| 1. |
- Eggers, Jens, et al.
(författare)
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Singularities of relativistic membranes
- 2015
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Ingår i: Geometric Flows. - : Portico. - 2353-3382. ; 1:1
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Tidskriftsartikel (refereegranskat)abstract
- Pointing out a crucial relation with caustics of the eikonal equation we discuss the singularity formation of 2-dimensional surfaces that sweep out 3-manifolds of zero mean curvature in R3,1.
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| 2. |
- Eggers, J., et al.
(författare)
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Singularity formation for time-like extremal hypersurfaces
- 2009
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Ingår i: Physics Letters B. - : Elsevier BV. - 0370-2693 .- 1873-2445. ; 680:3, s. 274-278
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Tidskriftsartikel (refereegranskat)abstract
- We derive self-similar string solutions in a graph representation, near the point of singularity formation, which can be shown to extend to point-like singularities on M(em)branes, as well as to the radially symmetric case. Crown
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| 3. |
- Pocklington, Michael, et al.
(författare)
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A Biological Perspective on Digital Ecosystems and Digital Preservation
- 2014
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Ingår i: Proceedings of the 11th International Conference on Digital Preservation, 6-10 October, 2014, Melbourne, Australia. - 9780642278814 ; , s. 363-365
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Successful preservation of Digital Objects (DOs) ultimately demands a solid theoretical framework. Such a framework with a high degree of generality emerges by treating DOs as containers of functional genetic information, exactly as in the genomes of organisms. We observe that functionality links survival in organisms and utility in DOs. In both cases, functional information is identifiable in principle by the consequence of its ablation. In molecular biology, genetic ablations (mutations) and environmental ablations (experimental manipulations) are used to construct interaction maps fully representing organismic activity. The equivalent of such interaction maps are dependency networks for the use of DOs within their Digital Environment (DE). In the poster we will present early work on the application of the theoretical background. It includes first results from a case-study examining a software-based art preservation scenario (SBA) developed as part of the PERICLES FP7 project [1].
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| 4. |
- Strelnikov, Boris, et al.
(författare)
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Sounding rocket project PMWE for investigation of polar mesosphere winter echoes
- 2021
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Ingår i: Journal of Atmospheric and Solar-Terrestrial Physics. - : Elsevier BV. - 1364-6826 .- 1879-1824. ; 218
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Tidskriftsartikel (refereegranskat)abstract
- A first sounding rocket campaign dedicated to investigate the creation mechanism of Polar Mesosphere Winter Echoes (PMWE) was conducted in April 2018 from the north Norwegian Andøya Space Center (69 °N, 16 °E). Two instrumented sounding rockets were launched on 13th and 18th of April under PMWE and non-PMWE conditions, respectively. In this paper we give an overview of the PMWE sounding rocket mission. We describe and discuss some results of combined in situ and ground-based measurements which allow to verify existing PMWE theories. Our measurements ultimately show that: a) polar winter mesosphere is abounded with meteor smoke particles (MSP) and intermittent turbulent layers, b) all PMWE observed during this campaign can be explained by neutral air turbulence, c) turbulence creates small-scale structures in all D-region constituents, including free electrons; d) MSP ultimately influence the radar volume reflectivity by distorting the turbulence spectrum of electrons, e) the influence of MSP and of background electron density is just to increase SNR.
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| 5. |
- Yu, Yingxian Estella, et al.
(författare)
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Time-dependent motion of a confined bubble in a tube : transition between two steady states
- 2018
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Ingår i: Journal of Fluid Mechanics. - : Cambridge University Press. - 0022-1120 .- 1469-7645. ; 857
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Tidskriftsartikel (refereegranskat)abstract
- When a confined bubble translates steadily in a cylindrical capillary tube, without the consideration of gravity effects, a uniform thin film of liquid separates the bubble surface and the tube wall. In this work, we investigate how this steady state is established by considering the transitional motion of the bubble as it adjusts its film thickness profile between two steady states, characterized by two different bubble speeds. During the transition, two uniform film regions coexist, separated by a step-like transitional region. The transitional motion also requires modification of the film solution near the rear of the bubble, which depends on the ratio of the two capillary numbers. These theoretical results are verified by experiments and numerical simulations.
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