Dissertations / Theses: 'Liner surface'

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Anderberg, Cecilia. "Characterisation and function of cylinder liner surfaces." Thesis, Halmstad University, School of Business and Engineering (SET), 2008. http://urn.kb.se/resolve?urn=urn:nbn:se:hh:diva-1340.

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The demands on decreased environmental impact from vehicles force the automotive industry to develop engines with reduced engine oil and fuel consumption. Engine oil consumption is recognized to be a significant source of pollutant emissions. Unburned or partially burned oil in the exhaust gases contribute directly to hydrocarbon and particulate emissions. Engine oil and fuel consumption are to a great extend controlled by the topography of the cylinder liner surface.

Recent engine tests have shown a promising reduction in oil consumption when using cylinder liners with a smoother finish than the current plateau honing.

One approach to produce smoother liner surfaces is to replace SiC ceramic honing stones with diamond tools. However, event though the diamond honing process results in higher productivity, improved demands of quality control is needed to monitor the degree of cold worked material - “blechmantel” (German), and the resulting risk of increased wear and scuffing.

A number of petrol and diesel engine cylinder liners have been mapped to be able to verify the quality and consequences, in terms of wear and function, of the honing process. A new mapping method, combining SEM images and quantitative image analysis with traditional 2D profilometry has been developed and tested in this study. The liners where tested in a reciprocating rig of 8 mm stroke and with a frequency of 10 Hz, simulating the top-dead center conditions in a running engine.

The tests where carried out in high- and low pressure conditions with smooth respectively rough liner roughnesses against PVD coated piston rings. The developed surface mapping method was employed before and after the test to study effect of running-in wear on the surface, features characterized with the SEM- and the 2D profilometer.

The results show that combining SEM- and profilometric methods gives a good picture of the effects of varying the cylinder liner pressure and roughness. The roughness of the core decreases more for diesel liners than for petrol liners. In average (rough and smooth liners) the diesel core roughness decreases 265% while the petrol liners average on a 60% decrease. Blechmantel- and Irregularities ratio show a high sensitivity to varying conditions and decrease 1180% to 100% for the diesel liners while the parameters increase between 106% to 18% for all the petrol liners. A probable cause is the more severe diesel high pressure run-in conditions are able to effectively “truncate” the plateaux and remove residing plastically deformed un-cut honing residues while the less severe petrol liner conditions not manage to remove the blechmantel and irregularities in an important extent.

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Rosenblatt, Nicolas. "Characterization of cylinder liner by image analysis." Thesis, Halmstad University, School of Business and Engineering (SET), 2007. http://urn.kb.se/resolve?urn=urn:nbn:se:hh:diva-929.

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The cylinder liners surface is of major importance in an engine since it interacts with the piston rings and creates a tribologic system. This tribologic system has to be qualified and controlled in order to understand and control wear, oil consumption and shelf life. In this purpose, a program has been created in order to analyze SEM pictures and from them qualify the surface.

The aim of the project presented here has been to improve the preliminary steps leading to the image computation by standardizing the picture acquisition and improve the image filtering.

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Buhaug, Øyvind. "Deposit Formation on Cylinder Liner Surface in medium-speed Engines." Doctoral thesis, Norwegian University of Science and Technology, Faculty of Engineering Science and Technology, 2003. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-209.

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The presence of deposits in the honing grooves in diesel engine cylinder liners can cause a severe increase in the consumption of lubricating oil. These deposits may appear amber in which case they may be referred to as 'liner lacquerer' or be nearly invisible in which case they are often referred to as 'transparent glaze' or 'bore glaze' in the marine sector. The formation of these deposits is believed to be influenced by engine design, engine load, fuel composition and lubricating oil composition. This relationship has, however, not been well understood and little material has been published on this subject. This thesis describes an investigation of this phenomenon. The problem has been approached by studying the composition of deposit samples, studying cases of deposit formation in the field and through experimental work.

As a result of this work, it is hypothesized that the root cause of the deposit formation is a mismatch between the rate of formation of oil insoluble material on or within the oil film and the oil film dispersing power and exchange rate. A large number of parameters will affect this balance which explains the sliding shift in appearance and composition of 'liner lacquer' and 'bore glaze' and the difficulty in identifying the cause of this problem.

A combined mass balance and chemical kinetics approach is used to bridge the gap between fundamental deposit theory and tangible engine related parameters. It is thus possible to rationalize the formation of deposits on cylinder liners. This understanding is sufficient to point out which factors should be considered in terms of the prevention of deposit formation and to present a viable hypothesis on the reason for the deposit formation in the engines that have been investigated in the course of this work as summarized in the following paragraph.

The presence of deposit indicates that the dispersing power and transport rate of the oil film is insufficient to deal with the deposit precursors being formed. This is believed related to extensive low load operation which is associated with both low liner temperatures and low nominal oil consumption in these engines. Low liner temperatures will encourage the formation of insoluble material due to condensation of sulphuric acid precursors, while low oil consumption is believed to indicate low oil film exchange which reduces the transport of matter and also contributes to oil film oxidation by prolonging the exposure to combustion gases.

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Spencer, Andrew. "A simulation tool for optimising combustion engine cylinder liner surface texture." Doctoral thesis, Luleå tekniska universitet, Maskinelement, 2013. http://urn.kb.se/resolve?urn=urn:nbn:se:ltu:diva-26512.

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Fuel efficiency is one of the most important areas of automotive vehicle research and development today, with rising fuel costs, energy security and environmental concerns being at the forefront of customers and legislators minds. Heavy Duty Diesel Engines (HDDE) are the primary source of mechanical power generation in today’s trucks and buses and this is likely to continue for the foreseeable future. In the 2011 European Commission White Paper on transport, a reduction of at least 60% of greenhouse gas emissions from transport by 2050, with respect to 1990 levels, was called for. The report concludes that acting on vehicles’ efficiency through new engines, materials and design will help in the reduction of oil dependence, the competitiveness of Europe’s automotive industry as well as health benefits, especially improved air quality in cities. Therefore, the efficiency and frictional losses in a vehicles powertrain are areas of great interest. This thesis focuses on the Piston Ring to Cylinder Liner (PRCL) contact and the potential for improving its performance through the specification of an optimised cylinder liner surface texture. The PRCL contact is one of the biggest contributors to mechanical losses in a HDDE and so there is potential for large performance gains to be achieved through optimisation of this contact. This research has led to the development of a simulation tool capable of calculating the friction, lubrication regime, oil consumption risk and wear that occurs in the full ring-pack of a HDDE. Furthermore, the tool allows for the evaluation of the relative performance of different cylinder liner surface topographies. A mixed lubrication model, incorporating flow factors calculated using the homogenization technique, has been implemented to allow all regimes of lubrication to be considered. A mass-conserving cavitation algorithm, formulated as a Linear Complimentarity Problem, enables lubricant cavitation, fully-flooded or starved inlet conditions and the quantity of lubricant deposited on the cylinder liner surface to be modelled. The simulation tool is validated with both reciprocating bench tests and full single cylinder fired engine tests. The reciprocating bench tests measured both friction and film thickness and both showed good correlation with the predictions from the simulation tool. Simulations and experiments were conducted on four different cylinder liner variants and both ranked the frictional performance of the cylinder liner variants in the same order. A parametric study of honing depth, spacing and angle was undertaken using the developed simulation tool and the influence of these parameters on lubricant film thickness, friction, wear and oil consumption was investigated. The thesis concludes that a reduction in specific fuel consumption is achieveable through the optimisation of cylinder liner texture and outlines how this might be achieved.
Godkänd; 2013; 20131110 (spencer); Tillkännagivande disputation 2013-11-22 Nedanstående person kommer att disputera för avläggande av teknologie doktorsexamen. Namn: Andrew Spencer Ämne: Maskinelement/Machine Elements Avhandling: A Simulation Tool for Optimising Combustion Engine Cylinder Liner Surface Texture Opponent: Professor Martin Priest, School of Mechanical Engineering, The University of Leeds, UK Ordförande: Professor Roland Larsson, Institutionen för teknikvetenskap och matematik, Luleå tekniska universitet Tid: Fredag den 13 december 2013, kl 10. Plats: E632, Luleå tekniska universitet

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Wassborg, Pär. "Tribological evaluation of the contact between upper compression ring and cylinder liner with different surface coatings." Thesis, Karlstads universitet, Institutionen för ingenjörsvetenskap och fysik, 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:kau:diva-45454.

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The constant pursuit in the automotive industry to increase the engines performance, new solutions are always developed and tested to reduce the friction and increase the efficiency in the engine. One component that contributes to friction losses is the piston ring pack where the top compression stands for up to 40 %. This master thesis collaborated with Scania’s material science department Basic engine and covers the friction and wear of four different materials on the cylinder liner surface against the top compression ring.The four tested materials were grey cast iron with different honing quality and three atmospheric plasma sprayed coatings with titanium oxide, chromium oxide and Metco’s mixture F2071 which is a stainless steel mixed with a ceramic. A martensitic steel piston ring with a chromium coated sliding surface was used for all the testing in the Cameron-Plint TE77 test-rig. This is a pin-on-disc test method and the parameters used for testing is set to replicate the environment the ring is exposed to at the top dead centre.The test-rig has been in Scania’s possession for a long time and has not always given a satisfying result. An uneven contact between the ring and liner has been a problem resulting in only worn edges of the liner specimen. The piston ring holder was therefore redesigned to be able to adjust the radius of the ring. This allowed a good conformability between the ring and liner to be obtained.The tested materials were evaluated according to friction and wear. Friction was measured with the test-rig and the wear was calculated with surface profiles that were measured before and after testing. Worn surfaces were studied in a SEM to verify which wear mechanism that was active. The changes of the surfaces was studied with the use of following surface parameters Ra, Rk, Rpk, Rvk and if there was a connection between these parameters and friction and wear coefficient.Independent of honing quality showed the grey cast iron lowest friction coefficient just under 0.13, the F2071 liner showed a friction coefficient just above 0.13. Both oxide layers showed similar friction where the chromium oxide had a friction just below 0.15 and the titanium oxide lay just above 0.15. Lowest wear coefficient had the chromium oxide followed by F2071, titanium oxide and the bad honed grey cast iron. These three liners showed almost the exact same wear coefficient. Worst wear coefficient had the grey cast iron with a good honing quality. A mild abrasive wear mechanism was active during the wear test and vague wear marks was found on the surface. There is no connection between wear coefficient and friction and the change in surface roughness during the test does not affect the friction.

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6

Treiss, Stephanie. "TIME-DEPENDENT SURFACE TEMPERATURE and HEAT FLUX MEASUREMENTS on a SINGLE CYLINDER ENGINE HEAD and LINER." The Ohio State University, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=osu1512061036731254.

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7

Zhao, Qing Ph D. Massachusetts Institute of Technology. "Modeling of contact between liner finish and piston ring in internal combustion engines based on 3D measured surface." Thesis, Massachusetts Institute of Technology, 2014. http://hdl.handle.net/1721.1/92105.

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Thesis: S.M., Massachusetts Institute of Technology, Department of Mechanical Engineering, 2014.
Cataloged from PDF version of thesis.
Includes bibliographical references (pages 87-88).
When decreasing of fossil fuel supplies and air pollution are two major society problems in the 21st century, rapid growth of internal combustion (IC) engines serves as a main producer of these two problems. In order to increase fuel efficiency, mechanical loss should be controlled in internal combustion engines. Interaction between piston ring pack and cylinder liner finish accounts for nearly 20 percent of the mechanical losses within an internal combustion engine, and is an important factor that affects the lubricant oil consumption. Among the total friction between piston ring pack and cylinder liner, boundary friction occurs when piston is at low speed and there is direct contact between rings and liners. This work focuses on prediction of contact between piston ring and liner finish based on 3D measured surface and different methods are compared. In previous twin-land oil control ring (TLOCR) deterministic model, Greenwood-Tripp correlation function was used to determine contact. The practical challenge for this single equation is that real plateau roughness makes it unreliable. As a result, micro geometry of liner surface needs to be obtained through white light interferometry device or confocal equipment to conduct contact model. Based on real geometry of liner finish and the assumption that ring surface is ideally smooth, contact can be predicted by three different models which were developed by using statistical Greenwood-Williamson model, Hertzian contact and revised deterministic dry contact model by Professor A.A. Lubrecht. The predicted contact between liner finish and piston ring is then combined with hydrodynamic pressure caused by lubricant which was examined using TLOCR deterministic model by Chen. et al to get total friction resulted on the surface of liner finish. Finally, contact model is used to examine friction of different liners in an actual engine running cycle.
by Qing Zhao.
S.M.

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8

Куркчи, Євгеній Петрович, Евгений Петрович Куркчи, and Yevhenii Petrovych Kurkchy. "Анализ методов поверхностного упрочнения, применяемых для увеличения износостойкости пар трения." Thesis, Сумский государственный университет, 2014. http://essuir.sumdu.edu.ua/handle/123456789/39651.

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В большинстве газовых и воздушных компрессоров в цилиндро-поршневой группе используются материалы пар трения, позволяющие полностью исключить введение смазки в рабочую зону. Однако существует проблема недостаточной очистки перекачиваемого газа, из-за чего абразивосодержащие примеси шаржируют поверхность колец и в процессе трения такой конструкции происходит ускоренный износ поверхности втулки цилиндра.

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9

Müller, Mario. "Wasserhaushaltsschichten als Bestandteil von Deponieoberflächenabdichtungssystemen." Doctoral thesis, Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2011. http://nbn-resolving.de/urn:nbn:de:bsz:14-qucosa-70532.

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Das Wechselspiel Boden-Pflanze und die damit verbundenen Wassergehaltsänderungen im Boden bestimmen die Funktionalität einer Wasserhaushaltsschicht. Untersuchungen an der Lysimeterstation Bautzen/Nadelwitz machen deutlich, dass vielfältige Faktoren (z. B. nFK, Durchwurzelungstiefe) die Mächtigkeit einer Wasserhaushaltsschicht bestimmen. Der Bodeneinbau mit einem Verdichtungsgrad von 90% - 92% Proctordichte gewährleistet ein setzungsstabiles Korngerüst unter Gewährleistung der geforderten nFK und LK. Durch die Erweiterung des Feinbodenartendreiecks mit den Ebenen „Durchwurzelung“, „nutzbare Feldkapazität“ und „Standsicherheit“ wird eine fachübergreifende Eignungsbeurteilung von Böden ermöglicht. Die wasserhaushaltspezifische Anwendung des Dreiecks der Phasenzusammensetzung nach RUDERT erlaubt die Ausweisung von Schwankungsbreiten bzgl. der Einbaukenngrößen, ohne Abweichungen von den geforderten bodenphysikalischen Anforderungen an eine Wasserhaushaltsschicht hinnehmen zu müssen.

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Block, Stephan [Verfasser]. "On surface forces and morphology of linear polyelectrolytes physisorbed onto oppositely charged surfaces / Stephan Block." Greifswald : Universitätsbibliothek Greifswald, 2011. http://d-nb.info/1010396889/34.

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11

Rehberger, Marcus. "Topographical micro-changes in corrugated board production : effects on flexographic post-print quality." Licentiate thesis, Stockholm : Department of Media Technology and Graphic Arts, School of Computer Science and Communication, Royal Institute of Technology, 2007. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-4583.

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12

Silva, Leonardo Rosa Ribeiro da. "Texturização superficial de cilindros automotivos." Universidade Federal de Uberlândia, 2016. https://repositorio.ufu.br/handle/123456789/17988.

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Conselho Nacional de Desenvolvimento Científico e Tecnológico
Coordenação de Aperfeiçoamento de Pessoal de Nível Superior
Fundação de Amparo a Pesquisa do Estado de Minas Gerais
A texturização superficial é uma importante ferramenta a ser utilizada na diminuição do atrito em contatos lubrificados, sendo sua eficácia atestada tanto em simulações como experimentalmente. Uma grande barreira para a utilização em escala industrial da texturização superficial e a dificuldade de se encontrar métodos de inserção destes padrões superficiais que combinem rapidez de implementação e baixo custo, tornando assim a técnica mais competitiva. O objetivo deste trabalho é investigar a viabilidade de se inserir texturas superficiais na superfície interna de cilindros automotivos de ferro fundido cinzento, utilizando método de texturização superficial sem mascaramento (MECT), o qual combina baixo custo e elevada velocidade de texturização. Uma vez estabelecidos os parâmetros de texturização do método MECT para o ferro fundido cinzento, foram conduzidos ensaios anel-bloco a fim de comparar os ganhos na redução do atrito e do desgaste de amostras texturizadas quando comparadas a amostras polidas mecanicamente e eletroquimicamente. O MECT se mostrou um método viável, rápido e de baixo custo para texturização de camisas de cilindros automotivos. Nos ensaios anel-bloco as amostras texturizadas superficialmente apresentaram menores coeficiente de atrito e volume desgastado em relação as amostras polidas mecanicamente e eletroquimicamente.
Surface texturing is an important tool to be used for reduction of the friction force in lubricated contacts, being its effectiveness evidenced in simulations and experimentally. A major barrier to use surface texturing in an industrial scale is the difficulty of finding application methods of these surface patterns that combine both high speed and low cost, thus making the surface texturing a more competitive technique. The objective of this work is to investigate the potentiality of inserting surface textures on the inner surface of an automotive cylinder liner made of grey cast iron, using Maskless Electrochemical Texturing Method (MECT), which is a both low cost and high-speed texturing process. Once established the texturing parameters for the method MECT for the grey cast iron, were made Block-on-Ring tests to compare the improvement in reducing friction force and wear of the textured samples in comparison with samples mechanically and electrochemically polished. The method MECT proved to be a viable method for texturing of automotive cylinder liners, being both fast and low cost. In the Block-on-Ring tests, the texturized samples showed lower friction coefficient and wear volume compared to the mechanically and electrochemically polished samples.
Dissertação (Mestrado)

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Kane, Charles B. "Plasma modification of linen." Thesis, University of Ulster, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.274070.

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Gyurecz, György, and Tibor Bercsey. "Surface Shape Correction by Highlight Lines." Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2017. http://nbn-resolving.de/urn:nbn:de:bsz:14-qucosa-228739.

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The design of industrial products applies various construction aspects. Beside functionality and manufacturability conditions that are essential in technical design, products must also meet aerodynamic, hydrodynamic and aesthetic demands. These demands are particularly important in automotive, ship and airplane industry but they are also present in the design of medical replacements, household appliances, etc. The common objective of above aspects is to produce smooth and irregularity free surface shape. Quality and smoothness of surfaces of industrial objects can efficiently be evaluated by highlight lines.

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Gyurecz, György, and Tibor Bercsey. "Surface Shape Correction by Highlight Lines." TUDpress - Verlag der Wissenschaften GmbH, 2012. https://tud.qucosa.de/id/qucosa%3A30525.

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The design of industrial products applies various construction aspects. Beside functionality and manufacturability conditions that are essential in technical design, products must also meet aerodynamic, hydrodynamic and aesthetic demands. These demands are particularly important in automotive, ship and airplane industry but they are also present in the design of medical replacements, household appliances, etc. The common objective of above aspects is to produce smooth and irregularity free surface shape. Quality and smoothness of surfaces of industrial objects can efficiently be evaluated by highlight lines.

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16

Methakullachat, Deeboon. "Surface reconstruction using 3D linear features /." The Ohio State University, 2002. http://rave.ohiolink.edu/etdc/view?acc_num=osu1486459267519196.

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Morgenthaler, Michael J. E. "Non-linear optical studies of surfaces." Thesis, Heriot-Watt University, 1993. http://hdl.handle.net/10399/1430.

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Dowey, Stephen James. "Advanced on-line and off-line process control for surface-engineered applications." Thesis, University of Hull, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.310319.

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19

Tang, Dawei. "Investigation of line-scan dispersive interferometry for in-line surface metrology." Thesis, University of Huddersfield, 2016. http://eprints.hud.ac.uk/id/eprint/29153/.

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Advanced manufacturing techniques enable ultra-precision surfaces to be fabricated with various complicated and large-area structures. For instance, the cost-effectiveness of Roll-to-Roll (R2R) manufacturing technology has been widely demonstrated in industries making high volume as well as large-area foil products and flexible electronics. Evaluation of these fine surfaces by an expensive trial-and-error approach is unadvisable due to the high scrap rate. Therefore quality control using in-line metrology of the functional surface plays an important role in the success of employing R2R technology by enabling a high product yield whilst guaranteeing high performance and a long lifespan of these multi-layer products. This thesis presents an environmentally robust line-scan dispersive interferometry (LSDI) technique that is suitable for applications in in-line surface inspection. Obtaining a surface profile in a single shot allows this interferometer to minimise the effect of external perturbations and environmental noise. Additionally, it eliminates the mechanical scanning and has an extended axial measurement range without the 2π phase ambiguity problem by dispersing the output of the spectrometer onto the camera. Benefiting from high-speed camera, general-purpose graphics processing unit and multi-core processor computing technology, the LSDI can achieve high dynamic measurement with a high signal-to-noise ratio and is effective for use on the shop floor. Two proof-of-concept prototypes aimed at different applications are implemented. The cylindrical lens based prototype has a large lateral range up to 6 mm and can be used for characterisation of additively manufactured surface texture, surface form and surface blemish. The second prototype using a 4X microscope objective with a diffraction limited lateral resolution (~ 4 µm) is aiming at characterisation of surface roughness, micro-scale defects, and other imperfections of the ultra-precision surfaces. System design, implementation, fringe analysis algorithms and system calibrations are presented in detail in this thesis. Their performances are evaluated experimentally by measuring several standard step heights as well as Al2O3 coated polyethylene naphthalate (PEN) films. The measurement results acquired using both prototypes and a commercial available instrument (Talysurf CCI 3000) align with each other acceptably. This shows that the developed metrology sensors may potentially be applied to production lines such as R2R surface inspection where only defects present on the surface are concerned in terms of quality assurance. Implementation of these prototypes offers an attractive solution to improve manufacturing processing and reliability for the products in ultra-highprecision engineering.

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MuÌˆnch, Wolfram Helmut Patrick. "Turbulent distortion of line and surface elements." Thesis, University of Cambridge, 1989. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.316760.

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BRITO, TIAGO NOVELLO DE. "DISCRETE LINE FIELDS ON SURFACES." PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIRO, 2018. http://www.maxwell.vrac.puc-rio.br/Busca_etds.php?strSecao=resultado&nrSeq=36019@1.

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PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIRO
COORDENAÇÃO DE APERFEIÇOAMENTO DO PESSOAL DE ENSINO SUPERIOR
PROGRAMA DE SUPORTE À PÓS-GRADUAÇÃO DE INSTS. DE ENSINO
PROGRAMA DE EXCELENCIA ACADEMICA
PROGRAMA DE DOUTORADO SANDUÍCHE NO EXTERIOR
Um campo de linhas sobre uma superfície é um mapa suave que atribui uma linha tangente a todos, exceto a um número finito de pontos. Esses campos modelam um número de propriedades geométricas e físicas, tais como as direções de curvatura principais nas superfícies ou o fluxo de tensão na elasticidade. Para entender um campo de linha, é usual estudar o comportamento de suas órbitas, que podem apresentar diferentes padrões. Para este fim, consideramos uma abordagem topológica que consiste em utilizar os pontos críticos e separatrices para decompor o campo em regiões de comportamento homogêneo. Focamos em campos que possuem uma estrutura de Morse–Smale. Isso permite operações como o cancelamento de pontos críticos controlados diretamente na decomposição de campo, o que é essencial para a remoção de ruído (simplificação da topologia) em campos provenientes de simulações ou amostragem de problemas do mundo real. Baseado na decomposição de um campo vetorial de Morse–Smale e no cancelamento de pontos críticos, Robin Forman introduziu uma definição discreta para esses campos. O presente trabalho fornece uma definição puramente combinatória para campos de linhas, os campos de linhas discretos, que implicam as construções discretas de Forman para campos de vetores por meio de uma nova representação destes. Campos de linhas discretos admitem uma decomposição que gera uma ponte entre os campos de linhas discretos e suaves, garantindo dessa forma a consistência topológica da definição. Também estabelecemos uma conexão entre um campo de linha discreto e um campo vetorial discreto, desse modo as ferramentas de campos de vetores podem ser usadas em campos de linhas. O trabalho fornece ainda um cancelamento topologicamente consistente de seus elementos críticos para um campo de linha discreto.
A line field on a surface is a smooth map that assigns a tangent line to all but a finite number of points. Such fields model a number of geometric and physical properties, e.g. the principal curvature directions on surfaces or the stress flux in elasticity. They can be seen as a generalization of vector fields. To understand a line field, it is common to study the behavior of its orbits, which can have many different patterns. To this end, we consider a topological approach: we use the critical points and separatrices to decompose the field in regions of similar behavior. We focus on fields that have a Morse–Smale structure. This allows operations like the cancellation of critical points controlled directly in the field decomposition, which is essential for noise removal (topology simplification) on fields coming from simulations or sampling of real-world problems. Based on the decomposition of a Morse–Smale vector field and on cancellation of critical points, Robin Forman introduced a discrete definition for Morse-Smale vector fields. This thesis provides a purely combinatorial definition of line fields, the discrete line fields, entailing Forman s discrete constructions for vector fields through a new representation of these. Discrete line fields admit a (Morse–Smale type of) decomposition that generates a bridge between discrete and smooth line fields, thus guaranteeing the topological consistency of the definition. We also use double branched coverings to suspend discrete line fields to discrete vector fields, so that vector field tools can be used for discrete line fields. Finally we provide, for a discrete line field, a topologically consistent (Morse-like) cancellation of critical elements. This allows a simplification of the discrete line field topology retaining only the most significant features.

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Spencer, Andrew. "Optimizing surface texture for combustion engine cylinder liners." Licentiate thesis, Luleå tekniska universitet, Maskinelement, 2010. http://urn.kb.se/resolve?urn=urn:nbn:se:ltu:diva-17001.

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The Piston Ring - Cylinder Liner (PRCL) contact is the single largest contributor to frictional losses in an internal combustion (IC) engine, causing 20-40% of all mechanical losses. If these mechanical losses can be reduced by 10% then vehicle fuel efficiency could be increased by approximately 1.5-2.5%. In todays automotive industry fuel efficiency is one of the most important factors in vehicle design due to increasing concerns about energy security, increasing fuel prices and climate change. The objective of this project is to optimise the cylinder surface texture, which when referring to cylinder liners in this work means the cross-hatch grooves left by the honing process.This work focuses on simulation techniques that can be used to help optimize cylinder liner surface texture to reduce friction while at the same time minimizing oil consumption and wear. Cylinder liner surface topography is investigated with a range of measurement techniques in order to reveal all the important features of the existing surface. Different ways of characterizing surface topography based on both traditional height averaging parametersand functional parameters calculated for a range of different surface measurements are discussed. The different characterization techniques are compared to find the most appropriate way of quantitatively describing surface topographies.A full engine cycle simulation of the PRCL contact has been developed. A homogenization technique was implemented for solving the Reynolds equation. This is a two scale approach where surface roughness is treated on the local scale and surface texture plus global geometry on the global scale. A method for generating artificial surface topography based on real surface measurement data was developed. This allows for the possibility of simulating a wide range of new surface topographies in order to investigate their potential for reducing friction and minimising oil consumption and wear.
Godkänd; 2010; 20101115 (spencer); LICENTIATSEMINARIUM Ämnesområde: Maskinelement/Machine Elements Examinator: Professor Roland Larsson, Luleå tekniska universitet Diskutant: Professor Michel Cervantes, Luleå tekniska universitet Tid: Fredag den 17 december 2010 kl 13.00 Plats: E231, Luleå tekniska universitet

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23

Hata, Misako. "Non linear tolerance analysis by response surface methodology." Ohio : Ohio University, 2001. http://www.ohiolink.edu/etd/view.cgi?ohiou1173897314.

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24

Al-Jibouri, Khalid Ibrahim G. "Electromagnetic linear surface guided modes and plasmon couplers." Thesis, University of Salford, 1991. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.304494.

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25

Hunt, M. J. "Linear and nonlinear free surface flows in electrohydrodynamics." Thesis, University College London (University of London), 2013. http://discovery.ucl.ac.uk/1397249/.

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This thesis examines free surface flows in electrohydrodynamics under forcing in the form of a moving pressure distribution or topography. The ideas from examining free surface flows with forcing and those ideas andmethods coming from examining solitary waves within electrohydrodynamics are combined to study free surface flows under forcing in electrohydrodynamics. Chapter 1 gives a brief introduction to the ideas and work that have gone into investigating free surface flows and solitary waves in general and gives an idea of what will happen in the thesis. Chapter 2 formulates the general problem for the full nonlinear case and then examines the linear solution for both a moving pressure distribution and topography and presents profiles of the free surfaces and then shows that the solutions are nonuniform by examining the deep water case. Chapter 3 introduces the scaling for the weakly nonlinear problem and produces an equation which there is no nonuniformity and the amplitude of the free surface is finite. The case when the Bond number is around a 1/3 is also examined. Stokes analysis is performed to look for Wilton ripples. Chapter 4 examines conducting fluids adhering to an upper surface, the basic equations are set up and then the dispersion relation is derived to examine the existence of linear waves for certain values of the wavenumber k. A set of weakly nonlinear equations are examined and then solved numerically with examples of periodic profiles presented. A Stokes analysis is carried out for small amplitudes to look for Wilton ripples. An analysis is carried out for the approximation of long wavelength but finite depth, where the wave amplitude is the depth of the fluid. Chapter 5 considers surface flows and generalised the results from chapters 2 and 3 from two dimensions to three, linear free surface profiles are calculated and plotted and the weakly nonlinear equation is derived for the cases where the Bond number is close to 1/3 and not close to 1/3 giving a 5th order (Kadomstev-Petviashvili) (KP) equation. Chapter 6 is the set of conclusions and avenues of future research.

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26

Mestre, Manuel. "Détermination d'intervalles de confiance par prédiction et optimisation de la position des sites de mesure en métrologie dimensionnelle des surfaces fabriquées." Cachan, Ecole normale supérieure, 1993. http://www.theses.fr/1993DENS0012.

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La métrologie dimensionnelle des surfaces fabriquées calcule le défaut de forme a partir d'échantillons de points mesures, ignorant le comportement de la surface en tous les autres points. Pour remédier à cela, cette thèse applique aux surfaces les méthodes classiques de prédiction linéaire d'un signal aléatoire à incréments gaussiens, stationnaires, ergodiques. Lorsque la surface se conforme à ces hypothèses, la prédiction est très satisfaisante. Dans le cas contraire, la prédiction présente diverses pathologies qu'il est possible de traiter par des méthodes corrigées. Toutes les surfaces peuvent alors être prédites de façon satisfaisante. Cette thèse étudie expérimentalement les propriétés statistiques et spectrales des surfaces fabriquées industrielles, en vue de la prédiction. D'autre part, les critères classiques d'optimisation de la position des sites de mesure, maximisant l'information apportée par un échantillon, donnent de bons résultats

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27

Cox, Anna Lee. "A categorization of piecewise-linear surfaces." Virtual Press, 1994. http://liblink.bsu.edu/uhtbin/catkey/902464.

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Any Piecewise-Linear (PL) surface can be formed from a regular polygon (including the interior) with an even number of edges, where the edges are identified in pairs to form a two-dimensional manifold. The resulting surfaces can be distinguished by algebraic means. An analysis of the construction algorithm can also be used to determine the resulting surface. Knowledge of the polygon used can also yield information about the surfaces formed.In this thesis, an algorithm is developed that will analyze all possible edge pairings for an arbitrary regular polygon. The combination of this data, along with known techniques from geometric topology, will categorize the constructions of these PL surfaces. A procedure using matrices is developed that will determine the Euler number and establish which algebraic words are equivalent.This topic extends to two-dimensional manifolds a classical method of analysis for three-dimensional manifolds. It therefore provides a more geometrical approach than has traditionally been used for two dimensional surfaces.
Department of Mathematical Sciences

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28

Kim, Sangwoo. "Multiconductor transmission line analysis using surface ribbon method /." Digital version accessible at:, 1999. http://wwwlib.umi.com/cr/utexas/main.

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29

Jayasankaran, Kathik. "STRUCTURE-BORNE NOISE MODEL OF A SPUR GEAR PAIR WITH SURFACE UNDULATION AND SLIDING FRICTION AS EXCITATIONS." The Ohio State University, 2010. http://rave.ohiolink.edu/etdc/view?acc_num=osu1269451200.

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30

Hurley, Barbara Jill. "Contact-line movement on a variably heated surface." Diss., Georgia Institute of Technology, 1993. http://hdl.handle.net/1853/16728.

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31

Melton, Mark David. "Precise surface placement in transmission line matrix modelling." Thesis, Loughborough University, 2001. https://dspace.lboro.ac.uk/2134/14898.

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The Transmission Line Matrix modelling technique is a spatially discrete, time domain numerical modelling method. It has uses in many fields; however its main applications are for acoustic and electromagnetic modelling. This work focuses upon the study the positioning of surfaces which reflect and scatter waves within TLM models. In particular, the way in which the precise position of objects and surfaces are represented within the limitations of the model. Previously reported methods for improving surface positioning are investigated and evaluated. The previous methods are used as the basis for a new and improved method. The key features and performance of the method are appraised and areas for improvement defined. From this starting point, an enhanced method modifying the basic features and implementation is described. This enhanced method gives significantly improved results. Extensive testing of the original method and the enhanced method . are given in an unobstructed abstract case, clearly showing the performance differences of both methods and suitability for representing preCisely placed surfaces. Examples of the application of the method for both electromagnetic and acoustic modelling are given. Applications to ideal, abstract, and real world models are included. Results are compared with standard analytical benchmarks, results from other methods and measured data. The results show that there is a very clear and significant improvement in the performance of the TLM technique if the precise placement scheme given here is used.

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32

Wu, Wei. "Linear analysis of surface temperature dynamics and climate sensitivity." Diss., Texas A&M University, 2005. http://hdl.handle.net/1969.1/4948.

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Spectral properties of global surface temperature and uncertainties of global climate sensitivity are explored in this work through the medium of Energy Balance Climate Models (EBCMs) and observational surface temperature data. In part I, a complete series of 2D time-dependent non-orthogonal eigenmodes of global surface temperature are analytically derived and their geographic patterns are presented. The amplitudes of these modes have temporal characteristics and present exponentially decaying patterns. Theoretically, if the energy balance model is forced by white noise forcing in time, the autocorrelation functions of the mode amplitudes should present the same exponentially decaying patterns. When observed surface temperature data are projected onto these theoretical modes, the autocorrelation time scales of the mode amplitudes exhibit similar exponential decaying patterns. These modes are believed to be useful for surface temperature studies and model intercomparison. In part II, an objective means of deriving the probability density function (PDF) of global climate sensitivity is investigated. The method constrains the PDF by its fit to the present climate in terms of surface temperature. We found that a wide range of parameter combinations, which corresponds to a broad range of the sensitivity, shows equally good fits to the present climate. It means that the uncertainties in global climate sensitivity are very difficult to eliminate if climate models are tuned to fit observations of surface temperature alone. The origin of the skewness of the PDF is found in very simple terms.

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33

Matiukas, Vilius. "Reconstruction of 3D object's surface image using linear beam." Doctoral thesis, Lithuanian Academic Libraries Network (LABT), 2012. http://vddb.laba.lt/obj/LT-eLABa-0001:E.02~2012~D_20120215_161626-44197.

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This dissertation investigates issues relevant to virtualization of a real 3D object – that is, producing a model of the object from its image data, and then visualizing this model as an image seen on the computer screen The object of investigation is methods and algorythms for reconstruction of a complex geometric shape from a number of unorganised point sets in to electronic form. Unorganised point sets are obtained by scanning the 3d object from defferent points of view. The choise of the complex oject is made so that it can not be described by a simple mathematical expression. To attain the aim, the following tasks were put forward: developing a model for a source of linear beam (scanner) and generating an unorganized point set that approximates the object scanned, filtering the unorganized point set and aggregating the unorganized point set to build an entire image of the object and reconstruct its surface. The aim of this work was to reconstruct the surface image of a 3D object using linear beam. This aim was sought by modifying the existing methods, or proposing new methods, and evaluating the accuracy of the reconstruction using statistical techniques The work consists of the general characteristic, four chapters, conclusions, list of literature and list of publications. The first section reviews the human visual system, computer vision and three-dimensional imaging technologies. The second section is addressed to a problem of linear beam’s centreline extraction in 2d... [to full text]
Šioje disertacijoje nagrinėjamas realaus trimačio objekto virtualizavimas – t. y. objekto paviršiaus modelio sukūrimas iš skenuotų vaizdų aibės, po to vizualizuojant šį modelį atvaizdo kompiuterio monitoriaus ekrane pavidalu. Tyrimų objektas – sudėtingos geometrinės formos erdvinio objekto paviršiaus atkūrimo elektroniniu pavidalu iš keleto nestruktūrizuotų taškų rinkinių, gautų nuskaitant objektą skirtingomis apžvalgos kryptimis, metodai ir algoritmai. Sudėtinga objekto forma pasirinkta tam, kad jos nebūtų galima perteikti paprasta matematine išraiška. Erdvinio objekto virtualizavimo procesą galima išskaidyti į šiuos keturis etapus: nestruktūrizuotų taškų rinkinio formavimą, filtravimą, apjungimą ir rekonstravimą. Pirmojo etapo metu, naudojant optinius jutiklius ir kontaktinį skaitymo metodą, objektas nuskaitomas skirtingomis apžvalgos kryptimis, taip gaunant keletą objekto paviršiaus nestruktūrizuotų taškų rinkinių. Antrame etape pašalinami taškai, atsiradę dėl optinių iškraipymų, atspindžių ir šešėlinių sričių įtakos. Trečiame etape atskiri taškų rinkiniai apjungiami į visumą. Paskutinis etapas skirtas erdvinio objekto paviršių aproksimuojančiam tinkleliui gauti. Pagrindinis šio darbo tikslas buvo rekonstruoti erdvinio objekto paviršiaus atvaizdą, objektą apšviečiant linijiniu šviesos pluoštu. Šio tikslo buvo siekiama tobulinant esamus metodus arba kuriant naujus, o taip pat statistiniais metodais vertinant rekonstrukcijos tikslumą. Disertacijos... [toliau žr. visą tekstą]

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34

Lott, Christian D. "Electrothermomechanical Modeling of a Surface-micromachined Linear Displacement Microactuator." BYU ScholarsArchive, 2005. https://scholarsarchive.byu.edu/etd/306.

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The electrothermomechanical characteristics of an electrically-heated polycrystallinesilicon microactuator are explored. Using finite-difference techniques, an electrothermal model based on the balance of heat dissipation and heat losses is developed. For accurate simulation, the relevant temperature dependent properties from the microactuator material are included in the model. The electrothermal model accurately predicts the steady-state power required to hold position, and the energy consumed during the thermal transient. Thermomechanical models use the predictions of temperature from the electrothermal solution to calculate displacement and force from pseudo-rigid-body approximations and commercial finite-element code. The models are verified by comparing experimental data to simulation results of a single leg-pair on a particular configuration of the device. The particular microactuator studied is called a Thermomechanical In-plane Microactuator, or TIM, and was fabricated with surface micromachining technology. A TIM requires a single releasable structural layer, is extremely flexible in design, and can operate with simple drive and control circuitry. The TIM produces linear motion of a center shuttle when slender legs on either side move the shuttle as a result of constrained thermal expansion. In a single example, when the current through a leg with dimensions 250×3×3.5 µm^3 and suspended 2 µm off the substrate is sufficient to maintain an average temperature of 615 C in air and vacuum environments, model simulated temperatures along the leg have a peak of 860 C in air and 1100 C in vacuum. The final measured and predicted displacement is 14 µm. In air, the power predicted by the model needed to maintain this average temperature profile is 95 mW while consuming 16.4 µJ in 0.22 ms to reach 90 percent of the final average temperature. In a vacuum, only 6.4 mW are required to maintain the same average temperature with 97.6 µJ consumed in 18.5 ms. Simulation results suggest that short-duration high-current pulses can improve the transient response and energy consumed in a vacuum when steady-state temperatures are not required. For a TIM leg with the dimensions above, the maximum measured force is approximately 47 µN per leg-pair when enough current is provided to move the TIM 8 µm as a result of ohmic heating and thermal expansion.

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35

Perumalsamy, Priya. "In-line Fiber Polarizer." Thesis, Virginia Tech, 1998. http://hdl.handle.net/10919/36897.

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Polarizers and polarization devices are important components in fiber optic communication and sensor systems. There is a growing need for efficient low loss components that are compatible with optical fibers. An all fiber in-line polarizer is a more desirable alternative that could be placed at appropriate intervals along communication links.

An in-line fiber polarizer was fabricated and tested. The in-line fiber polarizer operates by coupling optical energy propagating in the fiber to a surface plasmon on a metallic film, which has been deposited onto the surface of the fiber. The device was constructed by polishing a short section of the lateral surface of the cladding to within the evanescent field present around the fiber core. Several thin films including a metal film are applied to the polished section of the fiber. Ionic self-assembled monolayer method was used to coat the polished fiber with thin film.

Master of Science

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36

Allard, Nicolas. "Consequences of Machining on Roughness and Functions of Cylinder liners surfaces." Thesis, Halmstad University, School of Business and Engineering (SET), 2007. http://urn.kb.se/resolve?urn=urn:nbn:se:hh:diva-911.

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The cylinder liners’ surface is really important in an engine because it corresponds with piston rings to a tribologic system indispensable to know for reasons of wear, of oil consumption and engine’s life time. For these reasons, it is important to measure and characterize these surfaces.

The first part of the project is the observation of the impact of the number of strokes of the plateau honing on the surface of the cylinder liners. It is interesting to observe the impact of the variation of the number of strokes of the plateau honing on the peaks, plateaus and valleys of the surface.

The second part of the project is the simulation of the oil flow on the surface to observe the links between the roughness parameters and the oil flow and the shear stress.

The results are interesting, we will observe that the number of strokes of honing as a good impact on the quality of the surface.

In the second part of the project, the results show a correlation between the machining parameters and the roughness and functional parameters.

It could be interesting to mix the two parts of the project to see the correlation among machining, roughness and functional parameters for the samples made in the first of the project.

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37

Kuo, Betsy P. "Narrowing the molecular weight distribution of linear alcohol ethoxylates." Thesis, Georgia Institute of Technology, 1991. http://hdl.handle.net/1853/11773.

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Krywonos, Andrey. "PREDICTING SURFACE SCATTER USING A LINEAR SYSTEMS FORMULATION OF NON-PARAXIAL SCALAR DIFFRACTION." Doctoral diss., University of Central Florida, 2006. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/4218.

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Scattering effects from rough surfaces are non-paraxial diffraction phenomena resulting from random phase variations in the reflected wavefront. The ability to predict these effects is important in a variety of applications including x-ray and EUV imaging, the design of stray light rejection systems, and reflection modeling for rendering realistic scenes and animations of physical objects in computer graphics. Rayleigh-Rice (small perturbation method) and Beckmann-Kirchoff (Kirchhoff approximation) theories are commonly used to predict surface scatter effects. In addition, Harvey and Shack developed a linear systems formulation of surface scatter phenomena in which the scattering behavior is characterized by a surface transfer function. This treatment provided insight and understanding not readily gleaned from the two previous theories, and has been incorporated into a variety of computer software packages (ASAP, Zemax, Tracepro). However, smooth surface and paraxial approximations have severely limited the range of applicability of each of the above theoretical treatments. In this dissertation, a linear systems formulation of non-paraxial scalar diffraction theory is first developed and then applied to sinusoidal phase gratings, resulting in diffraction efficiency predictions far more accurate than those provided by classical scalar theories. The application of the theory to these gratings was motivated by the fact that rough surfaces are frequently modeled as a superposition of sinusoidal surfaces of different amplitudes, periods, and orientations. The application of the non-paraxial scalar diffraction theory to surface scatter phenomena resulted first in a modified Beckmann-Kirchhoff surface scattering model, then a generalized Harvey-Shack theory, both of which produce accurate results for rougher surfaces than the Rayleigh-Rice theory and for larger incident and scattering angles than the classical Beckmann-Kirchhoff theory. These new developments enable the analysis and simplify the understanding of wide-angle scattering behavior from rough surfaces illuminated at large incident angles. In addition, they provide an improved BRDF (Bidirectional Reflectance Distribution Function) model, particularly for the smooth surface inverse scattering problem of determining surface power spectral density (PSD) curves from BRDF measurements.
Ph.D.
Other
Optics and Photonics
Optics

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39

Provencher, Jerome R. "Afloat surface line commanding officer leadership : a comprehensive study." Thesis, Monterey, California. Naval Postgraduate School, 1992. http://hdl.handle.net/10945/25658.

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CIVINS
This thesis explored the leadership styles of Navy commanding officers of afloat commands to determine if there were any differences in leadership styles and the effect, if any, of rank, age, commissioning source, education, ethnicity, location, and ship community type that influenced that leadership style. A review of the literature indicated that the Navy adopted the Situational Leadership Model in 1976. The Navy concurred with the philosophy that there was no one style of leadership that was optimal in all situations, but rather, styles should change to reflect the existing circumstances and the readiness of subordinates. This study was conducted in January 1992 using sample responses from commanding officers and executive officers of Amphibious, Cruiser-Destroyer and Combat Logistic Forces around the world

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Seale, Richard Brent, and n/a. "The surface characteristics of spores from thermophilic bacilli isolated from a milk powder production line and their influence on adhesion to surfaces." University of Otago. Department of Food Science, 2009. http://adt.otago.ac.nz./public/adt-NZDU20091001.131237.

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Spores of thermophilic bacilli are a common concern during the manufacture of milk powder. Spores are believed to occur in high numbers in milk powder due to their ability to survive pasteurisation, attach to stainless steel surfaces, germinate, grow as biofilms and subsequently enter the product stream and thereby contaminate the final product. In this study, thirty one thermophilic bacilli isolates were obtained from a New Zealand milk powder production line and identified as either Anoxybacillus flavithermus or Geobacillus spp. using random amplified polymorphic DNA (RAPD) and species-specific PCR. Sporulation media and a polyethylene glycol two-phase separation system were modified to produce high yields of spores free from debris. The spores of four Geobacillus spp. isolates (CGT-8, D4, E7 and E11) were characterised in terms of structure (electron microscopy), surface charge (zeta potential), hydrophobicity (contact angle and microbial adhesion to hexadecane) and attenuated total reflectance infrared spectroscopy (ATR-IR). Spores from three of the four isolates possessed an exosporium while the fourth did not. However the integrity of the exosporium varied over time. The spores were negatively charged (-10 to -20 mV) at neutral pH and high ionic strength (0.1 M KC1). Both hydrophobicity assays revealed that the spores of the four isolates were relatively hydrophilic while ATR-IR revealed the spores' surfaces consisted of protein and polysaccharides. The influence of these spore characteristics on adhesion to a variety of substrata under high flow rates was examined using the extended Derjaguin, Landau, Verwey and Overbeek (XDLVO) theory. Spores generally attached in higher numbers to hydrophobic surfaces compared to hydrophilic surfaces, however this observation was more prevalent for isolate D4. This result indicated that a single mechanism could not describe the adhesion of spores from different strains. A series of glass surfaces with modified characteristics were produced in order to test the antifouling properties on the adhesion of D4 spores. Spores suspended in a high ionic strength medium (0.1 M KC1) attached in greater numbers (1 Log₁₀ CFU cm⁻�) to positively charged and hydrophobic surfaces compared with negatively charged and hydrophilic surfaces. A clean in place (CIP) procedure, reduced spore numbers on hydrophobic and hydrophilic surfaces by 1.5 and by 2.0 Log₁₀ CFU cm⁻�, respectively. When spores were suspended in milk, there was little difference in the number of spores attaching to the different surfaces (ie. 3.5 to 3.8 Log₁₀ CFU cm⁻�), and spore removal from surfaces via a CIP regime was unchanged (1.5 to 2.0 Log₁₀ CFU cm⁻� reduction) compared with spores that attached in simple 1:1 electrolyte media. The effects of a caustic wash on spore surface characteristics and adhesion was determined. There was a significant reduction in spore viability (2 Log₁₀ CFU mL⁻�) after a 30 min caustic wash at 65 �C in the current study, however surviving spores displayed a greater propensity to attach to stainless steel. Surface characterisation results revealed an increase in hydrophobicity and a greater negative charge on the spores' surface after treatment with NaOH. Surviving spores could potentially recontaminate sections of the plant which are cleaned with this recycled caustic wash solution, thereby seeding surfaces with spores at the beginning of the next processing run. In conclusion, while surfaces that reduce spore adhesion and enhance removal can be produced, exposure to complex solutions such as milk can reduce the anti-fouling effectiveness of such surfaces to spore adhesion.

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41

Robin, Ludovic. "Pointes AFM à nanotube de carbone pour la métrologie in-line de procédés de fonctionnalisations de surface." Thesis, Bordeaux, 2016. http://www.theses.fr/2016BORD0160/document.

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Actuellement, les recherches sur la fonctionnalisation des surfaces sont en pleine effervescence. Dans ce manuscrit, nous proposons une approche innovante pour mesurer l’efficacité de cette fonctionnalisation. Cette approche est basée sur l’utilisation d’un microscope à force atomique, opérant dans un mode dit de « modulation de fréquence ». Cet outil couplé aux pointes greffées d’un nanotube de carbone, que nous appellerons « sonde », permet d’obtenir des mesures qu’il serait impossible d’effectuer avec des pointes standards. En métrologie, afin d’assurer une bonne reproductibilité des mesures, nous avons besoin d’avoir des sondes ayant des caractéristiques les plus similaires possibles. Ceci a nécessité la mise en oeuvre d’une méthode pour optimiser la fabrication des sondes, ainsi qu’une définition de critères pour les classer dans différents grades de qualités. L’incertitude de répétabilité et de reproductibilité des mesures effectuées avec des sondes de grade « A » a été quantifiée. Ces mesures ont démontré que ces sondes sont compatibles en termes de robustesse et de sensibilité pour la caractérisation de surfaces fonctionnalisées, dont l’épaisseur est supérieure à la monocouche. Des mesures de cartographie effectuées sur de deux types de surfaces fonctionnalisées ont permis de dissocier la mesure de topographie de la réponse mécanique du nanotube en interaction avec la surface
At present, the researches on the surface functionalization are in full effervescence. In this manuscript, we propose an innovative approach to measure the efficiency of this functionalization. This approach is based on the use of an atomic force microscope, operating in a mode called "frequency modulation". This tool coupled with the grafted tips with a carbon nanotube, which we will call "probe", allows to obtain measurements which would be impossible to make with standard tips. However, in metrology, in order to ensure good reproducibility of the measurements, we need to have probes with characteristics that are as similar as possible. This required the implementation of a method to optimize the manufacture of the probes, as well as a definition of criteria to classify them in different grades of qualities. The uncertainty of repeatability and reproducibility of the measures made with probes of rank "A" were quantified. These measurements have demonstrated that these probes are compatible in terms of robustness and sensitivity for the characterization of functionalized surfaces, whose thickness is superior to the monolayer. Mapping measurements carried out on two types of functionalized surfaces enable to dissociate the topography measurement from the mechanical response of the nanotube in interaction with the surface

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42

DeFeo, Patrick A. "Sequential robust response surface strategy." Diss., Virginia Polytechnic Institute and State University, 1988. http://hdl.handle.net/10919/53687.

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General Response Surface Methodology involves the exploration of some response variable which is a function of other controllable variables. Many criteria exist for selecting an experimental design for the controllable variables. A good choice of a design is one that may not be optimal in a single sense, but rather near optimal with respect to several criteria. This robust approach can lend well to strategies that involve sequential or two stage experimental designs. An experimenter that fits a first order regression model for the response often fears the presence of curvature in the system. Experimental designs can be chosen such that the experimenter who fits a first order model will have a high degree of protection against potential model bias from the presence of curvature. In addition, designs can also be selected such that the experimenter will have a high chance for detection of curvature in the system. A lack of fit test is usually performed for detection of curvature in the system. Ideally, an experimenter desires good detection capabilities along with good protection capabilities. An experimental design criterion that incorporates both detection and protection capabilities is the A₂* criterion. This criterion is used to select the designs which maximize the average noncentrality parameter of the lack of fit test among designs with a fixed bias. The first order rotated design class is a new class of designs that offers an improvement in terms of the A₂* criterion over standard first order factorial designs. In conjunction with a sequential experimental strategy, a class of second order rotated designs are easily constructed by augmenting the first order rotated designs. These designs allow for estimation of second order model terms when a significant lack of fit is observed. Two other design criteria, that are closely related, and incorporate both detection and protection capabilities are the J_PCA, and J_PCMAX criterion. J_PCA, considers the average mean squared error of prediction for a first order model over a region where the detection capabilities of the lack of fit test are not strong. J_PCMAX considers the maximum mean squared error of prediction over the region where the detection capabilities are not strong. The J_PCA and J_PCMAX criteria are used within a sequential strategy to select first order experimental designs that perform well in terms of the mean squared error of prediction when it is likely that a first order model will be employed. These two criteria are also adopted for nonsequential experiments for the evaluation of first order model prediction performance. For these nonsequential experiments, second order designs are used and constructed based upon J_PCA and J_PCMAX for first order model properties and D₂ -efficiency and D-efficiency for second order model properties.
Ph. D.

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43

Middleman, Keith James. "The adsorption of linear and cyclic alkenes on metal single crystal surfaces." Thesis, University of Liverpool, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.343713.

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Zhang, Li Zhang Li. "Automatic digital surface model (DSM) generation from linear array images /." [S.l.] : [s.n.], 2005. http://e-collection.ethbib.ethz.ch/show?type=diss&nr=16078.

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45

Cable, Martin. "Surface characterisation of novel linear polyetherurethanes for blood contacting applications." Thesis, Brunel University, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.336645.

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46

Han, F. S. "Non-linear free surface problems using the boundary element method." Thesis, University of Manchester, 1987. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.378300.

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47

Veniani, Davide Cesare [Verfasser]. "Lines on K3 quartic surfaces / Davide Cesare Veniani." Hannover : Technische Informationsbibliothek (TIB), 2016. http://d-nb.info/1112954716/34.

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Maffucci, Riccardo Walter. "Nodal lines and surfaces of arithmetic random waves." Thesis, King's College London (University of London), 2018. https://kclpure.kcl.ac.uk/portal/en/theses/nodal-lines-and-surfaces-of-arithmetic-random-waves(daf91406-6414-4ca5-ae7f-78e36eb5632e).html.

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Abstract:

This thesis discusses various aspects of nodal sets of random Gaussian Laplace eigenfunctions (‘arithmetic random waves’) on the two- and three-dimensional tori. The first problem concerns the number of nodal intersections against a straight line segment in two dimensions. The expected intersections number, against any smooth curve, is universally proportional to the length of the ref-erence curve, times the wavenumber, independent of the geometry. I bounded the variance in the case of a straight line with rational slope. Without assuming rational slope, I proved that the same bound holds unconditionally for a density one sequence of energies, and conditionally for all energies. The three-dimensional analogue of the first problem is the study of the nodal intersections variance against a straight line segment on the three dimensional torus. I gave a bound for rational lines. For irrational lines, I proved an uncon-ditional result, and a stronger conditional result. I also found a better bound for irrational lines (a1, a2, a3) where a2/a1 is rational. The third problem is work in collaboration with J. Benatar. We studied the area of the nodal set in the three dimensional case. The expected area is proportional to the square root of the eigenvalue. We established an asymptotic formula for the nodal area variance. The methods involve the theory of random processes, the study of the covari-ance function and application of Kac-Rice formulas. The problems are closely related to the theory of lattice points on circles and spheres. I proved upper bounds for the number of lattice points on spheres that lie on a thin spher-ical segment, using Diophantine approximation. Together with J. Benatar, I bounded the number of non-degenerate 4-correlations, and 6-correlations, of lat-tice points on spheres.

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49

Alcolado, Adam. "Enumeration of real lines on smooth cubic surfaces." Thesis, McGill University, 2013. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=119517.

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In the nineteenth century, Cayley proved that a smooth cubic surface has exactly 27 lines over the complex field. Schläfli and others showed furthermore that the number of real lines could be 27, 15, 7, or 3. These results were found using the algebraic geometry techniques of the time. In this thesis, we solve this classic real enumeration problem using two different techniques. One method is group theoretic, and the other uses characteristic classes. Part of our goal is to show how these methods are related to each other as well as to the classical results. In particular, we give a description of important signs, which arise in both the classical and characteristic class approaches, in terms of our group theoretic approach. We also solve two other classic real enumerative problems using the group theoretic approach: the number of bitangent lines to a quartic plane curve, and the number of tritangent planes to a twisted sextic curve.
Pendant le dix-neuvième siècle, Cayley a prouvé qu'une surface cubique lisse contient exactement 27 droites sur le corps complexe. De plus, Schläfli et d'autres ont demontré que le nombre de droites réelles pourait être 27, 15, 7, ou 3. Ces résultats ont été découverts à travers des techniques de la géométrie algébrique de l'époque. Dans cette thèse, nous résolvons ce problème classique en utilisant deux techniques différentes. La première méthode utilise la théorie des groupes, et l'autre utilise des classes charactéristique. Notre but est, en partie, de démontrer comment ces méthodes sont reliées entre eux et, de plus, leurs relation aux résultats classiques. En particulier, nous donnons une description de signes importants, pro-venant de l'approche classique ainsi que l'approche des classes charactéristiques, du point de vu de la théorie des groupes. De plus, en utilisant l'approche des groupes, nous résolvons deux autres problèmes classiques en geométrie énumérative réelle : l'énumération des droites bi-tangentes à une courbe quartique du plan, et l'énumération des plans tritangents à une courbe tordu sextique.

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O'Dea, Enda. "Robust control of non-linear 2D and linear 3D disturbances in channel flow by surface transpiration." Thesis, University of Southampton, 2004. https://eprints.soton.ac.uk/47092/.

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The attenuation of perturbations in both periodic and non-periodic channel flow is attempted through wall-normal transcription and point wall-shear-stress measurements. The transcription is applied in both continuous harmonic form and a system based on discrete zero-net-mass-flux panel-pair form. For 2D flow it is demonstrated by means of a spectral Galerkin solver, that a simple classical controller with harmonic transpiration is capable of attenuating highly non-linear 2D perturbations. A multiple-input/multiple-output (MIMO) robust control scheme designed for the attenuation of perturbations in a non-periodic channel is applied to linear perturbations in the periodic setting. A certain set of linearly unstable modes in this periodic setting prove unstable for this control scheme. The significance of the last panel-pair in the scheme's failure in the presence of such modes is also demonstrated to continue to attenuate simple 2D perturbations in the presence of certain prescribed actuator/sensor faults. The identification of which faults are detrimental to the control demonstrates the importance of upstream actuators and downstream sensors respectively. Such observations may be useful in the design of fault tolerant control schemes. An ad-hoc extension of the 2D MIMO controller is applied to a 3D flow. A simple perturbation is initialised in the flow by an upstream panel pair

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Dissertations / Theses on the topic 'Liner surface'

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