In this work, I will be looking at the cross-linguistic restrictions on coda position, especially with regard to sonority and place. I propose that these restrictions can be best captured if we acknowledge two types of constraints; those which restrict the licensing ability of codas, as well as those which set out a relationship between a coda and a following onset. I show that in allowing for this distinction, the contrast between the restrictions on word-internal codas and word-final ones falls out straightforwardly. This study is carried out in the framework of Optimality Theory, but the basic claims are expected to hold in other frameworks, whether rule-based or constraint-based.

Languages differ in their sound patterns, but these differences are, to a large extent, systematic. One goal of Universal Grammar (Chomsky 1957, 1965) is to account for the systematic patterns which are attested across languages. Toward this end, Universal Grammar is considered to contain a set of phonological primitives such as features, and some restrictions on their combination. However, in rule-based phonology, it is assumed that rules are part of the grammar of an individual language. By their very nature, rules describe operations. As such, they are not well-suited to express restrictions on the ways in which segments may combine when no overt operation is involved. To account for such restrictions, Chomsky & Halle (Sound Pattern of English (SPE): 1968) supplemented rules with Morpheme Structure Constraints (MSCs) which define the possible morpheme shapes that a particular language allows (see also Halle 1959). Thus, in SPE, both MSCs and rules played a role in accounting for the phonological patterns observed in languages.

We study the two-user multiple-input single-output (MISO) Gaussian interference channel where the transmitters have perfect channel state information and employ single-stream beamforming. The receivers are capable of performing successive interference cancellation, so when the interfering signal is strong enough, it can be decoded, treating the desired signal as noise, and subtracted from the received signal, before the desired signal is decoded. We propose efficient methods to compute the Pareto-optimal rate points and corresponding beamforming vector pairs, by maximizing the rate of one link given the rate of the other link. We do so by splitting the original problem into four subproblems corresponding to the combinations of the receivers' decoding strategies - either decode the interference or treat it as additive noise. We utilize recently proposed parameterizations of the optimal beamforming vectors to equivalently reformulate each subproblem as a quasi-concave problem, which we solve very efficiently either analytically or via scalar numerical optimization. The computational complexity of the proposed methods is several orders-of-magnitude less than the complexity of the state-of-the-art methods. We use the proposed methods to illustrate the effect of the strength and spatial correlation of the channels on the shape of the rate region.

Honors Project--Smith College, Northampton, Mass., 2009. / Includes bibliographical references (p. 72-74).

Originally presented as the author's Thesis (Ph. D.)--Brandeis University, 1994. / Includes bibliographical references (p. 161-172).

Originally presented as the author's thesis (Ph. D.)--Brandeis University, 1994. / Includes bibliographical references (p. 161-172).

Neste trabalho, buscamos observar como os vocoides altos se comportam, no que diz respeito à silabificação e à atribuição do acento, em português brasileiro (PB). O termo “vocoide” é aqui empregado para designar um segmento subjacente que pode se realizar como vogal ou como glide. Nosso objetivo, então, é o de verificar em que contextos a realização se dará com uma ou com outro. Para a análise que tem como pressuposto teórico a Teoria de Otimidade (Prince e Smolensky (1993), McCarthy e Prince (1993b)), tomamos como ponto de partida as hipóteses de que o glide pós-vocálico localiza-se na coda silábica, enquanto o glide pré-vocálico forma núcleo complexo com a vogal seguinte. O principal argumento para a primeira hipótese é o fato de que o glide não coocorre com um (outro) segmento em coda. Fundamentando a segunda hipótese, há o fato de que o glide pré-vocálico possui um papel a desempenhar na atribuição do acento, uma vez que não existem palavras em PB nas quais o acento “pula” uma sílaba constituída por ditongo crescente na penúltima posição (*ídioma). Em uma análise não derivacional, não é possível interpretar tal ausência como consequência do fato de que, em uma etapa anterior de silabificação, o vocoide alto ocupa a posição de núcleo, o que significa que o acento não pode incidir em uma sílaba à sua esquerda, pois estaria sendo violada a restrição da “janela de três sílabas”. Propomos, então, um ranqueamento que dá conta das diferentes estruturas silábicas de vogal mais glide pós-vocálico e de glide pré-vocálico mais vogal. No que diz respeito à atribuição do acento, foi possível observar que, de maneira geral, o vocoide alto só receberá acento se for acentuado no input. Se o acento não estiver presente no input ou se outro segmento receber acento no input, haverá uma preferência pela realização do vocoide alto como glide, uma vez que tal realização permite a satisfação simultânea das restrições relativas à silabificação e à atribuição do acento. / In this work, we aim to analyze the way high vocoids behave in relation to syllabification and stress assignment in Brazilian Portuguese (BP). The term “vocoid” is used here to express a subjacent segment that can surface as vowel or glide. Our objective is to verify in which contexts will surface one or the other. Based on Optimality Theory (Prince and Smolensky (1993), McCarthy and Prince (1993b)), we take as starting point the hypothesis that the postvocalic glide is placed in the syllabic coda whereas the prevocalic glide forms a complex nucleus with the following vowel. In relation to the first hypothesis, the main argument refers to the fact that the glide does not co-occur with another coda segment. Concerning the second hypothesis, our argument refers to the fact that the prevocalic glide has to play a role in the stress assignment, since there are not words in BP in which the stress “jumps” a syllable constituted by rising diphthong in the penultimate position (*ídioma). In a non-derivational analysis, it is not possible to interpret this absence as a consequence of an anterior stage of syllabification, where the high vocoid was placed in the nucleus position, and stress placement on a syllable on its left would mean a “three syllable window” violation. Therefore, we propose a ranking that deals with the different syllabic structures of vowel plus postvocalic glide and prevocalic glide plus vowel. In relation to stress assignment, in a general way, we observed that the high vocoid will be stressed only if it is stressed in the input. If the stress is not present in the input or if other segment is stressed in the input, there will be a preference for the realization of a high vocoid as glide, since this realization allows a simultaneous satisfaction of the constraints relating to syllabification and to stress assignment.

Airships provide an eco-friendly and cost-effective means to suit sustained airborne operations. Smaller autonomous airships are highly susceptible to adverse atmospheric conditions owing to their under-actuated, underpowered and bulky size relative to other types of unmanned aerial vehicles (UAVs). To mitigate these limitations, careful considerations of the size and shape must be made at the design stage. This research presents a methodology for obtaining an optimized shape of a semi-rigid airship. Rapid descent of the LTA ship is achieved by means of a moving gondola attached to a rigid keel mounted under the helium envelope from the bow to the mid-section of the hull. The study entails the application of a robust hybrid genetic algorithm (HGA) for the multi-disciplinary design and optimization of an airship capable of rapid descent, with lower drag and optimum surface area. A comprehensive sensitivity analysis was also performed on the basis of algorithmic parameters and atmospheric conditions. With the help of HGA, a semi-rigid airship capable of carrying a payload of 0.25 kg to 1.0 kg and capable of pitching at right angles is conceptually designed. The algorithm is also tested on commercially available vehicles to validate the results. In multi-objective optimization problems (MOOPs), the significance of different objectives is dependent on the user.

Neste trabalho, buscamos observar como os vocoides altos se comportam, no que diz respeito à silabificação e à atribuição do acento, em português brasileiro (PB). O termo “vocoide” é aqui empregado para designar um segmento subjacente que pode se realizar como vogal ou como glide. Nosso objetivo, então, é o de verificar em que contextos a realização se dará com uma ou com outro. Para a análise que tem como pressuposto teórico a Teoria de Otimidade (Prince e Smolensky (1993), McCarthy e Prince (1993b)), tomamos como ponto de partida as hipóteses de que o glide pós-vocálico localiza-se na coda silábica, enquanto o glide pré-vocálico forma núcleo complexo com a vogal seguinte. O principal argumento para a primeira hipótese é o fato de que o glide não coocorre com um (outro) segmento em coda. Fundamentando a segunda hipótese, há o fato de que o glide pré-vocálico possui um papel a desempenhar na atribuição do acento, uma vez que não existem palavras em PB nas quais o acento “pula” uma sílaba constituída por ditongo crescente na penúltima posição (*ídioma). Em uma análise não derivacional, não é possível interpretar tal ausência como consequência do fato de que, em uma etapa anterior de silabificação, o vocoide alto ocupa a posição de núcleo, o que significa que o acento não pode incidir em uma sílaba à sua esquerda, pois estaria sendo violada a restrição da “janela de três sílabas”. Propomos, então, um ranqueamento que dá conta das diferentes estruturas silábicas de vogal mais glide pós-vocálico e de glide pré-vocálico mais vogal. No que diz respeito à atribuição do acento, foi possível observar que, de maneira geral, o vocoide alto só receberá acento se for acentuado no input. Se o acento não estiver presente no input ou se outro segmento receber acento no input, haverá uma preferência pela realização do vocoide alto como glide, uma vez que tal realização permite a satisfação simultânea das restrições relativas à silabificação e à atribuição do acento. / In this work, we aim to analyze the way high vocoids behave in relation to syllabification and stress assignment in Brazilian Portuguese (BP). The term “vocoid” is used here to express a subjacent segment that can surface as vowel or glide. Our objective is to verify in which contexts will surface one or the other. Based on Optimality Theory (Prince and Smolensky (1993), McCarthy and Prince (1993b)), we take as starting point the hypothesis that the postvocalic glide is placed in the syllabic coda whereas the prevocalic glide forms a complex nucleus with the following vowel. In relation to the first hypothesis, the main argument refers to the fact that the glide does not co-occur with another coda segment. Concerning the second hypothesis, our argument refers to the fact that the prevocalic glide has to play a role in the stress assignment, since there are not words in BP in which the stress “jumps” a syllable constituted by rising diphthong in the penultimate position (*ídioma). In a non-derivational analysis, it is not possible to interpret this absence as a consequence of an anterior stage of syllabification, where the high vocoid was placed in the nucleus position, and stress placement on a syllable on its left would mean a “three syllable window” violation. Therefore, we propose a ranking that deals with the different syllabic structures of vowel plus postvocalic glide and prevocalic glide plus vowel. In relation to stress assignment, in a general way, we observed that the high vocoid will be stressed only if it is stressed in the input. If the stress is not present in the input or if other segment is stressed in the input, there will be a preference for the realization of a high vocoid as glide, since this realization allows a simultaneous satisfaction of the constraints relating to syllabification and to stress assignment.

This study provides an Optimality-Theoretic analysis of the syllabification of word-initial biconsonantal clusters in the productions of Faifi Arabic and Asiri Arabic speakers. This study aimed at investigating the role of sonority in the syllabification of onset clusters. Two groups, each made up of 15 participants, were employed in this study to produce English nonwords, which had onsets composed of biconsonantal clusters with different sonority levels. The results of the study showed that the two groups had two different ways of treating the clusters. The Faifi group epenthesized a vowel before the onset clusters, forcing the second consonant in the cluster to become the onset of the following syllable. The Asiri group epenthesized a vowel between the consonants of onset clusters when the sonority slope equaled 2. When the sonority slope equaled 3, the cluster was produced intact. All of these differences were shown to be the result of different rankings of several markedness and faithfulness constraints.