Ponències/Comunicacions de congressos
http://hdl.handle.net/2117/79697
2024-03-29T15:06:50Z
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Energy performance of ventilated façades: assessment of the steady-state and transient calculation approaches
http://hdl.handle.net/2117/405006
Energy performance of ventilated façades: assessment of the steady-state and transient calculation approaches
Roig Mayoral, Oriol; Pardal March, Cristina; Isalgué Buxeda, Antonio; Paricio Ansuátegui, Ignacio
The ventilated façade is a construction system that can prevent sunny façades from overheating. It can also be used on existing buildings as an energy rehabili-tation system, which is so necessary to make the built environment more climate resilient.
The usual systems used by architects to calculate the energy performance of the architectural enclosures consider the façade in nearly steady-state conditions, with an energy balance. In addition, they disregard the particularities of the venti-lated façade. Therefore, they cannot give accurate information about the actual thermal performance of the façade. Thus, architects lack the tools to know, in a straightforward way, the real energy performance of the designed façade and how it is affected by different design decisions.
The daily evolution of temperatures has been measured at different points of a ventilated façade. Also, a calculation system has been developed. It considers the defining parameters of the measured façade, the geometry of the environment, and the meteorological conditions. It can compute the ventilation of the cavity and the thermal performance, both in steady-state and transient conditions.
In this presentation, the measured temperatures are compared with those re-sulting from the two types of calculation: steady-state and transient. The objective is to check which one is more appropriate in order to provide a reliable design tool for architects and designers.
2024-03-20T10:49:17Z
Roig Mayoral, Oriol
Pardal March, Cristina
Isalgué Buxeda, Antonio
Paricio Ansuátegui, Ignacio
The ventilated façade is a construction system that can prevent sunny façades from overheating. It can also be used on existing buildings as an energy rehabili-tation system, which is so necessary to make the built environment more climate resilient.
The usual systems used by architects to calculate the energy performance of the architectural enclosures consider the façade in nearly steady-state conditions, with an energy balance. In addition, they disregard the particularities of the venti-lated façade. Therefore, they cannot give accurate information about the actual thermal performance of the façade. Thus, architects lack the tools to know, in a straightforward way, the real energy performance of the designed façade and how it is affected by different design decisions.
The daily evolution of temperatures has been measured at different points of a ventilated façade. Also, a calculation system has been developed. It considers the defining parameters of the measured façade, the geometry of the environment, and the meteorological conditions. It can compute the ventilation of the cavity and the thermal performance, both in steady-state and transient conditions.
In this presentation, the measured temperatures are compared with those re-sulting from the two types of calculation: steady-state and transient. The objective is to check which one is more appropriate in order to provide a reliable design tool for architects and designers.
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Thermo-hydro-mechanical behaviour of deep Ypresian clays
http://hdl.handle.net/2117/403921
Thermo-hydro-mechanical behaviour of deep Ypresian clays
Sau Valenzuela, Núria; Romero Morales, Enrique Edgar; Van Baelen, H
Investigating the thermo-hydro-mechanical behaviour of deep Ypresian clays (300 to 400 m below ground) is crucial
since they are one of Belgium’s potential host rock formations for deep geological disposal of radioactive waste. To this
aim, a newly designed and fully instrumented thermal oedometer cell with lateral stress measurement was used to
determine the stress state accurately. First, well-preserved core samples were loaded to bring them to the large in situ
stresses and reduce the induced matric suction on deep water-undrained sampling. The remaining matric suction was then
reduced by soaking with synthetic water of the formation. Next, drained loading and unloading paths were followed to
attain different vertical effective stresses at varying overconsolidation ratios (OCRs) before the drained thermal paths
(heating and cooling). The results indicated a systematic increase in the horizontal effective stress on heating at constant
vertical effective stress. In addition, thermal-induced volume changes in heating/cooling at different OCRs were studied.
Test results were finally interpreted within a thermo-mechanical elastoplastic framework.
2024-03-07T11:52:45Z
Sau Valenzuela, Núria
Romero Morales, Enrique Edgar
Van Baelen, H
Investigating the thermo-hydro-mechanical behaviour of deep Ypresian clays (300 to 400 m below ground) is crucial
since they are one of Belgium’s potential host rock formations for deep geological disposal of radioactive waste. To this
aim, a newly designed and fully instrumented thermal oedometer cell with lateral stress measurement was used to
determine the stress state accurately. First, well-preserved core samples were loaded to bring them to the large in situ
stresses and reduce the induced matric suction on deep water-undrained sampling. The remaining matric suction was then
reduced by soaking with synthetic water of the formation. Next, drained loading and unloading paths were followed to
attain different vertical effective stresses at varying overconsolidation ratios (OCRs) before the drained thermal paths
(heating and cooling). The results indicated a systematic increase in the horizontal effective stress on heating at constant
vertical effective stress. In addition, thermal-induced volume changes in heating/cooling at different OCRs were studied.
Test results were finally interpreted within a thermo-mechanical elastoplastic framework.
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Stabilization of microlasers by non-Hermitian potentials
http://hdl.handle.net/2117/403892
Stabilization of microlasers by non-Hermitian potentials
Herrero Simon, Ramon; Botey Cumella, Muriel; Benadouda Ivars, Salim; Akhter, Mohammad Nayeem; Staliunas, Kestutis
Vertical-cavity semiconductor lasers as well as single units or arrays of Edge Emitting Lasers suffer from dynamical spatiotemporal instabilities leading to temporally unstable and low spatial beam quality. We propose a feasible stabilization mechanism for microlasers based on periodic non-Hermitian potentials, i.e. simultaneous modulations of refractive index and gain-loss. The proposed spatiotemporal modulations can be introduced by a potential directly acting on the field or by carrier modulations. The stabilization effect is based either on the suppression of the modulation instability or on asymmetric couplings in the transverse direction to localize and stabilize the field.
Copyright (2023) Society of Photo‑Optical Instrumentation Engineers (SPIE). One print or electronic copy may be made for personal use only. Systematic reproduction and distribution, duplication of any material in this publication for a fee or for commercial purposes, and modification of the contents of the publication are prohibited.
2024-03-06T15:53:48Z
Herrero Simon, Ramon
Botey Cumella, Muriel
Benadouda Ivars, Salim
Akhter, Mohammad Nayeem
Staliunas, Kestutis
Vertical-cavity semiconductor lasers as well as single units or arrays of Edge Emitting Lasers suffer from dynamical spatiotemporal instabilities leading to temporally unstable and low spatial beam quality. We propose a feasible stabilization mechanism for microlasers based on periodic non-Hermitian potentials, i.e. simultaneous modulations of refractive index and gain-loss. The proposed spatiotemporal modulations can be introduced by a potential directly acting on the field or by carrier modulations. The stabilization effect is based either on the suppression of the modulation instability or on asymmetric couplings in the transverse direction to localize and stabilize the field.
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Non-Hermitian modulations for stabilization of VCSEL, EEL and EEL arrays
http://hdl.handle.net/2117/403740
Non-Hermitian modulations for stabilization of VCSEL, EEL and EEL arrays
Herrero Simon, Ramon; Benadouda Ivars, Salim; Botey Cumella, Muriel; Staliunas, Kestutis
Semiconductor lasers and laser arrays emit temporally unstable and low spatial quality beams associated to intrinsic dynamical spatiotemporal instabilities. W e propose the simultaneous modulations of refractive index and gain-loss generating non-Hermitian potentials as a stabilization mechanism. Toe proposed spatiotemporal modulations are introduced by directly acting on field and carriers. The stabilization is based on the stabilization of specific stationary solutions or on field localization. Stabilization is shown for VCSELs, EELs and EEL arrays.
2024-03-05T14:21:54Z
Herrero Simon, Ramon
Benadouda Ivars, Salim
Botey Cumella, Muriel
Staliunas, Kestutis
Semiconductor lasers and laser arrays emit temporally unstable and low spatial quality beams associated to intrinsic dynamical spatiotemporal instabilities. W e propose the simultaneous modulations of refractive index and gain-loss generating non-Hermitian potentials as a stabilization mechanism. Toe proposed spatiotemporal modulations are introduced by directly acting on field and carriers. The stabilization is based on the stabilization of specific stationary solutions or on field localization. Stabilization is shown for VCSELs, EELs and EEL arrays.
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Stabilization of laser emission by non-Hermitian potentials
http://hdl.handle.net/2117/403701
Stabilization of laser emission by non-Hermitian potentials
Herrero Simon, Ramon; Benadouda Ivars, Salim; Botey Cumella, Muriel; Staliunas, Kestutis
Light emission from single lasers and laser arrays can suffer from dynamical spatiotemporal instabilities leading to emitted beams temporally unstable and with low spatial quality. We propose a feasible stabilization mechanism for laser emission based on non-Hermitian potentials, i.e. simultaneous modulations of refractive index and gain-loss. The proposed spatiotemporal modulations can be introduced by potentials directly acting on the field or on carriers. The stabilization can be based on the suppression of the modulation instability, on the stabilization of specific stationary solutions or on field localization. These stabilization mechanisms are applied in vertical-cavity semiconductor lasers, single units and arrays of Edge Emitting Lasers.
© 20XX IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses, in any current or future media, including reprinting/republishing this material for advertising or promotional purposes, creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other works.
2024-03-04T17:12:35Z
Herrero Simon, Ramon
Benadouda Ivars, Salim
Botey Cumella, Muriel
Staliunas, Kestutis
Light emission from single lasers and laser arrays can suffer from dynamical spatiotemporal instabilities leading to emitted beams temporally unstable and with low spatial quality. We propose a feasible stabilization mechanism for laser emission based on non-Hermitian potentials, i.e. simultaneous modulations of refractive index and gain-loss. The proposed spatiotemporal modulations can be introduced by potentials directly acting on the field or on carriers. The stabilization can be based on the suppression of the modulation instability, on the stabilization of specific stationary solutions or on field localization. These stabilization mechanisms are applied in vertical-cavity semiconductor lasers, single units and arrays of Edge Emitting Lasers.
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Complex time dependent patterns in the Soret regime
http://hdl.handle.net/2117/402323
Complex time dependent patterns in the Soret regime
Alonso Maleta, María Aránzazu; Mercader Calvo, María Isabel; Batiste Boleda, Oriol
2024-02-20T17:29:20Z
Alonso Maleta, María Aránzazu
Mercader Calvo, María Isabel
Batiste Boleda, Oriol
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Correlation between ionosphere scintillation and earthquakes around Coral Sea in 2022
http://hdl.handle.net/2117/401942
Correlation between ionosphere scintillation and earthquakes around Coral Sea in 2022
Carvajal Librado, Mireia; Molina Ordóñez, Carlos; Boudriki Semlali, Badr Eddine; Hyuk, Park; Camps Carmona, Adriano José
Lithosphere-Atmosphere-Ionosphere coupling models have been widely studied and applied to earthquakes and their potential precursors. Recent evidence has been found that electromagnetic phenomena related to earthquakes might produce ionospheric anomalies even before their occurrence. This study analyzes their correlation focusing on the ionospheric scintillation associated to seismic activities in 2022 in the area around the Coral Sea. Among all the ionospheric indicators, this study analyzes the S 4 scintillation index from COSMIC-2 GNSS Radio Occultation (GNSS-RO), to estimate the ionospheric perturbation and identify anomalies. Two cases of earthquakes in 2022 with magnitudes larger than 6 are presented showing the positive correlation between the ionospheric scintillation and earthquake precursors.
2024-02-15T07:53:08Z
Carvajal Librado, Mireia
Molina Ordóñez, Carlos
Boudriki Semlali, Badr Eddine
Hyuk, Park
Camps Carmona, Adriano José
Lithosphere-Atmosphere-Ionosphere coupling models have been widely studied and applied to earthquakes and their potential precursors. Recent evidence has been found that electromagnetic phenomena related to earthquakes might produce ionospheric anomalies even before their occurrence. This study analyzes their correlation focusing on the ionospheric scintillation associated to seismic activities in 2022 in the area around the Coral Sea. Among all the ionospheric indicators, this study analyzes the S 4 scintillation index from COSMIC-2 GNSS Radio Occultation (GNSS-RO), to estimate the ionospheric perturbation and identify anomalies. Two cases of earthquakes in 2022 with magnitudes larger than 6 are presented showing the positive correlation between the ionospheric scintillation and earthquake precursors.
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A neural network approach to predict the ionospheric scintillation Wbmod model variables
http://hdl.handle.net/2117/401746
A neural network approach to predict the ionospheric scintillation Wbmod model variables
Molina Ordóñez, Carlos; Boudriki Semlali, Badr Eddine; Hyuk, Park; Camps Carmona, Adriano José
The ionospheric scintillation can be explained as the fluctuations in the phase and intensity of electromagnetic rays after crossing the ionosphere. Rino’s theory was proposed in 1979 to quantify this scintillation, and subsequent models appeared to predict its characteristics. One of them is the WideBand ionospheric scintillation Model (WBMOD) from 1984. This study aims to provide a neural network that emulates the behavior of WBMOD model, by learning from phase and intensity scintillation data gathered from several ESA projects. By using the Rino’s power-law phase-screen ionospheric scintillation theory, the values of the height-integrated irregularities strength (C k L) and the slope of its PSD (q) can be obtained from the physically measured S 4 and σ ϕ . So, using this data, two neural networks are presented which obtains results that fit well with the WBMOD expected values.
2024-02-13T08:07:59Z
Molina Ordóñez, Carlos
Boudriki Semlali, Badr Eddine
Hyuk, Park
Camps Carmona, Adriano José
The ionospheric scintillation can be explained as the fluctuations in the phase and intensity of electromagnetic rays after crossing the ionosphere. Rino’s theory was proposed in 1979 to quantify this scintillation, and subsequent models appeared to predict its characteristics. One of them is the WideBand ionospheric scintillation Model (WBMOD) from 1984. This study aims to provide a neural network that emulates the behavior of WBMOD model, by learning from phase and intensity scintillation data gathered from several ESA projects. By using the Rino’s power-law phase-screen ionospheric scintillation theory, the values of the height-integrated irregularities strength (C k L) and the slope of its PSD (q) can be obtained from the physically measured S 4 and σ ϕ . So, using this data, two neural networks are presented which obtains results that fit well with the WBMOD expected values.
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A comparison of methodologies for pulmonary veins segmentation in high definition voltage maps of patients with atrial fibrillation
http://hdl.handle.net/2117/401542
A comparison of methodologies for pulmonary veins segmentation in high definition voltage maps of patients with atrial fibrillation
Moriones, Leire; Gonzalez, Iker; Echebarría Domínguez, Blas; Ravassa, Susana; Ibero, Javier; García Bolao, Ignacio; Bragard, Jean
This paper compares three methodologies used to seg- ment images extracted from the atria of patients with atrial fibrillation (AF). We collected voltage maps of 120 pa- tients’ left atrium before being treated for AF with tissue ablation. The high-definition voltage maps (HDVM) were extracted with the Rythmia software system from Boston Scientific and subsequently analyzed offline in MATLAB. During the analysis, the atrium is segmented into three main structures: body, pulmonary veins (PVs), and mitral valve (MV). Method I is based on a manual elimination of the PV by the operator. Method II uses a semi-automatic method based on geometric considerations coupled with a thresh- old for voltage value. Method III, in addition, uses geo- metric features, i.e., the geometric curvature, to eliminate the maps’ PVs. We quantitatively compare the two first methods’ effi- ciency and ease of use. In particular, the values of two electrical biomarkers associated with the maps are com- puted before and after the PV’s elimination process. This allows us to classify them according to their sensitivity with respect to the cleaning of the PVs. Finally, we discuss which methodology is more adequate to perform the PVs and MV segmentation in light of im- proving the precision of the resulting maps.
2024-02-08T19:02:59Z
Moriones, Leire
Gonzalez, Iker
Echebarría Domínguez, Blas
Ravassa, Susana
Ibero, Javier
García Bolao, Ignacio
Bragard, Jean
This paper compares three methodologies used to seg- ment images extracted from the atria of patients with atrial fibrillation (AF). We collected voltage maps of 120 pa- tients’ left atrium before being treated for AF with tissue ablation. The high-definition voltage maps (HDVM) were extracted with the Rythmia software system from Boston Scientific and subsequently analyzed offline in MATLAB. During the analysis, the atrium is segmented into three main structures: body, pulmonary veins (PVs), and mitral valve (MV). Method I is based on a manual elimination of the PV by the operator. Method II uses a semi-automatic method based on geometric considerations coupled with a thresh- old for voltage value. Method III, in addition, uses geo- metric features, i.e., the geometric curvature, to eliminate the maps’ PVs. We quantitatively compare the two first methods’ effi- ciency and ease of use. In particular, the values of two electrical biomarkers associated with the maps are com- puted before and after the PV’s elimination process. This allows us to classify them according to their sensitivity with respect to the cleaning of the PVs. Finally, we discuss which methodology is more adequate to perform the PVs and MV segmentation in light of im- proving the precision of the resulting maps.
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OpenFOAM numerical analysis of the diurnal cycle of thermally-driven winds on Mars
http://hdl.handle.net/2117/399667
OpenFOAM numerical analysis of the diurnal cycle of thermally-driven winds on Mars
Arias Calderón, Santiago; Rojas Gregorio, José Ignacio; Villardi de Montlaur, Adeline de
The study of Martian winds holds significant scientific interest and potential practical applications. For instance, understanding the dynamics and behaviour of Martian winds is crucial in order to properly evaluate and select landing sites for missions to Mars [1]. The study of wind patterns is also critical in determining the capacity of Martian winds to remove dust from solar panels, thereby improving their performance and longevity [2]. Furthermore, Martian winds' effects on dust are fundamental to comprehending the planet's weather and climate [3], and finally, studying regional-scale sand transport and dune formation can contribute to gain a deeper understanding of Martian geological processes [4]. Therefore, the investigation of Martian winds represents a multidisciplinary approach with meaningful repercussions for planetary science and space exploration.
This work focuses on analysing the formation of thermally-driven winds, which are typically observed in inclined regions, examining their implications for the production of renewable wind energy. While wind energy may not be ideal for initial stages of human settlement on Mars, due mainly to the low density of the Martian atmosphere, it has the potential to serve as a renewable energy source in the long term and as a backup for solar energy [5]. Thermally-driven winds can attain considerably high velocities for steep slopes (values of up to 17 m/s [6]), exerting a dominant influence on the near-surface wind. The study of maximum velocities (Fig. 1) and the heights at which these velocities typically occur could be of particular interest for determining the optimal placement of wind energy resources (such as wind turbines) for future energy production on planet Mars.
Within the scope of this study, 2D simulations of slope winds on Mars are achieved using the open source computational fluid dynamics (CFD) code OpenFOAM. Several slope angles (ranging from 5º up to 20º) are considered. Following [7], the incompressible Navier-Stokes equations with Boussinesq approximation with a conventional k–e turbulence model are used. The impact of slope angle on the creation of thermal winds for both anabatic (up-slope) and katabatic (down-slope) flows is analysed: velocity and temperature profiles are presented for each slope angle along with the position of the maximum velocity. The numerical simulations shown in this work can serve as a cost-effective initial approximation, particularly when evaluating numerous configurations, while computationally more expensive techniques like Large Eddy Simulations (LES) or Direct Numerical Simulations (DNS) could be used in the future for validation and further exploration of final configurations.
2024-01-17T11:05:02Z
Arias Calderón, Santiago
Rojas Gregorio, José Ignacio
Villardi de Montlaur, Adeline de
The study of Martian winds holds significant scientific interest and potential practical applications. For instance, understanding the dynamics and behaviour of Martian winds is crucial in order to properly evaluate and select landing sites for missions to Mars [1]. The study of wind patterns is also critical in determining the capacity of Martian winds to remove dust from solar panels, thereby improving their performance and longevity [2]. Furthermore, Martian winds' effects on dust are fundamental to comprehending the planet's weather and climate [3], and finally, studying regional-scale sand transport and dune formation can contribute to gain a deeper understanding of Martian geological processes [4]. Therefore, the investigation of Martian winds represents a multidisciplinary approach with meaningful repercussions for planetary science and space exploration.
This work focuses on analysing the formation of thermally-driven winds, which are typically observed in inclined regions, examining their implications for the production of renewable wind energy. While wind energy may not be ideal for initial stages of human settlement on Mars, due mainly to the low density of the Martian atmosphere, it has the potential to serve as a renewable energy source in the long term and as a backup for solar energy [5]. Thermally-driven winds can attain considerably high velocities for steep slopes (values of up to 17 m/s [6]), exerting a dominant influence on the near-surface wind. The study of maximum velocities (Fig. 1) and the heights at which these velocities typically occur could be of particular interest for determining the optimal placement of wind energy resources (such as wind turbines) for future energy production on planet Mars.
Within the scope of this study, 2D simulations of slope winds on Mars are achieved using the open source computational fluid dynamics (CFD) code OpenFOAM. Several slope angles (ranging from 5º up to 20º) are considered. Following [7], the incompressible Navier-Stokes equations with Boussinesq approximation with a conventional k–e turbulence model are used. The impact of slope angle on the creation of thermal winds for both anabatic (up-slope) and katabatic (down-slope) flows is analysed: velocity and temperature profiles are presented for each slope angle along with the position of the maximum velocity. The numerical simulations shown in this work can serve as a cost-effective initial approximation, particularly when evaluating numerous configurations, while computationally more expensive techniques like Large Eddy Simulations (LES) or Direct Numerical Simulations (DNS) could be used in the future for validation and further exploration of final configurations.