The impact of unequal processing time variability on reliable and unreliable merging line performance

Research on merging lines is expanding as their use grows significantly in the contexts of remanufacturing, reverse logistics and developing economies. This article is the first to study the behavior of unpaced, reliable, and unreliable merging assembly lines that are deliberately unbalanced with respect to their coefficients of variation (CV). Conducting a series of simulation runs with varying line lengths, buffer storage capacities and unbalanced CV patterns delivers intriguing results. For both reliable and unreliable lines, the best pattern for generating higher throughput is found to be a balanced configuration (equal CVs along both parallel lines), except for unreliable lines with a station buffer capacity of six. In that case, the highest throughput results from the descending configuration, i.e. concentrating the variable stations close to the beginning of both parallel lines and the steady stations towards the end of the line. Ordering from the least to most steady station also provides the best average buffer level. By exploring the experimental Pareto Frontier, this study shows the combined performance of unbalanced CV patterns for throughput and average buffer level. Study results suggest that caution should be exercised when assuming equivalent behavior from reliable and unreliable lines, or single serial lines and merging lines, since the relative throughput performance of some CV patterns changed between the different configurations

Unbalanced manual flow line operating characteristics.

This thesis studies the operating behaviour of the manual unpaced lines, which are the most important of the flow lines' systems. The lines examined are unbalanced and six types of imbalance are considered, namely, the imbalances of mean service times, coefficients of variation (Covars), buffers'capacities, means and Covars, means and buffers, and Covars and buffers. It is argued that the deep understanding of the behavioural characteristics of such lines, contributes towards the achievement of practical solutions to many of their problems. The lines are simulated under both steady and non-steady states conditions, with positively skewed weibull work times distributions, different values of line length (N), buffer capacity (B), degree of imbalance (DI), and pattern of imbalance, utilizing full factorial designs.The data are subjected to the analysis of variance, multiple regression, multiple comparisons with control, pairwise comparisons, canonical correlation, and utilitv analysis A simple utility approach is also explored briefly.Some of the important conclusions for all the unbalanced lines' investigations are:(1) At least one unbalanced pattern generates superior idle time (I) and/or mean buffer level (ABL), over those of a balanced line. The superiority in I decreases as DI rises, whereas the advantage in ABL reduces as DI is decreased.(2) The DI of the best unbalanced pattern can substantially or moderately be increased and still yields approximately equal I to that of a balanced configuration.(3) If a line is unbalanced in the wrong direction, significantly inferior performance to that of a balanced design will result.(4) The unbalanced patterns' I tends to decrease, when N and DI reduce and B increases, while ABL falls directly with B.(5) The I's transient size increases as N and B become higher and DI increases, while the ABL's transient size rises whenever B reduces

The line balancing algorithm for optimal buffer allocation in production lines

Cataloged from PDF version of article.Buffer allocation is a challenging design problem in serial production lines that is often faced in the industry. Effective use of buffers (i.e. how much buffer storage to allow and where to place it) in production lines is important since buffers can have a great impact on the efficiency of the production line. Buffers reduce the blocking of the upstream station and the starvation of the downstream station. However, buffer storage is expensive both due to its direct cost and the increase of the work-in-process inventories it causes. Thus, there is a trade-off between performance and cost. This means that the optimal buffer capacity and the allocation of this capacity have to be determined by analysis. In this thesis, we focus on the optimal buffer allocation problem. We try to maximize the throughput of the serial production line by allocating the total fixed number of buffer slots among the buffer locations and in order to achieve this aim we introduced a new heuristic algorithm called “Line Balancing Algorithm (LIBA)”applicable to all types of production lines meaning that there is no restriction for the distributions of processing, failure and repair times of any machine, the disciplines such as blocking, failure etc. and the assumptions during the application of LIBA in the line.Selvi, ÖmerM.S

Engineering data compendium. Human perception and performance, volume 3

The concept underlying the Engineering Data Compendium was the product of a research and development program (Integrated Perceptual Information for Designers project) aimed at facilitating the application of basic research findings in human performance to the design of military crew systems. The principal objective was to develop a workable strategy for: (1) identifying and distilling information of potential value to system design from existing research literature, and (2) presenting this technical information in a way that would aid its accessibility, interpretability, and applicability by system designers. The present four volumes of the Engineering Data Compendium represent the first implementation of this strategy. This is Volume 3, containing sections on Human Language Processing, Operator Motion Control, Effects of Environmental Stressors, Display Interfaces, and Control Interfaces (Real/Virtual)

Human Factors Certification of Advanced Aviation Technologies

Proceedings of the Human Factors Certification of Advanced Aviation Technologies Conference held at the Chateau de Bonas, near Toulouse, France, 19-23 July 1993