Academic literature on the topic 'Chambre à bulles'
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Journal articles on the topic "Chambre à bulles"
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Harigel, Gert G. "Nucléation dans les chambres à bulles." La Houille Blanche, no. 2 (March 1988): 103–20. http://dx.doi.org/10.1051/lhb/1988007.
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Oussou, Yousra, Jihad Raoui, Siham Hallab, Latifa Oukerraj, Mohamed Cherti, Kaoutar Imrani, Nabil Moatassim Billah, and Nassar Ittimade. "HYDATIC CARDIAC SYST: AN EXCEPTIONAL LOCATION." International Journal of Advanced Research 9, no. 09 (September 30, 2021): 122–27. http://dx.doi.org/10.21474/ijar01/13384.
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Hydatid cyst is a parasitic disease endemic in different regions of the world. Cardiac localization represents only 0.5 to 2% of all attacks, characterized by clinical, paraclinical and especially radiological polymorphism. Its spontaneous development is serious because of the risk of endocavity rupture. The diagnosis is facilitated by means of non-invasive imaging, in particular echocardiography, thoracic computed tomography and magnetic resonance imaging. Given the lack of alternative treatment options, cystectomy and pericystectomy are the only surgical techniques capable of offering chances of recovery with acceptable morbidity and mortality. Antiparasitic treatment comes in addition to surgery. Eradication of hydatid disease mainly involves effective collective and individual preventive measures. We present a clinical case of a 54-year-old patient who presented with asthenia followed by precordial pain, who has a normal EKG and chest x-ray. Transthoracic echocardiography (TTE) a mass that bulges in the lateral aspect of the left heart chambers. The thoracic tomodensitometry objectified a cystic image which bulges in the left cardiac chambers suggesting a cardiac hydatid cyst. A hypereosinophilia was objective in the biological assessment. The patient was sent to the cardiovascular surgery department for surgery. We present a clinical case of a 54-year-old patient who presented with asthenia followed by precordial pain, who has a normal EKG and chest x-ray. Transthoracic echocardiography (TTE) a mass that bulges in the lateral aspect of the left heart chambers. The thoracic tomodensitometry objectified a cystic image which bulges in the left cardiac chambers suggesting a cardiac hydatid cyst. A hypereosinophilia was objective in the biological assessment. The patient was sent to the cardiovascular surgery department for surgery. We present a clinical case of a 54-year-old patient who presented with asthenia followed by precordial pain, who has a normal EKG and chest x-ray. Transthoracic echocardiography (TTE) a mass that bulges in the lateral aspect of the left heart chambers. The thoracic tomodensitometry objectified a cystic image which bulges in the left cardiac chambers suggesting a cardiac hydatid cyst. A hypereosinophilia was objective in the biological assessment. The patient was sent to the cardiovascular surgery department for surgery. Transthoracic echocardiography (TTE) a mass that bulges in the lateral aspect of the left heart chambers. The thoracic tomodensitometry objectified a cystic image which bulges in the left cardiac chambers suggesting a cardiac hydatid cyst. A hypereosinophilia was objective in the biological assessment. The patient was sent to the cardiovascular surgery department for surgery. Transthoracic echocardiography (TTE) a mass that bulges in the lateral aspect of the left heart chambers. The thoracic tomodensitometry objectified a cystic image which bulges in the left cardiac chambers suggesting a cardiac hydatid cyst. A hypereosinophilia was objective in the biological assessment. The patient was sent to the cardiovascular surgery department for surgery.
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Yang, Yi, Lei Liu, Xiang Long Li, and Di Liu. "The Experimental Research Based on SHPB Test of the Rocks Plastic Damage Cumulative Effect." Advanced Materials Research 347-353 (October 2011): 1523–29. http://dx.doi.org/10.4028/www.scientific.net/amr.347-353.1523.
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This article to research through SHPB test of the rocks in the plastic damage under the cumulative effects. This paper selects bullets for the diameter steel rods, the bullet hit by a fixed speed when fixed, selects the two kinds of circumstances for gas chamber pressure such as P = 0.6 MPa and P = 0.7 MPa. It is concluded that the main important conclusions： Test specimen didn’t reach the effect for ,Limestone which is no initial damage to absorb lesser energy, as the same time the internal stones damage were also lower, and with the impact times accumulation, limestone damages degree were increasing, eventually make the specimen destroy. The internal of rock specimens are low destroy, when has the same effect, specimens receiving the maximum stress by lesser,when the internal damage can cumulative increases to certain value, and is suffered the same stress effect, finally the maximum stress will be decreased. For rocks material at repeated impact as low speed ,under this action show the obvious plastic damage accumulation effect
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Singh, B. P. "Suicide by homemade firearm." Medicine, Science and the Law 47, no. 4 (October 2007): 345–49. http://dx.doi.org/10.1258/rsmmsl.47.4.345.
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This paper presents a unique case of suicide committed by a homemade firearm. A 56-year-old man shot himself with a homemade firearm capable of accommodating and firing 8 mm rifle ammunition. The victim put the muzzle of the weapon on the right side of his skull and died immediately after firing. The overall and barrel lengths of the firearm were 29.5 cm and 17.5 cm respectively. The barrel was oversized for the 8 mm rifle bullet having an average muzzle and breech diameter of .423in. (9.53 mm) and .489in. (11.02 mm) respectively. The cartridge case recovered from the chamber was swollen due to the oversized non-standard chamber. The bullet recovered was deformed and elongated. The injury and bullet track present on the victim's head were unique in nature. With respect to the weapon and ammunition, this study represents an unusual suicide. The findings will be helpful to the medico-legal experts, forensic scientists and pathologists.
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Liscio, Eugene, and Bianca Ledo. "Defining Patterns and Behaviours of Forward Spatter Gunshot Misting." Forensic Sciences 1, no. 2 (August 9, 2021): 86–101. http://dx.doi.org/10.3390/forensicsci1020009.
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The purpose of this research was to study forward-spatter misting patterns by shooting a firearm through a chamber of blood encased in ballistic gel to determine if there is a relationship between bloodstain pattern size as a function of distance and orientation. There is a lack of research on forward spatter, blood travelling in the direction of a bullet, as most studies focus on back spatter, blood travelling in the opposite direction of a bullet. A bullet was fired through ballistic gel containing a blood chamber, depositing bloodstains onto a large sheet of butcher paper as the target surface. In total, there were 34 trials. The distances observed were 10, 20, 40, and 80 cm, the angles tested were 30°, 60°, and 90°. The orientation between the ballistic gel and paper target varied. A criterion was established to observe the overall area and symmetry of the bloodstain patterns. Statistical analyses indicated a negative linear relation relationship between the bloodstain pattern size and the paper’s angle and distance (R2 = 0.78) and the vertical symmetry of the bloodstain (R2 = 0.87). The orientation between the ballistic gel and paper target can impact the bloodstain pattern’s symmetry and size.
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Pawitan, Yudi, and Gabriel Isheden. "Resolving Zeckhauser’s paradox." Theory and Decision 88, no. 4 (December 17, 2019): 595–607. http://dx.doi.org/10.1007/s11238-019-09740-5.
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AbstractZeckhauser’s paradox has puzzled and entertained many rationality enthusiasts for almost half a century. You are forced to play a Russian Roulette with a 6-chamber revolver containing either (A) two bullets, or (B) four bullets. Would you pay more to remove the two bullets in (A) than you would to remove one in (B)? Most would say yes, but rational considerations based on the classical utility theory suggest you should not. We discuss a possible solution within the classical framework, by explicitly stating and accounting for more detailed preferences in terms of fewer bullets and smaller debt. To a large extent, the paradox arises due to a surreptitious trespassing of Savage’s Small-World utilities implied by a limited set of preferences to govern a larger world containing potentially conflicting preferences. To avoid logical issues associated with death in the roulette, we also describe a non-fatal game-show version, where you choose one box out of six that could be either empty or contain prize money. Here, the paradox arises when you pay from the prize money, but not when you pay from your own money. In summary, the paradox provides a useful lesson about the normative role of the utility function as a rational guide for our decisions and preferences.
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Brogliatti, G., F. Garcia Migliaro, R. Cavia, G. Larraburu, and A. Albrecht. "12 CASA PARAMETERS OF FRESH BULL SEMEN COLLECTED BY ARTIFICIAL VAGINA OR ELECTROEJACULATION IN ARGENTINA." Reproduction, Fertility and Development 17, no. 2 (2005): 156. http://dx.doi.org/10.1071/rdv17n2ab12.
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The latest entry in the field of semen evaluation is computer assisted semen analysis (CASA). Its greatest advantages are elimination of the subjective nature of routine semen evaluation and the addition of detailed motion analysis unquantifiable by visual examination. The objective of this study was to evaluate CASA motility parameters of fresh bull semen collected by artificial vagina (AV) or electroejaculation (EE) from a total of 56 beef different bulls. Semen samples from a total of 45 beef bulls were collected by AV from winter to the end of spring (740 collections), and from 11 beef bulls by EE (120 collections) in the same period. First and second AV collections were analyzed as individual data. EE collection was performed only one. Means and standard deviations for each characteristic were calculated, compared, and statistically analyzed. A sample of the collection was diluted 1:20 in a semi-defined semen extender (Andromed, Minitüb, Tiefenbach, Germany) and held in a glass tube at 36°C for 5 min before analysis. The sample was loaded into 20-μm chambers, and six microscope fields from each chamber were analyzed. The following sperm motility parameters were determined with the Ceros 12.1 sperm analyzer (Hamilton Thorne Biosciences, Inc., Beverly, MA, USA) on at least 1000 spermatozoa:concentration (CONC), velocity average path (VAP), velocity straight line (VSL), curvilinear velocity (VCL), amplitude lateral head (ALH), beat cross frequency (BCF), straightness (STR), linearity (LIN), and percentage of rapid or statics cells. There were no significant differences (P > 0.05) in VAP, VSL, VCL, ALH, STR, LIN, and the percentage of rapid and static cells of semen collected by AV or EE. The concentration (sperm/mL) of the AV-collected sperm was significantly higher than for the sperm collected by EE. Results from the analysis indicate that semen collected by artificial vagina have motility characteristics similar to those collected by electroejaculation. More research needs to be done to evaluate motility parameters of frozen/thawed semen collected by electroejaculation and by artificial vagina. This research was supported by Centro Genético Bovino de EOLIA sa Argentina.
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Sielicki, Piotr W., Adrian Pludra, and Michał Przybylski. "Experimental measurement of the bullet trajectory after perforation of a chambered window." International Journal of Applied Glass Science 10, no. 4 (July 11, 2019): 441–48. http://dx.doi.org/10.1111/ijag.13478.
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Mieno, Tetsu, Kazuki Ookouchi, Kazuhiko Kondo, Susumu Hasegawa, and Koichi Kurosawa. "Production of Carbonaceous Molecules by the Impact Reaction in Nitrogen Gas by Use of a Gas-Gun." Advanced Materials Research 1117 (July 2015): 31–34. http://dx.doi.org/10.4028/www.scientific.net/amr.1117.31.
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In order to investigate impact production of carbonaceous molecules by asteroid’s impact, simulation experiment is carried out using a 2-stage light gas-gun. A small polycarbonate bullet is injected into a pressurized chamber with 1 atm of nitrogen gas, to collide with a target. Strong emissions of CN and C2 molecules are measured, and CN rotational temperature is evaluated. In the produced soot, production of fullerenes, nanotubes, metal-encapsulated particles, balloon-like nano-carbons and amino acids is confirmed.
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Westbrook, Christopher David, Robin J. Hogan, and Anthony J. Illingworth. "The Capacitance of Pristine Ice Crystals and Aggregate Snowflakes." Journal of the Atmospheric Sciences 65, no. 1 (January 1, 2008): 206–19. http://dx.doi.org/10.1175/2007jas2315.1.
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Abstract A new method of accurately calculating the capacitance of realistic ice particles is described: such values are key to accurate estimates of deposition and evaporation (sublimation) rates in numerical weather models. The trajectories of diffusing water molecules are directly sampled, using random “walkers.” By counting how many of these trajectories intersect the surface of the ice particle (which may be any shape) and how many escape outside a spherical boundary far from the particle, the capacitances of a number of model ice particle habits have been estimated, including hexagonal columns and plates, “scalene” columns and plates, bullets, bullet rosettes, dendrites, and realistic aggregate snowflakes. For ice particles with sharp edges and corners this method is an efficient and straightforward way of solving Laplace’s equation for the capacitance. Provided that a large enough number of random walkers are used to sample the particle geometry (∼104) the authors expect the calculated capacitances to be accurate to within ∼1%. The capacitance for the modeled aggregate snowflakes (C/Dmax = 0.25, normalized by the maximum dimension Dmax) is shown to be in close agreement with recent aircraft measurements of snowflake sublimation rates. This result shows that the capacitance of a sphere (C/Dmax = 0.5), which is commonly used in numerical models, overestimates the evaporation rate of snowflakes by a factor of 2. The effect of vapor “screening” by crystals growing in the vicinity of one another has also been investigated. The results clearly show that neighboring crystals growing on a filament in cloud chamber experiments can strongly constrict the vapor supply to one another, and the resulting growth rate measurements may severely underestimate the rate for a single crystal in isolation (by a factor of 3 in this model setup).
Dissertations / Theses on the topic "Chambre à bulles"
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Puibasset, Joël. "Etude de suspensions de gouttelettes de fréon en surchauffe en vue de la réalisation d'un détecteur de matière cachée galactique." Paris 6, 2000. http://www.theses.fr/2000PA066390.
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Chen, Simon. "Test et calibrations technologiques avec PICO-0.1 pour les futurs détecteurs de chambre à bulle de matière sombre de PICO." Thesis, 2020. http://hdl.handle.net/1866/24366.
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Parmi les douzaines d’expériences qui visent à découvrir la matière sombre, l’expérience de détection directe PICO utilise des détecteurs à liquide surchauffé comme moyen pour s’y prendre. La chambre à bulle PICO-40L remplie de C3F8, présentement située dans le laboratoire sous-terrain SNOLAB, est en cours de test en vue d’une recherche aveugle de WIMP (Weakly Interacting Massive Particle) d’une durée de 1 an. Pour assurer la stabilité du détecteur pendant les périodes de préparation et pendant l’acquisition de données, un logiciel de surveillance a été écrit. Un moyen fiable de surveiller les paramètres importants du détecteur et d’envoyer des alarmes en cas d’urgence joue un rôle important à non seulement au succès de PICO-40L, mais aussi au développement du futur détecteur PICO-500.
Située à l’Université de Montréal, la chambre à bulle PICO-0.1 a été conçue afin de calibrer les nombreux événements de fond qui se présentent dans ce type de détecteur. De plus, cette chambre à bulle a été utilisée comme première tentative au monde de mesurer la diffusion Thomson sur un noyau d’atome en exposant le détecteur rempli de C3F8 à une source de gamma produite par la réaction 19F proton à alpha et gamma 16O à l’aide d’un faisceau de protons crée par l’accélérateur de particules de l’Université de Montréal. Ce type d’interaction s’avérera à un événement de fond important pour les expériences de détection directe de matière sombre à bas seuil.Amongst the dozens of experiments aiming to be the first to claim a dark matter signal, PICO is a direct dark matter detection experiment that utilizes superheated liquid detectors as a means of doing so. The latest C3F8 filled PICO-40L bubble chamber currently located in the SNOLAB underground laboratory is under testing to prepare for a 1 live-year blinded WIMP (Weakly Interacting Massive Particle) search. To ensure the stability of the detector during both the testing and the data acquisition phases, a monitoring software was coded. A reliable way to monitor all the parameters and to send alerts accordingly plays an important role in not only the success of PICO-40L, but also the development of the future larger-scale PICO-500 detector. PICO-0.1 is a test bubble chamber located at the University of Montreal that was built to calibrate for the numerous background events that can occur in this kind of technology. This test chamber was also used as a world’s first attempt to measure the coherent (Thomson) photon scattering onto a nucleus by exposing the C3F8 filled detector to a gamma source produced by the 19F proton to alpha and gamma 16O reaction using a proton beam created by the University of Montreal particle accelerator. This kind of interaction will prove to be a significant background for future sub-keV direct dark matter detection experiments.
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Tardif, Frédéric. "Direct detection of dark matter with the PICO Experiment and the PICO-0.1 calibration chamber." Thèse, 2018. http://hdl.handle.net/1866/22214.
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Laurin, Mathieu. "Recherche de la matière sombre à l’aide de détecteurs à liquides surchauffés dans le cadre de l’expérience PICO/Picasso." Thèse, 2016. http://hdl.handle.net/1866/18480.
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La matière sombre compte pour 85% de la matière composant l’univers et nous ne savons toujours pas ce qu’elle est. Depuis plusieurs années, l’expérience Picasso, maintenant devenue l’expérience PICO, tente d’élucider ce mystère. Les fréons de la famille des CXFY sont utilisés comme cibles de choix dans les détecteurs à liquides surchauffés de l’expérience PICO. Situés à SNOLab, en Ontario, ces détecteurs font parties des plus performant de la recherche de la matière sombre. Lors d’interactions de particules avec le liquide en surchauffe, un changement de phase est induit par le dépôt d’énergie engendré par l’interaction. Les bulles créées par l’évènement sont alors détectées par différents capteurs afin de déterminer le type d’interaction qui a eu lieu.
Dans ce travail seront présentés les détecteurs à liquides surchauffés dans le cadre de la recherche de la matière sombre. Principalement, nous y verrons trois types de détecteurs utilisés par les expériences PICO et Picasso. Le principe de
fonctionnement de chacun des détecteurs sera exposé en premier lieu ainsi que leur fabrication, puis leur mode d’opération et l’analyse des données. Les méthodes de calibration seront par la suite expliquées pour terminer avec une description des résultats obtenus démontrant la performance de ce type de détection.Dark matter makes up 85% of the matter content of the universe and we still don’t know what it is made of. The Picasso experiment, now named PICO, has been searching for it for several years with the use of superheated liquid detectors. Following the interaction of a particle with a superheated liquid freon of the CXFY family, a bubble is formed through a phase change and is detected with several types of sensors, telling us about the nature of the event. Located at SNOLab, in Ontario, these detectors produce some of the best results in the field. The present work will go through three types of superheated liquid detectors. A full description of the working principles will be presented for each of them. In addition, the fabrication, the operation mode and the data analysis will be shown. Detector calibration techniques will then be presented with different particle sources. Finally, the most recent results will be discussed, demonstrating the performance of the superheated liquid detector technique.
Books on the topic "Chambre à bulles"
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Barger, Ralph "Sonny." 6 Chambers, 1 Bullet: A Novel. HarperCollins Publishers, 2013.
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Lott, Marie Sumner. Creating “Progressive” Communities through Programmatic Chamber Music. University of Illinois Press, 2017. http://dx.doi.org/10.5406/illinois/9780252039225.003.0005.
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This chapter examines three programmatic works for strings, each with a different relationship to the cultural and political scene of its day: George Onslow's string quintet “The Bullet” deals with a hunting accident; Niels Gade's string quartet “Willkommen und Abschied” (Welcome and departure) interprets a Goethe poem; and Bedřich Smetana's string quartet “From My Life” provides a politically charged autobiography in tones. In all three cases, the composer has addressed a particular group of performers or listeners by using musical style and the written word to create a narrative that would resonate with a shared experience or identity. As such, these three works demonstrate the range of possibilities for programmaticism throughout the nineteenth century, as well as different points along the spectrum of depiction, from “characteristic” works that narrate a series of events with mimetic devices to more abstract works that attempt to translate a poetic ideal into musical sounds.
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Marietta, Morgan, and David C. Barker. One Nation, Two Realities. Oxford University Press, 2019. http://dx.doi.org/10.1093/oso/9780190677176.001.0001.
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Is climate change real? Does racism still determine who gets ahead? Is sexuality innate? Do immigration and free trade help or hurt the economy? Does gun control reduce violence? Are false convictions common? On these and many other basic questions of fact, Americans are deeply divided. How did this happen? What does it mean? And is there anything we can do about it? Drawing upon several years of original survey data and experiments, Marietta and Barker reach a number of enlightening and provocative conclusions. Among them is that dueling fact perceptions are not so much a result of hyper-partisanship or media propaganda as they are of simple value differences and deepening distrust of authorities. The educated—on both the Left and Right—carry the biggest guns and are the quickest to draw. These duels foster social contempt—even in the workplace—and they warp the electorate. And finally, the remedies that have been proposed don’t seem to holster many weapons; in fact, they add bullets to the chamber in some cases. Marietta and Barker’s pessimistic conclusions will challenge idealistic reformers.
Book chapters on the topic "Chambre à bulles"
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Muenzler, W. Stanley. "Lens replacement in pseudophakic bullous keratopathy: iris-sutured posterior chamber lenses." In Corneal Surgery, 413–14. Elsevier, 2009. http://dx.doi.org/10.1016/b978-0-323-04835-4.50052-5.
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Doherty, Terrence J., and Jonathan H. Lass. "Anterior chamber-type intraocular lens replacement during penetrating keratoplasty for pseudophakic bullous keratopathy." In Corneal Surgery, 407–11. Elsevier, 2009. http://dx.doi.org/10.1016/b978-0-323-04835-4.50051-3.
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Preston, Katherine K. "“The Life of a Musician”." In George Frederick Bristow, 3–19. University of Illinois Press, 2020. http://dx.doi.org/10.5622/illinois/9780252043420.003.0002.
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Bristow’s first teacher was his father, William Richard Bristow; he later studied with George Macfarren, Ole Bull, and others. During the 1840s he performed professionally in theater orchestras (Park, National, and Olympic), joined the Philharmonic Society (1842), and soon began performing in the orchestra (1843). Important mentors included William Musgrif and George Loder. In the same decade he wrote songs, piano pieces, and chamber works, as well the Concert Overture (1845) and Sinfonia No. 1 (1847). By mid-decade he was thoroughly immersed in the thriving performance scene of the city: as an ensemble member, conductor, and solo violinist or pianist.
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Brister, Wanda, and Jay Rosenblatt. "The Lady Composer Steps Out." In Madeleine Dring, 115–49. Liverpool University Press, 2020. http://dx.doi.org/10.3828/liverpool/9781949979312.003.0006.
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Dring’s early career is traced through her commissions for BBC radio and television broadcasts, of which the most significant is The Fair Queen of Wu, a ballet for singers and chamber ensemble with choreography by Felicity Gray. During these years, her first publications appeared, with an emphasis on piano music (for solo piano and two pianos) and her Three Shakespeare Songs. Dring’s music was also performed in recitals, including her recently published piano works and a selection of her songs (published and unpublished). The most favorable reviews are found for her Festival Scherzo (“Nights in the Gardens of Battersea”), written to commemorate the Festival of Britain. Also discussed is her one-act opera, Cupboard Love, the music written for the Christmas plays produced by Angela Bull’s Cygnet Company, and her first performance as a singer at the RCM’s Union “At Home.” A fine example of Dring’s cabaret style is found in the discussion and analysis of her song, “The Lady Composer.” In her personal life, the chapter documents her marriage to Roger Lord, his career as a musician (principal oboe in the London Symphony Orchestra for thirty-three years), and the birth of her son, Jeremy.
Conference papers on the topic "Chambre à bulles"
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Adams, Mark, and Eric J. Barth. "A Compressible Fluid Power Dynamic Model of a Liquid Propellant Powered Rifle." In ASME 2004 International Mechanical Engineering Congress and Exposition. ASMEDC, 2004. http://dx.doi.org/10.1115/imece2004-59620.
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This paper presents a dynamic model of the interior ballistics of an experimental liquid propellant-powered rifle. The liquid propellant-powered rifle described utilizes a misture of Hydroxyl Ammonium Nitrate (HAN) and hydrocarbon fuel to replace gunpowder typically used in such firearms. The motivation for such a development is to discard the need for a shell casing whereby carrying only propellant and bullets will reduce both the mass and volume per shot carried by the soldier. A first-principles dynamic model of the interior ballistics is derived as a compressible fluid power problem with the chemical liberation of heat within the chamber modeled via a condensed-phase reaction rate law. The model is used to predict the overall performance in terms of ballistic kinetic energy as well as draw design insight regarding the role of friction, chamber geometry, and the profile of chamber pressure with respect to time. Simulation results are presented as well as preliminary experimental results from a proof-of concept device.
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Mendes, A. C., L. M. A. Paredes, F. A. S. Gil, and J. R. Chaplin. "Small-Scale Model Tests of a Rubber-Tube Wave Energy Converter With Pneumatic Power Take-Off." In ASME 2014 33rd International Conference on Ocean, Offshore and Arctic Engineering. American Society of Mechanical Engineers, 2014. http://dx.doi.org/10.1115/omae2014-23452.
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The paper deals with a relatively new concept in wave-energy conversion systems: the Anaconda. This device consists basically of a distensible tube, made out of rubber material, which interacts with the incident waves in order to convey the absorbed energy to some form of power take-off (PTO). In the present case, the bulges inside the rubber tube drive a slug of water towards a vertical shaft referred to as a chimney. The oscillations of the water column inside the chimney induce a pressure oscillation in the pneumatic chamber above that activates an air-turbine. The Anaconda device has been studied extensively by experimental and theoretical means. However, so far, the pneumatic PTO for this device has only been examined within restrictive linear conditions. This study is about a series of 1:100 scale model tests of a freely floating Anaconda in a wave flume, under deep and intermediate water regular waves, for a device equipped with a non-linear PTO. In the model, the pneumatic chamber communicates with the atmosphere through an orifice. Three calibrated orifices of different diameters have been tested. The pressure across the orifice is determined from measurements taken of the amplitude of water column oscillations in the system, by applying Bernoulli’s law. These properties are subsequently used for calculating the power captured from the incident waves. Estimates of power output and energy capture width are presented, as functions of wave frequency, while the device interacts with linear and second-order waves. Our estimates are finally extrapolated to predict prototype performance.
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Mendes, A. C., F. P. Braga, L. M. A. Paredes, and J. R. Chaplin. "Performance Assessment of the Anaconda WEC in Regular Waves at 1:50 Model Scale." In ASME 2017 36th International Conference on Ocean, Offshore and Arctic Engineering. American Society of Mechanical Engineers, 2017. http://dx.doi.org/10.1115/omae2017-61478.
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The Anaconda WEC belongs to a new generation of wave-energy converters that are currently on their way to reach a pre-commercial stage. It consists of a long rubber tube that is designed to float head to waves. The tube is filled with water and its stern is connected to a power take-off system (PTO). As a result of the interactions with the incoming ocean waves, the tube conveys internal pressure bulges whose intensity grows in the direction of the PTO. A pneumatic system is considered herein, in which electrical energy can be produced from a turbo-generator set. The present research focuses on the performance assessment of a free-floating Anaconda model with air-flow PTO. The results of a series of tests with a 1:50 scale physical model in wave-tank are presented and discussed. In this model the pneumatic chamber connects with the atmosphere through an orifice plate. Several calibrated orifices of different diameters have been tested. The tests were undertaken in regular waves that translate to waves of 7 to 14 seconds in full-scale. Pressure in the pneumatic chamber and the water-column oscillations in the shaft were monitored. They provide estimates of the extracted power and energy capture efficiency of the system. One of the aims of the study is to account for the effects of compressibility on the power output of the system, as well as properly assessing the impact of scale effects upon performance estimates. The results, presented as a function of the wave frequency, are ultimately used to predict prototype performance.
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Matthiesen, Gunnar, Hubertus Murrenhoff, Johannes Storz, and Alexander Braun. "Pressure Control for a Hot Gas Bulge Test Using Parallel On-Off Valves." In ASME/BATH 2017 Symposium on Fluid Power and Motion Control. American Society of Mechanical Engineers, 2017. http://dx.doi.org/10.1115/fpmc2017-4239.
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Weight reduction is an ongoing trend in multiple industries. Especially in the mobility sectors, hot forming of sheet metal parts has become an alternative production process for high strength components. New material concepts, e.g., boron-manganese steels, enable the design of lighter parts at equivalent or even higher strength. During the preliminary process development phase detailed knowledge of the thermo-mechanical material properties of these sheet metals is required at elevated temperatures and high strain rates. Since hot tensile tests can only be evaluated up to comparably low strains, new test designs are needed to supply material parameters at elevated temperatures and higher strain rates. Therefore, the hot gas bulge test has been developed, that allows for such test conditions. In this paper, first the concept of the hot gas bulge test and the developed test bench are described. Opposed to standardized bulge tests, which use hydraulic oil as forming medium, the newly designed test uses gas as medium to account for the hot stamping conditions, i.e., temperatures of up to 950°C. As the forming speed has an increasing influence on the material behaviour at increasing temperatures, a closed loop control of the forming speed was developed. Since there are no proportional pneumatic valves available for the required pressure range, a parallel valve concept was chosen. By combining different valves, the characteristics of a larger proportional valve are imitated. A control algorithm was developed, that maps the required valves conductance into a valve combination to control the mass flow into the pressure chamber. The developed control system is presented and experimental results from the material test procedure are shown. These results reveal that the developed system is capable to track the required mass flow rate for low as well as high forming speeds up to a certain deformation when the deformation of the sheet becomes uncontrollable.
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Mendes, António C., Francisco P. Braga, and John R. Chaplin. "Wavetank Tests With a 1:20 Scale Model of a Distensible Tube Device for Wave Power Harnessing in the Azores." In ASME 2020 39th International Conference on Ocean, Offshore and Arctic Engineering. American Society of Mechanical Engineers, 2020. http://dx.doi.org/10.1115/omae2020-18176.
Full textAbstract:
Abstract The present research focuses on the performance assessment of a wave power system targeted for electrical supply of small communities in the Azores Archipelago. Firstly, the wave power potential and wave directionality in the region is assessed. The data collected points to a device capable of withstanding severe wave climate. The device considered herein incorporates a long rubber tube filled with water, floating head to waves, connected to an oscillating-water-column (OWC) in a shaft. The shaft and power take-off system (PTO) are to be mounted on an offshore jacket platform. By interacting with the incoming ocean waves the tube excites the OWC at its stern, thereafter forcing air in and out of the pneumatic chamber through a turbine-generator set. It has been observed that this device performs as a multiresonant attenuator that couples the tube’s surging motion and longitudinal pressure bulges with the water column oscillations. In our physical model the power take-off’s nonlinear impedance is emulated by means of a set of calibrated orifice plates with different diameters, connecting the pneumatic chamber to the atmosphere. A series of tests have been carried out with a 1:20 scale physical model in wave-tank, undertaken in regular waves that translate to 5 to 9 seconds wave period in full-scale. Two sets of waves were launched, whose wave heights cover a range from 1 to 5 m in real sea conditions, in deep water as well as in intermediate water depths. The pressure inside the chamber and the free-surface displacement in the shaft have been monitored, as well as the wave field. They provide estimates of the extracted power and energy capture efficiency of the system as a function of incident wave period. Scale effects are also addressed by comparison with previous experiments at different scales. Moreover, the amplification coefficient with the tube in position is quantified and compared with typical values for OWCs alone. It is worth noting that the accuracy of the power and energy capture predictions is greatly dependent on the volume flow calculations. Miller’s algorithm for compressible flow has been applied to reduce the uncertainty of volume flow calculations across the PTO orifice. The influences of the resonant operating modes and PTO impedance upon the capture-width are also discussed. The results obtained so far enable us to provide reliable estimates of absorbed power and energy capture efficiency, in prototype dimensions, under the wave climate in the Azores namely at Corvo Island.