Search results for "A. Fibre"
showing 10 items of 78 documents
Luminescence properties of chlorine molecules in glassy SiO 2 and optical fibre waveguides
2017
The support from Latvian Research Program IMIS 2, project “Photonics and materials for photonics” is acknowledged. K.K. was partially supported by the Collaborative Research Project of Materials and Structures Laboratory, Tokyo Institute of Technology. The publication costs of this article were covered by the Estonian Academy of Sciences and the University of Tartu.
Quasi-static behaviour and damage assessment of flax/epoxy composites
2015
Experimental investigations were conducted on flax and E-glass fibres reinforced epoxy matrix composites subjected to quasi-static loadings. Flax/epoxy samples having [0]12, [90]12, [0/90]3S and [±45]3S stacking sequences, with a fibre volume fraction of 43% have been tested under tension, compression and in-plane shear loadings. Overall, the compression strength of glass/epoxy was 76% greater than for the flax/epoxy composite. The damage evolution of flax/epoxy of [0/90]3S and [±45]3S samples has been evaluated in terms of transverse crack densities with respect to the load increment. The crack density exhibited a classical “S” shaped pattern for [0/90]3S and linearly for [±45]3S specimens…
Degradation mechanisms under hydro-thermo-mechanical loads of natural fibers-reinforced biocomposites : application to the development of lightweight…
2018
With the current environmental concerns, research turns to alternative solutions to synthetic fibres. Vegetal fibers appears as good candidates, with good mechanical properties. However, their low durability is a major issue, especially when the composites are exposed to hydro(hygro)thermal loadings.The purpore of this thesis is to analyse and understand the degradation mechanisms when hydro-thermo-mechanical loadings are applied, in order to implement a predictive modelisation of the composite durability.The manufacturing process wasstudied and optimised to produce reproducible and strong composites. Two materials were produced. Their only difference is their volumetric fiber contents (37.…
Almond shell reuse: a viable non-conventional aggregate for sustainable building materials
2022
Bio-based or green architecture is a new way of designing and building in line with the European Green Deal and in light of the Circular Economy principles. The main green approach directs the whole construction life cycle to be eco-sustainable and environmentally friendly from the beginning to the end of the building process. Beyond the use of eco sustainable and highly performing structural materials, new technologies able of reduce the environmental impact of buildings must be used. This paper is aimed at reviewing the possible reuse of bio- wastes of agricultural origin whose massive production generates a number of issues for their treatment and disposal. In particular, this study will…
Fibre Bragg gratings tuned and chirped using magnetic fields
1997
The authors report on the use of magnetic fields in conjunction with magnetostrictive materials for tuning and chirping optical fibre Bragg gratings. The Bragg wavelength shifts as a consequence of the strain induced in the fibre by a magnetostrictive rod when a magnetic field is applied. A tuning range of 1.1 nm has been achieved by a magnetic field of 103 mT and the grating has been chirped by applying non-uniform magnetic fields.
A note on coverings with special fibres and monodromy group $ S_{d}$
2012
We consider branched coverings of degree over with monodromy group , points of simple branching, special points and fixed branching data at the special points, where is a smooth connected complex projective curve of genus , and , are integers with . We prove that the corresponding Hurwitz spaces are irreducible if .
Compression and injection molding of recycled polyethylene for greenhouses in presence of the natural fibres
2003
Supercontinuum generation with 532 nm quasi-continuum pulses in photonic crystal fibre tapers
2007
We report experimental results on supercontinuum generation in PCF tapers using quasi-continuous pump pulses of 7 ns duration at 532 nm. SC generation in normal and anomalous dispersion regimes are presented. Introduction Supercontinuum generation (SC) in photonic crystal fibres (PCF), fibre tapers, and PCF tapers has been demonstrated in the past with pump pulses of fs, ps, and tenths of ns duration [1-2]. Here, we present experimental results on SC generation in PCF tapers using quasi-continuous pump pulses of 7 ns duration at 532 nm. Fabrication of the PCF tapers The PCF from which the tapers were made, was a large-air-hole PCF ("cobweb" PCF) with two rings of air holes around a solid si…
Effect of sisal and hydrothermal ageing on the dielectric behaviour of polylactide/sisal biocomposites
2017
[EN] The dielectric properties of virgin polylactide (PLA) and its reinforced composites with different weight amounts of sisal fibres were assessed at broad temperature (from - 130 degrees C to 130 degrees C) and frequency ranges (from 10(-2)-10(7) Hz), before and after being subjected to accelerated hydrothermal ageing. The synergetic effects of both the loading of sisal and hydrothermal ageing were analysed by means of dielectric relaxation spectra. The relaxation time functions were evaluated by the Havriliak-Negami model, substracting the ohmic contribution of conductivity. The intramolecular and intermolecular relaxations were respectively analysed by means of Arrhenius and Vogel-Fulc…
Diode-pumped self-Q-switched erbium-doped all-fibre laser
2004
A diode-pumped self-Q-switched erbium-doped fibre laser is developed and studied. The laser has an all-fibre configuration containing a piece of an active heavily erbium-doped fibre and two fibre Bragg grating mirrors and does not require any additional intracavity elements to obtain short pulses. Analysis of the laser operation suggests that the most probable mechanism of passive Q-switching of the laser cavity is absorption from the excited state of erbium resulting in the thermally induced nonlinear change in the refractive index in the erbium-doped fibre.