基于神经网络-遗传算法优化制氢工艺水碳比

根据某炼油厂制氢车间的生产数据,用人工神经网络(ANN)的反向传播(BP)算法建立了制氢装置转化生产中的水碳比神经网络预测模型,生产数据的检验表明,ANN方法能准确地关联和预报制氢装置转化生产中的水碳比,水碳比预测平均相对误差为2．83％;该神经网络预测模型用遗传算法优化并得到了最佳制氢工艺操作条件。     

应用经遗传算法优化的BP神经网络预测催化裂化装置焦炭产率

焦炭是催化裂化装置的主要副产物,准确预测催化裂化焦炭产率对提高装置的操作平稳度和经济效益具有重要意义。人工神经网络(ANN)具有强大的自学习和自适应能力,在非线性预测方面具有明显的优势。本研究将遗传算法(GA)与BP神经网络相结合,基于某炼厂催化裂化装置的生产数据,分别从原料、催化剂和操作条件3个方面选取28个关键影响参数建立了催化裂化焦炭产率预测模型,分别将BP神经网络和经遗传算法优化的BP神经网络(GA-BP)的预测结果与工业数据进行对比。结果表明,经遗传算法优化的预测模型无论在预测结果的准确性还是稳定性方面效果更好。最后,本研究还通过考察原料残炭、反应温度等单一关键参数对焦炭产率的影响,进一步证明了经遗传算法优化的BP神经网络预测模型的准确性。     

苯乙烯-马来酸酐本体共聚合过程的神经网络建模

人工神经网络(ANN)是一种有效的建模方法，尤其适用于机理复杂的化工过程，故应用ANN技术来研究苯乙烯-马来酸酐半连续本体共聚合过程的建模方法，并用原始实验数据训练BP网络，来预测本体共聚合过程的目标变量——反应转化率是合适的。由于标准BP训练算法的训练速度较慢，提出了一种改进的训练算法(marquardt算法)来提高网络的训练速度。结果表明，改进的训练算法提高收敛速度10倍以上，在不同的初始条件下，如停留时间5小时、聚合温度110-120℃和马来酸酐进料分量7％-10％，能得到满意的收敛点。在3个输入和1个输出(转化率)的情况下，估计结果的最大相对误差为10％-15％，平均相对误差小于5％。转化率的模型预测结果与原始实验数据具有良好的拟合。此方法可以有效地用于此类聚合过程的模型化。     

人工神经网络在材料开发中的应用研究进展

介绍了人工神经网络(ANN)的发展历程、模型特性与分类,以及反向传播(BP)神经网络模型及其改进算法,重点论述了ANN在高分子聚合反应过程和质量控制、成型加工工艺设计与条件优化、材料使用与服役性能预测方面的应用进展,以及在辅助性能表征与分析等方面的应用研究状况,并指出了ANN在未来新材料开发中应用的发展方向和亟待解决的问题。     

活性炭吸附甲基橙模拟废水预测模型研究

分别采用BP人工神经网络算法及多元线性回归法,以实验所得的36组数据为样本,建立了以吸附时间、活性炭投加量及甲基橙废水浓度为输入变量,以活性炭吸附处理后甲基橙溶液的吸光度为输出变量的吸附预测模型,并进行了两模型预测效果的对比。结果表明,BP神经网络模型获得了比多元线性回归更好的拟合预测效果。使用BP神经网络模型可以实现同时考虑三个操作因素条件下活性炭吸附特性的预测,而且预测结果与实验数据吻合度较高,其预测样本最大和最小相对偏差分别为2.92%和0.029%,残差绝对值小于0.050 5。     

航空发动机磨损趋势预测模型研究

文章讨论了神经网络的BP算法和遗传算法,提出用遗传算法来优化BP神经网络,应用遗传算法训练神经网络权重,实现网络结构的优化,用优化后的BP人工神经网络建立了航空发动机磨损故障趋势预测模型,利用发动机的光谱监测数据作为预测磨损趋势的特征参数,进行了模型的训练和预测试验,并将该模型预测结果与BP算法和多元线性回归法的预测结果进行了比较,证明了基于遗传算法的人工神经网络是航空发动机磨损故障趋势预测的一种理想方法。     

BP神经网络的发展及其在化学化工中的应用

人工神经网络（ANN）由于本身具有极强的非线性映射能力、容错性、自学习能力得到广泛的应用。基于反向传播算法（BP）的神经网络作为ANN重要组成部分,在涉及多种非线性因素建模时,相对于传统的反应机理建模显示出巨大的优势。虽然神经网络的发展几经繁荣与冷落,但目前在不同领域已经获得成功的应用。本文概述了BP神经网络的映射原理、缺点以及相应的改进方法,介绍其在催化剂设计、动力学模拟、理化特性估算、过程控制与优化、化学合成与反应性能预测的应用现状,展示了使用不同优化方法的改进模型在实验设计与优化方面取得的成果。最后指出未来BP神经网络的发展要进一步结合数据深度挖掘与机器学习等技术,为今后化学化工领域的研究提供强有力的工具。     

改进的BP网络在储层速敏损害预测中的应用

研究BP神经网络算法,建立一套神经网络预测模型,用于预测评价油气层的油气损害程度,为保护油气层拔高油气产量提供有力帮助.利用MATLAB 7.9.0中的BP神经网络算法Levenberg-Marquardt作为神经网络预测模型,以实验生产井的油气层数据作为训练样本,对该井区油气层进行预测准确率达到了95%.为提高油气的生产和推广神经网络系统在油气预测方面的应用起到了积极促进作用.     

KF/甲壳素固体碱催化剂的制备及用于生物柴油合成的研究1

本文用甲壳素为载体,使用浸渍法制备了负载型固体碱催化剂KF/甲壳素,将该催化剂用于生物柴油的制备,得到了较好的酯交换转化率.使用扫描电子显微镜(SEM)和X射线衍射谱(XRD)对所制备的催化剂进行了表征,结果表明KF能很好的负载在甲壳素上.考察了KF负载量,浸渍温度,陈化时间,煅烧温度等催化剂制备条件对生物柴油产率的影...     

基于遗传BP神经网络预测硫在高含硫气体中溶解度

为更精确地关联预测硫在高含硫气体中的溶解度,提出将遗传算法(GA)和LM-反向传播神经网络(LM-BP ANN)相结合的预测模型。设计了该模型的计算过程,讨论了模型参数的设置。以温度、压力和气体组分作为BP神经网络预测模型的输入变量,利用GA优化了BP神经网络的初始权值和阈值,采用遗传算法优化后的BP神经网络计算了元素硫在高含硫气体中的溶解度。结果表明,该模型训练结果与实测值之间的平均相对误差为5.90%,测试结果与实测值的平均相对误差为5.54%;该方法较BP神经网络模型具有预测精度高、收敛速度快的优点;该模型具有较好的模拟及内推、外推功能。     

Estimation of breakthrough time for water coning in fractured systems: Experimental study and connectionist modeling

Water coning in petroleum reservoirs leads to lower well productivity and higher operational costs. Adequate knowledge of coning phenomena and breakthrough time is essential to overcome this issue. A series of experiments using fractured porous media models were conducted to investigate the effects of production process and pore structure characteristics on water coning. In addition, a hybrid artificial neural network (ANN) with particle swarm optimization (PSO) algorithm was applied to predict breakthrough time of water coning as a function of production rate and physical model properties. Data from the literature combined with experimental data generated in this study were used to develop and verify the ANN‐PSO model. A good correlation was found between the predicted and real data sets having an absolute maximum error percentage less than 9%. The developed ANN‐PSO model is able to estimate breakthrough time and critical production rate with higher accuracy compared to the conventional or back propagation (BP) ANN (ANN‐BP) and common correlations. The presence of vertical fractures was found to accelerate considerably the water coning phenomena during oil production. Results of this study using combined data suggest the potential application of ANN‐PSO in predicting the water breakthrough time and critical production rate that are critical in designing and evaluating production strategies for naturally fractured reservoirs. © 2014 American Institute of Chemical Engineers AIChE J, 60: 1905–1919, 2014     

Comparison of Estimation Capabilities of the Artificial Neural Network with the Wavelet Neural Network in Lipase-Catalyzed Synthesis of Triethanolamine-Based Esterquats Cationic Surfactant

In this study, estimation capabilities of the artificial neural network (ANN) and the wavelet neural network (WNN) based on genetic algorithm were investigated in a synthesis process. An enzymatic reaction catalyzed by Novozym 435 was selected as the model synthesis process. The conversion of enzymatic reaction was investigated as a response of five independent variables; enzyme amount, reaction time, reaction temperature, substrates molar ratio and agitation speed in conjunction with an experimental design. After training of the artificial neurons in ANN and WNN, using the data of 30 experimental points, the products were used for estimation of the response of the 18 experimental points. Estimated responses were compared with the experimentally determined responses and prediction capabilities of ANN and WNN were determined. Performance assessment indicated that the WNN model possessed superior predictive ability than the ANN model, since a very close agreement between the experimental and the predicted values was obtained.     

Prediction of Timber Kiln Drying Rates by Neural Networks

The purpose of this exploratory work was to apply artificial neural network (ANN) modeling to the prediction of timber kiln drying rates based on species and basic density information for the hem-fir mix that grows along the local coastal areas. The ANN models with three inputs (initial moisture content, basic density, and drying time) were developed to predict one output, namely, average final moisture content. The back-propagation algorithm, the most common neural network learning method, was implemented for testing, training, and validation. Optimal configuration of the network model was obtained by varying its main parameters, such as transfer function, learning rule, number of neurons and layers, and learning runs. Accurate prediction of the experimental drying rate data by the ANN model was achieved with a mean absolute relative error less than 2%, thus supporting the powerful predictive capacity of this modeling method.     

咖啡因在水和乙醇中的溶解度及其关联

The solubility of caffeine in water and ethanol at 0—50 ℃ was measured using the laser method. The results were regressed with an empirical equation and simplified EOS correlation. A 2 - 2 - 1 backpropagation (BP) artificial neural network (ANN) model was selected from many other models. The prediction of interpolation and extrapolation of the data was made with trained 2 - 2 - 1 BP ANN model. The result was satisfactory.     

Prediction of Timber Kiln Drying Rates by Neural Networks

The purpose of this exploratory work was to apply artificial neural network (ANN) modeling to the prediction of timber kiln drying rates based on species and basic density information for the hem-fir mix that grows along the local coastal areas. The ANN models with three inputs (initial moisture content, basic density, and drying time) were developed to predict one output, namely, average final moisture content. The back-propagation algorithm, the most common neural network learning method, was implemented for testing, training, and validation. Optimal configuration of the network model was obtained by varying its main parameters, such as transfer function, learning rule, number of neurons and layers, and learning runs. Accurate prediction of the experimental drying rate data by the ANN model was achieved with a mean absolute relative error less than 2%, thus supporting the powerful predictive capacity of this modeling method.     

A Polymath Approach for the Prediction of Optimized Transesterification Process Variables of Polanga Biodiesel

An attempt has been made to employ an artificial neural network (ANN) combined with a genetic algorithm (GA) in MATLAB 7.0 for predicting the optimized reaction variables for maximum biodiesel production of polanga oil by the transesterification process. The developed ANN is a multilayer feed-forward back-propagation network (5-10-1) with five input, ten hidden and one output layers. The input variables are the molar ratio of ethanol to oil (X ₁ in % v/v), the catalyst concentration (X ₂ in % w/v), the reaction temperature (X ₃ in °C), the reaction time (X ₄ in min), the agitation speed (X ₅ in rpm) and the output parameter is biodiesel yield (% by weight) of polanga oil. The experimental data used in the developed ANN were obtained from response surface methodology (RSM) based on a central composite design. The trained ANN was tested using different training functions from the MATLAB to predict the best correlation coefficients of training, testing and validation. The data generated by trained ANN is used by GA with regards to the best response (for predicting biodiesel yield greater than predicted by RSM) for different combinations of variables (X ₁, X ₂, X ₃, X ₄, and X ₅) to attain optimization. The average biodiesel yield (by performing experiments under optimized conditions) of 92 % by weight was produced against the proposed value of 91.08 % by weight.