一种改进型混合遗传算法的分析

针对遗传算法和BP算法的特点,提出了一种在改进型遗传算法的基础上引入BP算法的混合遗传算法。仿真结果表明,该算法不仅保证了全局收敛性,而且大大提高了算法的收敛速度和稳定性。     

列队竞争算法在水污染控制系统规划中的应用

水污染控制系统规划可归结为非线性规划来求解,应用列队竞争算法对水污染控制系统规划问题的求解进行了研究,对文献中的实例求解结果表明,列队竞争算法的计算结果优于遗传算法的计算结果,列队竞争算法为求解水污染控制系统规划问题提供了一种有效方法.     

多产品间歇化工过程最优设计──混合模拟退火法

将模拟退火法（SimulatedAnnealing）与启发法（Heuristics）相结合,得到一种混合优化算法,应用于多产品间歇化工过程最优设计中,效果很好.该算法利用模拟退火的全局最优性保证了算法的全局最优,利用启发法加快了局部寻优进程,具有计算速度快、收敛性好等优点．同时,该算法自动确定了中间罐的最优数量和位置．算法对初值要求低,所需内存小,与严格数学规划法相比,相对误差小于0.5％．     

应用广义简约梯度算法增强遗传算法求解化工冶金相平衡

研究可靠的相平衡计算对化工冶金过程有很重要意义,本文采用广义简约梯度法（GRG）来增强遗传算法（GA）用于相平衡计算过程,在遗传算法演化快结束时引入GRG算子,演化结束后使用GRG精修结果,克服了GA局部搜索能力不强的缺点,加快了搜索速度.KCl-FeCl₂体系相平衡计算结果显示这种混合算法（Hybrid Algorithms）能够提高GA效率的同时保留了全局收敛的优点,因此其在化工冶金相平衡计算中将有广泛的应用前景.     

基于遗传算法的自适应最优阈值图像分割技术研究

本文通过对遗传算法搜索过程的改进与优化,采用了变异概率随适应度自动改变的自适应变异方法,提出了一种改进的基于遗传算法的自适应最优阈值图像分割算法。实验结果表明,该算法的收敛性能与分割效果都优于标准遗传算法。     

单台机器模糊加工时间排序问题的遗传算法

根据三角形模糊数的特性,在对总加工时间模糊度有约束的条件下,构造出NP-困难的1 fuzzy m in∑i=1Ci排序模型的遗传算法.并采用算例进行了仿真实验,验证算法的有效性.同时重点研究了设计的分段线性适应度函数的适用性.实例计算表明,通过调节适应度函数中的惩罚系数α和β,可以兼顾种群的多样性和促使搜索效率的提高.该算法的实际应用可行,且具有良好的收敛性和较高的搜索效率.     

全局优化搜索新算法--列队竞争算法(Ⅰ)解非线性和混合整数非线性规划问题

提出了一种称为列队竞争算法(LCA)的群体搜索算法,该算法在进化过程中始终保持着独立并行进化的家族,通过家族内部的生存竞争和家族间的地位竞争这两种不同的竞争方式,使群体快速进化到最优或接近最优的区域.根据家族的目标函数值大小排列成一个列队,按列队中家族地位的不同分配不同的搜索空间,使局部搜索与全局搜索达到均衡,同时,应用逐步收缩搜索空间技术加速收敛速度.数值计算表明,列队竞争算法的搜索效率优于遗传算法和模拟退火法等算法.     

全局优化搜索新算法——列队竞争算法(Ⅰ) 解非线性和混合整数非线性规划问题

提出了一种称为列队竞争算法(LCA)的群体搜索算法,该算法在进化过程中始终保持着独立并行进化的家族,通过家族内部的生存竞争和家族间的地位竞争这两种不同的竞争方式,使群体快速进化到最优或接近最优的区域.根据家族的目标函数值大小排列成一个列队,按列队中家族地位的不同分配不同的搜索空间,使局部搜索与全局搜索达到均衡,同时,应用逐步收缩搜索空间技术加速收敛速度.数值计算表明,列队竞争算法的搜索效率优于遗传算法和模拟退火法等算法.     

基于OpenMP的并行GA加速求解换热网络设计

为了提高化工过程系统中大规模优化问题的求解效率,提出了一个基于OpenMP系统的并行遗传算法。该算法实现了CPU主线程和GPU线程的同步并行化,达到了加速求解优化问题的目的。该算法在基本遗传算法的基础上引入了一系列调节和控制策略,用于改善算法的收敛性,提高算法获得最优解的概率。通过对算法中各项操作的并行性分析,设计了CPU-GPU异构系统下的并行遗传算法,并最终在OpenMP系统下得以实现。以2个不同规模的换热网络优化问题为例,验证算法的准确性和有效性。优化结果表明:基于OpenMP的并行遗传算法不但可以得到比文献中更优的换热网络设计方案,而且与串行的遗传算法相比具有明显的加速效果。而且加速比随着换热网络优化问题规模的增大而增大这一特征将有利于化工过程系统中各类优化问题的快速准确求解。     

逆向法测定酮洛芬对映体在Chiralpak AD柱上的吸附等温线

模拟移动床（SMB）色谱分离与纯化的操作过程复杂,对其进行设计与优化需要使用数值模拟方法,准确测定竞争型吸附等温线具有重要意义。采用逆向法确定了25℃下酮洛芬对映体在直链淀粉手性固定相（Chiralpak AD）上的竞争吸附等温线,先用高效液相色谱测得酮洛芬对映体在Chiralpak AD 柱上的过载流出曲线,再通过拟合实验测得的流出曲线确定吸附等温线模型及其参数。研究中采用平衡扩散模型描述酮洛芬对映体在色谱柱上流出的瞬态过程。参数拟合过程中,首先用非支配基因算法（NSGA-Ⅱ）在较广的参数空间内搜索吸附等温线模型参数,再以所得结果作为初值,使用Levenberg-Marquardt 算法（LMA）对参数进一步优化。比较了4种不同竞争吸附等温线模型对实验测得的流出曲线的拟合结果,其中五参数的Bi-Langmuir 模型拟合程度最好。测量了不同进料浓度和进料量条件下的流出曲线,并通过与模型预测结果的对照验证了所确定吸附等温线模型和参数。     

The applicability of the numerical algorithm for the evaluation of isosteric heat of adsorption

The calculation of isosteric enthalpy from an adsorption equation, and the comparison of theoretical enthalpy plot with the values measured calorimetrically is the fundamental condition for the verification of the correctness of an adsorption model. However, sometimes it is very difficult to get a simple analytical form of adsorption heat equation i.e. the isosteric heat of adsorption cannot be easily calculated from the thermodynamic van’t Hoff relation. For such cases we propose the new numerical algorithm. The applicability of the algorithm is checked out for two cases of the D’Arcy and Watt water adsorption isotherm equations. It is shown that the algorithm can be successfully applied for the thermodynamic verification of arbitrarily chosen adsorption isotherm equation, even possessing complicated form that disables simple analytical derivation of the heat formula.     

Single and competitive isotherms of phenol ando-cresol by pulsed-input method

There is a considerable industrial interest in both the scale-up and optimization of chromatographic operations used in the purification of fine chemicals and biomolecules. One of the major factors affecting the adsorption operation is the adsorption isotherm. Reversed-phase high-performance liquid chromatography (RP-HPLC) was used to measure the adsorption isotherm of phenol ando-cresol. From the experimental results, the retention times were decreased with increasing sample sizes, and the front of the peak was very stiff, so Langmuir adsorption isotherm was applied. Also Early-eluting component, phenol, in a mixture of the two components elutes faster than that in a pure component. Pulsed-injection method (PIM) was used to determine the two parameters of the Langmuir isotherm. The resulting parameters, a and b, were used to calculate the elution profiles of phenol ando-cresol in pure and mixed state. The agreement between the experimental data and calculated elution profiles was fairly good in a mixture as well as a pure component.     

Improved Estimation of the Langmuir Adsorption Isotherm Using Multiscale Filtering

Abstract

Adsorption isotherms play an important role in the design and analysis of adsorption processes. These isotherms are estimated empirically from measurements of adsorption process variables. Unfortunately, these measurements are usually contaminated with errors that degrade the accuracy of estimated isotherms. Therefore, these errors need to be filtered for improved isotherm estimation accuracy. Multiscale wavelet-based filtering has been shown to be a powerful filtering tool. In this work, multiscale filtering is utilized to improve the estimation accuracy of the Langmuir adsorption isotherm in the presence of measurement noise in the data by developing a multiscale isotherm estimation algorithm. The idea behind the algorithm is to use multiscale filtering to filter the data at different scales, use the filtered data from all scales to construct multiple isotherms, and then select among all scales the isotherm that best represent the data based on a cross-validation mean squares error criterion. The developed multiscale isotherm estimation algorithm is shown to outperform the conventional time-domain estimation method through a simulated example.     

槲皮素粗品吸附特性的测定与保留时间的预估

吸附等温线表示了组分在固定相和流动相两相之间浓度平衡的状态,对工艺设计和色谱过程模拟也有很重要的作用。前沿分析法是测定吸附等温线的较为准确、快速和经济的方法之一。该文的主要目的是利用前沿分析法测定槲皮素粗品的吸附等温线,并以此为基础,计算出保留时间,再与实验中的保留时间进行比较。实验中,选择了测定吸附等温线的条件,在选定条件的基础上,测定了3种不同槲皮素样品的吸附等温线,将它们的吸附特性进行了比较。结果表明,用单组分近似处理槲皮素粗品的吸附等温线是合理的,与标品及生化试剂测定的结果比较,符合多组分吸附竞争特性,合理地反映了杂质对吸附特性的影响。结果表明,在制备条件下通过计算得到的保留时间与实验测得的保留时间基本相符。因此,该文的方法可以作为优化槲皮素分离条件的基础。     

Removal of diclofenac from aqueous solution with multi-walled carbon nanotubes modified by nitric acid☆

Modified multi-walled carbon nanotubes (MWCNTs) were used as adsorbents for removal of diclofenac. The re-action conditions were examined. Langmuir, Freundlich, Temkin, and Dubinin–Radushkevich isotherm models were applied to determine appropriate equilibrium expression. The results show that the experimental data fit the Freundlich equation well. Thermodynamic parameters show that the adsorption process is spontaneous and exothermic. The kinetic study indicates that the adsorption of diclofenac can be well described with the pseudo-second-order kinetic model and the process is controlled by multiple steps.     

AN EVALUATION OF ISOTHERMS IN THE DESCRIPTION OF COMPETITIVE ADSORPTION EQUILIBRIA

Since adsorption isotherm equations are widely used in the industry to model adsorption on substances like activated carbon, an investigation was done to determine the applicability of three of these equations, viz, the multi-component Freundlich, multi-component Langmuir and the isotherm equation proposed by Fritz and Schluender. Based on statistical thermodynamic principles a discrete adsorption model was recently proposed. This model was used to create sets of binary adsorption data with some non-ideal characteristics. These data sets were used to evaluate the isotherm equations

It was found that the Langmuir isotherm gave the best fits, except where the visible adsorption energy changes with the surface loading or where selective adsorption occurs. Under these conditions, the Freundlich equation or that proposed by Fritz and Schluender should be used. It is recommended that these equations should be used to model low coverage-low concentration regions, while the high coverage-high concentration regions should be modelled using the Langmuir isotherm if possible

Some recommendations are made in connection with the procedure to estimate parameters for these isotherm equations.     

磁性壳聚糖/β-环糊精复合微球的制备及其吸附性能

以反相悬浮交联法制备磁性壳聚糖/β-环糊精复合微球。用光学显微镜、红外光谱仪、振动样品磁强计(VSM)对微球进行了表征,并研究其对模型蛋白(木瓜蛋白酶)的吸附行为。结果表明,微球为完整的球形,具有良好的磁响应性。模型蛋白在微球上的吸附关系既可用Langmuir方程描述,又可用计量置换吸附Freundlich方程描述,且更符合Freundlich方程描述;聚丙烯酰胺凝胶电泳(SDS-PAGE)结果表明,吸附的模型蛋白能从磁性粒子表面完整地脱附下来。     

逆向法测定氨氯地平在色谱柱Chiralpak OD-H上的竞争吸附等温线

使用逆向法测定氨氯地平在色谱柱Chiralpak OD-H上的竞争吸附等温线,先用泵进样的方式在高效液相色谱上测定氨氯地平的过载流出曲线,再选用5参数Bi-langmuir吸附等温线模型对过载流出曲线进行拟合,确定吸附等温线模型及模型参数,并验证参数准确性。     

前沿分析法测定葡萄糖在制备色谱柱上的吸附等温线

吸附等温线对模拟移动床色谱操作参数的模拟和优化具有重要的指导意义。以前沿分析法测定65℃下葡萄糖在离子树脂色谱柱上的吸附等温线,实验结果表明该行为符合anti-langmuir吸附模型。用所求模型参数预测脉冲实验,模拟结果较好,验证了测定的模型参数准确可靠。