Agriculture fleet vehicle routing: A decentralised and dynamic problem

To date, the research on agriculture vehicles in general and Agriculture Mobile Robots (AMRs) in particular has focused on a single vehicle (robot) and its agriculture-specific capabilities. Very little work has explored the coordination of fleets of such vehicles in the daily execution of farming tasks. This is especially the case when considering overall fleet performance, its efficiency and scalability in the context of highly automated agriculture vehicles that perform tasks throughout multiple fields potentially owned by different farmers and/or enterprises. The potential impact of automating AMR fleet coordination on commercial agriculture is immense. Major conglomerates with large and heterogeneous fleets of agriculture vehicles could operate on huge land areas without human operators to effect precision farming. In this paper, we propose the Agriculture Fleet Vehicle Routing Problem (AF-VRP) which, to the best of our knowledge, differs from any other version of the Vehicle Routing Problem studied so far. We focus on the dynamic and decentralised version of this problem applicable in environments involving multiple agriculture machinery and farm owners where concepts of fairness and equity must be considered. Such a problem combines three related problems: the dynamic assignment problem, the dynamic 3-index assignment problem and the capacitated arc routing problem. We review the state-of-the-art and categorise solution approaches as centralised, distributed and decentralised, based on the underlining decision-making context. Finally, we discuss open challenges in applying distributed and decentralised coordination approaches to this problem

0357 : Platypnea orthodeoxia syndrome: focus on predisposing anatomical factors

Platypnea orthodeoxia syndrome (POS) is a rare situation with hypoxia and breathlessness in the upright position recovering in the recumbent position. A mechanical inter-atrial septum distortion, causing redirection of flow from the right to the left atrium through a patent foramen ovale (PFO), despite normal pulmonary pressure, is suggested to explain POS. Prevalence of predisposing anatomical factors remain little knownMethodsAll patients who underwent a PFO closure for a POS were retrospectively included from 2 CHU. Predisposing anatomical factors were investigated.Results67 patients (Median age 72 y.o., interquartile range 61-80; 58.2% men) were included. All patients had dyspnea (76.2% NYHA III or IV, 53.7% under oxygen-therapy). The remaining patients had a refractory hypoxemia (38.2%) without POS. Most frequent predisposing anatomical factor was an enlarged or unwound aorta (n=29, 43.3% 95CI 31.2-56.0) with an aortic aneurysm in 25 patients (37.3%, 95CI 25.8-50.0). Other factors identified were pneumonectomy (n=8, 11.9% CI95 5.3-22.2), a history of cardiac surgery (n=7, 10.5%, 95CI 4.3-20.3), mechanical ventilation (n=6, 9.0% 95CI 3.4-18.5), kyphoscoliosis (n=4, 6.0% 95CI 1.7-14.6), hepatomegaly (n=4, 6.0% 95CI 1.7-14.6, 2 patients with hepato-renal polycystic disease, one hemochromatosis and one cirrhosis), right ventricle failure (n=2,3.0% 95CI 0.4-10.4), pericardial effusions (n=2,3.0% 95CI 0.4-10.4), right ventricle arrhythmogenic dysplasia (n=2,3.0% 95CI 0.4-10.4), diaphragmatic paralysis (n=1, 1.5% 95CI 0.1-8.0), carcinoid syndrome with tricuspid regurgitation (n=1, 1.5% 95CI 0.1-8.0), a right atrium pace-maker lead (n=1, 1.5% 95CI 0.1-8.0) and a tako-tsubo syndrome (n=1, 1.5% 95CI 0.1-8.0).ConclusionAortic aneurysm and pneumonectomy are the most frequent situation leading to a POS. Other causes were observed such as hepato-renal polycystic kidney, or atrial pacemaker probe that may be underdiagnosed in clinical practice

Classical Exact Algorithms for the Capacitated Vehicle Routing Problem

In this chapter we present an overview of the early exact methods used for the solution of the Capacitated Vehicle Routing Problem (CVRP). The CVRP is an extension of the well-known Traveling Salesman Problem (TSP), calling for the determination of a Hamiltonian circuit with minimum cost visiting exactly once a given set of points. Therefore, the foundation of many exact approaches for the CVRP were derived from the extensive and successful work done for the exact solution of the TSP. However, even if tremendous progress has been made with respect to the first algorithms, such as the tree search method by Christofides and Eilon [17], the CVRP is still far from being satisfactorily solved. Our analysis encompasses more than three decades of research and examines the main families of approaches, from direct tree search methods based on Branch-and-Bound to column generation and Branch-and-Cut algorithms presented around the year 2000. The wide variety and richness of methods proposed in these early decades of CVRP history is witnessed by the good number of survey works that analyzed the relevant literature. Following the first comprehensive work of Laporte and Nobert [39], several review papers were devoted to the analysis of exact algorithms for the VRP as those of Laporte [36], Toth and Vigo [52, 53], Bramel and Simchi-Levi [15], Naddef and Rinaldi [47], Cordeau et al. [20], and Baldacci, Toth, and Vigo [10,11]. More recent Branch-and-Cut-and-Price algorithms, which have successfully combined and enhanced those described in the following, will be covered in detail in Chapter 3