DILAB - Laboratori de física dels materials dielèctricshttp://hdl.handle.net/2117/32082024-03-28T23:56:47Z2024-03-28T23:56:47ZStudy analysis of thermal, dielectric and functional characteristics of an ethylene polyethylene diene monomer blended with end-of-life tire microparticles amountsMarín Genescà, MarcMujal-Rosas, Ramon MariaGarcia Amoros, JordiMudarra López, MiguelRamis Juan, XavierColom Fajula, Xavierhttp://hdl.handle.net/2117/3499462021-07-25T20:39:30Z2021-07-22T09:25:19ZStudy analysis of thermal, dielectric and functional characteristics of an ethylene polyethylene diene monomer blended with end-of-life tire microparticles amounts
Marín Genescà, Marc; Mujal-Rosas, Ramon Maria; Garcia Amoros, Jordi; Mudarra López, Miguel; Ramis Juan, Xavier; Colom Fajula, Xavier
The recycling and disposal of disused tires is a topic of great concern to today’s companies, researchers, and society in general. In this sense, our research aims to recycle end-of-life tires (GTRs) through the separation of the fraction of vulcanized rubber from the other compounds in order to later grind this fraction and separate it into lower particle sizes. Finally, we aim to incorporate these GTR particles as a filler of an ethylene-polyethylene-diene monomer (EPDM). The obtained composites with EPDM and GTR are tested (5%, 10%, 20%) comparing these values with neat EPDM as a control sample. Thermal tests such as differential calorimetry (DSC) and thermogravimetric analysis (TGA) as well as dielectric tests (DEA) are performed in order to characterize these materials and check their viability as dielectric or semiconductor, for industrial use. It is checked how the presence of GTR increases functional properties such as conductivity/permittivity. The influence of temperature (40 to 120 °C) and addition of GTR particles in electrical properties has also been analyzed. The dielectric behavior of these composites is fully characterized, analyzing the different types of relaxation with increasing frequency (10 mHz to 3 MHz), using the electric modulus, and Argand diagrams among other measures. The influence of GTR and temperature in the dielectric and thermal behavior of these materials has been analyzed, where CB of GTR creates interfacial polarization phenomena in the dielectric behavior of the composite and increases the permittivity (real and imaginary) as well as the conductivity. Finally, with these obtained properties, the possible application of EPDM/GTR composites as industrial dielectrics has been studied
2021-07-22T09:25:19ZMarín Genescà, MarcMujal-Rosas, Ramon MariaGarcia Amoros, JordiMudarra López, MiguelRamis Juan, XavierColom Fajula, XavierThe recycling and disposal of disused tires is a topic of great concern to today’s companies, researchers, and society in general. In this sense, our research aims to recycle end-of-life tires (GTRs) through the separation of the fraction of vulcanized rubber from the other compounds in order to later grind this fraction and separate it into lower particle sizes. Finally, we aim to incorporate these GTR particles as a filler of an ethylene-polyethylene-diene monomer (EPDM). The obtained composites with EPDM and GTR are tested (5%, 10%, 20%) comparing these values with neat EPDM as a control sample. Thermal tests such as differential calorimetry (DSC) and thermogravimetric analysis (TGA) as well as dielectric tests (DEA) are performed in order to characterize these materials and check their viability as dielectric or semiconductor, for industrial use. It is checked how the presence of GTR increases functional properties such as conductivity/permittivity. The influence of temperature (40 to 120 °C) and addition of GTR particles in electrical properties has also been analyzed. The dielectric behavior of these composites is fully characterized, analyzing the different types of relaxation with increasing frequency (10 mHz to 3 MHz), using the electric modulus, and Argand diagrams among other measures. The influence of GTR and temperature in the dielectric and thermal behavior of these materials has been analyzed, where CB of GTR creates interfacial polarization phenomena in the dielectric behavior of the composite and increases the permittivity (real and imaginary) as well as the conductivity. Finally, with these obtained properties, the possible application of EPDM/GTR composites as industrial dielectrics has been studiedComparative study of mechanical and electrical relaxations in poly(etherimide). Part 2Diaz Calleja, RicardoFriederichs, S.Jaímes, C.Sanchis, Jose MariaBelana Punseti, JuanCañadas Lorenzo, Juan CarlosDiego Vives, José AntonioMudarra López, Miguelhttp://hdl.handle.net/2117/3304502021-05-20T16:15:10Z2020-10-19T17:39:49ZComparative study of mechanical and electrical relaxations in poly(etherimide). Part 2
Diaz Calleja, Ricardo; Friederichs, S.; Jaímes, C.; Sanchis, Jose Maria; Belana Punseti, Juan; Cañadas Lorenzo, Juan Carlos; Diego Vives, José Antonio; Mudarra López, Miguel
The curves describing the relaxation behaviour of poly(etherimide) at several frequencies shows in the dielectric lossÈtemperature plot c and b relax- ations centred at [95¡C and 100¡C, respectively, at 10 Hz. The glassÈrubber relaxation or a process appears at 225¡C at 10 Hz; at this temperature free charge conductivity and blocking electrode phenomena become dominant at fre- quencies below 10 Hz. The same three relaxations are observed by dynamic mechanical thermal analysis (DMS). The strength of the c and a relaxations can be estimated from the Ðtting of empirical relaxation functions, such as the FuossÈ Kirkwood and HavriliakÈNegami equations, to the dielectric data measured in the frequency domain. An electric model was used to separate the dipolar response from conductivity contributions in the glassÈrubber relaxation. Finally, the e†ect of water on the low-temperature relaxation has been demonstrated by dielectric and mechanical measurements.
2020-10-19T17:39:49ZDiaz Calleja, RicardoFriederichs, S.Jaímes, C.Sanchis, Jose MariaBelana Punseti, JuanCañadas Lorenzo, Juan CarlosDiego Vives, José AntonioMudarra López, MiguelThe curves describing the relaxation behaviour of poly(etherimide) at several frequencies shows in the dielectric lossÈtemperature plot c and b relax- ations centred at [95¡C and 100¡C, respectively, at 10 Hz. The glassÈrubber relaxation or a process appears at 225¡C at 10 Hz; at this temperature free charge conductivity and blocking electrode phenomena become dominant at fre- quencies below 10 Hz. The same three relaxations are observed by dynamic mechanical thermal analysis (DMS). The strength of the c and a relaxations can be estimated from the Ðtting of empirical relaxation functions, such as the FuossÈ Kirkwood and HavriliakÈNegami equations, to the dielectric data measured in the frequency domain. An electric model was used to separate the dipolar response from conductivity contributions in the glassÈrubber relaxation. Finally, the e†ect of water on the low-temperature relaxation has been demonstrated by dielectric and mechanical measurements.Influence of Polymethylmethacrylate microstructure on its conductive properties at high temperatureGuarrotxena Arlunduaga, Miren NekaneMudarra López, Miguelhttp://hdl.handle.net/2117/1853622020-09-01T00:29:44Z2020-04-28T06:12:06ZInfluence of Polymethylmethacrylate microstructure on its conductive properties at high temperature
Guarrotxena Arlunduaga, Miren Nekane; Mudarra López, Miguel
The influence of a set of tacticity-governed microstructures on the conductive properties of poly(methyl methacrylate) has been studied at high temperatures. Those structures are specially the mmmr and the mmmmrx (x = m or r), which occur when an isotactic sequence breaks-off, and also the rrrm-based termini of syndiotactic sequences. The electrical properties have been studied at the electrical modulus level, assuming a dispersive conductivity to explain conduction processes and Havriliak-Negami equation to evaluate dipolar contribution. A good agreement between experimental data and the model is observed, and some considerations about the conductive processes can be concluded. Conductivity is thermally activated at the temperature range considered, and ac regime can be associated with a correlated ion hopping of carrier process, which does not reacha strongly correlated regime, what we associate with a high relaxation time of carriers at high temperatures that do allow carriers to follow processes associated to a.c. regime.Interestingly, conductivity is shown to be dependent on the mmmrm-based stereosequences longer than one heptad. These stereosequences have been shown to exhibit enhanced free volume and rotational motion, what may explain the conductivity-mmmrm structure correlations as found on this work.
2020-04-28T06:12:06ZGuarrotxena Arlunduaga, Miren NekaneMudarra López, MiguelThe influence of a set of tacticity-governed microstructures on the conductive properties of poly(methyl methacrylate) has been studied at high temperatures. Those structures are specially the mmmr and the mmmmrx (x = m or r), which occur when an isotactic sequence breaks-off, and also the rrrm-based termini of syndiotactic sequences. The electrical properties have been studied at the electrical modulus level, assuming a dispersive conductivity to explain conduction processes and Havriliak-Negami equation to evaluate dipolar contribution. A good agreement between experimental data and the model is observed, and some considerations about the conductive processes can be concluded. Conductivity is thermally activated at the temperature range considered, and ac regime can be associated with a correlated ion hopping of carrier process, which does not reacha strongly correlated regime, what we associate with a high relaxation time of carriers at high temperatures that do allow carriers to follow processes associated to a.c. regime.Interestingly, conductivity is shown to be dependent on the mmmrm-based stereosequences longer than one heptad. These stereosequences have been shown to exhibit enhanced free volume and rotational motion, what may explain the conductivity-mmmrm structure correlations as found on this work.Charge storage and retention in electret dielectric layers for energy harvesting applicationsDiáz-Ballester, A.Castillo-Anguera, SRafi, J. M.Gómez-Martínez, R.Abadal, G.Figueras, E.Plaza, J.A.Esteve, J.Mudarra López, MiguelCañadas Lorenzo, Juan Carloshttp://hdl.handle.net/2117/1326662020-07-23T23:04:53Z2019-05-07T11:57:04ZCharge storage and retention in electret dielectric layers for energy harvesting applications
Diáz-Ballester, A.; Castillo-Anguera, S; Rafi, J. M.; Gómez-Martínez, R.; Abadal, G.; Figueras, E.; Plaza, J.A.; Esteve, J.; Mudarra López, Miguel; Cañadas Lorenzo, Juan Carlos
By providing a permanent electric polarization, electrets have a wide range of applications in different fields like sensors and actuators, energy harvesting or biomedicine. Stable electrets with silicon-based compatible technology are particularly pursued. In this work, different dielectric layer stacks, including SiO 2 , Si 3 N 4 , AL 2 O 3 and AlN, are evaluated in terms of charge storage and retention. The corona charging characteristics are analyzed and local micro-breakdowns of the dielectric layers are observed for critical electric fields in the range of 6-7 MV/cm. A hexamethyldisilazane (HMDS) surface treatment is confirmed to provide an effective protection for electret charge retention. Unfortunately for potential applications involving liquids, the charge is found to vanish after electret surface soaking with either deionized water or ethanol. In principle, deeper charge storage in the electret dielectric layers could be achieved by using an alternative method based on charge injection by means of a direct contact. The results of first attempts with such alternative technique are also reported.
2019-05-07T11:57:04ZDiáz-Ballester, A.Castillo-Anguera, SRafi, J. M.Gómez-Martínez, R.Abadal, G.Figueras, E.Plaza, J.A.Esteve, J.Mudarra López, MiguelCañadas Lorenzo, Juan CarlosBy providing a permanent electric polarization, electrets have a wide range of applications in different fields like sensors and actuators, energy harvesting or biomedicine. Stable electrets with silicon-based compatible technology are particularly pursued. In this work, different dielectric layer stacks, including SiO 2 , Si 3 N 4 , AL 2 O 3 and AlN, are evaluated in terms of charge storage and retention. The corona charging characteristics are analyzed and local micro-breakdowns of the dielectric layers are observed for critical electric fields in the range of 6-7 MV/cm. A hexamethyldisilazane (HMDS) surface treatment is confirmed to provide an effective protection for electret charge retention. Unfortunately for potential applications involving liquids, the charge is found to vanish after electret surface soaking with either deionized water or ethanol. In principle, deeper charge storage in the electret dielectric layers could be achieved by using an alternative method based on charge injection by means of a direct contact. The results of first attempts with such alternative technique are also reported.Effects of UV radiation on the charge trapping capability of PETCañadas Lorenzo, Juan CarlosDiego Vives, José AntonioMudarra López, MiguelParsa, Seyedeh ElahehSellarès González, Jordihttp://hdl.handle.net/2117/1308182022-11-20T08:33:58Z2019-03-25T14:41:43ZEffects of UV radiation on the charge trapping capability of PET
Cañadas Lorenzo, Juan Carlos; Diego Vives, José Antonio; Mudarra López, Miguel; Parsa, Seyedeh Elaheh; Sellarès González, Jordi
Poly(ethylene terephthalate) (PET) is able to retain space charge in traps, as is usual in dielectric materials. This allows the material to attain an almost permanent polarization when space charge is displaced by an external electric field or is injected from an electrode. We have studied the influence of UV irradiation on the charge trapping capability of PET in samples exposed for different periods of time, up to 10 weeks. The pulsed electro-acoustic technique (PEA) has been used to determine the charge profile. The injected charge that the material is able to retain on the irradiated surface increases with irradiation time. This indicates the formation of new traps. An extensive characterization of these localized states has been performed by the technique of thermally stimulated depolarization currents. Parameters of charge relaxation kinetics have been obtained by fitting spectra of the space charge relaxation current of a semicrystalline polymeric material peak (), related to injected charge, to the general-order kinetics model. A relaxation map analysis shows that relaxation times become more distributed and the activation energy decreases as irradiation time is increased. The activation energy decreases by approximately 10% after 10 weeks of exposure. These results show that UV irradiation creates additional traps on the treated surface, which agrees with PEA results, and that the energy depth of these traps is shallower and it is more distributed than in the case of pre-existing traps.
2019-03-25T14:41:43ZCañadas Lorenzo, Juan CarlosDiego Vives, José AntonioMudarra López, MiguelParsa, Seyedeh ElahehSellarès González, JordiPoly(ethylene terephthalate) (PET) is able to retain space charge in traps, as is usual in dielectric materials. This allows the material to attain an almost permanent polarization when space charge is displaced by an external electric field or is injected from an electrode. We have studied the influence of UV irradiation on the charge trapping capability of PET in samples exposed for different periods of time, up to 10 weeks. The pulsed electro-acoustic technique (PEA) has been used to determine the charge profile. The injected charge that the material is able to retain on the irradiated surface increases with irradiation time. This indicates the formation of new traps. An extensive characterization of these localized states has been performed by the technique of thermally stimulated depolarization currents. Parameters of charge relaxation kinetics have been obtained by fitting spectra of the space charge relaxation current of a semicrystalline polymeric material peak (), related to injected charge, to the general-order kinetics model. A relaxation map analysis shows that relaxation times become more distributed and the activation energy decreases as irradiation time is increased. The activation energy decreases by approximately 10% after 10 weeks of exposure. These results show that UV irradiation creates additional traps on the treated surface, which agrees with PEA results, and that the energy depth of these traps is shallower and it is more distributed than in the case of pre-existing traps.Influence of internal flexibility on the double glass transition in a series of odd non-symmetric liquid crystal dimers characterised by dielectric measurementsDiego Vives, José AntonioSellarès González, JordiDíez Berart, SergioSalud Puig, JosepCañadas Lorenzo, Juan CarlosMudarra López, MiguelLópez Pérez, David Orenciode la Fuente Lavin, Maria RosarioRos, M Blancahttp://hdl.handle.net/2117/1064222020-07-23T21:38:50Z2017-07-14T09:36:40ZInfluence of internal flexibility on the double glass transition in a series of odd non-symmetric liquid crystal dimers characterised by dielectric measurements
Diego Vives, José Antonio; Sellarès González, Jordi; Díez Berart, Sergio; Salud Puig, Josep; Cañadas Lorenzo, Juan Carlos; Mudarra López, Miguel; López Pérez, David Orencio; de la Fuente Lavin, Maria Rosario; Ros, M Blanca
Dielectric measurements (thermally stimulated depolarisation currents and broadband dielectric spectroscopy) have been performed near the glass transition to study the glass transition on the odd non-symmetric liquid crystal (LC) dimers of the series -(4-cyanobiphenyl-4'-oxy)--(1-pyreniminebenzylidene-4'-oxy) alkanes (CBOnO.Py) with n ranging from 3 to 9. A previous study [S. Diez-Berart et al., Materials 8 (2015) 3334] carried out in CBO11O.Py showed the presence of two glass transition temperatures, attributed to different molecular motions of the terminal groups. The study performed allows us to analyse the molecular dynamics in the rest of the series and determine the role played by the flexible spacer. Parallel and perpendicular orientations of the molecular director with regards to the probe electric field have been investigated. The low and intermediate observed relaxations are explained in the framework of Stocchero's theoretical model [M. Stocchero, J. Chem. Phys. 121 (2004) 8079] for the dielectric behaviour of non-symmetric LCs dimers, as independent end-over-end rotations of each terminal semi-rigid unit. As the length of the spacer chain in the series of compounds decreases, the different relaxations become progressively more coupled at the glass transition. Numerical simulations of the calorimetric response from the obtained kinetic parameters show good agreement with experimental behaviour.
2017-07-14T09:36:40ZDiego Vives, José AntonioSellarès González, JordiDíez Berart, SergioSalud Puig, JosepCañadas Lorenzo, Juan CarlosMudarra López, MiguelLópez Pérez, David Orenciode la Fuente Lavin, Maria RosarioRos, M BlancaDielectric measurements (thermally stimulated depolarisation currents and broadband dielectric spectroscopy) have been performed near the glass transition to study the glass transition on the odd non-symmetric liquid crystal (LC) dimers of the series -(4-cyanobiphenyl-4'-oxy)--(1-pyreniminebenzylidene-4'-oxy) alkanes (CBOnO.Py) with n ranging from 3 to 9. A previous study [S. Diez-Berart et al., Materials 8 (2015) 3334] carried out in CBO11O.Py showed the presence of two glass transition temperatures, attributed to different molecular motions of the terminal groups. The study performed allows us to analyse the molecular dynamics in the rest of the series and determine the role played by the flexible spacer. Parallel and perpendicular orientations of the molecular director with regards to the probe electric field have been investigated. The low and intermediate observed relaxations are explained in the framework of Stocchero's theoretical model [M. Stocchero, J. Chem. Phys. 121 (2004) 8079] for the dielectric behaviour of non-symmetric LCs dimers, as independent end-over-end rotations of each terminal semi-rigid unit. As the length of the spacer chain in the series of compounds decreases, the different relaxations become progressively more coupled at the glass transition. Numerical simulations of the calorimetric response from the obtained kinetic parameters show good agreement with experimental behaviour.Experimental study of different LFF regimes in semiconductor lasers with an external cavityAragoneses Aguado, AndrésZamora Munt, JordiTiana Alsina, JordiTorrent Serra, Maria del CarmenMasoller Alonso, Cristinahttp://hdl.handle.net/2117/1059422021-11-07T01:26:18Z2017-06-28T12:47:06ZExperimental study of different LFF regimes in semiconductor lasers with an external cavity
Aragoneses Aguado, Andrés; Zamora Munt, Jordi; Tiana Alsina, Jordi; Torrent Serra, Maria del Carmen; Masoller Alonso, Cristina
2017-06-28T12:47:06ZAragoneses Aguado, AndrésZamora Munt, JordiTiana Alsina, JordiTorrent Serra, Maria del CarmenMasoller Alonso, CristinaA new approach to design an efficient micropost array for enhanced direct-current insulator-based dielectrophoretic trappingMohammadi, MahdiJavad Zare, MohammadMadadi, HojjatSellarès González, JordiCasals Terré, Jasminahttp://hdl.handle.net/2117/1023662020-07-23T22:29:45Z2017-03-13T10:01:04ZA new approach to design an efficient micropost array for enhanced direct-current insulator-based dielectrophoretic trapping
Mohammadi, Mahdi; Javad Zare, Mohammad; Madadi, Hojjat; Sellarès González, Jordi; Casals Terré, Jasmina
Direct-current insulator-based dielectrophoresis (DC-iDEP) is a well-known technique that benefits from the electric field gradients generated by an array of insulating posts to separate or trap biological particles. The aim of this study is to provide a first geometrical relationship of the post array that independent of the particles and/or medium, maximizes the trapping. A novel figure of merit is proposed to maximize the particle trapping in the post array while minimizing the required voltage, with a similar footprint and channel thickness. Different post array models with the variation of transversal distance (10 to 60 µm), longitudinal distance (10 to 80 µm), and post radius (10 to 150 µm) were analyzed using COMSOL Multiphysics finite element software. The obtained results indicated that a post radius of 40 µm larger than the transversal distance between posts could enhance the trapping condition between 56 % (for a transversal distance of 10 µm) and 341 % (for a transversal distance of 60 µm). For the validation of the numerical results, several microchannels with embedded post arrays were manufactured in polydimethylsiloxane (PDMS) and the particle trapping patterns of 6-µm-diameter polystyrene particles were measured experimentally. The experiments confirm the same trends as pointed out by the numerical analysis. The results show that this new figure of merit and geometrical relationship can be used to reduce the required electric field to achieve effective particle trapping and, therefore, avoid the negative effects of Joule heating in cells or viable particles. The main advantage of these results is that they depend only on the geometry of the micropost array and are valid for trapping different particles suspended in different media.
This is a copy of the author 's final draft version of an article published in the journal Analytical and bioanalytical chemistry. The final publication is available at Springer via http://dx.doi.org/10.1007/s00216-016-9629-2
2017-03-13T10:01:04ZMohammadi, MahdiJavad Zare, MohammadMadadi, HojjatSellarès González, JordiCasals Terré, JasminaDirect-current insulator-based dielectrophoresis (DC-iDEP) is a well-known technique that benefits from the electric field gradients generated by an array of insulating posts to separate or trap biological particles. The aim of this study is to provide a first geometrical relationship of the post array that independent of the particles and/or medium, maximizes the trapping. A novel figure of merit is proposed to maximize the particle trapping in the post array while minimizing the required voltage, with a similar footprint and channel thickness. Different post array models with the variation of transversal distance (10 to 60 µm), longitudinal distance (10 to 80 µm), and post radius (10 to 150 µm) were analyzed using COMSOL Multiphysics finite element software. The obtained results indicated that a post radius of 40 µm larger than the transversal distance between posts could enhance the trapping condition between 56 % (for a transversal distance of 10 µm) and 341 % (for a transversal distance of 60 µm). For the validation of the numerical results, several microchannels with embedded post arrays were manufactured in polydimethylsiloxane (PDMS) and the particle trapping patterns of 6-µm-diameter polystyrene particles were measured experimentally. The experiments confirm the same trends as pointed out by the numerical analysis. The results show that this new figure of merit and geometrical relationship can be used to reduce the required electric field to achieve effective particle trapping and, therefore, avoid the negative effects of Joule heating in cells or viable particles. The main advantage of these results is that they depend only on the geometry of the micropost array and are valid for trapping different particles suspended in different media.Study of the charge profile of thermally poled electretsParsa, Seyedeh ElahehTrull Silvestre, José FranciscoColom Fajula, XavierSellarès González, Jordihttp://hdl.handle.net/2117/1017942022-11-20T09:17:28Z2017-03-01T12:55:42ZStudy of the charge profile of thermally poled electrets
Parsa, Seyedeh Elaheh; Trull Silvestre, José Francisco; Colom Fajula, Xavier; Sellarès González, Jordi
The charge profile of thermally poled electrets has been studied using two different methods, laser induced pressure pulse (LIPP) and pulsed electroacoustic (PEA), to gain insight into the mechanisms that are activated and assess which is the most appropriate method to study the charge profile. Disc–shaped PET samples have been conventionally poled to activate both the a and the ¿ relaxation and, right after, partially discharged up to a temperature Tpd . In this way, samples with a different combination of dipolar and space charge polarization have been obtained. Both LIPP and PEA reveal asymmetric profiles for Tpd below the glass transition temperature, that progressively become antisymmetric for higher temperatures. The shape and evolution of the charge profiles can be explained assuming injection of negative carriers from the anode that enhances the trapping of positive carriers near this electrode. It can be observed that PEA is able to detect a wider variety of polarization mechanisms in the system while LIPP gives a simpler picture of the charge profile.
Preprint
2017-03-01T12:55:42ZParsa, Seyedeh ElahehTrull Silvestre, José FranciscoColom Fajula, XavierSellarès González, JordiThe charge profile of thermally poled electrets has been studied using two different methods, laser induced pressure pulse (LIPP) and pulsed electroacoustic (PEA), to gain insight into the mechanisms that are activated and assess which is the most appropriate method to study the charge profile. Disc–shaped PET samples have been conventionally poled to activate both the a and the ¿ relaxation and, right after, partially discharged up to a temperature Tpd . In this way, samples with a different combination of dipolar and space charge polarization have been obtained. Both LIPP and PEA reveal asymmetric profiles for Tpd below the glass transition temperature, that progressively become antisymmetric for higher temperatures. The shape and evolution of the charge profiles can be explained assuming injection of negative carriers from the anode that enhances the trapping of positive carriers near this electrode. It can be observed that PEA is able to detect a wider variety of polarization mechanisms in the system while LIPP gives a simpler picture of the charge profile.Confección y gestión automática de exámenes tipo testCañadas Lorenzo, Juan CarlosDiego Vives, José AntonioPelayo Melero, Ignacio Manuelhttp://hdl.handle.net/2117/972602020-07-23T22:24:12Z2016-11-25T13:35:58ZConfección y gestión automática de exámenes tipo test
Cañadas Lorenzo, Juan Carlos; Diego Vives, José Antonio; Pelayo Melero, Ignacio Manuel
El presente trabajo describe la implementación de una aplicación informática como recurso docente, diseñada como plataforma para la elaboración, utilización y corrección de controles formativos y exámenes de evaluación. La principal finalidad de esta aplicación es poder facilitar la elaboración de diversos exámenes tipo test, tanto presenciales como no presenciales, con su correspondiente proceso de autocorrección, siendo así un software específico de evaluación a través de Internet. El programa que presentamos es ideal para llevar a cabo evaluaciones con
una gran variedad de preguntas empleadas de forma individual y simultánea para todos los estudiantes. Entre las ventajas de la aplicación, destacan, por un lado, su facilidad para generar una gran multiplicidad de exámenes independientes tanto para pruebas presenciales como para las no presenciales en donde el alumno puede hacer el examen de forma offline (imprimiendo un archivo pdf), y por otro, la posibilidad de enviar las respuestas dentro de un
tiempo predeterminado, mediante conexión a la red. Se trata de un software diseñado en el seno del Departamento de Física de la Universitat Politècnica de Catalunya (BarcelonaTech), y utilizado con gran éxito en sucesivas versiones, en las asignaturas de Física de las titulaciones de la ESEIAAT, la escuela de Ingeniería Industrial y Aeronáutica de Terrassa.
2016-11-25T13:35:58ZCañadas Lorenzo, Juan CarlosDiego Vives, José AntonioPelayo Melero, Ignacio ManuelEl presente trabajo describe la implementación de una aplicación informática como recurso docente, diseñada como plataforma para la elaboración, utilización y corrección de controles formativos y exámenes de evaluación. La principal finalidad de esta aplicación es poder facilitar la elaboración de diversos exámenes tipo test, tanto presenciales como no presenciales, con su correspondiente proceso de autocorrección, siendo así un software específico de evaluación a través de Internet. El programa que presentamos es ideal para llevar a cabo evaluaciones con
una gran variedad de preguntas empleadas de forma individual y simultánea para todos los estudiantes. Entre las ventajas de la aplicación, destacan, por un lado, su facilidad para generar una gran multiplicidad de exámenes independientes tanto para pruebas presenciales como para las no presenciales en donde el alumno puede hacer el examen de forma offline (imprimiendo un archivo pdf), y por otro, la posibilidad de enviar las respuestas dentro de un
tiempo predeterminado, mediante conexión a la red. Se trata de un software diseñado en el seno del Departamento de Física de la Universitat Politècnica de Catalunya (BarcelonaTech), y utilizado con gran éxito en sucesivas versiones, en las asignaturas de Física de las titulaciones de la ESEIAAT, la escuela de Ingeniería Industrial y Aeronáutica de Terrassa.