Results 21 to 30 of about 567 (106)
Ricci Collineations for Non-Degenerate, Diagonal and Spherically Symmetric Ricci Tensors [PDF]
, 1999 The expression of the vector field generator of a Ricci Collineation for diagonal, spherically symmetric and non-degenerate Ricci tensors is obtained.
A. H. Bokhari +11 more
core +2 more sources
Advances in Mathematical Physics, Volume 2017, Issue 1, 2017., 2017 The aim of this paper is to give the geometrical/physical interpretation of the conserved quantities corresponding to each Noether symmetry of the geodetic Lagrangian of plane symmetric space‐times. For this purpose, we present a complete list of plane symmetric nonstatic space‐times along with the generators of all Noether symmetries of the geodetic ...
Bismah Jamil +3 more
wiley +1 more source
Symmetries of distributional domain wall geometries
, 2003 Generalizing the Lie derivative of smooth tensor fields to distribution-valued tensors, we examine the Killing symmetries and the collineations of the curvature tensors of some distributional domain wall geometries.
Alberto Sanoja +4 more
core +1 more source
Classification of Spherically Symmetric Static Spacetimes according to their Matter Collineations [PDF]
, 2003 The spherically symmetric static spacetimes are classified according to their matter collineations. These are studied when the energy-momentum tensor is degenerate and also when it is non-degenerate.
A. A. Coley +19 more
core +2 more sources
Features from a Single Vector Pressure Stroke
Mathematical Problems in Engineering, Volume 2017, Issue 1, 2017., 2017 Freehand sketching in a real‐time 3D styling system presents a different way to create a 3D model from the traditional CAD system. Strokes are the most common and useful objects in the expression of a stylist’s intention by using the gesture commands and in the construction of geometries.
Qiang Li +6 more
wiley +1 more source
On the definition of matter collineations
, 2010 It is shown that when the stress-energy tensor of a spacetime is diagonal and is written in the mixed form, its collineations admit infinite dimensional Lie algebras except possibly in the case when the tensor depends on all the spacetime coordinates ...
ASGHAR QADIR +4 more
core +1 more source
Comment on Ricci Collineations for type B warped space-times [PDF]
, 2000 We present two counterexamples to the paper by Carot et al. in Gen. Rel. Grav. 1997, 29, 1223 and show that the results obtained are correct but not general.Comment: LaTex, 3 pages, Eq. (9) and reference added, typos corrected; Gen. Rel.
G. S. Hall +4 more
core +4 more sources
Relativistic Localizing Processes Bespeak an Inevitable Projective Geometry of Spacetime
Advances in High Energy Physics, Volume 2017, Issue 1, 2017., 2017 Surprisingly, the issue of events localization in spacetime is poorly understood and a fortiori realized even in the context of Einstein’s relativity. Accordingly, a comparison between observational data and theoretical expectations might then be strongly compromised. In the present paper, we give the principles of relativistic localizing systems so as
Jacques L. Rubin, Ralf Hofmann
wiley +1 more source
Non‐Perfect‐Fluid Space‐Times in Thermodynamic Equilibrium and Generalized Friedmann Equations
Journal of Gravity, Volume 2016, Issue 1, 2016., 2016 We determine the energy‐momentum tensor of nonperfect fluids in thermodynamic equilibrium and, respectively, near to it. To this end, we derive the constitutive equations for energy density and isotropic and anisotropic pressure as well as for heat‐flux from the corresponding propagation equations and by drawing on Einstein’s equations.
Konrad Schatz +3 more
wiley +1 more source
Multistable Soft Robots Assembled from Bistable Auxetic Building Blocks
Advanced Intelligent Systems, Volume 7, Issue 4, April 2025.Bistable and multistable structures offer solutions for enhancing shape retention and load capacity in soft robots. This study presents a multistable soft robot design using bistable auxetic building blocks. Illustrated through a manipulator with 216 discrete stable states and a tube‐crawling robot, the design demonstrates significant versatility and ...
Bojian Zhang +6 more
wiley +1 more source