Results 111 to 120 of about 26,635,104 (298)

Propagation and fluxes of ultra-high energy cosmic rays in $$\varvec{f(R)}$$ f ( R ) gravity theory

European Physical Journal C: Particles and Fields
In this work, we study the effect of diffusion of ultra-high energy cosmic ray (UHECR) protons in the presence of turbulent magnetic fields (TMFs) in the light of the f(R) theory of gravity.
Swaraj Pratim Sarmah, Umananda Dev Goswami   +1 more
doaj   +1 more source

Higher-dimensional inhomogeneous perfect fluid collapse in f(R) gravity

European Physical Journal C: Particles and Fields, 2017
This paper is about the $$n+2$$ n + 2 -dimensional gravitational contraction of an inhomogeneous fluid without heat flux in the framework of a f(R) metric theory of gravity.
G. Abbas, M. S. Khan, Zahid Ahmad, M. Zubair   +3 more
doaj   +1 more source

Aspects of axion F(R) gravity

, 2020
We provide a compact review on recent developments on axion F(R) gravity. The axion field is a string-theory–originated theoretical particle that is a perfect candidate for low-mass particle dark matter.
Oikonomou, Vasilis K., S. D. Odintsov, V. K. Oikonomou, Odintsov, Sergei D.   +3 more
core   +1 more source

UCST‐Driven Shape Morphing in Digital Light Processing 4D‐Printed Hydrogels

Advanced Materials Technologies, EarlyView.
A DLP‐printable UCST hydrogel based on poly(acrylic acid‐co‐acrylamide) enables reversible thermally induced expansion and 4D shape morphing. Rational control of composition, porosity, and multimaterial architecture enables predictable 4D shape morphing through differential swelling and localized actuation, opening new opportunities for high‐resolution
Fato Niang, Vincent Lapinte, Sebastien Blanquer   +2 more
wiley   +1 more source

A comparative study of wormhole geometries under two different modified gravity formalism

European Physical Journal C: Particles and Fields
In the current article, we discuss the wormhole geometries in two different gravity theories, namely $$\texttt{F}(\texttt{Q, T})$$ F ( Q , T ) gravity and $$\texttt{F}(\texttt{R, T})$$ F ( R , T ) gravity.
Sweeti Kiroriwal, Jitendra Kumar, S. K. Maurya, Sourav Chaudhary   +3 more
doaj   +1 more source

Some exact relativistic star solutions in f(R) gravity

We present a covariant description of non-vacuum static spherically symmetric spacetimes in f(R) gravity applying the (1+1+2) covariant formalism.
Naidu N. F., Dunsby P. K. S., Campbell M., Carloni S.   +3 more
core   +1 more source

A Review of Stable, Traversable Wormholes in f(R) Gravity Theories

Symmetry
It has been proven that in standard Einstein gravity, exotic matter (i.e., matter violating the pointwise and averaged Weak and Null Energy Conditions) is required to stabilize traversable wormholes. Quantum field theory permits these violations due to the quantum coherent effects found in any quantum field.
Ramesh Radhakrishnan, Patrick Brown, Jacob Matulevich, Eric Davis, Delaram Mirfendereski, Gerald B. Cleaver   +5 more
openaire   +2 more sources

Identifying Physical Interactions in Contact‐Based Robot Manipulation for Learning from Demonstration

Advanced Robotics Research, EarlyView.
Robots can learn manipulation tasks from human demonstrations. This work proposes a versatile method to identify the physical interactions that occur in a demonstration, such as sequences of different contacts and interactions with mechanical constraints.
Alex Harm Gert‐Jan Overbeek, Herman van der Kooij, Douwe Dresscher, Mark Vlutters   +3 more
wiley   +1 more source

Notes on f(R) Theories of Gravity

, 2014
In this review paper we present some basic notions about f(R) theories of gravity and some simple cosmological models derived from it. We first make an introduction to General Relativity (GR), followed by the discussion of Gibbons-York-Hawking boundary term in GR.
openaire   +2 more sources

Asymmetry in Skipping Enhances Viability Against Control Input Noise

Advanced Robotics Research, EarlyView.
Quadruped animals use asymmetric galloping gaits at high speeds, yet the functional role of this asymmetry remains unclear. This study shows that left–right asymmetry in touchdown angles enhances robustness to control noise. Using a simple two‐legged locomotion model and viability theory, it demonstrates that asymmetric skipping substantially enlarges ...
Yuichi Ambe, Alvin So, Shinya Aoi
wiley   +1 more source