Statistical control implies stable random variation about a target value that is produced by some common cause. In many manufacturing systems, the majority of the processing time is spent in the steady-state phase. Hence, it makes sense that a system is in statistical control most of the time and the operator or decision-maker should avoid introducing unnecessary variation by making adjustments...

EPQ model; Replenishment lot size; Multiple deliveries; Random defective items; Production; Rework; Scrap items. Abstract This paper derives the optimal replenishment lot size and shipment policy for an Economic Production Quantity (EPQ) model with multiple deliveries and rework of random defective items. The classic EPQmodel assumes a continuous inventory issuing policy for satisfying demand a...

This paper develops an economic order quantity (EOQ) model with uncertain data. For modelling the uncertainty in real-world data, the exponents and coefficients in demand and cost functions are considered as interval data and then, the related model is designed. The proposed model maximises the profit and determines the price, marketing cost and lot sizing with the interval data. Since the mode...

Abstract: The development plan of a hydrocarbon field includes the design of all the production/injection wells forecasted for the scenario considered. The pressure depletion occurring during the hydrocarbon reservoir exploitation induces rock compaction in the near wellbore area, which may result in mechanical actions transmitted to the well completions, that alter the stress regime in some of...

The main purpose of this study is measuring and comparing of peanut harvesting loss in manual and mechanical methods in addition to economic analysis of them. Hence, a field was selected in Astaneh-Ashrafiyeh and divided to three different plots. Two plots were applied to measure mechanical harvesting loss and third one was applied for manual harvesting loss. According to test results, the lowe...

AIMS To assess the relation between a country's economic developmental status and its prevalence of blindness. METHODS Available epidemiological data on worldwide visual loss and its causes compiled by the World Health Organization were reviewed. Findings were compared with economic development data from the involved countries and regions. Analysis was completed in view of the socioeconomic s...

We study episodes where economic growth decelerates to negative rates. While the majority of these episodes are of short duration, a substantial fraction last for a longer period of time than can be explained as the result of business-cycle dynamics. The duration, depth and associated output loss of these episodes differs dramatically across regions. We investigate the factors associated with t...

In this paper, we extend Porteus (1986) to generalize the economic production quantity (EPQ) model with finite production rate and to derive an exact expression for the expected total annual cost function when maintenance actions and capital investment in setup cost reduction are adopted. In addition, the uniqueness property of the optimal lot size and the bounds of optimal lot size are derived...

We consider jointly replenishing multiple firms that operate under an EOQ like environment in a decentralized, non-cooperative setting. Each firm’s demand rate and inventory holding cost rate are private information. We are interested in finding a mechanism that would determine the joint replenishment frequency and allocate the joint ordering costs to these firms based on their reported stand-a...

Gold mining has rapidly increased in western Amazonia, but the rates and ecological impacts of mining remain poorly known and potentially underestimated. We combined field surveys, airborne mapping, and high-resolution satellite imaging to assess road- and river-based gold mining in the Madre de Dios region of the Peruvian Amazon from 1999 to 2012. In this period, the geographic extent of gold ...