When considering hub-and-spoke networks with multiple allocation, the classical models of literature compute solutions large discount factors for small flows on interhub connections. Addressing economies scale issue, a tighter formulation this problem is presented, bringing forward special structure. A specialized version Benders decomposition then developed to solve instances in reasonable time.

This paper presents the hub line location problem in which of a set facilities connected by means path (or line) is considered. Potential applications arise design public transportation and rapid transit systems, where network costs greatly dominate routing thus full interconnection unrealistic. Given that service time predominant objective these applications, considers minimization total weighted travel between origin/destination nodes while taking into account spent to access exit line. An...

This article formulates a model to analyze the role of fixed costs in design optimal transportation hub networks. The primary purpose this is better networks, an issue that has attracted considerable attention. allows particular versions networks emerge from cost structure, rather than by imposing rigid predefined connectivity protocol. integrates modeling approaches environmental location with three‐index formulation E rnst and K rishnamoorthy produce variable for all arcs. Our goal...

One of the most important challenges for mining engineers is to correctly analyze and generate short-term planning schedules, or simply month plan. The objective demonstrate how simulation optimization models were combined, with simultaneous execution, in order achieve a feasible, reliable accurate solution this problem. A tool based on Arena software Lingo was developed, tested approved within VALE (former CVRD Brazil), excellent results, presented paper.

One of the most important challenges for mining engineers is to correctly analyze and generate short-term planning schedules, or simply month plan. The objective demonstrate how simulation optimization models were combined, with simultaneous execution, in order achieve a feasible, reliable accurate solution this problem. A tool based on Arena software Lingo was developed, tested approved within VALE (former CVRD Brazil), excellent results, presented paper.

Multiechelon supply chains are complex logistics systems that require flexibility and coordination at a tactical level to cope with environmental uncertainties in an efficient effective manner. To these challenges, mathematical programming models developed evaluate chain flexibility. However, under uncertainty, become the scope of analysis is generally reduced. This paper presents unified approach can four-echelon via robust stochastic model. The model simultaneously considers plans multiple...

In this work, a mixed integer nonlinear programming model combining direct service links, demand uncertainty and congestion effects is proposed. This efficiently solved by Generalized Benders Decomposition, for instances of moderate sizes reasonable number scenarios. The deployed algorithms are further used re-designing the Brazilian air transportation network, enabling analysis future scenarios providing decision support about optimal investment policy Brazil.

This paper presents a Cut-and-Branch algorithm for the Multicommodity Traveling Salesman Problem (MTSP), useful variant of (TSP). The MTSP more general cost structure, allowing solutions that consider quality service to customers, delivery priorities and risk, among other possible objectives. In salesman pays traditional TSP fixed each arc visited, plus variable commodities being transported across network. We present strong mathematical formulation this relevant problem. implement which is...

We are introducing in this article the Multicommodity Traveling Salesman Problem (MTSP), where objective is to deliver all demands of different commodities by a tour that minimizes sum fixed and variable costs for selected arcs. The MTSP yields then large scale mixed integer linear programming problem. In we devise Lagrangean based heuristic approach tackle more general TSP variant.

When considering hub-and-spoke networks with single allocation, the absence of alternative routes makes this kind systems specially vulnerable to congestion effects. In order improve design such networks, costs must be addressed. This article deploys two different techniques for addressing on allocation networks: Generalized Benders Decomposition and Outer Approximation method. Both methods are able solve large scale instances. Computational experiments show how adoption advanced solution...

Transportation hub networks are important for many large-scale logistics and supply chain systems. Basic location models rely on some key assumptions about the transportation cost that limits their practicality We present a new model network design uses fixed variable costs all arcs, hubs, also allows direct arcs. This approach components to drive of network. provide basic formulation illustrative results show types optimal generated. The document wide range features can be generated from...

We are introducing in this article the Multicommodity Traveling Salesman Problem (MTSP), where objective is to deliver all demands of different commodities by a tour that minimizes sum fixed and variable costs for selected arcs. The MTSP yields then large scale mixed integer linear programming problem. In we devise Lagrangean based heuristic approach tackle more general TSP variant.