Examinando por Autor "Aroca, C."

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Acceso Abierto
Data Base of Extraterrestrial Magnetic Minerals, Test and Magnetic Simulation
(Institute of Electrical and Electronics Engineers, 2013-07-15) Fernández, A. B.; McHenry, M. E.; Díaz Michelena, M.; Aroca, C.; Maicas, M.
The description of the planetary magnetic anomalies is a difficult task that combines either aeromagnetic or in-situ magnetic field measurements, and further laboratory characterization of the local rocks. In the case of extraterrestrial planets this is a very difficult and costly task. With the objective to develop predictive algorithms prior to in-situ measurements, two complimentary lines of work have been undertaken: 1) characterization of magnetic minerals which occur in great abundance in extraterrestrial crusts; and 2) development of finite element method models (FEM) using the properties of these minerals to model possible scenarios and the variation of their magnetic behavior with temperature and temperature gradient swings on the superficial layers of the planets. The ultimate objective is the future comparison between the measurements developed by instruments on board Martian landers and rovers and the developed models.
Restringido
Lock-in amplifiers for AMR sensors
(Elsevier, 2015-02-01) Díaz Michelena, M.; Cobos, P.; Aroca, C.
Anisotropic magnetoresistive (AMR) magnetic sensors are often chosen as the magnetic transducer for magnetic field sensing in applications with low to moderate magnetic field resolution because of the relative low mass of the sensor and their ease of use. They measure magnetic fields in the order of the Earth magnetic field (with typical sensitivities of 1‰/G or 10−2‰/μT), have typical minimum detectable fields in order of nT and even 0.1 nT but they are seriously limited by the thermal drifts due to the variation of the resistivity with temperature (∼2.5‰/°C) and the variation of the magnetoresistive effect with temperature (which affects both the sensitivity of the sensors: ∼2.7‰/°C, and the offset: ±0.5‰/°C). Therefore, for lower magnetic fields, fluxgate vector sensors are generally preferred. In the present work these limitations of AMR sensors are outlined and studied. Three methods based on lock-in amplifiers are proposed as low noise techniques. Their performance has been simulated, experimentally tested and comparatively discussed. The developed model has been also used to derive a technique for temperature compensation of AMR response. The final goal to implement these techniques in a space qualified applied specific integrated circuit (ASIC) for Mars in situ exploration with compact miniaturized magnetometers.
Acceso Abierto
Single Point Gradiometer for Planetary Applications
(Institute of Electrical and Electronics Engineers, 2015-03-09) Mesa, J. L.; Díaz Michelena, M.; Ciudad, D.; Schoenthal, W.; McHenry, M. E.; Maicas, M.; Aroca, C.; Ministerio de Ciencia e Innovación (MICINN)
We have designed and fabricated a microelectromechanical device, based on the alternating field gradient concept, to measure surface magnetic field gradient on planets. Its sensitivity is 4 10 -4 T/m, which is appropriate for magnetite outcrops and areas with rocks formed at different stages recording geomagnetic field reversals. We present the results obtained with three different prototypes.
Acceso Abierto
Small Fluxgate Magnetometers: Development and Future Trends in Spain
(Multidisciplinary Digital Publishing Institute (MDPI), 2010-03-09) Ciudad, D.; Díaz Michelena, M.; Pérez, L.; Aroca, C.; Ministerio de Educación y Ciencias (MEC)
In this paper, we give an overview of the research on fluxgate magnetometers carried out in Spain. In particular we focus in the development of the planar-type instruments. We summarize the fabrication processes and signal processing developments as well as their use in complex systems and space.