Low cost anisotropic etching of monocrystalline Si (1 0 0): Optimization using response surface methodology

Reduced surface reflectance and enhanced light trapping is required by any high efficiency solar cell. Anisotropic etching was done on silicon (1 0 0) by using tetramethyl ammonium hydroxide TMAH, (CH₃)₄NOH, solution at 85 °C. Process variables considered were solution concentration and time proposed by response surface methodology (RSM). An effective surface texture was resulted with reflectance less than 8% without antireflection coating. The antireflection mechanism was also co-related with the etch rate of Si. Optimized values predicted by RSM for time and TMAH concentration were 5 min and 3.50% respectively. The technique and optimization of parameters by using response surface methodology (RSM) could be valuable in the texturization process for high-efficiency Si solar cells.     

Computational-Based Approach for Predicting Porosity of Electrospun Nanofiber Mats Using Response Surface Methodology and Artificial Neural Network Methods

Comparative studies between response surface methodology (RSM) and artificial neural network (ANN) methods to find the effects of electrospinning parameters on the porosity of nanofiber mats is described. The four important electrospinning parameters studied included solution concentration (wt.%), applied voltage (kV), spinning distance (cm) and volume flow rate (mL/h). It was found that the applied voltage and solution concentration are the two critical parameters affecting the porosity of the nanofiber mats. The two approaches were compared for their modeling and optimization capabilities with the modeling capability of RSM showing superiority over ANN, having comparatively lower values of errors. The mean relative error for the RSM and ANN models were 1.97% and 2.62% and the root mean square errors (RMSE) were 1.50 and 1.95, respectively. The superiority of the RSM-based approach is due to its high prediction accuracy and the ability to compute the combined effects of the electrospinning factors on the porosity of the nanofiber mats.     

Simultaneous ultrasound-assisted removal of sunset yellow and erythrosine by ZnS:Ni nanoparticles loaded on activated carbon: Optimization by central composite design

The present study focused on the simultaneous ultrasound-assisted removal of sunset yellow and erythrosine dyes from aqueous solutions using ZnS:Ni nanoparticles loaded on activated carbon (ZnS:Ni-NP-AC) as an adsorbent. ZnS:Ni nanoparticles were synthesized and characterized using different techniques such as FESEM, XRD and TEM. The effects of various parameters such as sonication time, pH, initial dye concentrations and adsorbent dose on the percentage of dye removal were investigated. Parameters were optimized by central composite design (CCD) combined with response surface methodology (RSM) and desirability function (DF). A good agreement between experimental and predicted values was observed. The ultrasound-assisted adsorbent (0.04 g) was capable of high percentage removal (98.7% and 99.6%) of sunset yellow and erythrosine in short time (3.8 min).     

混合植物染料敏化的太阳能电池性能

采用植物染料叶绿素和叶黄素，模拟光合作用的光电转化，以单独和混合等方式敏化纳晶多孔TiO2膜电极，制备了太阳能光化学电池.测试电池的输出特性发现，叶绿素和叶黄素以不同浓度混合后敏化的电池转化效率η为叶绿素和叶黄素单独敏化时的5.8倍和1.4倍，最大输出功率Wopt为叶绿素和叶黄素单独敏化时的5.7倍和1.4倍.混合染料敏化表现出明显的非线性叠加效应，其效能超过两种染料分别敏化时的线性叠加.混合染料的协同效应对提高电池转化效率，获取高效、廉价、环保能源具有重要意义.     

非链式脉冲DF化学激光器反应动力学模型

依据非链式脉冲氟化氘(DF)激光器的反应机理, 采用速率方程理论, 综合考虑了基态DF分子、D₂分子、D原子、F原子对激发态DF分子的消激发作用, 建立了非链式脉冲DF激光器反应动力学模型. 运用Runge-Kutta法对该模型进行数值计算, 得到了增益区内各组分粒子数密度随时间的变化关系. 进而运用该模型研究了工作气体配比和输出镜反射率对DF激光器腔内光子数密度、 单脉冲能量、脉冲宽度和输出功率的影响, 得到了最佳气体配比和最佳输出镜反射率参数. 采用放电引发方式对非链式DF激光器进行了实验研究, 实验测得脉冲波形及单脉冲能量与速率方程理论模型计算结果基本一致. 本文的研究结果可为非链式脉冲DF激光器的优化设计提供理论参考. 关键词： 脉冲DF激光器 动力学模型 速率方程 数值计算     

Modeling of process intensification of biodiesel production from Aegle Marmelos Correa seed oil using microreactor assisted with ultrasonic mixing

Conventionally, the batch type reactors were used for the production of biodiesel. However, in recent years, the usage of microreactors has started emerging as a significant substitute for biodiesel production due to its higher conversion rate at a short duration. These microreactors have a significantly high surface to volume ratio and high heat-mass transfer rate. The disadvantage of this type of reactors is its low mixing rate of the reagents. This can be overcome with the assistance of ultrasonic mixing. The main objective of this paper is to study the interlaced effect of a continuous flow microreactor and ultrasonic mixing on trans-esterification of Aegle Marmelos Correa seed oil using sodium methoxide catalyst. Results of microreactors with 0.3 mm and 0.8 mm diameter were compared. The effects of process parameters namely, flow rate (2–10 mL/min), reaction temperature (45–65 °C), catalyst amount (0.5–2.5 wt%), oil to methanol molar ratio (1:6–1:18) and ultrasonic mixing time (30–150 s) were studied using response surface methodology (RSM). The biodiesel yield of 98% and 91.8% were obtained for 0.3 mm and 0.8 mm microreactors, respectively. The maximum biodiesel yield observed in 0.3 mm reactor under following optimum conditions: 6.8 mL/min flow rate, 48 °C reaction temperature, 1.3 wt% catalyst, 1:9 oil to methanol molar ratio and 83 s ultrasonic mixing time. The predictive and generalization abilities of RSM and artificial neural network (ANN) models were evaluated and compared. The study showed that ANN and RSM models could predict the yield with an R² value of 0.9955 and 0.9900 respectively. However, the ANN model predicted the yield with the least mean square error value of 0.00001294, which is much lower than RSM.     

Ultrasound assisted aqueous two-phase extraction of polysaccharides from Cornus officinalis fruit: Modeling,optimization, purification,and characterization

Ultrasound assisted aqueous two-phase extraction of polysaccharides from Cornus officinalis fruit was modeled by response surface methodology (RSM) and artificial neural network (ANN), and optimized using genetic algorithm coupled with ANN (GA-ANN). Statistical analysis showed that the models obtained by RSM and ANN could accurately predict the Cornus officinalis polysaccharides (COPs) yield. However, ANN prediction was more accurate than RSM. The optimum extraction parameters to achieve the highest COPs yield (7.85 ± 0.09)% was obtained at the ultrasound power of 350 W, extraction temperature of 51 ℃, liquid-to-solid ratio of 17 mL/g, and extraction time of 38 min. Subsequently, the crude COPs were further purified via DEAE-52 and Sephadex G-100 chromatography to obtain a homogenous fraction (COPs-4-SG, 33.64 kDa) that contained galacturonic acid, arabinose, mannose, glucose, and galactose in a molar ratio of 34.82:14.19:6.75:13.48:12.26. The structure of COPs-4-SG was also characterized with UV–vis, fourier-transform infrared spectroscopy (FT–IR), atomic force microscopy (AFM), scanning electron microscopy (SEM), Congo-red test, and circular dichroism (CD). The findings provide a feasible way for the extraction, purification, and optimization of polysaccharides from plant resources     

基于粒子群优化支持向量机的太阳电池温度预测

建立通用而精确的太阳电池热模型对光伏系统的建模、输出功率与转换效率的损失分析至关重要. 基于复杂的太阳电池温度机理, 分别研究了太阳电池温度的稳态热模型(steady state thermal model, SSTM)和支持向量机(support vector machines, SVM) 方法建立的精确预测热模型. 首先, 基于空气温度、太阳辐射强度、风速3个最主要因素与太阳电池温度的近似线性关系, 在已有SSTM的基础上, 建立并校正了太阳电池的SSTM并采用差分进化算法提取模型的未知参数. 其次, 为提高SVM的模型预测精度, 采用粒子群优化(particle swarm optimization, PSO) 算法对SVM的核参数和惩罚因子进行动态寻优, 在确定输入/输出样本集并划分训练集和测试集的基础上, 建立了基于粒子群优化支持向量机(PSO-SVM)的太阳电池温度精确预测热模型. 最后, 搭建实验平台, 在实验操作过程中减弱空气湿度、太阳入射角和热迟滞效应等因素对太阳电池温度的耦合. 通过实验对比表明, 建立的预测热模型性能可靠、全面、简洁, 其参数寻优算法优于遗传算法和交叉校验法, 模型预测精度优于反向传播神经网络(back propagation neural network) 和SSTM.     

Hydrodynamic cavitation degradation of Rhodamine B assisted by Fe3+-doped TiO2: Mechanisms,geometric and operation parameters

In this paper, a novel method, hydrodynamic cavitation (HC) combined with Fe³⁺-doped TiO₂, for the degradation of organic pollutants in aqueous solution is reported. The venturi tubes with different geometric parameters (size, shape and half divergent angle) are designed to obtain a strong HC effect. The structure, morphology and chemical composition of prepared Fe³⁺-doped TiO₂ as catalyst are characterized via using XRD, SEM, TEM, XPS, UV-vis DRS and PL methods. The effects of added TiO₂ (heat-treated at different temperatures for different times) and Fe³⁺-doped TiO₂ (with different mole ratios of Fe and Ti) on the HC catalytic degradation of RhB are discussed. The influences of operation parameters including inlet pressure, initial RhB concentration and operating temperature on the HC catalytic degradation of RhB are studied by Box-Behnken design (BBD) and response surface methodology (RSM). Under 3.0 bar inlet pressure for 10 mg/L initial concentration of RhB solution at 40 °C operating temperature in the presence of Fe³⁺-doped TiO₂ with 0.05:1.00 M ratio of Fe and Ti, the best HC degradation ratio can be obtained (91.11%). Furthermore, a possible mechanism of HC degradation of organic pollutants in the presence of Fe³⁺-doped TiO₂ is proposed. Perhaps, this study may provide a feasible method for a large-scale treatment of dye wastewater.     

Ultrasound-assisted extraction of saffron bioactive compounds; separation of crocins,picrocrocin, and safranal optimized by artificial bee colony

In this work, a four-factor five-level full factorial central composite design (CCD) was used to optimize the ultrasound-assisted extraction (UAE) of saffron major components, namely picrocrocin, safranal and crocin. The process parameters included ethanol concentration (0–100%), extraction time (2–10 min), duty cycle (0.2–1.0) and ultrasonic amplitude (20–100%). The extracted compounds were measured both by spectrophotometry and chromatography techniques. The results revealed that the middle concentrations of ethanol and relatively long process durations along with high duty cycles and ultrasonic amplitudes had the most profound impact on the yields of the extracted bioactives. UAE was optimized using response surface methodology (RSM) and artificial bee colony (ABC); a comparison between these methods indicated their optimization power was approximately the same. According to the RSM analysis, an ethanol concentration of 58.58%, extraction time of 6.85 min, duty cycle of 0.82 and amplitude of 91.11% were the optimum extraction conditions, while the optimal conditions resulting from ABC were 53.07%, 7.32 min, 0.93 and 100% for the UAE variables respectively. Finally, HPLC analysis was carried out on the UAE optimum extract resulting from RSM. Four crocetin esters were detected in the optimal extract.     

Optimization of the synthesis parameters of high surface area ceria nanopowder prepared by surfactant assisted precipitation method

Response surface methodology (RSM) has been used to optimize the critical parameters responsible for higher surface area of ceria nanopowder prepared by surfactant assisted precipitation method. A three-level central composite design (CCD) was used to optimize pH, CTAB/metal molar ratio and calcination temperature. A quadratic model between response and the independent parameters was developed and the response surface model was tested with analysis of variance (ANOVA). The optimum operating conditions determined were a pH value of 9.4, CTAB/metal molar ratio of 0.5 and calcination temperature of 266 °C. Under these optimal conditions maximum surface area of 158 m²/g has been achieved.     

Optimization of the ultrasonic assisted removal of methylene blue by gold nanoparticles loaded on activated carbon using experimental design methodology

The present study was focused on the removal of methylene blue (MB) from aqueous solution by ultrasound-assisted adsorption onto the gold nanoparticles loaded on activated carbon (Au-NP-AC). This nanomaterial was characterized using different techniques such as SEM, XRD, and BET. The effects of variables such as pH, initial dye concentration, adsorbent dosage (g), temperature and sonication time (min) on MB removal were studied and using central composite design (CCD) and the optimum experimental conditions were found with desirability function (DF) combined response surface methodology (RSM). Fitting the experimental equilibrium data to various isotherm models such as Langmuir, Freundlich, Tempkin and Dubinin–Radushkevich models show the suitability and applicability of the Langmuir model. Analysis of experimental adsorption data to various kinetic models such as pseudo-first and second order, Elovich and intraparticle diffusion models show the applicability of the second-order equation model. The small amount of proposed adsorbent (0.01 g) is applicable for successful removal of MB (RE > 95%) in short time (1.6 min) with high adsorption capacity (104–185 mg g⁻¹).     

Modeling and analysis of simultaneous laser transmission welding of polycarbonates using an FEM and RSM combined approach

In this paper, simultaneous laser transmission welding process is systematically investigated via process modeling, using an FEM and RSM combined approach. The objective of the present research is to study the effects of process parameters on the temperature field and weld bead dimensions. The thermal field is simulated by solving a three dimensional transient heat diffusion equation with temperature dependent material properties using the ANSYS^® multi-physics. Response surface methodology is then applied for developing mathematical models based on simulation results. The second order equations developed by RSM can predict the values of the responses with significant accuracy. The effect of parameters and their interactions on the responses are studied using the developed response surface models. The mathematical models are further used in search of the optimal process window for obtaining an acceptable weld. The graphical optimization results into a couple of overlay contours plots, which allow quick visual inspection of the area of feasible response values in the factor space to choose the favorable welding parameter combination.     

An experimental study on the characterization of electric charge in electrostatic dust removal

Automatic dust removal using the electrostatic forces of electrodynamic screen (EDS) is an emerging method for mitigation of energy yield losses caused by dust accumulation on solar collectors. Both electric field distribution and dust particles' charge acquired during the removal process play pivotal roles in thorough evaluation of EDS performance. Previous studies have comprehensively analyzed the electric field distribution in EDS. In this paper we have conducted a number of experiments to examine how two EDS design parameters, electrode width and inter-electrode spacing, and two operational parameters, applied voltage and relative humidity, affect dust particles' charge. Sixteen EDS prototypes in two sets were developed and tested in a laboratory environment to study the acquired charge by dust particles via charge-to-mass ratio measurements. It has been shown that the charge-to-mass ratio is directly affected by the electric field intensity on an EDS surface. Furthermore, we have shown the detrimental impact of relative humidity on EDS performance. The results are advantageous in the evaluation of EDS design and its optimization to attain maximum dust removal efficiency.     

响应面方法的硅刻蚀工艺优化分析（英）

利用响应面分析方法优化了用于压力传感器硅敏感芯体的刻蚀操作条件。主要考虑了温度、KOH浓度和腐蚀时间三个操作参数，将它们的范围分别设定为40~60 ℃，0.4~0.48 mol/L 和 5~12.5 h，并设定各向异性腐蚀速率为响应值。通过建立二次方模型，分析这些参数的单独影响以及多个操作条件之间对腐蚀速率的相互交叠作用。分析结果表明:模型可以精确预测99%的响应值，相比于腐蚀时间，溶液浓度和工作温度对刻蚀速率的影响更为明显。     

Design and optimization of a cavitating device for Congo red decolorization: Experimental investigation and CFD simulation

The aim of this work is to perform design and optimization of a cavitating device based on CFD simulation. A set of operational and geometrical parameters such as convergence angle, divergence angle, length of throat, and inlet pressure that can affect the hydrodynamic cavitation phenomenon generating in a Venturi are evaluated through CFD simulation and experimental approaches. Response surface methodology (RSM) was employed to achieve the optimum geometrical configuration. The CFD results show that the maximum cavitation zone in the Venturi can be obtained when half angle of the convergence section, throat length and half angle of the divergence section are 22.7°, 4 mm, and 6.5°, respectively. A maximum decolorization of 38.8% has been obtained using the designed Venturi at cavitation number (Cv) of 0.12. Additionally, the results were compared to that of various orifice plates. A decolorization of 26.2% using 33 holes orifice plate and 11.55% in one hole orifice plate approved the superiority of the designed Venturi.     

Degradation of chlortetracycline in wastewater sludge by ultrasonication,Fenton oxidation,and ferro-sonication

Residual emerging contaminants in wastewater sludge remain an obstacle for its wide and safe applications such as landfilling and bio-fertilizer. In this study, the feasibility of individual ultrasonication (UlS) and Fenton oxidation (FO) and combined, Ferro-sonication processes (FO) on the degradation of chlortetracycline (CTC) in wastewater sludge was investigated. UlS parameters such as amplitude and sonication time were optimized by response surface methodology (RSM) for further optimization of FS process. Generation of highly reactive hydroxyl radicals in FO and FS processes were compared to evaluate the degradation efficiency of CTC. Increasing in the ratio of hydrogen peroxide and iron concentration showed increased CTC degradation in FO process; whereas in FS, an increase in iron concentration did not show any significant effect (p > 0.05) on CTC degradation in sludge. The estimated iron concentration in sludge (115 mg/kg) was enough to degrade CTC without the addition of external iron. The only adjustment of sludge pH to 3 was enough to generate in-situ hydroxyl radicals by utilizing iron which is already present in the sludge. This observation was further supported by hydroxyl radical estimation with adjustment of water pH to 3 and with and without the addition of iron. The optimum operating UlS conditions were found to be 60% amplitude for 106 min by using RSM. Compared to standalone UlS and FO at 1:1 ratio, FS showed 15% and 8% increased CTC degradation respectively. In addition, UlS of sludge increased estrogenic activity 1.5 times higher compared to FO. FS treated samples did not show any estrogenic activity.     

传热和内不可逆性对太阳能热机循环性能的影响

本文建立太阳能热机系统的一般循环模型，探讨传热和内不可逆性因素对其循环性能的影响；在不同的热传递规律下优化系统的各主要性能参数，对系统的效率、集热器的工作温度和热机中高、低温热交换器的传热面积比作了较深入的分析，从而获得一些有意义的新结论。     

选择性发射极晶体硅太阳电池的二维器件模拟及性能优化

利用PC2D二维模拟软件对选择性发射极晶体硅太阳电池(SE电池)进行了器件模拟和参数优化的研究.在对丝网印刷磷浆法制备的SE电池的实测典型电流-电压曲线实现完美拟合的基础上,全面系统地研究了栅线、基区、选择性发射区和背表面场层等的参数对电池性能的影响.模拟表明:基区少子寿命、前表面复合速度和背表面复合速度是对电池效率影响幅度最大的三个参数.在所研究的参数范围内,当基区少子寿命从50μs上升到600μs时,电池效率从18.53%上升到19.27%.低的前表面复合速度是使发射区方块电阻配比优化有意义的前提.要取得理想的电池效率,背表面复合速度需控制在500 cm/s以下.此外,对于不同的前表面复合速度,电池效率的最大值总是在50—90Ω/□的重掺区方阻、110—180Ω/□的轻掺区方阻的范围内取得.对不同的栅线数目,重掺区宽度与栅线间距之比为32%时,电池的效率最高.另外,在主栅结构保持较低面积比率的前提下,主栅数目的增加也可提高效率.最后,通过优化p型SE电池的效率可达到20.45%.     

Optimization of ultrasonic-assisted extraction of pomegranate (Punica granatum L.) seed oil

The effectiveness of ultrasonic-assisted extraction (UAE) of pomegranate seed oil (PSO) was evaluated using a variety of solvents. Petroleum ether was the most effective for oil extraction, followed by n-hexane, ethyl acetate, diethyl ether, acetone, and isopropanol. Several variables, such as ultrasonic power, extraction temperature, extraction time, and the ratio of solvent volume and seed weight (S/S ratio) were studied for optimization using response surface methodology (RSM). The highest oil yield, 25.11% (w/w), was obtained using petroleum ether under optimal conditions for ultrasonic power, extraction temperature, extraction time, and S/S ratio at 140 W, 40 °C, 36 min, and 10 ml/g, respectively. The PSO yield extracted by UAE was significantly higher than by using Soxhlet extraction (SE; 20.50%) and supercritical fluid extraction (SFE; 15.72%). The fatty acid compositions were significantly different among the PSO extracted by Soxhlet extraction, SFE, and UAE, with punicic acid (>65%) being the most dominant using UAE.