This paper deals with the problem of recreating horizontal alignments of existing railway lines.The main objective is to propose a simple method for automatically obtaining optimized recreated alignments located as cl...This paper deals with the problem of recreating horizontal alignments of existing railway lines.The main objective is to propose a simple method for automatically obtaining optimized recreated alignments located as close as possible to an existing one.Based on a previously defined geometric model,two different constrained optimization problems are formulated.The first problem uses only the information provided by a set of points representing the track centerline while the second one also considers additional data about the existing alignment.The proposed methodology consists of a two-stage process in which both problems are solved consecutively using numerical techniques.The main results obtained applying this methodology are presented to show its performance and to prove its practical usefulness:an academic example used to compare with other methods,and a case study of a railway section located in Parga(Spain)in which the geometry of its horizontal alignment is successfully recovered.展开更多
In the present article we propose a Partial Integro-Differential Equation(PIDE)model to approximate a stochastic SIS compartmental model for viral infection spread.First,an appropriate set of reactions is considered,a...In the present article we propose a Partial Integro-Differential Equation(PIDE)model to approximate a stochastic SIS compartmental model for viral infection spread.First,an appropriate set of reactions is considered,and the corresponding Chemical Master Equation(CME)that describes the evolution of the reaction network as a stochastic process is posed.In this way,the inherent stochastic behaviour of the infection spread is incorporated in the modelling approach.More precisely,by considering that infection is propagated in bursts we obtain the PIDE model as the continuous counterpart to approximate the CME.In this way,the model takes into account that one infectious individual can be in contact with more than one susceptible person at a given time.Moreover,an appropriate semi-Lagrangian numerical method is proposed to efficiently solve the PIDE model.Numerical results and computational times for CME and PIDE models are compared and discussed.We also include a comparison of the main statistics of the PIDE model with the deterministic ODE model.Moreover,we obtain an analytical expression for the stationary solution of the proposed PIDE model,which also allows us to study the disease persistence.The methodology presented in this work is also applied to a real scenario as the COVID-19 pandemic.展开更多
基金founded by project TED2021129324B-I00 of the Ministerio de Ciencia e Innovación(Spain)and NextGenerationEU(European Union)the Collaboration Agreement between Consellería de Educación,Formación Profesional e Universidades(Xunta de Galicia,Spain)and Universidade de Santiago de Compostela(Spain)which regulates the Specialization Campus Campus Terra under Grant number 2022-PU014support given by Xunta de Galicia(Spain)by means of the research projects 2023 GPC GI-2084 ED431B2023/17 and GRC GI-1563-ED431C 2021/15,respectively.
文摘This paper deals with the problem of recreating horizontal alignments of existing railway lines.The main objective is to propose a simple method for automatically obtaining optimized recreated alignments located as close as possible to an existing one.Based on a previously defined geometric model,two different constrained optimization problems are formulated.The first problem uses only the information provided by a set of points representing the track centerline while the second one also considers additional data about the existing alignment.The proposed methodology consists of a two-stage process in which both problems are solved consecutively using numerical techniques.The main results obtained applying this methodology are presented to show its performance and to prove its practical usefulness:an academic example used to compare with other methods,and a case study of a railway section located in Parga(Spain)in which the geometry of its horizontal alignment is successfully recovered.
基金support from grant FJC2019-041397-I funded by MCIN/AEI/10.13039/501100011033MP and CV acknowledge funding from the Spanish Ministry of Science and Innovation(grant PID2022-141058OB-I00)+1 种基金from the Galician Government(grants ED431C 2022/047 and ED431G 2023/01,both including FEDER financial support)IOM acknowledges support from grant GAIN Opportunius Xunta de Galicia 2021.
文摘In the present article we propose a Partial Integro-Differential Equation(PIDE)model to approximate a stochastic SIS compartmental model for viral infection spread.First,an appropriate set of reactions is considered,and the corresponding Chemical Master Equation(CME)that describes the evolution of the reaction network as a stochastic process is posed.In this way,the inherent stochastic behaviour of the infection spread is incorporated in the modelling approach.More precisely,by considering that infection is propagated in bursts we obtain the PIDE model as the continuous counterpart to approximate the CME.In this way,the model takes into account that one infectious individual can be in contact with more than one susceptible person at a given time.Moreover,an appropriate semi-Lagrangian numerical method is proposed to efficiently solve the PIDE model.Numerical results and computational times for CME and PIDE models are compared and discussed.We also include a comparison of the main statistics of the PIDE model with the deterministic ODE model.Moreover,we obtain an analytical expression for the stationary solution of the proposed PIDE model,which also allows us to study the disease persistence.The methodology presented in this work is also applied to a real scenario as the COVID-19 pandemic.
