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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
61

Modelling and Optimal Control of a Variable Nozzle Turbine in an SI Engine for Maximum Performance

Fransson Brunberg, Emil, Bolin, Karl January 2022 (has links)
The ever increasing demands on today's engine performance and emissions control is forcing the automotive industry to make use of innovative solutions. One of these is to apply the technology of VNT turbos on commercial petrol vehicles. When using a VNT turbo, the aspect ratio of the turbine can be altered while driving to suit the current operating window. In order to actually gain performance while using a VNT, the vanes have to be properly controlled using a suitable control strategy. In this project, direct collocation have been utilized through the usage of YOP which is an adaptation of CasADi in MATLAB to solve non-linear optimization problems. Comprehensive models of the turbocharger and the cylinders have been built and validated to properly represent a VEP4 LP engine from AUROBAY. The models are implemented in YOP to create and simulate different OCPs using the turbo speed as state and position of the vanes as control signal. With this model in YOP together with the air mass flow per second as reference, a good reference following together with decent values for relevant parameters can be accomplished. Other objective functions such as minimum time and maximal volumetric efficiency are also investigated in the project which yield likewise results. From the results it can be concluded that this type of model and control strategy can be used with success when studying optimal control of a VNT turbo.
62

A study of collocation in Hong Kong interlanguage

Lim, Yuk-wan, Grace., 林玉雲. January 1997 (has links)
published_or_final_version / English Studies / Master / Master of Arts
63

Telecom Infrastructure Sharing as a Strategy for Cost Optimization and Revenue Generation : A Case Study of MTN Nigeria/Zain Nigeria Collocation

Onuzuruike, Emeka January 2009 (has links)
There is a growing need for operators and providers in the Nigerian telecoms industry to drive down cost of capital assets or infrastructure deployed for telecom services. This has been expressed in recent times by many operators who now come, together , on basis of mutual, agreements , to consider sharing infrastructure. The telecom market in Nigeria is driven by growing demand for telecommunications services like voice, SMS, data services like internet, fax, etc as well as high broadband services like video calling, video messaging and video conferencing. This high demand from telecom users combined with the heated competition of a gradually maturing telecoms market in Nigeria has driven many telecoms operators to explore ways of reaching their potential customers in very cost efficient and cost effective ways, hence the need to reduce the cost of rolling out telecom infrastructure while at the same time achieving the numbers through effective network coverage. Also, the regulatory body in Nigeria,NCC( Nigeria Communications Commission) has also given its backing to this initiative by providing the legal and technical guidelines that would ensure fairplay and enhance fair competition. This study or research aims at exploring the value of infrastructure sharing as a means of achieving cost efficiency and revenue assurance. The research is based on a case study analysis of the current collocation arrangement between MTN Nigeria Ltd and Zain Nigeria Ltd. The study seeks to explore the benefits of the infrastructure sharing deal between these two companies as well as recommend an improved or enhanced framework or model to sustain this strategy model in the context of the Nigerian telecommunications industry. Based on a survey/interview of 20 respondents drawn from key departments involved in this sharing deal, the following conclusions were drawn. (1) That both operators have experienced significant reduction in their cost of CAPEX(capital expenditure) employed in network rollouts/deployments; (2) that passive infrastructure(network infrastructure sharing) has led to an improved cost efficiency in network deployments; (3) that infrastructure sharing has led to improved network based operational expenditure; (4) that passive infrastructure sharing has enabled operators achieve improved coverage and capacity; (5) that infrastructure sharing has had no negative impact on customer experience and quality of service; (6) that infrastructure sharing has led to improved service delivery by telecoms operators whereby captial gained or recouped has been invested in product innovations through better value added services to gain competitive advantage. The implications of these findings is that telecom infrastructure sharing serves as an effective business model for cost optimization and revenue generation for telecom operators in Nigeria and the rest of Africa. / +234-8032005495
64

Contribution à l'évolution des méthodologies de caractérisation et d'amélioration des voies ferrées

Rhayma, Noureddine 06 July 2010 (has links) (PDF)
Ce travail se base en premier lieu, sur une approche expérimentale de mesure des caractéristiques mécaniques et géométriques des composants de l'infrastructure de la voie. Un couplage du pénétromètre dynamique Panda et géoendoscope a permis de mesurer les épaisseurs ainsi que les modules des différentes couches de la voie et de fournir ainsi un base de données complète. Un traitement statistique des échantillons de mesure a permis de décrire l'incertitude qui entache ces caractéristiques de la voie. Afin d'en prendre en compte la variabilité dans le modèle EF, nous présentons la méthode de collocation stochastique destinée à l'analyse probabiliste d'un modèle dynamique représentant une section de voie ferrée. Cette méthode permet l'estimation des moments statistiques du processus de réponse ou de toute variable de contrôle liée à ce processus. Dans un second temps, nous avons mené une analyse paramétrique afin de quantifier de manière probabiliste l'apport des diverses opérations de maintenance : relevage de la voie, traitement de la souche avec renouvellement du ballast et opération de traitement de la plate-forme par amélioration des conditions de drainage. Cette analyse a montré le grand apport des deux derniers types de traitement en termes de diminution de la dispersion de la réponse du modèle et surtout de réduction des risques de défaillance. L'apport des opérations d'amélioration des conditions de drainage reste cependant plus bénéfique pour le comportement de la voie en terme de sécurité
65

Stochastic simulation of the cure of advanced composites

Mesogitis, Tassos January 2015 (has links)
This study focuses on the development of a stochastic simulation methodology to study the effects of cure kinetics uncertainty, in plane fibre misalignment and boundary conditions uncertainty on the cure process of composite materials. Differential Scanning Calorimetry was used to characterise cure kinetics variability of a commercial epoxy resin used in aerospace applications. It was found that cure kinetics uncertainty is associated with variations in the initial degree of cure, activation energy and reaction order. Image analysis was employed to characterise in plane fibre misalignment in a carbon fibre ±45º non-crimp fabric. The experimental results showed that variability in tow orientation was significant with a standard deviation of about 1.2º. A set of experiments using an infusion set-up was carried out to quantify boundary conditions uncertainty related to tool temperature, ambient temperature and surface heat transfer coefficient using thermocouples (tool/ambient temperature) and heat flux sensors (surface heat transfer coefficient). It was concluded that boundary conditions uncertainty can show considerable short term and long term variability. Conventional Monte Carlo and Probabilistic Collocation Method were integrated with a thermo-mechanical cure simulation model in order to investigate the effect of cure kinetics, fibre misalignment and boundary conditions variability on process outcome. The cure model was developed and implemented using a finite element model incorporating appropriate material sub-models of cure kinetics, specific heat capacity, thermal conductivity, moduli, thermal expansion and cure shrinkage. The effect of cure kinetics uncertainty on the temperature overshoot of a thick carbon fibre epoxy flat panel was investigated using the two stochastic simulation schemes. The stochastic simulation results showed that variability in cure kinetics can introduce a significant scatter in temperature overshoot, presenting a coefficient of variation of about 30%. Furthermore, it was shown that the collocation method can offer an efficient solution with significantly lower computational cost compared to Monte Carlo at comparable accuracy. Stochastic simulation of the cure of an angle shaped carbon fibre-epoxy component within the Monte Carlo scheme showed that fibre misalignment can cause considerable variability in the process outcome. The coefficient of variation of maximum residual stress can reach up to approximately 2% (standard deviation of 1 MPa) whilst qualitative and quantitative variations in final distortion of the cured part occur with the standard deviation in twist and corner angle reaching values of 0.4 º and 0.05º respectively. Simulation of the cure of a thin carbon fibre-epoxy panel within the Monte Carlo scheme indicated that surface heat transfer and tool temperature variability dominate variability in cure time, resulting in a coefficient of variation of about 22%. In addition to Monte Carlo, the effect of surface heat transfer coefficient and tool temperature variations on cure time was addressed using the collocation method. It was found that probabilistic collocation is capable of capturing variability propagation with good accuracy while offering tremendous benefits in terms of computational costs.
66

Paraphrasage des liens de fonctions lexicales

Popovic, Stéfan January 2003 (has links)
Mémoire numérisé par la Direction des bibliothèques de l'Université de Montréal.
67

Binomiály v češtině a ruštině / Binomials in Czech and Russian

Motornyuk, Alina January 2014 (has links)
The graduation thesis is dedicated to the binomials in the Czech and Russian languages. The author paid her attention to the substantive binomials, to the determination of their semantic categories and syntactic functions and to the comparison of the results of both languages. The source for the analysis is binomials, which were found in the Czech national corpus and the Russian national corpus.
68

Da tradução ou não de pronomes e partículas pronominais do Italiano ao Português: algumas escolhas feitas por dois tradutores / Translation or not of pronouns and pronominal particles from Italian to Portuguese: some choices made by two translators

Thiago, Irene Soares 03 March 2016 (has links)
Este estudo é movido pela curiosidade quanto a como se resolvem, nas traduções do italiano para o português, questões de colocação pronominal. Encontramos, normal e frequentemente, na língua italiana, principalmente na língua falada, pronomes cujos equivalentes em português existem em gramáticas normativas da língua portuguesa, mas que, na prática, não são utilizados pelos falantes e escritores brasileiros. Encontramos, também, na língua italiana, um significativo número de verbos pronominais (como esserci, volerci, averne etc.) e um considerável número de verbos pronominais múltiplos (como andarsene, farcela, fregarsene etc.) que, juntamente com esses pronomes, constituem, para os professores brasileiros de italiano língua estrangeira (LE), elementos difíceis de trabalhar na sala de aula. Além disso, tais elementos também podem dificultar o trabalho dos tradutores, que devem fazer determinadas escolhas ao traduzi-los para o português. Como são traduzidos os pronomes combinados do italiano nas versões brasileiras? Será que os portugueses, que possuem, por exemplo, tais pronomes utilizam-nos em todos os casos em que os encontramos nos textos de partida? E as partículas pronominais são simplesmente eliminadas no texto de chegada ou são substituídas? Tais aspectos, se observados e organizados, podem levar a uma melhor compreensão das duas línguas em contato e dar subsídios a estudantes, professores e tradutores. Pensando nessa dificuldade, esta pesquisa buscou e listou alguns autores e obras disponíveis para consulta e analisou um corpus com cento e sessenta e três ocorrências de pronomes no italiano, mais sete acréscimos de pronomes no português brasileiro (PB) e/ou português europeu (PE), partindo do romance Uno, nessuno e centomila de Luigi Pirandello e suas respectivas traduções em PB e PE. Nosso objetivo consiste em encontrar respostas úteis à diminuição do estranhamento, por parte de um italiano, que escuta, de um brasileiro, frases sem pronomes (ainda que o italiano as entenda) e/ou a sensação de inadequação e, até mesmo, de desconforto, por parte de um brasileiro, ao produzir frases com todos os pronomes. No corpus analisado, temos uma amostra das escolhas e respectivas traduções propostas pelos tradutores para casos de pronomes reflexivos, de pronomes pessoais do caso reto, de pronomes pessoais do caso oblíquo, de pronomes combinados e de partículas pronominais ne, ci e vi, com manutenções, omissões, trocas por outros pronomes (possessivos, retos, oblíquos, demonstrativos) e, até mesmo, uma espécie de compensação numérica com a inclusão de palavra inexistente no texto de partida. / This study is conducted by the curiosity on how pronoun collocations issues are solved in translations from Italian to Portuguese. We usually and normally find in the Italian, especially in the spoken language, pronouns whose equivalent in are given in normative grammars of the Portuguese language, but that are not used in pratice neither in written nor in the spoken language. We also find in the Italian language, a significant number of pronominal verbs (as esserci, volerci, averne etc.) and a considerable number of multiple pronominal verbs (as andarsene, farcela, fregarsene etc.) which are also difficult to work in the classroom. Furthermore, these elements can also hamper the work of translators, who must make certain choices to translate them into Portuguese. The question then arises, how are Italian combined pronouns rendered in Brazilian and European Portuguese translations? Do European Portuguese speakers, who use such pronouns, use them in all cases in which we find them in source texts? Are combined pronouns simply eliminated in the target text or are they replaced? Such aspects, when observed and organized, can lead to a better understanding of the two languages in contact and give grants to students, teachers and translators. Considering this difficulty, this research sought and listed some authors and available works for consultation and examined a corpus of one hundred sixty-three occurrences of pronouns in Italian, plus seven uses of pronouns in Brazilian Portuguese (BP) and/or European Portuguese (EP), based on the novel Uno, nessuno and centomila by Luigi Pirandello and its corresponding translations into PB and PE. Our objective is to find useful answers for the decrease of strangeness of an Italian listening to a Brazilian who is using sentences without pronouns (although the Italian understands them) and/or the feeling of inadequacy and even discomfort of a Brazilian to produce sentences with all the pronouns. In the analyzed corpus, we have a sample of the choices made by translators to translate reflexive, personal subjective pronouns and objective pronouns, combined pronouns and the pronominal particles ne, ci e vi, showing cases of maintenance, omission, exchanges for other pronouns (possessive, subjective, objective, demonstrative) and even a kind of numerical compensation with the inclusion of a full noun not occurring in the source text.
69

Kolokacioni postupci za rešavanje singularno perturbovanih problema / Collocation methods for solving singular perturbation problems

Radojev Goran 22 December 2015 (has links)
<p>U disertaciji su razvijeni kolokacioni postupci sa C<sup>1</sup>- splajnovima&nbsp;proizvoljnog stepena za re&scaron;avanje singularno-perturbovanih problema&nbsp;reakcije-difuzije u jednoj i dve dimenzije. U 1D, pokazano je da kolokacioni&nbsp;postupak sa kvadratnim C<sup>1</sup>-&nbsp;splajnom na modifikovanoj &Scaron;i&scaron;kinovoj mreži,&nbsp;konvergira uniformno, sa redom konvergencije skoro dva. Takođe, na gradiranim mrežama, ovaj metod ima red konvergencije dva &ndash; uniformno do na logaritamski faktor. Aposterirona ocena je postignuta za kolokacione postupke sa C<sup>1</sup>- splajnovima proizvoljnog stepena na proizvoljnoj mreži. Ova ocena je iskori&scaron;ćena i za kreiranje adaptivnih mreža. Numerički rezultati povtrđuju dobijene ocene. U 2D su razmatrane kolokacije sa bikvadratnim splajnovima. Aposterirona ocena gre&scaron;ke je postignuta. Numerički rezultati potvrđuju dobijene teorijske rezultate.<br />&nbsp;</p> / <p>Collocations with arbitrary order C<sup>1</sup>-splines for a singularly perturbed reaction-diffusion problem in one dimension and two dimensions are studied. In 1D, collocation with quadratic C<sup>1</sup>-splines is shown to be almost second order accurate on modified Shishkin mesh in the maximum norm, uniformly in the perturbation parameter. Also, we establish a second-order maximum norm a priori estimate on recursively graded mesh uniformly up to a logarithmic factor in the singular perturbation parameter. A posteriori error bounds are derived for the collocation method with arbitrary order C<sup>1</sup>-splines on arbitrary meshes. These bounds are used to drive an adaptivemeshmoving algorithm. An adaptive algorithm is devised&nbsp;to resolve the boundary layers. Numerical results are presented. In 2D, collocation with biquadratic C<sup>1</sup>-spline is studied. Robust a posteriori error bounds are derived for the collocation method on arbitrary meshes. Numerical experiments completed our theoretical results.</p>
70

Contribution à l'évolution des méthodologies de caractérisation et d'amélioration des voies ferrées

Rhayma, Noureddine 06 July 2010 (has links) (PDF)
Le thème de recherche proposé s'inscrit dans une démarche de compréhension du comportement de la voie ballastée sous circulation commerciale. Les principaux objectifs de la thèse sont alors, d'une part la caractérisation des di fférents paramètres de la voie ainsi que leur variabilité et d'autre part la prédiction du comportement mécanique d'une voie ballastée par modélisation numérique a n d'optimiser les opérations de maintenance et de réduire les coûts d'entretien. Ce travail se base en premier lieu, sur une approche expérimentale de mesure des caractéristiques mécaniques et géométriques des composants de l'infrastructure de la voie. Un couplage du pénétromètre dynamique Panda et géoendoscope a permis de mesurer les épaisseurs ainsi que les modules des diff érentes couches de la voie et de fournir ainsi une base de données complète. Un traitement statistique des échantillons de mesures a permis de décrire l'incertitude qui entache ces caractéristiques de la voie. A fin d'en prendre en compte la variabilité dans le modèle EF, nous présentons la méthode de collocation stochastique destinée à l'analyse probabiliste d'un modèle dynamique représentant une section de voie ferrée. Cette méthode permet l'estimation des moments statistiques du processus de réponse ou de toute variable de contrôle liée à ce processus. Dans un second temps, nous avons mené une analyse paramétrique a n de quanti er de manière probabiliste l'apport des diverses opérations de maintenance : relevage de la voie, traitement de la sous-couche avec renouvellement du ballast et opération de traitement de la plate-forme par amélioration des conditions de drainage. Cette analyse a montré le grand apport des deux derniers types de traitement en termes de diminution de la dispersion de la réponse du modèle et surtout de réduction des risques de défaillance. L'apport des opérations d'amélioration des conditions de drainage reste cependant plus béné fique pour le comportement de la voie en terme de sécurité.

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