In this thesis we used atomic force microscopy (AFM) to investigate systematically the behaviour of both electrostatically stabilised silica and sterically stabilised polystyrene (PS) colloidal systems on freshly cleaved mica substrates. For the silica colloidal nanoparticles we explored the effect of colloidal suspension concentration, particle size, and different application techniques on both the adsorption behaviour and subsequent structuring of the particles. For the PS colloidal nanoparticles we explored concentration effects and experimented with both dip-coating and droplet application techniques. We showed that silica nanoparticles adsorbed onto mica via irreversible adsorption that possessed lateral mobility due to the weak attraction between the nanoparticles and the substrate, facilitating subsequent capillary structuring of the nanoparticles during drying. We associated the effects of volume fraction with Debye screening, and kinetics effects with particle size and volume fraction. We also successfully imaged a partially dried film and showed the role of convective/capillary forces in the structuring of the nanoparticles. Studies with variations in particle size generated a number of different topography structures; with dewetting phenomena observed for 10 nm nanoparticles and the formation of crystalline structures for 100 nm nanoparticles. Spin coating techniques were used to produce even larger crystalline structures of nanoparticles. Size dependent ordering occurred for low concentration samples due to the polydispersity of the colloidal suspension. We showed that acceleration can affect interparticle spacing. We also studied the role of rotational speed on the crystallinity of the particle configurations and showed how fine tuning of rotational speed can generate large scale monolayer crystalline formations of nanoparticles.

Inúmeras são as vantagens da utilização de instrumentos rotatórios de níquel-titânio no preparo químico-cirúrgico, como por exemplo, melhor modelagem dos canais curvos e uma diminuição significativa no tempo de trabalho. Todavia, a maior preocupação no uso desses instrumentos tem sido a sua fratura, principalmente, por sua ocorrência estar ligada a diferentes fatores. O objetivo do presente estudo foi avaliar a influência da velocidade de rotação e do número de usos, no tempo de trabalho e na ocorrência de fraturas de instrumentos de dois sistemas rotatórios de níquel-titânio (K3 e RaCe), em canais simulados com mesmo ângulo de curvatura. Foram avaliados os instrumentos 25/.04 dos dois sistemas nas velocidades de 180, 350, 600 rpm ao instrumentarem 5 mm referentes à curvatura dos canais simulados. Para cada velocidade foram utilizadas limas com 1, 2 e 3 usos. Um contra-ângulo foi adaptado a um dispositivo calibrado para realizar movimentos padronizados de penetração nos canais simulados. Foram mensurados: o tempo necessário para instrumentar a curvatura do canal e a quantidade de fraturas ocorridas. Os resultados obtidos foram submetidos a ANOVA sendo em seguida empregado o teste de Tukey (&#945;=5%). Sob as condições desse experimento, o aumento da velocidade diminuiu o tempo de instrumentação em ambos os sistemas. Os instrumentos RaCe prepararam o canal em menor tempo do que os instrumentos K3 nas velocidades de 350 e 600 rpm (p<0,05), não havendo diferença em 180 rpm (p>0,05). Ocorreu maior número de instrumentos fraturados nas velocidades de 180 e 600 rpm para o sistema RaCe e de 600 rpm para o K3, e nenhuma fratura na velocidade de 350 rpm para ambos. O número de usos não influenciou o tempo de trabalho para nenhum sistema (p>0,05), porém, o número de fraturas aumentou proporcionalmente ao aumento do número de usos, exceto na velocidade de 350 rpm na qual não ocorreram fraturas. Os instrumentos RaCe apresentaram maior índice de fratura para a velocidade de 180 rpm (30%) do que para 600 rpm (13,33%). A velocidade de 350 rpm foi a mais segura para os instrumentos de ambos os sistemas. / Use of nickel-titanium rotary instruments has many advantages like better shaping of curved canals and lower working time. However, instrument fracture has always been a serious concern in root canal treatment because it involves a lot of factors. The aim of this study was to evaluate the influence of rotational speed and number of uses on the preparation time and incidence of fractures of K3 and RaCe instruments, using simulated root canals with the same angle of curvature. Nickel-titanium 25/.04- tapered instruments of both rotary systems were tested at 180, 350 and 600 rpm during shaping of 5 mm curvature’s extent. The files were used 3 times in each rotational speed. A contra-angle electric handpiece was mounted on a machine that was calibrated to deliver a constant penetration movement. Working time and incidence of fractures were measured. The results were analyzed statistically using a one-way analysis of variance with a post-hoc Tukey test (&#945;=5%). Under the conditions of this study, higher rotational speeds reduced preparation time for both rotary systems. RaCe instruments showed lower preparation time than K3 instruments at 350 and 600 rpm (p<0,05). There was no significant difference at 180 rpm (p>0,05). There was a higher incidence of fractures at 180 and 600 rpm for RaCe instruments and at 600 rpm for K3 instruments. No file breakage occurred at 350 rpm for both instruments. Preparation time was not influenced significantly by the frequency that the files were used (p>0,05). Incidence of fractures increased with an increase in the number of file usage, unless at 350 rpm in which none of the files fractured. At 180 rpm, RaCe instruments showed a higher incidence of breakage than at 600 rpm. Rotational speed of 350 rpm was the safest for both kind of instruments tested in this study.

Inúmeras são as vantagens da utilização de instrumentos rotatórios de níquel-titânio no preparo químico-cirúrgico, como por exemplo, melhor modelagem dos canais curvos e uma diminuição significativa no tempo de trabalho. Todavia, a maior preocupação no uso desses instrumentos tem sido a sua fratura, principalmente, por sua ocorrência estar ligada a diferentes fatores. O objetivo do presente estudo foi avaliar a influência da velocidade de rotação e do número de usos, no tempo de trabalho e na ocorrência de fraturas de instrumentos de dois sistemas rotatórios de níquel-titânio (K3 e RaCe), em canais simulados com mesmo ângulo de curvatura. Foram avaliados os instrumentos 25/.04 dos dois sistemas nas velocidades de 180, 350, 600 rpm ao instrumentarem 5 mm referentes à curvatura dos canais simulados. Para cada velocidade foram utilizadas limas com 1, 2 e 3 usos. Um contra-ângulo foi adaptado a um dispositivo calibrado para realizar movimentos padronizados de penetração nos canais simulados. Foram mensurados: o tempo necessário para instrumentar a curvatura do canal e a quantidade de fraturas ocorridas. Os resultados obtidos foram submetidos a ANOVA sendo em seguida empregado o teste de Tukey (&#945;=5%). Sob as condições desse experimento, o aumento da velocidade diminuiu o tempo de instrumentação em ambos os sistemas. Os instrumentos RaCe prepararam o canal em menor tempo do que os instrumentos K3 nas velocidades de 350 e 600 rpm (p<0,05), não havendo diferença em 180 rpm (p>0,05). Ocorreu maior número de instrumentos fraturados nas velocidades de 180 e 600 rpm para o sistema RaCe e de 600 rpm para o K3, e nenhuma fratura na velocidade de 350 rpm para ambos. O número de usos não influenciou o tempo de trabalho para nenhum sistema (p>0,05), porém, o número de fraturas aumentou proporcionalmente ao aumento do número de usos, exceto na velocidade de 350 rpm na qual não ocorreram fraturas. Os instrumentos RaCe apresentaram maior índice de fratura para a velocidade de 180 rpm (30%) do que para 600 rpm (13,33%). A velocidade de 350 rpm foi a mais segura para os instrumentos de ambos os sistemas. / Use of nickel-titanium rotary instruments has many advantages like better shaping of curved canals and lower working time. However, instrument fracture has always been a serious concern in root canal treatment because it involves a lot of factors. The aim of this study was to evaluate the influence of rotational speed and number of uses on the preparation time and incidence of fractures of K3 and RaCe instruments, using simulated root canals with the same angle of curvature. Nickel-titanium 25/.04- tapered instruments of both rotary systems were tested at 180, 350 and 600 rpm during shaping of 5 mm curvature’s extent. The files were used 3 times in each rotational speed. A contra-angle electric handpiece was mounted on a machine that was calibrated to deliver a constant penetration movement. Working time and incidence of fractures were measured. The results were analyzed statistically using a one-way analysis of variance with a post-hoc Tukey test (&#945;=5%). Under the conditions of this study, higher rotational speeds reduced preparation time for both rotary systems. RaCe instruments showed lower preparation time than K3 instruments at 350 and 600 rpm (p<0,05). There was no significant difference at 180 rpm (p>0,05). There was a higher incidence of fractures at 180 and 600 rpm for RaCe instruments and at 600 rpm for K3 instruments. No file breakage occurred at 350 rpm for both instruments. Preparation time was not influenced significantly by the frequency that the files were used (p>0,05). Incidence of fractures increased with an increase in the number of file usage, unless at 350 rpm in which none of the files fractured. At 180 rpm, RaCe instruments showed a higher incidence of breakage than at 600 rpm. Rotational speed of 350 rpm was the safest for both kind of instruments tested in this study.

In order to investigate the viability of friction stir welding for use in Naval construction, mode one elastic-plastic fracture toughness of friction stir processed HSLA-65 was determined using current ASTM 1820 and BS 7448 standards. Double-sided welds were used to achieve 12.7 mm thick samples. A constant feed rate of 100 mm/min was used for all welds. To explore the effect of weld parameters on toughness, welds were produced using two rotational speeds: 340 RPM and 490 RPM. The weld centerline, advancing side hardened region (ASHR), and TMAZ/HAZ regions were sampled, in addition to un-welded parent material. All elastic-plastic fracture toughness values were thickness dependent. For welds produced at 340 RPM, toughness ranged from 33% to 75% below parent material. By increasing the rotational speed to 490 RPM, weld toughness was likewise less than the parent material, but increased 12% to 50% relative to welds produced at 340 RPM. The lowest measured toughness was in the ASHR samples for both parameters. This region of the weld exhibited mixed mode stress-strain conditions and toughness 75% and 62% less than parent material. Toughness values for all samples failed to meet qualification requirements of both ASTM 1820 and BS 7448 due to non-uniform crack extension. Irregular crack extension was caused by the through thickness change in tensile properties due to welding and the affect this had on the plastic zone size compared to the thickness. Increased weld toughness from 340 RPM to 490 RPM was attributed to microstructural differences as a result of increased rotational speed. In addition, higher crack extensions were observed in the second weld pass relative to the first for both rotational speeds. This was attributed to weld tempering of the first pass by the second. The ASHR samples exhibited the highest crack extensions. In this location, the weld microstructure consisted of Widmanstatten ferrite, a microstructure known to be detrimental to toughness.

Die Dissertation befasst sich grundlegend mit der Herausforderung der Trennung der Drehzahl der primären Antriebsquelle und der Drehzahl des Arbeitswerkzeugs. Nach einer Analyse der verfügbaren Technologien wird ein neues System entwickelt. Der Konzeptentwicklung schließt sich eine eingehende analytische Betrachtung an. Durch Simulationsrechnungen werden die Leistungsfähigkeit und Effizienz hervorgehoben. Mit Hilfe einer Nutzwertanalyse erfolgt schließlich eine Auswahl des finalen Systems, welches zum Abschluss in die Realisierung geht. Die Arbeit schließt mit ersten Ergebnissen des in Hardware aufgebauten Systems.

This diploma thesis implements methods for a measurement of rotational speed. It is implemented on the Compact RIO platform from National Instruments. Corresponding SW is implemented using the graphical programming language G in LabView environment. Developed system uses two different sensors – incremental encoder and tacho sensor for measurements of rotational speed. Thesis further analysis and implements a method for an encoder nonlinearity determination and for its on-line correction. For used methods, effects adding errors into the measurements are evaluated and quantified.

Tesis por compendio / [ES] La disponibilidad de recursos hídricos a nivel mundial ha disminuido significativamente. Entre los principales agentes que han provocado esta situación se encuentran el cambio climático, la contaminación ambiental, las actividades humanas y las fallas en las estructuras hidráulicas, entre otros. Cada vez es más complicado acceder a fuentes apropiadas que cumplan con la calidad y cantidad del recurso. A pesar de ello, la pérdida de agua debida a fugas en sistemas de distribución presurizados todavía maneja valores considerables, con pérdidas significativas a nivel mundial. Teniendo en cuenta que la necesidad de agua es cada vez mayor, se deben implementar proyectos sostenibles que permitan optimizar al máximo la disponibilidad y el uso del recurso. El objetivo principal de esta tesis es desarrollar una propuesta metodológica, que permita estimar las curvas características de las bombas que trabajan como turbinas (PATs) a partir del número específico de la máquina y en función de la velocidad de giro, desarrollando las leyes modificadas de semejanza. El cumplimiento de los objetivos de esta tesis es a través de la elaboración de tres artículos publicados, que permitieron: (i) Realizar la contextualización respecto al estado del arte en PATs con énfasis en las metodologías de obtención de la predicción del comportamiento en las mismas tales como la realización de modelos numéricos con CFDs; (ii) Proponer una nueva estrategia para desarrollar un modelo matemático para bombas que funcionan como turbinas (PATs), considerando las leyes de afinidad modificadas; (iii) Ejecutar la modelación numérica a través del paquete de código libre OpenFOAM de una bomba que trabaja como turbina y , (iv)Validar los resultados , tanto de la aplicación de las nuevas expresiones y de la modelación numérica, a través de la comparación con resultados experimentales obtenidos de los ensayos realizados a una PATs. En el Articulo 1, que corresponde a la Fase de Contextualización, se realizó una investigación en la literatura técnica sobre PATs: Características, aplicaciones y diferentes estrategias utilizadas para comprender el comportamiento del flujo. Dentro de estas estrategias, se encuentra la simulación numérica del fenómeno con paquetes CFD (Dinámica Fluido Computacional). Se analizaron 56 casos donde se estudian diferentes tipos de máquinas: axiales, mixtas y radiales bajo operación con velocidad de giro fija y velocidad de giro variable. En función de esta información se calculó el error entre la modelación numérica y los resultados experimentales; y se verificaron las principales características de las modelaciones tales como paquete CFD utilizado, modelos de cierre, tipo de mallado, etc. En el Artículo 2, que corresponde a la primera parte de la Fase del Procedimiento Analítico, se propuso un análisis con diez expresiones generales (polinómicas y exponenciales), considerando las variables más significativas. En función de este análisis se obtuvieron nuevas expresiones para obtener las curvas características de las PATs. Estas expresiones se verificaron y compararon con 15 máquinas diferentes, que se probaron variando su velocidad de rotación y su velocidad específica. En la segunda parte de la Fase del Procedimiento Analítico, se realizó una simulación numérica con el paquete CFD OpenFOAM de una PATs que ha sido ensayada en el instituto CERIS de Portugal. Por medio de los resultados experimentales se logró validar tanto las nuevas expresiones propuestas en el Artículo 2 así como la modelación numérica. En el Artículo 3 se presenta el desarrollo de esta metodología. / [CA] La disponibilitat de recursos hídrics a nivell mundial ha disminuït significativament. Entre els principals agents que han provocat aquesta situació es troben el canvi climàtic, la contaminació ambiental, les activitats humanes i les falles en les estructures hidràuliques, entre altres. Cada vegada és més complicat accedir a fonts apropiades que complisquen amb la qualitat i quantitat del recurs. Malgrat això, la pèrdua d'aigua deguda a fugides en sistemes de distribució pressuritzats encara maneja valors considerables, amb pèrdues significatives a nivell mundial. Tenint en compte que la necessitat d'aigua és cada vegada major, s'han d'implementar projectes sostenibles que permeten optimitzar al màxim la disponibilitat i l'ús del recurs. L'objectiu principal d'aquesta tesi és desenvolupar una proposta metodològica, que permeta estimar les corbes característiques de les bombes que treballen com a turbines (PATs) a partir del número específic de la màquina i en funció de la velocitat de gir, desenvolupant les lleis modificades de semblança. El compliment dels objectius d'aquesta tesi és a través de l'elaboració de tres articles publicats, que van permetre: (i) Realitzar la contextualització respecte a l'estat de l'art en PATs amb èmfasi en les metodologies d'obtenció de la predicció del comportament en les mateixes com ara la realització de models numèrics amb CFDs; (ii) Proposar una nova estratègia per a desenvolupar un model matemàtic per a bombes que funcionen com a turbines (PATs), considerant les lleis d'afinitat modificades; (iii) Executar el modelatge numèric a través del paquet de codi lliure OpenFOAM d'una bomba que treballa com a turbina i , (iv)Validar els resultats , tant de l'aplicació de les noves expressions i del modelatge numèric, a través de la comparació amb resultats experimentals obtinguts dels assajos realitzats a una PATs. En l'Articule 1 , que correspon a la Fase de Contextualització, es va realitzar una investigació en la literatura tècnica sobre PATs: Característiques, aplicacions i diferents estratègies utilitzades per a comprendre el comportament del flux. Dins d'aquestes estratègies, es troba la simulació numèrica del fenomen amb paquets CFD (Dinàmica Fluid Computacional). Es van analitzar 56 casos on s'estudien diferents tipus de màquines: axials, mixtes i radials sota operació amb velocitat de gir fixa i velocitat de gir variable. En funció d'aquesta informació es va calcular l'error entre el modelatge numèric i els resultats experimentals; i es van verificar les principals característiques. dels modelatges com ara paquet CFD utilitzat, models de tancament,tipus d'emmallat, etc. En l'Article 2, que correspon a la primera part de la Fase del Procediment Analític, es va proposar una anàlisi amb deu expressions generals (polinòmiques i exponencials), considerant les variables més significatives. En funció d'aquesta anàlisi es van obtindre noves expressions per a obtindre les corbes característiques de les PATs. Aquestes expressions es van verificar i van comparar amb 15 màquines diferents, que es van provar variant la seua velocitat de rotació i la seua velocitat específica. En la segona part de la Fase del Procediment Analític, es va realitzar una simulació numèrica amb el paquet CFD OpenFOAM d'una PATs que ha sigut assajada en l'institut CERIS de Portugal. Per mitjà dels resultats experimentals es va aconseguir validar tant les noves expressions proposades en l'Article 2 així com el modelatge numèric. En l'Article 3 es presenta el desenvolupament d'aquesta metodologia. / [EN] The availability of water resources worldwide has decreased significantly. Among the main agents that have caused this situation are climate change, environmental pollution, human activities, and failures in hydraulic structures, among others. It is becoming increasingly difficult to access appropriate sources that meet the quality and quantity of the resource. Despite this, water loss due to leaks in pressurized distribution systems still manages considerable values, with significant losses worldwide. Considering that the need for water is increasing, sustainable projects should be implemented to optimize the availability and use of the resource to the maximum. The main objective of this thesis is to develop a methodological proposal that allows estimating the characteristic curves of pumps that work as turbines (PATs) from the specific number of the machine and, depending on the rotation speed, developing the modified laws of similarity. The fulfillment of the objectives of this thesis is through the elaboration of three published articles, which allowed: (i) To carry out the contextualization regarding the state of the art in PATs with emphasis on the methodologies of obtaining the prediction of the behavior in them such as the realization of numerical models with CFDs; (ii) To propose a new strategy to develop a mathematical model for pumps that work as turbines (PATs), considering the modified affinity laws; (iii) To execute the numerical modeling through the OpenFOAM free code package of a pump that works as a turbine and, (iv) Validate the results, both of the application of the new expressions and the numerical modeling, through the comparison with experimental results obtained from the tests carried out to a PATs. In Article 1, corresponding to the Contextualization Phase, an investigation was carried out in the technical literature on PATs: Characteristics, applications, and different strategies used to understand the flow behavior. The numerical simulation of the phenomenon with CFD (Computational Fluid Dynamics) packages is found within these strategies. 56 cases were analyzed where different types of machines were studied: axial, mixed, and radial under operation with fixed rotational speed and variable rotational speed. Based on this information, the error between the numerical modeling and the experimental results was calculated; and the main characteristics of the modeling were verified, such as the CFD package used, closure models, type of meshing, etc. In Article 2, which corresponds to the first part of the Phase of the Analytical Procedure, an analysis was proposed with ten general expressions (polynomial and exponential), considering the most significant variables. Based on this analysis, new expressions were obtained to obtain the characteristic curves of the PATs. These expressions were verified and compared with 15 different machines, which were tested by varying their rotation and specific speeds. In the second part of the Analytical Procedure Phase, a numerical simulation was performed with the OpenFOAM CFD package of a PATs that has been tested at the CERIS Institute in Portugal. The experimental results made it possible to validate both the new expressions proposed in Article 2 and the numerical modeling. The development of this methodology is presented in Article 3. / Plua Aguirre, FA. (2024). Metodología de análisis para la mejora de la predicción de las curvas características de bombas trabajando como turbina operando a velocidad variable [Tesis doctoral]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/203125 / Compendio

Ce travail de recherche s'inscrit dans le cadre de la surveillance des machines tournantes en régime non stationnaire et plus particulièrement la détection des défauts de roulement. Il se focalise sur la modélisation et l'analyse des variations de la vitesse de rotation instantanée. Les modèles numériques développés s'appuient sur une approche originale dite " angulaire " qui introduit explicitement les degrés de rotation libres de la machine et permet de s'affranchir de condition de fonctionnement en régime stationnaire. Un modèle de roulement à billes à gorge profonde a été développé couplant les efforts de contact normaux et tangentiels grâce à l'introduction du phénomène de résistance au roulement. Ce couplage permet d'expliquer l'origine des fluctuations de vitesse de rotation en présence de défaut de bague extérieure, phénomènes constatés expérimentalement : la présence d'un défaut sur une bague modifie périodiquement le couple de frottement. La modélisation de la liaison par engrenages est plus classique, la problématique a été de s'assurer qu'elle était compatible avec l'approche angulaire utilisée dans ces travaux. Le couplage des éléments de roulement et d'engrenage dans un modèle simple a montré que la présence de défauts de roulement provoque des variations des efforts radiaux ce qui modifie les efforts d'engrènement et en conséquence perturbe également la vitesse de rotation. Un modèle simplifié d'une éolienne a été réalisé et utilisé pour tester et valider des indicateurs spectraux de surveillance en conditions de fonctionnement non stationnaires. La comparaison avec des mesures expérimentales issues d'une éolienne a montré la robustesse du modèle. Il peut donc être exploité comme un outil d'analyse phénoménologique et de test d'indicateurs de surveillance. Il a par exemple permis de montrer l'importance des conditions de fonctionnement (charge et vitesse) sur le niveau des indicateurs utilisés en surveillance. Si besoin, les développements proposés peuvent être étendus sans difficulté à des modèles plus complexes de roulements, d'engrènements et de structures d'accueil de ces éléments technologiques. / This work has been developed within the framework of non-stationary rotating machinery surveillance with emphasis on the detection of roller bearing defects. It focuses on the modeling and analysis of instantaneous angular speed variations. The numerical models developed are based on an ``angular" approach which introduces explicitly the machine's free body rotation degrees of freedom allowing simulations in non stationary operating conditions. A deep groove ball bearing model has been developed coupling tangential and normal forces by taking into account the rolling resistance phenomenon. This coupling allows to explain the origin of angular speed fluctuations in the presence of outer race roller bearing defects, phenomena that has been observed experimentally: a roller bearing defect periodically modifies the friction torque. The description of the gear mesh has been performed by means of a classic approach where the scientific issue has been to verify the compatibility with the angular modeling, cornerstone of this dissertation. Integration of the roller bearing and the gear modeling approaches into a simple mechanical architecture has shown that the presence of bearing defects provoking variations in the rolling element-races normal forces, modifies the gear mesh forces leading to perturbations of the angular speed. A simplified wind turbine model has been used for the test and validation of non stationary surveillance spectral indicators. The robustness of the model has been shown by means of a comparison with measurements performed on a wind turbine. It has allowed to show the importance of the operating conditions (load and speed), on the level of indicators used. This means the model may be used as a tool for phenomenological analyses as well as a device to test surveillance indicators. If needed, the approaches presented may be easily extended into more complex models of bearings, gears, casings and foundations.