Results 21 to 30 of about 464 (128)
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 the Energy-Momentum Tensor: Some Basic Facts [PDF]
, 2006 It has been pointed by Hall et al. [1] that matter collinations can be defined by using three different methods. But there arises the question of whether one studies matter collineations by using the ${\cal L}_\xi T_{ab}=0$, or ${\cal L}_\xi T^{ab}=0$ or
E. Noether +9 more
core +3 more sources
PROPER CURVATURE COLLINEATIONS IN KANTOWSKI–SACHS AND BIANCHI TYPE III SPACETIMES [PDF]
Modern Physics Letters A, 2007 A study of Kantowski–Sachs and Bianchi type III spacetimes according to their proper curvature collineations is given by using the rank of the 6×6 Riemann matrix and direct integration techniques. It is shown that when the above spacetimes admit proper curvature collineations, they form an infinite dimensional vector space.
Shabbir, Ghulam, Mehmood, Abu Bakar
openaire +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
symmetries of the Ricci tensor of static space times with maximal symmetric transverse spaces
, 2006 Static space times with maximal symmetric transverse spaces are classified according to their Ricci collineations. These are investigated for non-degenerate Ricci tensor ($det.(R_{\alpha}) \neq 0$).
A.Z. Petro +4 more
core +2 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
Autonomous three dimensional Newtonian systems which admit Lie and Noether point symmetries
, 2012 We determine the autonomous three dimensional Newtonian systems which admit Lie point symmetries and the three dimensional autonomous Newtonian Hamiltonian systems, which admit Noether point symmetries.
Andronikos Paliathanasis +10 more
core +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
Spacelike Ricci Inheritance Vectors in a Model of String Cloud and String Fluid Stress Tensor
, 2005 We study the consequences of the existence of spacelike Ricci inheritance vectors (SpRIVs) parallel to $x^a$ for model of string cloud and string fluid stress tensor in the context of general relativity.
Carot J +9 more
core +1 more source