Bayesian Analysis of Simple Random Densities

A tractable nonparametric prior over densities is introduced which is closed under sampling and exhibits proper posterior asymptotics.Comment: 19 pages; 6 figure

Predictive analysis of microarray data

Microarray gene expression data are analyzed by means of a Bayesian nonparametric model, with emphasis on prediction of future observables, yielding a method for selection of differentially expressed genes and a classifier

Stochastic prediction of drought class transitions

This paper aims at the stochastic characterization of droughts applying Markov chains modeling to drought class transitions derived from SPI time series. Several sites in Southern Portugal having updated data on precipitation available were considered. The drought class probabilities, the expected residence time in each class of severity, the expected time for the transition between drought classes and the drought severity class predictions 1, 2, or 3 months ahead have been obtained. Those predictions are then compared with observed drought classes for the recent drought periods of 2003–2006. In addition, the estimation of the cumulated precipitation deficits, amount of monthly precipitation needed to decrease drought severity, and foreseen SPI values depending on different precipitation scenarios are also presented as complementing the prediction of drought class transitions

Analysis of the functional quality of pavements from texture measurements

The surface texture of a pavement, including uneveness, is largely determinant of drivers’safety and comfort. It is undoubtedly a major cause of road traffic accidents all over the world. Statistics show that one million killed and 50 million injured are reported every year by Competent Authorities. The effect of traffic noise has also become a critical public issue. On the road networking the surface characteristics of pavements also contributed to nearly 80-90% of roadway traffic noise. Not only engines or exhaust systems generate noise. The impact of tire-surface at speeds above 50 km/h also needs to be added to prime offenders. Functional requirements such as roadway safety, environmental quality, driving comfort and operating costs in the road network are assessed by indicators whose limits are continuously adjusted. The roadway texture is again a main intervenient. This paper aims at describing the texture indicators that can be used for the assessment of the texture of a pavement from a network point of view, based on profiles acquired at high speeds, including megatexture. First an overview of the concepts related to texture and the effects of texture, including unevenness, on safety, driving comfort, ride quality and environmental quality is given. Then, a case study related to a highly trafficked road in the north of Portugal is presented. This study is the second phase of a broader study that started with the analysis of the structural capacity of that road. In this second phase, a high speed profilometer was used to measure the pavement profile with a sampling rate which is considered to be adequate for the analysis of longitudinal profile, macrotexture and unevenness. Indicators such as the mean profile depth, the IRI and the rutting depth and the corresponding effects were addressed

Definição e características de superfícies de baixo ruído

As superfícies de pavimentos de baixo ruído são atualmente a medida de redução do ruído preferida pela maioria dos decisores por ser uma medida relativamente barata e por estarem na génese do ruído rodoviário. No entanto, para se averiguar se uma determinada superfície pode ser classificada de “baixo ruído” é fundamental a adoção de um sistema de classificação. Os principais objetivos deste trabalho são apresentar o problema da classificação de pavimentos, discutir a seleção de um limite ou de uma superfície de referência para apoiar a seleção de superfícies com desempenho acústico melhorado e identificar as características que conduzem a níveis de ruído de contato pneu-pavimento mais baixos, abordando-se particularmente a contribuição da macro e da megatextura.FEDE

Contribution of portuguese pavement surfaces to traffic noise

This paper aims at assessing the relative effect of Portuguese pavement surfaces on traffic noise. It presents the main results obtained with two distinct experiments, originally intended for other purposes, which address a significant number of thin layers and porous layers. These experiments included nine road surfaces: three of them were gap graded, three contained rubberized asphalt, one had porous asphalt and two had dense asphalt. On these road sections the tyre-road noise generated by two-axle heavy trucks and three-axle heavy trucks and several light vehicles at three levels of speed were measured by means of pass-by tests. Surface texture tests were also performed. The results focused on noise level variation versus speed and estimated noise level for each speed level versus type of surface. The best performances were achieved by gap graded mixtures with and without rubberized binder and small grain sizes. The fair behaviour shown by the porous asphalt indicates that the surface texture determined by the grain size seems to influence the noise level more than porosity

Análise da qualidade funcional e do impacto ambiental de uma estrada urbana

Este artigo tem por objectivos descrever os principais indicadores da qualidade funcional e da qualidade ambiental utilizados correntemente a nível da rede e apresentar um caso de estudo de uma estrada integrada em meio urbano reabilitada recentemente. Esta estrada contempla três camadas de desgaste diferentes, duas das quais com textura optimizada, com o objectivo de se estudar o seu efeito no ruído de contacto pneu/pavimento. Para a observação dos parâmetros técnicos de qualidade funcional (irregularidade, textura e resistência à derrapagem) foi utilizado um veículo do tipo multifunções e para a medição do ruído foram efectuadas medições junto à berma com a passagem de veículos a diversas velocidades. Com base nesses parâmetros, por um lado, prevê-se que a curto prazo seja necessário desenvolver-se actividades de conservação da qualidade funcional do pavimento. Por outro lado, verificou-se que as camadas de desgaste optimizadas reduzem consideravelmente o impacto do ruído de tráfego no ambiente

Access networks for mobility: a techno-economic model for broadband access technologies

The two main challenges for the access networks are the increasing bandwidth demand and mobility trends. The "triple play" services required (Internet, telephone and TV services) lead to a great increase in bandwidth demand. However, the existing access networks are not able to support this increase, and the capacity to delivery broadband services remain as a challenge ("last mile problem"). The access network remains a bottleneck in terms of the bandwidth and service quality it affords the end user. Besides the bandwidth, other great challenge to access networks is the mobility and the user need to have internet access anywhere and anytime. Then, the increasing demand of "quad-play" (also known as quadruple-play) services, including video, voice, data and mobility, have created new challenges to the modern broadband wireless/wired access networks. This document proposes a techno-economic model to support the new requirements of fixed and nomadic users

Game theoretic modeling of NGANs: impact of retail and wholesale services price variation

The increasing demand for broadband access leads operators to upgrade the existing access infrastructures (or building new access network). Broadband access networks require higher investments (especially passive infrastructures such as trenches/ducts and base station towers/masts), and before making any decision it is important to analyze all solutions. The selection of the best solution requires understanding the technical possibilities and limitations of the different access technologies, as well as understanding the costs of building and operating the networks. This study analyzes the effect of asymmetric retail and wholesale prices on operators’ NPV, profit, consumer surplus, welfare, retail market, wholesale market, and so on. For that, we propose a tehno-economic model complemented by a theoretic-game model. This tool identifies all the essential costs of building (and operating) access networks, and performs a detailed analysis and comparison of the different solutions in various scenarios. Communities, operators/service providers, and regulators can use this tool to compare different technological solutions, forecast deployment costs, compare diferente scenarios, and so on, and help them in making deployment (or regulatory) decisions. The game-theory analyses give a better understanding of the competition and its effect on the business case scenarios’ economic results