This paper studies a two-echelon supply chain with stochastic and discrete consumer demand, batch order quantities, periodic inventory review, and deterministic transportation times. Reorder point policies manage inventories at every location. Average inventory, backorders and fill rates are evaluated exactly for each location. Safety stock is evaluated exactly at the lower echelon and a good a...

We present a continuous-review inventory model for tactical planning in a multi-item, multi-echelon service parts distribution system with time-based service level requirements. Our goal is to determine base stock levels for all items at all locations so that the service level agreements are met at minimum investment. We present exact time-based fill rate expressions for each item and efficient...

In this paper we study two echelon multi-server tandom queueing systems where customers arrive according to a poisson process with two different rates. The service rates at both echelons are independent of each other. The service times of customers is assumed to be completed in two stages. The service times at each stage are exponentially distributed. At the first stage, the customers may balk ...

Design of a logistics network in proper way provides a proper platform for efficient and effective supply chain management. This paper studies a multi-period, multi echelon and multi-product integrated forward-reverse logistics network under uncertainty. First, an efficient complex mixed-integer linear programming (MILP) model by considering some real-world assumptions is developed for the inte...

HYPOTHESIS The required sample size of a prospective randomized trial comparing standard pancreaticoduodenectomy with pancreaticoduodenectomy plus extended lymphadenectomy for pancreatic adenocarcinoma is prohibitively large, making such a trial infeasible. DESIGN Retrospective cohort study. SETTING Comprehensive cancer center. PATIENTS We identified 158 patients who underwent pancreatico...

Mitigating the bullwhip effect is one of crucial problems in supply chain management. In this research, centralized and decentralized model predictive control strategies are applied to control inventory positions and to reduce the bullwhip effect in a benchmark four-echelon supply chain. The supply chain under consideration is described by discrete dynamic models characterized by balance equati...

BACKGROUND The need for routine axillary lymph node dissection (ALND) in patients with invasive breast cancer and low-volume sentinel node (SN) involvement is questionable. Accurate prediction of second echelon lymph node involvement could identify those patients most likely to benefit from ALND. METHODS A consecutive series of 317 patients with invasive breast cancer and a tumor positive axi...

This work studies a multi-echelon multi-item lot-sizing problem with remanufacturing and lost sales. The is formulated as mixed-integer linear program. A new family of valid inequalities taking advantage the structure introduced used in customized branch-and-cut algorithm. provided numerical results show that proposed algorithm outperforms both generic embedded standard-alone mathematical solve...