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- Burke, S. R., et al.
(författare)
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Analysis of the foam-forming of non-woven lightweight fibrous materials using X-ray tomography
- 2021
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Ingår i: SN Applied Sciences. - : Springer Nature. - 2523-3963 .- 2523-3971. ; 3:2
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Tidskriftsartikel (refereegranskat)abstract
- Abstract: Foam-forming has in the past predominantly been used to create two-dimensional sheet-like fibrous materials. Allowing the foam to drain freely and decay under gravity, rather than applying a vacuum to remove it rapidly, we can produce lightweight three-dimensional fibrous structures from cellulose fibres, of potential use for thermal and acoustic insulation. μCT scanning of the fibrous materials enable us to determine both void size distributions and also distributions of fibre orientations. Through image analysis and uniaxial compression testing, we find that the orientation of the fibres, rather than the size of the voids, determine the compressive strength of the material. The fibrous samples display a layering of the fibres perpendicular to the direction of drainage of the precursor liquid foam. This leads to an anisotropy of the compressive behaviour of the samples. Varying the initial liquid fraction of the foam allows for tuning of the compressive strength. We show an increase in over seven times can be achieved for samples of the same density (13 kg.m-3). Graphic abstract: [Figure not available: see fulltext.]. © 2021, The Author(s).
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| 2. |
- Malisz, Zofia, et al.
(författare)
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Dimensions of Segmental Variability : Interaction of Prosody and Surprisal in Six Languages
- 2018
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Ingår i: Frontiers in Communication. - : Frontiers Media SA. - 2297-900X. ; 3
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Tidskriftsartikel (refereegranskat)abstract
- Contextual predictability variation affects phonological and phonetic structure. Reduction and expansion of acoustic-phonetic features is also characteristic of prosodic variability. In this study, we assess the impact of surprisal and prosodic structure on phonetic encoding, both independently of each other and in interaction. We model segmental duration, vowel space size and spectral characteristics of vowels and consonants as a function of surprisal as well as of syllable prominence, phrase boundary, and speech rate. Correlates of phonetic encoding density are extracted from a subset of the BonnTempo corpus for six languages: American English, Czech, Finnish, French, German, and Polish. Surprisal is estimated from segmental n-gram language models trained on large text corpora. Our findings are generally compatible with a weak version of Aylett and Turk's Smooth Signal Redundancy hypothesis, suggesting that prosodic structure mediates between the requirements of efficient communication and the speech signal. However, this mediation is not perfect, as we found evidence for additional, direct effects of changes in surprisal on the phonetic structure of utterances. These effects appear to be stable across different speech rates.
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