Departamento de Estadística e Investigación Operativahttps://hdl.handle.net/10481/150292024-03-28T23:21:19Z2024-03-28T23:21:19ZA hierarchical decision-based maintenance for a complex modular system driven by the MoMA algorithmSegovia García, María del CarmenGámiz Pérez, María LuzMontoro Cazorla, Deliahttps://hdl.handle.net/10481/897612024-03-04T11:03:57ZA hierarchical decision-based maintenance for a complex modular system driven by the MoMA algorithm
Segovia García, María del Carmen; Gámiz Pérez, María Luz; Montoro Cazorla, Delia
This paper presents a maintenance policy for a modular system formed by
independent modules (n-subsystems) subjected to environmental conditions (shocks). For the modeling of this complex system, the use of the Matrix-Analytical Method (MAM) is proposed under a layered approach according to its hierarchical structure. Thus, the operational state of the system (top layer) depends on the states of the modules (middle layer), which in turn depend on the states of their components (bottom layer). This allows a detailed description of the system operation to plan maintenance actions appropriately and optimally. We propose a hierarchical decision-based maintenance strategy with periodic inspections as follows: at the time of the inspection, the condition of the system is first evaluated. If intervention is necessary, the modules are then checked to make individual decisions based on their states, and so on. Replacement or repair will be carried out as appropriate. An optimization problem is formulated as a function of the length of the inspection period and the intervention cost incurred over the useful life of the system. Our method shows the advantages, providing compact and implementable expressions. The model is illustrated on a submarine Electrical Control Unit (ECU).
Self-selection or indoctrination in the study of (standard) economics: A systematic literature reviewMiragaya Casillas, Cristina IsabelAguayo Estremera, RaimundoRuiz Villaverde, Albertohttps://hdl.handle.net/10481/888012024-02-09T09:05:41ZSelf-selection or indoctrination in the study of (standard) economics: A systematic literature review
Miragaya Casillas, Cristina Isabel; Aguayo Estremera, Raimundo; Ruiz Villaverde, Alberto
Considerable academic debate exists as to whether students with a background in economics exhibit distinct behavioural patterns that set them apart from students in other academic disciplines. Primarily, the debate concerns whether students who fit the stereotype of the economist choose to study economics (the self-selection hypothesis) or whether economics students develop these behavioural patterns in the course of their university studies (the indoctrination hypothesis). We conducted a systematic literature review that examines both hypotheses. According to the literature reviewed, the majority of researchers find the self-selection hypothesis to be the best supported. However, findings remain inconclusive due to several methodological limitations. In spite of that, this study should facilitate a deeper understanding of what causes behavioural changes in economics students and what exactly these behavioural differences are, among other relevant hypotheses.
logitFD: an R package for functional principal component logit regressionEscabias Machuca, ManuelAguilera Del Pino, Ana MaríaAcal González, Christian Joséhttps://hdl.handle.net/10481/886602024-02-08T08:09:45ZlogitFD: an R package for functional principal component logit regression
Escabias Machuca, Manuel; Aguilera Del Pino, Ana María; Acal González, Christian José
The functional logit regression model was proposed by Escabias et al. (2004) with the objective of modeling a scalar binary response variable from a functional predictor. The model estimation proposed in that case was performed in a subspace of L2(T) of squared integrable functions of finite dimension, generated by a finite set of basis functions. For that estimation it was assumed that the curves of the functional predictor and the functional parameter of the model belong to the same finite subspace. The estimation so obtained was affected by high multicollinearity problems and the solution given to these problems was based on different functional principal component analysis. The logitFD package introduced here provides a toolbox for the fit of these models by implementing the different proposed solutions and by generalizing the model proposed in 2004 to the case of several functional and non-functional predictors. The performance of the functions is illustrated by using data sets of functional data included in the fda.usc package from R-CRAN.
First Passage and First Exit Times for diffusion processes related to a general growth curveAlbano, GiuseppinaAntonio, BarreraGiorno, VirginiaRomán Román, PatriciaTorres Ruiz, Francisco De Asíshttps://hdl.handle.net/10481/883702024-02-06T10:35:06ZFirst Passage and First Exit Times for diffusion processes related to a general growth curve
Albano, Giuseppina; Antonio, Barrera; Giorno, Virginia; Román Román, Patricia; Torres Ruiz, Francisco De Asís
Recently a general growth curve including the well known growth equations, such as Malthus, logistic, Bertallanfy, Gompertz, has been studied. We now propose two stochastic formulations of this growth equation. They are obtained starting from a suitable
parametrization of the deterministic model, by adding an additive and multiplicative noise respectively. For these processes we focus attention on the First Passage Time from a barrier and on the First Exit Time from a region delimited by two barriers. We consider thresholds, generally time dependent, for which there exist closed-forms of the probability densities of the first passage time and of the first exit time.
ImaGEO: Integrative Gene Expression Meta-Analysis from GEO databaseToro-Dominguez, DanielMartorell-Marugan, JordiLopez-Dominguez, RaulGarcía-Moreno, AdrianGonzález-Rumayor, VictorAlarcón Riquelme, Marta EugeniaCarmona Sáez, Pedrohttps://hdl.handle.net/10481/882812024-02-05T13:04:02ZImaGEO: Integrative Gene Expression Meta-Analysis from GEO database
Toro-Dominguez, Daniel; Martorell-Marugan, Jordi; Lopez-Dominguez, Raul; García-Moreno, Adrian; González-Rumayor, Victor; Alarcón Riquelme, Marta Eugenia; Carmona Sáez, Pedro