In this paper, a variant of the orienteering problem in which the travel and service times are stochastic, is examined. Given a set of potential customers, a subset of them has to be selected to be serviced by the end of the day. Every time a delivery to a selected customer is fulfilled before the end of the day, a reward is received, otherwise, if the delivery is not completed, a penalty is in...

This paper studies a vehicle routing problem with time-dependent and stochastic travel times. In our problem setting, customers have soft time windows. A mathematical model is used in which both efficiency for service as well as reliability for customers are taken into account. Depending on whether service times are included or not, we consider two versions of this problem. Two metaheuristics a...

We consider a stochastic version of a dynamic resource allocation problem. In this setting, reusable resources must be assigned to demands that arise randomly over time. Both resources and demands are heterogeneous, and satisfying a demand generally will change the attributes of a resource. These problems arise in eet management, personnel training and assignment, and the remnant inventory prob...

In the context of public transportation system, improving the service quality and robustness through minimizing the average passengers waiting time is a real challenge. This study provides robust stochastic programming models for train timetabling problem in urban rail transit systems. The objective is minimization of the weighted summation of the expected cost of passenger waiting time, its va...

This study presents a time-dependent stochastic user equilibrium (TDSUE) traffic assignment model within a probit-based path choice decision framework that explicitly takes into account temporal and spatial correlation (traveler interactions) in travel disutilities across a set of paths. The TDSUE problem, which aims to find time-dependent SUE path flows, is formulated as a Fixed Point (FP) pro...

In this paper, we present a stochastic model for the dynamic fleet management problem with random travel times. Our approach decomposes the problem into time-staged subproblems by formulating it as a dynamic program and uses approximations of the value function. In order to deal with random travel times, the state variable of our dynamic program includes all individual decisions over a relevant...

This paper studies a vehicle routing problem with soft time windows and stochastic travel times. A model is developed that considers both transportation costs (total distance traveled, number of vehicles used and drivers’ total expected overtime) and service costs (early and late arrivals). We propose a Tabu Search method to solve this model. An initialization algorithm is developed to construc...

Transportation is an essential driver of the supply chain; directly impacts both the responsiveness and efficiency therein. The decision of route selection based on the optimal travel time reduces the product delivery time and cost; enhancing customer satisfaction. This paper presents a case study identifying the optimal routes in a network consisting of 81 alternatives. Various sample data wer...

Classical models of product market competition maintain that firms maximize their profits regardless of their financial condition. Yet over the last two decades a growing theoretical literature has examined whether a firm’s capital structure impacts competition in the market for the firm’s products. In this paper we ask whether a firm operating under bankruptcy protection significantly reshapes...