Various data structures have been proposed for representing the connectivity of manifold triangle meshes. For example, the Extended Corner Table (ECT) stores V+6T references, where V and T respectively denote the vertex and triangle counts. ECT supports Random Access and Traversal (RAT) operators at Constant Amortized Time (CAT) cost. We propose two novel variations of ECT that also support RAT operations at CAT cost, but can be used to represent and process Simplicial 2-Complexes (S2Cs), which may represent star-connecting, non-orientable, and non-manifold triangulations along with dangling edges, which we call sticks. Vlist stores V+3T+3S+3(C+S-N) references, where S denotes the stick count, C denotes the number of edge-connected components and N denotes the number of star-connecting vertices. Ering stores 6T+3S+3(C+S-N) references, but has two advantages over Vlist: the Ering implementation of the operators is faster and is purely topological (i.e., it does not perform geometric queries). Vlist and Ering representations have two principal advantages over previously proposed representations for simplicial complexes: (1) Lower storage cost, at least for meshes with significantly more triangles than sticks, and (2) explicit support of side-respecting traversal operators which each walks from a corner on the face of a triangle t across an edge or a vertex of t, to a corner on a faces of a triangle or to an end of a stick that share a vertex with t, and this without ever piercing through the surface of a triangle.

The purpose of this thesis is to perform numerical solutions of hypersonic, high temperature, perfect gas flows over various geometries. Three dimensional, thin layer, compressible, Navier-Stokes equations are solved. An upwind finite difference approach with Lower Upper-Alternating Direction Implicit (LU-ADI) decomposition is used. Solutions of laminar, hypersonic, high temperature, perfect gas flows over flat plate and compression corners (qw=5&deg / , 10&deg / , 14&deg / , 15&deg / , 16&deg / , 18&deg / and 24&deg / ) with eight different free-stream and wall conditions are presented and discussed. During the analysis, air viscosity is calculated from the Sutherland formula up to 1000&deg / K, for the temperature range between 1000 &ordm / K and 5000 &ordm / K a curve fit to the estimations of Svehla is applied. The effects of Tw/T0 on heat transfer rates, surface pressure distributions and boundary layer characteristics are studied. The effects of corner angle (&amp / #952 / w) on strong shock wave/boundary layer interactions with extended separated regions are investigated. The obtained results are compared with the available experimental data, computational results, and theory.

Η παρούσα διπλωματική εργασία αναπτύχθηκε στα πλαίσια των προπτυχιακών σπουδών του τμήματος Ηλεκτρολόγων Μηχανικών και Τεχνολογίας Υπολογιστών του Πανεπιστημίου Πατρών. Θέμα της είναι η τρισδιάστατη ανακατασκευή του χώρου από τουλάχιστον δύο φωτογραφίες του και αποτελεί μέρος του τομέα της Υπολογιστικής Όρασης. Συγκεκριμένα αναλύεται διεξοδικά η περίπτωση της στερεοσκοπικής όρασης, στην οποία η κάμερα μεταξύ δύο διαδοχικών λήψεων της ίδιας σκηνής, έχει μηδενική σχετική περιστροφή ως προς την αρχική της θέση και μικρή μετατόπιση, περίπου 5 εκατοστά. Με τον τρόπο αυτό, προσπαθούμε να προσομοιώσουμε τη λειτουργία της ανθρώπινης όρασης καθώς πολλές εφαρμογές της Τεχνητής Νοημοσύνης το κρίνουν απαραίτητο. Είναι λογικό ότι ο κάθε άνθρωπος θεωρεί τη στερεοσκοπική όραση αυτονόητη γιατί κινείται στον τρισδιάστατο κόσμο. Όταν αυτός όμως καταγράφεται από μία κάμερα, αυτόματα περνάει στο δισδιάστατο επίπεδο. Και πάλι είναι δυνατόν να εξάγουμε πληροφορίες βάθους από μία μόνο εικόνα, όμως γίνεται καθαρά εμπειρικά και βασίζεται στη σύγκριση διάφορων υφών, σχημάτων και μεγεθών. Ο ηλεκτρονικός υπολογιστής αναγνωρίζει την εικόνα σαν ένα οποιοδήποτε αρχείο. Δεν μπορεί να εξάγει κανένα συμπέρασμα για το τι απεικονίζει στον πραγματικό κόσμο. Χρειάζεται το συνδυασμό τουλάχιστον δύο εικόνων της ίδιας σκηνής από διαφορετικές θέσεις για να μπορέσει να αναγνωρίσει για παράδειγμα το βάθος της σκηνής που απεικονίζεται. Αυτή τη διαδικασία περιγράφει αναλυτικά η εργασία. Στο πρώτο κεφάλαιο εισάγουμε την έννοια και τη χρησιμότητα της στερεοσκοπικής όρασης. Στο δεύτερο κεφάλαιο παρουσιάζονται οι βασικές αρχές της προβολικής γεωμετρίας. Στο τρίτο κεφάλαιο αναφερόμαστε στη μοντελοποίηση της κάμερας και τις παραμέτρους που τη χαρακτηρίζουν. Στο τέταρτο κεφάλαιο αναλύεται η διαδικασία της βαθμονόμησης της κάμερας. Στο πέμπτο κεφάλαιο εξηγείται η διαδικασία αντιστοίχησης των σημείων ενδιαφέροντος στις δύο εικόνες. Στο έκτο κεφάλαιο αναλύονται οι βασικές αρχές της επιπολικής γεωμετρίας. Στο έβδομο κεφάλαιο παρουσιάζεται η πειραματική διαδικασία για την εύρεση του βάθους της σκηνής. Στο όγδοο κεφάλαιο παρουσιάζεται συνοπτικά η τρισδιάστατη ανακατασκευή του χώρου και παρουσιάζονται τα αντίστοιχα πειραματικά αποτελέσματα. Στο ένατο κεφάλαιο διατυπώνουμε τα συμπεράσματα της όλης διαδικασίας. Τόσο το θεωρητικό όσο και το πειραματικό μέρος αυτής της εργασίας καλύπτουν σε ένα μεγάλο ποσοστό τα βασικά στάδια ανακατασκευής του τρισδιάστατου χώρου. Τα αποτελέσματα της πειραματικής διαδικασίας αποδεικνύουν ότι οι υπάρχουσες μέθοδοι λειτουργούν ικανοποιητικά αλλά υπάρχουν πολλά περιθώρια βελτίωσης στο θέμα της Υπολογιστικής Όρασης. Στο σημείο αυτό να ευχαριστήσουμε τον επιβλέποντα καθηγητή μας κ. Δερματά για τη συνεργασία του και την κατανόησή του. / The current thesis has been written as part of the undergraduate studies for the department of Electrical and Computer Engineering of Patras University. Its objective is the three-dimensional (3D) reconstruction from two, at least, photographs, which is part of computer vision. More specifically, this thesis analyzes in detail the case of stereo vision when the camera, among two successive shots of the same image, has zero relative rotation compared to its initial position and an average translation of about 5 cm. In this way, it attempts to simulate human vision since this is essential for many Artificial Intelligence applications. Humans take stereo vision for granted since they live in a three-dimensional world. However, this world becomes two-dimensional when recorded by a camera. We can still get information about the image depth but this is empirically done based on comparing various heights, shapes and sizes. Images are identified by the computer as any other file. Computers cannot draw conclusions about what is depicted in the real world. They need to combine at least two images of the same scene and of different positions to identify the image’s depth. This process is described in the current thesis. The first chapter describes stereo vision and why it is so useful. The second chapter provides the basic principles of projective geometry, the mathematical background for passing from the two-dimensional level to the three-dimensional. The third chapter refers to camera modeling and its parameters (instrisic and extrinsic). Chapter four analyzes the camera calibration process. Chapter five explains the matching process of points of interest in both pictures. The sixth chapter provides the basic principles of epipolar geometry. The seventh chapter shows the experimental procedure that we followed in order to estimate the depth of the scene. Chapter eight shows how the 3D reconstruction is finally done. Chapter nine talks about our conclusions and how the results could improve. Both theoretical and experimental parts of this project cover the key points of 3d reconstruction. The results of the experiments show that the existing methods are satisfying but could improve more. We want to thank our supervisor professor Mr. Dermatas for his collaboration and his understanding.

Ma thèse de doctorat a comme objectif de contribuer d'un point de vue théorique et empirique à la littérature sur les modèles collectifs avec production domestique. On veut montrer que les modèles collectifs représentent un instrument alternatif aux modèles unitaires de représentation du comportement individuel. Les modèles collectifs peuvent être utilise pour analyser la distribution des ressources au sein du ménage et pour évaluer le pouvoir de négociation de l'homme et de la femme. Ce dernier a des effets sur l'offre de travail, sur la consommation et sur le bien-être des individus dans le ménage. Dans les deux premiers chapitres, en utilisant les données de l'American Time Use Survey, on veut estimer les offres de travail de marché de l'homme et de la femme. Dans le première on se concentre sur la question de l'identification de la règle de partage lorsque il n'y a pas des facteurs de distribution observés. Dans le deuxième travail on prend en compte les solutions en coins. Dans les troisième et le quatrième chapitre on veut étendre les modèles sur les ménages agricoles du pays en voie de développement à l'approche collective. Dans le premier travail on se concentre sur la propriété de séparabilité du model lorsque les individus du ménage sont engagés dans la production d'un bien non-marchand et peuvent ne pas travailler sur le marché. Dans le deuxième on conduise des simulations en utilisant des données italienne. / The objective of this research project is to contribute from both a theoretical and empirical perspective to the literature about collective models of household behavior accounting for household production. In particular, the aim is to show that the collective models represent an alternative tool with respect to unitary models of household behavior with the advantage to allow the analysis of intra-household distribution of resources. This has some effects on individual labor supply, consumption and material well-being. In the first two chapters, using the American Time Use Survey, the objective is to estimate man and woman's market labor supply. In the first work we prove a new identification result of the sharing rule for the case where no distribution factor is observable. The second work develops a theoretical model of labor supply with domestic production that is consistent with corner solutions. In the third and fourth chapter the objective is to extend the farm-household literature to the collective approach. In the first work we focus on the separability property on the model when both the price of the domestic produced good and the price of individual time are endogenously determined within the household. We present some statics comparative results. In the second work, using Italian ISMEA data, we carry out a simulation.

Les oscillations de pression sont un enjeu majeur dans le design des moteurs à propergol solide car de faibles oscillations de pression (ODP) dans la chambre entraînent de fortes oscillations de poussée ce qui conduit à des vibrations néfastes pour les structures et les satellites embarqués. Les ODP sont encore aujourd'hui un vaste sujet de recherche et la simulation numérique est un outil indispensable dans leur analyse. De nombreux travaux ont permis de mettre en évidence divers mécanismes générateurs d'oscillations, mais la conception des nouveaux moteurs favorise la formation d'une instabilité hydrodynamique, appelée VSA et caractérisée par des détachements tourbillonnaire au niveau des discontinuités de la surface débitante. Etudiée dans les travaux sur le C1x [Vuillot 1995, Dupays 1996], il reste cependant divers points à aborder afin d'avoir une vision complète des mécanismes qui pilotent et modifient cette instabilité. Pour cela, il a été choisi dans ces travaux d'isoler le VSA dans une configuration académique et d'étudier dans un premier temps, l'impact du soufflage latéral, généré par un dégagement gazeux du à la combustion d'un bloc de propergol en aval de l'angle. Les deux approches utilisées, à savoir la simulation numérique et la stabilité linéaire, démontrent que le soufflage latéral possède un fort effet stabilisant sur le VSA. Dans un deuxième temps, l'impact de la combustion des particules d'aluminium et des résidus, présents dans un moteur à propergol solide, est analysé. Ces travaux montrent que les particules, via des mécanismes complexes, peuvent jouer à la fois un rôle stabilisant et déstabilisant sur le VSA. Pour finir, l'impact de la mise à l'échelle sur l'instabilité est étudié. Si en gaz seul, les résultats obtenus à échelle réduite sont directement transposables vers l'échelle réelle, la mise à l'échelle modifie le comportement des particules dans les structures tourbillonnaires et donc leur rôle sur l'instabilité. / Pressure oscillations (ODP) are a major issue in solid rocket motor design, as very small pressure oscillations induce strong thrust oscillations, involving vibrations detrimental to carrying load. ODP are still a vast and intense domain of research and the improvement of rocket motors mainly resorts to advanced numerical simulations. Extensive research have enabled to characterize several sources of instabilities, but new motor design promotes one hydrodynamic instability, called VSA and characterized by vortex shedding at geometry angles. VSA has be studied in the C1x configuration [Vuillot 1995, Dupays 1996] but several points still need to be studied in order to have a complete view of the phenomena driving and impacting this instability in a solid rocket motor flow. In this work, the VSA is isolated in an academic configuration and, in a first part, the impact of lateral blowing is studied. This blowing, never analysed so far, is due to burnt gases coming from the combustion of propellant block after the angle. This study has been performed following two approaches, numerical simulations and linear stability analysis. Both demonstrate the strong stabilizing effect of the lateral blowing. In a second part, the impact of aluminium particles combustion including the presence of residual particles, found in solid rocker motors, is analysed. This work shows that due to complex interaction mechanisms, particles can have a stabilizing or a destabilizing impact on the instability. Finally, the scaling impact is studied with and without particles. In purely gaseous configuration, the results obtained at reduced scale can be used directly at real scale as all the characteristics of the instability are preserved. However, with particles, the scaling modifies the particles behaviour and then the particles impact on the VSA.

The current technologies for acquisition, storage and transmission of digital data, generate large amounts of data. This quantitative increase is directly proportional to the expansion of multimedia databases, where the bases are part of images. Factors contributing to this expansion is the generation of data access and multimedia, which are frequently used by the population through the media today. Thus, we find a clear need exists for automated systems, capable of dealing with the storage and retrieval of data in a time acceptable to the current standards. To this end, systems are designed for content retrieval of images, where the content is described through its low-level visual features such as shape, texture and color. To have such a system is considered ideal, it must be efficient and effective. The effectiveness will result from the way the information was obtained as a low level of images, considering different conditions of focus, lighting and occlusion. The efficiency is a consequence of the results obtained using the organization of information extracted. The methods of grouping are in one of the useful techniques to reduce the computational complexity of these systems, reducing the computational complexity of the methods implemented, but without losing the representation of information extracted. This work proposes a method for retrieval of images based on content, using appropriate techniques of clustering, a technique for detecting edges and a method to normalize the images in the aspect of enlightenment, to get through it the image descriptors that are robust and can be applied efficiently in a retrieval system for images by content - CBIR (Content Based Image Retrieval). / As tecnologias atuais de aquisição, armazenamento e transmissão de dados digitais geram grandes quantidades de dados. Esse aumento quantitativo é diretamente proporcional à ampliação das bases de dados multimídia, onde se inserem as bases de imagens. Fatores relevantes que contribuem para esta ampliação são o acesso e a geração de dados multimídia, os quais são freqüentemente utilizados pela população através dos meios de comunicação atuais. Desta forma, percebe-se claramente a necessidade existente por sistemas automatizados, capazes de lidar com o armazenamento e a recuperação destes dados em um tempo aceitável para os padrões atuais. Para este fim, são desenvolvidos sistemas de recuperação de imagens por conteúdo, onde este conteúdo é descrito através de suas características visuais de baixo nível, como forma, textura e cor. Para que um sistema deste tipo seja considerado ideal, ele deve ser eficiente e eficaz. A eficácia será resultado da maneira de como foram obtidas as informações de baixo nível das imagens, considerando diferentes condições de foco, oclusão e iluminação. A eficiência é conseqüência dos resultados obtidos utilizando-se a organização das informações extraídas. Os métodos de agrupamento constituem em uma das técnicas úteis para diminuir a complexidade computacional destes sistemas, uma vez que agrupa informações com características semelhantes, sob determinado critério, porém sem perder a representatividade das informações extraídas. Este trabalho propõe um método para recuperação de imagens baseada em conteúdo, que utiliza apropriadamente as técnicas de agrupamento, uma técnica de detecção de cantos e um método para normalizar as imagens no aspecto da iluminação, visando através disso obter descritores da imagem que sejam robustos e possam ser aplicados eficientemente em um sistema de recuperação de imagens por conteúdo - CBIR(Content Based Image Retrieval).

Introdução: A lesão traumática do canto posterolateral pode resultar em comprometimento do nervo fibular comum (NFC). A presença de lesão do nervo fibular comum pode implicar em mudanças de decisões terapêuticas e determinar sequelas sensitivas e motores. O objetivo principal deste estudo é descrever o aspecto de imagem da lesão crónica do nervo fibular comum após lesão traumática do canto posterolateral (CPL), por meio de imagens de Ultrassonografia (US) e Ressonancia Magnética (RM) e correlacionar com os achados clínicos. Materiais e Métodos: No período de 2009 a 2016, foram coletados 41 pacientes com lesão traumática do canto posterolateral. Destes, 18 apresentavam alteração do nervo fibular comum, sendo que em 5 foram obtidas informações do seguimento clínico, ultrassonográfico e por imagem de RM. Resultados: As imagens de RM de lesão do nervo fibular comum desses 5 pacientes tanto na fase aguda/subaguda após o trauma quanto na crónica foram avaliadas por dois radiologistas musculoesqueléticos, de forma consensual. Na análise das imagens de RM de lesão aguda/subaguda do NFC foram consideradas, 4 casos de neuropraxias e 1 caso de axonotmese. Destes, as imagens por RM e US da lesão crónica do NFC foram classificadas como nervo normal em 2 pacientes, grau I em 2 pacientes e grau 11 em 1 paciente. Finalmente, destes 4 pacientes com NFC classificado como normal e grau 1, ao exame clínico 3 não apresentavam alterações sensitivas e mataras e 1 permaneceu com discretas alterações de sensibilidade e motora. A lesão do NFC de 1 paciente classificada como grau 11, apresentou importantes sequelas sensitivas e motores na avaliação clínica. Conclusão: As alterações do NFC nas lesões traumáticas do CPL do joelho são detestáveis por RM tanto na fase aguda/subaguda quanto na crónica. As lesões crónicas do NFC classificadas como grau I por meio de imagens de RM e US, tiveram pouca ou nenhuma repercussão clínica e a grau 11, tiveram importantes sequelas sensitivas e motores, sugerindo a correlação entre os achados de imagem e a gravidade das sequelas neurais. / The posterolateral corner (PLC) injury may result in injury of common peroneal nerve (CPN). The presence of common peroneal nerve injury may result in changes in therapeutic decisions and determine sensory and motor sequelae. The main objective of this study is to evaluate the image aspect of chronic injury of common peroneal nerve after posterolateral corner injury by means of Ultrasound (US) and Magnetic Resonance (MR) images and correlate with clinical findings. Materials e Methods: A retrospective analysis of 41 patients with posterolateral corner injury was performed. Of these, 18 were considered to have common peroneal nerve injury, and in 5 clinical follow-up information and ultrasound and MR images were obtained. Results: MR images of common peroneal nerve injury of these 5 patients both in acute/subacute and chronic posttraumatic period were evaluated by two musculoskeletal radiologists, by consensus. During acute/subacute period of injury 4 cases were onsidered neuropraxia and 1 case axonotmese. Of these, MR and US images analysis during chronic period CPN were classified as normal nerve in 2 patients, grade I in 2 patients and grade 11 in 1 patient. Finally, the clinical evaluation of the 4 patients with CPN classified as normal or grade 1, showed 3 without sensitive and motor changes and 1 remained with minor sensitivity and motor deficit. The patient with chronic nerve injury classified as grade 11, presented important sensory and motor sequel in clinical evaluation.Conclusion: CPN changes in traumatic injuries of the knee PLC are detectable by MR both in acute/subacute and chronic phase. Chronic lesions of the NFC classified as grade I by MR and US images had little or no clinical manifestation and the injury classified as grade 11 had important sensory and motor sequels, suggesting the correlation between imaging findings and severity of neural sequels.

Orientador: Niza de Castro Tank / Dissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Artes / Made available in DSpace on 2018-08-21T07:31:06Z (GMT). No. of bitstreams: 1 Siqueira_EgleMariaLuzBragaZamariande_M.pdf: 1211156 bytes, checksum: 4bdebf92f5738e046ddd71ae882ac527 (MD5) Previous issue date: 2000 / Resumo: A Música, como modalidade de conhecimento ou como forma de expressão, tem caracterizado uma presença marcante na história do desenvolvimento cultural do Brasil. Considerando as inúmeras possibilidades da Música no processo de ensino, esta dissertação busca refletir sobre sua aplicação em Escolas de Educação Infantil e Ensino Fundamental, partindo de uma concepção construtivista, utilizando conceitos de antropologia cultural e sob a ótica da arte-educação, e descreve experimentos realizados em salas de aula entre os anos de 1992 e 1999. Sob o enfoque qualitativo, utiliza-se a canção como principal material de apoio, escolhida pelo fato de constituir o grande manancial da cultura musical brasileira e trazer em seu bojo importantes elementos referentes à sua linguagem: apreciação contextualização histórica da letra, de compositores e de autores, observação da instrumentação, arranjo e outros. Nestes elementos encontramos rica fonte de conhecimentos musicais, essenciais para a formação básica cultural da criança no processo constituitivo de um público fruidor no contexto musical, a fim de resgatar uma platéia ouvinte. A prática de trabalhar música, partindo da canção, com alunos na faixa etária compreendida de três a dez anos, revelou suas diversas potencialidades concretizando o sucesso das estratégias adotadas e aqui analisadas. Em outubro de 1999 foi realizada a gravação do CD intitulado "Coral da Escola Nova de Mococa", parte integrante desta dissertação / Abstract: Music as a model of knowledge, or just as one way of expression has a strong effect in Brazil cultural development. This dissertation deals with the many possibilities of music as a teaching tool for pre-school and grades 1-8, based on a conception of the constructivism, as well as cultural anthropology and art-education concepts. It describes experiments that were realized in the classroom between 1992/1999. Under the qualitative side it is convenient to make use of songs, since they are a fountainhead of Brazilian Musical Culture. It leads us to believe that is possible to bring out some very important elements such as: language, lyrics, history, composers, instrumentation, arrangement, and communication of the meaning of the words. From these elements we find a very rich musical source route which is essential for the development of the children's culture, and also in the process of creating new audience. The experience of working with songs, with the pupils from 03 to 10 years old, proved that it is possible to work and develop the strategies determined and analyzed through songs with success. In October 1999 was recorded a CD "Coral da Escola Nova" which is part of this dissertation / Mestrado / Artes / Mestre em Artes

Afin de concevoir des systèmes de propulsion innovants, l'amélioration des performances des prises d'air supersonique constitue un enjeu majeur. En particulier, les écoulements intervenant au sein des entrées d'air et/ou de diffuseurs supersoniques mettent en jeu des phénomènes complexes associés aux diverses échelles spatiales et temporelles: dynamique de la turbulence pariétale, interaction entre une onde de choc et une couche limite turbulente, décollements tridimensionnels et effets de coins. Malgré les contributions significatives et récentes des simulations numériques de haute fidélité sur les instationnarités de l'interaction onde de choc/couche limite sans paroi latérales, peu d'études numériques ont été menées sur l'influence des coins dans la dynamique de l'écoulement. En présence de parois latérales et à des nombres de Mach suffisamment élevés, l’interaction se modifie et un train de choc se forme dans le diffuseur. Dans le cadre de cette thèse, les équations de Navier-Stokes en régime compressible sont résolues à l'aide de schémas d'ordre élevé. Des simulations en régime supersonique de l'écoulement dans des diffuseurs rectangulaires de largeurs différentes sont effectuées. L'étude permet la mise en évidence de l'influence du confinement et des effets de coins. Une deuxième partie de l’étude est consacrée à la compréhension des instationnarités générées par un train de choc dans un diffuseur rectangulaire à l'aide d'outils de post-traitement avancés: décomposition modale dynamique et périodogramme. Les résultats montrent la présence d'un possible phénomène de résonance du diffuseur à des fréquences proches de celles émises par l'écoulement. / To design innovative propulsion systems, improving the performance of supersonic air intakes is a major issue. In particular, the flows through the air intakes and/or supersonic diffusers involve complex unsteady phenomena associated with various spatial and temporal scales such as: wall-bounded turbulence dynamics, interaction between a shock-wave and a turbulent boundary layer, three-dimensional separated flows and corners effects. Despite the significant contributions from recent high-fidelity simulations of unsteady shock-wave boundary layer interaction in the absence of side walls, few numerical studies were conducted with secondary flows due to corner effects. In the presence of side walls and at Mach numbers large enough, the topology of the interaction is modified and a shock-train forms in the diffuser. In this thesis, the Navier-Stokes compressible equations are solved using high-order schemes. Simulations of supersonic flows in rectangular diffusers of different widths are carried out. The study allows to highlight the influence of confinement and corners effects on the mean flow. A second part of the study is devoted to the understanding of the unsteadiness associated with a shock-train in a rectangular supersonic diffuser. For that purpose, advanced post-processing tools have been developed such as: dynamic mode decomposition and Fourier analysis. The results show the presence of a possible resonance phenomenon in the diffuser at frequencies close to those associated with the flow.

This paper is concerned with mesh refinement techniques for treating elliptic boundary value problems in domains with re- entrant edges and corners, and focuses on numerical experiments. After a section about the model problem and discretization strategies, their realization in the experimental code FEMPS3D is described. For two representative examples the numerically determined error norms are recorded, and various mesh refinement strategies are compared.