Дисертації з теми "Conventional and optical dilatometry"

Les matériaux à gradient de composition et de structure permettent d'associer des propriétés complémentaires dans une pièce donnée. Les cermets (matériaux composite céramique métal) développés par Rio Tinto Alcan seront potentiellement utilisés en tant qu'anodes inertes pour l'électrolyse de l'aluminium. Pour connecter cette pièce à matrice céramique au réseau électrique, ce matériau doit être associé avec un matériau conducteur électrique en une seule opération de frittage. En associant les connaissances issues de la métallurgie des poudres avec une analyse microstructurale, des calculs thermodynamiques et des considérations mécaniques, une gamme de matériaux appelés metcer (composite métal céramique) a été développée. Selon la proportion et composition de la phase métallique initiale de ces metcers, ils peuvent être cofrittés en une seule opération avec un cermet. Nous avons montré que la proportion de phase métallique influençait fortement la tenue mécanique de l'ensemble pendant le frittage ; que la composition des phases oxydes et métalliques permettait de maîtriser les phénomènes de diffusion entre les parties cofrittées pour construire une interface graduelle. Des lois phénoménologiques basées sur la mécanique des milieux continus ont été développées pour modéliser le frittage d'un cermet et d'un metcer. Ces lois ont été introduites dans un logiciel de calcul par éléments finis pour simuler le frittage d'assemblages bicouches et identifier les éventuels points de fragilité de différentes géométries. En comparant ces résultats de simulation numérique à des observations optiques in situ sur des pièces centimétriques, nous avons montré que l'amorçage de fissures proche de l'interface a lieu lorsque les contraintes sont élevées. A basse température, de faibles écarts de déformations entre les couches suffisent à amorcer des fissures lorsque les viscosités des matériaux sont grandes et qu'ils ont un comportement fragile. A haute température, lorsque les écarts de déformation sont grands et les viscosités faibles, les contraintes entre les couches sont relaxées. En utilisant les connaissances acquises à la fois sur la chimie et la mécanique du système, une pièce centimétrique tricouche à gradient exempt de fissure a été réalisée
Graded materials are used to gather complementary physical and/or chemical properties into a single part. Cermet material (ceramic metal composite) developed by Rio Tinto Alcan may be used as inert anode for aluminium electrolysis. To connect these ceramic matrix materials to the current network, we propose to associate them with a conductive material in a single sintering step. Using our knowledge on powder metallurgy with microstructure analysis, thermodynamical and mechanical calculations, a new range of material called metcer (metal ceramic composite) has been developed. According to their metal phase proportion and composition, the metcer materials can be cosintered with cermets in a single sintering step. By modifying the metal phase proportion, we enabled the parts to keep joined during the whole sintering thermal cycle. The composition of oxides and metal phases change the diffusion phenomena and enable one to build a graded interface between the layers. Based on continuum mechanics, constitutive equations have been used to simulate the sintering of a cermet and a metcer. Constitutive equations have been implemented into a finite element software to identify the weak regions of bilayers parts of complex geometry. We compared numerical simulation results with optical observations made during sintering on large scale bilayers. Cracks near the interface occur at low temperature when the strain mismatch between the layers is low and the viscosities of the layers are high. Thus, the materials have a fragile behaviour. At high temperature, when the viscosities are low and the strain mismatch is high, the stresses in the vicinity of the interface are released. Combining our knowledge on the chemistry and interactions between these materials, we developed a trilayer material. This material showed up a graded interface without any crack

This thesis reports the optical properties of InAlAs QDs and InGaAsN QWs grown by Molecular Beam Epitaxy (MBE) on both the conventional (100) and high Miller index surfaces. InAlAs QDs on AlGaAs matrix are grown by MBE on the conventional (100) and non-(100) GaAs substrates using different growth conditions, namely, growth temperature, different confinement barriers, and amount of deposited material. PL measurements revealed differences in the optical properties that are caused by substrate orientation effects. The PL emission energies of QDs grown on high Miller index surfaces such as (311)A and (311)B are found to be strongly dependent on the atomic terminated surface [A (Ga face) or B (As face)] of the substrate. The QDs grown on (311)B plane show superior optical properties over QDs grown on (311)A and (100) planes. The optimum structure to achieve the highest optical efficiency of QDs emitting in the visible red part of electromagnetic spectrum ( ̴ 666 nm) consisted of 4.4MLs Al0.35In0.65As/Al0.45Ga0.55As QDs grown on (311)B plane at a growth temperature of 550 0C. In addition, a further investigation was carried out to study the effect of post-growth thermal annealing on the optical properties of InAlAs QDs grown on (100), (311)A, and (311)B planes. A noticeable enhancement of the PL intensity at 10 K for all planes was observed by increasing the annealing temperature up to 700 0C. Thermal annealing of (311)A InAlAs/GaAlAs QDs resulted in a negligible blue shift, while a large blue shift was observed from (311)B and (100) QDs. This is explained by the smaller size of QDs, smaller strain, and lower In segregation from (311)A GaAs orientation. PL and Transmission Electron Microscopy (TEM) have been used to investigate the optical and structural properties, respectively, of In0.36Ga0.64As1-yNy/GaAs double quantum wells (QWs) grown both on the conventional (100) and non-(100) GaAs substrates. These include In0.36Ga0.64As1-yNy/GaAs QWs with three different compositions of nitrogen, namely, 0%, 1%, and 2%. QWs grown on (311)A GaAs plane show higher nitrogen incorporation over all the other planes. TEM measurements show that (311)B QWs have inferior structural properties than QWs grown on (311)A and (100). TEM images demonstrated that the (311)B QWs interfaces are undulated and not uniform. In contrast QWs grown on (311)A and (100) display very uniform and very flat interfaces. The effect of thermal annealing on the optical properties of In0.36Ga0.64As1-yNy/GaAs double QWs grown on different planes was investigated for two sets of samples having 0% and 1% nitrogen. It was found that annealing at 700 0C for 30 seconds is the optimum annealing temperature which improves the PL efficiency for all QWs. The PL enhancement is larger in samples with 1% nitrogen than 0%.

Inspirados por las investigaciones realizadas en los campos de la plasmónica y los metamateriales, en este trabajo hemos estudiado la difusión de la luz por pequeñas partículas (nanopartículas en el rango del visible) con propiedades ópticas arbitraria, tanto convencionales (dieléctricas como metálicas) como no convencionales (con permeabilidad magnética distinta de 1). El trabajo está principalmente enfocado en controlar la propiedades (principalmente la dirección) de la luz difundida por una partícula mediante la manipulación de sus constantes ópticas. Las principales aplicaciones de este estudio se pueden concentrar en los campos de los biosensores y/o de las comunicaciones ópticas. Es por esto que hemos considerado tanto partículas aisladas como sistemas de partículas(dímeros principalmente).
Inspired by the last researches on plasmonics and metamaterials, this work is devoted to the study of light scattering by small particles (nanoparticles in the visible range) with arbitrary optical properties, both conventional and non-conventional. We focused the analysis on the control of the directionality of light scattering by tunning the optical constants of the scatterer. This could be interesting for the design of futuristic optical communications and/or for the generation of improved biosensores. For this reason, isolated particles and also clusters of them (mainly dimers) were considered.

The work of this dissertation is centered on two non-conventional synthetic approaches to ferromagnetic nanomaterials: high-throughput experimentation (HTE) (polyol process) and continuous flow (CF) synthesis (aqueous reduction and the polyol process). HTE was performed to investigate phase control between FexCo1-x and Co3-xFexOy. Exploration of synthesis limitations based on magnetic properties was achieved by reproducing Ms=210 emu/g. Morphological control of FexCo1-x alloy was achieved by formation of linear chains using an Hext. The final study of the FexCo1-x chains used DoE to determine factors to control FexCo1-x, diameter, crystallite size and morphology. [Ag] with [Metal] provide statistically significant control of crystallite size. [OH]/[Metal] predict 100 % FexCo1-x at > 30. To conclude section 1, a morphological study was performed on synthesis of Co3-xFexOy using the polyol process. Co3-xFexOy micropillars were synthesized at various sizes. The close proximity of the particles in the nanostructure produced an optical anisotropy and was magnetically induced which is evidence for the magneto-birefringence effect. The second non-conventional synthetic approach involves continuous flow (CF) chemistry. Co nanoparticles (Ms=125 emu/g) were newly synthesized by aqueous reduction in a microreactor and had 30 ±10 nm diameter and were produced at >1g/hr, a marker of industrial-scale up viability. The final work was the CF synthesis of FexCo1-x. The FexCo1-x was synthesized with limitation to the composition. The maximum FexCo1-x phase composition at 20 % resulted from the aqueous carrier solvent triggering oxide formation over FexCo1-x.

Der weltraumgestützte Gravitationswellendetektor LISA (Laser Interferometer Space Antenna) besteht aus drei identischen Satelliten an Bord derer sich jeweils zwei frei schwebende Testmassen befinden. Die Lage der einzelnen Testmassen in Bezug auf die zugehörige optische Bank muss mit einer Genauigkeit besser 1 pm/sqrt(Hz) in der Abstands- und besser 10 nrad/sqrt(Hz) in der Winkelmessung erfolgen. In der vorliegenden Arbeit wird ein kompaktes optisches Auslesesystem präsentiert, welches als Prototyp für diese Abstands- und Winkelmetrologie dient. Das dafür entwickelte polarisierende Heterodyn-Interferometer mit räumlich getrennten Frequenzen basiert auf einem hoch-symmetrischen Design, bei dem zur optimalen Gleichtakt-Unterdrückung Mess- und Referenzarm die gleiche Polarisation und Frequenz sowie annähernd gleiche optische Pfade haben. Für die Winkelmessung wird die Methode der differentiellen Wellenfrontmessung eingesetzt. In einem ersten Prototyp-Aufbau wird ein Rauschniveau von weniger als 100 pm/sqrt(Hz) in der Translations- und von weniger als 100 nrad/sqrt(Hz) in der Winkelmessung (beides für Frequenzen oberhalb 0.1 Hz) demonstriert. In einem zweiten Prototyp-Aufbau werden zusätzlich eine Intensitätsstabilisierung und ein Phasenlock der beiden Frequenzen implementiert. Die analoge Phasenmessung ist durch eine digitale, FPGA basierte, ersetzt. Mit diesem Aufbau wird ein Rauschen kleiner 5 pm/sqrt(Hz) in der Translationsmessung und kleiner 10 nrad/sqrt(Hz) in der Winkelmessung, beides für Frequenzen größer 0.01 Hz, erreicht. Eine Rausch-Analyse wurde durchgeführt und die Nichtlinearitäten des Interferometers bestimmt. Das Interferometer wurde im Hinblick auf die LISA Mission entwickelt, findet seine Anwendung aber auch bei der Charakterisierung der dimensionalen Stabilität von ultra-stabilen Materialien sowie in der optischen Profilometrie. Die Adaptierung des Interferometers dazu sowie erste Resultate zu beiden Anwendungen werden in dieser Arbeit präsentiert.
The space-based gravitational wave detector LISA (Laser Interferometer Space Antenna) consists of three identical satellites. Each satellite accommodates two free-flying proof masses whose distance and tilt with respect to its corresponding optical bench must be measured with at least 1 pm/sqrt(Hz) sensitivity in translation and at least 10 nrad/sqrt(Hz) sensitivity in tilt measurement. In this thesis, a compact optical readout system is presented, which serves as a prototype for the LISA proof mass attitude metrology. We developed a polarizing heterodyne interferometer with spatially separated frequencies. For optimum common mode rejection, it is based on a highly symmetric design, where measurement and reference beam have the same frequency and polarization, and similar optical pathlengths. The method of differential wavefront sensing (DWS) is utilized for the tilt measurement. In a first prototype setup noise levels below 100 pm/sqrt(Hz) in translation and below 100 nrad/sqrt(Hz) in tilt measurement (both for frequencies above 0.1 Hz) are achieved. A second prototype was developed with additional intensity stabilization and phaselock of the two heterodyne frequencies. The analog phase measurement is replaced by a digital one, based on a Field Programmable Gate Array (FPGA). With this setup, noise levels below 5 pm/sqrt(Hz) in translation measurement and below 10 nrad/sqrt(Hz) in tilt measurement, both for frequencies above 0.01Hz, are demonstrated. A noise analysis was carried out and the nonlinearities of the interferometer were measured. The interferometer was developed for the LISA mission, but it also finds its application in characterizing the dimensional stability of ultra-stable materials such as carbon-fiber reinforced plastic (CFRP) and in optical profilometry. The adaptation of the interferometer and first results in both applications are presented in this work.

It is known from the literature that conventional voltage and current transformers measure inaccurate values for voltage and current harmonics which are parts of power quality. Maximum bandwidth of conventional current transformers, which are used in electricity transmission and distribution systems, is 1.5-2 kHz and it is lower for conventional voltage transformers. Also, it is known that
voltages in some frequency spectrum are measured higher and voltages in another frequency spectrum are measured lower by the conventional voltage transformers. Furthermore, because of the phase shift of fundamental component caused by the conventional current and voltage transformers, losses and efficiency can not be calculated accurately. In this work, through the simultaneous measurements taken at the same feeder by both conventional transformers and new technology measurement transformers
amplitude and phase shift errors which are caused by conventional transformers depending on frequency and so harmonics, are examined and evaluated. Amplitude coefficients and phase shifts are determined for different types of conventional transformers to be able to calibrate measurement deviation. Through this work, measured data by conventional transformers will be accurate and realistic in terms of harmonic components. This matter is important to determine whether the accurate limits which will be set in the future possibly concerning with harmonics and interharmonics, are surpassed or not
also for punitive sanction.

In the last two decades, zirconia has been of a great interest to dentists due to its superb mechanical and optical properties. At first, the use of zirconia was limited to fabrication of cores replacing the metal in crown construction. Nowadays, there is an increase in the trend of using monolithic ‘full contour’ translucent zirconia to overcome the problem of chipping of porcelain veneers and to overcome the limitation of using lithium disilicate in long span replacement. This has brought zirconia in direct contact with saliva and oral fluids and introduced the possibility of the material undergoing low temperature degradation. This study aimed to investigate the effect of accelerated hydrothermal aging on the mechanical and optical properties of two conventional core and two full contour translucent zirconia materials, expected to be used by 90% of zirconia manufacturers globally. Hydrothermal aging was carried out using an autoclave to simulate in vivo aging, using a specific protocol proposed by ISO 13356:2015 mimicking 15- 20 years of clinical service of the material. Each of the four materials were tested before and after aging, including structural analysis which was carried out using XRD, SEM, FIB-SEM and AFM. Mechanical property investigations were carried out by measuring BFS and Vickers hardness. Optical properties were thoroughly investigated through measuring a range of translucency parameters and changes in colour before and after aging. The results of this study showed that conventional core materials were less affected by hydrothermal aging in comparison to full contour translucent zirconia in terms of optical properties. All of the used materials showed clear colour changes after aging, however none of them showed significant changes in the mechanical properties even with more than 20% of t →m phase transformation in one of the translucent zirconia materials. Within the limitation of this in vitro study, it can be concluded that full contour translucent zirconia can be used clinically with no concern about its mechanical and optical properties, however, further studies on the perception and acceptability for changes in the optical properties would be highly recommended.

Despite enormous efforts and investments, the efficiency of InGaN-based green and yellow-green light emitters remains relatively low, and that limits progress in developing full color display, laser diodes, and bright light sources for general lighting. The low efficiency of light emitting devices in the green-to-yellow spectral range, also known as the “Green Gap”, is considered a global concern in the LED industry. The polar c-plane orientation of GaN, which is the mainstay in the LED industry, suffers from polarization-induced separation of electrons and hole wavefunctions (also known as the “quantum confined Stark effect”) and low indium incorporation efficiency that are the two main factors that contribute to the Green Gap phenomenon. One possible approach that holds promise for a new generation of green and yellow light emitting devices with higher efficiency is the deployment of nonpolar and semi-polar crystallographic orientations of GaN to eliminate or mitigate polarization fields. In theory, the use of other GaN planes for light emitters could also enhance the efficiency of indium incorporation compared to c-plane. In this thesis, I present a systematic exploration of the suitable GaN orientation for future lighting technologies. First, in order to lay the groundwork for further studies, it is important to discuss the analysis of processes limiting LED efficiency and some novel designs of active regions to overcome these limitations. Afterwards, the choice of nonpolar orientations as an alternative is discussed. For nonpolar orientation, the (1-100)-oriented (m-plane) structures on patterned Si (112) and freestanding m-GaN are studied. The semi-polar orientations having substantially reduced polarization field are found to be more promising for light-emitting diodes (LEDs) owing to high indium incorporation efficiency predicted by theoretical studies. Thus, the semi-polar orientations are given close attention as alternatives for future LED technology. One of the obstacles impeding the development of this technology is the lack of suitable substrates for high quality materials having semi-polar and nonpolar orientations. Even though the growth of free-standing GaN substrates (homoepitaxy) could produce material of reasonable quality, the native nonpolar and semi-polar substrates are very expensive and small in size. On the other hand, GaN growth of semi-polar and nonpolar orientations on inexpensive, large-size foreign substrates (heteroepitaxy), including silicon (Si) and sapphire (Al2O3), usually leads to high density of extended defects (dislocations and stacking faults). Therefore, it is imperative to explore approaches that allow the reduction of defect density in the semi-polar GaN layers grown on foreign substrates. In the presented work, I develop a cost-effective preparation technique of high performance light emitting structures (GaN-on-Si, and GaN-on-Sapphire technologies). Based on theoretical calculations predicting the maximum indium incorporation efficiency at θ ~ 62º (θ being the tilt angle of the orientation with respect to c-plane), I investigate (11-22) and (1-101) semi-polar orientations featured by θ = 58º and θ = 62º, respectively, as promising candidates for green emitters. The (11-22)-oriented GaN layers are grown on planar m-plane sapphire, while the semi-polar (1-101) GaN are grown on patterned Si (001). The in-situ epitaxial lateral overgrowth techniques using SiNx nanoporous interlayers are utilized to improve the crystal quality of the layers. The data indicates the improvement of photoluminescence intensity by a factor of 5, as well as the improvement carrier lifetime by up to 85% by employing the in-situ ELO technique. The electronic and optoelectronic properties of these nonpolar and semi-polar planes include excitonic recombination dynamics, optical anisotropy, exciton localization, indium incorporation efficiency, defect-related optical activities, and some challenges associated with these new technologies are discussed. A polarized emission from GaN quantum wells (with a degree of polarization close to 58%) with low non-radiative components is demonstrated for semi-polar (1-101) structure grown on patterned Si (001). We also demonstrated that indium incorporation efficiency is around 20% higher for the semi-polar (11-22) InGaN quantum wells compared to its c-plane counterpart. The spatially resolved cathodoluminescence spectroscopy demonstrates the uniform distribution of indium in the growth plane. The uniformity of indium is also supported by the relatively low exciton localization energy of Eloc = 7meV at 15 K for these semi-polar (11-22) InGaN quantum wells compared to several other literature reports on c-plane. The excitons are observed to undergo radiative recombination in the quantum wells in basal-plane stacking faults at room temperature. The wurtzite/zincblende electronic band-alignment of BSFs is proven to be of type II using the time-resolved differential transmission (TRDT) method. The knowledge of band alignment and degree of carrier localization in BSFs are extremely important for evaluating their effects on device properties. Future research for better understanding and potential developments of the semi-polar LEDs is pointed out at the end.

Background. The development of non-invasive imaging techniques has been stimulated by the shortcomings of histopathology. Currently the only valid diagnostic technique in dermatology is skin biopsy which remains a painful, invasive intervention for the patient. Moreover, this approach is not always convenient for monitoring and follow-up of a skin disease. Optical imaging technologies could solve these shortcomings as they are fast, precise, repeatable and painless. There are four established non-invasive skin imaging techniques used in daily practice: dermoscopy, high-frequency ultrasound, reflectance confocal microscopy (RCM) and conventional optical coherence tomography (C-OCT). In imaging there is a trade-off between resolution and penetration depth. The former permits the visualization of cells, if the resolution is at least 3 µm. The latter enables the recognition of patterns and structures in deeper layers of the skin if the penetration depth is deeper than 150 µm. New non-invasive techniques using infrared light sources have been developed recently. The technique used in this work is a high-definition optical coherence tomography (HD-OCT).Objectives. The overall aims of this thesis were the feasibility of HD-OCT to visualize in/ex vivo, in real time and in 3-D the cellular and structural morphology of the skin, secondly the assessment of the capability of this technology to measure in vivo and real time the cutaneous optical properties, and finally the determination of the contribution of this technique to the non-invasive near-infrared imaging technologies. Five specific objectives have been established: i) could cells be observed in their 3-D microenvironment in normal and diseased skin, ii) could we describe morphologic features of cells and structures in normal and diseased skin (m_HD-OCT), iii) could these morphologic features be quantified by optical property analysis (o_HD-OCT), iv) was it possible to perform accurate thickness measurements in normal and diseased skin, and finally v) what was the diagnostic potential of this technique?Methodology. HD-OCT uses a combination of parallel time-domain interferometry, high power tungsten lamp (with Gaussian filter, very low lateral coherence and ultra-high bandwidth (1300 nm +/- 100 nm)), and last but not least, full field illumination with real time focus tracking. A constant homogeneous resolution of 3 µm resolution in all three dimensions is obtained up to a depth of 570 µm. Hence, the system is capable of capturing real time full 3-D images. Moreover, the in vivo assessment of optical properties of the skin is only applicable to OCT when operating in focus-tracking mode, which is the case for HD-OCT. The means to obtain answers to the five specific questions were the comparison of en face HD-OCT images with RCM and HD-OCT cross-sectional images with histopathology and C-OCT. Results. At least 160 line pares were observed by imaging a high resolution phantom with HD-OCT. This suggested a 3 µm lateral resolution. The presence of cells such as keratinocytes, melanocytes, inflammatory cells, fibroblasts and melanophages in their 3-D cutaneous microenvironment in vivo as well as ex vivo has been demonstrated .A qualitative description of structures and patterns in normal and diseased skin could be performed by HD-OCT. Clear structural changes of the epidermis, dermo-epidermal junction, papillary dermis and reticular dermis related to intrinsic skin ageing could be observed. Lobulated structures, surrounded by stretched stromal fibers and arborizing vessels, could be demonstrated in nodular basal cell carcinoma (BCC). The o_HD-OCT of normal and diseased skin could be assessed in vivo. This approach permitted the quantitative assessment of the OCT signal attenuation profiles of normal healthy skin, actinic keratosis (AK) and squamous cell carcinoma (SCC). Differences in signal attenuation profiles could be demonstrated between these three groups. These differences were also observed between BCC subtypes. The slope of the exponential attenuation of the signal in the upper part of the epidermis was very high in benign nevi. The more malignant the lesion the lower the slope. Thickness measurements of epidermis and papillary dermis could be performed by m_HD-OCT, based on a cross-sectional images and their corresponding en face image. More accurate measurements of epidermal and papillary dermal thickness could be performed based on the optical analysis of a skin volume by o_HD-OCT. The diagnostic potential of HD-OCT in comparison with dermoscopy, RCM and C-OCT could be assessed regarding i) melanoma, ii) BCC differentiation from BCC imitators and BCC sub-differentiation and iii) SCC differentiation from AK. A much higher diagnostic potential could be demonstrated for o_HD-OCT in comparison with m_HD-OCT concerning melanoma detection. The diagnostic potential of HD-OCT to discriminate BCC from clinical BCC imitators was moderate. However, HD-OCT seemed to have high potential in sub-differentiation of BCC subtypes: i) it seemed to be the best technique to include and exclude a superficial BCC, ii) the technique appeared to be the best approach to exclude nodular BCC, and iii) HD-OCT looked to be the best technique to include an infiltrative BCC. Finally, HD-OCT has proven to be a powerful method to discriminate AK from SCC.Conclusions. HD-OCT is able to capture real time 3-D imaging with a sufficiently high optical resolution and penetration depth to allow the visualization of cells in and ex vivo in their micro-architectural context. At the same time, HD-OCT permits the recognition of patterns and structures in a sufficiently large volume of skin (1.5 mm³). HD-OCT closes therefore the gap between RCM with a high resolution but low penetration depth and C-OCT with a low resolution but high penetration depth. Moreover, HD-OCT permits, in contrast to RCM and C-OCT, the real time in vivo analysis of optical properties of the skin. HD-OCT seems to be a promising tool for early diagnosis of melanoma, BCC sub-differentiation and differentiation between SCC and AK.Future perspectives. Multicenter validation studies are needed to determine the diagnostic performance of this promising new technology, especially in other clinical settings combining both morphological and optical property analysis. This combined analysis could be a valuable method not only for diagnosis, monitoring and therapeutic guidance of dermatologic diseases but it could also be helpful in the management of non-dermatologic conditions such as diabetic micro-angiopathy, infantile cystinosis or even osteoporosis.
Doctorat en Sciences médicales (Santé Publique)
info:eu-repo/semantics/nonPublished

This diploma thesis deals with 3D reconstruction of objects using image analysis methods. The work includes mathematical theory associated with this problem, a procedure for creating 2D sharp images and 3D reconstruction itself. The outputs are 2D sharp images, 3D models, stl models. Different kinds of data are analyzed.

Etude de cristaux liquides thermotropes presentant des phases smectiques de type a et b. Etude de l'influence de divers parametres moleculaires sur la stabilite thermique de telles phases. Proposition d'un modele d'organisation des molecules a l'interieur d'une lamelle smectique

OBJECTIVE: This study aims to compare the flexural strength and color stability of conventional, machined, and printed dental polymers. Secondarily, the effects of aging, fatigue, coffee, distilled water, and UV light on the color stability and flexural strength of the different dental polymers will be evaluated. MATERIALS AND METHODS: Sixty disks 14mm in diameter and 2mm in thickness were fabricated from each of the following polymers: Jet Tooth Shade (Lang Dental), ProTemp (3M-ESPE), Telio CAD Temp (Ivoclar Vivadent), Vita CAD Temp (Vita), Temporary CB (FormLab), Dentca (Dentca), and Bego VarseoSmile Crown Plus (Bego). The sixty disks from each polymer were then divided into the six following groups: no treatment, thermocycling, fatigue, thermocycling and coffee, distilled water and finally UV Light. Prior to any treatment, the color coordinates CIE L*a*b*, were registered first. The non-treated groups were fractured using the Instron Universal Testing Machine to obtain flexural strength values. Thermocycling consisted of placing the specimens in 30 seconds 5°C water and then 30 seconds in 55°C water for 5,000 cycles. Fatigue testing consisted of cyclic loading the disk specimens by calculating 60% of the mean load to failure from the non-treated group and subjecting them to 50,000 cycles. The third group was placed under thermocycling for 1,500 cycles and then placed in coffee for 15 days. Another group was placed in distilled water for 15 days. Finally, the UV light treatment consisted of exposing the disk specimens to UV light for ten hours over the course of five days. After treatment, the color coordinates were recorded again and fractured using the Instron Universal Testing Machine. The data was analyzed for any statistically significant differences using ANOVA with a<0.05. RESULTS: The flexural strength values were highest for Telio CAD Temp, that was affected only by UV light via a statistical analysis. ProTemp was second highest followed by Bego VarseoSmile Crown Plus, Dentca, Temporary CB, Vita CAD Temp and finally Jet Tooth Shade. Color differences were highest for Dentca followed by Jet Tooth Shade, ProTemp, Telio CAD Temp, Temporary CB and finally Vita CAD Temp. UV light and thermocycling/ coffee had the highest impact. CONCLUSION: Telio CAD Temp had the highest overall flexural strength and was resistant to all post fabrication treatments except for UV light. ProTemp had the second highest overall flexural strength but was susceptible to multiple post fabrication treatments like distilled water, fatigue, and aging. The printed specimens had flexural strength values lower in the middle range of all tested materials. In terms of treatment, UV light and coffee/thermocycling had the biggest impact on the overall color stability values. Powder and Liquid based PMMA had the lowest overall flexural strengths.

碩士
國立成功大學
醫學工程研究所碩博士班
96
Traditional radiographic measures of the lower limb to indicate abnormal loading are common and critical. To improve the quality, every effort is made to maintain a standardized position and reduce the inconsistency from inter- and intra-observer variances. Unfortunately, many other factors still alter the accuracy and reproducibility. Besides, only few data are available from traditional radiographic two dimensional measurement and clinicians couldn’t have the spatial data from the identical posture without three dimensional measures, like computed tomography. In the laboratory, however, these problems could be easily resolved by the motion tracking system, and higher resolution was proved. In clinical, motion tracking system had been incorporated into the field of computer assisted orthopaedic surgery (CAOS). To our knowledge, most studies comparing the differences between navigation and manual method only with the traditional radiographic measures. Few studies used the optical motion tracking system as a tool for measurement and compared the results of different surgical methods. The aim of the study is to expand the use of current navigation system to the conventional total knee arthroplasty for the function of spatial measurement by its integrating optical tracking system. First, the feasibility of the combination of the optical tracking measurement system with conventional total knee arthroplasty needs verification. Second, use the spatial results of lower extremity alignments in primary total knee arthroplasty but performed with different surgical techs and find the differences. Third, set up the database of lower extremity alignments in primary total knee arthroplasty with different surgical techs for future correlations with the clinical outcomes. Some potential risks and the surgical differences were also analyzed and addressed.

碩士
國立臺灣科技大學
電子工程系
89
In the thesis, we propose a novel hybrid fiber amplifier, and it is connected with erbium-doped fiber amplifier and fiber Raman amplifier. The hybrid fiber amplifier structure can provide the property of both EDFA and Raman amplifier. It maintains the stabilization of EDFA character and has great gain of Raman amplifier. We add L-band EDFA to extend transmission bandwidth. The L-band EDFA is made by conventional erbium doped fiber, utilizing the phenomenon of EDFA gain shift. Therefore, we utilize L-band EDFA to extend transmissible capacity. Because the Raman amplifier can be operated at any wavelength windows, it can compensate the C-band and L-band of amplifier. For Raman amplifier, the C-band and L-band can be used. It just needs to adjust the wavelength of Raman pump. Because it strongly depended on the wavelength and power of Raman pump, it is a broadband component, and it is widely used. The novel hybrid fiber amplifier can bring great capacity for conventional EDFA. It used bidirectional data flowed to help upgrade the sys