La technologie de micro indentation est un des moyens de caractérisation (à partir de petits échantillons) qui s'est imposé ces derniers temps dans différents domaines (pharmaceutique, génie civil, industrie pétrolière etc.). Il répond à un certain nombre d'exigences en matière de solution au problème d'échantillonnage. Cette thèse est consacrée à la caractérisation des propriétés mécanique des géomatériaux, et spécialement pour les roches pétrolières comme l'argilite, le grès, la craie ... qui ont été utilisées pour les différentes études expérimentales menées au cours de la thèse. Après avoir présenté la méthode de dépouillement du test d'indentation pour un milieu isotrope, nous avons développé une méthode semi-analytique basée sur la fonction de Green pour caractériser le milieu isotrope transverse en déterminant les cinq paramètres élastique de ce milieu. L'influence des différentes sollicitations (mécaniques, thermiques, hydriques) sur les propriétés mécaniques des roches a été étudiée en utilisant la technologie de micro indentation avec la méthode de dépouillement isotrope transverse. Nous avons essayé de caractériser les paramètres de rupture (C et f) à l'aide du test d'indentation et d'un test de micro compression simple (MCS) effectué par la même machine d'indentation. Par l'essai d'indentation et une méthode d'analyse inverse, nous avons identifié les paramètres d'une loi de comportement élastoplastique (Drucker Prager). En l'absence d'une solution directe du problème d'indentation en régime plastique, nous avons eu recours à une modélisation numérique par un code de calcule élément finis (ABAQUS) pour déterminer la courbe d'indentation calculée. Cette détermination s'est révélée tout à fait probante et a été de plus validée par une simulation d'essais de compression triaxiale sur le même matériau. / The technology of micro indentation is one of the techniques ofmateriaJ characterization (by using small specimens) in various fields (mechanical engineering, civil engineering, oil industry, and pharmaceutical industry). Its main advantage lies in a certain number of practical requirements as regards the solution to the problem of small specimens. The present study is devoted the characterization of the mechanical properties of geomaterials, especially rocks involved in petroleum engineering. After having presented the methodology of the indentation test for isotropic rocks, we developed a semi-analytical method based on the use of Green function to characterize transverse isotropic rocks (five elastic parameters of these rocks). The influence of the various loadings (mechanical, thermal, hydrous) on the rock mechanics properties was studied by using the technology of micro indentation and the methodology proposed for isotropic transverse were used. Moreover, we characterize the failure parameters (C and f) by a combined approach of the indentation test and a test of micro compression (MCS) carried out the indentation device. Finally, we use inverse analysis in order to identify the parameters of a Drucker Prager mode!. ln the absence of a direct solution of the problem of indentation (in plastic regime), we had recourse to a numerical modelling by a finite element code (ABAQUS) to determine the calculated curve of indentation. This determination appeared completely convincing and moreover was validated by a simulation of triaxial compression tests on the same material

Micro-channels are very important in bio-medical and cooler research. Although many research have been conducted with micro-channels, few results have been contributed to discuss the properties of fluids inside a micro-channel. For example, the thermal distribution of the fluid in a micro-channel is only simulated with numerical analysis approach. In our research, we aim to design a device that can measure real thermal data within a micro-channel. We first applied excimer laser lithography on a PMMA substrate to fabricate a micro-channel with 20 mm length, 200£gm width and 200£gm depth. Micro-heater and micro-thermal sensor is than fabricated by sputtering pt thin-thim with PVD process on a glass substrate. Finally, these devices were assembled with UV-curing and than applied for further testing. According to our experiment, lift-off process cannot be easily applied to fabricate micro-heater and micro-thermal sensor since the architecture of these devices were fragile in metal line sidewalls. Wet-lithography is than used to conquer this problem. Our primary test on this micro-thermal sensor shows that its resistance varies with thermal changes. Such mechanism can be applied to measuring thermal field in a micro-channel.

<p>At the gas spring manufacturing company Strömsholmen AB there is the needfor a way to make the load alleviating gas springs more robust, endurable andmaintenance free. A small high pressure compressor with a control systemshould solve these problems. The system would have to raise the pressure in the gas spring if it were to drop under a level and let some pressure out if it were to increase over a certain level. The construction of this Micro Compressor system is presented in this master's thesis. At first, a deeper understanding of the task at hand was gathered resulting in a design specification, followed by a concept study generated by the systematic design method. The evaluation of the concept study resulted in a chosen concept for prototype production. This prototype system consists of a control system with a pressure switch, a pressure reducing valve and a Micro Compressor that raises the pressure when needed. An electric system was also designed to work with the pressure switch, actuating the compressor when needed. Thoughts of converting the Micro Compressor system to pneumatic drive were also considered to increase the scope of use. The prototype system was tested to see that the requirements in the design specification were met and then the project was handed back to Strömsholmen AB for future development together with a list of suggestions of things that need improvement.</p>

At the gas spring manufacturing company Strömsholmen AB there is the needfor a way to make the load alleviating gas springs more robust, endurable andmaintenance free. A small high pressure compressor with a control systemshould solve these problems. The system would have to raise the pressure in the gas spring if it were to drop under a level and let some pressure out if it were to increase over a certain level. The construction of this Micro Compressor system is presented in this master's thesis. At first, a deeper understanding of the task at hand was gathered resulting in a design specification, followed by a concept study generated by the systematic design method. The evaluation of the concept study resulted in a chosen concept for prototype production. This prototype system consists of a control system with a pressure switch, a pressure reducing valve and a Micro Compressor that raises the pressure when needed. An electric system was also designed to work with the pressure switch, actuating the compressor when needed. Thoughts of converting the Micro Compressor system to pneumatic drive were also considered to increase the scope of use. The prototype system was tested to see that the requirements in the design specification were met and then the project was handed back to Strömsholmen AB for future development together with a list of suggestions of things that need improvement.

An analog frontend of an implantable baseband SOC (System-on-a-chip) chip design for the interface of neural micro-stimulation is present in this thesis. The mentioned neural interface including controllable stimulators, and telemetry for data and power transmission which is powered by transcutaneous magnetic coupling. An external transmitter coil is required to power and communicate with the implanted device. It can avoid the risk of causing infection and the problem of limited battery life. The first topic of this thesis proposes a single stage differential amplifier to be used as an Error Amplifier in an LDO (Low Dropout) regulator. It increases the bandwidth and decreases the chip¡¦s area at the same time. When a bandgap bias is integrated with our design in a feedback loop, a stable voltage source is constituted to become a power supply for the entire implanted chip. The second topic reveals a C-less (no capacitor) area-saving ASK (Amplitude Shift keying) demodulator. Since there is no capacitor used in the demodulator, it can substantially reduce the layout area of the SOC without any sacrifice of the performance of the SOC

Orientador: Rui Fragassi Souza / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Eletrica / Made available in DSpace on 2018-07-19T12:40:07Z (GMT). No. of bitstreams: 1 Reis_EdsonCesardos_M.pdf: 6104773 bytes, checksum: ba61fb7ad7af067f1eb4d669c0e3051d (MD5) Previous issue date: 1994 / Resumo: Este trabalho descreve o projeto e construção de duas fontes de microondas para uso comercial, projetadas e testadas durante o desenvolvimento de sistemas para transmissão de sinais analógicos via satélite e digitais via rádio. É feita uma descrição prévia de elementos genéricos usados em fontes de microondas, muitos dos quais são usados nos projetos das duas fontes descritas / Abstract: This work describes two microwave sources, for analog satellite communication and digital radio systems, designed and manufactured for commercial application. Aiming at completeness, this study starts with a brief decription of the basic microwave source blocks, most of them used by the described oscillators / Mestrado / Mestre em Engenharia Elétrica

Les nanotechnologies sont en plein essor grâce aux nombreuses innovations et opportunités industrielles qu’elles offrent. Les nanomatériaux manufacturés (NM) présentent des propriétés physico-chimiques particulières, bien différentes de celles des matériaux conventionnels. A ce jour, un grand nombre d'incertitudes demeurent sur les effets des NM, qui se retrouvent libérés accidentellement ou non dans l’environnement. Cette thèse s’inscrit dans le cadre du projet ANR NanoSALT et a été réalisée dans 2 laboratoires partenaires : LIEC (Metz) et MMS (Angers- Nantes). Les objectifs étaient d'évaluer en milieu aquatique, l'impact de NM d’argent et de dioxyde de cérium sur deux espèces de bivalves couvrant un large gradient de salinité, Corbicula fluminea et Scrobicularia plana. Les organismes ont été exposés à des doses chroniques et réalistes de ces NM à différents stades de leur cycle de vie et à différentes salinités. Les recherches ont été menées en laboratoire, en utilisant des conditions d'exposition de plus en plus réalistes d'un point de vue environnemental (micro- et mésocosmes). Ce travail montre l’impact de la salinité sur les caractéristiques physico-chimiques et le devenir des NM. L’évaluation de l’écotoxicité des NM sur les deux modèles biologiques en intégrant plusieurs marqueurs biochimiques et comportementaux (approche multi-biomarqueurs) a permis de mettre en évidence l’effet des NM au travers du continuum eau douce-eau de mer sur ces organismes bivalves. / Due to numerous innovations and industrial opportunities, increased attention is given to nanotechnology. Nanomaterials present particular physico-chemical properties, largely different in comparison to the bulk material. A large number of uncertainties remains on accidental (or not) release of engineered nanomaterials (ENM) at different stages of the value chain (usage, end of life) in aquatic environment. In the framework of the ANR NanoSALT program, this PhD has been achieved in two partner laboratories (LIEC (Metz) and MMS (Angers-Nantes)). The aim was to assess the impact of silver and cerium dioxide ENM on two bivalve species living across a large salinity gradient, Corbicula fluminea and Scrobicularia plana. Organisms have been exposed to realistic and chronic ENM concentrations at different stage of the value chain and at different salinities. Research have been conducted in laboratory using more and more realistic exposure conditions (micro and mesocosm). This work highlight salinity impact on physico-chemical fate and behavior on ENM. Ecotoxicity assessment of ENM on both endobenthic species, using a battery of biochemical and behavioral biomarkers (multi-marker approach), allowed to highlight ENM effects through fresh-marine water continuum on both bivalves.

Les micro-plasmas constituent une technologie d'avenir pour des applications aussi nombreuses que diverses : dépollution, traitement de surface, applications bio-médicales, accélération aérodynamique... Nous avons étudié ces micro-plasmas dans des gaz inertes (hélium ou argon), en les alimentant en courant continu dans des structures de type micro-cathode creuse. Afin de comprendre les mécanismes physiques régissant leur comportement, nous les avons caractérisés par plusieurs diagnostics, notamment par caméra ICCD et par spectrométrie d'émission optique. Ce dernier diagnostic nous a permis de déterminer la température du gaz des micro-plasmas, par l’analyse de la structure rovibrationnelle des raies du second système positif de l’azote (présent à l’état de traces), mais aussi d’effectuer des mesures de densité électronique, en analysant l’élargissement Stark de la raie H béta. Ces paramètres physiques obtenus expérimentalement, ont été comparés à leurs équivalents obtenus par simulation (logiciel GdSIM du laboratoire Laplace). Ce travail de thèse a également permis de montrer la possibilité d’atteindre le régime luminescent anormal d’un micro-plasma, en réduisant l’aire de la surface cathodique extérieure de la micro-cathode creuse. Ce régime de fonctionnement s’accompagne d’une hausse rapide de la température du gaz, ainsi que d’un phénomène d’hystérésis qui apparaît sur une courbe I-V, pour une rampe d’alimentation en courant linéairement croissante puis décroissante. Dans le cas de plusieurs micro-plasmas fonctionnant en parallèle, nous avons mis à jour un nouveau mécanisme, expliquant l’allumage des cavités de proche en proche. / The micro-plasmas are a promising technology for a lot of applications: environmental remediation, surface treatment, bio-medical applications, aerodynamic acceleration ... Our micro-plasmas are generated in microhollow cathode (M.H.C) structures, supplied by direct current and studied in rare gases (helium or argon). To understand the physical mechanisms ruling their behaviour, they have been characterized by several diagnostics, especially ICCD camera and optical emission spectroscopy. This last diagnostic has been used to determine the micro-plasma gas tempe rature , by analysing the bands 1.3 and 0.2 (from the second . positive system of nitrogen). but also to measure the electron density by analyzing the Stark broadening of the H beta line. We have also carried out simulations with a fully fluid model to obtain the spatial profiles of the electric field, the charge species densities and the gas temperature. Thus, we have studied the breakdown, the self-pulsing regime and the normal glow regime of our micro-plasmas. We have also demonstrated that a micro-plasma can work in the ab normal glow regime, at the condition to limit the cathode surface of the micro-device. For increasing values of curre nt. this abnormal glow regime is accompanied by a fast increase of the gas temperature. Moreove r, when the micro-plasma is supplied by a linear increasing-decreasing DC voltage ramp, this regime is accompanied by the formation of a hysteresis phenome non. At last, in the case of a micro-devi ce with severa 1micro-ho 1I0wcathodes in parallel, we exp lain how the cathode limitation favours the parallel ignition and is an alternative issue to the individual ballasting.

In this work, a micro-model of the catalyst layer of polymer electrolyte membrane fuel cell (PEMFC) was developed. The micro-model includes the transport phenomena and the reaction kinetics within a three dimensional micro-structure representing a sample of PEMFC catalyst layer. Proper physical boundary conditions have been described on the surfaces of the sample as well as on the interfaces between the regions through which all constituents are solved in a coupled manner. A four-phase micro-structure of CL was reconstructed, the platinum particles were resolved in the computational grid generation and the governing equations were solved within platinum region. A body-fitted computational mesh was generated for the reconstructed micro-structure of CL. The number of computational cells were optimized based on how close to an analytical sphere the magnitude of the surface area of a sphere can be captured after generating the computational cells. The interfaces with important physical phenomena were more refined than the rest of the interfaces, specially the electrochemically active reaction surface. The computational mesh was checked for a grid independent numerical solution. The Knudsen effects was included by calculating the characteristic length in the pore region. Four different cases of including Knudsen effects were studied. Also, a comparison was made between solution with and without Knudsen effects. A physical model of oxygen dissolution was developed, the oxygen dissolution at the interface between pore and ionomer was treated as an superficial phenomenon. The performance curves were produced and provided for the reconstructed micro-structure along with the distribution of field variables. A length study of the reconstructed micro-structure was conducted such that the results from the micro-modeling can capture the trend in variable distributions observed in the macro-modeling of CL or experiments. A platinum loading study was preformed and the anomalous phenomena of dramatic increase in oxygen transport resistance observed in some experimental works was explained by isolating the ionomer region of the CL micro-structure and numerically calculating the shape factor for diffusive transport. It was found that the increase in oxygen transport resistance is due to the increase in diffusion pathway and decrease in the transport surface area. / Thesis (Ph.D, Mechanical and Materials Engineering) -- Queen's University, 2013-03-06 15:55:21.564

A novel process based on the principle of layered photolithography has been proposed and tested for making real three-dimensional micro-structures. An experimental setup was designed and built for doing experiments on this micro-fabrication process. An ultraviolet (UV) excimer laser at the wavelength of 248 nm was used as the light source and a single piece of photo-mask carrying a series of two dimensional (2D) patterns sliced from a three dimensional (3D) micro-part was employed for the photolithography process. The experiments were conducted on the solidification of liquid photopolymer from single layer to multiple layers. The single-layer photolithography experiments showed that certain photopolymers could be applied for the 3D micro-fabrication, and solid layers with sharp shapes could be formed from the liquid polymer identified. By using a unique alignment technique, multiple layers of photolithography was successfully realized for a micro-gear with features at 60 microns. Electroforming was also conducted for converting the photopolymer master to a metal cavity of the micro-gear, which proved that the process is feasible for micro-molding. / Singapore-MIT Alliance (SMA)