958 resultados para Fourier transformations
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Bulletin of the Malaysian Mathematical Sciences Society
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Communications in Algebra
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Dissertação apresentada na Faculdade de Ciências e Tecnologia da Universidade Nova de Lisboa para obtenção do grau de Mestre em Engenharia Electrotécnica e de Computadores
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In this paper, the fractional Fourier transform (FrFT) is applied to the spectral bands of two component mixture containing oxfendazole and oxyclozanide to provide the multicomponent quantitative prediction of the related substances. With this aim in mind, the modulus of FrFT spectral bands are processed by the continuous Mexican Hat family of wavelets, being denoted by MEXH-CWT-MOFrFT. Four modulus sets are obtained for the parameter a of the FrFT going from 0.6 up to 0.9 in order to compare their effects upon the spectral and quantitative resolutions. Four linear regression plots for each substance were obtained by measuring the MEXH-CWT-MOFrFT amplitudes in the application of the MEXH family to the modulus of the FrFT. This new combined powerful tool is validated by analyzing the artificial samples of the related drugs, and it is applied to the quality control of the commercial veterinary samples.
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The reported productivity gains while using models and model transformations to develop entire systems, after almost a decade of experience applying model-driven approaches for system development, are already undeniable benefits of this approach. However, the slowness of higher-level, rule based model transformation languages hinders the applicability of this approach to industrial scales. Lower-level, and efficient, languages can be used but productivity and easy maintenance seize to exist. The abstraction penalty problem is not new, it also exists for high-level, object oriented languages but everyone is using them now. Why is not everyone using rule based model transformation languages then? In this thesis, we propose a framework, comprised of a language and its respective environment, designed to tackle the most performance critical operation of high-level model transformation languages: the pattern matching. This framework shows that it is possible to mitigate the performance penalty while still using high-level model transformation languages.
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Aziridines, a class of organic compounds containing a three membered heterocycle with a nitrogen atom, are extremely valuable molecules in organic and medicinal chemistry. They are frequently used as versatile precursors in the synthesis of natural products, and many biologically active molecules possess the aziridine moiety. The reactivity of aziridines has been studied, for example, in ring-opening reactions with thiols. However, not much interest seems to be given to reactions of aziridines in aqueous media, despite the numberless advantages of using water as solvent in organic chemistry. The nucleophilic ring-opening reaction of aziridines in aqueous media was here explored. Following the Kaplan aziridine synthetic methodology, in which pyridinium salts undergo a photochemical transformation to give bicyclic vinyl aziridines, new aziridines were synthetized. Their nucleophilic ring-opening reaction in water under physiological conditions was investigated and a range of sulphur, nitrogen, carbon and oxygen nucleophiles tested. Thiols, anilines and azide proved to be good nucleophiles to react with the aziridines, giving the ring-opening product in moderate to good yields. The best results were obtained with thiols, more specifically with cysteine-derived nucleophiles. Preliminary results show that these bicyclic vinyl aziridines can modify calcitonin, a peptide containing two cysteine amino acids residues, grating them the potential to be used in bioconjugation as ligands to cysteine-containing proteins, or even as enzyme inhibitors of, for example, cysteine proteases. Additionally, exploratory investigations suggest that the separation of both enantiomers of the bicyclic vinyl aziridine can be performed by taking advantage of an enzymatic methodology for the resolution of racemic secondary alcohols. Both enantiomers would be highly valuable as precursors in the synthesis of enantiomerically pure molecules, as no other method is currently reported for their separation.
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Este trabalho foi realizado utilizando dados coletados em uma Floresta de Transição, em uma área pertencente à Fazenda Maracaí no Noroeste de Sinop, MT, com dados micrometeorológicos obtidos com o sistema de correlação de vórtices turbulentos (Eddy Covarience) instalado numa torre de 40 metros. Teve como objetivo principal estudar as potencialidades da análise de Fourier aplicada a dados de fluxo de Calor Latente (LE), Calor Sensível (H) e Temperatura (T). Para os cálculos foram feitas médias de 3 em 3 horas para cada mês, ao longo do período de 1999 a 2005, para as variáveis estudadas. Os períodos dominantes encontrados foram de 24; 12; 4 e 3,4 horas. Os dois primeiros são atribuíveis ao movimento de rotação da Terra, ou seja, à periodicidade dia/noite. Quanto aos dois períodos menores, há indícios que estão relacionados com a dinâmica de abertura dos estômatos. Assim sendo, os resultados deste trabalho indicam que os fatores que influenciam predominantemente as variáveis microclimatológicas durante o dia (freqüências entre 10-5 a 10-4 Hz) são a radiação solar e a dinâmica de abertura dos estômatos, um resultado que destaca as potencialidades da aplicação do método de Fourier no estudo da dinâmica de microclimas em ecossistemas.
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Let V be an infinite-dimensional vector space and for every infinite cardinal n such that n≤dimV, let AE(V,n) denote the semigroup of all linear transformations of V whose defect is less than n. In 2009, Mendes-Gonçalves and Sullivan studied the ideal structure of AE(V,n). Here, we consider a similarly-defined semigroup AE(X,q) of transformations defined on an infinite set X. Quite surprisingly, the results obtained for sets differ substantially from the results obtained in the linear setting.
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A partir de las políticas de descentralización llevadas adelante en Argentina desde la década de los ochenta, las provincias han adquirido desde entonces una importante serie de nuevas funciones lo cual las ha obligado a ampliar y diversificar sus estructuras burocráticas y administrativas. Lo que este proyecto busca abordar es un análisis de las transformaciones ocurridas durante los últimos veinte años en la organización burocrática del estado provincial en Córdoba. El proyecto pretende indagar dos aspectos de la organización burocrática: por un lado, el diseño organizacional institucional (leyes de Ministerios) y la división del trabajo que ello implica; y por otro lado, los principales procesos administrativos transversales que articulan funcionalmente las diferentes áreas de la burocracia provincial (administración financiera y recursos humanos). A partir de ello nos interesa poner en relación estas transformaciones con los cambios que va experimentando la agenda gubernamental. Suponemos, en este sentido, que los cambios organizacionales responden a cambios en dicha agenda y a la relación de fuerzas políticas que va implícita en la conformación de las mismas. De este modo, nuestra hipótesis plantea que los cambios organizaciones generados por la transformación de las agendas se manifiestan de forma más inmediata en la dimensión del diseño organizacional, mientras que los procesos administrativos transversales experimentan cambios más graduales y no necesariamente vinculados a las transformaciones de la primera dimensión. El objetivo general es analizar las transformaciones de la Administración Pública Provincial (APP) en la provincia de Córdoba, a través de dos dimensiones (el diseño de la organización burocrática y los procesos administrativos transversales), desde el retorno a la democracia (1983) a la actualidad. La investigación será realizada a la luz de posturas epistemológicas y metodológicas que en las ciencias sociales sustentan la triangulación de métodos. Recurriremos tanto a fuentes documentales y estadísticas para reconstruir el proceso de transformación de la APP, como a entrevistas semiestructuradas con actores claves para indagar sobre las dimensiones identificadas en el proyecto. Se encuadra en lo que metodológicamente se denomina "estudio de caso". La investigación permitirá fortalecer el estudio de la administración y las organizaciones públicas, lo que representa una tarea altamente significativa (y necesaria) para el mejoramiento del sector público y las necesidades de la ciudadanía. El impacto esperable es la explicitación y sistematización de las transformaciones del aparato burocrático, que puedan ser observadas, mejoradas y desarrolladas por el conjunto de las carteras ministeriales, y la confección de estrategias y tecnologías de gestión que permitan incrementar las capacidades de la administración pública provincial en la realización de las políticas y la resolución de los problemas sociales.
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New sufficient conditions for representation of a function via the absolutely convergent Fourier integral are obtained in the paper. In the main result, Theorem 1.1, this is controlled by the behavior near infinity of both the function and its derivative. This result is extended to any dimension d &= 2.
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Neolignans, generated by oxydative dimerization of propenylphenol and/or allylphenol, undergo further modifying steps. These biosynthetic reactions, confirmed in vitro, include Cope, retro-Claisen and Claisen rearrangements. Additionally acid catalysis effects convertions of bicyclo [3.2.1] octanoid neolignans into hydrobenzofuranoid neolignans, or inversely of hydrobenzofuranoid neolignans into bicyclo [3.2.1] octanoid neolignans, of hydrobenzofuranoid neolignans into futoenone type neolignans, of tetrahydrofuran neolignans into aryltetralin neolignans, as well as modifications by Friedel - Crafts reactions and the transformation of aryltetralin neolignans into arylindanones by pinacoline - pinacolone type rearrangement.
Posada a punt i validació de l'anàlisi d'urea en llet crua mitjançant IR per transformada de Fourier
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L’objectiu principal d’aquest projecte és posar a punt el mètode d’anàlisi d’urea en llet crua de vaca mitjançant la tècnica d’Infraroig per Transformada de Fourier (Fourier Transform Infrared Spectroscopy, FTIR). S’haurà de portar a terme la validació del mètode per FTIR (seguint els criteris de la ISO 17025) mitjançant la comparació amb el mètode de referència utilitzat actualment al laboratori.
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"Vegeu el resum a l'inici del document del fitxer adjunt."