6,089 research outputs found
The impact of accretion disc winds on the optical spectra of cataclysmic variables
No full textMany high-state non-magnetic cataclysmic variables (CVs) exhibit blueshifted absorption or P-Cygni profiles associated with ultraviolet (UV) resonance lines. These features imply the existence of powerful accretion disc winds in CVs. Here, we use our Monte Carlo ionization and radiative transfer code to investigate whether disc wind models that produce realistic UV line profiles are also likely to generate observationally significant recombination line and continuum emission in the optical waveband. We also test whether outflows may be responsible for the single-peaked emission line profiles often seen in high-state CVs and for the weakness of the Balmer absorption edge (relative to simple models of optically thick accretion discs). We find that a standard disc wind model that is successful in reproducing the UV spectra of CVs also leaves a noticeable imprint on the optical spectrum, particularly for systems viewed at high inclination. The strongest optical wind-formed recombination lines are H alpha and He ii lambda 4686. We demonstrate that a higher density outflow model produces all the expected H and He lines and produces a recombination continuum that can fill in the Balmer jump at high inclinations. This model displays reasonable verisimilitude with the optical spectrum of RW Trianguli. No single-peaked emission is seen, although we observe a narrowing of the double-peaked emission lines from the base of the wind. Finally, we show that even denser models can produce a single-peaked H alpha line. On the basis of our results, we suggest that winds can modify, and perhaps even dominate, the line and continuum emission from CVs.</p
Testing quasar unification: radiative transfer in clumpy winds
Full text linkVarious unification schemes interpret the complex phenomenology of quasars and luminous active galactic nuclei (AGN) in terms of a simple picture involving a central black hole, an accretion disc and an associated outflow. Here, we continue our tests of this paradigm by comparing quasar spectra to synthetic spectra of biconical disc wind models, produced with our state-of-the-art Monte Carlo radiative transfer code. Previously, we have shown that we could produce synthetic spectra resembling those of observed broad absorption line (BAL) quasars, but only if the X-ray luminosity was limited to 1043 erg s-1. Here, we introduce a simple treatment of clumping, and find that a filling factor of ~0.01 moderates the ionization state sufficiently for BAL features to form in the rest-frame UV at more realistic X-ray luminosities. Our fiducial model shows good agreement with AGN X-ray properties and the wind produces strong line emission in, e.g., Lyα and CIV 1550 Å at low inclinations. At high inclinations, the spectra possess prominent LoBAL features. Despite these successes, we cannot reproduce all emission lines seen in quasar spectra with the correct equivalent-width ratios, and we find an angular dependence of emission line equivalent width despite the similarities in the observed emission line properties of BAL and non-BAL quasars. Overall, our work suggests that biconical winds can reproduce much of the qualitative behaviour expected from a unified model, but we cannot yet provide quantitative matches with quasar properties at all viewing angles. Whether disc winds can successfully unify quasars is therefore still an open question
Assessoria técnica à IP – Infraestruturas de Portugal, S.A. para a conclusão do empreendimento do Túnel do Marão no âmbito dos equipamentos e sistemas de segurança - Relatório de síntese do acompanhamento da execução
No full textO presente relatório sintetiza a atividade da assessoria prestada pela equipa do LNEC à IP durante a fase de instalação dos equipamentos e sistemas de segurança ativa do túnel rodoviário do Marão. Este trabalho insere-se no âmbito da assessoria do LNEC à IP - INFRAESTRUTURAS DE PORTUGAL, S.A. para a conclusão deste empreendimento. Nele se incluem em anexo os pareceres e outros documentos que foram elaborados pela equipa do LNEC no decurso desta fase.IP – Infraestruturas de Portugal, S.A. / NÃO CONFIDENCIALCIC/NSE
Dredging Processes I: The Cutting of Sand, Clay & Rock - Theory
No full textThis book gives an overview of cutting theories. It starts with a generic model, which is valid for all types of soil (sand, clay and rock) after which the specifics of dry sand, water saturated sand, clay, rock and hyperbaric rock are covered. For each soil type small blade angles and large blade angles, resulting in a wedge in front of the blade, are discussed. The failure mechanism of sand, dry and water saturated, is the so called Shear Type. The failure mechanism of clay is the so called Flow Type, but under certain circumstances also the Curling Type and the Tear Type are possible. Rock will usually fail in a brittle way. This can be brittle tensile failure, the Tear Type, for small blade angles, but it can also be brittle shear failure, which is of the Shear Type of failure mechanism for larger blade angles. Under hyperbaric conditions rock may also fail in a more ductile way according to the Flow Type of failure mechanism. For each case considered, the equations/model for the cutting forces, power and specific energy are given. The models are verified with laboratory research, mainly at the Delft University of Technology, but also with data from literature.Marine & Transport TechnologyMechanical, Maritime and Materials Engineerin
Work among Japanese in the Salt River Valley of Arizona
No full textDocument written by S.A. Stewart Resident Missionary, East Kyushu Distict, Japan Methodist Church. Stewart discusses the events at the church and the free and restricted zones for Japanese Americans living in Glendale and Phoenix, Arizona.The Bishop James Chamberlain Baker Collection includes letters, documents, and articles about Japanese Americans during World War II. Subjects in the collection include Japanese Americans mass removal, Pearl Harbor and the aftermath, religion, and support from the non-Japanese American community. The collection was digitized and made accessible online by CSUDH Gerth Archives and Special Collections
Assessoria técnica à IP – Infraestruturas de Portugal, S.A. para a conclusão do Empreendimento do Túnel do Marão no âmbito dos equipamentos e sistemas de segurança - Parecer sobre a segurança
No full textO presente relatório apresenta o Parecer sobre a Segurança do Túnel do Marão, com a respetiva fundamentação, no âmbito do Decreto-Lei n.º 75/2006, de 27 de março [2], com a redação que lhe foi conferida pelo Decreto-Lei n.º 75/2014, de 13 de maio [3], que estabelece os requisitos mínimos de segurança para os túneis da rede rodoviária transeuropeia e da rede rodoviária nacional. Este parecer resultou das atividades desenvolvidas pela equipa do LNEC que acompanhou a colocação em funcionamento dos equipamentos de segurança e a realização dos ensaios finais. Resulta da concretização de um conjunto de condições e recomendações que a equipa do LNEC, através de documentos e verbalmente, foi transmitindo à IP nesse período que precedeu a entrada em funcionamento do túnel.IP – Infraestruturas de Portugal, S.A. / NÃO CONFIDENCIALCIC/NSE
The reverberation signatures of rotating disc winds in active galactic nuclei
Full text linkThe broad emission lines (BELs) in active galactic nuclei (AGN) respond to ionizing continuum variations. The time and velocity dependence of their response depends on the structure of the broad-line region: its geometry, kinematics and ionization state. Here, we predict the reverberation signatures of BELs formed in rotating accretion disc winds. We use a Monte Carlo radiative transfer and ionization code to predict velocity-delay maps for representative high- (C) and low-ionization (H) emission lines in both high- and moderate-luminosity AGN. Self-shielding, multiple scattering and the ionization structure of the outflows are all self-consistently taken into account, while small-scale structure in the outflow is modelled in the micro-clumping approximation. Our main findings are: (1) The velocity-delay maps of smooth/micro-clumped outflows often contain significant negative responses. (2)~The reverberation signatures of disc wind models tend to be rotation dominated and can even resemble the classic "red-leads-blue" inflow signature. (3) Traditional "blue-leads-red" outflow signatures can usually only be observed in the long-delay limit. (4) Our models predict lag-luminosity relationships similar to those inferred from observations, but systematically underpredict the observed centroid delays. (5) The ratio between "virial product" and black hole mass predicted by our models depends on viewing angle. Our results imply that considerable care needs to be taken in interpreting data obtained by observational reverberation mapping campaigns. In particular, basic signatures such as "red-leads-blue", "blue-leads-red" and "blue and red vary jointly" are not always reliable indicators of inflow, outflow or rotation. This may help to explain the perplexing diversity of such signatures seen in observational campaigns to date
TP S.A.) (Umowa spoleczna - narzedzie transformacji czy recepta na kryzys? (TP S.A.)
No full textThe author presents the path to the signing of a Social Contract for the years 2009-2011 by all eighteen trade unions active at 'Telekomunikacja Polska S.A. The Contract defines the most important elements of employment policy and worker development, including a plan for the restructuring of the company and voluntary resignation for compensation on the part of the employe
PLANEJAMENTO DEPARTAMENTAL - UM ESTUDO DE CASO DO SISTEMA PAAD-PLANEJAMENTO E ACOMPANHAMENTO DAS ATIVIDADES DOCENTES DA UNIVERSIDADE FEDERAL DE SANTA CATARINA
Full text linkRealizou-se neste trabalho um diagnóstico do sistema PAAD – Planejamento e Acompanhamento das Atividades Docentes da Universidade Federal de Santa Catarina. As recentes mudanças nas universidades demandam profissionalização e aperfeiçoamento nas ferramentas de gestão. Neste contexto, esta pesquisa foi idealizada com o objetivo de analisar o planejamento departamental na UFSC. Classifica-se como científica aplicada. Quanto aos fins é descritiva, quanto aos meios trata-se de um estudo de caso, do tipo documental e bibliográfico. Apresenta-se como qualitativa no sentido de estudar um plano que pode ser melhorado. Analisou-se o funcionamento, a origem e as características, a utilização das informações, bem como suas vantagens e desvantagens. Para coleta de dados foi utilizada entrevista semiestruturada com um gestor universitário, orientada por um roteiro de entrevista. A população escolhida foi universidades federais do Brasil. A população amostral foi realizada por acessibilidade sendo escolhido um gestor de uma universidade federal do Brasil, a UFSC. Limitou-se o método desta pesquisa à escolha da população amostral. Os dados foram tratados de maneira não estatística e codificados através da análise de conteúdo. O trabalho foi estruturado a fim de abordar os tópicos: Planejamento, Planejamento Escolar e Planejamento Estratégico, estabelecendo relações com os dados da pesquisa. Observou-se que o referido plano apresenta diferenças entre sua forma e objetivo e que embora tenha hoje uma plataforma web bem elaborada, ainda apresenta deficiências em sua metodologia. Estas incorreções estão sendo aprimoradas a fim de transformar a ferramenta num instrumento de tomada de decisão compatível com as necessidades da instituição
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