772 resultados para Right to information
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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
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This thesis presents the outcomes of a Ph.D. course in telecommunications engineering. It is focused on the optimization of the physical layer of digital communication systems and it provides innovations for both multi- and single-carrier systems. For the former type we have first addressed the problem of the capacity in presence of several nuisances. Moreover, we have extended the concept of Single Frequency Network to the satellite scenario, and then we have introduced a novel concept in subcarrier data mapping, resulting in a very low PAPR of the OFDM signal. For single carrier systems we have proposed a method to optimize constellation design in presence of a strong distortion, such as the non linear distortion provided by satellites' on board high power amplifier, then we developed a method to calculate the bit/symbol error rate related to a given constellation, achieving an improved accuracy with respect to the traditional Union Bound with no additional complexity. Finally we have designed a low complexity SNR estimator, which saves one-half of multiplication with respect to the ML estimator, and it has similar estimation accuracy.
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Most electronic systems can be described in a very simplified way as an assemblage of analog and digital components put all together in order to perform a certain function. Nowadays, there is an increasing tendency to reduce the analog components, and to replace them by operations performed in the digital domain. This tendency has led to the emergence of new electronic systems that are more flexible, cheaper and robust. However, no matter the amount of digital process implemented, there will be always an analog part to be sorted out and thus, the step of converting digital signals into analog signals and vice versa cannot be avoided. This conversion can be more or less complex depending on the characteristics of the signals. Thus, even if it is desirable to replace functions carried out by analog components by digital processes, it is equally important to do so in a way that simplifies the conversion from digital to analog signals and vice versa. In the present thesis, we have study strategies based on increasing the amount of processing in the digital domain in such a way that the implementation of analog hardware stages can be simplified. To this aim, we have proposed the use of very low quantized signals, i.e. 1-bit, for the acquisition and for the generation of particular classes of signals.
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Investigating parents’ formal engagement opportunities in public schools serves well to characterize the relationship between states and societies. While the relationship between parental involvement and students’ academic success has been thoroughly investigated, rarely has it been seen to indicate countries’ governing regimes. The researcher was curious to see whether and how does parents’ voice differ in different democracies. The hypothesis was that in mature regimes, institutional opportunities for formal parental engagement are plenty and parents are actively involved; while in young democracies there are less opportunities and the engagement is lower. The assumption was also that parental deliberation in expressing their dissatisfaction with schools differs across democracies: where it is more intense, there it translates to higher engagement. Parents’ informedness on relevant regulations and agendas was assumed to be equally average, and their demographic background to have similar effects on engagement. The comparative, most different systems design was employed where public middle schools last graders’ parents in Tartu, Estonia and in Huntsville, Alabama the United States served as a sample. The multidimensional study includes the theoretical review, country and community analyses, institutional analysis in terms of formal parental involvement, and parents’ survey. The findings revealed sizeable differences between parents’ engagement levels in Huntsville and Tartu. The results indicate passivity in both communities, while in Tartu the engagement seems to be alarmingly low. Furthermore, Tartu parents have much less institutional opportunities to engage. In the United States, multilevel efforts to engage parents are visible from local to federal level, in Estonia similar intentions seem to be missing and meaningful parental organizations do not exist. In terms of civic education there is much room for development in both countries. The road will be longer for a young democracy Estonia in transforming its institutional systems from formally democratic to inherently inclusive.
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Il compressed sensing è un’innovativa tecnica per l’acquisizione dei dati, che mira all'estrazione del solo contenuto informativo intrinseco di un segnale. Ciò si traduce nella possibilità di acquisire informazione direttamente in forma compressa, riducendo la quantità di risorse richieste per tale operazione. In questa tesi è sviluppata un'architettura hardware per l'acquisizione di segnali analogici basata sul compressed sensing, specializzata al campionamento con consumo di potenza ridotto di segnali biomedicali a basse frequenze. Lo studio è svolto a livello di sistema mediante l'integrazione della modulazione richiesta dal compressed sensing in un convertitore analogico-digitale ad approssimazioni successive, modificandone la logica di controllo. Le prestazioni risultanti sono misurate tramite simulazioni numeriche e circuitali. Queste confermano la possibilità di ridurre la complessità hardware del sistema di acquisizione rispetto allo stato dell'arte, senza alterarne le prestazioni.
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Abstract to be posted.