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1
Yu, Fei. "Hollow core negative curvature fibres." Thesis, University of Bath, 2013. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.648936.
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Hollow core fibre (HCF) is a type of novel optical fibre which has lower refractive index in the hollow core than in the cladding. Total internal reflection (TIR) cannot explain the confinement of light to the core of a HCF. According to the confinement mechanism, the HCFs can be generally divided into hollow core photonic bandgap fibres and hollow core leaky mode fibres depending on their optical properties of the cladding structure. Hollow core negative curvature fibre (HC-NCF) is a kind of hollow core leaky mode fibre, which is defined by the negative curvature of the core boundary. This thesis presents my study of HC-NCFs over the last two years. My research has focused on developing low loss silica HC-NCFs and exploring the attenuation limit of HC-NCFs. Fifty different HC-NCFs were fabricated, which covered the spectral range from 800 nm to 4.5 μm. Minimum attenuations of 24.4 dB/km and 85 dB/km were measured at around 2400 nm wavelength and 4000 nm respectively, which are the best achieved in HCFs at these wavelengths to the best of my knowledge. The limits of HC-NCF attenuation were revealed by analysing the data from HC-NCFs scaled for minimum attenuation in different spectral regions. Other properties of HC-NCFs, including bending loss and dispersion, were also studied experimentally. By using white light interferometery, a low group velocity dispersion (GVD) was found in HC-NCFs, which agrees well with simulations. The bending loss of HC-NCFs was preliminarily studied by measuring the transmission spectra under different bending conditions. Significant bending loss was found when the bending radius was less than 15 cm. Numerical simulations were performed using COMSOL software to study the properties of HC-NCFs. In the simulations, it was found that the capillary thickness is the most important factor determining the attenuation of HC-NCFs. These results were used to explain the experimental results. This thesis is comprised of seven chapters. Chapter 1 and 2 supply background material that helps to understand the light guidance mechanism of HC-NCFs. My original work is presented in Chapter 3, 4, 5, and 6. Chapter 7 includes a summary and suggestions for future work.
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Forsberg, Frans. "Gas Analysis using Hollow-Core Optical Fibers." Thesis, KTH, Tillämpad fysik, 2018. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-231924.
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Liu, Fangzhou. "Dynamic analysis of hollow core concrete floors." Licentiate thesis, KTH, Bro- och stålbyggnad, 2018. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-224778.
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Chu, Yiwen. "Loading rubidium atoms into a hollow core fiber." Thesis, Massachusetts Institute of Technology, 2007. http://hdl.handle.net/1721.1/40904.
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Thesis (S.B.)--Massachusetts Institute of Technology, Dept. of Physics, 2007.Includes bibliographical references (p. 71-73).
We demonstrate a procedure for cooling, trapping, and transferring rubidium atoms into a hollow core photonic band gap fiber. The atoms are first collected in a magneto-optical trap (MOT) and then cooled using polarization gradient cooling. Magnetic traps are then used to confine and transfer the atoms toward the face of the fiber. An optical dipole trap formed using laser light propagating through the fiber guide the atoms and confine them away from the fiber walls. We hope to use this system to achieve large optical depths with possible applications to quantum computing.
by Yiwen Chu.
S.B.
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Yin, Dongliang. "Integrated hollow core waveguide devices for optical sensing applications /." Diss., Digital Dissertations Database. Restricted to UC campuses, 2006. http://uclibs.org/PID/11984.
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Paine, Kevin Andrew. "Steel fibre reinforced concrete for prestressed hollow core slabs." Thesis, University of Nottingham, 1998. http://eprints.nottingham.ac.uk/11095/.
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An investigation of prestressed concrete containing steel fibres as secondary reinforcement to improve performance in shear, flexure and bond is reported. Emphasis is placed on the use of steel fibres in prestresssed extruded hollow core slabs, since these common precast elements have intrinsic difficulty in incorporating traditional secondary reinforcement due to their unique shape and manufacturing method. Two separate studies were carried out. The first study involved laboratory investigations into the bond between fibre reinforced concrete (FRC) and the prestressing strand, and the shear behaviour of laboratory-cast prestressed fibre reinforced concrete (PFRC) beams. The second part involved the factory production of fibre reinforced hollow core slabs in co-operation with a local manufacturer. The fibre reinforced hollow core slabs were subjected to conventional full-width shear tests, concentrated load shear tests, and to transverse flexure. For all laboratory cast elements, cubes, cylinders and prisms were cast to investigate compressive, tensile and flexural properties, respectively. Two types of steel fibre were investigated: hooked-end steel fibres at fibre volume fractions (Vf) of 0.5%, 1.0% and 1.5%; and amorphous metal fibres at Vf‘s of 0.28% and 0.56%. The trial production of fibre reinforced hollow core slabs necessitated the investigation of the effect of steel fibres on the extrusion manufacturing process. It was shown that fibre reinforced hollow core slabs could be adequately compacted with only slight increases in mixing water. Fibres were found to distribute randomly throughout the cross-section. However, the rotation of the augers affected the orientation of fibres, with fibres tending to align vertically in the web. It was shown that the addition of steel fibres to prestressed concrete has a negative effect on the bond between matrix and tendon, leading to longer transfer lengths. The effect of the increase in transfer length was to reduce cracking shear strengths by 4%. Shear tests showed that the incorporation of steel fibres could increase shear strength by as much as 45% for Vf = 1.5%. This increase in shear strength, known as the fibre contribution, was shown to be due to fibres bridging across the crack and an increased compressive resistance due to fibres arresting the propagation of cracks into the compressive zone. A semi-empirical equation for shear strength of PFRC elements is developed. It is given in two forms, one compatible with the present equations for prestressed concrete given in BS 8110 and Eurocode 2, and a second form compatible with that advocated for fibres in reinforced concrete. The equation makes use of equivalent flexural strength which is recognised as the most useful material property for design of FRC. The equation was found to give good correlation with the shear strength of single web beams cast both in the laboratory and under factory conditions. However, a overall strength reduction factor is required for full-width hollow core slabs to account for uneven load distribution and inconsistent web widths. This is consistent with tests on plain hollow core slabs found in the literature.
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Abokhamis, Mousavi Seyed Mohammad. "Exploring optical nonlinearity in gas-filled hollow core fibre." Thesis, University of Southampton, 2018. https://eprints.soton.ac.uk/428037/.
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The growing need for novel light sources in variety applications increases the demand for laser sources operating in many different range of spectrum. Despite the success in development of mid-infrared (mid-IR) lasers, which are essential in many applications such as: environmental science, bio-science and physics, there are still lack of reliable lasers in this range with existing fibre laser technology compatibility. Meanwhile the nonlinearity in gases has been explored extensively from the very beginning of nonlinear optics, however, new developments in pulsed lasers and fibre design provide opportunities for more applications. The introduction of Hollow Core Photonic Crystal Fibres (HC-PCF) has revolutionised the area of nonlinearity in gaseous media by offering a single-mode confined light beam for very long distances. In this thesis, the focus was on mid-IR pulse generation by Raman frequency conversion in a gas-filled HC-PCF. Due to reliable performance and compatibility of fibre lasers with HC-PCFs, and towards fully fiberized source, an erbium-doped fibre laser (1.55 μm) has been selected as the pump for this project. In order to reach as far as possible into the mid-IR region, hydrogen has been selected as the filling gas of fibre, due to its large frequency shift and high Raman gain. The large frequency shift and mid-IR operating range required a new fibre design with a broadband transmission window and relatively low loss in mid-IR. After studying conventional HC-PCF structures, the recently proposed Nested Anti-resonant Nodeless Fibre (NANF) has been selected as the most suitable option for the purpose of this thesis [71]. Two NANFs, made of silica and tellurite, have been designed and optimized through the use of the developed Finite Element Method (FEM) toolbox in this thesis for operating wavelengths at pump (1.55 μm) and 1st Stokes (4.35 μm). A novel design has also been introduced in NANFs which shows polarization maintaining feature as good as the latest state-of-the-art HC-PBGF type [77]. The proposed design also shows polarizing capability in addition to its polarization maintaining by presenting a large loss ratio (~30 dB) between different polarizations of propagating light through it. The pulse propagation throughout the hydrogen-filled NANFs has been investigated by modelling the Raman response of hydrogen and numerically solving the Generalized Nonlinear Schrödinger Equation (GNLSE). Simulations show promising results for frequency conversion towards mid-IR and the possibility of Raman lasers in this region by considering different gas and using the readily available air in HC fibres. Furthermore, in this work, the nonlinear dynamics of atmospheric air-filled HC fibres have been studied, ranging from Raman down conversion process to a high spectral power density supercontinuum spanning from 850 to 1600 nm. A semi-quantum model for air has been adopted and integrated into the GNLSE, which surpasses the limitations of simple model. Using the adopted model, the experimental results have been reproduced without any extra computational cost. A rigorous study has been performed on nonlinear dynamics of pulse propagation in air-filled HC fibres and the origin of many nonlinear phenomenon are identified.
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Love, Adrian. "Hollow core optical fibre based gas discharge laser systems." Thesis, University of Bath, 2018. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.760983.
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The humble electrically pumped gas laser has undergone little development in its fifty year life span due to the lack of an effective method to confine light within a hollow waveguide of any appreciable length in which an electrical discharge could be contained. New technologies in the field of anti-resonant guiding hollow core fibres present an opportunity to re-invent the gas laser. A recent breakthrough in the field demonstrated that DC pumped glow discharges of a helium and xenon gas mixture could not only be sustained in such a fibre, but also exhibited signs of gain on a number of mid-IR neutral xenon laser lines. The research presented in this thesis is a continuation of that project. The system was redesigned to incorporate two mirrors so that a cavity could be constructed. The previously hinted at gain on the 3:51 μm xenon line was confirmed through a series of CW measurements of the cavity, as was a polarisation of the laser due to a polarisation dependent output coupler. Further observation of the discharges revealed that they were of a pulsed nature, and that the mid-IR laser light was present in the discharge afterglow. A response to the cavity mirrors was observed in this afterglow pulse on the 3:11 and 3:36 μm xenon lines in addition to the 3:51 μm line previously seen. Through fast detection a modulation of the output power due to cavity mode beating effects was detected. The high gain and narrow bandwidth of the xenon laser lines resulted in a frequency pulling effect, and the mode separation in the 'hot' laser cavity was measured to be lower than in the 'cold' cavity. It was observed through pressure optimisation experiments in helium-xenon that higher output powers could be achieved by using lower partial pressures of xenon. This was exploited with neon-xenon mixtures, where the lower ionisation potential of neon allowed a lower pressure of xenon. Discharges were also achieved in helium-neon and argon gas mixtures.
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Sandoghchi, Seyed Reza. "Characterisation of imperfections in hollow core photonic bandgap fibres." Thesis, University of Southampton, 2016. https://eprints.soton.ac.uk/419065/.
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Over the past decades, the performance of standard single-mode fibre (SSMF) has improved to the point that limited scope now exists for significant further reductions in loss and nonlinearity, which determine the fibre’s transmission capacity. Given the current 40% per annum growth in data traffic, and the fact that state-of-the-art data transmission experiments are operating close to the fundamental information-carrying limit of SSMF, there is strong interest in developing radically new fibres capable of much higher data carrying capacity. Recently, a potentially disruptive new type of fibre, the hollow-core (HC) photonic bandgap fibre (PBGF), has emerged as a credible candidate. It guides light predominantly (i.e. ~99%) in air, providing a unique set of optical properties such as ultralow nonlinearity, ultimate low signal latency, and the potential for lower loss compared to SSMF. However, to enable the application of HC-PBGFs for data transmission, the fabrication of long lengths of uniform, low-loss HC-PBGFs is essential, which had not been possible until recently. Despite empirical observations of high loss section along HCPBGFs and of more frequent fibre breaks than in conventional fibres were known, very little was known about the root cause of these issues at the start of this PhD project. The investigation of the problems preventing the fabrication of long length of uniform, defect free HC-PBGF is the topic of this thesis. I developed and/or applied a suite of characterisation methods, such as IR side-scatter imaging, X-ray tomographic analysis and optical side scattering radiometry, aimed at identifying defects and imperfections that arise in HC-PBGFs. Through these techniques, I studied the morphology and longitudinal evolution (e.g. formation, stabilisation and decay) of such defects, the first systematic study of this kind for HC-PBGFs. Furthermore I could backtrack their origin to well defined stages in the fabrication (e.g. preforms and canes). My observations suggest that all or at least most defects arise due to contamination or stacking errors, which are unintentionally introduced when the HC-PBGF preforms are assembled from arrays of glass capillaries. Ultimately, the methods I have developed and the findings described in this PhD Thesis helped develop ways to greatly reduce (and hopefully, in future, completely eliminate) these defects, which resulted in several breakthroughs including the achievement of the current record length of low loss HC-PBGF, i.e., a 11km long fibre with a uniform 5.2dB/km loss and more than 200nm transmission bandwidth, a factor of 10 longer length than what had been reported before the start of this project.
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Cordier, Martin. "Photon-pair generation in hollow-core photonic-crystal fiber." Thesis, Université Paris-Saclay (ComUE), 2019. http://www.theses.fr/2019SACLT024/document.
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Les sources de paires de photons sont un composant essentiel des technologies émergentes en information quantique. De nombreux travaux ont permis des avancées importantes utilisant des processus non linéaires d'ordre 2 dans les cristaux et les guides d'ondes, et d'ordre 3 dans les fibres. Les limitations viennent dans le premier cas, des pertes et en particulier des pertes de couplage avec les fibres optiques et dans le second cas, du bruit dû à l'effet Raman dont le spectre est très large dans les fibres de silice. Ce projet propose une nouvelle architecture basée sur des fibres à cristal photonique à coeur creux (FCPCC) que l'on peut remplir de liquide ou de gaz non linéaire. Cette configuration permet la génération paramétrique de paires de photons corrélés par mélange à quatre ondes sans l'inconvénient de la diffusion Raman. Cette technologie offre une large gamme de paramètres à explorer en s'appuyant sur les propriétés physiques et linéaires contrôlables des FCPCC et la possibilité de remplissage de ces fibres avec des fluides aux propriétés non-linéaires variées. En effet, par une conception judicieuse de la FCPCC et un choix approprié du liquide ou du gaz, il est possible de (i) contrôler la dispersion et la transmission pour générer des photons corrélés sur une large gamme spectrale avec la condition d'accord de phase la plus favorable, (ii) d'ajuster la taille de coeur de la fibre et/ou sa forme pour augmenter sa non-linéarité ou son efficacité de couplage avec d'autres fibres et (iii) de s'affranchir totalement de l'effet Raman si on utilise par exemple un gaz monoatomique, ou d'obtenir des raies Raman fines, aisément discriminables des raies paramétriques dans le cas d'un liquidePhoton pair sources are an essential component of the emerging quantum information technology. Despite ingenious proposals being explored in the recent years based on either second order nonlinear processes in crystals and waveguides or on third order processes in fibers, limitations remain, due to losses and specifically coupling losses in the former case and due to Raman generation in silica, giving rise to a broad spectrum noise in the latter. These limitations have been challenging to lift because of the limited alternative nonlinear materials that fulfil the conditions for the generation of bright and high fidelity photon pairs in integrable photonic structures. In the present project, we develop a new and versatile type of photonic architecture for quantum information applications that offers access to a variety of nonlinear optical materials that are micro-structured in optical fiber forms to generate photon pairs, without the drawback of Raman scattering and with a large design parameter-space. Indeed, with a careful design of the HCPCF along with the appropriate choice of fluid, one can (i) control the dispersion and the transmission to generate photons with the most favourable phase-matching condition over a large spectral range, (ii) adjust the fibre core size and/or shape to enhance nonlinearity or the coupling efficiency with other fibres, (iii) totally suppress the Raman effect in monoatomic gases for instance or have only narrow and separated Raman lines that can thus be easily separated from the useful parametric lines in liquids
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Urich, Artur. "Silica hollow core fibres for mid-infrared medical applications." Thesis, Heriot-Watt University, 2013. http://hdl.handle.net/10399/2946.
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In this thesis two types of silica hollow core microstructured fibres - the Negative Curvature Fibre and the Photonic Bandgap Fibre - are presented as a novel solution for the flexible delivery of Er:YAG laser radiation. The Negative Curvature Fibre and Photonic Bandgap Fibre had attenuations of 0.06 dB/m and 1.1 dB/m at 2.94 μm wavelength, respectively. This is an important wavelength regime for medical applications, specifically surgery, due to the existence of a strong absorption peak for water around 3 μm. The guidance of high energy pulses of the order of 195 mJ and 14.4 mJ respectively is demonstrated. These energies are sufficient to ablate soft and hard biological tissue. As verification, porcine bone was ablated in air and submerged in water to simulate practical application of a surgical device. The presented fibres are compared to alternative state-of-the-art solid and hollow core fibres, in respect of the fabrication, attenuation, pulse energy delivery capability, bend sensitivity and the output beam profile. The fabrication and characterisation of a novel sapphire endtip is also presented, which seals the hollow cores of the fibres from contamination and therefore increases the usability significantly. The endtip was shown to be mechanically robust, provide a hermetic seal and able to survive practical tissue ablation in air and water. These encapsulated fibres provide a new fully flexible delivery system for high energy Er:YAG laser radiation and hence will open up the possibility of new minimally invasive surgical procedures.
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Xu, Mengrong. "Advances in hollow core fibres and application to mid-infrared fibre gas lasers." Thesis, University of Bath, 2018. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.760959.
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Anti-resonant hollow core fibre is a new kind of optical fibre waveguide in which light is trapped in a hollow core surrounded by the capillary formed microstructured cladding. This fibre exhibits high damage threshold, low dispersion and ultra-low nonlinearity with relatively low loss of a few tens of dB/km. Its intrinsic feature of multimode delivery limits the applications with high requirements of single mode transmission. In my thesis, I demonstrate how the design of hollow core fibre can be improved with single mode guidance. S2 imaging measurement was used to analyse the mode content of the solid core fibres. In my research, I established S2 measurement to measure the mode contents in hollow core fibres for the first time. Two hollow core fibres with 8 capillaries and 7 capillaries in their claddings were fabricated in same fashion and showed differences in low attenuations. By comparing the mode contents in both of the fibres via S2 imaging measurement, 7-capillary HCF was demonstrated to give better performance on single mode guidance. Among the applications of the HCF, the property of delivering high power in HCF makes the gas filled HCF laser possible. In my research, a continuous-wave mid-infrared acetylene filled hollow core laser was built with a slope efficiency of 33% and an output power of over 1 watt at the wavelength region of 3.1~3.2 μm. The pump source is an Erbium-doped fibre amplified tunable laser diode which works at C-band wavelength. The fibre without the gain medium has two transmission bands with low attenuation of 0.037 dB/m and 0.063 dB/m at pumping and lasing wavelengths respectively. This laser system works in either cavity-based configuration or single pass ASE configuration. The latter configuration shows a better performance in high output power and high slope efficiency. The optimized laser system was studied experimentally with the proper fibre length and gas pressure. This laser system could be extended to be filled with other molecules to longer wavelengths and has potential for high power output.
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Lam, Dennis. "Composite steel beams using precast concrete hollow core floor slabs." Thesis, University of Nottingham, 1998. http://eprints.nottingham.ac.uk/11350/.
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The main aim of this thesis is to develop an insight into the behaviour of composite floors that utilise steel beams acting in combination with precast concrete hollow core floor slabs and to produce design recommendations for use by industry for this type of construction. Full scale bending tests of proprietary precast prestressed concrete hollow core unit floor slabs attached through 19mm diameter headed shear studs to steel Universal Beams (UB) have been carried out to determine the increased strength and stiffness when composite action is considered. The results show the bending strength of the composite beam to be twice that of the bare steel beam, and its flexural stiffness to be more than trebled. In addition to the beam tests, isolated push-off tests and horizontal eccentric compression tests were used to study the horizontal interface shear resistance of the headed studs and the strength of the slab, respectively. Maximum resistances were compared with the predictions of the Eurcode EC4, and a reduction formula for the precast effect derived. In addition to the experimental investigations, finite element (FE) studies were also conducted using the FE package ABAQUS to extend the scope of the experimental work. Results show a 2-dimensional plane stress analysis to be sufficiently accurate, providing the correct material input data obtained from isolated push-off and compression tests are used. The FE model for the composite beam was designed and validated using the full scale beam tests. A parametric study, involving 45 analyses, was carried out to cover the full range of UB sizes and floor depths used in practice. From the finite element work, design charts are formulated which may be used to simplify the design rules. Given the results of this work, a full interaction composite beam design may be carried out using the proposed design equations. The results show that precast slabs may be used compositely with steel UB's in order to increase both flexural strength and stiffness at virtually no extra cost, except for the headed shear studs. The failure mode is ductile, and may be controlled by the correct use of small quantities of transverse reinforcement and insitu infill concrete.
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Welch, Matthew G. "Compressing and propagating solitons in hollow core photonic crystal fibre." Thesis, University of Bath, 2010. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.520840.
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The development of photonic crystal fibre from conventional optical fibre follows a trend in the development of materials, to create composites and structured materials on smaller and smaller scales. In fact the great success of photonic crystal fibre is largely due to the ability to structure it on scales comparable to the wavelength of light. It is this micron size structure that allows the creation of an (out of plane) optical bandgap in silica and allows hollow core fibre to guide light in an air core freeing the guided mode from the properties of bulk silica. This thesis focuses on the propagation and compression of high peak power optical solitons in hollow core fibre. As the Kerr nonlinear response of air is approximately a thousand times less than that of silica, the air core of hollow core fibre can support much higher peak powers than conventional optical fibre without the manifestation of nonlinear effects, making it ideal for the delivery of high peak power laser pulses. Coupled with this, hollow core fibre has a large region of anomalous dispersion in its transmission window allowing optical pulses to be transmitted as temporal solitons freeing them from the effects of dispersion. The author started his Ph.D. in 2006, three years after the first demonstration of soliton propagation in hollow core fibre and as the first demonstrations of soliton compression in hollow core fibre were being undertaken. Work by the author to build upon these early demonstrations is presented in this thesis in the following manner: Chapters 1, 2 and 3 are theory chapters. Chapter 1 explains the background waveguide theory and theory of nonlinear optics that is used throughout the thesis. Chapter 2 details the properties of photonic crystal fibres focusing on hollow core fibre. Chapter 3 details recent papers relevant to the propagation and compression of solitons in hollow core fibre. Chapters 4, 5 and 6 are experimental chapters reporting work undertaken by the author. Chapter 4 focuses on modifying the nonlinearity of hollow core fibre and measuring the dispersion of hollow core fibre accurately. Chapter 5 focuses on the compression of chirped and unchirped picosecond pulses in dispersion decreasing hollow core fibre tapers. Chapter 6 reports the compression in hollow core fibre of femtosecond pulses centred at 540nm wavelength through soliton effect compression.
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Porchert, Alexander, Dirk Schneider, Jürgen Haase, Mika Lindén, and Rustem Valiullin. "Diffusion and molecular exchange in hollow core-shell silica nanocapsules." Diffusion fundamentals 24 (2015) 39, S. 1, 2015. https://ul.qucosa.de/id/qucosa%3A14556.
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Amsanpally, Abhilash. "Linear properties of inhibited coupling hollow-core photonic crystal fibers." Thesis, Limoges, 2017. http://www.theses.fr/2017LIMO0028/document.
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Cette thèse a porté sur les principes de guidage, les propriétés linéaires et les outils de conception autour des fibres à cristal photonique à coeur creux (HC-PCF) à couplage inhibé (IC). Le guidage IC a été démontré comme une manifestation photonique de Q-BiC (état quasi lié dans un continuum) en étudiant des profils asymétriques et dépendants en polarisation dit Fano présentant une bande passante spectrale de 30 GHz. En utilisant le concept de IC, nous reportons la caractérisation linéaire de fibres IC HC-PCF supérieures à l’état de l’art. Par une optimisation de la forme du coeur, une fibre Kagome IC HC-PCF a démontré des pertes très faibles de 8,5 dB/km à 1030 nm associées à une bande passante à 3 dB de 225 nm. Une autre conception avec des entretoises de silice amincies à 300 nm a permis d’atteindre des pertes de 30 dB/km à 780 nm avec une bande de transmission fondamentale record décalée à 670 nm et capable de couvrir toutes les gammes spectrales du Ti:Sa, Yb et Er. Nous avons également travaillé sur la conception et la fabrication de IC HC-PCF présentant une gaine dont la structure est un réseau unique de tubes fins isolés. Une de ces fibres a permis de démontrer une transmission jusqu'à 220 nm avec des pertes records de 7,7 dB/km à ~ 750 nm, tandis qu’une seconde réalisation s’est traduit par une bande fondamentale de plus d’une octave allant de 600 à 1200 nm avec des pertes de 10-20 dB/km. Finalement, cette dernière fibre a été étudiée plus en détail pour déterminer les sources à l’origine des pertes due à la rugosité de surface présente à l’interface du contour du coeurThis thesis reported on guiding principles, linear properties and conceptual design tools of inhibited coupling (IC) guiding hollow-core photonic crystal fibers (HC-PCF). IC guidance was proved as photonic manifestation of Q-BiC (quasi bound-state-in-a-continuum) by investigating asymmetric and polarization dependent Fano profiles with bandwidth of 30 GHz in high resolution transmission spectra. By using IC design concept, we reported on linear characterization of state-of-the-art IC HC-PCFs. Based on core shaping optimization, a Kagome IC HC-PCF demonstrated ultra-low loss down to 8.5 km/km at 1030 nm associated with a 225 nm wide 3-dB bandwidth. Another Kagome design with thinner silica struts of 300 nm exhibited lowest loss of 30 dB/km at 780 nm along with record level fundamental bandwidth spreading down to 670 nm and able to cover the entire Ti:Sa, Yb and Er laser spectral ranges. We also reported on design and fabrication of single-ring tubular lattice IC HC-PCFs. One of these fibers demonstrated transmission down to 220 nm with a record transmission loss of 7.7 dB/km at ~750 nm, while the second one exhibited ultra-broad fundamental band with loss range of 10-20 dB/km over one octave spanning from 600 to 1200 nm. Finally, the second tubular fiber was further investigated for fundamental loss sources due to surface roughness around its core-contour
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Porchert, Alexander, Dirk Schneider, Jürgen Haase, Mika Lindén, and Rustem Valiullin. "Diffusion and molecular exchange in hollow core-shell silica nanocapsules." Universitätsbibliothek Leipzig, 2016. http://nbn-resolving.de/urn:nbn:de:bsz:15-qucosa-198514.
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Sam-Brew, Solace Araba. "The development of hollow core composite panels for value added applications." Thesis, University of British Columbia, 2010. http://hdl.handle.net/2429/28008.
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An ongoing shortage of suitable woody waste materials due to the many recent saw-mill closures in Canada has been a major concern for particleboard manufacturers. The existing particleboard plants are currently competing with other industries for the scarce fiber resources available and facing significant competition from the cheap lower grade substitutes being imported from China. This thesis presents a solution through the development of hollow core sandwich panels for modular furniture components that serve the same function as solid slabs of particleboard but with reduced amounts of raw material inputs (wood and resin).
Through a series of preliminary experiments, prototype honeycomb sandwich panels were fabricated with a variety of face and core materials. The characteristic effects of different types of Kraft paper honeycomb materials, its cell size, orientation and cell wall height as well as the influence of different wood-based face materials on the sandwich strength and stiffness properties were established.
The results indicate that by combining thicker (6 mm) face sheet materials with Kraft paper honeycomb with cell size less than 16 mm, cell wall height 38 mm and oriented with the core ribbon direction perpendicular to the long axis of the panel, a sandwich panel with significant strength properties can be produced. The findings also imply that the performance of the honeycomb sandwich panels can further be improved through the application of edge rail enforcements and edge band application. The outcome of this study has the potential of reducing the total weight of finished products for the furniture manufacturers and provides avenues for product differentiation.
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Arnal, Pablo Maximiliano. "The synthesis of monodisperse colloidal core @shell spheres and hollow particles." [S.l.] : [s.n.], 2006. http://deposit.ddb.de/cgi-bin/dokserv?idn=981080596.
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Amezcua-Correa, Rodrigo. "Development of hollow-core photonic bandgap fibres free of surface modes." Thesis, University of Southampton, 2009. https://eprints.soton.ac.uk/70915/.
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Conventional optical fibres can only guide light in a high refractive index core by total internal reflection. By using total internal reflections it is not possible to guide light in an air core. Light guidance in air is of great interest for various technological and scientific applications and has only recently been possible with the advent of photonic band gap fibres. However, the transmission performance of silica/air hollow-core photonic bandgap fibres has until now been affected by the existence of surface modes. These surface modes couple with the air-guided mode in specific spectral ranges inside the bandgap simultaneously increasing the attenuation and dispersion of the air-guided mode and reducing the useable bandwidth of the fibre. Therefore, for many applications it is important to eliminate surface modes or at least reduce their impact on the air mode. The fabrication of the first hollow-core photonic bandgap fibre with no surface modes is presented in this thesis. The fibre has state-of-the-art attenuation over the full spectral width of the bandgap. As a result of the elimination of surface modes the fibre presents increased bandwidth, reduced dispersion and dispersion slope compared to previous hollow-core photonic bandgap fibers. These advances have been possible due to the development of a modified fabrication method which makes the production of low-loss hollow-core fibers both simpler and 5 to 6 times quicker than previously. This development makes hollow-core fibres with improved performance more readily available than ever before
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Wu, Chunbai 1980. "Raman optical frequency comb generation in hydrogen-filled hollow-core fiber." Thesis, University of Oregon, 2010. http://hdl.handle.net/1794/11052.
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xiv, 138 p. : ill. (some col.)In this dissertation, we demonstrate the generation of optical Raman frequency combs by a single laser pump pulse traveling in hydrogen-filled hollow-core optical fibers. This comb generation process is a cascaded stimulated Raman scattering effect, where higher-order sidebands are produced by lower orders scattered from hydrogen molecules. We observe more than 4 vibrational and 20 rotational Raman sidebands in the comb. They span more than three octaves in optical wavelength, largely thanks to the broadband transmission property of the fiber. We found that there are phase correlations between the generated Raman comb sidebands (spectral lines), although their phases are fluctuating from one pump pulse to another due to the inherit spontaneous initiation of Raman scattering. In the experiment, we generated two Raman combs independently from two fibers and simultaneously observed the single-shot interferences between Stokes and anti-Stokes components from the two fibers. The experimental results clearly showed the strong phase anti-correlation between first-order side bands. We also developed a quantum theory to describe this Raman comb generation process, and it predicts and explains the phase correlations we observe. The phase correlation that we found in optical Raman combs may allow us to synthesize single-cycle optical pulse trains, creating attosecond pulses. However, the vacuum fluctuation in stimulated Raman scattering will result in the fluctuation of carrier envelope phase of the pulse trains. We propose that we can stabilize the comb by simultaneously injecting an auxiliary optical beam, mutually coherent with the main Raman pump laser pulse, which is resonant with the third anti-Stokes field.
Committee in Charge: Dr. Steven van Enk, Chair; Dr. Michael G. Raymer; Dr. Daniel A. Steck; Dr. David M. Strom; Dr. Andrew H. Marcus
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Murad, Ali. "Behaviour of long span composite beams with precast hollow-core slabs." Thesis, University of Leeds, 2007. http://etheses.whiterose.ac.uk/309/.
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The use of precast hollow-core concrete slabs with Fabsec steel beams in composite construction has had little research conducted in this area. The main purpose of the research is to develop an understanding into the behaviour of this form of construction and to demonstrate the advantages of using Fabsec beams with precast hollow-core concrete slabs. To achieve this, five full scale bending tests were carried out supplemented by horizontal push tests. In addition to the experimental work described, an analytical study is conducted and design recommendations are made. The main issues were the compression behaviour of the hollow-core slabs and the transfer of the horizontal shear forces between the steel beam and the concrete slab. The aim of the research is to investigate the performance of composite beams with the position of the neutral axis in the concrete and also establish the effective width. By varying the beam size, span of beam, shear connection and slab depth in five full-scale experiments, the behaviour of the composite beam will be established.
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Oliveira, Francisca Elenice Rodrigues de. "Síntese e estudo da atividade eletrocatalítica de nanopartículas com estruturas do tipo Core-Shell e Hollow para a redução de O2." Universidade de São Paulo, 2012. http://www.teses.usp.br/teses/disponiveis/75/75134/tde-17042012-170205/.
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A reação de redução de oxigênio (RRO) foi estudada em eletrocatalisadores com estruturas do tipo core-shell formadas por monocamadas de Pt depositadas sobre nanopartículas a base de Au e Pd, e estruturas hollow formadas de Pt. As nanopartículas core-shell foram sintetizadas por deposição em regime de subtensão utilizando-se substratos de Au e Pd. As estruturas hollow foram preparadas a partir de nanopartículas core-shell de Pt sobre Ni ou Co, seguido por ciclagem eletroquímica em eletrólito ácido. Os eletrocatalisadores foram caracterizados utilizando-se as técnicas de Energia Dispersiva, Difração e Espectroscopia de Absorção de Raios X e Microscopia Eletrônica de Transmissão. Os testes eletroquímicos foram feitos voltametria cíclica e curvas de polarização em eletrodo rotatório. Os catalisadores do tipo core-shell mostraram uma alta atividade para a RRO, o que foi associado a mudanças nas propriedades eletrônicas e geométricas da Pt, causadas pela presença dos átomos de Au e Pd, que conduzem a uma menor força de adsorção Pt-O. Neste caso, temos um melhor balanço de reatividade para as tendências opostas de quebra e formação de ligações nos intermediários reacionais adsorvidos na superficie do eletrocatalisador. As nanopartículas de Pt hollow apresentaram maior atividade que o electrocalisador de Pt/C. Isto foi atribuído aos fenômenos de contração da rede cristalina e abaixamento do centro de banda d da Pt devido à ligação da Pt com Ni ou Co remanescente na partícula. Estas estruturas mostraram que é possível o desenvolvimento de eletrocalisadores com baixa carga de platina, mas com atividade superior ao do material no estado-da-arte de Pt/C, através de modificações na estrutura e composição da nanopartícula.The oxygen reduction reaction (ORR) was studied on eletrocatalysts with core-shell structures formed by Pt monolayers deposited on Au and Pd, and by hollow strutures of Pt. The core-shell nanoparticles were synthesized by the Under Potention Deposition technique, using Au and Pd as substrates. The hollow structures were prepared starting foram core-shell nanoparticles of Pt deposited on Ni or Co, followed by electrochemical cycling in acid media. The eletrocatalysts were characterized using techniques of X Ray Diffration, Energy Dispersive X Ray Spectroscopy, X Ray Absorpion Spectroscopy, and Transmission Electron Microscopy. The electrochemical tests were cyclic voltammetry, and polarization curves with rotating disk electrode. The core-shell electrocatalysts howed high activity for the ORR, this increase being associated with changes in the geometric and electronic properties of Pt, caused by the presence of Au and Pd atoms, leading to a lower adsorpion strength of Pt-O. This effect conducts to a better balance of reactivity for the two opposing tendencies of breaking and bond formation in the reaction intermediates adsorbed on the catalyst surface. The Pt hollow nanoparticles showed higher activity in relation to that of Pt/C, which was attributed to the effects of contraction of the Pt lattice and the Pt electronic strutucture modification, which results ind down-shift of the Pt d-band center, leading to a lower Pt-O adsorption strength. This work has demonstrated that it is possible to design electrocatalyst structures with low Pt loading, but with higher electrocatalytic activity compared to that of the state-of-the-art Pt/C material, using changes in the nanoparticle structure and composition.
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Khanal, Abhisek. "Review of Hollow Core Floor Slab in New Zealand – History of Practice, Past Research, and Failure Modes Seen in Research and Recent Earthquakes." University of Toledo / OhioLINK, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=toledo1564480135728695.
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Lindwall, Caroline, and Jonas Wester. "Modelling Lateral Stability of Prefabricated Concrete Structures." Thesis, KTH, Betongbyggnad, 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-188586.
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Stability calculations of prefabricated concrete structures with help of FEM-tools demand knowledge about how the elements are related to each other. This thesis concerns how joints between building elements affect the results when modelling prefabricated concrete structures, with demarcation to joints between hollow core (HC) slabs and between solid wall elements. The thesis also covers how the properties of the floor can be adjusted to account for the effects of the joints without modelling every single element. The work started by measuring the deflection of 10 HC-slabs jointed together and loaded in-plane acting as a deep beam, in a FE-model made with Robot™, from Autodesk®. The joints between the HC-elements were modelled either rigid or elastic, and the cross-section and the length of the HC-elements were varied. The linear elastic stiffness between the HC-elements was obtained from the literature as 0.05 (GN/m)/m. The results showed that a changed cross-section geometry gave greater differences in deformation than a changed length. The in-plane shear modulus was then adjusted for the HC-elements in the rigid cases until the same deflection was achieved as for the elastic cases. The result showed that the shear modulus in average for the different cross-section geometries and lengths had to be reduced with a factor of 0.1 to account for the joints. Based on the geometry of a castellated joint between prefabricated solid concrete walls, a calculation model was developed for its linear elastic stiffness. The result was a stiffness of 1.86 (GN/m)/m. To verify the calculated stiffness, a FE-model was developed consisting of a 30m high wall, loaded horizontally in-plane and with one or two vertical joints where the stiffness was applied. The deflection and the reaction forces were noted and the result from the calculated stiffness was compared to other stiffnesses and assessed reasonable. The reaction forces were shown to depend on the stiffness of the joint. The reduced in-plane shear modulus of the HC-elements and the calculated stiffness of the wall joints were then used in a FE-model of a 10-storey building stabilised by two units. The vertical reaction forces were analysed and the results showed 0.02 % difference in the reaction forces in the stabilising units when consideration of the joints between the HC-elements were taken into account and 0.09 % when the vertical joints in the shear wall were taken into account. The results for the wall joint differed from the results when only the wall was modelled. This was thought to be a result of that the floors counteract the shear deformations in the wall joints. The influence of the floor joints was not significant for the building considered in this thesis, but for buildings with non-continuous configuration of the stiffness in the shear walls the outcome may be another, in these cases the reduction factor may be useful.Vid stabilitetsberäkningar av prefabricerade betongstommar med hjälp av FEM-verktyg ställs krav på kunskap om hur elementen förhåller sig till varandra. Detta arbete berör hur fogar mellan byggnadselement påverkar modellering av prefabricerade betongstommar med avgränsning till fogar mellan håldäckselement och mellan solida väggelement. Arbetet berör även en studie i hur ett bjälklags egenskaper kan justeras så att fogarnas effekt kan tillvaratas utan att modellera varje enskilt håldäckselement. Arbetet inleddes med att utböjningen analyserades hos 10 st ihopskarvade håldäckselement, lastade i dess plan likt en hög balk, i en FE-modell skapad i programmet Robot™, från Autodesk®. Fogarna mellan håldäcken modellerades som antingen rigida eller elastiska och håldäckens tvärsnittsgeometri och längd varierades under testet. Den linjära styvheten mellan håldäcken togs från litteraturen som 0.05 (GN/m)/m. Resultatet visade att ändrad tvärsnittsgeometri gav större skillnader för deformationen än varierad längd på håldäcken. Håldäckens skjuvmodul justerades sedan i dess plan för de rigida testen tills dess att de uppnådde samma utböjning som de elastiska. Resultatet visade att skjuvmodulen behövdes reduceras med en faktor 0.1, i medeltal för de olika tvärsnittsgeometrierna och håldäckslängderna. Utefter geometrin på en fog med förtagningar mellan prefabricerade väggar togs en beräkningsmodell fram för den linjärelastiska styvheten i väggfogarna. Resultatet blev en styvhet på 1.86 (GN/m)/m. För att verifiera den beräknade styvheten togs en FE-modell fram bestående av en 30m hög vägg lastad horisontellt i dess plan med en eller två vertikala fogar där en linjär styvhet applicerades. Utböjningen samt reaktionskrafterna noterades, resultatet för den uträknade linjära styvheten jämfördes med andra styvheter och bedömdes utifrån detta vara rimlig. Reaktionskrafterna visade sig vara beroende av styvheten på fogen. Den sänkta skjuvmodulen för håldäcken och den beräknade linjära elasticiteten för väggarna användes sedan i en FE-modell av en 10-våningsbyggnad med två stabiliserande enheter där de vertikala reaktionskrafterna analyserades. Resultatet visade att endast 0.02 procentenheter skiljer reaktionskrafterna i de stabiliserande enheterna då hänsyn tas till fogarna mellan håldäcken och 0.09 procentenheter då hänsyn tas till fogarna mellan väggarna. Resultatet skiljer sig från när endast väggen modellerades, vilket tros bero på att bjälklaget hjälper till att motverka deformationer i väggfogarna. Fogen mellan bjälklagselementen tros kunna ha större inverkan på en byggnad med stabiliserande enheter som drastiskt ändrar styvhet från ett plan till ett annat, i dessa fall kan den framtagna reduktionsfaktorn vara av nytta.
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Ren, Mei Juan. "Optimal predictive control of thermal storage in hollow core ventilated slab systems." Thesis, Loughborough University, 1997. https://dspace.lboro.ac.uk/2134/12436.
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The energy crisis together with greater environmental awareness, has increased interest in the construction of low energy buildings. Fabric thermal storage systems provide a promising approach for reducing building energy use and cost, and consequently, the emission of environmental pollutants. Hollow core ventilated slab systems are a form of fabric thermal storage system that, through the coupling of the ventilation air with the mass of the slab, are effective in utilizing the building fabric as a thermal store. However, the benefit of such systems can only be realized through the effective control of the thermal storage. This thesis investigates an optimum control strategy for the hollow core ventilated slab systems, that reduces the energy cost of the system without prejudicing the building occupants thermal comfort. The controller uses the predicted ambient temperature and solar radiation, together with a model of the building, to predict the energy costs of the system and the thermal comfort conditions in the occupied space. The optimum control strategy is identified by exercising the model with a numerical optimization method, such that the energy costs are minimized without violating the building occupant's thermal comfort. The thesis describes the use of an Auto Regressive Moving Average model to predict the ambient conditions for the next 24 hours. A building dynamic lumped parameter thermal network model, is also described, together with its validation. The implementation of a Genetic Algorithm search method for optimizing the control strategy is described, and its performance in finding an optimum solution analysed. The characteristics of the optimum schedule of control setpoints are investigated for each season, from which a simplified time-stage control strategy is derived. The effects of weather prediction errors on the optimum control strategy are investigated and the performance of the optimum controller is analysed and compared to a conventional rule-based control strategy. The on-line implementation of the optimal predictive controller would require the accurate estimation of parameters for modelling the building, which could form part of future work.
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Giraud, Carrier Matthieu C. "Perforated Hollow Core Waveguides for Alkali Vapor-cells and Slow Light Devices." BYU ScholarsArchive, 2016. https://scholarsarchive.byu.edu/etd/5692.
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The focus of this work is the integration of alkali vapor atomic vapor cells into common silicon wafer microfabrication processes. Such integrated platforms enable the study of quantum coherence effects such as electromagnetically induced transparency, which can in turn be used to demonstrate slow light. Slow and stopped light devices have applications in the optical communications and quantum computing fields. This project uses hollow core anti-resonant reflecting optical waveguides (ARROWs) to build such slow light devices. An explanation of light-matter interactions and the physics of slow light is first provided, as well as a detailed overview of the fabrication process. Following the discovery of a vapor transport issue, a custom capillary-based testing platform is developed to quantify the effect of confinement, temperature, and wall coatings on rubidium transport. A mathematical model is derived from the experimental results and predicts long transport times. A new design methodology is presented that addresses the transport problem by increasing the number of rubidium entry points. This design also improves chip durability and decreases environmental susceptibility through the use of a single copper reservoir and buried channel waveguides (BCWs). New chips are successfully fabricated, loaded, and monitored for rubidium spectra. Absorption is observed in several chips and absorption peaks depths in excess of 10% are reported. The chip lifetime remains comparable to previous designs. This new design can be expanded to a multi-core platform suitable for slow and stopped light experimentation.
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Bradley, Thomas David. "Atomic vapours filled hollow core photonic crystal fibre for magneto-optical spectroscopy." Thesis, University of Bath, 2014. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.616871.
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This thesis describes developments in atomic vapour loading in hollow core photonic crystal fibre (HC-PCF) for fabrication of atomic vapour loaded photonic microcells (PMC). These developments have been targeted at addressing some of the issues associated with loading atomic vapours in confined waveguiding geometries such as increased dephasing and physio-chemical wall absorptions. Atomic vapour loaded HC-PCF and PMC’s have applications in laser metrology, coherent optics and magneto optical spectroscopy. State of the art HC-PCF have been fabricated for loading with atomic vapour including both photonic bandgap (PBG) guiding and inhibited coupling (IC) hypocycloidal core shape Kagome HC-PCF. Record loss of 70 dB/km has been achieved in IC hypocycloid core shape Kagome HC-PCF in the spectral region centred at 800 nm. This fibre retains excellent single mode propagation combined with large core and increased optical bandwidth in comparison with specialist PBG HC-PCF optimised for operation around 800 nm. Aluminosilicate sol-gel coatings have been developed and successfully applied to the inner core wall of HC-PCF’s to reduce the atomic vapour surface interaction. Confining atomic vapours in micron scaled HC-PCF results in increased dephasing rates because of the frequent atom wall collisions. Anti relaxation coating materials have been applied to the inner core wall and the longitudinal relaxation time has been measured in coated and uncoated fibres utilising a magneto optical technique. Additionally sub Doppler transparencies are investigated in anti relaxation coated and uncoated HC-PCF.
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Beroukhim, Farnaz A. "New applications of hollow-core components in housing, administrative and public housing." Thesis, Massachusetts Institute of Technology, 1985. http://hdl.handle.net/1721.1/71362.
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Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Architecture, 1985.MICROFICHE COPY AVAILABLE IN ARCHIVES AND ROTCH.
Includes bibliographical references (leaves 71-72).
Standard prestressed hollow-core slabs have many advantages as construction members while being relatively very low in cost. The principal advantages include the ease of mass production, a small cross-sectional area, light weight, and flat surfaces. In addition, the slabs have the advantage s of concrete, precasting and prestressing. The only specifications which make hollow-core components unsuitable for wall members are their lack of weight and mass, their inability to be used as long members because of the limited distance between the floor-to-floor height, and, in some cases, insufficient insulating qualities. This thesis recommends a practical and economical system for the structural use of hollow-core components which have been modified with two other additional structural members - a continuous precast "L" beam and a precast support panel. This system will allow a high degree of standardization and an additional saving in the total cost of the equipment and formworks. Most of all, the wall members have the advantages of precast prestressed hollow-core slabs and their low cost. The new system's applications are mainly directed towards housing, administrative and public buildings. A design example is also introduced and analyzed in terms of possible variations in area of the individual units and the total cost of the building . The latter case shows that the total cost of structure per square-foot for the recommended system is considerably lower than the other construction types.
by Farnaz A. Beroukhim.
M.S.
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Jammi, Sindhu. "Towards quantum optics experiments with trapped atoms in a hollow-core fibre." Thesis, University of Nottingham, 2018. http://eprints.nottingham.ac.uk/49896/.
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A proposal for performing quantum memory schemes with a light matter interface in Hollow Core Fibres is introduced. Various technical aspects of implementing such a scheme in the proposed interface are outlined and the different elements required to realize this scheme are discussed, primarily the detection of atomic levels and the extension of the scheme to magnetically trappable levels. A new method to dispersively measure populations and population difference of alkali atoms prepared in their two clock states is introduced, for future use in the Hollow Core Fibre interface. The method essentially detects the atom numbers based on the influence of the linear birefringence in the ensemble on the detection light beams via polarization homodyning. Sideband detection is performed after dressing the atoms with a radio-frequency field to circumvent low-frequency technical noises. The noise performance of this scheme is discussed along with design modifications aimed at reaching the atomic shot noise limit. Another technical aspect of realizing the quantum memory scheme in the proposed light-matter interface is the extension of the scheme to the trappable states of the atomic system as the atoms will be trapped in an atom chip magnetic field. We achieve this extension by showing the microwave spectroscopy of the ground state ensemble of radio-frequency dressed atoms which proves the existence of pseudo one-photon transitions between the trappable clock states. Finally, the preliminary designs and results of integrating an HCF in an atom chip experiment are discussed.
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Apostolou, Konstantinos. "Optimisation of hollow core slabs : Producing units of a smaller standard width." Thesis, KTH, Byggvetenskap, 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-283993.
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The Swedish precast concrete company ‘Strängbetong’ produces a variety of Hollow Core slabs, with a standard width of 1200 mm. Quite often, the HC units are subjected to longitudinal cutting1, which takes place in the factory by a diamond blade, in order to achieve narrower elements. This results in a considerable material waste since the rest part of the HC unit cannot always be utilized. Regarding the cutting process, it requires a significant amount of time that slows down the production. Moreover, extra workhands are needed, while other factors such as the transfer and crash of unwanted pieces, contribute to a higher cost for the factory. Approximately 12% of the HC elements produced by Strängbetong are fillers. Aiming to achieve a more efficient and sustainable production, the reduction of the number of fillers is of vital importance.This thesis project investigates if a line producing smaller width elements would be more profitable. The study starts by investigating the most common width that HCs are cut, with the aim to create a line according to this width2. Then, the most promising width is determined, taking into account the possible alternatives and fillers’ width trends that have been found. To estimate accurately the possible cost saving, the impact of the smaller width line on the production and the possible increase of thru put3, the production of the factory in Kungsör, is simulated on MATLAB. Firstly, the current situation is simulated (8 lines, 1200-mm-wide) in order to evaluate the current efficiency. Then, the studied scenario is simulated (7 lines 1200-mm-wide and one 813-mm-line), to evaluate the advantages of this alteration. Both simulations start by imposing the HC production load of 2019. This thesis is completed by a repetition of the simulations, where the input data are modified, in an effort to calculate accurately the possible cost saving as a function of designers’ adaption to the 813-mm-line.The results show that if an 813-mm-line were used instead of a 1200-mm-line during 2019, the possible cost saving would be at least 1.0 million SEK annually. The suggested line leads to a more sustainable production, as concrete and steel waste can be decreased by 51.6% and 50.3%, respectively. A significant amount of time due to less longitudinal cutting can be saved while there is a slight increase of thru put. Moreover, the results show that the factory will be able to handle the pressure on the production, despite the decrease by 1/8 of the physical production capacity of 1200 mm units. Finally, if the designers adapt fast to the new width alternative, the possible cost saving would rise significantly. If it is possible to design 1 out of 5 future fillers as a full-width element, cost saving can reach 1.4 million SEK annually.
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Garlyyev, Batyr. "Synthesis and catalytic study of shell-shell, core-shell hollow gold nanocatalysts." Diss., Georgia Institute of Technology, 2016. http://hdl.handle.net/1853/54996.
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Metal nanoparticles have a large surface area to volume ratio compared to their bulk counterparts, which makes them attractive to use as catalysts. Atoms on the surface of metal nanoparticles are very active due to their high surface energy resulting from their unsatisfied valency. First synthesis of gold nanoparticles with different shapes and bimetallic structure are explored in detail. Then an experimental method which could distinguish between the two mechanisms (homogeneous or heterogeneous) by using hollow plasmonic gold nanocatalyst is developed. Furthermore the catalytic activity of gold nanocages was changed by adding an inner platinum or palladium nanoshell. Results suggested that adding palladium inner shell increased the activity of gold nanocages towards the reduction nitro groups to amino groups. Controlling the selectivity of the catalyst is an important goal of catalysis research. Lastly selectivity of the plasmonic nanocatalyst (Gold sphere-Gold shell Nanorattles) with multiple plasmon modes was studied for photo-dimerization of nitro groups into azo dimers were studied on gold nanocatalyst surface. Results showed that selectivity can be controlled by changing the wavelength of the light exciting surface plasmon.
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Tipparaju, Venkata Satya Sai Sarma. "An active core fiber optic gas sensor using a photonic crystal hollow core fiber as a transducer." Master's thesis, Mississippi State : Mississippi State University, 2007. http://sun.library.msstate.edu/ETD-db/theses/available/etd-06262007-164352/.
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Rinaldi, Nicola. "Thermal Mass, Night Cooling and Hollow Core Ventilation System as Energy Saving Strategies in Buildings." Thesis, KTH, Byggnadsteknik, 2009. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-34855.
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Couny, Francois. "Photonic solutions towards optical waveform synthesis." Thesis, University of Bath, 2008. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.478946.
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This thesis presents the development of photonic tools towards the realisation of an optical intensity waveform synthesiser and of an attosecond pulse synthesiser based on the generation and Fourier synthesis of a continuous-wave coherent spectral comb spanning more than 3 octaves (UV to mid-IR) by use of a gas-filled hollow core photonic crystal fibre (HC-PCF).
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Abdul, Hamid Nor Hayati. "Seismic damage avoidance design of warehouse buildings constructed using precast hollow core panels." Thesis, University of Canterbury. Civil Engineering, 2006. http://hdl.handle.net/10092/1153.
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Precast prestressed hollow core units are commonly used in the construction of the flooring system in precast buildings. These units without transverse reinforcement bars are designed to resist seismic loading as replacement for fixed-base precast wall panels in the construction of warehouse buildings. Thus, this research seeks to investigate the seismic performance of the units constructed as a subassemblage (single wall) subjected to biaxial loading and as a superassemblage (multi-panel) subjected to quasi-static lateral loading. A design procedure for warehouse building using precast hollow core walls under Damage Avoidance Design (DAD) is proposed. In addition, a risk assessment under Performance-Based Earthquake Engineering (PBEE) is evaluated using the latest computational tool known as Incremental Dynamic Analysis (IDA). A comparative risk assessment between precast hollow core walls and fixed-base monolithic precast wall panels is also performed. Experimental results demonstrate that rocking precast hollow core walls with steelarmouring do not suffer any non-structural damage up to 2.0% drift and minor structural damage at 4.0% drift. Results revealed that the wall with unbonded fuse-bars and 50% initial prestressing of unbonded tendons performed the best compared with other types of energy dissipators. Furthermore, 12mm diameter of fuse-bar is recommended as there is no uplifting of the foundation beam during ground shaking. Hence, this type of energy dissipator is used for the construction of seismic wall panels in warehouse buildings. One of the significant findings is that the capacity reduction factor (Ø ) which relates to global uncertainty of seismic performance is approximately equal to 0.6. This value can be used to estimate the 90th percentile of the structures without performing IDA. Therefore, the structural engineers are only required to compute Rapid-IDA curve along with the proposed design procedure.
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Numkam, Fokoua Eric Rodrigue. "Ultralow loss and wide bandwidth hollow-core photonic bandgap fibres for telecom applications." Thesis, University of Southampton, 2015. https://eprints.soton.ac.uk/383000/.
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Light guidance in air has significant potential in diverse photonics applications, one of hich is optical communications where it may be key to achieving lower attenuation and optical nonlinearity than in conventional silica fibres. This thesis presents research conducted as part of the EU FP7 project MODEGAP, and is concerned with the design of hollow-core photonic bandgap fibres (HC-PBGFs) with low loss and wide bandwidths suitable for high capacity data transmission. In these fibres, loss is dominated by scattering from surface roughness and is subject to the design of the fibre cross-section. Using the criterion of reduced guided mode-field intensity at the interfaces, we conduct detailed finite element simulations which allow to identify preferable structures. A theory of light scattering from surface roughness in HC-PBGFs is then derived, and expressions are obtained which combine statistical information on the roughness and the guided mode-field overlap with scattering surfaces to predict the far-field scattering pattern and the fibre loss. A model based on mass conservation is proposed to predict the properties of HC-PBGFs from knowledge of the preforms from which they are made, and this in turn allows optimizing the design of such preforms. A method allowing accurate modelling of fabricated HC-PBGFs from scanning electron micrographs of their cross-sections is devised and such simulations indicate that structural distortions in the fibre cross-section cause higher field intensities near the interfaces, and hence higher losses. Systematic studies of distortions are then conducted, and it is found that not all distortions are equally detrimental. Combining these findings and using realistic estimates, a HC-PBGF design with 37 cell core defect and loss as low as 0.2dB/km over 580nm of bandwidth near the wavelength of 2μm is presented.
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Wang, Chenchen. "Optical frequency references in acetylene-filled hollow-core optical fiber and photonic microcells." Diss., Kansas State University, 2015. http://hdl.handle.net/2097/18831.
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Doctor of PhilosophyDepartment of Physics
Kristan L. Corwin
Optical frequency references have been widely used in applications such as navigation, remote sensing, and telecommunication industry. For stable frequency references in the near-infrared (NIR), lasers can be locked to narrow absorption features in gases such as acetylene. Currently, most Near NIR references are realized in free space setups. In this thesis, a low-loss hollow-core optical fiber with a diameter of sub millimeters is integrated into the reference setup to provide long interaction lengths between the filling gas and the laser field, also facilitate the optical interaction with low power levels. To make portable NIR reference, gas can be sealed inside the hollow-core fiber, by creating a photonic microcell. This work has demonstrated all-fiber optical frequency references in the Near IR by fabricating and integrating gas sealed photonic microcells in the reference setup. Also, a thoughtful study regarding the lineshape of the fiber-based reference has been accomplished. According the proper modeling of a shift due to lineshape, a correction was applied to our previous absolute frequency measurement of an NIR optical frequency reference. Furthermore, effects of the hollow-core fibers, including mode-dependence frequency shift related to surface modes are explored. In addition, angle splicing techniques, which will improve the performance of the fiber-based frequency reference have been created. Low transmission and return loss angle splices of photonic bandgap fiber, single mode PCF, and large core kagome to SMF-28 are developed and those fibers are demonstrated to be promising for photonic microcell based optical frequency references. Finally, a potentially portable optical metrology system is demonstrated by stabilizing a fiber-laser based frequency comb to an acetylene-filled optical fiber frequency reference. Further work is necessary to fabricate an all-fiber portable optical metrology system with high optical transmission and low molecular contamination.
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Rajala, Jonathan Watsell. "ELECTROSPINNING FABRICATION OF CERAMIC FIBERS FOR TRANSPARENT CONDUCTING AND HOLLOW TUBE MEMBRANE APPLICATIONS." University of Akron / OhioLINK, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=akron1480909959851349.
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Chow, Kam Kong. "A raman cell based on hollow core photonic crystal fibre for human breath analysis." Thesis, University of British Columbia, 2012. http://hdl.handle.net/2429/43593.
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Knabe, Kevin. "Using saturated absorption spectroscopy on acetylene-filled hollow-core fibers for absolute frequency measurements." Diss., Manhattan, Kan. : Kansas State University, 2010. http://hdl.handle.net/2097/4126.
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Woods, Lisa Joy. "The significance of negative bending moments in the seismic performance of hollow-core flooring." Thesis, University of Canterbury. Civil and Natural Resources Engineering, 2008. http://hdl.handle.net/10092/2042.
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Hollow-core flooring units are designed as simply supported members. However, frequently in construction, continuity is established between the units and supporting structure by the addition of insitu topping concrete and steel reinforcement. This change in structural form can result in negative bending moments and axial forces being induced in the floor by seismic and other structural actions. Significant negative moments are induced by load combinations that include the effects of seismic forces due to vertical ground motion. The focus of this research was two failure mechanisms possible under these loading conditions, a flexural failure and a shear failure. Both failure mechanisms were investigated analytically and experimentally.
A brittle flexural failure was observed experimentally in a sub assembly test that contained starter bars and mesh reinforcement in the insitu topping concrete. The failure occurred at loads lower than those predicted using standard flexural theory. It appears that, due to the prestressing and low reinforcement ratio of the topping concrete, the assumption that plane sections remain plane is not appropriate for this situation. It is proposed that a strain concentration factor be introduced to account for the effects of tension stiffening. This factor improves the correlation between observed and predicted flexural strength.
The second failure mode investigated was a flexure shear failure in a negative moment zone. Flexural cracks reduce the shear strength of a reinforced concrete member. Analytical predictions suggest that some hollow-core floor details could be prone to this type of brittle failure. A flexure shear failure was not observed experimentally; however, this does not eliminate the possibility of this failure mode.
A summary of other failure mechanisms possible in hollow-core flooring is also presented. All failure modes should to be considered as part of establishing a hierarchy of failure in the design or retrofit of hollow-core floors.
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O'Neill, Kevin. "FEASIBILITY STUDY OF LIGHTWEIGHT HIGH-STRENGTH HOLLOW CORE BALSA-FRP COMPOSITE BEAMS UNDER FLEXURE." Master's thesis, University of Central Florida, 2010. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/3109.
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The United States of America s Military, more specifically the Army, has since the late 1990 s had a vested interest in the development of super-lightweight, portable, short-span composite bridge and decking components to replace aging heavy metal-alloy machine driven modular systems. The following study looks at the feasibility of using balsa wood as the structural core material in fiber reinforced polymer (FRP) wrapped hollow-core composites in short-span bridge applications. The balsa provides shear resistance and the FRP the flexural resistance, resulting in extremely high strength-to-weight and strength-to-depth ratios. Several scaled short span specimens were constructed and tested using a variety of fibers and resins. In addition, a calibrated finite element model (FEM) was developed using data acquired through testing. Of the 3 FRP-matrices tested (carbon-polyurethane, glass-polyurethane, and carbon-epoxy-resin), the carbon-epoxy-resin had the stiffest cross-section and highest ultimate load achieved, although the fiber did not have the highest elastic modulus and ultimate rupture strength of the constituent materials. The carbon-polyurethane fiber had the largest elastic modulus and ultimate strength, but due to construction difficulties did not perform as well as expected. The glass-polyurethane fiber had the lowest elastic modulus and ultimate load with high strain values and performed accordingly during specimen testing. Given the constraints of self-weight, section geometry, and deflection set forth for lightweight short-span portable bridging solutions, this study demonstrates that the balsa-FRP composite systems are viable solutions; in particular, when carbon fabric is paired with balsa cores.M.S.C.E.
Department of Civil and Environmental Engineering
Engineering and Computer Science
Civil Engineering MS
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Wong, Nicholas Heng Loong. "Characterisation of hollow-core photonic bandgap fibres and other multimode fibres for optical communications." Thesis, University of Southampton, 2017. https://eprints.soton.ac.uk/419655/.
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Progress in multimode fibre technology has opened diverse opportunities in science and technology, one of which is pushing data capacities beyond the fundamental limits of conventional single-mode fibre, so as to avert network gridlock precipitated by exponentially growing global traffic demands. Hollow-core photonic bandgap fibres (HC-PBGFs), where light propagates in air rather than glass, have been considered as a potential candidate for high-capacity telecommunications applications, while offering superior performance over solid-core fibres in terms of low loss, low latency, and ultralow nonlinearity. This thesis presents research conducted as part of the efforts of the EU FP7 project MODE-GAP to pioneer developments in HC-PBGF and related space-division multiplexing technologies. This work is involved with the characterisation of primarily HC-PBGFs and also solid-core multimode fibres, recently and respectively fabricated through the facilities of the Optoelectronics Research Centre and other project partners. A time-of-flight method is applied to make extensive measurements on these fibres to study their modal properties, including mode coupling and differential modal delay, in order to assess their capabilities for single-mode as well as mode-division multiplexed data transmission. In support of the fibre design process, this work has aided the full characterisation of the first ever fabricated 37-cell HC-PBGFs and enabled subsequent mode-division multiplexing trials at a record capacity of 73.7 Tbit/s. Characterisation of multi-kilometre record-length HC-PBGFs is also performed, and has supported the demonstration of these fibres in metro network environments. To further understand the modal processes and facilitate fibre improvement, a simulation environment is constructed based on a power coupling propagation model. This has enhanced interpretations of experimental time-of-flight data, as well as validated a proposed theory relating mode coupling and loss in HC-PBGFs. Finally, an experimental technique is introduced to inspect longitudinal defects in solid- and hollow-core fibres, by applying time-of-flight principles.
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Wang, Yingying. "Quantum-fluctuation-initiated coherent Raman comb in hydrogen-filled hollow-core photonic crystal fibre." Thesis, University of Bath, 2011. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.545332.
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This thesis explores the generation and the coherence properties of Raman frequency combs that are initiated from vacuum fluctuations using hydrogen-filled hollow-core photonic crystal fibre (HC-PCF). The motivation is to explore a novel route for generating attosecond pulses and waveform synthesis. To this end, work has been undertaken in the design and fabrication of HC-PCF, in the generation of Raman comb with a compact set-up and finally in an experimental demonstration of the mutual coherence between the comb spectral components. Here, the well-established photonic bandgap (PBG) HC-PCF is further developed. Surface mode spectral positions are controlled by chemical etching technique, and a single piece of fibre with two robust bandgaps is fabricated. Furthermore, the second established class of HC-PCF; namely large-pitch Kagome-lattice HC-PCF, has experienced challenging developments. This led to the fabrication of a hypocycloid-core seven-cell Kagome HC-PCF with comparable attenuation value to that of PBG HC-PCF while offering much larger bandwidth. Using the fabricated HC-PCF, different Raman frequency comb systems are developed. In addition to the previously-generated multi-octave Raman frequency comb from a large 1064 nm Nd:YAG Q-switch laser, several more compact version of Raman comb sources have been developed, including one whose lines lay in the visible and UV for applications in forensics and biomedicine. The Raman frequency comb generated inside a length of hydrogen-filled HC-PCF is further investigated by studying the coherence of the Raman lines. Despite of vacuum-fluctuation-initiation, it is demonstrated that the comb has self- and mutualcoherence properties within each single shot, bringing thus the possibility of generating attosecond pulses with non-classical properties.
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Antonopoulos, Grigorios. "Super-enhanced stimulated Raman scattering and particle guidance in hollow-core photonic crystal fibres." Thesis, University of Bath, 2006. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.425387.
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Hansell, Markus, and Panagiotis Tamtakos. "Dynamic analyses of hollow core slabs : Experimental and numerical analyses of an existing floor." Thesis, KTH, Bro- och stålbyggnad, 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-278539.
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For intermediate floors in residential and office buildings, as well as in parking garages and malls, there is a wide use of hollow core concrete slabs in Sweden today. Hollow core slabs are precast and prestressed concrete elements with cylindrical-shaped voids extending along the length of the slab. These structural elements have the advantage compared to cast-in-situ concrete slabs that they have a high strength, due to the prestressing, and that the voids allow for a lower self-weight. Additionally, the voids allow for a reduction in the use of concrete material. These characteristics offer possibilities to build long-span floors with slender designs. However, a consequence of the slenderness of the slabs is that such floors have an increased sensitivity to vibrations induced by various dynamic loads. In residential and office buildings vibrations are primarily caused by human activity, and therefore concerns related to the serviceability of such floors are raised. These vibrations are often not related to problems with structural integrity, but rather to different aspects of comfort of the residents or workers. The aim of this thesis is to provide additional information regarding the dynamic behavior of hollow core floors. An experimental modal analysis has been performed on an existing floor in an office building. The dynamic properties in the form of natural frequencies, mode shapes, damping ratios and frequency response functions were derived and analyzed from these measurements. Subsequently, several finite element models were developed, aiming to reproduce the experimental dynamic behavior of the studied floor. The measurements initially showed some unexpected dynamic responses of the floor. For this reason, more advanced methods of signal analyses were applied to the data. The analyses showed that the slab has some closely spaced modes and that the modes of the floor are complex to a certain degree. The finite element models were studied with different configurations. In particular, the effect the model size, boundary conditions, material properties and potential structural discontinuities have on the dynamic response of the slab was studied. Sufficiently good agreement has been achieved between the experimental and numerical results in terms of natural frequencies and mode shapes. The acceleration amplitude responses of the numerical models were generally higher than the ones obtained from the measurements, which leads to difficulties in matching of the frequency response functions.Håldäck i betong används idag i stor utsträckning som bjälklag i bostads- och kontorsbyggnader, liksom i parkeringsgarage och köpcentra. Håldäcksbjälklag består av prefabricerade och förspända betongelement, med cylindriska hål som sträcker sig i plattans längsriktning. Dessa konstruktionselement har fördelen, jämfört med platsgjutna betongplattor, att de har en hög hållfasthet på grund av förspänningen och att hålen möjliggör en lägre egenvikt. Dessutom gör hålen att en mindre mängd betongmaterial behövs. Dessa egenskaper ger möjligheter att bygga golv med långa spännvidder och slank design. En konsekvens av slankheten är emellertid att sådana golv har en ökad känslighet för vibrationer som orsakas av olika dynamiska belastningar. I bostads- och kontorsbyggnader orsakas vibrationer främst av mänsklig aktivitet, och därför finns det en del oro relaterad till sådana golvs brukbarhet. Dessa vibrationer är oftast inte relaterade till frågor om strukturell integritet, utan snarare till olika aspekter av boendes eller arbetares känsla av komfort. Syftet med detta examensarbete är att bidra till kunskapen om håldäcksbjälklags dynamiska beteende. En experimentell modalanalys har utförts på ett befintligt golv i en kontorsbyggnad. De dynamiska egenskaperna i form av egenfrekvenser, modformer, dämpning och frekvenssvarsfunktioner erhölls och analyserades med hjälp av dessa mätningar. Därefter utvecklades flera finita element modeller för att reproducera det experimentellt uppmätta dynamiska beteendet hos det studerade golvet. Mätningarna visade initialt något oväntade dynamiska responser från golvet. Av denna anledning applicerades mer avancerade signalanalysmetoder på datan. Analyserna visade att plattan har några moder inom ett litet frekvensintervall och att moderna till en viss grad är komplexa. De finita element modellerna studerades med olika konfigurationer. I synnerhet studerades effekten av modellstorleken, randvillkoren, materialegenskaperna och potentiella strukturella diskontinuiteter på golvets dynamiska respons. Tillräckligt bra överensstämmelse har uppnåtts mellan de experimentella och numeriska resultaten i form av egenfrekvenser och modformer. Accelerationsamplituderna för de numeriska modellerna var i allmänhet högre än de som erhölls under mätningarna, vilket leder till svårigheter att matcha frekvenssvarsfunktionerna.
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Dadashzadeh, Neda. "Improved performance of an optically pumped mid-infrared acetylene-filled hollow-core fiber laser." Diss., Kansas State University, 2017. http://hdl.handle.net/2097/36259.
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Doctor of PhilosophyDepartment of Physics
Kristan L. Corwin
The focus of this research is improving the pulse output energy of a mid-IR pulsed acetylene-filled Hollow-core Optical Fiber Gas LASer (HOFGLAS) system. Pump pulses and acetylene molecules interact with each other inside hollow-core photonic crystal fiber that effectively confines light and allows for strong gain. This results in lasing at 3.11 μm and 3.17 μm lines based on population inversion of acetylene molecules, which are optically pumped at rotational-vibrational overtones near 1.5 μm using 1 ns pulse duration from an optical parametric amplifier (OPA). This acetylene laser operates with no cavity mirrors because of a high gain in a single pass configuration. There are few laser sources in the mid-IR region while there are many applications for having a laser source in this range such as remote sensing, hazardous chemical detection, and breath analysis. This adds to the importance of the acetylene-filled HOFGLAS system. Some of the applications like remote sensing require high power. So, we moved toward power scaling this laser system by optimizing the laser operation through maximizing the OPA alignment to improve its modal content using longer length of fiber to increase the interaction length and improving the beam quality of the mid-IR emissions. The highest pulse energy ever obtained in the 3 µm mid-IR region from the acetylene-filled HOFGLAS after applying the improvements is reported here (1.4 μJ). Higher mid-IR pulse energies can be achieved by improving the pulse energy achievable from the OPA pump source and working with longer pulse duration to decrease the bandwidth of the OPA. This operation demonstrates many novel properties of acetylene-filled pulsed mid-IR hollow-core fiber lasers. The excellent spatial beam quality at highest power and phenomenological scaling of saturation power and efficiency with pressure that we observe point to the promise of power scaling and motivate further development of numerical models of the laser for deeper insight into these effects. M² measurement method was used to examine spatial beam quality and it was found to be fiber-dependent. For the improved setup, M² was investigated at several input pump powers in addition to the reproducibility checks. M² of 1.14 at the maximum output power motivates for beam combining to scale to higher power. The independence of efficiency on pressure is an evidence for reaching higher mid-IR power at a pressure where saturation behavior does not exist. achieving the highest mid-IR power to date, 1.4 μJ, encourages for building higher power OPA to produce high power mid-IR emissions. Taken as a whole, this laser exhibits novel behavior that motivates both numerical/theoretical investigation and further efforts to scale to higher powers.
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Harner, Mary. "Characterization of the mid-infrared wavelength dependent loss in hollow core photonic crystal fibers." Thesis, Kansas State University, 2015. http://hdl.handle.net/2097/18928.
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Master of ScienceDepartment of Physics
Brian Washburn
This research sought to characterize the length dependent loss of hollow core photonic crystal fibers (HC-PCF) in the mid-infrared. These fibers are used in gas-filled fiber lasers that operate in the mid-infrared range. A black body source which provided a broad mid-infrared spectrum was coupled into a HC-PCF and a fiber cut-back method was implemented to make the length dependent loss measurement. A monochromator was used to observe narrow bands of the broad spectrum provided by the black body source and the loss as a function of wavelength was constructed. The loss for four unique HC-PCF fibers was characterized across the wavelength range [lambda] =1754 nm to [lambda] =3220 nm. The best fibers demonstrated a loss of less than 2 dB/m across this range, with some fibers even exhibiting loss below 1 dB/m.
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Bateman, Samuel. "Hollow core fibre-based gas discharge laser systems and deuterium loading of photonic crystal fibres." Thesis, University of Bath, 2015. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.648951.
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Research towards the development of a gas-discharge fibre laser using noble gases, with target emission wavelengths in the mid-IR. Additional and separate work on gas treatment methods for managing the formation of photo-induced defects in silica glass.