Optimisation des états de surface et nouveau modèle de cavitation pour un écoulement lubrifié

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ISBN 13 :
Total Pages : 0 pages
Book Rating : 4.:/5 (139 download)

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Book Synopsis Optimisation des états de surface et nouveau modèle de cavitation pour un écoulement lubrifié by : Eric Dalissier

Download or read book Optimisation des états de surface et nouveau modèle de cavitation pour un écoulement lubrifié written by Eric Dalissier and published by . This book was released on 2012 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Cavitation dans un micro-canal modèle d'injecteur diesel

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ISBN 13 :
Total Pages : 201 pages
Book Rating : 4.:/5 (835 download)

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Book Synopsis Cavitation dans un micro-canal modèle d'injecteur diesel by : Cyril Mauger

Download or read book Cavitation dans un micro-canal modèle d'injecteur diesel written by Cyril Mauger and published by . This book was released on 2012 with total page 201 pages. Available in PDF, EPUB and Kindle. Book excerpt: Ce travail de thèse repose sur l’élaboration et l’exploitation d’un banc expérimental dédié à l’étude d’un écoulement cavitant dans un micro-canal, pour des conditions proches de celles de l’injection diesel. Ce banc a été développé dans le but de faire varier différents paramètres, notamment l’état de surface des parois du canal. Plusieurs méthodes optiques (imagerie en transmission, strioscopie et interférométrie) ont été mises en place afin de visualiser l’écoulementet d’en extraire des informations quantitatives. Les images en transmission permettent de visualiser la formation de vapeur dans le canal. Elles sont sensibles au gradient de masse volumique et font ainsi apparaître des couches de cisaillement, des structures turbulentes et des ondes de pression. Leur interprétation est rendue délicate par cette richesse en information et nécessite de recourir aux autres techniques optiques. Il ressort de ce travail que la cavitation se forme dans la couche de cisaillement, sous l’effet combiné de la dépression engendrée par le décollement à l’entrée du canal et de tourbillons générés par des instabilités dans la couche de cisaillement. La confrontation des résultats obtenus à l’aide des différentes techniques optiques, notamment les champs de pression reconstruits à partir des interférogrammes, montre que la zone de formation de la cavitation ne correspond pas à la zone de minimum de pression moyenne de l’écoulement. Il apparaît aussi que certaines bulles de vapeur ont une durée de vie bien supérieure à ce que prévoient les modèles de dynamique de bulles. On suspecte que des fluctuations de pression de l’ordre de 20 bar, associées à la turbulence, contribuent à la prolongation de ces temps de vie. Un algorithme de PIV, appliqué à des couples d’images en transmission, permet de montrer une augmentation importante des fluctuations de vitesse en sortie de canal lorsque les poches de vapeur se développent. Cette augmentation devient plus significative quand les poches atteignent60% de la longueur du canal. L’écoulement cavitant est essentiellement piloté par le nombre de cavitation K. Les conditions d’apparition et de développement de la cavitation ont été quantifiées dans différents canaux, en faisant varier des paramètres géométriques, la pression amont ou la température. L’influence de la hauteur du canal et du rayon de courbure à l’entrée de l’orifice est conforme aux données de la littérature. Une dépendance du nombre de cavitation critique Kcrit à l’apparition de la cavitation au nombre de Reynolds Re est montrée. Enfin, l’influence de l’état de surface des parois a fait l’objet d’une étude spécifique. Cette partie du travail demande probablement à être complétée mais l’état de surface semble avoir une influence sur la cavitation. D’après les cas étudiés au cours de cette thèse, une surface rugueuse ou texturée avec des motifs suffisamment espacés peut retarder l’apparition de la cavitation et une rugosité limitée (jusqu’à Ra = 0,7 μmici) peut favoriser le développement des poches de vapeur.

Cavitation and Related Phenomena in Lubrication

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ISBN 13 :
Total Pages : 248 pages
Book Rating : 4.:/5 (97 download)

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Book Synopsis Cavitation and Related Phenomena in Lubrication by : D. Dowson

Download or read book Cavitation and Related Phenomena in Lubrication written by D. Dowson and published by . This book was released on 1975 with total page 248 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Design and Modeling of Mechanical Systems

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Publisher : Springer Science & Business Media
ISBN 13 : 3642371434
Total Pages : 653 pages
Book Rating : 4.6/5 (423 download)

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Book Synopsis Design and Modeling of Mechanical Systems by : Mohamed Haddar

Download or read book Design and Modeling of Mechanical Systems written by Mohamed Haddar and published by Springer Science & Business Media. This book was released on 2013-03-12 with total page 653 pages. Available in PDF, EPUB and Kindle. Book excerpt: The 5th International Congress on Design and Modeling of Mechanical Systems (CMSM) was held in Djerba, Tunisia on March 25-27, 2013 and followed four previous successful editions, which brought together international experts in the fields of design and modeling of mechanical systems, thus contributing to the exchange of information and skills and leading to a considerable progress in research among the participating teams. The fifth edition of the congress (CMSM ́2013), organized by the Unit of Mechanics, Modeling and Manufacturing (U2MP) of the National School of Engineers of Sfax, Tunisia, the Mechanical Engineering Laboratory (MBL) of the National School of Engineers of Monastir, Tunisia and the Mechanics Laboratory of Sousse (LMS) of the National School of Engineers of Sousse, Tunisia, saw a significant increase of the international participation. This edition brought together nearly 300 attendees who exposed their work on the following topics: mechatronics and robotics, dynamics of mechanical systems, fluid structure interaction and vibroacoustics, modeling and analysis of materials and structures, design and manufacturing of mechanical systems. This book is the proceedings of CMSM ́2013 and contains a careful selection of high quality contributions, which were exposed during various sessions of the congress. The original articles presented here provide an overview of recent research advancements accomplished in the field mechanical engineering.

CONTRIBUTION A LA MODELISATION EN LUBRIFICATION HYDRODYNAMIQUE

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ISBN 13 :
Total Pages : 240 pages
Book Rating : 4.:/5 (49 download)

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Book Synopsis CONTRIBUTION A LA MODELISATION EN LUBRIFICATION HYDRODYNAMIQUE by : MICHELE.. CHAMBAT WEITZ

Download or read book CONTRIBUTION A LA MODELISATION EN LUBRIFICATION HYDRODYNAMIQUE written by MICHELE.. CHAMBAT WEITZ and published by . This book was released on 1987 with total page 240 pages. Available in PDF, EPUB and Kindle. Book excerpt: ANALYSE NUMERIQUE EN LUBRIFICATION HYDRODYNAMIQUE AVEC CAVITATION. EQUATIONS AUX DERIVEES PARTIELLES, METHODES ASYMPTOTIQUES, PROBLEMES DE FRONTIERES LIBRES ET HOMOGENEISATION. INFLUENCE DE LA RUGOSITE DE SURFACE

Poly(lactic acid) Science and Technology

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Publisher : Royal Society of Chemistry
ISBN 13 : 1849738793
Total Pages : 374 pages
Book Rating : 4.8/5 (497 download)

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Book Synopsis Poly(lactic acid) Science and Technology by : Alfonso Jiménez

Download or read book Poly(lactic acid) Science and Technology written by Alfonso Jiménez and published by Royal Society of Chemistry. This book was released on 2015 with total page 374 pages. Available in PDF, EPUB and Kindle. Book excerpt: A comprehensive overview of the synthesis, characterisation, properties and applications of poly(lactic acid) science and technology covering scientific, ecological, social and economic issues.

The London Underground and the public-private partnership agreements

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Publisher : The Stationery Office
ISBN 13 : 9780215038319
Total Pages : 134 pages
Book Rating : 4.0/5 (383 download)

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Book Synopsis The London Underground and the public-private partnership agreements by : Great Britain: Parliament: House of Commons: Transport Committee

Download or read book The London Underground and the public-private partnership agreements written by Great Britain: Parliament: House of Commons: Transport Committee and published by The Stationery Office. This book was released on 2008-01-25 with total page 134 pages. Available in PDF, EPUB and Kindle. Book excerpt: This report from the Transport Committee, examines London Underground and the Public-Private Partnership Agreements. The Government originally announced proposals for modernising the London Underground network system via Public-Private Partnership (PPP) agreements in 1998. Three contracts were drawn up with: (i) Tube Lines for the maintenance and renewal of the Jubilee, Piccadilly and Northern Lines; (ii) with Metronet Rail BVC for the maintenance and renewal of the Bakerloo, Central, Victoria & Waterloo & City Lines; (iii) with Metronet Rail SSL, responsible for the maintenance and renewal of the "sub-surface lines": the Circle, District, Hammersmith & City, Metropolitan & East London Lines. These PPP Agreements, 30 years in duration, were arrangements to maintain, renew and upgrade parts of London Underground by private sector infrastructure companies (Infracos), whilst London Underground is responsible for services to customers. The PPP Agreements also set out a performance-related incentive and penalty scheme to remunerate the Infracos for the improvements they make to the network. In May 2007, Metronet admitted an overspend of £1 billion and was refused access to loan facilities by the banks. It then made a reference to the PPP Arbiter, which in turn triggered an Extraordinary Review (which occurs when extra costs are incurred above the level allowed for the bid). Metronet put in a bid for £551m but the PPP Arbiter provisionally concluded that a sum of £121m was appropriate. Metronet subsequently went into administration on 18 July 2007. The report sets out a number of conclusions and recommendations, including: contracts that were supposed to deliver 35 station upgrades, in fact delivered only 14, 40% of the requirement; stations that were supposed to cost Metronet SSL £2m, cost £7.5m, with only 65% of schedule track renewal accomplished; the Committee criticises the consequences of the imposition of PPP on Transport for London, as a "lamentable state of affairs", with the future of most of London Underground's upgrade and maintenance work in doubt; the Committee states, that the Government should remember the failure of Metronet before it considers entering similar arrangements; that the Government should publish a candid analysis of the events preceding Metronet's collapse and its consequences; the Committee believe that the PPP model was flawed and probably inferior to traditional public-sector management; that the Government needs to prioritise transparency and clarity to taxpayers and ensure that any future contracts result in clear accountability.

Water Flow and Solute Transport in Soils

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Publisher : Springer Science & Business Media
ISBN 13 : 3642779476
Total Pages : 323 pages
Book Rating : 4.6/5 (427 download)

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Book Synopsis Water Flow and Solute Transport in Soils by : David Russo

Download or read book Water Flow and Solute Transport in Soils written by David Russo and published by Springer Science & Business Media. This book was released on 2012-12-06 with total page 323 pages. Available in PDF, EPUB and Kindle. Book excerpt: A year has passed since Eshel Bresler, my good friend and colleague, and a member of the editorial board of the Advanced Series in Agricultural Sciences, died suddenly while on a visit to the Chinese Academy of Sciences in Beijing. We had worked together for almost 30 years at the Institute of Soils and Water, ARO, The Volcani Center at Bet Dagan. At the very beginning of our scientific careers we cooperated directly and as a result one of our first publications was coauthored (Soil Sci. 101:205-209, 1966). Thereafter, our specific research interests diver sified, but we continued to work together, with similar approaches to research, and to strive towards the development of Israel soil science and its integration into general worldwide scientific progress. I don't need to emphasize Eshel's contribution to the understan ding of the processes governing water flow and solute transport pro cesses in soils and unsaturated zones. The contributions to this Volume by such a body of outstanding scientists shows the apprecia tion of the international scientific community to his research achievements.

Soil-Water-Solute Process Characterization

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Publisher : CRC Press
ISBN 13 : 9780367393359
Total Pages : 816 pages
Book Rating : 4.3/5 (933 download)

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Book Synopsis Soil-Water-Solute Process Characterization by : Javier Alvarez-Benedi

Download or read book Soil-Water-Solute Process Characterization written by Javier Alvarez-Benedi and published by CRC Press. This book was released on 2019-09-23 with total page 816 pages. Available in PDF, EPUB and Kindle. Book excerpt: The practitioner or researcher often faces complex alternatives when selecting a method to characterize properties governing a soil process. After years of research and development, environmental and agricultural professionals now have an array of methods for characterizing soil processes. Well-established methods, however, may not be suitable for the specific conditions of a study since many soil characteristics are intrinsically variable. An objective, integrated approach for soil characterization is needed to more effectively quantify parameters. Soil-Water-Solute Process Characterization goes beyond technical guidance and addresses the complicating factors such as spatial and temporal variability of soil processes, scale issues, soil structure, and the trade-offs between methods. It focuses on advanced methods for the monitoring and modeling of mass transfer processes in soil. Expert contributors present limitations to well-known methods and alternatives, discussing their practical applications for characterization efforts, evaluating strengths and weaknesses, and focusing on a reduced set of selected techniques. Three in-depth sections cover everything from multidisciplinary approaches for assessing subsurface non-point source pollution to techniques for characterizing water and energy balances at the soil-plant-atmosphere interface, field methods for monitoring soil water status, and computer models for characterizing the effect of chemicals in soil. This single-source reference is transforming method selection and our understanding of the principles, advantages, and limitations of the available monitoring techniques. Written in a simple and straightforward manner, Soil-Water-Solute Process Characterization is a detailed cookbook and a useful, practical reference for students, practitioners, and researchers.

Ergodic Theory

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Publisher : Walter de Gruyter GmbH & Co KG
ISBN 13 : 3110460912
Total Pages : 170 pages
Book Rating : 4.1/5 (14 download)

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Book Synopsis Ergodic Theory by : Idris Assani

Download or read book Ergodic Theory written by Idris Assani and published by Walter de Gruyter GmbH & Co KG. This book was released on 2016-06-20 with total page 170 pages. Available in PDF, EPUB and Kindle. Book excerpt: This monograph discusses recent advances in ergodic theory and dynamical systems. As a mixture of survey papers of active research areas and original research papers, this volume attracts young and senior researchers alike. Contents: Duality of the almost periodic and proximal relations Limit directions of a vector cocycle, remarks and examples Optimal norm approximation in ergodic theory The iterated Prisoner’s Dilemma: good strategies and their dynamics Lyapunov exponents for conservative twisting dynamics: a survey Takens’ embedding theorem with a continuous observable

Exact and Approximate Controllability for Distributed Parameter Systems

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ISBN 13 : 9781107096073
Total Pages : 472 pages
Book Rating : 4.0/5 (96 download)

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Book Synopsis Exact and Approximate Controllability for Distributed Parameter Systems by : Roland Glowinski

Download or read book Exact and Approximate Controllability for Distributed Parameter Systems written by Roland Glowinski and published by . This book was released on 2008-03-20 with total page 472 pages. Available in PDF, EPUB and Kindle. Book excerpt: A thorough mathematical analysis of controllability problems with a detailed investigation of methods for solving them numerically.

Water Treatment Handbook

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ISBN 13 : 9781845850050
Total Pages : 932 pages
Book Rating : 4.8/5 (5 download)

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Book Synopsis Water Treatment Handbook by :

Download or read book Water Treatment Handbook written by and published by . This book was released on 2007 with total page 932 pages. Available in PDF, EPUB and Kindle. Book excerpt: