Apresentamos um estudo das álgebras de incidência que são hereditárias por partes, as quais denominamos Phias, piecewise hereditary incidence algebras. Através da aljava com relações, descrevemos as Phias de tipo Dynkin e introduzimos uma nova família de Phias de tipo Dynkin extendido chamada família ANS, em referência a Assem, Nehring e Skowronski. Nessa descrição, o importante método foi o dos cortes em extensões triviais, os quais inspiraram a elaboração de um programa que concebe exatamente os cortes na extensão trivial dada que resultam em álgebras de incidência. Abordamos as Phias &#922\\&#916 de tipo feixes, estudando o &#922\\&#916-módulo sincero canônico M e a álgebra de extensão por um ponto &#922\\&#916[&#924]. Demonstramos que se &#922Q/I é uma álgebra sincera, quase-inclinada canônica de tipo aljava e tipo de representação infinito, então os &#922Q/I-módulos sinceros são excepcionais. Essa conclusão permite construir uma gama de Phias &#922\\&#916[&#924] de tipo selvagem. Exploramos as Phias simplesmente conexas, provando uma resposta positiva para o problema de Skowronski para &#922\\&#916 uma Phia de tipo H, com grafo de objetos inclinantes &#922_D^b (&#919) conexo: o grupo &#919^1(&#922\\&#916) é trivial se, e somente se, a álgebra &#922\\&#916 é simplesmente conexa. Na área homológica, determinamos um limitante superior da dimensão global forte das Phias; mais ainda, ampliamos esse resultado para as álgebras sinceras provando que dada uma álgebra sincera e hereditária por partes, sua dimensão global forte é menor ou igual a três. / We present a study of incidence algebras that are piecewise hereditary, which we denominate Phias. By means of the quiver with relations, we describe Phias of Dynkin type and introduce a new family of Phias of extended Dynkin type, which we call ANS family, in reference to Assem, Nehring, and Skowronski. In this description, the important method was the one of cuts on trivial extensions, inspiring the writing of a program that shows exactly the cuts on the given trivial extension that result on incidence algebras. We approach sheaves type Phias &#922\\&#916, studying the canonical sincere &#922\\&#916-module M and the one-point extension algebra &#922\\&#916[&#924]. We show that if &#922Q/I is a sincere, quasi-tilted canonical algebra of quiver type and infinite representation type, then sincere &#922Q/I-modules are exceptional. This conclusion allows the construction of a wide range of Phias &#922\\&#916[&#924] wild type. We explore the simply conectedeness of Phias, proving a positive answer of the so called Skowronski problem for &#922\\&#916 a Phia H type, with connected quiver of tilting objects &#922_D^b (&#919): the group &#919^1(&#922\\&#916) is trivial if, and only if, &#922\\&#916 is a simply connected algebra. On homology, we determine an upper bound for the strong global dimension of Phias; furthermore, we extend this result for sincere algebras proving that the strong global dimension of a sincere piecewise hereditary algebra is less or equal to three.

The Wiener index of a graph G is defined as the sum of the distances between all pairs of vertices in G. In this master thesis we introduce recursive trees, plane oriented recursive trees (PORTs) and simply generated trees. We then present results by Neininger, Janson, and Munsonius and Rüschendorf for the expectation and limiting distribution of the Wiener index of these families. For recursive trees and PORTs the results follow from analysing the recursive structure of the trees and the contraction method, while the results for simply generated trees is based on a limiting object, the continuum random tree.

Active Structural Acoustic Control (ASAC) is a subcategory of the more widely known field of Active Noise control (ANC). ASAC is different from traditional ANC methods because it seeks to attenuate noise by altering the noise producing structure instead of altering the acoustic waves traveling through the air. The greatest challenge currently facing ASAC researchers is that a suitable parameter has not yet been discovered which can be easily implemented as the minimization quantity in the control algorithms. Many parameters have been tried but none effectively attenuate the sound radiation in a way that can be easily implemented. A new parameter was recently developed which showed great potential for use as a minimization quantity. This parameter has been termed the "weighted sum of spatial gradients" (WSSG) and was shown by previous researchers to significantly reduce noise emissions from a vibrating simply supported plate in computer simulations. The computer simulations indicate that WSSG-based control provides as good or better control than volume velocity and does so with a single point measurement which is relatively insensitive to placement location. This thesis presents the experimental validation of the WSSG computer simulations. This validation consists of four major components. First, additional research was needed in to extend the use of WSSG from computer simulations to experimental setups. Second, the WSSG-based control method was performed on simply supported plates to validate the computer simulations. Third, the WSSG-based control method on was used on clamped plates to validate the computer simulations, and fourth, the WSSG-based control method was validated on plates with ribs. The important results are discussed and conclusions summarized for each of these sections. Recommendations are made for future work on the WSSG parameter.

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In response to the planned increase in operational speeds and axle loads of passengertrains that may lead to resonance-induced excessive vibrations in railway bridges,recent studies examined the reliability of bridges concerning train running safety andpassenger comfort limit states. In this respect, valuable information regarding theimportance of input variables can be obtained by conducting Sensitivity Analysis (SA).For instance, the determination of unimportant variables (where they can be treated asconstant) reduces the computational time, which is usually very high for probabilisticsimulations. In some of the previous studies, only deterministic SA has beenperformed. This thesis follows a stochastic approach using Global Sensitivity Analysis(GSA) methods. The considered performance functions are vertical acceleration anddeflection of single track ballasted simply supported reinforced concrete bridges.To reduce the computational time, available semi-analytical solution of a planarbeam under the passage of a series of moving loads is employed. To simulatethe bridge behaviour realistically, simplified methods to account for rail irregularityamplification, train-bridge interactions, and axle load redistribution were adopted.The considered random variables are train modal properties, number of train coaches,bogie spacing, axle spacing and loads, bridge mass, flexural stiffness and damping,and rail amplification factor. The analyses were carried out for a selected set of bridgelengths [10-30]m and a range of train speeds [100-400] km/hr. The study findingsshow that, in both acceleration and displacement, the dynamic response of the bridgeis sensitive to randomness in bridge mass, moment of inertia, coach length, and axleloads. Furthermore, the rail amplification factor and Young’s modulus are primarilyimportant for acceleration and displacement, respectively.

The full text will be available at the end of the embargo: 26th April 2025

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Water-assisted crack growth at an epoxy/glass interface was measured as a function of applied strain energy release rate, G, and temperature using a wedge test geometry. The specimens consist of two glass plates bonded with a thin layer of proprietary epoxy adhesive. The crack fronts along the epoxy/glass interfaces were measured using an optical stereomicroscope. The relationship between G and the debonding rate, v, can be measured using this method, and the threshold value of strain energy release rate, Gth, can be determined from the measured data. Two types of testing procedures were conducted in this study: ex situ, i.e., pre-conditioned wedge tests and in situ ones, in which wedges were applied before the specimens were submerged into water. A preliminary model was developed based on the thermal activation barrier concept, and allows the prediction of Gth for the temperatures beyond the testing region. Changes in interfacial strain energy release rate caused by thermal residual stresses in a triple-layered specimen were analyzed in Chapter Three. The method is based on linear elastic fracture mechanics and simple beam theory. The curvature of a bimaterial strip was chosen to characterize the residual stress in the specimen, and the strain energy release rate, caused by both tensile and compressive residual stresses in the adhesive, was derived for an asymmetric double cantilever beam (ADCB) geometry. The contribution of the thermal residual and mechanical stress to the global energy release rate was analyzed. The thermally induced energy release rate, GT, is found to be independent of crack length, but is a function of residual stress level and geometric and material parameters of the specimen. The adhesion of films and coatings to rigid substrates is often measured using blister geometries, which are loaded either by an applied pressure or a central shaft. The measurement will be affected if there are residual stresses that make a contribution to the energy release rate. This effect is investigated using analytical solutions based on the principle of virtual displacements. A geometrically nonlinear finite element analysis is conducted for comparison. Furthermore, the relationships among strain energy release rate, load, deflection, and fracture radius are discussed in detail in Chapter Four. Both analytical solutions and numerical results reveal that uniform tensile residual stresses reduce a specimen's deflection if it experiences plate behavior under small loads. However, this effect diminishes when membrane behavior is dominant. The mechanics of a single-lap joint with different boundary conditions subjected to tensile loading are investigated. Closed-form solutions are obtained for a specimen configuration considering different clamping methods. Based on the approach pioneered by Goland and Reissner, the solutions reported in this paper provide a simple but useful way to understand the effects of boundary conditions on this test geometry. The solutions in this study suggest that different grip configurations mainly affect the response of the specimens if the grip position is close to the joint edge or the loads are small. Generally, the influence caused by different gripping methods is only limited to the boundary region, and the behavior of the joint part subjected to tensile loading is almost the same as that for a simply-supported case. / Ph. D.

[ES] El objetivo de la tesis es proponer una metodología que permita la definición de pasarelas de un único vano a partir de unas condiciones de contorno determinadas, utilizando unos diseños estéticamente atractivos. Se desarrolla el diseño y la formulación geométrica de tres pasarelas paramétricas, denominadas Von Mises, Monocontentio y Bicontentio, cuyo diseño se basa en cinco fundamentos básicos: integración en la geometría del terreno, búsqueda continua de la sencillez, siluetas que emanan del comportamiento estructural, formas unitarias y detalles perdurables. La silueta de la pasarela Von Mises se basa en la gráfica del criterio de comparación de Von Mises de una viga biapoyada, la del prototipo Monocontentio en la ley de momentos de una viga empotrada-apoyada y la de la pasarela Bicontentio en la gráfica de flectores de una viga biempotrada. El trabajo incluye una metodología de formulación, que permite obtener las expresiones matemáticas que gobiernan las principales dimensiones y espesores de las pasarelas, en función de su anchura y su luz. Un análisis comparativo de diferentes tipologías de pasarelas viga permite constatar la eficiencia de los prototipos Von Mises, Monocontentio y Bicontentio. Esta se debe a su canto variable adaptado a los esfuerzos de solicitación y al empotramiento en estribos. Asimismo, se realiza un análisis que liga el enfoque de diseño y el pensamiento ingenieril con la expresión estética de los puentes. La tesis supone la puesta en orden de una particular filosofía de diseño utilizada por el autor en una treintena de puentes proyectados durante los últimos 25 años, para poder ser aplicada de manera sistemática por otros profesionales. / [CA] L'objectiu de la tesi és proposar una metodologia que permeta la definició de passarel·les d'un únic tram a partir d'unes condicions de contorn determinades, utilitzant uns dissenys estèticament atractius. Es desenvolupa el disseny i la formulació geomètrica de tres passarel·les paramètriques, denominades Von Mises, Monocontentio i Bicontentio, el disseny de les quals es basa en cinc fonaments bàsics: integració en la geometria del terreny, cerca contínua de la senzillesa, siluetes que emanen del comportament estructural, formes unitàries i detalls perdurables. La silueta de la passarel·la Von Mises es basa en la gràfica del criteri de comparació de Von Mises d'una biga bi- recolzada, la del prototip Monocontentio en la llei de moments d'una biga encastada-recolzada i la de la passarel·la Bicontentio en la gràfica de flectors d'una biga bi-encastada. El treball inclou una metodologia de formulació, que permet obtindre les expressions matemàtiques que governen les principals dimensions i grossàries de les passarel·les, en funció de la seua amplària i la seua llum. Una anàlisi comparativa de diferents tipologies de passarel·les biga permet constatar l'eficiència dels prototips Von Mises, Monocontentio i Bicontentio. Aquesta es deu al seu cant variable adaptat als esforços de sol·licitació i a l'encast en estreps. Així mateix es realitza una anàlisi que lliga l'enfocament de disseny i el pensament de l'enginyer amb l'expressió estètica dels ponts. / [EN] The purpose of this thesis is to propose a methodology for single-span, pedestrian bridges, based on specific conditions, using an attractive design.This thesis explains the design and geometric formulation of three types of pedestrian bridges, namely Von Mises, Monocontentio and Bicontentio. Their designs are based on five basic principles: (1) integration into the geometry of the environment; (2) permanent search for simplicity; (3) design based on a geometry that emanates from structural behavior; (4) uniform shapes; and (5) enduring details. The silhouette of the Von Mises bridge is inspired by the Von Mises criterion graph, corresponding to a simply- supported beam.The Monocontentio prototype is inspired by the bending moment diagram of a beam fixed at one end and simply supported at the other end. The Bicontentio bridge is inspired by the bending moment diagram of a beam fixed at both ends. This thesis includes a formulation methodology that defines mathematical expressions that govern the main dimensions and thickness of a pedestrian bridge, depending on its respective width and span. A comparative analysis demonstrates the efficiency of these three particular prototypes, due to their variable depth, adapted to the internal forces, and due to fix the structure in abutments. Likewise, this paper analyses and links the design and engineering with the aesthetic expression of the bridges.The author has used this design philosophy in thirty bridge projects over the last 25 years, and such philosophy may be applied in a systematic way by other professionals. / Guisasola Ron, M. (2022). Desarrollo de nuevas formas parametrizadas para pasarelas eficientes y elegantes [Tesis doctoral]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/180776

This dissertation advances the Vibration-Based Sound Power (VBSP) method for measuring the sound power of vibrating structures, expanding its applicability to a wider range of geometries and acoustic environments. The research addresses limitations of traditional sound power measurement techniques by developing an alternative method that achieves near Precision (Grade 1) accuracy while maintaining feasibility for in situ testing under uncontrolled acoustic conditions. After reviewing the current VBSP method in Unit 1, Unit 2 introduces stitching techniques for Scanning Laser Doppler Vibrometer (SLDV) measurements, enabling accurate 3D scans and extending the method to complex geometries. Experimental validation is provided for baffled simply curved plates and arbitrarily curved plates. The method also estimates sound power in uncontrolled acoustic environments, where traditional approaches are less effective. Initial work on thin unbaffled flat plates is presented, with a practical demonstration using pickleball paddles as a representative unbaffled configuration. Unit 3 addresses the computational demand of constructing radiation resistance (R) matrices, a key limitation of the VBSP method. Symmetry-based techniques leveraging acoustic reciprocity and geometric symmetries are applied to reduce computational demands by up to 75% for unbaffled structures. For baffled configurations, translational symmetry of acoustic reciprocity between elements results in the R matrix having Toeplitz symmetry, reducing the computational complexity from n^2 to n, where n is the number of mesh elements. Unit 4 introduces an indirect VBSP (I-VBSP) method to estimate sound power from encased sources, achieving near Precision (Grade 1) accuracy relative to the ISO 3741 standard using only a single surface scan. Validated on a Bluetooth speaker, this approach provides a simplified alternative to conventional methods, offering a practical solution for sound power measurement in structures with encased noise sources. Overall, this dissertation demonstrates that the VBSP method serves as a viable alternative to conventional sound power techniques, effectively applied across various geometries and scenarios. While the current VBSP method does not accommodate structures with multiple vibrating surfaces in contact, the I-VBSP method can theoretically achieve this by enclosing a structure and scanning one vibrating side. This research lays the foundation for future studies through the development of a generalized R matrix and application of foundational symmetries, enhancing the understanding of acoustic radiation from vibrating structures. Ultimately, this work aims to reduce noise pollution in consumer products through improved acoustic design and measurement strategies.