Cyclic Assembly Schedules

Cyclic assembly schedules are schedules which follow a repeating production pattern. Each component is produced at times that are integer multiples of the base planning period of the finished product. These schedules have the managerial advantages of ease of control and planning, since future production follows a familiar, repeating pattern. Establishing and maintaining such a schedule requires a system to protect the schedule when bottlenecks occur. This paper discusses some of these issues and describes a simple method for calculating the optimal parameters of a cyclic schedule in a multistage assembly operation when production intervals are power-of-two multiples of a base period specified by management. The cycles are based on an Economic Order Quantity analysis, which is applicable if demand for the end items is fairly steady as in the case of a facility that supplies components to an assembly line.     

Work Schedules and Body Rhythms

The human body changes its physiological functions throughout the 24-hour day. During waking hours, the body is prepared for physical work, while during the night sleep is normal. Attitudes and behavior also change rhythmically during the day. Work should be arranged to least disturb physiological, psychological, and behavioral rhythms to avoid negative health and social effects and to avoid reductions in work performance (Kroemer, Kroemer and Kroemer-Elbert, [20]).     

Optimality Criteria for Flowshop Schedules

This article considers the problem of scheduling n jobs on M machines in a flowshop and examines the present formulation of the problem. To understand the true nature of the problem, this article provides economic interpretations of various optimality criteria which are being used for solving the scheduling problem. A general optimization criterion, called minimization of opportunity cost, is proposed for flow-shop scheduling problems and the results of the sensitivity analysis of various optimality criteria are reported which indicate the need to reformulate the scheduling problem.     

Using Linear Programming to Design Oil Pollution Detection Schedules

This paper presents a flight scheduling system for sensor (infra-red and ultra-violet) equipped aircraft whose mission is the detection and prevention of harbor and coastal oil and hazardous material pollution. The aircraft scheduling model is a form of the stochastic traveling salesman problem which can be solved using linear programming. The objective of the model is to maximize the expected number of pollution incidents detected per pollution flight. The model requires as input parameters representing probabilities of pollution incidents occurring for different geographical sectors. These parameters are estimated using coastal and harbor shipping statistics for petroleum and hazardous material. The shipping statistics considered include movement of petroleum products along the Atlantic, Pacific and Gulf coasts as well as the movement of such commodities in the intra-coastal waterway system and the Great Lakes. Particular port characteristics and past pollution incident statistics are also used to estimate required parameters of the scheduling model. The constraints in the model concern the availability of aircraft, flight hours, mission hours, and the significant environmental factors which affect the performance of the sensors.     

针对不同后处理方式的彩色热浸镀液优选

为获得彩色镀层,钢板试样在添加了Mn、Ti、Ni、Cu和Ce等元素的热镀锌液中在420～620℃温度范围内进行热浸镀,并采用室温空冷,温水冷却和保温炉保温三种后处理方式,以试样表面色彩的均匀度和深度以及表面粗糙为基础建立量化评价体系,通过正交试验方法确定镀液综合性能优劣.结果表明,所建立的评价体系可较好地衡量镀液性能;添加Mn、Ni和Cu有利于提高镀液综合性能,Ce是有害元素,Ti的利弊与评价指标有关;并且优化镀液的组成还与后处理方式有关.     

Schedules for a two-stage hybrid flowshop with parallel machines at the second stage

Approximate solution algorithms are developed to find a minimum makespan schedule in a two-stage hybrid flowshop when the second stage consists of multiple identical machines. Computational experience comparing the ‘approximate’ makespans with their respective global lower bounds for large problems indicates that proposed polynomially bounded approximate algorithms are quite effective. It is shown that the proposed heuristic algorithms can be used to improve the efficiency of an existing branch and bound algorithm.     

基于均衡化对钢铁企业的生产采购协同研究

以某钢铁加工企业生产和采购为研究对象,采用精益方法解决原材料到货数量波动大、库存积压、缺货严重和资源投入过量等问题。提出了基于均衡化的订单分割计算方法,将月度计划均衡到工作日,以生产计划为母版制定采购计划,使用交期管理箱对计划到货进行控制,并使用帕累托方法对库位进行分配。根据改善过程中遇到的实际问题,给出了推行生产与采购均衡化改善的一些管理建议。改善后该工厂原料库存降低30%,人工成本和管理费用也明显降低。     

Improving Dielcometer Reliability

The paper discusses the effects of parasitic quality-factor modulation in a tuned circuit arising on parametric modulation and influencing a capacitance-sensor analyzer. Varicaps may be used for parametric modulation of a semiconductor capacitance in order to improve not only the reliability but also the accuracy of a dielcometric analyzer.     

Improving predictive distributions

Summary Consider a sequence of decision problemsS ₁,S ₂, ... and suppose that in problemS _i the statistician must specify his predictive distributionF _i for some random variableX _i and then make a decision based on that distribution. For example,X _i might be the return on some particular investment and the statistician must decide whether or not to make that investment. The random variablesX ₁,X ₂ ... are assumed to be independent and completely unrelated. It is also assumed that each predictive distributionF _i assigned by the statistician is a subjective distribution based on his information and beliefs aboutX _i. In this context, the standard Bayesian approach provides no basis for evaluating whether the statistician’s subjective predictive distribution forX _i is good or bad, and does not even recognize this question as being meaningful. In this paper we describe models in which the statistician can study his process for specifying predictive distributions identify bad habits, and improve his predictions and decisions by gradually breaking these habits.     

浮筏安装工艺的改进

浮筏是一类高效的隔振装置,目前正在向大尺度方向发展,由于筏架是一个弹性体,筏架支撑点的改变能导致安装面的挠度发生变化。在隔振装置安装中,仅以空间几何高度确定隔振器的安装状态,将难以避免由于安装面挠度变化导致的隔振器的实际载荷偏离设计值的现象。在分析产生这种误差起因的基础上,对浮筏的安装方法提出改进建议和实施方法,提出了共点负荷法安装的新工艺,该工艺能实现保障或提升隔振器的隔振效能的目的。     

机器人码垛机——生产率提高的利器

事实发生在JTM Products公司，该公司成立于1890年。当时称为凤凰石油公司（Phoenix Oil Company）．是墨非石油肥皂原来的生产厂家．同时还生产机器润滑油，两种主要产品的市场占有率估计为65％。总部设在美国俄亥俄州的Solon市．这家私营公司现在集中生产工业润滑剂以及进行定牌和专门制造方面的业务。