Diss. (sammanfattning) Stockholm : Karol. inst., 2004. / Härtill 4 uppsatser.

Thesis (in competition for the Angas Engineering Scholarship)--University of Adelaide, 1948. / Typewritten copy.

This thesis deals with cultural patrimony in Três Mártires, RS, Brazil, in order both to describe and to study how the creation and the foundation of that society were possible. Also, the research emphasizes the immigration process in the Fourth Colony, as well as the arrival of the first Italian families in that region. Families from different places and provinces officially came to and formed the Fourth Colony, but those ones which predominate in Três Mártires were those of Mantovanos, which are: Anversa, Avosani, Maffini, and Stradiotto. Another factor that is highlighted in this study, both for the foundation of the town and for the preservation of its custom, regards the tradition and the region since it emphasized and answered the needs of the first Italian families who arrived in that place. It was for this reason that the community was called Três Mártires, by being patrons the Mission Holy Martyrs. Based on that, this study approaches the local patrimony, describing issues concerning religiosity, Italian culture, work, and leisure in the community. Many authors inform on how this process happened in Três Mártires. Moreover, the research deals with aspects of customs traditions of immigrants which are preserved until today. Therefore, this work aims at providing a description of these relevant issues, thus, constituting answers to strengthen the preservation of local cultural heritage in order to keep alive the traditions and the customs of those people: the Italian identity and religiosity, with support not only for its patrimony, but also for its revitalization. We also propose a means of providing Três Mártires with information about the region through the local media. Thus, we suggest media spaces in cultural programs about the Fourth Colony in order to divulgate matters events, and the patrimony itself though the radio. The research product offers a valuation of the cultural and the religions patrimony along with the customs and the traditions of the community through radio programs. Such programs are focused on the Fourth Colony, but this proposal is part of Três Mártires, aiming to improve the local patrimony and appreciate what the community has to offer for those who do not know Três Mártires. / A presente dissertação consiste numa reflexão sobre o patrimônio cultural de Três Mártires a fim de descrever e estudar, num primeiro momento, como se deram a criação e a fundação da comunidade. Neste sentido, a pesquisa enfatiza o processo imigratório na Quarta Colônia, bem como a vinda das primeiras famílias italianas para tal região. Famílias de diversos locais e províncias da Itália vieram para a Quarta Colônia, mas as que predominam em Três Mártires são as dos Mantovanos, que são: Anversa, Avosani, Maffini e Stradiotto. Outro fator que é destaque neste estudo, tanto para a fundação da localidade quando para a preservação dos costumes, diz respeito às tradições e à religiosidade do local. Isto marcou muito o contexto social e econômico da região pelo fato de dar ênfase e atender aos anseios das primeiras famílias italianas que chegaram ao local. Foi por este motivo que a comunidade foi denominada de Três Mártires, sendo padroeiros os Santos Mártires das Missões. Com base nisto, a presente dissertação versa sobre o patrimônio local, descrevendo questões sobre a religiosidade, a cultura italiana, o trabalho e o lazer da comunidade. Diversos autores, no decorrer do texto, trazem informações de como este processo aconteceu em Três Mártires. Ademais, a pesquisa aborda aspectos dos costumes e das tradições dos imigrantes que são preservados até os dias de hoje. Portanto, o trabalho visa a fazer uma descrição destas questões relevantes, constituindo, assim, respostas para fortalecer a preservação do patrimônio cultural local. Isso objetiva a manter vivas as tradições e os costumes de um povo: a italianidade e a religiosidade, com respaldo não somente para a patrimonialidade, mas também para a revitalização. Por fim, em resposta a este estudo realizado, propomos um meio de enfatizar o processo de valorização de Três Mártires com informações do local na mídia regional. Para isto, sugerimos espaços midiáticos nos programas culturais da Quarta Colônia, com fins de divulgar assuntos, eventos e o próprio patrimônio na rádio. Ademais, o produto de pesquisa propõe valorizar o patrimônio cultural e religioso, além dos costumes e tradições da comunidade através dos programas de rádio. Os programas são voltados para a Quarta Colônia, tendo como foco principal de análise a comunidade de Três Mártires, com intuito de melhorar o patrimônio local e valorizar o que a comunidade tem a oferecer aos que não conhecem Três Mártires.

The demand for higher throughput and lower latency in telecommunication systems is growing. Upcoming telecommunication systems will operate at higher frequencies (above 15 GHz) compared with previous systems (below 6 GHz). Antenna arrays will be employed in upcoming systems for increased link budget (coverage) and multiple input multiple output channels. This implies that narrow beams will be used. Beam tracking and beam steering is necessary to follow the user equipment. It is hypothesised that changing beam direction changes the channel condition for the communication link. In this work beam changes in data gathered with a 5G testbed is analysed at both 15 GHz and 28 GHz. The results show that the channel is indeed affected by beam changes. Statistical results of the conducted analysis are presented followed by specific examples on how the channel is affected by the beam changes. Knowledge on how the channel is affected by beam changes is of interest when designing systems for beam selection. The results show a nearly threefold increase of rank changes immediately after a beam change at 15 GHz. The probability for a rank change up or down is found to be equal. At 28 GHz the metric used for channel richness is singular value ratio. The statistical results show that the difference in singular value ratio before and after a beam change is increased by a factor 2. It is also shown that grating lobes may have a significant effect on the channel richness when changing beam direction.

Solar wind shocks and the intracluster medium comprise hot, low-density plasmas with few Coulomb collisions. Electrons there are not fluid and so gain and exchange energy by interaction with a variety of plasma waves. We explore two mechanisms for electron energization in such plasmas. In 2D kinetic simulations of solar wind shocks with low beta (magnetic pressure greater than thermal pressure), fast-mode / oblique-whistler waves accelerate electrons in bulk via proton-scale parallel electric fields; electrons’ bulk kinetic energy then converts to heat via magnetic field-aligned electrostatic wave scattering. We show and measure the heating for 2D shocks of varying magnetic obliquity and Mach number, and we qualitatively map the mechanism’s shock parameter regime. Next, consider the intracluster medium: a high-beta plasma (thermal pressure greater than magnetic pressure) in which Megaparsec-scale motions promptly trigger nanoparsec-scale plasma waves, which in turn can scatter 1–100 MeV cosmic ray electrons. Small-scale scattering combined with large-scale motion can heat electrons, and this process is called magnetic pumping. We use 1D simulations of plasma subjected to continuous bulk compression to measure the efficiency of magnetic pumping upon cosmic ray electrons. It is speculated that magnetic pumping may help re-accelerate MeV electrons to radio-emitting energies and so help explain the origin of diffuse, MHz–GHz radio halos enshrouding some clusters of galaxies.

This thesis investigates statistical correlation as a means to enhance the use of ground-based radar in analyzing satellite-path millimeter wave propagation through rain and ice crystals. The technique presented involves correlating dB values of the satellite signal attenuation and polarization isolation with dBZ values of radar backscatter from each of 128 range gates. In it, Pearson product moment correlation coefficients are calculated for attenuation and backscatter and for isolation and backscatter. When these coefficients are plotted versus radar range, one of four certain characteristic patterns usually appears. Ice-crystal depolarization produces a pattern of near zero attenuation coefficients and varying isolation coefficients. Rain produces a correlation pattern in which the attenuation coefficient pattern is nearly mirror image of the isolation coefficient pattern. A special case of the rain event occurs when the cross-polarized satellite signal is essentially constant. The correlation patterns for this case are exact mirror images. Rain attenuation and depolarization accompanied by additional depolarization from another source, produce a correlation pattern that is not symmetrical. This is due to the additional depolarization. Discussion of these expected patterns and examples of each are presented. / Master of Science

The instantaneous performance of a site diversity system is analyzed. This analysis is performed using instantaneous diversity gain (a new parameter for describing diversity performance) and the correlation coefficient. Also, a relationship between the correlation coefficient and instantaneous diversity gain was established. In addition, a review of statistical diversity gain and existing models of statistical diversity gain were also presented. Measured statistical diversity gain data from the VPI&SU site diversity experiment were also presented and compared with instantaneous diversity gain. The relationship between the correlation coefficient and instantaneous diversity gain was used to present a crude model of diversity gain. This model was compared with the model of Hodge. Margin calculations were performed to display the usefulness of instantaneous diversity gain. These were performed using the VPI&SU site diversity experiment data. / Master of Science

Dual polarization allows a communication system to transfer twice as much information as a single polarized communication system, with no increase in the required bandwidth. Site diversity may be used in high frequency satellite communication systems to reduce the effects of attenuation and depolarization due to rain and ice. This thesis examines dual polarized site diversity satellite communication systems to determine how such systems would perform under operating conditions. Three diversity system models, including a new model which incorporates local weather patterns, are discussed and compared. The problem of how to select the best signals from the available diversity replicas is investigated for both PSK and FM modulation schemes. A new technique is proposed for combining the effects of attenuation. and isolation into a single criterion for FM systems. The thesis considers methods for improving dual polarized site diversity system performance. Compensation schemes, coherent signal addition, and optimum site location are investigated. A compensation scheme using pilot tones is proposed. Finally, the performance of operational PSK and FM systems is simulated using data from a VPI & SU satellite beacon experiment. / M.S.

The reliability of RFID systems depends on a number of factors including: RF interference, deployment environment, configuration of the readers, and placement of readers and tags. While RFID technology is improving rapidly, a reliable deployment of this technology is still a significant challenge impeding wide-spread adoption. This research investigates system software solutions for achieving a highly reliable deployment that mitigates inherent unreliability in RFID technology. We have considered two different problem domains for large scale RFID deployment. One is item tracking and the other is guidance-monitoring. Item tracking considers applications that have statically placed RFID readers to observe the RFID tagged objects in motion. An airport scenario to observe the tagged baggage or warehouse scenarios to track the tagged goods are examples of item tracking applications. A self guided tour, search and rescue scenario or a visually impaired person looking for direction and guidance in a tagged environment are examples of item location applications. It is observed that there is a notion of path that follows the direction and flow of the mobile items in the item tracking applications and a path gets created along the direction and flow of the mobile object in item location applications. A system level knowledge of the data flow can benefit the system in different aspects such as improved reliability, resource management and real time response. We have designed and implemented an RFID middleware for item tracking: RF²ID (Reliable Framework for Radio Frequency Identification) to organize and support queries over data streams in an efficient manner. We have developed (1) a virtual reader abstraction to improve the potentially error-prone nature of reader generated data (2) a novel path abstraction to capture the logical flow of information among virtual readers. Prototype implementation using both RFID readers and simulated readers using an empirical model of RFID readers show that RF²ID is able to provide high reliability, support path-based object detection and use efficient resource management techniques. We propose a middleware solution that takes into account the data flow information for item location application that requires real time response. The guidance-monitoring scenario considers mobile RFID readers that traverse in a tagged environment. We consider the scenario of an Assisted Living Center for elderly residents as a motivating guidance-monitoring application. The solution for guidance-monitoring system is called GuardianAngel. The application scenario considers a tagged indoor environment with residents having their own RFID readers to provide them with adequate information about the surroundings. The guidance and monitoring requirement can be conflicting. The guidance information requires very fine grain information about the environment to make proper decisions. On the other hand, the monitoring system must not have a fine grain knowledge which can introduce concerns such as privacy concerns. We consider this aspect during the design and implementation. The system is a two layered infrastructure that has the upper layer which is the monitoring layer. This layer is in charge of monitoring of the actors in the environment. The monitoring layer is physically a set of distributed virtual stations that have the knowledge about the environment. The environment itself is equipped with RFID tags. The residents of the environment have the mobile object that has a sensing element and a computing element (e.g., handhold device with a portable RFID reader) - the guidance server runs on this mobile object. The guidance server is in charge of making local decisions to the users. It is resource limited and asks for new information from the virtual stations as needed. The guidance server also provides the monitoring server with the information regarding the status of the mobile object. But the status information is not fine grain information - the guidance server wraps up the information over a period of time and over a larger region to hide the detailed information of the users.The system uses the logical path based abstraction to guide the users. We have implemented the real testbed using grid structured RFID devices along with scalability study using emulated RFID readers. The basic contribution of our work is based on providing novel middleware solution that is able to serve the application taking into account the inherent unreliability of RFID technology. Our path abstraction that uses the physical flow of data as an ally to generate a logical system level flow enhances the performance in many ways.

The study of continuum sky background spectrum at low radio frequencies has achieved specific importance in present day observational cosmology . At these low frequencies the sky continuum is contributed by the extragalactic radio sources together with the synchrotron emission of the Milky Way as well as CMB. Following the recombination, the energy exchange between the primordial neutral hydrogen and CMB photons, during its propagation through the ”Dark ages” as well as the ”cosmic dawn” resulted in absorption and emission features in CMB spectrum which evolved with the evolution of the HI over cosmic time. Due to cosmological expansion of the Universe such spectral signatures of cosmological origin is now redshifted to low radio wavelengths. Although the peak to peak amplitudes of the same are smaller by orders of magnitude than the total galactic and extragalactic contribution at these frequencies the later is expected to be smooth over the scales of few hundred MHz. Hence, except for the extreme cases where the time scale over which such radiative transfer interaction occurred is very long and therefore the spectral fluctuations are spread over a large range of frequencies, these cosmological radiation signatures should be detectable at meter wavelengths. The duration and frequency at which such spectral signatures may occur can give constraints on the physical processes that governed the process of such energy exchange at a very early time, the history of evolution of the gas and the nature and evolution of sources of first light in the Universe. Measurements of the absolute brightness of the continuum background at meter wavelengths and detection of the spatial and spectral variations can therefore be an important probe of cosmology. In addition, measurements to date suggest that the radio background that is of extragalactic origin consists of CMB plus a power-law spectrum and has a brightness temperature of (1.2 ± 0.09) × (ν/1 GHz)−2.60±0.04 K. Surprisingly, the sky brightness corresponding to discrete radio sources detected in the deepest surveys to date account for only a fraction of the extragalactic radio background, even after excluding the CMB. Improved measurements of the radio background and, in particular, the spectrum at long wavelengths where errors are relatively larger, are important in estimating the spectrum of the unexplained part and thereby constraining the sources of this cosmic radiation. The wideband measurements at meter wavelengths pose limit on the accuracy of such measurements where the errors are relatively large. The instrument systematics, which are frequency dependent, in interaction with the sky signal may result in an incorrect estimate of the absolute sky brightness as well as may give rise to spectral features which may confuse with the true cosmological signatures in the foreground. A strategic system design with the aim of minimizing the systematics and characterization of the system non-ideal behavior can lead to the measurement accuracy with which the cosmological signatures could be detected along with the absolute measurement of the foreground. The aim of the work that constitute this thesis is precision measurement of the continuum radio emission at long wavelengths and detect the signature from the epoch of reionization in the background spectrum. A single element radio telescope system has been designed and built which is capable of useful measurement of spectral signatures of the EoR in the radio background. SARAS deployed in the Gauribidanur Observatory, about 80 km north of Bangalore in India. The design, calibration method and observation strategies developed are novel and unique, and relevant for any wideband measurements. The content of this thesis is outlined below. The Chapter 1 briefly introduces to the 21 cm cosmology. The neutral hydrogen as an cosmological probe is discussed first. The redshifted 21 cm signal and its possible use to probe the early Universe is discussed in detail. The chapter also gives a description of the redshifted 21 cm background and the EoR global signature as well as the 21 cm power spectrum. Finally an account of the recent and future experiments for detection of the global EoR signature and the EoR power spectrum are given. In the light of the science introduced in this chapter, the major aim and the work of the thesis is also summarised. In Chapter 2 the design philosophy of the SARAS spectrometer is illustrated. The basic elements of the system, the antenna, analog and the digital receiver have been described in detail. The complete configuration and the complex performance of the integrated system are detailed. For an ideal performance of such a wideband system the calibration strategies are considered and measurement equations are derived. Chapter3 addresses the most important issues of systematic effect for this wideband continuum measurement. The designed system performance deviates from its ideal due to non-idealities. The non-ideal behaviour of the real systems that are the limiting factors for a precision wideband measurement at low frequencies are thoroughly investigated. The effects of single and multiple reflections that occurs due to impedance mismatch internal to the system and results in spurious response in the measured data are considered. Within the limits of the known systematics, the system has been argued to qualify to be able to measure the EoR spectral signature in the background spectrum. Chapter 4 gives the details of the SARAS observation and description of the measurement that has been done by the SARAS spectrometer from the Gouribidanur Radio Observatory . The detailed understanding of the systematics led to the two strategic observation modes; EoR mode and RB mode, which are also discussed in this chapter. Next, the absolute calibration of the SARAS spectrometer is described following which the interference rejection algorithms, purpose developed for rejection of RFI from the SARAS data are outlined. The measured data is calibrated and the additional calibration product is derived. The data set is then modelled by modelling the sky noise and the systematic effects. In Chapter 5 the methodology of the SARAS data analysis is illustrated along with step by step analysis of the observation made in the RB mode. The model that is derived in chapter 4 is fitted to the measurements and the parameters are estimated by minimising the merit function Chi-square. The minimisation followed the downhill simplex algorithm which is outlined in this chapter. The data analysis strategy relied on the derivation of the initial values of the parameters from the measured data. The data has been fitted in hierarchy and initial guesses for subset of parameters are derived from each step of hierarchical modelling. This method of analysis is strategic and discussed in detail in this chapter. The statistical and systematic error of measurement are discussed next. Finally, the posterior probability distribution of the parameters are calculated by uniformly sampling the parameter space around the best fit values and calculating the Chi-square and the likelihood functions of the parameters. Mariginalizing the computed posterior probability distribution over the system parameters, the error on estimated sky parameter or the confidence region of the sky parameter is estimated. Chapter 6 presents the analysis identical to that presented in the Chapter 5 for the data acquired in the second observing mode, the EoR mode is presented. In this section the detection ability and the limitations of the SARAS observations, made from the Gouribidanur Radio observatory, for a useful detection of the EoR spectral signature is considered. Chapter 7 described a concept of system bandpass calibration using the time domain information that could be obtained from the voltage samples before computing the power spectrum. In the Chapter 3, the spurious periodic correlation, generated due to the internal reflections of the noise voltages is discussed in detail. If a short pulse is injected into the system via the antenna, due to internal reflections, the primary pulse in the output voltage samples would be followed by a series of delayed pulses each of which is generated by subsequent reflections internal to the system. Inspection of such pulses in the time domain could potentially provide with accurate bandpass calibration. A digital hardware is programmed and a nano second pulse generator-accumulator system is built. The performance of this system and table top demonstration of this bandpass calibration concept is presented in this chapter. This pulse injection system is used in a proposed calibration experiment in the Parkes radio telescope. The initial result of the experiment is presented in this chapter. In Chapter 8 the work carried out for this thesis is summarised. The end to end task of carrying out the background measurement by purpose building a single element radio telescope, observing with it and analysis of the data has led to a successful measurement of the background spectrum with an accuracy > 1%. The detailed understanding of the problems associated with the precision measurements and development of the measurement techniques that can overcome such problems has led to significant progress towards a successful detection of the EoR signatures. Some aspects and ideas which are understood to be essentials for such an experiment yet unexplored here due to limited time are listed in this section and the future prospcts of this work is also discussed.