E-printshttp://hdl.handle.net/2117/285772018-04-26T22:45:42Z2018-04-26T22:45:42ZA multiple model adaptive architecture for the state estimation in discrete-time uncertain LPV systemsRotondo, DamianoHassani, VahidCristofaro, Andreahttp://hdl.handle.net/2117/1167492018-04-26T21:35:14Z2018-04-26T21:35:14ZA multiple model adaptive architecture for the state estimation in discrete-time uncertain LPV systems
Rotondo, Damiano; Hassani, Vahid; Cristofaro, Andrea
This paper addresses the problem of multiple model adaptive estimation (MMAE) for discrete-time linear parameter varying (LPV) systems that are affected by parametric uncertainty. The MMAE system relies on a finite number of local observers, each designed using a selected model (SM) from the set of possible plant models. Each local observer is an LPV Kalman filter, obtained as a linear combination of linear time invariant (LTI) Kalman filters. It is shown that if some suitable distinguishability conditions are fulfilled, the MMAE will identify the SM corresponding to the local observer with smallest output prediction error energy. The convergence of the unknown parameter estimation, and its relation with the varying parameters, are discussed. Simulation results illustrate the application of the proposed method.
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2018-04-26T21:35:14ZRotondo, DamianoHassani, VahidCristofaro, AndreaThis paper addresses the problem of multiple model adaptive estimation (MMAE) for discrete-time linear parameter varying (LPV) systems that are affected by parametric uncertainty. The MMAE system relies on a finite number of local observers, each designed using a selected model (SM) from the set of possible plant models. Each local observer is an LPV Kalman filter, obtained as a linear combination of linear time invariant (LTI) Kalman filters. It is shown that if some suitable distinguishability conditions are fulfilled, the MMAE will identify the SM corresponding to the local observer with smallest output prediction error energy. The convergence of the unknown parameter estimation, and its relation with the varying parameters, are discussed. Simulation results illustrate the application of the proposed method.Study of medium range reordering by plastic deformation in Cu46Zr46Al8Velasco Cruz, Jorge EnriqueConcustell, AmadeuPineda Soler, EloiCrespo Artiaga, Danielhttp://hdl.handle.net/2117/1167482018-04-26T18:04:56Z2018-04-26T18:04:56ZStudy of medium range reordering by plastic deformation in Cu46Zr46Al8
Velasco Cruz, Jorge Enrique; Concustell, Amadeu; Pineda Soler, Eloi; Crespo Artiaga, Daniel
The influence of shear in the atomic structure of ternary Cu46Zr46Al8 metallic glass was studied at different temperatures by molecular dynamics (MD) simulation. At temperatures above and below the glass transition temperature the system was subjected to a shear deformation cycle; the shear deformation was carried in the [100] direction and then the original geometry was recovered. The system was analyzed in three states: initial state (before deformation), deformed state (sheared) and final state (recovery). The different states obtained by the atomistic simulations were examined by computing the directional pair distribution functions (dPDF) in the coordinate planes. The results showed by dPDFs of the planes perpendicular to the coordinate axis are apparently isotropic. However, the dPDF disengage when computed perpendicular to rotated axis. This reveals that the anisotropy introduced during the deformation cycles appears in directions [110] and [1?0], tilted 45° with respect to the direction of the applied shear. To analyze the subtle structural change we systematically computed the positions and widths of the dPDF peaks on the rotated directions, thence allowing us to describe in detail the different signatures of anisotropy induced by deformation in the metallic glasses.
2018-04-26T18:04:56ZVelasco Cruz, Jorge EnriqueConcustell, AmadeuPineda Soler, EloiCrespo Artiaga, DanielThe influence of shear in the atomic structure of ternary Cu46Zr46Al8 metallic glass was studied at different temperatures by molecular dynamics (MD) simulation. At temperatures above and below the glass transition temperature the system was subjected to a shear deformation cycle; the shear deformation was carried in the [100] direction and then the original geometry was recovered. The system was analyzed in three states: initial state (before deformation), deformed state (sheared) and final state (recovery). The different states obtained by the atomistic simulations were examined by computing the directional pair distribution functions (dPDF) in the coordinate planes. The results showed by dPDFs of the planes perpendicular to the coordinate axis are apparently isotropic. However, the dPDF disengage when computed perpendicular to rotated axis. This reveals that the anisotropy introduced during the deformation cycles appears in directions [110] and [1?0], tilted 45° with respect to the direction of the applied shear. To analyze the subtle structural change we systematically computed the positions and widths of the dPDF peaks on the rotated directions, thence allowing us to describe in detail the different signatures of anisotropy induced by deformation in the metallic glasses.Environmental pollution produced by gold artisanal mining in the Mapiri river basin, Apolobamba, BoliviaVillegas Flores, Karla StephanieAlfonso Abella, María PuraHigueras Higueras, Pablo LeonPalacios Ubach, SilviaEsbrí, José MaríaGarcía-Noguero, E. M.http://hdl.handle.net/2117/1167472018-04-26T16:59:19Z2018-04-26T16:59:19ZEnvironmental pollution produced by gold artisanal mining in the Mapiri river basin, Apolobamba, Bolivia
Villegas Flores, Karla Stephanie; Alfonso Abella, María Pura; Higueras Higueras, Pablo Leon; Palacios Ubach, Silvia; Esbrí, José María; García-Noguero, E. M.
Mining activity is very important in Bolivia since colonial times. Today it has been reactivated, especially gold mining, due to rise in metal prices. Artisanal and small-scale mining activities are abundant in the protected area of Apolobamba, near the border with Peru. Here mercury is used to recovery gold by obtaining an Hg-Au amalgam.
This manipulation with mercury causes an important environmental impact in the area.
The present work is a preliminary study of the contamination of the Mapiri river basin in the Apolobamba area.
In the head of this basin, located at more than 4000 m above sea level, gold is mined from hydrothermal gold
deposits of Paleozoic age. We have sampled several mining sites from this area, in particular the ones known as
Viscachani, Flor de Mayo and Chojlaya, located in the proximity of the head area of the Mapiri river basin. These mining sites were in activity during the present sampling campaign.
Different metals were measured by means of XRF (Se, As, Cu, Zn, Cd, Pb, Hg) in tailing samples from the different gold mining sites. In addition mercury concentrations were measured in water and in vegetation close
to the processing areas by means of atomic absorption spectrometry with Zeeman effect (LUMEX RA-915 Equipment).
Tailings are mainly constituted by quartz with minor contents of clay minerals and sulphides. The most abundant sulphides are galena and arsenopyrite. Chalcopyrite, sphalerite, pyrite and sulphosalts also occur in minor
amounts, as well as minor secondary minerals. Gold content, after recovery with mercury, is high, between 4.56 ppm and 10.35 ppm.
The Hg content of the tailings ranges from 149 to 1027 ppm. Lixiviable mercury from these samples ranges between 30.10 and 859.94 ng l-1. Water released from the tailings contains between 0.1 and 5.7 ppb of Hg.
Studied vegetation typical of the area has high Hg contents, between 162 and 219 ppm.
In addition there is a high arsenic content in all the studied tailings, except in those from the Viscachani mining site, where concentrations of this element ranges from 456 ppm to 18540 ppm. The Pb content usually ranges from 337 to 939 ppm. The Chojlaya mining site tailing has exceptionally high values of heavy metals: Pb content is between 2.26 and 3.27 wt.%, Cd ranges from 160 to 228 ppm, Zn from 194 to 794 ppm, Cu from 847 to 1052 ppm and Se from 105 to 187 ppm. These contents also contribute to an environmental pollution.
In conclusion the gold mining activities in the Mapiri river basin produce and intense environmental pollution, mainly related to mercury and arsenic contents in the proximity of these mining activities. After processing,
tailings still contain important amounts of gold suggesting that the amalgamation method is not effective to gold recovering.
2018-04-26T16:59:19ZVillegas Flores, Karla StephanieAlfonso Abella, María PuraHigueras Higueras, Pablo LeonPalacios Ubach, SilviaEsbrí, José MaríaGarcía-Noguero, E. M.Mining activity is very important in Bolivia since colonial times. Today it has been reactivated, especially gold mining, due to rise in metal prices. Artisanal and small-scale mining activities are abundant in the protected area of Apolobamba, near the border with Peru. Here mercury is used to recovery gold by obtaining an Hg-Au amalgam.
This manipulation with mercury causes an important environmental impact in the area.
The present work is a preliminary study of the contamination of the Mapiri river basin in the Apolobamba area.
In the head of this basin, located at more than 4000 m above sea level, gold is mined from hydrothermal gold
deposits of Paleozoic age. We have sampled several mining sites from this area, in particular the ones known as
Viscachani, Flor de Mayo and Chojlaya, located in the proximity of the head area of the Mapiri river basin. These mining sites were in activity during the present sampling campaign.
Different metals were measured by means of XRF (Se, As, Cu, Zn, Cd, Pb, Hg) in tailing samples from the different gold mining sites. In addition mercury concentrations were measured in water and in vegetation close
to the processing areas by means of atomic absorption spectrometry with Zeeman effect (LUMEX RA-915 Equipment).
Tailings are mainly constituted by quartz with minor contents of clay minerals and sulphides. The most abundant sulphides are galena and arsenopyrite. Chalcopyrite, sphalerite, pyrite and sulphosalts also occur in minor
amounts, as well as minor secondary minerals. Gold content, after recovery with mercury, is high, between 4.56 ppm and 10.35 ppm.
The Hg content of the tailings ranges from 149 to 1027 ppm. Lixiviable mercury from these samples ranges between 30.10 and 859.94 ng l-1. Water released from the tailings contains between 0.1 and 5.7 ppb of Hg.
Studied vegetation typical of the area has high Hg contents, between 162 and 219 ppm.
In addition there is a high arsenic content in all the studied tailings, except in those from the Viscachani mining site, where concentrations of this element ranges from 456 ppm to 18540 ppm. The Pb content usually ranges from 337 to 939 ppm. The Chojlaya mining site tailing has exceptionally high values of heavy metals: Pb content is between 2.26 and 3.27 wt.%, Cd ranges from 160 to 228 ppm, Zn from 194 to 794 ppm, Cu from 847 to 1052 ppm and Se from 105 to 187 ppm. These contents also contribute to an environmental pollution.
In conclusion the gold mining activities in the Mapiri river basin produce and intense environmental pollution, mainly related to mercury and arsenic contents in the proximity of these mining activities. After processing,
tailings still contain important amounts of gold suggesting that the amalgamation method is not effective to gold recovering.Polluction caused by artisanal gold mining the Ocoña river Valley, PeruPalacios Ubach, SilviaAlfonso Abella, María PuraHigueras Higueras, Pablo LeonEsbri, José MariaGarcía-Noguero, Eva Maríahttp://hdl.handle.net/2117/1167462018-04-26T16:51:25Z2018-04-26T16:51:25ZPolluction caused by artisanal gold mining the Ocoña river Valley, Peru
Palacios Ubach, Silvia; Alfonso Abella, María Pura; Higueras Higueras, Pablo Leon; Esbri, José Maria; García-Noguero, Eva María
2018-04-26T16:51:25ZPalacios Ubach, SilviaAlfonso Abella, María PuraHigueras Higueras, Pablo LeonEsbri, José MariaGarcía-Noguero, Eva MaríaThe use of mercury for gold recovering in the artisanal gold mining from the Mapiri river basin, Apolobamba, BoliviaVillegas Flores, Karla StephanieAlfonso Abella, María PuraPalacios Ubach, SilviaHigueras Higueras, Pablo LeonEsbri, José MariaGarcía-Noguero, Eva Maríahttp://hdl.handle.net/2117/1167452018-04-26T17:01:08Z2018-04-26T16:43:38ZThe use of mercury for gold recovering in the artisanal gold mining from the Mapiri river basin, Apolobamba, Bolivia
Villegas Flores, Karla Stephanie; Alfonso Abella, María Pura; Palacios Ubach, Silvia; Higueras Higueras, Pablo Leon; Esbri, José Maria; García-Noguero, Eva María
2018-04-26T16:43:38ZVillegas Flores, Karla StephanieAlfonso Abella, María PuraPalacios Ubach, SilviaHigueras Higueras, Pablo LeonEsbri, José MariaGarcía-Noguero, Eva MaríaLarge-eddy simulations of the vortex-induced vibration of a low mass ratio two-degree-of-freedom circular cylinder at subcritical Reynolds numbersPastrana, DanielCajas, J.C.Lehmkuhl, OriolRodríguez Pérez, Ivette MaríaHouzeaux, Guillaumehttp://hdl.handle.net/2117/1167432018-04-26T16:03:13Z2018-04-26T16:03:13ZLarge-eddy simulations of the vortex-induced vibration of a low mass ratio two-degree-of-freedom circular cylinder at subcritical Reynolds numbers
Pastrana, Daniel; Cajas, J.C.; Lehmkuhl, Oriol; Rodríguez Pérez, Ivette María; Houzeaux, Guillaume
The vortex induced vibration phenomenon of a low mass ratio () two-degree-of-freedom circular cylinder at subcritical Reynolds numbers ( 5300, 11,000) has been investigated by means of large-eddy simulations. A low-dissipative spatial and time discretisation finite element schemes have been implemented and combined with the Wall-Adapting Local-Eddy viscosity (WALE) subgrid-scale model to solve the filtered incompressible flow equations. Several values of the reduced velocity in the range 3¿¿¿U*¿¿¿12 have been considered. The numerical results are extensively compared with available experimental and numerical data. Particular interest has been placed in the region of maximum cross-flow amplitudes, the super-upper branch, where previous high-fidelity numerical simulations have underestimated the peak amplitudes compared with experimental results. The transition between the super-upper and lower branches is also shown and described. The numerical simulations successfully reproduce the three-branch response maximum oscillation amplitudes and associated vortex formation modes. The 2T vortex formation mode, i.e. two triplets of vortices per oscillation period, has been observed to occur in the super-upper branch, for the three different values of the Reynolds number investigated. These results contradict the claim made in previous works [27] that the vortex formation mode in the super-upper branch is Reynolds number dependent. Beats are observed to appear prior the transition from the super-upper to the lower branch. It is argued that they may be related with the coherence and strength of the third vortex shed at the shoulder of the cylinder each half-cycle, which is finally suppressed in the transition to the lower branch.
2018-04-26T16:03:13ZPastrana, DanielCajas, J.C.Lehmkuhl, OriolRodríguez Pérez, Ivette MaríaHouzeaux, GuillaumeThe vortex induced vibration phenomenon of a low mass ratio () two-degree-of-freedom circular cylinder at subcritical Reynolds numbers ( 5300, 11,000) has been investigated by means of large-eddy simulations. A low-dissipative spatial and time discretisation finite element schemes have been implemented and combined with the Wall-Adapting Local-Eddy viscosity (WALE) subgrid-scale model to solve the filtered incompressible flow equations. Several values of the reduced velocity in the range 3¿¿¿U*¿¿¿12 have been considered. The numerical results are extensively compared with available experimental and numerical data. Particular interest has been placed in the region of maximum cross-flow amplitudes, the super-upper branch, where previous high-fidelity numerical simulations have underestimated the peak amplitudes compared with experimental results. The transition between the super-upper and lower branches is also shown and described. The numerical simulations successfully reproduce the three-branch response maximum oscillation amplitudes and associated vortex formation modes. The 2T vortex formation mode, i.e. two triplets of vortices per oscillation period, has been observed to occur in the super-upper branch, for the three different values of the Reynolds number investigated. These results contradict the claim made in previous works [27] that the vortex formation mode in the super-upper branch is Reynolds number dependent. Beats are observed to appear prior the transition from the super-upper to the lower branch. It is argued that they may be related with the coherence and strength of the third vortex shed at the shoulder of the cylinder each half-cycle, which is finally suppressed in the transition to the lower branch.Back junction n-type silicon heterojunction solar cells with V2O5 hole-selective contactGerling Sarabia, Luis GuillermoMasmitjà Rusiñol, GerardVoz Sánchez, CristóbalOrtega Villasclaras, Pablo RafaelPuigdollers i González, JoaquimAlcubilla González, Ramónhttp://hdl.handle.net/2117/1167412018-04-26T14:02:52Z2018-04-26T14:02:52ZBack junction n-type silicon heterojunction solar cells with V2O5 hole-selective contact
Gerling Sarabia, Luis Guillermo; Masmitjà Rusiñol, Gerard; Voz Sánchez, Cristóbal; Ortega Villasclaras, Pablo Rafael; Puigdollers i González, Joaquim; Alcubilla González, Ramón
2018-04-26T14:02:52ZGerling Sarabia, Luis GuillermoMasmitjà Rusiñol, GerardVoz Sánchez, CristóbalOrtega Villasclaras, Pablo RafaelPuigdollers i González, JoaquimAlcubilla González, RamónAnti-aging in ultrastable metallic glassesLüttich, MartinGiordano, ValentinaLeFloch, SylviePineda Soler, EloiZontone, FedericoLuo, YuansuSamwer, KonradRuta, Beatricehttp://hdl.handle.net/2117/1167402018-04-26T13:50:18Z2018-04-26T13:50:18ZAnti-aging in ultrastable metallic glasses
Lüttich, Martin; Giordano, Valentina; LeFloch, Sylvie; Pineda Soler, Eloi; Zontone, Federico; Luo, Yuansu; Samwer, Konrad; Ruta, Beatrice
As ultrastable metallic glasses (UMGs) are promising candidates to solve the stability issues of conventional metallic glasses, their study is of exceptional interest. By means of x -ray photon correlation spectroscopy, we have investigated the stability of UMGs at the atomic level. We find a clear signature of ultrastability at the atomic level that results in slower relaxation dynamics of UMGs with respect to conventional (rapidly quenched) metallic glasses, and in a peculiar acceleration of the dynamics by near T g annealing. This surprising phenomenon, called here anti-aging, can be understood in the framework of the potential energy landscape. For all samples, the structural relaxation process can be described with a highly compressed shape of the density fluctuations, unaffected by thermal treatments and regardless of the ultrastability of the glass.
This is the author final draft version of article https://doi.org/10.1103/PhysRevLett.120.135504
2018-04-26T13:50:18ZLüttich, MartinGiordano, ValentinaLeFloch, SylviePineda Soler, EloiZontone, FedericoLuo, YuansuSamwer, KonradRuta, BeatriceAs ultrastable metallic glasses (UMGs) are promising candidates to solve the stability issues of conventional metallic glasses, their study is of exceptional interest. By means of x -ray photon correlation spectroscopy, we have investigated the stability of UMGs at the atomic level. We find a clear signature of ultrastability at the atomic level that results in slower relaxation dynamics of UMGs with respect to conventional (rapidly quenched) metallic glasses, and in a peculiar acceleration of the dynamics by near T g annealing. This surprising phenomenon, called here anti-aging, can be understood in the framework of the potential energy landscape. For all samples, the structural relaxation process can be described with a highly compressed shape of the density fluctuations, unaffected by thermal treatments and regardless of the ultrastability of the glass.Application of mechanically alloyed MnAl particles to de-colorization of azo dyesAboliGhasemabadi, MitraMbarek Wael, BenCasabella, OriolRoca Bisbe, HelenaPineda Soler, EloiEscoda, LluïsaSuñol, Joan J.http://hdl.handle.net/2117/1167392018-04-26T13:40:44Z2018-04-26T13:40:44ZApplication of mechanically alloyed MnAl particles to de-colorization of azo dyes
AboliGhasemabadi, Mitra; Mbarek Wael, Ben; Casabella, Oriol; Roca Bisbe, Helena; Pineda Soler, Eloi; Escoda, Lluïsa; Suñol, Joan J.
The use of metallic particles has been shown to be an effective, low-cost method for degradation of many contaminating compounds. In this work, we analyze the efficiency of MnAl metallic powders for degrading azo dyes, which are the class of colorant compounds most utilized by the textile industry. We used different routes to produce the metallic particles obtaining different internal structures as characterized by X-ray diffraction and electronic microscopy. The ability to act as discoloration materials was assessed by decolorization experiments of Reactive Black 5 and Orange II azo dyes aqueous solutions. The degradation reaction of the dye molecules was monitored by ultraviolet–visible (UV) spectrophotometry showing fast kinetics, with reaction times among the shortest found in literature. The effect of the different production methods on their performance as decolorizing materials was studied as function as various parameters such as initial pH, dye concentration and temperature. The electrochemical and corrosion properties of the MnAl compounds seem to be the key factors explaining the high decolorization efficiency of these materials.
2018-04-26T13:40:44ZAboliGhasemabadi, MitraMbarek Wael, BenCasabella, OriolRoca Bisbe, HelenaPineda Soler, EloiEscoda, LluïsaSuñol, Joan J.The use of metallic particles has been shown to be an effective, low-cost method for degradation of many contaminating compounds. In this work, we analyze the efficiency of MnAl metallic powders for degrading azo dyes, which are the class of colorant compounds most utilized by the textile industry. We used different routes to produce the metallic particles obtaining different internal structures as characterized by X-ray diffraction and electronic microscopy. The ability to act as discoloration materials was assessed by decolorization experiments of Reactive Black 5 and Orange II azo dyes aqueous solutions. The degradation reaction of the dye molecules was monitored by ultraviolet–visible (UV) spectrophotometry showing fast kinetics, with reaction times among the shortest found in literature. The effect of the different production methods on their performance as decolorizing materials was studied as function as various parameters such as initial pH, dye concentration and temperature. The electrochemical and corrosion properties of the MnAl compounds seem to be the key factors explaining the high decolorization efficiency of these materials.Estimation of a room ventilation air change rate using a stochastic grey-box modelling approachMacarulla Martí, MarcelCasals Casanova, MiquelForcada Matheu, NúriaGangolells Solanellas, MartaGiretti, Albertohttp://hdl.handle.net/2117/1167382018-04-26T13:10:49Z2018-04-26T13:00:23ZEstimation of a room ventilation air change rate using a stochastic grey-box modelling approach
Macarulla Martí, Marcel; Casals Casanova, Miquel; Forcada Matheu, Núria; Gangolells Solanellas, Marta; Giretti, Alberto
The measurement of ventilation air change rate is a difficult, expensive task in buildings. Usually, the tracer-gas mass balance equation is used to determine ventilation air change rates. This method uses an ordinary differential equation. Consequently, it cannot deal with disturbances that enter the system, such as the influence of unrecognized and unmodelled inputs or the measurement noise. The use of the stochastic grey-box modelling approach, which is less common in the ventilation field, can help to deal with disturbances that can affect the system. The objective of this paper is to assess the potential of using the stochastic grey-box modelling approach to estimate the ventilation air change rate. The modelling is based on the stochastic differential equation of tracer-gas mass balance. The results show that this approach produces robust estimations to determine the ventilation air change rate of a room.
2018-04-26T13:00:23ZMacarulla Martí, MarcelCasals Casanova, MiquelForcada Matheu, NúriaGangolells Solanellas, MartaGiretti, AlbertoThe measurement of ventilation air change rate is a difficult, expensive task in buildings. Usually, the tracer-gas mass balance equation is used to determine ventilation air change rates. This method uses an ordinary differential equation. Consequently, it cannot deal with disturbances that enter the system, such as the influence of unrecognized and unmodelled inputs or the measurement noise. The use of the stochastic grey-box modelling approach, which is less common in the ventilation field, can help to deal with disturbances that can affect the system. The objective of this paper is to assess the potential of using the stochastic grey-box modelling approach to estimate the ventilation air change rate. The modelling is based on the stochastic differential equation of tracer-gas mass balance. The results show that this approach produces robust estimations to determine the ventilation air change rate of a room.