Multiple Phase Neighborhood Search-GRASP for the Capacitated Vehicle Routing Problem

Greedy Randomized Adaptive Search Procedure (GRASP) has been proved to be a very efficient algorithm for the solution of the Traveling Salesman Problem. Also, it has been proved that expanding the local search with the use of two or more different local search strategies helps the algorithm to avoid trapping in a local optimum. In this paper, a new modified version of GRASP, called Multiple Phase Neighborhood Search-GRASP (MPNS-GRASP), for the solution of the Vehicle Routing Problem is proposed. In this method, a stopping criterion based on Lagrangean Relaxation and Subgradient Optimization is utilized. In addition, a different way for expanding the neighborhood search is used based on a new strategy, the Circle Restricted Local Search Moves strategy. The algorithm was tested on two sets of benchmark instances and gave very satisfactory results. In both sets of instances the results have solution qualities with average values near to the optimum values and in a number of them the algorithm finds the optimum. The computational time of the algorithm is decreased significantly compared to other heuristic and metaheuristic algorithms due to the fact that the new strategy, the Expanding Neighborhood Search Strategy, is used.     

Coupling Genetic Local Search and Recovering Beam Search algorithms for minimizing the total completion time in the single machine scheduling problem subject to release dates

In this paper we consider the well-known single machine scheduling problem with release dates and minimization of the total job completion time. For solving this problem, denoted by 1|r_j|∑C_j, we provide a new metaheuristic which is an extension of the so-called filtered beam search proposed by Ow and Morton [30]. This metaheuristic, referred to as a Genetic Recovering Beam Search (GRBS), takes advantages of a Genetic Local Search (GLS) algorithm and a Recovering Beam Search (RBS) in order to efficiently explore the solution space. In this paper we present the GRBS framework and its application to the 1|r_j|∑C_j problem. Computational results show that it consistently yields optimal or near-optimal solutions and that it provides interesting results by comparison to GLS and RBS algorithms. Moreover, these results highlight that the proposed algorithm outperforms the state-of-the-art heuristics.     

A Memetic Chaotic Gravitational Search Algorithm for unconstrained global optimization problems

Metaheuristic optimization algorithms address two main tasks in the process of problem solving: i) exploration (also called diversification) and ii) exploitation (also called intensification). Guaranteeing a trade-off between these operations is critical to good performance. However, although many methods have been proposed by which metaheuristics can achieve a balance between the exploration and exploitation stages, they are still worse than exact algorithms at exploitation tasks, where gradient-based mechanisms outperform metaheuristics when a local minimum is approximated. In this paper, a quasi-Newton method is introduced into a Chaotic Gravitational Search Algorithm as an exploitation method, with the purpose of improving the exploitation capabilities of this recent and promising population-based metaheuristic. The proposed approach, referred to as a Memetic Chaotic Gravitational Search Algorithm, is used to solve forty-five benchmark problems, both synthetic and real-world, to validate the method. The numerical results show that the adding of quasi-Newton search directions to the original (Chaotic) Gravitational Search Algorithm substantially improves its performance. Also, a comparison with the state-of-the-art algorithms: Particle Swarm Optimization, Genetic Algorithm, Rcr-JADE, COBIDE and RLMPSO, shows that the proposed approach is promising for certain real-world problems.     

Ensemble of multi-objective metaheuristic algorithms for multi-objective unconstrained binary quadratic programming problem

Metaheuristics have been widely utilized for solving NP-hard optimization problems. However, these algorithms usually perform differently from one problem to another, i.e., one may be effective on a problem but performs badly on another problem. Therefore, it is difficult to choose the best algorithm in advance for a given problem. In contrast to selecting the best algorithm for a problem, selection hyper-heuristics aim at performing well on a set of problems (instances). This paper proposes a selection hyper-heuristic based algorithm for multi-objective optimization problems. In the proposed algorithm, multiple metaheuristics exhibiting different search behaviors are managed and controlled as low-level metaheuristics in an algorithm pool, and the most appropriate metaheuristic is selected by means of a performance indicator at each search stage. To assess the performance of the proposed algorithm, an implementation of the algorithm containing four metaheuristics is proposed and tested for solving multi-objective unconstrained binary quadratic programming problem. Experimental results on 50 benchmark instances show that the proposed algorithm can provide better overall performance than single metaheuristics, which demonstrates the effectiveness of the proposed algorithm.     

Local search versus Path Relinking in metaheuristics: Redesigning Meta-RaPS with application to the multidimensional knapsack problem

Most heuristics for discrete optimization problems consist of two phases: a greedy-based construction phase followed by an improvement (local search) phase. Although the best solutions are usually generated after the improvement phase, there is usually a high computational cost for employing a local search algorithm. This paper seeks another alternative to reduce the computational burden of a local search while keeping solution quality by embedding intelligence in metaheuristics. A modified version of Path Relinking is introduced to replace the local search in the improvement phase of Meta-RaPS (Meta-Heuristic for Randomized Priority Search) which is currently classified as a memoryless metaheuristic. The new algorithm is tested using the 0–1 multidimensional knapsack problem, and it is observed that it could solve even the largest benchmark problems in significantly less time while maintaining solution quality compared to other algorithms in the literature.     

A hybrid mobile object tracker based on the modified Cuckoo Search algorithm and the Kalman Filter

Most revolutionary algorithms are inspired from the behavior of natural species. This inspiration can be drawn from their reproductive behavior, flying mode, or even their ways of communication. One of the most efficient metaheuristics in a discrete search space is the Cuckoo Search algorithm, inspired by the Cuckoo?s reproductive behavior and combined with the Lévy flight pattern adopted by many animals and insects. In this paper, we present a new tracking approach, the Hybrid Kalman Cuckoo Search tracker, using a modified version of the Cuckoo Search algorithm combined with the well-known Kalman Filter. The Cuckoo Search algorithm is combined with the prediction step adopted by the Kalman Filter to enhance the initial population?s quality. Using the Hybrid Kalman Cuckoo Search tracker, we can efficiently explore the search space in order to locate an object?s position from one frame to the next. The Lévy flight model is also modified in order to re-adapt the Lévy step size as the algorithm approaches the desired solution. The Hybrid Kalman Cuckoo Search tracker is tested on a variety of datasets including one where we incorporated different situations, as well as some videos from the CAVIAR, SPEVI, and other datasets. The comparative study results show that the proposed algorithm outperforms the Particle Swarm Optimization based tracker, especially in terms of computation time.     

Free Pattern Search for global optimization

An efficient algorithm named Pattern search (PS) has been used widely in various scientific and engineering fields. However, even though the global convergence of PS has been proved, it does not perform well on more complex and higher dimension problems nowadays. In order to improve the efficiency of PS and obtain a more powerful algorithm for global optimization, a new algorithm named Free Pattern Search (FPS) based on PS and Free Search (FS) is proposed in this paper. FPS inherits the global search from FS and the local search from PS. Two operators have been designed for accelerating the convergence speed and keeping the diversity of population. The acceleration operator inspired by FS uses a self-regular management to classify the population into two groups and accelerates all individuals in the first group, while the throw operator is designed to avoid the reduplicative search of population and keep the diversity. In order to verify the performance of FPS, two famous benchmark instances are conducted for the comparisons between FPS with Particle Swarm Optimization (PSO) variants and Differential Evolution (DE) variants. The results show that FPS obtains better solutions and achieves the higher convergence speed than other algorithms.     

Decision support for multi-objective flow shop scheduling by the Pareto Iterated Local Search methodology

The article describes the proposition and application of a local search metaheuristic for multi-objective optimization problems. It is based on two main principles of heuristic search, intensification through variable neighborhoods, and diversification through perturbations and successive iterations in favorable regions of the search space. The concept is successfully tested on permutation flow shop scheduling problems under multiple objectives and compared to other local search approaches. While the obtained results are encouraging in terms of their quality, another positive attribute of the approach is its simplicity as it does require the setting of only very few parameters.The metaheuristic is a key element of the Multi-Objective Optimization and Production Planning Solver MOOPPS. The software has been awarded the European Academic Software Award in Ronneby, Sweden (http://www.bth.se/llab/easa_2002.nsf), and has since been used for research and higher education in the mentioned problem domain (Geiger, 2006).     

中文分词技术在搜索引擎中的应用研究

中文分词作为机器翻译、文本分类、主题词提取以及信息检索的基础环节,近年来得到了广泛的关注。搜索引擎技术的广泛应用和中文信息处理的发展,使得全文检索和中文分词技术的研究逐渐深入,涌现出了众多优秀的中文分词算法。本文结合中文分词算法的研究现状,分析了分词技术与搜索引擎的信息检索相结合需要解决的关键技术问题,并讨论了中文分词技术在搜索引擎中的应用。     

Estimation-based metaheuristics for the probabilistic traveling salesman problem

The probabilistic traveling salesman problem (PTSP) is a central problem in stochastic routing. Recently, we have shown that empirical estimation is a promising approach to devise highly effective local search algorithms for the PTSP. In this paper, we customize two metaheuristics, an iterated local search algorithm and a memetic algorithm, to solve the PTSP. This customization consists in adopting the estimation approach to evaluate the solution cost, exploiting a recently developed estimation-based local search algorithm, and tuning the metaheuristics parameters. We present an experimental study of the estimation-based metaheuristic algorithms on a number of instance classes. The results show that the proposed algorithms are highly effective and that they define a new state-of-the-art for the PTSP.     

Clustering Search for the Berth Allocation Problem

This work presents a new approach to the Berth Allocation Problem (BAP) for ships in ports. Due to the increasing demand for ships carrying containers, the BAP can be considered as a major optimization problem in marine terminals. In this paper, the BAP is considered as dynamic and modeled in discrete case and we propose a new alternative to solve it. The proposed alternative is based on applying the Clustering Search (CS) method using the Simulated Annealing (SA) for solutions generation. The CS is an iterative method which divides the search space in clusters and it is composed of a metaheuristic for solutions generation, a grouping process and a local search heuristic. The computational results are compared against recent methods found in the literature.     

一种SAT邻域的快速搜索算法

用局部搜索算法求解SAT问题．通常都需要在较大的邻域中。寻找合适的邻解。如果对邻域中的每个邻解。都通过重新判断每个子句是否为可满足来得到其可满足的子句个数．则时间耗费较多。已经有一些经典的处理方法．例如通过修改邻域结构．来减小搜索空间。从另外一个角度来考虑搜索过程．根据当前解和邻解的内在关系．介绍一种SAT邻域的快速搜索算法。该算法能在不影响解质量的前提下．快速寻找合适的邻解．从而进一步提高局部搜索算法的求解速度。另外．该算法还提供用于提高解质量的信息。有助于研究新的局部搜索算法。     

Effective local search algorithms for high school timetabling problems

This paper addresses the high school timetabling problem. The problem consists in building weekly timetables for meetings between classes and teachers with the goal of minimizing violations of specific requirements. In the last decades, several mixed-integer programs have been proposed and tested for this family of problems. However, medium and large size instances are still not effectively solved by these programs using state-of-the-art solvers and the scientific community has given special attention to the devising of alternative soft computing algorithms. In this paper, we propose a soft computing approach based on Iterated Local Search and Variable Neighborhood Search metaheuristic frameworks. Our algorithms incorporate new neighborhood structures and local search routines to perform an effective search. We validated the proposed algorithms on variants of the problem using seven public instances and a new dataset with 34 real-world instances including large cases. The results demonstrate that the proposed algorithms outperform the state-of-the-art approaches in both cases, finding the best solutions in 38 out of the 41 tested instances.     

Discrete cuckoo search algorithm for the travelling salesman problem

In this paper, we present an improved and discrete version of the Cuckoo Search (CS) algorithm to solve the famous traveling salesman problem (TSP), an NP-hard combinatorial optimisation problem. CS is a metaheuristic search algorithm which was recently developed by Xin-She Yang and Suash Deb in 2009, inspired by the breeding behaviour of cuckoos. This new algorithm has proved to be very effective in solving continuous optimisation problems. We now extend and improve CS by reconstructing its population and introducing a new category of cuckoos so that it can solve combinatorial problems as well as continuous problems. The performance of the proposed discrete cuckoo search (DCS) is tested against a set of benchmarks of symmetric TSP from the well-known TSPLIB library. The results of the tests show that DCS is superior to some other metaheuristics.     

HYBRID METAHEURISTICS FOR THE DESIGN OF COUPLED RESONATOR FILTERS

The design of coupled resonator filters used in many telecommunication applications poses an optimization problem that can be tackled with heuristic methods. In many configurations, simple heuristic methods do not give satisfactory results, and the combination in hybrid metaheuristics of local and global search methods is a better approach. This article analyzes the systematic development of hybrid metaheuristic methods for the design of coupled resonator filters. Engineers normally use the MATLAB computing environment to work on the design of these devices, so the available MATLAB optimization toolboxes are used here as a basis to address those optimization problems. The results obtained are in general satisfactory, and the best results are obtained in the experiments with memetic algorithms in which methods based in populations (Genetic Algorithms and Scatter Search) are combined with local search methods to improve individuals in the population at different parts of the metaheuristic.     

具有邻域搜索机制的爆炸搜索算法

受烟花(炸弹)爆炸的启发,提出一种新型的智能优化算法——爆炸搜索算法(ESA)。该算法引入邻域搜索的思想,包含3个重要算子：爆炸搜索算子,迁移算子,变异算子,具有较大的局部-全局搜索能力,且收敛速度快、稳定性好。对benchmark函数集进行仿真并与CPSO等算法进行比较,实验结果证实了ESA的高效性。     

基于BACS算法的数据库查询优化

针对布谷鸟算法局部搜索能力弱、寻优精度低等缺陷,提出一种蝙蝠算法和布谷鸟算法相融合的数据库查询优化算法（BACS）。按照布谷鸟优化算法对鸟巢位置进行更新,利用蝙蝠算法的动态转换策略对鸟巢位置进一步更新,避免算法陷入局部最优;最后将BACS应用于数据库查询优化问题求解,并通过仿真实验对BACS的性能进行测试。实验结果表明,BACS加快了数据库查询优化求解的收敛速度,获得了质量更高的查询优化方案。     

A Discrete Inter-Species Cuckoo Search for flowshop scheduling problems

This paper presents a discrete version of the Inter-Species Cuckoo Search (ISCS) algorithm and illustrates its use for solving two significant types of the flow-shop scheduling problems. These are Hybrid Flow-shop Scheduling (HFS) and Permutation Flow-shop Sequencing Problems (PFSP). Hybrid flowshop scheduling problems are a generalization of flowshops having parallel machines in some stages and these problems are known to be NP-hard. A heuristic rule called the Smallest Position Value (SPV) is used to enable the continuous inter-species cuckoo search to be applied to most types of sequencing problems. Makespan and mean flow time are the objective functions considered and computational experiments are carried out to compare the proposed Discrete Inter-Species Cuckoo Search (DISCS) with other state-of-the-art meta-heuristic algorithms. Experimental results confirm the superiority of DISCS with respect to many other existing metaheuristic search algorithms.     

XML-Based Advanced UDDI Search Mechanism for B2B Integration

Exploring appropriate business applications published as Web Services in UDDI registries is a critical issue. Search for such applications should be effective in terms of time and uniformed in terms of interfaces. In this paper, an XML-based advanced UDDI exploring engine, Business Explorer for Web Services (BE4WS), that provides developers with standard interfaces for efficiently searching business and service information in single or multiple UDDI registries is presented. The engine processes the proposed UDDI Search Markup Language (USML) that specifies a search request comprising multiple queries, UDDI sources, search criteria, and aggregation operator. The core component of BE4WS, Advanced UDDI Search Engine (AUSE), aggregates search results from different UDDI registries based on the USML request and built-in intelligent search facilities with the ability to cross-reference multiple categories. An aggregation example using BE4WS is demonstrated to enable easy B2B integration.     

基于新型拥挤度距离的多目标麻雀搜索算法

现实中的多目标问题日益复杂,解决这类问题需要高效的优化算法。基于麻雀搜索算法,提出多目标麻雀搜索算法（Multi-objective Sparrow Search Algorithm,MSSA）,对多目标优化问题进行求解。依据外部存档收敛性动态调整麻雀种群比例因子,以达到全局探索能力和局部开发能力的最佳平衡,确保收敛性;对麻雀种群进行非支配排序;对麻雀种群的发现者引入多项式变异因子,增强算法跳出局部最优的能力;设计一种新型拥挤度距离计算策略,利用外部存档解的拥挤度大小剔除相似个体的方法对种群进行裁剪,使个体不超过存档上限的同时维持种群的多样性。分别使用多目标函数和盘式制动器设计测试算法性能。MSSA与MOPSO、MOGWO、NSGA-II和SPEA2在多目标测试函数上进行对比实验,结果表明MSSA算法在收敛性和均匀性两项指标上有显著的优势。盘式制动器仿真结果表明,MSSA可以快速地找到问题的非支配解,证明了该方法的有效性。