Production Rate of Transfer Lines Without Buffer Storage

We consider transfer lines without buffer storage in between the machines and with synchronous transfer. The processing time of each machine is a constant but machines are unreliable. Our analysis is based on the overall completion time of the transfer line, which is the time between successive transfers of parts within the line. Two techniques are presented. The first one provides lower and upper bounds on the production rate. These bounds can be made as tight as desired. The second technique provides an approximation of the production rate. It is based on the approximation of some distributions by simpler distributions having the same mean and coefficient of variation. We first consider the case of transfer lines with identical processing times and exponential times to failure and times to repair. Extensions to different processing times and general repair times are also discussed.     

Allocation of Buffer Capacities for a Class of Fixed Cycle Production Lines

The sequential relay model of a fixed cycle production: line is considered in which integer buffer capacities can be allocated between each pair of adjacent production facilities. The feasible sizes of any set of allocations is constrained by a general system of linear constraints. Upper and lower bounds are established for the steady-state system output and certain concave, separable programs are formulated to determine buffer capacities. The result of the optimization process is integrated into a simulation model for comparison and evaluation.     

Justification for Installing Buffer Stocks in Unbalanced Two Stage Automatic Transfer Lines

This paper deals with the role of inventory banks in balanced and unbalanced flow-line production systems by presenting results of a theoretical study of the problem and numerical experiments by computer simulation. It is shown that if the costs of both storage capacity and division of the line for a buffer are high, and therefore installing a buffer is not possible, then the line should be designed to have the same cycle times over all stages. When installing a buffer is possible, the line should be designed in such a way that the stage production rates are the same. Provision of a buffer in this case will improve line output.     

On the Production Capacity of Automatic Transfer Lines with Unlimited Buffer Space

In this paper we derive a general formula for the production capacity of automatic transfer lines where partially processed units may have to be scrapped when the machine fails. In the derivation of this formula it is assumed that the buffer spaces between adjacent work stations are unlimited.     

An Approximate Model of Multistage Automatic Transfer Lines with Possible Scrapping Of Workpieces

We consider multistage automatic transfer lines with unreliable stages, finite interstage buffer storages, and possible scrapping of workpieces. It is assumed that the first stage never idles and the last stage never becomes blocked. Assuming that uptimes and downtimes of a stage are geometrically distributed, an approximate model is developed to compute different performance measures of the transfer line. The results obtained through the approximate model are compared to the exact results for three-stage transfer lines and to simulation results for longer transfer lines. It is observed that the approximate results are good in almost all cases considered.     

Analysis of the Effect of Buffer Storage Capacity in Transfer Line Systems

The purpose of this paper is to gain insight into the effect of buffer storage capacity in two-stage transfer lines by presenting results of a theoretical study of the problem. A Markov model of the problem is proposed to analyze the effect of in-process inventory banks on the production rate and the mean number of units in the storage area. Based on the model developed, the effect of internal storage is evaluated, and the question of how much buffer storage capacity should be provided is discussed.     

Optimal Scheduling in a Multistage Flowshop

The combinatorial approach to solve the n-job, .M-machine flowshop scheduling problem is examined. The mathematical developments of the Dudek-Teuton algorithm shown are correct and valid if correctly interpreted. However, the optimality conditions developed by these authors are too stringent and as such the combinatorial analysis for the flowshop scheduling problem is extended and an algorithm is proposed for the solution of the multistage flowshop scheduling problem, where the objective is to minimize a specified measure of total production cost and jobs have their associated start and stop lags.     

An Approximation for the Production Efficiency of Automatic Transfer Lines with In-Process Storages

This paper considers the production efficiency of automatic transfer lines where in-process storages are provided for stochastic station breakdowns. A simple approximation method is developed in order to readily obtain the production efficiency and show the benefit of providing storages even for long lines. Additionally, the optimal partitioning of the line and the method of allocating capacities for storages are numerically investigated.     

Analysis of Transfer Lines Consisting of Two Unreliable Machines with Random Processing Times and Finite Storage Buffers

A Markov process model of a transfer line is presented in which there are two machines and a single finite buffer. The machines have exponential service, failure, and repair processes. The movement of discrete parts is represented. The model is analyzed and a compact solution is obtained. Limiting behavior is investigated and numerical results are discussed.     

Texture Transfer Mechanism of Buffer Layer in Coated Conductors

We have studied the texture transfer process of buffer layers prepared by chemical solution deposition (CSD) methods on YSZ (00l) single crystal substrates and biaxial textured Ni?CW substrates. The structure, texture, and surface morphology of the buffer layers were investigated by X-ray diffraction (XRD), atomic force microscopy (AFM), and scanning electron microscopy (SEM). Our results show that the degree of texture and the surface morphology of the buffer layers vary with the changes of the substrate and the lattice mismatch of the top buffer layers with La₂Zr₂O₇ (LZO) after crystallization in argon?Chydrogen atmosphere. Moreover, the growth mode of multi-layer films and the type of the lattice strain have strong influence on the formation and the transfer of the bi-axial texture in multi-layer buffer architecture. It suggests that there exists a possible connection between the strain relaxation and the texture transfer in buffer layer fabricated by CSD methods. Information on the texture transfer of buffer layer is important for optimizing the buffer layer architecture in coated conductors.     

Optimal Availability Allocation in a Multicomponent System

In designing a multicomponent system, the use of availability as one of the criteria instead of reliability seems to be more reasonable. In this article, a method for allocating availability optimally to a multicomponent system is presented.     

EGS环境下的订单分配优化分析

将在线与店内顾客购物冲突引起的通道拥塞问题简化为排队等待时间优化问题,以订单在店内的最大等待时间最小化为目标,利用M|M|1排队系统建立了排队论优化模型.算例分析显示:在最优解中,该模型试图令所有的商店均达到工作载荷均衡,从而在配送预算范围内的任意时刻拥塞程度均可达到最小化.在敏感度分析中,最优等待时间与成本预算和总利用率两个变量密切相关,即当配送预算和总利用率达到某个特定值后,再次下降时,等待时间将分别发生显著增加和减少,这将对系统的绩效产生负面影响.     

不确定收益下关键链项目缓冲前置分配模型

在关键链项目管理技术中,缓冲的设置和监控是决定项目计划稳定性和有效性的关键一环.但现有的理论对项目缓冲的分配却没有一个清晰的界定.由于工序在执行时具备可延迟的特性,我们把实物期权的思想引入项目缓冲的分配过程中,通过将缓冲区前置,设计不确定性的概率分布来建立一个基于实物期权的0-1整数规划模型.将关键链管理思想和最迟开工规则有机结合,使得时间缓冲能够在各个关键工序中的灵活分配,实现关键链项目管理期权价值最大化.     

Two Outfalls in an Estuary: Optimal Wasteload Allocation

When two outfalls are discharging wastewater into a narrow (rapidly mixed) estuary within a tidal excursion of each other, the pollutant concentrations experienced at the two outfall sites are strongly inter-dependent. It is shown how a given total tidally integrated effluent load can be allocated optimally between the two outfalls so that the peak concentration (in time and position) of the principal contaminant species is minimized. Graphical results show the dependence of the wasteload allocation and of the peak concentration upon the pollutant decay rate, the separation between the outfalls and the fresh water flow along the estuary. Optimization with respect to any one of a mixture of pollutants is close to optimal for a wide range of other pollutants.     

An Analysis of Automated Storage and Retrieval Systems in Manufacturing Assembly Lines

An automated storage/retrieval system is a material handling system that can be used to pick and to deliver materials in a direct access fashion. An M/G/1 queueing model is used to study the system performance under a first-come-first-served dispatching rule. More detailed studies for different dispatching rules have been done by simulation. A number of cases with different hardware characteristics and workloads have been investigated. Conclusion is drawn based upon the results obtained from analysis as well as numerical experiments.     

多温级蓄能制冷系统动态特性模拟及分析

通过对用于工业和商业领域内需要多个制冷温度等级的,以氨水为工质的多温级蓄能制冷方法和工作流程的介绍,以长江流域某一典型的两温级冷库作为算例,对该蓄能系统在全量蓄能策略下能量转换及储存过程进行数值模拟,得到系统各设备负荷的大小和变化特性、循环工作参数随时间和外部条件的变化规律。研究结果为了解多温级蓄能制冷系统的运行特性、系统设计和设备选型以及制定动态控制方案提供帮助。     

储油罐自动计量系统的研制

以前测量油罐内油量及水量的方法是基于油水界面很明显,不考虑油罐内存在油水过渡带,而实际情况并非如此。本文先论述原油储罐油水量在线监测系统组成结构,再利用倒推法确定圆柱形油罐内油水量的基本原理,以及本系统的特点及注意事项,具有结构简单,经济适用的特点。     

Mechanical Analysis and Optimal Design on Transfer Case

Transfer case of all-terrain vehicle is classic cylindrical helical gear rotor system for power transmission. The power of motor is distributed to the driving axles through it. The mechanical model is established to study its performance and the data is applied to design the structure.     

Automatic Transformation of Curved-to-Flat Calibration Lines by a Normalizer

In high-accuracy swept-frequency insertion-loss testing, antenna-pattern measurement, and many other applications, significant measurement-system output variations are caused by the system itself. These variations can be recorded and subtracted from the measurement results to provide the required accuracy generally by recording system calibration lines with attenuation standards in the test position and reading the measurement results against these calibration lines. However, the procedure is tedious, costly, and does not lend itself to automation. The linearizer is a device for storing the system calibration and correcting for it before displaying the results. With no loss in accuracy, it provides an output curve that can be read on an ordinary rectilinear graph, used to actuate GO-NO GO switches, or automaticaly compare a test piece against a standard. Details of operation and some performance data are given for a particular analog-type linearizer and associated swept-frequency measurement system for insertion-loss or scattering coefficients. The linearizer can readily display a scale of 0.02 dB/inch with adequate stability and reproducibility. Two such linearizers can be used together to display two components of a vector or phase and amplitude, etc. Other applications are discussed and several possible approaches to an ideal system shown.     

Parallel Operation of Sequential Service Lines with Interline Transfer

Scientific analysis of servicing processes has resulted in the development of sequential servicing where a unit requiring service is processed through a fixed number of stages sequentially. A detailed study of such a system has been presented by Boling (1). This paper considers a large servicing system consisting of a finite number of identical sequential service lines. These lines are operated in parallel, but interline transfers of units are made whenever advantageous. Using time homogeneous Markov chains, a model is developed for analyzing the operation of such a system, which shows that interline transfers of units result in improved performance of the system. Practical considerations in the implementation of this mode of operation are discussed, and the model is illustrated.