response surface method

The aqueous two-phase system (ATPS) as a liquid-liquid fractionation technique has gained an interest because of great potential for recovery and purification of many biological materials such as proteins, enzymes, and nucleic acids. Ionic liquids (ILs), are a group of organic salts comprising entirely of ions and can be suggested as a suitable solvent for a specific purpose, especially separation processes. Among the various ILs, the alkyl-sulfate derivatives have the great advantages such as synthesizing easily in a halide-free way at a reasonable cost with relatively low viscosity and considering as a promising IL in ATPSs. In the present study, the partitioning of protease using the ATPS [1-Ethyl-3-Methyl-Imidazolium][EthylSulfate]([emim][eSO4])/Na2CO3 was evaluated. The effect of parameters, such as the initial concentration of enzyme (protease), concentration of ionic liquid (IL) ([emim][eSO4]) and concentration of salt (sodium carbonate) on the purification of protease was investigated.

The design experiment of BOX-Behnken as a method of the response surface methodology (RSM) was applied to minimize the number of runs and the process optimization.

The optimum conditions were enzyme/IL of 0.210 and enzyme/salt of 0.381 and concentration of enzyme in the top phase (IL rich phase) and separation yield were obtained, 4 ppm and 94%, respectively.

The results showed that the protein tends to be extracted in a top phase, hence the protein concentration in the bottom phase (salt rich phase) was negligible. Furthermore, the experimental results are correlated successfully using non-random two liquid non-random factor (NRTL-NRF) equation as a short-range contribution.

Contact and friction in moving systems cause heat generation and this factor affects the properties and performance of parts. The purpose of this research is to investigate the effect of speed, pressure, and friction coefficient parameters on the heat produced in a linear sliding system. In this regard, a finite element model of a linear reciprocating compressor piston assembly was used and the results were validated using experimental data. Also, the response surface method and ANOVA analysis were utilized in the design of experiments and analysis of the results. Investigation of the results showed the parameters of speed, friction coefficient, and pressure have a direct relationship with temperature, speed has the greatest effect and pressure has the least effect on the produced temperature. Increasing the speed causes to increase the heat production, but the effect of increasing the pressure is the result of increasing the heat caused by increasing the friction force and reducing the heat caused by increasing the effective contact surface and better heat transfer.

In this research, the modeling of a solar renewable system along with the use of intelligent optimization method was discussed in order to increase the system performance and reduce the life cycle cost. A system with a combination of five units of PVT panel, heat pump, PEM electrolyzer, hot water storage source and fuel cell was designed to provide the required energy consumption of an 80-unit residential complex in Iran, including hot water, cooling, heating and electricity. The performance of the proposed system was analyzed by using the weather information of the coastal city of Bandar Lengeh in Hormozgan province. System modeling was done using a new approach by TRNSYS software. Optimization of this system to increase system performance and reduce life cycle cost was done by Design Expert software and using RSM. The three objective functions investigated included electricity production, PMV and LCC, and four decision variables including the number of solar panels, fuel cell capacity, heat pump capacity and electrolyzer capacity were selected. The optimization results showed that in the most optimal state with the number of 1425 solar panels, the capacity of 65.99 kW for the fuel cell, the capacity of 40.01 kW for the heat pump and the capacity of 52.5 kW for the electrolyzer are in the optimal state. The system can reach the production value of 725955.25 kWh per year in the optimal condition with a PMV of 0.43 and a LCC of 344014.63 $.

Masonry arch bridges are built using masonry materials such as brick or stone with or without mortar. Their mechanical properties due to the variety of materials used, the quality of construction, and the effect of the passage of time can be inconstant and have significant uncertainties. Therefore, to ensure the ability and performance of the structure against the loads, especially earthquakes, adopting more accurate modeling methods and considering these uncertainties is fundamental issue of structural engineering. For a stone arch bridge of Iran's railway network, the mechanical properties of the materials including the normal and shear stiffness coefficient of the stone block joint as well as the internal friction angle of the joints were considered as quantities with uncertainty and as random variables. According to the discrete environment of the bridge, incremental dynamic analysis has been performed under the influence of eleven selected earthquake records using the discrete element method. After analyzing more than 2,600 bridge samples with different material properties, based on the response surface method, the limit state functions of the bridge failure in terms of three random variables have been determined for all records. Using FORM and MSC reliability methods, the reliability index and probability of bridge failure were calculated. The results showed that for the selected earthquake records, the spectral acceleration of the bridge collapse threshold were reduced by 30% to 50% considering the uncertainties compared to the case where the uncertainty in the materials is not considered.

Using latent heat storage systems with phase change materials (PCM) is an effective way to store thermal energy, which has been of great interest recently. Using fins is one of the simplest and cheapest ways to increase heat transfer in PCMs and increase the performance of the storage system. Since the fin arrangement has a significant impact on the charging time of the PCM, the main goal of this study is to optimize the fin arrangement in the PCM chamber in a double-pipe heat exchanger in order to decrease the charging time, and thus increase the efficiency of the storage system. For this purpose, the governing equations including conservation of mass, momentum, and energy in a finned double-pipe heat exchanger have been solved using ANSYS-Fluent software to investigate the dynamic behavior of PCM. The thermal-hydraulic performance of PCM at different configurations has been fully analyzed by drawing liquid fraction contours, velocity vectors and streamlines. Also, to find the optimal fin arrangement and maximize the storage performance, the response surface method based on the central composite design have been implemented. The results obtained from the response surface with the reduced cubic equaltion show that compared to the case without fins, the charging time reduces by about 19% using the uniform fin configuration, while reduces about 56% using the optimal fins arrangement, which is a significant amount.

In recent years, additive manufacturing has gained significant importance in the field of production. Most of the additive manufacturing technologies for metals involve melting and solidification processes, leading to metallurgical challenges. The friction stir additive manufacturing process is a novel solid-state method that does not face the common metallurgical challenges associated with the traditional melting methods. This process can be used for the production of aluminum-silicon carbide nanocomposites that find many applications in industries such as military, aerospace, automotive, etc. The primary objective of this research is to experimentally analyze the effect of tool rotational speed, tool traverse speed, and number of passes in friction stir additive manufacturing on the microhardness and wear amount of aluminum-silicon carbide nanocomposite manufactured by this method. To this end, the response surface method and Minitab software were used for experimental design, statistical analysis, and optimization of the parameters. Multi-objective optimization settings were selected to increase microhardness and reduce wear. The combinations of optimal values of the parameters were determined to achieve the optimization goals, and the results were validated. The optimization result with 0.87 desirability is obtained with a tool rotational speed of 1000 rpm, a tool traverse speed of 50 mm/min, and one pass. The predicted optimal responses of 104 Vickers for microhardness and 0.013 gr for wear had a small percentage of error compared to the experimental results.

In this paper dielectric barrier discharge plasma actuator effect on flow separation of a horizontal axis wind turbine blade section were studied. Firstly, two dimensional flow simulations of plasma actuator with improved electrostatic model were performed in various operational conditions and angle of attacks. Then, an explicit response surface mathematical model was derived for the effect of variables on aerodynamic coefficients. Separation zone shrinkage was observed as a consequence of momentum injection from plasma actuation. The mathematical model has an acceptable validity and shows the significant interaction between parameters. Finally, a MATLAB code was developed to implement blade element momentum method and evaluate the mechanical output power of Tellus 100 kW wind turbine with actuator operation. The results indicate no significant effect on output power for cut-in to 10 m/s wind speeds and an increase of about 11 percent for 11 to 16 m/s speeds.

In this paper, activated carbon prepared from agricultural waste has been used as pollutants absorbent in porous concrete. This activated carbon is produced during two stages of carbonization (pyrolysis) and activation at high temperature. In order to reach the desired and optimal results, the response surface method (RSM) has been used. while evaluating the ability to remove pollutants from runoff water, it has been trying to improve the mechanical characteristics of this type of concrete by adding activated carbon, micro silica, water to cement ratio changes and the amount of fine grains. Design-Expert software was used to design the experiment using the Box-Behnken method. To use the Box-Behnken method, 4 input variables were defined including active carbon percentage (1% to 2.5%), water-cement ratio (0.3 to 0.4%), micro silica percentage (5% to 10%) and fine grain percentage (0 to 10%), which provided 27 mixing plans. Results showed that the presented models for estimating 28-day compressive strength are correlated with R² value of 0.97, 7-day compressive strength with R² value of 0.84, 42-day compressive strength with R² value of 0.95, COD with R² value of 0.94, TSS with R² value of 0.93 , TDS with R² value of 0.91 and copper heavy metal removal with R² value of 0.94, which indicate the significance of the test design as well as the improvement of the mechanical characteristics and removal of pollutants in porous concrete containing waste activated carbon.