Contribution to the study of the multimodal transport problem in robust and multi-objective cases

Ce travail porte sur la modélisation et la résolution de problèmes d’optimisation robuste et multi-objectifs du transport multimodal. Après une synthèse des travaux de la littérature et des concepts de base de l’optimisation robuste et l’optimisation multi-objectif, nous proposons un nouveau modèle d’optimisation multi-objectif du transport multimodal des produits agricoles marocains vers des clients européens. L’objectif est de déterminer la meilleure stratégie d’exportation qui minimise simultanément le coût total de transport multimodal et l’overtime maximal en prenant en considération des contraintes réalistes. Nous proposons également des nouvelles approches de résolution avec une application sur un réseau de transport multimodal réel.Nous avons étudié une autre problématique du transport multimodal avec localisation de terminaux intermodaux. Outre la version déterministe, une optimisation robuste qui tient compte des incertitudes sur les capacités, les coûts d’utilisation et les coûts de transport. Deux approches hybrides ont été proposées pour la résolution du problème.Dans ces contributions, des modèles et des méthodes sont présentés, des remarques et des interprétations sont tirées à propos de l’impact de la périssabilité des produits et de la robustesse sur les flux, le choix des ports, des trajets et des modes de transport.Because of the importance of multimodal transport for goods importation and exportation from Morocco to international customers, our goals are modeling and solving multimodal freight transportation problems by more focusing on some issues confronted by our country. After presenting the required mathematical background on robust and multiobjective optimization and surveying the literature works on multimodal transport problems, its variants and solution approaches; and instead of testing them only on traditional benchmarks; we dealt with new variants and methods. A multi-objective mathematical model is proposed to optimize the multimodal transport of agricultural products from Morocco to Europe. To solve this model adapted to a real network, two multiobjective version algorithms are presented in order to optimize simultaneously the total transportation cost and the over-time.Given the complexity of the global logistics chain by various operations and several stakeholders, the data of the problem may sometimes be ignored or uncompleted. That’s why we have developed a mathematical model for multimodal terminal location problem by integrating uncertainties of the transportation costs, the capacities and the using costs of terminals. A population based simulated annealing and a hybrid method combining an exact and a metaheuristic approaches are proposed to effectively solving the problem. The test is then performed on a real intermodal network. These contributions are concluded by remarks and highlights about the impact of perishability and robustness on flows, location strategies of ports, the choice of paths and transportation modes

Contribution à l'étude du problème de transport multimodal dans le cas robuste et multi-objectif

Because of the importance of multimodal transport for goods importation and exportation from Morocco to international customers, our goals are modeling and solving multimodal freight transportation problems by more focusing on some issues confronted by our country. After presenting the required mathematical background on robust and multiobjective optimization and surveying the literature works on multimodal transport problems, its variants and solution approaches; and instead of testing them only on traditional benchmarks; we dealt with new variants and methods. A multi-objective mathematical model is proposed to optimize the multimodal transport of agricultural products from Morocco to Europe. To solve this model adapted to a real network, two multiobjective version algorithms are presented in order to optimize simultaneously the total transportation cost and the over-time.Given the complexity of the global logistics chain by various operations and several stakeholders, the data of the problem may sometimes be ignored or uncompleted. That’s why we have developed a mathematical model for multimodal terminal location problem by integrating uncertainties of the transportation costs, the capacities and the using costs of terminals. A population based simulated annealing and a hybrid method combining an exact and a metaheuristic approaches are proposed to effectively solving the problem. The test is then performed on a real intermodal network. These contributions are concluded by remarks and highlights about the impact of perishability and robustness on flows, location strategies of ports, the choice of paths and transportation modes.Ce travail porte sur la modélisation et la résolution de problèmes d’optimisation robuste et multi-objectifs du transport multimodal. Après une synthèse des travaux de la littérature et des concepts de base de l’optimisation robuste et l’optimisation multi-objectif, nous proposons un nouveau modèle d’optimisation multi-objectif du transport multimodal des produits agricoles marocains vers des clients européens. L’objectif est de déterminer la meilleure stratégie d’exportation qui minimise simultanément le coût total de transport multimodal et l’overtime maximal en prenant en considération des contraintes réalistes. Nous proposons également des nouvelles approches de résolution avec une application sur un réseau de transport multimodal réel.Nous avons étudié une autre problématique du transport multimodal avec localisation de terminaux intermodaux. Outre la version déterministe, une optimisation robuste qui tient compte des incertitudes sur les capacités, les coûts d’utilisation et les coûts de transport. Deux approches hybrides ont été proposées pour la résolution du problème.Dans ces contributions, des modèles et des méthodes sont présentés, des remarques et des interprétations sont tirées à propos de l’impact de la périssabilité des produits et de la robustesse sur les flux, le choix des ports, des trajets et des modes de transport

Modelling and solving a bi-objective intermodal transport problem of agricultural products

During the past few years, transportation of agricultural products is increasingly becoming a crucial problem in supply chain logistics. In this paper, we present a new mathematical formulation and two solution approaches for an intermodal transportation problem. The proposed bi-objective model is applied to the transportation of agricultural products from Morocco to Europe to minimise both the transportation cost either in the form of uni-modal or intermodal, as well as the maximal overtime to delivery products. The first solution approach is based on a non-dominated sorting genetic algorithm improved by a local search heuristic and the second one is the GRASP algorithm (Greedy Randomised Adaptive Search Procedure) with iterated local search heuristics. They are tested on theoretical and real case benchmark instances and compared with the standard NSGA-II. Results are analysed and the efficiency of algorithms is discussed using some performance metrics

A Robust Home Health Care Scheduling and Routing Approach with Time Windows and Synchronization Constraints Under Travel Time and Service Time Uncertainty

Part 4: Lean and Six Sigma in Services HealthcareInternational audienceHome health care (HHC) services represent a set of medical services given to patients at their homes. The patients require a set of care that must be coordinated and treated by skilled caregivers corresponding to their needs. This study proposes an HHC routing and assignment approach based on a mixed-integer linear programming model that aims to minimize total route cost. The HHC approach takes into account a set of HHC specific constraints and criteria. Secondly, we propose a new robust counterpart HHC model under uncertainty based on the well-known budgeted uncertainty set. The robust counterpart HHC model deals with travel and service times uncertainty. The computational results compare the deterministic model with its robust counterpart model. The small and medium instances have been solved using TSP benchmarks with specific data concerning HHC problems. The models have been implemented using ILOG CPLEX Optimization Studio. The computational results of small and medium instances indicated the efficiency of the proposed approach. Robustness analysis of the obtained results was conducted using a Monte Carlo simulation and indicated the price of robustness. The increase of route cost in comparison with the risk of infeasibility shows the importance of the designed robust routes for HHC routing and scheduling problems

A Multi-objective Approach for the Combined Master Surgical Schedule and Surgical Case Assignment Problems

International audienceIn this study, we propose a multi-objective approach to address the Master Surgical Schedule (MSS) and the Surgical Case Assignment (SCAP) problems for the common Operating Theater (OT) in an integrated hospital facility. The approach accounts for both surgeons' and Operating Rooms' (OR) availability and restrictions. We propose in this paper a multi-objective programming model that supports OT decision making to ensure patients' and surgeons' satisfaction and hospital quality of service by respecting surgeries due dates and balancing surgeons' workloads. The proposed approach determines the surgical discipline to perform on each session, the surgical cases assigned on each session, and the operations' start time on a weekly basis. The-constraint method is used to solve the multi-objective problem. The computational experiments are performed using ILOG CPLEX optimization studio. The model is tested on the empirical data archives of a medium-size French hospital and show the quality of solutions achieved using the proposed approach

A Three-stage Approach for the Multi-period Green Home Health Care Problem with Varying Speed Constraints

International audienceIn this paper, we address an environment-friendly approach to solve the Green Home Health Care (GHHC) routing and assignment problem. The approach aims to reduce fuel consumption to minimize carbon-dioxide emissions. The Home Health Care (HHC) routing and assignment problem is a very complex problem due to the multifactors and criteria that must be taken into consideration during the planning. The main of this work is to find an efficient working plan on a weekly basis, respecting continuity of care, with environmental concern, which ensures the satisfaction of both patients and caregivers and considers most of HHC constraints. The proposed approach is a threestage methodology; the first stage is a multi-objective programming model that minimizes the total traveled distance and fuel consumption with varying speed. In the second stage, we introduce an assignment heuristic, and the third stage is an Integer Linear Programming (ILP) model that aims to balance caregivers' workload. The small and medium instances are solved using CPLEX optimizer studio and show that better route planning and minimum fuel consumption is achieved with varying speed concept

Effect of physical exercise and training on gastrointestinal hormones in populations with different weight statuses

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Independent and Combined Effects of Antioxidant Supplementation and Circuit Resistance Training on Selected Adipokines in Postmenopausal Women

We examined the effects of the independent and combined effects of Zataria Multiflora supplementation and circuit resistance training (CRT) on selected adipokines among postmenopausal women. Forty-eight postmenopausal women were divided into four groups: Exercise (EG, n = 12), Zataria Multiflora (ZMG, n = 12), exercise and Zataria Multiflora (ZMEG, n = 12), and control (CG, n = 12). Participants in experimental groups either performed CRT (3 sessions per week with intensity at 55 of one-repetition maximum) or supplemented with Zataria Multiflora (500 mg every day after breakfast with 100 ml of water), or their combination, for 8 weeks. Blood samples were collected at pre- and post-intervention for measuring selected adipokines, including visfatin, omentin-1, vaspin, FGF-21, adiponectin, leptin, and ghrelin. Our findings demonstrated that visfatin, vaspin, and leptin levels significantly decreased over the intervention period (all p < 0.05), with these values were lower in EG and ZMEG in comparison to CG at post-intervention (all p < 0.05). Visfatin and vaspin levels were also lower in ZMEG in comparison to EG at post-intervention (both p < 0.05). In contrast, omentin-1, ghrelin, adiponectin, and FGF21 significantly increased in EG and EMG (all p < 0.05) after CRT. These findings suggest that Zataria Multiflora supplementation by itself has little effect on measured adipokines; however, its combination with CRT produced noticeable effects on circulating levels of these adipokines, even more than CRT alone. Consequently, a combination of CRT and Zataria Multiflora supplementation may represent a potentially beneficial non-pharmacologic intervention on some selected adipokines in postmenopausal women

Studies of the Structure and Optical Properties of BaSrMgWO6 Thin Films Deposited by a Spin-Coating Method

Highly transparent thin films with the chemical formula BaSrMgWO6 were deposited by spin coating using a solution of nitrates of Ba, Sr, and Mg and ammonium paratungstate in dimethylformamide with a Ba:Sr:Mg:W ratio = 1:1:1:1. XRD, SEM, EDX, and XPS investigations evidenced that annealing at 800 &deg;C for 1 h results in an amorphous structure having a precipitate on its surface, and that supplementary annealing at 850 &deg;C for 45 min forms a nanocrystalline structure and dissolves a portion of the precipitates. A textured double perovskite cubic structure (61.9%) was found, decorated with tetragonal and cubic impurity phases (12.7%), such as BaO2, SrO2, and MgO, and an under-stoichiometric phase (24.4%) with the chemical formula Ba2&minus;(x+y) SrxMgyWO5. From transmittance measurements, the values of the optical band gap were estimated for the amorphous (Egdir = 5.21 eV, Egind = 3.85 eV) and nanocrystalline (Egdir = 4.69 eV, Egind = 3.77 eV) phases. The presence of a lattice disorder was indicated by the high Urbach energy values and weak absorption tail energies. A decrease in their values was observed and attributed to the crystallization process, lattice strain diminution, and cation redistribution