BACKGROUND In patients at high risk for regional node metastasis from squamous cell carcinoma (SCC) of the skin of the face, ear, or scalp, radiotherapy to the regional nodes is an alternative to parotid or neck surgery. Data on the efficacy of elective nodal radiotherapy in this setting are scarce such that there is no publication specifically addressing the subject. The purpose of our study i...

We provide a broad characterization of the supply chain settings in which perfect coordination can be achieved with a simple wholesale pricing scheme based on constant unit wholesale prices or a single quantity discount scheme. We confine ourselves to two-echelon chains with a single supplier servicing a network of retailers who compete with each other by selecting retail prices (Bertrand compe...

We study a multi-item, two-echelon, continuous-review inventory problem at a Dutch utility company, Liander. We develop a model that optimizes the quantities of service parts and their allocation in the two-echelon network under an aggregate waiting time restriction. Specific aspects that we address are emergency shipments in case of stockout, and batching for regular replenishment orders at th...

This paper analyzes a series inventory system with stationary costs and stochastic demand over an infinite horizon. A distinctive feature is that demand can be negative, representing returns from customers, as well as zero or positive. We observe that, as in a system with nonnegative demand, a stationary echelon base-stock policy is optimal here. However, the steadystate behavior of the system ...

Multi-echelon distribution systems are quite common in supply-chain and logistic management. They are used by public administrations in their transportation and traffic planning strategies as well as by companies to model their distribution systems. In the literature, most studies address issues related to the movement of flows throughout the system from the origins to their final destinations....

In this study we use a flexible policy of spare part management in the context of airports corrective maintenance activities and provide a new approach for mathematically evaluate the performances of systems with lateral transshipments in case of one-for-one ordering policies, transfer times and peaked demand. This study deals with the spare optimization of a large logistics company, in charge ...

In today’s dynamic market numerous dynamic influencing factors have seriously aggravates the difficulties of inventory planning of the complex distribution networks. This paper proposes a simulation-based hybrid approach for the optimization of the inventory policies in complex distribution networks. The initial multi-echelon inventory policies are handed over to a simulation model, which is ca...

background: the purpose of this study was to evaluate nodal irradiation with conventional three-field's technique. materials and methods: fifty patients with breast cancer were enrolled in this study. computed tomography scans in the supine treatment position were imported into a treatment planning system. levels i-iii axillary and supraclavicular nodes were identified and their depths to ...

in this paper, a hierarchical p-hub median problem is considered that all the nodes and arcs on the network have limited capacities. proposed model has three-level where the complete network at the top level consists of the central hubs. the second and third levels consist of hub and demand nodes respectively, which are connected through star networks. also, delivery time restriction is taken i...

A new two-layered optimisation-based control approach is developed for multi-product, multi-echelon supply chain networks. The first layer employs simple feedback controllers to maintain inventory levels at all network nodes within pre-specified targets. The feedback controllers are embedded as equality constraints within an optimisation framework that incorporates model predictive control prin...