Hybrid genetic algorithm for multi-time period production/distribution planning

In this paper, we deal with a production/distribution problem to determine an efficient integration of production, distribution and inventory system so that products are produced and distributed at the right quantities, to the right customers, and at the right time, in order to minimize system wide costs while satisfying all demand required. This problem can be viewed as an optimization model that integrates facility location decisions, distribution costs, and inventory management for multi-products and multi-time periods. To solve the problem, we propose a new technique called spanning tree-based genetic algorithm (hst-GA). In order to improve its efficiency, the proposed method is hybridized with the fuzzy logic controller (FLC) concept for auto-tuning the GA parameters. The proposed method is compared with traditional spanning tree-based genetic algorithm approach. This comparison shows that the proposed method gives better results.     

Effective selection and allocation of material handling equipment for stochastic production material demand problems using genetic algorithm

This paper addresses the stochastic production demand problem in a manufacturing company. The objective of this research is to minimize the waiting time of production workstations and reduce stochastic production material problems through coordinating pickup and delivery orders in a warehouse. RFID technology is adopted to visualize the actual status of operations in production and warehouse environments. A mathematical model is developed to address this problem and a meta-heuristic algorithm using genetic algorithm (GA) is also developed to improve performance. Computational experiments are undertaken to examine the performance of the algorithm when dealing with congestion in cases of heavy and normal demand for production material. The overall result shows that the algorithm efficiently minimizes the total makespan of the production shop floor.     

炼钢-连铸作业计划的基于仿真的遗传算法

为了改普作业计划的可执行性,应用基于仿真的优化对炼钢-连铸作业计划问题进行了研究.借助数学模型描述该问题,进而开发了一个基于仿真的遗传算法.该算法能够仿真物理系统的运行和现场人员的部分操作,简洁明了且运行速度较快.实验及分析表明,该方法便于实现,能得到更接近实际的作业计划.     

Integration of process planning and production scheduling based on genetic algorithm

Lacking of flexibility in the traditional workshop production, a genetic algorithm is proposed to implement the integration of process planning and production scheduling. In this paper, the processing routes and processing machine are selected through chromosome crossover and mutation, in order to implement the optimal scheduling of the flexible workshop production. Meanwhile, a performance test about the integration of process planning and production scheduling is implemented, and the results shows that the genetic algorithm is efficient to obtain optimal or near optimal process routes which can meet the requirements of production scheduling.     

基于改进遗传算法的机器人路径规划

标准遗传算法在解决各类优化问题中获得成功,但它在具体的应用中由于缺乏对特定知识的利用,其性能有待提高.针对机器人路径规划的实际应用,通过优化设计标准遗传算法中的交叉算子和变异算子,提出一种应用于机器人路径规划的改进型遗传算法.在把地图特征信息引入遗传算子的操作过程中提高了算法的进化效率.计算机仿真实验结果证明该算法在收敛速度、最优解输出概率方面相对于基本遗传算法有了显著提高.     

机器人路径规划中的改进型遗传算法

提出了一种应用于机器人路径规划的改进型遗传算法。针对机器人路径规划的实际应用,优化设计了交叉算子和变异算子,引入了自定义的插入和删除两种遗传操作。通过把地图特征信息作为参与决策的已知条件来约束遗传算子的操作过程,提高了算法的进化效率。自定义遗传算子的使用,使得算法对复杂地图也表现出良好的适应能力。计算机仿真实验证明该算法在最优解输出概率方面相对于基本遗传算法有了显著提高。     

An algorithm for production planning in a flexible production system

In this paper, we consider the problem of determining the production rate, production batch size, and production sequence when production rate, setup cost, and unit processing cost are sequence-dependent. Using a standard lot sizing model with backorder, a tabu search algorithm for solving this problem is proposed. The algorithm is tested on some random test problems and its performance is compared with random sequencing. Computational results show that the proposed algorithm is very efficient.     

炼钢连铸作业计划的混合遗传优化与仿真分析

为提高炼钢连铸作业计划制定的效率和质量,面向生产工艺流程网络图,建立了一种基于遗传算法与蚁群算法相结合的混合智能优化方法,进行炼钢连铸生产作业计划的编制,并可实现常见扰动情况下的重计划制定;利用基于元胞自动机思想建立的炼钢连铸流程仿真模型,进行生产作业计划的仿真分析和评价。将计划编制模型与仿真模型有机结合,为作业计划的在线动态评价和自动调整提供了一种有效手段。针对某钢厂的仿真实验研究表明：提出的智能优化方法能较好地解决炼钢-连铸生产作业计划的时间不确定性优化问题,可快速生成炉次间作业无冲突的优化生产作业计划。     

用于游戏NPC路径规划的改进遗传算法

针对游戏非玩家控制(NPC)路径规划中传统遗传算法计算速度慢、正确率低等问题,设计了改进型遗传算法.提出了最佳种群规模估计方法,设计了基于精英主义思想的遗传算子.根据游戏地图的特点,引入了基于启发式深度优先搜索的变异操作.与传统遗传算法以及其他学者的改进算法进行了对比实验.实验结果表明:算法能够在保证正确率的前提下,提高计算速度,并且在多目标的环境下同样适用.     

知识引导遗传算法实现机器人路径规划

针对传统遗传算法求解机器人路径规划问题存在的收敛速度较慢的缺陷,设计一种知识引导遗传算法,在染色体的编码、初始种群的产生、各种遗传算子和优化算子中加入相关的领域知识.综合考虑机器人路径的长度、安全度和平滑度等性能指标,在对机器人进行路径规划的同时,利用删除、简化、修正和平滑4种优化算子进行路径优化操作.仿真结果表明,所提方法能够有效提高遗传算法求解实际路径规划问题的能力和效率.     

High performance genetic algorithm for land use planning

This study uses genetic algorithms to formulate and develop land use plans. The restrictions to be imposed and the variables to be optimized are selected based on current local and national legal rules and experts’ criteria. Other considerations can easily be incorporated in this approach. Two optimization criteria are applied: land suitability and the shape-regularity of the resulting land use patches. We consider the existing plots as the minimum units for land use allocation. As the number of affected plots can be large, the algorithm execution time is potentially high. The work thus focuses on implementing and analyzing different parallel paradigms: multi-core parallelism, cluster parallelism and the combination of both. Some tests were performed that show the suitability of genetic algorithms to land use planning problems.     

A heuristic genetic algorithm for product portfolio planning

Product portfolio planning has been recognized as a critical decision facing all companies across industries. It aims at the selection of a near-optimal mix of products and attribute levels to offer in the target market. It constitutes a combinatorial optimization problem that is deemed to be NP-hard in nature. Conventional enumeration-based optimization techniques become inhibitive given that the number of possible combinations may be enormous. Genetic algorithms have been proven to excel in solving combinatorial optimization problems. This paper develops a heuristic genetic algorithm for solving the product portfolio planning problem more effectively. A generic encoding scheme is introduced to synchronize product portfolio generation and selection coherently. The fitness function is established based on a shared surplus measure leveraging both the customer and engineering concerns. An unbalanced index is proposed to model the elitism of product portfolio solutions.     

An enhanced genetic algorithm for automated assembly planning

Automated assembly planning reduces manufacturing manpower requirements and helps simplify product assembly planning, by clearly defining input data, and input data format, needed to complete an assembly plan. In addition, automation provides the computational power needed to find optimal or near-optimal assembly plans, even for complex mechanical products. As a result, modern manufacturing systems use, to an ever greater extent, automated assembly planning rather than technician-scheduled assembly planning. Thus, many current research reports describe efforts to develop more efficient automated assembly planning algorithms. Genetic algorithms show particular promise for automated assembly planning. As a result, several recent research reports present assembly planners based upon traditional genetic algorithms. Although prior genetic assembly planners find improved assembly plans with some success, they also tend to converge prematurely at local-optimal solutions. Thus, we present an assembly planner, based upon an enhanced genetic algorithm, that demonstrates improved searching characteristics over an assembly planner based upon a traditional genetic algorithm. In particular, our planner finds optimal or near-optimal solutions more reliably and more quickly than an assembly planner that uses a traditional genetic algorithm.     

A novel congruent organizational design methodology using group technology and a nested genetic algorithm

A key concept in congruent organizational design is the so-called strategic grouping, which involves the aggregation of task functions, positions, and assets into units. Group technology (GT) has emerged as a manufacturing philosophy for improving productivity in batch production systems, while retaining the flexibility of a job shop production. In this paper, a methodology [nested genetic algorithm (NGA)] to group tasks and assets into several clusters [decision makers (DMs), command cells] is proposed; this methodology employs concepts from GT and genetic algorithms (GAs) to minimize the weighted total workload, measured in terms of intra-DM and inter-DM coordination workloads. The numerical results show that the proposed NGA approach obtains a near-optimal layout of the organization, i.e., the assignment of platforms to tasks and the patterns of coordination achieve a nice tradeoff between inter-DM and intra-DM coordination workload.     

Optimization process planning using hybrid genetic algorithm and intelligent search for job shop machining

Optimization of process planning is considered as the key technology for computer-aided process planning which is a rather complex and difficult procedure. A good process plan of a part is built up based on two elements: (1) the optimized sequence of the operations of the part; and (2) the optimized selection of the machine, cutting tool and Tool Access Direction (TAD) for each operation. In the present work, the process planning is divided into preliminary planning, and secondary/detailed planning. In the preliminary stage, based on the analysis of order and clustering constraints as a compulsive constraint aggregation in operation sequencing and using an intelligent searching strategy, the feasible sequences are generated. Then, in the detailed planning stage, using the genetic algorithm which prunes the initial feasible sequences, the optimized operation sequence and the optimized selection of the machine, cutting tool and TAD for each operation based on optimization constraints as an additive constraint aggregation are obtained. The main contribution of this work is the optimization of sequence of the operations of the part, and optimization of machine selection, cutting tool and TAD for each operation using the intelligent search and genetic algorithm simultaneously.     

产品设计规划问题建模及遗传算法求解

针对目前产品设计过程规划研究中存在的不足,在充分考虑实际设计过程中存在的各种不确定因素的基础上,以产品开发过程中的全体任务为规划对象,以设计迭代时间和成本为目标,将设计过程规划问题描述为基于仿真的随机优化问题进行处理。提出一种模型求解的混合遗传算法,该算法引入最优计算量分配技术进行样本分配,极大地提高了算法的搜索效率,有效地改善了遗传算法搜索的可靠性。以汽轮机轴承转子系统的设计为例,对提出的方法的有效性进行了验证,仿真结果表明,该建模方法有效且算法求解效率高。该方法可推广应用于各种产品设计过程的规划,具有普遍意义。     

基于遗传算法的主体规划实现

面向主体的软件开发是计算机科学与技术领域的一项重要技术.近年来,在主体体系结构,主体规划、主体通信语言等方面的研究已经得到了一系列进展.探讨了主体规划的实现问题,提出将遗传算法的思想用在主体每一步的动作的选择中.给出了基于遗传算法的主体规划算法,并结合一个应用实例展示了具体的实现过程.     

Adaptive genetic algorithm for advanced planning in manufacturing supply chain

A main function for supporting global objectives in a manufacturing supply chain is planning and scheduling. This is considered such an important function because it is involved in the assignment of factory resources to production tasks. In this paper, an advanced planning model that simultaneously decides process plans and schedules was proposed for the manufacturing supply chain (MSC). The model was formulated with mixed integer programming, which considered alternative resources and sequences, a sequence-dependent setup and transportation times.The objective of the model was to analyze alternative resources and sequences to determine the schedules and operation sequences that minimize makespan. A new adaptive genetic algorithm approach was developed to solve the model. Numerical experiments were carried out to demonstrate the efficiency of the developed approach. Received: June 2005 / Accepted: December 2005     

A Tabu-enhanced genetic algorithm approach for assembly process planning

Over the past decade, much work has been done to optimize assembly process plans to improve productivity. Among them, genetic algorithms (GAs) are one of the most widely used techniques. Basically, GAs are optimization methodologies based on a direct analogy to Darwinian natural selection and genetics in biological systems. They can deal with complex product assembly planning. However, during the process, the neighborhood may converge too fast and limit the search to a local optimum prematurely. In a similar domain, Tabu search (TS) constitutes a meta-procedure that organizes and directs the operation of a search process. It is able to systematically impose and release constraints so as to permit the exploration of otherwise forbidden regions in a search space. This study attempts to combine the strengths of GAs and TS to realize a hybrid approach for optimal assembly process planning. More robust search behavior can possibly be obtained by incorporating the Tabus intensification and diversification strategies into GAs. The hybrid approach also takes into account assembly guidelines and assembly constraints in the derivation of near optimal assembly process plans. A case study on a cordless telephone assembly is used to demonstrate the approach. Results show that the assembly process plans obtained are superior to those derived by GA alone. The details of the hybrid approach and the case study are presented.     

面向旅游行程规划的交互式多智能体遗传算法*

结合多智能体技术和交互式遗传算法,提出了一种面向旅游行程规划问题的交互式多智能体遗传算法。算法通过让固定在网格上的智能体展开进化和竞争行为来寻找满意行程。在算法每代中,用户只需评价选择一个当代最优智能体,就可计算得到当代所有智能体的能量,减少了评价次数,有效缓解了用户在评价过程中的疲劳问题。仿真实验验证了该算法在解决旅游行程规划问题中的可行性和有效性,并对问题规模表现出很好的可伸缩性。