22,558 research outputs found
Contributions to the relativistic mechanics of continuous media
This is a translation from German of an article originally published inProceedings of the Mathematical-Natural Science Section of the Mainz Academy of Science and Literature, Nr. 11, 1961 (pp. 792–837) (printed by Franz Steiner and Co, Wiesbaden), which is Paper IV in the series ldquoExact Solutions of the Field Equations of General Relativity Theoryrdquo by Pascual Jordan, Jürgen Ehlers, Wolfgang Kundt and Rainer K. Sachs. The translation has been carried out by G. F. R. Ellis (Department of Applied Mathematics, University of Cape Town), assisted by P. K. S. Dunsby, so that this outstanding review paper can be readily accessible to workers in the field today. As far as possible, the translation has preserved both the spirit and the form of the original paper. Despite its age, it remains one of the best reviews available in this area
On the Newtonian Limit of the Weyl Tensor
In this note we wish to complement some recent work in the cosmological
literature concerning the Weyl conformal curvature tensor and its parts. In
particular, we shall give a clear-cut definition of the Newtonian limits of
electric and magnetic parts of the Weyl tensor. We also discuss that only a
subset of the relativistic equations is needed to obtain a closed system of
equations in the Newtonian limit.Comment: 6 pages. Dedicated to the memory of Juergen Ehlers. To appear in the
upcoming Special Issue of "General Relativity and Gravitation
Low-Effort Specification Debugging and Analysis
Reactive synthesis deals with the automated construction of implementations
of reactive systems from their specifications. To make the approach feasible in
practice, systems engineers need effective and efficient means of debugging
these specifications.
In this paper, we provide techniques for report-based specification
debugging, wherein salient properties of a specification are analyzed, and the
result presented to the user in the form of a report. This provides a
low-effort way to debug specifications, complementing high-effort techniques
including the simulation of synthesized implementations.
We demonstrate the usefulness of our report-based specification debugging
toolkit by providing examples in the context of generalized reactivity(1)
synthesis.Comment: In Proceedings SYNT 2014, arXiv:1407.493
Propagation of High-Frequency Electromagnetic Waves Through a Magnetized Plasma in Curved Spaces-Time. II. Application of the Asymptotic Approximation
This is the second of two papers on the propagation of high-frequency electromagnetic waves through an inhomogeneous, non-stationary plasma in curved space-time. By applying the general two-scale W.K.B. method developed in part I to the basic wave equation, derived also in that paper, we here obtain the dispersion relation, the rays, the polarization states and the transport laws for the amplitudes of these waves. In an unmagnetized plasma the transport preserves the helicity and the eccentricity of the polarization state along each ray; the axes of the polarization ellipse rotate along a ray, relative to quasiparallely displaced directions, at a rate determined by the vorticity of the electron fluid; and the norm of the amplitude changes according to a conservation law which can be interpreted as the constancy of the number of quasiphotons. In a magnetized plasma the polarization state changes differently for ordinary and extraordinary waves, according to the angle between the wavenormal and the background magnetic field, and under specified approximation conditions the direction of polarization of linearly polarized waves undergoes a generalized Faraday rotation
Faster Sorting Networks for , and Inputs
We present new parallel sorting networks for to inputs. For and inputs these new networks are faster (i.e., they require less
computation steps) than the previously known best networks. Therefore, we
improve upon the known upper bounds for minimal depth sorting networks on and channels. The networks were obtained using a combination of
hand-crafted first layers and a SAT encoding of sorting networks
Joins for (Augmented) Simplicial Sets
We introduce a notion of join for (augmented) simplicial sets generalising
the classical join of geometric simplicial complexes. The definition comes
naturally from the ordinal sum on the base simplicial category .Comment: 8 page
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