2,619 research outputs found
Phase diagram of an Ising model with competitive interactions on a Husimi tree and its disordered counterpart
We consider an Ising competitive model defined over a triangular Husimi tree
where loops, responsible for an explicit frustration, are even allowed. After a
critical analysis of the phase diagram, in which a ``gas of non interacting
dimers (or spin liquid) - ferro or antiferromagnetic ordered state'' transition
is recognized in the frustrated regions, we introduce the disorder for studying
the spin glass version of the model: the triangular +/- J model. We find out
that, for any finite value of the averaged couplings, the model exhibits always
a phase transition, even in the frustrated regions, where the transition turns
out to be a glassy transition. The analysis of the random model is done by
applying a recently proposed method which allows to derive the upper phase
boundary of a random model through a mapping with a corresponding non random
one.Comment: 19 pages, 11 figures; content change
Planeamento de uma mobilidade urbana sustentável e eficiente: metodologia para avaliar a descarbonização do setor
No âmbito da aplicação dos fundos europeus estruturais e de investimento no período de programação 2014-2020 torna-se necessário, na temática da mobilidade, dar cumprimento ao seguinte Objetivo Temático ?Apoiar a transição para uma economia de baixo teor de carbono em todos os sectores?, que estabelece, entre outras, a Prioridade de Investimento 4.5, que visa a promoção de estratégias de baixo teor de carbono para todos os tipos de territórios, nomeadamente as zonas urbanas, incluindo a promoção da mobilidade urbana multimodal sustentável e eficiente. Da análise da metodologia existente para quantificar o volume de emissões do setor dos transportes utilizado pela Direção Geral de Energia e Geologia é possível concluir que a determinação desses valores não permite definir estratégias que visem a redução das emissões neste setor. Deste modo, a metodologia desenvolvida permitirá estimar o valor correspondente a um número de viagens de transporte motorizados para um determinado volume de emissões de GEE (tonCO2) e assim definir o quadro da repartição modal mais eficiente para os padrões de mobilidade urbana a atingir por um, ou vários, municípios de uma região. Assim, neste artigo será apresentada uma metodologia que vise estimar a diminuição do número de viagens em transporte individual, que possam ser transferidas para modos de transporte mais eficientes e menos poluentes, como o autocarro e os modos ativos, de modo a que se possa atingir o valor meta de CO2 para 2023.info:eu-repo/semantics/publishedVersio
Planeamento de itinerários para modos suaves de transporte : rotas saudáveis
A aplicação dos princípios da sustentabilidade à mobilidade urbana implica a adopção de um conjunto de
políticas e medidas que fomentem a utilização de modos de transporte menos poluentes, mais económicos e
equitativos, ou seja, mais sustentáveis, que se traduzem no modo pedonal e ciclável, vulgo modos suaves de
transporte. Neste trabalho é apresentada e descrita a metodologia subjacente ao conceito de geração de rotas
saudáveis, que integra a contaminação dos eixos de circulação dos modos suaves de acordo com os níveis de
poluição sonora e atmosférica do meio urbano em que estão inseridos, com o objectivo de reduzir o nível de
exposição e risco de desenvolverem doenças respiratórias e cardiovasculares. Pretende-se, com estas rotas
saudáveis, captar e fomentar a utilização dos modos suaves para realização da maioria das deslocações em meio
urbano.The application of sustainable principles on the definition of policies and actions on urban mobility relies on the
promotion of less pollutant, economic, and more equitable modes of transport, such as walking and cycling, also
known as smooth modes of transport. In this paper, a methodology is presented and described under the concept
of healthy route generation. This integrates the contamination of the smooth modes of transport network,
according to the noise levels and air pollution indices of the urban environment in which it is located, with the
main objective of reducing the exposure level and the risk of development of respiratory and cardiovascular
diseases. Healthy routes can be applied to attract and promote the use of smooth modes of transport in a regular
basis in urban environments
Sustainable mobility in a mid-sized city : a multimodal approach
Transportation systems of mid-sized cities play an important role in guaranteeing a
sustainable development of the surrounding areas. Sustainable principles applied to the
study of urban mobility involve the consideration of all different travel modes, as well as
the territory where all modes interact and establish points of connection. Consequently, a
multimodal approach is necessary, especially to encourage a more effective and sustainable
use of the system and to promote greener modes of transport, like pedestrians and cyclists,
or other less pollutant modes.
The paper presents a case study on the city of Viana do Castelo, which is located in the
North of Portugal with approximately 37000 inhabitants in 33.6 square kilometres. It is
considered a mid-sized city with a large number of different transport modes, namely
trains, buses, ferryboats, cyclists and pedestrians, which provide an opportunity to develop
and apply a multimodal approach towards a more sustainable city environment
The role of public transport in the achievement of urban sustainable mobility in mid-sized cities
Mid-sized cities or villages often have important issues associated with the relation
between demand and supply of transport, due to its own spatial dimension and also due to
the territory sprawl derived from years of deficient land use planning. Traditionally, public
transport was mainly designed to cover and serve the entire municipality, giving a rural
character to this service. Presently, some of these cities are sufficiently large to support the
adoption of an urban public transport. The main question is how to create a public transport
service in mid-sized cities integrated with the existing transport and parking system, so that
more sustainable patterns of mobility can be achieved. For this purpose, a case study will
be presented regarding the creation and planning of an urban public transport service for
the city of Barcelos, located in Northern Portugal
Electric mobility in Portugal: the beginning
This paper aims to address the main questions related with electric mobility in Portugal. For this, the four principal strategic areas of the electric mobility program in Portugal will be presented, such as the business model, infrastructure, incentives and communication. On the other hand, the current legislation will be succinctly described, as well as the priorities defined in the Program for Electric Mobility. The different phases of implementation of this Program will be identified, with particular emphasis to the measures and incentives in the pilot-phase to promote the use of the electric vehicle. Lastly, the adopted Model for Electric Mobility will be presented in terms of the main components of the model, value chain, actors, charging network and operation of the pilot-phase
The influence of air pollution in the selection of healthy routes forwalking and cycling
In this paper, a model for generation of alternative routes for walking and cycling will be
presented, taking into account the impact of environmental noise and air pollution in urban
areas. The main objective resides in the reduction of the exposure level and risk of
development of respiratory and cardiovascular diseases. Depending on the type of
optimization criteria, the output of the model could be the least noisy, the least air-polluted
or the healthiest route. The formulation of the model to generate healthy routes is initiated
with the generation of pollution maps, followed by the contamination of the walking and
cycling network and finally outputs the generated different types of healthy routes. An
application of the overall model will be presented in a case study example developed for a
central area of the city of Braga, in northern Portugal, with special focus on the influence
of air pollution in the selection of healthy routes in urban environments
Sustainable mobility in urban areas of midisized municipalities.
Publicado em "Recent Advances in Engineering Mechanics, Structures and Urban Planning" (ISBN : 978-1-61804-165-4) ; Mathematics and Computers in Science and Engineering Series, 8 (ISSN : 2227-4588)Conventionally, midsized cities in Portugal, as well as in other European countries, are characterized
by higher densities of population and households in relation to its surroundings, mainly at the municipality
level. On the other hand, the city itself is concentrated in a small urban agglomerate where most of the health,
educational, financial and administrative facilities are located, resulting in major traffic generators and central
active points of a regional coverage. Land use and mobility planning represents a key issue to achieve a more
sustainable urban transportation system. For that, sustainable mobility plans can be considered the first tool
towards action. These plans can be formally divided in three phases: the diagnosis of the current situation, the
definition of the objectives and concept of intervention in terms of mobility, and the development of proposals
for intervention. In order to describe the planning process framework, several proposals were developed in
municipal sustainable mobility plans for four different types of urban agglomerates of midsized cities in
Northern Portugal, namely in the town of Póvoa de Lanhoso
Public transport decarbonization via urban bus fleet replacement in Portugal
The transport sector accounts for around one-quarter of the GHG emissions in Europe, and, in Portugal, it represents almost one-third of the total emissions to the atmosphere. Unfortunately, these emissions have increased in recent years. Hence, cities and countries need plans to decarbonize their public transport fleets, and, more specifically, to replace fossil-fueled buses with electric buses that produce zero CO2 emissions. Thus, the main objective of this paper is to present a method to decarbonize the bus fleet in Portugal by a scheduled replacement of the current fleet, which is fueled by fossil fuels, with a completely electric fleet, in fourteen years. The study shows that it is possible to replace all Portuguese urban bus fleets with electric vehicles considering that all vehicles will be replaced when reaching the age of 14 years. Replacing the urban bus fleet with zero-emission buses would aid policymakers and bus companies to reduce the GHGs, and therefore contribute to fulfilling the Sustainable Development Goals of the United Nations 2030 Agenda for Sustainable Development, namely, Goal 13—take urgent action to combat climate change and its impacts.This research was funded by Fundação Mestre Casais (FMC-E#1-2021)
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