INTRODUCTION Stress is an important factor in the educational process. Teaching and learning are stressful processes. This stress can affect one's ability and change his/her performance. The purpose of this study was to investigate stressors of clinical education from the perspective of medical students in Yazd University of Medical Sciences. METHODS This descriptive-analytic study was conduc...

BACKGROUND To assess the quality of supplementary immunization activities (SIAs), the Global Polio Eradication Initiative (GPEI) has used cluster lot quality assurance sampling (C-LQAS) methods since 2009. However, since the inception of C-LQAS, questions have been raised about the optimal balance between operational feasibility and precision of classification of lots to identify areas with low...

The multi-product dynamic lot sizing problem with product returns and recovery is an important problem that appears in reverse logistics and is known to be NP-hard. In this paper we propose an efficient variable neighborhood descent heuristic algorithm for solving this problem. Furthermore, we present a new benchmark set with the largest instances in the literature. The computational results, d...

We consider a capacitated production-inventory problem in both discreteand continuous-time, stationary settings. In the discretetime setting we analyze the infinite horizon capacitated dynamic lot-sizing problem, find the optimal solution and characterize its properties. For the continuous-time setting we formulate a new problem, which we claim to be an appropriate counterpart of the above disc...

In this paper, we consider a class of single-item dynamic lot-sizing problem with quantity discount cost structure. We present an optimal polynomial algorithm for the case of multibreakpoint Ni, i = 1,2, . . . ,m. The complexity of our algorithm is O(n3 + mn2), where n is the number of periods in finite planning horizon.

The multi-stage lot-sizing problem with production capacities (MLSP-PC) deals with a supply chain that consists of a manufacturer with stationary production capacity and intermediaries (distribution centers or wholesalers) and a retailer to face deterministic demand. An optimal supply chain plan for the MLSP-PC specifies when and how many units each organization of the supply chain has to produ...

We optimize ordering and inbound shipment decisions for a manufacturer that sources multiple items from a single supplier. The objective is to satisfy the requirements in the production plan with minimum transportation and inventory holding costs over a multi-period planning horizon. Transportation costs are charged to the manufacturer on a per truck shipment basis. We investigate the option of...

This paper proposes two constructive heuristics for the well-known single-level uncapacitated dynamic lot-sizing problem. The proposed heuristics, called nLPC and nLPC(i), are developed by modifying the average period cost concept from Silver and Meal’s heuristic, commonly known as Least Period Cost (LPC). An improved tie-breaking stopping rule is also proposed in this paper. The computational ...