Artículos de revista DEIM - EIMS Aldizkari artikuluak

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D-optimal strain sensor placement for mechanical load estimation in the presence of nuisance loads and thermal strain
(Elsevier, 2024-12-08) Iriarte Goñi, Xabier; Bacaicoa Díaz, Julen; Aginaga García, Jokin; Plaza Puértolas, Aitor; Szczepanska-Álvarez, Anna; Ingeniería; Ingeniaritza; Estadística, Informática y Matemáticas; Estatistika, Informatika eta Matematika; Institute of Smart Cities - ISC; Gobierno de Navarra / Nafarroako Gobernua
The measurement of loads in circular cross-section geometries using strain gauges or other types of strain sensors is well-known in the field of mechanical engineering. Typical stress measurement configurations use 4 strain sensors strategically placed on the surface of the shaft and connected in the form of a complete Wheatstone bridge. Thus, 4 strain sensors are used to estimate each of the six load components to which a shaft may be subjected. Some typical configurations are designed to compensate for temperature effects, making them robust to temperature changes. Despite being used for decades, there is no record of any algorithm that serves to calculate these configurations, demonstrate that they are optimal or determine new configurations with other requirements. In this article, an algorithm is developed that allows calculating the optimal configurations of strain sensors to estimate one or several load components, compensating for the effect of other loads and temperature variations. This algorithm is based on the measurement of the strain of each gauge using Wheatstone quarter bridges and uses the same set of sensors for the estimation of various load components. The results are two-fold: on the one hand the traditional configurations are shown to be optimal and on the other hand a series of additional optimal configurations are obtained to estimate various sets of load components compensating for the influence of the rest. Additionally, a means of calculating the estimation variance of the loads of interest is provided.
Open Access
Application of the Sugeno integral in fuzzy rule-based classification
(Elsevier, 2024-09-27) Wieczynski, Jonata; Lucca, Giancarlo; Borges, Eduardo N.; Urío Larrea, Asier; López Molina, Carlos; Bustince Sola, Humberto; Pereira Dimuro, Graçaliz; Estadística, Informática y Matemáticas; Estatistika, Informatika eta Matematika; Universidad Pública de Navarra / Nafarroako Unibertsitate Publikoa
Fuzzy Rule-Based Classification System (FRBCS) is a well-known technique to deal with classification problems. Recent studies have considered the usage of the Choquet integral and its generalizations (e.g.: 𝐶𝑇 -integral, 𝐶𝐹 - Integral and 𝐶𝐶-integral) to enhance the performance of such systems. Such fuzzy integrals were applied to the Fuzzy Reasoning Method (FRM) to aggregate the fired fuzzy rules when classifying new data. However, the Sugeno integral, another well-known aggregation operator, obtained good results in other applications, such as brain–computer interfaces. These facts led to the present study, in which we consider the Sugeno integral in classification problems. That is, the Sugeno integral is applied in the FRM of a widely used FRBCS, and its performance is analyzed over 33 different datasets from the literature, also considering different fuzzy measures. To show the efficiency of this new approach, the results obtained are also compared with previous studies that involved the application of different aggregation functions. Finally, we perform a statistical analysis of the application.
Embargo
Robust boundary integral equations for the solution of elastic scattering problems via Helmholtz decompositions
(Elsevier, 2024-12-01) Turc, Catalin; Domínguez Baguena, Víctor; Estadística, Informática y Matemáticas; Estatistika, Informatika eta Matematika; Institute for Advanced Materials and Mathematics - INAMAT2
Helmholtz decompositions of the elastic fields open up new avenues for the solution of linear elastic scattering problems via boundary integral equations (BIE) (Dong et al. (2021) [20]). The main appeal of this approach is that the ensuing systems of BIE feature only integral operators associated with the Helmholtz equation. However, these BIE involve non standard boundary integral operators that do not result after the application of either the Dirichlet or the Neumann trace to Helmholtz single and double layer potentials. Rather, the Helmholtz decomposition approach leads to BIE formulations of elastic scattering problems with Neumann boundary conditions that involve boundary traces of the Hessians of Helmholtz layer potential. As a consequence, the classical combined field approach applied in the framework of the Helmholtz decompositions leads to BIE formulations which, although robust, are not of the second kind. Following the regularizing methodology introduced in Boubendir et al. (2015) [6] we design and analyze novel robust Helmholtz decomposition BIE for the solution of elastic scattering that are of the second kind in the case of smooth scatterers in two dimensions. We present a variety of numerical results based on Nyström discretizations that illustrate the good performance of the second kind regularized formulations in connections to iterative solvers.
Open Access
Proyecto Agroinc: prevención del impacto ambiental de incendios provocados por cosechadoras
(Interempresasmedia, 2022) Arazuri Garín, Silvia; Mangado Ederra, Jesús; López Maestresalas, Ainara; López Molina, Carlos; Angulo Muñoz, Blanca; Arnal Atarés, Pedro; Jarén Ceballos, Carmen; Ingeniería; Ingeniaritza; Estadística, Informática y Matemáticas; Estatistika, Informatika eta Matematika; Proyectos e Ingeniería Rural; Landa Ingeniaritza eta Proiektuak; Institute on Innovation and Sustainable Development in Food Chain - ISFOOD; Gobierno de Navarra / Nafarroako Gobernua
Las cosechadoras de cereales, por las condiciones ambientales en las que trabajan, alta temperatura y baja humedad, tanto ambiental como del producto que están cosechando, pueden provocar accidentalmente incendios durante la época de recolección. Los daños económicos y medioambientales que estos incendios suponen pueden ser muy importantes, ya que las condiciones de propagación del fuego son óptimas. Los principales objetivos de este proyecto han sido evaluar el impacto ambiental de los incendios producidos en Navarra en los últimos años y establecer una guía de buenas prácticas para su prevención.
Open Access
Optimizing freight delivery routes: the time-distance dilemma
(Elsevier, 2024-12-01) Alvarez Indave, Pablo; Serrano Hernández, Adrián; Lerga Valencia, Iosu; Faulín Fajardo, Javier; Estadística, Informática y Matemáticas; Estatistika, Informatika eta Matematika; Institute of Smart Cities - ISC; Universidad Pública de Navarra / Nafarroako Unibertsitate Publikoa, PJUPNA26-2022
Traditional approaches to optimizing freight delivery routes are based on minimizing a distance-based cost function. New approaches also use time as an objective function to minimize. However, the trade-off between time and distance is sometimes unclear. This paper presents a new approach to route optimization in which both time and distance are considered conjointly. For this purpose, the vehicle operating cost and the value of time have been used to translate time and distance into monetary units. By studying three different networks in Spain with varying levels of detail (the region of Catalonia, the city of Barcelona, and the Pamplona city center), the results show that minimizing both time and distance yield better results than the traditional approach, especially at a local level, where congestion effects are more relevant. These findings are helpful for logistics companies to optimize their operations, as well as for public authorities who could employ these models to make decisions and create policies on logistics.
Open Access
Automatic cross-validation in structured models: is it time to leave out leave-one-out?
(Elsevier, 2024-07-01) Adin Urtasun, Aritz; Krainski, Elias Teixeira; Lenzi, Amanda; Liu, Zhedong; Martínez-Minaya, Joaquín; Rue, Håvard; Estadística, Informática y Matemáticas; Estatistika, Informatika eta Matematika; Institute for Advanced Materials and Mathematics - INAMAT2; Universidad Pública de Navarra / Nafarroako Unibertistate Publikoa
Standard techniques such as leave-one-out cross-validation (LOOCV) might not be suitable for evaluating the predictive performance of models incorporating structured random effects. In such cases, the correlation between the training and test sets could have a notable impact on the model's prediction error. To overcome this issue, an automatic group construction procedure for leave-group-out cross validation (LGOCV) has recently emerged as a valuable tool for enhancing predictive performance measurement in structured models. The purpose of this paper is (i) to compare LOOCV and LGOCV within structured models, emphasizing model selection and predictive performance, and (ii) to provide real data applications in spatial statistics using complex structured models fitted with INLA, showcasing the utility of the automatic LGOCV method. First, we briefly review the key aspects of the recently proposed LGOCV method for automatic group construction in latent Gaussian models. We also demonstrate the effectiveness of this method for selecting the model with the highest predictive performance by simulating extrapolation tasks in both temporal and spatial data analyses. Finally, we provide insights into the effectiveness of the LGOCV method in modeling complex structured data, encompassing spatio-temporal multivariate count data, spatial compositional data, and spatio-temporal geospatial data.
Open Access
Including learning and forgetting processes in agent-based simulation models: application to police intervention in out-of-hospital cardiac arrests
(Elsevier, 2025-01-01) Baigorri Iguzquiaguirre, Miguel; Mallor Giménez, Fermín; Estadística, Informática y Matemáticas; Estatistika, Informatika eta Matematika; Institute of Smart Cities - ISC; Universidad Pública de Navarra / Nafarroako Unibertsitate Publikoa
Agent-based modeling has become increasingly popular in recent decades; however, defining agents that accurately depict human behavior remains a significant challenge. This paper contributes to the precise definition of human-like agents by incorporating learning and forgetting processes from the medical and psychological literature into agent-based simulation models. Specifically, the mathematical model for forgetting is developed to be compatible with empirical findings. The empirical evidence also supports the decomposition of the learning process into training sessions and the application of skills in real situations, as followed in this model. The resulting model of learning agents is then applied to study police intervention in out-of-hospital cardiac arrests. In numerous urban areas, there's ongoing discussion regarding the provision of defibrillators in patrol cars and CPR training for police officers. The results demonstrate that including learning and forgetting processes in simulation models provide a more accurate understanding of the benefits of using local police to attend cardiac arrests.
Open Access
Extension of Delaunay normalisation for arbitrary powers of the radial distance
(Elsevier, 2025-01-01) Lanchares Sánchez, Ernesto; Palacián Subiela, Jesús Francisco; Estadística, Informática y Matemáticas; Estatistika, Informatika eta Matematika; Institute for Advanced Materials and Mathematics - INAMAT2
In the framework of perturbed Keplerian systems we deal with the Delaunay normalisation of a wide class of perturbations such that the radial distance is raised to an arbitrary real number ϒ. The averaged function is expressed in terms of the Gauss hypergeometric function 2F1 whereas the associated generating function is the so called Appell hypergeometric function F1. The Gauss hypergeometric function related to the average depends on the eccentricity, e, whereas the Appell function depends additionally on the eccentric anomaly, E, and both special functions are properly defined and evaluated for all e Є [0,1) and E Є [-ꙥ ꙥ]. We analyse when the functions we determine can be extended to e=1. When the exponent of the radial distance is an integer, the usual values of the averaged and generating functions are recovered.
Open Access
Electromagnetic vibrational harvester based on U-shaped ferromagnetic cantilever: a novel two-magnet configuration
(Elsevier, 2024-09-07) Gandía Aguado, David; Garayo Urabayen, Eneko; Beato López, Juan Jesús; Royo Silvestre, Isaac; Cruz Blas, Carlos Aristóteles de la; Tainta Ausejo, Santiago; Gómez Polo, Cristina; Ciencias; Zientziak; Ingeniería Eléctrica, Electrónica y de Comunicación; Ingeniaritza Elektrikoa, Elektronikoa eta Telekomunikazio Ingeniaritza; Estadística, Informática y Matemáticas; Estatistika, Informatika eta Matematika; Institute for Advanced Materials and Mathematics - INAMAT2; Institute of Smart Cities - ISC
Electromagnetic vibrational harvesters are low-cost devices featuring high-power densities and robust structures, often used for capturing the energy of environmental vibrations (civil infrastructures, transportation, human motion, etc.,). Based on Faraday's law, energy generation relies on the modification of the magnetic field distribution within a magnetic element caused by mechanical vibrations inducing an electromotive force (EMF) in a pick-up coil. However, the practical implementation of this type of vibrational harvester is currently limited due to the reduced generated power under low-frequency vibrations. In this work, an electromagnetic vibrational harvester is experimentally characterized and analyzed employing magnetic circuit analysis. The harvester consists of a ferromagnetic U-shaped cantilever, a NdFeB magnet and a ferrite magnet used as ¿magnetic tip mass¿ to enhance the magnetic flux changes under vibrations of frequency < 100 Hz. For this configuration, an experimental voltage of ¿ 1.2 V peak-to-peak (open circuit) was obtained at a resonant frequency of 77 Hz, enabling the subsequent electronic rectification stage. Additionally, Finite Element Method (FEM) is used to explore different design possibilities including the modeling of complex geometries, mechanical properties and non-linear magnetic materials, enabling the tuning of the resonance frequency from 51 to 77 Hz, keeping constant the induced voltage.
Open Access
An efficient uniformly convergent method for multi-scaled two dimensional parabolic singularly perturbed systems of convection-diffusion type
(Elsevier, 2025-01-01) Clavero, Carmelo; Jorge Ulecia, Juan Carlos; Estadística, Informática y Matemáticas; Estatistika, Informatika eta Matematika; Institute of Smart Cities - ISC; Universidad Pública de Navarra / Nafarroako Unibertsitate Publikoa
In this work we solve initial-boundary value problems associated to coupled 2D parabolic singularly perturbed systems of convection-diffusion type. The analysis is focused on the cases where the diffusion parameters are small, distinct and also they may have different order of magnitude. In such cases, overlapping regular boundary layers appear at the outflow boundary of the spatial domain. The fully discrete scheme combines the classical upwind scheme defined on an appropriate Shishkin mesh to discretize the spatial variables, and the fractional implicit Euler method joins to a decomposition of the difference operator in directions and components to integrate in time. We prove that the resulting method is uniformly convergent of first order in time and of almost first order in space. Moreover, as only small tridiagonal linear systems must be solved to advance in time, the computational cost of our method is remarkably smaller than the corresponding ones to other implicit methods considered in the previous literature for the same type of problems. The numerical results, obtained for some test problems, corroborate in practice the good behavior and the advantages of the algorithm.
Open Access
Plant ammonium sensitivity is associated with external pH adaptation, repertoire of nitrogen transporters, and nitrogen requirement
(Oxford University Press, 2024-03-11) Rivero Marcos, Mikel; Lasa Larrea, Berta; Neves, Tomé; Zamarreño, Ángel M.; García Mina, José M.; García Olaverri, Carmen; Aparicio Tejo, Pedro María; Cruz, Cristina; Ariz Arnedo, Idoia; Ciencias; Zientziak; Estadística, Informática y Matemáticas; Estatistika, Informatika eta Matematika; Institute for Multidisciplinary Research in Applied Biology - IMAB; Institute for Advanced Research in Business and Economics - INARBE; Universidad Publica de Navarra / Nafarroako Unibertsitate Publikoa; Gobierno de Navarra / Nafarroako Gobernua
Modern crops exhibit diverse sensitivities to ammonium as the primary nitrogen source, influenced by environmental factors such as external pH and nutrient availability. Despite its significance, there is currently no systematic classification of plant species based on their ammonium sensitivity. We conducted a meta-analysis of 50 plant species and present a new classification method based on the comparison of fresh biomass obtained under ammonium and nitrate nutrition. The classification uses the natural logarithm of the biomass ratio as the size effect indicator of ammonium sensitivity. This numerical parameter is associated with critical factors for nitrogen demand and form preference, such as Ellenberg indicators and the repertoire of nitrogen transporters for ammonium and nitrate uptake. Finally, a comparative analysis of the developmental and metabolic responses, including hormonal balance, is conducted in two species with divergent ammonium sensitivity values in the classification. Results indicate that nitrate has a key role in counteracting ammonium toxicity in species with a higher abundance of genes encoding NRT2-type proteins and fewer of those encoding the AMT2-type proteins. Additionally, the study demonstrates the reliability of the phytohormone balance and methylglyoxal content as indicators for anticipating ammonium toxicity. This study emphasizes the importance of ecophysiological requirements and the repertoire of nitrogen transporters in understanding plant sensitivity to ammonium, and enhances our knowledge of plant nitrogen nutrition.
Open Access
Local wind speed forecasting based on WRF-HDWind coupling
(Elsevier, 2021-08-28) Prieto-Herráez, Diego; Frías Paredes, Laura; Cascón, J. Manuel; Lagüela, Susana; Gastón Romeo, Martín; Asensio, María Isabel; Martín Nieto, Ignacio; Fernandes Correia, Pedro Miguel; Laiz-Alonso, Pablo; Carrasco-Díaz, O. F.; Sáez Blázquez, Cristina; Hernández, Erwin; Ferragut, Luis; González-Aguilera, Diego; Estadística, Informática y Matemáticas; Estatistika, Informatika eta Matematika
Wind speed forecasts obtained by Numerical Weather Prediction models are limited for fine interpretation in heterogeneous terrain, in which different roughnesses and orographies occur. This limitation is derived from the use of low-resolution and grid-box averaged data. In this paper a dynamical downscaling method is presented to increase the local accuracy of wind speed forecasts. The proposed method divides the wind speed forecasting into two steps. In the first one, the mesoscale model WRF (Weather Research and Forecasting) is used for getting wind speed forecasts at specific points of the study domain. On a second stage, these values are used for feeding the HDWind microscale model. HDWind is a local model that provides both a high-resolution wind field that covers the entire study domain and values of wind speed and direction at very located points. As an example of use of the proposed method, we calculate a high-resolution wind field in an urban-interface area from Badajoz, a South-West Spanish city located near the Portugal border. The results obtained are compared with the values read by a weathervane tower of the Spanish State Meteorological Agency (AEMET) in order to prove that the microscale model improves the forecasts obtained by the mesoscale model.
Embargo
EOLO, a wind energy forecaster based on public information and automatic learning for the Spanish Electricity Markets
(Elsevier, 2024-03-23) Prieto-Herráez, Diego; Martínez-Lastras, Saray; Frías Paredes, Laura; Asensio, María Isabel; González-Aguilera, Diego; Estadística, Informática y Matemáticas; Estatistika, Informatika eta Matematika
For the correct operation of the electricity system, producers must provide an estimate of the energy they are going to discharge into the system, and they must face financial penalties if their forecasts are wrong. This is especially difficult in the case of renewable energies, and in particular wind energy because of its variability and intermittency. The tool proposed allows, in a first step, to improve the prediction of wind energy to be produced and, in a second step, to optimize the offer to be presented to the electricity market, so that the overall economic performance can be improved. This tool is based on the use of public information and automatic learning and has been evaluated on a set of 30 wind farms in Spain, using their historical production data. The results indicate improvements in both the accuracy of the energy estimation and the profit obtained from the energy sold.
Open Access
On constructing efficient UAV aerodynamic surrogate models for digital twins
(IEEE, 2024-07-31) Aláez Gómez, Daniel; Prieto Míguez, Manuel; Villadangos Alonso, Jesús; Astrain Escola, José Javier; Estadística, Informática y Matemáticas; Estatistika, Informatika eta Matematika; Institute of Smart Cities - ISC; Gobierno de Navarra / Nafarroako Gobernua
Aerodynamic modeling and optimization for unmanned aerial vehicles (UAVs) are complex and computationally intensive tasks. Surrogate models have emerged as a powerful tool for increasing efficiency in the aircraft design and optimization process. We review and evaluate some modeling techniques, such as artificial neural networks and support vector regression, showing that Gaussian process regression generally provides a well-performing solution to this type of problem. We propose an active learning algorithm based on the relevance factor, that combines bias estimated from nearest-neighbor Euclidean distance and variance, to achieve higher accuracy with fewer compuational fluid dynamics (CFD) simulations. The obtained performance is evaluated using four 2-D test functions and an experimental CFD case, indicating that the proposed active learning approach outperforms classical random sampling techniques. Thanks to this architecture, the development process of a new commercial UAV can be significantly streamlined by expediting the testing phase through the use of DTs modeled more efficiently.
Open Access
Extensions of orders to a power set vs. scores of hesitant fuzzy elements: points in common of two parallel theories
(MDPI, 2024-08-13) Induráin Eraso, Esteban; Munárriz Iriarte, Ana; Sara Goyen, Martín Sergio; Estadística, Informática y Matemáticas; Estatistika, Informatika eta Matematika; Institute for Advanced Research in Business and Economics - INARBE; Institute for Advanced Materials and Mathematics - INAMAT2
We deal with two apparently disparate theories. One of them studies extensions of orderings from a set to its power set. The other one defines suitable scores on hesitant fuzzy elements. We show that both theories have the same mathematical substrate. Thus, important possibility/impossibility results concerning criteria for extensions can be transferred to new results on scores. And conversely, conditions imposed a priori on scores can give rise to new extension criteria. This enhances and enriches both theories. We show examples of translations of classical results on extensions in the context of scores. Also, we state new results concerning the impossibility of finding a utility function representing some kind of extension order if some restrictions are imposed on the utility function considered as a score.
Open Access
Understanding the onto-semiotic approach in mathematics education through the lens of the cultural historical activity theory
(Sringer, 2024-05-29) Godino, Juan D.; Batanero, Carmen; Burgos, María; Wilhelmi, Miguel R.; Estadística, Informática y Matemáticas; Estatistika, Informatika eta Matematika
Research in mathematics education can be understood as a system of activities addressing the basic and applied problems related to teaching and learning of mathematics. Such a system includes the activities of foundation, planning, implementation, evaluation of mathematics instruction, and teacher professional development, which are supported by different theories. This diversity of theories raises interest in their comparison, coordination, and possible integration. The paper aims to present a case of application of the Cultural Historical Activity Theory (CHAT), in its 3rd and 4th generation versions, to analyze the emergence of the Onto-semiotic Approach to mathematical knowledge and instruction as a theoretical framework that addresses the study of the five partial activities mentioned above. This use of the CHAT can be useful in studies on theory articulation by focusing not only on the subjects, the object, and the instruments but also on the community context, the ecological-normative environment in which these activities take place, and the dilemmas or contradictions between theories.
Open Access
Dose-response relationship between exercise duration and enhanced function and cognition in acutely hospitalized older adults: a secondary analysis of a randomized clinical Trial
(Oxford University Press, 2024-06-01) López Sáez de Asteasu, Mikel; Martínez Velilla, Nicolás; Zambom Ferraresi, Fabrício; Galbete Jiménez, Arkaitz; Ramírez Vélez, Robinson; Cadore, Eduardo L.; Abizanda, Pedro; Gómez-Pavón, Javier; Izquierdo Redín, Mikel; Ciencias de la Salud; Osasun Zientziak; Estadística, Informática y Matemáticas; Estatistika, Informatika eta Matematika; Institute of Smart Cities - ISC; Gobierno de Navarra / Nafarroako Gobernua
Background and objectives: exercise may reverse functional decline in hospitalized older adults, but the optimal duration is unclear. This study examined the potential relationship between in-hospital multicomponent exercise program duration and changes in physical function, cognition, and muscle function to maximize exercise-related health benefits in acutely hospitalized older patients. Research design and methods: this secondary analysis of a multicenter randomized controlled trial examined the relationship between the duration of an in-hospital multicomponent exercise program and changes in physical function, cognition, and muscle strength in 570 acutely hospitalized older adults. Participants completed 3, 4, or 5-7 consecutive days of exercise based on the progression of their acute medical illness. The acute clinical condition of the older patients was similar across the study groups (i.e., 3/4/5-7 days) at admission. Outcomes included the Short Physical Performance Battery (SPPB) for functional capacity, Gait Velocity Test for gait speed, handgrip for muscle strength, and cognitive tests. Results: of the 570 patients included in the analysis, 298 were women (52.3%), and the mean (SD) age was 87.3 (4.8) years. Exercise groups increased SPPB scores compared with controls, with gains of 1.09 points after three days, 1.97 points after four days, and 2.02 points after 5-7 days (p < .001). The 4-day program showed the most significant benefit for functional capacity. Gait velocity increased by 0.11 m/s after 4 and 5-7 days (p = .032). Similar dose-response relationships were seen for handgrip strength and cognition, with 5-7 days showing more significant gains than three days (p < .05). Discussion and implications: multicomponent exercise programs enhance physical and cognitive function in hospitalized older adults, regardless of exercise dosage. A 4-day program significantly boosts functional capacity, although 5-7 days improves handgrip strength and cognition, highlighting the importance of exercise dosage in countering functional decline. Implementing evidence-based inpatient exercise prescriptions can help reverse muscle weakness and improve cognitive and physical function.
Embargo
Microeconomic analysis of ridesourcing market regulation policies
(Elsevier, 2024-08-01) García Herrera, Alisson Maurinne; Basso, Leonardo J.; Tirachini, Alejandro; Estadística, Informática y Matemáticas; Estatistika, Informatika eta Matematika
We develop a microeconomic model of competition between ridesourcing, public transport, and cruising taxis to analyse how alternative ridesourcing regulation policies affect not only the ridesourcing service but also other modes of transport. To maximise social welfare in a framework with congestion externalities, we analyse three alternative regulation policies (i) a charge as a percentage of the ridesourcing trip fare (ii) a fixed charge per ridesourcing trip, and (iii) a fixed charge per ridesourcing vehicle. A randomised search algorithm is programmed and simulations are performed considering the base case of the Metropolitan Region of Santiago de Chile. We find that for the case of speeds below 9 km/h, the market power of the platform is dominated by the congestion externality effect, which leads to an optimum where the regulator charges a tax to the platform. In turn, waiting time for ridesourcing increases, but congestion decreases. Lower congestion scenarios lead to a ridesourcing subsidy, in which the regulation policy increases the number of ridesourcing drivers and reduces waiting time, at the cost of increasing congestion. For a given scenario (either low-congestion or high-congestion), we find that the profits of the agents involved (ridesourcing platform and drivers, taxi drivers, and bus operator) are sensitive to the type of regulation applied, however the total social benefit and consumer surplus are largely insensitive to the regulation adopted, therefore policymakers could take into account, for instance, the effects on the financial situation of the public transport sector when deciding which type of regulation instrument to apply to the ridesourcing sector.
Embargo
Polynomial crisp-minimization algorithm for fuzzy deterministic automata
(Elsevier, 2024-11-01) González de Mendívil Grau, Aitor; Fariña Figueredo, Federico; Stanimirovic, Stefan; Micic, Ivana; González de Mendívil Moreno, José Ramón; Estadística, Informática y Matemáticas; Estatistika, Informatika eta Matematika; Institute of Smart Cities - ISC
Designing automata minimization algorithms is a significant topic in Automata Theory and Languages with practical applications. In this paper, we develop an efficient minimization algorithm for deterministic fuzzy finite automata over locally finite lattices. More precisely, the algorithm outputs an equivalent minimal crisp-deterministic fuzzy finite automaton for an input fuzzy deterministic finite automaton (FDfA). The running time of the proposed algorithm is polynomial for particular types of locally finite lattices, specifically for max-min-based complete residuated lattices. The intuition behind the proposed algorithm relies on the polynomial minimization algorithm's intuition for ordinary deterministic automata developed by Vazquez de Parga, Garcia, and Lopez (2013) [35]. The motivation for this study comes from the fact that the original algorithm's notions and meanings are lost in the context of fuzzy automata. Thus, we establish a new theoretical foundation that provides the correctness and the polynomial-time nature of this new crisp-minimization algorithm for FDfAs.
Embargo
Extremal values-based aggregation functions
(Elsevier, 2024-10-01) Halaš, Radomír; Mesiar, Radko; Kolesárová, Anna; Saadati, Reza; Herrera, Francisco; Rodríguez Martínez, Iosu; Bustince Sola, Humberto; Estadística, Informática y Matemáticas; Estatistika, Informatika eta Matematika; Institute of Smart Cities - ISC
We introduce and study aggregation functions based on extremal values, namely extended (𝑙, 𝑢)- aggregation functions whose outputs only depend on a fixed number 𝑙 of extremal lower input values and a fixed number 𝑢 of extremal upper input values, independently of the arity of the input 𝑛-tuples (𝑛 ≥ 𝑙 + 𝑢). We discuss several general properties of (𝑙, 𝑢)-aggregation functions and we study special (𝑙, 𝑢)-aggregation functions with neutral element, including t-conorms, t-norms and uninorms. We also study (𝑙, 𝑢)-aggregation functions defined by means of integrals with respect to discrete fuzzy measures, as well as (𝑙, 𝑢)-ordered weighted quasi-arithmetic means based on appropriate weighting vectors. We also stress some generalizations based on recently introduced new types of monotonicity. Some possible applications are sketched, too.