Addressing nodal constraints on the capacity of railways

As demand for passenger and freight transport on Britain’s railways increases, providing additional capacity and making the best use of the existing infrastructure are priorities for the industry. Since the stations and junctions forming the nodes of the railway network tend to form the constraints on route and network capacity, improved understanding of their operation and capacity characteristics is particularly important. This paper describes research undertaken to improve the understanding of nodal capacity and capacity utilisation, and to route and schedule trains more efficiently through nodes, thus improving service quality and/or releasing capacity for additional train service

Power counting and renormalization group invariance in the subtracted kernel method for the two-nucleon system

We apply the subtracted kernel method (SKM), a renormalization approach based on recursive multiple subtractions performed in the kernel of the scattering equation, to the chiral nucleon-nucleon (NN) interactions up to next-to-next-to-leading-order (NNLO). We evaluate the phase-shifts in the 1S0 channel at each order in Weinberg's power counting scheme and in a modified power counting scheme which yields a systematic power-law improvement. We also explicitly demonstrate that the SKM procedure is renormalization group invariant under the change of the subtraction scale through a non-relativistic Callan-Symanzik flow equation for the evolution of the renormalized NN interactions.Comment: Accepted for publication in Journal of Physics G: Nuclear and Particle Physic

Study on the Algorithm for Train Operation Adjustment Based on Ordinal Optimization

It is a crucial and difficult problem in railway transportation dispatch mechanism to automatically compile train operation adjustment (TOA) plan with computer to ensure safe, fast, and punctual running of trains. Based on the proposed model of TOA under the conditions of railway network (RN), we take minimum travel time of train as objective function of optimization, and after fast preliminary evaluation calculation on it, we introduce the theory and method of ordinal optimization (OO) to solve it. This paper discusses in detail the implementation steps of OO algorithm. A practical calculation example of Datong-Qinhuangdao (hereinafter referred to as Da-Qin) heavy haul railway is performed with the proposed algorithm to prove that OO can ensure getting good enough solution with high probability. Particularly, for complex optimization problems with large amount of calculation, OO can greatly increase computational efficiency, and it can save at least one order of magnitude of calculation amount than general heuristic algorithm. Thus, the proposed algorithm can well satisfy the requirements in engineering

High-speed railway timetable rescheduling method : a bi-level integrated programming approach

China’s railway has experienced a large-scale development in the recent years. Making up for delay time considering the energy efficiency when the train is delayed, which can satisfy the travel demand for passengers and save rail energy costs at the same time, will become the focus of future research on the railway. A bi-level programming optimization model is proposed in this paper. In the upper layer, the high-speed railway timetable is adjusted under unexpected interferences, and then the energy saving is optimized in the lower layer. A real-world case study is presented to illustrate the validity of the model and algorithm