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La liquefazione è un fenomeno complesso che potrebbe causare numerosi danni agli edifici e alle infrastrutture. È generalmente identificato come la perdita di resistenza e rigidità di un terreno a causa di scosse sismiche o altri carichi dinamici. Comprendere appieno il suo meccanismo rimane una delle sfide dell’ingegneria geotecnica legata ai terremoti, poiché i geomateriali non mostrano reazioni identiche in condizioni sismiche simili. Dal terremoto di Niigata del 1964, molti ricercatori hanno mostrato interesse per questo campo e si sono impegnati per studiare questo fenomeno. Questa tesi di dottorato si concentra sull'analisi dei terreni liquefacibili partendo da un metodo semplificato per poi esplorare i metodi avanzati, attraverso lo studio di due casi reali, che coinvolgono diverse strutture geotecniche. L'obiettivo è quello di fornire un metodo completo di analisi nel campo della liquefazione, concentrandosi soprattutto su apparecchiature di laboratorio che meglio simulino il comportamento dinamico del terreno. Per ottenere questo risultato, il lavoro è stato sviluppato in più fasi focalizzate principalmente sullo studio sperimentale, teorico e numerico; questo percorso rappresenta il tipico e peculiare approccio ingegneristico per l'analisi di un fenomeno reale. Le prove in situ sono considerate come punto di partenza nella valutazione della liquefazione, poiché forniscono il Fattore di Sicurezza del terreno in esame, necessario per ulteriori analisi. Le apparecchiature di laboratorio consentono di testare il materiale per valutare la sua suscettibilità alla liquefazione, ma soprattutto per definire una curva affidabile da utilizzare nella calibrazione della modellazione costitutiva. A questo scopo sono state eseguite diverse prove triassiali cicliche, a carico controllato e a deformazione controllata, al fine di definire una procedura di prova per ottenere risultati di alta qualità. Un'analisi finale mediante modellazione numerica basata sulla ca, Liquefaction is a complex phenomenon which could lead to several damages in building and infrastructure. It is generally identified as the loose of strength and stiffness of a soil by earthquake shaking or other dynamic loading. Fully understanding its mechanism remains one of the challenges of earthquake-related geotechnical engineering, as geomaterials do not exhibit identical reactions under similar seismic conditions. From Niigata earthquake in 1964, many researchers have shown interest in this field and have worked to study this phenomenon. This PhD thesis is focus on analysis of liquefiable soils starting from a simplified method and then exploring the advanced methods, by means of study of two real cases, which involve different geotechnical structure. The objective is to provide a full method of analysis in liquefaction field, focusing most of all on laboratory equipment which better simulate the dynamic behaviour of the soil. For getting this result, the work has been developed in more phasis focused mostly on experimental, theoretical and numerical study; this path represents the typical and peculiar engineering approach for analysing a real phenomenon. In situ tests are considered as a starting point in liquefaction assessment, since they provide the Factor of Safety of soil under investigation, necessary for further analysis. Laboratory equipment allow to test the material in order to evaluate its susceptibility to liquefaction, but most of all to define reliable curve to be used in constitutive modelling calibration. For this purpose, several cyclic triaxial test have been performed, load-controlled and strain-controlled, in order to define a testing procedure to obtain high quality results. A final analysis by means of numerical modelling based on real test calibration, allows to make prediction not only about susceptibility but also about the actual effects of liquefaction on structure. The work presented reinforces the possibility of using the combin

© 2024 Elsevier. This manuscript version is made available under the CC BY 4.0 DEED license https://creativecommons.org/licenses/by/4.0, We present a particular derivation of the face-centred finite volume (FCFV) method and study its performance in non-linear, coupled transport problems commonly encountered in geoscientific and geotechnical applications. The FCFV method is derived from the hybridisable discontinuous Galerkin formulation, using a constant degree of approximation for the discretization of the unknowns defined on the mesh faces (edges in two dimensions). The piecewise constant degrees of freedom are determined in a global problem over the mesh skeleton. Then, the solution and its gradient are recovered at the cells centroid in a set of element-by-element independent postprocesses, both exhibiting linear convergence. The formulation of the transient advection-diffusion-reaction equation is presented in detail and the numerical analysis under challenging advective/diffusive regimes is studied. Finally, we use several numerical examples to illustrate the advantages and limitations of the FCFV method to solve problems of geoscientific and geotechnical relevance governed by the non-linear coupling between advection-diffusion-reactive transport and Stokes flow. Our results show that the FCFV method is an attractive and highly competitive alternative to other commonly used methods., This work is funded by MCIN/AEI doi:/10.13039/501100011033 through project PID2020-113463RB-C32, by the Generalitat de Catalunya, Spain (Grant number: 2017-SGR-1278) and by EU H2020-MSCA-RISE grant agreement No 777778. MB acknowledges support from a doctoral scholarship by CSIRO., Peer Reviewed, Postprint (published version)

Every day, technical projects are carried out for the transformation on vehicles, especially on industrial vehicles, as these are designed to meet the needs of the final user and therefore undergo transformations more frequently than passenger cars. In many cases, the calculations and processes involved in the technical project are not highly complex. However, sometimes, before carrying out the technical project, a more detailed or specific study is desirable or required on the vehicle to give more accurate data to the customer. The purpose of this project is to conduct a more thorough study prior to the reform in order to make a more precise choice regarding the vehicle’s bodywork in terms of the structural resistance of the frame, aiming to ensure the safest structural configuration. To achieve this, theoretical calculations will be performed through basic static equations, the first and second Mohr’s theorems, and the results collected through these calculations will be compared with those obtained through simulation using finite element method software. The results obtained in this work have demonstrated the viability of both configurations, with the configuration featuring the crane at the rear overhang yielding more favourable results in terms of structural resistance and safety. However, it has been verified that the obtained results can be improved by reducing the dimensions of the rear overhang in both configurations.

Monitoring the spread of SARS-CoV-2 presents significant challenges due to the asymptomatic nature of the infections, the presence of numerous variants, and changes in population behavior resulting from the implementation of non-pharmaceutical interventions aimed at reducing transmission. To accurately estimate the true rate of infection, we have developed a Digital Twin model that simulates the evolution of SARS-CoV-2 infections in Catalonia. Continuous validation plays a crucial role in ensuring the accuracy of our model's predictions. Our system utilizes data from the Catalonia Health Service to quantify detected cases, hospitalizations, and the overall impact on the healthcare system. However, these data are susceptible to under-reporting due to changes in screening policies. To enhance the reliability of our model's forecasts, we incorporate data from the Catalan Surveillance Network of SARS-CoV-2 in Sewage (SARSAIGUA). In this paper, we show how we utilize sewage data in the validation process of the Digital Twin to identify any discrepancies between the model's predictions and real-time data. We outline how this continuous validation approach allows us to generate long-term forecasts and gain insights into the current situation regarding the spread of SARS-CoV-2, enabling us to reassess assumptions and enhance our understanding of the pandemic's behavior in Catalonia., Peer Reviewed, Objectius de Desenvolupament Sostenible::3 - Salut i Benestar, Objectius de Desenvolupament Sostenible::3 - Salut i Benestar::3.3 - Per a 2030, posar fi a les epidèmies de la sida, tuberculosi, malària i les malalties tropicals desateses, i com­batre l’hepatitis, les malalties transmeses per l’aigua i altres malalties transmissibles, Objectius de Desenvolupament Sostenible::3 - Salut i Benestar::3.d - Reforçar la capacitat de tots els països, en particular els països en desenvolupament, en matèria d’alerta primerenca, reducció de riscos i gestió dels riscos per a la salut nacional i mundial, Postprint (published version)

Robert’s rising thermal bubble (RRTB) is a benchmark case used to assess atmospheric models. In this paper, RRTB is further studied both using an analytical and a numerical approach, improving to a greater extent the qualitative description found in the literature. The theoretical framework used is that of buoyant thermals and scaling theory that together are able to predict part of the expected behavior of the bubble as it rises and, therefore, can be used to further validate the simulations. For the numerical experiments, we simulate both a two-dimensional and three-dimensional RRTB using a variety of convection schemes under the Boussinesq approximation and with a higher resolution. While the results are in agreement with those presented by previous authors on the same benchmark and also with the theoretical framework established, we add the quantitative measures to validate the underlying physics of the numerical model. Our results also show that, due to its completely chaotic nature when confined in a 2D plane, RRTB becomes a very challenging candidate to be used as a benchmark if only compared in a qualitative way, and when the 3D bubble is simulated, the shape changes significantly., The authors thankfully acknowledge the computer resources provided by Red Espanola de Super- ˜ computacion (RES) at the institutions of MareNostrum (BSC) ´ (AECT-2019-2-0006, AECT-2020-1-0005) and LaPalma (IAC) (RES-AECT-2021-2-0009), as well as the technical support provided. MAC is supported by the 2022 FI-00335 grant. The authors also thank the anonymous reviewers for their valuable comments. IFAE is partially funded by the CERCA program of the Generalitat de Catalunya., Postprint (author's final draft)

Topology optimization aims to find the best layout of material within a design domain to obtain the best performance, according to specific criteria. In many applications, the objective functional depends on the solution of a partial differential equation (PDE), so these problems may be looked as a PDE-constrained optimization problem of a domain-dependent functional. A method based on a reaction-diffusion equation is presented and applied to the design of a linear elastic structure under a minimum compliance requirement. Topology optimization methods can be sensitive to the discretization of the design space, and suffer from mesh dependency issues. To overcome such drawbacks, this work proposes an anisotropic mesh adaptation technique for the reaction-diffusion based optimization method. Implementing the anisotropic mesh adaptation allows us to deliver a final layout characterized by a smooth contour while significantly reducing the computational cost. Several structural benchmarks are given to demonstrate the validity of the proposed approach. In addition, we perform a sensitivity analysis to some parameters, proving the robustness of the method. We also show that complex designs, characterized by a higher number of inner holes, are feasible with remarkable computational efficiency.

In the present paper, a new strategy of multigrid method is introduced to accelerate the convergence speed of numerical simulations via lattice Boltzmann method. Based on the popular V-cycle multigrid algorithm, a simplified multigrid algorithm is presented and validated through the simulations of the classic lid-driven cavity flow for steady states. The novelty of the present algorithm resides in the construction of the information transferring process, in which, for a full cycle, the numerical simulation starts on the coarse mesh, transferring to medium mesh and then streams to the fine mesh through a prolongation operator. Afterwards, instead of using a restriction operator, the fluid information jumps back directly from the fine mesh to the coarse mesh via an assignment operator. The accuracy and efficiency of the simplified new algorithm are validated by comparing the results obtained when employing the classic V-cycle multigrid algorithm and the traditional lattice Boltzmann method with uniform Cartesian grid, This research was founded by the project provided by the Northwestern Polytechnical University (G2021KY05103). This work was also sponsored by the foundation of National Key Laboratory of Science and Technology on Aerodynamic Design and Research (No. 614220121030101), Postprint (author's final draft)

An OpenFOAM computational fluid dynamics model setup is proposed for simulating thermally driven winds in mountain–valley systems. As a first step, the choice of Reynolds Averaged Navier–Stokes k-e turbulence model is validated on a 3D geometry by comparing its results vs. large-eddy simulations reported in the literature. Then, a numerical model of an idealised 2D mountain–valley system with mountain slope angle of 20° is developed to simulate thermally driven winds. A couple of top surface boundary conditions (BC) and various combinations of temperature initial conditions (IC) are tested. A transient solver for buoyant, turbulent flow of incompressible fluids is used. Contrary to classical approaches where buoyancy is set as a variable of the problem, here temperature linearly dependent with altitude is imposed as BC on the slope and successfully leads to thermally driven wind generation. The minimum fluid domain height needed to properly simulate the thermally driven winds and the effects of the different setups on the results are discussed. Slip wall BC on the top surface of the fluid domain and uniform temperature IC are found to be the most adequate choices. Finally, valleys with different widths are simulated to see how the mountain–valley geometry affects the flow behaviour, both for anabatic (daytime, up-slope) and katabatic (nighttime, down-slope) winds. The simulations correctly reproduce the acceleration and deceleration of the flow along the slope. Increasing the valley width does not significantly affect the magnitude of the thermally driven wind but does produce a displacement of the generated convective cell., This research was funded by AGAUR/Generalitat de Catalunya, with grant number 2017 SGR 1278, and by the Spanish Science and Innovation Ministry (MCIN) within the project TABL4CW, with grant number PID2019-105162RB-I00, funded by MCIN/AEI/10.13039/501100011033., Objectius de Desenvolupament Sostenible::7 - Energia Assequible i No Contaminant, Objectius de Desenvolupament Sostenible::7 - Energia Assequible i No Contaminant::7.2 - Per a 2030, augmentar substancialment el percentatge d’energia renovable en el con­junt de fonts d’energia, Postprint (published version)

This work was supported by the Spanish Ministry of Science and Innovation and the Spanish State Research Agency MCIN/AEI/10.13039/501100011033 (PID2020-113463RB- C33 to M.G., PID2020-113463RB-C32 to A.H., CEX2018-000797-S to A.H. and M.G.). M.G. also acknowledges the support of the Generalitat de Catalunya through the Serra Húnter Programme., Peer Reviewed, Postprint (author's final draft)

Simulation of two-phase flows is relevant for reactor design and safety at normal operation or during accident scenarios. Often, the two-phase flow is in a regime in which slugs are formed or where the flow stratifies. Modeling such situations using standard single-phase Reynolds-averaged Navier-Stokes (RANS) turbulence models fails due to an overestimation of the eddy viscosity at the resolved two-phase interface. To solve this, an ad hoc turbulence damping term has been proposed in the literature that reduces the turbulence production locally at a two-phase interface, analogously to turbulence wall functions. However, this approach must be tailored to the specific setting and does not consider physical contributions such as surface tension or flow topology. Therefore, the problem of two-phase interfacial turbulence must be studied more in-depth. In this work, we consider co-current turbulent Taylor bubble flow using high-fidelity numerical simulation. The Basilisk code is used to simulate a Taylor bubble rising in a vertical pipe. By simulating the bubble in a moving frame of reference, we may study the turbulent kinetic energy (TKE) budgets ahead of the bubble, in its wake, and across the interface. The implementation of the TKE budget computation and the underlying averaging techniques are validated for the single-phase region ahead of the Taylor bubble using reference direct numerical simulation data. The analysis of the TKE budgets in the setting of Taylor bubble flow allows for the study of how turbulence behaves due to the presence of a two-phase interface and, in turn, supports the improvement of two-phase RANS models., This manuscript is co-authored by UChicago Argonne, LLC, Operator of Argonne National Laboratory (“Argonne”). Argonne, a U.S. DOE Office of Science laboratory, is operated under Contract No. DE-AC02-06CH11357., Peer Reviewed, Postprint (author's final draft)

This paper studies the problem of spurious eigensolutions in the context of the singular boundary method (SBM) formulated in the two-and-a-half-dimensional (2.5D) domain and proposes two numerical schemes to overcome this numerical difficulty. The SBM can be seen as a version of the method of fundamental solutions where the source points are located at the physical boundary. Similar to other boundary-type discretization schemes, the SBM also encounters the non-uniqueness problem at the vicinity of the eigensolutions of the corresponding interior problem. In the 2.5D domain framework, the so-called fictitious eigenfrequencies appearing in 3D problems arise in the form of spurious dispersion curves associated with propagation modes of the corresponding interior problem. The two enhanced 2.5D SBM approaches proposed in this work, based on the Burton–Miller method in one case and the dual surface method in the other, are designed to filter out the spurious eigenvalues from the simulation results and deliver accurate solutions along the wavenumber-frequency spectrum. Three benchmark examples including the radiation problems of an infinitely long cylinder under Dirichlet and Neumann boundary conditions and the radiation problem of a longitudinally infinite object with a constant star-like cross section subjected to a Dirichlet boundary condition are considered to study the proposed methods. The results demonstrate the capability of the proposed numerical schemes to successfully avoid the non-uniqueness problem when the 2.5D SBM is employed., Peer Reviewed, Postprint (published version)

La convecció de Rayleigh-Bénard en l'aproximació de Boussinesq ve regida per les equacions de Navier-Stokes, la condició d'incompressibilitat i una tercera equació per a l'energia, que es pot escriure en termes de temperatura. En aquesta dissertació estudiem el cas d'un fluid contingut en un domini rectangular vertical sotmès a escalfament per sota i refredament per dalt. L'objectiu és desenvolupar el mètode pseudoespectral de col·locació amb el qual s'integra el sistema d'equacions en derivades parcials corresponent, explorar-lo en un cert rang d'un dels paràmetres del problema (el nombre de Rayleigh) i trobar-ne els punts de bifurcació.

The version of record is available online at: http://dx.doi.org/10.1007/s00332-022-09882-x, Consider analytic generic unfoldings of the three- dimensional conservative Hopf-zero singularity. Under open conditions on the parameters determining the singularity, the unfolding possesses two saddle-foci when the unfolding parameter is small enough. One of them has one-dimensional stable manifold and two-dimensional unstable manifold, whereas the other one has one- dimensional unstable manifold and two-dimensional stable manifold. Baldomá et al. (J Dyn Differ Equ 25(2):335–392, 2013) gave an asymptotic formula for the distance between the one-dimensional invariant manifolds in a suitable transverse section. This distance is exponentially small with respect to the perturbative parameter, and it depends on what is usually called a Stokes constant. The nonvanishing of this constant implies that the distance between the invariant manifolds at the section is not zero. However, up to now there do not exist analytic techniques to check that condition. In this paper we provide a method for obtaining accurate rigorous computer-assisted bounds for the Stokes constant. We apply it to two concrete unfoldings of the Hopf-zero singularity, obtaining a computer-assisted proof that the constant is nonzero., This project has received funding from the European Research Council (ERC) under the European Union’s Horizon 2020 research and innovation programme (grant agreement No 757802). This work is part of the grants PGC2018-098676-B-100 and PID-2021-122954NB-100 funded by MCIN/AEI/10.13039/501100011033 and “ERDF A way of making Europe.” M. G. and T. M. S. are supported by the Catalan Institution for Research and Advanced Studies via an ICREA Academia Prize 2019. M.C. has been partially supported by the Polish National Science Center (NCN) grants 2019/35/B/ST1/00655 and 2021/41/B/ST1/00407. This work is also supported by the Spanish State Research Agency, through the Severo Ochoa and María de Maeztu Program for Centers and Units of Excellence in R&D (CEX2020-001084-M)., Peer Reviewed, Postprint (author's final draft)

This is an Accepted Manuscript of an article published by Taylor & Francis Group in Soft matter on 29/03/2023, available online at: http://www.tandfonline.com/10.1039/d2sm01326f, Cell migration is a physical process central to life. Among others, it regulates embryogenesis, tissue regeneration, and tumor growth. Therefore, understanding and controlling cell migration represent fundamental challenges in science. Specifically, the ability of cells to follow stiffness gradients, known as durotaxis, is ubiquitous across most cell types. Even so, certain cells follow positive stiffness gradients while others move along negative gradients. How the physical mechanisms involved in cell migration work to enable a wide range of durotactic responses is still poorly understood. Here, we provide a mechanistic rationale for durotaxis by integrating stochastic clutch models for cell adhesion with an active gel theory of cell migration. We show that positive and negative durotaxis found across cell types are explained by asymmetries in the cell adhesion dynamics. We rationalize durotaxis by asymmetric mechanotransduction in the cell adhesion behavior that further polarizes the intracellular retrograde flow and the protruding velocity at the cell membrane. Our theoretical framework confirms previous experimental observations and explains positive and negative durotaxis. Moreover, we show how durotaxis can be engineered to manipulate cell migration, which has important implications in biology, medicine, and bioengineering., P.S acknowledges support from the Spanish Ministry of Economy and Competitiveness (Grant No: PID2019-110949GB-I00) and the Generalitat de Catalunya (Grant No: 2017-SGR-1278). C.V. was supported by the Generalitat de Catalunya (FI grant). P.S and C.V. acknowledge support from the European Commission (Grant No. H2020-FETPROACT-01-2016-731957). We also thank W. Mirza, J.J. Muñoz, and M. Arroyo for discussion., Peer Reviewed, Postprint (author's final draft)

A substantial fraction of the time that computational modellers dedicate to developing their models is actually spent trouble-shooting and debugging their code. However, how this process unfolds is seldom spoken about, maybe because it is hard to articulate as it relies mostly on the mental catalogues we have built with the experience of past failures. To help newcomers to the field of material modelling, here we attempt to fill this gap and provide a perspective on how to identify and fix mistakes in computational solid mechanics models. To this aim, we describe the components that make up such a model and then identify possible sources of errors. In practice, finding mistakes is often better done by considering the symptoms of what is going wrong. As a consequence, we provide strategies to narrow down where in the model the problem may be, based on observation and a catalogue of frequent causes of observed errors. In a final section, we also discuss how one-time bug-free models can be kept bug-free in view of the fact that computational models are typically under continual development. We hope that this collection of approaches and suggestions serves as a “road map” to find and fix mistakes in computational models, and more importantly, keep the problems solved so that modellers can enjoy the beauty of material modelling and simulation., EC and JPP wish to thank their former supervisor Paul Steinmann for the inspiration to write this paper, which can be traced back to the talk we prepared for the ECCM-ECFD conference held in Glasgow in 2018. EC’s work was partially supported by the European Union’s Horizon 2020 research and innovation program under the Marie Skłodowska-Curie grant agreement No 841047. WB’s work was partially supported by the National Science Foundation under award OAC-1835673; by award DMS-1821210; by award EAR-1925595; and by the Computational Infrastructure in Geodynamics initiative (CIG), through the National Science Foundation under Award EAR-1550901 and The University of California – Davis ., Peer Reviewed, Postprint (published version)

The analysis of time series studies linking daily counts of a health indicator with environmental variables (e.g., mortality or hospital admissions with air pollution concentrations or temperature; or motor vehicle crashes with temperature) is usually conducted with Poisson regression models controlling for long-term and seasonal trends using temporal strata. When the study includes multiple zones, analysts usually apply a two-stage approach: first, each zone is analyzed separately, and the resulting zone-specific estimates are then combined using meta-analysis. This approach allows zone-specific control for trends. A one-stage approach uses spatio-temporal strata and could be seen as a particular case of the case–time series framework recently proposed. However, the number of strata can escalate very rapidly in a long time series with many zones. A computationally efficient alternative is to fit a conditional Poisson regression model, avoiding the estimation of the nuisance strata. To allow for zone-specific effects, we propose a conditional Poisson regression model with a random slope, although available frequentist software does not implement this model. Here, we implement our approach in the Bayesian paradigm, which also facilitates the inclusion of spatial patterns in the effect of interest. We also provide a possible extension to deal with overdispersed data. We first introduce the equations of the framework and then illustrate their application to data from a previously published study on the effects of temperature on the risk of motor vehicle crashes. We provide R code and a semi-synthetic dataset to reproduce all analyses presented., We acknowledge support from the grant CEX2018- 000806-S funded by MCIN/AEI/ 10.13039/501100011033, support from Ministry of Research and Universities of the Government of Catalonia (2021 SGR 01563) and support from the Generalitat de Catalunya through the CERCA Program., Peer Reviewed, Postprint (published version)

Technical report, A new method for computing the largest singular value \xi_1 and an associated right singular vector of a large and sparse complex matrix A is developed. The method accelerates a new method for computing \xi_1 and an associated right singular vector which converges from an initial random vector under the only condition that the initial vector has component in the eigenspace of A^HA associated with eigenvalue \xi_1^2, where A^H denotes the transpose conjugate of A. The storage required by the accelerated new method in addition to the storage of A includes for A large and sparse basically the storage of a few complex vectors of the column or row dimension of A. Using two benchmarks of large sparse nonsingular square Hermitian complex matrices with known singular values it is analyzed the accuracy and computational cost of the accelerated new method. Using standard floating-point arithmetic, the accelerated new method is able to compute xi_1 with slightly less than 8 decimal digits of accuracy in the worst case. The new method is in average somewhat faster than a method combining Lanczos without orthogonalization and inverse iteration, which can be regarded as a previous state-of-the-art method for A large and sparse with similar storage requirements as the new method and is very old (it was well understood in the late 70’s)., Postprint (updated version)

Public Bicycle Sharing Systems have spread in many cities for the last decade. The need of analysis tools to predict the behavior or estimate balancing needs has fostered a wide set of approaches that consider many variables. Often, these approaches use a single scenario to evaluate their algorithms, and little is known about the applicability of such algorithms in cities of different sizes. In this paper, we evaluate the performance of widely known prediction algorithms for three sized scenarios: a small system, with around 20 docking stations, a medium-sized one, with 400+ docking stations, and a large one, with more than 1500 stations. The results show that Prophet and Random Forest are the prediction algorithms with more consistent results, and that small systems often have not enough data for the algorithms to perform a solid work., Partially supported by PID2021-122136OB-C21 by Ministerio de Ciencia e Innovación/AEI: (10.13039/501100011033/FEDER, UE), and 2021SGR00613-(ADBD) by Generalitat de Cataluña. The authors would like to thank Logroño City Hall for providing the access to the data., Peer Reviewed, Postprint (published version)

Theoretical and experimental studies on loadbearing masonry walls have shown the significant influence of the axial load level (i.e., precompression) and wall aspect ratio on in-plane lateral resistance. Nonetheless, the impact of the precompression and spatial variability of the material properties needs to be further investigated at the scale of walls with openings. This study presents a stochastic analysis of unreinforced (URM) pier–spandrel systems subjected to both axial loads on piers and lateral loads, considering the spatial variation in material properties. A discontinuum-based computational model was utilized to assess the force–displacement behavior of a benchmark pier–spandrel structure under different vertical precompression levels on piers. A total of 750 simulations were carried out to propagate material uncertainties in lateral load analysis. The proposed modeling strategy, based on the discrete element method, explicitly represents joint openings, sliding, and crushing phenomena at the contact points defined between the adjacent discrete rigid blocks. According to the validated computational modeling strategy, meaningful inferences were made regarding the effect of the precompression level on the maximum displacement and ultimate lateral load-carrying capacity of the benchmark URM pier–spandrel system. The results showed that vertical pressure on piers had considerable influence on the displacement ductility of the system while yielding less variation in the displacement capacity. Furthermore, the appealing feature of the spatial probabilistic analysis is noted in the variation in the lateral load-carrying capacity of the structural system., Peer Reviewed, Postprint (published version)

This thesis presents the development of a research methodology oriented to the analysis of an aircraft structure in terms of operational reliability and maintainability requirements regarding its airworthiness. The study has been focused on modern commercial aircraft models, carrying out a market research and model selection according to different criteria. The study then develops a practical implementation consisting of the design approach of the aircraft airframe and main structural components for its subsequent numerical analysis and simulation. The numerical simulations will be computed by application of the Finite Elements Method on the main structural systems of the aircraft and establishment of boundary conditions. These simulations will allow the development of a computational study on linear, non-linear, and transient simulations of static loads, buckling, modal analysis, temperature, fatigue and thermal stress of individual structures and full assembly in different conditions. Finally, these results will be assessed and exported to a Matlab code which will compute an algorithmic methodology in order to approach the operational reliability and safety of the aircraft in the studied conditions. The thesis will conclude with a review of airworthiness regulations a proposal of research paths and further development of the methodology implemented.

A direct numerical simulation of a three-dimensional diffuser at Reynolds number Re = 10,000 (based on inlet bulk velocity) has been performed using a low-dissipation finite element code. The geometry chosen for this work is the Stanford diffuser, introduced by Cherry et al. (Int. J. Heat Fluid Flow 29:803–811, 2008). Results have been exhaustively compared with the published data with a quite good agreement. Additionally, further turbulent statistics have been provided such as the Reynolds stresses or the turbulent kinetic energy. A proper orthogonal decomposition and a dynamic mode decomposition analyses of the main flow variables have been performed to identify the main characteristics of the large-scale motions. A combined, self-induced movement of the large-scales has been found to originate in the top-right expansion corner with two clear features. A low-frequency diagonal cross-stream travelling wave first reported by Malm et al. (J. Fluid Mech. 699:320–351, 2012), has been clearly identified in the spatial modes of the stream-wise velocity components and the pressure, associated with the narrow band frequency of St¿[0.083,0.01] . This movement is caused by the geometrical expansion of the diffuser in the cross-stream direction. A second low-frequency trait has been identified associated with the persisting secondary flows and acting as a back and forth global accelerating-decelerating motion located on the straight area of the diffuser, with associated frequencies of St<0.005 . The smallest frequency observed in this work has been St=0.0013 . This low-frequency observed in the Stanford diffuser points out the need for longer simulations in order to obtain further turbulent statistics., The research leading to this work has been partially funded by the European Project NextSim which has received funding from the European High-Performance Computing Joint Undertaking (JU) under grant agreement No 956104 and co-founded by the Spanish Agencia Estatal de Investigacion (AEI) under grant agreement PCI2021-121962. Benet Eiximeno also acknowledges the financial support by the Ministerio de Economía y Competitividad, Secretaría de Estado de Investigación, Desarrollo e Innovación, Spain (Refs: PID2020-116937RB-C21 and PID2020-116937RB-C22). Oriol Lehmkuhl has been partially supported by a Ramon y Cajal postdoctoral contract (Ref: RYC2018-025949-I). He also acknowledges the support of the European Project HiFi-TURB which has received funding from the European Union’s Horizon 2020 research and innovation programme under grant agreement No 814837. We also acknowledge the Barcelona Supercomputing Center for awarding us access to the MareNostrum IV machine based in Barcelona, Spain. The authors acknowledge the support of Departament de Recerca i Universitats de la Generalitat de Catalunya to the Research Group Large-scale Computational Fluid Dynamics (Code: 2021 SGR 00902)., Peer Reviewed, Postprint (published version)

This study presents the performance of two fast Monte Carlo codes, PENELOPE/penEasyIR and MCGPU-IR in order to assess operator doses in interventional radiology. In particular, it aims to validate the calculations when workers are protected with shielding located between the patient and the operator. The experiments are performed in a calibration laboratory and measurements are gathered using Thermo EPD and Mirion DMC personal active dosemeters. Calculation efficiency of the fast Monte Carlo codes is approximately four orders of magnitude greater than for a standard Monte Carlo code. Satisfactory agreement between measurements and calculations is shown., This work was partially supported by EJP-CONCERT for 2014–2018 (662287); the Ministerio de Economía y Competitividad (PCIN-2017-044); and the Spanish Nuclear Safety Council through project EDOCI and the ‘Cátedra Argos’., Objectius de Desenvolupament Sostenible::3 - Salut i Benestar, Postprint (author's final draft)

© 2023 Elsevier. This manuscript version is made available under the CC-BY-NC-ND 4.0 license http://creativecommons.org/licenses/by-nc-nd/4.0, Background Intra-arterial thrombectomy is the main treatment for acute ischemic stroke due to large vessel occlusions and can consist in mechanically removing the thrombus with a stent-retriever. A cause of failure of the procedure is the fragmentation of the thrombus and formation of micro-emboli, difficult to remove. This work proposes a methodology for the creation of a low-dimensional surrogate model of the mechanical thrombectomy procedure, trained on realizations from high-fidelity simulations, able to estimate the evolution of the maximum first principal strain in the thrombus. Method A parametric finite-element model was created, composed of a tapered vessel, a thrombus, a stent-retriever and a catheter. A design of experiments was conducted to sample 100 combinations of the model parameters and the corresponding thrombectomy simulations were run and post-processed to extract the maximum first principal strain in the thrombus during the procedure. Then, a surrogate model was built with a combination of principal component analysis and Kriging. Results The surrogate model was chosen after a sensitivity analysis on the number of principal components and was tested with 10 additional cases. The model provided predictions of the strain curves with correlation above 0.9 and a maximum error of 28%, with an error below 20% in 60% of the test cases. Conclusions The surrogate model provides nearly instantaneous estimates and constitutes a valuable tool for evaluating the risk of thrombus rupture during pre-operative planning for the treatment of acute ischemic stroke., Peer Reviewed, Postprint (author's final draft)

L'objectiu d'aquest treball és l'estudi de la forma d'una única cèl·lula respectant alguns paràmetres presentats en el funcional d'energia, així com l'anàlisi de sistemes de dues cèl·lules, s'imposin o no condicions de simetria. Es mostren diversos resultats sobre l'existència de valors límit i contrastant els resultats amb els models numèrics., El objetivo de este trabajo es estudiar la forma de una sola célula respetando algunos parámetros presentados en el funcional de energía, así como el análisis de sistemas de dos células, se impongan o no condiciones de simetría. Se muestran diversos resultados abordando la existencia de valores límite, y contrastando los resultados con los modelos numéricos., The aim of this work is to study the shape of a single cell respect some parameters presented in the energy functional, as well as the analysis of systems of two cells, whether symmetrical conditions are imposed or not. It is shown various results addressing the existence of limit values, and contrasting the results with the numerical models.

The version of record of this article, first published in Results in Mathematics, is available online at Publisher’s website: http://dx.doi.org/10.1007/s00025-023-01902-w, We study the concept of the continuous mean distance of a weighted graph. For connected unweighted graphs, the mean distance can be defined as the arithmetic mean of the distances between all pairs of vertices. This parameter provides a natural measure of the compactness of the graph, and has been intensively studied, together with several variants, including its version for weighted graphs. The continuous analog of the (discrete) mean distance is the mean of the distances between all pairs of points on the edges of the graph. Despite being a very natural generalization, to the best of our knowledge this concept has been barely studied, since the jump from discrete to continuous implies having to deal with an infinite number of distances, something that increases the difficulty of the parameter. In this paper, we show that the continuous mean distance of a weighted graph can be computed in time roughly quadratic in the number of edges, by two different methods that apply fundamental concepts in discrete algorithms and computational geometry. We also present structural results that allow for a faster computation of this continuous parameter for several classes of weighted graphs. Finally, we study the relation between the (discrete) mean distance and its continuous counterpart, mainly focusing on the relevant question of convergence when iteratively subdividing the edges of the weighted graph., Peer Reviewed, Postprint (published version)

Los mecanismos de transporte de basura marina flotante en zonas costeras no se conocen bien, y su seguimiento con modelos numéricos es complejo debido a la geometría, procesos hidrodinámicos y la influencia de los procesos costeros, con estos últimos siendo especialmente complicados de incorporar. La herramienta LOCATE fue desarrollada para simular el movimiento y la acumulación de partículas de plástico en zonas costeras, usando mallas anidadas de diferentes resoluciones y escalas espaciales (2,5 km, 350 m y 70 m) para tener en cuenta los procesos costeros. La herramienta LOCATE acopla datos hidrodinámicos eulerianos con un modelo lagrangiano, requiriendo configuración y optimización para un funcionamiento adecuado. El modelo ha sido aplicado a la costa de Barcelona donde la geometría de costa y procesos costeros pueden actuar como acumuladores de basura y las concentraciones encontradas son comparables a otras zonas altamente contaminadas., Transport mechanisms of floating marine litter (FML) in coastal zones are poorly understood. Tracking FML dispersion with numerical models is complex due to the geometry, hydrodynamic processes and the influence of coastal processes, the latter being especially challenging to incorporate. The LOCATE tool was developed to simulate the motion and accumulation of plastic particles in coastal areas, using nested grids of varying spatial scales and resolutions (2.5 km, 350 m and 70 m) to account for coastal processes. LOCATE couples Eulerian hydrodynamic data with a Lagrangian particle solver, thus requiring configuration and optimization. As proof of concept, the model has been applied to the Barcelona coastline where the coastal geometry and processes can behave as marine litter traps and concentrations are comparable to some other heavily polluted areas.

The Southern Atlantic-Southwest Indian ridges (SASWIR) host mid-ocean ridge basalts with a residual subduction-related geochemical fingerprint (i.e., a ghost-arc signature) of unclear origin. Here, we show through an analysis of plate kinematic reconstructions and seismic tomography models that the SASWIR subduction-modified mantle source formed in the Jurassic close to the Georgia Islands slab (GI) and remained near-stationary in the mantle reference frame. In this analysis, the GI lies far inboard the Jurassic Patagonian-Antarctic Peninsula active margin. This was formerly attributed to a large-scale flat subduction event in the Late Triassic-Early Jurassic. We propose that during this flat slab stage, the subduction-modified mantle areas beneath the Mesozoic active margin and surrounding sutures zones may have been bulldozed inland by >2280 km. After the demise of the flat slab, this mantle anomaly remained near-stationary and was sampled by the Karoo mantle plume 183 Million years (Myr) ago and again since 55 Myr ago by the SASWIR. We refer to this process as asthenospheric anomaly telescoping. This study provides a hitherto unrecognized geodynamic effect of flat subduction, the viability of which we support through numerical modeling., G. M. G. and C. R. N. recognize the support given by CONICET and the funding given by the Universidad Nacional de la Patagonia San Juan Bosco (Grant number: CIUNPAT no. 1399). S. Z. and J. L. acknowledge the funding from the European Union’s Horizon 2020 research and innovation programme under the Marie Sklodowska-Curie grant agreement No 777778. S.Z. acknowledges the funding of Project PID2020-113463RB-C32 funded by MCIN/AEI /10.13039/501100011033 and the funding of Generalitat de Catalunya via the 2021 SGR 01049., Peer Reviewed, Postprint (published version)

Numerous simplified numerical models have been established to optimize the ball burnishing of steel surfaces. Nevertheless, their conceptualization has not considered the tool–part interaction, leading to an unsatisfactory process parameterization. As a solution, a structured numerical simulation has been defined that reproduces this interaction by several friction coefficient approximations. This study provides the tribological process inputs (friction and initial surface conditions) to this model, adapting it to a pre-textured martensitic precipitation hardening stainless-steel. Results show the versatility of the model to reproduce the surface integrity alterations. Hence, this consistent model configuration can be postulated as an economical and efficient approach to tackle ball burnishing parameterization according to the applicability of the manufactured steel parts., Peer Reviewed, Objectius de Desenvolupament Sostenible::9 - Indústria, Innovació i Infraestructura, Postprint (published version)

Els temporals de mar són fenòmens naturals que tenen repercussions econòmiques, personals, físiques i socials importants sobre el litoral. Durant les darreres dècades, aquests fenòmens han provocat de manera creixent un greu deteriorament del litoral català, on l'estat del mar és el principal factor. Per poder estudiar l'impacte que podria causar el fort onatge provocat pels temporals a les infraestructures costaneres i, en general, per a problemes relacionats amb l'enginyeria costanera, s'ha desenvolupat el model numèric DualSPHysics, basat en el mètode d'hidrodinàmica de partícules suavitzades, conegut com a “SPH” (Smoothed Particle Hydrodynamics). Des del seu llançament el 2011, DualSPHysics s'ha utilitzat per obtenir una resposta davant de les adversitats que podem trobar a l'àmbit de l'enginyeria marítima i costanera. En aquest projecte s'emprarà el mètode d'hidrodinàmica de partícules suavitzades (SPH) amb el propòsit de crear un cas on es pugui observar el moviment i la força a què se sotmet un objecte proper a la costa, quan aquest és copejat per una onada en condicions extremes o de tempesta. També determinar si aquest moviment de l'objecte podria suposar algun perill per a altres estructures o objectes, com ara una via del tren. A més de calcular la força exercida de l'onada sobre l'objecte., Los temporales de mar son fenómenos naturales que tienen repercusiones económicas, personales, físicas y sociales importantes sobre el litoral. Durante las últimas décadas estos fenómenos han provocado de forma creciente un grave deterioro del litoral catalán, donde el estado del mar es el principal factor. Para poder estudiar el impacto que podría causar el fuerte oleaje provocado por los temporales a las infraestructuras costeras y en general, para problemas relacionados con la ingeniería costera, se ha desarrollado el modelo numérico DualSPHysics, basado en el método de hidrodinámica de partículas suavizadas, conocido como “SPH” (Smoothed Particle Hydrodynamics). Desde su lanzamiento en 2011, DualSPHysics se ha utilizado para obtener una respuesta frente a las adversidades que podemos encontrar en el ámbito de la ingeniería marítima y costera. En este proyecto se empleará el método de hidrodinámica de partículas suavizadas (SPH) con el propósito de crear un caso donde se pueda observar el movimiento y la fuerza a la que se somete un objeto cercano a la costa, cuando éste es golpeado por una ola en condiciones extremas o de tormenta. También determinar si dicho movimiento del objeto podría suponer algún peligro para otras estructuras u objetos, como por ejemplo una vía del tren. Además de calcular la fuerza ejercida de la ola sobre el objeto., Sea storms are natural phenomena that have important economic, personal, physical and social repercussions on the coastline. Over the last few decades, these phenomena have increasingly caused serious deterioration of the Catalan coast, where the state of the sea is the main factor. In order to study the impact that strong waves caused by storms could cause to coastal infrastructure and in general, for problems related to coastal engineering, the DualSPHysics numerical model has been developed, based on the smoothed particle hydrodynamics method, known as “SPH” (Smoothed Particle Hydrodynamics). Since its launch in 2011, DualSPHysics has been used to obtain a response to the adversities that we can encounter in the field of maritime and coastal engineering. In this project, the smoothed particle hydrodynamics (SPH) method will be used with the purpose of creating a case where the movement and force to which an object near the coast is subjected, when it is hit by a wave, can be observed. in extreme or storm conditions. Also determine if said movement of the object could pose a danger to other structures or objects, such as a train track. In addition to calculating the force exerted by the wave on the object.

The version of record is available online at: http://dx.doi.org/10.1007/s40840-023-01582-3, The metric representation of a vertex u in a connected graph G respect to an ordered vertex subset is the vector of distances . A vertex subset W is a resolving set of G if , for every with . Thus, a resolving set with n elements provides a set of metric representation vectors with cardinal equal to the order of the graph. In this paper, we address the reverse point of view; that is, we characterize the finite subsets that are realizable as the set of metric representation vectors of a graph G with respect to some resolving set W. We also explore the role that the strong product of paths plays in this context. Moreover, in the case , we characterize the sets that are uniquely realizable as the set of metric representation vectors of a graph G with respect to a resolving set W., This work was partially supported by the grants of the Spanish Ministry of Science and Innovation PID2021-123278OB-I00 and PID2019-104129GB-I00, both funded by MCIN/AEI/10.13039/501100011033 and by “ERDF A way of making Europe”, and Gen. Cat. DGR 2021-SGR-00266., Peer Reviewed, Postprint (author's final draft)

Los deslizamientos de tipo flujo representan un fenómeno geológico con gran potencial destructivo. La transformación a un flujo es un proceso complejo ya que puede desarrollarse con rapidez, incrementando su capacidad destructiva. El presente estudio analiza el caso particular del deslizamiento del Vielha, que tuvo lugar en junio del 2013. Para el análisis se realiza una modelación numérica con el objetivo de reproducir el evento y analizar las causas y condiciones en las que se produjo el deslizamiento. Se realiza un análisis integral que combina un análisis morfológico y ensayos de laboratorio que, conjuntamente crean el modelo numérico. El análisis morfológico basado en modelos DEM (Modelo de Elevación Digital) y datos LiDAR (Laser Imaging Detection and Ranging), permite la comparación entre dos perfiles topográficos, pre y post rotura, demostrando una diferencia de cota de 2.8 metros entre ambas. Por otro lado, los ensayos de laboratorio clasifican dos unidades geotécnicas; arena limosa (SM) para el estrato superior y arena arcillosa (SC) para el estrato inferior, este último se encuentra en contacto con la roca, que es de origen devónico y compuesto por calizas y pizarras. Además presentan un ángulo de fricción residual de los suelos de 23° y 24 ° respectivamente. El modelo numérico es desarrollado en el software de elementos finitos PLAXIS 2D, el cual usa la información del análisis morfológico y los ensayos de laboratorio para la creación de 3 modelos numéricos. La diferencia entre los modelos es el espesor de estrato de cada uno de ellos, a los cuales posteriormente se aplicarán cinco escenarios diferentes con el fin de obtener una simulación del evento ocurrido. Los escenarios reproducen el comportamiento en 1) condiciones residuales, 2) condiciones secas, 3) con nivel freático, 4) con precipitación y 5) succión. Bajo estas condiciones los modelos revelan la influencia del agua por efectos del nivel freático y de precipitación, que tienen implicación en el, Flow-type landslides represent a geological phenomenon with significant destructive potential. The transformation into a flow is a complex process, as it can develop rapidly, increasing its destructive capacity. This study examines the specific case of the Vielha landslide, which occurred in June 2013. For the analysis, numerical modelling is conducted with the aim of reproducing the event and analyzing the causes and conditions under which the landslide occurred. An integrated analysis is performed that combines morphological analysis and laboratory tests, which together create the numerical model. The morphological analysis, based on Digital Elevation Models (DEMs) and Light Detection and Ranging (LiDAR) data, allows for a comparison between two topographic profiles, one before and one after the landslide, demonstrating a difference in elevation of 2.8 meters between them. On the other hand, laboratory tests classify two geotechnical units: silty sand (SM) for the upper layer and clayey sand (SC) for the lower layer, which is in contact with bedrock originating from the Devonian period and composed of limestone and shale. Additionally, the soils exhibit a residual friction angle of 23° and 24°, respectively. The numerical model is developed using the finite element software PLAXIS 2D, which utilizes information from the morphological analysis and laboratory tests to create three numerical models. The difference between these models lies in the thickness of the strata in each of them. Subsequently, five different scenarios are applied to these models to obtain a simulation of the event that occurred. These scenarios replicate behaviour under 1) residual conditions, 2) dry conditions, 3) with a water table, 4) with precipitation, and 5) suction. Under these conditions, the models reveal the influence of water due to the effects of the water table and precipitation, which have implications for the behaviour of the landslide. Together with geomorphological conditions

The geodynamic evolution of the Western Mediterranean related to the closure of the LigurianTethys ocean is not yet fully resolved. We present a new 3D numerical model of double subduction with opposite polarities fostered by the inherited segmentation of the Ligurian-Tethys margins and rifting system between Iberia and NW Africa. The model is constrained by plate kinematic reconstructions and assumes that both Alboran-Tethys and Algerian-Tethys plate segments are separated by a NW-SE transform zone enabling that subduction polarity changes from SE-dipping in the Alboran-Tethys segment to NW-dipping in the Algerian-Tethys segment. The model starts about late Eocene times at 36.5 Ma and the temporal evolution of the simulation is tied to the geological evolution by comparing the rates of convergence and trench retreat, and the onset and end of opening in the Alboran Basin. Curvature of the Alboran-Tethys slab is imposed by the pinning of its western edge when reaching the end of the transform zone in the adjacent westAfrica continental block. The progressive curvature of the trench explains the observed regional stress reorientation changing from N-S to NW-SE and to E-W in the central and western regions of the Alboran Basin. The increase of the retreat rates from the Alboran-Tethys to the Algerian-Tethys slabs is compatible with the west-to-east transition from continental-to-magmatic-to-oceanic crustal nature and with the massive and partially synchronous calc-alkaline and alkaline magmatism., Peer Reviewed, Postprint (published version)