We derive approximations for the service levels of two-echelon inventory systems with lost sales and Poisson demand. Our method is simple and accurate for a very broad range of problem instances, including cases with both high and low service levels. In contrast, existing methods only perform well for limited problem settings, or under restrictive assumptions.

The initial database search cost deteriorates due to record additions, deletions and updates performed during the system operation. Previous studies proposed strategies for selecting the optimum maintenance points by making various assumptions about the rate of database deterioration, the database planning period, the maintenance interval, etc. However, the studies did not express the optimum m...

I this paper, we investigate the equilibrium behavior of decentralized supply chains with competing retailers under demand uncertainty. We also design contractual arrangements between the parties that allow the decentralized chain to perform as well as a centralized one. We address these questions in the context of two-echelon supply chains with a single supplier servicing a network of (competi...

H-rotor Vertical Axis Wind Turbine (VAWT) is one of the most efficient energy suppliers which have been investigated in many recent types of research. The aim of this work is to study the aerodynamic performance of a doubled-row H-Darrieus VAWT. First, an ordinary three-bladed VAWT with NACA4415 profile is simulated by means of 3D computational fluid dynamics (CFD) and results are compared to a...

Increasing level of carbon dioxide CO2 due to industrial activity is primarily cause of global warming. Planting Artoplex lentiformis can help to reduce atmospheric CO2 buildup partly replacing use of fuels and by carbon storage. The objective of this study was to determine the effects of row spacing on carbon storage. A split- plot design with three replications included three row spacing (2×2...

A field experiment was conducted to assess the optimum inter- and intra-row spacing on growth, yield and yield component of Roselle (Hibiscus sabdariffa L.) in 2014/15 cropping season at Wondo Genet Agricultural Research Center experimental site (at Wondo Genet station). Two inter-row spacing (60 and 90 cm) and three intra-row spacing (30, 60 and 90 cm) were evaluated using two varieties, WG-Hi...

Rapeseed (Brassica napus L.) is an important alternate oilseed crop in eastern Anatolia, Turkey. No information on plant density for rapeseed is available in this region. Therefore a study was initiated to investigate the effects of spacings between rows and spacings within rows on the yield and agronomic characteristics of two genotypes of spring rapeseed (Tower and Lirawell) in Erzurum, easte...