A Line Complex-Based Evolutionary Algorithm for Many-Objective Optimization

In solving many-objective optimization problems(MaO Ps),existing nondominated sorting-based multi-objective evolutionary algorithms suffer from the fast loss of selection pressure.Most candidate solutions become nondominated during the evolutionary process,thus leading to the failure of producing offspring toward Pareto-optimal front with diversity.Can we find a more effective way to select nondominated solutions and resolve this issue?To answer this critical question,this work proposes to evolve solutions through line complex rather than solution points in Euclidean space.First,Plücker coordinates are used to project solution points to line complex composed of position vectors and momentum ones.Besides position vectors of the solution points,momentum vectors are used to extend the comparability of nondominated solutions and enhance selection pressure.Then,a new distance function designed for high-dimensional space is proposed to replace Euclidean distance as a more effective distancebased estimator.Based on them,a novel many-objective evolutionary algorithm(MaOEA)is proposed by integrating a line complex-based environmental selection strategy into the NSGAⅢframework.The proposed algorithm is compared with the state of the art on widely used benchmark problems with up to 15 objectives.Experimental results demonstrate its superior competitiveness in solving MaOPs.

A Bi-population Cooperative Optimization Algorithm Assisted by an Autoencoder for Medium-scale Expensive Problems

This study presents an autoencoder-embedded optimization(AEO)algorithm which involves a bi-population cooperative strategy for medium-scale expensive problems(MEPs).A huge search space can be compressed to an informative lowdimensional space by using an autoencoder as a dimension reduction tool.The search operation conducted in this low space facilitates the population with fast convergence towards the optima.To strike the balance between exploration and exploitation during optimization,two phases of a tailored teaching-learning-based optimization(TTLBO)are adopted to coevolve solutions in a distributed fashion,wherein one is assisted by an autoencoder and the other undergoes a regular evolutionary process.Also,a dynamic size adjustment scheme according to problem dimension and evolutionary progress is proposed to promote information exchange between these two phases and accelerate evolutionary convergence speed.The proposed algorithm is validated by testing benchmark functions with dimensions varying from 50 to 200.As indicated in our experiments,TTLBO is suitable for dealing with medium-scale problems and thus incorporated into the AEO framework as a base optimizer.Compared with the state-of-the-art algorithms for MEPs,AEO shows extraordinarily high efficiency for these challenging problems,t hus opening new directions for various evolutionary algorithms under AEO to tackle MEPs and greatly advancing the field of medium-scale computationally expensive optimization.

基于代理模型估值不确定度的昂贵多目标优化问题研究

针对代理模型辅助的多目标优化算法中个体不确定度之间相互冲突的问题,本文提出个体每个目标估值不确定的填充准则,同时,为了减少训练模型消耗的计算资源,提出基于非支配排序的样本选择算法。为了验证该算法的可行性,采用DTLZ和WFG测试函数进行测试,得出结果与近些年发表5种具有代表性的同类型算法进行对比,结果说明该算法可以有效的解决昂贵高维高目标优化问题。

带隐藏约束昂贵黑箱问题的自适应代理优化方法

针对带隐藏约束的昂贵黑箱全局优化问题,提出采用自适应转换搜索策略的代理优化方法。在转换搜索子步中采用与已估值点个数相关的标准差在当前最优点附近通过随机扰动生成候选点,以更好地平衡局部搜索和全局搜索。为更好地近似真实黑箱目标函数,采用了自适应组合目标代理模型。在50个测试问题上进行了数值实验,计算结果说明了所提算法的有效性。

Novel PIO Algorithm with Multiple Selection Strategies for Many-Objective Optimization Problems

With the increase of problem dimensions,most solutions of existing many-objective optimization algorithms are non-dominant.Therefore,the selection of individuals and the retention of elite individuals are important.Existing algorithms cannot provide sufficient solution precision and guarantee the diversity and convergence of solution sets when solving practical many-objective industrial problems.Thus,this work proposes an improved many-objective pigeon-inspired optimization(ImMAPIO)algorithm with multiple selection strategies to solve many-objective optimization problems.Multiple selection strategies integrating hypervolume,knee point,and vector angles are utilized to increase selection pressure to the true Pareto Front.Thus,the accuracy,convergence,and diversity of solutions are improved.ImMAPIO is applied to the DTLZ and WFG test functions with four to fifteen objectives and compared against NSGA-III,GrEA,MOEA/D,RVEA,and many-objective Pigeon-inspired optimization algorithm.Experimental results indicate the superiority of ImMAPIO on these test functions.

基于财务智能化的高校财务报销流程优化研究

目前,我国高等教育发展极为迅速,各高校也在积极地扩大教学规模。在此过程中,高校财务部门的业务量有了显著的增加,由此也出现了财务报销时间长、财务人员供给不足等问题。究其原因,报销难主要是由于现有财务报销流程无法满足与日俱增的业务需求。为了解决这一问题,高校必须就现行财务报销流程进行升级优化,尝试运用互联网技术以实现财务报销智能化发展,从而切实提高财务管理水平。基于此,笔者就高校财务报销流程优化展开深入的探讨分析,在高校财务报销流程现状及存在问题的基础上,借助互联网技术构建账前预审、报销过程智能化的财务报销机制,以期为提高财务报销工作效率提供参考。

Evolutionary Computation for Expensive Optimization:A Survey

Expensive optimization problem(EOP) widely exists in various significant real-world applications. However, EOP requires expensive or even unaffordable costs for evaluating candidate solutions, which is expensive for the algorithm to find a satisfactory solution. Moreover, due to the fast-growing application demands in the economy and society, such as the emergence of the smart cities, the internet of things, and the big data era, solving EOP more efficiently has become increasingly essential in various fields, which poses great challenges on the problem-solving ability of optimization approach for EOP. Among various optimization approaches, evolutionary computation(EC) is a promising global optimization tool widely used for solving EOP efficiently in the past decades. Given the fruitful advancements of EC for EOP, it is essential to review these advancements in order to synthesize and give previous research experiences and references to aid the development of relevant research fields and real-world applications. Motivated by this, this paper aims to provide a comprehensive survey to show why and how EC can solve EOP efficiently. For this aim, this paper firstly analyzes the total optimization cost of EC in solving EOP. Then, based on the analysis, three promising research directions are pointed out for solving EOP, which are problem approximation and substitution, algorithm design and enhancement, and parallel and distributed computation. Note that, to the best of our knowledge, this paper is the first that outlines the possible directions for efficiently solving EOP by analyzing the total expensive cost. Based on this, existing works are reviewed comprehensively via a taxonomy with four parts, including the above three research directions and the real-world application part. Moreover, some future research directions are also discussed in this paper. It is believed that such a survey can attract attention, encourage discussions, and stimulate new EC research ideas for solving EOP and related real-world applications more efficiently.

A many-objective evolutionary algorithm based on decomposition with dynamic resource allocation for irregular optimization

The multi-objective optimization problem has been encountered in numerous fields such as high-speed train head shape design,overlapping community detection,power dispatch,and unmanned aerial vehicle formation.To address such issues,current approaches focus mainly on problems with regular Pareto front rather than solving the irregular Pareto front.Considering this situation,we propose a many-objective evolutionary algorithm based on decomposition with dynamic resource allocation(Ma OEA/D-DRA)for irregular optimization.The proposed algorithm can dynamically allocate computing resources to different search areas according to different shapes of the problem’s Pareto front.An evolutionary population and an external archive are used in the search process,and information extracted from the external archive is used to guide the evolutionary population to different search regions.The evolutionary population evolves with the Tchebycheff approach to decompose a problem into several subproblems,and all the subproblems are optimized in a collaborative manner.The external archive is updated with the method of rithms using a variety of test problems with irregular Pareto front.Experimental results show that the proposed algorithèm out-p￡performs these five algorithms with respect to convergence speed and diversity of population members.By comparison with the weighted-sum approach and penalty-based boundary intersection approach,there is an improvement in performance after integration of the Tchebycheff approach into the proposed algorithm.

Large-Scale Expensive Optimization with a Switching Strategy

Some optimization problems in scientific research,such as the robustness optimization for the Internet of Things and the neural architecture search,are large-scale in decision space and expensive for objective evaluation.In order to get a good solution in a limited budget for the large-scale expensive optimization,a random grouping strategy is adopted to divide the problem into some low-dimensional sub-problems.A surrogate model is then trained for each sub-problem using different strategies to select training data adaptively.After that,a dynamic infill criterion is proposed corresponding to the models currently used in the surrogate-assisted sub-problem optimization.Furthermore,an escape mechanism is proposed to keep the diversity of the population.The performance of the method is evaluated on CEC’2013 benchmark functions.Experimental results show that the algorithm has better performance in solving expensive large-scale optimization problems.

基本医疗保险异地就医联网结算现状及优化对策

基本医疗保险异地就医联网结算是近年来国家力推的一项民心工程,也是我国医疗保险制度改革和创新的重要组成部分。随着社会发展,交通的便利,流动人口增多和人口老龄化,选择去医疗资源较好的城市治疗的患者越来越多,异地联网结算是顺应社会发展必然趋势,目前我国已基本实现异地医疗费联网结算工作,但运行中仍存在一些问题。全国各地区医保政策不统一,报销待遇存在明显差别;医疗保险三目标准不统一,异地住院费用审核难度大;异地联网结算系统不稳定。因此本次研究根据目前运行现状分析原因,并提出相应的优化对策:减小各地区医保政策差异;进一步推进国家统一编码,加强信息平台建设;签订异地医保联网协议,加强医疗费用审核和医保基金监管。

基于Kriging模型的改进型NSGA-Ⅲ解决昂贵优化问题

在许多实际的优化问题中,为了进行适应度评估,其物理实验或数值仿真代价高昂,这给大多数现有的多目标进化算法(EAs)带来了巨大挑战。因此,文中提出了一种基于克里金模型辅助的改进参考点引导进化的优化算法,用于解决昂贵的超多目标优化问题。具体而言,根据种群的空间分布特征,借助关联点的熵差信息筛选参考点引导进化,以达到探索与开发的平衡。所提出的代理辅助进化算法(SAEA)使用克里金法来逼近每个目标函数,而无需进行原始昂贵的函数评估从而降低了计算成本。模型管理中采用一种纯指标填充采样准则,借助收敛性、多样性指标确定适当采样策略并使用昂贵目标函数对采样解进行真实评估以提升种群收敛与算法优化的效率。对具有3个以上目标的80个DTLZ与WFG基准测试问题进行了对比研究,证明了此算法的有效性和可行性。

惯性分组和重叠特征选择辅助的昂贵大规模优化算法

昂贵大规模优化问题存在着决策变量之间高度耦合、求解容易陷入局部最优以及目标评价昂贵等问题,导致在资源有限的情况下很难获得全局最优解。为此,基于合作型协同演化策略提出了一种惯性分组和重叠特征选择的方法来辅助求解昂贵大规模优化问题。首先,采用重叠特征选择技术将一个大规模优化问题分解为若干个低维的重叠子问题,并对每一个子问题进行独立的代理模型辅助的优化搜索。其次,将每个子问题搜索获得的潜力个体合成一个完整的解,对其使用昂贵目标函数进行评价。再次,算法还采用惯性分组技术控制优化过程中重新分组的频率以延长分组方案的开发周期,从而提升优化效果。最后,为了测试所提算法的性能,将其与求解昂贵大规模问题的3种优化算法在CEC2013的15个基准函数上获得的实验结果进行了对比。结果表明:所提算法在求解昂贵大规模优化问题上具有一定的竞争力,尤其适用于求解部分可分离、重叠或完全不可分离等问题。

求解高维昂贵多目标问题的约束型Dropout代理辅助进化算法

现实优化问题常需同时对多个冲突目标进行评估优化,由于评估过程多依赖大量复杂的仿真实验,从而产生计算代价昂贵的问题.代理模型辅助下的进化算法可在计算资源有限的情况下为此类问题提供有效的最优解集.但随着问题决策以及目标空间维度变高,则会衍生出诸多负面因素限制代理模型的预测精度.对此,提出一种基于约束型Dropout神经网络的代理辅助进化算法(Constrained Dropout Neural Network based surrogate-assisted Evolution Algorithm,CDNNEA),以约束型Dropout神经网络作为一种可扩展方案来增强代理模型在高维空间中的适用性,在模型管理部分中,构建种群个体收敛性以及多样性评判指标,自适应地选取引导代理模型更新的代表性个体.通过在DTLZ基准测试问题上进行实验,CDNNEA显示出相较其它先进算法性能表现最优或近似最优,同时将其应用于高维参数自适应优化的现实问题中.实验表明:提供的代表性解决方案投入实际应用时识别准确率均较优且模型计算量可控,验证出CDNNEA在高维昂贵类优化问题上的有效性.

Hybrid Meta-Model Based Design Space Differentiation Method for Expensive Problems

In this work,a hybrid meta-model based design space differentiation(HMDSD)method is proposed for practical problems.In the proposed method,an iteratively reduced promising region is constructed using the expensive points,with two different search strategies respectively applied inside and outside the promising region.Besides,the hybrid meta-model strategy applied in the search process makes it possible to solve the complex practical problems.Tested upon a serial of benchmark math functions,the HMDSD method shows great efficiency and search accuracy.On top of that,a practical lightweight design demonstrates its superior performance.

基于自适应分解的多任务协作型昂贵多目标优化算法

现实世界的工程优化问题通常需要同时优化多个冲突的目标,且这些目标函数的评估由于依赖仿真、物理实验而十分昂贵,这类问题被称为昂贵多目标优化问题.使用机器学习方法建立代理模型用于估计候选解的目标函数值是求解此类问题的一种有效手段.高斯代理模型适用于训练样本数较少的中小规模问题,且能提供评估的不确定性,因此常作为代理模型被应用于昂贵优化.分解是处理多目标优化问题的一种有效手段.一个多目标优化问题可被分解为多个单目标优化子问题,且多个子问题可被进一步划分为代理模型学习的一个目标任务.现有基于分解的昂贵多目标优化算法大多将固定数量的子问题静态地划分到同一任务,从而构造多个固定任务并对其建立多任务高斯代理模型进行求解.这未能充分利用数据的相关信息动态反映出任务间的相关性,限制了多任务高斯过程模型的预测精度以及优化算法的最终性能.为此,本文提出了一种自适应多任务多种群协作搜索算法(AMMCS).AMMCS使用相似性指标实时度量已评估的解集,获得子问题间的相关性,从而自适应地划分任务,提升多任务模型的预测质量.此外,AMMCS使用一个解集(种群)优化一个任务,并通过多种群的协作搜索实现多任务高斯模型的批量优化,提高了采样效率,提升了算法的收敛效率.通过AMMCS与六个代理辅助进化算法进行多组实验对比和分析,显示了AMMCS具有良好的性能.我们同时也设计实验验证了算法中自适应分解以及多种群协作搜索的有效性.

模型辅助的计算费时进化高维多目标优化

代理模型能够辅助进化算法在计算资源有限的情况下加快找到问题的最优解集,因此建立高效的代理模型辅助多目标进化搜索逐渐受到了重视.然而随着目标数量的增加,对每个目标分别建立高斯过程模型时个体整体估值的不确定度会随之增加.因此通过对模型最优解集的搜索探索原问题潜在的非支配解集,并基于个体的收敛性,种群的多样性和估值的不确定度,提出了一种新的期望提高计算方法,用于辅助从潜在的非支配解集中选择使用真实目标函数计算的个体,从而更新代理模型,能够在有限的计算资源下更有效地辅助优化算法找到好的非支配解集.在7个DTLZ基准测试问题上的实验对比结果表明,该算法在求解计算费时高维多目标优化问题上是有效的,且具有较强的竞争力.

基于径向空间划分的昂贵多目标进化算法

为了解决难以建立精确数学模型或者真实评估实验成本高昂的多目标优化问题,提出了一种基于径向空间划分的昂贵多目标进化算法.首先算法使用高斯回归作为代理模型逼近目标函数;然后将目标空间的个体投影到径向空间,结合目标空间和径向空间信息保留对种群贡献更高的个体;之后由径向空间中个体的位置分布决定下一步应该选择哪些个体进行真实评估;最后,采用一种双档案管理策略维护代理模型的质量.数值实验和现实问题上的结果表明,与5种先进算法相比,该算法在解决昂贵多目标优化问题时能够提供更高质量的解.

差分进化算法在平面扭簧设计中的应用

由于因变量和自变量的关系无法用显式函数表达,导致平面扭簧的设计优化问题都是昂贵黑箱问题。差分进化算法是近年来用于解决高成本优化问题的方法,它通过使用代理模型,对适应度与因变量的关系进行预测,从而大幅降低计算成本。提出一种基于变可信度代理模型和差分进化相结合的设计优化方法(VFS-DE)。利用所提出的VFS-DE进行相关优化测试函数检验,结果表明:该方法可以有效地解决函数优化问题。将VFS-DE应用在机床伺服电机平面扭簧的设计中,相关实验结果验证了该方法的有效性。

一种基于多层设计空间缩减策略的近似高维优化方法

针对高维昂贵黑箱问题(high-dimensional expensive black-box,HEB)处理过程中工程模型复杂、计算量大的难题,提出一种基于多层设计空间缩减策略的近似高维优化方法(hierarchical design space reduction strategy based approximate high-dimensional optimization method,HSRAHO)。利用3种经典代理模型:多项式响应面模型、径向基函数模型和克里金模型,使用基于预测均方根误差权重因子优化方法计算获得各代理模型权系数,通过加权叠加构建组合代理模型,替代实际高维黑箱模型。使用多层设计空间缩减策略根据已知信息确定设计子空间,并在其内部确定有效样本点,逐步提高组合代理模型在感兴趣区域的预测精度,直至优化收敛。将提出的近似高维优化方法HSRAHO应用于标准优化函数和翼型设计优化问题,测试结果验证了该方法在高维优化效率和全局收敛性方面的优势。

动态Kriging优化算法求解昂贵约束优化问题

针对昂贵单目标约束优化中真实模型计算费时且现有算法收敛速度慢的问题,提出了动态Kriging优化算法以提高计算效率.该算法首先将所有约束条件转换为一个约束函数,然后采用拉丁超立方体采样(LHS)法进行采样,分别建立真实模型目标函数和约束函数的Kriging代理模型,同时结合真实模型对代理模型估计进行误差矫正,采用非支配个体选择、保留和替换机制不断更新样本库和Kriging代理模型.最后将进化最优种群代入真实模型计算其最优值.通过13个标准函数测试表明该算法具有较高的精确度和稳健性,明显减少了真实模型的评价次数.