Andrés Rosales - Academia.edu (original) (raw)

Papers by Andrés Rosales

Physica B-condensed Matter, 2010

In this paper, the phase transformations occurring during the crystallization process of FINEMETs... more In this paper, the phase transformations occurring during the crystallization process of FINEMETs in which Nb has been gradually replaced by Mo have been studied by a variety of techniques including DSC, DTA, TGA, XRD and TEM. The thermal stability of the alloy was deteriorated as a consequence of Mo’s smaller atomic size. The gradual replacement of Nb by Mo reduced the onset temperature of Fe-Si and of the borides. The Curie temperature of the amorphous phase slightly decreased from 594 K for x=0 to 587 K for x=3. The borides compounds Fe2B and Fe23B6 as well as the (Nb,Mo)5Si3 phase were found to precipitate in the second and third crystallization.

Journal of Magnetism and Magnetic Materials, 2001

The random-"eld Ising model (RFIM) system Fe Zn F is studied by magnetization and AC susceptibili... more The random-"eld Ising model (RFIM) system Fe Zn F is studied by magnetization and AC susceptibility measurements, under "nite DC applied "elds (H). For weak random "elds (corresponding to H(20 KOe), the phase transition (PT) at ¹ (H) is accompanied by the critical slowing down inherent to the random "eld problem. For higher H, the PT is destroyed and a glassy dynamics dominates the magnetic behavior.

Physica B-condensed Matter, 2010

In this paper, the phase transformations occurring during the crystallization process of FINEMETs... more In this paper, the phase transformations occurring during the crystallization process of FINEMETs in which Nb has been gradually replaced by Mo have been studied by a variety of techniques including DSC, DTA, TGA, XRD and TEM.The thermal stability of the alloy was deteriorated as a consequence of Mo’s smaller atomic size. The gradual replacement of Nb by Mo reduced

Journal of Magnetism and Magnetic Materials, 2001

The random-field Ising model (RFIM) system Fe0.42Zn0.58F2 is studied by magnetization and AC susc... more The random-field Ising model (RFIM) system Fe0.42Zn0.58F2 is studied by magnetization and AC susceptibility measurements, under finite DC applied fields (/H). For weak random fields (corresponding to H<20KOe), the phase transition (PT) at Tc(/H) is accompanied by the critical slowing down inherent to the random field problem. For higher H, the PT is destroyed and a glassy dynamics dominates the magnetic behavior.

Gastrointestinal Endoscopy, 2009

and outcome were evaluated. An acute-overt bleeding was defined as hematemesis, rectal blood loss... more and outcome were evaluated. An acute-overt bleeding was defined as hematemesis, rectal blood loss and/or melena. Results: In the period 2005-2008 in 22 patients had BAE for acute-overt GI bleeding: 12 males, mean age 65 (35-87) years. All patients had negative upper-en ileocolonoscopy. Clinical presentation was rectal blood loss in 11 (50%), melena and blood cloths in 7 (32%) and hematemesis and melena in 4 (18%) patients. In 18 (82%) transfusion was necessary; 11 (50%) patients presented with hemodynamic instability. Mean hemoglobin at presentation was 7.0 (5.3-10.1) g/dL (mean MCV 88). In 11 (50%) patients use of NSAID's, steroids and/or oral anticoagulation was reported. The enteroscopes used were diagnostic DBE in 12, therapeutic DBE in 7, and SBE in 3 patients. Mean insertion depth was proximal 247 (130-400) cm and distal 96 (30-150) cm. During BAE a likely cause of bleeding was found in 10 (45%) patients: in 4 (40%) tumoreus laesions (2 GIST and 2 adenocardinoma), in 4 (40%) vascular abnormalities (3 angiodysplasia and 1 jejunal varices), and 2 Dieulafoy-like-lesions were found. The pathologic findings were all located in the jejunum: 5 proximal and 5 in the mid-distal jejunum. Endoscopic therapy was applied in 6 (60%) patients, 4 patients had surgery. Two patients died due to other causes, all other patients were symptom free at mean follow-up of 23 (3-38) months. In 5 (23%) patients, wireless capsule endoscopy (WCE) was performed before BAE: in 1 case WCE was true positive, WCE was false negative in 3 cases (1 angiodysplasia and 2 tumors) and in 1 case false positive. Conclusion: BAE found the source of GI bleeding in nearly half of patients presenting with an acuteovert GI bleeding, with an initial negative upper-and lower endoscopy. Cause of bleeding could be treated endoscopically in majority of patients. The sensitivity for detection of acute small bowel bleeding seems higher for BAE as compared to WCE.

Plant Cell Tissue and Organ Culture, 2001

The effects of NaCl-adaptation and NaCl-stress on in vivo H+ extrusion and microsomal vanadate- a... more The effects of NaCl-adaptation and NaCl-stress on in vivo H+ extrusion and microsomal vanadate- and bafilomycin-sensitive ATPase and PPase activities were studied in tomato cell suspensions. Acidification of the external medium by 50 mM NaCl-adapted and non-adapted (control) tomato cells was similar. Extracellular acidification by both types of cells during the first hour of incubation with 2 μM fusicoccin (FC) in the presence of 100 mM NaCl was lightly increased while in the presence of 100 mM KCl it was increased by 3 (control)- and 6.5 (adapted)-fold. Extracellular alkalinization after 2 h of cell incubation in 100 mM NaCl indicated the possibility that a Na+/H+ exchange activity could be operating in both types of cells. Moreover, acidification induced by adding 100 mM NaCl + FC to non-adapted cells was relatively less affected by vanadate than that induced by 5 mM KCl + FC, which suggested that salt stress could induce some component other than H+ extrusion by H+-ATPase. In addition, no differences were observed in microsomal vanadate-sensitive ATPase activity among control, NaCl-adapted and NaCl-stressed cells, while K+-stimulated H+-PPase and bafilomycin-sensitive H+-ATPase activities were higher in microsomes from NaCl-adapted than in those from control cells. Likewise, the stimulation of in vivo H+ extrusion in NaCl adapted cells under NaCl or KCl stress in the presence of FC occurred with an inhibition of H+-PPase and bafilomycin-sensitive H+-ATPase activities and without changes in the vanadate-sensitive H+-ATPase activity. These results suggest that the stimulation of tonoplast proton pumps in NaCl-adapted cells, without changes in plasmalemma H+-ATPase, could serve to energize Na+ efflux across the plasmalemma and Na+ fluxes into vacuoles catalyzed by the Na+/H+ antiports.

In this paper a model based controller for mobile robots by using numerical methods is developmen... more In this paper a model based controller for mobile robots by using numerical methods is development. The system is approximated using numerical methods, next, the linear equations theory is used to compute the control signals and to obtain the minimal error conditions. The dynamic model of the PIONNER 3DX mobile robot with external forces and wheels slides is considered. Experimental

Robotica, 2009

A new approach for navigation of mobile robots in dynamic environments by using Linear Algebra Th... more A new approach for navigation of mobile robots in dynamic environments by using Linear Algebra Theory, Numerical Methods, and a modification of the Force Field Method is presented in this paper. The controller design is based on the dynamic model of a unicycle-like nonholonomic mobile robot. Previous studies very often ignore the dynamics of mobile robots and suffer from algorithmic singularities. Simulation and experimentation results confirm the feasibility and the effectiveness of the proposed controller and the advantages of the dynamic model use. By using this new strategy, the robot is able to adapt its behavior at the available knowing level and it can navigate in a safe way, minimizing the tracking error.

A nonlinear benchmark problem, very interesting due to interaction between translational and rota... more A nonlinear benchmark problem, very interesting due to interaction between translational and rotational movements is the RTAC system (also called TORA). Diverse control techniques in several previous papers have been dedicated to it. The present work proposes, by means of a straightforward procedure, a controller design based on an approach of RTAC system, using numerical methods, so that the system tends to origin after being displaced of this position. The control signal is calculated through the resolution of a linear equations system. Computer simulations show that the performance is comparable and in some aspects better than the one obtained with more complicated controllers

Robotica, 2010

A novel approach for trajectory tracking of a mobile-robots formation by using linear algebra the... more A novel approach for trajectory tracking of a mobile-robots formation by using linear algebra theory and numerical methods is presented in this paper. The formation controller design is based on the formation states concept and the dynamic model of a unicycle-like nonholonomic mobile robot. The proposed control law designed is decentralized and scalable. Simulations and experimental results confirm the feasibility and the effectiveness of the proposed controller and the advantages of using the dynamic model of the mobile robot. By using this new strategy, the formation of mobile robots is able to change its configuration (shape and size) and follow different trajectories in a precise way, minimizing the tracking and formation errors.

In this work, a strategy to calculate the control actions for a mobile robot following a pre esta... more In this work, a strategy to calculate the control actions for a mobile robot following a pre established trajectory is proposed. For this purpose, the Taylor series development of controlled variables is used and the control action is calculated to make the system follow the reference trajectory. As main result, an easy form to implement the strategy is obtained. Simulation

Control Engineering Practice, 2010

This work presents a novel linear interpolation based methodology to design control algorithms fo... more This work presents a novel linear interpolation based methodology to design control algorithms for the trajectory tracking of mobile robotic systems. Particularly, a typical nonlinear multivariable systema mobile robot-is analysed. The methodology is simple and can be applied to the design of a large class of control systems. Simulation and experimental results are presented and discussed, demonstrating the good performance of the proposed methodology.

A nonlinear predictive controller (NMPC) is developed to control a unicycle-like mobile robot for... more A nonlinear predictive controller (NMPC) is developed to control a unicycle-like mobile robot for trajectory tracking. Dynamic model of PIONNER 3-DX mobile robot is used, where external forces and wheels sliding have been considered. Restrictions on control actions and system states are also considered. Simulations results at both tracking and regulation (positioning) are shown, these results show the good performance of developed controller. Finally, this paper shows that the controller can be implemented in real-time by using an analysis of compute times of NMPC algorithm.

Physica B-condensed Matter, 2010

In this paper, the phase transformations occurring during the crystallization process of FINEMETs... more In this paper, the phase transformations occurring during the crystallization process of FINEMETs in which Nb has been gradually replaced by Mo have been studied by a variety of techniques including DSC, DTA, TGA, XRD and TEM. The thermal stability of the alloy was deteriorated as a consequence of Mo’s smaller atomic size. The gradual replacement of Nb by Mo reduced the onset temperature of Fe-Si and of the borides. The Curie temperature of the amorphous phase slightly decreased from 594 K for x=0 to 587 K for x=3. The borides compounds Fe2B and Fe23B6 as well as the (Nb,Mo)5Si3 phase were found to precipitate in the second and third crystallization.

Journal of Magnetism and Magnetic Materials, 2001

The random-"eld Ising model (RFIM) system Fe Zn F is studied by magnetization and AC susceptibili... more The random-"eld Ising model (RFIM) system Fe Zn F is studied by magnetization and AC susceptibility measurements, under "nite DC applied "elds (H). For weak random "elds (corresponding to H(20 KOe), the phase transition (PT) at ¹ (H) is accompanied by the critical slowing down inherent to the random "eld problem. For higher H, the PT is destroyed and a glassy dynamics dominates the magnetic behavior.

Physica B-condensed Matter, 2010

In this paper, the phase transformations occurring during the crystallization process of FINEMETs... more In this paper, the phase transformations occurring during the crystallization process of FINEMETs in which Nb has been gradually replaced by Mo have been studied by a variety of techniques including DSC, DTA, TGA, XRD and TEM.The thermal stability of the alloy was deteriorated as a consequence of Mo’s smaller atomic size. The gradual replacement of Nb by Mo reduced

Journal of Magnetism and Magnetic Materials, 2001

The random-field Ising model (RFIM) system Fe0.42Zn0.58F2 is studied by magnetization and AC susc... more The random-field Ising model (RFIM) system Fe0.42Zn0.58F2 is studied by magnetization and AC susceptibility measurements, under finite DC applied fields (/H). For weak random fields (corresponding to H<20KOe), the phase transition (PT) at Tc(/H) is accompanied by the critical slowing down inherent to the random field problem. For higher H, the PT is destroyed and a glassy dynamics dominates the magnetic behavior.

Gastrointestinal Endoscopy, 2009

and outcome were evaluated. An acute-overt bleeding was defined as hematemesis, rectal blood loss... more and outcome were evaluated. An acute-overt bleeding was defined as hematemesis, rectal blood loss and/or melena. Results: In the period 2005-2008 in 22 patients had BAE for acute-overt GI bleeding: 12 males, mean age 65 (35-87) years. All patients had negative upper-en ileocolonoscopy. Clinical presentation was rectal blood loss in 11 (50%), melena and blood cloths in 7 (32%) and hematemesis and melena in 4 (18%) patients. In 18 (82%) transfusion was necessary; 11 (50%) patients presented with hemodynamic instability. Mean hemoglobin at presentation was 7.0 (5.3-10.1) g/dL (mean MCV 88). In 11 (50%) patients use of NSAID's, steroids and/or oral anticoagulation was reported. The enteroscopes used were diagnostic DBE in 12, therapeutic DBE in 7, and SBE in 3 patients. Mean insertion depth was proximal 247 (130-400) cm and distal 96 (30-150) cm. During BAE a likely cause of bleeding was found in 10 (45%) patients: in 4 (40%) tumoreus laesions (2 GIST and 2 adenocardinoma), in 4 (40%) vascular abnormalities (3 angiodysplasia and 1 jejunal varices), and 2 Dieulafoy-like-lesions were found. The pathologic findings were all located in the jejunum: 5 proximal and 5 in the mid-distal jejunum. Endoscopic therapy was applied in 6 (60%) patients, 4 patients had surgery. Two patients died due to other causes, all other patients were symptom free at mean follow-up of 23 (3-38) months. In 5 (23%) patients, wireless capsule endoscopy (WCE) was performed before BAE: in 1 case WCE was true positive, WCE was false negative in 3 cases (1 angiodysplasia and 2 tumors) and in 1 case false positive. Conclusion: BAE found the source of GI bleeding in nearly half of patients presenting with an acuteovert GI bleeding, with an initial negative upper-and lower endoscopy. Cause of bleeding could be treated endoscopically in majority of patients. The sensitivity for detection of acute small bowel bleeding seems higher for BAE as compared to WCE.

Plant Cell Tissue and Organ Culture, 2001

The effects of NaCl-adaptation and NaCl-stress on in vivo H+ extrusion and microsomal vanadate- a... more The effects of NaCl-adaptation and NaCl-stress on in vivo H+ extrusion and microsomal vanadate- and bafilomycin-sensitive ATPase and PPase activities were studied in tomato cell suspensions. Acidification of the external medium by 50 mM NaCl-adapted and non-adapted (control) tomato cells was similar. Extracellular acidification by both types of cells during the first hour of incubation with 2 μM fusicoccin (FC) in the presence of 100 mM NaCl was lightly increased while in the presence of 100 mM KCl it was increased by 3 (control)- and 6.5 (adapted)-fold. Extracellular alkalinization after 2 h of cell incubation in 100 mM NaCl indicated the possibility that a Na+/H+ exchange activity could be operating in both types of cells. Moreover, acidification induced by adding 100 mM NaCl + FC to non-adapted cells was relatively less affected by vanadate than that induced by 5 mM KCl + FC, which suggested that salt stress could induce some component other than H+ extrusion by H+-ATPase. In addition, no differences were observed in microsomal vanadate-sensitive ATPase activity among control, NaCl-adapted and NaCl-stressed cells, while K+-stimulated H+-PPase and bafilomycin-sensitive H+-ATPase activities were higher in microsomes from NaCl-adapted than in those from control cells. Likewise, the stimulation of in vivo H+ extrusion in NaCl adapted cells under NaCl or KCl stress in the presence of FC occurred with an inhibition of H+-PPase and bafilomycin-sensitive H+-ATPase activities and without changes in the vanadate-sensitive H+-ATPase activity. These results suggest that the stimulation of tonoplast proton pumps in NaCl-adapted cells, without changes in plasmalemma H+-ATPase, could serve to energize Na+ efflux across the plasmalemma and Na+ fluxes into vacuoles catalyzed by the Na+/H+ antiports.

In this paper a model based controller for mobile robots by using numerical methods is developmen... more In this paper a model based controller for mobile robots by using numerical methods is development. The system is approximated using numerical methods, next, the linear equations theory is used to compute the control signals and to obtain the minimal error conditions. The dynamic model of the PIONNER 3DX mobile robot with external forces and wheels slides is considered. Experimental

Robotica, 2009

A new approach for navigation of mobile robots in dynamic environments by using Linear Algebra Th... more A new approach for navigation of mobile robots in dynamic environments by using Linear Algebra Theory, Numerical Methods, and a modification of the Force Field Method is presented in this paper. The controller design is based on the dynamic model of a unicycle-like nonholonomic mobile robot. Previous studies very often ignore the dynamics of mobile robots and suffer from algorithmic singularities. Simulation and experimentation results confirm the feasibility and the effectiveness of the proposed controller and the advantages of the dynamic model use. By using this new strategy, the robot is able to adapt its behavior at the available knowing level and it can navigate in a safe way, minimizing the tracking error.

A nonlinear benchmark problem, very interesting due to interaction between translational and rota... more A nonlinear benchmark problem, very interesting due to interaction between translational and rotational movements is the RTAC system (also called TORA). Diverse control techniques in several previous papers have been dedicated to it. The present work proposes, by means of a straightforward procedure, a controller design based on an approach of RTAC system, using numerical methods, so that the system tends to origin after being displaced of this position. The control signal is calculated through the resolution of a linear equations system. Computer simulations show that the performance is comparable and in some aspects better than the one obtained with more complicated controllers

Robotica, 2010

A novel approach for trajectory tracking of a mobile-robots formation by using linear algebra the... more A novel approach for trajectory tracking of a mobile-robots formation by using linear algebra theory and numerical methods is presented in this paper. The formation controller design is based on the formation states concept and the dynamic model of a unicycle-like nonholonomic mobile robot. The proposed control law designed is decentralized and scalable. Simulations and experimental results confirm the feasibility and the effectiveness of the proposed controller and the advantages of using the dynamic model of the mobile robot. By using this new strategy, the formation of mobile robots is able to change its configuration (shape and size) and follow different trajectories in a precise way, minimizing the tracking and formation errors.

In this work, a strategy to calculate the control actions for a mobile robot following a pre esta... more In this work, a strategy to calculate the control actions for a mobile robot following a pre established trajectory is proposed. For this purpose, the Taylor series development of controlled variables is used and the control action is calculated to make the system follow the reference trajectory. As main result, an easy form to implement the strategy is obtained. Simulation

Control Engineering Practice, 2010

This work presents a novel linear interpolation based methodology to design control algorithms fo... more This work presents a novel linear interpolation based methodology to design control algorithms for the trajectory tracking of mobile robotic systems. Particularly, a typical nonlinear multivariable systema mobile robot-is analysed. The methodology is simple and can be applied to the design of a large class of control systems. Simulation and experimental results are presented and discussed, demonstrating the good performance of the proposed methodology.

A nonlinear predictive controller (NMPC) is developed to control a unicycle-like mobile robot for... more A nonlinear predictive controller (NMPC) is developed to control a unicycle-like mobile robot for trajectory tracking. Dynamic model of PIONNER 3-DX mobile robot is used, where external forces and wheels sliding have been considered. Restrictions on control actions and system states are also considered. Simulations results at both tracking and regulation (positioning) are shown, these results show the good performance of developed controller. Finally, this paper shows that the controller can be implemented in real-time by using an analysis of compute times of NMPC algorithm.