Enlaces

Web of Science ResearcherID: J-6541-2018
ORCID: 0000-0002-1961-1958
SCOPUS Author ID: 56600741500
Researchgate: https://www.researchgate.net/profile/Manuel-Fernandez-Ros
brújula UAL: http://brujula.ual.es/authors/288.html

Artículos en revistas indexadas

• F. Portillo, A. Alcayde, R. M. Garcia, N. Novas, J. A. Gazquez, M. Fernandez-Ros «Grid Frequency Measurement through a PLHR Analysis Obtained from an ELF Magnetometer». Sensors, 2022. (10.3390/s22082954) (Abstract)

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  The stability of the power grid’s frequency is crucial for industrial, commercial, and domestic applications. The standard frequency in Europe’s grid is 50 Hz and it must be as stable as possible; therefore, reliable measurement is essential to ensure that the frequency is within the limits defined in the standard EN 50160:2010. In this article, a method has been introduced for the measurement of the grid frequency through a power line harmonics radiation analysis. An extremely low-frequency magnetometer was developed with the specific purpose of monitoring, in real time, the electromagnetic field produced by electrical installations in the range from 0 to 2.2 kHz. Zero-crossing and Fast Fourier transform algorithms were applied to the output signal to calculate the grid frequency as a non-invasive method. As a final step, data for a complete month (May 2021) were compared with a commercial power quality analyzer connected to the main line to validate the results. The zero-crossing algorithm gave the best result on 3 May 2021, with a coefficient of determination (R2) of 0.9801. Therefore, the indirect measurement of the grid frequency obtained through this analysis satisfactorily fits the grid frequency.
• F. Portillo, R. M. Garcia, A. Alcayde, J. A. Gazquez, M. Fernandez-Ros, N. Novas «Prospective environmental and economic assessment of a sensor network». Sustainability (Switzerland), 2021. (10.3390/su131810306) (Abstract)

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  Sustainability is becoming of vital importance in project management, and a life cycle assessment (LCA) can ensure a body of knowledge to bear in mind the environmental burdens the project involves. In this study, two different ways of supplying energy to a sensor network are an-alyzed. Firstly, we analyze the environmental impact of the devices connected to the public grid. Secondly, we analyze the completely full off-grid system, with the sensor connected to a photovol-taic (PV) panel. Our findings show that the off-grid option has a greater number of benefits than the grid-connected option in terms of environmental impacts, although it is less economically advanta-geous. In a detailed analysis of the off-grid scenario, it can be observed that the battery is the com-ponent with the highest impact, so actions to try to reduce consumption, and, therefore, the battery size and its negative impact are taken. After reducing the battery size, the break-even point was reached, providing a net economic benefit of EUR 0.23 sensor/year. However, this analysis refers to a single sensor, and although the environmental and economic benefits seem low, in an economy of scale, this could result in large savings if these types of sensors are massively installed.
• J. A. Gazquez, M. Fernandez-Ros, B. Torrecillas, J. Carmona, N. Novas «New approximate analytical solution of the diode-resistance equation». International Journal of Electronics and Communications, 2021. (10.1016/j.aeue.2021.153665) (Abstract)

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  The problem of finding an analytical solution for the circuit formed by a diode with series resistance (D-R circuit) has been investigated for a long time and several authors have proposed approximate solutions. Most solutions use the Lambert function and numerical methods. However, an analytical solution independent of experimental parameters is still missing to replace the D-R circuit with an analytical expression, in which only the diode and circuit parameters appear. In this paper, using a Taylor series expansion of the equation VD = f (VS, R, ID), we propose a new analytical solution that fits the exact solution with more accuracy than all known approximations. The average of the absolute error vector is the best, with an order of magnitude of difference compared to the other 3 approximations studied. This new function can be expressed by voltage analysis, which allows analytical solutions. Our solution may have many applications, such as a simple and accurate way, in circuit simulation programs or numerical calculation programs. In particular, it can be used as well in circuits with D-R branches, exponential amplifiers, logarithmic amplifiers and waveform shapers. On another level, a comparison with other state of the art approximations is presented.
• R. M. Garcia, N. Novas, A. Alcayde, D. El Khaled, M. Fernandez-Ros, J. A. Gazquez «Progress in the knowledge, application and influence of extremely low frequency signals». Applied Sciences (Switzerland), 2020. (10.3390/app10103494) (Abstract)

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  This paper describes the characteristics of contributions made by researchers worldwide in the field of ELF (extremely low frequency) waves from 1957 to 2019. The data were collected through the Scopus database and processed with analytical and bibliometric techniques. The selection of the keywords is an essential step, because ELF has a very different meaning in some areas of medicine, where it is associated with a gene. A total of 12,436 documents were worked on in 12 thematic communities according to their collaborative relationships between authors and documents. Studies included authors publishing in the different thematic areas and the country where the USA stands first with more researchers in this theme than China and Japan. Documents were analyzed from the temporal perspective, their overall contribution, means of publication, and the language of the publication. Research requires extra effort and multidisciplinary collaboration to improve the knowledge, the application, and influence of these fields.
• M. Fernandez-Ros, J. A. Gazquez, R. M. Garcia, N. Novas «Optimization of the periodogram average for the estimation of the power spectral density (PSD) of weak signals in the ELF band». Measurement: Journal of the International Measurement Confederation, 2015. (10.1016/j.measurement.2015.10.006) (Abstract)

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  The frequencies between the ELF, ULF and VLF bands are widely used as indicators of the electrical activity in the atmosphere, as precursors of seismic activity and are of interest in the study of geophysical phenomena. These signal methods of analysis are varied, and among them, we find a method of averaged periodograms, which is based on the Fast Fourier Transform (FFT). In this type of analysis, the optimal number of segments to be averaged must be determined; however, there seems to be no satisfactory method for choosing them. In this paper, we provide a method that will allow us to select the optimal number of segments to be averaged.
• J. A. Gazquez, M. Fernandez-Ros, N. Novas, R. M. Garcia «Techniques for Schumann Resonance Measurements: A Comparison of Four Amplifiers with a Noise Floor Estimate». IEEE Transactions on Instrumentation and Measurement, 2015. (10.1109/TIM.2015.2420376) (Abstract)

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  Schumann resonances are very weak natural electromagnetic signals produced in the earth-ionosphere cavity located in the extremely low frequency (ELF) band (7-60 Hz), and the sensors that measure them produce amplitudes of few microvolts. Strong signals from power lines (50-60 Hz) occur in the same frequency range. Amplification techniques play a key role in acquiring resonance modes with the best signal-To-noise (S/N) ratio. This paper presents a study of the various structures of amplification systems that optimize the S/N ratio for the signal of interest. The aim of this paper is to measure all possible resonance modes with low time acquisition. To this end, we compare four instrumentation amplifiers and design a new indirect method for obtaining the noise floor of the system with sensors manufactured on magnetic cores that are several meters long. We present the measurements of the Schumann resonance achieved using these techniques at the ELF electromagnetic wave observatory at Calar Alto (Spain). The solutions adopted allow measurement of seven resonance modes with an acquisition time of 30 min, where the S/N ratio in the fundamental mode was 39 dB.