Browsing by Subject "Transfer Lines"

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Open Access
Analysis of Erlang transfer lines
(1997) Dönmez, Nebahat
Transfer lines are widely used in the modeling and analysis of complex production systems. The literature is mostly devoted to the analysis of transfer lines with exponential processing times. However, most of the time a part is |)rocessed through stages(phases) of exponential processing times. It is possil)le to model such systems by means of processing times that are A,·—Erlang distributed. In the modeling and solution of these systems, significant difficulties arise due to the nature of the problem. In this thesis, we propose a -Markov model for transfer lines consisting of n reliable machines with A—Erlang processing times and finite buffers. The arrivals to the system is Poisson distributed. A program coded in C which is capable of solving the Markov model of a three machine transfer line is also developed. Besides the commonly used performance measures, such as utilization of the machines, mean throughput, mean WIP level, we calculate the variance of VVIP so that it is possible to construct confidence intervals.
Open Access
On the distribution of throughput of transfer lines
(1998) Deler, Bahar
A transfer line corresponds to a manufacturing system consisting of a number of work stations in series integrated into one system by a common transfer mechanism and a control system. There is a vast literature on the transfer lines. However, little has been done on the transient analysis of these systems by making use of the higher order moments of their performance measures due to the difficulty in determining the evolution of the stochastic processes under consideration. This thesis examines the transient behavior of relatively short transfer lines and derives the distribution of the performance measures of interest. The proposed method based on the analytical derivation of the distribution of throughput is also applied to the systems with two-part types. An experiment is designed in order to compare the results of this study with the state-space representations and the simulation. They are also interpreted from the point of view of the line behavior and design issue. Furthermore, extensions are briefly discussed and directions for future research are suggested.
Open Access
Serial production lines under pull environment
(1996) Eskigün, Erdem
Uie aim of this thesis is to evaliuite the performance of transfer lines under pull environment. In this study, we have modelled a two-stage trcuisfer line separated by finite buffers by using Markov-Chcun representation. Experiments with different parameters were carried out to evaluate the different performance measures of the system. A two-stage simulation model was also constructed by using the package PromodelPC 2.0. Since two-stage models are limited to analyze most prcictical systems in manufacturing, we have extended it to an N-stage model. From the experiments performed for both two-stage and Nstage models, we hcive observed that we can decreci.se the in-process inventory substantially by just exchanging the positions of the nicichines in the system. Assembly-disassembly systems under pull environment have also been modelled by using simulation.