Monitorización de la actividad de descargas parciales en sistemas aislantes papel-aceite mediante la detección y análisis de sus emisiones acústicas

Los sistemas aislantes papel-aceite son una parte crítica en el diseño y en el correcto funcionamiento de los transformadores de potencia. Debido a las condiciones de operación del transformador, el sistema aislante está sometido a un estrés continuo, provocando una degradación constante en el mismo hasta su fallo. Para diagnosticar con la suficiente antelación la aparición de daño en el aislante y anticipar el fallo del transformador es necesario monitorizar un fenómeno que esté asociado a la degradación del sistema aislante. En este sentido, las descargas parciales (DP) han demostrado que son un marcador fiable del envejecimiento del aislante, ya que son a su vez síntoma y causa de dicho envejecimiento. Las DP son un fenómeno físico complejo que consiste en descargas eléctricas localizadas causadas por la ruptura parcial del medio aislante bajo la influencia de la tensión del campo eléctrico local. Se manifiestan como pulsos de corriente extremadamente rápidos (duración menor que 1 μs) y de baja magnitud (menor que 10000 pC). Son además un proceso estocástico, por lo que una DP no es significativa de la presencia de un fallo en el aislante, y es necesario un acercamiento estadístico sobre un conjunto de medidas de DP. La monitorización de DP se puede realizar por procedimientos eléctricos (corrientes inducidas) y acústicos (impulsos de ultrasonidos), los cuales resultan ser complementarios. De la medida eléctrica, además de la posible identificación del tipo de descargas, se obtiene una referencia de tiempos cero para calcular el tiempo de vuelo de las señales acústicas detectadas, permitiendo con ello la localización del origen de la DP. El objetivo del presente trabajo es monitorizar DP a través de sus emisiones acústicas, utilizando como referencia de tiempos la señal eléctrica, para obtener información relacionada con el grado de envejecimiento del aislante. Para alcanzar este objetivo se han marcado cuatro hitos principales. El primero consiste en diseñar una plataforma de ensayo que permita generar y estudiar distintos tipos de descargas parciales. Con este estudio se pretende caracterizar sus señales eléctricas y las emisiones acústicas asociadas, así como conocer los efectos producidos sobre el aislante por la presencia de distintos tipos de descargas. El segundo hito está relacionado con la dificultad para detectar e identificar las emisiones acústicas de DP debido a la atenuación y a la degradación. Por ello se presentan varias técnicas de procesamiento que permiten analizar las señales acústicas y eléctricas de las DP. Posteriormente, se caracteriza la respuesta de cada técnica mediante una simulación creada específicamente para ese fin. El tercer hito es el diseño y programación de un algoritmo en Matlab® que permite la monitorización de la actividad de DP con distintos tipos de sensores. Por último, el cuarto hito consiste en aplicar el sistema de monitorización a un problema real y conocido dentro de la plataforma de ensayo y estudiar su viabilidad para utilizarlo en entornos más complejos.Paper-oil insulation systems are a critical part of the design and operation of power transformers. Due to the operating conditions of the transformer, the insulation system is subjected to a continuous stress, causing a constant degradation in it until its failure. To diagnose the existence of damage in the insulation and anticipate the failure of the transformer, it is necessary to monitor a phenomenon that is associated with the degradation of the insulation system. In this sense, partial discharges (PD) have shown that they are a reliable marker of the aging of the insulation, since they are a symptom and a cause of this aging. PD are a complex physical phenomenon consisting of a localized electric discharge caused by the partial break of the insulation medium under the influence of local electric field voltage. They appear as an extremely fast current pulse (duration below 1 μs) and low magnitude (charge below 10000 pC). They are also a stochastic process, so a PD is not significant of the presence of a failure in the insulation, and a statistical approach of a set of PD measurements is necessary. PD monitoring can be performed by electrical (induced currents) and acoustic (ultrasonic pulses) procedures, which are complementary. From the electrical measurement, besides the possibility of PD identification, a zero-time reference is obtained to calculate the flight time of the detected acoustic signals, allowing the location of the origin of the PD. The objective of the present work is to monitor PD through its acoustic emissions, using as a zero-time reference the electrical signal, to obtain information on the degree of aging of the insulation. To reach this objective four key milestones have been marked. The first one is the design of a test bench to generate and study different types of PD. From this study, it is expected to characterize its associated electrical and acoustic emissions, as well as knowing the effects produced by the presence of different types of PD in the insulation. The second milestone is related to the difficulty in detecting and identifying acoustic PD emissions due to the attenuation and the degradation. Therefore, several signal processing techniques are presented which allow the analysis of the acoustic and electrical signals of PD. Subsequently, the response of each technique is characterized, through a simulation created expressly for that purpose. The third milestone is the design and the programming of an algorithm in Matlab® that allows the monitoring of PD activity with different kind of sensors. Finally, the fourth milestone consists of applying the monitoring system to a real and known problem within the test bench and study its feasibility for use in more complex environments.Programa Oficial de Doctorado en Ingeniería Eléctrica, Electrónica y AutomáticaPresidente: Javier Sanz Feito.- Secretario: Fernando Machado Domínguez.- Vocal: Miguel A. Sánchez-Urán Gonzále

Corporate Social Responsibility and Crowdfunding: The Experience of the Colectual Platform in Empowering Economic and Sustainable Projects

We would like to thank Colectual platform for illustrating us on its activity and for the database provided.In recent years, sustainable crowdfunding has been one of the key elements in the search for new sources of financing. This has involved eliminating financial barriers and intermediaries, bringing entrepreneurs’ projects closer to fund providers, and thus instigating changes in traditional investment and profitability parameters. Among these indicators, the sustainable business return and its relationship with Corporate Social Responsibility (CSR) could be a relevant factor to improve the cost of funding, to explain the return on assets (ROA), and, consequently, impacting on the return on equity (ROE). In this context, this paper takes as a reference 101 projects that are part of Colectual’s lending. We analyze factors such as sustainability—the application of CSR across a social responsibility index; the financial characteristics of the company—liquidity, leverage, and solvency; and the characteristics of the loans related to crowdfunding—amount, maturity, and charge rate of the loan. Our study provides empirical evidence that, besides financial characteristics, the commitment to CSR can improve collective lending and the management of resources, as well as enhance the capital wealth of companies, by improving shareholder profitability or ROE. Investors consider not only financial risk but also sustainability factors

Instrumentation system for location of partial discharges using acoustic detection with piezoelectric transducers and optical fiber sensors

In this paper, a multichannel instrumentation system for the location of partial discharges (PDs) in power transformers is presented. It is based on the detection of the acoustic emissions from PDs in oil with several piezoelectric (PZT) and fiber optic sensors. An acoustic detection and location approach is proposed based on a time reference given by one fiber optic sensor installed inside the tank and the times of arrival to several PZT sensors installed outside the tank (two in front of each phase windings of a three phase transformer for a typical application). The signal processing includes digital denoising techniques and time-difference lookup table-based 3-D location algorithms; these algorithms have been implemented with virtual instrumentation. The system is tested in an acoustic experimental setup and the location accuracy is evaluated. Finally, the error propagation from the times of arrival and the influence of the number of sensors and their sites in the 3-D location algorithm were analyzed.This work was supported in part by the Spanish National Ministry of Science and Innovation under the Project DPI 2009-14628-C03-01 and in part by the scholarship FPI under Grant BES-2010-04208

The Impact of Enforcement Capabilities on the Effectiveness of Public Assessment on Occupational Safety

número del art. 6426(1) Objective: The objective of this study was to evaluate the effect of enforcement capabilities on the efficacy of two public interventions to improve occupational safety in olive mills. (2) Method: The difference in efficacy was evaluated by comparing the risks detected in two groups in an initial assessment (with visits in the 2006–2008 period) to the risks detected in a later assessment, either after an intervention by Authorized Technicians with enforcement capabilities or after an intervention by Technical Advisors without enforcement capabilities (2011–2013). The assessments identified risks in the companies, according to a specific risk map for olive oil mill enterprises. (3) Results: Statistically significant differences were observed in the comparison of the risk reductions of the two groups, with regard to the initial assessment. The greatest reductions in risk were found in the companies that received interventions by Authorized Technicians with enforcement capabilities, in the sections of individual protection equipment and the storage of dangerous products. (4) Conclusion: Interventions by Authorized Technicians with enforcement capabilities are more effective than interventions by Technical Advisors without enforcement capabilities

Nanostructured Au(111)/Oxide epitaxial heterostructures with tailoring plasmonic response by a one-step strategy

In this work, we present a strategy for developing epitaxial incommensurate nanostructured Au/oxide heterostructures with tunable plasmonic response. Previously, high-quality single-phase and single-oriented alfa-Fe2O3(0001) thin films were achieved, which have been used as a template for noble-metal epitaxial deposition. The complex systems have been grown by pulsed laser deposition on two different types of oxide substrates: alfa-Al2O3(0001) and SrTiO3(111). A one-step procedure has been achieved tailoring the isolated character and the morphological features of Au nanostructures through the substrate temperature during Au growth, without altering the structural characteristics of the hematite layer that is identified as a single iron oxide phase. The epitaxial character and the lattice coupling of Au/oxide bilayers are mediated through the sort of oxide substrate. Single-oriented Au(111) islands are disposed with a rotation of 30° between their crystallographic axes and those of alfa-Fe2O3(0001). The Au(111) and SrTiO3(111) lattices are collinear, while a rotation of 30° happens with respect to the alfa-Al2O3(0001) lattice. The crystallographic domain size and crystalline order of the hematite structure and the Au nanostructured layer are dependent on the substrate type and the Au growth temperature, respectively. Besides, the functional character of the complex systems has been tested. The localized surface plasmons related to Au nanostructures are excited and controlled through the fabrication parameters, tuning the optical resonance with the degree of Au nanostructuring.This work was supported by the Ministerio Español de Ciencia, Innovación y Universidades (MCIU), and the Consejo Superior de Investigaciones Cientificas (CSIC) through the project PIE-2010 6 OE 013. J.L.-S. and E.E. acknowledge the FPI fellowship and the Torres Quevedo contract (ref: PTQ-14-07289). The ESRF, MCIU, and CSIC are acknowledged for the provision of synchrotron radiation facilities. The authors thank Dr M.A. García for the useful discussion about the plasmonic results and Carlos Beltrán for technical support during the experiments at the BM25 beamline at The ESRF

The service learning values map

[spa] A pesar de que la bibliografía especializada reconoce el aprendizaje-servicio como una metodologíarelevante de educación en valores, no se dispone todavía de una relación suficientemente completa dela pluralidad de valores que activa. El objetivo de este artículo es construir un mapa fiable de los valores quepropone esta metodología. Para conseguirlo se definirán los niveles de aprendizaje que se superponen en una práctica educativa compleja y luego se determinarán los valores que se trabajan en cada uno de los niveles de la práctica del aprendizaje-servicio. Para conseguirlo se ha realizado un trabajo de reconstrucción racional basado en la optimización recíproca conseguida entre una selección de buenas experiencias de aprendizaje-servicio y la teoría de las prácticas morales y del aprendizaje-servicio. Esta metodología ha permitido establecer tres niveles simultáneos de aprendizaje la práctica, las acciones y las tareas así como un elenco de los valores que cristalizan en cada uno de ellos: un mapa completo de la variedad y riqueza de valores que se ponen en juego en el aprendizaje-servicio. Un resultado que, en los procesos de formación del profesorado, ayudará a tomar conciencia de la fuerza moral de esta metodología y a activarla durante su desempeño profesional.[eng] Despite the fact that the specialized bibliography recognizes service learning as a relevant methodology for values education, a sufficiently complete list of the plurality of values that it activates, is not yet available. The objective of this article is to build a reliable map of the values that service learning proposes. In order to achieve it, the levels of learning that overlap in a complex educational practice will be defined and then the values that works at each level of service-learning practices will be determined. To achieve this, a rational reconstruction work based on the reciprocal optimization achieved between a selection of good service-learning experiences and the theory of moral practices and service learning has been carried out. This methodology has allowed us to establish three simultaneous levels of learning —practice, actions and tasks— as well as a list of the values that crystallize in each of them: a complete map of the variety and richness of values that are put into play in service learning. A result that, in the processes of teacher training, will help to raise awareness of the moral strength of this methodology and to activate it during their professional performance

How to evaluate service learning projects?

El objetivo central de este artículo es presentar un instrumento para autoevaluar y mejorar las experiencias de aprendizaje servicio. Tras definir qué entendemos por aprendizaje servicio, ver algunos ejemplos y repasar los motivos que lo convierten en una propuesta pedagógica de alto valor, se presenta la arquitectura de una rúbrica pensada para facilitar la evaluación de las experiencias de aprendizaje servicio. Se describen sus dinamismos y los niveles de madurez de cada uno de ellos. El escrito termina proponiendo los principales pasos a recorrer para convertir la aplicación de la rúbrica en una oportunidad de reflexión y de mejora de las experiencias de aprendizaje servicio que llevan a cabo los equipos docentes

Improving the co and ch4 gas sensor response at room temperature of alpha-fe2o3(0001) epitaxial thin films grown on srtio3(111) incorporating au(111) islands

In this work, the functional character of complex -Fe2O3(0001)/SrTiO3(111) and Au(111) islands/ -Fe2O3(0001)/SrTiO3(111) heterostructures has been proven as gas sensors at room temperature. Epitaxial Au islands and -Fe2O3 thin film are grown by pulsed laser deposition on SrTiO3(111) substrates. Intrinsic parameters such as the composition, particle size and epitaxial character are investigated for their influence on the gas sensing response. Both Au and -Fe2O3 layer show an island-type growth with an average particle size of 40 and 62 nm, respectively. The epitaxial and incommensurate growth is evidenced, confirming a rotation of 30 between the in-plane crystallographic axes of -Fe2O3(0001) structure and those of SrTiO3(111) substrate and between the in-plane crystallographic axes of Au(111) and those of -Fe2O3(0001) structure. -Fe2O3 is the only phase of iron oxide identified before and after its functionalization with Au nanoparticles. In addition, its structural characteristics are also preserved after Au deposition, with minor changes at short-range order. Conductance measurements of Au(111)/ -Fe2O3(0001)/SrTiO3(111) system show that the incorporation of epitaxial Au islands on top of the -Fe2O3(0001) layer induces an enhancement of the gas-sensing activity of around 25% under CO and 35% under CH4 gas exposure, in comparison to a bare -Fe2O3(0001) layer grown on SrTiO3(111) substrates. In addition, the response of the heterostructures to CO gas exposure is around 5–10% higher than to CH4 gas in each case.This work has been supported by the Ministerio Español de Ciencia e Innovación (MICINN) and the Consejo Superior de Investigaciones Cientificas (CSIC) through the projects PIE-2010-OE-013- 200014, PIE 2021-60-E-030 and RTI2018-095303-A-C52. The ESRF, MICINN and CSIC are acknowledged for the provision of synchrotron radiation facilities. A.S. acknowledges financial support from Comunidad de Madrid for an “Atracción de Talento Investigador” Contract (2017-t2/IND5395)

Efficacy of a topical gel containing chitosan, chlorhexidine, allantoin and dexpanthenol for pain and inflammation control after third molar surgery : a randomized and placebo-controlled clinical trial

The aim of this study was to evaluate and compare the postoperative effect of a topic gel containing chlorhexidine, chitosan, allantoine and dexpanthenol versus a placebo for pain and inflammation control after third molar surgery. A gel combining 0.2% chlorhexdine, 0.5% chitosan, 5% dexpanthenol, 0.15% allantoin and 0.01% sodium saccharin was selected for this split mouth randomized controlled and double-blind trial including 36 patients with bilaterally and symmetrically impacted lower third molars. The teeth (n=72) were randomly divided into two groups before surgical removal: control group (CG; in which a placebo was given) and experimental group (EG). Swelling, trismus, postoperative pain, wound healing and complications were measured and recorded in order to evaluate differences between the placebo and experimental product. Five patients suffered from an alveolitis in the CG (13.9%), and none in the study group (0%), but no statistically significant difference was found (p=0.063). From day 0 to day 7, trismus and swelling were significantly less pronounced in the EG, and wound healing was considered ?good? in 22.2% for the CG and 97.2% for the EG (p<0.001). Mean VAS scores during the seven postoperative days were statistically lower in the study (2.56±1,19) compared to the placebo group (3.25±1.6) (p=0.002). The mean consumption of analgesic pills during the first 92 hours was also statistically lower in the EG (0.26±0.51) in comparison to the CG (0.56±0.67) (p=0.003). The use of an experimental gel containing chlorhexidine, chitosan, allantoine and dexpanthenol seems to significantly reduce postoperative pain, trismus and signs of inflammation. Future studies should further evaluate, if the gel is effective in dry socket preventing after third molar removal

Correlator implementation for orthogonal CSS used in an ultrasonic LPS

This paper presents a new architecture for the correlation of orthogonal complementary sets of sequences (OCSS) and their performance in an ultrasonic local positioning system (U-LPS). OCSS are sets of sequences whose addition of correlation functions has ideal properties, that makes interference-free code-division multiple access (CDMA) possible. They can be used to encode the signals emitted by a CDMA based U-LPS, enhancing the performance of such systems in terms of immunity against noise, multipath propagation, and near-far effect. Also, the orthogonality of the codes offers an operation resistance to multiaccess interference, which endows the U-LPS with the capability of simultaneous emission from different beacons. On the other hand, the detection of OCSS codes can be performed by means of efficient algorithms. This paper presents an optimization of previous proposals allowing the simultaneous correlation of OCSS by using fewer operations and memory elements. Furthermore, the hardware implementation of the proposed optimization is also addressed, and an U-LPS based on this proposal is presented.Fil: Peréz Rubio, M. Carmen. Universidad de Alcalá; EspañaFil: Sanz Serrano, Rebeca. Universidad de Alcalá; EspañaFil: Ureña Ureña, Jesús. Universidad de Alcalá; EspañaFil: Hernández Alonso, Álvaro. Universidad de Alcalá; EspañaFil: de Marziani, Carlos Manuel. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Álvarez Franco, Fernando J.. Universidad Nacional de la Patagonia "San Juan Bosco". Facultad de Ingeniería - Sede Comodoro; Argentin