3,393 research outputs found
Influence of spatially heterogeneous deterioration patterns on strength and ductility of corroded reinforced concrete bridge piers
This work reports on some preliminary results obtained within the framework of a wide research project aimed to study the influence of the corrosion of in Reinforced Concrete (RC) piers on the overall seismic performances of bridges. In this context, after the statistical evaluation of a large database of real structures, a consistent set of bridges and piers has been selected as a sample representative of typical bridge profiles, pier heights and cross-sections as well as of material properties. In the first part of the project, pushover analyses of isolated piers with different corrosion patterns and intensity are carried out to evaluate the residual strength and ductility of corroded piers. In the second part, nonlinear static and dynamic seismic analyses of bridges with corroded piers are carried out to evaluate the influence of the deterioration on the overall seismic performance. Due to specific environmental conditions exposure or to water percolation from the superstructures, it is often the case that corrosion is non-uniformly distributed over piers producing non-homogeneous spatial deterioration patterns. The nonlinear modeling of this type of situations represents specific challenges related to the description of the deterioration patterns and the calibration of material properties. To this end, a multi-level modeling approach based on fiber-based finite elements has been developed and implemented in a specific OpenSeesPy software that allows users to accurately model RC piers subject to arbitrary corrosion patterns, up to their ultimate limit states. In this work, a specific case study of a typical RC rectangular hollow bridge extracted from the mentioned above database subject to different corrosion intensity and patterns is studied. In particular, the influence of the corrosion-induced deterioration on residual strength and ductility are studied. Results show that depending on the intensity and on the patterns significant variations of both strength and ductility can be observed with respect to the undamaged conditions
Transcribing and annotating speech corpora for speech recognition: A three-step crowdsourcing approach with quality control
Large speech corpora with word-level transcriptions annotated for noises and disfluent speech are necessary for training automatic speech recognisers. Crowdsourcing is a lower-cost, faster-turnaround, highly scalable alternative for expert transcription and annotation. In this paper, we showcase our three-step crowdsourcing approach motivated by the importance of accurate transcriptions and annotations.info:eu-repo/semantics/publishedVersio
Discovery of optical pulsations in V2116 Ophiuchi/GX 1+4
We report the detection of pulsations with s period in V2116 Oph,
the optical counterpart of the low-mass X-ray binary GX 1+4. The pulsations are
sinusoidal with modulation amplitude of up to 4% in blue light and were
observed in ten different observing sessions during 1996 April-August using a
CCD photometer at the 1.6-m and 0.6-m telescopes of Laborat\'orio Nacional de
Astrof\'{\i}sica, in Brazil. The pulsations were also observed with the
fast photometer. With only one exception the observed optical periods are
consistent with those observed by the BATSE instrument on board the Compton
Gamma Ray Observatory at the same epoch. There is a definite correlation
between the observability of pulsations and the optical brightness of the
system: V2116~Oph had magnitude in the range when the pulsed
signal was detected, and when no pulsations were present. The
discovery makes GX 1+4 only the third of accretion-powered X-ray
pulsars to be firmly detected as a pulsating source in the optical. The
presence of flickering and pulsations in V2116 Oph adds strong evidence for an
accretion disk scenario in this system. The absolute magnitude of the pulsed
component on 1996 May 27 is estimated to be . The implied
dimensions for the emitting region are 1.1 R_{\sun}, 3.2 R_{\sun}, and 7.0
R_{\sun}, for black-body spectral distributions with K, K, and K, respectively.Comment: 9 pages, 3 figures in PostScript, latex, accepted for publication on
the Astrophysical Journal Letter
Avaliação da fertilidade do solo e do estado nutricional da cultura do caju em assentamentos do município de Caraúbas-RN
O município de Caraúbas-RN, apesar de estar situado numa área considerada de baixa aptidão para a cultura do caju, chega a produzir mais de 100.000 kg de castanhas/ano, sendo esta atividade de grande importância social e econômica, pois está diretamente relacionada com a sobrevivência de 114 famílias instaladas em assentamentos e comunidades rurais do município. O levantamento da fertilidade do solo e dos teores foliares de nutrientes tem a finalidade de identificar a existência de deficiências ou excessos destes para direcionar as pesquisas regionais de adubação a serem programadas. Diante do exposto, o principal objetivo deste trabalho foi avaliar a fertilidade dos solos cultivados com caju e o estado nutricional da cultura em três assentamentos do município de Caraúbas, Estado do Rio Grande do Norte. Os dados foram coletados em áreas dos Assentamentos Morada Nova, Petrolina e Santa Agostinha localizados no município de Caraúbas, região Oeste do Estado do RN. Realizou-se a amostragem de solo em cada área, retirando-se 20 amostras simples por lote, nas profundidades de 0-20 e 20-40 cm, onde se determinou: teores de carbono (C), potássio (K), sódio (Na), cálcio (Ca), magnésio (Mg) e alumínio (Al) trocáveis, fósforo (P) disponível; acidez potencial (Al + H) e pH em água. A partir dessas análises calcularamse a CTC total (T) e efetiva (t), soma de bases (SB), saturação por bases (V) e por alumínio (m) e porcentagem de sódio trocável (PST). Para avaliação do estado nutricional da cultura, foram escolhidas, aleatoriamente, 10 plantas por área homogênea (lote). Foram determinados os teores de P, Ca, Mg, K e Na. Calcularam-se os seguintes parâmetros estatísticos: média, valores mínimos e máximos, e coeficiente de variação. Todas as plantas apresentaram teores de P e K muito abaixo dos considerados adequados para a cultura do caju; os teores foliares de Ca e Mg, em média, foram considerados adequados para a cultura; existe a necessidade do desenvolvimento de pesquisas na área dos assentamentos com a finalidade de desenvolver ou adaptar técnicas de manejo para a cultura, para melhorar o estado nutricional das plantas e, conseqüentemente, a produção e qualidade dos frutos produzidos nesses assentamentos
Astrometry of the main satellites of Uranus: 18 years of observations
We determine accurate positions of the main satellites of Uranus: Miranda,
Ariel, Umbriel, Titania, and Oberon. Positions of Uranus, as derived from those
of these satellites, are also determined. The observational period spans from
1992 to 2011. All runs were made at the Pico dos Dias Observatory, Brazil.
We used the software called Platform for Reduction of Astronomical Images
Automatically (PRAIA) to minimise (digital coronography) the influence of the
scattered light of Uranus on the astrometric measurements and to determine
accurate positions of the main satellites. The positions of Uranus were then
indirectly determined by computing the mean differences between the observed
and ephemeris positions of these satellites. A series of numerical filters was
applied to filter out spurious data. These filters are mostly based on the
comparison between the positions of Oberon with those of the other satellites
and on the offsets as given by the differences between the observed and
ephemeris positions of all satellites.
We have, for the overall offsets of the five satellites, -29 (+/-63) mas in
right ascension and -27 (+/-46) mas in declination. For the overall difference
between the offsets of Oberon and those of the other satellites, we have +3
(+/-30) mas in right ascension and -2 (+/-28) mas in declination. Ephemeris
positions for the satellites were determined from DE432+ura111. Comparisons
using other modern ephemerides for the solar system -INPOP13c- and for the
motion of the satellites -NOE-7-2013- were also made. They confirm that the
largest contribution to the offsets we find comes from the motion of the
barycenter of the Uranus system around the barycenter of the solar system, as
given by the planetary ephemerides. Catalogues with the observed positions are
provided.Comment: 13 pages, 21 figure
Equações empíricas para a estimativa da evapotranspiração de referência diária para Parnaíba e Santa Rosa do Piauí.
A estimativa da evapotranspiração de referência (ETo) é importante para o manejo da água e para o dimensionamento dos sistemas de irrigação, sendo necessário estudos, ajustes e avaliações para a sua plena utilização. O objetivo deste trabalho foi o de desenvolver equações empíricas para estimativa de ETo, a partir de dados diários oriundos de estações agrometeorológicas automáticas, por meio da técnica de análise de regressão linear múltipla para estimar a ETo em Parnaíba e Santa Rosa do Piauí, PI. Os elevados coeficientes de determinação e os reduzidos erros padrão de estimativa indicam que as equações empíricas propostas podem ser aplicadas para a estimativa da ETo diária nos dois locais estudados
Comparação de métodos empíricos de estimativa da evapotranspiração de referência para Piripiri, Piauí.
O cálculo diário da evapotranspiração de referência (ETo) é a base para se determinar a lâmina de irrigação a ser aplicada aos cultivos. O método padrão de estimativa da ETo por Penman-Monteith/FAO (PM), por usar muitos elementos climáticos, torna os cálculos mais onerosos e de difícil aplicação em diversos locais. Este trabalho objetivou comparar e avaliar o desempenho de métodos empíricos de estimativa da ETo, de modo a proporcionar maior acessibilidade à estimativa de ETo pelos produtores do Perímetro Irrigado do Açude Caldeirão, em Piripiri, Piauí. Os dados climáticos foram obtidos em uma estação agrometeorológica automática localizada dentro do Perímetro (latitude 04º20?00,4?S e longitude 41º43'52?W), de 01/01/2005 a 31/12/2009. Os métodos de estimativa de ETo avaliados foram os de Thornthwaite (TH), Blaney-Criddle (BC), Jensen-Haise (JH), Priestley-Taylor (PT), Hargreaves-Samani (HS) e Método da Radiação (Rad), admitindo como método padrão para comparação o de Penman-Monteith/FAO. Foram realizados cálculos do erro padrão da estimativa (EPE), dos coeficientes de determinação, correlação, índice de Willmott e de confiança entre os métodos avaliados e o padrão. Todos os métodos de estimativa de evapotranspiração de referência obtiveram desempenho ótimo quando comparados a PM, porém TH, BC, JH e Rad superestimaram os valores de ETo diária. Os métodos HS e PT apresentaram os menores EPE, sendo estes indicados para o adequado manejo de irrigação no Perímetro Irrigado do Açude Caldeirão.CONBEA 2013
Desmoplastic Melanoma: Report of 5 Cases
Background. The clinical presentation of desmoplastic melanoma is often challenging. We report the experience of the Melanoma Unit of Spedali Civili University Hospital of Brescia, Italy. Method. Study subjects were drawn from 1770 patients with histologica confirmed melanoma. Within this group, desmoplastic melanoma developed in 5 patients. For each diagnosed melanoma, histological characteristics, treatment, and outcomes were evaluated. Results. Of the 5 patients described in this study, 2 were males and 3 females. The average age was 62.4 years ranging from 56 to 68 years. Breslow thickness ranged from 2.1 to 12 mm with a mean thickness of 5.8 mm. Primary treatment of 5 patients included a wide local excision of their primary lesions. Conclusions. Desmoplastic melanoma is a rare neoplasm which clinically may mimic other tumours or cutaneous infiltrate of uncertain significance. The diagnosis is hiastopathological and radical resection is necessary
An analysis of rainfall based on entropy theory
The principle of maximum entropy can provide consistent basis for analyzing rainfall and for geophysical processes in general. The daily rainfall data was assessed using the Shannon entropy for a 10-years period from 189 stations in the northeastern region of Brazil. Mean values of marginal entropy were computed for all observation stations and isoentropy maps were then constructed for delineating annual and seasonal characteristics of rainfall. The Mann-Kendall test was used to evaluate the long-term trend in marginal entropy for two sample stations. The marginal entropy values of rainfall were higher for locations and periods with highest amount of rainfall. The results also showed that the marginal entropy decreased exponentially with increasing coefficient of variation. The Shannon theory produced spatial patterns which led to a better understanding of rainfall characteristics throughout the northeastern region of Brazil. Trend analysis indicated that most time series did not have any significant trends
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