Contributions to discrete-time methods for room acoustic simulation

The sound field distribution in a room is the consequence of the acoustic properties of radiating sources and the position, geometry and absorbing characteristics of the surrounding boundaries in an enclosure (boundary conditions). Despite there existing a consolidated acoustic wave theory, it is very difficult, nearly impossible, to find an analytical expression of the sound variables distribution in a real room, as a function of time and position. This scenario represents as an inhomogeneous boundary value problem, where the complexity of source properties and boundary conditions make that problem extremely hard to solve. Room acoustic simulation, as treated in this thesis, comprises the algebraical approach to solve the wave equation, and the way to define the boundary conditions and source modeling of the scenario under analysis. Numerical methods provide accurate algorithms for this purpose and among the different possibilities, the use of discrete-time methods arises as a suitable solution for solving those partial differential equations, particularized by some specific constrains. Together with the constant growth of computer power, those methods are increasing their suitability for room acoustic simulation. However, there exists an important lack of accuracy in the definition of some of these conditions so far: current frequency-dependent boundary conditions do not comply with any physical model, and directive sources in discrete-time methods have been hardly treated. This thesis discusses about the current state-of-the-art of the boundary conditions and source modeling in discrete-time methods for room acoustic simulation, and it contributes some algorithms to enhance boundary condition formulation, in a locally reacting impedance sense, and source modelling in terms of directive sources under a defined radiation pattern. These algorithms have been particularized to some discrete-time methods such as the Finite Difference Time Domain and the Digital Waveguide Mesh.Escolano Carrasco, J. (2008). Contributions to discrete-time methods for room acoustic simulation [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/8309Palanci

Size and spatial and functional structure of aggregate daily mobility networks in functional urban areas: Integrating adjacent spaces at several scales

People's daily movements, as aggregated in spatial units, shape mobility flows that can be modelled by geospatial networks. The structure of these networks both reflects and influences how cities are lived in, perceived and planned. In this study, location tracking data from mobile phones were used to investigate the functional and spatial structures of daily mobility networks and how these networks change as they grow in size. A case study was performed on 81 Spanish functional Urban Areas (FUAs). The results of this study show that the friction of the space and the average length of the aggregate daily mobility are constant and do not depend on the area and demographic size of the FUAs. The average length of the aggregate daily mobility is associated with the increase in complexity that occurs as mobility networks grow, which is reflected in an increase in the number of levels of interaction and the proportion of local flows that integrate adjacent spaces across different scales. The method used provides quantitative indicators that reveal the similarities and differences of daily mobility, as well as the interactions that occur in FUAs according to their size. This information is very useful in urban and mobility planning

La evaluación de creencias y actitudes disfuncionales en los modelos de Ellis y Beck: similitudes y diferencias

El objetivo del presente estudio es el análisis comparativo del 'Inventario de Actitudes y Creencias' (ABI) y la 'Escala de Actitudes Disfuncionales' (DAS) elaborados, respectivamente, desde las perspectivas de la Terapia Racional Emotivo Conductual (TREC) de Albert Ellis y la Terapia Cognitiva (TC) de Aaron Beck. Administramos sendos cuestionarios a una muestra de 156 estudiantes universitarios y verificamos la correspondencia y covariancia entre escalas mediante análisis de correlación de Spearman y canónica, componentes principales y regresión múltiple. Los resultados revelan escasa correlación y variancia compartida entre el ABI y la DAS, lo que sugeriría que ambos cuestionarios evalúan aspectos diferentes. Sin embargo, consideramos que ello pueda ser debido a la combinación lineal constatada entre las subescalas de actitudes y creencias del ABI, por lo que sugerimos cambios estructurales en el contenido y distribución de los ítems de dicho instrumento

A mixed boundary condition for accounting energy absorption and transmission in a diffusion equation model

The acoustic diffusion equation model has shown to be a versatile alternative model for certain types of scenarios where the classical geometrical methods have been demonstrated to be inefficient or even inaccurate. In certain scenarios, the transmission loss plays a fundamental role for accounting, i.e., noise levels and sound propagation between rooms. This paper presents an extension of the absorption boundary conditions known as modified that unifies previously proposed boundary conditions in one equation, including transmission of energy between coupled rooms by both openings and enclosures.Ingeniería, Industria y Construcció