PERT图的结点优化分布算法及计算机实现

本文介绍用计算机自动生成PERT图时的结点逻编定位算法。所提出的算法因引入了虚结点而可分列处理,减少了问题的复杂性。文中介绍了为得到布局合理的图形而对结点分布进行优化的方法。文中提出的算法均已在计算机上实现。     

试论PERT中作业持续时间的期望与方差的估值

本文讨论了PERT中作业持续时间的期望与方差的估计式的由来及适用范围。在假设作业持续时间服从正态分布或特定的β分布的条件下,导出了估计式及其适用范围;在假设作业持续时间的分布函数只知道三点值的条件下,借助逆变换关系及插值法,导出了期望与方差的表达式,进而归纳出估计式的适用范围。     

混合销售预测模型

为提高产品销售预测的准确性,为企业生产决策提供有力的参考依据,建立BP＿Adaboost和计划评审技术PERT混合销售预测模型。将BP神经网络模型与Adaboost算法进行结合,克服单纯使用BP神经网络容易陷入局部极小值的问题;计划评审技术PERT有效利用销售管理人员的经验,在一定程度上实现对销售数据偶然性的预测;将BP＿ Adaboost和计划评审技术PERT组成混合模型进行销售预测。实验结果表明,该模型提高了销售预测的准确性和有效性。     

采用可用度理论的瓶颈设备前缓冲时间估计

针对确定缓冲时间困难的问题,提出了一种基于可用度理论的缓冲时间估算方法,将瓶颈前的每道工序都看成独立的单部件可修系统,根据故障率和维修率由马尔可夫过程方法得到该工序的持续时间估计,从而估计出必需的缓冲时间.分别给出了瓶颈前有单个工序、多个工序串联、并联或混联时的缓冲时间估算公式,还提出了一种改进模糊概率PERT方法,对得到的缓冲时间进行可信度计算.基于在制品存储费用和概率风险损失给出了缓冲时间的最优化模型.仿真试验的结果表明,该方法得到的缓冲时间合理、可信.     

Risk analysis for occupational safety and health in the textile industry: Integration of FMEA,FTA, and BIFPET methods

Identifying and managing health and safety risks that threaten personnel in production systems are vital for the continuity and success of organizations. Many tools are used to accurately analyze and assess risks. Failure mode and effect analysis (FMEA) is one of the most commonly used tools in different industries. However, the accuracy and reliability of FMEA method have been fairly criticized by many researchers in the field. In this study, an approach based on FMEA that integrates the advantages of the fault tree analysis (FTA) method and belief in fuzzy probability estimations of time (BIFPET) algorithm has been proposed in order to improve the performance of the FMEA method. In order to practically apply the proposed method to real life problems, it has been employed to analyze and assess the potential risks for a finishing process in the fabric dyeing department of a textile company. The performance of the proposed FMEA-FTA-BIFPET method has been compared to the results obtained by FMEA-FTA and FMEA-FTA-program evaluation and review technique (PERT) distribution integrated methods. The results of this study show that failure related to fabric trimming adjustment in the tenter has the highest risk priority number. The proposed approach can be used in various industry for risk analysis. In addition, results obtained by the study have indicated that the proposed approach can be implemented in practice to perform comprehensive risk assessment procedures as it reflects real-life dynamics to analyze and assess potential risk.     

关键链方法在项目进度管理中的应用研究

介绍了关键链(CCM)方法,指出了其对CPM/PERT的改进之处,然后构建了基于CCM的项目进度管理体系,最后指出了该体系的应用条件,以期促进CCM在提高项目管理绩效方面的应用与研究。     

改进的PERT项目工期方差的估算方法

提出了针对于经典PERT方法假设条件过于苛刻,方差估算公式固定单一等局限性的改进方法。仅保留一个PERT假设条件,按照Malcolm(1959)最初的意图,将最可能值m与Beta分布的众数M相对应,并且考虑其对方差的影响将PERT方差公式进行改进。仿真与实例证明,改进后的PERT方差估算方法具有更大的柔性和合理性,能够更好地反映多变的、不确定的实际问题。     

Cyclic Scheduling of Operations for a Part Type in an FMS Handled by a Single Robot: A Parametric Critical-Path Approach

We consider two problems of periodic scheduling of parts in a robotic production system functioning under a given repetitive robot's route. The objective is to determine the starting times and durations of processing operations so as to minimize the cycle length. We reduce the problems to finding parametric critical paths in networks with varying arc lengths. In contrast to previously known methods, which solve these cyclic scheduling problems in cubic time, the parametric network approach solves the problems in time, m being the problem size.     

基于蚁群算法的计划调度应用研究

计划调度评审技术是系统工程中对潜在任务进行分析的一种方法,是一种科学的组织管理技术,其建立的目的是为了简化复杂项目的计划和分配任务的时间。文章将蚁群算法应用于计划调度的工期-费用优化问题之中,得到一种精确、全面,求解效率高的优化方法。     

PERT网络计划图自动布点的研究

提出一种PERT网络图自动生成算法,可以直接生成PERT网络图,以及在自动布点后的网络图上进行交互式的修改,使图形原则上以屏幕的横向中线为中心对称分布。