Màster universitari en Física per a l'Enginyeria (Pla 2018)http://hdl.handle.net/2117/3480192024-03-28T13:47:09Z2024-03-28T13:47:09ZTimescales of perceptual evidence integration in an auditory decision-making taskMora Juvanteny, Joanhttp://hdl.handle.net/2117/4043632024-03-13T08:30:38Z2024-03-13T08:21:34ZTimescales of perceptual evidence integration in an auditory decision-making task
Mora Juvanteny, Joan
Complex cognitive functions such as working memory and decision-making require integration of perceptual evidence over different timescales, from transient sensory stimuli to long-term contextual cues. The perceptual evidence typically changes continuously in real-life environments, which may suggest that decision are made by means of an adaptive integration. In this project, we have designed a novel auditory decision-making task to study how perceptual evidence is integrated in 6 subjects, supported by the comparison of two computational models. The aim of this project is to use the task and results obtained for future electrophysiological studies of timescale adaptation.
2024-03-13T08:21:34ZMora Juvanteny, JoanComplex cognitive functions such as working memory and decision-making require integration of perceptual evidence over different timescales, from transient sensory stimuli to long-term contextual cues. The perceptual evidence typically changes continuously in real-life environments, which may suggest that decision are made by means of an adaptive integration. In this project, we have designed a novel auditory decision-making task to study how perceptual evidence is integrated in 6 subjects, supported by the comparison of two computational models. The aim of this project is to use the task and results obtained for future electrophysiological studies of timescale adaptation.Endothelial vascularization, HUVEC monolayer coating of a microchannel under flow conditionsPuig álamo, Adriàhttp://hdl.handle.net/2117/4038472024-03-19T11:07:26Z2024-03-06T12:05:53ZEndothelial vascularization, HUVEC monolayer coating of a microchannel under flow conditions
Puig álamo, Adrià
Microfluidic devices have been studied and developed over the last decades due to their multiple biology applications. One of their fields of most interest is the organ-on-a-chip technology, which consists in emulating an organ on a microchip. This technology presents several advantages, from ethical aspects for stop experimenting with animals to the control of many parameters while performing an experiment. This master?s thesis explores new microfluidic devices designs in order to study the malaria?s parasite \textit{Plasmodium vivax}, which is one of the main parasites that spread the disease. The parasite enters into the human body through the circulatory system, so the designs are focused on emulate blood vessels and the aim of this project is to search the best ways to ease the formation of a monolayer of endothelial cells over the walls of the channels of the microdevice under flow conditions. In concrete, the project studies the relation between the microdevices material PDMS and fluids as well as the interaction with microdevices walls when fluid is flowing through it in order to better the signs and achieve suitable parameters.
2024-03-06T12:05:53ZPuig álamo, AdriàMicrofluidic devices have been studied and developed over the last decades due to their multiple biology applications. One of their fields of most interest is the organ-on-a-chip technology, which consists in emulating an organ on a microchip. This technology presents several advantages, from ethical aspects for stop experimenting with animals to the control of many parameters while performing an experiment. This master?s thesis explores new microfluidic devices designs in order to study the malaria?s parasite \textit{Plasmodium vivax}, which is one of the main parasites that spread the disease. The parasite enters into the human body through the circulatory system, so the designs are focused on emulate blood vessels and the aim of this project is to search the best ways to ease the formation of a monolayer of endothelial cells over the walls of the channels of the microdevice under flow conditions. In concrete, the project studies the relation between the microdevices material PDMS and fluids as well as the interaction with microdevices walls when fluid is flowing through it in order to better the signs and achieve suitable parameters.Towards a quantum simulator emulating the electron-phonon interactionMascaró Burguera, Lucashttp://hdl.handle.net/2117/4032322024-02-26T17:10:20Z2024-02-26T17:08:53ZTowards a quantum simulator emulating the electron-phonon interaction
Mascaró Burguera, Lucas
The interaction between electrons and phonons lies behind a plethora of exotic physical phenomena, from Mott insulators and ferromagnetism to superconductivity. This interaction is really complex, and classical simulation methods fall short. Here is where analog quantum simulators come in. One can take advantage of the outstanding mechanical and electronic properties of carbon nanotubes to couple their electronic degrees of freedom to their mechanical modes. This platform would allow for the first realization of an analog quantum simulator for the electron-phonon interaction, effectively realising a Hubbard Hamiltonian. Quantum dots are to be electrostatically defined in a carbon nanotube, and the electronic states are to be coupled to the mechanical modes. The realization of such a simulator requires extremely clean suspended semiconducting nanotubes, high coupling and fast and sensitive readout for the interdot transitions. This work presents a fabrication method to obtain this kind of devices and their characterization at cryogenic temperatures. Fast and sensitive readout is achieved by using RF reflectometry to study the conduction changes in an adjacent quantum dot used as a SET sensor. Only single quantum dots have been defined in the devices, since really good devices have yet to been cooled down. Single charge transition events have yet to be measured, and the reflectometry measurements need to be optimized. The overall progress of the project is promising, and the first devices have been already produced.
2024-02-26T17:08:53ZMascaró Burguera, LucasThe interaction between electrons and phonons lies behind a plethora of exotic physical phenomena, from Mott insulators and ferromagnetism to superconductivity. This interaction is really complex, and classical simulation methods fall short. Here is where analog quantum simulators come in. One can take advantage of the outstanding mechanical and electronic properties of carbon nanotubes to couple their electronic degrees of freedom to their mechanical modes. This platform would allow for the first realization of an analog quantum simulator for the electron-phonon interaction, effectively realising a Hubbard Hamiltonian. Quantum dots are to be electrostatically defined in a carbon nanotube, and the electronic states are to be coupled to the mechanical modes. The realization of such a simulator requires extremely clean suspended semiconducting nanotubes, high coupling and fast and sensitive readout for the interdot transitions. This work presents a fabrication method to obtain this kind of devices and their characterization at cryogenic temperatures. Fast and sensitive readout is achieved by using RF reflectometry to study the conduction changes in an adjacent quantum dot used as a SET sensor. Only single quantum dots have been defined in the devices, since really good devices have yet to been cooled down. Single charge transition events have yet to be measured, and the reflectometry measurements need to be optimized. The overall progress of the project is promising, and the first devices have been already produced.Mathematical modelling of the epidemic dynamics due to viral interferenceUsán Sanz, Pablohttp://hdl.handle.net/2117/4019642024-02-15T09:50:30Z2024-02-15T09:45:24ZMathematical modelling of the epidemic dynamics due to viral interference
Usán Sanz, Pablo
Throughout this report we will study the substitution dynamics between two variants of SARS-CoV-19, more specifically the one who took place between Delta and Omicron BA.1 variants. To this effect, we develop two mathematical models that differ from the classical SIR and SEIR, two of the most commonly used compartmental models in epidemiology. In first place, we introduce a backward flow from Exposed to Susceptible individuals, characterized by a regression rate β′. We find that the introduction of this backward flow allows us to consider several epidemiological scenarios regarding the number of individuals who have been in contact with the virus. In second place, we consider an interaction between these two variants, characterized by an interaction rate η. We find that the effect this interaction has on the infected curves can be neglected for low values of η.
2024-02-15T09:45:24ZUsán Sanz, PabloThroughout this report we will study the substitution dynamics between two variants of SARS-CoV-19, more specifically the one who took place between Delta and Omicron BA.1 variants. To this effect, we develop two mathematical models that differ from the classical SIR and SEIR, two of the most commonly used compartmental models in epidemiology. In first place, we introduce a backward flow from Exposed to Susceptible individuals, characterized by a regression rate β′. We find that the introduction of this backward flow allows us to consider several epidemiological scenarios regarding the number of individuals who have been in contact with the virus. In second place, we consider an interaction between these two variants, characterized by an interaction rate η. We find that the effect this interaction has on the infected curves can be neglected for low values of η.First-principles computational modelling of novel anti-perovskite halide materials for energy materials applicationsBenítez Colominas, Polhttp://hdl.handle.net/2117/4005582024-01-31T07:50:19Z2024-01-31T07:45:59ZFirst-principles computational modelling of novel anti-perovskite halide materials for energy materials applications
Benítez Colominas, Pol
Anti-perovskite halides (AH) with formula Ag3BC (where B=S,Se and C=I,Br,Cl) are a family of semiconductor materials displaying suitable thermal and optoelectronic properties for potential energy materials applications, such as photovoltaic and thermoelectric devices. Nevertheless, AH have been little investigate to date, both at the experimental and theoretical levels, hence their stability, structural and vibrational properties remain relatively unknown. In this work, we have studied the representative compound Ag3SBr with computational first-principles approaches for advancing knowledge in material science and assessing the functional properties of anti-perovskite halides. In particular, we have employed Density Functional Theory (DFT) techniques considering different exchange-correlation functionals and quantum relativistic spin-orbit coupling effects to simulate this material. Our DFT calculations have revealed several interesting results. First, different interesting phases have been found using crystal structure prediction techniques. Second, we have shown that at least four of them are stable phases non previously reported. Among the stable phases a cubic phase with symmetry group P2_13 emerges as a very promising candidate structure for the ground-state of Ag3SBr. And third, the computed band gaps approximately range from 1 to 2 eV and the optical absorption coefficients are relatively large (10E4 - 10E5 1/cm) over all the whole visible spectrum. Therefore, in view of our theoretical DFT results it can be concluded that (1) new and more detailed experiments are needed to fully characterize AH at the fundamental level, and (2) the optoelectronic and thermodynamic stability properties of Ag3SBr suggest great potential of AH for photovoltaic applications.
2024-01-31T07:45:59ZBenítez Colominas, PolAnti-perovskite halides (AH) with formula Ag3BC (where B=S,Se and C=I,Br,Cl) are a family of semiconductor materials displaying suitable thermal and optoelectronic properties for potential energy materials applications, such as photovoltaic and thermoelectric devices. Nevertheless, AH have been little investigate to date, both at the experimental and theoretical levels, hence their stability, structural and vibrational properties remain relatively unknown. In this work, we have studied the representative compound Ag3SBr with computational first-principles approaches for advancing knowledge in material science and assessing the functional properties of anti-perovskite halides. In particular, we have employed Density Functional Theory (DFT) techniques considering different exchange-correlation functionals and quantum relativistic spin-orbit coupling effects to simulate this material. Our DFT calculations have revealed several interesting results. First, different interesting phases have been found using crystal structure prediction techniques. Second, we have shown that at least four of them are stable phases non previously reported. Among the stable phases a cubic phase with symmetry group P2_13 emerges as a very promising candidate structure for the ground-state of Ag3SBr. And third, the computed band gaps approximately range from 1 to 2 eV and the optical absorption coefficients are relatively large (10E4 - 10E5 1/cm) over all the whole visible spectrum. Therefore, in view of our theoretical DFT results it can be concluded that (1) new and more detailed experiments are needed to fully characterize AH at the fundamental level, and (2) the optoelectronic and thermodynamic stability properties of Ag3SBr suggest great potential of AH for photovoltaic applications.Flash sintering of high-performance lead-free (K,Na)NbO3-based piezoceramics: microstructure-properties relationshipBarrón Portela, Andreahttp://hdl.handle.net/2117/4002352024-01-25T10:10:17Z2024-01-25T10:05:51ZFlash sintering of high-performance lead-free (K,Na)NbO3-based piezoceramics: microstructure-properties relationship
Barrón Portela, Andrea
Piezoelectric materials are widely used as functional element of electromechanical trans- ducers in a large number of domestic and industrial applications. Because of their low cost and relatively easy fabrication, piezoelectric transducers are mainly based on polycrys- talline ferroelectric oxides; that is, oxide-based ferroelectric ceramics. Although piezoelec- tric ceramics are extensively used, their fabrication entails two environmental issue. On the one hand, the most used piezoelectric materials contain toxic element, in particular a high lead content. On the other hand, the ceramic materials manufacture requires a high energy demand, since the heat treatments involve high temperatures, in general above 1200 ºC, for several hours. To solve these issues, new eco-friendly piezoelectric materials are required. In this context, this project focusses on obtained lead-free piezoceramics by a low cost fast sintering process. In particular, this project aims to obtain lead-free (K, Na)NbO3-based piezoceramics with tailored microstructure to show high electrome- chanical response. Flash sintering, a novel ultrafast sintering technique, will be used to obtain dense ceramics of (K, Na)NbO3 system. This sintering methodology leads to a higher control of the microstructure and, therefore, enhanced functional properties may be reached. Controlling the flash sintering parameters (i.e., applied electric field, electrical current density and dwelling time) is crucial for obtaining high-dense samples and, consequently, it has an influence in the microstructure and the functional properties, which is what this project studies. In this work, highly-dense KNL-NTS ceramics are obtained by current controled flash sintering. The results reveal a grain growth for a decreasing applied field and decreasing dwelling time, but the opposite for the current density. Moreover, regarding functional properties, the highest remnant polarization is obtained for the sample with the highest dielectric constant and the smallest grain size.
2024-01-25T10:05:51ZBarrón Portela, AndreaPiezoelectric materials are widely used as functional element of electromechanical trans- ducers in a large number of domestic and industrial applications. Because of their low cost and relatively easy fabrication, piezoelectric transducers are mainly based on polycrys- talline ferroelectric oxides; that is, oxide-based ferroelectric ceramics. Although piezoelec- tric ceramics are extensively used, their fabrication entails two environmental issue. On the one hand, the most used piezoelectric materials contain toxic element, in particular a high lead content. On the other hand, the ceramic materials manufacture requires a high energy demand, since the heat treatments involve high temperatures, in general above 1200 ºC, for several hours. To solve these issues, new eco-friendly piezoelectric materials are required. In this context, this project focusses on obtained lead-free piezoceramics by a low cost fast sintering process. In particular, this project aims to obtain lead-free (K, Na)NbO3-based piezoceramics with tailored microstructure to show high electrome- chanical response. Flash sintering, a novel ultrafast sintering technique, will be used to obtain dense ceramics of (K, Na)NbO3 system. This sintering methodology leads to a higher control of the microstructure and, therefore, enhanced functional properties may be reached. Controlling the flash sintering parameters (i.e., applied electric field, electrical current density and dwelling time) is crucial for obtaining high-dense samples and, consequently, it has an influence in the microstructure and the functional properties, which is what this project studies. In this work, highly-dense KNL-NTS ceramics are obtained by current controled flash sintering. The results reveal a grain growth for a decreasing applied field and decreasing dwelling time, but the opposite for the current density. Moreover, regarding functional properties, the highest remnant polarization is obtained for the sample with the highest dielectric constant and the smallest grain size.Complete fabrication station of scalable microfluidic devices for sensing applicationsYang, Chunyuhttp://hdl.handle.net/2117/3863992023-04-19T10:20:19Z2023-04-19T10:11:47ZComplete fabrication station of scalable microfluidic devices for sensing applications
Yang, Chunyu
Microfluidics has become a field of intense research in the last decades due to the interesting capabilities this type of devices have. In the sensing area, they are meant to outperform classical laboratory techniques in terms of speed, volume of sample required, resolution, handling and efficiency. However, the technology has not achieved the predicted impact on the actual sensing world. Among the issues that slow down its development, the limited scalability of the fabrication techniques used results in a poor translation from research to the market.
2023-04-19T10:11:47ZYang, ChunyuMicrofluidics has become a field of intense research in the last decades due to the interesting capabilities this type of devices have. In the sensing area, they are meant to outperform classical laboratory techniques in terms of speed, volume of sample required, resolution, handling and efficiency. However, the technology has not achieved the predicted impact on the actual sensing world. Among the issues that slow down its development, the limited scalability of the fabrication techniques used results in a poor translation from research to the market.CNN-based detection and classification of UV-radiation solar and extrasolar flaresAyyash Sala, Danielhttp://hdl.handle.net/2117/3863982023-04-19T10:20:16Z2023-04-19T10:11:38ZCNN-based detection and classification of UV-radiation solar and extrasolar flares
Ayyash Sala, Daniel
This MSc. thesis studies the applicability of the CNN-based algorithm stella [2] for the detection of flares from different data sets: optical TESS (exo)stellar, EUV DSO/AIA and GNSS (the last two for Solar flares). First, the optical TESS (exo)stellar part, makes use of the new TESS catalog of flares. It is capable of training new models on uni-sector data, thus avoiding the over-fitting present, indicatively, in the pre-training models of stella. An analysis of the behavior of the models in sectors other than those where they have been trained and according to the spectral type of the flaring stars is presented. AUC across 2 × 10 (exo)stellar models trained span [0.973, 0.981]. Second, we consider the EUV SDO/AIA and GNSS data sets for Solar flares detection. With these two data sources, stella models are created for the detection of solar flares. Due to the casuistry related to the scarcity of data available in these two data sources used (due to low number of cadences for SDO/AIA or due to short baseline for GNSS), the results are not entirely satisfactory. However, they point the improvement paths for future development of better flare detection models based on stella.
2023-04-19T10:11:38ZAyyash Sala, DanielThis MSc. thesis studies the applicability of the CNN-based algorithm stella [2] for the detection of flares from different data sets: optical TESS (exo)stellar, EUV DSO/AIA and GNSS (the last two for Solar flares). First, the optical TESS (exo)stellar part, makes use of the new TESS catalog of flares. It is capable of training new models on uni-sector data, thus avoiding the over-fitting present, indicatively, in the pre-training models of stella. An analysis of the behavior of the models in sectors other than those where they have been trained and according to the spectral type of the flaring stars is presented. AUC across 2 × 10 (exo)stellar models trained span [0.973, 0.981]. Second, we consider the EUV SDO/AIA and GNSS data sets for Solar flares detection. With these two data sources, stella models are created for the detection of solar flares. Due to the casuistry related to the scarcity of data available in these two data sources used (due to low number of cadences for SDO/AIA or due to short baseline for GNSS), the results are not entirely satisfactory. However, they point the improvement paths for future development of better flare detection models based on stella.Density functional approach in the study of Bose-Bose liquid dropsSanuy Latorre, Areshttp://hdl.handle.net/2117/3863972023-04-19T10:20:21Z2023-04-19T10:11:30ZDensity functional approach in the study of Bose-Bose liquid drops
Sanuy Latorre, Ares
We have studied quantum liquid drops composed by a mixture of two Bose components using a density-functional formulation. The functional has been built following two different methods: the beyond mean-field Lee-Huang-Yang (MFLHY) approximation and the Quantum Monte Carlo (QMC) method. Our main goal has been the calculation of the critical atomic number for binding using the two methods. The calculation has been carried out in free space, where spherical drops are formed, and under the compression produced by an external transversal harmonic confinement. Our results show that the finite-range effects, present in the QMC functional, obtained as the difference between the critical atom numbers between QMC and MFLHY, are small in spherical drops. In contrast, these effects are enhanced in compressed drops where the critical number shrinks. We have studied the effect of harmonic compression by increasing the strength of the confinement.
2023-04-19T10:11:30ZSanuy Latorre, AresWe have studied quantum liquid drops composed by a mixture of two Bose components using a density-functional formulation. The functional has been built following two different methods: the beyond mean-field Lee-Huang-Yang (MFLHY) approximation and the Quantum Monte Carlo (QMC) method. Our main goal has been the calculation of the critical atomic number for binding using the two methods. The calculation has been carried out in free space, where spherical drops are formed, and under the compression produced by an external transversal harmonic confinement. Our results show that the finite-range effects, present in the QMC functional, obtained as the difference between the critical atom numbers between QMC and MFLHY, are small in spherical drops. In contrast, these effects are enhanced in compressed drops where the critical number shrinks. We have studied the effect of harmonic compression by increasing the strength of the confinement.Innovative calibration method for rotating-coil magnetometersFontanet Valls, Andrea Del Carmehttp://hdl.handle.net/2117/3751312022-10-27T09:50:29Z2022-10-27T09:42:41ZInnovative calibration method for rotating-coil magnetometers
Fontanet Valls, Andrea Del Carme
Rotating-coil magnetometers, which rely on induction-coil arrays, are commonly used for magnetic measurements of particle accelerator magnets. In order to characterize magnetic fields with high accuracy using the induced voltages, it is essential to calibrate the geometry of the coils. In this thesis we present an innovative method of calibration of the coil radius of rotation which is necessary for determination of the field gradient. The method, called rotating calibration method, is based on two well-known measurement techniques: single-stretched wire and rotating induction-coils. The flux measured with a rotating induction-coil over the entire length of a reference quadrupole magnet is cross-calibrated with a single-stretched wire measurement. In the experimental validation of the method, the radius of rotation of several coils has been calibrated with an accuracy of 10 µm on a radius of 30 mm. The advantage of this method is that the calibration is performed under the same conditions in which the rotating-coil magnetometers are used for measuring accelerator magnets. In the thesis also a proposal for calibration of other geometric factors of a coil by using higher order multipoles is presented.
2022-10-27T09:42:41ZFontanet Valls, Andrea Del CarmeRotating-coil magnetometers, which rely on induction-coil arrays, are commonly used for magnetic measurements of particle accelerator magnets. In order to characterize magnetic fields with high accuracy using the induced voltages, it is essential to calibrate the geometry of the coils. In this thesis we present an innovative method of calibration of the coil radius of rotation which is necessary for determination of the field gradient. The method, called rotating calibration method, is based on two well-known measurement techniques: single-stretched wire and rotating induction-coils. The flux measured with a rotating induction-coil over the entire length of a reference quadrupole magnet is cross-calibrated with a single-stretched wire measurement. In the experimental validation of the method, the radius of rotation of several coils has been calibrated with an accuracy of 10 µm on a radius of 30 mm. The advantage of this method is that the calibration is performed under the same conditions in which the rotating-coil magnetometers are used for measuring accelerator magnets. In the thesis also a proposal for calibration of other geometric factors of a coil by using higher order multipoles is presented.