15 research outputs found
Tomographic PIV behind a prosthetic heart valve
No full textThe instantaneous three-dimensional velocity field past a bioprosthetic heart valve was measured using tomographic particle image velocimetry (PIV). Two digital cameras were used together with a mirror setup to record PIV images from four different angles. Measurements were conducted in a transparent silicone phantom with a simplified geometry of the aortic root. The refraction indices of the silicone phantom and the working fluid were matched to minimize optical distortion from the flow field to the cameras. The silicone phantom of the aorta was integrated in a flow loop driven by a piston pump. Measurements were conducted for steady and pulsatile flow conditions. Results of the instantaneous, ensemble and phase averaged flow field are presented. The three-dimensional velocity field reveals a flow topology, which can be related to features of the aortic valve prosthesis
Global Doppler frequency shift detection with near-resonant interferometry
No full textThe recent development in measuring 2D Doppler shift distributions for flow velocimetry using the dispersive properties of atomic line filters is presented. On the basis of velocity field measurements on a subsonic jet flow and a tip vortex flow in a medium-sized wind tunnel, the technique was assessed. Atomic line filters near a resonant transition combine imaging capabilities with a sharp frequency cutoff and an associated region of strong anomalous dispersion. While conventional Doppler global velocimetry relies on the absorption of the filter to convert frequency shifts to intensity variations, near-resonant interferometry uses its dispersion to detect frequency shifts as phase changes in an interference pattern. In the present setup, an iodine vapor cell in an imaging Michelson interferometer is used. With the illuminating laser frequency tuned near a resonant transition, the cell's dispersion converts the frequency content of the field of view into a distortion of the carrier-fringe pattern recorded at the image plane of the interferometer. The phase distribution in the fringe images is reconstructed by filtering the individual images with a 2D Gabor filter pair tuned to the spatial frequencies of the basic carrier-fringe pattern. The post-processing is concluded with subsequent phase-unwrapping and subtraction of the carrier reference fringe phase. The method and the setup were demonstrated and calibrated experimentally on a rotating disc. The capability of the technique to operate in a real experimental environment was validated in a free subsonic jet and a tip vortex flow behind a wing section in a medium-sized wind tunnel facility. The measurements were found to be in generally good agreement with the theoretically predicted system characteristics and the reference measurements. As with other Doppler global techniques, the stability of the pulsed laser system and the secondary scattering in the test volume were identified as the main error source
Global Doppler frequency shift detection with near-resonant interferometry
No full textISSN:0723-4864ISSN:1432-1114ISSN:1432-111
Maurice Maeterlinck, an author in the cinema of the 1910s and the 1920s: history, sociology and aesthetic
No full textSi l’œuvre littéraire de Maurice Maeterlinck suscite nombre de recherches, ses activités dans le domaine du cinéma sont moins connues et moins étudiées. La présente thèse, qui s’appuie sur les concepts de la sociologie de Pierre Bourdieu, entend combler une lacune en analysant la trajectoire de l’auteur dans le champ cinématographique pendant les années 1910 et 1920, c’est-à-dire la période où il manifeste le plus d’intérêt pour le cinéma. L’étude comprend trois analyses. La première concerne le point de vue de Maurice Maeterlinck, son entrée et son déplacement dans le champ cinématographique. L’auteur consacré dans son champ d’origine développe, dans le nouveau champ investi, des produits dérivés orientés vers le public élargi et diversifié. La deuxième analyse concerne les transformations du champ cinématographique et le point de vue des autres agents, en particulier celui des maisons de production et de distribution. Celles-ci insèrent les adaptations de l’auteur dans une série de produits plus ou moins standardisés, qui leur permettent de se situer dans le champ. La troisième analyse concerne quelques films et projets de films datant des années 1910 et 1920, liés aux œuvres littéraires de Maurice Maeterlinck, comme The Blue Bird (Maurice Tourneur, 1918). Aussi bien les composantes externes (par exemple, la mise en place du projet, la production ou l’exploitation) que les composantes internes (par exemple, la mise en scène ou l’éclairage) sont les indicateurs de la position de l’auteur et les indicateurs du fonctionnement du champ dans son ensemble. / The researches on the literary works of Maurice Maeterlinck are numerous but his activity in the cinema is less known and less studied. The PhD thesis is based on the concepts of the sociology of Pierre Bourdieu ;its purpose is to bring new information by analyzing the trajectory of the author in the cinematic field during the 1910s and the 1920s, when he is the most interested in the cinema. The study includes three analyses. The first one concerns Maurice Maeterlinck's point of view, his entrance and his movement in the cinematic field. The author who is recognized in his first field develops in the new invested field several products who are directed to the widened and diversified public. The second analysis concerns the transformations of the cinematic field and the point of view of the other agents, e.g. the houses of production and distribution. These houses insert the adaptations of the author into a series of more or less standardized products, which allow them to be situated in the field. The third analysis concerns some films and projects of films of the 1910s and the 1920s, adapted from the literary works of Maurice Maeterlinck (e.g. The Blue Bird, Maurice Tourneur, 1918). The external components (the organization of the project, the production or the exploitation) and the internal components (the direction or the lighting) indicate how the author is situated and how the field is organized.Doctorat en Information et communicationinfo:eu-repo/semantics/nonPublishe
Blade tip vortex detection in maneuvering flight using the Background Oriented Schlieren (BOS) technique
No full textThe background oriented Schlieren (BOS) technique was used to visualize the blade tip vortices of a Eurocopter
AS532UL Cougar helicopter in maneuvering flight. The test program included a wide range of maneuvers covering a
large part of the flight envelope such as hover, fast forward flight, flare maneuvers and high speed turns. For selected
flight conditions, the aerodynamic results are presented here. It is shown that with the reference-free BOS method,
the detection of vortex filaments up to vortex ages of 540° is possible. The visualization of the vortex system
is used to detect aerodynamic phenomena like blade vortex interactions (BVI), vortex airframe interactions and the
occurrence of smooth sinuous disturbances. A detailed description of the applied reference-free BOS setup is given
and the suitability of different natural backgrounds for the BOS method is analyzed
Exploring Gravitational Waves Recordings with Machine Learning Techniques
No full textThe study of Gravitational Waves (GWs) opened a new window of possibilities to improve our understanding of the Universe. GWs provide suitable astronomical messengers for studying events that were not possible before through electromagnetic radiation, or in other cases complementing their observations. Ground-based interferometers like LIGO have been recording multiple GW events since the first detections in 2015. Despite the success of Earth-based observatories, the space limitations and noise sources on Earth point toward the need of building a spaceborne interferometer. The Laser Interferometer Space Antenna (LISA) is a planned project that will provide us with such a detector and will allow gaining access to lower frequency bands and more types of GW sources. To make the most out of LISA’s strengths, it is important to identify and develop alternative data analysis tools which are more appropriate for low latency searches of GWs than the current ones in use. Machine Learning techniques are a promising candidate since they can provide high accuracies, higher speeds, and a lower computational cost. Therefore, they can be used for the development of Low Latency Detectors (LLD) of GWs, which will be used to analyze the LISA recordings. I propose to build a prototype LLD by using a Sliding Window Algorithm, which makes use of Convolutional Neural Networks (CNNs) as its classification mechanism. To implement the LLD, I first create datasets composed of synthetic GW recordings of two different GW source types: Galactic Binaries (GBs) and Merging Blackhole Binaries (MBHBs). Then, I transform these recordings originally represented only in the time domain, into the frequency domain, and the time-frequency domain and train two different ML architectures (CNNs and Fully-Connected Neural Networks) using both the original and the transformed data. A performance evaluation is done to select the best combination of ML architecture and domain representation for solving the detection task. The chosen combination is then used as the classifier mechanism of the LLD acting in windows of five days duration. The LLD is tested on one-year-long recordings with different levels of noise. The analysis suggests that the time-frequency domain representations offer the most promising results for detecting both types of sources (GBs and MBHBs) reaching high accuracies in recordings with low to moderate signal-to-noise ratio (SNR).Applied Geophysics | IDEA Leagu
The cisanthropic figurine - Liminal humanity and affective contagion in animation cinema
No full textThis thesis aims at answering an apparently simple question: How come "cartoony" characters always seem to be able to trigger better affective responses than more realistic ones (therefore avoiding the uncanny valley). By linking classical animated cartoons to their print cartoon ancestors, the author is able to call upon the array of studies on caricature perception to build a new understanding of animated character design, summed up into a type of character called cisanthropic figurine
