Abstract

In the efficient management of the supply chain the optimal management of transport of consumables and finished products appears. The costs associated with transport have direct impact on the final value consumers must pay, which in addition to requiring competitive products also demand that they are generated in environmentally friendly organizations. Aware of this reality, this document is intended to be a starting point for Master's and Doctoral degree students who want to work in a line of research recently proposed: green routing. The state of the art of the vehicle routing problem is presented in this paper, listing its variants, models and methodologies for solution. Furthermore, the proposed interaction between variants of classical routing problems and environmental effects of its operations, known in the literature as Green-VRP is presented. The goal is to generate a discussion in which mathematical models and solution strategies that can be applied within organizations that consider within their objectives an efficient and sustainable operation are posed. En el gerenciamiento eficiente de la cadena de suministro aparece la gestión óptima del transporte de insumos y productos terminados. Los costos asociados al transporte tienen impacto directo sobre el valor final que deben pagar los consumidores, que además de requerir productos competitivos también exigen que los mismos sean generados en organizaciones amigables con el medioambiente. Consientes de esa realidad este documento pretende ser un punto de partida para estudiantes de maestría y doctorado que quieran trabajar en una línea de investigación propuesta recientemente: el ruteo verde. En este trabajo se muestra un estado del arte del problema de ruteo de vehículos, enumerando sus variantes, modelos y metodologías de solución. Además, se presenta la interacción que se ha propuesto entre variantes clásicas de los problemas de ruteo y los efectos ambientales de su operación, denominados en la literatura como Green-VRP. El objetivo es generar una discusión donde se planteen modelos matemáticos y estrategias de solución que puedan ser aplicadas en organizaciones que consideren dentro de sus objetivos una operación eficiente y sustentable. Document type: Article

Abstract

Traffic congestion is a widespread epidemic that continually wreaks havoc in urban areas. Traffic jams, car wrecks, construction delays, and other causes of congestion, can turn even the biggest highways into a parking lot. Several congestion mitigation strategies are being studied, many focusing on micro-simulation of traffic to determine how modifying road structures will affect the flow of traffic and the networking perspective of vehicle-to-vehicle communication. Vehicle routing on a network of roads and intersections can be modeled as a distributed constraint optimization problem and solved using a range of centralized to decentralized techniques. In this paper, we present a constraint optimization model of a traffic routing problem. We produce congestion data using a sinusoidal wave pattern and vary its amplitude (saturation) and frequency (vehicle waves through a given intersection). Through empirical evaluation, we show how a centralized and decentralized solution each react to unknown congestion information that occurs after the initial route planning period. Document type: Part of book or chapter of book

Abstract

Recently, the quality and the diversity of transport services are more and more required. Moreover, in case of a great deal of services and selling goods, a significant part of price is transport cost. Thus, the design of models and applications which make possible efficient transport planning and scheduling becomes important. A great deal of real transport problems may be modelled by using Pickup and Delivery Problem with Time Windows (PDPTW) and capacity constraints, which is based on the realization of a set of transport requests by a fleet of vehicles with given capacities. Each request is described by pickup and delivery locations, time periods when pickup and delivery operations should be performed and needed load. Application of evolutionary approach has brought good results in case of another, simpler transport problem – the Vehicle Routing Problem with Time Windows (VRPTW). This paper is aimed at proposing a straightforward extension of VRPTW based heuristics for the PDPTW. Document type: Part of book or chapter of book

Abstract

Part 5: Modelling and Optimization; International audience; In this paper, we address the problem of determining the optimal fleet size for Personal Rapid Transit system (PRT). In our problem, we consider electric battery and distance constraints which are found in real world application of the PRT system. To tackle this problem, we propose two valid mathematical formulations that are able to find optimal fleet size. Extensive computational experiments show that the edge based formulation performs impressively well, in terms of solution quality and computational time in comparison to the node based formulation. Document type: Part of book or chapter of book

Abstract

SDO; "p"Electric vehicle routing problems (eVRPs) extend classical routing problems to consider the limited driving range of electric vehicles. In general, this limitation is overcome by introducing planned detours to battery charging stations. Most existing eVRP models rely on one (or both) of the following assumptions: (i) the vehicles fully charge their batteries every time they reach a charging station, and (ii) the battery charge level is a linear function of the charging time. In practical situations, however, the amount of charge is a decision variable, and the battery charge level is a concave function of the charging time.In this paper we extend current eVRP models to consider partial charging and nonlinear charging functions. We present a computational study comparing our assumptions with those commonly made in the literature. Our results suggest that neglecting partial and nonlinear charging may lead to infeasible or overly expensive solutions.

Abstract

Part 3: Smart City Interoperability and Cross-Platform Implementation; International audience; In today’s challenging sector of logistics and transportation, companies, seek to adapt software which leads to efficient solutions at an acceptable cost. Conventional routing software is developed to solve vehicle routing problem and help managers and planners in decision making. Simultaneously, specific constraints and different VRP (Vehicle Routing Problem) variants are considered each time, such as the Capacitated, the Multi Depot and the Pickup and Delivery VRP. However, the last few years the need for more reliable deliveries and better customer services arose. In addition, reducing travel distance, travel cost and environmental impact are important factors encountered in urban freight transportation. Therefore, routing software needs to take into account multiple constraints. Such constraints are traffic congestion, speed limits, transportation regulations and restricted zones. These constraints affect mainly Time dependent VRP, VRP with Time Windows, Dynamic VRP and Green VRP. Data collection and processing are essential in routing software for solving these variants and offering the best solution. The methods for solving these problems, along with technological achievements, including cloud computing, can lead to efficient, easily adaptable routing software. Such software solutions can eventually render companies with complex transportation and logistics problems, competitive. The scope of this paper is to describe the concept and methodological approach for the development of such a routing and scheduling system, operating in a cloud environment. The definition of its requirements and the development of the system is the main purpose of an ongoing research project, being in its first stages of system’s analysis and design. Document type: Conference object

Abstract

Due to the regulation and laws concerning the emission of greenhouse gasses, carriers are starting to use electric vehicles for last-mile deliveries. The limited battery capacities of these vehicles necessitate visits to recharging stations during delivery tours of industry-typical length, which have to be considered in the route planning to avoid inefficient vehicle routes with long detours. This thesis seeks to propose new heuristic solution methods for Electric Vehicle Routing Problem with Time Windows (E-VRPTW), which incorporates the possibility of recharging at any of the available charging stations to minimize the total travel distance based on the Clarke and Wright (CW) Saving Heuristic. The solution method focuses on the construction of routes according to waiting time of vehicles, determined priority of customers with regard to their earliest starting service time, customers’ demands and etc. Moreover, the recharging rate, vehicle freight capacity, battery capacity, time windows and recharging time are considered to make it close to real-life logistics problems. Numerical tests are performed on newly designed instances by Schneider and performances of proposed methods are discussed. Keywords: Vehicle Routing Problem, Clarke and Wright Saving Heuristic, Green Logistic, Electric Vehicles, Combinatorial Optimization ÖZ : Sera gazlarının salınımı ile ilgili kural ve yasalardan dolayı taşımacılar şehir içi taşımalarını elektrikle çalışan araçlarla yapmaya başlamışlardır. Bu araçların sınırlı olan batarya kapasiteleri, taşıma sırasında zorunlu olarak batarya dolum istasyonlarında şarj edilmeleri gereksinimini doğurmakta ve bu durum da uzun ve verimsiz rotaların önlenmesi için rota planlamasında gözönüne alınmalıdır. Bu tezin amacı, alınan toplam mesafeyi enküçüklemek amacıyla şarjın tüm dolum istasyonlarında mümkün olduğu ve Clarke & Wright tasarruf algoritmasını esas alan Electric Vehicle Routing Problem with Time Windows (E-VRPTW) problemine yeni bir sezgisel çözüm yöntemi önermektir. Önerilen çözüm yöntemi öncelikle araçların bekleme sürelerine, müşterilerin zaman önceliklerine, taleplerine vs. göre rotalar oluşturmaya odaklanmaktadır. Problemin lojistik olarak daha da gerçekçi olmasını sağlamak üzere araçların taşıma kapasiteleri, batarya kapasiteleri, zaman aralıkları, şarj zamanları ve hızları da gözönüne alınmıştır. Schneider’in değerleri üzerinden sayısal deneyler de yapılmış ve önerilen yöntemlerin performansları da tartışılmıştır. Anahtar Kelimeler: Araç rotalama sorunu, Clarke ve Wright tasarruf sezgiseli, yeşil lojistik, elektrikli araçlar, birleşi eniyilemesi Master of Science in Industrial Engineering. Thesis (M.S.)--Eastern Mediterranean University, Faculty of Engineering, Dept. of Industrial Engineering, 2014. Co-Supervisor: Assoc. Prof. Dr. Bülent Çatay, Supervisor: Assist. Prof. Dr. Gökhan İzbırak.