PASA: A Priori Adaptive Splitting Algorithm for the Split Delivery Vehicle Routing Problem

The split delivery vehicle routing problem (SDVRP) is a relaxed variant of the capacitated vehicle routing problem (CVRP) where the restriction that each customer is visited precisely once is removed. Compared with CVRP, the SDVRP allows a reduction in the cost of the routes traveled by vehicles. The exact methods to solve the SDVRP are computationally expensive. Moreover, the complexity and difficult implementation of the state-of-the-art heuristic approaches hinder their application in real-life scenarios of the SDVRP. In this paper, we propose an easily understandable and effective approach to solve the SDVPR based on an a priori adaptive splitting algorithm (PASA). The idea of a priori split strategy was first introduced in Chen et al. (2017). In this approach, the demand of the customers is split into smaller values using a fixed splitting rule in advance. Consequently, the original SDVRP instance is converted to a CVRP instance which is solved using an existing CVRP solver. While the proposed a priori splitting rule in Chen et al. (2017) is fixed for all customers regardless of their demand and location, we suggest an adaptive splitting rule that takes into account the distance of the customers to the depot and their demand values. Our experiments show that PASA can generate solutions comparable to the state-of-the-art but much faster. Furthermore, our algorithm outperforms the fixed a priori splitting rule proposed by Chen et al. (2017)

Analyzing a fleet solution using scenarios

Transportation is one of the most important logistics activities, accounting for a significant part of the logistics costs and with high level of impact in terms of the service level provided to the customer. To counteract the upward trend in costs, it is fundamental to identify a transport strategy that can reduce costs and, at the same time, does not adversely affect the service levels agreed with customers. The main objective of this research is to propose a methodology for companies to identify, from a set of scenarios proposed and through a comparative analysis of scenarios, a new fleet solution, allowing the Company under study to reduce its transport costs without harming the current service level agreements with its customers. This research is grounded on a case study methodology. The case study used is of a small Portuguese company that produces, imports and distributes a wide range of products. The distribution is conducted based on both its own fleet and subcontracted transportation. The comparative analysis of scenarios allowed identifying the current transportation solution as the most advantageous one for the company. A roadmap to address fleet solution is provided.info:eu-repo/semantics/acceptedVersio

Una aplicación web, para asignación y ruteo de vehículos en caso de desastres

The natural disasters are events that exceed the capacity of covering of a population and generate large losses, both economic and humans, with externalities in many cases not quantified in their entirety. The resources needed to supply the distribution centers are provided both private and government must allocate providers, by the disaster damage. Then, the distribution is performed from the depots, to the different customers or distribution centers. It presents a web application that assigns the super depots, and then establishes the routing that the vehicles must follow to cover the distribution centers, considering different probabilities of populations to be covered. The application is a parametric framework to any geographical area and scenarios, given the existing integration with applications such as Google Maps ®. Computational times are reasonable, and at the software architecture level the product is scalable and extensible. In addition, it complies with a set of good software quality practices present in ISO9126.Los desastres naturales, son eventos que exceden la capacidad de respuesta de una población y generan cuantiosas pérdidas, tanto económicas como humanas, con externalidades en muchos casos no cuantificadas en su totalidad. Los recursos necesarios para abastecer los centros de distribución son provistos tanto por proveedores privados como gubernamentales, deben ser asignados en virtud del daño del desastre. Luego viene la distribución desde los depósitos, hasta los distintos clientes o centros de distribución. Se presenta una aplicación web que asigna los superdepósitos, y luego establece el ruteo que han de seguir los vehículos para cubrir los centros de distribución, considerando diversas probabilidades de poblaciones que han de ser cubiertas. La aplicación es un marco de trabajo paramétrico a cualquier zona geográfica y escenarios, dado la integración existente con aplicaciones como Google Maps ®. Los tiempos computacionales son razonables, a nivel de arquitectura de software el producto es escalable y extensible. Además, cumple con un conjunto de buenas prácticas de calidad de software presentes en la ISO9126

DYMEMULP – Dynamic Model of Process Optimisation in Regional Logistics

The expansion of logistics requirements, limited space and strict requirements of generators of logistics requests (GLR) in terms of service quality complicate the supply of the region, resulting in the necessity to improve logistics models (MoL). Proximity to water, the presence of ports and piers along the coast, new eco vehicles and the development of cooperation between land and water transport are elements for improving the existing MoLs in an economically and environmentally acceptable way. Research on the development of an improved multi-echelon logistics network with variable terminals including the coordination and cooperation of a heterogeneous group of transport agencies for the realisation of goods flows represents an innovation in regional logistics (RL). This article presents an integrated MoL development process using dynamic optimisation with a focus on spatial, temporal, transport, economic and environmental components

Logística inversa de residuos agroquímicos en Argentina: resolución heurística y exacta

Argentina es uno de los principales exportadores de productos agrícolas del mundo, localizándose gran parte de esta producción en la región pampeana. Debido a su enorme escala, esta actividad, además de generar importantes ingresos a nuestro país, también origina una gran cantidad de residuos especiales, entre ellos, los envases de los agroquímicos. Son conocidos los problemas ambientales y económicos que genera el incorrecto manejo de estos residuos por poseer sustancias que representan un riesgo para la salud y el medio ambiente. Teniendo en cuenta esta problemática, la Universidad Nacional del Sur (UNS) y la Universidad Provincial del Sudoeste (UPSO), proponen diseñar un sistema de reciclado de dichos envases en la región que comprende los veintiún municipios del sudoeste bonaerense (SOB). En el marco de este proyecto, el presente trabajo consistió en la optimización de la red logística de recolección de los residuos agroquímicos y la evaluación de la localización de la planta de tratamiento de los mismos. El modelado de la red se abordó como un problema CVRP (Capacitated Vehicle Routing Problem). Se consideraron distintas frecuencias de recolección y se resolvió mediante técnicas exactas y heurísticas

Logística inversa de residuos agroquímicos en Argentina: resolución heurística y exacta

Argentina es uno de los principales exportadores de productos agrícolas del mundo, localizándose gran parte de esta producción en la región pampeana. Debido a su enorme escala, esta actividad, además de generar importantes ingresos a nuestro país, también origina una gran cantidad de residuos especiales, entre ellos, los envases de los agroquímicos. Son conocidos los problemas ambientales y económicos que genera el incorrecto manejo de estos residuos por poseer sustancias que representan un riesgo para la salud y el medio ambiente. Teniendo en cuenta esta problemática, la Universidad Nacional del Sur (UNS) y la Universidad Provincial del Sudoeste (UPSO), proponen diseñar un sistema de reciclado de dichos envases en la región que comprende los veintiún municipios del sudoeste bonaerense (SOB). En el marco de este proyecto, el presente trabajo consistió en la optimización de la red logística de recolección de los residuos agroquímicos y la evaluación de la localización de la planta de tratamiento de los mismos. El modelado de la red se abordó como un problema CVRP (Capacitated Vehicle Routing Problem). Se consideraron distintas frecuencias de recolección y se resolvió mediante técnicas exactas y heurísticas.Sociedad Argentina de Informática e Investigación Operativ

UMA HEURÍSTICA ILS PARA A RESOLUÇÃO DO PROBLEMA DE ROTEAMENTO DE VEÍCULOS COM FROTA HETEROGÊNEA

O problema de roteamento de veículos com frota heterogênea (PRVFH) é um problema de otimização combinatória que, devido à variação na capacidade dos veículos, ao número de restrições e ao número de clientes a serem visitados, apresenta elevada complexidade computacional. O objetivo principal do PRVFH é determinar o melhor conjunto de rotas possível que os veículos possam percorrer entre o depósito e os clientes, observando a capacidade de cada veículo. O presente trabalho apresenta uma abordagem utilizando a meta-heurística Iterated Iocal Search (ILS) para resolução do PRVFH. A solução inicial é obtida pelo procedimento de economias (Clarke-Wright). Como métodos de busca local, foram adotados os movimentos two-opt e two-point-move para melhorar as soluções. Os resultados, quando comparados a solução inicial obtida usando a heurística de Clarke-Wright, chegaram a melhorias de até 23%, com tempos computacionais abaixo de sete segundos. O método foi aplicado a 27 instâncias encontradas na literatura e adaptadas para o problema com variação de 32 a 80 clientes

The influence of time windows on the costs of urban freight distribution services in city logistics applications

In freight distribution services a required quality level may have a relevant effect on transportation costs. For this reason an evaluation tool is useful to compare different service settings and support the decision, on the base of quantitative indicators. This paper proposes a method for cost evaluation in this context and presents an application to a case study concerning a freight distribution service, which operates on a wide road network having a city centre, a peripheral urban area and a peri-urban rural zone. A simulation method is proposed to obtain real-life scenarios in order to test the method and its indicators. The performance of each indicator has been evaluated in an experimental context to produce realistic test cases, using a trip planning tool and a demand generator. First, the behaviour of the indicators is analysed with regard to the time windows width planned for the service. Then, their ability in estimating the total transportation cost to satisfy all the requests, under different time period profiles, is shown. The results confirm the ability of the set of indicators to predict with a good approximation the transportation costs and therefore to be used in supporting the service quality planning decision