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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.
91

Modélisation biomécanique de la nage avec palmes

Gouvernet, Guillaume 08 July 2011 (has links)
Ce travail doctoral a pour objectif de mettre en place des méthodes permettant de quantifier les efforts subits par le nageur avec palme, lors de la pratique de 3 activités (Natation, Randonnée Aquatique et Body-Board). Pour ce faire, un modèle utilisant des procédures de dynamique inverse a été mis en place. Dans la première phase de cette étude, la cinématique tridimensionnelle des 3 segments du membre inférieur gauche a été analysée. Il en résulte 3 cinématiques fondamentalement différentes. Avec un modèle type Bottum-Up, la mesure d’efforts distaux est nécessaire. Un robot palmeur a donc été développé, afin de reproduire la cinématique du pied pour chacune des ces pratiques et ainsi permettre une mesure fiable des forces et moments au centre articulaire de la cheville. Ainsi, nous avons quantifié via le modèle, les moments au genou et à la hanche. Ainsi, via le robot nous pouvons quantifier l’effet d’un design de palme sur les efforts subit par l’utilisateur à la cheville, et s’assurer par le modèle que les efforts ne sont pas répercutés sur le genou ou la hanche. En plus de cette étude biomécanique, une analyse de l’activité musculaire a été réalisée sur les principaux muscles moteurs du membre inférieur, pour différentes cinématiques et différents designs de palme. Les résultats nous ont prouvé que le design de la palme a un effet non uniforme sur l’ensemble des muscles, et que pour chacune des pratiques, les demandes musculaires ne sont pas similaires. / The present work had in objective to develop some methods to quantify the joint torque endured by a fin swimmer during is activity for 3 sports (Swimming, Snorkeling, Body-Board). In this way, a model using inverse dynamic methods has been done. During the first step of this study, the 3D kinematic of each activity was mad on the 3 segments of the lower limbs, and this allows defining 3 specifics motions. For a Bottom-Up model, a forces measurement on distal segment is needed to make the calculation. So, a swimming fin robot has been develop to reproduce the foot kinematics for each activity and measure all forces and torques on the ankle joint. By this way, with all this inputs, by the model we can quantify the demands on knee and hip. With this robot, we measure the effect of design modification on muscular request on the joint ankle, and by the model we assure torques are not postpone on knee or hip. In addition to this biomechanical study, a muscular activities study has been realise on the main muscle, and this for different kinematics and different fin blade shapes. The results acknowledge that the fin designs differentiate the effect on specific muscles, and that for each activity the muscular requests are not the same.
92

Le moment américain du roman français (1945-1950) / The American Moment of the French Novel (1945-1950)

Cadin, Anne 19 March 2015 (has links)
De 1945 à 1950, le roman américain impose sa présence dans le paysage littéraire en France et apparaît alors comme un modèle susceptible de renouveler le roman français. Notre thèse est consacrée à ce moment américain du roman français qui s’ouvre à la Libération. La publication de romans américanisés s’accroît et suscite un intérêt constant de la critique, tantôt enthousiasmée, tantôt scandalisée par les conséquences de l’injection de ce « sang neuf » dans les veines du roman français. Les romanciers « légitimes » — Sartre, Des Forêts, Vailland — sont attirés par cette ressource miraculeuse tout autant que les auteurs de romans policiers — Simenon, Malet, Meckert — qui quant à eux cherchent profiter du succès du hard boiled. Simultanément, deux voies d’appropriation du matériau américain se dessinent : les romanciers « sérieux » s’en emparent brièvement, mais passent assez vite de la fascination à la désillusion ; les auteurs de roman policier, quant à eux, transforment un réflexe d’imitation pure en une assimilation féconde. L’ensemble de ce phénomène a été peu étudié. Notre travail a pour objectif de mettre au jour cette voie américaine, empruntée par un vaste groupe de romanciers français, de manière d’autant plus fructueuse qu’ils se servirent du matériau états-unien comme point de départ d’une expérimentation littéraire, mais aussi d’une affirmation de leur propre identité romanesque. En réexaminant la dette du roman français vis à vis de celui venu d’outre Atlantique, nous redonnons à ce fulgurant moment américain qui constitue une transition entre les changements opérés par les avant gardes des années 1920 et la révolution du Nouveau Roman. / From 1945 to 1950, the American Novel promulgates his presence on the French literary scenery and appears as a model beyond compare to renew the French novel. Our thesis is dedicated to this American moment of the French novel that opens at the Liberation. The publication of Americanized novels increases and creates a constant interest from the literary critics, sometimes enthusiast, sometimes outraged by the consequences of this “new-blood” injection in the French novel’s veins. “Legitimate” novelists, such as Sartre, Des Forêts, Vailland, are actually as attracted by this miraculous resource as the detective novel writers, such as Simenon, Malet, Meckert, who are the first willing to benefit from the hard boiled success. Simultaneously, two different ways to seize the American substance are appearing: the “serious” novelists embrace it briefly, but go from fascination to disappointment; as to the detective novel writers, they transform a sheer imitation reflex into fertile assimilation. Yet, all those novels have not often been studied. Our work is aiming to expose this American path, taken by a vast panel of French novelists, in an even more so profitable manner since they used the American material as a starting point, an experimentation opportunity, but also as a way to assert their own fictional identity. By reexamining the French novel’s debt towards the one from across the Atlantic, we hope to confer all its significance to this dazzling American moment that establishes the transition between the changes made by the avant gardes in the twenties and the ones undertaken by the New Novelists.
93

Complexes moment-angle et variétés complexes / Moment-angle complexes and complexe manifolds

Tambour, Jérôme 13 December 2010 (has links)
Le but de cette thèse est d’étendre les résultats de l'article [B-M] sur les relations entre variétés moment-angle et variétés complexes. On s'intéressera ici aux variétés moment-angle issues d'une décomposition simpliciale (et non simplement polytopale) de la sphère. On cherchera ensuite à utiliser la relation entre ces deux types d’objets pour comprendre la topologie de certaines variétés complexes.[B-M] F.Bosio, L.Meersseman, Real quadrics in Cn, complex manifolds and polytopes, Acta Mathematica, 197 (2006), n° 1, 53 -- 127. / The aim of this thesis is to extend the results of the article [B-M] on the relations between moment-angle complexes and complex manifolds. We will focus here on moment-angle complexes defined by a simplicial (not only polytopal) decomposition of the sphere. We will also seek to use the relationship between these two kinds of objects to be understand the topology of several complex manifolds. [B-M] F.Bosio, L.Meersseman, Real quadrics in Cn, complex manifolds and polytopes, Acta Mathematica, 197 (2006), n° 1, 53 -- 127.
94

The transformation behaviour and hot strength of 3CR12 during the continuous casting process

Siyasiya, Charles Witness 20 June 2005 (has links)
Extensive research has been done over the years and has contributed quite a lot to the development of 3CR12 stainless steel. Nevertheless, there is still much to be understood about the behaviour of this steel during its production. One of the problems that are occasionally encountered is the side bulging effect i.e. the unconstrained narrow faces of the strand plastically bulge due to ferrostatic pressure from the liquid core of the strand at high temperatures. In general, this problem is prevalent in ferritic stainless steels as they exhibit a weaker hot strength than austenitic stainless steels. Coupled with side bulging, there is also strand width variation at high temperatures i.e. when the steel is in the ferrite-austenite dual phase region. Both of these dimensional changes to the slab profile create some processing problems in subsequent hot rolling operations when unacceptable width variations are encountered. This work was, therefore, motivated by the requirement to quantify the role that the metallurgical behaviour of this steel plays with regard to the above width variation problem. The research work involved studies of the <font face="symbol">d</font>-ferrite to austenite phase change during continuous cooling (simulating cooling during continuous casting) and the establishment of CCT diagrams, the influence of chemical composition on the austenite start temperature and the hot ductility and hot strength visà-vis the side bulging effect. The casting conditions in the mould are crucial to ensure that the solidification shell is thick enough to withstand the ferrostatic pressure exerted on the unconstrained narrow sides of the strand as it exits from the mould. Therefore, part of the solution lies in the study of the optimisation of the cooling rate, mould flux properties, casting speed, mould taper angle and the chemical composition of this steel, among other factors. Additions of austenite formers, within the specification range of 3CR12, should be favourable for a stronger solidification shell since austenite exhibits superior hot strength to <font face="symbol">d</font>-ferrite. The good hot ductility observed in 3CR12 may also provide a leeway for increasing the secondary cooling rate in order to form a thicker solidification shell soon after emerging from the mould. This may reduce the side bulging effect. This can be achieved without a risk of transverse cracking if the cooling is adjusted carefully. As long as the <font face="symbol">d</font>-ferrite to austenite phase ratio keeps fluctuating due to variations in (i) the chemical composition within the specification range and (ii) the cooling rate in the dual phase region from cast to cast, the strand width variation effect will persist. This is simply because of the effect these have on the ferrite to austenite phase ratios through the differences between the lattice structures of these two phases. Ferrite being less dense than austenite, occupies more volume than austenite, thereby affecting the slab width. The remedy to this problem is to control within stricter chemical composition limits in order to reduce or completely avert this width variation effect. / Dissertation (MSc (Metallurgy))--University of Pretoria, 2006. / Materials Science and Metallurgical Engineering / unrestricted
95

Výpočet aerodynamických charakteristik vozidla s vybočením / Calculation of vehicle aerodynamic characteristics under yaw conditions

Fojtů, Kevin January 2020 (has links)
The diploma thesis focuses on CFD simulation of a vehicle with various geometric modifications and non-zero angle flow. The goal of the work is to evaluate the effect of crosswinds for individual vehicle modifications together with the validation of these data sets with measured data from the wind tunnel. The last part of the thesis contains analysis of the flow field.
96

Měření setrvačných charakteristik těles pro účely matematického modelování dynamiky vozidel / Measurement of Inertia properties of bodies for the purpose of mathematical modeling of vehicle dynamics

Dvořák, Karel January 2008 (has links)
The aim of the diploma thesis is to create a concept of methods that can be used for measurement of important mechanical inertia properties of bodies -- the coordinates of center of gravity and the the moment of inertia tensor, in case we don't have 3D model of these bodies. The thesis divides this problem into several sub-problems and suggests the solutions for each of them. Required equipment was created and measurement was carried out. At the end the measured values are compared with the teoretical ones and accuracy of this method is determined.
97

Měření hmotnostních parametrů vozidel / Measurement of the Weight Parameters of Vehicles

Rücker, Jan January 2012 (has links)
This thesis is the first part deals with methods of determining weight parameters of vehicles. By measuring the position of center of gravity and inertia measurements. In the second part focuses on the measurement of gravity position in a selected group of vehicles Škoda and their comparison between vehicles and comparison with simulation programs PCcrach and Virtual crach.
98

The Truncated Matricial Hamburger Moment Problem and Corresponding Weyl Matrix Balls

Kley, Susanne 31 March 2021 (has links)
The present thesis intents on analysing the truncated matricial Hamburger power moment problem in the general (degenerate and non-degenerate) case. Initiated due to manifold lines of research, by this time, outnumbering results and thoughts have been established that are concerned with specific subproblems within this field. The resulting presence of such a diversity as well as an extensively considered topic si- multaneously involves advantageous as well as obstructive aspects: on the one hand, we adopt the favourable possibility to capitalise on essential available results that proved beneficial within subsequent research. Nevertheless, on the other hand, we are obliged to illustrate major preparatory work in order to illucidate the comprehension of the attaching examination. Moreover, treating the matricial cases of the respective problems requires meticulous technical demands, in particular, in view of the chosen explicit approach to solving the considered tasks. Consequently, the first part of this thesis is dedicated to furnishing the necessary basis arranging the prime results of this research paper. Compul- sary notation as well as objects are introduced and thoroughly explained. Furthermore, the required techniques in order to achieve the desired results are characterised and ex- haustively discussed. Concerning the respective findings, we are afforded the opportunity to seise presentations and results that are, by this time, elaborately studied. Being equipped with mandatory cognisance, the thematically bipartite second and pivo- tal part objectives to describe all the possible values of all the solution functions of the truncated matricial Hamburger power moment problem M P [R; (s j ) 2n j=0 , ≤]. Aming this, we realise a first paramount achievement epitomising one of the two parts of the main results: Capturing an established representation of the solution set R 0,q [Π + ; (s j ) 2n j=0 , ≤] of the assigned matricial Hamburger moment problem via operating a specific algorithm of Schur-type, we expand these findings. We formulate a parameterisation of the set R 0,q [Π + ; (s j ) 2n j=0 , ≤] which is compatible with establishing respective equivalence classes within a certain subset of Nevanlinna pairs and utilise specific systems of orthogonal polynomials in order to entrench novel representations. In conclusion, we receive a para- meterisation that is valid within the entire upper open complex half-plane Π + . The second of the two prime parts changes focus to analysing all possible values of the functions belonging to R 0,q [Π + ; (s j ) 2n j=0 , ≤] in an arbitrary point w ∈ Π + . We gain two decisive conclusions: We identify these respective values to exhaust particular matrix balls 2n K[(s j ) 2n j=0 , w] := {F (w) | F ∈ R 0,q [Π + ; (s j ) j=0 , ≤]} the parameters of which are feasable to being described by specific rational matrix-valued functions and, in this course, enhance formerly established analyses. Moreover, we compile an alternative representation of the semi-radii constructing the respective matrix balls which manifests supportive in further consideration. We seise the achieved parameterisation of the set K[(s j ) 2n j=0 , w] and examine the behaviour of the respective sequences of left and right semi-radii. We recognise that these sequences of semi-radii associated with the respective matrix balls in the general case admit a particular monotonic behaviour. Consequently, with increasing number of given data, the resulting matrix balls are identified as being nested. Moreover, a proper description of the limit case of an infinite number of prescribed moments is facilitated.:1. Brief Historic Embedding and Introduction 2. Part I: Initialising Compulsary Cognisance Arranging Principal Achievements 2.1. Notation and Preliminaries 2.2. Particular Classes of Holomorphic Matrix-Valued Functions 2.3. Nevanlinna Pairs 2.4. Block Hankel Matrices 2.5. A Schur-Type Algorithm for Sequences of Complex p × q Matrices 2.6. Specific Matrix Polynomials 3. Part II: Momentous Results and Exposition – Improved Parameterisations of the Set R 0,q [Π + ; (s j ) 2n j=0 , ≤] 3.1. An Essential Step to a Parameterisation of the Solution Set R 0,q [Π + ; (s j ) 2n j=0 , ≤] 3.2. Parameterisation of the Solution Set R 0,q [Π + ; (s j ) 2n j=0 3.3. Particular Matrix Polynomials 3.4. Description of the Solution Set of the Truncated Matricial Hamburger Moment Problem by a Certain System of Orthogonal Matrix Polynomials 4. Part III: Prime Results and Exposition – Novel Description Balls 4.1. Particular Rational Matrix-Valued Functions 4.2. Description of the Values of the Solutions 4.3. Monotony of the Semi-Radii and Limit Balls of the Weyl Matrix 5. Summary of Principal Achievements and Prospects A. Matrix Theory B. Integration Theory of Non-Negative Hermitian Measures
99

Återbruk av prefabricerade betongbalkar : Hållfasthetsegenskaper av 60 år gamla prefab betongbalkar / Reuse of precast concrete beams

Azar, Kaihan, Abusetta, Seif Abdulhaziz January 2023 (has links)
Inom den här studien undersöks om det är möjligt att återbruka 60 år gamla befintliga balkar som för närvarande används som takbalkar i lagerbyggnaden Viskaholm i Borås. Studien är kopplat till stadsutvecklingsprojektet Västerbro, där det planeras att lagerbyggnaden ska rivas och i stället ska det byggas nya bostäder. Balkarna som undersöks i studien är prefabricerade förspända betongbalkar. Målet med studien är att ta reda på hur balkarna skulle dimensioneras enligt boverkets konstruktionsregler BKR. Därefter kontrollera om balkarnas bärighetskapacitet klarar dagens standarder enligt Eurokoden EKS12/EC2 för högpresterande förspända betongbalkar. Detta med syftet att undersöka om det är möjligt att återbruka 60 år gamla prefabriceradebetongbalkar i nybyggnation. Balkarna var dimensionerade och fabrikgjutna i 1960-talet i enlighet med den svenska byggregeln Byggnadsstadga 1960 (BABS 60). Konstruktionsritningar för balkarna saknas och det finns brist på data för dimensionering av förspända betongbalkar enligt BABS 60. På grund av detta har balkarna dimensionerats i enlighet med Boverkets Kontruktionsregler BKR som gällde i 1995. Boken Byggkonstruktion 3 Betongkonstruktion av Bengt Langesten har används som stöd för dimensionering av balkarna. Sedan har balkarnas bärighetskapacitet beräknats enligt Eurokod 2, för att kontrollera om de klarar dagens bärighetskrav. Resultaten har visat att balkarnas moment- och tvärkraftskapacitet klarar den dimensionerande moment- och tvärkraften. Dock innehåller dessa balkar ingen minimiarmering eftersom det inte  krävdes av BKR. Men enligt Eurokod 2 ska balkarna innehålla minimiarmering även om deras tvärkraftskapacitet klarar den dimensionerande tvärkraften. Enligt resultaten dras slutsatsen att balkarna klarar både den dimensionerande moment- och tvärkraft. Men för att balkarna ska kunna återbrukas idag måste den minimiarmering som krävs enligt EK2 ersättas på något sätt. / This study investigates if it is possible to reuse 60 year old beams that are currently used as roofbeams in the Viskaholm warehouse building in Borås. The study is linked to the urban development project Västerbro, where it is planned to demolish the warehouse building and build new housing instead. The beams that were investigated in the study are precast prestressed concrete beams. The goal of the study is to find out how the beams would have been dimensioned according to Swedish National Board of Housing’s Construction Regulations BKR. Then check whether the- load-bearing capacity of the beams meets today’s standards according to the EurocodeEKS12/EC2 for high-performing prestressed concrete beams. This with the aim of investigating whether it is possible to reuse 60 years old precast concrete beams in new construction. The beams were dimensioned, and factory cast in the 1960s in accordance with the Swedish building code Byggnadsstadga 1960 (BABS 60). Construction drawings for the beams are missing and there is a lack of data for the dimensioning of prestressed concrete beams according to BABS 60. Because of this, the beams have been dimensioned in accordance with Swedish National Board of Housing’s Construction Regulations BKR which applied in 1995. The book Building Construction 3 by Bengt Langesten has been used as guide for dimensioning of the beams. The the load-bearing capacity of the beams has then been calculated according to Eurocode 2, to check whether they meet toady’s load-bearing requirements. The results of the study have shown that the moment and shear force capacity of the beams can bear the maximal moment and shear force. However, these beams do not contain minimum reinforcement because it was not required by BKR. But according to Eurocode 2, the beams must contain minimum reinforcement even if their shear force capacity can bear the maximal shear force. Based on the results, it is concluded that the beams can bear both the maximal moment and shear force. But in order for the beams to be reused today, the minimum reinforcement required by EC2 must be compensated in some way.
100

Flexural performance of FRP reinforced concrete beams

Kara, Ilker F., Ashour, Ashraf 04 1900 (has links)
yes / A numerical method for estimating the curvature, deflection and moment capacity of FRP reinforced concrete beams is developed. Force equilibrium and strain compatibility equations for a beam section divided into a number of segments are numerically solved due to the non-linear behaviour of concrete. The deflection is then obtained from the flexural rigidity at mid-span section using the deflection formula for various load cases. A proposed modification to the mid-span flexural rigidity is also introduced to account for the experimentally observed wide cracks over the intermediate support of continuous FRP reinforced concrete beams. Comparisons with experimental results show that the proposed numerical technique can accurately predict moment capacity, curvature and deflection of FRP reinforced concrete beams. The ACI-440.1R-06 equations reasonably predicted the moment capacity of FRP reinforced concrete beams but progressively underestimated the deflection of continuous ones. On the other hand, the proposed modified formula including a correction factor for the beam flexural rigidity reasonably predicted deflections of continuous FRP reinforced concrete beams. It was also shown that a large increase in FRP reinforcement slightly increases the moment capacity of FRP over-reinforced concrete beams but greatly reduces the defection after first cracking.

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