RSM) and central composite design (CCD). Maximum MFA extraction predicted by RSM (97.66) was achieved at pH 4.0, 60 μL of ferrofluid, 3%w/v NaCl, and 7 min vortex time with desirability of 1.0. Under the optimized conditions, the limits of detection (LOD) and the limit of quantification (LOQ) were 1.351 ng mL−1 and 4.575 ng mL−1, respectively. The intra-day and inter-day precision (RSD [relative standard deviation]%) in the concentrations of 50, 300, and 700 ng mL−1 of MFA were less than 3.6% and 4.2%, respectively. The method developed in our study could successfully determine MFA in urine samples. The MFA microextraction in urine samples were between 80.25 and 97.44% with RSD% less than 4.60%. Inclusion of ferrofluid in a miniaturized method for sample preparation is proportional to the achievement of high microextraction percentage using green analytical method.

Effects of PEG, PVP and SDS on the Properties of Chromium Coatings Prepared from Trivalent Chromium Chloride Baths Using Experimental Design and Multi-Response Optimisation

Effects of PEG, PVP and SDS on the Properties of Chromium Coatings Prepared from Trivalent Chromium Chloride Baths Using Experimental Design and Multi-Response Optimisation

Modulation of the Release of a Non-Interacting Low Solubility Drug from Chitosan Pellets Using Different Pellet Size, Composition and Numerical Optimization.

Two size classes of piroxicam (PXC) pellets (mini (380–550 μm) and conventional (700–1200 μm)) were prepared using extrusion/spheronization and medium viscosity chitosan (CHS). Mixture experimental design and numerical optimization were applied to distinguish formulations producing high sphericity pellets with fast or extended release. High CHS content required greater wetting liquid volume for pellet formation and the diameter decreased linearly with volume. Sphericity increased with CHS for low-to-medium drug content. Application of PXRD showed that the drug was a mixture of form II and I. Crystallinity decreased due to processing and was significant at 5% drug content. Raman spectroscopy showed no interactions. At pH 1.2, the dissolved CHS increased ‘apparent’ drug solubility up to 0.24 mg/mL while, at pH 5.6, the suspended CHS increased ‘apparent’ solubility to 0.16 mg/mL. Release at pH 1.2 was fast for formulations with intermediate CHS and drug levels. At pH 5.6, conventional pellets showed incomplete release while mini pellets with a CHS/drug ratio ≥2 and up to 21.25% drug, showed an extended release that was completed within 8 h. Numerical optimization provided optimal formulations for fast release at pH 1.2 with drug levels up to 40% as well as for extended release formulations with drug levels of 5% and 10%. The Weibull model described the release kinetics indicating complex or combined release (parameter ‘b’ > 0.75) for release at pH 1.2, and normal diffusion for the mini pellets at pH 5.6 (‘b’ from 0.63 to 0.73). The above results were attributed mainly to the different pellet sizes and the extensive dissolution/erosion of the gel matrix was observed at pH 1.2 but not at pH 5.6.

Design of experiment for optimization of nitrophenol reduction by green synthesized silver nanocatalyst

Phenol derived molecules are considered as critical pollutants in the environment and need to be decontaminated to safeguard our mother Earth. This may sometimes be achieved by degradation using nanomaterials. Plant mediated biosynthesis of nanoparticles is truly encouraging for environmental safety as well as easy availability of precursor materials.The present report demonstrates the catalytic reduction of 4-nitrophenol using silver nanoparticle, synthesized from rhizome of Cyperus Rotundus. It is characterized by UV–vis and FTIR spectra, DLS, SEM-EDS, AFM, FESEM and TEM. The size of the particle is estimated to be in the range of 10–40 nm. Degradation pathway using NaBH4 and silver nanoparticle catalyst is followed under visible light. The influence of variables such as time, dose of NaBH4, 4-nitrophenol (4-NP) and silver nanoparticle was investigated following response surface methodology. A mathematical model is built up to correlate the interactive influences of the significant variables and the reduction. The mutual interactions of these variables are mapped in the design space by response surface and contour plots. The process follows a pseudo first-order kinetic model and the activation energy was evaluated to be 53.3 kJ mol−1. The conversion of 4-NP–4-AP was confirmed from NMR studies.

Electrochemical synthesis of Zn:ZnO/Ni2P and efficient photocatalytic degradation of Auramine O in aqueous solution under multi-variable experimental design optimization

Present work is devoted to synthesis Zn:ZnO/Ni2P by electrochemical method and identification and properties investigation by various techniques such as SEM, EDS, XRD and DRS. The experimental results reveal have ability for degradation of Auramine O (AO) following estimation of correlation among response to (main effect and variables interactions) variable like irradiation time, nanocomposite mass, pH and initial AO concentrations by a central composite design (CCD). The optimum condition for the photo-degradation of AO by photocatalyst was 6.72, 61.66 min, 13.13 mg L−1 and 0.014 g correspond to the pH, irradiation time, AO concentration and photocatalyst mass, respectively. At these optimum conditions, the AO photocatalytic degradation percentages with desirability of 0.94 was 95.47% using reasonable consumption of reagent. The quasi first-order kinetic model derived from Langmuir–Hinshelwood (L–H) efficiently represent real behavior of experimental data of correspond to under study system. The photocatalytic reaction, L–H rate constants and L–H adsorption constants for Zn:ZnO/Ni2P were 0.0375 min−1, 27.39 mg min−1 L and 0.00048 L mg−1, respectively.

Statistical Design of Experiments for Screening and Optimization

AbstractDesign of experiments (DoE) is a family of methods for performing experiments that are maximally informative for a chosen mathematical model. Statistical design of experiments focuses on empirical models that are sufficiently flexible as to describe a wide variety of systems, while having favorable mathematical properties for convenient estimation and optimization. This review describes approaches in statistical DoE for screening through many potential influencing factors and finding optimum process conditions.

Application of design of experiments for laser shock peening process optimization

Laser shock peening—a very promising life enhancement technique—has demonstrated great success regarding the improvement of fatigue behavior via deep compressive residual stresses. However, the prediction and adaption of residual stress fields on basis of the laser peening parameters are still not comprehensively established. The aim of the current work is to investigate the effects of the laser pulse energy, the number of treatment overlaps as well as the laser spot size on the resulting residual stress distribution, characterized by following quantities: the residual stress close to the surface, the maximum compressive residual stress, and the integral compressive stress area over the specimen depth. For a systematic investigation of all main and interaction-based process parameter effects, and a subsequent parameter optimization, the general full factorial design is employed. The results show that laser shock peening with different process parameter combinations, inducing residual stresses with comparable integral stress area, can lead to a minimum fatigue life extension of approx. 100,000 cycles, representing a minimum fatigue life of 250% of the base material. The experimental scatter in the number of cycles to failure follows the Weibull distribution which qualitatively correlates with the standard deviation of the integral stress area.

Experimental performance evaluation and design optimization of a horizontal multi-pipe separator for subsea oil-water bulk separation

Subsea separation of produced water increases the recovery rates for brown field installations. Removing produced water on the seabed increases production rates, removes topside produced water bottlenecks and enables better utilization of existing topside facilities. Existing subsea bulk water separator technologies are limited to gravity and compact gravity vessel types, as seen on Troll and Tordis, and the pipe separator installed at Marlim, which are large, heavy and costly installations. In order to make the business case for subsea produced water separation more attractive, there is a need to reduce the weight and areal footprint of separator designs. It is also important to develop separator solutions that can be qualified for a wide range of field operating conditions.This paper presents the experimental testing of a novel produced water separator design, the Multiple Parallel Pipe Separator (MPPS). The design uses multiple horizontal pipe segments in parallel for liquid-liquid separation, with inclined outlet pipe segments for increased water holdup and eased water extraction. Experiments are performed on a two-pipe prototype.A limited test matrix was run to investigate the best location for water extraction. Three tapping locations were tested. Experiments displayed oil re-entrainment along the inclined extraction pipe, and the best extraction point was found to be close to the horizontal to inclined transition.Using the identified tapping location, a detailed performance mapping was performed at total flow rates from 300 to 700 L/min and water cuts ranging from 30 to 90%. The performance mapping was performed with three different inlet configurations, a normal inlet, a tangential inlet, and a tangential inlet accompanied with novel phase re-arranging internals. Best separator performance was achieved for the tangential inlet with internals configuration, displaying efficiencies in the range 78.8–100%.A dispersion layer was observed in the separator pipes for total flow rates above 350 L/min. At low water extraction rates, this forming dispersion layer was observed to migrate completely into one of the two separator branches at random. The uneven splitting of the dispersion layer was observed to strengthen when changing from a normal to a tangential inlet configuration. The installation of phase-rearranging internals eliminated the uneven splitting of the dispersion layer, resulting in an even phase distribution between the two separator branches.

Photocatalytic Activity of ZnO–SnO2 Ceramic Nanofibers for RhB Dye Degradation: Experimental Design, Modeling, and Process Optimization

Photocatalytic degradation of rhodamine B (RhB) dye in aqueous solution is evaluated using ZnO−SnO2 nanofibers under visible‐ and UV‐light irradiation. The ceramic nanofibers are characterized by X‐ray diffractometry (XRD) and TEM technique. The results of XRD disclose the wurtzite phase for the inorganic structures. In turn, the microscopy analysis by TEM reveals the formation of the ultrathin ceramic fibers with 500 nm in diameter. The influence of the irradiation time, temperature, and pH on the color removal efficiency is investigated. UV–vis spectral analysis is used to measure the photocatalytic activity of metal oxide composites. The optimal conditions for the efficient RhB dye degradation under visible‐light are found to be: irradiation time *t = 13.3 h; temperature *T = 42 °C, and *pH = 9.5. In these conditions, a color removal efficiency of 94.20% is observed under visible‐light irradiation. In addition, a photocatalytic test under UV‐light irradiation is performed revealing a pseudo‐first‐order rate constant of 0.0166 min−1 and a color removal efficiency of 99.35%.

Production of Nattokinase Based Nutraceutical by Solid State Fermentation using Bacillus subtilis MTCC1427

Present study was undertaken to produce Nattokinase by solid state fermentation (SSF) using Bacillus subtilis MTCC1427. Initial studies are based on one parameter optimization experiments and data obtained were utilized for design of experiments for optimization through response surface methodology (RSM) taking five parameters namely inoculum size, concentration of combinations of dehulled soybean and fenugreek seeds, pH, temperature and fermentation time. Analysis of the results obtained from 32 experiments revealed the maximum yield 44.51 U/gdwt. of Nattokinase under the condition of inoculum size 3.02%, concentration of 26.92% fenugreek seeds(FS) with dehulled soybean, pH 6.98, temperature 31.72oC and fermentation time 55.03 hours. RSM suggests the yield of Nattokinase 44.51 U/gdwt., it is 11.28% higher than one parameter optimization experiments. Human consumption of this nutraceutical product is not only suitable for prevention of cardiovascular diseases but also very good for diabetic patients. However sensonary evaluation suggest overall acceptability as dislike slightly.