The effects of a free-repair warranty on the discrete-time periodic replacement policy

This paper presents the effects of a free-repair warranty on a periodic replacement policy with a discrete time process. Considering a repairable product that should be operational at the time over an indefinitely long operation cycle n (n=1, 2, …), under the discrete-time periodic replacement policy, a product is preventively replaced at pre-specified operation cycles N, 2N, 3N, … (N=1, 2, …). When the product fails, a minimal repair is performed at the time of failure, and the failure rate is not disturbed by each repair. The cost models from the customers' perspectives are developed for both warranted and non-warranted products. The corresponding optimal replacement period N? is derived such that the long-run expected cost rate is minimized. Under the assumption of the discrete time increasing failure rate, the existence and uniqueness of the optimal replacement period are shown, and the impact of a free-repair warranty on the optimal periodic replacement policies is investigated analytically. The optimal N* for a warranted product should be adjusted toward the end of the warranty period. Finally, numerical examples are demonstrated for the optimal policy illustration and verification. The observations from the numerical results provide valuable information for a buyer (user) to adjust the optimal periodic replacement policy if a product is operating in discrete time under a free-repair warranty.     

Integrating noncyclical preventive maintenance scheduling and production planning for a single machine

This paper deals with the problem of integrating noncyclical preventive maintenance and tactical production planning for a single machine. We are given a set of products that must be produced in lots during a specified finite planning horizon. The maintenance policy suggests possible preventive replacements at the beginning of each production planning period, and minimal repair at machine failure. The proposed model determines simultaneously the optimal production plan and the instants of preventive maintenance actions. The objective is to minimize the sum of preventive and corrective maintenance costs, setup costs, holding costs, backorder costs and production costs, while satisfying the demand for all products over the entire horizon. The problem is solved by comparing the results of several multi-product capacitated lot-sizing problems. The value of the integration and that of using noncyclical preventive maintenance when the demand varies from one period to another are illustrated through a numerical example and validated by a design of experiment. The later has shown that the integration of maintenance and production planning can reduce the total maintenance and production cost and the removal of periodicity constraint is directly affected by the demand fluctuation and can also reduce the total maintenance and production cost.     

INCOM a general system for medium and long-range forecasting

Modern industrial stratege demands accurate and dynamic medium and long-range planning. It is expected to have a strong influence on the profitability of investments, the optimum management of manufacturing and stocks, good marketing strategy and, of course, a sound financial management.     

Links among innovation,food system transformation,and technology adoption,with implications for food policy: Overview of a special issue

This overview paper introduces the special issue focused on links among innovation, food system transformation, and technology adoption in all segments of agrifood value chains from inputs to farming to post-harvest segments including logistics, wholesale, processing, and retail. We identify the issues and the gaps in the literature, and then note key points and contributions of the papers in the special issue. We then highlight food policy implications.