Дисертації з теми "Solid contact"
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Hernández, Malo Rafael. "Solid contact potentiometric sensors based on carbon nanomaterials." Doctoral thesis, Universitat Rovira i Virgili, 2014. http://hdl.handle.net/10803/401334.
Повний текст джерелаEsta tesis aporta un avance en la construcción de electrodos de contacto sólido (SCE) basados en materiales nanoestructurados de carbono. Se verifica por una parte, la posibilidad de utilización de los nanotubos de carbono de capa simple (SWCNTs) para la determinación de iones en muestras reales complejas como es la savia vegetal. Adicionalmente, se lleva a cabo la utilización del grafeno modificado químicamente como elemento transductor en los electrodos de estado sólido determinando su mecanismo de transducción y como prueba de su funcionamiento se llevan a cabo dos electrodos, por una parte un electrodo selectivo de iones (ISE) para la determinación de calcio, y por otra parte, un aptasensor para la determinación selectiva de Staphylococcus aureus.
This thesis provides a breakthrough in the construction of solid contact electrode (SCE) based on nanostructured carbon materials. It is checked the possibility of using single walled carbon nanotubes (SWCNTs) for the determination of ions in real complex samples such as plant sap. Additionally, the use of chemically modified graphene is performed as a transducer in solid state electrodes to determine the transduction mechanism. As a proof of concept two electrodes have been developed, in one hand, an ion-selective electrode (ISE) for the determination of calcium, and on the other one, an aptasensor for the selective detection of Staphylococcus aureus.
Parel, Kurien Stephen. "An analysis of contact stiffness and frictional receding contacts." Thesis, University of Oxford, 2017. http://ora.ox.ac.uk/objects/uuid:3c29863a-b0cf-4870-851d-261be72f457f.
Повний текст джерелаPapillon, Anthony. "Frittage de composites Cu-Cr pour l'élaboration de matériaux de contact d'ampoules à vide." Thesis, Université Grenoble Alpes (ComUE), 2016. http://www.theses.fr/2016GREAI099.
Повний текст джерелаCu-Cr composites are commonly used as contact materials for medium voltage circuit breakers vacuum bottles. Solid state sintering process of Cu-Cr composites is widespread but has been relatively little studied. Optimizing the process requires understanding the sintering mechanisms. This study was focused on two important aspects of sintering: the redox reactions associated to oxides on the powder surface and the competition between densification and swelling mechanisms during sintering.The redox reactions were studied by thermogravimetric analysis coupled to various spectroscopic techniques, first on isolated Cu and Cr, then on Cu-Cr composites. Interfaces analyses obtained by FIB clarified the location of the oxide inside the sintered materials. Oxygen transfer takes place between copper and chromium powders. This phenomenon strongly depends on the reducing character of the sintering atmosphere.Densification was analyzed by dilatometry on Cu, Cr and Cu-Cr composites. This analysis was supported by microstructural observations, including X-ray tomography .The effect of process parameters (atmosphere, heating rate, powders ...) was studied. The results show the relationship between sintering and copper oxide reduction. The swelling phenomenon of copper compacts is explained by high temperature degassing of copper during pore closure. This swelling does not occur in Cu-Cr composites as chromium delays pore closing and entraps the gases released by copper. Sintering atmosphere, chromium morphology and chromium particle size affect densification. Vacuum sintering reduces porosity. Chromium particles with spherical shape limit its inhibiting effect on densification. For small particle sizes, chromium participates to densification, leading to better densification of the material. These results open the route for optimizing the sintering of Cu-Cr composites.Cu-Cr composites were tested for short circuit performance in vacuum interrupters. The result of these tests showed the importance of reducing the chromium oxide amount. The effect of impurities commonly encountered on the powders copper and chromium powders was also determined
Brunetti, Jacopo. "Mechanical energy balance of frictional contacts : From surface to solid energy dissipation in contact dynamic instabilities." Thesis, Lyon, INSA, 2015. http://www.theses.fr/2015ISAL0118/document.
Повний текст джерелаWhenever relative motion between two system components occurs, through a dry contact interface, vibrations are induced by the frictional contact. The local dynamics at the contact (ruptures and wave generation) couples with the system dynamics, giving origin to vibrations and affecting the macroscopic frictional behavior of the system. In this thesis, in order to develop an overall approach to the investigation of the multi-physic phenomenon, the energy has been pointed out as a coupling physical characteristic among the several phenomena at the different scales. The formulation of a mechanical energy balance is used for distinguishing between two different dissipative terms, i.e. the dissipation by material/system damping and the dissipation at the contact. The energy flows coming from the frictional surfaces, by friction induced vibrations, excites the dynamic response of the system, and vice versa the influence of the system dynamic response on the local energy dissipation at the contact interface affects the related tribological phenomena. The friction-induced vibrations have been analyzed using three different approaches: the finite element approach, to investigate the coupling between the contact and system dynamics by the analysis of the energy flows; the experimental approach to validate the numerical results and observe the influence of phenomena not still included into the numerical model; a lumped parameter model approach to quickly investigate the effects of the system parameters. The numerical analysis by the 2D finite element model allowed investigating the repartition of the energy introduced into the mechanical system between the two dissipative terms (material damping and contact) during both stable and unstable friction-induced vibrations. In particular, it has been shown how the friction-induced vibrations modify the overall capacity of the system to absorb and dissipate energy; an estimation of the power dissipated at the contact, without considering the dynamic behavior of the system (energy flows by friction induced vibrations) can lead to significant error in the quantification of the dissipated energy at the contact, which affects directly several tribological phenomena. The experimental squeal measurements show how the same unstable modes are recovered both experimentally and numerically, validating the use of the 2D transient simulations for the reproduction of the unstable friction-induced vibrations. Once the energy balance formulated, it has been used on the lumped model to approach the instability over-prediction issue characteristic of the complex eigenvalue analysis. By energy considerations, a newer instability index (MAI) has been defined to compare the different unstable modes and to select the mode that becomes effectively unstable during the transient response. The Modal Absorption Index allows quantifying the capability of each mode to exchange energy with the external environment
Crespo, Paravano Gastón Adrián. "Solid contact ion selective electrodes based on carbon nanotubes." Doctoral thesis, Universitat Rovira i Virgili, 2010. http://hdl.handle.net/10803/9050.
Повний текст джерелаPotentiometric classical ion selective electrodes (ISEs) have been used for analytical applications since the beginning of 1900's. Determination of pH by a glass membrane ion selective electrode emerged at the beginning, being the first ISEs developed. pH glass electrode is still one the most useful and robust sensors for routine measurements both in laboratories and industries.
Throughout the years, new technologies, ideas and designs have been developed and incorporated successfully in the potentiometric fields so as to provide answers to the new society's needs. Therefore, the ion selective electrodes developed in this thesis are a step further in the progress of ISEs and must be considered as products of the scientific envisioning, growth, and interdisciplinary cooperation of many research teams over many years of continuous efforts.
The sensing part can be regarded nowadays as well developed, although it has been during only the last few years when considerable improvements have taken place in the development of new polymeric membranes, ionophores and lipophilic ions. Moreover, the understanding of the theoretical sensing mechanism has been a powerful solid backbone in the rise of ISEs.
Miniaturization of classical ISEs requires making all solid contact electrodes to avoid the intrinsic drawbacks of the inner solution. In this manner, the transduction layer has been the focus of attention for the two last decades. New solid contact transducers having the capacity to convert an ionic current into an electronic current have been emerging. Within them, conducting polymers have played an important role in the transduction of the potentiometric signal, being the most used in solid contact ion selective electrodes (SC-ISEs) up to now. However, the behaviour of conducting polymers can be further improved. For instance, their sensitivity to light one of main operational issues yet to be solved.
In the present context of searching for new materials able to transduce potentiometric signals we selected and tested carbon nanotubes (CNTs). CNTs, which were rediscovered by Ijima in 1991, display excellent electronic properties in terms of signal transduction. In addition, due to their chemical reactivity CNTs can be easily functionalized with receptors or other functional groups. In fact, depending on the type of functionalization the macroscopic and microscopic properties of CNTs can be drastically changed. This nanostructured material had not been used previously as a solid contact material in ISEs.
The main aim of this thesis is to demonstrate that CNTs can act as a clean and efficient transducer in SC-ISEs overcoming the drawbacks displayed by the previously assayed solid contact materials. The developed electrodes were used in different conditions to determine several ions in different sample types, demonstrating the capabilities of this nanostructured material.
The thesis has been structured in different chapters, each one containing the following information:
· Chapter 1 provides a short historical overview of potentiometric ISEs. The evolution from the "classical ISEs" to the SC-ISEs is briefly illustrated. Once the motivation for thesis is described, the general and specific objectives of the thesis are reported.
· Chapter 2 reports the scientific foundations of the developed electrodes. All components of the ISE, sensing layer, transducers and detection systems are introduced. Analytical performance characteristics of ISEs are also described.
· Chapter 3 corresponds to the experimental part. Reagents, protocols, procedures and instruments used in the thesis are reported.
· Chapter 4 provides the demonstration that CNTs can act as a transducer layer in SC-ISEs. The first SC-ISEs based on CNTs are characterized by electrochemical and optical techniques.
· Chapter 5 contains the experimental results that lead to the elucidation of the possible transduction mechanism of CNTs in SC-ISEs. Electrochemical impedance spectroscopy (EIS) is employed as the main characterization technique.
· Chapter 6 is composed of four sections reporting different analytical applications. In the first section, the common pH electrode is developed using a solid contact technology based on CNTs. In the second section, the development of SC-ISEs based on a new synthetic ionophore selective to choline, and CNTs as transducers is shown. In the third section, watertight and pressure-resistant SC-ISEs based on CNTs are developed and tested in aquatic research to obtain information about the gradient profiles along the depth of the lakes. In the fourth section, SC-ISEs based on CNTs are adapted for the on-line control of a denitrification catalytic process.
· Chapter 7 reports the possibilities of miniaturization of the SC-ISEs based on CNTs to reach a nanometric electrode. Potentiometric and optical characterizations are described in this section. Moreover, a discussion about the limitations of the real miniaturization in potentiometry is undertaken.
· Chapter 8 points out the conclusions of the thesis. In addition, future prospects are suggested.
· Finally, several appendices are added to complete the doctoral thesis.
El principal objetivo de esta tesis es el desarrollo de electrodos selectivos de iones de contacto sólido, ESIs-CS, utilizando como capa transductora una red compuesta de nanotubos de carbono.
Los electrodos potenciométricos selectivos de iones han sido utilizados en aplicaciones analíticas desde comienzos de 1900. La determinación de pH mediante electrodos de vidrio selectivo de iones fue el primer ESI desarrollado. Hoy en día, el electrodo de vidrio para la determinación de pH es todavía uno de los más útiles y robustos sensores utilizados en mediciones rutinarias tanto en laboratorios como en industrias.
A lo largo de los años, nuevas tecnologías, ideas y diseños han sido desarrollados e incorporados satisfactoriamente en el campo potenciométrico proporcionando soluciones a las necesidades en continua evolución de la sociedad. De esta manera, los electrodos selectivos de iones desarrollados en esta tesis son un paso más en el progreso de los ESIs y deben ser considerados como el producto de una sólida base científica, del crecimiento y de la cooperación interdisciplinaria de diversos grupos de investigación durante varios años.
La parte del sensor donde tiene lugar el reconocimiento químico y donde se genera el potencial dependiente de la muestra en estudio en los ESIs se puede considerar, en estos días, ampliamente desarrollada, aunque considerables mejoras han tenido lugar durante los últimos años, especialmente en el desarrollo de nuevas membranas poliméricas, ionóforos e iones lipofílicos. Sobretodo, el estudio y la comprensión del mecanismo teórico del sensor ha sido muy importante en el crecimiento y desarrollo de los ESIs.
El concepto de electrodos selectivos de iones de estado sólido surge como requisito vital para evitar las intrínsecas desventajas de la solución interna, en el proceso de miniaturización de los ESIs clásicos. De esta forma, la capa transductora ha sido el principal punto de atención durante dos décadas. Así, nuevos transductores de contacto sólido con la capacidad de convertir una corriente iónica en una corriente electrónica han sido desarrollados. Entre ellos, los polímeros conductores han jugado un importante papel en la transducción de la señal potenciométrica, siendo éstos los más empleados en los electrodos selectivos de iones de contacto sólido (ESIs-CS). Sin embargo el comportamiento de los polímeros conductores puede ser mejorado. Por ejemplo, la sensibilidad hacia la luz de estos materiales es un inconveniente todavía no resuelto.
En este contexto de investigación de nuevos materiales capaces de actuar como transductor de una señal potenciométrica, se han escogido y estudiado los nanotubos de carbono (NTCs) como transductores. Los NTCs fueros redescubiertos por Ijima en 1991, y muestran excelentes propiedades electrónicas en términos de traducción de señal. Además, debido a su reactividad química, los NTCs pueden ser fácilmente funcionalizados con receptores u otros grupos funcionales. De hecho, sus propiedades macroscópicas y microscópicas pueden ser afectadas drásticamente dependiendo del tipo y grado de funcionalización. Este material nanoestructurado no había sido previamente utilizado como transductor en ISEs.
El principal propósito de esta tesis es demostrar que los nanotubos de carbono pueden actuar de forma eficiente como transductor en electrodos selectivos de iones de estado sólido logrando vencer las desventajas de los transductores previamente mencionados. Los electrodos desarrollados fueron usados en diferentes condiciones para determinar distintos iones en diversos tipos de sistemas, demostrando las extraordinarias capacidades de este material nanoestructurado.
Esta tesis ha sido estructurada en capítulos que contienen la siguiente información:
· El Capítulo 1 proporciona una breve visión histórica de lo electrodos potenciométricos selectivos de iones. Se ilustra la evolución desde los "clásicos ESIs" hasta los actuales "ESIs-CS". Además se señalan en esta sección los objetivos generales y específicos.
· El Capitulo 2 contiene las bases científicas de los electrodos desarrollados. Se introducen todos los componentes que integran un ESI, tales como: capa reconocedora, capa transductora y sistema de detección. A continuación se describen los parámetros analíticos de calidad de los ESIs.
· El Capitulo 3 describe la parte experimental. Se recogen los reactivos, protocolos, procedimientos e instrumentos usados a lo largo de la tesis.
· El Capitulo 4 provee de la demostración de que los NTCs pueden actuar eficientemente como capa transductora en SC-ISEs. Se caracteriza el primer ESI-CS integrado por NTCs mediante técnicas ópticas y electroquímicas.
· El Capitulo 5 contiene los resultados experimentales que permiten la posible elucidación del mecanismo de transducción de los NTCs en los ESIs-CS. La Espectroscopia de Impedancia Electroquímica (ESI) es utilizada como la principal técnica de caracterización.
· El Capitulo 6 está integrado por cuatro secciones con diferentes aplicaciones analíticas. En la primera sección, se desarrolla un electrodo de pH que usa NTCs como nueva tecnología transductora en ESIs-CS. En la segunda sección se muestra el desarrollo de un ESI-CS integrado por un ionóforo sintético selectivo a colina, y NTCs como transductores. En la tercera sección, ESIs-CS basados en NTCs, resistentes a altas presiones y totalmente herméticos, se desarrollan y prueban en investigaciones acuáticas con la finalidad de obtener información sobre los gradientes de concentración de iones en función de la profundidad de un lago. En la cuarta sección ESIs-CS basados en NTCs se adaptan para el control on-line de un proceso catalítico de desnitrificación.
· El Capitulo 7 presenta la posibilidad de la miniaturización de los ESIs-CS basados en NTCs logrando obtener un electrodo nanométrico. Se muestran en esta sección la caracterización óptica y potentiométrica. Además, se discuten las limitaciones de la miniaturización real de los ESIs en potenciometría.
· El Capitulo 8 contiene las conclusiones de la tesis. Adicionalmente, se sugieren las perspectivas futuras del trabajo presentado.
· Finalmente, se añaden algunos apéndices como complemento de la tesis doctoral.
Mukherjee, Manas. "Bubble Solid Interaction." Thesis, Indian Institute of Science, 2004. http://hdl.handle.net/2005/78.
Повний текст джерелаPham, Phong Ngoc. "Origin of shear-induced diffusion in particulate suspensions : crucial role of solid contacts between particles." Thesis, Aix-Marseille, 2016. http://www.theses.fr/2016AIXM4706/document.
Повний текст джерелаEven at low Reynolds number, particles within a shear flow exhibit irreversible dynamics. Many theories have been put forth to explain this phenomenon, the origin of irreversibility remains unclear. An integrated program of experimental and computational studies has been performed to assess the origin of the irreversible behavior of particles. Numerical simulations were used to evaluated the relative importance of long-range hydrodynamic interactions, lubrication, and contact forces. By isolating contribution of these interactions, we have shown that neither the long-range hydrodynamic interactions nor the lubrication are responsible for irreversibility. Solid contacts between particles largely dominate this phenomenon. However, producing realistic results requires both contact interactions and lubrication. Two different experiments were performed to address the role of contacts between particles in sheared suspensions. In the first experiment, the particle trajectories are irreversible during the first cycle but reversible for the next cycles. By showing that the magnitude of irreversibility increases with the particle roughness, we provide direct evidence that contacts occur in viscous flow. Experimental particle trajectories are well captured by the numerical model. In the second experiment, performed in a homogeneous suspension, the role of solid collisions was also revealed by showing that the critical strain amplitude depends on the particle roughness. A geometrical model based on the assumption that colliding particles produce irreversibility was derived. The model successfully reproduces the measured values of the critical strain amplitude
Jelagin, Denis. "Frictional Effects on Hertzian Contact and Fracture." Doctoral thesis, KTH, Hållfasthetslära (Avd.), 2007. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-4535.
Повний текст джерелаQC 20100729
Hahn, Carsten. "Models, algorithms and software concepts for contact and fragmentation in computational solid mechanics /." Hannover : Institut für Baumechanik und Numerische Mechanik, 2006. http://bvbr.bib-bvb.de:8991/F?func=service&doc_library=BVB01&doc_number=015469864&line_number=0001&func_code=DB_RECORDS&service_type=MEDIA.
Повний текст джерелаZhang, Yilei. "The effect of surface roughness parameters on contact and wettability of solid surfaces." [Ames, Iowa : Iowa State University], 2007.
Знайти повний текст джерелаRutherford, Christine Elizabeth. "Contact angles in relation to the effects of solid particles on foam stability." Thesis, University of Hull, 1995. http://hydra.hull.ac.uk/resources/hull:14124.
Повний текст джерелаWretborn, Joel. "Modelling cracks in solid materials using the Material Point Method." Thesis, Linköpings universitet, Institutionen för fysik, kemi och biologi, 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-136797.
Повний текст джерелаDonev, Jason Matthew Kaiser. "Non-contact atomic force microscopy studies of amorphous solid water deposited on Au(111) /." Thesis, Connect to this title online; UW restricted, 2003. http://hdl.handle.net/1773/9779.
Повний текст джерелаFrost, Daniel Wayne. "Study of adsorption of biological and nanoparticle solutions at the solid-liquid interface." Manhattan, Kan. : Kansas State University, 2007. http://hdl.handle.net/2097/411.
Повний текст джерелаPerrin, Hugo. "Lignes de contact dynamiques à l'échelle microscopique." Thesis, Sorbonne Paris Cité, 2017. http://www.theses.fr/2017USPCC287/document.
Повний текст джерелаThis thesis reveals two dissipative microscopic phenomena close to the contact line in the fields of capillarity and adhesion. The study is based on dynamic experiments and theoretical predictions. Experimental measurement of macroscopic quantities and the hydrodynamic theory give access to dynamic information located close to the contact line. The different dissipative phenomena, located close to the contact line, originate from the properties of the substrates on which the contact line moves. For a heterogeneous rigid surface, we have developed a rheological model of the contact line based on hydrodynamics, in order to theoretically establish the temporal evolution of the contact line and its deformations. A modal decomposition based on the reduction of the energy by the reaction path theory allows a quantitative prediction of the thermally activated dynamics of the contact line, in agreements with the experiment carried out. For a deformable substrate, based on the analysis of two different experiments of wetting dynamics and on the estimation of the dissipation in the substrate founded on its viscoelasticity, a general understanding of the dynamical behavior of contact lines on viscoelastic substrates is achieve. Finally, this viscoelastic model is applied to the case of weak adhesion, where experimentally we measured the peeling dynamics from a viscoelastic substrate. This extension to adhesion bridge the gap between different interfacial phenomena into a general understanding
Hannes, Dave. "Growth of cracks at rolling contact fatigue." Thesis, KTH, Hållfasthetslära (Avd.), 2008. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-33659.
Повний текст джерелаUtmattning med rullande kontakter är ett ofta förekommande problem för många maskinelement. I den aktuella rapporten utfördes en numerisk studieför att förutsäga sprickvägen hos utmattningssprickor som initierats i ytan vidrullande kontakter. Implementeringen av kontaktproblemet bygger på asperitpunktlastmekanismen för rullande kontakter. Studien av kontaktproblemetär tillämpad till kugghjul. Olika belastningstyper och modeller studeradesoch jämfördes med profilen hos en experimentell spall. Bra överensstämmelseobserverades för korta spricklängder när en modell med fördelad belastninganvänds för en belastningstyp där en normalbelastning agerar på asperiten ochvid cylindriska kontakten och en tangentialbelastning införs på asperiten. Olikakriterier för spricktillväxt implementerades för att verifiera giltigheten av antagandetatt mode I spricktillväxt är dominant. Några generella kännetecken avutmattningssprickor med rullande kontakter framhävdes. En kvantitativ parameterstudie för den implementerade modellen utfördes.
Parra, Arnó Enrique José. "New appoaches for the development of solid-contact ion-selective electrodes based on carbon nanotubes." Doctoral thesis, Universitat Rovira i Virgili, 2012. http://hdl.handle.net/10803/79134.
Повний текст джерелаThis Doctoral Thesis intends to provide an insight into the design, construction and operation of solid contact ion-selective electrodes (SC-ISEs) based on multi-walled carbon nanotubes (MWCNTs). MWCNTs are used as effective ion-to-electron transducers for SC-ISEs. Additionally, new hybrid materials with the receptor covalent and non-covalent linked to the MWCNTs have been developed for determination of ions. And finally, new polymeric matrix based on poly vinyl butyral is introduced as an alternative to conventional matrixes based on poly(vinyl chloride).
Mao, Bosi. "Dynamics of agar-based gels in contact with solid surfaces : gelation, adhesion, drying and formulation." Thesis, Bordeaux, 2017. http://www.theses.fr/2017BORD0593/document.
Повний текст джерелаMy PhD work was carried out in partnership with the company BioMérieux, a leader int he production of agar-based culture media, cast in Petri disches and used in microbioly. Being mainly composed of water (>95 % wt.), agar gels are naturally prone to solvent-loss by evaporation either at rest or under an external perturbation. As a result, the gel shrinks and detaches from the sidewall fo dish. The goal of my PhD work was to identify the key paramters driving the gel detachment, in relation with both the gel chemical composition, as well as the dish surface properties. This expzrimental word has allowed me to use a wide array of thecniques such as normal force controlled rheology, intererometric observations, or optical flow analysis applied to the gel deformation. I succesfully unravelled the driving forces that lead to the gel detachment from the sidewall of the dish and proposed concrete solutions to be implemented on a commercial scale to prevent il
Wilkinson, Lucas T. "Silver-perovskite composite materials for SOFC cathode-interconnect contact a thesis presented to the faculty of the Graduate School, Tennessee Technological University /." Click to access online, 2009. http://proquest.umi.com/pqdweb?index=23&sid=1&srchmode=1&vinst=PROD&fmt=6&startpage=-1&clientid=28564&vname=PQD&RQT=309&did=1760523391&scaling=FULL&ts=1250866302&vtype=PQD&rqt=309&TS=1250866321&clientId=28564.
Повний текст джерелаRadulescu, Fabian. "Pd-Ge ohmic contact on to GaAs formed by the solid phase epitaxy of Ge : a microstructure study /." Full text open access at:, 2000. http://content.ohsu.edu/u?/etd,226.
Повний текст джерелаQi, Jia. "Measurement of Surface and Interfacial Energies between Solid Materials Using an Elastica Loop." Thesis, Virginia Tech, 2000. http://hdl.handle.net/10919/35442.
Повний текст джерелаMaster of Science
Xiong, Hu. "Simulation of forming, compaction and consolidation of thermoplastic composites based on solid shell elements." Thesis, Lyon, 2017. http://www.theses.fr/2017LYSEI085/document.
Повний текст джерелаAs the pre-impregnated thermoplastic composites have recently attached increasing interest in the automotive industry for their excellent mechanical properties and their rapid cycle manufacturing process, modelling and numerical simulations of forming processes for composites parts with complex geometry is necessary to predict and optimize manufacturing practices. This thesis is devoted to modelling and simulation of the consolidation behavior during thermoplastic prepreg composites forming process. A new seven-node prismatic solid-shell element is proposed: six located at the apexes and the seventh sited at the center. A shear stain field is assumed to subdue transverse shear locking, the enhanced assumed strain method by addition of an extra displacement DOF from the central node and a reduced integration scheme are combined offering a linear varying strain field along the thickness direction to circumvent thickness locking, and an hourglass stabilization procedure is employed in order to correct the element’s rank deficiency for pinching. This element permits the modelling of three-dimensional constitutive behavior of thermoplastic prepreg with the consolidation effect, which is modelled by a viscoelastic relaxation model. An intimate contact model is employed to predict the evolution of the consolidation which permits the microstructure prediction of void presented through the prepreg. Within a hyperelastic framework, several simulation tests are launched by combining the new developed finite element and the consolidation models. The comparison with conventional shell element and experimental results shows the efficiency of the proposed solid-shell element not only dealing with the in-plan deformation and bending deformation problems, but also in analyzation of the consolidation behavior, and the degree of intimate contact provides the level of consolidation by applied process conditions, which is essential for the appearance of defects in final composite part
Bendada, Abdelhakim. "Tomographie infrarouge stimulée : estimation d'une résistance d'interface non uniforme." Vandoeuvre-les-Nancy, INPL, 1995. http://docnum.univ-lorraine.fr/public/INPL_T_1995_BENDADA_A.pdf.
Повний текст джерелаLe, Bars Theo. "Investigation of the behaviour of return collectors on Paris’ subway MP05 (Line 1)." Thesis, KTH, Järnvägsteknik, 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-159281.
Повний текст джерелаGreen, Christopher K. "Development of Model for Solid Oxide Fuel Cell Compressive Seals." Diss., Georgia Institute of Technology, 2007. http://hdl.handle.net/1853/19696.
Повний текст джерелаShoulders, Jacky. "Cathode-side contact materials with high sinterability for intermediate temperature SOFC applications a thesis presented to the faculty of the Graduate School, Tennessee Technological University /." Click to access online, 2009. http://proquest.umi.com/pqdweb?index=14&did=1908036121&SrchMode=1&sid=2&Fmt=6&VInst=PROD&VType=PQD&RQT=309&VName=PQD&TS=1264176901&clientId=28564.
Повний текст джерелаGiovanna, Lacerra. "Friction-Induced Vibrations as a result of system response and contact dynamics : A newer friction law for broadband contact excitation." Thesis, Lyon, 2017. http://www.theses.fr/2017LYSEI118/document.
Повний текст джерелаFriction-Induced Vibrations (FIV) are a complex phenomenon which arises each time two surfaces undergo relative sliding. During the last decades, a significant amount of experimental and numerical works dealt with Friction-Induced Vibrations, while the simulation of the dynamic excitation from frictional contacts has always been a real challenge to face in many industrial research areas. In this research framework, this work is addressed to the investigation of the Friction-Induced Vibrations, carrying on at the same time experimental and numerical analyses; a new numerical approach is proposed to reproduce the local dynamic excitation from the contact and its effect on the vibrational response of the system, without significant increase of the computational time costs. The mechanical system, object of the investigation, is composed by two steel beams in frictional contact during relative motion; the simple dynamics of the system allows for distinguishing between the dynamics response of the system and the broadband excitation coming from the contact. A parametrical experimental campaign has been conducted to analyse the effects of three main contact parameters (the relative sliding velocity, the normal load and the surface roughness) on the system vibrational response, i.e. on the induced vibrations. In parallel, a numerical model has been implemented to reproduce the local dynamic excitation from the contact and its effect on the vibrational response of the system. A new friction law has been introduced in the model, proposing the use of a perturbative term in the friction coefficient in order to simulate the effects of the contact excitation. The inclusions of the local dynamic excitation, due to the contact phenomena, by the perturbation term of the friction coefficient allows to correctly reproduce the Friction-Induced Vibrations without introducing a representation of the real surface topography, which usually needs a large number of elements, saving then computational time. Different signals for the perturbative term have been tested to simulate correctly the measured vibrations. The evolution of the perturbative term recovered by an inverse method allowed for highlighting the different spectral contributions of the local excitation coming from the contact. The comparison between the measured Friction-Induced Vibrations and the ones simulated numerically showed good correlation, validating the proposed friction law. Finally, the effect in a change of the sliding velocity and surface roughness have been simulated numerically too and correlated with experimental results
Martin, Sylvain. "Contribution à la modélisation du frittage en phase solide." Thesis, Compiègne, 2014. http://www.theses.fr/2014COMP2144/document.
Повний текст джерелаThis thesis deals with the simulation of the sintering of nuclear fuel on a pellet scale. The goal is to develop numerical tools which can contribute to a better understandingof the physical phenomena involved in the sintering process. Hence, a multi scale approach is proposed. First of all, a Discrete Element model is introduced. It aims at modeling the motion of particles on a Representative Elementary Volume scale using an original Discrete Element Method. The latter is a Non Smooth Method called Contact Dynamics. Recently, there have been numerous papers about the simulation of sintering using Discrete Element Method. As far as we know, all these papers use smooth methods. Different studies show that the results match well experimental data. However, some limits come from the fact that smooth methods use an explicit scheme which needsvery small time steps. In order to obtain an acceptable time step, the mass of particles have to be dramatically increased. The Non Smooth Contact Dynamics uses an implicit scheme, thus time steps can be much larger without scaling up the mass of particles. The comparison between smooth and non smooth approaches shows thatour method leads to a more realistic representation of rearrangement. An experimental validation using synchrotron X-Ray microtomography is then presented, followedby a parametric study on the sintering of bimodal powders that aims at showing the capacity of this model.The second part presents a mechanical model on the sub-Granular scale, using a Finite Element method. This targets a better understanding of the behavior of twograins in contact. The model is currently being developped but the first results already show that some parameters like the shape of the surface of the neck are very sensitive.In the future, the Non smooth Contact Dynamics model of sintering may be improvedusing the results obtained by the sub-Granular scale mechanical model
Young, Mimy. "Evaluation of Non-Contact Sampling and Detection of Explosives using Receiver Operating Characteristic Curves." FIU Digital Commons, 2013. http://digitalcommons.fiu.edu/etd/994.
Повний текст джерелаNeto, Dorival Piedade. "On the Generalized Finite Element Method in nonlinear solid mechanics analyses." Universidade de São Paulo, 2013. http://www.teses.usp.br/teses/disponiveis/18/18134/tde-20012014-094606/.
Повний текст джерелаO Método dos Elementos Finitos Generalizados (MEFG) é um método numérico baseado no conceito de partição da unidade (PU) e inspirado no Método da Partição da Unidade (MPU) e o método das Nuvens-hp. De acordo com o MEFG, a PU é obtida por meio de funções de interpolação Lagragianas de primeiro grau, definidas sobre uma rede de elementos similar àquela do Método dos Elementos Finitos (MEF). De fato, o MEFG pode ser considerado uma extensão do MEF para a qual se pode aplicar enriquecimentos em regiões específicas do domínio, buscando melhorias na solução. Esta técnica já foi aplicada com sucesso em problemas com descontinuidades e singularidades, como os originários da Mecânica da Fratura. Apesar disso, a maioria das publicações sobre o método está relacionada a análises lineares. A presente tese é uma contribuição aos poucos estudos relacionados a análises não-lineares de Mecânica dos Sólidos por meio do MEFG. Um de seus principais tópicos é o desenvolvimento de um elemento de contato generalizado do tipo segmento a segmento baseado no método mortar. Fenômenos não lineares devidos ao material e à cinemática também são considerados nos modelos numéricos. Um projeto de orientação a objetos para a implementação de uma plataforma de análises não-lineares foi desenvolvido, escrito em linguagem de programação Python. Os resultados validam a formulação e demonstram os ganhos e possíveis desvantagens da abordagem a problemas não lineares por meio do MEFG.
Doyen, David. "Numerical methods for dynamic contact and fracture problems." Phd thesis, Université Paris-Est, 2010. http://tel.archives-ouvertes.fr/tel-00596029.
Повний текст джерелаLiedtke, Anne-Kathrin. "Study of a new gas-liquid-solid three phase contact mode at millimetric scale : catalytic reactors using “slurry Taylor” flow." Thesis, Lyon 1, 2014. http://www.theses.fr/2014LYO10137/document.
Повний текст джерелаSlurry reactors, widely encountered in chemical industry (laboratory scale up to manufactaring), offer good mass and heat transfer capacities and their high flexibility ensures the simple changeover of solid phases enables a continuous online fresh catalyst feed for fast deactivating catalysts. However slurry reactors promote a high degree of backmixing which can be a drawback for reactions with selectivity issues or when very high conversions are required. In microreaction technology, Taylor flow is often employed providing excellent heat and mass transfer and almost ideal plug flow behavior. Solid handing in these small structures is often resolved by immobilizing the solid catalyst which impinges on the flexibility. One possible solution to combine beneficial properties of Taylor flow with the operational flexibility of conventional slurry reactors is a “slurry Taylor” flow (STF) where catalyst particles are suspended and kept in motion by the internal circulations present in the liquid slugs. The focus of this work is the design and characterization of this innovative gas-liquid-solid contactor. Particles were transported in millimetric horizontal and vertical tubing without the risk of clogging. Hydrodynamic studies revealed different flow patterns depending mainly on velocity and flow orientation. Ion exchange resin particles were used to study the liquid-solid mass transfer and first correlation for the Sherwood number in STF is proposed
Flicek, Robert C. "Analysis of complete contacts subject to fatigue." Thesis, University of Oxford, 2015. http://ora.ox.ac.uk/objects/uuid:10c6e429-4e9e-45f0-a7a6-21823592043b.
Повний текст джерелаCai, Shaobiao. "3D numerical modeling of dry/wet contact mechanics for rough, multilayered elastic-plastic solid surfaces and effects of hydrophilicity/hydrophobicity during separation with applications." Columbus, Ohio : Ohio State University, 2008. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=osu1205118488.
Повний текст джерелаTreguer, Véronique. "Recherche des conditions optimales de mise en contact de particules solides et de gouttelettes dans un réacteur à jets : application au craquage catalytique." Vandoeuvre-les-Nancy, INPL, 1995. http://docnum.univ-lorraine.fr/public/INPL_T_1995_TREGUER_V.pdf.
Повний текст джерелаSabbagh, Lamis Marlyn Kenedy. "Study of rigid solids movement in a viscous fluid." Thesis, Montpellier, 2018. http://www.theses.fr/2018MONTS103/document.
Повний текст джерелаThis thesis is devoted to the mathematical analysis of the problem of motion of afinite number of homogeneous rigid bodies within a homogeneous incompressible viscous fluid. Viscous fluids are classified into two categories: Newtonian fluids, and non-Newtonian fluids. First, we consider the system formed by the incompressible Navier-Stokes equations coupled with Newton’s laws to describe the movement of several rigid disks within a homogeneous viscous Newtonian fluid in the whole space R^2. We show the well-posedness of this system up to the occurrence of the first collision. Then we eliminate all type of contacts that may occur if the fluid domain remains connected at any time. With this assumption, the considered system is well-posed globally in time. In the second part of this thesis, we prove the non-uniqueness of weak solutions to the fluid-rigid body interaction problem in 3D in Newtonian fluid after collision. We show that there exist some initial conditions such that we can extend weak solutions after the time for which contact has taken place by two different ways. Finally, in the last part, we study the two-dimensional motion of a finite number of disks immersed in a cavity filled with a viscoelastic fluid such as polymeric solutions. The incompressible Navier–Stokes equations are used to model the flow of the solvent, in which the elastic extra stress tensor appears as a source term. In this part, we suppose that the extra stress tensor satisfies either the Oldroyd or the regularized Oldroyd constitutive differential law. In both cases, we prove the existence and uniqueness of local-in-time strongsolutions of the considered moving-boundary problem
Ager, Christoph Franz [Verfasser], Wolfgang A. [Akademischer Betreuer] Wall, Wolfgang A. [Gutachter] Wall, and Marek [Gutachter] Behr. "Computational Methods for Fluid-Structure Interaction including Porous Media and Solid Contact / Christoph Franz Ager ; Gutachter: Wolfgang A. Wall, Marek Behr ; Betreuer: Wolfgang A. Wall." München : Universitätsbibliothek der TU München, 2021. http://d-nb.info/1230985131/34.
Повний текст джерелаSimon, Samuel. "De la dynamique ferroviaire à l’accommodation microstructurale du rail : Contribution des TTS à la réponse tribologique des aciers : Cas du défaut de squat." Thesis, Lyon, INSA, 2014. http://www.theses.fr/2014ISAL0028/document.
Повний текст джерелаSquats have recently become recognised as one of the major rolling contact fatigue defects in modern railway networks for which there is currently no solution other than preventive grinding operations or costly rail renewal. To better understand the entire damage mechanism of squat, A tribological and metallurgical analysis of the rolling band and the near surface layer was performed close to an incipient squat. This characterization show a significant anisotropy of the rail surface layer associated with developments of Tribological Transformation of Surface. These results reflect some specific wheel/rail contact conditions in this squat area, including an unusual level of shear forces in a straight track. In order to validate this observations, two tests were performed. On the one hand, the contact conditions in a squat area were measured from an instrumented train. On the other hand, the tribological response of the rail steel was studied through regular monitoring of a test site subjected to railway traffic. These tests allow to identify a high imbalance of the traction forces and the presence of local slips at the wheel/rail interface. Several thermomechanical initiation mechanism of squats are then given in a overall diagram of the tribological response of rail steels
Alois, Stefano [Verfasser], Jörn [Akademischer Betreuer] Sesterhenn, Jörn [Gutachter] Sesterhenn, and Manfred [Gutachter] Lane. "Contact electrification in aerosolized micron-sized solid particles: dependence upon size, chemical composition and gas properties / Stefano Alois ; Gutachter: Jörn Sesterhenn, Manfred Lane ; Betreuer: Jörn Sesterhenn." Berlin : Technische Universität Berlin, 2019. http://d-nb.info/1176623559/34.
Повний текст джерелаLopez, Claire. "Synthèse de polymères à empreintes moléculaires d'alcaloïdes Vinca pour leur extraction sur phase solide dans des extraits de plantes ou des fluides biologiques : développement du détecteur conductimétrique sans contact à couplage capacitif et de la technique de la double injection en électrophorèse capillaire." Thesis, Orléans, 2010. http://www.theses.fr/2010ORLE2078.
Повний текст джерелаThis thesis reports in a first part results obtained with molecularly imprinted polymers (MIP) during solid liquid extraction. Polymer-analyte interactions, composition of the sample matrix and selectivity of MIPs have been studied.The first application concerned the extraction of molecules in a plant extract. Two MIPs respectively prepared from the methacrylic acid (MAA) and itaconic acid ( IA) and with respectively catharanthine and vindoline as template showed their selectivity on standard solutions then on a plant extract. Experiments of cross reactivity performed with analogue of the template (dimers alkaloids) have proved the specificity of analytes recognition by the MIPs. The MIP-catharanthine is characterized by Scatchard isotherms and its capacity was estimated from the extract of Catharanthus roseus. A MIP prepared from MAA with the vinorelbine as template was applied in salt aqueous matrices for the extraction of vinflunine and its metabolite in bovine plasma and urine. High extraction recoveries were reached with a study of the impact of salts and the choice of washing solvents adapted to the matrix. The second part showed the simplicity of use and the sensibility of capacitively coupled contactless conductivity detection (C4D) for the analysis of counter-ion and active principle in pharmaceutical compounds in capillary electrophoresis (CE). The technique of double injection allowed the simultaneous analysis of cations and anions. The developed method EC-C4D was applied to Vinca alkaloids and various medicines with anionic or cationic counter-ions
Bhattarai, Bishal. "Wetting properties of structured interfaces composed of surface-attached spherical nanoparticles." Wright State University / OhioLINK, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=wright1544817024854422.
Повний текст джерелаBerthe, Laure. "Durée de vie des contacts rugueux roulants." Thesis, Lyon, INSA, 2014. http://www.theses.fr/2014ISAL0097/document.
Повний текст джерелаThe surface life of rolling rough contacts is an important problem in the evaluation of the life expectancy of a machine. This life span is conditioned by the first cycles of the running-in process and then by the surface fatigue. The running-in period is defined by the time necessary for the rough surfaces to accommodate. The real area of contact is small compared with the apparent area, hence the load creates important pressures which lead to important stresses in the superficial layer and to plastic deformation of the microgeometry. The plastic deformation takes place over the first cycles then the surface stabilizes, this is the end of running-in process. The repeated cyclic loading finally leads to material damage below the surface and to surface micropitting. After a bibliographical study on the rough rolling contact and the existing experimental test machines, the difficulty of analysing the roughness evolution is pointed out. It requires a precise, continuous monitoring of the contact surface evolution on a small enough scale. A two-disk micro-machine was developed to perform this almost "in situ" monitoring at the roughnesses scale, allowing one to identify the mechanisms of running-in and surface degradation. An accurate experimental protocol allows one to measure the opposing surfaces in the first cycles corresponding to the running-in period. The initial surfaces are used as entrance parameters for a numerical simulation of the rough contact of a sphere on a plane. The deformed surface numerically obtained in the stabilized state is compared with the measured one at the end of the running-in period. The very good agreement between these results allows one to validate this method and the numerical results such as the residual stresses and the plastic deformation. Different multiaxial fatigue criteria are applied to the numerical results obtained in the stabilized state. The results are compared to the experimental observations to determine the criterion that is the most suited for this analysis and allows one to explain the crack formation and surfaces damage
Saatdjian, Estéban. "Contribution à l'étude des phénomènes physiques complexes dans les réacteurs gaz-solides d'hydro-pyrolyse du charbon." Paris 6, 1987. http://www.theses.fr/1987PA066097.
Повний текст джерелаCortial, Angèle. "Nouvelles applications des nanoparticules organiques : de la vectorisation d'un mélange d'actifs à travers la peau jusqu'au développement d'un test diagnostique in vitro de l'allergie aux parfums." Thesis, Lyon 1, 2015. http://www.theses.fr/2015LYO10018/document.
Повний текст джерелаThe aim of this work was to develop and optimize methods for fragrance mix I (FMI) encapsulation into nanoparticles (NPs) of two types of nanoparticles (NPs) : polymeric NPs (poly-ε-caprolactone, PCL) and solid lipid NPs (SLNs) (prepared with petrolatum, shea butter, candelilla wax, C10-18 triglycerides, or cetyl palmitate). Then, these new NPss were evaluated as vectors through a pig skin to analyze the distribution of the FMI molecules in the different skin layers. In parallel, NPs have also been applied as solubilizers for the development of a new in vitro test for the diagnosis of fragrance allergy. Our results show that (i) NPs polymers, mainly anionic NPs, are the most suitable vectors to promote trans-epidermal penetration of fragrance. On the contrary, SLNs were found in the stratum corneum, leading to an accumulation of fragrance in this layer; (ii) whatever the type of NPs, the penetration of the FMI molecules in the deeper layers of the skin depends on their intrinsic partition coefficient; (iii) PCL-NPs significantly increase the FMI solubilization in conventional culture media and, allowing a robust reactivation of circulating specific T cells in patients with allergy to fragrances. All of these results confirm the potential of organic NPs for the development of future strategies (for the skin delivery of several actives in the different skin layers). These new vectors further offer a promising alternative to improve the diagnosis of contact dermatitis induced by fragrances and more generally by hydrophobic allergens
Raiyan, Asif. "Fundamentals of Liquid Interactions with Nano/Micro Engineered Surfaces at Low Temperatures." University of Toledo / OhioLINK, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=toledo154471832751114.
Повний текст джерелаVotsios, Vasilis. "Contact mechanics and impact dynamics of non-conforming elastic and viscoelastic semi-infinite or thin bonded layered solids." Thesis, Loughborough University, 2003. https://dspace.lboro.ac.uk/2134/11815.
Повний текст джерелаZethelius, Thea. "Development of headspace solid phase microextraction gas chromatography mass spectrometry method for analysis of volatile organic compounds in board samples : Correlation study between chromatographic data and flavor properties." Thesis, Karlstads universitet, Institutionen för ingenjörs- och kemivetenskaper (from 2013), 2021. http://urn.kb.se/resolve?urn=urn:nbn:se:kau:diva-84941.
Повний текст джерелаKwetkus, Bernhard Andreas. "Contact electrification of solids /." [S.l.] : [s.n.], 1992. http://e-collection.ethbib.ethz.ch/show?type=diss&nr=9788.
Повний текст джерелаAras, Eyyup. "Cutter-workpiece engagement identification in multi-axis milling." Thesis, University of British Columbia, 2008. http://hdl.handle.net/2429/1020.
Повний текст джерелаCaserta, Alice Jordam. "Desenvolvimento de relações não-lineares para mecanismos de contato por meio de estudo analítico e numérico." Universidade de São Paulo, 2015. http://www.teses.usp.br/teses/disponiveis/18/18149/tde-17112015-134233/.
Повний текст джерелаMultiphase flow are frequently observed in nature, such as rain drops in air or snowfalls, volcanoes and sandstorms, and several other situations. For solving these problems which involve gas-solid and granular flows are often used two models: the continuous model (Eulerian-Eulerian formulation) and the discrete model (Eulerian-Lagrangian formulation). There are two main contact models used in DEM, the hard-sphere model and the soft-sphere model. In this work is carried out a detailed study of contact models, focusing on soft-sphere model, based on a dynamic system modeled as nonlinear mass-spring-damper. In order to improve the nonlinear contact model, in this study it is proposed two new approximate relations for determining the damping coefficient and duration of contact for a specific nonlinear soft-sphere contact model where the contact force is continuous at the start and end of the contact. The methodology of the development of this work is divided into three parts: literature research of the contact models; analytical and numerical study of these models and test problems with numerical experiments, using the open source code MFIX (Multiphase Flow with Interphase eXchange). The proposed relations are analyzed and applied in three different problems: dynamic problem, gas-solid flow and granular flow. All results are compared with literature data showing good agreement for these cases studied in the present work.