A5073807806- Physics of Superconductivity and Magnetism
- Magnetic Bearings and Levitation Dynamics
- Advanced Condensed Matter Physics
- Electric Motor Design and Analysis
- Superconducting Materials and Applications
- Magnetic properties of thin films
- Magnetic and transport properties of perovskites and related materials
- Magnetic and Electromagnetic Effects
- High-pressure geophysics and materials
- Theoretical and Computational Physics
- Frequency Control in Power Systems
- Magnetic confinement fusion research
- Electromagnetic Launch and Propulsion Technology
- Magnetic Properties and Applications
- Tribology and Lubrication Engineering
- Underwater Vehicles and Communication Systems
- Engineering and Technology Innovations
- Electric Power Systems and Control
- Ultrasonics and Acoustic Wave Propagation
- Spacecraft Design and Technology
- Microgrid Control and Optimization
- Chemical and Physical Properties of Materials
- Organic and Molecular Conductors Research
- Magnetic Properties of Alloys
- Vibration Control and Rheological Fluids
Universidade Federal do Rio de Janeiro
2012-2024
Eletrobras (Brazil)
2022
Altera (United States)
2022
Instituto de Pesquisas da Marinha
2022
Southwest Jiaotong University
2019-2020
Centro de Tecnologia Mineral
2012
Universidade Federal Fluminense
2010
Massachusetts Institute of Technology
2003-2005
Fundación Ciencias Exactas y Naturales
1998-2000
Institut de Ciència de Materials de Barcelona
1996-1998
The Brazilian project MagLev-Cobra proposes a superconducting levitation vehicle for urban transportation in highly populated cities. technology is based on the diamagnetic behavior and flux pinning property of Y-Ba-Cu-O blocks proximity magnetic field Nd-Fe-B magnets. traction given by short primary linear induction motor. In previous editions EUCAS conference, laboratory tests were presented to validate method design. this paper, recent operational results traveling along an outdoor 200-m...
We report transport measurements in the mixed state of single crystals ${\mathrm{Bi}}_{2}$${\mathrm{Sr}}_{2}$${\mathrm{CaCu}}_{2}$${\mathrm{O}}_{\mathit{x}}$ using a modified version dc flux transformer geometry pioneered by Giaever low-${\mathit{T}}_{\mathit{c}}$ materials. find that over wide range phase diagram vortices are effectively two dimensional character. Our results suggest vortex cutting is an efficient process and it unlikely strongly entangled this region diagram.
Different types of bearingless induction motors have been reported in the literature. One them is rotor cage motor with split windings. Continuing research about this theme, paper proposes a new control system. Since radial forces are consequences magnetic energy changes, modeling and speed system implemented reference frame airgap flux. In addition, due to lag between stator current vector flux, an automatic correction angular orientation Cartesian coordinates position sensors proposed....
Based on the magnetic characteristics of HTS superconductors, group Laboratory Applied Superconductivity from COPPE/UFRJ in Brazil has proposed and developed a full-scale superconducting MagLev vehicle. The levitation system this vehicle consists linear bearing, which is composed permanent guideway (PMG) YBCO bulks superconductors. guidance forces that appear due to interaction between superconductor PMG keep passively levitating stable equilibrium point. However, under operational...
A sharp temperature- and field-dependent transition from a logarithmic to nonlogarithmic flux-creep behavior has been found in Bi-Sr-Ca-Cu-O superconductors. The is not followed by any noticeable change the magnetization. However, vibrating-reed measurements show that it coincides with strong hardening of magnetic structure. occurs at fields temperatures well below reversibility line. possible relation recently proposed flux lattice melting discussed.
Transport measurements show that the critical current in c direction, ${\mathit{J}}_{\mathit{c}}^{\mathit{c}}$ of ${\mathrm{Bi}}_{2}$${\mathrm{Sr}}_{2}$${\mathrm{CaCu}}_{2}$${\mathrm{O}}_{8}$ single crystals increases with temperature for low zero field cooled (ZFC) measurements. As a consequence, direction electrical resistance ZFC state, at given dc current, is finite, goes to increasing temperature, and becomes finite again higher temperatures. The results are consistent loss axis long...
This paper describes the design and experimental test of a passive magnetic bearing system composed by superconductor (SMB) permanent magnet (PMB). setup is part flywheel energy storage system. The advantage using that it offers low friction without need controller, increasing reliability decreasing consumption. first set tests were quasi-static radial axial force measurements PMB operating alone together with SMB. As intrinsically unstable in one degree freedom, operation SMB necessary to...
Alternating current (AC) loss occurs when the high-temperature superconducting (HTS) maglev running on a permanent magnetic guideway (PMG) with varying field. The stability and safety of HTS vehicle will be influenced by AC losses, which are closely related to field fluctuation PMG levitation characteristics bulks. In order study losses bulk under different frequencies amplitudes, numerical simulation experimental analysis employed. model was built COMSOL Multiphysics partial differential...
This paper presents simulations and experimental results for two types of Passive Permanent Magnet Bearings. The bearing system under investigation consists permanent magnet rings opposing to each other in different configurations. influence parameters, such as thickness radiu s magnets, the force is presented through FEM calculations. Two setups passive magnetic bearings have been built. Static measurements radial axial forces are reported compared with simulations. Also, dynamic tests show...
Mais de 80% da população brasileira vive em cidades. Como resposta para osgraves problemas mobilidade urbana, a UFRJ desenvolveu o MagLev-Cobra, umveículo que utiliza técnica levitação magnética (MagLev) baseada emsupercondutores elevada temperatura crítica e imãs terras-raras, viabilizadaapenas no final do século XX início XXI. O artigo apresenta oselementos essenciais entendimento sistema, comparando-o com outrasalternativas transporte urbano outras técnicas magnética.Inúmeras...
Pseudo-spin-valve NiFe∕Cu∕NiFe, Co∕Cu∕Co, NiFe∕Cu∕Co films and magnetic tunnel junction have been patterned into arrays of rectangular elements with widths 40–140nm aspect ratios 1.5–18. The switching field the hard soft layers interaction between measured as a function ratio. In pseudo-spin-valve structures behavior is dominated by magnetostatic interactions layers, leading to antiparallel alignment at remanence for small ratios. Patterned show weaker effects, exchange bias from...
Abstract The microstructure and superconducting properties of directionally solidified YBa2Cu3O7/Y2BaCuO5 composites made to creep at 930°C, have been investigated using transmission electron microscopy, dc ac magnetic measurements. It is found that the plastic deformation high critical current samples induces a shift irreversibility line toward lower fields temperatures as result decrease activation energy for flux motion. Such behaviour directly correlated with observed microstructure,...
Superconducting Electric Machines (SEM) have some advantages compared to machines with conventional conductors, such as higher power density, weight reduction, increased efficiency, and overload capacity. Those properties make the SEM ideal for several applications where a lighter smaller machine is necessary. The can be constructed using high temperature superconductor (HTS) bulks trapped field or superconducting tapes arranged coils. Recent works been proposed replace HTS bulk by stacks of...
A review of the Superconducting Magnetic Levitation (SML) technology applied to urban transportation will be presented. The historical time line highlighted, pointing out pioneering efforts at Southwest Jiatong University (SWJTU), China, followed by Supra Trans project in IFW-Dresden, Germany, and MagLev-Cobra UFRJ, Brazil.
 Background: Details project, first, until today single one, applying SML that counts with a real scale prototype, operating regularly open air, disclosed....
Bulk cylinders of YBa/sub 2/Cu/sub 3/O/sub 7/-Y/sub 2/BaCuO/sub 5/ composites, up to 35.0 mm in diameter, have been melt-processed using MgO single crystals, Nd123 and Sm123 melt textured ceramics, as seeds. The influence processing parameters has examined order optimize the growth conditions. Polarized light microscopy, SEM EDX, used characterize orientation, size morphology grains, well spatial distribution Y211 particles. An increase levitation forces is observed when top seeding carried...
We investigated with ac susceptibility the mixed state of twinned, deoxygenated single crystals and highly $c$-axis-oriented melt-textured samples ${\mathrm{YBa}}_{2}{\mathrm{Cu}}_{3}{\mathrm{O}}_{6+x}$ oxygen stoichometry corresponding to that orthorhombic II phase. In crystal we found, below ${H}^{*}\ensuremath{\approx}700$ Oe over almost four orders magnitude in frequency, a frequency-independent ``irreversibility line'' (IL). Complementry dc magnetization measurements seem disregard an...