Line balancing in a just-in-time production environment: balancing multiple U-lines

The introduction of multiple, independent production lines has helped many firms to increase their production flexibility, provide for redundancy when equipment breaks down, reduce idle time and labor costs, and achieve many other benefits. This paper introduces and formalizes the multiple U-line balancing problem. Optimal solution methodologies are provided for Type I (minimize the number of stations for a given cycle time), Type II (minimize the cycle time for a given number of stations), and cost-minimization line-balancing problems. A branch-and-bound algorithm is also developed for the situation in which equipment requirements are dependent on the line configuration and the task assignment to stations. Computational results indicate that the greatest benefit of exploiting multiple lines occurs for smaller cycle-time problems that require higher output.     

Balancing stochastic two-sided assembly lines

In a two-sided assembly line, tasks can be executed simultaneously on both sides of the line. One task cannot be started until both of its direct predecessors on the left and right sides are completed. Therefore, the start time of the task is the maximum of the two predecessors’ finish times. In many realistic situations, it is assumed that the task times are independent and normally distributed with known means and variances. However, the maximum of two normal variables is not normally distributed, but can be well approximated by results from extreme value theory. In this paper, we utilise these results to develop a solution methodology to balance two-sided assembly lines with stochastic task times, minimising the line length and the number of stations while guaranteeing all tasks are completed within the cycle time with a given confidence level.     

Visual facility layout design system

This paper presents an integrated visual facility layout design system to solve layout problems with geometric constraints on a continual planar site. The system employs a tabu search algorithm as the search engine with heuristic neighbourhood control and a manual interference mechanism to obtain good solutions. The Windows®-based system provides layout designers with a friendly environment that can automatically search a good solution aided by the visual inspection function. The visual inspection function is a mechanism embedded in the search process that dynamically displays the improvement status and allows manual adjustment of facility location during the search. The system also serves as a powerful tool for performing 'what if' analyses for layout designers.     

A statistical approach to multiple-attribute decision-making with interval numbers

In multiple-attribute decision-making, the overall values of alternatives would be interval numbers due to the inherent uncertain property of the problems in the ambiguous decision domain. Bryson and Mobolurin proposed the use of linear programming models to compute attribute weights and overall values of the alternatives in the form of interval numbers. The intervals of the overall values of alternatives are then transformed into points or crisp values for comparisons among the alternatives. However, transforming the overall values of the alternatives from intervals to points may result in information loss. In this paper, statistical distributions, normal distribution and uniform distribution, are placed on the intervals of attribute weights and attribute values of the alternatives. By adopting a simulation method, means together with standard deviations and correlations of the overall values of alternatives are used to conduct the comparisons. The proposed statistical approach simplifies and enriches Bryson and Mobolurin's approach by providing superiority possibilities between alternatives, means, standard deviations, and correlations for alternative comparisons. The simulation results show that under a uniform distribution, the intervals of the overall values of alternatives coincide with the ‘level 3 composite’ intervals of Bryson and Mobolurin. Comparisons between the alternatives associated with their evaluated intervals are also discussed for the case of normal distribution on the intervals of attribute weights and crisp values for the attribute values of alternatives.     

Fuzzy interpolative reasoning for sparse fuzzy rule-based systems based on the slopes of fuzzy sets

In this paper, we present a new fuzzy interpolative reasoning method for sparse fuzzy rule-based systems based on the slopes of fuzzy sets. The proposed method can deal with fuzzy rules interpolation involving complex polygonal fuzzy sets with the advantages of simplest calculation and get more reasonable fuzzy interpolative reasoning results. We also make some experiments to compare the fuzzy interpolative reasoning results of the proposed method with the ones of the existing methods. The experimental results show that the proposed method outperforms the existing fuzzy interpolative reasoning methods for sparse fuzzy rule-based systems.     

A simulated annealing procedure for single row layout problems in flexible manufacturing systems

In this paper we address a layout problem in flexible manufacturing systems (FMSs). A layout type that has been extensively implemented in FMSs is the single row machine layout. In such a configuration machines are arranged along a straight track with a material handling device moving jobs from one machine to another. The single row layout problem (SRLP) deals with the optimal arrangement of the machines for the above configuration. We propose a simulated annealing (SA) heuristic for the solution of SRLP. Extensive computational results, and ways to improve the performance of the SA algorithm through parameter fine-tuning procedures, are reported.     

Optimal production and inventory decisions under demand and production disruptions

Unanticipated events may take place and disrupt demand and/or production in a supply chain. Conditional on the type, magnitude and duration of disruptions, changes may be called to revise the original production plan. We analyse different disruption scenarios and propose optimal production–inventory models for products facing demand and production disruptions. To lower the cost, we optimise the production run time, purchasing times and order quantity for the manufacturer. Numerical experiments are conducted to examine the influences of disruption time and magnitude on optimal production and purchasing decisions.     

Optimal algorithms for row layout problems in automated manufacturing systems

In many automated manufacturing environments, particularly flowlines and flexible manufacturing systems (FMSs), machines are arranged along a straight material-handling track with a material-handling device moving jobs from one machine to another. These layouts are referred to as row machine layouts. In this paper we study the row layout problem (RLP) under the design objective of minimizing the total backtracking distance of the material-handling device, which is an NP-complete problem. We propose the use of a dynamic programming algorithm for its solution. A special case of the problem, usually encountered in flexible manufacturing cells and which can be solved with a polynomial procedure, is also discussed. For the equidistance case (i.e., successive candidate locations are in equal distances), we formulate the problem as an integer linear program. The use of standard mathematical programming codes can efficiently solve this formulation.     

Whole pH range anti-corrosion property of aluminium alloy coated with MFI zeolite film

ABSTRACT

Strong protection capability of zeolite coating for AA6061 substrate from corrosion in NaCl, H₂SO₄ and NaOH solution has been demonstrated with reduction of corrosion current by five orders of magnitude. Film resistance was identified as the governing parameter in the formation of a barrier shielding the penetration of aggressive species. For the MFI zeolite film growth on the surface of the AA6061 substrate, while the in situ crystallisation (InC) protocol generated loosely packed film made of large zeolite crystal, the dry-gel conversion (DGC) protocol prepared dense film comprising of nanoparticles. Superior protection ability of DGC-grown film is attributed to the increased film resistance associated with a dense and impermeable zeolite layer. As such, the DGC-grown film requiring thinner film thickness around 5?μm showed better anti-corrosion function than the InC-grown film.

This paper is part of a supplementary issue from the 17th Asia-Pacific Corrosion Control Conference (APCCC-17).     

Integrating multi-product production and distribution in newspaper logistics

This paper presents a tabu search metaheuristic to aid in the coordination and synchronization of the production and delivery of multi-product newspapers to bulk delivery locations. The problem is modeled as an open vehicle routing problem with time windows and zoning constraints. The methodology is applied to the newspaper production and distribution problem in a major metropolitan area. Computational results are presented and show significant improvement relative to an existing newspaper company's operations.