Capacity Enhancement Using MIMO Antenna Arrays in Realistic Macro-Cellular Urban Environment

In MIMO systems the antenna array configuration in the BS and MS has a large influence on the available channel capacity. In this paper, we first introduce a new Frequency Selective (FS) MIMO framework for macro-cells in a realistic urban environment. The MIMO channel is built over a previously developed directional channel model, which considers the terrain and clutter information in the cluster, line-of-sight and link loss calculations. Next, MIMO configuration characteristics are investigated in order to maximize capacity, mainly the number of antennas, inter-antenna spacing and SNR impact. Channel and capacity simulation results are presented for the city of Lisbon, Portugal, using different antenna configurations. Two power allocations schemes are considered, uniform distribution and FS spatial water-filling. The results suggest optimized MIMO configurations, considering the antenna array size limitations, specially at the MS side.

Improving a Cluster Based Directional Channel Model in Realistic Macro-Cell Environment

In this paper a realistic directional channel model that is an extension of the COST 273 channel model is presented. The model uses a cluster of scatterers and visibility region generation based strategy with increased realism, due to the introduction of terrain and clutter information. New approaches for path-loss prediction and line of sight modeling are considered, affecting the cluster path gain model implementation. The new model was implemented using terrain, clutter, street and user mobility information for the city of Lisbon, Portugal. Some of the model's outputs are presented, mainly path loss and small/large-scale fading statistics.

Indoor school environment: easy and low cost to assess inorganic pollutants

Total particulate matter (TPM) was passively collected inside two classrooms of each of five elementary schools in Lisbon, Portugal. TPM was collected in polycarbonate filters with a 47 mm diameter, placed inside of uncovered plastic petri dishes. The sampling period was from 19 May to 22 June 2009 (35 days exposure) and the collected TPM masses varied between 0.2 mg and 0.8 mg. The major elements were Ca, Fe, Na, K, and Zn at μg level, while others were at ng level. Pearson′s correlation coefficients above 0.75 (a high degree of correlation) were found between several elements. Soil-related, traffic soil re-suspension and anthropogenic emission sources could be identified. Blackboard chalk was also identified through Ca large presence. Some of the determined chemical elements are potential carcinogenic. Quality control of the results showed good agreement as confirmed by the application of u-score test.

Levantamento das metodologias (ensaios e medições acústicas) utilizadas por entidades acreditadas: estado da arte

O ruído é, por definição, um som desagradável ou indesejável que perturba o ambiente, contribuindo para o mal-estar físico e psíquico, podendo pôr em causa a saúde do ser humano. As situações de exposição nos espaços de repouso, lazer e trabalho a valores sonoros elevados, especialmente nos meios urbanos e suburbanos, têm-se multiplicado. Por outro lado, o desenvolvimento cultural dos cidadãos, cada vez mais cientes do direito à qualidade de vida, tem originado um aumento das exigências de conforto, influenciado directamente pela qualidade dos edifícios que habitam. Através da publicação do Regulamento Geral Sobre o Ruído – RGR – (aprovado pelo Decreto Lei nº251/87 de 24 de Junho) bem como o Regulamento dos Requisitos Acústicos dos Edifícios – RRAE - (aprovado pelo Decreto Lei nº129/02 de 11 de Maio), com as devidas alterações no Decreto-lei nº96/08, de 9 de Junho, foi permitido relacionar um conjunto de disposições normativas e legais, permitindo o estabelecimento de condições para a verificação das exigências fundamentais associadas ao conforto acústico dos edifícios (integração urbanística, isolamento sonoro a sons aéreos, isolamento a sons de percussão, exposição ao ruído durante o trabalho), justificando assim a necessidade da existência de regulamentação pelo facto da saúde dos indivíduos também se encontrar relacionada ao conforto acústico. Na presente dissertação, pretende-se dar um contributo para a elaboração da avaliação e certificação do comportamento acústico de edifícios de habitação através da definição dos principais aspectos a avaliar neste processo. Para tal, foi retratado o actual estado da arte e foi feito um levantamento das metodologias utilizadas pelas entidades acreditadas para os ensaios de acústica, tendo em conta a normalização e regulamentação existente, de maneira a obter o panorama destes diagnósticos de conforto acústico para a verificação da sua conformidade com as exigências regulamentares.

Unit Commitment in a Competitive and Emission Constrained Environment

This paper is on the unit commitment problem, considering not only the economic perspective, but also the environmental perspective. We propose a bi-objective approach to handle the problem with conflicting profit and emission objectives. Numerical results based on the standard IEEE 30-bus test system illustrate the proficiency of the proposed approach.

Tools for testing the Solvency Capital Requirement for life insurance

Longevity risk is one of the major risks that an insurance company or a pension fund has to deal with and it is expected that its importance will grow in the near future. In agreement with these considerations, in Solvency II regulation the Standard formula furnished for calculating the Solvency Capital Requirement explicitly considers this kind of risk. According to the new European rules in our paper we suggest a multiperiod approach to evaluate the SCR for longevity risk. We propose a backtesting framework for measuring the consistency of SCR calculations for life insurance policies.

Assessment of exposure to airborne ultrafine particles in the urban environment of Lisbon, Portugal

The aim of this study was the assessment of exposure to ultrafine in the urban environment of Lisbon, Portugal, due to automobile traffic, and consisted of the determination of deposited alveolar surface area in an avenue leading to the town center during late spring. This study revealed differentiated patterns for weekdays and weekends, which could be related with the fluxes of automobile traffic. During a typical week, ultrafine particles alveolar deposited surface area varied between 35.0 and 89.2 μm2/cm3, which is comparable with levels reported for other towns such in Germany and the United States. These measurements were also complemented by measuring the electrical mobility diameter (varying from 18.3 to 128.3 nm) and number of particles that showed higher values than those previously reported for Madrid and Brisbane. Also, electron microscopy showed that the collected particles were composed of carbonaceous agglomerates, typical of particles emitted by the exhaustion of diesel vehicles. Implications: The approach of this study considers the measurement of surface deposited alveolar area of particles in the outdoor urban environment of Lisbon, Portugal. This type of measurements has not been done so far. Only particulate matter with aerodynamic diameters <2.5 (PM2.5) and >10 (PM10) μm have been measured in outdoor environments and the levels found cannot be found responsible for all the observed health effects. Therefore, the exposure to nano- and ultrafine particles has not been assessed systematically, and several authors consider this as a real knowledge gap and claim for data such as these that will allow for deriving better and more comprehensive epidemiologic studies. Nanoparticle surface area monitor (NSAM) equipments are recent ones and their use has been limited to indoor atmospheres. However, as this study shows, NSAM is a very powerful tool for outdoor environments also. As most lung diseases are, in fact, related to deposition of the alveolar region of the lung, the metric used in this study is the ideal one.

A risk-averse optimization model for trading wind energy in a market environment under uncertainty

In this paper, a stochastic programming approach is proposed for trading wind energy in a market environment under uncertainty. Uncertainty in the energy market prices is the main cause of high volatility of profits achieved by power producers. The volatile and intermittent nature of wind energy represents another source of uncertainty. Hence, each uncertain parameter is modeled by scenarios, where each scenario represents a plausible realization of the uncertain parameters with an associated occurrence probability. Also, an appropriate risk measurement is considered. The proposed approach is applied on a realistic case study, based on a wind farm in Portugal. Finally, conclusions are duly drawn. (C) 2011 Elsevier Ltd. All rights reserved.

Fibras óticas de plástico em redes de acesso

Trabalho Final de Mestrado para obtenção do grau de Mestre em Engenharia de Eletrónica e Telecomunicações

Transformador para fonte de alta-tensão contínua

Dissertação para a obtenção do grau de Mestre em Engenharia Electrotécnica Ramo de Automação e Electrónica Industrial

Biblioteca de navegação autónoma baseada em campos de potencial

Trabalho de Final de Mestrado para obtenção do grau de Mestre em Engenharia Informática e de Computadores

Detecção de sectores cruzados e optimização de cobertura em redes LTE

Trabalho Final de Mestrado para obtenção do grau de Mestre em Engenharia de Electrónica e Telecomunicações

Horse stable environment: what to expect regarding fungi and particles occupational exposure?

The simultaneous presence of fungi and particles in horse stable environment can create a singular exposure condition because particles have been reported has a good carrier for microorganisms and their metabolites. This study intends to characterize this setting and to recognize fungi and particles occupational exposure.

Metaheuristic approach to the Holt-Winters optimal short term load forecast

Electricity short-term load forecast is very important for the operation of power systems. In this work a classical exponential smoothing model, the Holt-Winters with double seasonality was used to test for accurate predictions applied to the Portuguese demand time series. Some metaheuristic algorithms for the optimal selection of the smoothing parameters of the Holt-Winters forecast function were used and the results after testing in the time series showed little differences among methods, so the use of the simple local search algorithms is recommended as they are easier to implement.

Durability of ancient lime mortars in humid environment

Historical buildings are important fingerprints of the history and culture of a region and its communities. Climatic and environmental conditions are often very severe for construction materials, namely in presence of high humidity or in direct contact with water and salts. However, some historical buildings have in our days a very good condition, probably due to careful construction and/or accurate materials selection and to a specific technology. The knowledge of old mortars composition has a fundamental role on the preservation of cultural heritage, allowing information about the used materials, their performance in their specific environment, conducting to adequate and compatible materials to conservation purposes. This article presents two case studies of historical buildings with important defence functions in Lisbon coast, in which ancient lime mortars where used under severe seaside environmental actions. Mortar samples from these two case studies are characterized and the relationship of their composition with the good performance and high durability observed is discussed.