Zobrazeno 1 - 10
of 18
pro vyhledávání: '"D. P. Lonie"'
Autor:
Graham Hall, D. P. Lonie
Publikováno v:
Journal of Geometry and Physics. 61:381-399
This paper studies the situation when two four-dimensional Lorentz manifolds (that is, space–times) admit the same (unparametrised) geodesics, that is, when they are projectively related. A review of some known results is given and then the problem
Externí odkaz:
https://explore.openaire.eu/search/publication?articleId=doi_________::278db6e384f7a934dfeb966c6a78ba04
https://doi.org/10.1016/j.geomphys.2010.10.007
https://doi.org/10.1016/j.geomphys.2010.10.007
Autor:
D. P. Lonie, G. S. Hall
Publikováno v:
Journal of Physics A: Mathematical and General. 39:2995-3010
This paper considers 4-dimensional manifolds upon which there is a Lorentz metric, h, and a symmetric connection and which are originally assumed unrelated. It then derives sufficient conditions on the metric and connection (expressed through the cur
Externí odkaz:
https://explore.openaire.eu/search/publication?articleId=doi_________::dd7d05f94481e918d5b8b55b5704f31f
https://doi.org/10.1088/0305-4470/39/12/009
https://doi.org/10.1088/0305-4470/39/12/009
Publikováno v:
GECCO
Problem structure, or linkage, refers to the interaction between variables in a black-box fitness function. Discovering structure is a feature of a range of algorithms, including estimation of distribution algorithms (EDAs) and perturbation methods (
Externí odkaz:
https://explore.openaire.eu/search/publication?articleId=doi_________::a0a21f7a55637dc6472089d1b57a91c1
https://doi.org/10.1145/2576768.2598240
https://doi.org/10.1145/2576768.2598240
Publikováno v:
Physics of Plasmas. 6:1374-1377
A region with chaotic magnetic field lines where the magnetic field (B) and plasma velocity (v) are continuous and differentiable and satisfy the dissipative incompressible magnetohydrodynamic equations with magnetic diffusivity η and kinematic visc
Externí odkaz:
https://explore.openaire.eu/search/publication?articleId=doi_________::dfd96e3446e43bd30fd4bc3bb53f940d
https://doi.org/10.1063/1.873386
https://doi.org/10.1063/1.873386
Publikováno v:
UKCI
Estimation of distribution algorithms (EDAs) use structure learning to build a statistical model of good solutions discovered so far, in an effort to discover better solutions. The non-zero coefficients of the Walsh transform produce a hypergraph rep
Externí odkaz:
https://explore.openaire.eu/search/publication?articleId=doi_________::ca8730c129c19096a0c0d78ff12f628b
https://doi.org/10.1109/ukci.2013.6651297
https://doi.org/10.1109/ukci.2013.6651297
Publikováno v:
Journal of Plasma Physics. 56:507-530
Linear null points of a magnetic field may come together and coalesce at a secondorder null, or vice versa a second-order null may form and split, giving birth to a pair of linear nulls. Such local bifurcations lead to global changes of magnetic topo
Externí odkaz:
https://explore.openaire.eu/search/publication?articleId=doi_________::011d4af294015149a92af9e21c74f35f
https://doi.org/10.1017/s0022377800019449
https://doi.org/10.1017/s0022377800019449
Publikováno v:
Journal of Geophysical Research: Space Physics. 101:7631-7646
Magnetic reconnection has traditionally been associated exclusively with the presence of magnetic null points or field lines tangential to a boundary. However, in many cases introducing a three-dimensional perturbation in a two-and-half-dimensional m
Externí odkaz:
https://explore.openaire.eu/search/publication?articleId=doi_________::76f98c9db515cf232f84cd0b1abb6e37
https://doi.org/10.1029/95ja03558
https://doi.org/10.1029/95ja03558
Autor:
Graham Hall, D. P. Lonie
Publikováno v:
Classical and Quantum Gravity. 12:1007-1020
Projective collineations in spacetimes, i.e. vector fields generating local groups of geodesic-preserving diffeomorphisms, are studied. The situation for Einstein spaces is resolved completely and some general results are established regarding arbitr
Externí odkaz:
https://explore.openaire.eu/search/publication?articleId=doi_________::a7c03626fef841b2272226c163175456
https://doi.org/10.1088/0264-9381/12/4/010
https://doi.org/10.1088/0264-9381/12/4/010
Autor:
D. P. Lonie, Graham Hall
Publikováno v:
Symmetry, Integrability and Geometry: Methods and Applications, Vol 5, p 066 (2009)
A study is made of 4-dimensional Lorentz manifolds which are projectively related, that is, whose Levi-Civita connections give rise to the same (unparameterised) geodesics. A brief review of some relevant recent work is provided and a list of new res
Externí odkaz:
https://explore.openaire.eu/search/publication?articleId=doi_dedup___::10bfc066ab0a8bac40d4a5ed69761191
https://doi.org/10.3842/sigma.2009.066
https://doi.org/10.3842/sigma.2009.066
Autor:
D. P. Lonie, Graham Hall
A study is made of the possible holonomy group types of a space-time for which the energy-momentum tensor corresponds to a null or non-null electromagnetic field, a perfect fluid or a massive scalar field. The case of an Einstein space is also includ
Externí odkaz:
https://explore.openaire.eu/search/publication?articleId=doi_dedup___::2e738feb625688e5afdef5a549eb02c2
http://arxiv.org/abs/gr-qc/0310076
http://arxiv.org/abs/gr-qc/0310076
