Identifying influential spreaders in social networks: A two-stage quantum-behaved particle swarm optimization with Lévy flight

The influence maximization problem aims to select a small set of influential nodes, termed a seed set, to maximize their influence coverage in social networks. Although the methods that are based on a greedy strategy can obtain good accuracy, they come at the cost of enormous computational time, and are therefore not applicable to practical scenarios in large-scale networks. In addition, the centrality heuristic algorithms that are based on network topology can be completed in relatively less time. However, they tend to fail to achieve satisfactory results because of drawbacks such as overlapped influence spread. In this work, we propose a discrete two-stage metaheuristic optimization combining quantum-behaved particle swarm optimization with Lévy flight to identify a set of the most influential spreaders. According to the framework,first, the particles in the population are tasked to conduct an exploration in the global solution space to eventually converge to an acceptable solution through the crossover and replacement operations. Second, the Lévy flight mechanism is used to perform a wandering walk on the optimal candidate solution in the population to exploit the potentially unidentified influential nodes in the network. Experiments on six real-world social networks show that the proposed algorithm achieves more satisfactory results when compared to other well-known algorithms.

Enhanced Multi-Objective Grey Wolf Optimizer with Lévy Flight and Mutation Operators for Feature Selection

The process of selecting features or reducing dimensionality can be viewed as a multi-objective minimization problem in which both the number of features and error rate must be minimized.While it is a multi-objective problem,current methods tend to treat feature selection as a single-objective optimization task.This paper presents enhanced multi-objective grey wolf optimizer with Lévy flight and mutation phase(LMuMOGWO)for tackling feature selection problems.The proposed approach integrates two effective operators into the existing Multi-objective Grey Wolf optimizer(MOGWO):a Lévy flight and a mutation operator.The Lévy flight,a type of random walk with jump size determined by the Lévy distribution,enhances the global search capability of MOGWO,with the objective of maximizing classification accuracy while minimizing the number of selected features.The mutation operator is integrated to add more informative features that can assist in enhancing classification accuracy.As feature selection is a binary problem,the continuous search space is converted into a binary space using the sigmoid function.To evaluate the classification performance of the selected feature subset,the proposed approach employs a wrapper-based Artificial Neural Network(ANN).The effectiveness of the LMuMOGWO is validated on 12 conventional UCI benchmark datasets and compared with two existing variants of MOGWO,BMOGWO-S(based sigmoid),BMOGWO-V(based tanh)as well as Non-dominated Sorting Genetic Algorithm II(NSGA-II)and Multi-objective Particle Swarm Optimization(BMOPSO).The results demonstrate that the proposed LMuMOGWO approach is capable of successfully evolving and improving a set of randomly generated solutions for a given optimization problem.Moreover,the proposed approach outperforms existing approaches in most cases in terms of classification error rate,feature reduction,and computational cost.

Salp Swarm Incorporated Adaptive Dwarf Mongoose Optimizer with Lévy Flight and Gbest-Guided Strategy

In response to the shortcomings of Dwarf Mongoose Optimization(DMO)algorithm,such as insufficient exploitation capability and slow convergence speed,this paper proposes a multi-strategy enhanced DMO,referred to as GLSDMO.Firstly,we propose an improved solution search equation that utilizes the Gbest-guided strategy with different parameters to achieve a trade-off between exploration and exploitation(EE).Secondly,the Lévy flight is introduced to increase the diversity of population distribution and avoid the algorithm getting stuck in a local optimum.In addition,in order to address the problem of low convergence efficiency of DMO,this study uses the strong nonlinear convergence factor Sigmaid function as the moving step size parameter of the mongoose during collective activities,and combines the strategy of the salp swarm leader with the mongoose for cooperative optimization,which enhances the search efficiency of agents and accelerating the convergence of the algorithm to the global optimal solution(Gbest).Subsequently,the superiority of GLSDMO is verified on CEC2017 and CEC2019,and the optimization effect of GLSDMO is analyzed in detail.The results show that GLSDMO is significantly superior to the compared algorithms in solution quality,robustness and global convergence rate on most test functions.Finally,the optimization performance of GLSDMO is verified on three classic engineering examples and one truss topology optimization example.The simulation results show that GLSDMO achieves optimal costs on these real-world engineering problems.

引入Lévy flight和萤火虫行为的鱼群算法

针对人工鱼群算法(artificial fish-swarm algorithm,AFSA)和萤火虫算法(firefly algorithm,FA)在多维多极值函数寻优过程中易陷入局部最优和精度有待提高等问题,提出引入Lévy flight和萤火虫行为的鱼群算法(fish swarm algorithm with Lévy flight and firefly behavior).该算法将萤火虫算法中萤火虫个体的移动策略引入到鱼群的聚群,觅食两种行为模式中,进而将Lévy flight引入到鱼群的搜索策略中,使得鱼群的搜索更加高效.此外,采取一种基于动态参数的非线性变视野和变步长的策略来限定鱼群的搜索范围.仿真分析表明,新算法较其他测试算法具有更好的全局搜索能力和寻优精度.

基于Lévy Flight的地震搜救模拟研究

地震是一种极其严重的自然灾害。由于地震灾害救援密切关系到灾区人民的生命财产安全,关于灾后救援的科学调查研究因此也具有实践指导意义。搜救行动是一个需要合作的过程。探讨合作搜救的复杂特性,对指导救援行动意义重大。随机游走模型在众多领域中已经得到了广泛的应用。将随机游走模型中的一种,Lévy Flight引入到搜救模拟的研究中来,建立基于合作的搜救模型。基于初始救援物资有限的前提,将被困幸存者存活率这一因素加以考虑,提出了救灾物资这一概念,并与幸存者存活率相结合。探讨在初期物资有限的前提下,不同规模的救援队配置对救援工作开展的影响以及新的合作规则在救援中发挥的作用。结果表明,模型能在一定程度上描述灾后搜救过程,对加深搜救工作的理解及对策制定有一定的指导作用。

Control allocation for a class of morphing aircraft with integer constraints based on Lévy flight

Aiming at tracking control of a class of innovative control effector(ICE) aircraft with distributed arrays of actuators, this paper proposes a control allocation scheme based on the Lévy flight.Different from the conventional aircraft control allocation problem,the particular characteristic of actuators makes the actuator control command totally subject to integer constraints. In order to tackle this problem, first, the control allocation problem is described as an integer programming problem with two desired objectives. Then considering the requirement of real-time, a metaheuristic algorithm based on the Lévy flight is introduced to tackling this problem. In order to improve the searching efficiency, several targeted and heuristic strategies including variable step length and inherited population initialization according to feedback and so on are designed. Moreover, to prevent the incertitude of the metaheuristic algorithm and ensure the flight stability, a guaranteed control strategy is designed. Finally, a time-varying simulation model is introduced to verifying the effectiveness of the proposed scheme. The contrastive simulation results indicate that the proposed scheme achieves superior tracking performance with appropriate actuator dynamics and computational time, and the improvements for efficiency are active and the parameter settings are reasonable.

基于LF-ATSO算法在光伏系统MPPT中的研究

在复杂遮荫工况下,传统MPPT策略在面对多峰值现象时易陷入局部最大功率点(LMPP),而基于元启发式算法的最大功率点跟踪策略也存在寻优精度不高、追踪时间慢等问题。为解决上述问题,文中构建Lévy飞行-自适应金枪鱼群算法(LF-ATSO)。首先,采用基于Circle混沌映射的反向学习策略合理分配初始化种群以提高种群遍历性;其次,改进参数a用以调整最优个体和前一个体的比重,提高收敛速度;然后,嵌入Lévy flight策略提高算法全局搜索能力,帮助其跳出局部最优;最后,加入算法重启机制以应对复杂变化工况。将改进后的TSO算法与未改进TSO算法、PSO算法、改进GWO算法进行仿真对比,实验结果表明,改进后的TSO算法在静态、动态复杂遮荫工况下均能够更快、更精准地追踪到全局最大功率点(GMPP)。

基于Lévy Flight的混合GA在柔性作业车间调度问题中的性能分析

近年来,柔性作业车间调度问题(FJSP)由于其NP难特性与在制造系统中的广泛应用被大量关注。为提高该类问题求解效率,本文在标准Lévy flight的基础上提出了一种新的离散Lévy flight搜索策略,并将该策略与遗传算法框架结合,形成一种离散Lévy flight策略的混合遗传算法。该混合算法通过使用离散Lévy flight搜索策略对每代精英种群进行变步长搜索,提高了算法的局部搜索能力,增强了种群多样性。本文通过将CS、GA和TLBO等经典算法作为对比算法,对不同规模的54个FJSP算例进行实验,证明了所提出的算法具备更好的收敛效果与稳定性,适合于求解大规模FJSP。

Lévy Flights, 1/<i>f </i>Noise and Self Organized Criticality

A new analysis of a previously studied traveling agent model, showed that there is a relation between the degree of homogeneity of the medium where the agents move, agent motion patterns, and the noise generated from their displacements. We proved that for a particular value of homogeneity, the system self organizes in a state where the agents carry out Lévy walks and the displacement signal corresponds to 1/f noise. Using probabilistic arguments, we conjectured that 1/f noise is a fingerprint of a statistical phase transition, from randomness (disorder) to predictability (order), and that it emerges from the contextuality nature of the system which generates it.

小数据集下基于DRKDE-ICSO的BN结构学习

为了解决在小数据集条件下进行数据拓展时产生数据高度相似的问题,提出了基于降维核密度估计的小数据集拓展方法,从而得到较为准确的拓展数据。另外,针对鸡群优化算法求解效率低下和收敛性不足的问题,提出改进的鸡群优化算法进行结构学习:在雄鸡的位置更新公式中引入莱维飞行,使鸡群算法具有更强的跳跃能力;采用指数递减的动态调节惯性权重,以加速局部搜索和提高收敛速度;通过引入最优个体引导策略,增加找到较优位置的概率。实验结果表明,所提算法在小数据集条件下,BIC评分、准确率及汉明距离等指标均优于MCMC算法、BPSO算法、CSO算法、ADLCSO-I算法和SA-ICSO算法。

基于改进鲸鱼优化算法的工业CT图像增强方法

针对工业CT图像中存在着的前景遮挡,背景噪声干扰和对比度低等问题,提出了一种基于改进鲸鱼优化算法的图像增强方法。首先应用混沌映射对鲸鱼优化算法的种群进行初始化,通过让鲸鱼种群分布的更加广泛来提升全局搜索能力。然后使用莱维飞行对鲸鱼个体的位置进行更新,进一步提高算法的局部搜索能力。最后应用改进的鲸鱼优化方法来寻找CLAHE的最佳参数,实现对图像的自适应最优增强。实验结果显示,相比于几种流行的图像增强算法,本文提出的方法能够更好的对工业CT图像进行增强,能够显著提升图像质量,并保留更多的细节信息。

瞬变电磁数据L-PSO反演方法

本文针对粒子群优化算法(PSO)搜索步长短的问题,提出将Lévy flight搜索策略引入其中.利用Lévy flight兼具短距离搜索与偶尔长距离游走的特点,在不降低PSO算法收敛效率的情况下赋予其大步长游走能力,提高了PSO算法搜索全局最优的能力,极大增加了PSO算法飞出局部最优的概率.最后本文将L-PSO算法应用于实际资料的反演中,结果表明L-PSO算法适用于瞬变电磁法的一维反演.

L_1 adaptive controller design for hypersonic formation flight

The design of an L_1 adaptive controller for hypersonic formation flight is presented. The traditional leader/wingman formation control problem is considered, with focused attention on dealing with the input disturbance and parametric variations, both of which are intrinsic properties of the system that result in undesired control performance. A proportional-derivative control scheme based on nonlinear dynamic inversion is implemented as the baseline controller, and an L_1 adaptive controller is augmented to the baseline controller to attenuate the effects of input disturbance and parametric variations. Simulation results illustrate the effectiveness of the proposed control scheme.

An improved estimation of distribution algorithm for multi-compartment electric vehicle routing problem

The multi-compartment electric vehicle routing problem(EVRP)with soft time window and multiple charging types(MCEVRP-STW&MCT)is studied,in which electric multi-compartment vehicles that are environmentally friendly but need to be recharged in course of transport process,are employed.A mathematical model for this optimization problem is established with the objective of minimizing the function composed of vehicle cost,distribution cost,time window penalty cost and charging service cost.To solve the problem,an estimation of the distribution algorithm based on Lévy flight(EDA-LF)is proposed to perform a local search at each iteration to prevent the algorithm from falling into local optimum.Experimental results demonstrate that the EDA-LF algorithm can find better solutions and has stronger robustness than the basic EDA algorithm.In addition,when comparing with existing algorithms,the result shows that the EDA-LF can often get better solutions in a relatively short time when solving medium and large-scale instances.Further experiments show that using electric multi-compartment vehicles to deliver incompatible products can produce better results than using traditional fuel vehicles.

Differential Evolution with Adaptive Mutation and Parameter Control Using Lvy Probability Distribution

Differential evolution （DE） has become a very popular and effective global optimization algorithm in the area of evolutionary computation. In spite of many advantages such as conceptual simplicity, high efficiency and ease of use, DE has two main components, i.e., mutation scheme and parameter control, which significantly influence its performance. In this paper we intend to improve the performance of DE by using carefully considered strategies for both of the two components. We first design an adaptive mutation scheme, which adaptively makes use of the bias of superior individuals when generating new solutions. Although introducing such a bias is not a new idea, existing methods often use heuristic rules to control the bias. They can hardly maintain the appropriate balance between exploration and exploitation during the search process, because the preferred bias is often problem and evolution-stage dependent. Instead of using any fixed rule, a novel strategy is adopted in the new adaptive mutation scheme to adjust the bias dynamically based on the identified local fitness landscape captured by the current population. As for the other component, i.e., parameter control, we propose a mechanism by using the Levy probability distribution to adaptively control the scale factor F of DE. For every mutation in each generation, an Fi is produced from one of four different Levy distributions according to their historical performance. With the adaptive mutation scheme and parameter control using Levy distribution as the main components, we present a new DE variant called Levy DE （LDE）. Experimental studies were carried out on a broad range of benchmark functions in global numerical optimization. The results show that LDE is very competitive, and both of the two main components have contributed to its overall performance. The scalability of LDE is also discussed by conducting experiments on some selected benchmark functions with dimensions from 30 to 200.

Differential Evolution-Boosted Sine Cosine Golden Eagle Optimizer with Lévy Flight

Golden eagle optimizer(GEO)is a recently introduced nature-inspired metaheuristic algorithm,which simulates the spiral hunting behavior of golden eagles in nature.Regrettably,the GEO suffers from the challenges of low diversity,slow iteration speed,and stagnation in local optimization when dealing with complicated optimization problems.To ameliorate these deficiencies,an improved hybrid GEO called IGEO,combined with Lévy flight,sine cosine algorithm and differential evolution(DE)strategy,is developed in this paper.The Lévy flight strategy is introduced into the initial stage to increase the diversity of the golden eagle population and make the initial population more abundant;meanwhile,the sine-cosine function can enhance the exploration ability of GEO and decrease the possibility of GEO falling into the local optima.Furthermore,the DE strategy is used in the exploration and exploitation stage to improve accuracy and convergence speed of GEO.Finally,the superiority of the presented IGEO are comprehensively verified by comparing GEO and several state-of-the-art algorithms using(1)the CEC 2017 and CEC 2019 benchmark functions and(2)5 real-world engineering problems respectively.The comparison results demonstrate that the proposed IGEO is a powerful and attractive alternative for solving engineering optimization problems.

Correlated Lvy flight in external force fields

The correlated Levy flight is studied analytically in terms of the fractional Fokker-Planck equation and simulated numerically by using the Langevin equation, where the usual white Ltvy noise is generalized to an Ornstein-Uhlenbeck Levy process （OALP） with a correlation time τc. We analyze firstly the stable behavior of OULP. The probability density function of Ltvy flight particle driven by the OULP in a harmonic potential is exactly obtained, which is also a Ltvy-type one with Tc-dependence width; when the particle is bounded by a quartic potential, its stationary distribution has a bimodality shape and becomes noticeable with the increase of τc.

Enhanced Growth Optimizer and Its Application to Multispectral Image Fusion

The growth optimizer(GO)is an innovative and robust metaheuristic optimization algorithm designed to simulate the learning and reflective processes experienced by individuals as they mature within the social environment.However,the original GO algorithm is constrained by two significant limitations:slow convergence and high mem-ory requirements.This restricts its application to large-scale and complex problems.To address these problems,this paper proposes an innovative enhanced growth optimizer(eGO).In contrast to conventional population-based optimization algorithms,the eGO algorithm utilizes a probabilistic model,designated as the virtual population,which is capable of accurately replicating the behavior of actual populations while simultaneously reducing memory consumption.Furthermore,this paper introduces the Lévy flight mechanism,which enhances the diversity and flexibility of the search process,thus further improving the algorithm’s global search capability and convergence speed.To verify the effectiveness of the eGO algorithm,a series of experiments were conducted using the CEC2014 and CEC2017 test sets.The results demonstrate that the eGO algorithm outperforms the original GO algorithm and other compact algorithms regarding memory usage and convergence speed,thus exhibiting powerful optimization capabilities.Finally,the eGO algorithm was applied to image fusion.Through a comparative analysis with the existing PSO and GO algorithms and other compact algorithms,the eGO algorithm demonstrates superior performance in image fusion.

变异蝙蝠算法求解折扣{0-1}背包问题

针对确定性算法难于求解规模大、数据范围广的折扣{0-1}背包问题(D{0-1}KP),提出了基于蝙蝠算法的快速求解D{0-1}KP的变异蝙蝠算法(MDBBA)。首先,利用双重编码解决D{0-1}KP的编码问题;其次,将贪心修复与优化算法(GROA)应用于蝙蝠个体适应度计算中,使算法快速得到有效解;然后,选择使用差分演化(DE)的变异策略提高算法的全局寻优能力;最后,蝙蝠个体按一定概率进行Lévy飞行,增强算法探索能力和跳出局部极值的能力。对四类大规模实例的仿真计算表明:MDBBA非常适于求解大规模的D{0-1}KP,比第一遗传算法(FirEGA)和双重编码蝙蝠算法(DBBA)求得的最优值和平均值都更优,MDBBA收敛速度明显快于DBBA。

求解带约束优化问题的混合式多策略萤火虫算法

目前多目标优化算法主要针对如何处理多个目标之间的冲突,对于如何处理约束考虑较少,鉴于此,提出一种求解带约束优化问题的混合式多策略萤火虫算法(HMSFA-PC).首先,提出一种改进的动态罚函数策略对约束优化问题进行预处理,将其转换为非约束优化问题;其次,对萤火虫算法本身进行改进,采用Lévy flights搜索机制有效地增大搜索范围;接着,引入随机扩张因子改进算法吸引模型,使种群突破束缚,有效避免早熟收敛,提出自适应维度重组机制,根据不同迭代时期选择差异性较大的个体进行信息交互、相互学习.为检验算法处理无约束优化问题的性能,将其在基准测试函数上与部分典型算法进行比较;为检验算法处理约束优化问题的性能,将其在实际约束测试问题中与一些顶尖约束求解算法进行比较.结果表明,HMSFA-PC在处理无约束优化问题时具有收敛速度快、收敛精度高等优势,并且在动态罚函数的协作下求解实际约束优化问题时仍具有良好的优化性能.