1,720,956 research outputs found
Dataset supporting the University of Southampton Doctoral Thesis "Novel fibres for next-generation fibre optic gyroscopes"
No full textDataset supporting the University of Southampton Doctoral Thesis "Novel fibres for next-generation fibre optic gyroscopes".
This is an ensemble of all gyro data acquisition runs for the multicore IFOG (MCIFOG ) and the benchmark PM IFOG (Benchmark IFOG) described in the thesis. The conditions for each individual test data run is given in an excel workbook which tabulates all the relevant conditions for the run. The Readme file gives a further description of all the data files.
All data can be processed via the MATLAB scripts contained in the folder "Gyro Data Analysis".
Process data by updating the "main_dir" variable in the main script, "analyze_gyro_data_v8.m", to match the data folder which is to be processed.
The temperature log for a given run can be processed simultaneously by enabling the "use_thermal_data" option.
Descriptions of processing options and other analysis features is given in the comments of the MATLAB code.
A detailed description of the test configuration for each gyro run is given in the excel files:
"MCIFOG 1 Test Log.xlsx" and "PM Gyro Test Log.xlsx"
Some of the data included in this set is given in the following publication:
A. Taranta, A. Gillooly, V. I. Kopp, D. Neugroschl, M. Ibsen, C. Emslie, and J. Sahu, "Performance Characteristics of a Multicore Interferometric Fiber Optic Gyroscope Using a 7-Core Fiber," in 2020 DGON Inertial Sensors and Systems (ISS) (IEEE, 2020), pp. 1–20.
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Novel fibres for next-generation fibre-optic gyroscopes
No full textThe fibre-optic gyroscope (FOG) is one of the most successful optical fibre sensors in history and it has become a keystone technology for high-performance rotation sensing. Its core sensing element is a long optical fibre wound into a coil. Here, sensitivity to rotation scales in proportion with optical path length, and thus much FOG development has been directed toward deploying longer fibres within the same footprint. However, the fibre itself can be a major source of signal errors via Rayleigh backscattering, polarization cross-coupling, environmental effects, and non-linearity – thus, high-performance FOGs require advanced strategies to suppress these limitations in their multi-kilometer long sensing coils. This work explores two exciting fibre technologies which show great potential to address these challenges. The first is multicore optical fibre (MCF), in which multiple, independent optical waveguides (cores) are placed within the same glass cladding. These densely packed cores increase optical length, and thus gyro sensitivity, while preserving the coil geometry. This work details the construction of a fully functional interferometric FOG employing state-of-the-art MCF. This demonstrator uses a 7-core, 154 m long fibre coil, and through acquisition of detailed performance data, we realize the 7X sensitivity improvement conferred by use of MCF. The promise of MCF for FOGs is further highlighted by illustrating novel designs and improvements to existing FOG systems which are afforded by this signal density enhancement. The second fibre technology is hollow core antiresonant fibre (ARF), in which a glass microstructure confines signal light to the central hollow region of the fibre. Ultra-low interaction between light and glass renders the fibre orders of magnitude less sensitive to material and environmental effects. This work highlights several benefits of ARFs for FOGs, including the first-ever measurements of polarization coupling in long, symmetric ARFs. These data show that polarization in ARFs can be 2-3 orders of magnitude purer than the theoretical limit for solid fibres. It is further shown, through use of an advanced resonator FOG testbed, that ARFs are immune to many of the material-related guidance impairments which beleaguer solid core FOGs. Through the analysis and demonstrations presented here we show the great promise that these two novel fibres can offer future FOGs. This is a boon for existing and emerging FOG applications which require high-performance navigation in a compact format – from new concepts in robotics and autonomous vehicles which are beginning to shape our world, to the next-generation of space and submarine applications which will explore new worlds
Dataset for "Support-Free Thermally Insensitive Hollow Core Fiber Coil"
No full textLight traversing an optical fiber is subject to various local phase perturbations driven by temperature. This thermal phase sensitivity is undesirable in fiber interferometers and their applications which require that a fixed, stable phase be received after propagation. The use of hollow core fiber (HCF) has been shown to reduce this thermal phase sensitivity over solid core fibers and here we propose and demonstrate how coiling HCF to a prescribed geometry can further significantly reduce this sensitivity. Our proof-of-concept experiment shows reduction by a factor of ~90 with respect to the uncoiled HCF, and over three orders of magnitude with respect to uncoiled solid core optical fiber. Our strategy exploits a nuance of the elastic properties of fiber coils whereby the constrained thermal expansion of the composite material (fiber + coating) can result in a coil having compressed inner layers and expanded outer layers. Thermal expansion is the dominant effect responsible for thermal phase sensitivity in HCFs, and in this scheme the compressed inner coil layers compensate the thermal expansion of the outer layers. In this study we design the coil parameters using finite element simulations, studying the relationship between coil performance and its key parameters. The proof-of-principle coil has 160 mm diameter and incorporates a 548 m length of HCF out of which a 230 m section shows almost zero (slightly negative) thermal phase sensitivity. Though the coil shows low thermal phase sensitivity over tens of hours, the long-time constant viscoelastic properties of the coating materials used in the HCF under study are shown to limit these benefits. To make this strategy practical for systems with fast temperature dynamics, a coating having more stable mechanical properties could be used. For precision timing systems in which long thermal time constants are already the norm, this scheme represents a low-cost and provides a significant reduction to thermal sensitivity which is immediately practicable.</span
Distributed measurement and modified Navier-Stokes model of gas pressure profile evolution in hollow-core antiresonant fibres
No full textRecent progress in reducing the loss of hollow-core fibres (HCFs) makes them great candidates for many fibre applications. However, as the fibre's optical properties depend on the gas pressure and composition within the core and cladding holes, it is essential to understand the gas dynamics at play when the fibres are pressurised, vented or evacuated. Here, we investigate the gas flow dynamics along the core of an HCF with a more complex microstructure design, as is typical of recent state-of-the-art HCFs. We use a novel distributed technique based on optical time-domain reflectometry (OTDR). This technique enables measurement of the evolution of the pressure distribution within the hollow core during the gas-filling process over long fibre lengths. Using these results, we show that the pressure distribution inside the HCF can be simulated using simplified Navier-Stokes equations and approximating the fibre core as a simple cylindrical tube of ∼ 0.7 times the fibre core diameter
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Dispelling the Myths Behind First-author Citation Counts
Full text linkWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
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