The objectives of this work are to review, investigate and model the microwave planar filters of the modern wireless communication system. The recent main stream of microwave filters are classified and discussed separately. Various microwave filters with detailed applications are investigated in terms of their geometrical structures and operational performances. A comprehensive theoretical study of microwave filters is presented. The main types of microwave filters including the basic low-pass filters such as Butterworth and Chebyshev filters are fully analysed and described in detail. The transformation from low-pass prototype filters to high-pass filters, band-pass filters and band-stop filters are illustrated and introduced. Research work on stepped impedance resonator (SIR) and asymmetric stepped impedance resonator (ASIR) structure is presented. The characteristics of λg/4, λg/2 and λg (λg is the guided wavelength of the fundamental frequency in the free space) type SIR resonators, and the characteristic of asymmetric SIR resonator are categorized and investigated. Based on the content mentioned above, novel multi-standard high performance asymmetric stepped impedance resonator single-wideband and dual-wideband filters with wide stopbands are proposed. The methodologies to realize wide passband and wide stop-band filters are detailed. In addition, multi-standard high performance triplewideband, quadruple-wideband and quint-wideband filters are suggested and studied. The measurement results for all prototype filters agree well with the theoretical predictions and simulated results from Ansoft HFSS software. The featured broad bandwidths over single/multiple applicable frequency bands and the high performances of the proposed filters make them very promising for applications in future multistandard wireless communication.

En un análisis sísmico tradicional, se considera principalmente la existencia de fuerzas sísmicas que actúan unidireccionalmente en dos o tres direcciones independientes. Sin embargo, se ha demostrado que la naturaleza del movimiento sísmico es errática, es decir, que las acciones sísmicas actúan en diferentes direcciones hacia la estructura. En el presente estudio, se analizó las respuestas de 4 modelos estructurales con una geometría arquitectónica escalonada usando un Análisis Modal Espectral (AME) y un Análisis Lineal Tiempo Historia (ALTH), con ángulos de incidencia con incrementos cada 10°, de manera que se evidencie los efectos de la bidireccionalidad sísmica frente al unidireccional a través de las respuestas máximas de los modelos. Para el ALTH, se consideraron 3 registros sísmicos ocurridos en Lima-Perú en un tipo de suelo rígido obtenidos a través de la red acelerográfica nacional peruana CISMID. Los resultados alcanzados muestran que, para el Análisis Modal Espectral (AME) el ángulo de incidencia mayor donde se presentan mayores repuestas es 45° para los 4 modelos, y para el ALTH los ángulos de incidencia son variables. Asimismo, en ambos análisis dinámicos, evaluando la bidireccionalidad sísmica se obtienen respuestas de 10 a 40% más que un análisis unidireccional. / In a traditional seismic analysis, it is mainly considered the existence of seismic forces that work unidirectionally in two or three independent directions. However, it has been demonstrated that the nature of the seismic movement is erratic, that is to say, that the seismic actions act in different directions towards the structure. In the present study, the responses of 4 structural models with a staggered architectural geometry were analyzed using a Spectral Modal Analysis (SMA) and a Linear Time History Analysis (ALTH), with incidence angles increased every 10°, so as to evidence the effects of the seismic bidirectionality against the unidirectional one through the maximum responses of the models. For the ALTH, 3 seismic records were considered, which occurred in Lima-Peru in a type of rigid soil obtained through the Peruvian national accelerographic network CISMID. The results achieved show that, for the Spectral Modal Analysis (SMA), the incidence angle where the greatest responses are presented is 45° for the 4 models, and for the ALTH the incidence angles are variable. Moreover, in both dynamic analyses, evaluating the seismic bidirectionality, responses are obtained from 10 to 40% more than a unidirectional analysis. / Trabajo de investigación

<div>The design of bridges prior to 1994 was carried out by either the Load Factor Design (LFD) or the Allowable Stress Design (ASD) methodologies. Load rating of these bridges was primarily conducted by Load Factor Rating (LFR). In 1994, the American Association of State Highway and Transportation Officials (AASHTO) developed and encouraged the use of a probabilistic-based method titled Load and Resistance Factor Design (LRFD) for carrying out bridge design. A new methodology consistent with LRFD was also developed and adopted for conducting load rating. Thus, a new Load and Resistance Factor Rating (LRFR) was adopted by AASHTO in 2001 for load rating. Today, the bridges that were designed by the old LFD methodology are rated by both LFR and LRFR. Continued development suggests that load rating in future will be based only on LRFR, therefore LRFR is the recommended method for carrying out load rating of bridges even if they were designed by LFD. </div><div><br></div><div>The Indiana Department of Transportation (INDOT) came across some LFD designed bridges which were adequate by LFR methodology, i.e., produced a rating factor of more than 1.0, but inadequate for LRFR. The load ratings were carried out using AASHTOWare Bridge Rating (BrR) software. These bridges belonged to five different limit states: lateral torsional buckling, changes in cross-section along the member length, tight stringer spacings, girder end shear and moment over continuous piers. </div><div><br></div><div>This research study explores the inherent differences between LFR and LRFR to justify the inconsistencies in the rating values. To find an explanation for these discrepancies, load ratings of these bridges were carried out extensively on AASHTOWare BrR. To verify the results produced by BrR, a separate analysis was also conducted using Mathcad and structural analysis results from SAP2000 for comparison purposes. Finally, the study also recommends some modifications in the BrR software that can be adopted for each of the above-mentioned limit states to resolve inconsistencies found between LFR and LRFR rating values. </div><div><br></div>

The objectives of this work are to review, investigate and model the microwave planar filters of the modern wireless communication system. The recent main stream of microwave filters are classified and discussed separately. Various microwave filters with detailed applications are investigated in terms of their geometrical structures and operational performances. A comprehensive theoretical study of microwave filters is presented. The main types of microwave filters including the basic low-pass filters such as Butterworth and Chebyshev filters are fully analysed and described in detail. The transformation from low-pass prototype filters to high-pass filters, band-pass filters and band-stop filters are illustrated and introduced. Research work on stepped impedance resonator (SIR) and asymmetric stepped impedance resonator (ASIR) structure is presented. The characteristics of λg/4, λg/2 and λg (λg is the guided wavelength of the fundamental frequency in the free space) type SIR resonators, and the characteristic of asymmetric SIR resonator are categorized and investigated. Based on the content mentioned above, novel multi-standard high performance asymmetric stepped impedance resonator single-wideband and dual-wideband filters with wide stopbands are proposed. The methodologies to realize wide passband and wide stop-band filters are detailed. In addition, multi-standard high performance triplewideband, quadruple-wideband and quint-wideband filters are suggested and studied. The measurement results for all prototype filters agree well with the theoretical predictions and simulated results from Ansoft HFSS software. The featured broad bandwidths over single/multiple applicable frequency bands and the high performances of the proposed filters make them very promising for applications in future multistandard wireless communication.

Noise and vibration suppression is an important aspect in the design process of structures and machines. Undesirable vibrations can cause fatigue in a structure and are, therefore, a risk to the safety of a structure. One of the most effective and widely used methods of mitigating these unwanted vibrations from a system is passive damping, by using a viscoelastic material. This dissertation will primarily focus on constrained layer passive damping treatments in structures and the investigation of associated complex modes. The key idea behind constrained damping treatment is to increase damping as affected by the presence of a highly damped core layer vibrating mainly in shear. Our main goal was to incorporate viscoelastic material in a thick stiffened panel with plate-strip stiffeners, to enhance the damping characteristics of the structure. First, we investigated complex damped modes in beams in the presence of a viscoelastic layer sandwiched between two elastic layers. The problem was solved using two approaches, (1) Rayleigh beam theory and analyzed using the principle of virtual work, and (2) by using 2D plane stress elasticity based finite-element method. The damping in the viscoelastic material was modeled using the complex modulus approach. We used FEM without any kinematic assumptions for the transverse shear in both the core and elastic layers. Moreover, numerical examples were studied, by including complex modulus in the base and constraining layers. The loss factor was calculated by modal strain energy method, and by solving a complex eigenvalue problem. The efficiency of the modal strain energy method was tested for different loss factors in the core layer. Complex mode shapes of the beam were also examined in the study, and a comparison was made between viscoelastically damped and non-proportionally damped structures. Secondly, we studied the free vibration response of an integrally stiffened and/or stepped plate. The stiffeners used here were plate-strip stiffeners, unlike the rib stiffeners often investigated by researchers. Both plate and stiffeners were analyzed using the first-order shear deformation theory. The deflections and rotations were assumed as a product of Timoshenko beam functions, chosen appropriately according to the given boundary conditions. Unlike Navier and Levy solution techniques, the approach used here can also be applied to fully clamped, free and cantilever supported stiffened plates. The governing differential equations were solved using the Rayleigh-Ritz method. The development of the stiffness and the mass matrices in the Ritz analysis was found to consume a huge amount of CPU time due to the recursive integration of Timoshenko beam functions. An approach is suggested to greatly decrease this amount of CPU time, by replacing the recursive integration in a loop structure in the computer program, with the analytical integration of the integrand in the loop. The numerical results were compared with the exact solutions available in the literature and the commercially available finite-element software ABAQUS. Some parametric studies were carried out to show the influence of certain important parameters on the overall natural frequencies of the stiffened plate. Finally, we investigated the damped response of an adhesively bonded plate employing plate-strip stiffeners, using FSDT for both the plate and stiffeners. The problem was analyzed using the principle of virtual work. At first, we did not consider damping in the adhesive in order to validate our code, by comparing our results with those available in the literature as well as with the results obtained using ABAQUS 3D model. The results were found to be highly satisfactory. We also considered the effect of changing the stiffness of the adhesive layer on the vibration of the bonded system. As a second step, we included damping in the stiffened structure using complex modulus approach, a widely used technique to represent the rheology of the viscoelastic material. We observed an overall increase in the natural frequencies of the system, due to the damping provided by the viscoelastic material. Moreover, it was noticed that when the thickness of the adhesive layer is increased, the natural frequencies and loss factor of the stiffened structure decrease. A viscoelastic material with high loss factor and small thickness will be a perfect design variable to obtain overall high damping in the structure. / Ph. D.

Cette étude de cas vise à comparer le modèle de soins implanté sur le territoire d’un centre de santé et des services sociaux (CSSS) de la région de Montréal aux modèles de soins en étapes et à examiner l’influence de facteurs contextuels sur l’implantation de ce modèle. Au total, 13 cliniciens et gestionnaires travaillant à l’interface entre la première et la deuxième ligne ont participé à une entrevue semi-structurée. Les résultats montrent que le modèle de soins hiérarchisés implanté se compare en plusieurs points aux modèles de soins en étapes. Cependant, certains éléments de ces derniers sont à intégrer afin d’améliorer l’efficience et la qualité des soins, notamment l’introduction de critères d’évaluation objectifs et la spécification des interventions démontrées efficaces à privilégier. Aussi, plusieurs facteurs influençant l’implantation d’un modèle de soins hiérarchisés sont dégagés. Parmi ceux-ci, la présence de concertation et de lieux d’apprentissage représente un élément clé. Néanmoins, certains éléments sont à considérer pour favoriser sa réussite dont l’uniformisation des critères et des mécanismes de référence, la clarification des rôles du guichet d’accès en santé mentale et l’adhésion des omnipraticiens au modèle de soins hiérarchisés. En somme, l’utilisation des cadres de référence et d’analyse peut guider les gestionnaires sur les enjeux à considérer pour favoriser l’implantation d’un modèle de soins basé sur les données probantes, ce qui, à long terme, devrait améliorer l’efficience des services offerts et leur adéquation avec les besoins populationnels. / The purpose of the present study was to compare the care model of one Montreal local territory to the stepped-care model and to investigate factors influencing the implementation of this model. A qualitative case-study approach was employed involving 13 semi-structured interviews with services providers and managers from primary and specialist mental healthcare. Results showed that the hierarchical care model in place in this territory is compared in several points with the stepped-care model. However, some elements of these models have to be integrated to improve efficiency and quality of care, including the introduction of objective evaluation criteria and the specification of evidence-based interventions. Furthermore, some factors influenced the implementation of this hierarchical care model. Thus, the presence of collaborative working and learning strategies were identified to be a key condition. However, some elements must be considered to facilitate its success like the standardization of the referral criteria and process, the clarification of the mental health guichet d’accès (centralized access point) roles and the general practitioners' adherence to the care model. In conclusion, the use of the reference and analysis frames of this study may guide managers on issues to be considered to support the implementation of an evidence-based care model which may facilitate mental healthcare efficiency and its adequacy with the population needs.

In this study, the &ldquo / Free Flexural (or Bending) Vibrations of Stiffened Plates or Panels&rdquo / are investigated in detail. Two different Groups of &ldquo / Stiffened Plates&rdquo / will be considered. In the first group, the &ldquo / Type 4&rdquo / and the &ldquo / Type 6&rdquo / of &ldquo / Group I&rdquo / of the &ldquo / Integrally-Stiffened and/or Stepped-Thickness Plate or Panel Systems&rdquo / are theoretically analyzed and numerically solved by making use of the &ldquo / Mindlin Plate Theory&rdquo / . Here, the natural frequencies and the corresponding mode shapes, up to the sixth mode, are obtained for each &ldquo / Dynamic System&rdquo / . Some important parametric studies are also presented for each case. In the second group, the &ldquo / Class 2&rdquo / and the &ldquo / Class 3&rdquo / of the &ldquo / Bonded and Stiffened Plate or Panel Systems&rdquo / are also analyzed and solved in terms of the natural frequencies with their corresponding mode shapes. In this case, the &ldquo / Plate Assembly&rdquo / is constructed by bonding &ldquo / Stiffening Plate Strips&rdquo / to a &ldquo / Base Plate or Panel&rdquo / by dissimilar relatively thin adhesive layers. This is done with the purpose of reinforcing the &ldquo / Base Plate or Panel&rdquo / by these &ldquo / Stiffening Strips&rdquo / in the appropriate locations, so that the &ldquo / Base Plate or Panel&rdquo / will exhibit satisfactory dynamic response. The forementioned &ldquo / Bonded and Stiffened Systems&rdquo / may also be used to repair a damaged (or rather cracked) &ldquo / Base Plate or Panel&rdquo / . Here in the analysis, the &ldquo / Base Plate or Panel&rdquo / , the &ldquo / Stiffening Plate Strips&rdquo / as well as the in- between &ldquo / adhesive layers&rdquo / are assumed to be linearly elastic continua. They are assumed to be dissimilar &ldquo / Orthotropic Mindlin Plates&rdquo / . Therefore, the effects of shear deformations and rotary moments of inertia are considered in the theoretical formulation. In each case of the &ldquo / Group I&rdquo / and &ldquo / Group II&rdquo / problems, the &ldquo / Governing System of Dynamic Equations&rdquo / for every problem is reduced to the &ldquo / First Order Ordinary Differential Equations&rdquo / . In other words the &ldquo / Free Vibrations Problem&rdquo / , in both cases, is an &ldquo / Initial and Boundary Value Problem&rdquo / is reduced to a &ldquo / Two- Point or Multi-Point Boundary Value Problem&rdquo / by using the present &ldquo / Solution Technique&rdquo / . For this purpose, these &ldquo / Governing Equations&rdquo / are expressed in &ldquo / compact forms&rdquo / or &ldquo / state vector&rdquo / forms. These equations are numerically integrated by the so-called &ldquo / Modified Transfer Matrix Method (MTMM) (with Interpolation Polynomials)&rdquo / . In the numerical results, the mode shapes together with their corresponding non-dimensional natural frequencies are presented up to the sixth mode and for various sets of &ldquo / Boundary Conditions&rdquo / for each structural &ldquo / System&rdquo / . The effects of several important parameters on the natural frequencies of the aforementioned &ldquo / Systems&rdquo / are also investigated and are graphically presented for each &ldquo / Stiffened and Stiffened and Bonded Plate or Panel System&rdquo / . Additionally, in the case of the &ldquo / Bonded and Stiffened System&rdquo / , the significant effects of the &ldquo / adhesive material properties&rdquo / (i.e. the &ldquo / Hard&rdquo / adhesive and the &ldquo / Soft&rdquo / adhesive cases) on the dynamic response of the &ldquo / plate assembly&rdquo / are also presented.

Cette étude de cas vise à comparer le modèle de soins implanté sur le territoire d’un centre de santé et des services sociaux (CSSS) de la région de Montréal aux modèles de soins en étapes et à examiner l’influence de facteurs contextuels sur l’implantation de ce modèle. Au total, 13 cliniciens et gestionnaires travaillant à l’interface entre la première et la deuxième ligne ont participé à une entrevue semi-structurée. Les résultats montrent que le modèle de soins hiérarchisés implanté se compare en plusieurs points aux modèles de soins en étapes. Cependant, certains éléments de ces derniers sont à intégrer afin d’améliorer l’efficience et la qualité des soins, notamment l’introduction de critères d’évaluation objectifs et la spécification des interventions démontrées efficaces à privilégier. Aussi, plusieurs facteurs influençant l’implantation d’un modèle de soins hiérarchisés sont dégagés. Parmi ceux-ci, la présence de concertation et de lieux d’apprentissage représente un élément clé. Néanmoins, certains éléments sont à considérer pour favoriser sa réussite dont l’uniformisation des critères et des mécanismes de référence, la clarification des rôles du guichet d’accès en santé mentale et l’adhésion des omnipraticiens au modèle de soins hiérarchisés. En somme, l’utilisation des cadres de référence et d’analyse peut guider les gestionnaires sur les enjeux à considérer pour favoriser l’implantation d’un modèle de soins basé sur les données probantes, ce qui, à long terme, devrait améliorer l’efficience des services offerts et leur adéquation avec les besoins populationnels. / The purpose of the present study was to compare the care model of one Montreal local territory to the stepped-care model and to investigate factors influencing the implementation of this model. A qualitative case-study approach was employed involving 13 semi-structured interviews with services providers and managers from primary and specialist mental healthcare. Results showed that the hierarchical care model in place in this territory is compared in several points with the stepped-care model. However, some elements of these models have to be integrated to improve efficiency and quality of care, including the introduction of objective evaluation criteria and the specification of evidence-based interventions. Furthermore, some factors influenced the implementation of this hierarchical care model. Thus, the presence of collaborative working and learning strategies were identified to be a key condition. However, some elements must be considered to facilitate its success like the standardization of the referral criteria and process, the clarification of the mental health guichet d’accès (centralized access point) roles and the general practitioners' adherence to the care model. In conclusion, the use of the reference and analysis frames of this study may guide managers on issues to be considered to support the implementation of an evidence-based care model which may facilitate mental healthcare efficiency and its adequacy with the population needs.

The new legal regulations derived from climate change dictate that hydraulic structures must be designed to handle flood events associated with return periods up to 10,000 years. This obviously involves adapting the existing infrastructure to meet such requirements. In order to avoid risks in the restitution of the flow discharged to rivers, such as bank overflows or streambed erosion and scour processes, hydraulic design must be supported by reliable tools capable of reproducing the behavior of hydraulic structures. In the work presented herein, a fully three-dimensional CFD model to reproduce the behavior of different types of air-water flow in hydraulic structures is presented. The flow is assumed to be turbulent, isotropic and incompressible. Several RANS turbulence models are tested and structured rectangular meshes are employed to discretize the analyzed domain. The presence of two fluids is modeled using different VOF approaches and simulations are run using the PIMPLE algorithm. The model is implemented using the open-source platform OpenFOAM and its performance is compared to the commercial code FLOW-3D. The analysis is conducted separately on two different parts of hydraulic structures, namely: the spillway and the stilling basin. Additionally, a case of practical application, where the model reproduces the flow of a real-life case, is also presented in order to prove the suitability of the model to actual design cases. Mesh independence and model validation using experimental data are checked in the results of all the case studies. The sensitivity of the presented model to certain parameters is extensively discussed using different indicator variables. Among these parameters are turbulence closure, discretization scheme, surface tracking approach, CFD code or boundary conditions. Pros and contras of each of them are addressed. The analyzed turbulence models are the Standard k ¿ ¿, the Realizable k ¿ ¿, the RNG k ¿ ¿, and the SST k ¿ ¿. The discretization schemes under study are: a first-order upwind method, the second-order limited Van Leer method, and a second-order limited central difference method. The VOF approaches analyzed are the Partial VOF, as implemented in OpenFOAM, and the TruVOF, as implemented in FLOW-3D. In most cases, the Standard k ¿ ¿ model provides the most accurate estimations of water free surface profiles, although the rest of variables, with few exceptions, are better predicted by the RNG k ¿ ¿. The latter model generally requires slightly longer computation times. The SST k ¿ ¿ reproduces correctly the phenomena under study, although it generally turned out to be less accurate than its k ¿ ¿ counterparts. As regards the comparison among VOF approaches and codes, it is impossible to determine which one performs best. E.g. OpenFOAM, using the Partial VOF, managed to reproduce the in- ternal hydraulic jump structure and all derived variables better than FLOW-3D, using the TruVOF, although the latter seems to capture better the momentum transfer and so all derived variables. In the case of flow in stepped spillways, OpenFOAM captures better the velocity profiles, although FLOW-3D is more accurate when estimating the water free surface profile. It is worth remark- ing that not even their response to certain model parameters is comparable. E.g. FLOW-3D is significantly less sensitive to mesh refinement than OpenFOAM. Given the result accuracy achieved in all cases, the proposed model is fully applicable to more complex design cases, where stilling basins, stepped spillways and hydraulic structures in general must be investigated. / Las nuevas disposiciones legales derivadas del cambio climático dictaminan que las estructuras hidráulicas sean capaces de funcionar correctamente con eventos de inundación asociados a periodos de retorno de hasta 10,000 años. Esto, obviamente, implica adaptar la infraestructura existente para satisfacer dichos requerimientos. A fin de evitar riesgos en la restitución de los caudales vertidos al río, como desbordamientos o procesos erosivos y de socavación, el diseño hidráulico ha de sustentarse en herramientas fiables capaces de reproducir el comportamiento de las estructuras hidráulicas. En este trabajo, se presenta un modelo numérico CFD completamente tridimensional para reproducir el comportamiento de diferentes tipos de flujo aire-agua en estructuras hidráulicas. Se asume que el flujo es turbulento, isotrópico e incompresible. Diversos modelos de turbulencia RANS son contrastados y se emplean mallas estructuradas rectanuglares para discretizar el dominio analizado. La presencia de dos fluidos es modelada utilizando diferentes enfoques VOF y las simulaciones son ejecutadas empleando el algoritmo PIMPLE. El modelo es implementado mediante la plataforma de código abierto OpenFOAM y su respuesta es comparada con la del modelo comercial FLOW-3D. El análisis se lleva a cabo sobre dos partes diferentes de una estructura hidráulica, a saber, el aliviadero y el cuenco amortiguador, de forma separada. Además, un caso de aplicación práctica, donde el modelo reproduce el flujo en una estructura real, es presentado también a fin de probar la adecuación del modelo a casos de diseño aplicado. Se comprueban la independencia de la malla y la validación con datos experimentales de los resultados de todos los casos de estudio. La sensibilidad del modelo presentado a ciertos parámetros es analizada de forma exhaustiva empleando diferentes variables indicadoras. Los pros y contras de cada uno de éstos son planteados. Los modelos de turbulencia analizados son el Standard k-epsilon, el Realizable k-epsilon, el RNG k-epsilon y el SST k-omega. Los esquemas de discretización estudiados son: un método de primer orden upwind, uno de Van Leer de segundo orden y un esquema de segundo orden limitado de diferencias centradas. Los enfoques VOF analizados son el Partial VOF, implementado en OpenFOAM, y el TruVOF, implementado en FLOW-3D. En la mayoría de casos, el modelo k-epsilon aporta las estimaciones más precisas de perfiles de lámina libre de agua, pese a que el resto de variables, con alguna excepción, son mejor predichas por el RNG k-epsilon. Este modelo generalmente requiere mayores tiempos de cálculo. El k-omega reproduce correctamente los fenómenos bajo estudio, pese a que su precisión es generalmente más baja que la de los modelos k-epsilon. En lo que respecta a la comparación entre enfoques VOF y códigos, es imposible determinar cuál es el mejor. Por ejemplo, OpenFOAM, empleando el Partial VOF, logra reproducir la estructura interna del resalto hidráulico y todas las variables derivadas mejor que FLOW-3D, empleando el TruVOF, a pesar de que este último parece capturar mejor la transferencia de cantidad de movimiento y, por tanto, todas las variables derivadas. En el caso del flujo en aliviaderos escalonados, OpenFOAM captura mejor los perfiles de velocidad, pese a que FLOW-3D es más preciso en la estimación de los perfiles de lámina libre de agua. Conviene recalcar que ni tan sólo su respuesta a ciertos parámetros del modelo es comparable. Por ejemplo, FLOW-3D es significativamente menos sensible al refinado de malla que OpenFOAM. A la luz de la precisión de los resultados obtenidos en todos los casos, el modelo propuesto es completamente aplicable a casos de diseño más complejos, donde cuencos amortiguadores, aliviaderos escalonados y estructuras hidráulicas en general han de ser investigadas. / Les noves disposicions legals derivades del canvi climàtic dictaminen que cal que les estructures hidràuliques siguen capaces de funcionar correctament amb esdeveniments d'inundació associats a períodes de retorn de fins a 10,000 anys. Això, òbviament, implica adaptar la infraestrctura existent per satisfer aquests requeriments. A fi d'evitar riscs en la restitució dels cabals vessats al riu, com desbordaments o processos erosius i de socavació, el disseny hidràulic ha de recolzar-se en ferramentes fiables capaces de reproduir el comportament de les estructures hidràuliques. En aquest treball, es prsenta un model numèric CFD completament tridimensional per a reproduir el comportament de diferents tipus de flux aire-aigua en estructures hidràuliques. S'assumeix que el flux és turbulent, isotròpic i incompressible. Diferents models de turbulència RANS són contrastats i s'empren malles estructurades rectangulars per discretitzar el domini analitzat. La presència de dos fluids és modelada utilitzant diferents enfocaments VOF i les simulacions són executades emprant l'algorisme PIMPLE. El model és implementat mitjançant la plataforma de codi obert OpenFOAM i la seua resposta és comparada amb la del codi comercial FLOW-3D. L'anàlisi es du a terme sobre les diferents parts d'una estructura hidràulica, a saber, sobreeixidors esgraonats i vas esmorteïdor, de forma separada. A més, un cas d'aplicació pràctica, on el model reprodueix el flux a una estructura real, és presentat també a fi de provar l'adequació del model a casos de disseny aplicat. Es comproven la independència de la malla i la validació amb dades experimentals dels resultats de tots els casos d'estudi. La sensibilitat del model presentat a certs paràmetres és analitzada de forma exhaustiva emprant diferents variables indicadores. Els pros i contres de cadascun d'aquests són plantejats. Els models de turbulència analitzats són l'Standard k-epsilon, el Realizable k-epsilon, el RNG k-epsilon i l'SST k-omega. Els esquemes de discretització estudiats són: un mètode de primer ordre upwind, un de Van Leer de segon ordre i un esquema de segon ordre limitat de diferències centrades. Els enfocaments VOF analitzats són el Partial VOF, implementat en OpenFOAM, i el TruVOF, implementat en FLOW-3D. En la majoria de casos, el model Standard k-epsilon aporta les estimacions més precises de perfils de làmina lliure d'aigua, tot i que la resta de variables, amb alguna excepció, són millor predites pel RNG k-epsilon. Aquest model generalment requereix majors temps de càlcul. El k-omega reprodueix correctament els fenòmens sota estudi, tot i que la seua precisió és generalment més baixa que la dels models k-epsilon. Pel que fa la comparació entre enfocaments VOF i codis, és impossible determinar quin és el millor. Per exemple, OpenFOAM, emprant el Partial VOF, aconsegueix reproduir l'estructura interna del ressalt hidràulic i totes les variables derivades millor que FLOW-3D, emprant el TruVOF, tot i que aquest últim pareix capturar millor la transferència de quantitat de moviment i, per tant, totes les variables derivades. En el cas del flux en sobreeixidors esgraonats, OpenFOAM captura millor els perfils de velocitat, tot i que FLOW-3D és més precís en estimar els perfils de làmina lliure d'aigua. Cal deixar palès que ni tan sols la seua resposta a certs paràmetres del model és comparable. Per exemple, FLOW-3D és significativament menys sensible al refinament de malla que OpenFOAM. En base a la precisió dels resultats obtinguts en tots els casos, el model proposat és completament aplicable a casos de disseny més complexos, on vassos esmorteïdors, sobreeixidors esgraonats i estructures hidràuliques en general han de ser investigades. / Bayón Barrachina, A. (2017). Numerical analysis of air-water flows in hydraulic structures using computational fluid dynamics (CFD) [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/90440 / TESIS

Thesis is devoted to a problem of Power Factor Correction on the low voltage level. It has still its own difficulties despite the fact that topic moved through long development. The main goal of this work is to offer reader variable procedure considering design process. It is based on use of measured data of network analyzer Meg30. The design algorithm has to share a maximum of eventual influencing factors. Therefore the body of master thesis goes through detailed analysis of Power Factor Correction.