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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
11

Análise multi-espectral dos eventos cíclicos de Carinae / Multi-spectral analysis of the cyclic events of Eta Carinae

Mairan Macedo Teodoro 23 October 2009 (has links)
Nesta tese foi feito um estudo dos eventos cíclicos em Carinae em diversas faixas espectrais. A presença de um buraco na região polar do Homúnculo foi confirmada pelos mapas de velocidade da linha do [Fe II] 12567. A componente em emissão da linha do He I 10830, detectada na linha de visada do lóbulo NW e que apresenta velocidades negativas, foi mapeada e está contida no plano equatorial. Foi observado que durante um período de 206 dias, centrado na fase zero, a linha do He I 10830 apresenta um aumento na velocidade máxima da componente em absorção, atingindo 1800 km/s. Tal comportamento favorece orientações orbitais onde a passagem pelo periastro ocorre próximo à oposição. O Pequeno Homúnculo apresenta a mesma distribuição espacial da emissão em rádio e, considerando que esta seja proveniente principalmente da secundária, o fluxo de fótons no contínuo de Lyman é compatível com uma estrela de tipo espectral O5.5O7. A variabilidade das componentes largas e estreitas das linhas em diversas faixas espectrais apresenta um período bem definido (2022.1±0.6 dias) e extremamente estável ao longo dos últimos 60 anos, sendo que as variações observadas no período são devido aos erros nas medidas. Utilizando a componente estreita da linha do He I 6678 foi possível determinar a fase zero do ciclo #11 (T0=2452819.8). Os eventos espectroscópicos são compostos de dois regimes: um de variações lentas e outro de colapso. A primeira é revelada por variações lentas no nível de ionização do meio circunstelar ao longo de todo o ciclo e está associada a variações graduais no cone de choque dos ventos (abertura angular e conteúdo). O regime de colapso é observado ao redor do mínimo e é causado por um colapso temporário do cone de choque. Os fenômenos de alta energia são sensíveis somente ao regime de colapso, enquanto os de baixa energia, ao de variação lenta. Os fenômenos que envolvem energias intermediárias, respondem aos dois regimes. Foi observado uma anti-correlação entre a linha do Fe II 6455 e a do He I 7065, indicando que a primeira é formada nas regiões mais externas do vento da primária e a segunda, na secundária ou no cone de choque dos ventos. A curva de luz do He II 4686 apresenta dois picos antes da fase zero e outro logo após. Os dois picos antes do mínimo apresentam uma correlação com os picos na faixa dos raios-X, porém estes ocorrem 16.5 dias antes daqueles. O mecanismo mais provável para explicar a luminosidade observada do He II 4686 é a produção de fótons com 1215 Å através do fluxo de fótons na faixa do ultra-violeta extremo/raios-X moles produzidos na região próxima ao ápex do cone de colisão dos ventos. Como este mecanismo é extremamente sensível à densidade do meio, a região mais favorável para produzir a luminosidade observada do He II 4686 é a região do cone de choque voltada para a primária. / In this thesis, a multi-wavelength study on the cyclic events of Eta Carinae was performed. The presence of a hole in the polar region of the Homunculus was confirmed by the velocity maps of the [Fe II] 12567 line. The blue-shifted component of the He I 10830, detected towards the NW lobe, was mapped and it is in the equatorial plane. It was observed that within a short period of 206 days, centered on phase zero, the He I 10830 line shows an increase in the maximum velocity of the absorption component, which reaches up to -1800 km/s. Such behavior favors orbital orientation with periastron passage around oposition. The Little Homunculus shows the same spatial distribution as the radio emission and considering that the radio flux comes mainly from the secondary, then the photon flux in the Lyman continuum is comparable to a star with spectral type in the range O5.5-O7. The variability of the narrow and broad lines from many spectral regions shows a well-defined period (2022.1+/-0.6 days), which is also extremely stable along the last 60 years, during which the observed variations in the period are due to measurement errors. Using the narrow component of the He I 6678 it was possible to determine the phase zero of the cycle #11 (T_0=2452819.8). The spectroscopic events are a combination of two components: slow variation and collapse. The former is revealed by slow changes in the ionization level of circunstellar matter across the whole cycle and is associated to gradual changes in the wind-wind collision shock-cone (angular opening and gaseous content). The collapse component is restricted to around the minimum and is caused by a temporary collapse of the wind-wind collision shock. High-energy phenomena are sensitive only to the collapse component, while low-energy only to the slow variation component. Intermediate-energy phenomena are sensitive to both components. It was observed an anti-correlation between the Fe II 6455 and He II 7065, suggesting that the former is formed in the outer parts of the primary\'s wind, while the latter is associated to the secondary or to the wind-wind shock cone. The lightcurve of He II 4686 shows two peaks before phase zero and another one short after it. The two peaks before phase zero are correlated to the peaks seen in the X-rays. However, the X-ray peaks occur 16.5 days before those seen in the He II 4686 lightcurve. The most likely mechanism to explain the observed peak luminosity of the He II 4686 is the creation of ~1215 Angstroms photons by the extreme ultra-violet/soft X-rays photons, which are produced near the apex of the wind-wind shock-cone. Since this mechanism is extremely sensitive to the density, the most likely region to form the observed peak luminosity of the He II 4686 is on the primary\'s side of the wind-wind shock-cone.
12

Avaliação de índices climáticos na amazônia para meados e final do século xxi baseada no cenário rcp8.5 com o modelo regional ETA

Brito, Adriane Lima 30 June 2016 (has links)
Submitted by Gizele Lima (gizele.lima@inpa.gov.br) on 2017-02-15T21:04:32Z No. of bitstreams: 2 01-Dissertação-Adriane.pdf: 25884094 bytes, checksum: 41cbb40c48f6a464d8f8ba21f9bb8b94 (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) / Made available in DSpace on 2017-02-15T21:04:32Z (GMT). No. of bitstreams: 2 01-Dissertação-Adriane.pdf: 25884094 bytes, checksum: 41cbb40c48f6a464d8f8ba21f9bb8b94 (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) Previous issue date: 2016-06-30 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES / The greenhouse effct is a phenomenon that causes the natural warming of the earth’s surface. However, in recent decades this warming is increasing due to natural causes and principalemente to human activities, causing global climate change, including the Amazon region with p otentially catastrophic impacts. These changes in climate are measured using historic al series of meteorological variables such as the temp erature and precipitation. Thus, the World Meteorological Organization (WMO), through various worksops created twenty-seven changes in weather detection indicators based on temepratura and precipitation. They were used in this study 8 climate indices based on precipitation and calculated in the Amaz on Basin region, which is Grende imp ortance econônima for the p eople (directly and/or indirectly), in vie w of the role of these climatic indicators for the middle and end of the century XXI in order to b etter planning to minimize the environmental, so cial and economic impacts. Thus, the present study used data from precipitation Climate Prediction Center (CPC) and the regional mo del ETA EXP-CTRL , b oth for the p erio d 1981-1990, in order to evaluate 8 climatic indicators, comparing their-spatial patterns and ETA validate the mo del using statistical metho ds BIAS and RMSE. The present study also used data from the regional mo del ETA, with the b oundary conditions of numerical simulations of the general circulatio n mo del HadGEM2 for the scenario of greenhouse gas emissions RCP 8.5, we selected three diffrent p erio ds, they are: 1 ) 1961-1990 (EXP-CTRL), 2) 2021-2050 (EXP-FP8.5) and 3) 2071-2100 (EXP-FD8.5). To evaluate the inflence of the increase in the concentrati on of greenhouse gases, characterized by the IPCC scenario RCP8.5 on 8 clima te indices based on rainfall data to the Amazon Basin. The results showed that the validation base d on BIAS, the mo del showed changes similar to that observed in terms of spatial di stribution. In the validation based on the RMSE, it was observed that the mo de l has go o d accuracy of the mo del in relation to what was observed for the numb er of consecutive days and dried the maximum amount of rainfall in a day. The results also indicated that the EXP-FP8.5 only the numb er of consecutive rainy days, the total numb er of dry days and the total numb er of rainy days are signifiantly impacted. So for the EXP-FP8.5 and EXP-FD8.5 exp eriments, mo del ETA force d the HadGEM2, there may b e a signifiant increase in the numb er of dry days and a reduction in the numb er of rainy days and consecutive or not b etween the middle and end the twenty-fist century. For other climatic indicators (total amount of rainfall, maximum rainfall o ccurred in 1 day, maximum rainfall amo unt o ccurred in fie days, the p ercentile 95% of rain) mo del indicates a reduction in the amount of rain on the region of the Amazon Basin mainly for the indic ators asso ciated with extreme events. / O efeito estufa é um fenômeno que o casiona o aquecimento natural da sup erfície terrestre. No entanto, nas úl timas décadas esse aquecimento vem aumentando devido à causas naturais e principalmente às atividades antrópicas, acarretando mudanças no c lima global, incluindo a região Amazônica com impactos p otencialmente catastrófios. Essas mudan- ças no c lima são medidas utilizando séries históric as de variáveis meteorológicas como, p or e xemplo, a temp eratura e a precipitação. Desse mo do, a Organização Mundial de Meteorologia (OMM), a través de vários workshops criou vinte e sete indicadores de detec- ção de mudanças no clima, baseados na temp eratura e na precipitação. Foram utiliza dos no presente trabalho 8 índices climáticos baseados na precipitação e calculados na região da Bacia Amazônica, que é de grande imp ortância econômica para a p opulação (direta e/ou indiretamente), tendo em vista o pap e l desses indicadores climáticos para meados e fial do século XXI com o intuito de melhores planejamentos para minimizar os impactos ambientais, so ciais e econômicos. A presente p esquisa utilizou dados de precipitação do Climate Prediction Center (CPC) e do mo de lo regional ETA do EXP-CTRL, com o intuito de avaliar 8 indicadores climáti cos comparando seus pa drõ es espaciais e vali dar o mo delo ETA utilizando os méto dos e sta tí sti co BIAS e RMSE. No presente estudo tamb ém foram utilizados dados provenientes do mo delo regional ETA, tendo com o condiçõ es de contorno as simulaçõ es numéricas do mo delo de circulação geral HadGEM2 para o cenário de emissõ es de gases de ef eito estufa RCP 8.5. Foram selecionados três p erío dos distintos, são eles: 1) 1961 a 199 0 (EXP-CTRL), 2) 2021 a 2050 (EXP-FP8.5) e 3) 2071 a 2100 (EXP-FD8.5). Ob jetivando avaliar a inflência do aumento na concentração dos GEE, caracterizado p e lo cenário RCP8.5 do IPCC, sobre 8 índices climáticos baseados em dados de precipitação para a Bac ia amazônica. Dessa forma, os resultados mostraram que na validação baseada no BIAS, o mo delo apresentou variaçõ es semelhantes ao que foi observado, em termos de distribuição espacial. Na validação baseada no RMSE, observou-se que, o mo delo p ossui b oa precisão, em relação ao que foi observado, para o número consecutivo de dias secos e a quantidade máxima de precipitação em um dia. Os resultados tamb ém indica ram que, no EXP-FP8.5 ap enas o número de dias consecutivos chuvosos, o número total de dias secos e o número total de dias chuvosos são impactados signifiativamente. Assim para os exp erimentos EXP-FP8.5 e EXP-FD8.5, do mo delo ETA forçado p elo HadGEM2, p o derá haver um aumento signifiativo do número de dias secos e uma redução no número de dias chuvosos, sendo consecutivos ou não e ntre meados e fial do século XXI. Para os de mais i ndi cadores climáticos (quantidade total de chuva, quantidade máxima de chuva o corrida em 1 dia, quantidade máxima de chuva o corrida em 5 dias, p e rcentil de 95% de chuva) o mo del o indica redução na quantidade de chuva sobre a regi ão da Bacia Amazônica, principalmente para os indicadores asso c iados a eventos extremos.
13

Can e+e- → ηπ+π- be detected at DAΦNE?

Thorén, Viktor January 2015 (has links)
Studying the annihilation of e+e- into hadrons is of great interest in the search for physics beyond the standard model. The cross sections of specific hadronic channels can be used in precise test of the Standard Model, or to estimate the anomalous muon magnetic moment, for which there are discrepancies between theory and experiment. This thesis focuses on one particular hadronic channel, e+e- → ηπ+π- with the final state π+π-γγ. As background, the reaction e+e- → π+π-π0 is chosen. By simulations using the Monte Carlo event generator PHOKHARA and the data analysis framework ROOT, the feasibility of detecting the aforementioned reaction with the detector KLOE at the electron-positron collider DAΦNE is studied. The detector acceptance and expected number of events is evaluated both for the signal and the background. An analysis program that can be used for feasibility studies of e+e- → ηπ+π- was written. The simulations indicate that the signal significance from an experiment at DAΦNE would be 2.4σ and thus lower than the confidence level required for detection. A definitive statement can however only be made after further investigations into minimizing the background and studies of additional final states with other decays of the η-meson and their corresponding background reactions. / I sökandet efter fysik bortom standardmodellen är studier av elektron-positron-annihilation till hadroner av stort intresse. Tvärsnitten för specifika hadroniska kanaler kan användas för precisa tester av standardmodellen, eller för att uppskatta myonens anomala magnetiska moment, vars teoretiska värde avviker från det experimentella. Detta examensarbete fokuserar på en specifik hadronisk kanal, e+e- → ηπ+π- med sluttillståndet π+π-γγ. Som bakgrund väljs reaktionen e+e- → π+π-π0. Med hjälp av simulationer byggda på den Monte Carlo-baserade händelsegeneratorn PHOKHARA, och ROOT, ett ramverk för dataanalys, studeras om det är genomförbart att detektera den ovan nämnda reaktionen med detektorn KLOE vid acceleratorn DA\(\Phi\)NE. Detektoracceptansen och det förväntade antalet händelser utvärderas både för signalen och bakgrunden. Ett analysprogram som skulle kunna användas för andra genomförbarhetsstudier för e+e- → ηπ+π- har skrivits. Simulationerna visar signifikansen för signal från experiment vid DAΦNE skulle vara 2.4σ, vilket är lägre än den konfidensnivå som krävs för att reaktionen med säkerhet ska kunna detekteras. Dock kan ett slutgiltigt besked ges först efter att möjligheten att ytterligare minska antalet bakgrundshändelser har undersökts och fler sluttillstånd med andra η-sönderfall och motsvarande bakgrundsreaktioner har studerats.
14

An Astrometric Analysis of eta Carinae's Eruptive History using HST WFPC2 and ACS Observations /

Dorland, Bryan Currie, Doug January 2007 (has links)
Thesis (Ph.D.) - University of Maryland. / "Dissertation directed by Professor Doug Currie, Department of Physics." Includes bibliographical references (p. 260-269).
15

Chirale Dynamik und die Physik des j'-Mesons

Wetzel, Stefan Wolfgang. Unknown Date (has links)
Techn. Universiẗat, Diss., 2001--München.
16

Avaliação da eficiência do método de remediação eletrocinética na descontaminação do lodo de uma estação de tratamento de água

Marder, Fernanda 31 March 2017 (has links)
Submitted by FERNANDA DA SILVA VON PORSTER (fdsvporster@univates.br) on 2018-01-04T17:02:11Z No. of bitstreams: 2 license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) 2017FernandaMarder.pdf: 3448153 bytes, checksum: 2350fde73f91b391dde6a88ee1196174 (MD5) / Approved for entry into archive by Ana Paula Lisboa Monteiro (monteiro@univates.br) on 2018-01-05T19:29:13Z (GMT) No. of bitstreams: 2 license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) 2017FernandaMarder.pdf: 3448153 bytes, checksum: 2350fde73f91b391dde6a88ee1196174 (MD5) / Made available in DSpace on 2018-01-05T19:29:13Z (GMT). No. of bitstreams: 2 license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) 2017FernandaMarder.pdf: 3448153 bytes, checksum: 2350fde73f91b391dde6a88ee1196174 (MD5) Previous issue date: 2018-01 / CAPES / A geração de lodo em Estações de Tratamento de Águas (ETA) convencionais é o subproduto do processo de tratamento formado por sólidos e precipitados químicos decorrentes da adição de coagulantes como os sais de ferro e alumínio. Alternativas ambientais vêm sendo desenvolvidas para realizar o reaproveitamento deste material e não impactar o meio ambiente. Neste trabalho, investigou-se os efeitos do potencial aplicado, tempo de eletrólise e conteúdo de eletrólito sobre a remoção eletrocinética de alumínio e ferro presentes em lodo gerado por ETA usando o planejamento experimental estatístico Box-Behnken. A análise multivariada do alumínio forneceu um modelo significativo estatístico, com p = 0,0509. A parte quadrática, em particular, teve resultados relevantes, justificando assim as experiências de otimização. A superfície de resposta para a remoção de alumínio mostrou um rendimento ótimo previsto de 60,5% para o potencial aplicado de 25 V, tempo de eletrólise de 72 h e quantidade de eletrólito de 90%. Já a análise multivariada para a remediação eletrocinética de ferro não forneceu um modelo significativo, com p = 0,1156730. Assim, esse modelo estatístico não obteve resultados favoráveis, sendo o modelo descartado. Os fatores utilizados não obtiveram êxito, e estes parâmetros não podem ser utilizados em futuras análises. / The generation of sludge in conventional water treatment plants (WTPs) is the byproduct of the treatment process formed by solids and chemical precipitates resulting from the addition of coagulants such as iron and aluminum salts. Environmental alternatives have been developed to realize the reuse of this material and not to impact the environment. In this work, the effects of the applied potential, electrolysis time and electrolyte content on the electrokinetic removal of aluminum and iron present in WTP generated sludge using the Box- Behnken experimental experimental design were investigated. The multivariate analysis of aluminum provided a statistically significant model, with p = 0.0509. The quadratic part, in particular, had relevant results, thus justifying the optimization experiments. The response surface for aluminum removal showed an optimum predicted efficiency of 60.5% for the 25 V applied potential, 72 h electrolysis time and 90% electrolyte quantity. The multivariate analysis for electrokinetic iron remediation did not provide a significant model, with p = 0.1156730. Thus, this statistical model did not obtain favorable results, being the model discarded. The factors used were not successful, and these parameters can’t be used in future analyzes.
17

Towards measurement of the ratio BR(η → 3π<sup>0</sup>) / BR(η → π<sup>+</sup> π<sup>- </sup>π<sup>0</sup>)

Heijkenskjöld, Lena January 2010 (has links)
<p>This diploma thesis presents a preliminary study of the ratio of branching ratio r = BR(η → 3π<sup>0</sup>) / BR(η → π<sup>+</sup> π<sup>- </sup>π<sup>0</sup>). The experimental data used is collected by WASA-at-COSY which is a 4π sr detector optimised to detect light mesons and their decay products and is situated in Jülich, Germany.The focus of the work is to see how different reconstruction methods for the detected particles can alter both the measured values of the  branching ratios and the luminosity dependence of these branching ratios. The results show that for some of the methods, the measured branching ratios have a clear luminosity dependence. Depending on method, the extracted branching ratios vary differently. A few different methods have been studied, so the results provides a qualitative understanding of the behaviour of the measured branching ratios for different luminosities.</p>
18

Synthesis of bicyclic and bimetallic titanacyclobutenes

Quesnel, Jeffrey Scott 11 1900 (has links)
In an attempt to expand the scope of titanacyclobutenes, malonate-derived ,-alkylpropargyl dibromides and ,-bis(bromopropargyl) malonates were prepared and examined for their reactivity with titanocene reagents. Unfortunately, all of the ,-alkylpropargyl dibromomalonates failed, presumably from chelation of the carbonyl oxygen followed by radical or nucleophilic attack. The ,-bis(bromopropargyl) malonate substrates allowed the successful synthesis of ester-functionalized allenyl or alkynyl-substituted bicyclic titanacyclobutene complexes. Allenyl-substitution is favoured when the being formed ring is small. When ring strain is minimal, cycloalkynes are obtained. An impressive example of a twelve-membered macrobicyclic titanacyclobutene was achieved, supported by extensive NMR spectroscopy and X-ray crystallography. 3-Propargyltitanium(III) complexes were synthesized and displayed equilibrium behaviour between the monomeric propargyl and dimeric di(titanacyclobutene) forms. Both steric and electronic effects are believed to be contributing factors for dimerization. Bimetallic titanacyclobutenes are obtained from the reaction of an epoxide and titanocene monochloride in the presence of a 3-propargyltitanium(III) complex.
19

Towards measurement of the ratio BR(η → 3π0) / BR(η → π+ π- π0)

Heijkenskjöld, Lena January 2010 (has links)
This diploma thesis presents a preliminary study of the ratio of branching ratio r = BR(η → 3π0) / BR(η → π+ π- π0). The experimental data used is collected by WASA-at-COSY which is a 4π sr detector optimised to detect light mesons and their decay products and is situated in Jülich, Germany.The focus of the work is to see how different reconstruction methods for the detected particles can alter both the measured values of the  branching ratios and the luminosity dependence of these branching ratios. The results show that for some of the methods, the measured branching ratios have a clear luminosity dependence. Depending on method, the extracted branching ratios vary differently. A few different methods have been studied, so the results provides a qualitative understanding of the behaviour of the measured branching ratios for different luminosities.
20

Synthesis of bicyclic and bimetallic titanacyclobutenes

Quesnel, Jeffrey Scott Unknown Date
No description available.

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