Orientador: Kyoko Furuya / Dissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Fisica Gleb Wataghin / Made available in DSpace on 2018-07-25T13:09:15Z (GMT). No. of bitstreams: 1 Angelo_RenatoMoreira_M.pdf: 1714464 bytes, checksum: b173ca3c346c3501aa7d229f8e313a75 (MD5) Previous issue date: 1999 / Resumo: No presente trabalho, apresentamos um estudo sistemático do volume caótico no espaço de fase do Hamiltoniano clássico associado ao modelo do Maser Caótico em função dos parâmetros de interação G e G'. O estudo foi realizado utilizando-se um ensemble médio de 100 condições iniciais. Cada condição inicial foi caracterizada como caótica ou regular através do cálculo de seu respectivo expoente de Lyapunov acompanhado da vizualização da seção de Poincaré correspondente. O número relativo de trajetórias caóticas obtidas equivale ao volume caótico do sistema correspondente ao regime dinâmico definido pelos parâmetros de acoplamento. Apresentamos também a relação entre o expoente de Lyapunov e o parâmetro G', que indica que não só a quantidade de caos do sistema é incrementada com G' mas também a divergência média entre trajetórias vizinhas. Outro resultado importante deste trabalho se refere à borda clássica para as variáveis de spin, a qual é oriunda de uma mudança de topologia do sistema. Observa-se que, em regiões próximas da borda, trajetórias vizinhas regulares apresentam afastamento exponencial, comportamento característico de trajetórias caóticas. Também foi observado afastamento exponencial para um pacote clássico de condições iniciais regulares preparado sobre a separatriz do movimento. O pacote clássico se deforma à medida que se aproxima da borda e, em tempos longos, forma seções de toros "acima e abaixo da separatriz na seção de Poincaré. O efeito de borda tem sido utilizado recentemente para explicar efeitos puramente quânticos em regimes semiclássicos / Abstract: In the present work, we show a systematic study of the chaotic volume in the classical Hamiltonian phase space associated to the Chaotic Maser Model as a function of the interaction parameters G and G'. The study has been realized using an average ensemble with 100 initial conditions. Each condition has been classified as chaotic or regular by means of their respective Lyapunov exponent together with their corresponding Poincaré section. The relative number of chaotic trajectories corresponds to the chaotic volume of the system for the dynamical regime determined by the coupling parameters. We also show the dependence of the Lyapunov exponent on the parameter G', which indicates that the amount of chaos and the average divergence between close trajectories both increase with G'. Another important result is connected with the classical border of the spin coordinates, which comes out from a topological change in the spin phase space. We have observed exponential departure of two nearby trajectories, an usual behavior of chaotic trajectories, which manifests here for regular trajectories close to the border . This sort of divergence has also been observed for a classical patch of regular initial conditions prepared on the separatrix region. The patch deforms itself near the border and, for long times, develops sections of tori both above and below the separatrix in the Poincaré section. The border effect has been recently used to explain purely quantum effects in semiclassical regimes / Mestrado / Física / Mestre em Física

In this thesis, the background and technical theory of the receivers are discussed. Methods used to search for periods, correlations, and delays in the time series of class II methanol masers at 6668 MHz and 12178 MHz are presented together with the observed variability of these sources. Background theory is given on, the processes by which massive stars are formed. The theory of astronomical masers and methanol maser excitation is given in detail. The receiver testing and observation technique chapters describe: the results and methods used to calibrate the two receivers, namely 2.5-cm and 4.5-cm, with central frequencies of 6668 MHz and 12178 MHz respectively, as well as data cap- ture methods for spectroscopic observations. The laboratory square law detector or radiometer was also calibrated to ensure that the noise diode temperature was accurately determined. There is 8.3 per cent deviation from an ideal square law detector. The time series and spectra for one methanol source, G351.42+0.64 which serves as a control source at 6668 MHz and 12178 MHz, one irregularly varying methanol source G351.78-0.54 at 6668 MHz, seven known quasi-periodic and periodic sources (G9.62+0.20E, G12.89+0.49, G188.95+0.89 and G328.24-0.55, at both 6668 MHz and 12178 MHz, and G331.13-0.24, G338.93-0.06, and G339.62-0.12, at 6668 MHz), and seven new methanol maser source regions (G0.092+0.663, G6.189-0.358, G8.832- 0.028, G8.872-0.493, G348.617-1.162, G351.688+0.171 and G358.460-0.391, at both 6668 MHz and 12178 MHz) are shown and discussed. The seven new sources were from the 6668-MHz Methanol Multi-Beam (MMB) survey Catalogues I and II. Periods were searched for using the Lomb-Scargle and epoch-folding methods. The quasi-periodic and periodic sources show diverse waveforms and diverse periods be- tween 29 and 511 days. From the seven new methanol maser sources, G8.872-0.493 (76 day period) and G358.460-0.391 (187 day period) both at 6668 MHz, were found to be variable and they are possible new candidates for the periodic or quasi-periodic group of sources. The Colliding Wind Binary (CWB) model is proposed by van der Walt (2011) as the source of the observed periodic variability in these regions. The properties of the binary systems using the 29 and 511 day period are discussed as well as the common features in the time series, such as long-term variations and flares. The source of the periodicities has not been finally determined but the foundation has been laid.

This thesis describes the properties of interstellar water maser sources, and other sources near 22 GHz. Calculations based on manufacturer's specifications of the 22 GHz mixer, which was to be used in a water radiometer, and on the size antenna aperture of the proposed antenna aperture, show the viability of constructing such a radiometer for spectral line and continuum work. Various sections of the radiometer were constructed, including the Cassegrain feed system and its support, an intermediate frequency amplifier and buffer, a timing control unit, and a data processor. These units are part of the radiometer, which is almost ready for observations of sources.

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Thesis (doctoral)--Universitetet i Lund. / Description based on print version record.

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