Supply planning model for remanufacturing system in reverse logistics environment

This paper discusses the remanufacturing process of reusable parts in reverse logistics, where the manufacturer has two alternatives for supplying parts: either ordering the required parts to external suppliers or overhauling returned products and bringing them back to ‘as new’ conditions. We propose a general framework for this remanufacturing environment and a mathematical model to maximize the total cost savings by optimally deciding the quantity of parts to be processed at each remanufacturing facilities, the number of purchased parts from subcontractor. The model is newly introduced and developed in the reverse logistics literatures. The model is validated through a set of experimental data reflecting practical business situation and sensitivity analyses are conducted on various parameters to gain insight into the proposed model.     

Comments on the erratum to “The spatial and temporal consolidation of returned products in a closed-loop supply chain network” [Comput. Ind. Eng. 51 (2006) 309–320]

A genetic algorithm based mixed-integer; non-linear programming model proposed by Min et al. [Min, H., Ko, C. S., & Ko, H. J. (2006). The spatial and temporal consolidation of returned products in a closed-loop supply chain network. Computers & Industrial Engineering, 51, 309–320] was recently published in Computers & Industrial Engineering journal to solve the reverse logistics problem involving both spatial and temporal consolidation of returned products. In this work, comments and suggestions are given to the recently published model of Min et al. (2006). The comments like centralized return center location, maximum allowable distance between customers and the initial collection point, calculation of transportation cost and finally, the modification of the objective function are suggested in this work.     

Comments on “An effective hybrid optimization approach for multi-objective flexible job-shop scheduling problems” [Comput. Ind. Eng. 48 (2005) 409–425]

An effective hybrid optimization approach proposed by Xia and Wu [Xia, W. J., Wu, Z. M. (2005). An effective hybrid optimization approach for multi-objective flexible job-shop scheduling problems. Computers & Industrial Engineering, 48, 409–425] was recently published in Computers & Industrial Engineering journal to solve the multi-objective flexible job-shop scheduling problems. In this work, comments and suggestions are given to the recently published approach of Xia and Wu (2005). The comments like centralized the problem formulation and experimental comparison. The modification of the problem formulation is suggested in this work.     

Comments on “State estimation for linear systems with state equality constraints” [Automatica 43 (2007) 1363-1368]

The state estimation problem for linear systems with linear state equality constraints was dealt with in Ko & Bitmead [Ko, S., & Bitmead, R. (2007). State estimation for linear systems with state equality constraints. Automatica, 43, 1363-1368]. In this correspondence, it is first shown that a necessary assumption on the covariance of the process noise is missing in the main result of the paper. It is then shown that the main result of the paper can be achieved in a convenient and more general way without any additional assumptions on the covariance of the process noise except positive definiteness.     

Corrigendum to: “On ordering free groups” [J. Symbolic Comput. 40 (2005) 1285–1290]

The proof of the main result of the paper is corrected.