Applications of an exact counting formula in the Bousso-Polchinski Landscape

The Bousso-Polchinski (BP) Landscape is a proposal for solving the Cosmological Constant Problem. The solution requires counting the states in a very thin shell in flux space. We find an exact formula for this counting problem which has two simple asymptotic regime one of them being the method of counting low $\Lambda$ states given originally by Bousso and Polchinski. We finally give some applications of the extended formula: a robust property of the Landscape which can be identified with an effective occupation number, an estimator for the minimum cosmological constant and a possible influence on the KKLT stabilization mechanism.Comment: 43 pages, 11 figures, 2 appendices. We have added a new section (3.4) on the influence of the fraction of non-vanishing fluxes in the KKLT mechanism. Other minor changes also mad

Mapas de ruido. Estrategia y concienciación en la lucha contra el ruido

El ruido ambiental es un problema que está siendo acometido por diferentes iniciativas internacionales..

Improvement of sound quality in spaces and products

The perceived quality of any electrical appliance, vehicle, or either interior or exterior spaces is influenced by the quality of its sound, and this includes the reduction of noise, but also a fine tuning of its sound features. Sound quality is growing field of study that transversally influences the design of products and spaces, combining objective measures with subjective perception of people. Closed to mechanical and acoustics engineering, sound quality and soundscapes bring people views into the scene, trying to translate their subjective response into objective parameters that can be implemented in a product or a space. I2A2 has been involved in several research projects closely related to the optimization of sound emissions of products, such electrical appliances or vehicle components, and spaces, such as vehicle cabins, building components or rooms in an industr

Tourist Influence on Nightlife Noise

Although environmental noise from entertainment and leisure activities is causing a growing number of complaints from EU population, this noise issue is not covered by the current EU initiatives on environmental noise management. This noise problem is difficult to tackle strategically and technically – no specific standards have yet been established for measurements, methods and indicators, and the practical remedies are still limited. This paper reviews nightlife noise and more specifically how the presence of tourists influences the variation of the noise. Several case studies were conducted in some Spanish locations by the seasonal tourist incursion, mainly in the summer months. Variations in the nightlife noise in recreational zones during the weekends and “working days” are compared. This research also discusses data from different years and seasonal periods and reinforced with data obtained through surveys specifically designed for foreign tourists. These surveys reveal practical information about how tourists perceive noise, and their behaviour and reactions to it. Those data could be useful for Environmental Noise Authorities to develop noise action plans, as recreational noise is a source not considered when noise mapping by means of using simulation techniques

Monitorado de ruido de aeropuertos: técnicas de detección, clasificación e identificación de ruido de aeronaves como causantes de incertidumbre en la medida

Monitorado de ruido de aeropuertos: técnicas de detección, clasificación e identificación de ruido de aeronaves como causantes de incertidumbre en la medida (TFM

Un análisis estadístico del paisaje de Bousso-Polchinski y otros modelos relacionados

Consideramos diferentes formas de contar estados metaestables en el paisaje de Bousso-Polchinski (BP). La fórmula exacta de contaje permite identificar una incompatibilidad (el "problema-alpha^*") entre la forma usual de contar y el mecanismo KKLT de estabilización. Este problema aparece debido a la falta de un estudio de estabilidad en el modelo BP, como demuestra el hecho de que el paisaje de Einstein-Maxwell multi-esfera, que construimos en detalle en 1+1 dimensiones, no posee tal problema

Spatial Interpolation contribution to noise maps uncertainty

Noise maps results are usually presented as contour graphs or isophone curves, which describe the sound levels as functions of spatial location. These maps are added to Geographic Information Systems (GIS), allowing sound level evaluation as a function of the continuous coordinates x and y, for a given height above ground. Although the outcome of the system is a continuous variable, the calculations that allow its evaluation are obtained in discrete points that form a calculation grid, which is created by the application of spatial sampling techniques. Using spatial interpolation tools, values are assigned to the locations in which measures or calculations have not been performed. The application of sampling and interpolation techniques (the type of grid, its density, the interpolation algorithms…) contributes to the uncertainty of the results. This paper describes a calculation method to quantify the uncertainty associated to the spatial sampling and interpolation process. We also propose a revision of the classical meaning of noise mapping uncertainty, taking into account the final application of the results

Aportaciones a los sistemas de discriminación de fuentes sonoras en la medida de ruido en aeropuertos

La contaminación acústica se ha convertido en uno de los principales problemas en materia medioambiental de nuestra sociedad. La creciente preocupación ha propiciado la aparición de legislación, en los distintos ámbitos de la administración, cuyo objetivo consiste en gestionar y reducir la contaminación acústica y sus efectos sobre las personas y el medio ambiente. En este sentido, en relación a las infraestructuras del transporte, y de modo muy especial en los aeropuertos, el monitorado del ruido se convierte en una herramienta de suma importancia para la gestión del ruido, la planificación del territorio y la adopción de medidas correctoras (planes de acción). Los terminales de monitorado de ruido ambiental, que se utilizan fundamentalmente en los aeropuertos, realizan una medición del nivel de ruido ambiental, y evalúan la contaminación que generan las aeronaves al ambiente sonoro general. Para ello, deben ser capaces de medir la evolución temporal del ruido y discriminar aquellos eventos sonoros que se correspondan con el paso de un avión frente al ruido de fondo. Los requisitos aplicables a las unidades de medida, así como los procedimientos de medida implicados han sido descritos recientemente en normas internacionales, como la ISO 20906 o la ARP 4721. Es precisamente en el aspecto relacionado con la discriminación del origen del ruido, donde los sistemas existentes presentan las principales carencias, ya que, un sistema básico de monitorado de ruido realiza la detección de eventos a partir de las medidas de nivel sonoro, evaluando los incrementos de nivel mediante la utilización de umbrales. Dichos umbrales relacionan nivel sonoro y tiempo, de forma que se efectúa el marcado de eventos cuando el nivel de presión sonora, Lp(t), supera un valor determinado durante, al menos, un determinado intervalo temporal. Uno de los principales objetivos de esta tesis se centra en el análisis de los sistemas que existen para la discriminación de ruido de aeronaves, y en el análisis de las contribuciones de estos sistemas sobre la incertidumbre de la medida y el reporte de resultados. Para la consecución de dicho objetivo, se ha definido un modelo de incertidumbre que permite evaluar los diferentes factores de influencia y realizar una cuantificación de la incertidumbre para diferentes escenarios. Durante este proceso se han definido y analizado los conceptos de incertidumbre de detección e incertidumbre de identificación, ambos derivados del diagrama de bloques que propone la norma ISO 20906 para la discriminación del ruido producido por los aviones y el procesado de datos. Asimismo, se pretende abordar el problema de la discriminación de aeronaves con un enfoque novedoso, que permita mejorar el rendimiento de los sistemas y reducir la incertidumbre. Mediante un sistema basado en reconocimiento de patrones uniclase, se aborda esta tarea en base al análisis de la semejanza entre la señal sonora registrada y el sonido que producen los aviones, dejando al margen la magnitud del sonido. Las técnicas de reconocimiento de patrones, y reconocimiento automático de habla, han sido aplicadas previamente al reconocimiento de fuentes de ruido ambiental. Algunos de estos proyectos se han centrado en el ruido de aviones, pero la novedad en esta tesis radica en la aplicación de clasificadores uniclase en un sistema que detecta eventos sonoros gracias a la clasificación de los fragmentos que lo componen. Actualmente los sistemas de gestión de ruido aeroportuario enlazan los datos de ruido proporcionados por las estaciones de monitorado con los datos procedentes del sistema seguimiento de los vuelos de los aviones mediante radar. Este tipo de sistemas es el que ha presentado mayor aceptación y ha sido implantado en los sistemas de monitorado de ruido de los principales aeropuertos internacionales. Sin embargo, este enfoque requiere de equipamiento que permita realizar el seguimiento de la posición de avión, y, dado que únicamente utilizan los niveles sonoros medidos para enlazarlos con el avión que los origina, no será capaz de detectar errores derivados de la presencia de una fuente sonora secundaria cuando existe un avión en la zona. El sistema que se plantea con la realización de esta tesis supone un avance debido a que permite eliminar del proceso de discriminación los umbrales de nivel sonoro, analizando única y exclusivamente la semejanza entre las señales comparadas. De esta manera se pretende mejorar las tasas de error en la identificación, e incluir umbrales de semejanza que permitan eliminar los umbrales de nivel sonoro en el proceso de detección. La implementación del sistema complementando al resto de sistemas del aeropuerto, permitirá la ampliación de las capacidades en el monitorado y la reducción de los costes en las campañas de medición desatendida. Al tiempo que se introducen las técnicas de reconocimiento de patrones en los sistemas de discriminación de los monitores de ruido, se pretende sacar partido de las posibilidades abiertas para dotar al sistema de capacidades adicionales, como es el caso de la detección del ruido de reversa, que se produce tras el aterrizaje de los aviones. La reversa se activa tras el contacto con tierra por parte de los aviones, para reducir la velocidad y acortar la distancia de frenado de los aviones. Esta práctica se usa de forma habitual en los aterrizajes, especialmente en los casos en los que la salida que debe tomar el avión rumbo al terminal se encuentra demasiado próxima al punto de aterrizaje. El empuje inverso se debe a una alteración en el flujo normal de aire que atraviesa los motores, que produce un violento choque contra la carcasa del motor, originando vibraciones y flujo turbulento que se convierte en ruido. El ruido de reversa puede alcanzar unos niveles mucho mayores que el propio aterrizaje, y sus características dinámicas y espectrales lo convierten en especialmente molesto. Por este motivo la utilización injustificada (salvo por motivos de seguridad) está prohibida o es desaconsejada en un gran número de aeropuertos, a nivel internacional (especialmente durante el período nocturno). Sin embargo, las autoridades aeroportuarias carecen de herramientas eficientes y fiables que permitan detectar la utilización de reversa, siendo este punto uno de los aspectos tratados en esta investigación

Network Topology and Protocol Design for Efficient Consensus in Sensor Networks

Doktorgradsavhandling ved Fakultet for teknologi og naturvitenskap, Universitetet i Agder, 2016In the new era of Internet of Things, complex sensor networks are becoming crucial to link the physical world to the Internet. These sensor networks, composed by hundreds or thousands of nodes, provide many important services to promote a heightened level of awareness about the area of interest such as in predictive maintenance, intelligent buildings, enhanced security systems, etc. In order to make these services possible, several signal processing tasks are needed to support their operation, some widely used examples of these tasks are parameter estimation, signal detection and target tracking. These tasks allow to improve the services by inferring missing data, reducing samples noise, etc., at the cost of some collaboration of the network nodes that implies their repeated communication over time. Most of these solutions are consensus-based strategies, which have recently attracted a great deal of research work because of its simplicity. These are in-network algorithms, where each node only exchanges information with its immediate neighbors and these are able to obtain global information as a function of some sensed data. A relevant example is the average consensus algorithm, which its goal is to obtain, in a distributed way, the average of the initial data. These algorithms avoid the need of performing all the computations at one or more sink nodes, thus, reducing congestion around them and incrementing the robustness of the network. In this dissertation, we focus on improving consensus algorithms in terms of different parameters and under different types of communications and network configurations. Each setting considered requires its own assumptions and methodologies, since the convergence conditions for each of them are related but different in general. In particular, in this work, all of the methodologies proposed are based on designing how the underlying communications are performed. In static networks, where the asymptotic convergence to the average value is easily ensured, a topology optimization can be a priori performed in terms of several relevant parameters. In particular, we optimize the network topology to make consensus algorithms fast and energy efficient. In this setting and for continuous systems, we derive a general framework to minimize several energy related functions under different network and nodes constraints To solve it, we propose a fractional convex-concave optimization problem with different constraints that leads to obtain the optimal topology in terms of the energy function considered. As a significant variation of the previous results, we also optimize the network topology in discrete systems. The discretization of the system introduces a weight matrix and certain step-size (related to the discrete increments of time) in the process. We show that if this step-size is small enough, the energy related problems stated before can be still casted as convex-concave fractional problems with the weight matrix as a unique optimization variable. As the step-size of the process increases in size, a discrete system requires a different approach. To solve it, we aim to find another formulation based on adding a constraint on the connectivity and solving the problem several times (for different values of the step-size). In addition, two low-complex methodologies with different computational requirements are proposed to a posteriori redesign an existing topology by the collaboration of the network nodes. On the contrary, in time-varying (random) networks, it is needed to guarantee a minimum accuracy of the algorithm, while maximizing the number of simultaneous exchanges of data to ensure fast convergence. Regarding random and asymmetric communications, we propose a novel gossip algorithm, which is based on the residual information that is generated when an asymmetric communication is performed. We exploit this information to preserve the summation of the process and accelerate it. Moreover, our proposal is useful in the case of having both unicast and broadcast communications, presenting faster convergence in both schemes than existing approaches in the related literature. When the problem of wireless interferences constraining the communications is additionally taken into account, we propose a novel and computationally efficient link scheduling protocol that correctly operates in the presence of secondary interference. Our protocol is easily implementable and does not require global knowledge of the network. The main objective of this new protocol is to be suitable for a cross-layer scheme in which the execution of the average consensus algorithm is favoured, ensuring necessary conditions for its convergence with certain accuracy. Additionally, the number of simultaneous links is additionally considered in order to make the convergence of the consensus process as fast as possible

E-comparisons: A new approach to round robin tests for environmental noise assessment in transport infrastructures

The increasing importance of pollutant noise has led to the creation of many new noise testing laboratories in recent years. For this reason and due to the legal implications that noise reporting may have, it is necessary to create procedures intended to guarantee the quality of the testing and its results. For instance, the ISO/IEC standard 17025:2005 specifies general requirements for the competence of testing laboratories. In this standard, interlaboratory comparisons are one of the main measures that must be applied to guarantee the quality of laboratories when applying specific methodologies for testing. In the specific case of environmental noise, round robin tests are usually difficult to design, as it is difficult to find scenarios that can be available and controlled while the participants carry out the measurements. Monitoring and controlling the factors that can influence the measurements (source emissions, propagation, background noise…) is not usually affordable, so the most extended solution is to create very effortless scenarios, where most of the factors that can have an influence on the results are excluded (sampling, processing of results, background noise, source detection…) The new approach described in this paper only requires the organizer to make actual measurements (or prepare virtual ones). Applying and interpreting a common reference document (standard, regulation…), the participants must analyze these input data independently to provide the results, which will be compared among the participants. The measurement costs are severely reduced for the participants, there is no need to monitor the scenario conditions, and almost any relevant factor can be included in this methodolog