约束优化问题的改进混合遗传算法

提出了罚函数与修复的混合策略,改进了罚函数,给出了种群早熟度评价指标,对遗传算法的交叉算子进行了改进,解决了单一使用罚函数方法求约束优化问题所遇到的困难,方便了遗传算法在约束优化问题中的应用,提高了遗传算法在机械及工程中应用的适应性。数值实验证明,该方法比传统的遗传算法处理约束优化问题效率高。     

离散粒子群算法的波纹管优化设计研究

为了解决波纹管所涉及的非线性约束离散变量的优化设计问题,文中尝试将粒子群算法与惩罚函数法相结合,建立新型离散粒子群算法,实现离散变量与连续变量之间的转化。提出了一种新的离散惩罚因子更新策略,以保证离散解的精度及算法的收敛性。通过著名的容器设计算例验证,文中方法优于文献方法。用该方法对波纹管工程实例进行优化设计,优化目标值比在用产品提高了79.96%,且与理论值接近,离散解的精度满足要求,进一步证明了该方法在求解波纹管工程非线性约束离散变量优化设计问题时的有效性。     

换热网络填充函数法的全局优化

换热网络全局优化问题属于混合整数非线性规划范畴,其难点是目标函数和约束条件呈现为严重的非线性和非凸特性,局部最优解陷阱星罗棋布.针对其全局优化的难点,应用一种变换函数的全局优化方法--填充函数法,对换热网络进行全局优化.通过具体的填充函数对某特定算例进行求解表明,通过不断的交替优化,填充函数能够使换热网络目标函数跳出局...     

混沌搜索方法及其在化工过程优化中的应用

提出利用混沌搜索方法结合精确不可微罚函数求解约束优化问题的新方法 ,并将该方法用于闪蒸过程优化 .结果表明 ,该方法算法简单 ,实现容易 ,求解精度和可靠性较高 ,是解决化工优化问题的有效方法 .     

分级优化用于边值固定的化工动态优化问题

针对边值固定的化工动态优化问题, 提出了分级优化策略, 包括约束优先与目标优先两种方案, 它们的基本思想是将原问题转化为一系列的边值无约束问题, 采用目前成熟的优化算法加以集成即可实现. 对于控制变量受箱型约束的问题, 采用三角函数转换将其转化为控制无约束问题. 分级优化策略避免了罚函数策略的缺陷. 实例研究显示了分级优化策略能以足够的精度满足边值约束, 三角函数转换法是可行的.     

Optimization-based design of reactive distillation columns using a memetic algorithm

The design optimization of reactive distillation columns (RDC) is characterized by complex nonlinear constraints, nonlinear cost functions, and the presence of many local optima. The standard approach is to use MINLP solvers that work on a superstructure formulation where structural decisions are represented by discrete variables and lead to an exponential increase in the computational effort. The mathematical programming (MP) methods which solve the continuous sub-problems provide only one local optimum which depends strongly on the initialization. In this contribution a memetic algorithm (MA) is introduced and applied to the global optimization of four different formulations of a computational demanding real-world design problem. An evolution strategy addresses the global optimization of the design decisions, while continuous sub-problems are efficiently solved by a robust MP solver. The MA is compared to MINLP techniques. It is the only algorithm that finds the global solution in reasonable times for all model formulations.     

PTFE间歇聚合反应过程变周期动态经济优化控制

聚四氟乙烯(PTFE)间歇聚合生产模式可满足小批量、多用途以及高质量产品的市场需求。针对PTFE聚合过程存在强非线性和大时滞特性,提出了一种基于自由终端的动态经济优化控制方法。首先,将生产周期作为一个自由度纳入优化变量建立动态经济优化问题,采用改进控制变量参数化方法,控制输入被离散为可变长度的片状序列,便可将动态经济优化问题转换为非线性规划(NLP)问题;然后,采用基于梯度下降的内点罚函数法求解NLP问题,通过变周期预测时域的滚动优化控制方法优化控制输入和终端时间;最后将提出的变周期动态经济优化控制与传统PI控制、非线性模型预测控制进行对比测试分析,仿真结果表明本方法单位经济效益更高,生产周期更短,突显了间歇生产的灵活性。     

PTFE间歇聚合反应过程变周期动态经济优化控制

聚四氟乙烯(PTFE)间歇聚合生产模式可满足小批量、多用途以及高质量产品的市场需求。针对PTFE聚合过程存在强非线性和大时滞特性,提出了一种基于自由终端的动态经济优化控制方法。首先,将生产周期作为一个自由度纳入优化变量建立动态经济优化问题,采用改进控制变量参数化方法,控制输入被离散为可变长度的片状序列,便可将动态经济优化问题转换为非线性规划(NLP)问题;然后,采用基于梯度下降的内点罚函数法求解NLP问题,通过变周期预测时域的滚动优化控制方法优化控制输入和终端时间;最后将提出的变周期动态经济优化控制与传统PI控制、非线性模型预测控制进行对比测试分析,仿真结果表明本方法单位经济效益更高,生产周期更短,突显了间歇生产的灵活性。     

考虑中间换热器的能量集成精馏序列合成

针对考虑中间换热器（IHE）的精馏序列合成问题,提出基于随机优化策略的能量集成非清晰精馏序列（IHE-HIDSs）合成方法。通过对精馏序列分离任务合并处引入二元0/1变量表示是否存在IHE,以精馏序列的年总成本（TAC）为优化目标,建立了该合成问题的隐式混合整数非线性规划模型（MINLP）,通过模拟退火和粒子群优化（SA-PSO）混合随机优化算法进行求解。为验证在精馏序列合成中同时考虑IHE的必要性以及所提出合成方法的有效性,对五组分醇类混合物和五组分烷烃类混合物两个算例的精馏序列合成问题进行了研究。结果表明,相比同时考虑热耦合和能量集成的精馏序列,IHE-HIDS具有更低的TAC。此外,所提出的方法可以在合理的计算时间内以高概率获得多个分离序列方案。     

Time optimal control of high dimensional systems by iterative dynamic programming

For time optimal control, the problem is first transformed into a finite dimensional optimization problem by using time stages of varying lengths to enable accurate switching, and then solved by iterative dynamic programming. In high dimensional systems care is necessary to ensure convergence to the global optimum. Incorporating penalty functions into the performance index and using an adequate number of stages can yield the global optimum. The use of a continuation approach, where the number of stages in an intermediate solution is systematically increased, appears to be more effective. Three linear systems are used to develop and to test the approaches.     

基于Kriging代理模型的稳健优化设计

稳健优化设计需要进行不确定性分析,优化过程比较费时。为提高计算效率,提出了基于Kriging代理模型的稳健优化设计方法。该方法结合双重Kriging代理模型和多点加点准则进行稳健优化设计。双重Kriging代理模型的建立,减小了不确定性分析的计算量,提高了计算效率。多点加点准则实现了序列的迭代优化,在保证计算效率的同时提高了对全局最优解的逼近程度。数学函数测试结果表明,与一般模拟基稳健优化方法相比,本文所提出的序列稳健优化方法在效率上有很大的提高。最后,考虑注塑工艺的不稳定性,对一盒式注塑制件的壁厚和工艺进行稳健优化,结果表明该稳健优化设计方法是有效的。     

A new optimization model and a customized solution method for natural gas production network design and operation

This article proposes to tackle integrated design and operation of natural gas production networks under uncertainty, using a new two‐stage stochastic programming model, a novel reformulation strategy, and a customized global optimization method. The new model addresses material balances for multiple key gas components, pressure flow relationships in gas wells and pipelines, and compressor performance. This model is a large‐scale nonconvex mixed‐integer nonlinear programming problem that cannot be practically solved by existing global optimization solvers or decomposition‐based optimization methods. With the new reformulation strategy, the reformulated model has a better decomposable structure, and then a new decomposition‐based global optimization method is developed for efficient global optimization. In the case study of an industrial naturals production system, it is shown that the proposed modeling and optimization methods enable efficient solution, and the proposed optimization method is faster than a state‐of‐the‐art decomposition method by at least an order of magnitude. © 2016 American Institute of Chemical Engineers AIChE J, 63: 933–948, 2017     

粒子群算法求解边值固定的化工动态过程优化问题

针对化工过程系统优化中广泛存在着边值固定的动态优化问题,该问题的求解数学上还没有有效的方法,现今的方法之一是将问题转化为多目标优化问题.本文在粒子群优化(PSO)算法的基础上,提出在PSO算法中加入惩罚项,同时对局部极值与全局极值作进一步的调整,使PSO算法适用于求多目标优化问题理想有效解,该算法对多目标问题起到边优化边求理想有效解的功效;即只用一步即可求理想有效解,这使得在求解速度上大为加快.最后将其用于间歇反应器的最佳反应温度边值固定动态优化控制的实际运用中,取得良好效果.     

萃取精馏分离异丙醇-水共沸体系的模拟与优化

对异丙醇-水共沸体系的萃取精馏过程进行模拟与优化。以乙二醇为萃取剂,基于UNIFAC模型,使用Aspen Plus化工模拟软件中的RadFrac模块进行萃取精馏模拟,并利用灵敏度分析模块对各工艺参数进行灵敏度分析与优化。结果表明,以乙二醇做萃取剂分离异丙醇-水共沸体系是可行的。对于处理流量5000kg·h-1的异丙醇-水共沸溶液,精馏塔具有22块塔板时,原料进料位置在第16块塔板,萃取液进料位置在第3块塔板,摩尔回流比为1.4,萃取剂与原料的进料比为2∶1,塔顶异丙醇质量分数可达0.9981,萃取精馏塔的分离效果和热负荷达到最优。模拟和优化的结果对工业化设计和生产具备指导意义。     

模块环境下的filter-SQP用于过程优化

引言 20世纪70年代中期以来,经过许多学者的努力,SQP法成为求解非线性规划(NLP)问题最有效的方法之一.     

基于信赖域算法的精馏塔优化

从结构优化角度建立精馏塔优化的混合整数非线性规划(MINLP)模型,为了消除整数变量,引入绕流效率将MINLP问题转化为非线性规划(NLP)问题。针对得到的NLP问题提出一种优化方法,在该方法中采用结构优化中常用的信赖域优化算法进行求解,并应用虚拟瞬态连续性方程辅助优化中的稳态模拟。采用提出的优化方法对3个精馏系统进行设计优化,以不同初始值开始,均可得到令人满意的优化结果,表明所提优化方法具有良好的稳健性,对于较复杂的部分热耦合精馏过程仍然可以有效优化求解;信赖域算法在精馏塔优化中也表现出良好的收敛性。     

A global optimization method based on multi-unit extremum-seeking for scalar nonlinear systems

Finding the global optimum of a nonlinear function is a challenging task that could involve a large number of functional evaluations. In this paper, an algorithm that uses tools from the domain of extremum-seeking is shown to provide an efficient deterministic method for global optimization. Extremum-seeking schemes typically find the local optimum by controlling the gradient to zero. In this paper, the multi-unit framework is used, where the gradient is estimated by finite difference for a given offset between the inputs. The gradient is pushed to zero by an integral controller. It is shown that if the offset is reduced to zero, the system can be made to converge to the global optimum of nonlinear continuous static, scalar maps. The result is extended to constrained problems where a switching control strategy is employed. Several illustrative examples are presented and the proposed method is compared with other methods of global optimization.     

基于流程模拟器和列队竞争算法的精馏操作优化

精馏是高耗能的操作单元,对其进行操作优化是企业实现节能降耗、提高经济效益的有效手段。本文提出列队竞争算法与流程模拟软件相结合的精馏操作优化方法,通过MATLAB-Aspen Plus的接口工具调用Aspen Plus模拟精馏操作过程,得到目标函数值,使用列队竞争算法对其进行操作条件的优化。将所提出的方法应用于某石化企业催化裂化主分馏塔的操作优化,其中目标函数值同时考虑了热能利用与产品分布,优化求解得到了总体效益最大的优化操作方案。     

Design stage optimization of an industrial low-density polyethylene tubular reactor for multiple objectives using NSGA-II and its jumping gene adaptations

Design stage optimization of an industrial low-density polyethylene (LDPE) tubular reactor is carried out for two simultaneous objectives: maximization of monomer conversion and minimization of normalized side products (methyl, vinyl, and vinylidene groups), both at the reactor end, with end-point constraint on number-average molecular weight (M_n,f) in the product. An inequality constraint is also imposed on reactor temperature to avoid run-away condition in the tubular reactor. The binary-coded elitist non-dominated sorting genetic algorithm (NSGA-II) and its jumping gene (JG) adaptations are used to solve the optimization problem. Both the equality and inequality constraints are handled by penalty functions. Only sub-optimal solutions are obtained when the equality end-point constraint on M_n,f is imposed. But, correct global optimal solutions can be assembled from among the Pareto-optimal sets of several problems involving a softer constraint on M_n,f. A systematic approach of constrained-dominance principle for handling constraints is applied for the first time in the binary-coded NSGA-II-aJG and NSGA-II-JG, and its performance is compared to the penalty function approach. A three-objective optimization problem with the compression power (associated with the compression cost) as the third objective along with the aforementioned two objectives, is also studied. The results of three-objective optimization are compared with two different combinations of two-objective problems.     

注射模浇口数目和位置的优化设计

给出一种注塑模具浇口位置和数目的优化设计方法.为达到减少塑件翘曲变形和熔接线的目的,以平衡充填和浇口数目最少为优化目标,以最大注射压力为约束条件,将浇口位置坐标作为设计变量,并根据浇口位置在充填数值模拟中对浇口数目和注射流率进行处理,从而可以同时优化浇口数目及其位置,优化求解采用遗传算法.算例表明,提出的优化模型和算法是有效的.