Thesis (Ph. D.)--University of Wisconsin--Madison, 1988. / Typescript. Vita. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references (leaves 192-198).

Stanley B. Gershwin, David M. Orlicki, Yacov Zahavi. / Cover title. "October 1981." Contract no. DTRS-57-80-C-00012. Performing organizations: Mobility Systems, Inc. and Massachusetts Institute of Technology, Laboratory for Information and Decision Systems. Under contract to the Transportation Systems Center. / Includes bibliographical references.

Ο γραμμικός προγραμματισμός είναι μια μεθοδολογία της Επιχειρησιακής Έρευνας η οποία ασχολείται με το πρόβλημα της κατανομής των περιορισμένων πόρων ενός συστήματος σε ανταγωνιζόμενες μεταξύ τους δραστηριότητες με τον καλύτερο δυνατό τρόπο. Από μαθηματικής σκοπιάς το πρόβλημα αφορά τη μεγιστοποίηση ή ελαχιστοποίηση μιας γραμμικής συνάρτησης σύμφωνα με κάποιους γραμμικούς περιορισμούς. Τόσο η μαθηματική διατύπωση του προβλήματος, όσο και μια συστηματική διαδικασία επίλυσής του, η μέθοδος Simplex, οφείλεται στον G.B. Duntzig στα 1947. Την ίδια εποχή ο J. Von Neuman διατύπωνε το αργότερα γνωστό ως δυϊκό πρόβλημα γραμμικού προγραμματισμού. Το πρώτο κεφάλαιο της παρούσης εργασίας ξεκινά με τη γενική μαθηματική θεώρηση των δύο προβλημάτων και συνεχίζει με τα βασικά θεωρήματα τα οποία αφορούν τη διαδικασία λύσης, τις ιδιότητές τους καθώς επίσης και τις σχέσεις που τα συνδέουν. Στο δεύτερο κεφάλαιο παρουσιάζονται διάφοροι τύποι ανάλυσης ευαισθησίας του γραμμικού μοντέλου, της μελέτης δηλαδή των αλλαγών που επιφέρουν στην άριστη λύση, αλλαγές σε διάφορα μεγέθη -παράμετροι- του προβλήματος. Στο ίδιο κεφάλαιο παρουσιάζεται η ανάλυση ευαισθησίας μιας ειδικής κλάσης προβλημάτων γραμμικού προγραμματισμού, του προβλήματος καταμερισμού εργασίας (εκχώρησης). Τέλος γίνεται μια σύντομη αναφορά στον υπολογισμό των δυϊκών τιμών στην περίπτωση των εκφυλισμένων λύσεων. / Linear programming is a method of Operations Research which deals with the problem of distribution of limited resources of a system to rivaling activities -with each other - in the best possible way. From mathematics point of view the problem concerns the maximization or minimization of a linear function according to certain linear restrictions. Not only the mathematic formulation of the problem, but also a systematic procedure of solution (gradualism), the Simplex method, are due to G. B. Duntzig (1947). At the same time J. Von Neuman formulated the later known as dual problem of linear programming. The first chapter of this paper starts with the general mathematical regard of these two problems and steps to the essential theorems used for the solution procedure, their attributes as well as the relations that bind them. In the second chapter various types of linear model’s sensitivity analysis are presented, the study of changes that lead to the most efficient solution, changes in various elements - parameters of the problem. At the same chapter the sensitivity analysis of special group of linear programming problems is presented, the assignment problem. Finally a brief note is made at the calculation of dual values in case of degenerated solutions.

Power system stabilizers (PSSs) provide the most economical way to improve damping of electro-mechanical oscillations in electrical power systems. Synchrophasor technology enables the use of remotely measured signals in the PSS allowing for greater flexibility in the design of the PSS. Issues related to the transmission of remote signals should be addressed before implementing such systems in practice. This study investigates two of the data transmission issues: (i) delays, and (ii) data dropout; using a synchrophasor-based PSS designed for a two-area four-generator power system model. A time delayed system is modeled using discrete transformation and the effect of the constant delay on the control action of improving damping of an electro-mechanical oscillation is determined analytically. The effect of random delays and data dropout is investigated using non-linear simulations considering viable remedies to overcome these effects. This research also identifies effective means of using synchrophasor signals for improving the performance of PSSs. Primarily, this research introduces a novel control design algorithm based on eigenstructure assignment that could utilize remotely measured signals to design a robust PSS considering different operating conditions at the design stage. Remote signals could be used as additional inputs to the controller, which introduces extra degrees of freedom. In eigenstructure assignment, these additional degrees of freedom are used to assign eigenvalues and eigenvectors to have adequate damping performance of the system over different operating conditions. The algorithm is formulated as a derivative-free non-linear optimization problem and solved using a single step of optimization by eliminating the use of eigenvalue sensitivities. The proposed algorithm is tested for the 68 bus model of the interconnected New England test system and New York power system. Three different control configurations that use local and remote signals are considered in the design. The algorithm is solved using non-linear simplex optimization considering different initial points for seeking a global solution. Delays in the remote signals are also incorporated into the design. The designed controllers are verified in a non-linear simulation platform. Finally, the reliability of synchrophasor-based PSS is discussed in brief. / February 2016

Thesis (MComm)--Stellenbosch University, 2012. / ENGLISH ABSTRACT: In a ground-based air defense (GBAD) military environment, defended assets on the ground require protection from enemy aircraft entering the defended airspace. These aircraft are detected by means of a network of sensors and protection is afforded by means of a pre-deployment of various ground-based weapon systems. A fire control officer is responsible for deciding upon an assignment of weapon systems to those aircraft classified as threats. The problem is therefore to find the best set of weapon systems to assign to the threats, based on some pre-specified criterion or set of criteria. This problem is known as the weapon assignment problem. The conditions under which the fire control officer has to operate are typically extremely stressful. A lack of time is a severely constraining factor, and the fire control officer has to propose an assignment of weapon systems to threats based on his limited knowledge and intuition, with little time for analysis and no room for error. To aid the fire control officer in this difficult decision, a computerised threat evaluation and weapon assignment (TEWA) decision support system is typically employed. In such a decision support system a threat evaluation subsystem is responsible for classifying aircraft in the defended airspace as threats and prioritising them with respect to elimination, whereas a weapon assignment subsystem is responsible for proposing weapon assignments to engage these threats. The aim in this thesis is to model the weapon assignment problem as a multiobjective decision problem. A list of relevant objectives is extracted by means of feedback received from a weapon assignment questionnaire which was completed by a number of military experts. By using two of these objectives, namely the cost of assigning weapon systems and the accumulated single shot hit probability, for illustrative purposes, a bi-objective weapon assignment model is derived and solved by means of three multiobjective optimisation methodologies from the literature in the context of a simulated, but realistic, GBAD scenario. The analytic hierarchy process (AHP) is implemented by means of assessments carried out in conjunction with a military expert. The assignment of weapon systems to threats is achieved by means of a greedy assignment heuristic and an AHP assignment model. Both these methods provide plausible results in the form of high quality assignments achieving an acceptable tradeoff between the two decision objectives. However, a disadvantage of the AHP approach is that it is inflexible in the sense that a large portion of its pre-assessments have to be reiterated if the set of weapon systems and/or threats is adapted or updated. A bi-objective additive utility function solution approach to the weapon assignment problem is also developed as a result of various assessments having been carried out in conjunction with a military expert. The assignment of weapon systems to threats is again achieved by means of a greedy assignment heuristic and a utility assignment model. Both these methods again provide high quality assignments of weapon systems to threats, achieving an acceptable trade-off between the two decision objectives. However, a disadvantage of the utility function approach is that if additional weapon systems are added to the current set of weapon systems, which achieve objective function values outside the current ranges of the values employed, new utility functions have to be determined for the relevant objective function. Moreover, both the AHP and utility function approaches are also constrained by generating only one solution at a time. A final solution approach considered is the implementation of a multiobjective evolutionary metaheuristic, known as the Nondominated Sorting Genetic Algorithm II (NSGA II). This approach provides very promising results with respect to high quality assignments of weapon systems to threats. It is also flexible in the sense that additional weapon systems and threats may be added to the current sets without the need of considerable additional computations or significant model changes. A further advantage of this approach is that it is able to provide an entire front of approximately pareto optimal solutions to the fire control officer. / AFRIKAANSE OPSOMMING: In ’n militêre grond-gebaseerde lugafweeromgewing vereis bates op die grond beskerming teen vyandelike vliegtuie wat die beskermde lugruim binnedring. Hierdie vliegtuie word deur middel van ’n netwerk van sensors waargeneem en deur middel van ’n ontplooing van ’n verskeidenheid grond-gebaseerde wapenstelsels afgeweer. ’n Afvuur-beheer operateur is verantwoordelik vir die besluit om wapenstelsels aan vliegtuie wat as bedreigings geklassifiseer is, toe te wys. Die onderliggende probleem is dus om die beste stel wapens, volgens ’n voorafbepaalde kriterium of ’n stel kriteria, aan die bedreigings toe te wys. Hierdie probleem staan as die wapentoewysingsprobleem bekend. Die toestande waaronder die afvuur-beheer operateur besluite ten opsigte van wapentoewysings maak, is besonder stresvol. ’n Gebrek aan tyd is ’n uiters beperkende faktor, en die afvuurbeheer operateur moet gevolglik binne ’n tydspan wat weinige analise en geen ruimte vir foute toelaat, wapentoewysings volgens sy beperkte kennis en intuïsie maak. ’n Gerekenariseerde bedreigingsafskatting-en-wapentoekenningstelsel kan gebruik word om die operateur met besluitsteun te bedien. In sò ’n besluitsteunstelsel is ’n bedreigingsafskattingdeelstelsel verantwoordelik om vliegtuie wat die beskermde lugruim binnedring as bedreigings of andersins te klassifiseer en ten opsigte van eliminasie te prioritiseer, terwyl ’n wapentoewyingsdeelstelsel verantwoordelik is om wapentoewysings aan die bedreigings voor te stel. Die hoofdoel in hierdie tesis is om die wapentoewysingsprobleem as ’n multikriteria-besluitnemingsprobleem te modelleer. ’n Lys van relevante doelwitte is met behulp van ’n wapentoewysingsvraelys verkry wat aan militêre kenners vir voltooing uitgestuur is. Twee van hierdie doelwitte, naamlik toewysingskoste en geakkumuleerde enkelskoot-trefwaarskynlikheid, is vir illustratiewe doeleindes gebruik om ’n twee-doelwit wapentoewysingsprobleem te formuleer wat met behulp van drie multikriteria-besluitnemingsmetodologië uit die literatuur in die konteks van ’n realistiese, gesimuleerde grond-gebaseerde lugafweerscenario opgelos word. Die analitiese hiërargiese proses (AHP) is met behulp van assesserings in samewerking met ’n militêre kenner geïmplementeer. Die toewysing van wapenstelsels is met behulp van ’n gulsige toewysingsheuristiek asook aan die hand van ’n AHP-toewysingsmodel bepaal. Beide hierdie metodes is in staat om resultate van hoë gehalte te behaal wat ’n aanvaarbare afruiling tussen die twee doelwitte verteenwoordig. ’n Nadeel van die AHP is egter dat dit onbuigsaam is in die sin dat ’n groot hoeveelheid vooraf-assesserings herhaal moet word indien meer wapenstelsels en/of bedreigings by die huidige sisteem gevoeg word. ’n Twee-doelwit additiewe nutsfunksiebenadering tot die wapentoewysingsprobleem is ook met behulp van velerlei assesserings in samewerking met ’n militêre kenner ontwikkel. Die toewysings is weereens met behulp van ’n gulsige wapentoewysingsheuristiek asook ’n nutstoewysingsmodel bepaal. Beide hierdie metodes is ook in staat om resultate van hoë gehalte te behaal wat ’n aanvaarbare afruiling tussen die twee doelwitte verteenwoordig. ’n Nadeel van die nutsfunksiebenadering is egter dat indien addisionele wapenstelsels by die huidige stel wapenstelsels gevoeg word, en indien die waardes van hierdie addisionele wapenstelsels buite die grense van die doelfunksiewaardes van die huidige wapenstelsels val, daar ’n nuwe nutsfunksie vir die relevante doelwit van voor af bereken moet word. Beide die AHP- en die nutsfunksiebenaderings is verder tot die lewering van slegs een oplossing op ’n slag beperk. Laastens is ’n multikriteria evolusionêre metaheuristiek (die NSGA II) geïmplementeer wat ook goeie resultate in terme van hoë-gehalte toewysings van wapenstelsels aan bedreigings lewer. Die voordeel van hierdie benadering is dat dit buigsaam is in die sin dat die getal wapenstelsels en bedreigings in die huidige sisteem aangepas kan word sonder om noemenswaardig meer berekeninge of groot modelveranderinge teweeg te bring. ’n Verdere voordeel is dat die metaheuristiese benadering daartoe in staat is om ’n front van benaderde pareto-optimale oplossings gelyktydig te lewer.

Cette thèse propose un outil d’aide à la décision pour la gestion de processus de maintenance basée surune affectation optimale des ressources humaines afin d’améliorer la performance de la maintenance.En effet, une bonne performance de la fonction maintenance est indispensable pour maintenir laproductivité des installations industrielles, et donc de la compétitivité des entreprises manufacturières.L’approche que nous développons dans ce manuscrit procure un cadre de référence des leviersd’actions envisageables pour mesurer, évaluer, améliorer et optimiser la performance de lamaintenance. Nous prenons en considération un problème d’affectation des ressources humaines, quiprend en compte non seulement leurs disponibilités et compétences, mais aussi la gestion des urgencesd’intervention sur terrain.La méthode que nous proposons est basée sur un modèle de simulation à événements discrets,reproduisant au mieux un service de maintenance. Ceci nous a permis d’évaluer la situation via desindicateurs de performance présélectionnés. Pour optimiser le système, nous proposons un couplagedu modèle de simulation avec un module d’optimisation indépendant qui se réfère à une métaheuristiquebasée sur une approche Pareto. Notre proposition a été testée dans une entrepriseindustrielle réelle.L’approche que nous proposons donne un ensemble de solutions d’affectation des ressourceshumaines, aidant le décideur à mieux gérer l’indisponibilité de ses outils. Nous obtenons de bonsrésultats en un temps raisonnable. / In this thesis, a decision-making tool for maintenance management process based on assignment ofhuman resources is proposed in order to improve maintenance performance. An optimal maintenanceperformance is indispensable to guarantee the productivity and competitiveness of manufacturingcompanies.The proposed approach provides a framework of different possible levers to measure, evaluate,improve and optimize the maintenance performance. The assignment of human resources problem isconsidered. It takes into account different constraints like human resources availability, competences,urgency degree management of interventions requests etc.The proposed method is based on a discrete event simulation model, providing a better presentation ofthe maintenance service and better comprehensive thanks to the performance indicators. To improveuntil optimize the model, a simulation-based Pareto optimization method is introduced. Optimizationmodule was coded on independent programs in order to provide an opportunity of control thesimulation based optimization process.The proposed simulation based optimization method find good solutions in a reasonable amount oftime. Applying this technique on an industrial case-study, we show that it is more effective indetecting real faults than existing alternatives. The approach can be extended to cover other domainsand other types of simulation models.

A busca de soluções para a mobilidade urbana que minimizem a agressão do setor de tráfego e transportes ao meio ambiente está cada vez maior. Os veículos elétricos se posicionam como uma alternativa interessante, pois reduzem a emissão de gases poluentes na atmosfera, a poluição sonora e o consumo de petróleo. No entanto, sua limitada autonomia e a escassez de postos de recarga intimidam sua adoção. Por conta disso, políticas governamentais de incentivo têm sido desenvolvidas para a oferta de benefícios a quem optar por um veículo elétrico. Estima-se que dentro de poucas décadas toda a frota urbana será substituída por veículos dessa natureza. Por isso, é importante entender as mudanças no tempo de viagem e no consumo de energia oriundos da inclusão de veículos elétricos em cenários de tráfego. Trabalhos anteriores estudaram as diferenças entre os mecanismos internos de veículos convencionais e elétricos na determinação destas mudanças. Porém, dadas as características destes últimos, motoristas de veículos elétricos se preocupam com a economia de energia e podem optar por rotas diferentes. Logo, uma análise completa destes impactos deve considerar uma nova distribuição de tráfego. Este trabalho propõe um método biobjetivo de alocação de tráfego que considera o tempo de viagem e o consumo de energia para determinar a distribuição de veículos elétricos em cenários de tráfego urbano. Duas estratégias de distribuição de fluxo são propostas como mecanismos de escolha de rotas. Como parte da alocação de tráfego, é proposto um algoritmo biobjetivo de caminhos mínimos para veículos elétricos. A abordagem apresentada foi aplicada a três cenários distintos, onde percebeu-se uma diminuição de até 80% no consumo total de energia. Em cenários com congestionamento, observou-se um aumento de 10% no tempo de viagem. Já em cenários sem congestionamento o tempo de viagem diminuiu cerca de 2%. A recuperação de energia representa quase 6% da economia total dos veículos elétricos. Além disso, experimentos mostraram que investimentos na eficiência dos veículos elétricos podem resultar em uma economia de até 15% de energia. / The search for urban mobility solutions that minimize the aggression to the environment is increasing. Electric vehicles are an attractive alternative because they reduce greenhouse gas emissions, noise pollution, and oil consumption. However, their limited autonomy and the lack of charging stations restrict their popularization. Therefore, government incentive policies have been developed in order to offer benefits to those who choose an electric vehicle. It is estimated that the entire urban fleet will be replaced by these vehicles in a few decades. Therefore, it is important to understand the changes in travel time and energy consumption from the inclusion of electric vehicles in traffic scenarios. Previous works determined these changes by studying the differences between the internal engine of conventional and electric vehicles. However, given the characteristics of the latter, drivers of electric vehicles care about saving energy and may want to choose different routes. Thus, a complete analysis of these impacts should consider a redistribution of traffic. This work proposes a bi-objective traffic assignment method that considers the travel time and the energy consumption to determine the distribution of electric vehicles in urban traffic scenarios. We introduce two strategies for flow distribution as models of route choice. As a procedure of the traffic assignment method, we propose a bi-objective shortest path algorithm for electric vehicles. Our approach was applied to three different scenarios, which resulted in a decrease of up to 80% in total energy consumption. In congested scenarios, we observe an increase of about 10% in average travel time. In uncongested scenarios, travel time decreases about 2%. Energy recovery is almost 6% of the total savings of electric vehicles. Moreover, experiments have shown that investments in the efficiency of electric vehicles can result in up to 15% of energy savings.

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.

[pt] A organização lógica de data centers recai principalmente na questão estratégica de distribuir os serviços nos equipamentos de forma que os custos operacionais sejam os menores possíveis. Além desses custos, devem ser considerados outros aspectos que envolvem a interdependência de seus serviços internos e a distribuição entre suas localidades, visando assim melhorar a qualidade de seu produto aos seus clientes. Este trabalho explora o problema de atribuição de processos a máquinas do desafio ROADEF de 2012 pelos métodos de programação inteira e geração de colunas. Apresenta estratégias para lidar com as dificuldades numéricas encontradas. Na geração de colunas, analisa técnicas para acelerar a convergência, por meio de resolver o mestre restrito após cada variável, geração prévia de colunas e estabilização das variávies duais. Ao final do trabalho, são comparados os resultados obtidos com os melhores resultados oficiais. / [en] A data center logic organization lies mainly by the strategic decision on how distribute services between machines, so the operational costs should be the smallest as possible. Beside those costs, must also consider the interdependence of their own services, the distribution between their localities, to improve the quality of their product to their customers. This work explores the challenge ROADEF 2012 machine assignment problem by the means of integer programming and column generation. Shows strategies to address numeric issues. At column generation, it analyzes techniques to speed up the convergence, by solving after each variable adiction, a previous generation of columns and stabilization of duals variables. At the end of the work, it compares the results obtained are compared with the best official results.

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.