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...

Multi-echelon transaction is a common situation in the supply chain nowadays. This research is to formulate a three-echelon integrated inventory model under defective products, reworking and credit period consideration. An algorithm and numerical analysis are used to observe the effect of defective rate and credit period time to the inventory policy and total profit.

Multi-echelon distribution schemes are one of the most common strategies adopted by the transport companies in an aim of cost reduction, but their identification in scientific literature is not always easy due to a lack of unification. This paper presents the main concepts of two-echelon distribution via a systematic review, in the specific a meta-narrative analysis, in order to identify and un...

The Two-Echelon Routing Problem constitutes a class of combinatorial optimization problems with applications in many different fields such as city logistic planning, intermodal transportation, postal and parcel delivery distribution systems and so on. This thesis contains: a survey of the main contributions related to the two-echelon routing, focusing on the Two-Echelon Location Routing Problem...

multi-echelon inventory systems are one of the most important and attractive areas in modelling supply chain management so that several researches and studies have been done about. in this paper, the total cost function of a two-echelon inventory system with central warehouse and many identical retailers controlled by continuous review inventory policy is estimated. we have assumed the demand i...

Hospitalization data were extracted for Marines wounded in Vietnam from 1965 to 1969 to examine the echelon flow of treatment care for different types of injuries. The inter-echelon movement of each patient who was hospitalized at an echelon II or III facility was tracked until the treatment was completed or until the patient was moved to a facility in the continental United States. Results sho...

The delivery of freight from its origin to its destination is often managed through one or more intermediate facilities where storing, merging and consolidation activities are performed. This type of distribution systems is commonly called multi-echelon, where each echelon refers to one level of the distribution network. Multi-echelon distribution systems are often considered by public administ...

In allusion to such problems as low accuracy and long convergence time in traditional two-echelon vehicle routing optimization algorithm, a Memetic algorithm (QDEMA) based on Q learning theory and differential evolution is proposed in this article to solve above problems. Firstly, it is necessary to research the two-echelon vehicle routing optimization problem and adopt the optimal segmentation...

We present a two-echelon dual-channel inventory model in which stocks are kept in both a manufacturer warehouse (upper echelon) and a retail store (lower echelon), and the product is available in two supply channels: a traditional retail store and an Internet-enabled direct channel. The system receives stochastic demand from two customer segments: those who prefer the traditional retail store a...