this paper proposes a new mixed integer programming model for multi-item capacitated lot-sizing problem with setup times, safety stock and demand shortages in closed-loop supply chains. the returned products from customers can either be disposed or be remanufactured to be sold as new ones again. due to the complexity of problem, three meta-heuristics algorithms named simulated annealing (sa) al...

We examine the placement of safety stocks in a supply chain for which we have an evolving demand forecast. Under assumptions about the forecasts, the demand process, and the supply chain structure, we show that safety stock placement for such systems is effectively equivalent to the corresponding well-studied problem for systems with stationary demand bounds and base stock policies. Hence, we c...

We consider a manufacturer’s stochastic production/inventory problem under periodic review and present concepts for safety stock determination to cope with uncertainties that are caused by stochastic demand and different types of yield randomness. Order releases follow a linear control rule. Taking manufacturing lead times into account it turns out that safety stocks have to be considered that ...

This paper is aimed at filling the gap between theory and practice in the area of safety stocks under MRP environments. It is focused on providing a new methodology for dimensioning an overall buffer against uncertainty in market demand, which often plagues SMEs – that act as sub-contractors or suppliers within large projects or they have a reduced bargaining power – and adversely affects their...

Exponential smoothing is often used to forecast lead-time demand for inventory control. In this paper, formulae are provided for calculating means and variances of lead-time demand for a wide variety of exponential smoothing methods. A feature of many of the formulae is that variances, as well as the means, depend on trends and seasonal effects. Thus, these formulae provide the opportunity to i...

To determine the safety stock required to achieve a desired service level, demands are commonly assumed to follow a normal probability distribution. However, since demands are necessarily truncated at values below zero, this paper will show that this approach underestimates the actual demand level and results in achieved service levels that are less than those targeted. Use of a left-truncated ...

The impact of commercial airplane crashes on the shareholder wealth US-listed airline stocks has been focus many prior studies, but none have explored concomitant trading volume. We expand scope studies to include near crashes. examine 262 ‘incidents’ from 1962 2018 (220 with return evidence) and document a significant (negative) for fatalities casualties, an insignificant incidents no casualti...