12,718 research outputs found
Dynamic nonlinear analyses for the 4-storey infilled R/C frame: study of a retrofitting solution
A research project on assessment and retrofitting of R/C frame structures is currently being developed under the research programme of the ICONS TMR-research network. This paper presents and discusses the preliminary experimental results from a 4-storey bare frame representative of the common practice of 40~50 years ago in most south European countries and devotes special attention to the study of a retrofitting solution based on bracing and rubber dissipaters, which intends to increase stiffness and damping reducing consequently the earthquake deformation demands.O estudo aqui apresentado concentra-se numa solução de reforço de um pórtico utilizando contraventamentos (k-bracing) com perfis de aço em conjunto com elementos elastoméricos de dissipação. Os resultados das análises não lineares da estrutura com e sem alvenaria e com reforço são apresentados e discutidos. Na segunda parte da comunicação apresentam-se os resultados experimentais já disponíveis e discute-se o problema da modelação recorrendo aos resultados experimentais e comparando os resultados obtidos com diferentes tipos de modelos
Seismic analyses of a R/C building: study of a retrofitting solution
The preliminary experimental results from the tests on a 4-storey R/C frame structure are presented and discussed. The full-scale model is representative of the common practice of 40~50 years ago in most south European countries. Special attention is devoted to the study of a retrofitting solution based on bracing and rubber dissipaters, which intends to increase stiffness and damping reducing consequently the earthquake deformation demands
Seismic strengthening of beam-column joints with multidirectional CFRP laminates
An experimental program was carried out to analyse the potentialities of a technique based on the use of multidirectional CFRP laminates (MDL-CFRP) for the seismic repair and strengthening of reinforced concrete (RC) beam-column joints. This experimental program comprises cyclic tests on three full-scale RC joints, representative of interior beam-column connections in buildings. The joints were initially submitted to a cyclic test inducing a
damage pattern representative of a seismic event. Subsequently, they were repaired and
strengthened with MDL-CFRP. The strengthened joints were then tested for the same loading
history of the original ones up to their failure. The adopted strengthening technique uses the MDL-CFRP that are simultaneously glued and anchored to the concrete surfaces. This technique is called Mechanically Fastened and Externally Bonded Reinforcement (MF-EBR).
In the present study, the effectiveness of two different strengthening configurations was investigated. The tests are described and the main results are presented and analyzed
Ensuring successful introduction of Wolbachia in natural populations of Aedes aegypti by means of feedback control
The control of the spread of dengue fever by introduction of the
intracellular parasitic bacterium Wolbachia in populations of the vector Aedes
aegypti, is presently one of the most promising tools for eliminating dengue,
in the absence of an efficient vaccine. The success of this operation requires
locally careful planning to determine the adequate number of individuals
carrying the Wolbachia parasite that need to be introduced into the natural
population. The introduced mosquitoes are expected to eventually replace the
Wolbachia-free population and guarantee permanent protection against the
transmission of dengue to human.
In this study, we propose and analyze a model describing the fundamental
aspects of the competition between mosquitoes carrying Wolbachia and mosquitoes
free of the parasite. We then use feedback control techniques to devise an
introduction protocol which is proved to guarantee that the population
converges to a stable equilibrium where the totality of mosquitoes carry
Wolbachia.Comment: 24 pages, 5 figure
HIV-1 mother-to-child transmission in Brazil (1994\u20132016): a time series modeling
HIV-1 mother-to-child transmission (HIV-1 MTCT), is an important cause of children mortality worldwide. Brazil has been traditionally praised by its HIV/Aids program, which provides free-of-charge care for people living with HIV-1. Using public epidemiology and demographic databases, we aimed at modeling HIV-1 MTCT prevalence in Brazil through the years (1994\u20132016) and elaborate a statistical model for forecasting, contributing to HIV-1 epidemiologic surveillance and healthcare decision-making. We downloaded sets of live births and mothers\u2019 data alongside HIV-1 cases notification in children one year old or less. Through time series modeling, we estimated prevalence along the years in Brazil, and observed a remarkable decrease of HIV-1 MTCT between 1994 (10 cases per 100,000 live births) and 2016 (five cases per 100,000 live births), a reduction of 50%. Using our model, we elaborated a prognosis for each Brazilian state to help HIV-1 surveillance decision making, indicating which states are in theory in risk of experiencing a rise in HIV-1 MTCT prevalence. Ten states had good (37%), nine had mild (33%), and eight had poor prognostics (30%). Stratifying the prognostics by Brazilian region, we observed that the Northeast region had more states with poor prognosis, followed by North and Midwest, Southeast and South with one state of poor prognosis each. Brazil undoubtedly advanced in the fight against HIV-1 MTCT in the past two decades. We hope our model will help indicating where HIV-1 MTCT prevalence may rise in the future and support government decision makers regarding HIV-1 surveillance and prevention
Towards higher precision and operational use of optical homodyne tomograms
We present the results of an operational use of experimentally measured
optical tomograms to determine state characteristics (purity) avoiding any
reconstruction of quasiprobabilities. We also develop a natural way how to
estimate the errors (including both statistical and systematic ones) by an
analysis of the experimental data themselves. Precision of the experiment can
be increased by postselecting the data with minimal (systematic) errors. We
demonstrate those techniques by considering coherent and photon-added coherent
states measured via the time-domain improved homodyne detection. The
operational use and precision of the data allowed us to check for the first
time purity-dependent uncertainty relations and uncertainty relations for
Shannon and R\'{e}nyi entropies.Comment: 11 pages, 6 figures, 1 table, some results are extende
SiUinde: A collaborative platform to share conditions for near-the-shore activities
Currently, a large number of near-the-shore activities (sports and leisure) with a huge set of practitioners (growing everyday) exist. Also, the number of commercial companies, such as sport schools, that explore such type of costal activities are also on the rising. These kind of coastal activities are dependent of a set of conditions (in particular on what concerns the sun, the wind and waves) that affect directly or indirectly, the type of activity – mostly sportive – that can be practiced (surf, windsurf, paddle, kite surfing, canoeing, paragliding and others) on a given spot at a given time. This paper presents a platform, called SiUinde that was developed to allow users to collaboratively communicate reports about the coastal conditions, using several parameters, which include the wind conditions and the sea conditions, through a smartphone or tablet, permitting other users to have an in-depth and timely overview of the best places to enjoy their near-the-shore activities. This collaborative platform, takes advantage from the concept of collaborative intelligence and crowdsourcing to provide to the end-users the best possible recommendations for their preferred near-the-shore activities.info:eu-repo/semantics/submittedVersio
Relação solo-planta-atmosfera.
Importância da água para os vegetais; Relações da água no sistema solo-planta-atmosfera; O conceito de potencial químico da água; Caracterização quantitativa: umidade e potencial da água; Fluxo de água no solo; Infiltração da água no solo; Distribuição de água no solo sob irrigação; Soluções analíticas de escoamento da água no solo; Soluções numéricas de escoamento da água no solo; Estimativa do volume molhado do solo sob irrigação localizada; Distribuição radicular e absorção da água do solo; Balanço de água localizada no perfil do solo para estimativa da umidade; A água na planta - transpiração; Caracterização quantitativa das condições hídricas das plantas; Transporte de água na fase liquída na planta; Fluxo de vapor d'água entre as folhas e a atmosfera (transpiração); Fatores que afetam a absorção de água e a transpiração pelas plantas; Indicadores vegetais do grau de deficit hídrico; Potencial de água na folha; Transpiração e condutância foliar à difusão de vapor; Variações micromorfométricasde órgãos vegetais; Diferença de temperatura folha-ar
X-ray method to study temperature-dependent stripe domains in MnAs/GaAs(001)
MnAs films grown on GaAs (001) exhibit a progressive transition between
hexagonal (ferromagnetic) and orthorhombic (paramagnetic) phases at wide
temperature range instead of abrupt transition during the first-order phase
transition. The coexistence of two phases is favored by the anisotropic strain
arising from the constraint on the MnAs films imposed by the substrate. This
phase coexistence occurs in ordered arrangement alternating periodic terrace
steps. We present here a method to study the surface morphology throughout this
transition by means of specular and diffuse scattering of soft x-rays, tuning
the photon energy at the Mn 2p resonance. The results show the long-range
arrangement of the periodic stripe-like structure during the phase coexistence
and its period remains constant, in agreement with previous results using other
techniques.Comment: 4 pages, 4 figures, submitted to Applied Physics Letter
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