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Showing 1 to 10 of 10 (0.034 seconds)Spelling suggestions: "subject:"cassiopeia A"" "subject:"kassiopeia A""
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TeV-[gamma]-Emission [TeV-gamma-Emission] des Supernova-Überrestes Cassiopeia A erster Nachweis mit dem HEGRA-Cherenkov-Teleskop-System /Pühlhofer, Gerd. January 2001 (has links)
Heidelberg, Universiẗat, Diss., 2001. / Dateiformat: tgz, Dateien im PS-Format.
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New Observational and Theoretical Insights on Cassiopeia AEriksen, Kristoffer Albert January 2009 (has links)
Using two techniques not previously applied to Cassiopeia A (Cas A), we measure the reddening toward its expansion center. An estimate of AV from the near-IR [Fe II] lines is hampered by uncertain atomic data, though the spatial variation in their flux ratio allows relative measurement of the extinction in regions without previous optical estimates. We use a second technique based on the broad-band IR shape of the synchrotron emission, and find Aᵥ = 6.2 ± 0.6 for a knot 13" from the expansion center. Assuming a plausible lower limit on the apparent magnitude of the SN in outburst, the ⁵⁶Ni yield was 0.058 < M(Ni) < 0.16M⊙. With the ⁴⁴Ti mass from published gamma-ray observations, this implies a ⁴⁴Ca/ ⁵⁶Fe ratio consistent with the solar abundance. Recently published Spitzer Space Telescope IRS observations detect dust and line emission from cold gas interior to Cas A’s reverse shock. Using simple physical arguments and new hydrodynamic, non-equilibrium photoionization calculations, we infer the physical conditions in this material. We find that the mid-IR bright clumps are photoionized by the SNR shocks, over-dense relative to the expected average in the interior of the remnant, and have abundances consistent with incomplete oxygen burning. The lack of detectable iron lines indicates that any Si-burning material still interior to the reverse shock must be far more tenuous than the clumps of O-burning ashes. Finally, we present calculations from a new multi-dimensional hydrodynamics and non-equilibrium ionization and cooling code designed to model the emission from SNR shocks. Two-dimensional simulations of a shock-cloud interaction in a pure-oxygen plasma, with flow parameters relevant to Cas A, show a wider range of temperatures and ionization states than is typical in single-zone or 1D calculations, indicating that fluid and cooling instabilities play a role in producing the observed spectra of radiative shocks in metal-rich gas.
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TeV-Gamma-Emission des Supernova-Überrestes Cassiopeia A erster Nachweis mit dem HEGRA-Cherenkov-Teleskop-System /Pühlhofer, Gerd. January 2001 (has links)
Heidelberg, Univ., Diss., 2001.
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ENEM nas redes sociais: minera??o de textos e clusteriza??oSilva, Leila Maria 18 December 2017 (has links)
Submitted by Jos? Henrique Henrique (jose.neves@ufvjm.edu.br) on 2018-07-24T17:34:56Z
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Previous issue date: 2017 / A internet ? hoje a maior fonte de informa??o eletr?nica existente. Cresce a cada dia o n?mero
de usu?rios da internet, e consequentemente o uso das redes sociais online. S?o muitas
as informa??es novas que ficam embutidas nas bases de dados textuais. Por causa da sua natureza
din?mica, ou seja, milh?es de p?ginas surgem e desaparecem todos os dias, a tarefa de
encontrar informa??es relevantes nessas bases de dados se torna muito dif?cil. As t?cnicas de
minera??o de textos para a descoberta de informa??es na web surgiram da necessidade de
sanar este problema. O presente trabalho versa sobre a aplica??o de m?todos de minera??o
de textos com clusteriza??o na grande quantidade de mensagens sobre o Exame Nacional do
Ensino M?dio no ano de 2016 provenientes da rede social Twitter. O foco deste estudo est?
na obten??o de grupos de textos, a fim de possibilitar uma visualiza??o resumida e sintetizada
dos assuntos mais comentados pelos usu?rios. Para manipula??o dessas bases textuais, o
Modelo Cassiopeia foi utilizado empregando seu algoritmo de agrupamento textual que tem como
principal finalidade gerar agrupamentos, ou seja, clusters (grupos) de documentos textuais
que apresentam algum tipo de similaridade. O Modelo Cassiopeia apresenta um limite de processamento
com a quantidade m?xima de 700 tweets. Os tweets passam primeiramente pela fase de
limpeza dos textos no pr?-processamento, logo ap?s, a utiliza??o do algoritmo no processamento
e por fim, as an?lises dos resultados no p?s-processamento. Os resultados obtidos neste trabalho
mostram valores coesos quanto ? similaridade dos documentos dentro de um cluster e entre os
clusters, avaliados por medidas de agrupamento textual, proposto pelo Modelo Cassiopeia. Isso
demonstra a aplicabilidade dessa proposta para a visualiza??o sintetizada das informa??es
mais significativas de um determinado tema, muitas vezes permitindo que a??es sejam antecipadas
e impactos sobre a popula??o afetada sejam reduzidos. / Disserta??o (Mestrado Profissional) ? Programa de P?s-Gradua??o em Educa??o, Universidade Federal dos Vales do Jequitinhonha e Mucuri, 2017. / The Internet is today the largest source of existing electronic information. The number of Internet
users is increasing daily, and consequently the use of online networks online. There
are many new information that is embedded in textual databases. Because of its dynamic nature-
that is, millions of pages and other numbers-a task of finding relevant information in
those databases becomes very difficult. The techniques of text mining for a discovery of information
on the web came from the need to heal this problem. The present work is about an
application of methods of text mining with clustering in the large amount of messages on the
National High School Exams in the year 2016 issu social network Twitter. The focus of this
study is on obtaining groups of texts in order to enable a summary and synthesized publication
of the appropriate comments of the users. For manipulation of textual bases, the Cassiopeia
Model was used by using its textual grouping algorithm that has as main purpose to
generate clusters, that is, clusters of textual documents and executed some kind of similarity.
The Cassiopeia Model has a processing limit with a maximum of 700 tweets. The tweets first
pass through the phase of cleaning the texts without preprocessing, afterwards, a use of the
algorithm without processing and, finally, as analysis of the results without post-processing.
The results obtained in this work are more closely related to the similarity of the documents
within the cluster and between the clusters, through the measurements of textual grouping,
proposed by the Cassiopeia Model. This demonstrates an application for an uninformed publication
of the most important information on a given topic, often allowing actions to be anticipated
and impacts on an affected population to be reduced.
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Modelo Cassiopeia como avaliador de sum?rios autom?ticos: aplica??o em um corpus educacionalAguiar, Lu?s Henrique Gon?alves de 05 December 2017 (has links)
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Previous issue date: 2017 / Considerando a grande quantidade de informa??es textuais dispon?veis atualmente,
principalmente na web, est? se tronando cada vez mais dif?cil o acesso e a assimila??o desse
conte?do para o usu?rio. Nesse contexto, torna-se necess?rio buscar tarefas capazes de
transformar essa grande quantidade de dados em conhecimento ?til e organizado. Uma
alternativa para amenizar esse problema, ? reduzir o volume de informa??es dispon?veis a partir
da produ??o de resumos dos textos originais, por meio da sumariza??o autom?tica (SA) de
textos. A sumariza??o autom?tica de textos consiste na produ??o autom?tica de resumos a partir
de um ou mais textos-fonte, de modo que o sum?rio contenha as informa??es mais relevantes
deste. A avalia??o de resumos ? uma tarefa importante no campo da sumariza??o autom?tica
de texto, a abordagem mais intuitiva ? a avalia??o humana, por?m ? onerosa e improdutiva.
Outra alternativa ? a avalia??o autom?tica, alguns avaliadores foram propostos, sendo a mais
conhecida e amplamente usada ? a medida ROUGE (Recall-Oriented Understudy for Gisting
Evaluation). Um fator limitante na avalia??o da ROUGE ? a utiliza??o do sum?rio humano de
refer?ncia, o que implica em uma restri??o do idioma e dom?nio, al?m de requerer um trabalho
humano demorado e oneroso. Diante das dificuldades encontradas na avalia??o de sum?rios
autom?ticos, o presente trabalho apresenta o modelo Cassiopeia como um novo m?todo de
avalia??o. O modelo ? um agrupador de textos hier?rquico, o qual consiste no uso da
sumariza??o na etapa do pr?-processamento, onde a qualidade do agrupamento ? influenciada
positivamente conforme a qualidade da sumariza??o. As simula??es realizadas neste trabalho
mostraram que a avalia??o realizada pelo modelo Cassiopeia ? semelhante a avalia??o realizada
pela ferramenta ROUGE. Por outro lado, a utiliza??o do modelo Cassiopeia como avaliador de
sum?rios autom?ticos evidenciou algumas vantagens, sendo as principais; a n?o utiliza??o do
sum?rio humano no processo de avalia??o, e a independ?ncia do dom?nio e do idioma. / Disserta??o (Mestrado Profissional) ? Programa de P?s-Gradua??o em Educa??o, Universidade Federal dos Vales do Jequitinhonha e Mucuri, 2017. / Considering the large amount of textual information currently available, especially on the web,
it is becoming increasingly difficult to access and assimilate this content to the user. In this
context, it becomes necessary to search for tasks that can transform this large amount of
information into useful and organized knowledge. The solution, or at least an alternative, to
moderate this problem is to reduce the volume of information available, from the production of
abstracts of the original texts, through automatic summarization (SA) of texts. The Automatic
Summarization of texts consists of the automatic production of abstracts from one or more
source texts, which the summary must contain the most relevant information of the source text.
The evaluation of abstracts is an important task in the field of automatic text summarization,
the most intuitive approach is human evaluation, but it is costly and unproductive. Another
alternative is the automatic evaluation, some evaluators have been proposed, and the most
widely used is the ROUGE (Recall-Oriented Understudy for Gisting Evaluation). A limiting
factor in ROUGE's evaluation is the use of the human reference summary, which implies a
restriction of language and domain, as well as requiring time-consuming and expensive human
work. In view of the difficulties encountered in the evaluation of automatic summaries, this
paper presents the Cassiopeia model as a new evaluation method. The model is a hierarchical
text grouper, which consists of the use of the summarization in the stage of the pre-processing,
where the quality of the grouping is influenced positively according to the quality of the
summarization. The simulations performed in this work showed that the evaluations performed
by Cassiopeia in comparison to the ROUGE tool are similar. On the other hand, the use of the
Cassiopeia model as an automatic summarization evaluator showed some advantages, the main
ones are; being the non-use of the human abstract in the evaluation process, and the independent
of the domain and the language.
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X-Ray Measurements of the Particle Acceleration Properties at Inward Shocks in Cassiopeia ASato, Toshiki, Katsuda, Satoru, Morii, Mikio, Bamba, Aya, Hughes, John P., Maeda, Yoshitomo, Ishida, Manabu, Fraschetti, Federico 22 January 2018 (has links)
We present new evidence that the bright nonthermal X-ray emission features in the interior of the Cassiopeia A supernova remnant are caused by inward-moving shocks, based on Chandra and NuSTAR observations. Several bright inward-moving filaments were identified using monitoring data taken by Chandra in 2000-2014. These inward-moving shock locations are nearly coincident with hard X-ray (15-40 keV) hot spots seen by NuSTAR. From proper-motion measurements, the transverse velocities were estimated to be in the range of similar to 2100-3800 km s(-1) for a distance of 3.4 kpc. The shock velocities in the frame of the expanding ejecta reach values of similar to 5100-8700 km s(-1), which is slightly higher than the typical speed of the forward shock. Additionally, we find flux variations (both increasing and decreasing) on timescales of a few years in some of the inward-moving shock filaments. The rapid variability timescales are consistent with an amplified magnetic field of B similar to 0.5-1 mG. The high speed and low photon cut-off energy of the inward-moving shocks are shown to imply a particle diffusion coefficient that departs from the Bohm regime (k(0) = D-0/D-0,D-Bohm similar to 3-8) for the few simple physical configurations we consider in this study. The maximum electron energy at these shocks is estimated to be similar to 8-11 TeV, which is smaller than the values of similar to 15-34 TeV that were inferred for the forward shock. Cassiopeia A is dynamically too young for its reverse shock to appear to be moving inward in the observer frame. We propose instead that the inward-moving shocks are a consequence of the forward shock encountering a density jump of 5-8 in the surrounding material.
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Binary hypotheses for bipolar mass loss in transientsFitzpatrick, Benedict John Russell January 2012 (has links)
We investigate binary hypotheses for the formation of bipolar nebulae using the smoothed particle hydrodynamics code Gadget-2. In the general case, we present a parameter study of mass loss from very simple common envelope models, which seems to show a strongly bipolar trend for sufficiently oblate envelopes and low enough spiral-in injection energy. The density profiles of the envelopes produce differing structure within the ejecta. We also investigate 3 specific bipolar mass loss events. In the case of the outer nebula of SN 1987A, we study the effects of fast polar jets interacting with a pre- existing progenitor wind and find that these are consistent with the observed light echoes from the nebula, in particular for the feature known as ’Napoleon’s Hat’. In the case of Cas A, we briefly study the effects of close binarity on supernova ejecta and suggest the influence of a close, compact companion may lead to at least one jet-like disturbance that may be observable in a supernova remnant. Finally, we study whether a fast bipolar wind, similar to that of Eta Car’s present wind, may inflate ejecta similar to that produced in the common envelope models to a shape consistent with that of Eta Car’s Homunculus Nebula.
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CHARLES MEE’S HOTEL CASSIOPEIA: A DIRECTORIAL COMPOSITION IN SEARCH OF THE ‘INNER LIFE’Farris, Charles Adron, III 23 July 2009 (has links)
No description available.
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Charles Mee's Hotel Cassiopeia a directorial composition in search of the 'inner life' /Farris, Charles Adron. January 2009 (has links)
Thesis (M.A.)--Miami University, Dept. of Theatre, 2009. / Title from first page of PDF document. Includes bibliographical references (p. 59-61).
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Implementation and Analysis of Co-Located Virtual Reality for Scientific Data VisualizationJordan M McGraw (8803076) 07 May 2020 (has links)
<div>Advancements in virtual reality (VR) technologies have led to overwhelming critique and acclaim in recent years. Academic researchers have already begun to take advantage of these immersive technologies across all manner of settings. Using immersive technologies, educators are able to more easily interpret complex information with students and colleagues. Despite the advantages these technologies bring, some drawbacks still remain. One particular drawback is the difficulty of engaging in immersive environments with others in a shared physical space (i.e., with a shared virtual environment). A common strategy for improving collaborative data exploration has been to use technological substitutions to make distant users feel they are collaborating in the same space. This research, however, is focused on how virtual reality can be used to build upon real-world interactions which take place in the same physical space (i.e., collaborative, co-located, multi-user virtual reality).</div><div><br></div><div>In this study we address two primary dimensions of collaborative data visualization and analysis as follows: [1] we detail the implementation of a novel co-located VR hardware and software system, [2] we conduct a formal user experience study of the novel system using the NASA Task Load Index (Hart, 1986) and introduce the Modified User Experience Inventory, a new user study inventory based upon the Unified User Experience Inventory, (Tcha-Tokey, Christmann, Loup-Escande, Richir, 2016) to empirically observe the dependent measures of Workload, Presence, Engagement, Consequence, and Immersion. A total of 77 participants volunteered to join a demonstration of this technology at Purdue University. In groups ranging from two to four, participants shared a co-located virtual environment built to visualize point cloud measurements of exploded supernovae. This study is not experimental but observational. We found there to be moderately high levels of user experience and moderate levels of workload demand in our results. We describe the implementation of the software platform and present user reactions to the technology that was created. These are described in detail within this manuscript.</div>
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