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A MODELLING FRAMEWORK FOR PROCUREMENT OF A RETAIL DISTRIBUTION SYSTEM WITH ECONOMIC AND ENVIRONMENTAL GOALS

International audienc

A state of the art and a general formulation model of Hub Location-Routing Problems for LTL shipments

National audienceIn many logistic systems for less than truckload (LTL) shipments, transportation of goods from one origin to its destination is made through collection tours to a hub and delivery tours from the same or another hub, while the goods are shipped between two hubs using Full Truckload (FTL) shipments. Therefore, managers need to determine the location of the hubs, the allocation of non-hub nodes, and the optimal collection and delivery routes within the network. This problem, known as the hub location-routing problem (HLRP), is related to both the hub location problem (HLP) and the location-routing problem (LRP). The HLP involves the location of hub facilities concentrating flows in order to take advantage of economies of scale and through which flows are to be routed from origins to destinations. The objective of the HLRP is to minimize the total costs including hub costs, inter-hub transportation costs, and collection/distribution routing costs. Based on the literatures review, the aims of this paper are to analyze the state of the art, propose some generic mathematical models for the HLRP and implement some tests using a MIP solver

Estudo comparativo da aderência de vergalhões de aço e de materiais compósitos ao concreto com alta salinidade, utilizando técnicas de imagem por raios x coletadas in-situ

Dissertação de Mestrado apresentada ao Programa de Pós- Graduação em Física Aplicada da Universidade Federal da Integração Latino-Americana (PPGFISA-UNILA) como parte dos requisitos necessários para obtenção do título de Mestre em Física. Orientador: Prof. Dr. Marcelo Gonçalves Hönnicke Coorientadora: Prof. Dra Ana Carolina Parapinski SantosO uso de areia salgada na mistura de concretos para construção civil tem crescido especialmente em locais onde existe escassez do produto. Contudo, essa salinidade ataca diretamente os vergalhões de aço nas estruturas de concreto armado, ocasionando problemas de corrosão. Uma alternativa é a utilização de vergalhões de materiais compósitos, que muitas vezes apresentam resistência mecânica igual ou superior ao aço, com a vantagem de não estarem sujeitos à corrosão. Geralmente, tais vergalhões são fabricados com fibras (basalto, vidro ou carbono) em uma matriz polimérica (resina epoxi). Neste trabalho foi realizado um estudo comparativo de amostras de concreto armado (corpos de prova), submetidos ao ensaio “pull-out”, do qual é possível obter informações da aderência entre o concreto e os vergalhões inseridos nos corpos de prova. As propriedades dos vergalhões utilizados foram verificadas por medidas de difração de raios X, microscopia eletrônica (imagem e espectroscopia - EDS) e por ensaio de tração. Para cada tipo de vergalhão (Aço CA-50, Fibra de basalto e Fibra de vidro) foram produzidos corpos de prova em dois conjuntos: i) O primeiro contendo concreto com adição de cloreto de sódio (sal) e; ii) O segundo contendo concreto sem adição de cloreto de sódio. Os ensaios “pull-out” foram realizados em diferentes estágios de envelhecimento (63, 217 e 315 dias) após a moldagem dos corpos de prova. Os resultados obtidos mostram que a aderência entre os materiais diminui para os corpos de prova moldados com vergalhões de aço e concreto com adição sal (cerca de 20% em 315 dias), devido principalmente ao processo corrosivo. Esta diminuição da aderência não foi observada nos corpos de prova moldados com vergalhões de materiais compósitos (Fibra de basalto e Fibra de vidro). Os resultados também mostram que os vergalhões de Aço CA-50 suportam em média uma tensão de aderência superior (cerca de 30%) comparado aos vergalhões de materiais compósitos. Das radiografias realizadas in-situ foi possível extrair algumas informações importantes, tais como, locais de máxima compressão do concreto antes da perda de aderência, aparecimento de fissuras longitudinais e, o momento exato que ocorre a perda de aderência entre o vergalhão e o concreto.The use of salty sand in the concrete mixture for building construction has grown especially in places where there is absence of regular sand. However, the salinity attacks the steel rebar in reinforced concrete structures, resulting in corrosion problems. An alternative is to use composite material rebars, which shows similar or superior mechanical strength compared to steel rebar and are not strongly affected by corrosion. Usually, theses rebars are manufactured with fibers (basalt, glass or carbon) in a polymer matrix (Epoxy resin). In this work, reinforced concrete samples (test samples) with and without addition of salt (sodium chloride), molded with different rebars (CA-50 Steel, Basalt Fiber and Glass Fiber), were submitted to the pull-out tests in order to take bonding information between the concrete and the rebar. The pull-out tests were performed at different ages (63, 217 and 315 days) after the molding. The results showed a bonding loss (about 20% in 315 days) for the test samples molded with steel rebar and salty concrete. This bonding loss was not observed in test samples molded with composite rebars (basalt fiber and glass fiber). Also, it was possible to detect that the CA-50 steel rebar supports higher bond strengths (~ 30% higher) compared to the composite rebars. Indeed, with in-situ radiographies, was possible to extract different information such as: i) locations of maximum concrete compression before the bonding loss; ii) appearance of longitudinal cracks and; iii) the exact moment of bonding loss between rebar and concrete. At last, the rebar properties were checked by tests of conformance, including X- ray diffraction, electron microscopy (imaging and spectroscopy - EDS) and stress-strain. Keywords: salty-sand concrete, bonding, composite material rebars, pull-out test, in-situ” radiograph

An adaptive large neighborhood search for a full truckload routing problem in public works

International audienceThis paper presents a truck routing and scheduling problem faced by a public works company. Itconsists of optimizing the collection and delivery of materials between sites, using a heterogeneousfleet of vehicles. These flows of materials arise in levelling works and construction of roads networks.As the quantity of demands usually exceeds the capacity of a truck, several trucks are needed tofulfill them. As a result, demands are split into full truckloads. A set of trucks routes are needed toserve a set of demands sharing a set of resources, available at pickup or delivery sites, which can beloaders or asphalt finishers in our application cases. Thus, these routes need to be synchronized ateach resource. We propose an Adaptive Large Neighborhood Search (ALNS) to solve this problem.This approach is evaluated on real instances from a public work company in France

Prognostic factors for survival of women with unstable spinal bone metastases from breast cancer

Background: Bone metastases are an important clinical issue in women with breast cancer. Particularly, unstable spinal bone metastases (SBM) are a major cause of severe morbidity and reduced quality of life (QoL) due to frequent immobilization. Radiotherapy (RT) is the major treatment modality and is capable of promoting re-ossification and improving stability. Since local therapy response is excellent, survival of these patients with unstable SBM is of high clinical importance. We therefore conducted this analysis to assess survival and to determine prognostic factors for bone survival (BS) in women with breast cancer and unstable SBM. Methods: A total population of 92 women with unstable SBM from breast cancer who were treated with RT at our department between January 2000 and January 2012 was retrospectively investigated. We calculated overall survival (OS) and BS (time between first diagnosis of bone metastases until death) with the Kaplan-Meier method and assessed prognostic factors for BS with a Cox regression model. Results: Mean age at first diagnosis of breast cancer was 60.8 years ± SD 12.4 years. OS after 1, 2 and 5 years was 84.8, 66.3 and 50 %, respectively. BS after 1, 2 and 5 years was 62.0, 33.7 and 12 %, respectively. An age > 50 years (p < .001; HR 1.036 [CI 1.015–1.057]), the presence of a single bone metastasis (p = .002; HR 0.469 [CI 0.292–0.753]) and triple negative phenotype (p < .001; HR 1.068 [CI 0.933–1.125]) were identified as independent prognostic factors for BS. Conclusions: Our analysis demonstrated a short survival of women with breast cancer and unstable SBM. Age, presence of a solitary SBM and triple-negative phenotype correlated with survival. Our results may have an impact on therapeutic decisions in the future and offer a rationale for future prospective investigations

Modélisation et résolution de problèmes généralisés de tournées de véhicules

Le problème de tournées de véhicules est un des problèmes d optimisation combinatoire les plus connus et les plus difficiles. Il s agit de déterminer les tournées optimales pour une flotte de véhicules afin de servir un ensemble donné de clients. Dans les problèmes classiques de transport, chaque client est normalement servi à partir d un seul nœud (ou arc). Pour cela, on définit toujours un ensemble donné de nœuds (ou arcs) obligatoires à visiter ou traverser, et on recherche la solution à partir de cet ensemble de nœuds (ou arcs). Mais dans plusieurs applications réelles où un client peut être servi à partir de plus d un nœud, (ou arc), les problèmes généralisés qui en résultent sont plus complexes. Le but principal de cette thèse est d étudier trois problèmes généralisés de tournées de véhicules. Le premier problème de la tournée sur arcs suffisamment proche (CEARP), comporte une application réelle intéressante en routage pour le relevé des compteurs à distance ; les deux autres problèmes, problème de tournées couvrantes multi-véhicules (mCTP) et problème généralisé de tournées sur nœuds (GVRP), permettent de modéliser des problèmes de conception des réseaux de transport à deux niveaux. Pour résoudre ces problèmes, nous proposons une approche exacte ainsi que des métaheuristiques. Pour développer la méthode exacte, nous formulons chaque problème comme un programme mathématique, puis nous construisons des algorithmes de type branchement et coupes. Les métaheuristiques sont basées sur le ELS (ou Evolutionary Local Search) et sur le GRASP (ou Greedy Randomized Adaptive Search Procedure). De nombreuses expérimentations montrent la performance de nos méthodes.The Routing Problem is one of the most popular and challenging combinatorial optimization problems. It involves finding the optimal set of routes for fleet of vehicles in order to serve a given set of customers. In the classic transportation problems, each customer is normally served by only one node (or arc). Therefore, there is always a given set of required nodes (or arcs) that have to be visited or traversed, and we just need to find the solution from this set of nodes (or arcs). But in many real applications where a customer can be served by from more than one node (or arc), the generalized resulting problems are more complex. The primary goal of this thesis is to study three generalized routing problems. The first one, the Close-Enough Arc Routing Problem(CEARP), has an interesting real-life application to routing for meter reading while the others two, the multi-vehicle Covering Tour Problem (mCTP) and the Generalized Vehicle Routing Problem(GVRP), can model problems concerned with the design of bilevel transportation networks. The problems are solved by exact methods as well as metaheuristics. To develop exact methods, we formulate each problem as a mathematical program, and then develop branch-and-cut algorithms. The metaheuristics are based on the evolutionary local search (ELS) method et on the greedy randomized adaptive search procedure (GRASP) method. The extensive computational experiments show the performance of our methods.NANTES-ENS Mines (441092314) / SudocSudocFranceF

The influence of orthopedic corsets on the incidence of pathological fractures in patients with spinal bone metastases after radiotherapy

Background: Clinical care of unstable spinal bone metastases in many centers often includes patient immobilization by means of an orthopedic corset in order to prevent pathological fractures. The aim of this retrospective analysis was to evaluate the incidence of pathological fractures after radiotherapy (RT) in patients with and without orthopedic corsets and to assess prognostic factors for pathological fractures in patients with spinal bone metastases. Methods: The incidence of pathological fractures in 915 patients with 2.195 osteolytic metastases in the thoracic and lumbar spine was evaluated retrospectively on the basis of computed tomography (CT) scans between January 2000 and January 2012 depending on prescription and wearing of patient-customized orthopedic corsets. Results: In the corset group, 6.8 and 8.0 % in no-corset group showed pathological fractures prior to RT, no significant difference between groups was detected (p = 0.473). After 6 months, patients in the corset group showed pathological fractures in 8.6 % and in no-corset group in 9.3 % (p = 0.709). The univariate and bivariate analyses demonstrated no significant prognostic factor for incidence of pathological fractures in both groups. Conclusions: In this analysis, we could show for the first time in more than 900 patients, that abandoning a general corset supply in patients with spinal metastases does not significantly cause increased rates of pathological fractures. Importantly, the incidence of pathological fracture after RT was small

A memetic algorithm for the hub location-routing problem

International audienceIn many logistic systems for less than truckload (LTL) shipments, transportation of goods is made through collection/delivery tours to/from a hub. The design of such a logistic network corresponds to the Hub Location Routing Problem (HLRP). HLRP consists in locating hub facilities concentrating flows in order to take advantage of economies of scale and through which flows are to be routed from origins to destinations, and considers also both collection and distribution routes. We present a generic MIP formulation of this problem and a solution method based on a genetic algorithm improved by some local searches. Computational experiments are presented