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[pt] Esta dissertação aborda o estudo de códigos fontanais (códigos LT e códigos Raptor) que são uma classe de códigos criados para a transmissão de dados de maneira confiável e eficiente através de canais os quais podem ser modelados como canais com apagamento. Os códigos LT e códigos Raptor são denominados códigos fontanais, devido a que eles são uma boa aproximação para o conceito de fontanas digitais. Além disso, eles são classificados como códigos de taxa versátil, no sentido que o número de símbolos codificados que podem ser gerados a partir dos dados de entrada é potencialmente ilimitado. Códigos LT são capazes de recuperar, com probabilidade maior do que (1 − delta), um conjunto de k símbolos de entrada a partir de quaisquer k + O((raiz quadrada de k)(ln(2))(k/delta)) símbolos codificados recebidos, com uma média de O(k ln(k/delta)) operações XOR. Os códigos Raptor são uma extensão de códigos LT, na qual o processo de codificação é composto de duas etapas: um código de bloco de comprimento fixo (denominado pré- código) e um código LT com uma distribuição de graus apropriada. Investigou-se o desempenho dos códigos LT usando duas novas distribuições de graus (Sóliton Robusta Melhorada e Sóliton Robusta Truncada) e foi proposto um modelo de códigos LT Bidimensionais, na qual os símbolos de entrada são agrupados em forma de matriz. Neste esquema os blocos correspondentes às linhas da matriz são codificados usando um código LT e, em seguida, a matriz resultante tem suas colunas também codificadas usando um código LT. Ainda que a complexidade do esquema tenha sido dobrada o desempenho alcançado pelos códigos LT Bidimensionais superou o desempenho dos códigos LT convencionais para situações em que a qualidade do canal BEC é elevada. / [en] Fountain Codes (LT Codes and Raptor Codes) are a class of codes proposed to efficient and reliably transmit data through Erasure Channels. LT Codes and Raptor Codes are a good approximation to the concept of digital fountain and as such are named as fountain codes. They are said to be rateless codes in the sense that the number of symbols produced by the encoder could grow, potentially, to infinite. With probability of success larger than (1−delta), a decoder of an LT code based scheme can recover the k transmitted symbols from any received block of k + O((square root k)(ln(2))(k/delta)) correct symbols with an average of O(k ln(k/delta)) XOR operations. Raptor codes are an extension of the LT codes idea, with a tandem scheme where a fixed length block code (namely a pre- code) is followed by an LT code that uses a properly chosen degree distribution. In this dissertation the performance of LT codes with two recently proposed degree distributions, the Improved Robust Soliton and the Truncated Soliton Robust Distribution were investigated. A new scheme called Bidimensional LT Codes, has been proposed. In this scheme the input symbols are structured in a matrix form and afterwards the blocks corresponding to the lines of the matrix are encoded with an LT code. The columns of the new matrix so obtained are next encoded with a similar LT code. The complexity of the new scheme is doubled and yet its performance only just surpasses that of the conventional LT scheme for high quality BEC.

Decreasing enrollments, lower rates of student retention and changes in the learning styles of today's students are all issues that the Computer Science (CS) academic community is currently facing. As a result, CS educators are being challenged to find the right blend of technology and pedagogy for their curriculum in order to help students persist through the major and produce strong graduates. Visual technologies are being explored as a way to present difficult programming concepts in a manner that is easier to visualize and simpler to use. Visual technologies can make learning programming easier by minimizing the syntax of the programming language being used and providing visual feedback to the students to aid in conceptualization of the programming constructs. The goal was to improve student retention and performance by incorporating visual technologies in the introductory programming course, CS1, at East Tennessee State University (ETSU). The ADDIE approach to instructional design was used to develop and implement a curriculum that incorporated visual technologies in CS1 at ETSU. Subsequently, quasi-experimental research methods, using the Post-Test Only Nonequivalent Groups Design approach, were used to perform assessment on the effects of the revised curriculum on student performance in the course and retention in the major as compared to student performance and retention as measured prior to the course redesign. The results of the study indicate a positive impact on student performance in CS1 and student retention in the major as a result of the use of two types of visual technologies in CS1 at ETSU. Visual technologies supporting algorithm development, such as RAPTOR, had a positive impact on student performance in the area of problem solving and algorithm development as well as the use of decision and repetition constructs in programming. Visual technologies supporting program development, such as Alice, had a positive impact on student performance in the area of object-oriented programming concepts such as objects and classes. The combination of these two types of visual technologies showed evidence of improvement among student performance as a whole in the course and slight improvement in student persistence in the major.

abstract: In sub transmission systems, many more raptor deaths have been recorded near metal poles rather than wood poles. The metal pole, which is reliable in structure but also grounded, may increase the risk of electrocution when raptors perch on the insulator. This thesis focuses on evaluating the effectiveness of the raptor guard to prevent both debilitating and lethal electrocutions to local wildlife in 69 kV sub transmission systems. First, the two-dimensional (2D) finite difference methods (FDM) were proposed to solve the Poisson and Laplace equations, which describe the electric field. Second, the verification of the FDM algorithm was made based on a parallel-plate capacitor model. Then, the potential and the electric field were simulated by the raptor-insulator model to evaluate the possibility of flashover and leakage current under various conceivable scenarios. Third, several dielectric performance experiments were implemented to gain insight into the physical property of the raptor guard developed by the Salt River Project (SRP) as an example. The proposed initial-tracking-voltage and time-to-track experiments tested the ability of the guard, which is designed to prevent the tracking phenomenon under a contaminated situation such as rain, fog, and snow. A data acquisition also collected the leakage current data for the comparison of maximum raptor tolerance. Furthermore, the puncture voltage of this guard material was performed by the dielectric breakdown voltage experiment in an oil-covered container. With the combination of the model simulation and the experiments in this research, the raptor guard was proven to be practical and beneficial in sub transmission system. / Dissertation/Thesis / Masters Thesis Electrical Engineering 2016

Gray hawks became established in the San Pedro River (SPR) valley in the mid-1900s following landscape changes that created habitat for them. The population of gray hawks along the SPR is at the northern edge of the species’ range, and its growth has been documented periodically since the 1970s. A study in the 1990s quantified gray hawk diet and habitat use in this area, and found that gray hawks hunt primarily in mesquite, eat mostly lizards, and that their productivity is positively correlated with the percentage of mesquite in their territories. The gray hawk population along the SPR has nearly doubled since the initial study was conducted, and pairs now nest in areas that contain little or no mesquite. Our main objectives were to determine whether: a) diet and habitat requirements have changed for gray hawks along the SPR since the population has as expanded, and b) productivity has declined as the population has expanded into habitats of potentially lower quality. We used nest cameras to document prey deliveries, and ESRI ArcGIS to quantify vegetation types within estimated home ranges of gray hawks. We compared productivity of gray hawk pairs in the 1990s and the 2010s, as well as the current productivity of pairs in territories that had been occupied by gray hawks in the 1990s (original territories) and those that only became occupied after the original study was completed (new territories). We found that that gray hawks used a wider variety of vegetation types, such as nest trees surrounded by grasslands, and consumed a wider variety of prey than they did in the 1990s, and that productivity remained constant over time. Like many populations at the edge of their range, the gray hawks that initially settled in the San Pedro River valley likely had access to only a portion of the resources that are common at the center of the species’ range, and therefore appeared to have a narrower set of diet and habitat requirements than the species as a whole. Areas that are currently being used by gray hawks for nesting (e.g., nest trees surrounded by grasslands) were likely unsuitable in the 1990’s because they were being used for agriculture and grazing. The two chapters of this thesis will be submitted to journals for publication and therefore contain overlapping information.

One of the most important emerging aspects of Third Generation Partnership Project (3GPP) is the Multimedia Broadcast/Multicast Service (MBMS) aiming to deliver multimedia contents to mobile users more efficiently in point-to-multipoint way. 3GPP also recommends an Application Layer Forward Error Correction (AL-FEC) scheme, especially for MBMS, in order to provide reliable transmission over mobile networks. Due to many emerging FEC schemes, the existing 3GPP standardized systematic fountain Raptor code FEC scheme is considered to be outdated. One of the newly emerged codes, namely RaptorQ, has enhanced an AL-FEC scheme by providing higher protection against packet loss and superior flexibility to meet the growing demand in mobile multicast services. In this work, we provide an extensive device based performance evaluation of RaptorQ FEC codes, specified as RFC 6330 in Internet Engineering Task Force (IETF), and notice that the performance always outperforms that of the existing Raptor (RFC 5053) codes in terms of decoding speed, latency and memory. We also include the device based performance comparison of RaptorQ FEC codes in a comparison with other FEC schemes like Supercharged codes and Reed Solomon + Low Density Parity Check codes (RS+ LDPC). Finally, we conduct simulation carried out in the mobile devices for several network parameters like latency, decoding speed and memory in combination with FEC encoding and decoding parameters and investigate that RaptorQ is the best code that suits multicast services. / +46723185198, +4917626686238,+4915166808450

<p>Free-space optical (FSO) communication has witnessed rapid development recently in response to ever-increasing demands for greater bandwidth. FSO links provide fiberspeed with the flexibility of wireless. Commercially available systems offer transmission speeds up to 2.5 Gbps, 5 Gbps and 10 Gbps, and demonstration systems report data rates as high as 160 Gbps. Its advantages also include license free operation, high immunity to interference, and ease of deployment. However, FSO systems are sensitive to adverse weather conditions such as fog, rain and snow.</p> <p>In order to improve the availability of FSO channels degraded by atmospheric turbulence and varying weather conditions, the effects of channel gain variations must be compensated. In this thesis, two rate-adaptive techniques, punctured low-density parity-check (LDPC) codes and Raptor codes, are studied using experimental data measured over a1.87 km terrestrial FSO link.</p> <p>Rate-adaptive performances with punctured LDPC codes and Raptor codes are evaluated in terms of outage probability and throughput. In comparison to uncoded system, rate-adaptive systems with both techniques demonstrate significant improvement of throughput and mitigation of outage probability especially in rainy weather. Due to its flexible rate-adaptation and simple hardware implementation, Raptor coded systems are judged more applicable to be implemented in field-programmable gate array (FPGA) based hardware. A dedicated decoding structure is proposed and tested, showing remarkable improvement in resource efficiency as compared to traditional Gauss-Jordan (GJ) decoding structures.</p> / Master of Applied Science (MASc)

American Kestrels (Falco sparverius) are a small falcon with an expansive range across North America. However, kestrels have been reported to be declining since the 1960s, with the primary cause of decline unknown. With previous research focusing on the summer breeding season, researchers have called for additional investigation in understudied wintering and migratory periods. In Chapter 2, I quantified annual survivorship against five covariates of migrant kestrels wintering in north Texas to contribute to population level analyses across the kestrel's expansive range. Notably, I found that juvenile survival is similar to that of adults once on the wintering grounds, and that aspects of urbanization may increase survival in wintering kestrels. In Chapter 3, I outlined kestrel movement ecology by quantifying migration phenology, performance, and patterns. Additionally, I identified breeding and stopover sites and analyzed both winter and summer home ranges. In this analysis, I contributed three additional migration tracks to the five currently published. Further, I reported the first loop and indirect migration patterns to our knowledge. Overall, this research highlights understudied aspects of the kestrel full annual cycle in the winter and migratory periods, providing insight into possible causes for kestrel declines.

Considering the high reproductive investment of the social male and the cost to the female of losing this benefit by soliciting copulations outside the social pair bond, it is expected that most raptor populations would exhibit low to no occurrence of extra-pair paternity (EPP). This holds true for the majority of raptor species studied to date with only one exception of an urban Cooper's hawk (Accipiter cooperii) study which reported an unexpectedly high extra-pair young frequency of 19.29%. In our study we examined the frequency of EPP within a red-shouldered hawk (Buteo lineatus) population residing in the suburban/urban matrix of southwest Ohio. During the breeding seasons of 2018 and 2019, 181 breeding age and nestling individuals were color-banded and sampled for genetic analysis using nine microsatellite loci. After genotyping a total of 40 broods (with at least two nestlings per brood) and both presumptive parents of each brood, no clear evidence of EPP was detected. However, at one nest site, the entire brood of four chicks was not sired by the adult male observed during the courtship period, nor another adult male observed tending the chicks later in the season. We suspect that this particular nest represented two instances of rapid mate replacement rather than extra-pair fertilization by a third unsampled male, because none of the chicks were sired by either of the two adult males observed at the nest. We also reviewed potential factors contributing to our finding of overall genetic monogamy in our study population in comparison to other raptor taxa EPP studies. Our results suggested that factors other than habitat composition alone play an important role in determining the type of breeding strategy exhibited by different raptor populations.