Ke Ding

Bio: Ke Ding is an academic researcher. The author has contributed to research in topics: Frequency-hopping spread spectrum & Tabu search. The author has an hindex of 2, co-authored 2 publications receiving 116 citations.

A Tabu-Search Heuristic for the Capacitated Lot-Sizing Problem with Set-up Carryover

Abstract: This paper presents a tabu-search heuristic for the capacitated lot-sizing problem (CLSP) with set-up carryover. This production-planning problems allows multiple items to be produced within a time period, and setups for items to be carried over from one period to the next. Two interrelated decisions, sequencing and lot sizing, are present in this problem. Our tabu-search heuristic consists of five basic move types--three for the sequencing decisions and two for the lot-sizing decisions. We allow infeasible solutions to be generated at a penalty during the course of the search. We use several search strategies, such as dynamic tabu list, adaptive memory, and self-adjusting penalties, to strengthen our heuristic. We also propose a lower-bounding procedure to estimate the quality of our heuristic solution. We have also modified our heuristic to produce good solutions for the CLSP without set-up carryover. The computational study, conducted on a set of 540 test problems, indicates that on average our heuristic solutions are within 12% of a bound on optimality. In addition, for the set of test problems our results indicate an 8% reduction in total cost through set-up carryover.

Optimizing Frequency Hopping in GSM Cellular Phone Networks

Abstract: The mobile telephony market has been undergoing a dramatic increase in the volume of demand as well as in the quality requirements. The limiting resource in this highly competitive market is the available frequency spectrum. In GSM networks, frequency reuse has been the basic tool for optimizing the spectrum management. This method is sometimes insufficient, however, for the most congested networks. Frequency Hopping (FH) is a method that allows one to expand the available capacity of mobile networks or to improve the quality of service through interference averaging and frequency diversity. Current implementations of FH are based on Random or Cyclic Hopping patterns. In this paper, we propose to optimize FH. We describe a simple heuristic algorithm for allocating frequencies to cells and scheduling the frequency hopping for each mobile. The performance of the proposed approach in a synchronized network is compared to Random and Cyclic FH and to the optimized static frequency reuse implementations. We show that hopping algorithms that use some form of controlled optimization beyond random and cyclic hopping could significantly improve the quality of service and achieve interference averaging, should the telecommunications equipment manufacturers decide to implement such a feature or to allow the operators to control frequency hopping by using their own algorithms.

Modeling Industrial Lot Sizing Problems: A Review

Abstract: In this paper we give an overview of recent developments in the field of modeling deterministic single-level dynamic lot sizing problems. The focus of this paper is on the modeling of various industrial extensions and not on the solution approaches. The timeliness of such a review stems from the growing industry need to solve more realistic and comprehensive production planning problems. First, several different basic lot sizing problems are defined. Many extensions of these problems have been proposed and the research basically expands in two opposite directions. The first line of research focuses on modeling the operational aspects in more detail. The discussion is organized around five aspects: the set ups, the characteristics of the production process, the inventory, demand side and rolling horizon. The second direction is towards more tactical and strategic models in which the lot sizing problem is a core substructure, such as integrated production-distribution planning or supplier selection. Recent advances in both directions are discussed. Finally, we give some concluding remarks and point out interesting areas for future research.

Dynamic capacitated lot-sizing problems: a classification and review of solution approaches

Abstract: This paper presents a review of four decades of research on dynamic lot-sizing with capacity constraints. We discuss both different modeling approaches to the optimization problems and different algorithmic solution approaches. The focus is on research that separates the lot-sizing problem from the detailed sequencing and scheduling problem. Our conceptional point of reference is the multi-level capacitated lot-sizing problem (MLCLSP). We show how different streams of research emerged over time. One result is that many practically important problems are still far from being solved in the sense that they could routinely be solved close to optimality in industrial practice. Our review also shows that currently mathematical programing and the use of metaheuristics are particularly popular among researchers in a vivid and flourishing field of research.