Enviament des de DRAC
http://hdl.handle.net/2117/3055
Wed, 07 Dec 2016 06:36:25 GMT2016-12-07T06:36:25ZEdificios singulares en mallas regulares: iglesias en L'Eixample y en La Baixa
http://hdl.handle.net/2117/97819
Edificios singulares en mallas regulares: iglesias en L'Eixample y en La Baixa
Arboix Alió, Alba
Un edificio se considera singular cuando destaca entre el tejido común de la ciudad por su forma, su naturaleza y por su proceso de producción y seriación. Si esta singularidad arquitectónica va acompañada de una distinción urbanística, el resultado es mucho más efectivo porque el conjunto se convierte en un enclave urbano capaz de
ordenar y jerarquizar la ciudad. Quizás el ejemplo más ilustrativo para las ciudades históricas de tradición católica sea el de la iglesia con el espacio público que aparece a su alrededor. Durante siglos, el edificio sacro y el atrio que le precede han representado el punto referencial y el centro articulador de la vida social, económica y cultural de la ciudad. Pero si esto es más o menos evidente en los cascos antiguos sedimentados con el paso del tiempo, ¿cómo se resuelve en las ciudades modernas formadas a partir de una malla regular cuyo trazado se antepone a la libertad de la edificación? Con Barcelona y Lisboa como casos de estudio, el artículo versa sobre la implantación y la tipología de las iglesias más paradigmáticas de los barrios de L’Eixample de Cerdà y La Baixa pombalina.; A building is considered unique when it outstands within the common fabric of the city due to its form,
its nature, and its production and serialization process. If this architectural singularity is accompanied by an
urban distinction, the result is much more effective because the compound becomes an urban enclave capable
of arranging and hierarchically organising the city. The most illustrative example for historic cities with a Catholic
tradition may probably be the church with the public space that materializes around it. For centuries, the sacred
building and the atrium that precedes it have represented the city’s reference point and articulating centre of social,
economic and cultural life. Nevertheless, if this is more or less evident in old towns consolidated over time; how is
this solved in modern cities formed by a regular urban layout whose grid is put before the freedom of the buildings?
With Barcelona and Lisbon as case studies, the paper focuses on the implementation and typology of the most
paradigmatic churches in the neighbourhoods of L’Eixample Cerdà and La Baixa Pombalina.
Mon, 05 Dec 2016 18:27:31 GMThttp://hdl.handle.net/2117/978192016-12-05T18:27:31ZArboix Alió, AlbaUn edificio se considera singular cuando destaca entre el tejido común de la ciudad por su forma, su naturaleza y por su proceso de producción y seriación. Si esta singularidad arquitectónica va acompañada de una distinción urbanística, el resultado es mucho más efectivo porque el conjunto se convierte en un enclave urbano capaz de
ordenar y jerarquizar la ciudad. Quizás el ejemplo más ilustrativo para las ciudades históricas de tradición católica sea el de la iglesia con el espacio público que aparece a su alrededor. Durante siglos, el edificio sacro y el atrio que le precede han representado el punto referencial y el centro articulador de la vida social, económica y cultural de la ciudad. Pero si esto es más o menos evidente en los cascos antiguos sedimentados con el paso del tiempo, ¿cómo se resuelve en las ciudades modernas formadas a partir de una malla regular cuyo trazado se antepone a la libertad de la edificación? Con Barcelona y Lisboa como casos de estudio, el artículo versa sobre la implantación y la tipología de las iglesias más paradigmáticas de los barrios de L’Eixample de Cerdà y La Baixa pombalina.
A building is considered unique when it outstands within the common fabric of the city due to its form,
its nature, and its production and serialization process. If this architectural singularity is accompanied by an
urban distinction, the result is much more effective because the compound becomes an urban enclave capable
of arranging and hierarchically organising the city. The most illustrative example for historic cities with a Catholic
tradition may probably be the church with the public space that materializes around it. For centuries, the sacred
building and the atrium that precedes it have represented the city’s reference point and articulating centre of social,
economic and cultural life. Nevertheless, if this is more or less evident in old towns consolidated over time; how is
this solved in modern cities formed by a regular urban layout whose grid is put before the freedom of the buildings?
With Barcelona and Lisbon as case studies, the paper focuses on the implementation and typology of the most
paradigmatic churches in the neighbourhoods of L’Eixample Cerdà and La Baixa Pombalina.CO oxidation and COPrOx over preformed Au nanoparticles supported over nanoshaped CeO2
http://hdl.handle.net/2117/97815
CO oxidation and COPrOx over preformed Au nanoparticles supported over nanoshaped CeO2
Soler Turu, Lluís; Casanovas Grau, Albert; Urrich, Aitor; Angurell Purroy, Inmaculada; Llorca Piqué, Jordi
Au/CeO2 (0.25% wt. Au) catalysts were prepared by anchoring preformed Au nanoparticles over ceria polycrystals, cubes and rods and tested in the oxidation of CO and COPrOx. The use of preformed Au nanoparticles assured a constant Au particle size (ca. 5 nm by HRTEM) for all samples, which allowed to a precise assessment of the effect of the morphology of nanoshaped ceria on catalytic activity. The catalytic performance of the Au/CeO2-rods was much better than that of the Au/CeO2-polycrystals and Au/CeO2-cubes both in the oxidation of CO and COPrOx reactions. The Au/CeO2-rods exhibited the highest amount of oxidized Au and Ce(III) species by XPS, whereas in the Au/CeO2-cubes gold was totally metallic and the amount of Ce(III) was minimum. An intermediate situation was encountered in the Au/CeO2-polycrystals. Considering the differences in the oxidation states ofAu and Ce and the factthat all samples were prepared
with preformed metallic Au nanoparticles of the same size, the results indicate that the intrinsic nature of the different ceria surfaces exerts a prominent role in the gold-ceria interaction and in the electron density transfer from Au to Ce, which in turn has a strong effect on catalytic activity. Gold nanoparticles strongly interact with CeO2-{1 1 0} surfaces with respect to CeO2-{1 1 1} and CeO2-{1 0 0}, even when Au nanoparticles are prepared separately and simply deposited by impregnation.
Mon, 05 Dec 2016 17:58:49 GMThttp://hdl.handle.net/2117/978152016-12-05T17:58:49ZSoler Turu, LluísCasanovas Grau, AlbertUrrich, AitorAngurell Purroy, InmaculadaLlorca Piqué, JordiAu/CeO2 (0.25% wt. Au) catalysts were prepared by anchoring preformed Au nanoparticles over ceria polycrystals, cubes and rods and tested in the oxidation of CO and COPrOx. The use of preformed Au nanoparticles assured a constant Au particle size (ca. 5 nm by HRTEM) for all samples, which allowed to a precise assessment of the effect of the morphology of nanoshaped ceria on catalytic activity. The catalytic performance of the Au/CeO2-rods was much better than that of the Au/CeO2-polycrystals and Au/CeO2-cubes both in the oxidation of CO and COPrOx reactions. The Au/CeO2-rods exhibited the highest amount of oxidized Au and Ce(III) species by XPS, whereas in the Au/CeO2-cubes gold was totally metallic and the amount of Ce(III) was minimum. An intermediate situation was encountered in the Au/CeO2-polycrystals. Considering the differences in the oxidation states ofAu and Ce and the factthat all samples were prepared
with preformed metallic Au nanoparticles of the same size, the results indicate that the intrinsic nature of the different ceria surfaces exerts a prominent role in the gold-ceria interaction and in the electron density transfer from Au to Ce, which in turn has a strong effect on catalytic activity. Gold nanoparticles strongly interact with CeO2-{1 1 0} surfaces with respect to CeO2-{1 1 1} and CeO2-{1 0 0}, even when Au nanoparticles are prepared separately and simply deposited by impregnation.On fluctuations in interfacial fluid systems
http://hdl.handle.net/2117/97813
On fluctuations in interfacial fluid systems
Torner Sabata, Lluís; Rubí Capaceti, José Miguel; Díaz Guilera, Albert
We study the propagation of the temperature fluctuations in a system in the presence of an interface. Such fluctuations originate from surface noise sources which are introduced through the random parts of the interfacial currents which satisfy fluctuation-dissipation theorems. The formal solution for the fluctuations in the media and at the interface is given and from it we compute and analyze the prepagators. In particular we find that such quantities depend on three characteristics frequencies that are responsible for their peculiar behaviour. The temperature correlation function exhibits 1/f noise in a particular frequency range.
Mon, 05 Dec 2016 17:39:06 GMThttp://hdl.handle.net/2117/978132016-12-05T17:39:06ZTorner Sabata, LluísRubí Capaceti, José MiguelDíaz Guilera, AlbertWe study the propagation of the temperature fluctuations in a system in the presence of an interface. Such fluctuations originate from surface noise sources which are introduced through the random parts of the interfacial currents which satisfy fluctuation-dissipation theorems. The formal solution for the fluctuations in the media and at the interface is given and from it we compute and analyze the prepagators. In particular we find that such quantities depend on three characteristics frequencies that are responsible for their peculiar behaviour. The temperature correlation function exhibits 1/f noise in a particular frequency range.HVDC-based modular multilevel converter in the STATCOM operation mode
http://hdl.handle.net/2117/97812
HVDC-based modular multilevel converter in the STATCOM operation mode
Antonio Ferreira, Abel; Gomis Bellmunt, Oriol; Teixidó, Miquel
In a futuristic vision, deeply interconnected ac and dc networks are expected, which would be restructured over the time in order to maximize the power transmission efficiency. In some grid configurations, grid-tied inverters can eventually become islanded from the dc grid by means of breakers and enhancing those converters with the static synchronous compensator (STATCOM) functionality can increase their value. In this context, there is an extra degree of freedom, which is the voltage drop that should be targeted between the dc poles of the converter. Due to the modular multilevel converter (MMC) flexibility, the converter energy storage and the average voltage generated in the converter arms can be managed to achieve some goals as the converter efficiency and ac power quality increase, conjointly with the voltage ripple reduction on the capacitor values. This work analyzes the referred degrees of freedom of the converter control and the correspondent impact on the converter operating performance.
Mon, 05 Dec 2016 17:14:11 GMThttp://hdl.handle.net/2117/978122016-12-05T17:14:11ZAntonio Ferreira, AbelGomis Bellmunt, OriolTeixidó, MiquelIn a futuristic vision, deeply interconnected ac and dc networks are expected, which would be restructured over the time in order to maximize the power transmission efficiency. In some grid configurations, grid-tied inverters can eventually become islanded from the dc grid by means of breakers and enhancing those converters with the static synchronous compensator (STATCOM) functionality can increase their value. In this context, there is an extra degree of freedom, which is the voltage drop that should be targeted between the dc poles of the converter. Due to the modular multilevel converter (MMC) flexibility, the converter energy storage and the average voltage generated in the converter arms can be managed to achieve some goals as the converter efficiency and ac power quality increase, conjointly with the voltage ripple reduction on the capacitor values. This work analyzes the referred degrees of freedom of the converter control and the correspondent impact on the converter operating performance.Mode count in planar graded-index waveguides
http://hdl.handle.net/2117/97811
Mode count in planar graded-index waveguides
Torner Sabata, Lluís; Canal Bienzobas, Fernando; March, L. de
The cut-off properties for the TE modes of planar graded-index waveguides have been analysed in terms of the usual normalised waveguide parameters by using the multilayer technique. High accuracy has been achieved. The refractive index distributions more often used to model the actual profiles obtained by the usual fabrication techniques have been considered.
Mon, 05 Dec 2016 17:02:58 GMThttp://hdl.handle.net/2117/978112016-12-05T17:02:58ZTorner Sabata, LluísCanal Bienzobas, FernandoMarch, L. deThe cut-off properties for the TE modes of planar graded-index waveguides have been analysed in terms of the usual normalised waveguide parameters by using the multilayer technique. High accuracy has been achieved. The refractive index distributions more often used to model the actual profiles obtained by the usual fabrication techniques have been considered.Soliton excitation and mutual locking of light beams in bulk quadratic nonlinear crystals
http://hdl.handle.net/2117/97810
Soliton excitation and mutual locking of light beams in bulk quadratic nonlinear crystals
Torner Sabata, Lluís; Wright, E M
The mutual trapping and locking of intense fundamental and second-harmonic continuous-wave light beams propagating in bulk crystals with large second-order nonlinearities is investigated. We report the outcome of a comprehensive series of numerical experiments to study the dynamics of the excitation of solitons with Gaussian input beams under different material and excitation conditions in terms of input powers, wave-vector mismatch, and linear walk-off between the fundamental and the second-harmonic waves. We show the dynamics of the mutual trapping and study how solitons emerge from the input beams in a wide variety of conditions that are not necessarily close to those given by stationary solutions of the governing equations. Solitons also emerge with inputs that fall far from those solutions. We specifically investigate the dynamics of soliton excitation with only the fundamental beam at the input face of the nonlinear crystal and in configurations with a moderately large phase mismatch. We find large oscillations in the amplitude of the beams with potentially important implications. We also study the mutual dragging of the beams in the presence of linear walk-off and in particular of phase-matching geometries with a nonsmall, but moderate, walk-off.
Mon, 05 Dec 2016 16:52:08 GMThttp://hdl.handle.net/2117/978102016-12-05T16:52:08ZTorner Sabata, LluísWright, E MThe mutual trapping and locking of intense fundamental and second-harmonic continuous-wave light beams propagating in bulk crystals with large second-order nonlinearities is investigated. We report the outcome of a comprehensive series of numerical experiments to study the dynamics of the excitation of solitons with Gaussian input beams under different material and excitation conditions in terms of input powers, wave-vector mismatch, and linear walk-off between the fundamental and the second-harmonic waves. We show the dynamics of the mutual trapping and study how solitons emerge from the input beams in a wide variety of conditions that are not necessarily close to those given by stationary solutions of the governing equations. Solitons also emerge with inputs that fall far from those solutions. We specifically investigate the dynamics of soliton excitation with only the fundamental beam at the input face of the nonlinear crystal and in configurations with a moderately large phase mismatch. We find large oscillations in the amplitude of the beams with potentially important implications. We also study the mutual dragging of the beams in the presence of linear walk-off and in particular of phase-matching geometries with a nonsmall, but moderate, walk-off.Reentry produced by small-scale heterogeneities in a discrete model of cardiac tissue
http://hdl.handle.net/2117/97809
Reentry produced by small-scale heterogeneities in a discrete model of cardiac tissue
Alonso Muñoz, Sergio; Bär, Markus
Reentries are reexcitations of cardiac tissue after the passing of an excitation wave which can cause
dangerous arrhythmias like tachycardia or life-threatening heart failures like fibrillation. The heart is formed by a
network of cells connected by gap junctions. Under ischemic conditions some of the cells lose their connections,
because gap junctions are blocked and the excitability is decreased. We model a circular region of the tissue where
a fraction of connections among individual cells are removed and substituted by non-conducting material in a twodimensional
(2D) discrete model of a heterogeneous excitable medium with local kinetics based on electrophysiology.
Thus, two neighbouring cells are connected (disconnected) with a probability f (1 - f). Such a region is assumed to be
surrounded by homogeneous tissue. The circular heterogeneous area is shown to act as a source of new waves which
reenter into the tissue and reexcitate the whole domain. We employ the Fenton-Karma equations to model the action potential for the local kinetics of the discrete nodes to study the statistics of the reentries in two dimensional networks
with different topologies. We conclude that the probability of reentry is determined by the proximity of the fraction of
disrupted connections between neighboring nodes (
Mon, 05 Dec 2016 16:51:59 GMThttp://hdl.handle.net/2117/978092016-12-05T16:51:59ZAlonso Muñoz, SergioBär, MarkusReentries are reexcitations of cardiac tissue after the passing of an excitation wave which can cause
dangerous arrhythmias like tachycardia or life-threatening heart failures like fibrillation. The heart is formed by a
network of cells connected by gap junctions. Under ischemic conditions some of the cells lose their connections,
because gap junctions are blocked and the excitability is decreased. We model a circular region of the tissue where
a fraction of connections among individual cells are removed and substituted by non-conducting material in a twodimensional
(2D) discrete model of a heterogeneous excitable medium with local kinetics based on electrophysiology.
Thus, two neighbouring cells are connected (disconnected) with a probability f (1 - f). Such a region is assumed to be
surrounded by homogeneous tissue. The circular heterogeneous area is shown to act as a source of new waves which
reenter into the tissue and reexcitate the whole domain. We employ the Fenton-Karma equations to model the action potential for the local kinetics of the discrete nodes to study the statistics of the reentries in two dimensional networks
with different topologies. We conclude that the probability of reentry is determined by the proximity of the fraction of
disrupted connections between neighboring nodes (Spatial correlations for temperature fluctuations from surface noise
http://hdl.handle.net/2117/97807
Spatial correlations for temperature fluctuations from surface noise
Rubí Capaceti, José Miguel; Díaz Guilera, Albert; Torner Sabata, Lluís
The equal-time or static temperature correlation function from fluctuations originated at a surface is computed. Such fluctuations come from a random heat flux appearing in Newton's law of cooling. The correlation is studied in the real space and for different values of the Nusselt number.
Mon, 05 Dec 2016 16:46:48 GMThttp://hdl.handle.net/2117/978072016-12-05T16:46:48ZRubí Capaceti, José MiguelDíaz Guilera, AlbertTorner Sabata, LluísThe equal-time or static temperature correlation function from fluctuations originated at a surface is computed. Such fluctuations come from a random heat flux appearing in Newton's law of cooling. The correlation is studied in the real space and for different values of the Nusselt number.Comparative study of high-performance liquid chromatography and micellar electrokinetic capillary chromatography applied to the analysis of different mixtures of pesticides
http://hdl.handle.net/2117/97806
Comparative study of high-performance liquid chromatography and micellar electrokinetic capillary chromatography applied to the analysis of different mixtures of pesticides
Farran Marsà, Adriana; Ruiz Boqué, Sílvia; Serra Coma, M.Carme; Aguilar Sanjuán, Manuel
High-performance liquid chromatography (HPLC) and micellar electrokinetic capillary chromatography (MECC) methods for the determination of different pesticides mixtures have been developed. These mixtures include triazine, phenylurea, phenoxyalkyl acid, carbamate and organophosphorous pesticides that have been selected because their use in different combinations in commercial formulations. The best results have been obtained by using mobile phase gradients in HPLC and by working with n-alcohols as mobile phase modifiers in MECC. When the quality parameters of both methods have been compared, it was observed that they are not sensitive enough for environmental analysis. In this sense two different concentration methodologies, off-line solid extraction by using Carbopack columns and a special injection MECC method, have been studied to enhance sensitivity. Off-line solid extraction can be used for both HPLC and MECC methodologies and permits to detect low ppb levels of individual pesticides. Special injection methods applied to the MECC system provides a 200-fold sensitivity improvement for the ionic pesticides.
Mon, 05 Dec 2016 16:45:57 GMThttp://hdl.handle.net/2117/978062016-12-05T16:45:57ZFarran Marsà, AdrianaRuiz Boqué, SílviaSerra Coma, M.CarmeAguilar Sanjuán, ManuelHigh-performance liquid chromatography (HPLC) and micellar electrokinetic capillary chromatography (MECC) methods for the determination of different pesticides mixtures have been developed. These mixtures include triazine, phenylurea, phenoxyalkyl acid, carbamate and organophosphorous pesticides that have been selected because their use in different combinations in commercial formulations. The best results have been obtained by using mobile phase gradients in HPLC and by working with n-alcohols as mobile phase modifiers in MECC. When the quality parameters of both methods have been compared, it was observed that they are not sensitive enough for environmental analysis. In this sense two different concentration methodologies, off-line solid extraction by using Carbopack columns and a special injection MECC method, have been studied to enhance sensitivity. Off-line solid extraction can be used for both HPLC and MECC methodologies and permits to detect low ppb levels of individual pesticides. Special injection methods applied to the MECC system provides a 200-fold sensitivity improvement for the ionic pesticides.Stability analysis of periodic solutions in non-linear autonomous circuits: a discrete time approach
http://hdl.handle.net/2117/97804
Stability analysis of periodic solutions in non-linear autonomous circuits: a discrete time approach
Miró Sans, Joan Maria; Palà Schönwälder, Pere; Mas Casals, Orestes Miquel
Steady-state methods have been devised to compute periodic wave-forms without having to integrate the
autonomous circuit equations until the transients die out. Stability analysis of the computed solutions is the
next topic to be addressed by a steady state circuit simulator. Shooting methods based on Newton's iteration
are expensive in terms of computing time, because each iteration step requires integration of the variational
equation, but directly provide information on the stability of the final On the other hand, when
making use of harmonic balance methods, the stability of the computed solutions is typically investigated
from a continuation point of view.4 Recently a discrete time approach (DTA) was proposed for the analysis
and optimization of non-linear autonomous circuits.' This letter describes how the stability of the
computed periodic wave-forms may be easily determined (I posteriori with no modification to the DTA
solution method.
Mon, 05 Dec 2016 16:39:28 GMThttp://hdl.handle.net/2117/978042016-12-05T16:39:28ZMiró Sans, Joan MariaPalà Schönwälder, PereMas Casals, Orestes MiquelSteady-state methods have been devised to compute periodic wave-forms without having to integrate the
autonomous circuit equations until the transients die out. Stability analysis of the computed solutions is the
next topic to be addressed by a steady state circuit simulator. Shooting methods based on Newton's iteration
are expensive in terms of computing time, because each iteration step requires integration of the variational
equation, but directly provide information on the stability of the final On the other hand, when
making use of harmonic balance methods, the stability of the computed solutions is typically investigated
from a continuation point of view.4 Recently a discrete time approach (DTA) was proposed for the analysis
and optimization of non-linear autonomous circuits.' This letter describes how the stability of the
computed periodic wave-forms may be easily determined (I posteriori with no modification to the DTA
solution method.