Grups de recerca
http://hdl.handle.net/2117/28581
2020-08-12T06:51:43ZReutilización de espacios industriales anónimos en el barrio del Poblenou
http://hdl.handle.net/2117/328135
Reutilización de espacios industriales anónimos en el barrio del Poblenou
Salvadó Aragonès, Núria
Esta propuesta de reutilización de una serie de cinco naves industriales, en el sector del Poblenou de Barcelona, pretende —y consigue— aprovechar lo existente no como un obstáculo sino como una oportunidad de mejorar funcionalidad y calidad espacial del conjunto.
2020-07-31T09:00:15ZSalvadó Aragonès, NúriaEsta propuesta de reutilización de una serie de cinco naves industriales, en el sector del Poblenou de Barcelona, pretende —y consigue— aprovechar lo existente no como un obstáculo sino como una oportunidad de mejorar funcionalidad y calidad espacial del conjunto.Analysis and prediction of COVID-19 for EU-EFTA-UK and other countries
http://hdl.handle.net/2117/328129
Analysis and prediction of COVID-19 for EU-EFTA-UK and other countries
Català Sabaté, Martí; Cardona Iglesias, Pere Joan; Prats Soler, Clara; Alonso Muñoz, Sergio; Álvarez Lacalle, Enrique; Marchena Angos, Miquel; Conesa, David; López Codina, Daniel
The present report aims to provide a comprehensive picture of the pandemic situation of COVID-19 in the
EU countries, and to be able to foresee the situation in the next coming days.
We employ an empirical model, verified with the evolution of the number of confirmed cases in previous
countries where the epidemic is close to conclude, including all provinces of China. The model does not
pretend to interpret the causes of the evolution of the cases but to permit the evaluation of the quality of
control measures made in each state and a short-term prediction of trends. Note, however, that the effects
of the measures’ control that start on a given day are not observed until approximately 7-10 days later.
The model and predictions are based on two parameters that are daily fitted to available data:
a: the velocity at which spreading specific rate slows down; the higher the value, the better the
control.
K: the final number of expected cumulated cases, which cannot be evaluated at the initial stages
because growth is still exponential.
We show an individual report with 8 graphs and a table with the short-term predictions for different
countries and regions. We are adjusting the model to countries and regions with at least 4 days with more
than 100 confirmed cases and a current load over 200 cases. The predicted period of a country depends on
the number of datapoints over this 100 cases threshold, and is of 5 days for those that have reported more
than 100 cumulated cases for 10 consecutive days or more. For short-term predictions, we assign higher
weight to last 3 points in the fittings, so that changes are rapidly captured by the model. The whole
methodology employed in the inform is explained in the last pages of this document.
In addition to the individual reports, the reader will find an initial dashboard with a brief analysis of the
situation in EU-EFTA-UK countries, some summary figures and tables as well as long-term predictions for
some of them, when possible. These long-term predictions are evaluated without different weights to datapoints. We also discuss a specific issue every day.
2020-07-31T08:12:36ZCatalà Sabaté, MartíCardona Iglesias, Pere JoanPrats Soler, ClaraAlonso Muñoz, SergioÁlvarez Lacalle, EnriqueMarchena Angos, MiquelConesa, DavidLópez Codina, DanielThe present report aims to provide a comprehensive picture of the pandemic situation of COVID-19 in the
EU countries, and to be able to foresee the situation in the next coming days.
We employ an empirical model, verified with the evolution of the number of confirmed cases in previous
countries where the epidemic is close to conclude, including all provinces of China. The model does not
pretend to interpret the causes of the evolution of the cases but to permit the evaluation of the quality of
control measures made in each state and a short-term prediction of trends. Note, however, that the effects
of the measures’ control that start on a given day are not observed until approximately 7-10 days later.
The model and predictions are based on two parameters that are daily fitted to available data:
a: the velocity at which spreading specific rate slows down; the higher the value, the better the
control.
K: the final number of expected cumulated cases, which cannot be evaluated at the initial stages
because growth is still exponential.
We show an individual report with 8 graphs and a table with the short-term predictions for different
countries and regions. We are adjusting the model to countries and regions with at least 4 days with more
than 100 confirmed cases and a current load over 200 cases. The predicted period of a country depends on
the number of datapoints over this 100 cases threshold, and is of 5 days for those that have reported more
than 100 cumulated cases for 10 consecutive days or more. For short-term predictions, we assign higher
weight to last 3 points in the fittings, so that changes are rapidly captured by the model. The whole
methodology employed in the inform is explained in the last pages of this document.
In addition to the individual reports, the reader will find an initial dashboard with a brief analysis of the
situation in EU-EFTA-UK countries, some summary figures and tables as well as long-term predictions for
some of them, when possible. These long-term predictions are evaluated without different weights to datapoints. We also discuss a specific issue every day.A compact fission detector for fission-tagging neutron capture experiments with radioactive fissile isotopes
http://hdl.handle.net/2117/328127
A compact fission detector for fission-tagging neutron capture experiments with radioactive fissile isotopes
Bacak, Michael; Aiche, Mourad; Bélier, Gilbert; Berthoumieux, Eric; Diakaki, Maria; Dupont, Emmeric; Gunsing, Frank; Kopecky, Stefan; Calviño Tavares, Francisco; Casanovas Hoste, Adrià; Cortés Rossell, Guillem Pere; Tarifeño Saldivia, Ariel Esteban
In the measurement of neutron capture cross-sections of fissile isotopes, the fission channel is a source of background which can be removed efficiently using the so-called fission-tagging or fission-veto technique. For this purpose a new compact and fast fission chamber has been developed. The design criteria and technical description of the chamber are given within the context of a measurement of the 233U(n,gamma) cross-section at the n_TOF facility at CERN, where it was coupled to the n_TOF Total Absorption Calorimeter. For this measurement the fission detector was optimized for time resolution, minimization of material in the neutron beam and for alpha-fission discrimination. The performance of the fission chamber and its application as a fission tagging detector are discussed.
2020-07-31T08:07:06ZBacak, MichaelAiche, MouradBélier, GilbertBerthoumieux, EricDiakaki, MariaDupont, EmmericGunsing, FrankKopecky, StefanCalviño Tavares, FranciscoCasanovas Hoste, AdriàCortés Rossell, Guillem PereTarifeño Saldivia, Ariel EstebanIn the measurement of neutron capture cross-sections of fissile isotopes, the fission channel is a source of background which can be removed efficiently using the so-called fission-tagging or fission-veto technique. For this purpose a new compact and fast fission chamber has been developed. The design criteria and technical description of the chamber are given within the context of a measurement of the 233U(n,gamma) cross-section at the n_TOF facility at CERN, where it was coupled to the n_TOF Total Absorption Calorimeter. For this measurement the fission detector was optimized for time resolution, minimization of material in the neutron beam and for alpha-fission discrimination. The performance of the fission chamber and its application as a fission tagging detector are discussed.Investigation of the 240Pu (n, f) reaction at the n_TOF/EAR2 facility in the 9 meV–6 MeV range
http://hdl.handle.net/2117/328124
Investigation of the 240Pu (n, f) reaction at the n_TOF/EAR2 facility in the 9 meV–6 MeV range
Stamatopoulos, A.; Tsinganis, Andrea; Colonna, Nicola; Vlastou, Roza; Diakaki, Maria; Žugec, Petar; Gunsing, Frank; Sabaté-Gilarte, Marta; Barbagallo, Massimo; Calviño Tavares, Francisco; Cortés Rossell, Guillem Pere
Background: Nuclear waste management is considered amongst the major challenges in the field of nuclear energy. A possible means of addressing this issue is waste transmutation in advanced nuclear systems, whose operation requires a fast neutron spectrum. In this regard, the accurate knowledge of neutron-induced reaction cross sections of several (minor) actinide isotopes is essential for design optimization and improvement of safety margins of such systems. One such case is 240 Pu , due to its accumulation in spent nuclear fuel of thermal reactors and its usage in fast reactor fuel. The measurement of the 240 Pu ( n , f ) cross section was previously attempted at the CERN n_TOF facility EAR1 measuring station using the time-of-flight technique. Due to the low amount of available material and the given flux at EAR1, the measurement had to last several months to achieve a sufficient statistical accuracy. This long duration led to detector deterioration due to the prolonged exposure to the high a activity of the fission foils, therefore the measurement could not be successfully completed. Purpose: It is aimed to determine whether it is feasible to study neutron-induced fission at n_TOF/EAR2 and provide data on the 240 Pu ( n , f ) reaction in energy regions requested for applications. Methods: The study of the 240 Pu ( n , f ) reaction was made at a new experimental area (EAR2) with a shorter flight path which delivered on average 30 times higher flux at fast neutron energies. This enabled the measurement to be performed much faster, thus limiting the exposure of the detectors to the intrinsic activity of the fission foils. The experimental setup was based on microbulk Micromegas detectors and the time-of-flight data were analyzed with an optimized pulse-shape analysis algorithm. Special attention was dedicated to the estimation of the non-negligible counting loss corrections with the development of a new methodology, and other corrections were estimated via Monte Carlo simulations of the experimental setup. Results: This new measurement of the 240 Pu ( n , f ) cross section yielded data from 9 meV up to 6 MeV incident neutron energy and fission resonance kernels were extracted up to 10 keV . Conclusions: Neutron-induced fission of high activity samples can be successfully studied at the n_TOF/EAR2 facility at CERN covering a wide range of neutron energies, from thermal to a few MeV.
2020-07-31T07:48:34ZStamatopoulos, A.Tsinganis, AndreaColonna, NicolaVlastou, RozaDiakaki, MariaŽugec, PetarGunsing, FrankSabaté-Gilarte, MartaBarbagallo, MassimoCalviño Tavares, FranciscoCortés Rossell, Guillem PereBackground: Nuclear waste management is considered amongst the major challenges in the field of nuclear energy. A possible means of addressing this issue is waste transmutation in advanced nuclear systems, whose operation requires a fast neutron spectrum. In this regard, the accurate knowledge of neutron-induced reaction cross sections of several (minor) actinide isotopes is essential for design optimization and improvement of safety margins of such systems. One such case is 240 Pu , due to its accumulation in spent nuclear fuel of thermal reactors and its usage in fast reactor fuel. The measurement of the 240 Pu ( n , f ) cross section was previously attempted at the CERN n_TOF facility EAR1 measuring station using the time-of-flight technique. Due to the low amount of available material and the given flux at EAR1, the measurement had to last several months to achieve a sufficient statistical accuracy. This long duration led to detector deterioration due to the prolonged exposure to the high a activity of the fission foils, therefore the measurement could not be successfully completed. Purpose: It is aimed to determine whether it is feasible to study neutron-induced fission at n_TOF/EAR2 and provide data on the 240 Pu ( n , f ) reaction in energy regions requested for applications. Methods: The study of the 240 Pu ( n , f ) reaction was made at a new experimental area (EAR2) with a shorter flight path which delivered on average 30 times higher flux at fast neutron energies. This enabled the measurement to be performed much faster, thus limiting the exposure of the detectors to the intrinsic activity of the fission foils. The experimental setup was based on microbulk Micromegas detectors and the time-of-flight data were analyzed with an optimized pulse-shape analysis algorithm. Special attention was dedicated to the estimation of the non-negligible counting loss corrections with the development of a new methodology, and other corrections were estimated via Monte Carlo simulations of the experimental setup. Results: This new measurement of the 240 Pu ( n , f ) cross section yielded data from 9 meV up to 6 MeV incident neutron energy and fission resonance kernels were extracted up to 10 keV . Conclusions: Neutron-induced fission of high activity samples can be successfully studied at the n_TOF/EAR2 facility at CERN covering a wide range of neutron energies, from thermal to a few MeV.Finite element modeling of temperature fields on the cutting edge in the dry high-speed turning of aisi 1045 steel
http://hdl.handle.net/2117/328122
Finite element modeling of temperature fields on the cutting edge in the dry high-speed turning of aisi 1045 steel
Pérez Rodriguez, Roberto; Hernández González, Luis Wilfredo; Quesada Estrada, Ana María; Pino Tarrragó, Julio Cesar; Zayas Figueras, Enrique Ernesto
High-speed turning is an advanced and emerging machining technique that, in contrast to the conventional machining, allows the manufacture of the workpiece with high accuracy, efficiency and quality, with lower production costs and with a considerable reduction in the machining times. The cutting tools used for the conventional machining cannot be employed for high-speed machining due to a high temperature induced in machining and a lower tool life. Therefore, it is necessary to study the influence of high cutting speeds on the temperature distribution in different typologies of cutting tools, with the aim of evaluating their behavior. In this paper, a finite element method modeling approach with arbitrary Lagrangian-Eulerian fully coupled thermal-stress analysis is employed. The research presents the results of different cutting tools (two coated carbide tools and uncoated cermet) effects on average surface temperature fields on the cutting edge in the dry high-speed turning of AISI 1045 steel. The numerical experiments were designed based on different cutting tools like input parameters and different temperature field zones like dependent variables in the dry high-speed turning of AISI 1045 steel. The results indicate that the dry high-speed turning of AISI 1045 steel does not influence significantly the temperature field zones when P10, P15 or P25 inserts are used. Therefore, the use of a dry high-speed turning method, which reduces the amount of lubricant and increases productivity, may represent an alternative to turning to the extent here described.
2020-07-31T07:32:57ZPérez Rodriguez, RobertoHernández González, Luis WilfredoQuesada Estrada, Ana MaríaPino Tarrragó, Julio CesarZayas Figueras, Enrique ErnestoHigh-speed turning is an advanced and emerging machining technique that, in contrast to the conventional machining, allows the manufacture of the workpiece with high accuracy, efficiency and quality, with lower production costs and with a considerable reduction in the machining times. The cutting tools used for the conventional machining cannot be employed for high-speed machining due to a high temperature induced in machining and a lower tool life. Therefore, it is necessary to study the influence of high cutting speeds on the temperature distribution in different typologies of cutting tools, with the aim of evaluating their behavior. In this paper, a finite element method modeling approach with arbitrary Lagrangian-Eulerian fully coupled thermal-stress analysis is employed. The research presents the results of different cutting tools (two coated carbide tools and uncoated cermet) effects on average surface temperature fields on the cutting edge in the dry high-speed turning of AISI 1045 steel. The numerical experiments were designed based on different cutting tools like input parameters and different temperature field zones like dependent variables in the dry high-speed turning of AISI 1045 steel. The results indicate that the dry high-speed turning of AISI 1045 steel does not influence significantly the temperature field zones when P10, P15 or P25 inserts are used. Therefore, the use of a dry high-speed turning method, which reduces the amount of lubricant and increases productivity, may represent an alternative to turning to the extent here described.Characterizations of some complexity classes between [theta sub 2 super p] and [delta sub 2 super p]
http://hdl.handle.net/2117/328115
Characterizations of some complexity classes between [theta sub 2 super p] and [delta sub 2 super p]
Castro Rabal, Jorge; Seara Ojea, Carlos
We give some characterizations of the classes P super NP [0(log super k n)]. First, we show that these classes are equal to classes AC super k-1 (N P). Second, we prove that they are also equivalent to some classes defined in the Extended Boolean hierarchy. Finally, we show that there exists a strong connection between classes defined by polynomial time Turing machines with few queries to an N P oracle and classes defined by small size circuits with N P oracle gates. With these results we solve open questions arosed by K. W. Wagner and by E. Allender and C.B. Wilson.
2020-07-30T17:42:15ZCastro Rabal, JorgeSeara Ojea, CarlosWe give some characterizations of the classes P super NP [0(log super k n)]. First, we show that these classes are equal to classes AC super k-1 (N P). Second, we prove that they are also equivalent to some classes defined in the Extended Boolean hierarchy. Finally, we show that there exists a strong connection between classes defined by polynomial time Turing machines with few queries to an N P oracle and classes defined by small size circuits with N P oracle gates. With these results we solve open questions arosed by K. W. Wagner and by E. Allender and C.B. Wilson.Generalized Kolmogorov complexity in relativized separations
http://hdl.handle.net/2117/328102
Generalized Kolmogorov complexity in relativized separations
Gavaldà Mestre, Ricard; Torenvliet, Leen; Watanabe, Osamu; Balcázar Navarro, José Luis
We describe several developments of a technique, due to Hartmanis, that uses Kolmogorov complexity to prove the existence of relativizations separating complexity classes. The main advantage of these proofs is that they clearly show the limitations of certain classes of oracle machines and the relevance of these limitations for the proof. Such limitations refer to the extent to which the machines defining the class are able to process Kolmogorov-complex structures.
2020-07-30T16:24:57ZGavaldà Mestre, RicardTorenvliet, LeenWatanabe, OsamuBalcázar Navarro, José LuisWe describe several developments of a technique, due to Hartmanis, that uses Kolmogorov complexity to prove the existence of relativizations separating complexity classes. The main advantage of these proofs is that they clearly show the limitations of certain classes of oracle machines and the relevance of these limitations for the proof. Such limitations refer to the extent to which the machines defining the class are able to process Kolmogorov-complex structures.Superfluid and supersolid phases of He-4 on the second layer of graphite
http://hdl.handle.net/2117/328096
Superfluid and supersolid phases of He-4 on the second layer of graphite
Gordillo Bargueño, Maria Carmen; Boronat Medico, Jordi
We revisited the phase diagram of the second layer of 4He on top of graphite using quantum Monte Carlo methods. Our aim was to explore the existence of the novel phases suggested recently in experimental works, and determine their properties and stability limits. We found evidence of a superfluid quantum phase with hexatic correlations, induced by the corrugation of the first Helium layer, and a quasi-two-dimensional supersolid corresponding to a 7/12 registered phase. The 4/7 commensurate solid was found to be unstable, while the triangular incommensurate crystals, stable at large densities, were normal.
2020-07-30T14:31:29ZGordillo Bargueño, Maria CarmenBoronat Medico, JordiWe revisited the phase diagram of the second layer of 4He on top of graphite using quantum Monte Carlo methods. Our aim was to explore the existence of the novel phases suggested recently in experimental works, and determine their properties and stability limits. We found evidence of a superfluid quantum phase with hexatic correlations, induced by the corrugation of the first Helium layer, and a quasi-two-dimensional supersolid corresponding to a 7/12 registered phase. The 4/7 commensurate solid was found to be unstable, while the triangular incommensurate crystals, stable at large densities, were normal.Finite-range effects in ultradilute quantum drops
http://hdl.handle.net/2117/328095
Finite-range effects in ultradilute quantum drops
Cikojevic, Viktor; Vranješ Markic, Leandra; Boronat Medico, Jordi
In the first experimental realization of dilute Bose–Bose liquid drops using two hyperfine states of 39K some discrepancies between theory and experiment were observed. The standard analysis of the data using the Lee–Huang–Yang beyond mean-field theory predicted critical numbers which were significantly off the experimental measurements. Also, the radial size of the drops in the experiment proved to be larger than expected from this theory. Using a new functional, which is based on quantum Monte Carlo results of the bulk phase incorporating finite-range effects, we can explain the origin of the discrepancies in the critical number. This result proves the necessity of including finite-range corrections to deal with the observed properties in this setup. The controversy on the radial size is reasoned in terms of the departure from the optimal concentration ratio between the two species of the mixture.
2020-07-30T14:16:44ZCikojevic, ViktorVranješ Markic, LeandraBoronat Medico, JordiIn the first experimental realization of dilute Bose–Bose liquid drops using two hyperfine states of 39K some discrepancies between theory and experiment were observed. The standard analysis of the data using the Lee–Huang–Yang beyond mean-field theory predicted critical numbers which were significantly off the experimental measurements. Also, the radial size of the drops in the experiment proved to be larger than expected from this theory. Using a new functional, which is based on quantum Monte Carlo results of the bulk phase incorporating finite-range effects, we can explain the origin of the discrepancies in the critical number. This result proves the necessity of including finite-range corrections to deal with the observed properties in this setup. The controversy on the radial size is reasoned in terms of the departure from the optimal concentration ratio between the two species of the mixture.Recreational beach management: a case study from the Amazon coast
http://hdl.handle.net/2117/328094
Recreational beach management: a case study from the Amazon coast
de Sousa-Felix, Rosigleyse Corrêa; Coelho Pessoa, Rubem Manoel; da Costa, Rauquírio Marinho; Jiménez Quintana, José Antonio; Cajueiro Carneiro Pereira, Luci
Coastal tourism is the most important segment of this economic sector, given that a majority of tourists tend to prefer coastal destinations. The sandy beaches of the Brazilian Amazon coast, with their well-preserved environments distributed along 3900 km of coastline, have considerable potential for tourism, in particular, ecotourism. The aim of this study was to evaluate of the tourism scenario of three Amazon beaches for the identification of the strengths and weaknesses of this environment, and the investigation of the principal external factors (legislation, economics, and environmental conditioners) that influence local tourism. Data on hydrological and socioeconomic variables were collected and used as input for a SWOT matrix to determine the principal strengths, weaknesses, opportunities, and threats existing for these beaches. The principal opportunities are derived from the legislation, including the State Coastal Management Plan, the Beachfront Project, and the management plans of the local conservation units. The threats are maximized by the inadequate application of the legal management mechanisms, which has resulted in beaches with no public sanitation, water treatment, the unregulated occupation of land, low levels of education, environmental degradation, and a loss of biodiversity. The principal strength for the management of the Amazonian beaches is the fact that these sites are in the public domain, which allows the government to implement wide-ranging management strategies based on the systematic evaluation of parameters. The weaknesses of the beaches identified in the present study included the lack of public sanitation, high concentrations of visitors, and inadequate beach security services. Overall, the analysis of the SWOT matrix indicated that the adoption of the Integrated Coastal Zone Management (ICZM) principles would provide an excellent opportunity for the changes necessary to resolve the environmental problems observed on the study beaches. This would help to establish a more inclusive, participative, and proactive approach to the management of the local beach environments.
2020-07-30T14:12:10Zde Sousa-Felix, Rosigleyse CorrêaCoelho Pessoa, Rubem Manoelda Costa, Rauquírio MarinhoJiménez Quintana, José AntonioCajueiro Carneiro Pereira, LuciCoastal tourism is the most important segment of this economic sector, given that a majority of tourists tend to prefer coastal destinations. The sandy beaches of the Brazilian Amazon coast, with their well-preserved environments distributed along 3900 km of coastline, have considerable potential for tourism, in particular, ecotourism. The aim of this study was to evaluate of the tourism scenario of three Amazon beaches for the identification of the strengths and weaknesses of this environment, and the investigation of the principal external factors (legislation, economics, and environmental conditioners) that influence local tourism. Data on hydrological and socioeconomic variables were collected and used as input for a SWOT matrix to determine the principal strengths, weaknesses, opportunities, and threats existing for these beaches. The principal opportunities are derived from the legislation, including the State Coastal Management Plan, the Beachfront Project, and the management plans of the local conservation units. The threats are maximized by the inadequate application of the legal management mechanisms, which has resulted in beaches with no public sanitation, water treatment, the unregulated occupation of land, low levels of education, environmental degradation, and a loss of biodiversity. The principal strength for the management of the Amazonian beaches is the fact that these sites are in the public domain, which allows the government to implement wide-ranging management strategies based on the systematic evaluation of parameters. The weaknesses of the beaches identified in the present study included the lack of public sanitation, high concentrations of visitors, and inadequate beach security services. Overall, the analysis of the SWOT matrix indicated that the adoption of the Integrated Coastal Zone Management (ICZM) principles would provide an excellent opportunity for the changes necessary to resolve the environmental problems observed on the study beaches. This would help to establish a more inclusive, participative, and proactive approach to the management of the local beach environments.