Doroteo Verastegui Rayo
@uclm.es
Profesor del Departamento de Matemáticas de la Escuela de Ingeniería Minera e Industrial de Almadén
Universidad de Castilla La Mancha
Scopus Publications
Scholar Citations
Scholar h-index
Scholar i10-index
Scopus Publications
C. Fúnez Guerra, L. Reyes-Bozo, E. Vyhmeister, M. Jaén Caparrós, J.L. Salazar, A. Godoy-Faúndez, C. Clemente-Jul, and D. Verastegui-Rayo
Elsevier BV
Abstract The processes and logistics of the mining industry have continually undergone transformations in order to deal with rigorous regulations, economic considerations, safety and the social burden regarding environmental conditions (i.e. every sustainability pillar). In underground mines, the use of diesel-powered machinery has been increased in the past decades. The combustion of diesel fuel produces a great quantity of pollutants (i.e. gas emissions, particulate matter, etc.). Thus, a constant ventilation is required to satisfy the regulations on health and safety of miners. One of the innovative transformations that underground mining processes have adopted is the use of electrical Load Haul Dumps (LHDs) to reduce the in-mine emissions and the ventilation burden and to improve in-mine working conditions, among other benefits. Electric mobile LHDs could be further improved by replacing battery-based energy supplies with hydrogen fuel cells. The present work focuses on the techno-economic assessment of modifying electrical LHDs by incorporating different processes and equipment (i.e. fuel cell stacks, storage tanks, DC/DC converters). The base case considers the modification of the whole mining fleet of diesel-based LHDs. As a result, a positive Net Present Value (for the project time span under consideration) and a payback period of 7.78 years were observed. The sensitivity analysis showed that considerable modifications of the current states of diesel price are required so that modifications are not feasible (diesel prices of 0.53 €/l). A tight electricity cost of 70 €/MWh was obtained as a breaking point (considerably safe for several industrial conditions).
CARLOS FUNEZ GUERRA, LOURDES RODRIGUEZ MAYOR, RICARDO GARCIA RODENAS, DOROTEO VERASTEGUI RAYO, EUSEBIO ANGULO, CARMEN CLEMENTE JUL, and LORENZO REYES BOZA
Publicaciones DYNA
El uso de vehiculos de combustibles alternativos (AFV), como los vehiculos de hidrogeno (pilas de combustible) (FCV), para reemplazar a los vehiculos impulsados por motores de combustion interna, son una clara alternativa del transporte por carretera que puede proporcionar, a largo plazo, seguridad en el suministro de energia, reduccion de las emisiones de gases de efecto invernadero y mejora de la calidad del aire en las ciudades. Para garantizar la penetracion en el mercado de estos vehiculos ecologicos, se deben abordar seis aspectos fundamentales: (a) precio de compra, (b) costes de funcionamiento, (c) disponibilidad de estaciones de repostaje, (d) autonomia de los vehiculos, (e) tiempo de repostaje y (f) emisiones de CO2 por kilometro. Con los modelos de localizacion se pretende acelerar la penetracion de los FCV en el mercado, tomando decisiones eficientes sobre el diseno de la infraestructura. Una infraestructura adecuada (oferta) generara la demanda de estos vehiculos. Sin embargo, para que la infraestructura sea economicamente viable debe de existir ya un nivel adecuado de demanda. En este trabajo, describimos una parte del modelo binivel que simula el comportamiento de los usuarios de los vehiculos de H2. Utilizamos un modelo de eleccion discreta para representar como los usuarios adquieren los FCV durante el periodo en estudio. El modelo logit anidado jerarquico, elegido para este estudio, ha sido ampliamente utilizado en el campo del transporte. En el nivel superior del proceso de elegir un FCV, un usuario elige comprar un vehiculo convencional (alternativa b) o un AFV (alternativa a). En el nivel inferior, los usuarios de AFV eligen el tipo de combustible alternativo. Con el modelo logit anidado, es posible realizar un analisis de sensibilidad que permita observar como afecta cada uno de los atributos a la utilidad de cada tipo de vehiculo y, por tanto, a su venta. Palabras clave: logit anidado, vehiculos de pila de combustible, estaciones de repostaje, comportamiento, vehiculos convencionales
C. Fúnez Guerra, Ricardo García-Ródenas, E. Angulo Sánchez-Herrera, Doroteo Verastegui Rayo, and C. Clemente-Jul
Elsevier BV
Ricardo García-Ródenas and Doroteo Verastegui-Rayo
Informa UK Limited
The network calibration problem (NCP) consists of adjusting (or estimating) the parameters of the link travel-time functions in a congested traffic network via the use of traffic link counts and equilibrium costs in a set of origin–destination demand pairs. In this article, a mathematical program with equilibrium constraints (MPEC) is proposed to model this problem. The proposed model is called NCP(ρ) and supposes that the available information has been obtained in several different periods (each period is defined by a single origin–destination demand matrix). The existence of the solutions to the stated NCP(ρ) under weak conditions in the link travel-time functions is established, and a sensitivity analysis of these solutions is carried out. A column generation algorithm (CGA) is proposed to solve the NCP(ρ) model, using sensitivity analysis to prove that this algorithm converges to a local optimum of the MPEC problem. Finally, the special case of estimating the link travel-time functions in additive models when information is only available for a single period is analysed in a numerical study. In this case the NCP(ρ) model is overspecified, that is, it has an infinite number of solutions. For this reason we propose, as an alternative, estimating the congestion costs ψ in a subset of links, rather than estimating the parameterisation of the link travel-time functions ρ. This special case has been named the NCP(ψ) model. The numerical study has been carried out in small and medium-sized networks, with the objective of studying both the proposed MPEC models and the computational aspects of the CGA.
Ricardo García-Ródenas and Doroteo Verastegui-Rayo
Elsevier BV
Abstract The general problem of estimating origin–destination (O–D) matrices in congested traffic networks is formulated as a mathematical programme with equilibrium constraints, referred to as the demand adjustment problem (DAP). This approach integrates the O–D matrix estimation and the network equilibrium assignment into one process. In this paper, a column generation algorithm for the DAP is presented. This algorithm iteratively solves a deterministic user equilibrium model for a given O–D matrix and a DAP restricted to the previously generated paths, whose solution generates a new O–D trip matrix estimation. The restricted DAP is formulated via a single level optimization problem. The convergence on local minimum of the proposed algorithm requires only the continuity of the link travel cost functions and the gauges used in the definition of the DAP. In order to analyze the convergence and performance of the proposed algorithm, various numerical tests were carried out on small scale problems.
Ricardo García-Ródenas, María Luz López-García, Alejandro Niño-Arbelaez, and Doroteo Verastegui-Rayo
Elsevier BV
Abstract The continuous dynamic network loading problem (CDNLP) aims to compute link travel times and path travel times on a congested network, given time-dependent path flow rates for a given time period. A crucial element of CDNLP is a model of the link performance. Two main modeling frameworks have been used in link loading models: The so-called whole-link travel time (WTT) models and the kinematic wave model of Lighthill–Whitham–Richards (LWR) for traffic flow. In this paper, we reformulate a well-known whole-link model in which the link travel time, for traffic entering a time t, is a function of the number of vehicles on link. This formulation does not require the satisfying of the FIFO (first in, first out) condition. An extension of the basic WTT model is proposed in order to take explicitly into account the maximum number of vehicles that the link can accommodate (occupancy constraint). A solution scheme for the proposed WTT model is derived. Several numerical examples are given to illustrate that the FIFO condition is not respected for the WTT model and to compare the travel time predictions effected by LWR and WTT models.