We present a partially observed Markov decision process model of a single product supply chain system with lost sales, in which a single decision maker selects a replenishment quantity at each decision epoch. Demand is modeled using an exogenous Markov chain, such that the distribution of demand in a period is dependent on the demand level in the prior period. The objective is to maximize expec...

We consider a perishable inventory system that operates under stochastic demand, constant lifetime and a constant lead time. The system employs a continuous review ðr;Q Þ inventory control policy where unfilled demands are lost. We investigate the properties of the cost function and present an approximation procedure to find the parameters r and Q that minimize the total cost. We then conduct a...

Competitiveness is an important means of determining whether a company will prosper. Business organizations compete with one another in a variety of ways. Among these competitive methods are time and cost factors. The purpose of this paper is to examine the inventory models presented by Padmanabhan and Vrat [International Journal of Systems Sciences 21 (1990) 1721] with a mixture of back orders...

We consider Bayesian updating of demand in a lost sales newsvendor model with censored observations. In a lost sales environment, where the arrival process is not recorded, the exact demand is not observed if it exceeds the beginning stock level, resulting in censored observations. Adopting a Bayesian approach for updating the demand distribution, we develop expressions for the exact posteriors...

We consider a system that faces stochastic demand, reviews the system periodically and places replenishment orders to raise the inventory position to exactly S at the beginning of every period. The lead time associated with each of these orders is random. However the lead time process is such that these orders are ful lled in a rst-in rst-out sequence. Demand that can not be met with inventory ...

In this paper, we consider a version of the newsvendor problem in which the demand for newspapers is unknown and the lost sales are unobservable. This problem serves as a surrogate for more complex supply chain problems in which learning plays a role. We propose the knowledge gradient (KG) policy, which considers how much is learned about the demand distribution from each order. This policy com...

In this paper we consider a single-item inventory systemwith lost sales and fixed order cost. We numerically illustrate the lack of a clear structure in optimal replenishment policies for such systems. However, policies with a simple structure are preferred in practical settings. Examples of replenishment policies with a simple parametric description are the (s, S) policy and the (s,nQ) policy....

We discuss plausible locations of radiating regions in the magnetospheres of pulsars and argue that the mechanisms of pulsar radiation at different frequencies are closely connected with the locations of the radiating regions, especially in the radio range. If the region that is responsible for the bulk of the non-thermal radiation at some frequency is localized in the pulsar magnetosphere then...

Traditional inventory models focus on operational decisions. In this research, we propose a general framework for incorporating financial states of an organization in multi-period inventory models with lost sales. This approach differs from the traditional ones in that operational decisions are correlated with and constrained by financial flows of the firm. We study the borrowing and and lendin...

Lost sales, increased costs and poor customer service due to inaccurate forecasts, out-of-stocks, overstocks, unsuccessful promotions, markdowns and out-of-season items play havoc with a company’s bottom line. Not too many companies can remain profitable by writing off hundreds of thousands of dollars worth of merchandise on an annual basis or sitting idly by as their customer bases erode due t...