New maritime transport scenarios. Part II: fluctuations in shipping and new scenarios

This FAL Bulletin details the situation of the shipping industry and forms the second and final part of a larger document that begins with Issue No. 338, which puts the current status of maritime trade in context. Both documents fit into a series of bulletins about ports and maritime trade in the region and are, therefore, closely linked to Issue No. 337, which sets out the need for a new port governance in the region to address the new circumstances that have arisen in the maritime market.

Do demand and profitability stimulate capital accumulation? An analysis for Brazil

This article tests whether the profit share of gdp and capacity utilization affect capital accumulation in Brazil in the period 1950-2008 (in the sense of Granger causality). The methodology developed by Toda and Yamamoto (1995) is used to verify the Granger non-causality hypothesis. The results show that capacity utilization “Granger-causes” capital accumulation in the Brazilian economy and, also that the profit share of gdp does not “Granger-cause” the national investment-capital ratio. This corroborates the Kaleckian proposal based on the fundamental role of the accelerator, and suggests that the Brazilian economy can grow with either a concentration or a de-concentration of income, provided a suitable institutional arrangement is in place.

Towards a demand model for maritime passenger transportation in the Caribbean: a regional study of passenger ferry services

In this paper, the main factors that influence the demand for maritime passenger transportation in the Caribbean were studied. While maritime studies in the Caribbean have focused on infrastructural and operational systems for intensifying trade and movement of goods, there is little information on the movement of persons within the region and its potential to encourage further integration and sustainable development. Data to inform studies and policies in this area are particularly difficult to source. For this study, an unbalanced data set for the 2000-2014 period in 15 destinations with a focus on departing ferry passengers was compiled. Further a demand equation for maritime passenger transportation in the Caribbean using panel data methods was estimated. The results showed that this demand is related to the real fare of the service, international economic activity and the number of passengers arriving in the country by air.

Meta-analysis of the income and price elasticities of gasoline demand: public policy implications for Latin America

By means of a meta-analysis, this article sets out to estimate average values for the income and price elasticities of gasoline demand and to analyse the reasons for the variations in the elasticities reported by the literature. The findings show that there is publication bias, that the volatility of elasticity estimates is not due to sampling errors alone, and that there are systematic factors explaining these differences. The income and price elasticities of gasoline demand differ between the short and long run and by region, and the estimation can appropriately include the vehicle fleet and the prices of substitute goods, the data types and the estimation methods used. The presence of a low price elasticity suggests that a fuel tax will be inadequate to control rising consumption in a context of rapid economic growth.

Financing for climate change in Latin America and the Caribbean in 2014

Quantifying the resources mobilized to tackle climate change makes it possible to ascertain the region’s status in this area and the opportunities it offers. It provides countries with the detailed information they need to move forward and prepare to meet the objectives of the United Nations Framework Convention on Climate Change (UNFCCC). With accurate, up-to-date information on climate finance flows, countries can define their strategies for the transition to more sustainable development scenarios with a smaller environmental footprint and fiscal agents can identify gaps between supply and demand for specific financial instruments. The hope is that, rather than investment by fund providers and managers in sustainable initiatives with a smaller environmental footprint being an exception or anomaly, it will become a business model that gradually decouples economic development, investment and social inclusion from greenhouse gas (GHG) emissions.

Análise crítica de aspectos de modelagem matemática no planejamento da expansão a longo prazo de sistemas de transmissão

Pós-graduação em Engenharia Elétrica - FEIS

Planejamento de médio e longo prazo de sistemas de distribuição de energia elétrica com geradores distribuídos (GDs) considerando custos de confiabilidade, operação e expansão

Pós-graduação em Engenharia Elétrica - FEIS

Roteamento multicamada baseado em eficiência energética e qualidade de enlace para redes de sensores sem fio

A pesquisa apresentada nesta dissertação descreve a elaboração de um protocolo de roteamento para aplicações de Redes de Sensores Sem Fio (RSSF) em cidade inteligentes com forte restrição de energia e alta densidade de nodos. Através do estudo dos principais objetivos da comunicação de dados e do levantamento do estado-da-arte sobre os protocolos de roteamento e tecnologias para RSSF, a proposta contempla requisitos como: vazão de dados, confiabilidade de entrega e eficiência energética. A pesquisa apresenta em detalhes o protocolo AODV (Ad hoc On Demand Distance Vector), bem como sua relevância no contexto de RSSF devido a sua popularidade entre as plataformas de dispositivos comercializados. Além disso, são apresentados protocolos derivados do AODV, e a ausência de uma proposta robusta capaz de contemplar os requisitos levantados. O protocolo REL (Routing by Energy and Link Quality) é o resultado da pesquisa levantada e a proposta de solução para roteamento plano sob demanda baseado em eficiência energética e qualidade de enlace para prover um roteamento escalável, capaz de realizar balanceamento de carga e prolongar o tempo de vida da rede. O protocolo REL foi avaliado através de simulação e tesbed, a fim de garantir validação da proposta em ambiente real de escala reduzida e simulado de alta densidade. Os resultados mostraram que o protocolo REL apresenta considerável melhoria de entrega de dados através da escolha de enlaces confiáveis de transmissão e menos suscetíveis a erro, além de moderado consumo de energia capaz de prolongar o tempo de vida da rede, evitando a saturação prematura de nodos.

Cross-layer optimizations for multimedia distribution over Wireless Multimedia Sensor Networks and Flying Ad-Hoc Networks with quality of experience support

The proliferation of multimedia content and the demand for new audio or video services have fostered the development of a new era based on multimedia information, which allowed the evolution of Wireless Multimedia Sensor Networks (WMSNs) and also Flying Ad-Hoc Networks (FANETs). In this way, live multimedia services require realtime video transmissions with a low frame loss rate, tolerable end-to-end delay, and jitter to support video dissemination with Quality of Experience (QoE) support. Hence, a key principle in a QoE-aware approach is the transmission of high priority frames (protect them) with a minimum packet loss ratio, as well as network overhead. Moreover, multimedia content must be transmitted from a given source to the destination via intermediate nodes with high reliability in a large scale scenario. The routing service must cope with dynamic topologies caused by node failure or mobility, as well as wireless channel changes, in order to continue to operate despite dynamic topologies during multimedia transmission. Finally, understanding user satisfaction on watching a video sequence is becoming a key requirement for delivery of multimedia content with QoE support. With this goal in mind, solutions involving multimedia transmissions must take into account the video characteristics to improve video quality delivery. The main research contributions of this thesis are driven by the research question how to provide multimedia distribution with high energy-efficiency, reliability, robustness, scalability, and QoE support over wireless ad hoc networks. The thesis addresses several problem domains with contributions on different layers of the communication stack. At the application layer, we introduce a QoE-aware packet redundancy mechanism to reduce the impact of the unreliable and lossy nature of wireless environment to disseminate live multimedia content. At the network layer, we introduce two routing protocols, namely video-aware Multi-hop and multi-path hierarchical routing protocol for Efficient VIdeo transmission for static WMSN scenarios (MEVI), and cross-layer link quality and geographical-aware beaconless OR protocol for multimedia FANET scenarios (XLinGO). Both protocols enable multimedia dissemination with energy-efficiency, reliability and QoE support. This is achieved by combining multiple cross-layer metrics for routing decision in order to establish reliable routes.

Simulação e avaliação das tecnologias LTE e DSL como backhaul utilizando software OPNET

A crescente demanda por capacidade vem levando os padrões de comunicação sem-fio a prover suporte para a coexistência de macro e pico células. O backhaul, conexão entre a rede de acesso e o núcleo da rede, é de grande interesse neste contexto devido aos diversos desafios técnicos e financeiros envolvidos ao tentar satisfazer o crescente tráfego dos usuários. Fibra óptica e micro-ondas com linha de visada são as opções mais amplamente adotadas para o backhaul de macro-células. Contudo, em muitas situações de interesse prático, estas não são factíveis devido aos altos custos e logística envolvidos. Este trabalho avalia o backhaul de pico-células, focando primeiramente na utilização de cobre como backhaul. O simulador OPNET foi utilizado para avaliar os requerimentos de backhaul para redes móveis em cenários específicos considerando garantir qualidade de serviço para os diversos tipos de tráfego envolvidos. Assumindo demandas de tráfego para LTE e LTE-Advanced, as tecnologias VDSL2 e G.fast são avaliadas e os resultados mostram que mesmo com uma grande demanda de aplicações de vídeo de alta definição, estas tecnologias podem acomodar o tráfego no backhaul de pico-células. VDSL2 é capaz de prover as taxas requeridas para cenários de pico-células LTE, mas não é capaz de acomodar tráfego LTE-Advanced típico. Por outro lado, considerando as taxas atingidas com a tecnologia G.fast, o tráfego backhaul para pico-células LTE-Advanced pode ainda ser entregue com garantias de qualidade de serviço. Neste trabalho também é proposta uma solução para simulação de cenários contendo redes de acesso heterogêneas considerando backhaul LTE sem linha de visada. São demonstrados também os resultados de simulações no OPNET com o backhaul LTE proposto para validar a solução proposta como capaz de caracterizar o tráfego de ambas as tecnologias WiFi e LTE na rede de acesso de acordo com o tipo de serviço.

Wavelength assignment using a hybrid evolutionary computation to reduce cross-phase modulation

In this paper, we propose a hybrid methodology based on Graph-Coloring and Genetic Algorithm (GA) to solve the Wavelength Assignment (WA) problem in optical networks, impaired by physical layer effects. Our proposal was developed for a static scenario where the physical topology and traffic matrix are known a priori. First, we used fixed shortest-path routing to attend demand requests over the physical topology and the graph-coloring algorithm to minimize the number of necessary wavelengths. Then, we applied the genetic algorithm to solve WA. The GA finds the wavelength activation order on the wavelengths grid with the aim of reducing the Cross-Phase Modulation (XPM) effect; the variance due to the XPM was used as a function of fitness to evaluate the feasibility of the selected WA solution. Its performance is compared with the First-Fit algorithm in two different scenarios, and has shown a reduction in blocking probability up to 37.14% when considered both XPM and residual dispersion effects and up to 71.42% when only considered XPM effect. Moreover, it was possible to reduce by 57.14% the number of wavelengths.

Proposta de metodologia de auxílio à decisão utilizando conjuntos Fuzzy para repotenciação de PCHs

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Planejamento e otimização de sistemas energéticos para gestão econômica e ambiental de cidades

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)