Departaments
http://hdl.handle.net/2117/28579
2024-03-29T05:05:13ZEstudi de paisatge: Camp de l'Arpa
http://hdl.handle.net/2117/405583
Estudi de paisatge: Camp de l'Arpa
Cervera Alonso de Medina, Marina; Mercadé Aloy, Josep; Navas Ferrer, Teresa; Villares Junyent, Míriam; Roca Bosch, Elisabet
El coneixement profund del territori, és a dir, la seva auscultació paisatgística, esdevé un instrument previ cada vegada més imprescindible per a desenvolupar el planejament, per a les actuacions en les infraestructures i la urbanització, per a les intervencions sobre el patrimoni construït i, en general, per a orientar les actuacions sobre el territori
2024-03-28T19:46:35ZCervera Alonso de Medina, MarinaMercadé Aloy, JosepNavas Ferrer, TeresaVillares Junyent, MíriamRoca Bosch, ElisabetEl coneixement profund del territori, és a dir, la seva auscultació paisatgística, esdevé un instrument previ cada vegada més imprescindible per a desenvolupar el planejament, per a les actuacions en les infraestructures i la urbanització, per a les intervencions sobre el patrimoni construït i, en general, per a orientar les actuacions sobre el territoriCoupled hydromechanical modelling of cone penetration in layered liquefiable soils
http://hdl.handle.net/2117/405582
Coupled hydromechanical modelling of cone penetration in layered liquefiable soils
Boschi, Katia; Arroyo Alvarez de Toledo, Marcos; Monforte Vila, Lluís; Carbonell Puigbó, Josep Maria; Gens Solé, Antonio
Soil layering modifies cone penetration measurements when the cone is close to layer boundaries. Transition zone and thin-layer effects appear, complicating interpretation. To help identify the mechanisms underlying transition and thin-layer effects, several series of realistic simulations of cone penetration in layered soils are presented. Cone penetration tests are simulated using fully coupled hydromechanical models solved with the particle finite element method. A constitutive model capable of representing flow liquefaction is employed to explore the effect of embedded layers with different initial state parameter and/or hydraulic conductivity than the host soil. Sensing and development distances for tip resistance and excess pore pressure are examined, as well as the effect of layering on dissipation tests. It is shown how distortion of layer interfaces by the cone is captured, explaining several characteristics of pore pressure and dissipation records. It is also shown that looser soil states may be hidden in the tip resistance trace by simultaneous changes in soil hydraulic conductivity.
2024-03-28T19:37:17ZBoschi, KatiaArroyo Alvarez de Toledo, MarcosMonforte Vila, LluísCarbonell Puigbó, Josep MariaGens Solé, AntonioSoil layering modifies cone penetration measurements when the cone is close to layer boundaries. Transition zone and thin-layer effects appear, complicating interpretation. To help identify the mechanisms underlying transition and thin-layer effects, several series of realistic simulations of cone penetration in layered soils are presented. Cone penetration tests are simulated using fully coupled hydromechanical models solved with the particle finite element method. A constitutive model capable of representing flow liquefaction is employed to explore the effect of embedded layers with different initial state parameter and/or hydraulic conductivity than the host soil. Sensing and development distances for tip resistance and excess pore pressure are examined, as well as the effect of layering on dissipation tests. It is shown how distortion of layer interfaces by the cone is captured, explaining several characteristics of pore pressure and dissipation records. It is also shown that looser soil states may be hidden in the tip resistance trace by simultaneous changes in soil hydraulic conductivity.Experimental programme on austenitic stainless steel RHS members subjected to monotonic and cyclic bending
http://hdl.handle.net/2117/405568
Experimental programme on austenitic stainless steel RHS members subjected to monotonic and cyclic bending
González de León, Isabel; Nastri, Elide; Arrayago Luquin, Itsaso; Montuori, Rosario; Piluso, Vincenzo; Real Saladrigas, Esther
Stainless steel is a corrosion resistant iron alloy with great potential in structural engineering due to its excellent mechanical features, durability and aesthetic properties. Since most of the existing research has concerned the behaviour of the material, the response of individual structural members, or the performance of simple structural systems under monotonic loading, one of the challenges that remains is the evaluation of the cyclic performance of members to promote its use in seismic design and exploit the excellent ductility and strain hardening properties of this material. For this reason, an experimental programme on austenitic stainless steel Rectangular Hollow Section (RHS) specimens was carried out at the Department of Civil Engineering of the Università degli Studi di Salerno in collaboration with the Universitat Politècnica de Catalunya. A total of eight RHS specimens were tested around the minor axis under both monotonic (three specimens) and cyclic (five specimens) loading, in an experimental set-up that followed a cantilever scheme. The main purpose of this study was to acquire information on the cyclic performance of austenitic steel structural members, focusing on the comparison between monotonic and cyclic behaviours. The outcomes of the tests included the load–displacement and the moment–rotation curves, the energy dissipation capacity, and the evaluation of the key rotation capacities of the members. The reported data are essential to enhance the still scarce research on the seismic behaviour of stainless steel structures.
2024-03-28T19:01:54ZGonzález de León, IsabelNastri, ElideArrayago Luquin, ItsasoMontuori, RosarioPiluso, VincenzoReal Saladrigas, EstherStainless steel is a corrosion resistant iron alloy with great potential in structural engineering due to its excellent mechanical features, durability and aesthetic properties. Since most of the existing research has concerned the behaviour of the material, the response of individual structural members, or the performance of simple structural systems under monotonic loading, one of the challenges that remains is the evaluation of the cyclic performance of members to promote its use in seismic design and exploit the excellent ductility and strain hardening properties of this material. For this reason, an experimental programme on austenitic stainless steel Rectangular Hollow Section (RHS) specimens was carried out at the Department of Civil Engineering of the Università degli Studi di Salerno in collaboration with the Universitat Politècnica de Catalunya. A total of eight RHS specimens were tested around the minor axis under both monotonic (three specimens) and cyclic (five specimens) loading, in an experimental set-up that followed a cantilever scheme. The main purpose of this study was to acquire information on the cyclic performance of austenitic steel structural members, focusing on the comparison between monotonic and cyclic behaviours. The outcomes of the tests included the load–displacement and the moment–rotation curves, the energy dissipation capacity, and the evaluation of the key rotation capacities of the members. The reported data are essential to enhance the still scarce research on the seismic behaviour of stainless steel structures.Analysis of the extension of the elastic parameters for modelling highly expansive unsaturated soils with the Barcelona basic model
http://hdl.handle.net/2117/405567
Analysis of the extension of the elastic parameters for modelling highly expansive unsaturated soils with the Barcelona basic model
Alcoverro Bassols, Jordi; Pintado, Xavier; Olivella Pastallé, Sebastià; Toprak, Erdem; Niskanen, Mika
Modelling of engineered barrier systems (EBS) in deep geological disposals of spent nuclear fuel requires sophisticated approaches that include highly nonlinear constitutive models. The Barcelona Basic Model for Expansive soils (BBMEx) is an extension for highly expansive unsaturated soils of the Barcelona Basic Model (BBM) for slightly-to-moderately expansive unsaturated soils. In this extension, the parameter k (logarithmic compliance with respect to changes in net pressure) of the BBM is extended to a function of suction and a set of parameters, and the parameter ks (logarithmic compliance with respect to changes in suction) of the BBM is extended to a function of net pressure, suction, and a set of parameters. On these functions, four conditions which are satisfied in the BBM are considered. For each condition, two results are obtained: (1) the ranges of the values of the parameters such that the condition is satisfied for all positive net pressures and all non-negative suctions and (2) for given values of the parameters, the maximum net pressure and the maximum suction such that the condition is satisfied for positive net pressures and non-negative suctions. The results should help prevent unrealistic predictions of the BBMEx. The extension was used for carrying out the simulation of an infiltration test in two different bentonites and the BBMEx model parameters analysed.
2024-03-28T18:53:15ZAlcoverro Bassols, JordiPintado, XavierOlivella Pastallé, SebastiàToprak, ErdemNiskanen, MikaModelling of engineered barrier systems (EBS) in deep geological disposals of spent nuclear fuel requires sophisticated approaches that include highly nonlinear constitutive models. The Barcelona Basic Model for Expansive soils (BBMEx) is an extension for highly expansive unsaturated soils of the Barcelona Basic Model (BBM) for slightly-to-moderately expansive unsaturated soils. In this extension, the parameter k (logarithmic compliance with respect to changes in net pressure) of the BBM is extended to a function of suction and a set of parameters, and the parameter ks (logarithmic compliance with respect to changes in suction) of the BBM is extended to a function of net pressure, suction, and a set of parameters. On these functions, four conditions which are satisfied in the BBM are considered. For each condition, two results are obtained: (1) the ranges of the values of the parameters such that the condition is satisfied for all positive net pressures and all non-negative suctions and (2) for given values of the parameters, the maximum net pressure and the maximum suction such that the condition is satisfied for positive net pressures and non-negative suctions. The results should help prevent unrealistic predictions of the BBMEx. The extension was used for carrying out the simulation of an infiltration test in two different bentonites and the BBMEx model parameters analysed.SOLDIER: SOLution for Dam behavior Interpretation and safety Evaluation with boosted Regression trees
http://hdl.handle.net/2117/405565
SOLDIER: SOLution for Dam behavior Interpretation and safety Evaluation with boosted Regression trees
Salazar González, Fernando; Irazábal González, Joaquín; Conde Vázquez, André
Decision making in dam safety is fundamentally based on the comparison between the predictions of a behavior model and the records of the monitoring system. Traditionally, simple linear regression models have been used. Recently, models based on machine learning are being explored, which generally offer greater precision –therefore, greater capacity for detecting anomalies –, higher flexibility and versatility. We have developed an interactive application based on R-Shiny to generate models based on boosted regression trees, evaluate their accuracy and analyze the effect of predictor variables on the system response. This allows for identifying changes in dam behavior, detecting potential anomalies and better understanding the effect of the loads on the structure. The availability of the software will contribute to the penetration of machine learning techniques in the dam engineering sector and will open the door to its use in structural health monitoring for other civil infrastructures.
2024-03-28T18:02:02ZSalazar González, FernandoIrazábal González, JoaquínConde Vázquez, AndréDecision making in dam safety is fundamentally based on the comparison between the predictions of a behavior model and the records of the monitoring system. Traditionally, simple linear regression models have been used. Recently, models based on machine learning are being explored, which generally offer greater precision –therefore, greater capacity for detecting anomalies –, higher flexibility and versatility. We have developed an interactive application based on R-Shiny to generate models based on boosted regression trees, evaluate their accuracy and analyze the effect of predictor variables on the system response. This allows for identifying changes in dam behavior, detecting potential anomalies and better understanding the effect of the loads on the structure. The availability of the software will contribute to the penetration of machine learning techniques in the dam engineering sector and will open the door to its use in structural health monitoring for other civil infrastructures.Optimization-based level-set re-initialization: a robust interface preserving approach in multiphase problems
http://hdl.handle.net/2117/405562
Optimization-based level-set re-initialization: a robust interface preserving approach in multiphase problems
Hashemi, Alireza; Hashemi, Mohammad Reza; Ryzhakov, Pavel; Rossi, Riccardo
In spite of its overall efficiency and robustness for capturing the interface in multiphase fluid dynamics simulations, the well-known shortcoming of the level-set method is associated with the lack of a systematic approach for preserving the regularity of the distance function. This is mainly due to the stretching (or compressing) effect of the strain rate especially in the vicinity of the liquid-gas interface. Level-set re-initialization is an effective treatment for this issue. However, the traditional approach based on the hyperbolic Hamilton–Jacobi equation is a computationally expensive procedure. Crucially, due to the hyperbolic nature of the formulation, the accuracy of the results hinges significantly on the specialized handling of blind spots near the liquid-gas interface intersecting the substrate. The present work proposes a two-step elliptic level-set re-initialization approach that strictly preserves the location of zero level-set via incorporation of an element splitting process. The primary initialization step helps remove any non-smoothness in the to-be regularized level-set function dramatically improving the efficiency of the secondary optimization step. Geometric representation of the boundary conditions is utilized in the initialization step, while the optimization step minimizes the reliance of the results on the treatment of the blind spots. The performance of the proposed method is examined for free and sessile three-dimensional droplets.
2024-03-28T17:44:18ZHashemi, AlirezaHashemi, Mohammad RezaRyzhakov, PavelRossi, RiccardoIn spite of its overall efficiency and robustness for capturing the interface in multiphase fluid dynamics simulations, the well-known shortcoming of the level-set method is associated with the lack of a systematic approach for preserving the regularity of the distance function. This is mainly due to the stretching (or compressing) effect of the strain rate especially in the vicinity of the liquid-gas interface. Level-set re-initialization is an effective treatment for this issue. However, the traditional approach based on the hyperbolic Hamilton–Jacobi equation is a computationally expensive procedure. Crucially, due to the hyperbolic nature of the formulation, the accuracy of the results hinges significantly on the specialized handling of blind spots near the liquid-gas interface intersecting the substrate. The present work proposes a two-step elliptic level-set re-initialization approach that strictly preserves the location of zero level-set via incorporation of an element splitting process. The primary initialization step helps remove any non-smoothness in the to-be regularized level-set function dramatically improving the efficiency of the secondary optimization step. Geometric representation of the boundary conditions is utilized in the initialization step, while the optimization step minimizes the reliance of the results on the treatment of the blind spots. The performance of the proposed method is examined for free and sessile three-dimensional droplets.Probabilistic estimation of the dynamic response of high-rise buildings via transfer functions
http://hdl.handle.net/2117/405561
Probabilistic estimation of the dynamic response of high-rise buildings via transfer functions
Tirado Gutiérrez, Rodolfo Javier; Vargas Alzate, Yeudy Felipe; González Drigo, José Ramón
The significant number of seismic ground motion records to be considered when designing or assessing civil structures is a common restriction for employing advanced nonlinear dynamic methods. This is because the large computational time involved in the calculation of the nonlinear dynamic response of complex multi-degree-of-freedom systems. There are several strategies to overcome this limitation; however, the reliability estimation of the analyzed systems can be compromised. This research is focused on developing a methodology to achieve a probabilistic and reliable estimation of the seismic response of buildings by tackling the computational effort. To do so, a set of transfer functions extracted from the dynamic response of three building models have been obtained. Then, an optimal transfer function per building is identified as the one maximizing the prediction of engineering demand parameters (EDPs), when each structure is subjected to a large set of ground motions records. Results show that the response of a reduced number of records allows developing an enhanced strategy to obtain reliable results in terms of the main statistical moments of the EDPs. This increased capacity to analyze complex systems in an affordable time has important consequences in the identification of optimal designs in terms of the material-performance ratio, as well as in the estimation of expected seismic risk.
2024-03-28T17:31:36ZTirado Gutiérrez, Rodolfo JavierVargas Alzate, Yeudy FelipeGonzález Drigo, José RamónThe significant number of seismic ground motion records to be considered when designing or assessing civil structures is a common restriction for employing advanced nonlinear dynamic methods. This is because the large computational time involved in the calculation of the nonlinear dynamic response of complex multi-degree-of-freedom systems. There are several strategies to overcome this limitation; however, the reliability estimation of the analyzed systems can be compromised. This research is focused on developing a methodology to achieve a probabilistic and reliable estimation of the seismic response of buildings by tackling the computational effort. To do so, a set of transfer functions extracted from the dynamic response of three building models have been obtained. Then, an optimal transfer function per building is identified as the one maximizing the prediction of engineering demand parameters (EDPs), when each structure is subjected to a large set of ground motions records. Results show that the response of a reduced number of records allows developing an enhanced strategy to obtain reliable results in terms of the main statistical moments of the EDPs. This increased capacity to analyze complex systems in an affordable time has important consequences in the identification of optimal designs in terms of the material-performance ratio, as well as in the estimation of expected seismic risk.The DESI survey validation: Results from visual inspection of the quasar survey spectra
http://hdl.handle.net/2117/405556
The DESI survey validation: Results from visual inspection of the quasar survey spectra
BAILEY, S.; Carr, Andrew J.; Farr, James P.; Levi, Martín Iván; Pérez Ràfols, Ignasi; Aazou, Safae
A key component of the Dark Energy Spectroscopic Instrument (DESI) survey validation (SV) is a detailed visual inspection (VI) of the optical spectroscopic data to quantify key survey metrics. In this paper we present results from VI of the quasar survey using deep coadded SV spectra. We show that the majority (˜70%) of the main-survey targets are spectroscopically confirmed as quasars, with ˜16% galaxies, ˜6% stars, and ˜8% low-quality spectra lacking reliable features. A nonnegligible fraction of the quasars are misidentified by the standard spectroscopic pipeline, but we show that the majority can be recovered using post-pipeline "afterburner" quasar-identification approaches. We combine these "afterburners" with our standard pipeline to create a modified pipeline to increase the overall quasar yield. At the depth of the main DESI survey, both pipelines achieve a good-redshift purity (reliable redshifts measured within 3000 km s-1) of ˜99%; however, the modified pipeline recovers ˜94% of the visually inspected quasars, as compared to ˜86% from the standard pipeline. We demonstrate that both pipelines achieve a median redshift precision and accuracy of ˜100 km s-1 and ˜70 km s-1, respectively. We constructed composite spectra to investigate why some quasars are missed by the standard pipeline and find that they are more host-galaxy dominated (i.e., distant analogs of "Seyfert galaxies") and/or more dust reddened than the standard-pipeline quasars. We also show example spectra to demonstrate the overall diversity of the DESI quasar sample and provide strong-lensing candidates where two targets contribute to a single spectrum.
2024-03-28T12:47:25ZBAILEY, S.Carr, Andrew J.Farr, James P.Levi, Martín IvánPérez Ràfols, IgnasiAazou, SafaeA key component of the Dark Energy Spectroscopic Instrument (DESI) survey validation (SV) is a detailed visual inspection (VI) of the optical spectroscopic data to quantify key survey metrics. In this paper we present results from VI of the quasar survey using deep coadded SV spectra. We show that the majority (˜70%) of the main-survey targets are spectroscopically confirmed as quasars, with ˜16% galaxies, ˜6% stars, and ˜8% low-quality spectra lacking reliable features. A nonnegligible fraction of the quasars are misidentified by the standard spectroscopic pipeline, but we show that the majority can be recovered using post-pipeline "afterburner" quasar-identification approaches. We combine these "afterburners" with our standard pipeline to create a modified pipeline to increase the overall quasar yield. At the depth of the main DESI survey, both pipelines achieve a good-redshift purity (reliable redshifts measured within 3000 km s-1) of ˜99%; however, the modified pipeline recovers ˜94% of the visually inspected quasars, as compared to ˜86% from the standard pipeline. We demonstrate that both pipelines achieve a median redshift precision and accuracy of ˜100 km s-1 and ˜70 km s-1, respectively. We constructed composite spectra to investigate why some quasars are missed by the standard pipeline and find that they are more host-galaxy dominated (i.e., distant analogs of "Seyfert galaxies") and/or more dust reddened than the standard-pipeline quasars. We also show example spectra to demonstrate the overall diversity of the DESI quasar sample and provide strong-lensing candidates where two targets contribute to a single spectrum.A workflow for standardizing the analysis of highly resolved vessel tracking data
http://hdl.handle.net/2117/405555
A workflow for standardizing the analysis of highly resolved vessel tracking data
Mendo, Tania; Mujal Colilles, Anna; Stounberg, Jonathan; Glemarec, Gildas; Mugerza, Estanis; Egekvist, Josefine; Mega Rufino, Marta; Swift, Rene; James, Mark Andrew
Knowledge on the spatial and temporal distribution of the activities carried out in the marine environment is key to manage available space optimally. However, frequently, little or no information is available on the distribution of the largest users of the marine space, namely fishers. Tracking devices are being increasingly used to obtain highly resolved geospatial data of fishing activities, at intervals from seconds to minutes. However, to date no standardized method is used to process and analyse these data, making it difficult to replicate analysis. We develop a workflow to identify individual vessel trips and infer fishing activities from highly resolved geospatial data, which can be applied for large-scale fisheries, but also considers nuances encountered when working with small-scale fisheries. Recognizing the highly variable nature of activities conducted by different fleets, this workflow allows the user to choose a path that best aligns with the particularities in the fishery being analysed. A new method to identify anchoring sites for small-scale fisheries is also presented. The paper provides detailed code used in each step of the workflow both in R and Python language to widen the application of the workflow in the scientific and stakeholder communities and to encourage its improvement and refinement in the future.
2024-03-28T12:46:38ZMendo, TaniaMujal Colilles, AnnaStounberg, JonathanGlemarec, GildasMugerza, EstanisEgekvist, JosefineMega Rufino, MartaSwift, ReneJames, Mark AndrewKnowledge on the spatial and temporal distribution of the activities carried out in the marine environment is key to manage available space optimally. However, frequently, little or no information is available on the distribution of the largest users of the marine space, namely fishers. Tracking devices are being increasingly used to obtain highly resolved geospatial data of fishing activities, at intervals from seconds to minutes. However, to date no standardized method is used to process and analyse these data, making it difficult to replicate analysis. We develop a workflow to identify individual vessel trips and infer fishing activities from highly resolved geospatial data, which can be applied for large-scale fisheries, but also considers nuances encountered when working with small-scale fisheries. Recognizing the highly variable nature of activities conducted by different fleets, this workflow allows the user to choose a path that best aligns with the particularities in the fishery being analysed. A new method to identify anchoring sites for small-scale fisheries is also presented. The paper provides detailed code used in each step of the workflow both in R and Python language to widen the application of the workflow in the scientific and stakeholder communities and to encourage its improvement and refinement in the future.Generative artificial intelligence in education: from deceptive to disruptive
http://hdl.handle.net/2117/405554
Generative artificial intelligence in education: from deceptive to disruptive
Alier Forment, Marc; García Peñalvo, Francisco José; Camba, Jorge D.
Generative Artificial Intelligence (GenAI) has emerged as a promising technology that can create original content, such as text, images, and sound. The use of GenAI in educational settings is becoming increasingly popular and offers a range of opportunities and challenges. This special issue explores the management and integration of GenAI in educational settings, including the ethical considerations, best practices, and opportunities. The potential of GenAI in education is vast. By using algorithms and data, GenAI can create original content that can be used to augment traditional teaching methods, creating a more interactive and personalized learning experience. In addition, GenAI can be utilized as an assessment tool and for providing feedback to students using generated content. For instance, it can be used to create custom quizzes, generate essay prompts, or even grade essays. The use of GenAI as an assessment tool can reduce the workload of teachers and help students receive prompt feedback on their work. Incorporating GenAI in educational settings also poses challenges related to academic integrity. With availability of GenAI models, students can use them to study or complete their homework assignments, which can raise concerns about the authenticity and authorship of the delivered work. Therefore, it is important to ensure that academic standards are maintained, and the originality of the student's work is preserved. This issue highlights the need for implementing ethical practices in the use of GenAI models and ensuring that the technology is used to support and not replace the student's learning experience.
2024-03-28T12:42:27ZAlier Forment, MarcGarcía Peñalvo, Francisco JoséCamba, Jorge D.Generative Artificial Intelligence (GenAI) has emerged as a promising technology that can create original content, such as text, images, and sound. The use of GenAI in educational settings is becoming increasingly popular and offers a range of opportunities and challenges. This special issue explores the management and integration of GenAI in educational settings, including the ethical considerations, best practices, and opportunities. The potential of GenAI in education is vast. By using algorithms and data, GenAI can create original content that can be used to augment traditional teaching methods, creating a more interactive and personalized learning experience. In addition, GenAI can be utilized as an assessment tool and for providing feedback to students using generated content. For instance, it can be used to create custom quizzes, generate essay prompts, or even grade essays. The use of GenAI as an assessment tool can reduce the workload of teachers and help students receive prompt feedback on their work. Incorporating GenAI in educational settings also poses challenges related to academic integrity. With availability of GenAI models, students can use them to study or complete their homework assignments, which can raise concerns about the authenticity and authorship of the delivered work. Therefore, it is important to ensure that academic standards are maintained, and the originality of the student's work is preserved. This issue highlights the need for implementing ethical practices in the use of GenAI models and ensuring that the technology is used to support and not replace the student's learning experience.