Дисертації з теми "Fibel"
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1
Vielitz, Kathrin. "Die Granatscheibenfibeln der Merowingerzeit /." Montagnac : Ed. Mergoil, 2003. http://www.loc.gov/catdir/toc/fy0608/2004545491.html.
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Kahl, Heike, Frank Hinte, Tobias Braun, Frances Fischer, Matthias Labisch, Stefanie Lippitsch, and Ken Mertens. "SchülerInnen Fibel: Das Buch mit Wirkung #4." Deutsche Kinder- und Jugendstiftung GmbH, 2020. https://slub.qucosa.de/id/qucosa%3A75205.
Повний текст джерелаАнотація:
Die Schüler*innenfibel ist DAS Nachschlagewerk für sächsische Schülervertreter*innen. Es basiert auf jahrelangen Erfahrungen innerhalb der Schüler*innenmitwirkung und in der Programmarbeit von Mitwirkung mit Wirkung. Ihr erfahrt alles über die gesetzlichen Grundlagen von SV und wie ihr eure Interessen in den Gremien eurer Schule vertreten könnt. Praktische Tipps für euren SV-Alltag, die Organisation von Projekten und den Umgang mit Konflikten ergänzen die theoretischen Grundlagen und machen euch fit fürs Handeln und Mitmischen!
Redaktionsschluss: 15.12.2020
3
Striewe, Karin. "Studien zur Nauheimer Fibel und ähnlichen Formen der Spätlatènezeit /." Espelkamp : M. Leidorf, 1996. http://catalogue.bnf.fr/ark:/12148/cb392755527.
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Teistler, Gisela [Verfasser], and Heidemarie [Akademischer Betreuer] Kemnitz. "Schulbücher als bildungsgeschichtliche Quellen : das Beispiel der Fibel / Gisela Teistler ; Betreuer: Heidemarie Kemnitz." Braunschweig : Technische Universität Braunschweig, 2008. http://d-nb.info/1175820385/34.
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5
Jollivet, Clemence. "Specialty Fiber Lasers and Novel Fiber Devices." Doctoral diss., University of Central Florida, 2014. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/6295.
Повний текст джерелаАнотація:
At the Dawn of the 21st century, the field of specialty optical fibers experienced a scientific revolution with the introduction of the stack-and-draw technique, a multi-steps and advanced fiber fabrication method, which enabled the creation of well-controlled micro-structured designs. Since then, an extremely wide variety of finely tuned fiber structures have been demonstrated including novel materials and novel designs.
As the complexity of the fiber design increased, highly-controlled fabrication processes became critical. To determine the ability of a novel fiber design to deliver light with properties tailored according to a specific application, several mode analysis techniques were reported, addressing the recurring needs for in-depth fiber characterization.
The first part of this dissertation details a novel experiment that was demonstrated to achieve modal decomposition with extended capabilities, reaching beyond the limits set by the existing mode analysis techniques. As a result, individual transverse modes carrying between ~0.01% and ~30% of the total light were resolved with unmatched accuracy. Furthermore, this approach was employed to decompose the light guided in Large-Mode Area (LMA) fiber, Photonic Crystal Fiber (PCF) and Leakage Channel Fiber (LCF). The single-mode performances were evaluated and compared. As a result, the suitability of each specialty fiber design to be implemented for power-scaling applications of fiber laser systems was experimentally determined.
The second part of this dissertation is dedicated to novel specialty fiber laser systems. First, challenges related to the monolithic integration of novel and complex specialty fiber designs in all-fiber systems were addressed. The poor design and size compatibility between specialty fibers and conventional fiber-based components limits their monolithic integration due to high coupling loss and unstable performances. Here, novel all-fiber Mode-Field Adapter (MFA) devices made of selected segments of Graded Index Multimode Fiber (GIMF) were implemented to mitigate the coupling losses between a LMA PCF and a conventional Single-Mode Fiber (SMF), presenting an initial 18-fold mode-field area mismatch. It was experimentally demonstrated that the overall transmission in the mode-matched fiber chain was increased by more than 11 dB (the MFA was a 250 ?m piece of 50 ?m core diameter GIMF). This approach was further employed to assemble monolithic fiber laser cavities combining an active LMA PCF and fiber Bragg gratings (FBG) in conventional SMF. It was demonstrated that intra-cavity mode-matching results in an efficient (60%) and narrow-linewidth (200 pm) laser emission at the FBG wavelength.
In the last section of this dissertation, monolithic Multi-Core Fiber (MCF) laser cavities were reported for the first time. Compared to existing MCF lasers, renown for high-brightness beam delivery after selection of the in-phase supermode, the present new generation of 7-coupled-cores Yb-doped fiber laser uses the gain from several supermodes simultaneously. In order to uncover mode competition mechanisms during amplification and the complex dynamics of multi-supermode lasing, novel diagnostic approaches were demonstrated. After characterizing the laser behavior, the first observations of self-mode-locking in linear MCF laser cavities were discovered.Ph.D.
Doctorate
Optics and Photonics
Optics and Photonics
Optics and Photonics
6
Horvath, A. Elisabet. "The effects of cellulosic fiber charges on polyelectrolyte adsorption and fiber-fiber interactions." Doctoral thesis, Stockholm : Department of Fibre and Polymer Technology, Royal Institute of Technology, 2006. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-4158.
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Wern, Chien Wei. "Fiber and fiber-matrix interface effects on the orthogonal cutting of fiber reinforced plastics /." Thesis, Connect to this title online; UW restricted, 1995. http://hdl.handle.net/1773/7133.
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Ratu, Ricky Novry. "Development of polypropylene fiber as concrete reinforcing fiber." Thesis, University of British Columbia, 2016. http://hdl.handle.net/2429/57779.
Повний текст джерелаАнотація:
The objective of this research is to produce polypropylene fibers with improved interface bonding with a concrete matrix. The Laboratory Mixing Extruder paired with the Randcastle fiberline drawing device was used for producing fiber from polypropylene (PP) chips. A target diameter of 0.5 mm fiber was obtained from a 2-stage process in the production line. The effort to improve the fiber surface by applying aluminum oxide sol-gel coating was unsatisfactory due to the failure of the coating materials to adhere to the fiber. Incorporating silica fume (SF) powder in the fiber extrusion process enhanced fiber properties. Silica fume co-extruded PP (SFPP) fiber has different characteristics in appearance, flexibility and surface roughness. Most importantly, the co-extrusions produced significance improvements in surface characteristics. Silica fume particles caused significant changes in the surface roughness of the fiber and contributed to the improved bonding performance in a cement-based matrix. The inclusion of the extruded fibers in a concrete matrix also improved the flexural toughness. Additional testing was conducted to examine the performance of extruded fiber in preventing plastic shrinkage cracking. Fiber reinforced mortar containing RPP and SFPP fibers were evaluated. Based on total crack area reduction efficiency, and crack width reduction efficiency SFPP fibers performed better than RPP fibers. These results indicate that the objective of developing a concrete reinforcing fiber using laboratory equipment was successfully achieved. The inclusion of silica fume particles in the extrusion process significantly changed the properties of the fiber and therefore contributed to the performance of these extruded fibers in the concrete matrix.Applied Science, Faculty of
Civil Engineering, Department of
Graduate
9
Fernberg, Patrik. "Fiber bridging concepts applied to short fiber composites." Licentiate thesis, Luleå tekniska universitet, 2000. http://urn.kb.se/resolve?urn=urn:nbn:se:ltu:diva-18743.
Повний текст джерелаАнотація:
Polymer composite materials are in wide-spread use in the transportation industry. In aerospace industry the use these materials are established while in automotive industry the interest is increasing. The attention of automotive industry is to a great deal focused on various kinds of molded composites such as glass mat reinforced thermoplastics (GMT) and sheet molding compound (SMC). Their interest is to a large extent driven by the possibility to manufacture components of complex geometry in a cost- efficient process with these materials. An increasing number of car and truck manufacturers are using SMC for external panels such as trunk covers, hoods, roofs and spoilers. A property of obvious importance for an external car- or truck-panel is its capacity to withstand impact. In this context, improved understanding of crack growth and toughening mechanisms of the material is of great interest. A major part of the work presented in this thesis is driven by an interest to increase the understanding of how material composition and microstructure of short fiber composites influence their overall fracture behaviour. In materials such as metals and unreinforced polymers, linear elastic fracture mechanics (LEFM) is widely used, often with great success, both in design and in development of new materials. Unfortunately, problems arise when LEFM is applied to short fiber composites. This is due to the large process zone that develops ahead of a crack in these materials. The fundamental assumption of LEFM, that the damage zone at the tip of the crack is small compared to crack length, is often violated in experiments. The presented thesis considers a different approach, in which the damage ahead of a crack tip is described by a bridging-law. By considering the bridging-law as the major failure property of the material, a coupling between mechanisms acting on a microscale and the macroscopic failure behaviour can be established. No such information can be obtained using a LEFM approach where the material behaviour is described in terms of a single value, the fracture toughness. Bridging-laws for three different short fiber composites are experimentally determined and presented in the first paper of the thesis. A matter of key importance for future work in this field is that there are methods available for experimental verification of the suggested fiber bridging approach. Optical strain field measurement methods are therefore very useful. The thesis contains a pilot study to evaluate the use of two recently developed optical methods , Stereoscopic Digital Speckle Photography (Stereo-DSP) and combined DSP-DSPI (Digital Speckle Pattern Interferometry), for measurements of fracture behaviour of notched short fiber composites. We found Stereo-DSP to be a versatile technique that can be used when knowledge of overall displacement fields is required. The combined technique can with advantage be used when detailed information about large deformation at small areas is of interest, e.g. the complex fiber bridging interaction at the crack tip of a short fiber composite. The last paper in the thesis presents a study where the influence of fiber surface treatment on transverse cracking in cross-ply laminates was investigated. In the case of tubes and pressure vessels, the formation of transverse cracks ultimately leads to leakage since cracks connect and form a path through the wall. In the presented study, our ambition was to investigate the influence of film former polymer on transverse cracking properties of cross-ply laminates.Both onset of transverse cracking and tendency for multiple crack development were strongly affected by the different film formers. The strong film former effect was proposed to be due to a combination of improved interfacial adhesion and the plasticizing effect from the film former on the interphase region. The thesis is composed by the following papers: Patrik Fernberg, Lars Berglund, Bridging law and toughness characterisation of CSM and SMC composite, to be submitted. Angelica Andersson, Patrik Fernberg, Mikael Sjödahl, Optical methods to study fracture of notched glass mat composites. Proceedings of the International Conference on trends in Optical Nondestructive Testing, Lugano, Switzerland, May 3-6, 2000 (in press). Patrik Fernberg, Lars Berglund, Effects of glass fiber size composition (film former type) on transverse cracking in cross-ply laminates. Accepted for publication in Composites, Part A.Godkänd; 2000; 20070318 (ysko)
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Smith, Kevin H. "In-fiber Optical Devices Based on D-fiber." BYU ScholarsArchive, 2005. https://scholarsarchive.byu.edu/etd/291.
Повний текст джерелаАнотація:
This dissertation presents the fabrication and analysis of in-fiber devices based on elliptical core D-shaped optical fiber. Devices created inside optical fibers are attractive for a variety of reasons including low loss, high efficiency, self-alignment, light weight, multiplexibility, and resistance to electromagnetic interference. This work details how D-fiber can be used as a platform for a variety of devices and describes the creation and performance of two of these devices: an in-fiber polymer waveguide and a surface relief fiber Bragg grating. In D-fiber the core is very close to the flat side of the ‘D’ shape. This proximity allows access to the fields in the fiber core by removal of the cladding above the core. The D-fiber we use also has an elliptical core, allowing for the creation of polarimetric devices. This work describes two different etch processes using hydrofluoric acid (HF) to remove the fiber cladding and core. For the creation of devices in the fiber core, the core is partially removed and replaced with another material possessing the required optical properties. For devices which interact with the evanescent field, cladding removal is terminated before acid breaches the core. Etching fibers prepares them for use in the creation of in-fiber devices. Materials are placed into the groove left when the core of a fiber is partially removed to form a hybrid waveguide in which light is guided by both the leftover core and the inserted material. These in-fiber polymer waveguides have insertion loss less than 2 dB and can potentially be the basis for a number of electro-optic devices or sensors. A polarimetric temperature sensor demonstrates the feasibility of the core replacement method. This work also describes the creation of a surface relief fiber Bragg gratings (SR-FBGs) in the cladding above the core of the fiber. Because it is etched into the surface topography of the fiber, a SR-FBG can operate at much higher temperatures than a standard FBG, up to at least 1100 degrees Celsius. The performance of a SR-FBG is demonstrated in temperature sensing at high temperatures, and as a strain sensor.
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Сад, Альона Юріївна. "Optical fiber." Thesis, Київський національний університет технологій та дизайну, 2017. https://er.knutd.edu.ua/handle/123456789/7391.
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Misner, Scottie. "Dietary Fiber." College of Agriculture and Life Sciences, University of Arizona (Tucson, AZ), 2006. http://hdl.handle.net/10150/146440.
Повний текст джерелаАнотація:
2 pp.Even dietary fiber is not considered a nutrient, health professionals agree that most Americans don't get nearly enough in their diet. So, why is fiber important? what does fiber do? This article answers the questions regarding diet fiber by providing information on the practical aspects of fiber in the diet as well as food sources and their dietary fiber content.
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Misner, Scottie, Evelyn Whitmer, and Traci Armstrong Florian. "Dietary Fiber." College of Agriculture and Life Sciences, University of Arizona (Tucson, AZ), 2013. http://hdl.handle.net/10150/298146.
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Wang, Xiaozhen. "Characterization of Fiber Tapers for Fiber Devices and Sensors." Thèse, Université d'Ottawa / University of Ottawa, 2012. http://hdl.handle.net/10393/23330.
Повний текст джерелаАнотація:
Fiber tapers have attracted much attention and have been successfully employed in various applications, ranging from resonators, filters, interferometers to sensors. This thesis studies the properties of fiber tapers for the purpose of making tapered-based devices and sensors in aerospace related application where small size and light weight are critical. This thesis includes theoretical derivation and experimental verifications of distributed mode coupling in tapered single-mode fibers (SMFs) with high-resolution optical frequency-domain reflectometry (OFDR) technique. The studies are realized with OFDR through phase detection of a Mach-Zehnder interferometer (MZI), which measures local refractive index change relative to the reference arm. The wavelength shifts converted by the phase change give the group index differences between the fundamental mode and higher-order modes of fiber tapers. The energy re-distribution is observed in Rayleigh backscatter amplitude as a function of fiber length with a ~13µm resolution over the entire fiber taper, and group index difference between core and cladding modes is measured with a spatial resolution of ~2cm by using autocorrelation data processing. The thermal and mechanical properties of fiber tapers have also been characterized with OFDR. The cross-correlation wavelength shift is related to the refractive index change of the modes. It is shown that residual stress induced by the tapering process results in the inhomogeneous thermal property, which can be significantly reduced by an annealing treatment. A fiber taper with a waist diameter of ~6µm has a force sensitivity of ~620.83nm/N, ~500 times higher than that of SMF. Furthermore, polarization-preserving character of tapered polarization-maintaining fibers (PMFs) is evaluated by OFDR-based distributed birefringence along tapered PMFs. Three tapered-based micro-fiber devices have been used as effective mode selecting components to build narrow-linewidth tunable Erbium-doped fiber ring lasers. The fabrication is easy and at a low cost. 1) a tapered fiber tip forms multimode interference mechanism; 2) a two-taper MZI has been demonstrated by splitting/combining the fundamental mode and higher-order modes through fiber tapers and is tuned by bending one taper waist; 3) a novel tunable fiber Fabry-Perot filter, consisting of a hollow-core photonic bandgap fiber and a micro-fiber, is employed in the reflection mode.
15
Wang, Long. "Fiber Based Mode Locked Fiber Laser Using Kerr Effect." University of Dayton / OhioLINK, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=dayton1454081445.
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Suzuki, Shigeru. "Optical Fiber Devices: Novel Fiber Lasers and Image Amplifier." Diss., The University of Arizona, 2008. http://hdl.handle.net/10150/194910.
Повний текст джерелаАнотація:
Three fiber based optical devices: all phosphate glass fiber laser, single hybrid mode fiber laser, and fiber image amplifier, were investigated in this dissertation. Phosphate fiber Bragg grating (FBG) is desired to improve performance of recently developed high power single frequency lasers that were based on highly rare earth ion doped phosphate fibers because these lasers were fabricated with silica FBGs that have incompatible properties with standard phosphate glasses. Since standard phosphate glasses are not photosensitive, Ge-doped phosphate glasses were fabricated and their UV-photosensitivity was examined. A phosphate fiber that has Ge-doped core showed UV index changes more than ~1.1 × 10⁻³. An all-phosphate fiber laser was also demonstrated with the Ge-doped phosphate FBG. Single hybrid mode fiber laser that involves a large area mode in cavity formation was demonstrated. The fiber laser consists of an Er-doped active fiber and two FBGs. One FBG was a core-cladding mode converter, and the other FBG was a narrowband high reflector that selects the lasing wavelength and mode. This approach for designing a laser cavity provides a much larger mode area than conventional large-mode-area stepindex fibers, and is supposed to suitable for a high power fiber laser. Also this configuration allows us to make novel ring-like cavities and sensor devices that consist of higher mode of optical fibers. Image amplifier based on a highly rare earth ion doped phosphate fiber is a unique approach to overcome weakness of widely used image intensifiers that lose a lot of information in the image, such as spectral distribution, polarization, and phase. Image amplification with a 19-pixel optical image amplifier array based on high gain per unit length Yb³⁺-doped phosphate glass optical fiber was demonstrated. A 10-cm of the 19- pixel fiber image amplifier provides spatially uniform image amplification with gain of 30 dB/pixel or more. This image amplifier responds quickly to changes in the image position – with potential for GHz-level or higher frame rates. This unique approach for image amplification offers low noise, high gain, and wide field of view in a compact fiber-based device.
17
Cassino, Christopher Daniel. "Detection of fiber fracture in Unidirectional Fiber Reinforced Composites using an In-Plane Fiber Optic Sensor." Thesis, Virginia Tech, 2002. http://hdl.handle.net/10919/32419.
Повний текст джерелаАнотація:
Fiber reinforced polymers (FRP) are an efficient and inexpensive method of repairing deteriorating infrastructure. FRP sheets can be applied to spalling bridge sections and columns to prevent further deterioration and increase stiffness. However, the effect of the environment on the long-term durability of FRP and how the various damage mechanisms initiate and develop are not known. Systems for structural health monitoring are being sought as a means of managing important components in transportation systems as assets in light of modern life cycle cost concepts. This study characterizes a fiber optic sensor for use in detecting acoustic emissions (AE) in FRP. The results of AE analysis (signal amplitude, frequency spectra, MARSE, and in-plane displacement) caused by simulated fiber fracture experiments and other types of mechanical loading in FRP test coupons are reported. The applications to the development of FRP structural health monitoring systems are also discussed.Master of Science
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Joshi, Ninad Milind. "Study of the Effect of Unidirectional Carbon Fiber in Hybrid Glass Fiber / Carbon Fiber Sandwich Box Beams." University of Dayton / OhioLINK, 2013. http://rave.ohiolink.edu/etdc/view?acc_num=dayton1386188162.
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Song, Jiawei, and Jiawei Song. "Nd-doped Fiber Lasers and Fiber Amplifiers at 9xx nm." Thesis, The University of Arizona, 2016. http://hdl.handle.net/10150/620827.
Повний текст джерелаАнотація:
The lasers operating in the wavelength range of 900 - 1000 nm have caused intense attention because they are in great demands for: 1. Highpower blue and deep UV laser generation 2. High power single-mode pump laser source 3. Light detection and Lidar , etc. And now, there are actually many different types of lasers can generate laser in this wavelength range. For example, Nd and Yb doped fiber laser, Nd and Yb doped glass and crystal lasers, OPO and SHG laser, etc. Among all this options, we decided to study the Nd-doped fiber laser for their outstanding advantages: 1. As fiber laser, it possess all the advantages of any fiber lasers have, such as: high power scalability, excellent beam quality, high spectral and intensity stability, super compactness, robustness and reliability. 2. Comparing to other rare-earth-ion, the Nd^3+ ions have a more broad emission wavelength range from 900-950 nm. My goals for doing this thesis research are:1.Experimentally and theoretically investigate Nd-doped fiber lasers and amplifiers at 9xx nm. 2. Develop 9xx nm single frequency fiber lasers and amplifiers. 3.Obtain directions for developing high power single-frequency Nd-doped fiber laser sources at 9xx nm. To achieve these goals, 1. Nd-doped fiber lasers at 934 nm were investigated. 2. Core-pumped and cladding-pumped Nd-doped fiber amplifiers are also investigated. 3. The simulation of the Nd-doped fiber amplifiers have been done.
20
Smulski, Stephen John. "Flexural behavior of a glass fiber reinforced wood fiber composite." Diss., Virginia Polytechnic Institute and State University, 1985. http://hdl.handle.net/10919/53596.
Повний текст джерелаАнотація:
The static and dynamic flexural properties of a wood fiber matrix internally reinforced with continuous glass fibers were investigated. When modelled as a sandwich composite, the static flexural modulus of elasticity (MOE) of glass fiber reinforced hardboard could be successfully predicted from the static flexural MOE of the wood fiber matrix, and the tensile MOE and effective volume fraction of the glass fiber reinforcement. Under the same assumption, the composite modulus of rupture (MOR) is a function of the reinforcement tensile MOE and effective volume fraction, and the matrix stress at failure. The composite MOR was predicted on this basis with limited success.
The static flexural modulus of elasticity, dynamic modulus of elasticity, and modulus of rupture of glass fiber reinforced hardboard increased with increasing effective reinforcement volume fraction. The logarithmic decrement of the composite decreased with increasing effective reinforcement volume fraction. Excellent linear correlation found among flexural properties determined in destructive static tests and nondestructive dynamic tests demonstrated the usefulness of dynamic test methods for flexural property evaluation.
The short-term flexural creep behavior of glass fiber reinforced hardboard was accurately described by a 4-element linear viscoelastic model. Excellent agreement existed between predicted and observed creep deflections based on nonlinear regression estimates of model parameters.Ph. D.
21
Li, Hongying. "Fiber tracking and fiber architecture description in cardiac DT-MRI." Thesis, Lyon, INSA, 2013. http://www.theses.fr/2013ISAL0125.
Повний текст джерелаАнотація:
La connaissance de l’architecture tridimensionnelle (3D) des fibres est cruciale dans la compréhension de la fonction du cœur humain. L’imagerie par résonance magnétique du tenseur de diffusion (IRM-DT) est une technique permettant de mesurer la diffusion des molécules d’eau dans des tissus humains, et donc d’étudier de manière non-invasive l’architecture 3D des fibres du cœur humain. Dans l’IRM-TD cardiaque, la tractographie des fibres est essentielle pour représenter et visualiser l’architecture des fibres, mais souvent utilisée qualitativement comme une dernière étape qui consiste à visualiser sur l’écran l’architecture myocardique obtenue à partir des données IRM-TD. Cependant, cette visualisation qualitative n’est pas suffisante pour décrire de manière objective et complète l’architecture des fibres. L’objectif de cette thèse est de développer de nouvelles approches pour la tractographie et pour la description quantitative de l’architecture des fibres cardiaques du cœur humain en IRM-TD cardiaque. Les travaux de cette thèse se focalisent sur trois axes. Le premier est le développement d’un algorithme de tractographie probabiliste, qui prend en compte la corrélation spatiale des fibres pendant le suivi des fibres myocardiques. Les résultats expérimentaux montrent que la méthode proposée est robuste au bruit. Les fibres produites sont plus régulières et plus lisses, et la configuration des fibres cardiaques est plus facile à observer. Le second axe concerne une nouvelle notion de dépliement de fibres pour décrire les fibres du cœur humain, qui sont souvent complexes dans l’espace 3D. L’idée est d’analyser cette architecture 3D dans un espace réduit à deux dimensions (2D), en utilisant une technique d’apprentissage de variété. L’approche de dépliement proposée permet la description quantitative de l’architecture 3D de fibres cardiaques dans un plan 2D. Les résultats montrent qu’il est beaucoup plus facile d’observer et d’étudier les caractéristiques des fibres cardiaques après les avoir dépliées, et qu’il semble exister des formes de fibres caractéristiques du cœur humain. Le dernier axe consiste en la fusion de fibres, qui est obtenue en moyennant les fibres selon une grille. Cette approche fournit des architectures de fibres simplifiée à différentes échelles, et permet de mieux mettre en évidence la configuration des fibres cardiaquesIt is important to study the cardiac fiber architecture in order to understand the heart function. Diffusion tensor MRI (DT-MRI) is the only noninvasive technique that allows studying cardiac fiber architecture in vivo. Tractography is essential in representing and visualizing cardiac fiber architecture in DT-MRI, but is often employed qualitatively. The motivation of this thesis is to develop technique for studying the cardiac fiber architecture from the fiber tracts provided by the tractography process in cardiac DT-MRI. Our goal is to develop tractography algorithm and approaches for the quantitative description of cardiac fiber architecture. My work is composed of three main axis. The first is the development of a probabilistic tractography algorithm, which takes fiber spatial correlation into accounts in tracing fibers. Experimental results show that the proposed method is meaningfully more robust to noise than the streamlining method, and produces more regular and smoother fibers, which enables cardiac fiber configurations to be more clearly observed. The second concerns a new framework, namely cardiac fiber unfolding, which is an isometric mapping. Our fiber unfolding framework allows the quantitative description of three dimensional cardiac fiber architecture in a two dimensional plan. Our experimental results show that fiber tract pattern can be observed much easier by unfolding them in a plane, and several cardiac fiber patterns were found. The last axis consists in merging fibers, which is achieved by averaging fibers according to a grid. This fiber merging approach provide simplified fiber architecture at different scale as output that highlights the cardiac fiber configuration
22
Fierling, Yannick P. H. "Analysis of fiber-reinforced composite plates utilizing curvilinear fiber trajectories." Thesis, This resource online, 1995. http://scholar.lib.vt.edu/theses/available/etd-01312009-063412/.
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Myrén, Niklas. "Poled fiber devices." Doctoral thesis, KTH, Physics, 2005. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-262.
Повний текст джерелаАнотація:
The topic of this thesis is the development of devices for telecom applications based on poled optical fibers. The focus is on a specific function, optical switching/modulation.
Some of the most important results are summarized below. Optical switching at telecom wavelengths (1.55 μm) is demonstrated in an all-fiber switch based on a fiber with internal electrodes. The fiber is made electro-optically active with a thermal poling process in which a strong electric field is recorded in the glass at a temperature of 255 °C. After poling, the fiber is put in one arm of a Mach-Zehnder interferometer and by applying a voltage across the two electrodes the refractive index is modulated and the optical signal switched from one output port to the other. A switching voltage of 190 V at 1550 nm was achieved, which to the best of our knowledge is the lowest value reported. By carefully matching the lengths of the fibers in the two arms of the interferometer the optical bandwidth could be made as large as 20 nm. The extinction ratio, determined by the power ratio in the two arms, was 30 dB and the highest modulation frequency was 30 MHz. Poled fibers were packaged to increase the thermal and mechanical stability and to make handling easier. 40 Gb/s transmission test through the device showed no bit-error-rate performance degradation. Protection switching of a 10 Gb/s signal is also demonstrated.
The depletion region in a poled fiber was found to be wedge-shaped and very wide, 13 μm and completely overlapped with the core. In a time-resolved poling experiment the recorded electric field was measured. The sign of the field changed after ~20 min, when the depletion region passed through the core, which led to the conclusion that an electric field is present also outside of the depletion region.
A ring laser was constructed with an erbium doped fiber as the gain medium. A fiber modulator was placed inside the cavity and when a small RF signal, with a frequency matched to the cavity ground frequency, was applied to the modulator the laser was modelocked. The output pulse train contained pulses of sub ns duration and is the first demonstration of mode-locking using poled fibers.
A sampled grating with 16 channels spaced by 50 GHz was inserted into the cavity. The fiber modulator had optical bandwidth of 7 nm with center wavelength that depends on the applied voltage. By applying of 10 – 210 V to the modulator it was possible to tune the laser to 11 of the 16 channels for a total tuning range of over 4 nm.
A scheme to deposit 1 μm thin silver electrodes inside the holes of an optical fiber is demonstrated together with a new method of creating periodic electrodes by periodically ablating the silver film electrodes. The periodic electrodes are used to create a quasi-phase matched (QPM) nonlinearity in a fibers which is showed in a proof of principle experiment.
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Myrén, Niklas. "Poled fiber devices /." Stockholm, 2005. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-262.
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Bock, Katherine J. "Femtosecond Fiber Lasers." Thèse, Université d'Ottawa / University of Ottawa, 2012. http://hdl.handle.net/10393/23391.
Повний текст джерелаАнотація:
This thesis focuses on research I have done on ytterbium-doped femtosecond fiber lasers. These lasers operate in the near infrared region, lasing at 1030 nm. This wavelength is particularly important in biomedical applications, which includes but is not limited to confocal microscopy and ablation for surgical incisions. Furthermore, fiber lasers are advantageous compared to solid state lasers in terms of their cost, form factor, and ease of use. Solid state lasers still dominate the market due to their comparatively high energy pulses. High energy pulse generation in fiber lasers is hindered by either optical wave breaking or by multipulsing. One of the main challenges for fiber lasers is to overcome these limitations to achieve high energy pulses. The motivation for the work done in this thesis is increasing the output pulse peak power and energy. The main idea of the work is that decreasing the nonlinearity that acts on the pulse inside the cavity will prevent optical wave breaking, and thus will generate higher energy pulses. By increasing the output energy, ytterbium-doped femtosecond fiber lasers can be competitive with solid state lasers which are used commonly in research. Although fiber lasers tend to lack the wavelength tuning ability of solid state lasers, many biomedical applications take advantage of the 1030 µm central wavelength of ytterbium-doped fiber lasers, so the major limiting factor of fiber lasers in this field is simply the output power. By increasing the output energy without resorting to external amplification, the cavity is optimized and cost can remain low and economical. During verification of the main idea, the cavity was examined for possible back-reflections and for components with narrow spectral bandwidths which may have contributed to the presence of multipulsing. Distinct cases of multipulsing, bound pulse and harmonic mode-locking, were observed and recorded as they may be of more interest in the future. The third-order dispersion contribution from the diffraction gratings inside the laser cavity was studied, as it was also considered to be an energy-limiting factor. No significant effect was found as a result of third-order dispersion; however, a region of operation was observed where two different pulse regimes were found at the same values of net cavity group velocity dispersion. Results verify the main idea and indicate that a long length of low-doped gain fiber is preferable to a shorter, more highly doped one. The low-doped fiber in an otherwise equivalent cavity allows the nonlinear phase shift to grow at a slower rate, which results in the pulse achieving a higher peak power before reaching the nonlinear phase shift threshold at which optical wave breaking occurs. For a range of net cavity group velocity dispersion values, the final result is that the low doped fiber generates pulses of approximately twice the value of energy of the highly-doped gain fiber. Two techniques of mode-locking cavities were investigated to achieve this result. The first cavity used NPE mode-locking which masked the results, and the second used a SESAM for mode-locking which gave clear results supporting the hypothesis.
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Lestoquoy, Guillaume. "Multimaterial fiber electronics." Thesis, Massachusetts Institute of Technology, 2014. http://hdl.handle.net/1721.1/87929.
Повний текст джерелаАнотація:
Thesis: Ph. D., Massachusetts Institute of Technology, Department of Electrical Engineering and Computer Science, 2014.Cataloged from PDF version of thesis.
Includes bibliographical references (pages 119-129).
As the number of materials that are thermally-drawable into fibers is rapidly expending, numerous new multimaterial fiber architectures can be envisioned and fabricated. High-melting temperature metals, compound materials, composite, conductive or ferroelectric polymers: the broad diversity of these materials' nature and properties, combined with various post-fabrication treatments recently developed (poling, annealing, injection, coating, capillary breakup), enable the making of novel in-fiber, stand-alone-fiber and fiber-array devices. In this thesis, we demonstrate a wide variety of novel multimaterial fiber capabilities at all these levels, focusing specifically on new electronic functions. First, the implementation of conductive polymer as in-fiber current buses is shown to enable distributed light sensing and modulation along a single fiber, by inducing transmission-line effects in d.c. and a.c. operation. Next, the design and operation of a photosensing fiber specially treated to detect explosives is presented, and the sensitivity of this fiber device is shown to meet state-of-the-art industry standards. A novel large-interface-area design for dielectric fibers is then presented, which enables both energy storage in flexible fiber capacitors as well as enhanced acoustic transduction in piezoelectric fibers. The flexibility as well as the assembly into arrays of the latter are shown to enable the shaping of a pressure field in all three dimensions of space. Finally, a novel thermal-gradient capillary breakup process for silica-based fibers is shown, enabling the fabrication of silicon-in-silica micro spheres and rectifying devices. Taken as a whole, these new capabilities greatly expand the breadth of functionality of multimaterial fibers, further paving the way towards highly multifunctional, wholly integrated electronic fiber devices and fabrics that can collect, store and transduce energy in all of its forms.
by Guillaume Lestoquoy.
Ph. D.
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Oblapenko, B. S. "Fiber optic cabling." Thesis, Сумський державний університет, 2012. http://essuir.sumdu.edu.ua/handle/123456789/28545.
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Battiato, James Michael 1966. "Fiber Bragg gratings." Diss., The University of Arizona, 1998. http://hdl.handle.net/10150/288905.
Повний текст джерелаАнотація:
The properties of fiber Bragg gratings are investigated theoretically and experimentally. The effects of experimental parameters on grating characteristics are modeled for both uniform and non-uniform gratings. Particular emphasis is placed on the formation of fiber Bragg gratings tilted at 45 degrees with respect to the fiber axis in single mode fibers. In this case, light is coupled out of the fiber in a surface normal manner. Several fabrication methods for producing tilted fiber gratings are explored and characterized. The most efficient gratings are obtained with a prism coupling technique. Experimental tilted grating performance is shown to be in good agreement with the predictions of a two-dimensional coupled mode theory. Fiber gratings are also used to demonstrate an Er/Nd co-doped fiber laser. This dual wavelength laser is formed with a common cavity and common gain medium.
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Jin, Chuhang. "Microstructured Terahertz Fiber." Thesis, KTH, Tillämpad fysik, 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-265667.
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Zhou, Renjie. "Developments of Narrow-Linewidth Q-switched Fiber Laser, 1480 nm Raman Fiber Laser, and Free Space Fiber Amplifier." Thesis, The University of Arizona, 2011. http://hdl.handle.net/10150/202931.
Повний текст джерелаАнотація:
In the first chapter, a Q-switched fiber laser that is capable of generating transform-limited pulses based on single-frequency fiber laser seeded ring cavity is demonstrated. The output pulse width can be tuned from hundreds of nanoseconds to several microseconds. This Q-switched ring cavity fiber laser can operate over the whole C-band. In addition, a theoretical model is developed to numerically study the pulse characteristics, and the numerical results are in good agreements with the experimental results. In the next chapter, a Raman fiber laser is developed for generating signal at 1480 nm. Initial experimental results has demonstrated generating of Raman laser at 1175 nm, 1240 nm, 1315 nm, and 1395 nm wavelength. Finally, a free space fiber amplifier is studied both theoretically and experimentally. The experimental work has demonstrated signal coupling efficiency up to 90% in the NP highly Er/Yb co-doped phosphate fiber.
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Inci, Hasan. "Discrete Fiber Angle And Continuous Fiber Path Optimization In Composite Structures." Master's thesis, METU, 2012. http://etd.lib.metu.edu.tr/upload/12614127/index.pdf.
Повний текст джерелаАнотація:
Fiber orientation angle stands out as one of the most effective design variables in the design optimization of composite structures. During the manufacturing of the composite structures, one can change the fiber orientation according to the specific design needs and constraints to optimize a pre-determined performance index. Fiber placement machines can place different width tows in curvilinear paths resulting in continuous change of the fiber orientation angle in a layer of the composite structure. By allowing the fibers to follow curvilinear paths in the composite structure, modification of load paths within the laminate can be obtained. Thus, more favorable stress distributions and improved laminate performance can be achieved. Such structures are called as variable stiffness composites structure. This thesis presents a fundamental study on the discrete fiber angle and continuous fiber path optimization of composite structures. In discrete fiber angle optimization, application of different analysis/optimization tools is demonstrated for optimum fiber angle optimization at the element level for both orthotropic and laminated composite structures. In the continuous fiber path optimization, which can be produced with fiber placement machines, optimized fiber paths are determined for different case studies. Continuous fiber path optimization is performed by means of an interface code that is developed. It is hard to find the global optimum for complex optimization problems with hundreds of design variables. In order to find the global optimum solution for such complex optimization problems, a gradient based optimization algorithm is not appropriate because there will be a lot of local minima for the problem and gradient based optimization algorithms may be stuck at the local minimums. Therefore, an evolutionary algorithm is a better solver for such kind of complex optimization problems. In this thesis, genetic algorithm, an evolutionary algorithm, in MATLAB Optimization Toolbox is used for the optimizer and commercial finite element program Nastran is used for the structural solver. For the continuous fiber path optimizations these two programs are integrated with the interface code that is developed. Manufacturing constraints of a typical fiber placement machine is also included in the constraint definition of continuous fiber path optimization. By coupling of Nastran finite element solver and MATLAB genetic algorithm tool, with the manufacturing constraint for the fiber placement machines, the first buckling load of a continuous fiber composite plate is increased %22 with respect to a composite plate with zero degree orientations.
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Dobson, Cedric Alan. "Numerical studies of fiber fracture in a single-fiber-composite specimen." Thesis, Georgia Institute of Technology, 1993. http://hdl.handle.net/1853/17636.
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Iqbal, Shoaib, and Zuhaib Ahmad. "Impact of degree or Polymerization of Fiber on Viscose Fiber Strength." Thesis, Högskolan i Borås, Institutionen Textilhögskolan, 2011. http://urn.kb.se/resolve?urn=urn:nbn:se:hb:diva-20861.
Повний текст джерелаАнотація:
The aim of the study was to find out the relationship between the DP and the tensile properties of different regenerated cellulose fibers. During the process to make regenerated cellulose fibers from wood, the reduction in DP of cellulose is a necessary process to enable fiber extrusion. The reduction of the DP is usually from 1000 to 350 (Coley 1953). The reduction in DP is necessary, first to make the cellulose soluble, and then further decrease in DP is required to control the viscosity of the solution to minimize the mechanical difficulties during processing faced. It is a fact that the reduction in DP is a compromise which is necessary, as reduction in DP means reduction in tensile properties of the fiber produced. The reduction in DP is optimized to make the process both processing and the final product more feasible. The relation in DP and the strength of the fibers is rather obvious i.e. higher the DP higher the tensile strength, but researchers have different views regarding the relationship. By the experiments performed by us we tried to come to a conclusion regarding the difference in opinions. Different types of regenerated cellulose fibers were collected from various sources. Both wet and dry tenacities of 19 different viscose, bamboo viscose, kupro viscose, modal and Tencel fibers were determined. The fiber linear density was also measured, but for some samples we had to take the fiber density value as provided by the manufacturer, due to the limitation of the instrument regarding the fiber length and low fiber linear density. Then out of all the samples 10 were selected (based on our and company’s interest). SEC analysis was used to determine the DP of the samples. These tests were not carried out by us but by MoRe Research. The results of both the analysis were gathered, analyzed and commented upon.Program: Master Programme in Textile Technology
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Fernandes, Henrique. "Fiber orientation analysis of carbon fiber-reinforced polymers by infrared thermography." Doctoral thesis, Université Laval, 2015. http://hdl.handle.net/20.500.11794/27294.
Повний текст джерелаАнотація:
L’utilisation de Matériaux Composites est de plus en plus courante dans plusieurs applications, notamment dans les structures aéronautiques où des pièces de forme complexe sont fort demandées. Dans ces matériaux, la disposition ou l’orientation des fibres l’une par rapport à l’autre, la concentration de celles-ci, et leur distribution sont des facteurs qui ont une influence notable sur la résistance et d’autres propriétés des composites renforcés de fibres. Ainsi, on a besoin de développer des techniques d’essai pour évaluer la teneur en fibres. Des méthodes destructrices peuvent être utilisées pour évaluer les fibres dans un échantillon composite par exemple, en évaluant une section de coupe du matériau après polissage de la surface par microscopie. Cependant, l’approche destructrice n’est pas toujours une option puisque l’échantillon est endommagé après l’inspection et probablement impropre à l’utilisation. Ainsi, les techniques de Contrôle non-destructif (CND) doivent être utilisées dans certains cas pour évaluer le contenu de la matière fibreuse. Dans cette thèse, la thermographie infrarouge, une technique de CND bien connue, est utilisé afin d’évaluer l’orientation des fibres de matériaux composites, à la surface et sous la surface de pièces plates ainsi que de pièces de forme complexes. Plus précisément, l’ellipsométrie thermique utilisant une source de point laser de chauffage (statique) et une source de chauffage en ligne produit par balayage en vol du point laser (dynamique) sont employés. L’évaluation de l’orientation de la fibre sur des pièces de forme complexe est accomplie avec succès en raison de la fusion d’un modèle en trois dimensions de la surface de l’échantillon avec les données infrarouge obtenues par l’inspection d’ellipsométrie thermique. Le matériau qui va être inspecté dans ce projet est le Carbone/Polyether-Ether-Ketone (PEEK) réalisé par disposition de flocons de fibres appelée Randomly-Oriented Unidirectional Strand (ROS).The use of Composite Materials (CM) is growing more and more every day in several applications, especially in aeronautic structures where complex shaped parts are highly demanded. The arrangement or orientation of the fibers relative to one another, the fiber concentration, and the distribution all have a significant influence on the strength and other properties of fiber reinforced composites. Thus, one needs to develop testing techniques to assess fiber content. Destructive methods can be employed to evaluate the fiber on a composite, e.g. cutting a section of the material, polishing the area and evaluating it by microscopy. However, the destructive approach is not always an option since the sample will be ‘damaged’ after the inspection and probably unfit for use. Therefore, Non-Destructive Testing and Evaluation (NDT& E) techniques must be employed in some cases to assess the material’s fiber content. In this thesis, InfraRed Thermography (IRT), a well-known NDT& E technique, is used in order to assess fiber orientation of composite materials on the surface and beneath the surface of booth flat and complex shaped parts. More specifically, Thermal Ellipsometry (TE) using a laser spot heating source (static) and a line heating source produced by a flying laser spot inspection (dynamic) are employed. Fiber orientation assessment on complex shaped parts is successfully accomplished due to the merge of a Three-Dimensional (3D) model of the part’s surface with the InfraRed (IR) data obtained by the TE inspection. The specimens that are going to be inspected in this project are Carbon/Polyether-Ether-Ketone (PEEK) plates reinforced by Randomly-Oriented Unidirectional Strand (ROS) of unidirectional slit tape.
O uso de Materiais Compósitos tem crescido mais e mais a cada dia em várias aplicações, especialmente em estruturas aeronáuticas onde peças em forma de complexos sõ extremamente procurados. O arranjo ou orientação das fibras com relação umas às outras, a concentração de fibra, e sua distribuição tem todos um grande impacto na força, rigidez e outras propriedades de materiais compósitos reforçados com fibras. Assim, se faz necessário o desenvolvimento de técnicas capazes de avaliar o conteúdo fibroso destes materiais. Métodos destrutivos podem ser empregados para avaliar as fibras em um material compósito, por exemplo cortando-se uma secção do material, polindo a área e avaliado a região com um microscópio. Entretanto, a abordagem destrutiva nõ é sempre uma opção uma vez que após o ensaio a peça ficará danificada e provavelmente imprópria para uso. Deste modo, ensaios não-destrutivos devem ser empregados em certos casos para avaliar o conteúdo fibroso do material. Nesta tese, termografia infravermelha, uma conhecida técnica de ensaios não-destrutivo, é usada para acessar a orientação das fibras de materiais compósitos na superfície e sub-superfície de amostras planas bem como de amostras com formas complexas. Mais especificamente, elipsometria térmica usando fonte de aquecimento ponto de laser (estático) e uma fonte de aquecimento em linha produzida por uma inspeção de ponto voador (dinâmico) são empregadas. Avaliação de orientação de fibra em amostras de formas complexas é realizada com sucesso graças a fusão de um modelo tridimensional da superfície da amostra e os dados infravermelhos obtidos com o ensaio de elipsometria térmica. As amostras inspecionadas durante este projeto são feitas Carbono/Polyether-Ether-Ketone (PEEK) reforçadas com Randomly-Oriented Unidirectional Strand (ROS).
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Lee, Munki. "Heat Transfer and Consolidation Modeling of Fiber Tow in Fiber Placement." Diss., Virginia Tech, 2002. http://hdl.handle.net/10919/11123.
Повний текст джерелаАнотація:
New heating techniques are required to better control heat transfer between heating tools and a composite towpreg in the automated fiber placement process. This dissertation suggests new heating techniques with liquid and rigid contact heat sources, and compares them with a widely used gas heat source for the fiber placement process.
A thin towpreg composite model needs to be developed to describe the heat transfer. Subsequently, the response of the towpreg with each heat source was compared from manufacturing speed and energy efficiency viewpoints. The most promising heat source was developed for heat transfer modeling between a moving towpreg and dynamic heat source in the automated fiber placement. Through the heat transfer model, both the temperature controllability of the towpreg and manufacturing speed could be investigated.
In addition, an accurate compaction process is needed in response to the growing demand for better composite processing. Since the errors in compaction mechanisms and robotic machinery in fiber placement have not been discussed in the literature, experimental investigation to address possible reasons for the variations in the compaction force was conducted with a compaction mechanism. A clearer understanding of the physical compaction process can lead to controllable process parameters for consistent ply compaction, such that the final parts quality can be enhanced.
Even though this dissertation investigates the thin thermoset fiber placement process, the proposed approach could be universally applicable to other composite-fabrication processes.Ph. D.
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Sabat, Philippe Jacques. "Evaluation of fiber-matrix interfacial shear strength in fiber reinforced plastics." Thesis, Virginia Polytechnic Institute and State University, 1985. http://hdl.handle.net/10919/77733.
Повний текст джерелаАнотація:
The role of the interphase in fiberglass reinforced composites was studied by a combination of theoretical analysis, mechanical tests, and several high-resolution analytical techniques. The interphase was varied in composition by using epoxy and polyester matrix polymers with and without added coupling agents, as well as four fiber surface modifications. Different coupling agents on the fibers were shown to change the fiber tensile strength markedly. Filament wound unidirectional composites were tested in short beam "shear." Corresponding samples were fabricated by embedding one to seven fibers in the center of polymer dogbone specimens that were tested in tension to determine critical fiber lengths. Those values were used in a new theoretical treatment (that combines stress gradient shear-lag theory with Weibull statistics) to evaluate "interfacial shear strengths". The fact that results did not correlate with the short beam data was examined in detail via a combination of polarized light microscopy, electron microscopy (SEM) and spectroscopy (XPS or ESCA) and mass spectroscopy (SIMS). When the single fiber specimens were unloaded, a residual birefringent zone was measured and correlated with composite properties, as well as with SIMS and SEM analysis that identified changes in the locus of interphase failure. Variations in the interphase had dramatic effects upon composite properties, but it appears ·that there may be an optimum level of fiber-matrix adhesion depending upon the properties of both fiber and matrix. Fiber-fiber interactions were elucidated by combining tensile tests on multiple fiber dogbone specimens with high-resolution analytical techniques. In general, this work exemplifies a multidisciplinary approach that promises to help understand and characterize the structure and properties of the fiber-matrix interphase, and to optimize the properties of composite materials.Master of Science
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Razvan, Ahmad. "Fiber fracture in continuous-fiber reinforced composite materials during cyclic loading." Diss., This resource online, 1992. http://scholar.lib.vt.edu/theses/available/etd-05042006-164536/.
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Haskell, Adam Benjamin. "A Durability and Utility Analysis of EFPI Fiber Optic Strain Sensors Embedded in Composite Materials for Structural Health Monitoring." Fogler Library, University of Maine, 2006. http://www.library.umaine.edu/theses/pdf/HaskellAB2006.pdf.
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Abdi, Yussuf Yusuf, and Ibrahim Zand Jalal. "FRP:s användning inom brokonstruktioner." Thesis, KTH, Byggteknik och design, 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-259362.
Повний текст джерелаАнотація:
I dagsläget är de flesta broar i Sverige tillverkade med betong eller stål. Dessa broar är många gånger förknippade med stora kostnader som ofta beror på underhåll och reparation. FRP, som står för Fiber Reinforced Polymer, är ett relativt nytt material i bärande stommar men är ett väl etablerat material i förstärkningssammanhang. I Europa och i synnerhet Nederländerna finns det flertal broar byggda i FRP. Men på grund av brist på normer och regelverk att luta sig emot sker det sällan någon form av brokonstruktion med FRP i Sverige. Detta examensarbete syftar till att undersöka befintliga normer och studera hur materialet FRP används vid förstärkning och konstruktion av broar. Vidare syftar även arbetet till att undersöka egenskaperna hos FRP som byggmaterial och jämföra det med konventionella material som stål och betong. FRP, också benämnd fiberkomposit, är ett kompositmaterial som kan sammanställas på flera olika sätt. Genom olika material som kombineras och olika tillverkningsprocesser som används kan man på så sätt ge individuell utformning till materialet för dess användning. Fördelarna med FRP är många, men i allmänhet har det god styrka, god beständighet samtidigt som det har en låg vikt. Detta resulterar i att inom brokonstruktion så ger det strukturen en minskad egenvikt, vilket i sin tur underlättar en mängd olika saker. Detta arbete visar på att FRP-material har fördelaktiga egenskaper och kan i vissa situationer vara mer gynnsamt att använda än stål eller betong. Dock som tidigare påpekat saknas det specifika Eurokoder för detta material. Däremot är vi säkra på att introduktionen av en ny Eurokod samt med uppmuntran från myndigheter kommer användningen av FRP inom brokonstruktion utan tvekan öka.At present, most bridges in Sweden are made with concrete or steel. These bridges are often associated with high costs, which often depend on maintenance and repair. FRP, which stands for Fiber Reinforced Polymer, is a relatively new material in load-bearing structures but is a well- established material in the context of reinforcement. In Europe and in particular the Netherlands, there are several bridges built in FRP. But due to a lack of norms and regulations to lean against, there is rarely any kind of FRP bridge construction in Sweden. The aim of this thesis is to examine existing norms and study how the material FRP is used in the reinforcement and construction of bridges. Furthermore, this thesis also aims to investigate the properties of FRP as building material and compare it with conventional materials such as steel and concrete. FRP, also called fiber-composite, is a composite material that can be assembled in several different ways. Through various materials that are combined and different manufacturing processes used, one can thus provide individual designs for the material. The benefits of FRP are many, but generally it has good strength, good durability while having a low weight. This results in that within bridge construction, it gives the structure a reduced self-weight, which in turn facilitates a variety of things. This thesis shows that FRP materials have advantageous properties and in some situations can be more favorable to use than steel or concrete. However, as previously pointed out, there are no specific Eurocodes for this material. However we are sure that the introduction of a new Eurocode and encouragement from authorities will undoubtedly increase the use of FRP in bridge construction.
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Zu, Seung-Don. "The effect of irregular fiber distribution and error in assumed transverse fiber CTE on thermally induced fiber/matrix interfacial stresses." Texas A&M University, 2005. http://hdl.handle.net/1969.1/3800.
Повний текст джерелаАнотація:
Thermally induced interfacial stress states between fiber and matrix at cryogenic
temperature were studied using three-dimensional finite element based micromechanics.
Mismatch of the coefficient of thermal expansion between fiber and matrix, and
mismatch of coefficient of thermal expansion between plies with different fiber
orientation were considered. In order to approximate irregular fiber distributions and to
model irregular fiber arrangements, various types of unit cells, which can represent nonuniformity,
were constructed and from the results the worst case of fiber distributions
that can have serious stress states were suggested. Since it is difficult to measure the
fiber transverse coefficient of thermal expansion at the micro scale, there is an
uncertainty problem for stress analysis. In order to investigate the effect of error in
assumed fiber transverse coefficient of thermal expansion on thermally induced
interfacial stresses, systematic studies were carried out. In this paper, the effect of
measurement errors on the local stress states will be studied. Also, in order to determine
fiber transverse CTE values from lamina properties, a back calculation method is used
for various composite systems.
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Gao, Song. "Fabrication of Tapered Dual-core As2Se3-PMMA Fiber and Its Applications." Thesis, Université d'Ottawa / University of Ottawa, 2019. http://hdl.handle.net/10393/38697.
Повний текст джерелаАнотація:
Fiber optical temperature and strain sensors have been extensively investigated for applications in the civil structures to ensure safety and prevent disasters in advance. Most of the demonstrated fiber sensors are based on the silica fibers to form an interferometer by measuring the spectrum wavelength shift caused by the change of the refractive index and fiber length, and the sensitivities, defined as the rate of wavelength shift with respect to temperature or strain, are limited by the small values of thermal-expansion coefficient and thermo-optic effect of the silica materials. To improve the sensitivity, we designed the dual-core As2Se3-PMMA fiber with the PMMA cladding diameter 56.5 times larger than that of the As2Se3 cores, which brings out many interesting sensing applications.
Nonlinear devices have a variety of practical applications including parametric amplification, all-optical switching, super-continuum generation, and sensing applications. Tapered chalcogenide-polymer fiber structures composed of an As2Se3 core and a polymethyl methacrylate (PMMA) cladding are a promising platform for nonlinear applications because the As2Se3 core provides high nonlinearity over the near- and mid-infrared spectral ranges for compact nonlinear devices with low power consumption and the PMMA cladding provides high mechanical strength for easy handling. Advanced As2Se3-PMMA fiber structures such as dual-core fibers that support guided propagation of an even mode and an odd mode will open the way for a variety of novel devices in the near- and mid-IR wavelength range.
In my work I utilized two As2Se3 fibers and a polymethyl methacrylate (PMMA) tube for the fabrication of dual-core As2Se3-PMMA tapers and demonstration of the sensing applications and nonlinear optical effects.
The thesis mainly consists of three parts: the fabrication process, the sensing applications, and the nonlinear applications in the tapered dual-core As2Se3-PMMA fiber.
In the first part, the fabrication process of the tapered dual-core As2Se3-PMMA fiber is introduced. The dual-core As2Se3-PMMA fibers are fabricated using a rod-in-tube method. The images of the setups and fibers in process are listed.
In the second part, a theoretical model for temperature and strain measurement and four sensing applications are introduced. Firstly, we demonstrate an approach for high-sensitivity simultaneous temperature and strain measurement in a dual-core As2Se3-PMMA taper with As2Se3 core diameter of 0.55 μm. High measurement sensitivities are observed for both principal polarization axes of the tapered dual-core As2Se3-PMMA fiber with temperature sensitivities of -115 pm/ºC for axis-1, -35.5 pm/ºC for axis-2, and strain sensitivities of -4.21 pm/με for axis-1 and -3.16 pm/με for axis-2. Secondly, the thermal forces in a dual-core As2Se3-PMMA taper are investigated. A temperature-insensitive strain sensor is proposed and demonstrated based on the thermal forces. Finally, two approaches for temperature and strain sensitivity enhancement are investigated. The first approach is by reducing the value of the variation of the difference between phases of the even and odd modes with respect to wavelength (∂ϕd(λ)/∂λ) and increasing thermal-forces in a dual-core As2Se3-PMMA taper with As2Se3 core diameter of 2.5 μm. The value of ∂ϕd(λ)/∂λ decreases with the As2Se3 core diameter and thermal-forces on the As2Se3 cores are enhanced in the fibers with large PMMA cladding, which work together to enhance the measurement sensitivity. The second approach is based on effective group-velocity matching between the even and odd modes of a dual-core As2Se3-PMMA taper on which an antisymmetric long-period grating is inscribed. The variation of the difference between phases of the even and odd modes with respect to wavelength tends to 0 (∂ϕd(λ)/∂λ→0) near the resonance wavelength of the grating due to the effective group-velocity matching between the two modes, and consequently, thermally-induced change of the difference between phases of the two modes ϕd (λ) leads to a large wavelength shift indicating enhancement of the temperature measurement sensitivity.
In the third part, I study the nonlinear optical effects in the hybrid fibers. Firstly, I demonstrate modulation instability within the normal-dispersion regime in a dual-core As2Se3-PMMA fiber. Then I review the work about the forward stimulated Brillouin scattering and its sensing applications. The radial and torsional-radial guided acoustic modes of silica fibers and tapered dual-core As2Se3-PMMA fibers are investigated experimentally and the preliminary results are presented.
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Li, Qin, and 李沁. "All-fiber laser sources for fiber optical parametric amplifiers in 1 um." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2011. http://hub.hku.hk/bib/B47175898.
Повний текст джерелаАнотація:
Fiber optical parametric amplifier (FOPA) is undoubtedly one of the most thriving research topics about optical amplifiers during the past decades. The high optical gain, arbitrary gain regions and wavelength conversion with large frequency shift make FOPA outstanding in diverse application areas like the high-speed all-optical communication, wavelength-tunable laser sources and optical imaging systems. Special fiber gain medium and proper pump source are two essential elements in an FOPA setup. As the research interest on FOPAs has recently gradually extended from the conventional 1.5-_m region to the shorter wavelength band at 1 μm, photonic crystal fibers (PCFs) act as the gain media by virtue of their customized dispersion curve and nonlinearity in this band. And the 1-mum laser sources incorporating ytterbium-doped fiber (YDF) as the gain medium have been investigated as well. We prefer all-fiber laser as the pump source not only because of its high output quality but also its compatibility with other fiber systems like FOPA. However, compared with 1.5-_m range, fiber lasers in 1-_m wavelength window have not been fully developed. Most of the laser sources reported in this wavelength range are not all-fiber base. For those few all-fiber reports, the tuning range of the pulsing wavelength is not wide enough, which might limit the performance of the FOPA. In this thesis, we have investigated tunable fiber lasers aiming at becoming the promising pump sources for 1-μm FOPAs. All-fiber lasers with different techniques and operation schemes based on the YDF have been discussed.
Tunable ytterbium (Yb) fiber lasers with short pulsed output are important for pulsed-pumped FOPAs in 1 _m. Passive and active mode locking techniques are both commonly employed in short pulse generation. Passive mode-locking laser cavity usually works at the fundamental frequency of the cavity (?MHz) and has the potential to generate ultra-short pulse (? fs) due to its fast recovery time. On the other hand, active mode locking is more agile in terms of the repetition rate, which is synchronized with the external electrical signal. It can be as high as tens of GHz, which is useful for high-speed optical communication, and also can be as low as tens of MHz, which can benefit applications that require high peak power. For an all-fiber mode-locked laser based on YDF, the self-starting of the passive mode locking in 1 _m is more difficult than in 1.5 μm due to the large value of the normal material dispersion in optical fibers in this shorter wavelength range. In this thesis, we have focused on the active mode-locking cavity. Two schemes of actively mode-locked fiber lasers have be demonstrated. One is with a high repetition rate of about 10-GHz at around 1030 nm. The 30-nm tuning range is beneficial to the development of the wavelength-division multiplexing (WDM) technology in the newly developed 1-μm communication band. And on the basis of this scheme, another actively mode-locked fiber laser with a wider tuning range (almost 50 nm) have been achieved by optimizing the length of the YDF inside the cavity. Considering the applications like fiber sensing or spectroscopy where high peak power is more essential and also due to the limitation of our 980-nm pump power, the repetition rate has been lowered down to around 300 MHz in the second scheme.
Tunable continuous-wave (CW) fiber lasers in 1 _m have also been discussed. For an all-fiber ring laser cavity, a stable CW output without mode-hopping can be achieved by selecting out single frequency. Various experimental configurations have been proposed for single-longitudinal-mode (SLM) oscillation. We have combined the multiple-ring cavity (MRC) and the saturable absorber in the same fiber laser cavity to facilitate the SLM generation in 1 _m. The tunable CW SLM fiber laser has the potential to build a sweeping source with instantaneous narrow linewidth for optical coherence tomography (OCT) in this range. It can also be utilized as the pump source for CW FOPAs, which is more immune from the walk-off effect between the pulsed pump and the signal, as long as the stimulated Brillouin scattering (SBS) has been suppressed properly.published_or_final_version
Electrical and Electronic Engineering
Master
Master of Philosophy
43
Lin, Ming Ching, and 林銘清. "Application of Optical Fiber Amplifier For Fiber Sensor and Fiber Ring Laser." Thesis, 2005. http://ndltd.ncl.edu.tw/handle/81156727069054242645.
Повний текст джерелаАнотація:
碩士國立交通大學
光電工程系所
93
In the first part of the thesis, we propose and investigate experimentally a gain-clamped S-band erbium-doped fiber amplifier (EDFA), a stable and single-longitudinal-mode oscillation of an S-band EDF ring laser. The behaviors and performances of the S-band amplifier have also been discussed in the text. Single-longitudinal-mode laser output can be realized by employing a Fabry-Perot filter and a saturable-absorber-based autotracking filter composed of an unpumped EDF and an optical reflector. The performance of output power is larger then 10 dBm and a side-mode suppression ratio (SMSR) is larger then 49.1 dB from 1488.7 to 1505.7 nm. In the second part of the thesis, we propose the S-band fiber sensor technique and a multiplexed fiber sensing system based on semiconductor optical amplifier (SOA). In the experiment of S-band fiber sensor system, the proposed laser lases at each wavelength of the FBG accordingly by tuning the Fabry-Perot filter. In the experiment of multiplexed sensing system, all lasing wavelengths based on the inhomogeneous broadening effect of SOA are accordingly the FBG central wavelength. Using properly coupling ratio, we can obtain the clearly optical signals.
44
Lin, Shih-Chuan, and 林世川. "Fiber Sensors Based On Superstructure Fiber Gratings." Thesis, 2009. http://ndltd.ncl.edu.tw/handle/01102210091779371642.
Повний текст джерелаАнотація:
碩士逢甲大學
電機工程所
97
The content of this thesis is to investigate the fiber sensor based on the superstructure fiber gratings (SFGs) with two different fiber-etching processes. The SFG can be used to simultaneously measure two different physical parameters for simplifying the design of a sensor system. This is due to an SFG including the optical characteristics both of an FBG and an LPG. By means of different fabricating processes, we can make the corrugate-type and air-gap of superstructure fiber gratings. The corrugate-type has high sensitivity for measuring the applied strain. The air-gap type has better performance for sensing the surrounding index variation. Both of them can simultaneously measure two-parameters for enhancing the sensing accuracy. In this thesis, we also study about the side-polished long-period grating coating with a poly-aniline thin film in photonic crystal fibers for measuring different concentrations of ammonia gas. The sensing mechanism is based on the index change of the poly-aniline thin-film as it is interacted with the ammonia gas. It is new sensing design with high sensitivity and accuracy for developing a wide range of sensing applications.
45
Yen-ChengFang and 方彥程. "All-fiber self Q-switched fiber laser." Thesis, 2010. http://ndltd.ncl.edu.tw/handle/60141711939221725072.
Повний текст джерелаАнотація:
博士國立成功大學
微電子工程研究所碩博士班
98
The purpose of this dissertation is to propose and demonstrate self Q-switched all-fiber erbium laser systems, using three novel techniques local intensity-enhancement in a ring resonator, mode-field mismatching in a standing-wave resonator, and lifetime-shortening with an auxiliary laser source. A saturable absorber Q-switched all-fiber ring laser is first realized. By locating a saturable-absorber fiber in the intensity-enhanced section of a ring resonator, an all-fiber laser is passively Q-switched. The design has been numerically and experimentally demonstrated using Er3+-doped fiber at the emission wavelength of 1550 nm. A single-mode Q-switched pulse with pulse energy of 0.37 μJ and pulse duration of 218 ns was achieved with 980-nm pump power near 7 mW. In addition, a self Q-switching method using mismatched mode field areas and a saturable-amplifier pump switch are successfully demonstrated for sequentially generating Q-switched pulses. This is a fully passive, all-fiber Q-switched laser system. Pumped with a continuous-wave (CW) 980-nm laser diode (LD), sequential pulses with a pulse energy of 8–6 μJ and a pulse duration of 80-320 ns, corresponding to a pulse repetition rate of 0.25-1 kHz, were obtained. A peak pulse power of near 100 W was achieved. Furthermore, a technology of increasing the recovering rate of the saturable absorber using an auxiliary laser source is demonstrated. Through the use of an auxiliary 1570-nm laser that shortened the relaxation lifetime of erbium, sequentially Q-switched pulses with pulses energies between 4 and 6 μJ and pulse widths of 40 ns were achieved. A peak power of 165 W was obtained.
46
Hung, Kuan-luen, and 洪寬綸. "Study on Fiber Laser, Fiber Sensing and Monitoring Technologies Based on Fiber Bragg Gratings." Thesis, 2006. http://ndltd.ncl.edu.tw/handle/8cef3c.
Повний текст джерелаАнотація:
碩士國立臺灣科技大學
電子工程系
94
In this thesis, we fabricate fiber Bragg gratings (FBGs) and propose several novel configurations in three applications regarding fiber laser, fiber sensing and in-service monitoring. Firstly, introduction of FBG fabrication process includes light exposure, annealing, thermal compensation, and package process. The home-made FBG has reflectivity over 99 % and 3 dB bandwidth of 0.25 nm. We also demonstrate the feasibility of covering the C-band window by using several tunable FBGs. Moreover, we propose four types of cavity fiber laser and two improved frames. Under the condition of 100 mW pump laser and 3 m Erbium doped fiber, optical circulator ring fiber laser has better side mode suppression ratio 66.78 dB while fiber mirror fiber laser and optical circulator linear fiber laser has better transfer efficiency 19.1 % and 17.62 %, respectively. Next using FBGs as sensor heads, we propose sensing system about temperature, strain, and vibration whose sensibility gets 33.1 pm/℃, 0.16 nm/0.01 mm and 15 pm/degree, respectively. Furthermore, replacing traditional broadband light source with fiber laser could raise sensing power from -21.88 dBm to 3.1 dBm and peak-to-noise ratio from 8.89 dB to 65.31 dB and decrease 3 dB line width from 0.31 nm to 0.06 nm. Based on this sensing scheme, the probability of inaccurate judgment would be diminished. Finally, in order to upgrade quality of service in the optical internet we propose hybrid in-service monitor configuration by integrating FBGs with optical time domain reflector. Such configuration could precisely diagnose where the possible broken point happens towards any type of path demand.
47
Zhang, Hui. "Lumped fiber Raman amplifiers with highly nonlinear fiber." Thesis, 2005. http://spectrum.library.concordia.ca/8713/1/MR14289.pdf.
Повний текст джерелаАнотація:
Fiber Raman amplifiers (FRAs) can provide broadband and low-noise-figure amplification, and the gain can be achieved at any wavelength. It has been proved that FRA is a useful technique to extend the span lengths and capacity of fiber-optic transmission systems. In particular, lumped fiber Raman amplifiers (LRAs), based on dispersion compensating fibers, have been considered in long-haul WDM transmission systems. However, noise can limit the performance of LRAs having a gain of more than 15 dB. Noise degrades the optical signal-to-noise ratio (OSNR) resulting in receiver sensitivity penalty and thus the amplifier gain is limited to some extent for a single LRA. Highly nonlinear fiber (HNLF) is a fiber with high nonlinearity to generate Raman gain efficiently and can be used as a gain medium for lumped Raman amplifiers. In this thesis, we will investigate Raman gain and noise characteristics of LRAs using HNLFs as a gain medium. It is shown that both the signal and the amplified spontaneous emission induced multiple-path interferences are suppressed in LRAs with HNLF, thus for the same Raman gain a better noise performance can be achieved independently of co-, counter- and bi- directional pumping methods, compared to LRAs with DCF gain medium. Moreover, the effect of Rayleigh scattering coefficient on LRA's noise performance improvement is also investigated. To achieve an accurate modeling, a theoretical model, which includes effects of multiple-path interference (MPI), anti-Stokes, and Rayleigh scattering, is used, and a new Raman gain coefficient scaling method is also employed in this modeling.
48
Sethna, Rustam Homi. "Fiber deflocculation." 1985. http://catalog.hathitrust.org/api/volumes/oclc/12727744.html.
Повний текст джерелаАнотація:
Thesis (M.S.)--University of Wisconsin--Madison, 1985.Typescript. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references (leaves 111-112).
49
Chang, Chih-Hao, and 張志豪. "Fabrication of Fiber Gratings and Their Application on DBR Fiber Lasers and Fiber Grating Resonators." Thesis, 1996. http://ndltd.ncl.edu.tw/handle/16369247606944664910.
Повний текст джерелаАнотація:
碩士國立交通大學
光電工程研究所
84
In this thesis we study the theory, fabrication, and applicationsof fiber gratings. We have successfully fabricated high-reflectivityfiber gratings using the phase mask approach and used them to buildEr DBR fiber lasers. Such lasers are very compact, stable, and have a very narrow linewidth. They are suitable light sources for fibercommunication systems and fiber sensors. We have also successfully fabricated phase-shifted fiber grating resonators and measured theirresonant characteristics. Such a kind of resonators can be used fornarrow-band filtering or to build DBR fiber lasers.
50
Jhong, Guo-sing, and 鍾國興. "Investigation of Fiber Laser Based on Fiber Bragg Grating." Thesis, 2007. http://ndltd.ncl.edu.tw/handle/76mevc.
Повний текст джерелаАнотація:
碩士國立臺灣科技大學
電子工程系
95
This thesis is consist of four parts: the first part is the amplification theorem of erbium doped fiber amplifier (EDFA), the second part is the analysis of EDF fiber laser, then we introduce high-efficiency C-Band tunable fiber laser including the forward/backward circulator-based fiber laser, and forward/backward broadband mirror-based fiber laser schemes. In the four structures, 50 mW pumping power and 4 m EDF are adopted. For the data measurement, the lasing power are 6.12, 7.24, 9.27, and 9.98 mW, side mode suppression ratio (SMSR) are 53.65, 53.46, 54.9, and 54.47 dB, transfer efficiency are 14.01, 16.42, 20.46, and 21.93 %, 3 dB bandwidth are 0.06, 0.06, 0.051, and 0.05 nm respectively. The third part is to introduce a conventional resonator fiber laser and an improved structure. As 20 mW pumping power and 4 m EDF are adopted in these two configurations, the lasing power are 2.1, 2.78 mW, SMSR are 61.2 and 5.89 dB, transfer efficiency are 13.92 and 18.29 %, 3dB bandwidth are both 0.06 nm. Finally, we introduce the L-Band linear-cavity fiber laser structure, including the forward/backward circulator-based fiber laser and forward/backward broadband mirror-based fiber laser structures. In these four structures, 50 mW pumping power and 15 m EDF are adopted. For these four configurations, the lasing power are 3.86, 4.23, 4.63, and 4.72mW, SMSR are 50.08, 51.02, 51.26, and 51.33 dB, transfer efficiency are 10.36, 11.24, 12.2, and 12.36 %, 3 dB bandwidth are 0.052, 0.051, 0.05, and 0.05 nm, respectively. These kinds of fiber lasers we proposed here are all with merit of efficiency improvement. They could find many applications in fiber sensing system to increase the dynamic range, or transmitter technology to reduce the required pumping power.