ИССЛЕДОВАНИЕ НЕКОТОРЫХ КЛАССИЧЕСКИХ АЛГОРИТМОВ ЗАДАЧИ МАРШРУТИЗАЦИИ ТРАНСПОРТА

The article is devoted to the study of some classical algorithms for transport routing problems. The article describes the existing classical transport routing algorithms, such as the Clark-Wright algorithm and its extended algorithm. The main minus of Clarke-Wright’s algorithm has been revealed, which consists in the efficiency of its operation decreases as it approaches the end of the calculations, while at the beginning of the work, the solutions are relatively successful. To improve the performance of the Clark-Wright algorithm, three approaches have been proposed in its extended algorithm. Also were explored the algorithms of Mole-Jameson and Christofides, Mingozzi and Tossa, which can be used for tasks with an unspecified in advance number of vehicles, are investigated. The algorithm of the Notes, which is used for the initial processing of the problems of ZMT, is proposed. Classical improvement algorithms for MMT are investigated, in which either a single route at a time or several routes are processed. The above algorithms give more interesting results than their predecessors, and are considered optimal in terms of the use of certain resources.The article is devoted to the study of some classical algorithms for transport routing problems. The article describes the existing classical transport routing algorithms, such as the Clark-Wright algorithm and its extended algorithm. The main minus of Clarke-Wright’s algorithm has been revealed, which consists in the efficiency of its operation decreases as it approaches the end of the calculations, while at the beginning of the work, the solutions are relatively successful. To improve the performance of the Clark-Wright algorithm, three approaches have been proposed in its extended algorithm. Also were explored the algorithms of Mole-Jameson and Christofides, Mingozzi and Tossa, which can be used for tasks with an unspecified in advance number of vehicles, are investigated. The algorithm of the Notes, which is used for the initial processing of the problems of ZMT, is proposed. Classical improvement algorithms for MMT are investigated, in which either a single route at a time or several routes are processed. The above algorithms give more interesting results than their predecessors, and are considered optimal in terms of the use of certain resources

Arbeitsbericht Nr. 2006-05, November 2006

Ilmenauer Beiträge zur Wirtschaftsinformatik Nr. 2006-05 / Technische Universität Ilmenau, Fakultät für Wirtschaftswissenschaften, Institut für Wirtschaftsinformatik, ISSN 1861-9223 ISBN 3-938940-06-

Driver helper dispatching problems: Three essays

The driver helper dispatching problems (DHDPs) have received scant research attention in past literature. In this three essay format dissertation, we proposed two ideas: 1) minimizing of the total cost as the new objective function to replace minimizing the total distance cost that is mostly used in past traveling salesman problem (TSP) and vehicle routing problem (VRP) algorithms and 2) dispatching vehicle either with a helper or not as part of the routing decision. The first study shows that simply separating a single with-helper route into two different types of sub-routes can significantly reduce total costs. It also proposes a new dependent driver helper (DDH) model to boost the utilization rate of the helpers to higher levels. In the second study, a new hybrid driver helper (HDH) model is proposed to solve DHDPs. The proposed HDH model provides the flexibility to relax the constraints that a helper can only work at one predetermined location in current-practice independent driver helper (IDH) model and that a helper always travels with the vehicle in the current-practice DDH model. We conducted a series of full-factorial experiments to prove that the proposed HDH model performs better than both two current solutions in terms of savings in both cost and time. The last study proposes a mathematical model to solve the VRPTW version of DHDPs and conducts a series of full factorial computational experiments. The results show that the proposed model can achieve more cost savings while reducing a similar level of dispatched vehicles as the current-practice DDH solution. All these three studies also investigate the conditions under which the proposed models would work most, or least, effectively

Driver helper dispatching problems: Three essays

The driver helper dispatching problems (DHDPs) have received scant research attention in past literature. In this three essay format dissertation, we proposed two ideas: 1) minimizing of the total cost as the new objective function to replace minimizing the total distance cost that is mostly used in past traveling salesman problem (TSP) and vehicle routing problem (VRP) algorithms and 2) dispatching vehicle either with a helper or not as part of the routing decision. The first study shows that simply separating a single with-helper route into two different types of sub-routes can significantly reduce total costs. It also proposes a new dependent driver helper (DDH) model to boost the utilization rate of the helpers to higher levels. In the second study, a new hybrid driver helper (HDH) model is proposed to solve DHDPs. The proposed HDH model provides the flexibility to relax the constraints that a helper can only work at one predetermined location in current-practice independent driver helper (IDH) model and that a helper always travels with the vehicle in the current-practice DDH model. We conducted a series of full-factorial experiments to prove that the proposed HDH model performs better than both two current solutions in terms of savings in both cost and time. The last study proposes a mathematical model to solve the VRPTW version of DHDPs and conducts a series of full factorial computational experiments. The results show that the proposed model can achieve more cost savings while reducing a similar level of dispatched vehicles as the current-practice DDH solution. All these three studies also investigate the conditions under which the proposed models would work most, or least, effectively

On the inventory routing problem with stationary stochastic demand rate

One of the most significant paradigm shifts of present business management is that individual businesses no longer participate as solely independent entities, but rather as supply chains (Lambert and Cooper, 2000). Therefore, the management of multiple relationships across the supply chain such as flow of materials, information, and finances is being referred to as supply chain management (SCM). SCM involves coordinating and integrating these multiple relationships within and among companies, so that it can improve the global performance of the supply chain. In this dissertation, we discuss the issue of integrating the two processes in the supply chain related, respectively, to inventory management and routing policies. The challenging problem of coordinating the inventory management and transportation planning decisions in the same time, is known as the inventory routing problem (IRP). The IRP is one of the challenging optimization problems in logis-tics and supply chain management. It aims at optimally integrating inventory control and vehicle routing operations in a supply network. In general, IRP arises as an underlying optimization problem in situations involving simultaneous optimization of inventory and distribution decisions. Its main goal is to determine an optimal distribution policy, consisting of a set of vehicle routes, delivery quantities and delivery times that minimizes the total inventory holding and transportation costs. This is a typical logistical optimization problem that arises in supply chains implementing a vendor managed inventory (VMI) policy. VMI is an agreement between a supplier and his regular retailers according to which retailers agree to the alternative that the supplier decides the timing and size of the deliveries. This agreement grants the supplier the full authority to manage inventories at his retailers'. This allows the supplier to act proactively and take responsibility for the inventory management of his regular retailers, instead of reacting to the orders placed by these retailers. In practice, implementing policies such as VMI has proven to considerably improve the overall performance of the supply network, see for example Lee and Seungjin (2008), Andersson et al. (2010) and Coelho et al. (2014). This dissertation focuses mainly on the single-warehouse, multiple-retailer (SWMR) system, in which a supplier serves a set of retailers from a single warehouse. In the first situation, we assume that all retailers face a deterministic, constant demand rate and in the second condition, we assume that all retailers consume the product at a stochastic stationary rate. The primary objective is to decide when and how many units to be delivered from the supplier to the warehouse and from the warehouse to retailers so as to minimize total transportation and inventory holding costs over the finite horizon without any shortages

OPTIMIZATION OF RAILWAY TRANSPORTATION HAZMATS AND REGULAR COMMODITIES

Transportation of dangerous goods has been receiving more attention in the realm of academic and scientific research during the last few decades as countries have been increasingly becoming industrialized throughout the world, thereby making Hazmats an integral part of our life style. However, the number of scholarly articles in this field is not as many as those of other areas in SCM. Considering the low-probability-and-high-consequence (LPHC) essence of transportation of Hazmats, on the one hand, and immense volume of shipments accounting for more than hundred tons in North America and Europe, on the other, we can safely state that the number of scholarly articles and dissertations have not been proportional to the significance of the subject of interest. On this ground, we conducted our research to contribute towards further developing the domain of Hazmats transportation, and sustainable supply chain management (SSCM), in general terms. Transportation of Hazmats, from logistical standpoint, may include all modes of transport via air, marine, road and rail, as well as intermodal transportation systems. Although road shipment is predominant in most of the literature, railway transportation of Hazmats has proven to be a potentially significant means of transporting dangerous goods with respect to both economies of scale and risk of transportation; these factors, have not just given rise to more thoroughly investigation of intermodal transportation of Hazmats using road and rail networks, but has encouraged the competition between rail and road companies which may indeed have some inherent advantages compared to the other medium due to their infrastructural and technological backgrounds. Truck shipment has ostensibly proven to be providing more flexibility; trains, per contra, provide more reliability in terms of transport risk for conveying Hazmats in bulks. In this thesis, in consonance with the aforementioned motivation, we provide an introduction into the hazardous commodities shipment through rail network in the first chapter of the thesis. Providing relevant statistics on the volume of Hazmat goods, number of accidents, rate of incidents, and rate of fatalities and injuries due to the incidents involving Hazmats, will shed light onto the significance of the topic under study. As well, we review the most pertinent articles while putting more emphasis on the state-of-the-art papers, in chapter two. Following the discussion in chapter 3 and looking at the problem from carrier company’s perspective, a mixed integer quadratically constraint problem (MIQCP) is developed which seeks for the minimization of transportation cost under a set of constraints including those associating with Hazmats. Due to the complexity of the problem, the risk function has been piecewise linearized using a set of auxiliary variables, thereby resulting in an MIP problem. Further, considering the interests of both carrier companies and regulatory agencies, which are minimization of cost and risk, respectively, a multiobjective MINLP model is developed, which has been reduced to an MILP through piecewise linearization of the risk term in the objective function. For both single-objective and multiobjective formulations, model variants with bifurcated and nonbifurcated flows have been presented. Then, in chapter 4, we carry out experiments considering two main cases where the first case presents smaller instances of the problem and the second case focuses on a larger instance of the problem. Eventually, in chapter five, we conclude the dissertation with a summary of the overall discussion as well as presenting some comments on avenues of future work

Decision making under uncertainty in routing problems for reverse logistics

In der vorliegenden Dissertationsschrift befassen wir uns mit einer Erweiterung des Tourenplanungsproblems mit simultaner Auslieferung und Abholung. Es wird angenommen, dass Auslieferungsaufträge im Voraus bekannt sind, Abholungen jedoch stochastisch sind und erst bekannt werden, nachdem eine a priori Route bestimmt wurde. Dies kann dazu führen, unzureichende Fahrzeugkapazität zu haben, um den realisierten Abholbedarf eines Verbrauchers einzusammeln. Diese Situation wird als Ausfall bezeichnet. Als Korrekturmaßnahme wird eine zusätzliche Route berechnet, um die Abholungsmengen an den Ausfall-Punkten einzusammeln. Das Ziel ist, die zurückgelegte Strecke der ersten Stufe mit bekannten Auslieferungsaufträgen, sowie die erwartete zusätzliche Strecke der Korrekturroute zu minimieren. Wir beschränken uns auf den Fall nur ein Fahrzeug zur Verfügung zu haben und präsentieren ein zweistufiges stochastisches Modell mit Korrekturmaßnahmen, sowie einen exakten Algorithmus, um dieses zu lösen. Der vorgeschlagene Algorithmus basiert auf einer Anpassung des Integer L-Shaped Verfahrens für stochastische Tourenplanungsprobleme. Risikoneutrale und risikoscheue Routing-Entscheidungen werden untersucht und verglichen.We consider a stochastic extension of the vehicle routing problem with simultaneous delivery and pickup. While delivery amounts are assumed to be fixed and known in advance, pickup amounts are stochastic and revealed only after the determination of an a priori route. This may lead to arriving at a customer with insufficient capacity to collect the realized pickup demand. Such a situation is referred to as a failure. As corrective action an additional route is computed to collect the pickup amounts which are left at the failure points. The objective is to minimize the distance traveled in the first-stage with known delivery quantities plus the expected distance traveled along the corrective route. For the single vehicle case, we present a two-stage stochastic programming model with recourse as well as an exact algorithm to solve it. The proposed algorithm is based on an extension of the Integer L-Shaped method adapted for stochastic vehicle routing problems. Risk neutral and risk averse routing decisions are examined and compared

Planification de trajectoires pour une flotte d'UAVs.

RÉSUMÉ Les drones, qu’on appelle aussi UAVs (Unmanned Aerial Vehicles) ou RPV (Remotely Piloted Vehicles), sont des avions sans pilote. Ils sont adoptés par des organisations militaires et civiles pour accomplir des tâches difficiles dans des environnements très hostiles, sans aucun risque pour l’humain. Comme toute nation développée, le Canada a recours à ces avions pour ses missions militaires de maintien de la paix et pour des missions civiles telles que la surveillance du littoral, la surveillance des grands territoires et pour l’aide lors d’opérations de sauvetage. L’utilisation des UAVs est très diverse, que ce soit pour des opérations militaires ou civiles, et l’engouement pour ces engins est de plus en plus grand dans les pays industrialisés. Les progrès réalisés dans les technologies de contrôle, de détection et de calcul ont permis à ces véhicules de réaliser des missions indépendantes du contrôle direct de l'opérateur. L’itinéraire peut être planifié à l'avance de la mission et le drone peut alors l’exécuter automatiquement. La planification de cet itinéraire efficace implique la détermination de solutions permettant d’atteindre un certain but fixé, comme par exemple éviter que le drone soit détecté par les radars au cours de son itinéraire, ou trouver l'itinéraire le plus court en terme de temps de déplacement, ou encore la minimisation du coût de la mission.--------- ABSTRACT UAVs (Unmanned Aerial Vehicles) or RPV (Remotely Piloted Vehicles), are planes without pilots. They were adopted by military and civilian organizations to accomplish difficult tasks over hostile environments and without risk for humans. Like any other developed nation, Canada has used the UAVs for its military missions such as peacekeeping and for civilian missions such as coastal monitoring, surveillance of large areas and rescue operations. The applications of UAVs are very diverse, ranging from surveillance operations to combat operations through rescues. Advances in monitoring technologies, detection and computing have allowed these vehicles to perform missions without the direct control of the operator. The itinerary can be planned in advance and the UAVs can then run automatically. Planning efficient routes involves determining a specific solution with a precise objective like avoiding radar detection of the UAVs, finding the shortest path in terms of time, or minimizing the cost of the mission