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- Basso, Rafael, 1979, et al.
(författare)
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Electric vehicle routing problem – a nested two level approach
- 2017
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Ingår i: Proceedings of Swedish transportation research conference Stockholm 17-18 October 2017.
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Konferensbidrag (refereegranskat)abstract
- Some of the main constraints of electric vehicles are related to their battery, in terms of energy capacity, time to recharge, weight and cost. One of the most important consequences is a limitation in driving range, which especially impacts commercial vehicles. Therefore in order to plan routes for this kind of vehicle, it is necessary to precisely estimate the energy required to drive and plan for charging whenever needed. This paper introduces the Two-stage Electric Vehicle Routing Problem (2sEVRP) that considers detailed information about the paths when estimating energy consumption and planning the routes. First, a method to calculate cost parameters for the road network is outlined including topography, speed, powertrain efficiency and the effect of acceleration and braking at traffic lights and intersections. Second, an integrated two-stage approach is described, which finds the best paths between pairs of nodes and then finds the best routes including battery and time-window constraints. Energy consumption is used as cost function including payload and auxiliary systems. The road cost parameters are aggregated to generate the path cost parameters that are used in the routing problem. In this way all the details of the paths are taken into account when computing energy demand for the routes. Last, numerical experiments were conducted with the road network from Gothenburg-Sweden and high-fidelity vehicle model simulations, focusing on trucks for urban distribution of goods. The results indicate that time and energy estimation are signeficantly more precise than existing methods. Consequently it is possible to generate important savings and be sure that the planned routes are feasible.
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| 2. |
- Sarmiento Nova, Silvia J., et al.
(författare)
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Response Surface Method strategies coupled with NLFEA for structural reliability analysis of prestressed bridges
- 2021
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Ingår i: IABSE Congress Ghent 2021. - Zurich, Switzerland : International Association for Bridge and Structural Engineering (IABSE). ; , s. 1813-1822
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Konferensbidrag (refereegranskat)abstract
- The Response Surface Method (RSM) has become an essential tool to solve structural reliability problems due to its accuracy, efficacy, and facility for coupling with Nonlinear Finite Element Analysis (NLFEA). In this paper, some strategies to improve the RSM efficacy without compromising its accuracy are tested. Initially, each strategy is implemented to assess the safety level of a highly nonlinear explicit limit state function. The strategy with the best results is then identified and used to carry out a reliability analysis of a prestressed concrete bridge, considering the nonlinear material behavior through NLFEA simulation. The calculated value of ? is compared with the target value established in Eurocode for ULS. The results showed how RSM can be a practical methodology and how the improvements presented can reduce the computational cost of a traditional RSM giving a good alternative to simulation methods such as Monte Carlo.
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