A Heuristic for Multiple Lot Sizing For an Order Under Variable Yield

Consider a job shop which must completely fill a large make-to-order demand of a product where production yield is highly variable. After a production lot is completed, if the total output of satisfactory units is inadequate to satisfy the demand, then a new run (with associated setup cost) is made. When the output of good units exceeds the demand, then the excess units are scrapped (with possible salvage value). The optimal lot size minimizes the total of production, setup, holding, shortage, and scrap costs. A heuristic is developed based on the incremental cost of increasing the lot size by one unit. The computational ease and excellent cost performance of the heuristic favor its use in place of the mathematically optimal solution obtained by dynamic programming. Real world manufacturing applications and additional properties of the model are also discussed.     

启发式遗传算法的生产能力约束多产品再制造批量决策

建立了生产能力约束条件下的再制造批量决策模型,同时考虑了批量制造、批量再制造和外包,确定性的需求由批量制造、批量再制造和外包来满足.利用启发式遗传算法求解多产品再制造批量模型,研究了种群大小和迭代次数对遗传算法实验的影响,并通过一些算例来证实了算法的有效性.     

Lot Splitting Under Learning Effects with Minimal Revenue Requirements and Multiple Lot Types

The lot splitting problem in the presence of learning is addressed. This work is an extension of an approach proposed for splitting in the case of a single item. We address the issue of a minimal revenue requirement from partial deliveries until a predetermined time. This is achieved by imposing a constraint on what is originally an unconstrained optimization problem. When sublots of different items are involved, the optimal splitting decisions have to be combined with the sequencing of the deliveries. Numerical examples are presented to demonstrate the proposed approach.     

Joint Lot Sizing and Inspection Policy in an EOQ Model with Random Yield

We study a joint lot sizing and inspection policy under an EOQ model where a random proportion of units are defective. Those unitscan be discovered only through costly inspections. The problem is thus bivariate: both lot size and fraction to inspect are to be chosen. We first analyze a model in which the only penalty for uninspected defectives is financial, and then consider a model where defective units cannot be used and thus must be replaced by non-defective ones.     

Simultaneous Lot Sizing and Sequencing for Multistage Production Systems

Inventory and scheduling theory have, in general, been developed independently. This paper presents a model which integrates these two traditionally different aspects of production planning in a multi-stage environment by transforming a lot-sizing problem to an equivalent job-shop scheduling program. The proposed model may improve the effectiveness of existing decision making processes.     

Lot Sizing with Several Groups of Single-Cycling Retailers and One Warehouse

In this paper I describe a consecutiveness rule for grouping N retailers into m groups with independent single-cycle policies for each group which enables the creation of groups using a shortest-path approach. I also suggest a very efficient algorithm to compute the lot sizes for any single-cycle policy which can easily be incorporated into the shortest-path model for the creation of m single-cycle groups.     

基于寄售的供应链批量协调问题研究

随着生产商柔性的提高,在基于寄售库存的供应链中,生产商和批发商的订货及库存持有成本发生了显著的变化,以此为背景,建立了一对一的供应链在寄售情形下的成本函数和批量模型,提出了当生产商的最优生产批量小于批发商的最优订货批量时,生产商可以通过按批发商的订货批量提供一定比例寄售,并转移部分获得收益给批发商的批量协调策略。算例分析表明,在一定条件下,该策略能够使生产商和批发商同时受益,从而使整个供应链实现帕累托优化。     

A Branch and Bound Algorithm for a Single-Item Multi-Source Dynamic Lot Sizing Problem with Capacity Constraints

In this paper we present a branch and bound algorithm for solving a single-item, multi-source dynamic lot sizing problem with time-varying capacity constraints. We consider a single-item production (and/or procurement) environment where there are multiple sources of supply with different cost structures. Computational results are presented.     

Experimental Evaluation of Conducted Emissions by Variable-Speed Drives Under Variable Operating Conditions

This paper presents an experimental study about the effects that various operating conditions have on conducted emissions by variable-speed drives. The objective of the research is to determine what quantities most significantly affect emissions so that electromagnetic compatibility test procedures can be carried out under the most appropriate conditions according to the specific destination of the equipment under test. The obtained measurements would so match the standard's requirement that they represent the worst case for the disturbance emission levels. A quantitative analysis has been made possible by introducing two indexes with values determined by emissions over the measurement band. The effects of voltage asymmetry and amplitude, motor operating frequency, and torque applied to it have been investigated. Results show a strong dependence on motor operating frequency and torque and that the fluctuations in the measured emissions largely depend on the measurement configuration adopted.     

Damage Tolerance Evaluation of Rotorcraft Horizontal Tail Under Variable Amplitude Service Loading Conditions

Journal of Failure Analysis and Prevention - To ensure the safe operation of the helicopter throughout its lifetime, the primary structure has to be designed taking into account damage tolerance...     

20GrMnTi合金钢下屈服强度测量不确定度的评定

本文主要介绍20GrMnTi合金钢屈服强度测量不确定度的评定方法。     

单件小批条件下的动态生产函数模型

基于微观投入产出理论，本文总结了几种动态生产函数，并对其在单件小批订货生产类型企业的生产决策中的应用条件进行了研究。提出了改进基本模型的具体方案。     

Evaluation and Analysis of Heuristic Techniques for Vector Ordering of VLSI Test Sets

Vector ordering is an essential task in testing very large scale integration systems because it affects this process from two perspectives: 1) power consumption and 2) correlation among test data. The former feature is crucial and, if not properly controlled, may result in permanent failure of the device under test (DUT). The latter feature is also important because correlation is captured by coding schemes to efficiently compress test data and ease memory requirements of automatic test equipment (ATE) while reducing volume and lowering test application time. Vector ordering, however, is NP-complete. This paper presents an evaluation of different heuristic techniques for vector ordering using the 1985 and 1989 IEEE International Symposium on Circuits and Systems (ISCAS85 and ISCAS89, respectively) benchmark circuits in terms of run time and solution quality. For this application, it is shown that the best heuristic technique is not the one based on the famous Christofides or Lin–Kernighan criteria but on the multifragment technique. It has been shown that the selection of an appropriate heuristic can lead to an increase in the compression ratio of up to 178% and a reduction in the power consumption during test of up to 46%.      

多台泵变频调速运行方案性能仿真研究

基于多台泵性能曲线图，针对并联泵采用一台泵调连加两台泵定速、两台泵调速加一台泵定速和三台泵同时调速方案，建立分别调速过程的方程组，用仿真的方法模拟定速泵、调速泵的泵效率、功率与背压、调节流量的变化规律，为并联泵在各种调节工况运行、控制设计提供理论分析，所得结论具有普遍意义。     

An Improved Extended Basic Period Procedure for Solving the Economic Lot Scheduling Problem

This paper describes an easily programmable procedure for solving the problem of determining lot sizes for n products to be produced on a single machine. The procedure is based upon the extended basic period approach of Elmagrahby. Feasible solutions are obtained by restricting the number of periods between runs for each product to the powers of 2. The effectiveness of the procedure is demonstrated by solving six problems originally solved by Fujita. Significantly better answers were found for five of the six while in one case the procedure generated a solution that was only slightly inferior.     

An Extension to the Class of Easy Economic Lot Scheduling Problems

We extend known conditions under which a rotation schedule is optimal in the Economic Lot Scheduling Problem by using a tighter lower bound that explicitly considers machine capacity. We also show how these results can be used when backorders are allowed.     

An Economic Lot Size Model for Perishable Products with Age-Dependent Inventory and Backorder Costs

This paper presents an Economic Lot Size (ELS) model for perishable products where the costs of holding inventory stocks (having backorders) in each period depend on the age of inventories (backorders). We propose a polynomial-time dynamic programming algorithm to solve two structured problems, one with non-decreasing demands and the other with non-decreasing marginal backorder cost with respect to the age of the backorder. Our results generalize a recent study on an ELS model for perishable product but without backorders.     

Al-Si合金熔体变质效果评估判据

综述了评价铝硅合金变质效果的一般方法,主要有断口观察法、电导率法、金相法和热分析法.重点分析了热分析技术的各个判据,指出了目前热分析判据研究的两种动向,并指出人工神经网络技术结合成熟的热分析技术将有广阔的应用前景.     

水溶性上浆剂改性芳纶增强环氧复合材料界面研究

为提高芳纶与环氧树脂间的界面结合力,本文开发了一种新型水溶性上浆剂,该上浆剂具有环保,不改变原有工艺等特点。该上浆剂能在芳纶表面通过自组装形成一层单分子层,该单分子层可以参与环氧树脂的固化,增大复合材料层间剪切强度,上浆后界面剪切强度提高23.81%,该方法可以在不损伤芳纶本身性能前提下提高与环氧树脂间的界面剪切强度,并且可以修复纤维表面的缺陷。