复杂体系化学平衡组成计算方法

The chaos-Monte Carlo algorithm (CMCA) was proposed for solving chemical equilibrium of complex system. By introducing random well-distributed points into the Monte Carlo algorithm, this new approach showed good convergent probability and high-speed. Equilibrium composition of some complex systems, such as methanol synthesis, ammonia oxidation, and Claus process were calculated. The results showed good agreement with Liu Xiaodi‘s and Xu Jinhuo‘s calculations. Compared with the gradient method, the genetic algorithm and the modified genetic algorithm, the CMCA is simple, general and insensitive to initial value. It is an efficient algorithm based on the theory of minimization of Gibbs free energy to solve chemical equilibrium of complex system.     

非理想多相共存体系的平衡计算

对于给定温度和压力的系统,平衡状态时其吉布斯自由能最小。根据热力学基本关系式,在多组分体系中元素和电荷守恒的限制条件下,最小化吉布斯函数,通过SQP方法来求解此有约束的优化问题,通过迭代法求解反应后的温度。该方法可用于复杂的非理想、多相流体、电解液或非电解液混合物的相平衡计算,平衡计算结果包括温度、密度、组分浓度等。对于某新型热动力系统中使用的一种含铝火药,应用本文方法,获得了化学平衡计算结果。     

基于改进人工鱼群算法优化的BP神经网络预测控制系统

为了使传统的BP神经网络预测控制的收敛速度更快、准确率更高,提出一种改进的人工鱼群算法。分别用BP神经网络、PSO-BP神经网络和IAFSA-BP神经网络来优化预测控制系统的建模部分和滚动优化部分,并进行仿真试验,结果表明:IAFSA-BP神经网络优化后的预测模型精度更高,并且滚动优化部分的响应速度加快,控制系统更稳定。     

人工鱼群算法在气固流化床流型识别中的应用

准确识别流型是流化床气固二相流参数检测的一项重要内容,实验是在流化床气固二相流实验系统上进行的。首先,采集5种典型流型的压力波动信号,并以信号的统计参量作为流型特征。然后,将样本送入经过人工鱼群优化的BP神经网络进行训练。人工鱼群(AFSA)是一种新型的智能优化算法,具有全局收敛性好,鲁棒性强,对初值不敏感等特点,通过优化神经网络的权值使识别率得到明显提高,实现了气固流化床典型流型的快速、准确识别。实验结果表明,该方法对气固流化床5种典型流型的识别率达到97%,为在线识别气固流化床流型提供了一种新的有效方法。     

混合整数非线性规划法求解多组分复杂体系相平衡问题

基于Gibbs自由能最小化原理,提出一种求解多组分复杂体系相平衡问题的混合整数非线性规划(MlNLP)方法.通过建立MlNLP模型,将相平衡计算问题转化为有约束的双层最优化问题,内层用来计算给定相组合结构下的平衡组成,外层则是搜索最优的相组合结构,整个求解过程通过遗传算法来实现.所建立的方法只需要求解最小化问题,就可以同时给出多相平衡时存在的相数、相态及各相组成.以苯-乙氰-水和甲醇合成两个体系的相平衡计算为例,结果表明该方法是可行和有效的.     

基于混合粒子群算法的复杂相平衡计算方法

对于含有两个部分互溶液相的相平衡问题,采用经典方法收敛困难或易陷于平凡解。为此根据最小Gibbs自由能原理,提出采用混合粒子群算法搜索全局最优解,计算得到系统的最小Gibbs自由能状态,实现复杂相平衡计算。通过改建目标函数,减少计算量,并引入组分相分率,将物料平衡约束转换为规范型立方空间的优化问题,适于粒子群算法搜索。在常规粒子群算法中引入Nelder-Mead单纯形操作,可显著提高搜优的速率和精度。将其应用于甲苯-水-苯胺液液平衡和苯-乙腈-水汽液液平衡计算,取得了良好的效果。     

基于人工鱼群优化的锅炉汽包水位模糊预测

介绍火电厂锅炉汽包水位在实际生产中的工作特点,将人工鱼群优化滚动、优化策略的广义预测控制算法和T-S模糊模型应用于汽包水位建模中,并将其作为广义预测控制的预测模型,研究基于模糊T-S模型的广义预测控制算法在汽包液位控制系统中的应用。在MATLAB仿真环境下对其控制效果和性能进行分析。     

基于鱼群算法的体育运动员高强运动损伤图像识别研究

运动员经过高强度的体育训练难免会受到损伤,在治疗时需要对其损伤图像进行识别,然而当前有些识别方法的效率和精确度不高,于是文章将研究基于鱼群算法的体育运动员高强运动损伤图像识别,首先对损伤部位轮廓进行提取,然后获得对损伤图像进行初步识别,最后基于鱼群算法对图像进一步识别.通过实验研究,与其他识别方式相比,基于鱼群算法的识...     

基于响应面模型与人工鱼群算法的汽车车门内饰柱注塑成型优化设计

汽车车门内饰柱一般为板型注塑件,在注塑加工过程中不同的注塑工艺参数对整个注塑件的质量和性能有非常大的影响。针对丙烯腈-丁二烯-苯乙烯塑料汽车车门内饰柱的翘曲变形的问题,首先利用响应面模型方法对注塑过程中对翘曲变形影响最大的4个参数：熔体温度、模具温度、保压压力、保压时间进行分析,并拟合得到4个工艺参数与翘曲变形量之间的回归方程。其次在分析所得的回归方程基础上结合人工鱼群算法对工艺参数组合及翘曲变形量进行寻优,最后将寻得的工艺参数组合通过软件仿真验证。结果表明,采用此优化方法后内饰柱翘曲变形下降14.2%,并且算法寻优结果与Moldflow仿真结果仅相差1.6%,证明优化方法在车门内饰柱注塑工艺优化过程中有较好的效果。     

人工鱼算法的重磁位场反演方法

位场反演是地球物理反演问题研究的主要内容之一,其任务为确定地质体的空间形体参数和物性参数。目前,局部和全局最优化技术结合是地球物理反演的热点。人工鱼群算法是源于对鱼群觅食行为而提出的一种新型群体智能优化算法,在多参数、非线性、多极值函数优化问题中具有较强的优越性。通过分析人工鱼群算法的原理,本文用该非线性算法实现了重磁位场反演,并且在理论模型的实验中,证明了算法的可行性。     

基于遗传算法和粒子群优化算法的电力系统无功优化

从数学的角度分析,电力系统无功优化是一个多变量、多约束、非连续性的混合非线性规划问题,因此,优化过程十分复杂.以减少有功网损为目标函数建立电力系统无功优化计算的数学模型,基于遗传算法和粒子群优化算法,提出一种新颖的混合策略来求解无功优化问题.IEEE 6和IEEE 14节点系统的仿真计算结果表明:与单一的遗传算法或粒子群优化算法相比,该混合策略在优化效果方面具有明显的优势.     

基于人工免疫算法的入侵检测系统

将人工免疫的理论运用到计算机入侵检测系统中。充分利用了人工免疫系统的分布性、自适应性、记忆性和高效性。为入侵检测系统的高误报率和缺乏自适应性的问题提供了一个可实用模型。     

含离子液体体系液液相平衡的计算

含有离子液体体系的液液平衡数据是离子液体实际应用最重要的基础数据之一。文中在扩展的NRTL方程中进一步引入了分子体积修正项,计算结果表明,该修正能更好地提高模型预测含离子液体体系的精度。因此,文中利用该模型关联了文献报道的多种常见离子液体和醇类二元体系,所有体系计算值与实验值的质量分数最大绝对误差小于3.5%,平均绝对误差小于1.5%;同时,文中利用拟合得到的二元模型参数,成功预测了23℃和50℃时水-正丁醇-[bmim]PF6三元体系的液液平衡相图。     

A concrete mix proportion design algorithm based on artificial neural networks

The concepts of five parameters of nominal water-cement ratio, equivalent water-cement ratio, average paste thickness, fly ash-binder ratio, grain volume fraction of fine aggregates and Modified Tourfar's Model were introduced. It was verified that the five parameters and the mix proportion of concrete can be transformed each other when Modified Tourfar's Model is applied. The behaviors (strength, slump, et al.) of concrete primarily determined by the mix proportion of concrete now depend on the five parameters. The prediction models of strength and slump of concrete were built based on artificial neural networks (ANNs). The calculation models of average paste thickness and equivalent water-cement ratio can be obtained by the reversal deduction of the two prediction models, respectively. A concrete mix proportion design algorithm based on a way from aggregates to paste, a least paste content, Modified Tourfar's Model and ANNs was proposed. The proposed concrete mix proportion design algorithm is expected to reduce the number of trial and error, save cost, laborers and time. The concrete designed by the proposed algorithm is expected to have lower cement and water contents, higher durability, better economical and ecological effects.     

The effect of isomerization on chemical equilibrium

A proof is given of the following statement: “If a set of isomeric forms is accessible to a chemical substance at equilibrium in a closed system (at given T and P, say) then the (relative) amount of the substance present at equilibrium is greater than it would be if only a strict subset of these forms were accessible”. The proof is restricted to ideal solutions. The statement is illustrated by calculations on the system consisting of benzene and the methyl benzenes to show the implications for equilibrium conversion and yield.     

Experimental study of chemical equilibrium and vapor-liquid equilibrium calculation for chemical-equilibrium states of the n-propanol-acetic acid-n-propyl acetate-water system

Chemical equilibrium data for the n-propanol-acetic acid-n-propyl acetate-water system at 303.15 K are presented. The results of UNIFAC-based modeling of the vapor-liquid equilibrium in the system at 303.15 and 313.15 K are reported.     

神经网络计算脂肪酸酯与超临界CO_2体系相平衡

用2×2×1结构的BP神经网络计算了脂肪酸酯 超临界CO2体系的液相相边界溶解度数据,用2×4×2结构的BP神经网络对相平衡数据进行了计算,计算结果比较令人满意。同时对神经网络计算过程中涉及的一些参数也进行了讨论。     

Localized Fisher discriminant analysis based complex chemical process monitoring

Complex chemical process is often corrupted with various types of faults and the fault‐free training data may not be available to build the normal operation model. Therefore, the supervised monitoring methods such as principal component analysis (PCA), partial least squares (PLS), and independent component analysis (ICA) are not applicable in such situations. On the other hand, the traditional unsupervised algorithms like Fisher discriminant analysis (FDA) may not take into account the multimodality within the abnormal data and thus their capability of fault detection and classification can be significantly degraded. In this study, a novel localized Fisher discriminant analysis (LFDA) based process monitoring approach is proposed to monitor the processes containing multiple types of steady‐state or dynamic faults. The stationary testing and Gaussian mixture model are integrated with LFDA to remove any nonstationarity and isolate the normal and multiple faulty clusters during the preprocessing steps. Then the localized between‐class and within‐class scatter mattress are computed for the generalized eigenvalue decomposition to extract the localized Fisher discriminant directions that can not only separate the normal and faulty data with maximized margin but also preserve the multimodality within the multiple faulty clusters. In this way, different types of process faults can be well classified using the discriminant function index. The proposed LFDA monitoring approach is applied to the Tennessee Eastman process and compared with the traditional FDA method. The monitoring results in three different test scenarios demonstrate the superiority of the LFDA approach in detecting and classifying multiple types of faults with high accuracy and sensitivity. © 2010 American Institute of Chemical Engineers AIChE J, 2011     

Computation of chemical equilibrium compositions II

A simple modification to a previously described search method for the computation of chemical equilibria is presented. The modification consists of an automatic correction for any drift which normally arises with the search method. The drift correction also obviates the need for starting estimates which obey atom balance conditions. The modified method is both faster and more convenient to use than the method described previously.