Mohamed Ben-Daya

The joint economic lot sizing problem: Review and extensions

With the growing focus on supply chain management, firms realize that inventories across the entire supply chain can be more efficiently managed through greater cooperation and better coordination. This paper presents a comprehensive and up-to-date review of the joint economic lot sizing problem (JELP) and also provides some extensions of this important problem. In particular, a detailed mathematical description of, and a unified framework for, the main JELP models are given. Additionally, a comparative empirical study of the main policies proposed for JELP is conducted. The focus of this study is on assessing the deviation of these policies from the optimal solution. Studying the performance of different models provides additional insights that will help in justifying their use in more complex supply chain models that involve more stages or other practical considerations of interest.

Some stochastic inventory models with deterministic variable lead time

In this paper we determine optimal reduction in the procurement lead time duration for some stochastic inventory models, jointly with the optimal ordering decisions. The models are developed with complete and partial information about the lead time demand distribution. The stochastic models analyzed in this paper are the classical continuous and periodic review models with a mixture of backorders and lost sales and the base stock model. For each of these models, we provide sufficient conditions for the uniqueness of the optimal operating policy. We also develop algorithms for solving these models and provide illustrative numerical examples.

Maintenance and quality: the missing link

Focuses on the relationship between maintenance and quality. Then briefly reviews models relating production and quality on the one hand, and production and maintenance on the other. Using concepts from predictive maintenance and the measure of equipment effectiveness from total productive maintenance (TPM), identifies explicit links between maintenance and quality. Emphasizes the need to develop adequate models relating maintenance and quality. Presents two approaches for modelling the link between maintenance and quality. The first approach is based on the concept of imperfect maintenance and the second one uses the Taguchi approach to quality and maintenance.

A tabu search approach for the flow shop scheduling problem

In this paper, we propose a tabu search approach for solving the permutation flow shop scheduling problem. The proposed implementation of the tabu search approach suggests simple techniques for generating neighborhoods of a given sequence and a combined scheme for intensification and diversification that has not been considered before. These new features result in an implementation that improves upon previous tabu search implementations that use mechanisms of comparable simplicity. Also, better results were obtained than those produced by a simulated annealing algorithm from the literature.

The economic production lot-sizing problem with imperfect production processes and imperfect maintenance

Abstract This paper deals with an integrated model for the joint determination of economic production quantity and preventive maintenance (PM) level for an imperfect process having a general deterioration distribution with increasing hazard rate. The effect of PM activities on the deterioration pattern of the process is modeled using the imperfect maintenance concept. It is assumed that, after each PM, the age of the system is reduced proportional to the PM level. A numerical example is used to illustrate the effect of PM level on the cost of nonconforming items and restoration cost due to shift to the out-of-control state. It is found that performing PM will yield reductions in quality related costs. It is more economical to perform PM when the extra PM cost is compensated for by the reduction in quality related costs.

A revised failure mode and effects analysis model

Proposes an improvement of the RPN model used in the failure mode and effects analysis. The aim of the proposed model is to make RPN a better measurement tool. Suggests combining the improved RPN model with an expected cost model in quality improvement efforts.

Production and shipment lot sizing in a vendor–buyer supply chain with transportation cost

Abstract Previous research on the joint vendor–buyer problem focused on the production shipment schedule in terms of the number and size of batches transferred between the two parties. It is a fact that transportation cost is a major part of the total operational cost. However, in most joint vendor–buyer models, the transportation cost is only considered implicitly as a part of fixed setup or ordering cost and thus is assumed to be independent of the size of the shipment. As such, the effect of the transportation cost is not adequately reflected in final planning decisions. There is a need for models involving transportation cost explicitly for better decision-making. In this study we analyze the vendor–buyer lot-sizing problem under equal-size shipment policy. We introduce the complete solution of the problem in an explicit and extended manner that has not existed in the literature. We incorporate transportation cost explicitly into the model and develop optimal solution procedures for solving the integrated models. All-unit-discount transportation cost structures with and without over declaration have been considered. Numerical examples are presented for illustrative purpose.

Handbook of maintenance management and engineering

Maintenance Organization.- Maintenance Productivity and Performance Management.- Failure Statistics.- Failure Mode and Effect Analysis.- Maintenance Control.- Guidelines for Budgeting and Costing Planned Maintenance Services.- Simulation Based Approaches for Maintenance Strategies Optimization.- Maintenance Forecasting and Capacity Planning.- Integrated Spare Parts Management.- Turnaround Maintenance.- Maintenance Planning and Scheduling.- Models for Production and Maintenance Planning in Stochastic Manufacturing Systems.- Inspection Strategies for Randomly Failing Systems.- System Health Monitoring and Prognostics - A Review of Current Paradigms and Practices.- Applied Maintenance Models.- Reliability Centered Maintenance.- Total Productive Maintenance.- Warranty and Maintenance.- Delay Time Modeling for Optimized Inspection Intervals of Production Plant.- Integrated e-maintenance and Intelligent Maintenance Systems.- Maintainability & System Effectiveness.- Safety and Maintenance.- Maintenance Quality and Environmental Performance Improvement: An Integrated Approach.- Industrial Asset Maintenance and Sustainability Performance: Economic, Environmental, and Societal Implications.- Human Reliability and Error in Maintenance.- Human Error in Maintenance - A Design Perspective.

Effect of maintenance on the economic design of x̄-control chart

Abstract An integrated model for the joint optimization of the maintenance level and the economic design of x-control chart is presented. This is done for a deteriorating process where the in-control period follows a general probability distribution with an increasing hazard rate. In the proposed model, preventive maintenance reduces the shift rate to an out-of-control state by an amount proportional to the preventive maintenance level. An example of a Weibull shock model with increasing hazard rate is used to illustrate the effect of the maintenance level on quality control costs. A comparison between uniform and non-uniform schemes is made both with and without preventive maintenance. Effect of distribution parameters has also been investigated.

A generic conceptual simulation model for maintenance systems

Maintenance is a complex process that is triggered by equipment failure or planned repair. This process requires planning, scheduling, control and the deployment of maintenance resources to perform necessary maintenance activities. In this paper a generic conceptual model for maintenance systems has been developed. The conceptual model consists of seven modules. The first one is the input module in which the characteristic of the maintenance system is specified. The second module is concerned with modeling the maintenance load. The third module is the planning and scheduling. This module is the most critical, since it controls the maintenance process. The fourth module is the material and spare parts supply, followed by the equipment availability module. The sixth module is the quality control module and the performance measures are the seventh module. The specification of such a conceptual model lays the ground for developing a realistic simulation model.