Enlaces

Web of Science ResearcherID: L-8298-2014
ORCID: 0000-0001-8980-6163
SCOPUS Author ID: 57196297883
Researchgate: https://www.researchgate.net/profile/Nuria-Novas/research
brújula UAL: http://brujula.ual.es/authors/698.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.
• M. E. González-Revuelta, N. Novas, J. A. Gazquez, M. A. Rodríguez-Maresca, J. M. García-Torrecillas «User Perception of New E-Health Challenges: Implications for the Care Process». International Journal of Environmental Research and Public Health, 2022. (10.3390/ijerph19073875) (Abstract)

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  Establishing new models of health care and new forms of professional health-patient communication are lines of development in the field of health care. The onset of the COVID-19 pandemic has accelerated the evolution of information systems and communication platforms to guarantee continuity of care and compliance with social distancing measures. Our objective in this article was, firstly, to know the expectations of patients treated in the healthcare processes “cervical cancer” and “pregnancy, childbirth and puerperium” regarding online access to their clinical history and follow-up in the care process. Secondly, we analyzed times involved in the cervical cancer process to find points of improvement in waiting times when digital tools were used for communication with the patient. A descriptive cross-sectional study was carried out on 120 women included in any of the aforementioned processes using a hetero-administered questionnaire. The analysis of times was carried out using the Business Intelligence tool Biwer Analytics®. Patients showed interest in knowing their results before the appointment with the doctor and would avoid appointments with their doctor if the right conditions were met. Most recognized that this action would relieve their restlessness and anxiety. They were highly interested in receiving recommendations to improve their health status. It was estimated that there was room for improvement in the times involved in the care process, which could be shortened by 34.48 days if communication of results were through digital information access technologies. This would favor the optimization of time, resources and user perception.
• 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.
• N. Novas, R. M. Garcia, J. M. Camacho, A. Alcayde «Advances in solar energy towards efficient and sustainable energy». Sustainability (Switzerland), 2021. (10.3390/su13116295) (Abstract)

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  Conventional energy resources are not climate sustainable. Currently, engineers and scientists are looking for sustainable energy solutions influenced by climate change. A wide variety of sustainable natural energy resources are available, but they require technical solutions for their implementation. The general trend in energy research is based on renewable resources, amongst which solar energy stands out, being the most mature and widely accepted. In this paper, the current state of the sustainable energy system has been analysed. The main purpose is to provide additional context to assess future scenarios. The study of past contributions allows sustainability planning and increasing the welfare of future society. The aim is to highlight global trends in research on sustainable solar energy from 1995 to 2020 through a bibliometric analysis of 4260 publications. According to their linkages, the analysed articles are distributed in nine clusters: Sustainability assessment, Sustainable energy solutions, Environmental payback time analysis, Sustainability of solar energy in different scenarios, Environmental sustainability, Solar energy applications, Sustainable energy optimisation, Energy transition and Energy and sustainable scenarios. The most repeated keywords are Sustainability, Renewable energy, and Solar energy. Energy research and the exploration of new renewable solar resources are still necessary to meet sustainable energy’s future challenges.
• 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.
• N. Novas, A. Alcayde, I. Robalo, F. Manzano-Agugliaro, F. Gil «Energies and its worldwide research». Energies, 2020. (10.3390/en13246700) (Abstract)

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  Energy efficiency and management is certainly one of the key drivers of human progress. Thus, the trends in the energy research are a topic of interest for the scientific community. The aim of this study is to highlight global research trends in this field through the analysis of a scientific journal indexed exclusively in the energy and fuels category. For this purpose, a journal has been selected that is in the center of the category considering its impact factor, which is only indexed in this category and of open access, Energies of the publisher MDPI. Therefore, a bibliometric analysis of all the contents of the journal between 2008 and 2020, 13,740 documents published, has been carried out. Analyzing the articles that are linked to each other by their citations, 14 clusters or research topics have been detected: smart grids; climate change-electric energy community; energy storage; bioenergy sources; prediction algorithms applied to power; optimization of the grid link for renewable energy; wind power; sustainability of power systems; hydrocarbon improvements; conversion of thermal/electrical energy; electric motor advancements; marine renewable energy; hydropower and energy storage; and preventive techniques in power transformers. The main keywords found were electric vehicle, renewable energy, microgrid, smart grid, and energy efficiency. In short, energy research remains necessary to meet the future challenge of sustainable energy with high efficiency and the exploration of new renewable resources, all for increasingly sustainable cities.
• F. Ferrón-Carrillo, J. C. Gómez-Cortés, J. Regalado-Sánchez, M. Urrestarazu, N. Novas «Algorithm implementation in MATLAB for root measurement». Computers and Electronics in Agriculture, 2020. (10.1016/j.compag.2020.105487) (Abstract)

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  Modern agriculture has a growing level of technification, through the incorporation of new technologies of great utility in other disciplines different from the agricultural sector. The use of remote sensing systems to monitor the physiological state of crops by observing the volume and appearance of the roots is another example of its application. These systems are based on the detection and recording of spectral variations of crops both in the range of visible radiation and within the electromagnetic spectrum in the infrared range. Thermography is a visual tool that has found applications in agriculture. The monitoring of water status through the observation of crop roots is essential to optimize the use of water in agriculture, as well as its development and final production. The efficiency of root growth in basil crops has been analysed in a chamber with controlled humidity and temperature. The aim of this work was to demonstrate a better efficiency of root analysis with a first non-invasive and environmentally friendly method, visually, using thermal imaging and digital processing in the evaluation of radical growth versus two other conventional methods: traditional standard analysis and invasive analysis with digital image treatment. The results also showed advantages in the use of thermographic images compared to the use of RGB images for roots smaller than 1 mm.
• R. M. Garcia, N. Novas, A. Alcayde, D. El Khaled, F. Gil «Electronics and its worldwide research». Electronics, 2020. (10.3390/electronics9060977) (Abstract)

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  The contributions of researchers at a global level in the journal Electronics in the period 2012–2020 are analyzed. The objective of this work is to establish a global vision of the issues published in the Electronic magazine and their importance, advances and developments that have been particularly relevant for subsequent research. The magazine has 15 thematic sections and a general one, with the programming of 385 special issues for 2020–2021. Using the Scopus database and bibliometric techniques, 2310 documents are obtained and distributed in 14 thematic communities. The communities that contribute to the greatest number of works are Power Electronics (20.13%), Embedded Computer Systems (13.59%) and Internet of Things and Machine Learning Systems (8.11%). A study of the publications by authors, affiliations, countries as well as the H index was undertaken. The 7561 authors analyzed are distributed in 87 countries, with China being the country of the majority (2407 authors), followed by South Korea (763 authors). The H‐ index of most authors (75.89%) ranges from 0 to 9, where the authors with the highest H‐Index are from the United States, Denmark, Italy and India. The main publication format is the article (92.16%) and the review (5.84%) The magazine publishes topics in continuous development that will be further investigated and published in the near future in fields as varied as the transport sector, energy systems, the development of new broadband semiconductors, new modulation and control techniques, and more.
• 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.
• N. Novas, A. Fernández-García, F. Manzano-Agugliaro «A simplified method to avoid shadows at parabolic-trough solar collectors facilities». Symmetry, 2020. (10.3390/sym12020278) (Abstract)

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  Renewable energy today is no longer just an affordable alternative, but a requirement for mitigating global environmental problems such as climate change. Among renewable energies, the use of solar energy is one of the most widespread. Concentrating Solar Power (CSP) systems, however, is not yet fully widespread despite having demonstrated great efficiency, mainly thanks to parabolic-trough collector (PTC) technology, both on a large scale and on a small scale for heating water in industry. One of the main drawbacks to this energy solution is the large size of the facilities. For this purpose, several models have been developed to avoid shadowing between the PTC lines as much as possible. In this study, the classic shadowing models between the PTC rows are reviewed. One of the major challenges is that they are studied geometrically as a fixed installation, while they are moving facilities, as they have a tracking movement of the sun. In this work, a new model is proposed to avoid shadowing by taking into account the movement of the facilities depending on their latitude. Secondly, the model is tested to an existing facility as a real case study located in southern Spain. The model is applied to the main existing installations in the northern hemisphere, thus showing the usefulness of the model for any PTC installation in the world. The shadow projected by a standard, the PTC (S) has been obtained by means of a polynomial approximation as a function of the latitude (Lat) given by S = 0.001-Lat2 + 0.0121-Lat + 10.9 with R2 of 99.8%. Finally, the model has been simplified to obtain in the standard case the shadows in the running time of a PTC facility.
• N. Novas, A. Alcayde, D. El Khaled, F. Manzano-Agugliaro «Coatings in photovoltaic solar energy worldwide research». Coatings, 2019. (10.3390/coatings9120797) (Abstract)

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  This paper describes the characteristics of contributions that were made by researchers worldwide in the field of Solar Coating in the period 1957-2019. Scopus is used as a database and the results are processed while using bibliometric and analytical techniques. All of the documents registered in Scopus, a total of 6440 documents, have been analyzed and distributed according to thematic subcategories. Publications are analyzed from the type of publication, field of use, language, subcategory, type of newspaper, and the frequency of the keyword perspectives. English (96.8%) is the language that is most used for publications, followed by Chinese (2.6%), and the rest of the languages have a less than < 1% representation. Publications are studied by authors, affiliations, countries of origin of the authors, and H-index, which it stands out that the authors of China contribute with 3345 researchers, closely followed by the United States with 2634 and Germany with 1156. The Asian continent contributes the most, with 65% of the top 20 affiliations, and Taiwan having the most authors publishing in this subject, closely followed by Switzerland. It can be stated that research in this area is still evolving with a great international scientific contribution in improving the efficiency of solar cells.
• M. Chihib, E. Salmerón-Manzano, N. Novas, E. Salmerón-Manzano «Bibliometric maps of BIM and BIM in universities: A comparative analysis». Sustainability (Switzerland), 2019. (10.3390/su11164398) (Abstract)

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  Building Information Modeling (BIM) is increasingly important in the architecture and engineering fields, and especially in the field of sustainability through the study of energy. This study performs a bibliometric study analysis of BIM publications based on the Scopus database during the whole period from 2003 to 2018. The aim was to establish a comparison of bibliometric maps of the building information model and BIM in universities. The analyzed data included 4307 records produced by a total of 10,636 distinct authors from 314 institutions. Engineering and computer science were found to be the main scientific fields involved in BIM research. Architectural design are the central theme keywords, followed by information theory and construction industry. The final stage of the study focuses on the detection of clusters in which global research in this field is grouped. The main clusters found were those related to the BIM cycle, including construction management, documentation and analysis, architecture and design, construction/fabrication, and operation and maintenance (related to energy or sustainability). However, the clusters of the last phases such as demolition and renovation are not present, which indicates that this field suntil needs to be further developed and researched. With regard to the evolution of research, it has been observed how information technologies have been integrated over the entire spectrum of internet of things (IoT). A final key factor in the implementation of the BIM is its inclusion in the curriculum of technical careers related to areas of construction such as civil engineering or architecture.
• N. Novas, J.A. Álvarez-Bermejo, J.L. Valenzuela, J. A. Gazquez, F. Manzano-Agugliaro «Development of a smartphone application for assessment of chilling injuries in zucchini». Biosystems Engineering, 2019. (10.1016/j.biosystemseng.2019.03.009) (Abstract)

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  Depending on their type and variety, horticultural products are injured by cold when this follows a period of exposure to a range of temperatures above their freezing point. These lesions are a result of tissues having been weakened rendering them unable to conduct normal metabolic processes. Cold stress produces physiological and biochemical alterations and cellular dysfunctions in response to cooling that negatively affect their quality and frequently result in products unsuitable for sale. Currently, evaluation of cold damage is usually carried out qualitatively by experts. This is not particularly accurate and, above all, depends on the observer and is therefore subjective. This study developed an application for a smartphone that automates this process and applied it to one of the most sensitive vegetables, zucchini or courgette. The results provide qualitative values and avoid all subjectivity. To demonstrate their validity, the results were compared to those of the standard method. They were also compared among distinct varieties allowing thresholds of hue and saturation settings to be adapted to these different varieties. These settings allow users to calculate damage in a more reliable manner depending on the specific variety analysed. This application allows for new perspectives in the field of evaluation of cold damage to fruits and vegetables in general and in particular zucchini.
• J. A. Garrido-Cardenas, F. Manzano-Agugliaro, L. González-Cerón, F. Gil, A. Alcayde, N. Novas, C. Mesa-Valle «The Identification of Scientific Communities and Their Approach to Worldwide Malaria Research». International Journal of Environmental Research and Public Health, 2018. (10.3390/ijerph15122703) (Abstract)

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  It is essential to establish a pattern to detect the strengths and weaknesses of working groups publishing on malaria, to promote coordination to facilitate the eradication of the disease. Given the complexity of the scientific network of groups and institutions studying malaria, it is necessary to use a mathematical algorithm that allows us to know the real structure of research on the disease in the world. In this work, articles with the word “malaria” in the title or author keywords gathered from Elsevier Scopus database were analyzed. By means of specific software, graphs were created. The analysis of the data allowed established different scientific communities, among which two were very diverse: one formed by those groups concerned about the vector transmission and control, and another one focused on the drug resistance of the parasite. Basic, applied, and operational research to eradicate malaria is an ambitious goal of the international institutions and the scientific community. The combination of effort and the establishment of a worldwide-scientific network that allows an effective interconnection (exchange) of knowledge, infrastructure technology, collaborators, financial resources, and datasets will contribute more effectively to end the disease.
• D. El Khaled, N. Novas, J. A. Gazquez, F. Manzano-Agugliaro «Microwave dielectric heating: Applications on metals processing». Renewable and Sustainable Energy Reviews, 2018. (10.1016/j.rser.2017.10.043) (Abstract)

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  Microwave material processing is a novel energy efficient technology with improved mechanical properties, minimized defects and economical and environmental advantages making it a convenient application for various types of materials. Although, microwave interaction with matter has been largely investigated and published in food processing, ceramics and chemistry, no particular work has been involved in collecting the interactions of microwaves with metals and placing a special emphasis on their interaction with metals and metal-based formulations, and here resides the aim of the review: consolidating the fundamentals of microwave heating applications as a time and energy saving application and addressing its various applications and mechanisms with metal interactions seeking a more sustainable environment. This review reports the latest literature findings on microwave processing fundamentals and highlights the advanced technological improvement applied on metals in this field. It focuses on the relevant industrial applications related to the development of microwave technology on metals and its possible future processing in this specific scope of investigation.
• D. El Khaled, N. Novas, J. A. Gazquez, F. Manzano-Agugliaro «Dielectric and bioimpedance research studies: A scientometric approach using the scopus database». Publications, 2018. (10.3390/publications6010006) (Abstract)

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  This work describes theworldwide applications of dielectric and bioimpedancemeasurements techniques in various fields. Dielectric and bioimpedance spectroscopy are major non-destructive measurement systems with great potential in the technology field. All results produced by the Scopus database were used as the core of the study in hand, with different items from journals, papers and conference proceedings being taken into account. The results of this analysis show that the interest in electrical properties has risen in the last years due to the advanced technological measurements offered on the scientific level. Results show that bioimpedance studies are considerably more recent compared to dielectric studies, and are more directed towards medical purposes while dielectric spectroscopy focuses on physical aspects, and is used mostly in engineering and material science. It can be stated that bioimpendance and dielectric spectroscopy are being increasingly applied and that they have the capacity to deepen and enhance research investigation.
• A. J. Perea-Moreno, A. García-Cruz, N. Novas, F. Manzano-Agugliaro «Rooftop analysis for solar flat plate collector assessment to achieving sustainability energy». Journal of Cleaner Production, 2017. (10.1016/j.jclepro.2017.02.019) (Abstract)

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  The insufficiency of current energy sources, elevated costs and global climate worriment are distinctive factors making of renewable energy an issue of boosting consideration. In this concern, solar energy is viewed as being indefinitely environmental friendly, carbon-free, beneficial nature with appreciated cost potentials and is witnessing fast progressing. Following the Horizon 2020 climate and energy package, the volume of gases emitted by greenhouses has to be cut down by 20% by all the European Union (EU) member countries in order to enhance energy performance by 20% and raise the renewable energy rate to 20% by 2020. Solar energy on building roofs plays a crucial aspect in renewable and sustainable energy consumption of high-density human habitats. A merest energy should be allocated to provide hot water service from solar sources, as other European norms for new buildings by the Spanish Technical Building Code, similarly to other European regulation on achievement objectives. The climate zone and the overall demand of hot water in the building regulate this minimal amount needed. This manuscript use a new methodology for automatic detection of geometric patterns from aerial or space images using a Hierarchical Temporal Memory (HTM) algorithm. In this way, an automatic method for the identification of building roofs in order to assess the opportunities available to install solar thermal systems in small urban areas has been developed. As case of study: a village with 7000 inhabitants was analyzed in the South of Spain. The maximum overall accuracy obtained among the different classifications made was 98.05%, avoiding problems related to the use of images with high spatial resolution, as in the salt-and-pepper noise effect. This approach contributes reducing the generated carbon and GHG emissions and open new perspectives for energy savings strategies to optimize the energy efficiency of buildings. In the case study, implementing the solar thermal systems would come out with a saving of 1.4 tons of CO2 per inhabitant.
• D. El Khaled, N. Novas, R. M. Garcia, F. Manzano-Agugliaro «Alcohols and alcohols mixtures as liquid biofuels: A review of dielectric properties». Renewable and Sustainable Energy Reviews, 2016. (10.1016/j.rser.2016.08.032) (Abstract)

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  Oils, pure alcohols and alcohols mixtures have a complicated dielectric behavior. The strong electric field of the ions affects intensively the molecular interaction of solvents. Microwave heating resides in the characterization of dielectric properties. Classified as biodiesel precursors, advances in microwave technology of alcohols have a significant potential in improving the biodiesel production. In this context, this review provides basic knowledge on the dielectric properties theory and the heating phenomenon in the microwave fields. The main goal of the paper is to provide an organized summary of the main chemical and physical properties of alcohols and links them to their corresponding research studies dealing with dielectric properties measurements. The review covers the dielectric constant and loss factor variations observed with temperature and frequency, the relaxation time and the tangent loss of various mixtures found in the literature. Moreover, the review provides an updated database for organic solvents and alcohols to account for their abilities to couple in microwave radiation. The aim of the work is building a rigid bridge between chemico-physical and dielectric properties so it can make an essential step towards improving biofuels production. This review opens new perspectives for further investigation of dielectric properties that are interesting for microwave heating studies.
• D. El Khaled, N. Novas, J. A. Gazquez, A. J. Perea-Moreno, F. Manzano-Agugliaro «Dielectric spectroscopy in biomaterials: Agrophysics». Materials, 2016. (10.3390/ma9050310) (Abstract)

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  Being dependent on temperature and frequency, dielectric properties are related to various types of food. Predicting multiple physical characteristics of agri-food products has been the main objective of non-destructive assessment possibilities executed in many studies on horticultural products and food materials. This review manipulates the basic fundamentals of dielectric properties with their concepts and principles. The different factors affecting the behavior of dielectric properties have been dissected, and applications executed on different products seeking the characterization of a diversity of chemical and physical properties are all pointed out and referenced with their conclusions. Throughout the review, a detailed description of the various adopted measurement techniques and the mostly popular equipment are presented. This compiled review serves in coming out with an updated reference for the dielectric properties of spectroscopy that are applied in the agrophysics field.
• J. A. Gazquez, N. Novas, F. Manzano-Agugliaro «Intelligent low cost telecontrol system for agricultural vehicles in harmful environments». Journal of Cleaner Production, 2016. (10.1016/j.jclepro.2015.11.015) (Abstract)

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  The use of vehicles to control pests and crop diseases is needed to maintain agricultural production. This paper describes how to design and implement a low cost intelligent telecontrol system applied for agricultural machinery that are designed for use in places where human presence is not adequate, such as pesticide spraying tasks in farming environments as greenhouses. The intelligent system designed basically consists of these parts: States Encoding, Console Automaton, Vehicle Automaton, Communication System and Security of Communications. This system has been developed with a special-purpose UHF narrow band modem that interchanges digital operative commands/states from the console to the vehicle. The intelligent telecontrol system acts as a security system to protect against outsiders, and loss of communications due to fading or others interference. The originality of this system is based on the fact that it is 10 times cheaper than autonomous systems; those systems need electronic systems, GPS, a complex sensorial system, and a beforehand mapping performed on the new work environment. Related to classic remote control, our system protects from potential oversights of the operator. In addition, in the proposed system, the vehicle state is shown in the console, due the bidirectional communications. The system was successfully applied in prototype vehicle used for spraying tasks, and the result shows that the system operated stably and has confirmed the effectiveness of this intelligent telecontrol system. The proposed technology will help providing solutions for humans and robots working together in agricultural environments considered to be harmful to humans.
• 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.
• D. El Khaled, N. Novas, J. A. Gazquez, R. M. Garcia, F. Manzano-Agugliaro «Fruit and vegetable quality assessment via dielectric sensing». Sensors (Switzerland), 2015. (10.3390/s150715363) (Abstract)

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  The demand for improved food quality has been accompanied by a technological boost. This fact enhances the possibility of improving the quality of horticultural products, leading towards healthier consumption of fruits and vegetables. A better electrical characterization of the dielectric properties of fruits and vegetables is required for this purpose. Moreover, a focused study of dielectric spectroscopy and advanced dielectric sensing is a highly interesting topic. This review explains the dielectric property basics and classifies the dielectric spectroscopy measurement techniques. It comprehensively and chronologically covers the dielectric experiments explored for fruits and vegetables, along with their appropriate sensing instrumentation, analytical modelling methods and conclusions. An in-depth definition of dielectric spectroscopy and its usefulness in the electric characterization of food materials is presented, along with the various sensor techniques used for dielectric measurements. The collective data are tabulated in a summary of the dielectric findings in horticultural field investigations, which will facilitate more advanced and focused explorations in the future.
• 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.
• F. Manzano-Agugliaro, M. Castro-García, A. M. Pérez-Romero, A. García-Cruz, N. Novas, E. Salmerón-Manzano «Alternative methods for teaching cadastre and remote sensing». Survey Review, 2015. (10.1179/1752270615Y.0000000046) (Abstract)

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  Cadastre is essential for the sustainable development of modern society. As well, mapping and surveying is one of the most important tasks for surveyors worldwide in order to maintain the Cadastre. This article summarises a recent study conducted by the authors on overall student assessment of learning Cadastre and Remote Sensing. The goal is to highlight which teaching method has better success rate for students. This paper studies the academic outcomes for a total of 286 students divided into two optional courses of Cadastre at higher education for eight academic years. They are analysed through three different educational modalities: face-to-face (FTF), blended and online for one course, and FTF and online for another. In order to deepen the analysis, a model using classification trees (Classification and regression trees, CART) was created. It has been observed that the blended modality is the one that offers worst results in terms of success rate. If we compare exclusively the FTF method to the online one, we can conclude that the latter shows better results in all respects, improving the success rate and increasing the percentage of students who obtain highest marks.
• N. Novas, J. A. Gazquez, M. Noguerol «Real-time biomedical telemetry system for ambulances». Healthcare Administration: Concepts, Methodologies, Tools, and Applications, 2014.
• J. Clement, N. Novas, J. A. Gazquez, F. Manzano-Agugliaro «An active contour computer algorithm for the classification of cucumbers». Computers and Electronics in Agriculture, 2013. (10.1016/j.compag.2013.01.006) (Abstract)

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  The cucumber is one of the most important crops worldwide and, because it is generally consumed fresh, it must be classified into quality categories. The European classification system includes a parameter that relates the degree of curvature relative to the length. Until now, this classification could not been be achieved with an automatic system due to the difficulty associated with correctly calculating the axis of a cucumber. This article describes a computer algorithm that uses active contours or " snakes" to classify cucumbers by length and curvature. This algorithm demonstrates an advantage in the determination of the central line of each cucumber, based on an iterative process that is quick and carries out the classification process efficiently. The method was validated against human classification for 360. cucumbers and was also compared with an ellipsoid approximation method. The active contour method reduced the classification error by 15% points, compared with the ellipsoid approximation method, to 1%, with no serious errors (i.e., misclassification of Class Extra and I into Class II or vice versa). Meanwhile, the ellipsoid approximation method led to a 16% error rate, of which 2% were serious errors (an error of two classes). The developed approach is applicable to fresh cucumber commercial classification lines to meet the requirements of the European regulations for cucumber classification.
• R. M. Garcia, J. A. Gazquez, N. Novas «Characterization and modeling of high-value inductors in ELF band using a vector network analyzer». IEEE Transactions on Instrumentation and Measuremen, 2012. (10.1109/TIM.2012.2215141) (Abstract)

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  Characterization and modeling of high-value inductors (hundreds to thousands of henrys) are complex problems, exacerbated when working in the extremely low frequency (ELF) range. This paper details the measurement and characterization of inductors using a vector network analyzer that has a bottom operating frequency of 5 Hz. Using this device, we establish a strategy for measuring the impedance of high-inductance coils - with or without a high-permeability core - and propose a mathematical model that can explain the behavior of these high-inductance coils, which incorporate long lengths of winding wire, as a function of working frequency. These inductors were constructed as part of a research project on ELF electromagnetic fields. The importance of making a complete characterization derives from the need to exploit the largest possible amount of energy captured by the coil, which acts as a sensor. We propose a mixed model of concentrated and distributed parameters that fits the experimental results with an error of about 2% for the frequency range of 5-500 Hz, as part of the characterization process. The effects of the magnetic core on inductance and winding resistance, as a function of frequency, have been characterized in terms of concentration of the magnetic field.
• J. Clement, N. Novas, J. A. Gazquez, F. Manzano-Agugliaro «High speed intelligent classifier of tomatoes by colour, size and weight». Spanish Journal of Agricultural Research, 2012. (10.5424/sjar/2012102-368-11) (Abstract)

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  At present most horticultural products are classified and marketed according to quality standards, which provide a common language for growers, packers, buyers and consumers. The standardisation of both product and packaging enables greater speed and efficiency in management and marketing. Of all the vegetables grown in greenhouses, tomatoes are predominant in both surface area and tons produced. This paper will present the development and evaluation of a low investment classification system of tomatoes with these objectives: to put it at the service of producing farms and to classify for trading standards. An intelligent classifier of tomatoes has been developed by weight, diameter and colour. This system has optimised the necessary algorithms for data processing in the case of tomatoes, so that productivity is greatly increased, with the use of less expensive and lower performance electronics. The prototype is able to achieve very high speed classification, 12.5 ratings per second, using accessible and low cost commercial equipment for this. It decreases fourfold the manual sorting time and is not sensitive to the variety of tomato classified. This system facilitates the processes of standardisation and quality control, increases the competitiveness of tomato farms and impacts positively on profitability. The automatic classification system described in this work represents a contribution from the economic point of view, as it is profitable for a farm in the short term (less than six months), while the existing systems, can only be used in large trading centers.
• N. Novas, J. A. Gazquez, J. F. L. Rodríguez, F. Manzano-Agugliaro «Telemetry system for transmission data from an ambulance». Dyna, 2012. (Abstract)

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  Currently the transfer of critically patients is carried out through a coordination center for outpatient care and hospital care. Modern wireless communications technologies offer the possibility of improving some systems in the context of critical care emergency; under these situations are many occasions requiring additional examinations. The telemetry system developed in this paper provides real-time communication of patient's blood biochemistry that with a clinical suspicion based on an adequate history taking and physical examination, require this kind of diagnostic tests to better assess the patient's condition. This allows improving attendance at all times and the preparation of all necessary resources for the rapid, and effective patient reception in the hospital without additional cost, since these tests also would be required in the hospital. This allows early detection of conditions that endanger imminent the life of a patient. The results verify the interest of this new service.
• J. A. Gazquez, N. Novas, R. M. Garcia, et al. «Rescaled range analysis of ELF natural electromagnetic noise from Antarctica». Progress In Electromagnetics Research Symposium Proceedings, Marrakesh, Morocco,, 2011. (Abstract)

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  We present the results of a statistical rescaled range (R/S) analysis of natural electromagnetic noise in the extremely low frequency (ELF) band. The Hurst exponent was derived from the records of two horizontal magnetic antennas taken in Antarctica with a sample frequency of 512 Hz, to guarantee enough resolution with the small number of samples in the analysis. The study shows that ELF radio noise is a persistent random process, maintaining its value between 0.75 and 0.85 for the different series analyzed. A numerical simulation was performed, in which each discharge was modeled by the radiated field of a wire antenna excited by a Gaussian pulse, demonstrating a way of inferring lightning rates from R/S analysis.