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Dissertations / Theses on the topic 'Holey fibres'

Author: Grafiati

Published: 4 June 2021

Last updated: 7 February 2022

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1

Belardi, Walter. "Holey optical fibres for high nonlinearity devices." Thesis, University of Southampton, 2003. https://eprints.soton.ac.uk/42430/.

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This thesis describes the development of a novel type of optical fibre, namely holey optical fibre (HF), for its specific incorporation in optical devices based on fibre nonlinearity. The development of the fabrication technique to produce such a fibre is discussed, and the fibres produced are characterized and used in device applications, proving the advantages of HF technology in the implementation of highly nonlinear optical devices, as well as showing its limitations. The initial fabrication problems that hindered the production of HFs with a high nonlinearity are identified and several st

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2

Baggett, Joanne Claire. "Bending losses in large mode area holey fibres." Thesis, University of Southampton, 2004. https://eprints.soton.ac.uk/65504/.

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The aims of the study presented here are to develop methods of accurately predicting bend loss in arbitrary index fibres, to use these techniques to explore the potential offered by holey fibres in the large-mode-area, single-mode regime, and to place their performance in context against conventional step-index fibres. In the study presented here, numerical and experimental techniques have been developed that are capable of accurately evaluating the bending losses, the fundamental mode area and the modedness of holey fibres. Note that these techniques are also applicable to conventional solid

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3

Yusoff, Zulfadzli. "Applications of highly nonlinear holey fibres in optical communications." Thesis, University of Southampton, 2004. https://eprints.soton.ac.uk/15465/.

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Holey fibre (HF) is a new type of fibre that uses rings of air holes around a solid core toconfine light. A small core HF with a high air fill fraction can have effective nonlinearitycoefficient of around 10-100 times greater than conventional fibre. Apart from that, its dispersion value is also highly tailorable simply by changing the structural dimensions. These two characteristics make HFs attractive as a nonlinear medium. This thesis reports the first demonstration of various nonlinear fibre devices based on HFs. Thediscrete Raman amplifier is an attractive option to extend optical transmi

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4

Issa, Nader. "Modes and propagation in microstructured optical fibres." University of Sydney. Physics and Optical Fibre Technology Centre, 2005. http://hdl.handle.net/2123/613.

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Microstructured optical fibres (MOFs), also commonly called photonic crystal fibres or holey fibres, describe a type of optical fibre in which continuous channels of (typically) air run their entire length. These `holes' serve to both confine electromagnetic waves within the core of the fibre and to tailor its transmission properties. In order to understand and quantify both of these functions, a new computational algorithm was developed and implemented. It solves for the eigenvalues of Maxwell's wave equations in the two-dimensional waveguide cross-section, with radiating boundary conditions

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5

Kuhlmey, Boris T. "Theoretical and Numerical Investigation of the Physics of Microstructured Optical Fibres." University of Sydney and Universite Aix-Marseille III. School of Physics, 2003. http://hdl.handle.net/2123/560.

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We describe the theory and implementation of a multipole method for calculating the modes of microstructured optical fibers (MOFs). We develop tools for exploiting results obtained through the multipole method, including a discrete Bloch transform. Using the multipole method, we study in detail the physical nature of solid core MOF modes, and establish a distinction between localized defect modes and extended modes. Defect modes, including the fundamental mode, can undergo a localization transition we identify with the mode�s cutoff. We study numerically and theoretically the cutoff of t

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6

Kim, Jeong I. "Analysis and Applications of Microstructure and Holey Optical Fibers." Diss., Virginia Tech, 2003. http://hdl.handle.net/10919/29089.

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Microstructure and photonic crystal fibers with periodic as well as random refractive-index distributions are investigated. Two cases corresponding to fibers with one-dimensional (1D) radial index distributions and two-dimensional (2D) transverse index distributions are considered. For 1D geometries with an arbitrary number of cladding layers, exact analytical solutions of guided modes are obtained using a matrix approach. In this part, for random index distributions, the average transmission properties are calculated and the influence of glass/air ratio on these properties is assessed. Import

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7

Chen, Yong. "Hole control in photonic crystal fibres." Thesis, University of Bath, 2014. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.616649.

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Photonic crystal fibres (PCFs) are special fibres with air holes which run along the whole fibre length. These holes not only determine the fibres' unique properties, but also provide a new degree of freedom for fibre modications. In this thesis, we focus on hole control in PCFs from two perspectives: during their fabrication and after they have been made. We found for the first time that the direct information of viscosity was not necessary for description of the fibre drawing process. This conclusion matched our experimental results without recourse to any adjustable fitting parameters. By p

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8

Kominsky, Daniel. "Development of Random Hole Optical Fiber and Crucible Technique Optical Fibers." Diss., Virginia Tech, 2005. http://hdl.handle.net/10919/28949.

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This dissertation reports the development of two new categories of optical fibers. These are the Random Hole Optical Fiber (RHOF) and the Crucible Technique Hybrid Fiber (CTF). The RHOF is a new class of microstructure fiber which possesses air holes which vary in diameter and location along the length of the fiber. Unlike all prior microstructure fibers, these RHOF do not have continuous air holes which extend throughout the fiber. The CTF is a method for incorporating glasses with vastly differing thermal properties into a single optical fiber. Each of these two classes of fiber brings

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9

Alfeeli, Bassam. "Ionizing Radiation Resistance of Random Hole Optical Fiber for Nuclear Instrumentation and Control Applications." Thesis, Virginia Tech, 2009. http://hdl.handle.net/10919/32661.

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Random hole optical fibers (RHOF) offer advantages over other types of microstructured optical fibers (MOFs). They are inexpensive and easy-to-make when compared to the high cost of ordered hole MOFs. They also have unique characteristics since they contain open and closed holes. The open holes contain ambient air under normal conditions and the closed holes contain residual gases from the fabrication process at certain pressure. The objective of this research work was to investigate the radiation resistance of Random Hole Optical Fibers (RHOF) for possible use as both sensing element and data

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10

Leong, Julie Yeen Yeen. "Fabrication and applications of lead-silicate glass holey fibre for 1-1.5 microns : nonlinearity and dispersion trade offs." Thesis, University of Southampton, 2007. https://eprints.soton.ac.uk/50197/.

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This thesis describes the development of novel microstructured optical fibres (MOFs), namely holey optical fibres (HFs), based on a commercial highly nonlinear non-silica glass: By taking the advantages of the zero dispersion of the HFs at 1 μm and 1.55 μm, the SC studies are carried out using these HFs (WW HFs and SEST HFs). Both of the fibre SC studies combined experimental and numerical results, and the simulations and experiments were in qualitative agreement. We observed a spectrum spanning over 1000nm by using just ~98 pJ energy pulses in a 60cm piece of the WW HF. This demonstrated the

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11

Zucchini, Sara. "Primordial black holes in string inflation." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2018. http://amslaurea.unibo.it/17097/.

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In this thesis we consider the production of primordial black holes (PBH) in the context of single field inflation with the aim of describing a significant fraction of dark matter. In the models we consider, the inflaton is a string modulus and its potential is typical of type IIB fibre inflation. The potential presents a plateau at CMB scales and an extremely flat region on smaller scales. The background is analysed by solving the Friedmann's and the Klein-Gordon equations for the system. Perturbations are introduced through the usual Mukhanov-Sasaki equation for the gauge invariant curvatur

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12

Mohamad, Masita. "Multistage fibre length fractionation of softwood chemical pulp using a pressure screen equipped with smooth-holed screen cylinder." Thesis, University of British Columbia, 2012. http://hdl.handle.net/2429/42993.

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Often, fibre fractionation produce a higher value long-fibred reject stream and a lower value short-fibred accept stream simultaneously. Fractionation is only practical when a mill can make use of all obtained fractions. This study sought to demonstrate the potential of upgrading the reject fraction through multiple stages of fractionation while creating a new market for the remaining low value pulp for an efficient use of the raw materials. In this study, an NBSK pulp was fractionated on the basis of fibre length using a small industrial pressure screen Beloit MR-8 in multiple consecutive sta

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13

Pedrelli, Luca. "Inflation and primordial black holes in matter domination." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2018. http://amslaurea.unibo.it/17095/.

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In this thesis we will study a new interpretation of dark matter in terms of Primordial Black Holes (PBHs), i.e. black holes that are believed to form when large density perturbations, produced during the inflationary epoch, reenter the horizon and collapse because of their own gravitational force. Black holes produced in this way are referred to as "Primordial" since their production mechanism has a primordial origin during inflation. These large density fluctuations are produced if the inflationary potential possesses enough tuning freedom to feature a slow-roll plateau followed by a near in

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14

Ellis, Frederick Paa Kwesi. "Fabrication of Random Hole Optical Fiber Preforms by Silica Sol-Gel Processing." Thesis, Virginia Tech, 2004. http://hdl.handle.net/10919/31489.

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Conventional fibers are comprised of a solid glass core and solid glass cladding often protected by a thin polymer sheath. The finely tuned difference in refractive indices, for step index-fibers, is achieved by doping the core with germanium or elements with similar effects. Holey fibers (including photonic crystal fibers) comprise of a pure silica core, and a pure but porous silica cladding of air holes [1]. This provides a huge difference in the refractive indices on the cladding and core without doping. This translates into radiation resistant fibers with very low losses and very robus

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15

Jason, Johan. "Fibre-Optic Displacement and Temperature Sensing Using Coupling Based Intensity Modulation and Polarisation Modulation Techniques." Doctoral thesis, Mittuniversitetet, Avdelningen för elektronikkonstruktion, 2013. http://urn.kb.se/resolve?urn=urn:nbn:se:miun:diva-18964.

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Optical fibre sensors are employed in the measurements of a number of different physical properties or for event detection in safety and security systems. In those environments which suffer from electromagnetic disturbance, in harsh environments where electronics cannot survive and in applications in favour of distributed detection, fibre-optic sensors have found natural areas of use. In some cases they have replaced conventional electronic sensors due to better performance and long-term reliability, but in others they have had less success mainly due to the higher costs which are often involv

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16

Asquith, Nathan Lee. "Extended D-E knob-hole interaction sites in fibrin polymerisation, clot formation and clot mechanics." Thesis, University of Leeds, 2019. http://etheses.whiterose.ac.uk/22624/.

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Background: Abnormal thrombus formation and occlusion of a vessel is one of the main events of cardiovascular disease. A main component of the thrombus is the protein fibrin, which is formed by proteolytic cleavage of its precursor fibrinogen by the serine protease thrombin. The cleavage of fibrinogen to fibrin releases fibrinopeptides from the E-region of the molecule which leads to the exposure of peptide sequences termed knobs A and B. The knobs A and B on one fibrin molecule are able to spontaneously interact to binding pockets (termed holes a and holes b) via hydrogen bonds forming half s

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17

Balatbat, Richard Vincent S. "An Investigation of Damage Arrestment Devices Application with Fastener/Hole Interaction." DigitalCommons@CalPoly, 2010. https://digitalcommons.calpoly.edu/theses/402.

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This thesis presents a parametric study on the effects of how damage arrestment devices application interacts with a fastener in a composite sandwich panel. The primary objective of the damage arrestment device was to prevent the failure of the composite face sheet, such as crack propagation, around the hole/fastener joint. The damage arrestment devices are made of composite strips that are inserted under the face sheet to increase the overall structural strength of the panel and to prevent the propagation of failure along the hole. This was supposed to be a quicker and stronger alternative to

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18

Treasurer, Paul James. "Characterization and Analysis of Damage Progression in Non-Traditional Composite Laminates With Circular Holes." Thesis, Georgia Institute of Technology, 2006. http://hdl.handle.net/1853/13989.

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Carbon Fiber / Epoxy Laminates are increasingly being used in the primary structure of aircraft. To make effective use these materials, it is necessary to consider the ability of a laminate to resist damage, as well as material strength and stiffness. A possible means for improving damage tolerance is the use of non-traditional composite laminates, in which the longitudinal 0 plies are replaced with 5 or 10 plies. The main objectives of this collaborative Georgia Tech / Boeing research was the characterization of these non-traditional laminates, and the determination of appropriate lamina-leve

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19

Mollenhauer, David Hilton. "Interlaminar Deformation at a Hole in Laminated Composites: A Detailed Experimental Investigation Using Moire Interferometry." Diss., Virginia Tech, 1997. http://hdl.handle.net/10919/30680.

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The deformation on cylindrical surfaces of holes in tensile loaded laminated composite specimens was measured using new moire interferometry techniques. These new techniques were developed and evaluated using a 7075-T6 aluminum control specimen. Grating replication techniques were developed for replicating high quality diffraction gratings onto the cylindrical surfaces of holes. Replicas of the cylindrical specimen gratings (undeformed and deformed) were fabricated onto circular steel sectors. Narrow angular regions of these sector gratings were directly evaluated in a moire interferometer. Th

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20

Ferreira, João Carlos de Melo. "Fiber amplifiers in transparent and dynamic optical networks." Doctoral thesis, Universidade de Aveiro, 2015. http://hdl.handle.net/10773/14090.

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Doutoramento em Engenharia Eletrotécnica<br>In this thesis a study of optical fiber amplifiers in the context of transparent and dynamic optical networks is performed. We propose and validate a simplified model to estimate the gain profile and amplified spontaneous emission (ASE) noise of broadband counterpumped Raman fiber amplifiers (RFAs). The proposed model requires very low computational resources and it is suitable to be used in network planning tools. Based on the proposed model, we also present an algorithm to design flat gain counter-pumped RFAs for the extended C-band with lo

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21

Cheng, Ming-Yi. "An experimental investigation into tool wear in micro-drilling of aluminium, aluminium/copper metal alloys and carbon fibre reinforced composites." Thesis, Brunel University, 2017. http://bura.brunel.ac.uk/handle/2438/14613.

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Limitation of conventional machining equipment has become a growing concern over the past two decades due to the demands for greater machining accuracy in today’s manufacturing. The development of micro-machining has therefore attracted significant attention; it signifies the advancement of national economy as well as the level of accuracy manufacturing industry could achieve. While the connection between tool lifespan, cost of machining and throughput is well established, the factor of tool lifespan appears to have more significance since the miniaturization of tool could lead to further perf

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22

Leidorf, Michal. "Srovnání svarů vytvořených CO2 laserem a vláknovým laserem." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2011. http://www.nusl.cz/ntk/nusl-229442.

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The project compares the technology of welding of CO2 laser and fiber laser in terms of engineering study, the welds will be made by same welding conditions on two materials (S235JRG2 a X5CrNi 18-10), by using different protective gases (Helium and Argon). In the terms of literal background research both the technologies and questions of laser welding are described. The geometry of welds is carried out in the experimental part. The final results of the experiment are concluded at the end of the diploma thesis.

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23

Myrén, Niklas. "Poled fiber devices." Doctoral thesis, KTH, Physics, 2005. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-262.

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<p>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.</p><p>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 inte

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24

Robertson, Scott James. "Hawking radiation in dispersive media." Thesis, University of St Andrews, 2011. http://hdl.handle.net/10023/1900.

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Hawking radiation, despite its presence in theoretical physics for over thirty years, remains elusive and undetected. It also suffers, in its original context of gravitational black holes, from conceptual difficulties. Of particular note is the trans-Planckian problem, which is concerned with the apparent origin of the radiation in absurdly high frequencies. In order to gain better theoretical understanding and, it is hoped, experimental verification of Hawking radiation, much study is being devoted to systems which model the spacetime geometry of black holes, and which, by analogy, are also t

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25

Jacquet, Maxime J. "Negative frequency at the horizon : scattering of light at a refractive index front." Thesis, University of St Andrews, 2017. http://hdl.handle.net/10023/11780.

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This thesis considers the problem of calculating and observing the mixing of modes of positive and negative frequency in inhomogeneous, dispersive media. Scattering of vacuum modes of the electromagnetic field at a moving interface in the refractive index of a dielectric medium is discussed. Kinematics arguments are used to demonstrate that this interface may, in a regime of linear dispersion, act as the analogue of the event horizon of a black hole to modes of the field. Furthermore, a study of the dispersion of the dielectric shows that five distinct configurations of modes of the inhomogene

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26

Machinet, Guillaume. "Développement de sources lasers femtosecondes ytterbium à très haute cadence et applications." Thesis, Bordeaux 1, 2013. http://www.theses.fr/2013BOR14999/document.

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Ce travail de thèse est consacré au développement de sources lasers femtosecondes à haute cadence, de forte puissancemoyenne (>10 W) avec des énergies supérieures à 100 μJ. Ce type de sources est primordial pour le développementd’applications industrielles variées (micro-usinage athermique, chirurgie oculaire, …) ainsi qu’en recherchefondamentale pour l’étude de l’interaction laser matière.Après un chapitre d’introduction sur l’état de l’art des chaînes lasers de forte puissance moyenne à base de matériauxdopés ytterbium, la réalisation d’une chaîne laser de forte puissance moyenne compacte

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27

Renault, Michel. "Tolerance a l'endommagement de composites carbone-resine et stratifies t300-914." Paris, ENMP, 1988. http://www.theses.fr/1988ENMP0109.

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Etude experimentale (essais de fatigue, essais de traction, de compression) sur des eprouvettes entaillees ou non, trouees ou non de stratifies resine epoxyde/carbone. Analyse mathematique avec des calculs par elements finis

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28

Santos, Rafael Alexandre Mota dos. "Effect of the Distance Between Impact Point and Hole Position and Non-Perpendicular Holes on the Impact Strength of Composite Laminates." Master's thesis, 2016. http://hdl.handle.net/10400.6/7703.

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The effect of the distance between impact point and hole position and the angle of the hole with the vertical axis was studied. In order to understand this effect, flexural tests were also performed to evaluate the bending strength of CFRP. In terms of distance of the hole, a maximum reduction of 29.7% on the bending load for a distance of 0 mm was found. This reduction was 22.3% on the impact load. In terms of angle of the hole, a maximum load reduction of 15.6% on the bending strength was found and for the impact load this value was found to be 7% for 20º. The fatigue resistance was also stu

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29

Okai, Smart K. "Determination of residual stresses in a carbon-fibre reinforced polymer using the incremental hole-drilling technique." Thesis, 2017. http://hdl.handle.net/10539/22997.

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A Research Report submitted to the Faculty of Engineering and the Built Environment, University of the Witwatersrand, in fulfillment of the requirements for the degree of Master of Science in Engineering(Mechanical Engineering 30 January 2017<br>An extensive variety of experimental techniques exist to determining residual stresses, but few of these techniques is suitable, however, for finding the residual stresses that exist in orthotropic or anisotropic layered materials, such as carbon-fibre reinforced polymers (CFRP). Among these techniques, particularly among the relaxation techniques, th

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30

Σωτηριάδης, Γεώργιος. "Μη καταστροφικός έλεγχος για τη μελέτη της συσσώρευσης βλάβης σε σύνθετα υλικά ενισχυμένα με ίνες γυαλιού, με και χωρίς την παρουσία νανοσωληνίσκων άνθρακα". Thesis, 2009. http://nemertes.lis.upatras.gr/jspui/handle/10889/2468.

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Τα σύνθετα υλικά οργανικής μήτρας ενισχυμένα με ίνες γυαλιού είναι μια κατηγορία υλικών που έχει υψηλό τεχνολογικό ενδιαφέρον τις τελευταίες δεκαετίες με πληθώρα εφαρμογών στην αεροπορική και διαστημική βιομηχανία, στην αυτοκινητοβιομηχανία, στη formula 1, στα σπορ και γενικότερα όπου οι απαιτήσεις για υψηλή επίδοση των υλικών συνδυάζονται με την απαίτηση για χαμηλό βάρος. Στην κατεύθυνση αυτή έχει συντελέσει και το διαρκώς μειούμενο κόστος παραγωγής των υλικών αυτών μέσω της χρήσης καινοτόμων τεχνικών. Η συνεχής εξέλιξη των υλικών αυτών οδηγεί σε βελτιωμένα υλικά ενισχυτικής και μητρικής φάση

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31

Siegmund, Bernward. "Untersuchung der Geschosswirkung in der sehr frühen Phase unter besonderer Berücksichtigung der Hochgeschwindigkeitsmunition." Doctoral thesis, 2006. http://hdl.handle.net/11858/00-1735-0000-0006-B33E-8.

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