Many astronomers require large amounts of observational data to solve astrophysical problems and to validate theoretical hypotheses. It is therefore imperative that both the observer and telescope work efficiently, maximising data collection whilst minimising object selection and acquisition time. One method in which this can be achieved is through telescope automation. The advent of cheap integrated process controllers enables the system designer to realise novel control system architectures which were previously prohibitive to all but the largest of sites. This thesis reviews the development of processor based control systems in the astronomical and industrial environment and compares distributed and centralised control system architecture. It describes the design and construction of one such distributed control system for the St Andrews Twin Photometric Telescope.

The aim of this thesis has been to carry out 3D MHD simulations to investigate nonlinear MHD instabilities and the behaviour of solar coronal loops. The simulations have been carried out on a parallel computer using a new shock-capturing Lagrangian-remap code, LareSd. As part of the PhD this code has been extended to include resistivity allowing the study of the non-linear resistive evolution of the instability. In particular the kink instability in line-tied coronal loops has been studied. This was suggested as a possible explanation of compact loop flares, sudden brightenings of a coronal loop due to a release of energy which does not destroy the loop. For the kink instability to explain such flares it must drive reconnection. This requires high current densities, i.e. current sheets. The results presented in this thesis suggest that the formation of current sheets during the non-linear evolution of the kink instability is more complicated than was previously believed. Indeed, if the loop is allowed to evolve slowly until the instability is triggered than the current appears to saturate at a finite value. This suggests that the kink instability cannot explain a compact loop flare. LareSd has also been used to model space observations from NASA's SoHO (a joint NASA/ESA satellite) and TRACE satellites. These observations showed a group of rotating sunspots and their overlying system of loops. The simulations will allow further investigations of this behaviour to be carried out.

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Orientador: Rogério Custodio / Tese (doutorado) - Universidade Estadual de Campinas, Instituto de Química / Made available in DSpace on 2018-08-25T11:52:57Z (GMT). No. of bitstreams: 1 Pereira_DouglasHenrique_D.pdf: 3749609 bytes, checksum: b3ed317231247b116e3bdb8974c60c94 (MD5) Previous issue date: 2014 / Resumo: Este trabalho desenvolveu e aplicou métodos de química quântica, mais especificamente a teoria Gaussian 3, nos estudos de propriedades eletrônicas e estruturais de átomos e molécula e encontra-se dividido em 5 capítulos. No capítulo 1 são apresentados os resultados da implementação de pseudopotencial na teoria G3 para 446 reções envolvendo moléculas contendo átomos do 1º, 2º e 3° período representativo da tabela periódica, método denominado G3CEP. O método G3CEP foi aplicado para cálculos de entalpias de formação, energias de atomização e ionização, afinidade eletrônica e de prótons. A implementação final apresentou um desvio absoluto médio total de 1,29 kcal mol-1 para o G3CEP e 1,16 kcal mol-1 para o método G3. Outro aspecto importante associado ao uso do método G3CEP é a redução do tempo de CPU. Em geral, a redução no tempo de CPU varia entre 7-60%, dependendo do tamanho da molécula e dos tipos de átomos presentes na estrutura. O capítulo 2 mostra a aplicação do método G3CEP juntamente com o método original G3, no estudo de 43 barreiras rotacionais internas. Neste estudo procurou-se analisar a precisão dos métodos, bem como entender os efeitos estereoeletrônicos responsáveis pelas conformações mais estáveis. A comparação dos resultados demonstra que os cálculos G3 e G3CEP são mais precisos do que os cálculos MP4 ou cálculos incluindo a energia do ponto zero em relação aos dados experimentais. Considerando o tamanho das moléculas estudadas, uma redução de 32 % no tempo de CPU foi obtida com a utilização do método G3CEP. No capítulo 3 foram aplicados três métodos de alta precisão, os quais são: método Gaussian-3 (G3), Monte Carlo Quântico de Difusão (MCQD) e Coupled Cluster (CCSD(T)/aug-cc-pVQZ) para os cálculos de potenciais de ionização sucessivos e os conjuntos testes estudados foram os três primeiros períodos da tabela periódica [H-Ar]. O método CCSD(T) apresentou melhor precisão nos resultados para as ionizações do 1° e 2° período, seguido do G3 e por fim o MCQD. Para o 3º período o método MCQD é o mais preciso, seguido dos métodos G3 e CCSD(T). Analisando-se os três períodos juntos, o método MCQD juntamente com o método G3 mostraram resultados similares para o potencial de ionização com um desvio absoluto médio de 1,44 eV. O capítulo 4 mostra os resultados da implementação de pseudopotencial na teoria G3(MP2). Este trabalho vem dando continuidade a teoria desenvolvida no capítulo 1, embora agora, utilizando uma versão de ordem reduzida a qual elimina os cálculos em nível MP4 reduzindo assim a demanda computacional. Os resultados mostram um desvio absoluto médio total de 1,67 kcal mol-1 para o G3CEP(MP2) e 1,47 kcal mol-1 para o método G3(MP2) com uma redução computacional de 10-40 %. Por final, o capítulo 5 traz a aplicação do método G3CEP(MP2) e G3(MP2) no estudo da preferencia endo/exo de reações de Diels-Alder. A reação do anidrido maleico e ciclopentadieno apresentou uma menor energia de ativação para o aduto endo em relação ao aduto exo para ambas as metodologias empregadas. Os parâmetros de avaliação termodinâmicos apontam para o produto exo com o método G3(MP2) e para o produto endo utilizando o método G3CEP(MP2). A reação de acrilonitrila com o ciclo-hexadieno mostrou que a preferencia exo é observado tanto pelo controle cinético como pelo termodinâmico para as metodologias empregadas / Abstract: Abstract This study developed and applied methods of quantum chemistry, specifically the Gaussian 3 theory in studies of electronic and structural properties of atoms and molecule and is divided into five chapters: In Chapter 1, related to the development of methods, the results of the implementation of pseudopotential in the G3 theory for 446 atoms and molecules containing the 1st, 2nd and 3rd representative period of the periodic table, method referred to as G3CEP are presented. The G3CEP method was applied to calculations of enthalpies of formation, atomization and ionization energy, electron and protons affinity. The final implementation presented a total mean absolute deviation of 1.29 kcal mol-1 for G3CEP and 1.16 kcal mol-1 for G3 method. Another important aspect associated with the use of G3CEP is the reduction of CPU time. In general CPU time has been reduced from 7% to 60% depending on the size of the molecule and type of atom present in the structure. Chapter 2 shows the application of the G3CEP method together with the original G3, in the study of 43 internal rotational barriers. This study sought to analyze the accuracy of the methods as well as to understand the stereoelectronic effects responsible for the most stable conformations. The comparison of the results shows that the G3 calculations and G3CEP are more accurate than MP4 calculations or calculations including zero point energy in relation to the experimental data. Considering the size of the molecules studied, a 32% reduction in CPU time was obtained using the G3CEP method. In Chapter 3, three methods of high accuracy were applied. They are: Gaussian-3 theory (G3), Diffusion Quantum Monte Carlo (DQMC) and Coupled Cluster (CCSD(T)/aug-cc-pVQZ) for calculations of successive ionization potentials and test sets studied were the first three periods of the periodic table [H-Ar]. The CCSD(T) method showed better accuracy in the results for the ionization of the 1st and 2nd period, followed by G3 and finally DQMC. For the 3rd period the DQMC method is the most accurate, followed by G3 and CCSD(T). Analyzing the three periods together, the DQMC with the G3 methods showed similar results for the ionization potential with a mean absolute deviation of 1.44 eV. Chapter 4 shows the results of the implementation of pseudopotential in the G3(MP2) theory. This work is continuing the theory developed in Chapter 1, although now using a reduced-order version which eliminates the calculations at MP4, thereby, reducing the computational demand. The results show a total mean absolute deviation of 1.67 kcal mol-1 for G3CEP(MP2) and 1.47 kcal mol-1 for G3(MP2) with a reduced computational of 9-40%. By the end, chapter 5 brings the application of methods G3CEP(MP2) and G3(MP2) in the study of preference endo/exo of Diels-Alder reaction. The reaction of maleic anhydride and cyclopentadiene showed lower activation energy for the endo adduct compared to the exo adduct for both methodologies. The evaluation of the thermodynamic parameters indicate the exo product for the G3(MP2) method, and for the endo product using the G3CEP(MP2) method. The reaction of acrylonitrile with cyclohexadiene showed that the exopreference is observed by both the thermodynamic and kinetic controls to the methodologies applied / Doutorado / Físico-Química / Doutor em Ciências

This paper is concerned with a generalization of the concept of unitary equivalence of spectral measures on a Baer *-semigroup. A connection is made between abstract spectral measures, and three other distinct mathematical systems. Chapter II is devoted specifically to generalizing the concept of a spectral measure and to determining necessary and sufficient conditions for which two spectral measures will be unitarily equivalent. Chapter III discusses the problem of each (C(M) , qμ) being type I in terms of cycles, the basic elements of C(M). In Chapter IV it is shown that in a Loomis *-semigroup each type I (C(M) , qμ) will be type I homogeneous. Chapter V relates the study of unitary equivalence of spectral measures and the unitary equivalence of normal elements in a Finite Dimensional Baer *-algebra. / Ph. D.

Duomenų perdavimas elektros tinklais. Magistro baigiamasis darbas elektronikos inžinerijos laipsniui. Vilniaus Gedimino technikos universitetas. Vilnius, 2012, 67 p., 38 iliustr., 15 lent., 27 bibl., 3 priedai. Darbo tikslas – sukurti ir ištirti duomenų perdavimo elektros tinklais sistemos modelį. Darbe išnagrinėti šiuolaikiniai duomenų perdavimo elektros tinklais standartai, ištirti šiuolaikiniai duomenų perdavimo elektros tinklais metodai, atskleisti pagrindiniai šiuolaikinių duomenų perdavimo elektros tinklais metodų trūkumai. Siekiant sumažinti šiuolaikinių sistemų trūkumus sudarytas duomenų perdavimo elektros tinklais sistemos modelis su dirbtiniu neuronų tinklu. Gautieji darbo rezultatai atitiko užduotyje iškeltus reikalavimus. / The goal of this work was to create and analize a power line comunication model. This work analizes up to date power line comunication standards, methods and the main disadvantages of these methods are discussed. To compensate these disadvantages a power line communication system model with an artificial neural network was proposed. The results of this work suits the task. The systems with the artificial neural network model gave positive results.

This paper studies the triggers and the agglomeration of M&A activity within clusters constituted by time, market and industry. Based on almost 500,000 individual transactions, we find that industry factors play a significant role in triggering activity and that M&A agglomerates strongly across related industries. While clustering in time turns out to be insignificant, stock-market effects can be either an attracting or a repelling force, depending on the type of deal examined. This supports the view that merger waves are largely driven by industry shocks.

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The purpose of this study was to compare the effectiveness of the classical estimator with that of a supplementary sample non-parametric empirical Bayes estimator in detecting an out-of-control situation arising in statistical quality control work. The investigation was accomplished through Monte Carlo simulation on the IBM-7040/1401 system at the Virginia Polytechnic Institute Computing Center, Blacksburg, Virginia. In most cases considered in this study, the sole criterion for accepting or rejecting the hypothesis that the industrial process is in control was the location of the estimate on the control chart for fraction defectives. If an estimate fell outside the 30 control limits, that particular batch was said to have been produced by an out-of-control system. In other cases the concept of "runs" was included as an additional criterion for acceptance or rejection. Also considered were various parameters, such as the mean in-control fraction defectives, the mean out-of-control fraction defectives, the~first sample size, the standard deviation of the supplementary sample estimates, and the number of past experiences used in computing the empirical Bayes estimator. The Monte Carlo studies showed that, for almost any set of parameter values, the empirical Bayes estimator is much more effective in detecting an out-of-control situation than is the classical estimator. The most notable advantage gained by using the empirical Bayes estimator is that long-range lack of detection is virtually impossible. / M.S.

No / The paper examines the determinants of stabilization and its impact on the aftermarket prices. We use a unique dataset to relax several assumptions in the stabilization literature. We find that underwriters support IPO prices shortly after listing, particularly in cold markets and when demand is weak. We also show that stabilized IPOs are more common amongst reputable underwriters. This finding suggests that stabilization may be used as a mechanism to protect the underwriter’s reputation. It also implies that reputable underwriters may possess private information and price IPOs closer to their true values (i.e., higher than those indicated by the weak premarket demand). Consistent with the latter view, we show that stabilized IPOs are offered at higher prices and suffer less underpricing than those indicated by the premarket demand, firm characteristics and market-wide conditions. The post-IPO performance results indicate that stabilized IPOs are unlikely to be mispriced as their prices do not exhibit any significant reversal after the initial stabilization period. We conclude that stabilization may be superior to underpricing as it protects investors from purchasing overpriced IPOs, benefits issuers by reducing the total money “left on the table” and enhances the overall profitability of underwriters.