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Fan, Q. (author), van Essen, J.T. (author), Correia, Gonçalo (author)Ride-hailing companies will face the emergence and gradual expansion of AVs-only zones in urban areas where only automated vehicles (AVs) are allowed to circulate. When owning a mixed fleet (automated and conventional taxis), a ride-hailing company has to determine the optimal fleet size as a function of the gradually expanding coverage of...journal article 2024
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Fan, Q. (author), van Essen, J.T. (author), Correia, Gonçalo (author)Shared automated vehicles (SAV) are expected to benefit the sustainable development of urban regions and alleviate the negative impacts brought by the increasing number of private cars. In this paper, we envision a future scenario where non-pooled SAVs replace private cars and provide public on-demand mobility services to satisfy the mobility...journal article 2023
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van der Beek, T. (author), Souravlias, D. (author), van Essen, J.T. (author), Pruyn, J.F.J. (author), Aardal, K.I. (author)The resource constrained project scheduling problem with a flexible project structure and consumption and production of resources, involves making a selection of activities and scheduling these activities in order to minimize the makespan, subject to precedence and resource constraints. Since finding a feasible selection of activities is NP...journal article 2023
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Prencipe, Luigi Pio (author), van Essen, J.T. (author), Caggiani, Leonardo (author), Ottomanelli, Michele (author), Correia, Gonçalo (author)Electric car-sharing systems have attracted large attention in recent years as a new business model for achieving both economic and environmental benefits in urban areas. Among different types, the one considered in this paper is the so-called one-way car-sharing system whereby a user can begin and end a trip at any station of the system. At...journal article 2022
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Fan, Q. (author), van Essen, J.T. (author), Correia, Gonçalo (author)The era of intelligent transportation with automated vehicles (AVs) is coming. Nonetheless, the transition to this system will be a gradual process. On the one hand, some zones in the city may be dedicated to AVs with a fully intelligent traffic management system geared toward high performance. On the other hand, automated and conventional...journal article 2022
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Jamshidi, Helia (author), Correia, Gonçalo (author), van Essen, J.T. (author), Nökel, Klaus (author)Short driving range, limited chargers, and long charging times challenge the profitability of electric taxi operations. In this paper, a charging algorithm is developed to accompany a taxi service with online trip requests, which uses a private charging infrastructure for both slow and fast charging. The vehicle charging curves are assumed to be...journal article 2021
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Pierotti, J. (author), van Essen, J.T. (author)Automated vehicles are becoming a reality. Expectations are that AVs will ultimately transform personal mobility from privately owned assets to on-demand services. This transformation will enhance the possibility of sharing trips, leading to shared AVs (SAVs). The preeminent aim of this paper is to lay foundations for fast and efficient...journal article 2021
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Pierotti, J. (author), Kronmueller, Maximilian (author), Alonso-Mora, J. (author), van Essen, J.T. (author), Böhmer, J.W. (author)Combinatorial optimization (CO) problems are at the heart of both practical and theoretical research. Due to their complexity, many problems cannot be solved via exact methods in reasonable time; hence, we resort to heuristic solution methods. In recent years, machine learning (ML) has brought immense benefits in many research areas,...book chapter 2021
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Pierotti, J. (author), Ferretti, Lorenzo (author), Pozzi, Laura (author), van Essen, J.T. (author)Metaheuristics have been widely used to solve NP-hard problems, with excellent results. Among all NP-hard problems, the Travelling Salesman Problem (TSP) is potentially the most studied one. In this work, a variation of the TSP is considered; the main differences being, edges may have positive or negative costs and the objective is to return...conference paper 2021
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Foster, Travis (author), Vanberkel, Peter (author), Venkatadri, Uday (author), van Essen, J.T. (author)Emergency Medical Services organizations are responsible for providing paramedic crews, vehicles and equipment to transfer patients from one location to another in emergency and non-emergency settings. They must solve difficult scheduling and assignment problems to ensure on-time arrival of patients and the efficient use of health care...conference paper 2020
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Schneider, A.J. Thomas (author), van Essen, J.T. (author), Carlier, Mijke (author), Hans, Erwin W. (author)Surgery groups are clustered surgery procedure types that share comparable characteristics (e.g. expected duration). Scheduling OR blocks leaves many options for operational surgery scheduling and this increases the variation in usage of both the OR and downstream beds. Therefore, we schedule surgery groups to reduce the options for...journal article 2020
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van der Beek, T. (author), van Essen, J.T. (author), Pruyn, J.F.J. (author), Aardal, K.I. (author), Hopman, J.J. (author)The primary drivers for buying a ship from a certain yard are price, delivery time and quality. In order to decrease construction time and costs, shipbuilding companies are exploring the development of product-families to include family wide modularity and cross family standardization. Standardization is the use of identical components across...conference paper 2019
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van den Berg, P.L. (author), van Essen, J.T. (author)Many ambulance providers operate both advanced life support (ALS) and basic life support (BLS) ambulances. Typically, only an ALS ambulance can respond to an emergency call, whereas non-urgent patient transportation requests can be served by either an ALS or a BLS ambulance. The total capacity of BLS ambulances is usually not enough to...journal article 2019
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van Essen, J.T. (author), Correia, Gonçalo (author)The possibility of having driverless cars on the streets seems to be more real than ever. In this paper, we focus on developing exact methods that can determine the effects of privately owned automated vehicles (AVs) and how switching to those vehicles is going to change mobility in urban environments. The considered problem determines the...journal article 2019
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Røislien, Jo (author), van den Berg, Pieter L. (author), Lindner, Thomas (author), Zakariassen, Erik (author), Uleberg, Oddvar (author), Aardal, K.I. (author), van Essen, J.T. (author)Background: Helicopter emergency medical services are important in many health care systems. Norway has a nationwide physician manned air ambulance service servicing a country with large geographical variations in population density and incident frequencies. The aim of the study was to compare optimal air ambulance base locations using both...journal article 2018
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Dollevoet, Twan (author), van Essen, J.T. (author), Glorie, Kristiaan M. (author)In order to perform medical surgeries, hospitals keep large inventories of surgical instruments. These instruments need to be sterilized before each surgery. Typically the instruments are kept in trays. Multiple trays may be required for a single surgery, while a single tray may contain instruments that are required for multiple surgical...journal article 2018
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Bhulai, Sandjai (author), Li, P (author), van Essen, J.T. (author)Taxis are an essential component of the transportation system in most urban centers. The ability to optimize the efficiency of routing represents an opportunity to increase revenues for taxi drivers. The vacant taxis cruising on the roads are not only wasting fuel consumption, the time of a taxi driver, and create unnecessary carbon emissions...conference paper 2017
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Aringhieri, Roberto (author), Bruni, Mariaelena E. (author), Khodaparasti, Sara (author), van Essen, J.T. (author)One of the most important health care services is emergency medical service as it plays a vital role in saving people's lives and reducing the rate of mortality and morbidity. Over the last years, many review papers have discussed emergency medical services (EMS) location problems, however, only few review papers consider the full range of EMS...journal article 2017
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Phillipson, Frank (author), de Hoog, Suzanne (author), van Essen, J.T. (author)Most telecom operators have to plan the migration of their existing copper networks to full or hybrid fibre networks, to offer their clients the bandwidth they require. This paper<br/>proposes methods to optimise this migration path, heterogeneously per central office area, using geometric models as input. The methods result in a detailed...journal article 2017
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Røislien, Jo (author), van den Berg, P.L. (author), Lindner, Thomas (author), Zakariassen, Erik (author), Aardal, K.I. (author), van Essen, J.T. (author)Background Helicopter emergency medical services are an important part of many healthcare systems. Norway has a nationwide physician staffed air ambulance service with 12 bases servicing a country with large geographical variations in population density. The aim of the study was to estimate optimal air ambulance base locations. Methods We used...journal article 2016