A fast-response production-inventory model for deteriorating seasonal products with learning in set-ups
, Volume 2, Number 4, pp. 715-736
Ibraheem Abdul and Atsuo Murata PDF (368 K)
Abstract: The classical production-inventory model assumes that both demand and set-up costs are constant. However, in real manufacturing environment, managers usually embark on continuous improvement programmes that often lead to more effective use of tools and machineries and consequently reduction in set-up costs. In fact, constant emphasis on reduction of set-up costs is usually cited as one of the factors responsible for the efficiency of Japanese manufacturing methods. On the other hand, the demand for seasonal product is often characterized by a mixture of time-dependent patterns over the entire season. This paper investigates the effect of learning-based reduction in set-up costs on the optimal schedules and costs of a production-inventory system for deteriorating seasonal products. The demand pattern is a general three-phase ramp-type demand function that represents the various phases of demand commonly observed in many seasonal products in the market. A two-parameter Weibull-distribution function is used for the deterioration of items in order to make the model more generalized and realistic. The study further presents two different multi-period production strategies that can ensure a fast-response to customers’ demand and compare them with the usual single period strategy. The Numerical example and sensitivity analysis shows that learning-based reduction in set-up costs leads to higher production frequency and shorter production runs which are vital aspects of the just-in-time (JIT) philosophy.
Keywords: Production, Learning, Set-up reduction, Seasonal products, Deterioration, Varying demand pattern
A new improved genetic algorithm approach and a competitive heuristic method for large-scale multiple resource-constrained project-scheduling problems
, Volume 2, Number 4, pp. 737-748
Mostafa Khanzadi, Rambod Soufipour and Mohammad Rostami PDF (189 K)
Abstract: The aim of this paper is to present a new genetic algorithm approach for large scale multiple resource-constrained project-scheduling problems (RCPSP). It also presents a heuristic approach to achieve proper solutions for large scale problems. This research area is very common in industry especially when a set of activities needs to be finished as soon as possible subject to two sets of constraints, precedence constraints and resource constraints. The emphasis in this research is on investigating the complexity of scheduling problems and developing a new GA approach to solve this problem in such a way that the advantages of GA are appropriately utilized by applying a novel method to reduce the complexity of the problem. Computational results are also reported for the most famous classical problems taken from the operational research literature.
Keywords: RCPSP problem, Resource-constrained, Metaheuristics, Genetic Algorithm
An improved sheep flock heredity algorithm for job shop scheduling and flow shop scheduling problems
, Volume 2, Number 4, 749-764
Chandramouli Anandaraman PDF (232 K)
Abstract: Job Shop Scheduling Problem (JSSP) and Flow Shop Scheduling Problem (FSSP) are strong NP-complete combinatorial optimization problems among class of typical production scheduling problems. An improved Sheep Flock Heredity Algorithm (ISFHA) is proposed in this paper to find a schedule of operations that can minimize makespan. In ISFHA, the pairwise mutation operation is replaced by a single point mutation process with a probabilistic property which guarantees the feasibility of the solutions in the local search domain. A Robust-Replace (R-R) heuristic is introduced in place of chromosomal crossover to enhance the global search and to improve the convergence. The R-R heuristic is found to enhance the exploring potential of the algorithm and enrich the diversity of neighborhoods. Experimental results reveal the effectiveness of the proposed algorithm, whose optimization performance is markedly superior to that of genetic algorithms and is comparable to the best results reported in the literature.
Keywords: Job shop scheduling, Flow shop scheduling, Sheep flock heredity algorithm Makespan
The Karush–Kuhn–Tucker optimality conditions in minimum weight design of elastic rotating disks with variable thickness and density
, Volume 2, Number 4, 765-774
Sanaz Jafari PDF (235 K)
Abstract: Rotating discs work mostly at high angular velocity. High speed results in large centrifugal forces in discs and induces large stresses and deformations. Minimizing weight of such disks yields various benefits such as low dead weights and lower costs. In order to attain a certain and reliable analysis, disk with variable thickness and density is considered. Semi-analytical solutions for the elastic stress distribution in rotating annular disks with uniform and variable thicknesses and densities are obtained under plane stress assumption by authors in previous works. The optimum disk profile for minimum weight design is achieved by the Karush–Kuhn–Tucker (KKT) optimality conditions. Inequality constrain equation is used in optimization to make sure that maximum von Mises stress is always less than yielding strength of the material of the disk.
Keywords: Rotating annular disk, Variable thickness, Variable density, Optimization, Karush-Kuhn-Tucker method
An integrated TSP-GA with EOL cost model for selecting the best EOL option
, Volume 2, Number 4, 775-792
Zakri Ghazalli and Atsuo Murata PDF (698 K)
Abstract: This paper presents our research works on integrating design for disassembly with cost model for end-of-life (EOL) product. This paper has two objectives. The first objective is to optimize disassembly sequence of the EOL product. We integrate a traveling salesman problem approach with genetic algorithm in finding the optimal disassembly sequence for disassembling the EOL product. Based on this optimal sequence, the second objective is to identify the best EOL option. We employ EOL profits and net present value of parts and subassemblies of the EOL product to determine the best EOL option of components and parts of the EOL product. The predicted results showed that the developed cost model has reached a good correspondence with the established methods.
Keywords: Disassembly sequence planning, Traveling salesman problem, Genetic algorithm Environmental cost, Economical cost, End-of-life profit, Net present value
The center location problem with equal weights in the presence of a probabilistic line barrier
, Volume 2, Number 4, 793-800
M. Amiri-Aref, N. Javadian, R. Tavakkoli-Moghaddam and M.B. Aryanezhad PDF (238 K)
Abstract: In this paper, a single facility centre location problem with a line barrier, which is uniformly distributed on a given horizontal route in the plane is proposed. The rectilinear distance metric is considered. The objective function minimizes the maximum expected barrier distance from the new facility to all demand points in the plane. An algorithm to solve the desired problem is proposed where a mixed integer nonlinear programming needs to be solved. The proposed model of this paper is solved using some already existed benchmark problem in the literature and the results are compared with other available methods.
Keywords: Planar center location problem, Probabilistic line barrier, Rectilinear distance
A review of multi-criteria decision making techniques for supplier evaluation and selection
, Volume 2, Number 4, 801-810
Prince Agarwal, Manjari Sahai, Vaibhav Mishra, Monark Bag and Vrijendra Singh PDF (117 K)
Abstract: Supplier evaluation and selection has been a vital issue of strategic importance for long time. Different multi-criteria decision making (MCDM) approaches have been proposed by the researchers in past, to solve the supplier evaluation and selection problem. In this paper, we present a review of various MCDM methodologies reported in the literature for solving the supplier evaluation and selection process. The review is solely based on sixty-eight research articles, including eight review articles in the academic literature from 2000 to 2011. We try to find out the most prevalent approach in the articles and thereby present the future scope of arriving at an optimal solution to the problem, based on the specifications, the strategies and the requirements of the buyers. The study presents that with the change in processes and the requirements, how the approach of the manufacturing industry has shifted from striving for operational effectiveness to the strategic partnership in the dyadic relationship.
Keywords: Supplier selection, Supplier evaluation, MCDM, Supply chain management
Coordinating a two-echelon supply chain under inflation and time value of money
, Volume 2, Number 4, 811-818
B.C. Giri and S. Bardhan PDF (147 K)
Abstract: In the current global economic scenario, inflation plays a vital role in deciding optimal pricing of goods in any business entity. This paper develops a two-echelon (manufacturer-buyer) supply chain model taking into account inflation and time value of money. The present value of the total cost of the supply chain is derived when the manufacturer produces a number of lots, the sum of which is equal to the buyer’s total demand over a time horizon and the manufacturer’s each production lot is delivered to the buyer in n shipments. The optimal solution of the model is obtained for a numerical example after some adjustments (required to exhibit feasibility) in the derived solution. Sensitivity analysis is also carried out in order to examine the effects of changes in model-parameters on the optimal solution.
Keywords: Supply chain, Inflation, Time value of money
Surface roughness model and parametric optimization in finish turning using coated carbide insert: Response surface methodology and Taguchi approach
, Volume 2, Number 4, pp. 819-830
Ashok kumar Sahoo and Bidyadhar Sahoo PDF (180 K)
Abstract: This paper presents the experimental study, development of mathematical model and parametric optimization for surface roughness in turning D2 steel using TiN coated carbide insert using Taguchi parameter design and response surface methodology. The experimental plan and analysis was based on the Taguchi L27 orthogonal array taking cutting speed (v), feed (f) and depth of cut (d) as important cutting parameters. The influence of the machining parameters on the surface finish has also been investigated and the optimum cutting condition for minimizing the surface roughness is evaluated. The optimal parametric combination for TiN coated cutting insert is found to be v3-f1-d3. The ANOVA result shows that feed the most significant process parameter on surface roughness followed by depth of cut. The cutting speed is found to be insignificant from the study. The RSM model shows good accuracy between predicted values and experimental values with 95% confidence intervals and adequate. It is concluded that the developed RSM model can be effectively utilized to predict the surface roughness in turning D2 steel.
Keywords: Taguchi, Surface roughness, Response surface method optimization, Coated carbide
A comparative study on the ranking performance of some multi-criteria decision-making methods for industrial robot selection
, Volume 2, Number 4, 831-850
Vijay Manikrao Athawale and Shankar Chakraborty PDF (233 K)
Abstract: Industrial robots are mainly employed to perform repetitive and hazardous production jobs, multi-shift operations etc. to reduce the delivery time, improve the work environment, lower the production cost and even increase the product range to fulfill the customers’ needs. When a choice is to be made from among several alternative robots for a given industrial application, it is necessary to compare their performance characteristics in a decisive way. As the industrial robot selection problem involves multiple conflicting criteria and a finite set of candidate alternatives, different multi-criteria decision-making (MCDM) methods can be effectively used to solve such type of problem. In this paper, ten most popular MCDM methods are considered and their relative performance are compared with respect to the rankings of the alternative robots as engaged in some industrial pick-n-place operation. It is observed that all these methods give almost the same rankings of the alternative robots, although the performance of WPM, TOPSIS and GRA methods are slightly better than the others. It can be concluded that for a given industrial robot selection problem, more attention is to be paid on the proper selection of the relevant criteria and alternatives, not on choosing the most appropriate MCDM method to be employed.
Keywords: Robot selection, MCDM method, Ranking performance, Spearman’s rank correlation coefficient, Kendall’s coefficient of concordance
A robust moving average iterative weighting method to analyze the effect of outliers on the response surface design
, Volume 2, Number 4,pp. 851-862
Mehdi Bashiri and Amir Moslemi PDF (253 K)
Abstract: The paper discusses about the effect of outliers and trends on the response surface design fitted to the experiments results. The common way to analyze the response surface is to fit the polynomial regression to the response variable by ordinary least square method and to find the significant controllable variables by ANOVA. In this case, the outliers can have confusing effect on the regression model, which derives the experiment results and lead to wrong interpretation of the data. The proposed moving average iterative method (MAIW) of this paper is a robust approach to decrease the effect of these faulty points by considering the previous data to detect the outliers or detect the probable trends in residuals. The iterative weighting method is used to estimate the coefficients of the regression model and a numerical example illustrates the proposed approach.
Keywords: Response surface design, Ordinary least square, Outliers, Moving average method
Multi-objective assembly line balancing using genetic algorithm
, Volume 2, Number 4, 863-872
Samad Ayazi, Abdol Naser Hajizadeh, Mostafa Emrani Nooshabadi, Hamid reza Jalaie and Yaghoob Mohammad moradi PDF (118 K)
Abstract: One of the primary issues in line balancing problems is the uncertainty associated with the processing times. There are different reasons for having uncertain processing times such as task deterioration, failure in machines, etc. On the other hand, there are different objectives, such as cycle time, number of workstations in an assembly line balancing. In this paper, we present a multi-objective decision making assembly line balancing which minimizes different objectives such as cycle time and number of workstations. The resulted problem is formulated based on Lp-norm mixed integer programming and a meta-heuristic approach is also presented to solve the resulted model. The problem formulation is solved for some test examples and the results are discussed under different conditions.
Keywords: Assembly line balancing, Genetic Operators, Multi-objective, Genetic algorithm
A proposition of a manufactronic network approach for intelligent and flexible manufacturing systems
, Volume 2, Number 4, 873-890
Fernando Almeida , Paulo Dias, Gil Gonçalves, Michael Peschl and Michael Hoffmeister PDF (3400 K)
Abstract: The XPRESS project introduces a completely new scalable concept of a manufactronic networked factory, which is composed by a co-ordinated team of specialized autonomous objects (Manufactrons), each knowing how to do a certain process optimally. This knowledge based concept integrated the complete chain: production configuration (decrease of ramp-up time of at least 50%), multi-variant production line (varying types and volumes on a single line) and 100% quality monitoring. The manufactronic networked architecture allows continuous process improvement, and will be able to anticipate and to respond to rapidly changing consumer needs, producing high-quality products in adequate quantities while reducing costs. This concept is demonstrated in the automotive, aeronautics and electrical industry but can be transferred to nearly all production processes.
Keywords: Intelligent manufacturing, Production unit, Quality systems, Workflow models
Retailer’s optimal ordering policies with cash discount and progressive payment scheme derived algebraically
, Volume 2, Number 4, 891-900
Alok kumar, K K Kaanodiya, and R R Pachauri PDF (150 K)
Abstract: This study presents optimal ordering policies for retailer when supplier offers cash discount and two progressive payment schemes for paying of purchasing cost. If the retailer pays the outstanding amount before or at first trade credit period M, the supplier provides r_1cash discount and does not charge any interest. If the retailer pays after M but before or at the second trade period N offered by the supplier, the supplier provides r_2 cash discount and charges interest on unpaid balance at the rate 〖Ic〗_1 . If retailer pays the balance after N, (N>M) then the supplier does not provide any cash discount but charges interest on unpaid balance at the rate 〖Ic〗_2. The primary objective of this paper is to minimize the total cost of inventory system. This paper develops an algebraic approach to determine the optimal cycle time, optimal order quantity and optimal relevant cost. Numerical example are also presented to illustrate the result of propose model and solution procedure developed.
Keywords: EOQ, Permissible delay in payments, Trade credit, Cash discount, Algebraic approach
(Q, R) inventory model with service level constraint and variable lead time in fuzzy-stochastic environment
, Volume 2, Number 4, 901-912
Hardik Soni PDF (252 K)
Abstract: In today's global marketplace, individual firms do not compete as independent entities rather as an integral part of a supply chain. Uncertainty is the main attribute in managing the supply chains. Accordingly, we develop a (Q, R) inventory model with service level constraint and variable lead-time in fuzzy-stochastic environment. In addition, the triangular fuzzy numbers counts upon lead-time are used to construct fuzzy-stochastic lead-time demand. Using credibility criterion, the expected shortages are calculated. Without loss of generality, we assume that all the observed values of the fuzzy random variable, representing the demand are triangular fuzzy numbers. Consequently, the value of total expected cost in the fuzzy sense is derived using the expected value criterion or credibility criterion. To determine an optimal policy, a numerical technique is presented and the results are analyzed using scan and zoom for constraint optimization. Finally, in order to demonstrate the accuracy and effectiveness of the proposed model, numerical example and sensitivity analysis are also included.
Keywords: Inventory control, Fuzzy random variable, Expected value, Variance
Integration of part selection, machine loading and machining optimisation decisions for balanced workload in flexible manufacturing system
, Volume 2, Number 4, 913-930
Mussa I. Mgwatu PDF (313 K)
Abstract: This paper demonstrates the importance of incorporating and solving the machining optimisation problem jointly with part selection and machine loading problems in order to avoid unbalanced workload in the FMS. Unbalanced workload renders to ineffective FMS such that some machines on the manufacturing shop floor become more occupied than others. Since CNC machine tools employed in the FMS are rather expensive, it is mostly important to balance the workload so that all machines can be effectively utilised. Therefore, in this study, two mathematical models are presented and solved in efforts to balance the workload and improve the performance of the FMS. A two-stage sequential approach is adopted whereby the first stage deals with the maximum throughput objective while the second stage deals with the minimum production cost objective. The results show that when part selection, machine loading and machining optimisation problems are jointly solved, more practical decisions can be made and a wide range of balanced workload in the FMS can be realised with minimum production cost objective. The results also show that the available machine time and tooling budget have enormous effects on throughput and production cost.
Keywords: Part selection, Machine loading, Machining optimisation, Flexible manufacturing systems
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