Results 21 to 30 of about 103 (82)
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
Journal of Mathematics, Volume 2026, Issue 1, 2026.This article explores the necessary and sufficient conditions for a vector field on the cotangent bundle of a Riemannian manifold to qualify as an m− modified conformal vector field or a Ricci bi‐conformal vector field. The analysis employs an adapted frame and concerns the Riemannian extension metric.
Lokman Bilen +3 more
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
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On Quasi‐Hermitian Varieties in Even Characteristic and Related Orthogonal Arrays
Journal of Combinatorial Designs, Volume 33, Issue 3, Page 109-122, March 2025.ABSTRACT In this article, we study the BM quasi‐Hermitian varieties, laying in the three‐dimensional Desarguesian projective space of even order. After a brief investigation of their combinatorial properties, we first show that all of these varieties are projectively equivalent, exhibiting a behavior which is strikingly different from what happens in ...
Angela Aguglia +3 more
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Conformal Vector Fields on Doubly Warped Product Manifolds and Applications
Advances in Mathematical Physics, Volume 2016, Issue 1, 2016., 2016 This article aimed to study and explore conformal vector fields on doubly warped product manifolds as well as on doubly warped spacetime. Then we derive sufficient conditions for matter and Ricci collineations on doubly warped product manifolds. A special attention is paid to concurrent vector fields.
H. K. El-Sayied +3 more
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2‐Conformal Vector Fields on the Model Sol Space and Hyperbolic Ricci Solitons
Journal of Mathematics, Volume 2025, Issue 1, 2025.In this study, we present the notion of 2‐conformal vector fields on Riemannian and semi‐Riemannian manifolds, which are an extension of Killing and conformal vector fields. Next, we provide suitable vector fields in Sol space that are 2‐conformal. A few implications of 2‐conformal vector fields in hyperbolic Ricci solitons are investigated.
Rawan Bossly +3 more
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Paracomplex Paracontact Pseudo‐Riemannian Submersions
Geometry, Volume 2014, Issue 1, 2014., 2014 We introduce the notion of paracomplex paracontact pseudo‐Riemannian submersions from almost para‐Hermitian manifolds onto almost paracontact metric manifolds. We discuss the transference of structures on total manifolds and base manifolds and provide some examples.
S. S. Shukla +2 more
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International Journal of Scientific Research in Science and Technology, 2020 The present communication has been devoted to the study of projective motion, projective curvature collineation and infinitesimal projective transformation in a Finsler space equipped with semi-symmetric connection. In this communication we have derived results in the form of theorems which hold when the Finsler space under consideration admits both ...
S. K. Tiwari, Ved Mani
openaire +1 more source
Complexity of Self-Gravitating Systems. [PDF]
Entropy (Basel), 2021 Herrera L.
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