Application of response surface methodology and central composite rotatable design for modeling the influence of some operating variables of the lab scale thickener performance

This study discussed the application of response surface methodology(RSM)and central composite rotatable design(CCRD)for modeling and optimization of the influence of some operating variables on the performance of a lab scale thickener for dewatering of tailing in the flotation circuit.Four thickener operating variables,namely feed flowrate,solid percent,flocculant dosage and feedwell height were changed during the tests based on CCRD.The ranges of values of the thickener variables used in the design were a feed flowrate of 9–21 L/min,solid percent of 8%–20%,flocculant dosage of 1.25–4.25 g/t and feedwell height of 16–26 cm.A total of 30 thickening tests were conducted using lab scale thickener on flotation tailing obtained from the Sarcheshmeh copper mine,Iran.The underflow solid percent and bed height were expressed as functions of four operating parameters of thickener.Predicted values were found to be in good agreement with experimental values(R2values of 0.992 and 0.997 for underflow solid percent and bed height,respectively).This study has shown that the RSM and CCRD could effciently be applied for the modeling of thickener for dewatering of flotation tailing.

Optimization of Extraction Process of Clerodendrum philippinum Schauer var. simplex Mlodenke Total Flavonoids(CPTF) by Central Composite Design-Response Surface Methodology

[Objectives] The research aimed to optimize extraction process of Clerodendrum philippinum Schauer var. simplex Mlodenke total flavonoids( CPTF),and provide reference for its development and utilization. [Methods] Based on single-factor test,ethanol concentration,extraction temperature and extraction time were taken as independent variables,and total flavonoids yield was taken as dependent variable. The test was conducted according to central composite design principle. Multivariate linear regression and binomial equation fitting of the result were conducted,and extraction process of CPTF was optimized by using response surface methodology. [Results]The optimal extraction process of CPTF was as below: ethanol concentration 54. 76%,extraction temperature 83. 92℃,extraction time 102. 64 min,solid-liquid ratio 1:20,extraction for twice. [Conclusions] The extraction process of CPTF by central composite design-response surface methodology was simple and feasible,with reliable prediction result,which was suitable for industrial production.

Extraction Process Optimization of Total Flavonoids from Mallotus apelta Stems by Central Composite Design/Response Surface Method

[Objectives] To optimize the extraction process of total flavonoids in stems of Mallotus apelta. [Methods]On the basis of singlefactor test,with volume fraction of ethanol,extraction time and ratio of solvent as independent variables,the content of total flavonoids as dependent variables,the completely secondary response surface regression fitting was conducted on the independent and dependent variables,and the Response Surface Method was used to optimize the optimum extraction process of total flavonoids in Mallotus apelta stems and predict the optimum process. [Results] The optimum extraction process of total flavonoids in Mallotus apelta was determined as follows: ethanol concentration of 71. 5%; extraction time of 154. 6 min; solid-liquid ratio of 1∶19. 2; total flavonoids content of 7. 060 mg/g; fitted binomial squared correlation coefficient R^2= 0. 8751.[Conclusions]Composite Design/Response Surface Method could be used in the extraction process optimization of total flavonoids in Mallotus apelta stems,the mathematical model established had high prediction accuracy,the method was simple and operability was good.

Optimization of Extraction Process of Total Flavonoids from Akebia trifoliata (Thunb.) Koidz. by Central Composite Design-Response Surface Methodology

[Objectives]To optimize extraction process of total flavonoids from Akebia trifoliata( Thunb.) Koidz.,so as to provide references for development and use of Akebia trifoliata( Thunb.) Koidz. [Methods]The extraction rate of total flavonoids of Akebia trifoliata( Thunb.)Koidz. was taken as observation indicator. On the basis of single factor experiment,central composite design( CCD) was used to evaluate the effects of the extraction temperature,extraction time,and ethanol concentration on the extraction process. Multiple linear regression and binomial fitting were used,and response surface methodology( RSM) was used to select the optimum extraction process. [Results] The optimum extraction process conditions for total flavonoids of Akebia trifoliata( Thunb.) Koidz. was extraction temperature: 83. 92 ℃; extraction time:96. 47 min; ethanol concentration: 63. 92%; extraction times: two times; solid to liquid ratio: 1 ∶ 20; extraction rate of total flavonoids:4. 55%. [Conclusions] The central composite design-response surface methodology( CCD-RSM) is simple,convenient,and feasible for extraction of total flavonoids from Akebia trifoliata( Thunb.) Koidz.,and the prediction results are reliable.

Analysis of Heat Transfer Performance of Oscillating Heat Pipes Based on a Central Composite Design

Oscillating heat pipes (OHPs) are very promising cooling devices. Their heat transfer performance is af- fected by many factors, and the form of the relationship between the performance and the factors is complex and non-linear. In this paper, the effects of charging ratio, inclination angle, and heat input and their interaction effects on heat transfer performance of a looped copper-water OHP are analyzed. First, suppose that the relationship between the response and the variables approximates a second-order model. And use the central composite design to arrange the ex- periment. Then, the method of least squares is used to estimate the parameters in the second-order model. Finally, multi- variate variance analysis is used to analyze the model. The results show that the assumption is right, that is to say, the re- lationship is well modeled by a second-order function. Among the three main effect variables, the effect of inclination angle is the most significant, but their interaction effects are not significant. In the range of the considered factors, both the optimum charging ratio and the optimum inclination angle increase as the heating water flow rate increases.

A Study of Design Optimization Using Response Surface Analysis and Fabricaiton MEMS Probe Tip

In semiconductor manufacturing process, probe station that is testing equipment is important. Inspection step is for detecting defects on semiconductor before the packaging. Probe card is a part of probe station and contains probe tip that contacts to semiconductor. Through probe tip, it can inspect defects of semiconductor. In this paper, optimization method is used with response surface analysis to design MEMS type probe tip. And fabricating probe tip uses maskless lithography, electro-plating and lapping process.

Optimization and Characterization of Cellulose Extraction from Grevillea robusta (Silky Oak) Leaves by Soda-Anthraquinone Pulping Using Response Surface Methodology

Response surface methodology (RSM) using the central composite design (CCD) was applied to examine the impact of soda-anthraquinone pulping conditions on Grevillea robusta fall leaves. The pulping factors studied were: NaOH charge 5% to 20% w/v, pulping time 30 to 180 minutes, and the anthraquinone charge 0.1 to 0.5% w/w based on the oven-dried leaves. The responses evaluated were the pulp yield, cellulose content, and the degree of delignification. Various regression models were used to evaluate the effects of varying the pulping conditions. The optimum conditions attained were;NaOH charge of 14.63%, 0.1% anthraquinone, and a pulping period of 154 minutes, corresponding to 20.68% pulp yield, 80.56% cellulose content, and 70.34% lignin removal. Analysis of variance (ANOVA), was used to determine the most important variables that improve the extraction process of cellulose. The experiment outcomes matched those predicted by the model (Predicted R2 = 0.9980, Adjusted R2 = 0.9994), demonstrating the adequacy of the model used. FTIR analysis confirmed the elimination of the non-cellulosic fiber constituents. The lignin and hemicellulose-related bands (around 1514 cm−1, 1604 cm−1, 1239 cm−1, and 1734 cm−1) decreased with chemical treatment, indicating effective cellulose extraction by the soda-anthraquinone method. Similar results were obtained by XRD, SEM and thermogravimetric analysis of the extracted cellulose. Therefore, Grevillea robusta fall leaves are suitable renewable, cost-effective, and environmentally friendly non-wood biomass for cellulose extraction.

Analysis of Density of Sintered Iron Powder Component Using the Response Surface Method

The continued growth of ferrous powder metallurgy in automobile and others engineering application is largely de-pendent on the development of higher density materials and improved mechanical properties. Since density is a predominant factor in the performance of powder metallurgy components, it has been primarily considered for the present investigation. An experimental investigation have been undertaken in order to understand the variation of density with respect to the variation of process parameters viz., compaction load, sinter temperature and sintering time. The relation among the various process parameters with density has been observed. A mathematical model has been developed using second order response surface model (RSM) with central composite design (CCD) considering the above mentioned process parameters. The developed mathematical model would help in predicting the variation in density with the change in the level of different parameters influencing the density variation. This model also can be useful for setting of optimum value of the parameters for achieving the target density.

Catalytic Hydrothermal Liquefaction of Water Hyacinth Using Fe3O4/NiO Nanocomposite: Optimization of Reaction Conditions by Response Surface Methodology

This research aimed at optimizing the reaction conditions for the catalytic hydrothermal liquefaction (HTL) of water hyacinth using iron oxide/nickel oxide nanocomposite as catalysts. The iron oxide/nickel oxide nanocomposite was synthesized by the co-precipitation method and used in the hydrothermal liquefaction of water hyacinth. The composition and structural morphology of the synthesized catalysts were determined using X-ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM), and atomic absorption spectroscopy (AAS). The particle size distribution of the catalyst nanoparticles was determined by the Image J software. Three reaction parameters were optimized using the response surface methodology (RSM). These were: temperature, residence time, and catalyst dosage. A maximum bio-oil yield of 59.4 wt% was obtained using iron oxide/nickel oxide nanocomposite compared to 50.7 wt% obtained in absence of the catalyst. The maximum bio-oil yield was obtained at a temperature of 320°C, 1.5 g of catalyst dosage, and 60 min of residence time. The composition of bio-oil was analyzed using gas chromatography-mass spectroscopy (GC-MS) and elemental analysis. The GC-MS results showed an increase of hydrocarbons from 58.3% for uncatalyzed hydrothermal liquefaction to 88.66% using iron oxide/nickel oxide nanocomposite. Elemental analysis results revealed an increase in the hydrogen and carbon content and a reduction in the Nitrogen, Oxygen, and Sulphur content of the bio-oil during catalytic HTL compared to HTL in absence of catalyst nanoparticles. The high heating value increased from 33.5 MJ/Kg for uncatalyzed hydrothermal liquefaction to 38.6 MJ/Kg during the catalytic HTL. The catalyst nanoparticles were recovered from the solid residue by sonication and magnetic separation and recycled. The recycled catalyst nanoparticles were still efficient as hydrothermal liquefaction (HTL) catalysts and were recycled four times. The application of iron oxide/ nickel oxide nanocomposites in the HTL of water hyacinth increases the yield of bio-oil and improves its quality by reducing hetero atoms thus increasing its energy performance as fuel. Iron oxide/nickel oxide nanocomposites used in this study are widely available and can be easily recovered magnetically and recycled. This will potentially lead to an economical, environmentally friendly, and sustainable way of converting biomass into biofuel.

Central Composite Design响应面法优化厚裂凤仙花总黄酮提取工艺研究

为厚裂凤仙花中总黄酮资源的开发利用,本文采用单因素与星点-效应面法相结合的方式,考察提取溶剂浓度、料液比、提取时间、提取次数对厚裂凤仙花中总黄酮提取率的影响。优选出厚裂凤仙花总黄酮最佳提取方法为:甲醇体积分数80%,料液比为1︰64,提取时间为50 min;提次数为3次;验证实验结果表明,总黄酮平均提取率为5.51 mg/g,与实验模型RSD值为0.79%。建立的模型与实际方案有较高拟合度,可作为苗药厚裂凤仙花总黄酮提取工艺参数。

Probabilistic assessment of rock slopes stability using the response surface approach——A case study

This paper examines the stability condition of a jointed rock slope in the south western region of Saudi Arabia using deterministic and probabilistic approaches,under both dry and wet conditions.The study area is characterized by complex geology in rugged terrains.The stability analysis is carried out using the code FLAC3D to generate a 3-dimensional,ubiquitous joint model,to determine the influence of the dominant,unfavourable discontinuity orientation with respect to the slope face.The deterministic analysis is first implemented using the mean values of the selected random variables,namely the dip,dip direction and friction angle of the dominant discontinuity set,and the stability condition is assessed with a factor of safety based on the classical frictional joint constitutive model.A Box-Behnken design(BBD)approach is then adopted to create the surface response function as a second order polynomial for the factor of safety.To do so,fifteen FLAC3D models are generated in accordance with the BBD.Based on this,10,000 simulations of different slope realizations are carried out using Monte-Carlo simulation technique,and the probability of unsatisfactory of performance of the rock slope is assessed.It is shown that the probabilistic approach provides more insight and confidence in the stability condition of the rock slope,both under dry and steady state heavy rainfall conditions.A discussion is presented on the significance of accepting lower safety factors when heavy rainfall conditions are encountered.

Improvement of xylanase production by Aspergillus niger XY-1 using response surface methodology for optimizing the medium composition

Objective: To study the optimal medium composition for xylanase production by Aspergillus niger XY-1 in solid-state fermentation (SSF). Methods: Statistical methodology including the Plackett-Burman design (PBD) and the central composite design (CCD) was employed to investigate the individual crucial component of the medium that significantly affected the enzyme yield. Results: Firstly, NaNO3, yeast extract, urea, Na2CO3, MgSO4, peptone and (NH4)2SO4 were screened as the significant factors positively affecting the xylanase production by PBD. Secondly, by valuating the nitrogen sources effect, urea was proved to be the most effective and economic nitrogen source for xylanase production and used for further optimization. Finally, the CCD and response surface methodology (RSM) were applied to determine the optimal concentration of each sig-nificant variable, which included urea, Na2CO3 and MgSO4. Subsequently a second-order polynomial was determined by multiple regression analysis. The optimum values of the critical components for maximum xylanase production were obtained as follows: x1 (urea)=0.163 (41.63 g/L), x2 (Na2CO3)=?1.68 (2.64 g/L), x3 (MgSO4)=1.338 (10.68 g/L) and the predicted xylanase value was 14374.6 U/g dry substrate. Using the optimized condition, xylanase production by Aspergillus niger XY-1 after 48 h fermentation reached 14637 U/g dry substrate with wheat bran in the shake flask. Conclusion: By using PBD and CCD, we obtained the optimal composition for xylanase production by Aspergillus niger XY-1 in SSF, and the results of no additional expensive medium and shortened fermentation time for higher xylanase production show the potential for industrial utilization.

Optimization of medium components using response surface methodology (RSM) for mycelium biomass and exopolysaccharide production by <i>Lentinus squarrosulus</i>

The interaction between sucrose, yeast extract and initial pH was investigated to optimize critical medium components for mycelium biomass and production of exopolysaccharide (EPS) of Lentinus squarrosulus using Response Surface Methodology (RSM). A central composite design (CCD) was applied and a polynomial regression model with quadratic term was used to analyse the experimental data using analysis of variance (ANOVA). ANOVA analysis showed that the model was very significant (p Lentinus squarrosulus are as follows: sucrose concentration 114.61 g/L, yeast extract 1.62 g/L and initial pH of 5.81;sucrose concentration 115.8 g/L, yeast extract of 3.39 g/L and initial pH of 6.44 respectively.

Enhacement of the Viability of <i>Lactobacillus</i><i>plantarum</i>during the Preservation and Storage Process Based on the Response Surface Methodology

Objective: The Response Surface Methodology (RSM) is a commonly used system to optimize cell viability of probiotic strains when they are subjected to different preservation and storage processes. Methods and Results: To determine the optimal levels of incorporation of several cry oprotectants (skim milk, sucrose and trehalose) in the freeze-drying process of Lactobacillus plantarum, a range of experiments based on a Rotational Central Composite design (CCD) were conducted. The results were adjusted to a quadratic model, resulting in the presence of interaction between the different variables. Solving a regression equation, we obtained the optimum concentrations of cryoprotective agents: 24.06% milk powder, 6.22% sucrose, 5.63% trehalose. To visualize the interactions between the three variables involved in the study, Design Expert? software was used. Conclusions: The analysis reveals that while trehalose has a direct effect on the viability of L. plantarum, skim milk and sucrose exert quadratic effects. There are also interactions between cryoprotectants, which emphasize the synergies produced between milk and sucrose and between sucrose and trehalose, which allows maintaining the viability of L. plantarum. Significance and Impact of the Study: The addition of new oligosaccharides as trehalose in premixtures for functional feed can maintain the viability of L. plantarum during longer periods of time, ensuring the proper administration of probiotics to their destinations.

Optimization of Dielectric Barrier Discharge Process for Decolorization of Reactive Blue 19 by Means of Response Surface Methodology

The decolorization of reactive blue 19(RB-19)as a model dye from aqueous solutions has been studied by means of the dielectric barrier discharge(DBD)process.The independent parameters of input power,initial dye concentration and initial pH value were evaluated respectively.Experimental data were optimized by means of a 33 factorial design and response surface methodology(RSM).The dye was quickly removed during the treatment,yielding 96.9%of decolorization efficiency under optimized conditions.Therefore,the total organic carbon(TOC)and chemical oxygen demand(CODcr)results indicated that only the chromophore was destroyed rather than completed oxidation.This was confirmed with UV-vis and tertiary butanol assessments during the DBD treatment.

Optimal Evaluation of Coag-Flocculation Factors for Alum-Brewery Effluent System by Response Surface Methodology

This work investigates coag-flocculation optimization treatment of alum-brewery effluent system via response surface methodology (RSM). To minimize suspended and dissolved particles (SDP), experiments were carried out using nephelometric jar test and 23-factorial design with three star-points, six-center-points and two replications. A central composite design, which is the standard design of RSM, was used to evaluate the effects and interactions of three major factors (coagulation pH, coagulant dosage, settling time) on the treatment efficiency. Multivariable quadratic model developed for the response studied indicates the optimum conditions to be 9, 500mg/l and 20minutes for coagulation pH, coagulant dosage and settling time, respectively. At optimum, the SDP was reduced from 10831.490mg/l to 801.451mg/l, representing 92.601% removal efficiency. RSM has demonstrated to be appropriate approach for the optimization of the coag-flocculation process by statistical evaluation.

Optimization of the Impeller Geometry for an Automotive Torque Converter Using Response Surface Methodology and Desirability Function

Response surface methodology (RSM) based on desirability function approach (DFA) is applied to obtain an optimal design of the impeller geometry for an automotive torque converter. The relative importance of six design parameters including impeller blade number, blade thickness, bias angle, scroll angle, inlet angle and exit angle is investigated using orthogonal design approach. The impeller inlet angle, exit angle and bias angle are found to exert the greatest influence on the overall performance of a torque converter, with two flow area factors being considered, namely 17% and 20%. Then, RSM together with central composite design (CCD) method is used to in-depth evaluate the interaction effect of the three key parameters on converter performance. The results demonstrate that impeller exit angle has the strongest impact on peak efficiency, with larger angles yielding the most favorable results. The stall torque ratio maximization is attainable with the increase of impeller bias angle and inlet angle together with smaller exit angle. In the end, an optimized design for the impeller geometry is obtained with stall torque ratio and peak efficiency increased by 1.62% and 1.1%, respectively. The new optimization method can be used as a reference for performance enhancement in the design process of impeller geometry for an automotive torque converter.

基于Plackett-Burman设计和响应面法优化枣花蜂蜜挥发性成分的萃取条件

为了提高蜂蜜中挥发性成分的顶空固相微萃取(head space-solid phase micro extraction,HS-SPME)效率,以便利用气相色谱-质谱联用仪(gas chromatograph-mass spectrometer,GC-MS)对其进行更精确的定性与定量分析,以枣花(Ziziphus jujuba Mill.)蜂蜜挥发性成分的色谱图总峰面积作为考察指标,采用Plackett-Burman(PB)设计和响应面(response surface methodology,RSM)对枣花蜂蜜的萃取条件(萃取温度、萃取时间、样品量、去离子水添加量、氯化钠添加量和搅拌速度)进行优化。结果发现,萃取温度、萃取时间和样品量对色谱图总峰面积影响显著。优化后的萃取条件为萃取温度68.5℃、萃取时间51.6 min、取样量5.1 g,在最优萃取条件下,色谱图总峰面积可达2.20×10^(9) mAU·min^(-1)。以上研究结果为蜂蜜中挥发性成分的进一步定性与定量分析提供一定的方法性指导。

碳纤维复合材料与极地环境因素交互关系研究

目的揭示低温环境对碳纤维复合材料静态力学性能的影响,探讨极地环境因素的交互关系及其性能敏感性。方法采用正交试验设计,并通过极值与方差分析法探究各因素对材料性能影响的显著性与主次顺序。基于响应面法,建立力学性能指标与各环境因素间的二次回归模型,分析各因素之间的交互作用。结果碳纤维复合材料的硬度、抗拉强度和弹性模量对环境因素的敏感性存在差异。材料硬度和抗拉强度主要受辐照影响,其次为温度和覆冰厚度;弹性模量则受温度影响显著。响应面分析结果表明,温度、覆冰厚度与辐照之间存在明显的交互效应,尤其是对抗拉强度和弹性模量的影响更为显著,而对硬度的交互影响较弱。结论碳纤维复合材料在极地环境下表现出良好的稳定性与环境适应性,该研究将为碳纤维复合材料的极地应用提供一定的数据支持与理论基础。

Optimization of Jiawei Qing'e Oral Fast Disintegrating Tablets Based on Response Surface-Central Composite Design

Abstract: Objective To apply the response surface-central composite design to developing and optimizing the oral fastdisintegrating tablets (ODT) formulation for Jiawei Qing’e, a kind of prescription of Chinese herbal medicine.Methods The bitterness of Jiawei Qing’e was masked using Eudragit E-100 by solvent evaporation technique.Response surface approach was applied to investigating the interaction of formulation parameters in optimizing theformulation. The independent variables were Eudragit E-100/drug ratio (X1), amount of disintegrants (X2), and theamount of diluents (X3). The disintegration time (Y1), hardness (Y2), and weight variations of the tablets werecharacterized. Results The models predicted levels of X1= 4.63%, X2= 5.25%, and X3= 34.33%, for the optimalformulation having a hardness of 3.0 kg with the disintegration time of 30 s within experimental region. The observedresponse of Y1= 26.5 s and Y2= 3.14 kg reasonably agreed with the predicted response. Conclusion Responsesurface methodology shows the good predictability and reliability in optimizing the formulation. The optimized ODTof Jiawei Qing’e has acceptable taste, rapid disintegrating ability, and good mechanical strength.