The prediction of unsteady three-dimensional aerodynamics on wind turbine blades

After introducing the main features of the aerodynamics of wind turbines, a review of key theoretical studies and aerodynamic modelling methods provides the opportunity to focus on predictive methods and the main technical challenges associated with the aerodynamics of HAWTs. The basic aerodynamic method adopted in this study, a classic Blade Element Momentum theory model, BEM, is described next and its extension to yawed flow is detailed for completeness. Analysis then focuses on how stall delay due to three-dimensional effects can be predicted on a HAWT. Implementation of a semi-empirical stall delay model shows sensitivity to blade geometry but no dependency on wind velocity or rotational speed. This seems to be physically incorrect and suggests that a deeper understanding of 3-D effects is still needed if better algorithms are to be developed. The work then examines the onset of dynamic stall. A 2-D semi-empirical correlation of vortex stall onset, developed previously at Glasgow University, is implemented and validated through available field data from the NREL turbine Phases II and IV. The comparison of measured and predicted locations of dynamic stall onset highlights some interesting features of the three-dimensionality of the process; after the local inception, earlier dynamic stall appears to be triggered in adjacent stations. An attempt to study how 3-D stall delay interacts with the onset of dynamic stall, shows that stall delay appears not to influence the inception of dynamic stall in the way it does static stall. Moreover, the firsts signs of dynamic stall onset are generally best characterised by the correlation when it assumes locally 2-D flow. This is a significant result, as it demonstrates that the earliest signs of dynamic stall onset on wind turbines can be correctly predicted using 2-D tools. A closer examination of the discrepancies between the predictions and measurements has highlighted the particular aerodynamic characteristics of the S809 aerofoil, utilised as the blade section of the NREL turbines. The unusual stalling characteristics of this aerofoil bring into question the significance of the static stall angle in relation to dynamic stall. It is show that other features of the static behaviour may provide a more appropriate link to dynamic stall for some aerofoils. Finally, the phenomenon of tower shadow on a downwind turbine is studied. Unaveraged pressure measurements and integrated normal force coefficients from tests conducted at Glasgow University are analysed. The analysis highlights many interesting features of the tower shadow response. In particular, as the blade enters the tower shadow region, there is a rapid reduction in normal force due to the tower wake velocity deficit. As the blade leaves the tower shadow, the recovery is consistently slower and more progressive and apparently extends further than the edge of the velocity deficit region. These observations are then used in a examination of tower shadow modelling. A steady model, based on a cosine shaped velocity deficit is evaluated by comparison with the wind tunnel measurements. Unfortunately neither the phase nor the intensity of the response is adequately captured. This leads to the implementation of a new model, based on classic unsteady thin aerofoil theory that accounts for the aerofoil wake induced velocities. The unsteady model captures, in a satisfactory manner, the global response of the blade through the tower shadow region, with a negligible computational cost

CFD and aeroelastic analysis of the MEXICO wind turbine

This paper presents an aerodynamic and aeroelastic analysis of the MEXICO wind turbine, using the compressible HMB solver of Liverpool. The aeroelasticity of the blade, as well as the effect of a low-Mach scheme were studied for the zero-yaw 15m/s wind case and steady- state computations. The wake developed behind the rotor was also extracted and compared with the experimental data, using the compressible solver and a low-Mach scheme. It was found that the loads were not sensitive to the Mach number effects, although the low-Mach scheme improved the wake predictions. The sensitivity of the results to the blade structural properties was also highlighted

Los puentes hacia el empleo: las transiciones personales de los jóvenes en Sevilla

The changes experienced by young people during the transition into employment in Seville are examined. Particular atention is paid to subjectives trajectories. Important changes in the transition into adulthood and work values are observed. Less defined personal projects are frequent. Young people give more importance to leisure time. Individualistic attitudes coincide with the prolongation of the studies and the residence of young people at home, with their parents

Arto almidoian oinarritutako nanokonposite film eta hidrogelen garapena polisakarido eta grafenotik eratorritako nanoegiturak erabiliz

239 p.Doktorego tesi honen helburua almidoian oinarritutako materialen lorpena eta karakterizazioa izan da. Aplikazio desberdinetan erabiltzeko bi material mota garatu dira.: plastifikatutako almidoi film eta nanokonposite filmak paketatze aplikazioetan erabilitako ohiko polimero sintetikoen ordezkari bezala eta saretutako almidoi nanokonposite hidrogelal biomedikuntza aplikazioetarako. Horrela, plastifikatzaileak materialen amaierako propietateetan eta erretrogradazioan duen eragina aztertu da. Bestalde, nanokonposite filmak nanokristal polisakaridoak gehituta prestatu dira, almidoi eta zelulosa nanokristalak erabiliz hain zuzen. Horrez gain, estrusio/konpresio bidez almidoi termoplastiko filmak lortzeko bideragarritasuna ebaluatu da Bestalde, plastifikatutako almidoi nanokonposite filmak karbono nanopartikulak gehituta lortu dira. Grafeno eta grafeno oxido eduki desberdinak plastifikatutako almidoi matrizean gehitzeak duen eragina aztertu da. Nanokonposite hidrogelen sintesiari dagokionez, alde batetik, saretutako hidrogelak furano taldeaz eraldatutako almidoia eta tetramaleimida baten arteko Diels-Alder erreakzioaren bitartez lortu dira zelulosa nanokristalak gehituz. Zelulosa nanokristal edukiak hidrogelen propietate erreologiko, puzte gaitasuna, morfologia, botika askapen zinetika eta zelula itsaspen gaitasunean duen eragina aztertu da. Gainera, nanokonposite hidrogel antibakterial eta eroaleak lortu dira, grafenoa eta Salvia estraktuak egonkortzaile bezala erabiliz.GMT Materials + Technologies Research Grou

Vinsonen eta van Eysen arteko gutunak

The aim of this research is to complete the publication of letters written between two Bascologists in the 19th century so as to have an overall view of Bascology and ideas about language at that time. The selected collection consists of 103 letters exchanged between Julien Vinson and Willem Jan van Eys from 1868 to 1901. In general, Vinson’s perspectives on linguistics coincide with those of van Eys. For example, as regards the question of Basque-Iberism and the generalised nature of Basque grammar and verb structure. Nevertheless, there were some specific issues on which they disagreed. Moreover, the letters also reveal some disputes mainly between Vinson and other linguists and Bascologists at that time. To conclude, it is important to acknowledge their dedication to collecting and publishing old Basque texts. Throughout the letters, the collecting and preparing of those publications is widely mentioned; Lan honen helburua x i x. mendeko bi euskalariren arteko gutunak arakatuz horien edizioa osatzea da, garai hartako euskalaritza eta hizkuntza-ideien inguruan gutxi gorabeherako ikuspegi bat eduki ahal izateko. Hautatu dudan gutun-sorta 1868tik 1901era Julien Vinsonek eta Willem Jan van Eysek elkartrukatutako ehun eta hiru gutunek osatzen dute. Oro har, Vinsonen hizkuntzalaritza ikuspegiak van Eysenarekin bat egiten du, besteak beste eus-koiberismoaren auziari eta euskal gramatikaren eta aditz ereduaren orokortasunei dagokienez. Ala-baina, badira euren artean eztabaida sortzen duten gai zehatzagoak ere. Gainera, gutunetan batez ere Vinsonek garaiko hizkuntzalari nahiz euskalariekin izandako au-rrez aurrekoak ere azaleratzen dira Amaitzeko, ezin alde batera utzi batak zein besteak euskal testu zaharren bilketa eta edizioan eginiko lanak. Gutunetan zehar aipamen ugari jasotzen dituzte edizioen bilketa eta prestaketa lanek

Control robusto basado en modelo de referencia de convertidores multinivel. Aplicación a filtros activos en conexión paralelo para corrección de armónicos en redes eléctricas de media tensión

En esta Tesis se presentan dos aportaciones novedosas principales. La primera es la propuesta del control Robusto basado en modelo de referencia (RMF) para regular las corrientes de salida y la tensión del Bus DC de un convertidor NPC de tres niveles, trabajando como Filtro Activo Paralelo (FAP) en redes de media tensión. La segunda aportación importante de la tesis es el desarrollo de nuevos modelos de pequeña señal del convertidor NPC-FAP de tres niveles, que permiten diseñar con mayor precisión tanto los reguladores de corriente como los reguladores de tensión de Bus de continua (DC) del convertidor. Se ha propuesto una metodología de modelado de convertidores trifásicos en el sistema de referencia síncrono dq0, y se han desarrollado los modelos de pequeña y gran señal del convertidor NPC de tres niveles, para una aplicación de filtro activo paralelo a tres hilos. Se han obtenido las funciones de transferencia necesarias para el control lineal del convertidor, deduciendo las funciones de transferencia necesarias para el control de la corriente inyectada por el filtro y de la tensión de Bus DC del convertidor. Se ha realizado un estudio de nuevas alternativas para el control de las corrientes del FAP y de la tensión del Bus DC. Tras analizar el control convencional PI, se propone un nuevo control robusto RMF, aplicando ambos controles tanto a la regulación de armónicos de corriente como al control de la tensión de Bus DC. Se analiza también un "controlador resonante" basado en Integradores Generalizados (PIS) aplicado al control de corriente del convertidor. En todos los casos se desarrolla una metodología de diseño de los controladores, tanto en tiempo continuo como en tiempo discreto, y se lleva a cabo un análisis comparativo entre los distintos reguladores propuestos, tanto de corriente como de tensión. Se llega a la conclusión de que la mejor opción para el lazo de corriente es el controlador PIS, mientras que el controlador RMF es el óptimo para el lazoMunduate Tellería, A. (2007). Control robusto basado en modelo de referencia de convertidores multinivel. Aplicación a filtros activos en conexión paralelo para corrección de armónicos en redes eléctricas de media tensión [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/1942Palanci

Arto almidoian oinarritutako nanokonposite film eta hidrogelen garapena polisakarido eta grafenotik eratorritako nanoegiturak erabiliz

239 p.Doktorego tesi honen helburua almidoian oinarritutako materialen lorpena eta karakterizazioa izan da. Aplikazio desberdinetan erabiltzeko bi material mota garatu dira.: plastifikatutako almidoi film eta nanokonposite filmak paketatze aplikazioetan erabilitako ohiko polimero sintetikoen ordezkari bezala eta saretutako almidoi nanokonposite hidrogelal biomedikuntza aplikazioetarako. Horrela, plastifikatzaileak materialen amaierako propietateetan eta erretrogradazioan duen eragina aztertu da. Bestalde, nanokonposite filmak nanokristal polisakaridoak gehituta prestatu dira, almidoi eta zelulosa nanokristalak erabiliz hain zuzen. Horrez gain, estrusio/konpresio bidez almidoi termoplastiko filmak lortzeko bideragarritasuna ebaluatu da Bestalde, plastifikatutako almidoi nanokonposite filmak karbono nanopartikulak gehituta lortu dira. Grafeno eta grafeno oxido eduki desberdinak plastifikatutako almidoi matrizean gehitzeak duen eragina aztertu da. Nanokonposite hidrogelen sintesiari dagokionez, alde batetik, saretutako hidrogelak furano taldeaz eraldatutako almidoia eta tetramaleimida baten arteko Diels-Alder erreakzioaren bitartez lortu dira zelulosa nanokristalak gehituz. Zelulosa nanokristal edukiak hidrogelen propietate erreologiko, puzte gaitasuna, morfologia, botika askapen zinetika eta zelula itsaspen gaitasunean duen eragina aztertu da. Gainera, nanokonposite hidrogel antibakterial eta eroaleak lortu dira, grafenoa eta Salvia estraktuak egonkortzaile bezala erabiliz.GMT Materials + Technologies Research Grou

Increasing integrative negotiation in European organizations through trustworthiness and trust

Integrative negotiation in which employers and employees create value is a major necessity in the current challenging context. Collective labor negotiations in organizations are traditionally focused on mostly distributive issues, such as pay, working hours, and holidays. However, the current situation demands the inclusion of other issues of a potentially more integrative nature, such as telework, sustainability, and risk prevention, the enhancement of which is a major challenge for organizations. In this study, we explore the negotiation process between management and employee representatives (ERs), analyzing the roles of trust and trustworthiness. We collected data from 614 human resources managers from different organizations in 11 European countries. The results confirm that ERs who management perceive to be trustworthy have a greater influence on negotiation, particularly with regard to integrative as opposed to distributive issues, and that trust partially mediates this relationship

Discriminatory language in the workplace: unmasking prejudices and stereotypes

The link between language, communication and open discrimination has been the focus of numerous studies. For many years, language has been a vehicle of prejudice and negative stereotypes. However, in the last few years, overt verbal aggressions have diminished thanks to the implementation of equality policies and awareness-raising initiatives. Despite that, negative attitudes against protected groups might not have disappeared and may instead be transmitted subtly, such as through uncivil language. The goal of this research is to study the relation between language and subtle discrimination against lesbian and gay (LG) workers. With this goal in mind, 39 in-depth interviews were conducted. The analysis showed that LG people are victims of subtle discrimination and that language is one of the most common vehicles of prejudice and negative stereotypes. Jokes, inappropriate comments and questions are the expression of negative attitudes, which are probably present at an implicit level. Due to the ambiguity of these expressions and the settings where they have been studied — the workplace — these acts could be defined as uncivil behaviours. Practical implications, limitations and directions for future research are discussed.info:eu-repo/semantics/acceptedVersio

La gestión de conflictos organizacionales por medios extrajudiciales

En este artículo los autores analizan diferentes aspectos de la solución de conflictos organizacionales a través de medios extrajudiciales. Así, comienzan destacando la importancia y el interés creciente de los medios de solución extrajudicial de conflictos a nivel europeo; a continuación se centran en la evolución desarrollada en España, presentando un modelo contrastado de mediación en el ámbito de las relaciones laborales: el Sistema Extrajudicial de Resolución de Conflictos Laborales de Andalucía (SERCLA). Los autores también destacan la importancia de las intervenciones de mediación, a veces informales, que se realizan dentro de las propias organizaciones, enfatizando la mediación como herramienta de carácter preventivo. Otros aspecto que se considera es la importancia de las estrategias empleadas en la mediación (estrategias reflexivas, substantivas y contextuales) y su efectividad. Por último, los autores plantean algunos de los beneficios derivados de la mediaciónThis article examines different aspects of organizational conflict management by non-judicial means. The authors begin emphasizing the crescent importance and interest of the non-judicial means of conflict resolution at a European level. Next, based on the evolution of the topic in Spain, they present a contrasted model of mediation in labor relation settings: The Extrajudicial System for Labour Conflict Resolution in Andalusia (SERCLA). The authors also point out the importance of mediation interventions, some times informal, which are made within the organizations, emphasizing mediation as a preventive tool. Another aspect considered in this article is the importance of the strategies used in mediation (contextual, substantive and reflexive strategies) and its efficiency. Finally, the authors comment on some benefits produced from mediatio