随机型混合模式装配线平衡问题的集束搜索算法

本文提出了基于集束搜索的算法来解决随机型混合模式装配线平衡问题,目标是总费用最小化。给出的算例表明本文提出的算法与Prem Vrat的相比可以得到更好的结果。     

混流装配线平衡问题的多目标优化方法研究

针对混流装配线存在的工序作业多、平衡难度大等问题,以U型布置的混装线为研究对象,兼顾工作站平均负荷和瞬时负荷平衡,在最小化工作站数的基础上均衡了工作站间和工作站内不同产品的作业负荷,建立U型混流装配线多目标平衡优化模型,同时提出目标法解决联合目标中的目标函数兼容性问题。设计并运用改进的自适应遗传算法求解模型,考虑到交叉、变异操作的随机性,在变异阶段加入强制规则,并对新生成的子代个体进行基因冲突检测,以提高可行解的比率。算例研究的结果表明本文所提的多目标优化方法能够较好地解决混装线平衡问题。     

混合模式下U型装配线平衡问题的目标规划求解

装配线平衡对于提高装配效率和降低装配成本都有重要意义。为了满足顾客需求的多样化和减少成本,通常采用混合模式的装配线。本文针对混合模式下U型装配线平衡问题,提出一个目标规划法以求解该问题,量化示例表明所提方法是有效的。     

多目标装配线平衡的优化算法

在生产制造系统中，装配线的平衡需要针对多个目标，传统的装配线平衡问题，优化单一目标，忽略了目标之间的联系。优化一个目标的同时，劣化了另外一个目标。章研究了多目标装配线平衡问题，探讨了这些目标之间的联系，设计了禁忌搜索算法求解多目标装配线的平衡问题。章从生产管理系统的角度优化多目标装配线平衡，与单一目标相比，具有显的改进。     

基于GA-SA的混合U型装配线平衡

在JIT生产系统中，混合U型装配线是一种能够满足市场多样化需求的柔性系统，章综合考虑作业元素的分配和产品的投产排序两个因素，建立了混合U型装配线的平衡模型，给出了人工智能算法的平衡方法，从全局优化的角度研究了混合U型装配线的平衡问题。     

面向大规模定制的建筑工业化住宅混合装配线平衡优化研究

为解决大规模定制工业化住宅混合装配线平衡问题,以预制构件均匀消耗为目标建立了混合装配线生产优化模型,并基于目标追随法(GCA)和建筑工业化住宅的建造特点,提出相应的求解算法.通过所构建的优化模型及算法,可对随机输入的工业化装配顺序进行优化,进而获得预制构件消耗速率均匀的优化装配顺序.最后,通过案例分析验证了优化模型的有效性,优化结果表明优化后的生产序列的预制构件消耗更为趋近于平均消耗水平,能够获得更为均匀的预制构件消耗速率,进而提升工业化住宅项目的准时性及效率.     

具有工作站数量约束的多人工作站混合装配线平衡问题研究

针对装配线设计或改造过程中存在的因场地或成本原因导致的工作站数量不易变更的问题,研究了节拍已知情况下,具有工作站数量约束的多人工作站混合装配线平衡问题,建立以装配线总人数最小、工人负荷量标准差最小、各产品在各工作站装配时间与节拍之间的标准差最小为目标的数学模型,设计了一种结合差分进化的多目标混合遗传算法对该问题求解。通过案例计算以及与其他算法的对比分析表明,本文算法在收敛性和综合性能方面优于NSGAII和DEMO,在装配线人数和工人负荷标准差方面优于Roshani和Nezami提出的算法。     

求解混合型Lyapunov矩阵方程的参数迭代法

采用参数迭代法求一类混合型Lyapunov矩阵方程A~TX XA B~TXB=C的对称解.在方程相容的条件下,给出了迭代法收敛的充要条件和一些充分条件,以及参数的选取方法.最后,利用数值算例对有关结果进行了验证.     

Bessel—Neumann混合型方程特征根系的求解方法

本文讨论了Bessel-Neumann混合型方程特征根系{λ_(?)}(λ_0λ_1λ_2…)的求解法问题.给出了计算特征根系的表达式和最小根的取值方法.这种计算方法的优点是不用多位的Bessel函数表,也不需要计算机就能快速地计算出特征根系{λ_(?)}并具有较高的计算精度。     

一种类微粒群算法及其在混流装配线调度问题中的应用

混流装配生产线的调度问题是准时化生产系统中最重要的问题之一.基于微粒群算法的原理,提出了一种类微粒群算法——PPSO(Pseudo Particle Swarm Optimization),可应用于解决准时化生产方式下的混流装配线调度问题.数值试验表明,采用PPSO方法比采用目标追随法、遗传算法和模拟退火算法的求解质量有很大提高.     

A Hybrid Genetic Algorithm for Assembly Line Balancing

This paper presents a hybrid genetic algorithm for the simple assembly line problem, SALBP-1. The chromosome representation of the problem is based on random keys. The assignment of the operations to the workstations is based on a heuristic priority rule in which the priorities of the operations are defined by the chromosomes. A local search is used to improve the solution. The approach is tested on a set of problems taken from the literature and compared with other approaches. The computation results validate the effectiveness of the algorithm.     

Branch and bound procedures for solving the Assembly Line Worker Assignment and Balancing Problem: Application to Sheltered Work centres for Disabled

In this paper a new problem called Assembly Line Worker Assignment and Balancing Problem (ALWABP) is introduced. This problem arises in those assembly lines where we have certain limited resources available (normally workers) in which the operation time for every task is different depending on who executes the task, and where there are also some task-worker incompatibilities defined. The problem consists of providing a simultaneous solution to a double assignment: (1) tasks to stations; and (2) available workers to stations.After defining the mathematical model for this problem, a basic Branch and Bound approach with three possible search strategies and different parameters is presented. We also propose the use of a Branch and Bound-based heuristic for large problems and analyse the behaviour of both exact and heuristic methods through experimental studies. Finally the implementation of these procedures in a Sheltered Work centre for Disabled—the real environment which has inspired this research—is described. In these centres the adoption of assembly lines provide many advantages, since the traditional division of work in single tasks may become a perfect tool for making certain worker disabilities invisible. Efficiently applying this configuration helps these centres to achieve their primary aim: growth in order to provide more jobs for more disabled people, but always considering the specific limitations that the disabled workers have. In this sense this paper shows one of the possible real applications where Operations Research can help not only to get economic and productive benefits but also certain social aims.     

Car sequencing versus mixed-model sequencing: A computational study

The paper deals with the two most important mathematical models for sequencing products on a mixed-model assembly line in order to minimize work overload the mixed-model sequencing (MMS) model and the car sequencing (CS) model. Although both models follow the same underlying objective, only MMS directly addresses the work overload in its objective function. CS instead applies a surrogate objective using so-called sequencing rules which restrict labor-intensive options accompanied with the products in the sequence. The CS model minimizes the number of violations of the respective sequencing rules, which is widely assumed to lead to minimum work overload. This paper experimentally compares CS with MMS in order to quantify the gap in the solution quality between both models. The paper studies several variants of CS with different sequencing rule generation approaches and different objective functions from the literature as well as a newly introduced weighting factor. The performance of the different models is evaluated on a variety of random test instances. Although the objectives of CS and MMS are positively linearly correlated, results show that a sequence found by CS leads to at least 15% more work overload than a solution found by MMS. For none of the considered test instances and for none of the three different objective functions, CS is able to produce competitive results in terms of solution quality (work overload) compared to MMS. The results suggest that decision makers using CS should investigate whether MMS would lead to better sequencing orders for their specific instances.     

A comparison of heuristic algorithms for cost-oriented assembly line balancing

Two new heuristic algorithms for solving cost-oriented assembly line balancing problems -the Wage-Rate-Method (WR) and the Wage-Rate-Smoothing-Method (WRS) — are presented and compared with two known heuristics — the Positional-Weight-Method (PW) and the Positional-Weight-Wage-Rate-Difference-Method (PWWD) with respect to their solution qualities. Firstly, the heuristics are outlined and their computational effort is stated. Then, a theoretical worst-case bound for the solution quality is given and the results of an extensive performance study are reported. In the study the heuristics were investigated with respect to their solution quality by solving randomly generated line balancing problems and problems from literature. It can be concluded that PWWD and WRS are generally superior to PW and WR.Parts of this research have been supported by the Stiftung Industrieforschung.     

Supporting offshoring and nearshoring decisions for mass customization manufacturing processes

Offshore countries attract companies for a possible relocation of production processes through extremely low worker wages. Particularly, mass production processes seem to be highly appropriate for a relocation. However, while the impact of wage reductions can be directly estimated, an appropriate determination of additional cost consequences proves to be a complex task. For instance, on account of lower education standards and higher fluctuation rates, the average worker skills in offshore countries are often significantly lower than in high-wage countries like the United States. In order to appropriately analyze and evaluate the resulting tradeoff between wages and worker skills for mass customization manufacturing systems, this paper introduces a new approach that comprises a detailed mixed-model assembly line balancing. This approach provides a direct comparison of the estimated variable manufacturing costs by generating a country-dependent line layout for all competing locations. In order to validate the efficiency of the balancing approach and, in particular, derive general implications for management, several test series with various country configurations were executed. First, by attaining improvement rates of up to 40%, the capability of a generated Tabu Search procedure for finding appropriate line layouts was proven. Second, as the main result, the complexity of the variant program was identified as a crucial factor for offshoring decisions since it substantially affects variable manufacturing costs. This was particularly proven for countries with low worker skills, which attract offshoring/nearshoring through exceptionally low labor costs. Hence, companies that consider outsourcing production systems to those countries are strongly hold to examine these decisive effects thoroughly. Regarding this, offshoring becomes very promising for manufacturing processes characterized by a moderate variant complexity level.     

A Multiple-rule Heuristic for Assembly Line Balancing

This paper introduces a four-rule heuristic method for production/assembly line balancing which seeks to minimize the number of workstations for a given cycle time. To evaluate its performance, the proposed method was compared with 15 other heuristic methods ranging in complexity from random assignment of work elements to Hoffmann's enumeration procedure. The results, based on both randomly generated problems and problems taken from the literature, indicate that the proposed heuristic outperformed other procedures. Further, the suggested method was able to find the optimal solution for 57 (85%) of the 67 literature problems.