混合粒子群算法在混流装配线优化调度中的应用

应用粒子群算法求解混流装配线的优化调度问题,给出粒子的构造方法,并针对算法中存在过早收敛的问题,提出了一种与局部优化和粒子微变异方法相结合的混合粒子群算法.给出了一个实例,实例应用粒子群算法和混合粒子群算法分别进行求解,与其他一些方法比较表明,混合粒子群算法可以有效、快速地求得混流装配线优化调度问题的解.     

SPS模式下零部件配送质量的混流装配线总装排序

针对零部件供应不能实现JIT的混流装配线排序问题,提出在SPS物料配送模式下,以提高零部件配送质量为目的,分析拣选环节筐车排列顺序对零件拣选错配和漏配的影响,从两方面探讨通过安排筐车排列顺序以最小化拣选错配和漏配率;同时在总装环节,追求零部件消耗速率均衡化.从而建立同时考虑总装和零部件配送两阶段优化的混流装配线排序模型.结合排序案例,证明该排序模型能在平准化零部件消耗的同时提高配送质量.     

考虑转换约束的汽车混流装配线投产排序研究

讨论了有生产线线边替补人员协助完成超载工作量的情况下,汽车混流装配线投产排序的问题,并且考虑工作人员行走占用的时间。通过对某整车厂进行实地调研,将汽车装配生产中的优化问题从以往文献中只考虑的总装车间向前延伸到涂装车间,给出连续喷涂某种颜色的车辆数的上界s。在此基础上,并考虑总装线线边物料消耗速率波动均衡和子装配工负荷均衡的约束条件,建立涂装切换成本和总装车间人工成本最小化的数学模型。最后,用CPLEX对模型进行优化求解,并分析得出生产节拍和工作站长度等参数与总成本之间的变化关系。     

考虑需求紧迫度差异与公平分配的三级应急物资调度研究

各受灾点因灾情不同对获取不同类别物资的需求紧迫度存在较大差异,忽略这一现实情况的模型会导致有限应急物资无法公平分配和高成本等问题。与已有文献相比,首先,引入了CRITIC法计量各灾点对有限物资需求的波动性与冲突性,提出需求紧迫度量化方法;其次,运用极小极大函数对已有研究的公平目标予以改进;然后,针对突发灾害时长途调运物资的现实情况,采用“储备点-中转站-受灾点”三级结构进行分析;之后,建立了以各灾点最大物资短缺度最小和调度成本最小为目标的多目标混合整数规划模型;最后,利用模糊理论对模型进行等价转化,设计改进遗传算法进行求解。算例分析证明,该模型在保障多受灾点之间物资分配公平性的同时,能够有效控制调度成本,可为现实突发灾害应急物资调度提供决策支持。     

考虑人员能力差异的装配生产线优化

针对具有人员能力差异的装配生产线节拍优化问题,建立数学模型,提出一种先分配工序、后分配工人的分步求解启发式方法,并分别利用双种群遗传算法和分枝定界法对其进行求解;提出构建原优化问题的上下界,并以某企业的装配生产线为实例,验证了本方法的有效性与实用性。     

考虑工人疲劳的工作排程研究

为提高企业整体生产力,降低工人累积性疲劳对生产过程的影响,在综合考虑工人疲劳与作业负荷的基础上,以单人多任务排程为研究对象,工人的最大可接受工作时间为休息与否的判定依据,构建了单人工作-休息排程的数学模型。从不同的工作休息组合中选出最佳的排程组合,以优化最小化任务的最大完工时间和因工人工作时间超过最大可接受工作时间而产生的额外能量消耗双目标函数。应用线性加权和法将多目标化为单目标用遗传算法求解,通过算例分析得出模型的满意解,从而得到任务的排序以及工人的休息时间和休息次数的排程组合方案。模型存在多个满意解,为管理者提供多种备选方案,管理者根据实际情况选择实施最优化的组合方案。     

考虑使用优先权的泊位分配和船舶调度集成优化

本文针对单向航道单港池的离散泊位散货港口,对固定计划期内船舶调度和泊位分配的集成问题进行研究,考虑了船舶进出港与船舶靠离泊的时间和空间的约束,重点兼顾了由于船舶靠泊优先权引起的移泊问题带来的现实限制,构建了以船舶总在港时间最小为目标的集成优化模型,设计了免疫遗传算法进行求解,并给出了泊位分配方案、移泊方案以及船舶进出港...     

一种工序公差的并行优化分配方法

在产品的最初设计阶段,首先把所需的装配功能公差分配给各有关零件的相关尺寸,然后把这些尺寸表示为工序尺寸,利用工序公差链,将产品的功能公差直接表示为工序公差。通过建立并求解化模型,可实现工序公差的并行优化设计,最后给出了一个工程实例。     

卡诺制冷机的Yong损率和Yong效率优化

应用有限时间热力学理论研究内可逆卡诺制冷机的Ｙｏｎｇ损率和Ｙｏｎｇ效率，导出它们与制冷率间的优化关系，并作了分析和讨论。获得一些有意义的新结论，可供制冷机的优化设计和最佳工况选择时参考。     

考虑供应商交货数量风险的订货量分配模型

针对有装配线最小批量要求且供应商交货数量随机条件下的多物料订货量分配问题,以订货成本、采购成本、库存持有成本和拖期成本组成的总成本最小为优化目标,构建了混合整数随机规划模型;使用离散粒子群优化算法对模型进行求解,通过两组算例将粒子群优化算法与遗传算法和枚举算法进行了对比分析,算例结果验证了离散粒子群优化算法解决该问题的可行性和有效性。最后,通过一组实例分析了不同单位拖期成本和单位库存成本情形下的订货量分配方案以及单位拖期成本/单位库存成本这一比例对总成本的影响。实例结果表明,物料的订货量分配方案与单位拖期成本/单位库存成本有关,且总成本与该比例呈线性相关关系。     

Worker coordination policies in parallel station systems: performance models for a set of jobs and for continuous arrival of jobs

Varying workloads and uncertain processing times in parallel assembly cause idle times for skilled, high-cost workers. This idleness can be avoided and the utilisation of the workers improved by allowing workers to move between the stations to help each other. Worker movement between assembly stations needs efficient and feasible coordination, and therefore, this paper compares four different worker coordination policies: no helping, floater, pairs and complete helping. The dynamics of the policies are modelled by studying the parallel assembly as a continuous-time Markov process. The system is studied with two different job release cases for non-identical jobs (customised products). In the first case, a given number of jobs have to be completed by the entire system. In the second case, new jobs arrive with a Poisson-distributed rate. The models assume that when one worker helps another, their collaborative inefficiency reduces the productivity. The models are used in numerical experiments to compare the performances of worker coordination policies as average job cycle times. The main conclusions from the results suggest the use of the complete helping policy in minor collaborative inefficiency conditions, especially with a given set of jobs. The pairs policy is a reasonable alternative in major inefficiency conditions with the continuous arrival of jobs.     

A heuristic based on Vogel's approximation method for sequencing mixed-model assembly lines

Sequencing mixed-model assembly lines is a well researched topic in the literature. However, many methods that have been developed to solve this problem fail to cope with either the large size or the specific characteristics of real-life problems. In this paper, a heuristic is proposed that is derived from Vogel's approximation method for transportation planning. The heuristic is able to handle large and supposedly difficult problem instances. Sophisticated test scenarios considering real-life aspects were generated to evaluate the performance of the heuristic for realistic problem instances. It is shown that the proposed heuristic significantly outperforms priority rule-based methods and requires only reasonable computational effort.     

Minimising utility work and utility worker transfers for a mixed-model assembly line

Mixed-model assembly lines (MMALs) are types of production lines that are able to respond to diversified costumers’ demand for a variety of models without holding large inventories. The effective utilisation of a mixed-model assembly line requires the determination of the assembly sequence for different models. In this paper, two objectives are considered in a sequential manner, namely minimising: (i) total utility work, which means work from an additional worker to assist an operator for completion of an assembly task; and (ii) utility worker transfer which states the move of a utility worker to a different segment of the assembly line. First, due to the NP-hard nature of the problem, three heuristic methods are proposed with the aim of minimising total utility work. Then, the solutions which are obtained from the heuristics are improved in terms of the total number of utility worker transfers via a local search based method. Furthermore, the solution approach was applied in a real life mixed model tractor assembly line. Results validated the effectiveness of sequencing approach in terms of solution quality.     

A two-phase variable neighbourhood search algorithm for assembly line worker assignment and balancing problem type-II: an industrial case study

The assembly line worker assignment and balancing problem type-II (ALWABP-2) occurs when workers and tasks (where task times depend on workers’ skills) are to be simultaneously assigned to a fixed number of workstations with the goal of minimising the cycle time. In this study, a two-phase variable neighbourhood search (VNS) algorithm is proposed to solve the ALWABP-2 due to the NP-hard nature of this problem. In the first phase of the algorithm, a VNS approach is applied to assign tasks to workstations with the aim of minimising the cycle time while in the second phase, a variable neighbourhood descent method is applied to assign workers to workstations. The performance of the proposed algorithm is tested on well-known benchmark instances. In addition, the proposed algorithm has been used to solve a real case study from a consumer electronics company that manufactures LCD TVs. The results show that the algorithm is superior to the methods reported in the literature in terms of its higher efficiency and robustness. Furthermore, the algorithm is easy to implement and significantly improves the performance of the final assembly line for the investigated LCD TV real case study.     

装配作业的改善

根据天津夏利轿车新总装车间生产实际情况,提出了装配作业改善的几个主要方面,并举例介绍说明。     

湍流对气流分级效率影响的研究

以湍流脉动分量服从正态分布的假设为基础,导出湍流对分级效率影响的数学方程。方程数值解表明,湍流度越大对分级效率的影响越大,湍流对所有粒径的颗粒都有影响,但不会导致“鱼钩效应”的产生。     

手工装配作业单元的布局优化设计研究

针对典型的手工装配作业单元，将人的因素在布局中的影响定量化，结合物流因素，提出新的布局优化设计模型，并采用遗传算法对其求解。实例研究的仿真结果表明，基于新模型的手工作业单元的布局设计方案，在优化物流、保证作业效率的同时，还能优化作业姿态，从而降低作业者从事手工装配作业的平均能量消耗水平。     

复合结构减振优化设计模型

复合材料由于具有低密度、高阻尼和良好的比强度、比刚度等特性而被工程结构设计广泛采用。复合材料结构设计的特点在于力学性能设计和结构设计相结合,设计变量多,影响因素更为复杂,优化设计工作显得尤为重要。基于不同减振评价指标,结构动力学优化设计可以采用不同优化模型,减振效果也相差很大。以钢 -复合材料复合基座结构为例,研究采用功率流落差与振级落差进行减振效果评价,以结构总重量或评价点输出功率流等为目标函数,以钢板厚度、复合材料铺层数和铺层角度为设计变量,考虑应力约束时各种结构动力学优化数学模型,并采用多岛遗传算法进行求解,比较减振效果。研究表明,采用复合结构功率流优化模型能获得更佳减振效果。     

Strategy of Concurrent Optimization for an Assembly Sequence

An effective constraint release based approach to realize concurrent optimization for an assembly sequence is proposed. To quantify the measurement of assembly efficiency, a mathematical model of concurrency evaluation index was put forward at first, and then a technology to quantify assembly constraints was developed by application of some fuzzy logic algorithms. In the process of concurrent optimization of the assembly sequence, two kinds of constraints were involved. One was self-constraints of components, which was used to evaluate the assemble capability of components under the condition of full-freedom. Another was an assembly constraint between components represented by geometric constraints between points, lines and planes under physical restriction conditions. The concept of connection strength degree （CSD） was introduced as one efficient indicator and the value of it was evaluated by the intersection of the two constraints mentioned above. The equivalent constraints describing the connection weights between components were realized by a well designed constraints reduction, and then the connection weights based complete assembly liaison graph was applied to release virtual connections between components. Under a given threshold value, a decomposition and reconstituting strategy for the graph with the focus on high assembly concurrency was used to realize an optimized assembly concurrency evaluation index. Finally, the availability of the approach was illustrated in an example to optimize the assembly of a shift pump.