Absorción de radiación procedente de terminales móviles GSM

¿Son peligrosos los Sistemas de Comunicaciones Móviles? Ésta es una pregunta que se han hecho muchos medios de comunicación dado el revuelo social de los usuarios respecto a esta duda. De hecho, pese a que es bien conocida la influencia que determinadas ondas de radio tienen sobre el cuerpo humano (Rayos X, Radiación Gamma ... ), la posibilidad de aparición de tumores debidos al tipo de radiación emitida por los terminales y las estaciones de Telefonía Móvil se ha destacado como el más importante motivo de preocupación. En nuestro trabajo se ha intentado resumir en lo posible el estado actual de las múltiples investigaciones y estudios publicados sobre el tema, así como desarrollar un modelo numérico específico y de precisión que permitiese evaluar el cumplimiento de la normativa vigente en materia de terminales móviles.Peer Reviewe

Absorción de radiación procedente de terminales móviles GSM

¿Son peligrosos los Sistemas de Comunicaciones Móviles? Ésta es una pregunta que se han hecho muchos medios de comunicación dado el revuelo social de los usuarios respecto a esta duda. De hecho, pese a que es bien conocida la influencia que determinadas ondas de radio tienen sobre el cuerpo humano (Rayos X, Radiación Gamma ... ), la posibilidad de aparición de tumores debidos al tipo de radiación emitida por los terminales y las estaciones de Telefonía Móvil se ha destacado como el más importante motivo de preocupación. En nuestro trabajo se ha intentado resumir en lo posible el estado actual de las múltiples investigaciones y estudios publicados sobre el tema, así como desarrollar un modelo numérico específico y de precisión que permitiese evaluar el cumplimiento de la normativa vigente en materia de terminales móviles.Peer Reviewe

Modelling the propagation of electromagnetic waves across complex metamaterials in closed structures

[EN] Metamaterials are currently one of the most popular fields in microwave technology because their particular electromagnetic properties lead to a plenty of very relevant applications, both military and civilian. Additionally, the analysis and design of microwave components based on this kind of materials is one of the more challenging problems found by the applied electromagnetism community due to the complexity introduced in the mathematical formulation by their constitutive relationships. The most general case of metamaterial is the bi-anisotropic one, where both the electric field and the electric induction simultaneously depend on the magnetic field and the magnetic induction. In this paper, we present a new and powerful Finite Element Method scheme valid for the analysis of the most general waveguides, filled with lossy bi-anisotropic linear materials. Edge elements have been used in order to prevent the appearance of spurious solutions and the final eigensystems are very sparse, thus allowing a great memory and computing time saving.Balbastre Tejedor, JV.; Nuño Fernández, L. (2019). Modelling the propagation of electromagnetic waves across complex metamaterials in closed structures. Journal of Computational and Applied Mathematics. (352):40-49. https://doi.org/10.1016/j.cam.2018.11.004S404935

Presentación Dosier. Emigración, exilio y emociones

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Estudio del comportamiento de cámaras semianecoicas utilizando una técnica híbrida bidimensional

Semianechoic chambers are the most widely used emplacements for Electromagnetic Compatibility (EMC) Tests. Semianechoic chambers design is not an easy task, since they must behave like an ideal Open Area Test Site (OATS) within a quite narrow margin (±4 dB) in a wide frequency span (from 30 to 1000 MHz). There are several possible configurations for a Semianechoic Chamber, based on different technological solutions (dielectric foam absorbers of different shapes, ferrite absorbing tiles or a combination of both elements are found in most of the actual chambers). In this work a new and efficient technique for the analysis of 2-D simplified model of a chamber with arbitrary absorber is introduced and validated. Some advanced results are presented, and a 2-D estimator for studying the overall behaviour of the chamber is proposed

Adaptative mesh refinement in electromagnetic problems

This paper describes an adaptive mesh refinement algorithm for improving the accuracy in the solution of electromagnetic problems in transmission lines. A residual error indicator is used for detecting the refinement zones, and two h-refinement techniques for triangular meshes (the longest edge bisection and the regular split) are applied for increasing the degrees of freedom in the mesh. This procedure has been applied in several structures and the results show that the adaptive meshing allows obtaining accurate solution with a small amount of unknowns

Aproximación 2-D a la eficacia del apantallamiento de carcasas metálicas

In this work an approximated method to obtain Shielding Effectiveness of metallic enclosures with an aperture is evaluated. The method consists of the analysis of the 2-D transversal cut of the structure through a numerical method. A Finite Element Method based CAD tool, has been used in order to obtain the results for the susceptibility analysis of the structure. To obtain the level of energy coupling between the inner and outer part of the cavity an empirical formula is used. Shielding Effectiveness of metallic enclosures with different sizes and apertures has been analysed and good agreement has been found between the 2-D approximated method and measurements. This tool can be used to study shielding properties of materials and the effects of enclosure contents, PCBs, I/O devices, etc.Este trabajo ha sido financiado por la Fundación Séneca, Agencia Regional de Ciencia y Tecnología, a través del proyecto 00700/PPC/04

SIVA UAV: A Case Study for the EMC Analysis of Composite Air Vehicles

[EN] The increased use of carbon-fiber composites in unmanned aerial vehicles is a challenge for their EMC assessment by numerical solvers. For accurate and reliable simulations, numerical procedures should be tested not only for individual components, but also within the framework of complete systems. With this aim, this paper presents a benchmark test case based on experimental measurements coming from direct-current injection tests in the SIVA unmanned air vehicle, reproduced by a numerical finite-difference-time-domain solver that employs a new subgridding scheme to treat lossy composite thin panels. Validation was undertaken by applying the feature selective validation method, which quantifies the agreement between experimental and numerical data.This work was supported by the Projects TEC2013-48414C3-{ 1,2,3}-R, TEC2016-79214-C3-{1,2,3}-R, and TEC2015-68766-REDC (Spanish MINECO, EU FEDER), P12-TIC-1442 (J. de Andalucia, Spain), Alhambra-UGRFDTD (AIRBUS DS), and by the CSIRC alhambra.ugr.es supercomputing center.Cabello, MR.; Fernández, S.; Pous, M.; Pascual-Gil, E.; Angulo, LD.; López, P.; Riu, PJ.... (2017). SIVA UAV: A Case Study for the EMC Analysis of Composite Air Vehicles. IEEE Transactions on Electromagnetic Compatibility. 59(4):1103-1113. https://doi.org/10.1109/TEMC.2017.2648507S1103111359

Noninvasive monitoring of serial changes in pulmonary vascular resistance and acute vasodilator testing using cardiac magnetic resonance

Objectives The study sought to evaluate the ability of cardiac magnetic resonance (CMR) to monitor acute and long-term changes in pulmonary vascular resistance (PVR) noninvasively. Background PVR monitoring during the follow-up of patients with pulmonary hypertension (PH) and the response to vasodilator testing require invasive right heart catheterization. Methods An experimental study in pigs was designed to evaluate the ability of CMR to monitor: 1) an acute increase in PVR generated by acute pulmonary embolization (n = 10); 2) serial changes in PVR in chronic PH (n = 22); and 3) changes in PVR during vasodilator testing in chronic PH (n = 10). CMR studies were performed with simultaneous hemodynamic assessment using a CMR-compatible Swan-Ganz catheter. Average flow velocity in the main pulmonary artery (PA) was quantified with phase contrast imaging. Pearson correlation and mixed model analysis were used to correlate changes in PVR with changes in CMR-quantified PA velocity. Additionally, PVR was estimated from CMR data (PA velocity and right ventricular ejection fraction) using a formula previously validated. Results Changes in PA velocity strongly and inversely correlated with acute increases in PVR induced by pulmonary embolization (r = –0.92), serial PVR fluctuations in chronic PH (r = –0.89), and acute reductions during vasodilator testing (r = –0.89, p ≤ 0.01 for all). CMR-estimated PVR showed adequate agreement with invasive PVR (mean bias –1.1 Wood units,; 95% confidence interval: –5.9 to 3.7) and changes in both indices correlated strongly (r = 0.86, p < 0.01). Conclusions CMR allows for noninvasive monitoring of acute and chronic changes in PVR in PH. This capability may be valuable in the evaluation and follow-up of patients with PH

Prediction of poor outcome in clostridioides difficile infection: A multicentre external validation of the toxin B amplification cycle

Producción CientíficaClassification of patients according to their risk of poor outcomes in Clostridioides difficile infection (CDI) would enable implementation of costly new treatment options in a subset of patients at higher risk of poor outcome. In a previous study, we found that low toxin B amplification cycle thresholds (Ct) were independently associated with poor outcome CDI. Our objective was to perform a multicentre external validation of a PCR-toxin B Ct as a marker of poor outcome CDI. We carried out a multicentre study (14 hospitals) in which the characteristics and outcome of patients with CDI were evaluated. A subanalysis of the results of the amplification curve of real-time PCR gene toxin B (XpertTM C. difficile) was performed. A total of 223 patients were included. The median age was 73.0 years, 50.2% were female, and the median Charlson index was 3.0. The comparison of poor outcome and non–poor outcome CDI episodes revealed, respectively, the following results: median age (years), 77.0 vs 72.0 (p = 0.009); patients from nursing homes, 24.4% vs 10.8% (p = 0.039); median leukocytes (cells/μl), 10,740.0 vs 8795.0 (p = 0.026); and median PCR-toxin B Ct, 23.3 vs 25.4 (p = 0.004). Multivariate analysis showed that a PCR-toxin B Ct cut-off <23.5 was significantly and independently associated with poor outcome CDI (p = 0.002; OR, 3.371; 95%CI, 1.565–7.264). This variable correctly classified 68.5% of patients. The use of this microbiological marker could facilitate early selection of patients who are at higher risk of poor outcome and are more likely to benefit from newer and more costly therapeutic options